The objective of this study was the evaluation of the genetic diversity found in HBV circulating among Venezuelan Amerindians and the general population in Colombia. Phylogenetic analysis of the S region in 194 isolates showed that genotype F is highly predominant in Colombia and Venezuela. This might be related to the genetic background of the population. F3 is the main subgenotype which circulates in both countries. Phylogenetic analysis of 61 complete genome sequences of HBV American genotypes confirms the presence of two genotypes F and H, and 4 F subgenotypes. In Venezuela, subgenotypes F1, F2, and F3 circulate in East and West Amerindians, while only F3 was found among South Amerindians. Japreira community derived from Yucpa Amerindians around 150 years ago. However, several Japreira HBV sequences were forming a clade that can be classified as subgenotype 2b, differing from Yucpa sequences that belong mainly to subgenotype F3. The apparent absence of correlation between the phylogenetic groupings of HBV isolates with the ethnical origin in aboriginal populations might be suggesting a recent origin of HBV American subgenotypes, or a genetic drift effect.

We propose a steady-state kinetic model for the squid Na⁺/Ca²⁺exchanger that differs from other current models of regulationin that it takes into account, within a single kinetic scheme,all ionic [intracellular Ca²⁺ (Ca_i²⁺)-intracellular Na⁺ (Na_i⁺)-intracellularH_i⁺] and metabolic (ATP) regulations of the exchanger in whichthe Ca_i²⁺-regulatory pathway plays the central role in regulation.Although the integrated ionic-metabolic model predicts all squidsteady-state experimental data on exchange regulation, a criticaltest for the validity of it is the predicted dual effect ofNa_i⁺ on steady-state Ca²⁺ influx through the exchanger. To testthis prediction, an improved technique for the estimation ofisotope fluxes in squid axons was developed, which allows sequentialmeasurements of ion influx and effluxes. With this method, wereport here two novel observations of the squid axon Na⁺/Ca²⁺exchanger. First, at intracellular pH (7.0) and in the absenceof MgATP, Na_i⁺ has a dual effect on Ca²⁺ influx: inhibitionat low concentrations followed by stimulation at high Na_i⁺ concentrations,reaching levels higher than those seen without Na_i⁺. Second,in the presence of MgATP, the biphasic response to Na_i⁺ disappearsand is replaced by a sigmoid activation. Furthermore, the modelpredicts that Ca²⁺ efflux is monotonically inhibited by Na_i⁺,more pronouncedly without than with MgATP. These results arepredicted by the proposed kinetic model. Although not fullyapplicable to all exchangers, this scheme might provide someinsights on expected net Ca²⁺ movements in other tissues undera variety of intracellular ionic and metabolic conditions.

We have studied the effects of mitochondria poisoning by carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP) on Ca²⁺ signaling in enzymatically dissociated mouse flexor digitorum brevis (FDB) muscle fibers. We used Fura-2AM to measure resting [Ca²⁺]_i and MagFluo-4AM to measure Ca²⁺ transients. Exposure to FCCP (2 µM, 2 min) caused a continuous increase in [Ca²⁺]_i at a rate of 0.60 nM/s and a drastic reduction of electrically elicited Ca²⁺ transients without much effect on their decay phase. Half of the maximal effect occurred at [Ca²⁺]_i?=?220 nM. This effect was partially reversible after long recuperation and was not diminished by Tiron, a reactive oxygen species (ROS) scavenger. FCCP had no effects on fiber excitability as shown by the generation of action potentials. 4CmC, an agonist of ryanodine receptors, induced a massive Ca²⁺ release. FCCP diminished the rate but not the amount of Ca²⁺ released, indicating that depletion of Ca²⁺ stores did not cause the decrease in Ca²⁺ transient amplitude. Ca²⁺ transient amplitude could also be diminished, but to a lesser degree, by increases in [Ca²⁺]_i induced by repetitive stimulation of fibers treated with ciclopiazonic acid. This suggests an important role for Ca²⁺ in the FCCP effect on transient amplitude.

We report the use of the fluorescent dye CalciumOrange-5N (CaOr-5N) as a specific mitochondria Ca²⁺ marker in enzymatically dissociated mouse FBD muscle fibers. Using laser scanning confocal microscopy and the dyes Mitotracker Green (MTG), di-8-ANEPPS and endoplasmic reticulum tracker green (ERTG), we determined the relative position of mitochondria, transverse tubules and sarcoplasmic reticulum in the sarcomere. Comparison with electron micrographies showed that mitochondria are mostly present at both sides of Z lines and near the triads located at the A-I band border. CaOr-5N fluorescence was mainly distributed in mitochondria, highly co-localised with MTG and basically excluded from the A band space. ERTG localised mostly between the two t-tubules present in each sarcomere. We studied the effect of the protonophore FCCP using CaOr-5N to measure mitochondrial Ca²⁺ and JC-1 dye to measure mitochondria inner membrane potential (?? _m). After FCCP treatment, the CaOr-5N fluorescence diminished by about 33% in 80 s, while JC-1 fluorescence diminished by 36% in 200 s. Our results show the loss of Ca²⁺ from mitochondria when ??_m is depolarised and demonstrate the usefulness of CaOr-5N to mark mitochondrial [Ca²⁺]_m.

Zeolites FAU, EMT and their intergrowths were synthesized using 15-crown-5, 18-crown-6 and their equimolar mixture, respectively. The synthesized products were characterized by XRD, SEM-EDX, N2 adsorption and TPD-NH₃. The solids obtained were all highly crystalline. The FAU samples were formed by octahedral submicrometric crystallites, EMT samples had hexagonal plate morphology of 2—5 µ m. The intergrowth crystals were micrometric hexagonal plates through whose hexagonal faces, the octahedral FAU crystallites intergrow. The intergrowth proportion was evaluated by means of DIFFaX, resulting in different intergrowth proportions, depending on the molar ratio of template/Al₂O₃ and on the relative template proportion used in the synthesis gel. For a template/ Al₂O₃ ratio of 0.70, a 50%FAU/50%EMT intergrowth proportion was obtained, with cluster-type stacking and for template/ Al₂O₃ of 0.30 the intergrowth proportion was 12%FAU/88%EMT with two stacking arrangements: clusters and random. Platinum was incorporated to these zeolites and their intergrowths by solid ion exchange; the metal dispersion was evaluated by TEM. For most catalysts the platinum particles were between 4 and 10 nm. All the catalysts were active for n -pentane conversion. The activity was found to be a function of acidity. The intergrowth catalysts were the most active materials. The iso -pentane selectivity, at 350 ? C and carrier gas composition of H₂:N₂ = 2:1, was 82% independent of time on stream, acidity, Pt/Al ratio and Pt dispersion. The selectivity increased with decreasing temperature and as carrier gas composition became richer in H₂. The catalytic remaining activity (at 10 min) decreased in the following order: FAU>EMT> intergrowth.

Active catalysts for the water - gas shift (WGS, CO + H₂O –> H₂ + CO₂) reaction were synthesized from nickel molybdates ( ß -NiMoO₄ and nH₂O • NiMoO₄) as precursors, and their structural transformations were monitored using in situ time-resolved X-ray diffraction and X-ray absorption near-edge spectroscopy. In general, the nickel molybdates were not stable and underwent partial reduction in the presence of CO or CO/H₂O mixtures at high temperatures. The interaction of ß -NiMoO₄ with the WGS reactants at 500 ° C led to the formation of a mixture of Ni ( ~ 24 nm particle size) and MoO₂ ( ~ 10 nm particle size). These Ni - MoO₂ systems displayed good catalytic activity at 350, 400, and 500 ° C. At 350 and 400 ° C, catalytic tests revealed that the Ni - MoO₂ system was much more active than isolated Ni (some activity) or isolated MoO₂ (negligible activity). Thus, cooperative interactions between the admetal and oxide support were probably responsible for the high WGS activity of Ni - MoO₂. In a second synthetic approach, the NiMoO₄ hydrate was reduced to a mixture of metallic Ni, NiO, and amorphous molybdenum oxide by direct reaction with H2 gas at 350 ° C. In the first pass of the water - gas shift reaction, MoO₂ appeared gradually at 500 ° C with a concurrent increase of the catalytic activity. For these catalysts, the particle size of Ni ( ~ 4 nm) was much smaller than that of the MoO₂ ( ~ 13 nm). These systems were found to be much more active WGS catalysts than Cu - MoO₂, which in turn is superior to commercial low-temperature Cu - ZnO catalysts.

In thiswork it is studied the effect of the type of precursor (sulfate vs. nitrate of promotor) and the synthesis method (conventional vs. carbothermal carbiding) on the thiophene hydrodesulfurization (HDS) activity of activated carbon supported Fe-Mo, Co-Mo and Ni-Mo carbides. Catalytic precursors were prepared by co-impregnation of the support with solutions of ammonium heptamolybdate and the promotor salt. Conventional carbiding consists of a temperature-programmed treatment under a CH₄/H₂ (1:4) atmosphere, while the carbothermal method employs pure H₂. The passivated carbided solids were characterized by XRD and XPS. The presence of metals and Fe₃Mo₃C or M₆Mo₆C₂ phases (M =Co or Ni) in samples from sulfate precursors and of ß -Mo₂C and metals in those from nitrate precursors was verified by XRD, whereas XPS showed the presence at the surface of Mo ^{d +} (0 = d = 2), Mo⁴+, Mo⁶⁺, Fe³⁺, Co²⁺, Ni⁰ and Ni²⁺ species. The bimetallic carbides obtained from sulfate precursors retained sulfur on the surface, as shown by signals in the S 2p region, at 169 and 162 eV, assigned to S^{2 -} and SO₄^{2 -} , respectively. Prior to the catalytic reaction, the passivated carburized forms of carbon supported catalysts were presulfided in situ . The catalytic activity of carbides was strongly influenced by the type of precursor and slightly by the synthesis method. The activity of carbides obtained by the carbothermal method and with sulfate precursors was greater than that of the solids obtained by the conventional method and with nitrate precursors. The carbides obtained from nitrates showed increased catalytic activity when presulfided, suggesting that the carbides with sulfided surfaces or mixed carbo-sulfide species could be the active phase in HDS on carbide catalysts. The catalysts derived from sulfates showed higher activity than those obtained from nitrates, even without presulfiding, suggesting that sulfide from the precursor sulfate results in more active species than those obtained after presulfiding.

The discovery of Tobacco mosaic virus (TMV) at the end of the 19th century by the pioneers Adolph Mayer, Dmitrii Iwanowsky and Martinus Beijerinck marked the beginning of the science of virology. Since then, TMV was extensively used as a model for the development of viral disease diagnosis methods, from bioassays on indicator test plants, electron microscopy observation and serology tests, to the development of cDNA probes, and the typing of pathotypes in single mixed-infected plant by RT-PCR. In the near future, it is anticipated that improved tests developed from current PCR/probe systems, and from DNA chip technology, will greatly enhance TMV diagnosis process, such as plant quarantine service and molecular monitoring of the environment for virus and genetically modified plants containing virus-derived genes. In this chapter, current knowledge of TMV, with particular emphasis on recent progress on molecular diagnosis and its application to disease management has been discussed.

El agotamiento de las reservas mundiales de hidrocarburos fósiles pronosticado para el presente siglo, hará necesario la implementación de tres alternativas: 1) uso de bio-combustibles, 2) energía solar a través de celdas fotovoltaicas, y 3) energía nuclear y otras. Aunque el uso de los bio-combustibles es la alternativa más cercana, no debe tomarse como definitiva, ya que puede atentar contra el suministro de alimentos para el ser humano. Los bio-combustibles pueden mejor considerarse como un vehículo de transición entre la era de los combustibles fósiles y la era de las nuevas alternativas energéticas.

The exhaustion of the world fossil hydrocarbon reserves predicted for the present century will make it necessary to implement three emergent alternatives: 1) the use of bio-fuels, 2) solar energy through photovoltaic cells, and 3) nuclear energy and others Although the use of bio-fuels is the nearest alternative, it should not be taken as definitive, because it can upset human food supply. Bio-fuels could be better considered as a transition vehicle between the fossil fuel age and the age of new energy alternatives.

Neurodegeneration in Alzheimer’s disease (AD) has been linked to intracellular accumulation of misfolded proteins and dysregulation of intracellular Ca²⁺. In the current work, we determined the contribution of specific Ca²⁺ pathways to an alteration in Ca²⁺ homeostasis in primary cortical neurons from an adult triple transgenic (3xTg-AD) mouse model of AD that exhibits intraneuronal accumulation of ß-amyloid proteins. Resting free Ca²⁺ concentration ([Ca²⁺]_i), as measured with Ca²⁺-selective microelectrodes, was greatly elevated in neurons from 3xTg-AD and APP_SWE mouse strains when compared with their respective non-transgenic neurons, while there was no alteration in the resting membrane potential. In the absence of the extracellular Ca²⁺, the [Ca²⁺]_i returned to near normal levels in 3xTg-AD neurons, demonstrating that extracellular Ca²⁺contributed to elevated [Ca²⁺]_i. Application of nifedipine, or a non-L-type channel blocker, SKF-96365, partially reduced [Ca²⁺]_i. Blocking the ryanodine receptors, with ryanodine or FLA-365 had no effect, suggesting that these channels do not contribute to the elevated [Ca²⁺]_i. Conversely, inhibition of inositol trisphosphate receptors with xestospongin C produced a partial reduction in [Ca²⁺]_i. These results demonstrate that an elevation in resting [Ca²⁺]_i, contributed by aberrant Ca²⁺entry and release pathways, should be considered a major component of the abnormal Ca²⁺ homeostasis associated with AD.

The semi-diurnal tidal regime (mayor o igual 2 m) in the Paria Gulf on the Atlantic coastof Venezuela, and the flat landscape of the region, allow the penetration for tens of km of marine waters into the rivers draining thenortheastern coastal plain of the country. The levels of salinity, tidal flooding, and sedimentation decrease perpendicularly from theriver channel toward the back swamps. The vegetation varies sequentially from fringe mangroves along the river margins, to back swampscontaining forests dominated by Pterocarpus officinalis, herbaceous communities of Lagenocarpus guianensis, and palm swamps with Mauritiaflexuosa, Chrysobalanus icaco, and Tabebuia spp. This environmental structure was used to test the hypotheses that: (a) mangrovedistribution is strongly associated with salinity of interstitial water, and (b) they occupy areas where tidal influence and sedimentdynamics determine a relatively open N cycle. Analyses of soil, water, and plants along a 1.5 km transect located near the confluence ofthe Guanoco and San Juan Rivers (Sucre and Monagas States, Venezuela) revealed that: (a) conductivity decreased from 11 to 0.2 mmhos cm^-1from the river fringe to the internal swamp, whereas Na in the same stretch decreased from 100 to 2 µM; (b) average leaf tissueconcentrations of Na, P, and N decreased significantly along the transect; (c) P. officinalis showed a large Na-exclusion capacityindicated by positive K/Na ratios from 8 to 200, and Crinum erubescens counteracted Na by accumulating K above 1,000 mmol kg^-1;(d) leaves varied widely in ¹³C (-25.5 to -32‰) and (d ¹⁵N (4 to -10.5‰) values. Samples wereaggregated according to soil carbon content corresponding to those of the mangrove forest belt (5–28 mol C kg^-1; 0–650 from river fringe)and those of the back swamps (40–44 mol C kg^-1; 700–1,500 m from river fringe). The concentrations of Na, P, and N (in mmol kg^-1)and d ¹⁵N values (in ‰) were significantly higher in the mangrove forest compared to the back swamp (Na 213 vs. 88; P 41 vs. 16; N 1,535 vs. 727; d ¹⁵N 1.5 vs. -3.7), indicating that the fringe forest was not nutrient limited. These results support the hypotheses that mangroves are restricted to the more-saline sections of the transect, and that the fringe forest has a more open N cycle,favoring ¹⁵N accumulation within the system.

The genetic variation of papaya ringspot virus (PRSV) in Venezuela was estimated by single strand conformation and nucleotide sequence analyses of two genomic regions of twenty-six isolates. These analyses showed that mutation, virus movement, selection, mixed infections and recombination contributed to shape the genetic variation observed. Phylogenetic analysis indicated that Venezuelan isolates were within a clade composed of isolates from the Americas and Australia. The genetic diversity of these isolates was sufficiently large that it must be taken into account when designing control strategies such as transgenic resistance and cross-protection.

ABSTRACT: Upon comparative analysis, the satyrine genera Parapedaliodes Forster and Neopedaliodes Viloria, L. D. Miller & J. Y. Miller are reassessed, redefined and revised. There are a few fundamental morphological homologies between these two genera. Two species and six subspecies of Neopedaliodes are described as new: N. lafebreae y N. michaeli , new species ; N. juba jubilosa, N. margaretha allyni, N. michaeli critica, N. michaeli innupta, N. nora stepheni, and N. proculeja malaga new subspecies . One new combination is established. Synonymies and descriptions are accompanied by brief bionomical comments on each taxon and data on its distribution.

RESUMEN: Después de un análisis comparativo se reevalúan, redefinen y revisan los géneros de mariposas satirinas Parapedaliodes Forster and Neopedaliodes Viloria, L. D. Miller & J. Y. Miller. Entre ambos géneros existe pocas homologías morfológicas fundamentales. Se describen como nuevas dos especies y seis subespecies de Neopedaliodes : N. lafebreae y N. michaeli , especies nuevas; N. juba jubilosa, N. margaretha allyni, N. michaeli critica, N. michaeli innupta, N. nora stepheni, and N. proculeja malaga subespecies nuevas. Se establece una nueva combinación. Se acompañan las sinonimias y descripciones de cada taxón con comentarios bionómicos breves y datos sobre su distribución.

The aggregation of patients with Huntington's disease (HD) around Lake Maracaibo, Zulia State, Venezuela, is widely recognized, but the epidemiology of HD in the whole country is relatively unstudied. We have examined 279 individuals from 60 unrelated affected families residing in various areas of Venezuela for the presence of CAG repeats and other features associated with HD. The number of expanded repeats in 139 carriers varied from 35 to 112. Based on our examination of 71 symptomatic individuals, we developed a log-transformed regression equation, y = -0.0238x + 2.6616, to enable the prediction of age of onset in asymptomatic carriers. Intragenic haplotypes were constructed with two VNTRs (variable number of tandem repeats) and two SNPs (single nucleotide polymorphisms) in the promoter region as well as CCG repeat and ?2642 polymorphisms to assess kinship between families. In 43 of 45 tested families, the haplotype on the mutated chromosome was 1;G;C;7;(A). The other haplotypes observed, 1;G;C;7;(B) and 4;G;C;7;(A), were of Peruvian and French origins, respectively. The geographic source of the first affected ancestor was assessed in 54 families from 15 different states. Residents of the states of Miranda, Lara and Táchira, excluding those of Zulia, had a mutated allele prevalence five- to ninefold higher than that of other areas. A low (approx. 1/200,000) prevalence, a wide-spread distribution with aggregation in some states and a likely remote European Caucasoid origin are defining epidemiologic features of HD in Venezuela.

An MFI type galosilicate was synthesized and characterized employing XRD, N₂ adsorption at -196 °C, chemical analysis by ICP-AES, and XPS. This material was used in the preparation of Pd/H[Ga]ZSM5 and Pt/H[Ga]ZSM5 bifunctional catalysts, calcined under dry air for 6 h at 500 and 300 °C, respectively, and then reduced “in situ” under H₂ flow for 6 h at 500 °C. The bifunctional catalysts were also characterized by XRD, N₂ physisorption, TEM, chemical analysis, and XPS. The support possesses an MFI structure with excellent crystallinity, as shown by XRD. Bulk chemical analysis shows a (Si/Ga)_ICP-AES atomic ratio of 16. The absence of Ga₂O₃ is suggested by both XRD and XPS (at surface level). The atomic ratio at the surface, (Si/Ga)_XPS, is the same as that found by ICP-AES, suggesting that Ga is distributed homogeneously. XRD and N₂ physisorption results of the bifunctional catalysts suggest that metal incorporation does not affect sensibly the structure of the support. Dispersion of Pd and Pt in either catalyst was estimated from TEM analysis, indicating in both cases values of the order of 80%. The atomic ratios (Si/Ga)_XPS at the surface were 16 for Pd/Galosilicate, and 4 for Pt/Galosilicate, suggesting that Pt promotes migration of Ga towards the external surface of the solid, a phenomenon that is not observed for the Pd/H[Ga]ZSM5 catalyst. Degaliation promoted by Pt could be explained assuming that Pt and Ga could form stable chemical species, as might be indicated by XPS results. The transformation of acetone to MIBK was employed as catalytic test. These results indicate very different behaviors for either bifunctional catalyst.

Solids of the MCM-41 type (BET specific surface area around 600 m²/g), with only Si and with Si/Al (atomic ratio) = 25, were synthesized and employed as supports of dodecatungstophosphoric acid (HPW)-based catalysts. Catalysts were prepared by impregnation of HPW, in amounts of 20, 40 and 60 wt%. Characterization by DTA, TGA, XRD, FT-IR and NH₃-TPD suggest an interaction of HPW with the supports. This interaction in the HPW/MCM-41 (Si) catalysts leads to a higher thermal stability of the Keggin structure of HPW and thus a preservation of its acidic protons. This effect is reflected in a higher density of acid sites upon increasing HPW loading. Powder XRD patterns of catalysts and the steady loss of specific surface area in both supports are consistent with a uniform distribution of the supported HPW. Analysis by FT-IR of the supported catalysts shows a displacement of the W—O—W band of supported HPW as compared with pure HPW. This displacement decreases with increasing loading, being higher for 20% HPW/(Si/Al). The catalytic activity in the alkylation of toluene with 1-dodecene increases in the following sequence: 20% HPW/(Si/Al) %26lt; 40% HPW/(Si/Al) %26lt; 20% HPW/(Si) %26lt; 60% HPW/(Si/Al) %26lt; 40% HPW/(Si) %26lt; 60% HPW/(Si), which is directly related to the acid site density. The conversions and selectivities towards monoalkylated products for HPW/MCM-41 (Si) catalysts are higher than those for HPW/MCM-41 (Si/Al). The 60% HPW/MCM-41 (Si) catalysts presents the higher selectivity to monoalkylated products and the higher thermal stability, while for 20% HPW/MCM-41 (Si/Al) no catalytic activity was observed

Abstract The aggregation of patients with Huntington's disease (HD) around Lake Maracaibo, Zulia State, Venezuela, is widely recognized, but the epidemiology of HD in the whole country is relatively unstudied. We have examined 279 individuals from 60 unrelated affected families residing in various areas of Venezuela for the presence of CAG repeats and other features associated with HD. The number of expanded repeats in 139 carriers varied from 35 to 112. Based on our examination of 71 symptomatic individuals, we developed a log-transformed regression equation, y = -0.0238x + 2.6616, to enable the prediction of age of onset in asymptomatic carriers. Intragenic haplotypes were constructed with two VNTRs (variable number of tandem repeats) and two SNPs (single nucleotide polymorphisms) in the promoter region as well as CCG repeat and ?2642 polymorphisms to assess kinship between families. In 43 of 45 tested families, the haplotype on the mutated chromosome was 1;G;C;7;(A). The other haplotypes observed, 1;G;C;7;(B) and 4;G;C;7;(A), were of Peruvian and French origins, respectively. The geographic source of the first affected ancestor was assessed in 54 families from 15 different states. Residents of the states of Miranda, Lara and Táchira, excluding those of Zulia, had a mutated allele prevalence five- to ninefold higher than that of other areas. A low (approx. 1/200,000) prevalence, a wide-spread distribution with aggregation in some states and a likely remote European Caucasoid origin are defining epidemiologic features of HD in Venezuela

The dimeric complex dioxo (-oxo) thiocyanato of molybdenum(VI) bearing a 4,4-di-ter-butyl-2,2-bipyridine ligand in trans conformation (complex 1) has been used in catalytic reactions of olefins (ethylene) oxidation, giving as intermediate a dimeric complex oxo bis (-oxo) thiocyanato of molybdenum(V) in cis conformation (complex 2). Binding and electronic properties were calculated using the parametric quantum chemistry method for catalytic reactions, CATIVIC. The interaction of an ethylene molecule with complex 3 (cis version of complex 1) leads to the formation of the intermediate named complex 4. This complex is dissociated to form complex 5 plus ethylene oxide. Changes of electronic and bonding properties are analyzed in terms of atomic charge, orbital population, total binding energies, diatomic bond energies, diatomic energies, and Wiberg indexes, and equilibrium bond distances. The energy balance for the complete catalytic process is presented in a schematic way. Results confirm the extraordinary oxo-transfer abilities of this complex, considering that the whole process is exothermic (-44 kcal/mol). Regeneration of the catalyst is also calculated by the interaction of H₂O₂ with complex 5.

Neuropathic pain is a major clinical problem, and several animal models have been developed to investigate its mechanisms and its treatment. In this report, the role of the rostral ventromedial medulla (RVM) in the early events of the chronic constriction injury (CCI) model was investigated in behavioral and electrophysiological experiments. Placing the 4 CCI ligatures around the sciatic nerve induced large discharges and residual ongoing activity in spinal nociceptive neurons. Two weeks after CCI ligation, the rats showed behavioral hyperalgesia and allodynia as well as increased ongoing activity and responsiveness of spinal nociceptive neurons to innocuous and noxious stimuli. Blockade of excitatory synapses in the RVM by a kynurenate microinjection (2 nmol in 0.5 µL) 5 minutes before placement of the sciatic ligatures had no immediate effect on spinal neuronal activity but largely prevented the activation of spinal neurons. In kynurenate microinjected rats, behavioral hyperalgesia and allodynia developed slowly and incompletely, which corresponded with an incompletely developed hyperexcitability of spinal neurons. To the best of our knowledge, these results show for the first time that the initial response to nerve damage requires facilitation from the RVM

Perspective: The present and previous findings indicate that descending facilitation from brainstem nuclei critically contributes to the spinal hyperexcitability that underlies neuropathic pain. The present results indicate that this contribution begins at the very moment the nerve is damaged and should be prevented and treated accordingly.

The transformations of 5-methoxy, 6-methoxy and 7-methoxy-a-tetralones are described. Studies on the synthesis of diterpenes veadeiroic acid 12, triptolide 18, sesquiterpenes biflorin 25, mansonone F 26, cacalol 39 and a potential intermediate for 11-deoxydaunomycinone 59 from 5-methoxy-a-tetralone 1 are discussed. Several intermediates for diterpenoid compounds and a total synthesis of phytoalexin orchinol 53 from 6-methoxy-a-tetralone 2 have been accomplished. 7-Methoxy-a-tetralone 3 has proved to be a suitable starting material for a simple and short synthesis of cadinene dihydrochloride 45

Rotavirus infection of cells in culture induces major changesin Ca²⁺ homeostasis. These changes include increases in plasmamembrane Ca²⁺ permeability, cytosolic Ca²⁺ concentration, andtotal cell Ca²⁺ content and a reduction in the amount of Ca²⁺released from intracellular pools sensitive to agonists. Variouslines of evidence suggest that the nonstructural glycoproteinNSP4 and possibly the major outer capsid glycoprotein VP7 areresponsible for these effects. In order to evaluate the functionalroles of NSP4 and other rotavirus proteins in the changes inCa²⁺ homeostasis observed in infected cells, the expressionsof NSP4, VP7, and VP4 were silenced using the short interferingRNA (siRNA) technique. The transfection of specific siRNAs resultedin a strong and specific reduction of the expression of NSP4,VP7, and VP4 and decreased the yield of new viral progeny bymore than 90%. Using fura-2 loaded cells, we observed that knockingdown the expression of NSP4 totally prevented the increase inCa²⁺ permeability of the plasma membrane and cytosolic Ca²⁺concentration measured in infected cells. A reduction in thelevels of VP7 expression partially reduced the effect of infectionon plasma membrane Ca²⁺ permeability and Ca²⁺ pools releasedby agonist (ATP). In addition, the increase of total Ca²⁺ content(as measured by ⁴⁵Ca²⁺ uptake) observed in infected cells wasreduced to the levels in mock-infected cells when NSP4 and VP7were silenced. Finally, when the expression of VP4 was silenced,none of the disturbances of Ca²⁺ homeostasis caused by rotavirusesin infected cells were affected. These data altogether indicatethat NSP4 is the main protein responsible for the changes inCa²⁺ homeostasis observed in rotavirus-infected cultured cells.Nevertheless, VP7 may contribute to these effects.

Water reservoirs formed by the leaf axils of bromeliads are a highly derived system for nutrient and water capture that also house a diverse fauna of invertebrate specialists. Here we investigate the origin and specificity of bromeliad-associated insects using Copelatinae diving beetles (Dytiscidae). This group is widely distributed in small water bodies throughout tropical forests, but a subset of species encountered in bromeliad tanks is strictly specialized to this habitat. An extensive molecular phylogenetic analysis of Neotropical Copelatinae places these bromeliadicolous species in at least three clades nested within other Copelatus . One lineage is morphologically distinct, and its origin was estimated to reach back to 12—23 million years ago, comparable to the age of the tank habitat itself. Species of this clade in the Atlantic rainforest of southern Brazil and mountain ranges of northern Venezuela and Trinidad show marked phylogeographical structure with up to 8% mtDNA divergence, possibly indicating allopatric speciation. The other two invasions of bromeliad water tanks are more recent, and haplotype distributions within species are best explained by recent expansion into newly formed habitat. Hence, bromeliad tanks create a second stratum of aquatic freshwater habitat independent of that on the ground but affected by parallel processes of species and population diversification at various temporal scales, possibly reflecting the paleoclimatic history of neotropical forests.

ABSTRACT:- Multiscale and multivariate analyses for assessing psittacine nesting susceptibility to predation: an example from yellow- shuldere parts (Amazona barbadensis).- Predation is the main natural factor reducing breeding success of the Amazona barbadensis population on Margarita Island (Venezuela). The objective of this study was to determine the nest characteristics most closely related to predation by conducting a multivariate analysis considering variables at different spatial scales. I expected that nests with higher entrances, deeper cavities, no branches below the entrance, and higher density of surrounding and canopy vegetation, would have lower rates. The following variables were considered at nest characteristics (entrance height, nest depth, height of the first branch under the nest entrance, canopy and horizontal cover), macrohabitat (patch size, patch shape complexity index), and landscape scales. (percentages and number of different kinds of vegetation in a circles of 100-m radius around the nest). Parrot nests (n = 51) were classified in different categories de pending on their predation rate during 10 years study (1990-1999). Principal component analyses (PCA) were done at different spatial scales and the ones showing specific trends were then analyzed with ANOVA, using principal component 1 as the dependent variable. Nests with the highest predation rates had lower entrances, lower branches under the entrance, and less canopy cover compared with nests with no predation. Also, they were in smaller vegetation patches, with smaller extension of riparian vegetation cover and more types of vegetation around them. The study suggests that, in this species, predation is affected by variables at larger spatial scale than those traditionally measured at the microhabitat level. The former should be

considered for nests management, either natural or artificial.

RESUMEN:- En la población de la Cotorra Cabeciamarilla. (Amazona Barbadensis) de la isla de Margarita (Venezuela), la depredación es el factor natural más importante en reducir el éxito reproductivo. El objetivo del trabajo fue encontrar las características de los nidos que están más relacionadas con la depredación, realizado el análisis a distintas escalas espaciales y en forma multivariada. Se esperaría que los nidos con entradas a mayor altura, más profundos, sin ramificaciones por debajo de la entrada del nido, mayor densidad de vegetación circundante y del dosel, fueran los que presentaran menor depredación. Se consideraron las siguientes variables a escalas de microhábitat (altura de la entrada, profundidad del nido, altura de la primera ramificación por debajo de la boca delnido, cobertura del dosel y horizontal). macrohábitat (área del parche e índice de complejidad de forma) y paisaje (porcentajes y números de distintos tipos de vegetación en radio de100 m alrededor del nido). Los nidos de cotorras(n = 51) se clasificaron en distintas categorías según las tasas de depredación que sufrieron en los 10 años de estudios (1990- 1999).Se realizaron análisis de componente principales a las distintas escalas espaciales y los que mostraron alguna tendencia fueron posteriormente analizados a través de ANOVA con el componente principal 1 como variable dependiente. Los nidos con altas tasas de depredación tuvieron entradas más bajas, ramificaciones por debajo de la boca a menores alturas y cobertura del dosel más escasa, con respecto a los nidos que no sufrieron depredación. Tambiénestuvieron en parche más pequeños, con menor cobertura de vegetación asociada a quebradas y mayor número de tipos de vegetación diferentes. El estudio sugiere que en esta especies la depredación está afectada por variables a escalas más grandes que las de microhábitat, y que, por lo tanto, deberían ser consideradas en el manejo de nidos tanto naturales como artificiales.

ABSTRACT:%26nbsp; A remarkable silvery Dalla is described and illustrated from high elevations in the Cerro Pintado, Sarranía de Valledupar, on the Venezuela-Colombian border, This species is apparently related to Dalla semiargentea (C. Felder %26amp; R. Felder, 1876), also redescribed and illustrated, of Colombia. The new species resembles the satyrine Lymanopoda paramera Adams %26amp; Bernard, 1979, with which it flies and apparently shares chusquea species as its larval foodplant.

The molecular characterization of partial- length genomic segment2 of porcine picobirnavirus (PBV) strains and the developmentof a specific reverse transcription-PCR (RT-PCR) assay for detectionof virus in feces are reported. Phylogenetic analysis indicatedthat the studied porcine isolates were more closely related(>85% identity) to human PBV belonging to genogroup I thanto the other porcine PBV described so far. Analysis by RT-PCRand polyacrylamide gel electrophoresis of fecal samples collectedin Venezuela and Argentina showed that PBV circulate at highfrequencies in piglets.

Neuropathic pain is a major clinical problem, and several animal models have been developed to investigate its mechanisms and its treatment. In this report, the role of the rostral ventromedial medulla (RVM) in the early events of the chronic constriction injury (CCI) model was investigated in behavioral and electrophysiological experiments. Placing the 4 CCI ligatures around the sciatic nerve induced large discharges and residual ongoing activity in spinal nociceptive neurons. Two weeks after CCI ligation, the rats showed behavioral hyperalgesia and allodynia as well as increased ongoing activity and responsiveness of spinal nociceptive neurons to innocuous and noxious stimuli. Blockade of excitatory synapses in the RVM by a kynurenate microinjection (2 nmol in 0.5 µL) 5 minutes before placement of the sciatic ligatures had no immediate effect on spinal neuronal activity but largely prevented the activation of spinal neurons. In kynurenate microinjected rats, behavioral hyperalgesia and allodynia developed slowly and incompletely, which corresponded with an incompletely developed hyperexcitability of spinal neurons. To the best of our knowledge, these results show for the first time that the initial response to nerve damage requires facilitation from the RVM.

Perspective

The present and previous findings indicate that descending facilitation from brainstem nuclei critically contributes to the spinal hyperexcitability that underlies neuropathic pain. The present results indicate that this contribution begins at the very moment the nerve is damaged and should be prevented and treated accordingly.

Many species of bats secrete a wide variety of substances, frequently associated with olfactory communication. We characterized a seasonal phenomenon of dorsal sebaceous secretion in the Curaçaoan long-nosed bat, Leptonycteris curasoae, in Venezuela, and the lesser long-nosed bat, Leptonycteris yerbabuenae, in Mexico. The phenology of the sebaceous patch was determined, a histological analysis of the affected area was conducted using specimens of L. curasoae from Venezuela, and finally, a preliminary chemical characterization of the substance secreted was performed combining histochemical techniques with gas chromatography and mass spectrometry analyses. The sebaceous patch was detected exclusively in male adult specimens. Individuals presenting it had a variable area of fur covered with a fatty and odoriferous substance at the level of the interscapular zone. Occurrence of the sebaceous patch was cyclical and coincided with the mating season in Venezuela and Mexico. The following histological changes associated with occurrence of the patch were observed: increase of epidermis thickness and decrease of dermis and hypodermis thicknesses, increase in density of sebaceous glands, increase of percentage of skin covered by sebaceous glands, increase of size of sebaceous glands previous to secretion followed, and increase of the sebum volume within sebaceous glands previous to secretion. Several compounds tentatively identified as fatty acids, cholestanes and cholesterol were present in the sebaceous secretion. Based on the evidence obtained, we hypothesize that the sebaceous patch could be involved in olfactory communication, possibly related to mating behavior in these bats

The asymmetric unit of the title compound, C17H16ClNO, contains two crystallographically independent molecules. These molecules are connected in an alternating fashion through N–H...O and C–H...O hydrogen bonds, generating one-dimensional chains of graph sets R¹₂(6) and C(4)along the a axis.

ABSTRACT: Coral is a material that recently has gained increased attention as a potential bone graft substitute material. The porosity and pore size distribution of the exoskeleton of eight different coral species were investigated by mercury intrusion and microscopy. A classification was established comprising two groups according to porosity: L-type, having low porosity (%26lt; 20 vol.%), and H-type, having high porosity (%26gt; 20 vol.%). According to literature, this value of 20 vol.% seems to be a lower porosity limit for successful surgical applications as bone graft substitution material. Pore size distributions are well-defined in three H-type species, each one having a different order of magnitude for the median pore diameter: Porites (order 2), Millepora (order 1), and Manicina (order 0). Tubular and slit pore geometries were suggested after microscopy

We have synthesized two naphthyl ester quinolone derivates and determined their ability to generate reactive oxygen species (ROS) such as ¹O₂, OH, H₂O₂ upon photolysis with UV-A light. The ability of cinoxacin ( 1 ) and nalidixic acid ( 2 ), and their naphthyl ester derivatives ( 3 and 4 ) to generate a dose-dependent amount of singlet oxygen and ROS (^-O₂, OH) in cell-free systems was detected by histidine assay and by luminol-enhanced chemiluminescence (LCL), respectively. Their electronic absorption and emission spectra were quantified and their photostability was determined. Their tendency to generate peroxidic derivative species showed the following order: 3 more than 4 ; in contrast, their ability to generate singlet oxygen was 4 more than 3 and these were better sensitizers than their parent quinolones 1 and 2 . The antibacterial activity in darkness and under irradiation of compounds 3 and 4 was tested on Escherichia coli and compared with that of their parent compounds. An enhanced antibacterial activity by irradiation of the naphthyl esters of cinoxacin and nalidixic acid on E. coli was observed.

El mundo está como un automóvil que quiere correr más quedándole poca gasolina en el tanque. Las reservas mundiales de petróleo “fácil”, aquel que fluye de los actuales pozos perforados en tierra o en aguas poco profundas, han llegado al tope y lo que queda es cada vez más costoso. El petróleo existente en zonas de difícil acceso y el gas natural “difícil” (gas atrapado e hidratos de metano) son de explotación muycostosa, más aún al evitar causar daños ambientales.

Los altos precios del petróleo son debidos en parte alta inversión necesaria para explotar nuevos yacimientos difíciles y para establecer nuevos procesos de producción de gasolina a partir de gas natural, basados en la casi olvidada tecnología Fischer-Tropsch, usada por los alemanes en la segunda guerra mundial para sintetizarla a partir de carbón mineral. Otra causa es la estrecha relación entre la industria petrolera y otra muy poderosa, la automotriz, en la que el rápido incremento de la oferta, por mejor producción en serie y reciclo de chatarra, aumenta la demanda de combustibles.

An attempt has been made to synthesise 2-acetyl-7,8-dimethoxy-1,2,3,4-tetrahydronaphthalene aiming at its transformation to intermediates for the synthesis of natural products

El skyrin es un producto natural proveniente de algunas especies botánicas (hongos) y es uno de los primeros agentes antidiabéticos no-peptídico de pequeño peso molecular. El objetivo de este estudio fue el de investigar la habilidad del skyrin en inhibir radicales libres y algunas especie oxigenadas reactivas como .OH, ¹O_2^, H₂O₂ generados en sistemas libres de células usando la quimioluminiscencia del isoluminol, luminol y espectroscopía de absorción como monitores. En los ensayos de quimioluminescencia del isoluminol (ILCE) en presencia de peroxidasa de rábano (HRP) y en los del luminol – H2O2 o ión férreo, fue observado una inhibición dependiente de la cantidad de skyrin adicionada a este medio. Por otro parte, el skyrin mostró una actividad secuestradora del galvanoxyl radical en soluciones etanólicas. En un experimento separado el skyrin fue capaz de atrapar oxígeno singlete (¹O₂) generado mediante la irradiación con luz visible de rosa de bengala. La actividad antioxidante del skyrin se comparó con otros antioxidantes conocidos como la emodina, dipiridamol y las vitaminas C y E en diferentes ensayos como también en peroxidación lipídica. Estos resultados sugieren que el skyrin atrapa especies reactivas de oxígeno y de radicales libres en grado similar que la emodina, vitamina C y E o al del dipiridamol.

The effect of salinity on leaf water relations, and rate and ionic composition of leaf secretion was investigated in plants of Avicennia germinans growing under controlled salinity conditions. Increases in salinity from 0 to 940 mol NaCl m^-3 reduced the predawn water potential from -0.56 to -4.16 MPa and the solute potential from -2.27 to -4.48 MPa, whereas the pressure potential remained positive in all treatments. Compared to the control, at 940 mol NaCl m^-3 Na⁺ and Cl^- concentrations of leaf sap increased 19 and 7 times, respectively. With the addition of salt the main ions accumulated in leaves were Na⁺ and Cl^- whereas plants grown without salt accumulated K⁺ in leaves at levels similar to those of Na⁺ with salt treatments. Secretion rates of Na⁺ and Cl^- ions increased up to the highest salinity treatment, amounting to 59 and 46 times respectively, compared to control plants. The increase in secretion rate contributed to counteract the increase of salt concentration in the leaf. In the treatments receiving salts, the Na⁺/K⁺ ratio of leaf sap ranged from 4 to 10, whereas that of the secretion ranged from 24 to 56. The ratio of Cl^- vs the rest of anions remained around 3 in the leaf sap of salt-treated plants whereas it varied between 96 and 243 in the secretion. With increasing salinity higher secretion rates maintained the internal ion leaf concentration relatively low. The selective character of the secretion contributes to maintain favourable Na⁺/K⁺ and Cl^-/anion ratios in the leaf cells

This work presents the preparation and characterization of three bifunctional catalysts consisting of palladium supported on H-[Ga]ZSM5 zeolite, with a Si/Ga atomic ratio of 16 and Pd contents of 0.09, 0.50 and 1.02 wt%. The lowest and highest Pd content solids, which were assessed by transmission electron microscopy (TEM), show dispersion of the supported phase of 90% and 73%, respectively. The XPS characterization studies of the catalysts allowed to detect the presence of framework, tetrahedral Ga species, Pd(0) aggregates and Pd(0) atomically dispersed. These solids were tested in the synthesis of methyl isobutyl ketone (MIBK) from acetone. The results confirm that the catalyst with 1.02 wt% Pd, shows an initial global activity about twice as higher as that of 0.09 wt%Pd/H-[Ga]ZSM5, and additionally the selectivity to MIBK of the former is four times higher. These results show that the catalyst with lower Pd content do not have a high number of active metallic sites to catalyze the hydrogenation of Mesityl oxide to MIBK, even though it showed an excellent dispersion, while the catalyst with 1.02 wt% Pd seems to be a catalyst with a proper balance of the acidic-hydrogenating functions

This article reviews the isolation, biological activity and syntheses of several diterpenes. The chemistry and biological activities of norditerpene dilactones have been described. The aim of the present article is to provide an overview on the important role of diterpenoid compounds in medicine and agriculture. The synthetic discussions of these diterpenes are very briefly described

Abstract: We recently demonstrated that rat cerebellar Type-1 astrocytes express a very active Na⁺/Ca²⁺ exchanger highly colocalized with ryanodine receptors (RyRs), which in turn play a key role in glutamate-induced Ca²⁺ signaling through a calcium-induced calcium release (CICR) mechanism. In this work we have explored whether the Na⁺/Ca²⁺ exchanger has any role in the Ca²⁺_i signal induced by hypo-osmotic stress in these cells, using microspectrofluorometric measurements with Fura-2, pharmacological tools, and confocal microscopy image analysis. We present evidence for the first time that the increase in [Ca²⁺]_i in rat cerebellar Type-1 astrocytes, resulting from moderate hypotonic shock, is mediated by Ca²⁺release from ryanodine-operated Ca²⁺_i stores, and that the magnitude of the intracellular Ca²⁺ signal induced by hypotonicity in the short term (up to 240 s) is small and controlled by the activity of the Na⁺/Ca²⁺ exchanger operating in its extrusion mode. With longer times in the hypotonic medium, intracellular Ca²⁺ store depletion leads to Ca²⁺ entry through store-operated Ca²⁺ channels. We found it interesting that the activity of the Na⁺/Ca²⁺ exchanger measured during this reverse mode operation (Ca²⁺ entry in exchange for internal Na⁺) was found to be greatly increased in hypotonic solutions and decreased in hypertonic ones. The buffering of the [Ca²⁺] _i rise induced by hypo-osmotic stress may prevent excessive increases in [Ca²⁺]_i, which otherwise might impair the normal function of this glial cell.

La ateroesclerosis y las patologías asociadas han emergido como la primera causa de morbimortalidad en el mundo occidental y son, por lo tanto, un gran problema de salud pública. Se ha sugerido que los radicales libres y las especies reactivas del oxígeno están involucradas en la fisiopatología de estas enfermedades. Se sabe que la actividad física tiene un gran papel como medida de salud pública al, entre otras cosas, disminuir en la población general el riesgo de eventos cardiovasculares relacionados con ateroesclerosis. Se conoce también que la actividad física aumenta en varios tejidos la producción de radicales libres y especies reactivas de oxígeno. En el presente texto se revisa la relación entre ateroesclerosis, estrés oxidativo y actividad física discutiendo la aparente paradoja según la cual la actividad física regular reduce la ateroesclerosis y el riesgo cardiovascular al mismo tiempo que se da un fenómeno aparentemente dañino como es el aumento del estrés oxidativo. Se presenta una hipótesis que incluye la evidencia experimental y clínica para explicar dicha paradoja.

Se estudió la anatomía foliar en 15 especies de plantas vasculares que crecen en la zona costera del estado Falcón (Venezuela), a fin de analizar las características con potencial valor adaptativo en suelos salinos. El material foliar colectado se fijó en FAA y posteriormente se efectuaron secciones transversales y macerados de la lámina. En la mayoría de las especies estudiadas el desarrollo de tejido acuífero en la epidermis y/o en el mesofilo es la principal característica asociada con el hábitat salino. Otros rasgos anatómicos de posible valor adaptativo son: presencia de tricomas, estomas protegidos por papilas, cristales en las células del mesofilo, estructuras secretoras y anatomía Kranz.

The leaf anatomy of 15 species of vascular plants occurring in coastal zones of the Falcon State (Venezuela) was studied to evaluate the potential adaptive value of leaf anatomical features to the saline environment. Transverse sections and macerates of leaf material preserved in FAA were prepared for microscopic analysis. Results show that the development of water storing tissue in the mesophyll and/or epidermal cells is the main characteristic associated with the saline habitat in these species. Other characteristics of potential adaptive value are: presence of trichomes, stomata protected by papillae, crystals in mesophyll cells, secretory tissues, and Kranz anatomy.

Para determinar su grado de halofitismo se analizó la composición mineral y de isótopos estables (13C y 15N) de 18 especies de plantas de comunidades costeras, y de los suelos asociados en tres localidades del estado Falcón,Venezuela, en la carretera Coro-La Vela (COVE); y la costa oriental (COP) y la bahía de Tacuato (TAC), ambas en Paraguaná. Los suelos de COP presentaron textura arenosa y valores menores de N, P, K y Na. Los suelos de TAC mostraron mayor salinidad (Na, Mg y Ca) y los de COVE tenían concentraciones mayores de N y P, y textura arcillosa. Las especies de COP tenían las mayores concentraciones de Na, y eran más suculentas (Sesuvium portulacastrum, S. edmondstonii, Batis maritima, Sarcocornia perennisy Heterostachys ritteriana). Chamaesyce mesembrianthemifoliay Croton punctatus tenían cocientes K/Na %26gt; 1 (no halófitas). Chamaesyce mesembrianthemifolia, Scaevola plumieri, Argusia gnaphalodes, Egletes prostrata, Suriana maritimay Gomphrena albiflora son concentradoras relativas de K. Las especies calciófobas acumulan la mayor parte del Ca como oxalato insoluble (Atriplex oestophora, G. albifloray Alternanthera halimifolia), o secuestrado como fosfatos y pectatos (Croton punctatus, S. portulacastrum y S. edmondstonii, H. ritteriana, E. prostrata y Melochia crenata). Las especies calciófilas presentaron una fracción de Ca soluble en agua 50% (S. maritima, C. mesembrianthemifolia, S. plumieri, H. curassavicum, Sporobolus virginicusy B. maritima). El ä13C reveló cinco especies con metabolismo fotosintético C4 (A. halimifolia, G. albiflora, S. virginicus, C. mesembrianthemifoliay A. oestophora). Los altos valores de ä15N sugieren como fuente principal de N al NO3 del suelo. Este trabajo incluye una compilación de especies de plantas superiores de la costa caribeña de Venezuela con indicaciones sobre su carácter halofítico.

To determine their degree of halophytism it was analyzed the mineral composition and stable isotopes (13C, and 15N) of leaf material and associated soils of 18 species of coastal plant species in three locations in Falcon State,Venezuela (Coro-La Vela road, COVE; east coast of Paraguaná, COP, and Tacuato bay in Paraguaná, TAC). COP soils were sandy and had the lowest concentrations of N, P, K and Na. TAC soils showed higher salinity (Na, Mg and Ca), whereas those of COVE had higher N and P concentrations and clay texture. COP species had the highest Na concentrations and were more succulent (Sesuvium portulacastrum, S. edmondstonii, Batis maritima, Sarcocornia perennis and Heterostachys ritteriana). Chamaesyce mesembrianthemifolia and Croton punctatus had leaf K/Na ratios %26gt; 1 (non halophytes). Chamaesyce mesembrianthemifolia, Scaevola plumieri, Argusia gnaphalodes, Egletes prostrata, Suriana maritima, and Gomphrena albiflora were relative K accumulators. Calciophobes accumulated most Ca in form of water insoluble oxalate (Atriplex oestophora, G. albiflora and Alternanthera halimifolia), or sequestered in form of phosphates and pectates (Croton punctatus, S. portulacastrum and S. edmondstonii, H. ritteriana, E. prostrata, and Melochia crenata). Calciophile species had a water soluble Ca fraction = 50% (S. maritima, C. mesembrianthemifolia, S. plumieri, H. curassavicum, Sporobolus virginicusand B. maritima). The ä13C values revealed five species with C4-photosynthesis (A. halimifolia, G. albiflora, S. virginicus, C. mesembrianthemifolia and A. oestophora). The positive values of ä15N suggest soil NO3 as the main N source. This paper includes a compilation of higher plant species of the Caribbean coast of Venezuela with indications of their halophytic

Abstract The semi-diurnal tidal regime ( mayor o igual a 2 m) in the Paria Gulf on the Atlantic coast of Venezuela, and the flat landscape of the region, allow the penetration for tens of km of marine waters into the rivers draining the northeastern coastal plain of the country. The levels of salinity, tidal flooding, and sedimentation decrease perpendicularly from the river channel toward the back swamps. The vegetation varies sequentially from fringe mangroves along the river margins, to back swamps containing forests dominated by Pterocarpus officinalis, herbaceous communities of Lagenocarpus guianensis, and palm swamps with Mauritia flexuosa, Chrysobalanus icaco, and Tabebuia spp. This environmental structure was used to test the hypotheses that: (a) mangrove distribution is strongly associated with salinity of interstitial water, and (b) they occupy areas where tidal influence and sediment dynamics determine a relatively open N cycle. Analyses of soil, water, and plants along a 1.5 km transect located near the confluence of the Guanoco and San Juan Rivers (Sucre and Monagas States, Venezuela) revealed that: (a) conductivity decreased from 11 to 0.2 mmhos cm^-1 from the river fringe to the internal swamp, whereas Na in the same stretch decreased from 100 to 2 µ M; (b) average leaf tissue concentrations of Na, P, and N decreased significantly along the transect; (c) P. officinalis showed a large Na-exclusion capacity indicated by positive K/Na ratios from 8 to 200, and Crinum erubescens counteracted Na by accumulating K above 1,000 mmol kg^-1; (d) leaves varied widely in d ¹³ C (-25.5 to -32‰) and d ¹⁵ N (4 to -10.5‰) values. Samples were aggregated according to soil carbon content corresponding to those of the mangrove forest belt (5—28 mol C kg^-1; 0—650 from river fringe) and those of the back swamps (40—44 mol C kg^-1; 700—1,500 m from river fringe). The concentrations of Na, P, and N (in mmol kg^-1) and d ¹⁵ N values (in ‰) were significantly higher in the mangrove forest compared to the back swamp (Na 213 vs. 88; P 41 vs. 16; N 1,535 vs. 727; d ¹⁵ N 1.5 vs. -3.7), indicating that the fringe forest was not nutrient limited. These results support the hypotheses that mangroves are restricted to the more-saline sections of the transect, and that the fringe forest has a more open N cycle, favoring ¹⁵N accumulation within the system.

Para determinar su grado de halofitismo se analizó la composición mineral y de isótopos estables (13C y 15N) de 18 especies de plantas de comunidades costeras, y de los suelos asociados en tres localidades del estado Falcón,Venezuela, en la carretera Coro-La Vela (COVE); y la costa oriental (COP) y la bahía de Tacuato (TAC), ambas en Paraguaná. Los suelos de COP presentaron textura arenosa y valores menores de N, P, K y Na. Los suelos de TAC mostraron mayor salinidad (Na, Mg y Ca) y los de COVE tenían concentraciones mayores de N y P, y textura arcillosa. Las especies de COP tenían las mayores concentraciones de Na, y eran más suculentas (Sesuvium portulacastrum, S. edmondstonii, Batis maritima, Sarcocornia perennisy Heterostachys ritteriana). Chamaesyce mesembrianthemifoliay Croton punctatus tenían cocientes K/Na %26gt; 1 (no halófitas). Chamaesyce mesembrianthemifolia, Scaevola plumieri, Argusia gnaphalodes, Egletes prostrata, Suriana maritimay Gomphrena albiflora son concentradoras relativas de K. Las especies calciófobas acumulan la mayor parte del Ca como oxalato insoluble (Atriplex oestophora, G. albifloray Alternanthera halimifolia), o secuestrado como fosfatos y pectatos (Croton punctatus, S. portulacastrum y S. edmondstonii, H. ritteriana, E. prostrata y Melochia crenata). Las especies calciófilas presentaron una fracción de Ca soluble en agua 50% (S. maritima, C. mesembrianthemifolia, S. plumieri, H. curassavicum, Sporobolus virginicusy B. maritima). El ä13C reveló cinco especies con metabolismo fotosintético C4 (A. halimifolia, G. albiflora, S. virginicus, C. mesembrianthemifoliay A. oestophora). Los altos valores de ä15N sugieren como fuente principal de N al NO3 del suelo. Este trabajo incluye una compilación de especies de plantas superiores de la costa caribeña de

To determine their degree of halophytism it was analyzed the mineral composition and stable isotopes (13C, and 15N) of leaf material and associated soils of 18 species of coastal plant species in three locations in Falcon State,Venezuela (Coro-La Vela road, COVE; east coast of Paraguaná, COP, and Tacuato bay in Paraguaná, TAC). COP soils were sandy and had the lowest concentrations of N, P, K and Na. TAC soils showed higher salinity (Na, Mg and Ca), whereas those of COVE had higher N and P concentrations and clay texture. COP species had the highest Na concentrations and were more succulent (Sesuvium portulacastrum, S. edmondstonii, Batis maritima, Sarcocornia perennis and Heterostachys ritteriana). Chamaesyce mesembrianthemifolia and Croton punctatus had leaf K/Na ratios %26gt; 1 (non halophytes). Chamaesyce mesembrianthemifolia, Scaevola plumieri, Argusia gnaphalodes, Egletes prostrata, Suriana maritima, and Gomphrena albiflora were relative K accumulators. Calciophobes accumulated most Ca in form of water insoluble oxalate (Atriplex oestophora, G. albiflora and Alternanthera halimifolia), or sequestered in form of phosphates and pectates (Croton punctatus, S. portulacastrum and S. edmondstonii, H. ritteriana, E. prostrata, and Melochia crenata). Calciophile species had a water soluble Ca fraction = 50% (S. maritima, C. mesembrianthemifolia, S. plumieri, H. curassavicum, Sporobolus virginicusand B. maritima). The ä13C values revealed five species with C4-photosynthesis (A. halimifolia, G. albiflora, S. virginicus, C. mesembrianthemifolia and A. oestophora). The positive values of ä15N suggest soil NO3 as the main N source. This paper includes a compilation of higher plant species of the Caribbean coast of Venezuela with indications of their halophytic character

Myosin binding protein C (MyBP-C) is a component of the thick filament of striated muscle. The importance of this protein is revealed by recent evidence that mutations in the cardiac gene are a major cause of familial hypertrophic cardiomyopathy. Here we investigate the distribution of MyBP-C in the A-bands of cardiac and skeletal muscles and compare this to the A-band structure in cardiac muscle of MyBP-C-deficient mice. We have used a novel averaging technique to obtain the axial density distribution of A-bands in electron micrographs of well-preserved specimens. We show that cardiac and skeletal A-bands are very similar, with a length of 1.58 ± 0.01 µm. In normal cardiac and skeletal muscle, the distributions are very similar, showing clearly the series of 11 prominent accessory protein stripes in each half of the A-band spaced axially at 43-nm intervals and starting at the edge of the bare zone. We show by antibody labelling that in cardiac muscle the distal nine stripes are the location of MyBP-C. These stripes are considerably suppressed in the knockout mouse hearts as expected. Myosin heads on the surface of the thick filament in relaxed muscle are thought to be arranged in a three-stranded quasi-helix with a mean 14.3-nm axial cross bridge spacing and a 43 nm helix repeat. Extra “forbidden” meridional reflections, at orders of 43 nm, in X-ray diffraction patterns of muscle have been interpreted as due to an axial perturbation of some levels of myosin heads. However, in the MyBP-C-deficient hearts these extra meridional reflections are weak or absent, suggesting that they are due to MyBP-C itself or to MyBP-C in combination with a head perturbation brought about by the presence of MyBP-C.

Blebbistatin is a small-molecule, high-affinity, noncompetitiveinhibitor of myosin II. We have used negative staining electronmicroscopy to study the effects of blebbistatin on the organizationof the myosin heads on muscle thick filaments. Loss of ADP andPi from the heads causes thick filaments to lose their helicalordering. In the presence of 100 µM blebbistatin, disorderingwas at least 10 times slower. In the M·ADP state, myosinheads are also disordered. When blebbistatin was added to M·ADPthick filaments, helical ordering was restored. However, blebbistatindid not improve the order of thick filaments lacking bound nucleotide.Addition of calcium to relaxed muscle homogenates induced thick-thinfilament interaction and filament sliding. In the presence ofblebbistatin, filament interaction was inhibited. These structuralobservations support the conclusion, based on biochemical studies,that blebbistatin inhibits myosin ATPase and actin interactionby stabilizing the closed switch 2 structure of the myosin head.These properties make blebbistatin a useful tool in structuraland functional studies of cell motility and muscle contraction.

Muscle contraction involves the interaction of the myosin heads of the thick filaments with actin subunits of the thin filaments. Relaxation occurs when this interaction is blocked by molecular switches on these filaments. In many muscles, myosin-linked regulation involves phosphorylation of the myosin regulatory light chains (RLCs). Electron microscopy of vertebrate smooth muscle myosin molecules (regulated by phosphorylation) has provided insight into the relaxed structure, revealing that myosin is switched off by intramolecular interactions between its two heads, the free head and the blocked head. Three-dimensional reconstruction of frozen—hydrated specimens revealed that this asymmetric head interaction is also present in native thick filaments of tarantula striated muscle. Our goal in this study was to elucidate the structural features of the tarantula filament involved in phosphorylation-based regulation. A new reconstruction revealed intra- and intermolecular myosin interactions in addition to those seen previously. To help interpret the interactions, we sequenced the tarantula RLC and fitted an atomic model of the myosin head that included the predicted RLC atomic structure and an S2 (subfragment 2) crystal structure to the reconstruction. The fitting suggests one intramolecular interaction, between the cardiomyopathy loop of the free head and its own S2, and two intermolecular interactions, between the cardiac loop of the free head and the essential light chain of the blocked head and between the Leu305—Gln327 interaction loop of the free head and the N-terminal fragment of the RLC of the blocked head. These interactions, added to those previously described, would help switch off the thick filament. Molecular dynamics simulations suggest how phosphorylation could increase the helical content of the RLC N-terminus, weakening these interactions, thus releasing both heads and activating the thick filament.

La estructura de los filamentos gruesos de músculo estriado en el estado relajado ha sido finalmente comprendida a nivel molecular. La estructura revela interacciones intra- e intermoleculares que mantienen las cabezas de miosina unidas formando hélices adosadas a la superficie del filamento grueso. La fosforilación de las cadenas ligeras reguladoras de la miosina induce el debilitamiento de estas interacciones permitiendo la activación de los filamentos gruesos, produciendo el desorden y la liberación de las cabezas de miosina, y permitiendo su interacción con los filamentos delgados. Estos resultados abren las puertas para la comprensión del mecanismo molecular de la regulación ligada a miosina de la contracción muscular, de relevancia ya que las mutaciones asociadas a la cardiomiopatía hipertrófica medioventricular están ubicadas cercanas al sitio de fosforilación en las cadenas ligeras reguladoras de miosina.

The structure of the thick filaments of striated muscle has been finally understood at the molecular level. The structure reveals intra- and inter-molecular interactions that held the myosin heads forming helices on the thick filament surface. The phosphorylation of the myosin regulatory light chains induces the weakening of these interactions, allowing the activation of thick filaments, and enabling their interaction with the thin filaments. These results open the possibility to the understanding of the molecular mechanism of the myosinlinked regulation of muscle contraction. This is of relevance as the mutations associated with mid ventricular cardiomyopathy are located near the phosphorylation site in the regulatory light chain.

We have carried aut the study of the photochemical propierties of a series synthetic meso-tet raphenylsulfonate porphyrins (TPPMS₄) bonde to several metal ions such as: Cu(II), Zn(II), Pd(II), Mn(II),Fe(III),Ni(II),and Co(II) for the optimization of their clinical applications as antiviral agents against the human immunodeficiency virus (HIV-1) as well as the studuy of the in vitro antiviral photoinactivation mechanisms with future application in blood sterilization. A selective inhibition has been determined in the viral growth (HIV-1) when this is irradiated in the presence of the complex TPPFeS₄ and TPPMnS₄ (photosensitizer-mediated type I reation) as well as in the ¹O₂-mediated (typeII reaction) in the presence of TPPPdS₄ and TppZnS₄, remaing cellular viability unaltered in each case.

The objective of this study was to investigate the ability of allopurinol (1) to inhibit free radical or reactive oxygen species (.OH, ¹O₂, H₂O₂) as well as the study of itsphotochemical activity. We investigated the ability of 1 to scavenge oxygen metabolites generated by cell-free systems using luminol enhanced-chemiluminescence and electronic absorption spectra as monitors. Both absorbance and fluorescence scans reveal that 1 is able to react with equimolar quantities of H₂O₂. In the presence of 1 a dose-dependent inhibition period was observed in this system as assayed by isoluminol-enhanced chemiluminescence (ILCL) in the presence of horseradish peroxidase (HRP), as well as by luminol-enhanced chemiluminescence (LCL) in the presence of H₂O₂ or ferrous ion. On the other hand, 1 did not show an efficient scavenging activity of galvanoxyl radical in ethanolic solutions. Furthermore, in a separate experiment, it was not observed trapping of singlet oxygen (¹O₂) generated by Rose Bengal, in the presence of 1. The activity of 1 was compared with that of vitamins E and C. In vitro experiments of photohemolysis in presence of 1 and cinoxacin, a phototoxic antibacterial quinolone, the photohemolytic effect of cinoxacin was diminished. Allopurinol alone did not show any phototoxic effect under irradiation with UV-A or visible light but was photo-unstable and phototoxic in vitro with UV-B light.

The gastric glands of the mammalian fundic mucosa are constitutedby different cell types. Gastric fluid is a mixture of acid,alkali, ions, enzymes, and mucins secreted by parietal, chief,and mucous cells. We studied activation of acid secretion usingLysoSensor Yellow/Blue in conjunction with fluo 3 to measurechanges in pH and Ca²⁺ in isolated rabbit gastric glands. Weevidenced a spatial heterogeneity in the amplitude of acid responsealong the gland axis under histamine and cholinergic stimulation.Carbachol induced a transitory pH increase before acidification.This relative alkalinization may be related to granule releasefrom other cell types. Omeprazole inhibited the acid componentbut not the rise in pH. Histamine stimulated acid secretionwithout increase of lumen pH. We studied the relationship betweenCa²⁺ release and/or entry and H⁺ secretion in glands stimulatedby carbachol. Ca²⁺ release was associated with a fast and transientcomponents of H⁺ secretion. We found a linear relationship betweenCa²⁺ release and H⁺ secretion. Ca²⁺ entry was associated witha second slow and larger component of acid secretion. The fastcomponent may be the result of activation of Cl^— and K⁺channels and hence H⁺/K⁺ pumps already present in the membrane,whereas the slow component might be associated with translocationof H⁺/K⁺ pumps to the canaliculi. In conclusion, with cholinergicstimulation, gastric glands secrete a mixture of acid and otherproduct(s) with a pH above 4.2, both triggered by Ca²⁺ release.Maintenance of acid secretion depends on Ca²⁺ entry and perhapsmembrane fusion.

Tityus discrepans venom (TdV) produces digestive hemorrhages, disseminated intravascular coagulation, alveoli fibrin deposition and/or prothrombin and partial thromboplastin time alterations in humans. T. discrepans venom presents an in vitro tissue plasminogen activator-like (tPA-like), fibrino(geno)lytic and plasmin inhibitory activities. The plasmin inhibitor, called discreplasminin, was isolated from TdV. Discreplasminin has a pI of 8.0 and a relative molecular weight of %26lt;6,000 Da. Discreplasminin and aprotinin strongly inhibited plasmin activity and moderately tPA activity, while epsilon amino caproic acid (EACA) moderately inhibited both enzymes. In presence and absence of fibrin, the plasmin generation by tPA was completely inhibited by aprotinin and discreplasminin. EACA in the absence of fibrin partially inhibited plasmin generation (37%); however, it produced a total inhibition of plasmin generation on a fibrin surface. The tPA-clot lysis assay showed that discreplasminin acts like aprotinin inducing a slight delay in lysis time and lysis rate; in contrast, EACA presented a total inhibitory effect on fibrin lysis. These results suggest that discreplasminin presents an anti-fibrinolytic mechanism similar to aprotinin. Discreplasminin probably interacts with the active sites of plasmin and tPA. The presence of discreplasminin and other similar components in scorpion venom could partially explain the generalized fibrin deposition which was found previously in rams.

Ameranthropoides loysi Montandon 1929: The History of a Primatological Fraud reviews the information published on the controversy of the discovery of an alleged Neotropical anthropoid ape, that resulted in one of the most notorious scientific frauds of the 20th Century. Such finding supposedly occurred either in 1917 or 1918 while oil prospecting in the forests of the Tarra River region, located in the southwestern part of Lake Maracaibo, Zulia state, Venezuela. This case was as much discussed as it was unresolved. Detailed analysis of the archival sources suggested that the naming of such a primate was a fraud orchestrated by the Swiss physician George Montandon and de Loys himself, resulting in one of the most notorious scientific frauds of the 20th Century. This investigation provides previously unpublished information about this case -whose development seems to be resolved in Venezuela, through the account of a third witness, the Venezuelan physician Enrique Tejera.

Ameranthropoides loysi Montandon 1929: la historia de un fraude primatológico revela la información publicada en torno de la controversia del descubrimiento de un supuesto simio neotropical, que resultó ser uno de los mayores fraudes científicos del siglo XX. Tal hallazgo presuntamente ocurrió en 1917 ó 1918 durante una exploración petrolera en la región del río Tarra, al sur del Lago de Maracaibo, estado Zulia, Venezuela. Es un caso tan discutido como irresoluto. El análisis detallado de las fuentes documentales permite sugerir que la descripción de dicho primate fue una farsa orquestada por el médico suizo George Montandon y por el mismo de Loys. La investigación aporta información inédita sobre este particular -posiblemente uno de los fraudes científicos más escandalosos del siglo XX- y cuyo desarrollo parece quedar aclarado en Venezuela por el testimonio de un tercer testigo, el médico venezolano Enrique Tejera.

La movilidad geográfica es un proceso en aumento. Si bien hacia 1960 había en el mundo 245,000 estudiantes estudiando en el extranjero, en 2004 había 2.5 millones. Los flujos de movilidad se orienta de países en desarrollo hacia las instituciones de educación superior en países ricos. Se percibe una valiosa orientación internacinal a ver la educación y la investigación una vía de posicionamiento en el mundo y su economia. En el presente, sin embargo, hay alternativas significativas en muchos contexto locales donde la información en investigación ha tenido avances muy notable. Pero lo que se ha logrado en las instituciones de los países en desarrollo, está bajo la constante amenaza de perdese ante el mercado internacional.

Not only was it necessary to attempt to convince the local inhabitants and the local authorities of the importance of these marine pollution studies, but also the national funding agencies. The local fishermen needed to be educated in the proper harvesting of the clams, as well as prosessing the raw clams to clam meats without introducing further contamination. Proper sampling and sample preparation is very costly and is difficult to even convince the goverment funding programs and need to be taken into account when soliciting funding. Similarly to the California Mussel Watch monitoring program that began in 1977 and reviweb by phillips in 1988 [1], our research program that began in 2000 had many of the same shortcomings, but not only for economic reasons:

N-Dichlorophosphanyldibenzo[b,f]azepine (6) reacted with (-)-2,3-O-isopropylidene-d-threitol, (R)-taddol, (R,R)-diethyltartrate, (R,R)-diethyltartrate, (S)-binaphthol, a,a-diphenyl-l-prolinol, and (S)-proline to form the corresponding chiral P-alkene ligands 7-12. These ligands were then used to synthesize dinuclear chloro-bridged Rh(I) complexes 13-18 with the general formula [Rh(µ-Cl)(P-alkene)]2. It was shown by X-ray diffraction analyses that these P-alkenes indeed act as bidentate ligands for Rh(I). Furthermore, the crystal structures revealed a change in the hybridization state of the dibenzazepine N atom, passing from sp2 in the free ligand to sp3 when coordinated to Rh in a bidentate fashion, thus modifying the bite angle of the ligands. The Rh complexes 16 and 18, bearing the (S)-binaphthol-derived ligand 10 and the a,a-diphenyl-l-prolinol-derived ligand 12, respectively, were shown to be active and enantioselective catalysts for the 1,4 addition of arylboronic acids to enones. At 80 °C turnover numbers of up to 61 and enantiomeric excesses of up to 92% were observed.

Abstract. Pedaliodes chrysotaenia Hopffer, a little known central Peruvian species, is discussed and compared with P. spina Weymer and P. jelskii Pyrcz. Its new subspecies is described from southern Junín. A new, similarly patterned, sympatric species is described from Pasco.

Abstract. Pedaliodes demathani Pyrcz is one of the most polytypic representatives of the genus, with ten recognised subspecies. The nominotypical subspecies was discovered in northern Peru (Amazonas and San Martín). We describe nine new subspecies here, which differ from each other in colour patterns, mostly of the hindwing upper and underside. Further differences are in male genital morphology. New subspecies are distributed through central (Huánuco, Pasco, Junín and Ayacucho) and southern Peru (Cuzco and Puno), and the Bolivian Yungas de La Paz. Two subspecies of P. demathani in central Peru form a mimicry ring involving four loosely related congeners.

Abstract. A new species P. derisoris is described from the Huánuco department in central Peru. It is found to be closely related to P. paneis (Hewitson) occurring in northern Peru. The two share a striking synapomorphy, elongated ocellar elements on the hindwing underside. Their male genitalia are closely similar, whereas more conspicuous elements of wing colour pattern are widely divergent.

Abstract. Two little known south Peruvian species, Pedaliodes niveonota Butler and P. parma Thieme, are redescribed. Two related species, P. cendreata n. sp. and P. misericordiosa n. sp., are described from central Peru. The “P. niveonota” group is identified by a series of synapomorphies in the external morphology and male genitalia.

Abstract. The systematics and taxonomy of high elevation species related to Pedaliodes pammenes (Hewitson) is discussed. Four species and five subspecies are described. P. illimania Staudinger, P. garleppi Thieme and P. uncus Thieme are reinstated as valid species. Synapomorphic characters defining the so-called P. pammenes group are identified and discussed.

Abstract. Eight new taxa related to Pedaliodes tyro Thieme are described, including six species and two subspecies. It is demonstrated that the designation of the lectotype of Pedaliodes tyro from Marcapata is incorrect, and that the true type locality is Limbani. P. tyro is redescribed and redefined.

Abstract. Pedaliodes ornata is an endemic species of the Cordillera de Mérida, known thus far only from the Chama valley in the centre of the range. Its new subspecies, P. ornata haroldboxi n. ssp., is described from the northern part of the Cordillera. Ecological traits, altitudinal and geographic ranges, and the affinities of P. ornata are discussed.

A semi-empirical method to determine radionuclide concentrations in large environmental samples without the use of reference material and avoiding the typical complexity of Monte-Carlo codes is proposed. The calculation of full-energy peak efficiencies was carried out from a relative efficiency curve (obtained from the gamma spectra data), and the geometric (simulated by Monte-Carlo), absorption, sample and intrinsic efficiencies for energies between 130 and 3000 keV. The absorption and sample efficiencies were determined from the mass absorption coefficients, whereas the intrinsic efficiency was approximated by an empirical function. The deviations between calculated and experimental efficiencies for a reference material in most cases are less than 10%. Radionuclide activities in marine sediment samples calculated by the proposed method and by the experimental comparative method were not significantly different. This new method can be used for routine environmental monitoring when uncertainties up to 10% are acceptable.

Lonomia achelous caterpillar, Lepidoptera distributed along some South American countries, induces a hemorrhagic syndrome in people who come into contact with its bristles. A clinical characteristic in these patients is that fresh healed wounds are re-opened and bleed. In order to explain this symptomatology, we evaluated the effect of Lonomin V (a protein isolated from L. achelous hemolymph), on some functional properties of fibronectin, which in turn plays an important role in the hemostasis. The effect of Lonomin V on fibronectin was studied by SDS-PAGE in reduced condition, binding to gelatin and heparin, crosslinking to fibrin and platelet adhesion. Formation of degradation products of 120, 66, 50, 40 and 29 kDa, some of which retain affinity to heparin and gelatin were observed; however, the fibronectin degradation fragments presented a significant decrease of crosslinking capacity to fibrin and platelet adhesion, suggesting that the proteolysis of fibronectin by Lonomin V induces changes in its crosslinking sites and on platelet receptors. These findings might partially explain the wound dehiscence observed in the patients. Due to its effect on adhesive proteins with concomitant impairment of some functional properties, Lonomin V might be useful for cellular adhesion studies involved in hemostasis such as platelet adhesion.

We propose an alternative method to remove the tensile instability in standard SPH simulations of a fluid. The method relies on an adaptive density kernel estimation (ADKE) algorithm, which allows the width of the kernel interpolant to vary locally in such a way that only the minimum necessary smoothing is applied to the data. By means of a linear perturbation analysis of the SPH equations for a heat-conducting, viscous, van der Waals fluid, we derive the corresponding dispersion relation. Solution of the dispersion relation in the short wavelength limit shows that the tensile instability is effectively removed for a wide range of the ADKE parameters. Application of the method to the formation of equilibrium liquid drops confirms the analytical results of the linear stability analysis. Examples of the resolving power of the method are also given for the nonlinear oscillations of an excited drop and the Sedov blast wave problem.

The present study was carried out in order to examine the anticancer properties of two sesquiterpene lactones, millerenolide and thieleanin, isolated from Viguiera sylvatica and Decachaeta thieleana, against cell lines in vitro, and on the growth B16/BL6 melanoma tumors in C57BL/6 mice. Millerenolide and thieleanin showed a similar pattern of cytotoxicity with the greatest effect on viability being evident with A549 human lung cancer cells (IC₅₀ – 40 and 32 µM respectively), and with the 3T3/HER2 cell line which are 3T3 mouse fibroblasts transfected with the HER2 oncogene (IC₅₀ – 16 and 28 µM respectively). The parent 3T3 cells and the B16/BL6 mouse melanoma cells were less sensitive to these compounds, with thieleanin showing an IC₅₀ with B16/BL6 greater than the highest dose tested (203 µM). Treatment with millerenolide (8 mg/kg, i.p. on days 0, 2 and 4 post-inoculation) significantly inhibited the growth of subcutaneous B16/BL6 tumors in C57BL/6 mice, (50% inhibition at day 25, P = 0.015), as well as retarding the appearance of detectable tumor (millerenolide – day 15.2 ± 0.4 vs control – day 12.8 ± 0.5, mean ± SEM, P = 0.011). In contrast, treatment with thieleanin (8 mg/kg every other day up to the day of kill) neither retarded the appearance of the tumor nor its growth.

The effect of land use changes on the woody cover and patchiness of the Orinoco lowlands was analyzed from 1951 to 1997 by using a stretched exponential model in terms of the patch size distribution. We selected five production systems on the basis of the following components: policy option, technology and environment. They are: (a) high-input pasture in deep soil (DL-HIGraz), (b) low-input cropping in deep soil (DH-LOCrop), (c) high-input cropping in deep soil (DH-HICrop), (d) low-input cropping in shallow soil (SL-LOCrop) and (e) extensive cattle grazing in shallow soil (SL-LOGraz). For comparison, stands with similar soil depth and woody density (DL-Fallow, DH-Fallow and SL-Fallow) were selected at the protected Biological Reserve in the Calabozo region. Results indicate that the distribution of the patches was described by the stretched exponential distribution model with c as the exponent distribution. The magnitude of c reflected the effect of land use changes over time. Thus, the parameter c for human impacted stands was higher than that for the fallow stands. The stretched exponential model implies that the human impact had a multiscalar effect on the Orinoco mosaic, in terms of the multiplicative processes. There is a generic mechanism exhibiting an anomalous distribution of the patches such as has been proposed for physical systems. Therefore, the number of generation of the multiplicative processes (i.e. inverse of c) for impacted stands was lower than that in the fallow stands. As the time from fallow establishment proceeded, there was a tendency to patch re-organization by biotic effects

The precipitation and impregnation methods in the preparation of chromium-doped magnetite for water gas shift reaction (WGSR) were compared in this work. This reaction is an important step in the commercial production of highly pure hydrogen from natural gas or naphtha feedstocks. It was found that the preparation method affects both the textural and catalytic properties of chromium-doped magnetite. However, chromium was able to preserve the specific surface area during the WGSR and to delay the metallic iron production, independently of the preparation method. Chromium caused a decrease in activity per area, depending on the preparation method. This fact was assigned to its ability in making the production of Fe²⁺ species more difficult, making the catalytic sites less active, because the redox cycle of the reaction becomes more difficult. The most active catalyst was obtained by adding chromium by impregnation, which led to a large amount of total chromium in the solid and then a catalyst with high specific surface area was produced. It was showed that the catalysts can be prepared in the active phase avoiding the reduction step, before reaction.

A novel PCR method was developed to discriminate amongst genotypes A—C of the rotavirus non-structural protein 4 (NSP4). Genotype-specific primers were designed that correctly identified the NSP4 genotype when evaluated as a multiplex PCR with cell culture adapted rotavirus strains. Rotavirus strains B223 SGIG6P6[1], NCDV SGIG6P6[1] and SA11 SGIG3P5B[2] were used as control for NSP4 genotype A; A34 SGIG5P14[23], Gottfried SGIIG4P2B[6] and Wa SGIIG1P1A[8] for NSP4 genotype B; RRV SGIG3P5B[3] for NSP4 genotype C. Subsequently, the same set of specific primers was used to genotype a set of 77 Swedish clinical samples. The results showed that all human clinical samples analyzed belong to the NSP4 genotype B and the VP6 subgroup

The ethylbenzene dehydrogenation in the presence of steam is the dominant technology for styrene production, one of the most important high value chemicals. The most widely used industrial catalyst comprises potassium-promoted iron oxide, which deactivates with time, due to potassium loss. In order to find alternative free-potassium catalysts, the effect of lanthanum on hematite-based catalysts was studied in this work. Samples with different amounts of lanthanum and prepared with different precipitants (ammonium hydroxide, sodium carbonate and sodium hydroxide) were obtained. It was found that lanthanum led to the production of solids with small particles when ammonium hydroxide was used, a fact which was assigned to lanthanum species on the surface where they keep the hematite particles apart avoiding sinterization. On the other hand, bigger particles were produced when sodium hydroxide and sodium carbonate are used, which resulted in solids with small specific surface areas. This was related to the sodium species which covered the surface impairing the lanthanum action. The most promising catalyst was that prepared with ammonium hydroxide and with La/Fe = 0.1, which showed the highest specific activity and the highest activity per area. In this solid, lanthanum acts as a structural promoter.

Sulfated zirconia has found several industrial applications, mainly for catalyzing reactions which require acidic sites. In order to control the properties of this solid, the effect of iron on the sulfated zirconia properties was studied in this work. Samples with different iron to zirconium molar ratios were prepared by the sol—gel method, followed by sulfation and characterization by several techniques. It was found that all iron ions go into zirconia when Fe/Zr = 0.4. However, when higher amounts of iron (Fe/Zr = 0.8) are added, hematite is segregated. Different phases can be obtained depending on the iron content and on the sulfur presence. Iron increases the specific surface areas of both sulfated and pure zirconia but does not affect the incorporation of sulfate groups as compared to pure zirconia. Iron also makes the solids thermally more stable and modifies the sulfated zirconia surface creating acidic sites with medium strength. Therefore, it is possible to control the acidity of the solid doping the sulfated zirconia with iron. All these changes are very useful for catalytic applications.

Electron paramagnetic resonance (EPR) experiments were made in the diluted magnetic semiconductor CuGa_1-xMn_xTe₂, in the temperature range 70%26lt;T%26lt;300 K. The samples were synthesized by direct fusion of stoichiometric mixtures of the elements, with Mn composition from x=0.0 to 0.25. The EPR spectra were measured as function of temperature, Mn composition, and field orientation. The temperature variation of the resonance field shows a critical point at about 235 K, and is associated with a transition from the ferromagnetic to the superparamagnetic state. The resonance field was also measured as a function of the field angle, and displays a well-defined uniaxial symmetry. This uniaxial field depends on the Mn concentration and is due to tetragonal distortions induced by Mn²⁺ at Ga sites, and the demagnetizing effects due to formation of ferromagnetism (FM) Mn-clusters.

Bothrops colombiensis venom from two similar geographical locations were tested for their hemostatic functions and characterized by gel-filtration chromatography and SDS-PAGE electrophoresis. The snakes were from Caucagua and El Guapo towns of the Venezuelan state of Miranda. Fibrino(geno)lytic, procoagulant, hemorrhagic, lethal activities, gel-filtration chromatography and SDS-PAGE profiles were analyzed and compared for both venoms. The highest hemorrhagic activity of 5.3 µg was seen in El Guapo venom while Caucagua venom had the lowest LD₅₀ of 5.8 mg/kg. Both venoms presented similar thrombin-like activity. El Guapo showed a factor Xa-like activity two times higher than Caucagua. Differences were observed in kallikrein-like and t-PA activities, being highest in El Guapo. Caucagua venom showed the maximum fibrin lysis. Both crude venom runs on Sephadex G-100 chromatography gave fraction SII with the high fibrinolytic activity. Proteases presented in SII fractions and eluted from Benzamidine-Sepharose (not bound to the column) provoked a fast degradation of fibrinogen a chains and a slower degradation of ß chains, which could possibly be due to a higher content of a fibrinogenases in these venoms. The fibrinogenolytic activity was decreased by metalloprotease inhibitors. The results suggested that metalloproteases in SII fractions were responsible for the fibrinolytic activity. The analysis of samples for fibrin-zymography of SII fractions showed an active band with a molecular mass of approximately 30 kDa. These results reiterate the importance of using pools of venoms for antivenom immunization, to facilitate the neutralization of the maximum potential number of toxins.

New heteroallyl-containing 5-nitrofuranes were synthesized as potential anti-Trypanosoma cruzi agents with a dual mechanism of action, oxidative stress and inhibition of membrane sterol biosynthesis. Some of the derivatives were found to have high and selective activity against the proliferative stages of the parasite, with IC₅₀ values against the clinically relevant intracellular amastigote forms in the low micromolar to sub-micromolar range. Oxidative stress was verified measuring cyanide dependent respiration. Inhibition of the de novo sterol biosynthesis at the level of squalene epoxidase was confirmed, using high-resolution gas—liquid chromatography coupled to mass spectrometry, by the disappearance of the parasite’s mature sterols and the concomitant accumulation of squalene. The in vitro activities of these novel compounds were superior to that of nifurtimox, a nitrofuran currently used in the treatment of human Chagas’ disease, and terbinafine, a commercially available allylamine-based squalene epoxidase inhibitor. The results support further in vivo studies of some of these nitrofuran derivatives.

The effect of neodymium, lanthanum, aluminum and zirconium on the textural and catalytic properties of hematite was studied in this work, which aimed to develop catalysts to ethylbenzene dehydrogenation, in the presence of steam, the main commercial route to obtain styrene. Hematite and magnetite were found in fresh and spent catalysts, respectively. All dopants increased the specific surface area of the fresh and spent catalysts and made them more resistant against reduction, but only aluminum avoided sintering during reaction. The dopants increased the catalytic activity per area of hematite, except aluminum which acted only as a textural promoter. The selectivity was decreased due to zirconium and lanthanum while the other dopants did not change this parameter. The neodymium-containing catalyst showed high levels of activity and selectivity and was able to work up to 530 °C, without deactivation, being the most promising with regard to styrene production.

The IS6110 element is widely used in studies of molecular epidemiology of tuberculosis and it is considered the gold standard for genotyping Mycobacterium tuberculosis strains. Because of its high frequency of transposition, IS6110 is probably a major contributor to the evolution of M. tuberculosis. Nevertheless, very few studies of the effect of IS6110 insertions on the virulence of M. tuberculosis have been reported. We analysed two isogenic groups of M. tuberculosis strains isolated from the sputa of two patients. Strains belonging to the same isogenic group differed from one another by one IS6110-oriC hybridising band, but they showed identical spoligo and MIRU-VNTR profiles. Isogenic strains containing the IS6110 element in oriC exhibited a diminished growth rate and average dimensions of the bacilli were modified; moreover, they were less virulent in a mouse model

Quantum-chemical calculations were performed using the DFT method and a qualitative parametric quantum method (PQM) named CATIVIC, in order to model the whole EFAL formation process. Two clusters (AlSi₃O₁₂H₉ and AlSi₆₃O₁₅₂H₄₉) were employed to model zeolite ZSM-5. Formation of intermediate Al species was reported with four to zero bond coordinations to the zeolite framework. The EFAL formation process was analyzed by the evaluation of bond distances, diatomic bond energies changes (Delta-DBE) and Wiberg's indexes (WI) of Al—O bonds. Penta- and hexacoordinated intermediates were produced and free Al(OH)₃ and Al(OH)₃(H₂O)₂ EFAL species were formed from the small and big clusters, respectively. Comparisons with the DFT method permit establishing that CATIVIC or a well-parameterized PQM method can be used to understand zeolite changes under hydrothermal treatment.

Membrane type 1 matrix metalloproteinase (MT1-MMP) is an integral membrane protein that participates in the processing and degradation of cell surface proteins and the extracellular matrix (ECM). This enzyme regulates ECM turnover in wound repair, promotes cell migration and activates other MMPs, such as MMP-2, which is involved in angiogenesis, cell migration and tumoral metastasis. An increase in pro-inflammatory cytokine expression, such as gamma interferon (IFN-Gamma), has been associated with chronic wounds in inflammatory bowel diseases. However, the extent to which cytokines modulate MT1-MMP has not been totally defined. In this report, the effects of the bacterial lipopolysaccharide (LPS) and ECM-bound IFN-Gamma on MT1-MMP expression and MMP-2 activity were evaluated by Western blot, RT-PCR and zymography in isolated intestinal epithelial and cultured HT-29 cells. In the presence of LPS, ECM-bound IFN-Gamma, but not soluble IFN-Gamma, reduced the enterocyte MT1-MMP protein expression. In addition, the active form of MMP-2 was also decreased in the presence of both LPS and IFN-Gamma, indicating that lower MMP-2 activity accompanied the decrease in MT1-MMP expression. These results suggest the possibility that endotoxin and ECM-bound IFN-Gamma may affect matrix remodeling by modulating matrix metalloproteinase in enterocytes during wound healing.

By means of genealogical concordance phylogenetic species recognition (GCPSR), we have investigated coding and non-coding regions from various genes and the ITS sequences of 7 new and 14 known isolates of Paracoccidioides brasiliensis. Such isolates grouped within the three phylogenetic groups recently reported in the genus Paracoccidioides, with one single exception, i.e., Pb01, a strain that has been the subject of intense molecular studies for many years. This isolate clearly separates from all other Paracoccidioides isolates in phylogenetic analyses and greatly increases the genomic variation known in this genus.

We introduce two new binary operations on combinatorial species; the arithmetic product and the modified arithmetic product. The arithmetic product gives combinatorial meaning to the product of Dirichlet series and to the Lambert series in the context of species. It allows us to introduce the notion of multiplicative species, a lifting to the combinatorial level of the classical notion of multiplicative arithmetic function. Interesting combinatorial constructions are introduced; cloned assemblies of structures, hyper-cloned trees, enriched rectangles, etc. Recent research of Cameron, Gewurz and Merola, about the product action in the context of oligomorphic groups, motivated the introduction of the modified arithmetic product. By using the modified arithmetic product we obtain new enumerative results. We also generalize and simplify some results of Canfield, and Pittel, related to the enumerations of tuples of partitions with the restrictions met.

Specific immunoassays were developed to detect anti-horse, anti-chicken and anti-bovine immunoglobulins in human IgG preparations. Three samples of 5% human IgG for intravenous use (“Inmunoglobulina G Endovenosa al 5%”^™, Quimbiotec CA), were studied. All samples were produced from pools of greater than 2500 plasma units from different donors. One sample was produced from an only Venezuelan plasma pool (2660 donors) and the other two were produced from a 1:1 blend of Venezuelan and Canadian plasma pools. The amounts of human IgG detected were 0.017 against horse IgG, 0.37 (0.28, 0.48) mg/ml (n=18) against cattle IgG and 1.27 (1.15, 1.40) mg/ml (n=15) against chicken IgY. Similar results were obtained on individual Venezuelan plasma samples. The differences probably reflect the consumption and antigenicity of meat. Poultry and bovine meat are widely consumed in Venezuela and Canada, while equine meat is not consumed; also chicken is more heterologous to man and may be more antigenic than bovine meat. This suggests that when IgY immunotherapeutics are used in populations with an important dietary component of poultry meat and eggs, there is a risk of producing untoward reactions and less efficient antivenoms

The molybdenum(VI) dioxodibromo-(4,4'-dicarboxylate-2,2'-bipyridine) complex was anchored on a TiO₂ solid matrix, fully characterized by ¹³C and ¹⁵N solid-state NMR spectroscopy and evaluated as an oxygen atom transfer agent under visible light (Lambda greater than 420 nm) irradiation. It was compared with the complex molybdenum(VI) dioxodibromo-(4,4'-dicarbomethoxy-2,2'-bipyridine) under homogeneous conditions. Two positive effects were observed: (1) an important reactivity increase due to the photogenerated electronic flux onto the molybdenum coordination sphere and (2) a catalyst life span amplification due to the isolation of the metallic centers allowing the catalytic system to be turned on and off in the presence or absence of O₂.

Optically homogeneous single wall carbon nanotube-silica gel composites are prepared from aqueous supensions using a sol-gel process. The gels display a strong photoluminescent signal which indicates that no aggregation occurs during gelation, i.e. that the nanotubes are essentially dispersed as individuals in the composites.

Capillary effect was used to fill double wall carbon nanotubes (DWCNT) with iron. The samples are characterized by Mössbauer and Raman spectroscopies, TEM, SAED, and magnetization. The experimental results indicate the presence of alpha-Fe nanowires inside the DWCNTs. The samples are ferromagnetic at room temperature. There are three striking results due to the confinement effects on the physical behavior of alpha-Fe: the hyperfine fields increase, the Debye temperature decreases and Raman modes are observed.

We investigate the connections between functions of type x_n=p(?Tzⁿ) and nonlinear maps coupled to non-invertible transformations. These systems can produce unpredictable dynamics. We study the higher-order correlations in the generated sequences. We show that (theoretically) it is possible to construct systems that can generate sequences that constitute a set of statistically independent random variables. We apply the results in the improvement of a two-dimensional coupled map system that has been used in practical applications as e.g. cryptosystems and data compression.

Trypanosomatids contain predominantly ergostane-based sterols, which differ from cholesterol, the main sterol in mammalian cells, in the presence of a methyl group in the 24 position. The methylation is initiated by S-adenosyl-l -methionine: ?^{24 (25)}-sterol methenyltransferase, an enzyme present in protozoa, but absent in mammals. The importance of this enzyme is underscored by its potential as a drug target in the treatment of the leishmaniases. Here, we report studies concerning the intracellular distribution of sterol methenyltransferase in Leishmania major promastigotes and overexpressing cells using a specific antibody raised against highly purified recombinant protein. It was found by immunofluorescence and electron microscopy studies that in L. major wild-type cells sterol methenyltransferase was primarily associated to the endoplasmic reticulum. In addition to this location, the protein was incorporated into translucent vesicles presumably of the endocytic pathway. We also found in this study that cells overproducing the enzyme do not have increased resistance to the sterol methenyltransferase inhibitor 22, 26 azasterol.

This article discusses the world distribution of scientists, engineers, and technologists and the movement of these personnel from peripheral countries to central countries. It begins with an analysis of the US as the center of attraction for scientists and technologists, using Latin America as an example. It characterizes mobility and migration flows and examines the migration of Venezuelan scientists and technologists to the US. Finally, it discusses the relevance of intellectual patrimony and physical location in view of the possibilities offered by information and communication technology (ICT).

Modifications of lymphocyte serotonergic system have been described in major depression. The aim of this study was to determine new possible changes of this system in depression. Twenty eight patients, free of drugs, diagnosed with major depression disorder by Structured Clinical Interview for Disorders of Axis I, without medical illnesses, written consent, approved by Ethical Committees were included. Controls were 30 healthy subjects without family history of psychiatric disease. Blood monocytes were isolated with Ficoll/Hypaque, and lymphocytes by differential adhesion to plastic. Serotonin and 5-hydroxyindoleacetic acid determined by HPLC. Monocytes had higher serotonin concentrations than lymphocytes, and serotonin/5-hydroxyindoleacetic acid was lower in patients. Basal proliferation was elevated in depressed and not increased by Concanavalin A. Fluoxetine reduced basal proliferation more efficiently in patients, indicating activation of lymphocytes in depression. The number of cells expressing serotonin transporter was reduced in depressed. There were no differences in CD4+ (~ 50%) or CD8+ (~ 25%) lymphocytes between the groups, although CD8+ were lower in depressed, and greater number of them co-localized serotonin transporter than CD4+, which could be crucial for function in relation to serotonin and its receptors in immune cells. Lymphocytes were activated in this group of patients and fluoxetine reduced proliferation, probably being relevant for the psychopharmacological treatment of depression.

Leishmaniasis is a parasitic zoonosis caused by protozoans of the genus Leishmania transmitted by insects known as phlebotomines, which are found in wild or urban environments. The disease occurs in tropical and sub-tropical areas, mainly in Asia, Europe, Africa and the Americas. At present, there is no effective treatment for this disease. In the search for new rational chemotherapeutic alternatives, two novel trans [Pt(Hpy 1 )₂(Cl)₂] ( 1 ) and trans [Pt(Hpy 2 )₂ (Cl)₂] ( 2 ) complexes were synthesized by the reaction of K₂PtCl₄ with sterol hydrazone ligands 20-hydrazone-pyridin-2-yl-5a-pregnan-3ß-ol (Hpy 1 ) and 22-hydrazone-pyridin-2-yl-chol-5-ene-3ß-ol (Hpy 2 ). These organic compounds are specific inhibitors of sterol methyl transferase (SMT). The new platinum complexes were characterized by a combination of ESI–MS (electrospray ionization–mass spectroscopy), UV–vis, infrared and NMR spectroscopies; elemental analysis and molar conductivity. Promastigotes of Leishmania (L.) mexicana were treated for 48 h with 10 µM of the sterol hydrazones Hpy 1 or Hpy 2 alone or coordinated to Pt. Hpy 1 produced higher leishmanistatic activity than Hpy 2 (39% growth inhibition vs. 16%), which significatively increased (71%, p%26nbsp;Less than 0.001) when the complex trans-[Pt(Hpy 1 )₂(Cl)₂] was used. This complex represents a new chemotherapeutic alternative to be evaluated in depth in experimental models of leishmaniasis.

Brain dopaminergic system has a crucial role in the etiology of several neuropsychiatric disorders, including Parkinson’s disease, depression, and schizophrenia. Several dopaminergic drugs are used to treat these pathologies, but many problems are attributed to these therapies. Within this context, the search for new more efficient dopaminergic agents with less adverse effects represents a vast research field. The aim of the present study was to synthesize N-[2-(4,5-dihydroxyphenyl)-methyl-ethyl]-4,5-dihydroxy-2-aminoindan hydrobromide ( 3 ), planned to be a dopamine ligand, and to evaluate its dopaminergic action profile. This compound was assayed as a diastereoisomeric mixture in two experimental models: stereotyped behavior (gnaw) and renal urinary response, after central administration. The pharmacological results showed that compound 3 significantly blocked the apomorphine-induced stereotypy and dopamine-induced diuresis and natriuresis in rats. Thus, compound 3 demonstrated an inhibitory effect on dopaminergic-induced behavior and renal action. N-[2-(-Methyl-ethyl)]-4,5-dihydroxy-2-aminoindan hydrobromide ( 4 ) was previously reported as an inotropic agent, and in the present work it was also re-evaluated as a diastereoisomeric mixture for its possible central action on the behavior parameters such as stereotypy and dopamine-induced diuresis and natriuresis in rats. Our results indicate that compound 4 produces an agonistic response, possibly through dopaminergic mechanisms. To better understand the experimental results we performed molecular dynamics simulations of two complexes: compound 3 /D₂DAR (dopamine receptor) and compound 4 /D₂DAR. The differential binding mode obtained for these complexes could explain the antagonist and agonist activity obtained for compounds 3 and 4 , respectively.

We have synthesized two naphthyl ester quinolone derivates and determined their ability to generate reactive oxygen species (ROS) such as ¹O₂, OH, H₂O₂ upon photolysis with UV-A light. The ability of cinoxacin ( 1 ) and nalidixic acid ( 2 ), and their naphthyl ester derivatives ( 3 and 4 ) to generate a dose-dependent amount of singlet oxygen and ROS (^-O₂, OH) in cell-free systems was detected by histidine assay and by luminol-enhanced chemiluminescence (LCL), respectively. Their electronic absorption and emission spectra were quantified and their photostability was determined. Their tendency to generate peroxidic derivative species showed the following order: 3 Greater than 4 ; in contrast, their ability to generate singlet oxygen was 4 Greater than 3 and these were better sensitizers than their parent quinolones 1 and 2 . The antibacterial activity in darkness and under irradiation of compounds 3 and 4 was tested on Escherichia coli and compared with that of their parent compounds. An enhanced antibacterial activity by irradiation of the naphthyl esters of cinoxacin and nalidixic acid on E. coli was observed.

The theoretical study of the gas-phase pyrolysis kinetics of several tert-nitroalkanes, 2-methyl-2-nitropropane, 2-methyl-2-nitrobutane, and 2, 3-dimethyl-2-nitrobutane, has been carried out at the MP2/6-31G(d), B3LYP/6-31G(d), B3PW91/6-31G(d), levels of theory. The nitroalkanes yield the corresponding alkene and HNO₂ gas in a rate determining step. The B3PW91/6-31G(d) method was found to give a reasonable good agreement with the experimental kinetic and thermodynamic parameters. The elimination of these reactions suggest a concerted non-synchronous five-membered cyclic transition state type of mechanism.

Muscle contraction involves the interaction of the myosin heads of the thick filaments with actin subunits of the thin filaments. Relaxation occurs when this interaction is blocked by molecular switches on these filaments. In many muscles, myosin-linked regulation involves phosphorylation of the myosin regulatory light chains (RLCs). Electron microscopy of vertebrate smooth muscle myosin molecules (regulated by phosphorylation) has provided insight into the relaxed structure, revealing that myosin is switched off by intramolecular interactions between its two heads, the free head and the blocked head. Three-dimensional reconstruction of frozen—hydrated specimens revealed that this asymmetric head interaction is also present in native thick filaments of tarantula striated muscle. Our goal in this study was to elucidate the structural features of the tarantula filament involved in phosphorylation-based regulation. A new reconstruction revealed intra- and intermolecular myosin interactions in addition to those seen previously. To help interpret the interactions, we sequenced the tarantula RLC and fitted an atomic model of the myosin head that included the predicted RLC atomic structure and an S2 (subfragment 2) crystal structure to the reconstruction. The fitting suggests one intramolecular interaction, between the cardiomyopathy loop of the free head and its own S2, and two intermolecular interactions, between the cardiac loop of the free head and the essential light chain of the blocked head and between the Leu305—Gln327 interaction loop of the free head and the N-terminal fragment of the RLC of the blocked head. These interactions, added to those previously described, would help switch off the thick filament. Molecular dynamics simulations suggest how phosphorylation could increase the helical content of the RLC N-terminus, weakening these interactions, thus releasing both heads and activating the thick filament.

In the present work, ultrasound assisted synthesis of NiS, CoS, NiMoS and CoMoS was studied. Solids thus obtained were characterized by X-ray diffraction, confocal microscopy, chemical analysis, surface area determinations, and their activities in thiophene and benzothiophene hydrodesulfurization (HDS) were also evaluated. It was found that NiMo catalyst was 5 and 2.4 times more active than NiS, in thiophene and benzothiophene HDS, respectively, while CoMo was 6.4 and 3.2 more active than CoS for the same reactions. It is proposed that the high activity for bimetallic solids is due to the precipitation of a mixed sulfide in nanometric size particles.

Many recent amphibian declines have been associated with chytridiomycosis, a cutaneous disease caused by the chytrid fungus Batrachochytrium dendrobatidis, but increasing evidence suggests that this pathogen may coexist with some species without causing declines. In the Venezuelan Andes, the disappearance of three anuran species during the late eighties was attributed to B. dendrobatidis. Recently, this pathogen was found to be prevalent in this region on the introduced American bullfrog, Lithobates catesbeianus. As a first step toward assessing the risk of amphibian communities to B. dendrobatidis in this region, we conducted a broad survey across multiple habitat types and an altitudinal gradient spanning over 2000 m. We diagnosed 649 frogs from 17 species using real time and conventional PCR assays, and recorded relevant abiotic characteristics of host habitats. Infection was detected in 10 native species of pond, stream and terrestrial habitats from 80—2600 m, representing nine new host records. L. catesbeianus was the most important reservoir with 79.9% of individuals infected and an average of 2299 zoospores. Among native frogs, Dendropsophus meridensis, an endangered species sympatric with L. catesbeianus, showed the highest infection prevalence and mean zoospore load (26.7%; 2749 zoospores). We did not detect clinical signs of disease in infected hosts; however, species such as D. meridensis may be at risk if environmental stress exacerbates vulnerability or pathogen loads. While surveillance is an effective strategy to identify highly exposed species and habitats, we need to understand species-specific responses to B. dendrobatidis to stratify risk in amphibian communities.

Se sintetizó nitruro de vanadio (VN) mediante la reducción carbotérmica de mezclas de óxido de vanadio (ex vanadato de amonio) y carbón activado en atmósfera de N₂. El método de disolución utilizado para la mezcla de los precursores NH₄VO₃ y C, permitió obtener VN de morfología uniforme con tamaño de cristalita submicrométrica, a temperaturas inferiores a aquellas utilizadas en procesos convencionales. El producto obtenido fue caracterizado por difracción de rayos X (DRX), microscopía electrónica de barrido (MEB), espectroscopia de fotoelectrones de rayos X (XPS) y área superficial-BET. Para posible aplicación en catálisis, el producto sintetizado fue evaluado en la hidrodesulfuración (HDS) de tiofeno a presión atmosférica y T = 400°C, encontrándose que la actividad catalítica de los sólidos sintetizados durante 120 min. a 1100ºC fue mayor a aquella de polvos de VN obtenidos con tratamientos térmicos más cortos.

It has be en synthesized vanadium nitride (VN) by carbothermal reduction of vanadium oxide (ex ammonium vanadate) and activated carbon mixtures in a N₂ atmosphere. The solution-derived precursor method used to mix NH₄VO₃ and C promoted the formation of submicrometer and morphologically uniform crystallites of VN at a lower temperature in comparison with conventional methods. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and BET-surface area. In order to consider catalytic uses the synthesized product has been evaluated in the reaction of hydrodesulfuration of thiophene under atmospheric pressure and T = 400°C. It was found that the catalytic activity of the heat treated solids during 120 min. at 1100ºC was larger than those of VN powders obtained at shorter heat treatment times.

In the present article we study asymptotic isometries and asymptotic conformal Killing motions of some anisotropic Bianchi cosmological models. We show that asymptotically isotropic homogeneous cosmological spaces can be covariantly studied and characterized using scalars constructed with the help the Killing equations. We exhibit some illustrative examples of space-times possessing asymptotic Killing collineations. We apply our results in order to discuss asymptotic symmetries associated with scalar cosmological perturbations.

The hoatzin is unique among known avian species because of thefermentative function of its enlarged crop. A small-bodied flyingforegut fermenter is a paradox, and this bird provides an interestingmodel to examine how diet selection and the gut microbiota contributeto maximizing digestive efficiency. Therefore, we characterizedthe bacterial population in the crop of six adult hoatzins capturedfrom the wild. A total of 1,235 16S rRNA gene sequences weregrouped into 580 phylotypes (67% of the pooled species richnesssampled, based on Good's coverage estimator, with C_ACE and Chao1estimates of 1,709 and 1,795 species-level [99% identity] operationaltaxonomic units, respectively). Members of 9 of the 75 knownphyla in Bacteria were identified in this gut habitat; the Firmicuteswere dominant (67% of sequences, belonging to the classes Clostridia,Mollicutes, and Bacilli), followed by the Bacteroidetes (30%,mostly in the order Bacteroidales), Proteobacteria (1.8%), andLentisphaerae, Verrucomicrobia, TM7, Spirochaetes, Actinobacteria,and Aminanaerobia (all less than 0.1%). The novelty in this ecosystemis great; 94% of the phylotypes were unclassified at the "species"level and thus likely include novel cellulolytic lineages

Diversos esfuerzos han sido dirigidos a fin de esclarecer los principales mecanismos de protección y recuperación en las infecciones virales agudas y el posible papel de las citocinas involucradas en la respuesta inmunitaria primaria inducida por una cepa epizoótica del virus de Encefalitis Equina Venezolana (EEV). En el presente estudio se determinaron las concentraciones de citocinas TH1 Interleucina-2 (IL-2) e Interferon-gamma (IFN-gamma), TH2 Interleucina-4 (IL-4), proinflamatorias (IL-1beta) y el Factor de Necrosis Tumoral -alfa (TNF-alpha) en suero y cerebro de ratones infectados con el virus de EEV a diferentes períodos de infección. Se utilizaron ratones NMRI albinos machos infectados con una suspensión (10 DL₅₀) de la cepa Guajira del virus de EEV, y un grupo control (sin infectar). En los días 1, 3 y 5 post-infección, se extrajo sangre completa de ratones para la obtención de suero y el cerebro previa perfusión, para la obtención de homogeneizados cerebrales. En ambas muestras se determinaron IL-2, IFN-gamma, IL-4, IL-1beta, y TNF-alpha por la técnica de ELISA. Se observó un incremento significativo (p less than 0,01) en suero y homogeneizados cerebrales al 1_er, 3_er y 5_to día post-infección en las concentraciones de IL-1beta, IFN-gamma y TNF-alpha, al compararlos con el grupo control. La cuantificación de IL-2 e IL-4, no arrojaron diferencias estadísticamente significativas al ser comparados con los controles. Estos resultados sugieren que la IL-1beta, IFN-gamma y TNF-alpha, podrían estar involucradas en la respuesta inmunitaria temprana al virus de EEV durante la infección primaria.

A multifractal random walk (MRW) is defined by a Brownian motion subordinated by a class of continuous multifractal random measures M[0, t], 0 Less than or egual t Less than or egual 1. In this paper we obtain an extension of this process, referred to as multifractal fractional random walk (MFRW), by considering the limit in distribution of a sequence of conditionally Gaussian processes. These conditional processes are defined as integrals with respect to fractional Brownian motion and convergence is seen to hold under certain conditions relating the self-similarity (Hurst) exponent of the fBm to the parameters defining the multifractal random measure M. As a result, a larger class of models is obtained, whose fine scale (scaling) structure is then analyzed in terms of the empirical structure functions. Implications for the analysis and inference of multifractal exponents from data, namely, confidence intervals, are also provided.

In order to study the genetic variability of Mycobacterium tuberculosis circulating in the Carabobo State at Venezuela, 317 strains of M. tuberculosis isolated from patients living in different health districts whose acid fast smears were positive, were included. Each strain was characterized by spoligotyping and the pattern compared with the national and worldwide SpolDB4.0 databases; 220 isolates (69.4%) were grouped in 24 clusters, being LAM the most common family (34%). In contrast to other Venezuelan regions, the most common Carabobo spoligotype was number 605, with 46 isolates (14.5%). In addition, there were 97 (30.6%) orphan spoligotypes, 19 of which are found in SpolDB4.0, and 78 non described. Co-infection with human immunodeficiency virus was detected in 11 patients (3.5%). These results show high genotypic variability of M. tuberculosis in the region, contributing with new information for a better understanding of tuberculosis transmission in Venezuela.

It is known that human syncytiotrophoblast (hSCT) actively transports more than 80% of the Ca²⁺ that goes from maternal to fetal circulation. Transepithelial transport of Ca²⁺ is carried out through channels, transporters and exchangers located in both microvillous (MVM) and basal (BM) plasma membranes. The plasma membrane Ca-ATPase (PMCA) is the most important mechanism of Ca²⁺ homeostasis control in the human placenta. In this work, we reexamined the distribution of PMCA in isolated hSCT of term placenta. The PMCA activity was determined in isolated hSCT plasma membranes. A partial characterization of the PMCA activity was performed, including an evaluation of the sensitivity of this enzyme to an in vitro induced lipid peroxidation. Expression of the PMCA in hSCT plasma membranes and tissue sections was investigated using Western blots and immunohistochemistry, respectively. Our study demonstrates, for the first time, a correlation between the activity and structural distribution of PMCA in both MVM and BM of hSCT. It also demonstrates a higher PMCA activity and expression in MVM as compared to BM. Finally, PMCA4 seems to be preferentially distributed in both hSCT plasma membranes, while PMCA1 is shown to be present in the hSCT homogenate. However, the membrane fractions did not show any PMCA1 labeling. Our results must be taken into account in order to propose a new model for the transport of calcium across the hSCT.

The evolutionary relationships among members of the cetacean family Delphinidae, the dolphins, pilot whales and killer whales, are still not well understood. The genus Sotalia (coastal and riverine South American dolphins) is currently considered a member of the Stenoninae subfamily, along with the genera Steno (rough toothed dolphin) and Sousa (humpbacked dolphin). In recent years, a revision of this classification was proposed based on phylogenetic analysis of the mitochondrial gene cytochrome b, wherein Sousa was included in the Delphininae subfamily, keeping only Steno and Sotalia as members of the Stenoninae subfamily. Here we investigate the phylogenetic placement of Sotalia using two mitochondrial genes, six autosomal introns and four Y chromosome introns, providing a total of 5,196 base pairs (bp) for each taxon in the combined dataset. Sequences from these genomic regions were obtained for 17 delphinid species, including at least one species from each of five or six currently recognized subfamilies plus five odontocete outgroup species. Maximum Parsimony, Maximum Likelihood and Bayesian phylogenetic analysis of independent (each fragment) and combined datasets (mtDNA, nuDNA or mtDNA+nuDNA) showed that Sotalia and Sousa fall within a clade containing other members of Delphininae, exclusive of Steno. Sousa was resolved as the sister taxon to Sotalia according to analysis of the nuDNA dataset but not analysis of the mtDNA or combined mtDNA+nuDNA datasets. Based on the results from our multi-locus analysis, we offer several novel changes to the classification of Delphinidae, some of which are supported by previous morphological and molecular studies.

The renal renin—angiotensin system plays a major role in determining the rate of chronic renal disease progression. Treatment with activators of the vitamin D receptor retards the progression of experimental chronic renal disease, and vitamin D is known to suppress the renin—angiotensin system in other organs. Here we determined if the beneficial effects of paricalcitol (19-nor 1,25-dihydroxyvitamin D₂) were associated with suppression of renin—angiotensin gene expression in the kidney. Rats with the remnant kidney model of chronic renal failure (5/6 nephrectomy) were given two different doses of paricalcitol thrice weekly for 8 weeks. Paricalcitol was found to decrease angiotensinogen, renin, renin receptor, and vascular endothelial growth factor mRNA levels in the remnant kidney by 30—50 percent compared to untreated animals. Similarly, the protein expression of renin, renin receptor, the angiotensin type 1 receptor, and vascular endothelial growth factor were all significantly decreased. Glomerular and tubulointerstitial damage, hypertension, proteinuria, and the deterioration of renal function resulting from renal ablation were all similarly and significantly improved with both treatment doses. These studies suggest that the beneficial effects of vitamin D receptor activators in experimental chronic renal failure are due, at least in part, to down-regulation of the renal renin-angiotensin system.

The validity of the concentrations of carbon and oxygen reported in formvar previously and the underlying assumption that these elements are uniformly distributed in our formvar films have been checked. New elastically scattered 13 MeV ⁶Li+¹²C and 13 MeV ⁶Li+¹⁶O cross-sections have been measured at 17.5°, 25° and 28°. By use of these cross-sections, carbon and oxygen concentrations, a factor of 10 higher than previously reported values, have been determined for the first time in our formvar backings with a dispersion per backing not greater than 7%.

A heterocatalytic model involving the graphite surface, which has been previously used for the surface formation of chemisorbed amino acids, is consistently extended to the synthesis of monocarboxylic acids and polyhydroxylated compounds. Extensive computations with semi-empirical and ab initio quantum chemical methods have been carried out to analyze reaction pathways on surface models of different sizes. The model assumes surface recombinations involving small functional groups. Polymerization is initiated by either a carboxyl (COOH) or a formyl (HCO) group that is anchored to the graphite surface through two chemisorption sites, and proceeds by the addition of mobile diffusors of the type CH_n (1n3) and CH_n'OH (0n^'2). Polymer length is determined by the competition between surface diffusion and hydrogenation. Some of the features observed in the laboratory regarding the surface self-assembly of monocarboxylic chains, in the organic inventory of star-forming regions and in carbonaceous meteorites can be addressed with the present approach.

Term placental villous fragments from normotensive pregnant women were incubated under hypoxia in order to induce lipid peroxidation of the placental plasma membranes and, consequently, to increase their release of lipid peroxide products into the incubation medium. The homogenates of the villous fragments were assayed for plasma membrane Ca-ATPase (PMCA) activity and TBARS. The incubation medium, after placental hypoxia, was used to incubate intact red blood cells (RBCs) from normotensive pregnant women. Similarly, intact RBCs from normotensive pregnant women were incubated with deproteinized blood plasma from normotensive pregnant women and women with preeclampsia. In all the cases, red cell ghosts were prepared from the incubated cells and assayed for PMCA and TBARS. The incubation of placental villous fragments under hypoxia led to an increase in the TBARS and a significant reduction in the PMCA activity of their homogenates, as compared to those of villous fragments incubated under normoxia. The exposure of intact RBCs from normotensive pregnant women either to the incubation medium of placental hypoxia or to deproteinized blood plasma from women with preeclampsia, caused a rise of the TBARS and a diminution of PMCA activity of the red cell ghosts. Inside-out vesicles were also prepared from intact RBCs incubated with the medium where the placental hypoxia was carried out. These vesicles were assayed for active calcium transport. Pretreatment of RBCs with the incubation medium of placental hypoxia led to a lower active calcium transport as compared to that of inside-out vesicles from RBCs without any preincubation. These results are in agreement with the idea that the RBCs can be peroxidized when passing through a highly oxidized medium, such as the placental intervillous space from women with preeclampsia. The peroxidized RBCs would contribute then to the propagation of lipid peroxidation from the placenta to nearby and far away tissues.

It is known that human syncytiotrophoblast (hSCT) actively transports more than 80% of the Ca²⁺ that goes from maternal to fetal circulation. Transepithelial transport of Ca²⁺ is carried out through channels, transporters and exchangers located in both microvillous (MVM) and basal (BM) plasma membranes. The plasma membrane Ca-ATPase (PMCA) is the most important mechanism of Ca²⁺ homeostasis control in the human placenta. In this work, we reexamined the distribution of PMCA in isolated hSCT of term placenta. The PMCA activity was determined in isolated hSCT plasma membranes. A partial characterization of the PMCA activity was performed, including an evaluation of the sensitivity of this enzyme to an in vitro induced lipid peroxidation. Expression of the PMCA in hSCT plasma membranes and tissue sections was investigated using Western blots and immunohistochemistry, respectively. Our study demonstrates, for the first time, a correlation between the activity and structural distribution of PMCA in both MVM and BM of hSCT. It also demonstrates a higher PMCA activity and expression in MVM as compared to BM. Finally, PMCA4 seems to be preferentially distributed in both hSCT plasma membranes, while PMCA1 is shown to be present in the hSCT homogenate. However, the membrane fractions did not show any PMCA1 labeling. Our results must be taken into account in order to propose a new model for the transport of calcium across the hSCT.

We have proposed a tentative model for fluid secretion in Rhodnius Malpighian Tubules (MT): (i) At the basolateral cell membrane, fundamental are a Na⁺/K⁺/2Cl^- cotransporter and a Cl^-—HCO^-₃ exchanger; of intermediate importance, the Na⁺/K⁺-ATPase, Cl^- channels and Rp-MIP water channels; K⁺ channels play a lesser role; (ii) at the apical cell membrane, most important are a K⁺/Cl^- cotransporter, a V—H⁺-ATPase, and a Na⁺/H⁺ exchanger; a urate-anion exchanger and K⁺ channels are less important while Cl^- channels are not important. Resting control of [Na⁺]_i has been attributed to the action of the Na⁺/K⁺ ATPase. A 2nd Na⁺ ATPase (Pump II) was described in the mammalian kidney, in MT, and other tissues. This ATPase does not require K⁺, is Ouabain insensitive and is inhibited by Furosemide (F). F is known to inhibit MT secretion through inhibition of the Na⁺/K⁺/2Cl^- cotransporter, and it seems difficult to ascertain whether F acts also through Pump II. As a further stage on this line of studies we have measured [Na⁺]_i in MT using microfluorescence methods under unstimulated conditions. We have found that: (a) Ouabain, up to 0.1 mM does not alter [Na⁺]_i; (b) up to 1 mM F increases [Na⁺]_i; (c) this increase is even sharper in the presence of Ouabain, and is observed even in the absence of [Cl^-]_o; (d) 0.1 mM Amiloride reverts this increase. After stimulation some increase in [Na⁺]_i is observed that becomes sharper with F. These results are compatible with a basolateral Na⁺/K⁺ ATPase with a stronger Pump II that extrudes Na⁺ basolaterally; and a Na⁺/K⁺/2Cl^- cotransporter and amiloride sensitive Na⁺. These experiments were partly supported by Fonacit F2005000222 and Fundación Polar.

Renal tubulointerstitial inflammation is a constant feature of experimental models of hypertension and likely plays a role in the pathogenesis of salt-sensitive hypertension. We have previously raised the possibility that the immune cell infiltration is driven by a low grade autoimmune reactivity directed to or facilitated by renal heat shock protein over expression. The present studies were done to gain insight on possible cell-mediated immune mechanisms in experimental hypertension by determining the renal expression of HSP70 and the proliferation index of T lymphocytes cultured with HSP70. We studied male Sprague-Dawley rats with inhibition of nitric oxide (NO) synthase (n=6), protein overload (PO) proteinuria (n=7) and short-term angiotensin II (Ang II) infusion (n=5), and their corresponding control groups. Each model was associated with 2 to 4 fold increase (P less Than 0.05-0.001) in renal HSP70 expression. T cells isolated from the spleens demonstrated a significant two- to nine-fold response compared to controls (P less Than 0.05 or lower for each comparison) when cultured with HSP70. These studies suggest that autoimmunity to stress proteins is involved in the sustained low-grade inflammatory infiltration that occurs in the tubulointerstitial areas of the hypertensive kidney.

Abstract: The title compound, C₂₇H₃₁N₃, has E substitution at each imine double bond where the two N atoms adopt a trans-trans relationship. The benzene rings are twisted out of the mean plane of the pyridine ring; the mean planes of the aromatic groups are rotated by 63.0 (1) and 72.58 (8)°. The crystal structure is sustained mainly by C-H and hydrophobic methyl-methyl interactions.

A series of elementary parametric functionals (EPFs) for resonance integral, electron-electron repulsion, electron-nucleus attraction, core-core interaction, and bond correlation correction were included in the new version of CATIVIC method [Int J Quantum Chem 2004, 96, 321]. In the present work, a systematic way to improve the precision of parametric quantum methods (PQMs) by using several EPFs in the parameterization of a set of molecules is proposed. Based on the fact that a linear combination of elementary functionals from the exact Hamiltonian is also a functional, a linear combination of EPFs has been proved that can enhance the accuracy of PQMs by considering the convex condition. A general formulation of simulation techniques for molecular properties is presented and a formal extension of the minimax principle to PQMs is also considered.

Crotalus durissus cumanensis is an endemic rattlesnake found in Venezuela and Colombia. In this study, a comparative analysis of hemorrhagic, coagulation and fibrino(geno)lytic activities in the presence or absence of protease inhibitors was performed with venoms of the same species Crotalus durissus cumanensis, from seven geographical regions of Venezuela (Lagunetica, Santa Teresa, Carrizales, Guarenas, Anzoátegui, Margarita and Maracay). Lagunetica, Carrizales and Anzoátegui venoms induced hemorrhagic activity. All venoms, except that of snakes from the Carrizales region presented thrombin-like activity, which was inhibited completely by phenylmethanesulfonyl fluoride and ethylene glycol-bis-N, N,N',N'-tetraacetic acid. This effect of the latter could be explained by the high chelant calcium effect, which is a cofactor for the fibrin polymerization process. Soybean trypsin inhibitor was effective on Santa Teresa venom. Antithrombin III/Hep complex and phenantroline partially inhibited this activity in all venoms except Margarita and Anzoátegui, respectively, which were not inhibited. Serine protease inhibitors were more effective against thrombin, kallikrein and plasmin-like amidolytic activities. Additionally, metalloprotease inhibitors significantly inhibited the t-PA-like amidolytic activity and completely the hemorrhagic and fibrino(geno)lytic activities. In conclusion, the thrombin-like activity observed in these venoms was partially reduced by serine protease inhibitors, indicating the possible presence of catalytic domains in those enzymes that do not interact with these inhibitors. Using protease inhibitors on venom hemostatic activities could contribute to our understanding of the active components of snake venom on the hemostatic system, and further reveal the intraspecies variation of venoms, which is important in the treatment of envenomation, and in addition represents an interesting model for the study of venom in hemostasis.

In a recent article, Liao et al 1 used mice lacking the CC chemokine receptor 2 (CCR2) to test the hypothesis that CCR2 activation plays an important role in the renal damage induced by angiotensin infusions. In their elegant article, it was also shown that CCR2^-/- mice and CCR2^+/+ mice developed similar elevations of blood pressure despite significantly different levels of oxidative stress and tubulointerstitial inflammation. The authors concluded that CCR2, oxidative stress, and renal inflammation play an important role in the development of hypertensive nephropathy but not in hypertension. Although the conclusions of the article are logical, they apply to conditions characterized by a high level of circulating angiotensin II. The experiments of Liao et al 1 were done during angiotensin infusion, and the potent hemodynamic actions of circulating angiotensin II make it unlikely that any modification of other contributing factors would result in a significant amelioration of hypertension. Interestingly, however, the infusion of angiotensin II can also cause salt-sensitive hypertension after the infusion is stopped. In this setting, the salt-sensitive hypertension has been shown to be attributed to the induction of renal microvascular disease, tubulointerstitial inflammation, and the generation of local oxidative stress and intrarenal angiotensin II.² The triad of renal inflammation, oxidative stress, and local angiotensin II production is interlacing and interdependent.3 Under these conditions, immunosuppression with mycophenolate does prevent inflammation and hypertension, although this same treatment has no effect on blood pressure during the infusion of angiotensin II.² Salt-sensitive hypertension is, of course, a condition characterized by low plasma renin and high renal angiotensin.⁴ Several studies from us and others have demonstrated that immune suppressive drug therapy is associated with improvement of hypertension, oxidative stress, and intrarenal angiotensin II activity in the Dahl salt-sensitive rat, in the spontaneously hypertensive rat, and in practically all of the experimental models of salt-dependent hypertension and in humans with grade I essential hypertension (reviewed in Reference 5). Thus, whereas inflammation may not have a role in blood pressure in animals during the infusion of pharmacological doses of angiotensin II, the evidence is mounting that intrarenal inflammation has a central role in the pathogenesis of salt-sensitive hypertension.

In the present work, a study of the effect of the surfactant nature on the synthesis of polymethylmethacrylate (PMMA) obtained by high frequency ultrasonic radiation and redox initiation is presented. The surfactants used were an anionic: sodium lauryl sulfate (SLS) and a nonionic: nonylphenol etoxilated. Different morphologies, particle size, and microstructures were obtained depending on the surfactant concentration (0.5, 1.0, 1.5, and 2.0)%. The highest conversion values of PMMA were obtained with SLS, resulting in a highly syndiotactic polymer. High frequency ultrasound is very efficient when ionic surfactants are used. However, for nonionic surfactants ultrasonic irradiation is very inefficient to initiate polymerization, in this case the effect of redox initiation was very marked increasing polymerization conversion. For this, surfactant blends of PMMA/PEO were obtained when redox initiation was used together with high frequency ultrasound.

Neurodegeneration in Alzheimer's disease (AD) has been linked to intracellular accumulation of misfolded proteins and dysregulation of intracellular Ca²⁺. In the current work, we determined the contribution of specific Ca²⁺ pathways to an alteration in Ca²⁺ homeostasis in primary cortical neurons from an adult triple transgenic (3xTg-AD) mouse model of AD that exhibits intraneuronal accumulation of ß-amyloid proteins. Resting free Ca²⁺ concentration ([Ca²⁺]_i), as measured with Ca²⁺-selective microelectrodes, was greatly elevated in neurons from 3xTg-AD and APP_SWE mouse strains when compared with their respective non-transgenic neurons, while there was no alteration in the resting membrane potential. In the absence of the extracellular Ca²⁺, the [Ca²⁺]_i returned to near normal levels in 3xTg-AD neurons, demonstrating that extracellular Ca²⁺contributed to elevated [Ca²⁺]_i. Application of nifedipine, or a non-L-type channel blocker, SKF-96365, partially reduced [Ca²⁺]_i. Blocking the ryanodine receptors, with ryanodine or FLA-365 had no effect, suggesting that these channels do not contribute to the elevated [Ca²⁺]_i. Conversely, inhibition of inositol trisphosphate receptors with xestospongin C produced a partial reduction in [Ca²⁺]_i. These results demonstrate that an elevation in resting [Ca²⁺]_i, contributed by aberrant Ca²⁺entry and release pathways, should be considered a major component of the abnormal Ca²⁺ homeostasis associated with AD.

Triethyl orthoacetate and triethyl orthopropionate were pyrolyzed in a static system over the temperature range of 291-351°C and pressure range of 80-170 Torr. The elimination reactions of these orthoesters in seasoned vessels are homogeneous, unimolecular, and follow a first-order rate law. The reaction products are ethanol, ethylene and the corresponding ethyl ester. The Arrhenius expressions of these eliminations were found as follow: for triethyl orthoacetate, log k₁ (s^-1) = (13.76 ± 0.09) - (187.6 ± 1.1) kJ mol^-1 (2.303 RT)^-1 (r = 0.9993), and for triethyl orthopropionate, log k₁ (s^-1) = (13.63 ± 0.07) - (193.3 ± 1.8) kJ mol^-1 (2.303 RT)^-1 (r = 0.9992). A reasonable mechanism of these elimination is to consider that the COCH₂CH₃ bond, as C^+- OCH₂CH₃ in the TS, is the rate-determining step. The nucleophilicity of the oxygen atom of OCH₂CH₃ may abstract the hydrogen of the adjacent CH bond for a four-membered cyclic structure to give the corresponding unsaturated ketal. The unstable ketal intermediate decomposes, in a six-membered cyclic transition state, into ethylene and the corresponding ethyl ester.

The mechanisms of the gas phase elimination of N,N-dimethylglycine, picolinic acid, and N-phenylglycine and their ethyl esters have been examined at Möller-Plesset MP2/6-31G (d, p) level of theory. The ethyl esters of these 2-amino carboxylic acids produce the corresponding amino carboxylic acid and ethylene in a rate-determining step. However, the unstable intermediate amino carboxylic acid rapidly decarboxylate to give the corresponding amino compound. These calculations imply a concerted, semi-polar six-membered cyclic transition state type of mechanism for the ethyl esters, and a non-synchronous five-membered cyclic transition state for the amino acids decarboxylation. The present results support previous mechanistic consideration of the elimination of the above-mentioned compounds in the gas phase

Animal trypanosomosis is one of the most severe constraints to agricultural development in sub-Saharan Africa and is also an important disease of livestock in Latin America and Asia. The causative agents are various species of protozoan parasites belonging to the genus Trypanosoma, among which T. congolense and T. evansi are the major pathogenic species. The extracellular position of trypanosomes obliges us to consider both the parasite and its excreted/secreted factors in the course of the physiopathologic process. The advent of proteomics led us to propose a comparative approach of the proteome (i.e., the whole parasite content) and the secretome (i.e., naturally excreted/secreted molecules) of T. congolense and T. evansi with particular attention to common and specific molecules between strains of differing virulence and pathogenicity. The molecular identification of differentially expressed trypanosome molecules correlated with either the virulence process or the pathogenicity will provide new potential molecular targets for improved field diagnosis and chemotherapy of animal trypanosomosis.

The bivalve mollusks Tivela mactroides and Crassostrea rhizophorae are abundant along the Venezuelan coast and are widely consumed as seafood. The globally important seagrass Thalassia testudinumis also abundant in Venezuelan. We report the concentrations of Cd, Cr, Cu, Ni, V and Zn in the soft parts of Tivela mactroides and Thalassia testudinum, and the concentrations of Cd, Cr, Cu and Ni in the soft parts of Crassostrea rhizophorae, in seven Venezuelan coastal sites. Metal concentrations were determined by Inductively Coupled Plasma Optical Emission Spectroscopy. Statistical analysis (one-way ANOVA) indicated that the organisms had different levels of metal bioaccumulation, and might be used as biomonitors for trace metals. Significant site-specific differences were found for the elements Cd, Cr, Ni and V in Tivela mactroides; Cd and Cr in Crassostrea rhizophorae; and V in Thalassia testudinum tissue.

Stenocereus griseus y Cereus repandus son dos de las cactáceas columnares más abundantes y ampliamente distribuidas en las regiones áridas y semiáridas de Venezuela. A pesar de su valor como especies clave para la fauna silvestre y de su potencial valor económico, la información sobre su actividad reproductiva y capacidad de regeneración es muy limitada. Dichos aspectos fueron evaluados en poblaciones naturales de Padre Diego, estado Lara y la Península de Paraguaná , estado Falcón. Estos cactus poseen patrones reproductivos temporalmente amplios y niveles de fecundidad elevados ( S. griseus : 44.225 semillas/ind , C. repandus : 322.749 semillas/ind ), que les confieren grandes ventajas para su regeneración natural y propagación. Estas especies dependen de plantas nodriza para su establecimiento, presentando los porcentajes más elevados de supervivencia bajo la sombra de árboles. En condiciones naturales, estas plantas rinden media tonelada de pulpa de fruta por hectárea.

Stenocereus griseus and Cereus repandus are two of the most abundant and widely distributed columnar cacti in the arid and semiarid regions of Venezuela. Despite their value as keystone species for wildlife and their potential economic value, information on their reproductive activity and regeneration capacities is quite limited. These aspects were evaluated in natural populations from Padre Diego, Lara State, and Paraguana Peninsula, Falcon State. These cacti have broad time windows for reproduction and considerably high fecundity levels ( S. griseus : 44,225 seeds/ind , C. repandus : 322,749 seeds/ind ), which confer them great advantages in terms of natural regeneration and propagation. These species depend on nurse plants for their establishment. The highest percentages of survival occurred under the shadow of trees. Under natural conditions, these species can produce half a ton of fruit pulp per hectare.

The 2 major challenges currently confronting the International Union for Conservation of Nature (IUCN) with regard to the ‘red listing’ process are the taxonomic, and the geographic growth of the data base. Taxonomic growth refers to the objective of gradually assessing the risk of extinction of all the world’s species and periodically repeating such assessments. Geographic growth refers to the increasing number of people around the world interested in performing extinction risk assessments for various groups of organisms in their region or country. The taxonomic challenge, although a large and demanding task, can be addressed by expanding and strengthening the networks of experts organized within the IUCN Species Survival Commission (SSC), which represents a significant scaling-up of a well-developed, known model. However, no current structure within the IUCN has the mandate to address the geographic challenge; this requires the creation of new structures or mechanisms. At least 5 key activities must be implemented to effectively integrate the diffuse network of national assessors into the global red listing process: (1) large-scale publicizing of the Guidelines for Application of IUCN Red List Criteria at Regional Levels, and encouraging the work of national assessors; (2) establishing the IUCN Species Programme as the primary trainer and certifier of multipliers; (3) delegating the majority of training to national institutions; (4) creating a virtual data clearing house for national red lists, seamlessly linked to the global list; and (5) consolidating the IUCN Species Programme as the primary endorser of national red list assessments. Hundreds of regional and national red lists will probably be produced in the next decade using the IUCN Red List Categories and Criteria, particularly because they are now recognized by international agreements such as the 2010 biodiversity target of the Convention on Biological Diversity and the United Nation’s General Assembly Millennium Development Goals. By catalyzing this process, the IUCN would expand the information on the world’s threatened species, while strengthening local scientific capacity for generating and using these data to support conservation action.

2-acetyl furanonaphthoquinone (FNQ) is a naturally occurring drug with enhanced toxicity versus glucose-starved tumor cells, which frequently show topoisomerase II drug resistance. Since loss of p53 tumor suppressor function or overexpression of the antiapoptotic bcl-2 gene can decrease susceptibility to some cancer therapies, we now investigated the effect of FNQ against genetically matched C8161 melanoma cell lines transduced to express unequal levels of Bcl-2, or engineered to harbour a functional wt p53 for comparison with dominant-negative mutant p53 R175H. Cells with differing p53 genotype showed susceptibility to FNQ. However, this response was attenuated in those overexpressing mutant p53, although a brief p53 induction was early seen in FNQ-treated wt p53 cells. Cells susceptible to FNQ showed cleavage of anti-apoptotic Mcl-1, sustained activation of the c-Jun N-terminal Kinase (p-JNK), and apoptosis-associated PARP fragmentation, all of which were counteracted in bcl-2 overexpressing cells. Suppression of JNK activation with the specific inhibitor, SP600125 also prevented FNQ-mediated cell death. Our data suggests that Bcl-2, persistent JNK phosphorylation and cleavage of anti-apoptotic Mcl-1 are key events controlling susceptibility to FNQ.

Worldwide, many large mammals are threatened by poaching. However, understanding the causes of poaching is difficult when both hunter and hunted are elusive. One alternative is to apply regression models to opportunistically-collected data but doing so without accounting for inherent biases may result in misleading conclusions. To demonstrate a straightforward method to account for such biases, and to guide further research on an elusive Vulnerable species, we visualized spatio-temporal poaching patterns in 844 Andean bear Tremarctos ornatus presence reports from the Cordillera de Mérida, Venezuela. To create maps of poaching risk we fitted two logistic regression models to a subset of 287 precisely georeferenced reports, one ignoring and one including spatial autocorrelation. Whereas the variance explained by both models was low, the second had better fit and predictive ability, and indicated that protected status had a significant positive effect on reducing poaching risk. Poaching risk increased at lower altitudes, where all indicators of human disturbance increased, although there was scant evidence that human-bear conflicts are a major direct trigger of poaching events. Because highest-risk areas were different from areas with most bear reports, we speculate that hunting may be driven by opportunistic encounters, rather than by purposeful searches in high-quality bear habitat. Further research comparing risk maps with bear abundance models and data on poaching behaviour will be invaluable for clarifying poaching causes and for identifying management strategies.

The family Meruidae has been established recently for the newly discovered species Meru phyllisae Spangler %26amp; Steiner, 2005 from Southern Venezuela. These beetles are morphologically highly distinct and at a body length of 0.8 mm represent the perhaps smallest individuals of Adephaga. Here, we use DNA sequence data to place this enigmatic taxon relative to other aquatic groups in this suborder. Meruidae was most closely associated with Noteridae, supporting a previous analysis of morphological structures which had suggested this sister relationship, albeit with weak support. While different alignment strategies did not affect the topology, the precise placement of Meruidae was affected by the choice of tree reconstruction method. Bayesian inference suggests a sister relationship of Meruidae + Noteridae, while parsimony analyses retrieve Meruidae + Notomicrus (a basal noterid genus), which combined are the sister group of all remaining Noteridae. Considering morphological evidence, the former placement appears more plausible.

We evaluated whether the blockade of the proinflammatory transcriptionfactor NF-B would modify the oxidative stress, inflammation,and structural and hemodynamic alterations found in the kidneyas a result of massive proteinuria. Twenty male Sprague-Dawleyrats were injected with 2 g of BSA intraperitoneally daily for2 wk. Ten of them received in addition the inhibitor of NF-Bactivation pyrrolidine dithiocarbamate (PDTC; 200 mg·kg^—1·day^—1sc) and the rest received vehicle. Seven rats that receivedintraperitoneal saline were used as controls. Glomerular hemodynamicswere studied after 14 days. Markers of oxidative stress (NF-Bsubunit p65+ cells, 3-nitrotyrosine, and 4-hydroxynonenal),inflammation (cortical CD68+ cells and NOS-II), and afferentarteriole damage were assessed by immunohistochemistry and morphometry.Activity of antioxidant enzymes superoxide dismutase, catalase,glutathione peroxidase, and glutathione reductase was evaluatedin renal cortex and medulla. Albumin overload induced massiveproteinuria, oxidative stress with reduced activity of antioxidantenzymes, NF-B activation, inflammatory cell infiltration, asignificant presence of proteinaceous casts, systemic and glomerularhypertension, as well as arteriolar remodeling. Treatment withPDTC prevented or improved all of these findings. In this modelof nephrotic syndrome, we demonstrate a key role for oxidativestress and inflammation in causing systemic and glomerular hypertensionand proteinuria. Oxidative stress and inflammation may havea key role in accelerating renal injury associated with intenseproteinuria.

We address hysteresis of three-dimensional polydisperse granular packs, comparing macro- and microscopic viewpoints, to reveal their elastic/inelastic mechanics and force network anisotropy. During the uniaxial loading-unloading cycle of an appropriately prepared pack, one can decompose the force network into weak and strong subnetworks. The first stages of loading exhibit arching, where all the fabric displays negative anisotropy. For later stages, the strong (weak) network shows positive %1negativeanisotropy. On unloading, the force network progresses to a fabric wide hydrostatic point, where the anisotropies of the weak and strong subnetworks switch signs. During the loading stage, a Mohr circle analysis permits the identification of a well-defined macroscopic internal friction angle, whose value is larger than that of grain-grain interactions. To analyze unloading, a generalized local Coulomb-friction argument predicts a continuously changing friction angle, that vanishes at the hydrostatic point. A suggestive interplay between microscopic friction and fabric structure, at different loding stages, is proposed as the mechanism for the emergence of a macro internal%26nbsp;%26nbsp; friction angle.

In this article, we study the problem of recovering the unknown solution of a linear ill-posed problem, via iterative regularization methods, from a statistical point of view. The basic purpose of the paper is to develop adaptive model selection techniques for determining the regularization parameters, i.e., the iteration index. We assume observations are taken over a fixed grid and we consider solutions over a sequence of finite-dimensional subspaces. Based on concentration inequalities techniques, we derive non-asymptotic optimal upper bounds for the mean square error of the proposed estimator

2-acetyl furanonaphthoquinone (FNQ) is a naturally occurring drug with enhanced toxicity versus glucose-starved tumor cells , which frequently show topoisomerase II drug resistance. Since loss of p53 tumor suppressor function or overexpression of the anti-apoptotic bcl-2 gene can decrease susceptibility to some cancer therapies , we now investigated the effect of FNQ against genetically matched C8161 melanoma cell lines transduced to express unequal levels of Bcl-2 , or engineered to harbour a functional wt p53 for comparison with dominant-negative mutant p53 R175H .Cells with differing p53 genotype showed susceptibility to FNQ. However , this response was attenuated in those overexpressing mutant p53 , although a brief p53 induction was early seen in FNQ —treated wt p53 cells . Cells susceptible to FNQ showed cleavage of anti-apoptotic Mcl-1, sustained activation of the c-Jun N-terminal Kinase ( p-JNK) , and apoptosis-associated PARP fragmentation , all of which were counteracted in bcl-2 overexpressing cells. Suppression of JNK activation with the specific inhibitor , SP600125 also prevented FNQ —mediated cell death. Our data suggests that Bcl-2 , persistent JNK phosphorylation and cleavage of anti-apoptotic Mcl-1 are key events controlling susceptibility to FNQ.

Escape from an unstable fixed point in a time-delayed dynamical system in the presence of additive white noise depends on both the magnitude of the time delay, Tau , and the initial function. In particular, the longer the delay the smaller the variance and hence the slower the rate of escape. Numerical simulations demonstrate that the distribution of first passage times is bimodal, the longest first passage times are associated with those initial functions that cause the greatest number of delayed zero crossings, i.e. instances where the deviations of the controlled variable from the fixed point at times t and t - Tau have opposite signs. These observations support the utility of control strategies using pulsatile stimuli triggered only when variables exceed certain thresholds.

We report the use of the fluorescent dye CalciumOrange-5N (CaOr-5N) as a specific mitochondria Ca²⁺ marker in enzymatically dissociated mouse FBD muscle fibers. Using laser scanning confocal microscopy and the dyes Mitotracker Green (MTG), di-8-ANEPPS and endoplasmic reticulum tracker green (ERTG), we determined the relative position of mitochondria, transverse tubules and sarcoplasmic reticulum in the sarcomere. Comparison with electron micrographies showed that mitochondria are mostly present at both sides of Z lines and near the triads located at the A-I band border. CaOr-5N fluorescence was mainly distributed in mitochondria, highly co-localised with MTG and basically excluded from the A band space. ERTG localised mostly between the two t-tubules present in each sarcomere. We studied the effect of the protonophore FCCP using CaOr-5N to measure mitochondrial Ca²⁺ and JC-1 dye to measure mitochondria inner membrane potential (?? _m). After FCCP treatment, the CaOr-5N fluorescence diminished by about 33% in 80 s, while JC-1 fluorescence diminished by 36% in 200 s. Our results show the loss of Ca²⁺ from mitochondria when ??_m is depolarised and demonstrate the usefulness of CaOr-5N to mark mitochondrial [Ca²⁺]_m.

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