Impact on clinical practice of the preoperative screening of Covid-19 infection in surgical oncological patients. Prospective cohort study.

BACKGROUND: In the oncological patient, an COVID-19-Infection, whether symptomatic or asymptomatic, a surgical procedure may carry a higher postoperative morbidity and mortality. The aim of this study was to describe the impact on clinical practice of sequential preoperative screening for COVID-19-infection in deciding whether to proceed or postpone surgery. METHODS: Prospective, cohort study, based on consecutive patients' candidates for an oncological surgical intervention. Sequential preoperative screening for COVID-19-infection: two-time medical history (telematic and face-to-face), PCR and chest CT, 48 h before of surgical intervention. COVID-19-infection was considered positive if the patient had a suggestive medical history and/or PCR-positive and/or CT of pneumonia. RESULTS: Between April 15th and May 4th, 2020, 179 patients were studied, 97 were male (54%), mean (sd) age 66.7 (13,6). Sequential preoperative screening was performed within 48 h before to surgical intervention. The prevalence of preoperative COVID-19-infection was 4.5%, 95%CI:2.3-8.6% (8 patients). Of the operated patients (171), all had a negative medical history, PCR and chest CT. The complications was 14.8% (I-II) and 2.5% (III-IV). There was no mortality. The hospital stay was 3.1 (sd 2.7) days.In the 8 patients with COVID-19-infection, the medical history was suggestive in all of them, 7 presented PCR-positive and 5 had a chest CT suggestive of pneumonia. The surgical intervention was postponed between 15 and 21 days. CONCLUSION: Preoperative screening for COVID-19-infection using medical history and PCR helped the surgeon to decide whether to go ahead or postpone surgery in oncological patients. The chest CT may be useful in unclear cases.

Primera evidencia de Chlamydia psittaci en huron sable (Mustella putorios furo) en Venezuela / First evidence of Chlamydia psittaci in the sable ferret (Mustella putorios furo) in Venezuela

RESUMEN Chlamydia psittaci (Cp) es una bacteria intracelular obligada transmitida a través de aerosoles derivados de secreciones nasales y ópticas, tejidos, heces y plumas. Comúnmente es identificada en aves, sin embargo, han emergido genotipos capaces de infectar nuevos reservorios mamíferos. Por ello, se buscó ADN de Cp en muestras de cinco individuos de Mustella putorios furo y un hisopado cloacal de un individuo de Colinus cristatus en cautiverio en Venezuela a través de la PCR-anidada, amplificando un segmento del gen 16S ADNr. Se demostró la presencia de Cp en un Colinus cristatus con signos de clamidiosis y en cuatro Mustella putorios furo sin signos clínicos de clamidiosis. Se indica un posible nuevo reservorio para Cp, donde el contacto con productos de excreción de Colinus cristatus con manifestaciones clínicas de clamidiosis, hacinamiento, inadecuada ventilación, contacto con productos de excreción de Psittaciformes y condiciones sanitarias deficientes favoreció la infección por Cp. Se desconoce el total de reservorios de Cp, por ello la notificación de los aislados permite el entendimiento, distribución y diversidad de agentes clamidiales en fauna silvestre y en cautiverio.

ABSTRACT Chlamydia psittaci (Cp) is an obligate intracellular bacterium, transmitted through aerosols from nasal and optic secretions, tissues, feces, and feathers. Although commonly identified in birds, genotypes have emerged that can infect new mammalian reservoirs. Therefore, of rectal swabs samples of five Mustella putorios furo individuals and a cloacal swab sample of Colinus cristatus in captivity, in Venezuela, were tested for Cp, using the nested PCR amplifying a segment of the 16S rDNA gene. The presence of Cp was found in four asymptomatic Mustela putorios furo and one symptomatic Colinus cristatus for avian chlamydiosis, indicating a new potential reservoir for Cp. The contact with excretions of infected Colinus cristatus and Psittaciformes, as well as overcrowding, inadequate ventilation, and inadequate sanitary conditions can favor Cp infection. The total number of Cp reservoirs is unknown; therefore, the noting and molecular characterization of isolates enable the understanding, distribution, and diversity of chlamydial agents in wildlife and animals in captivity.

Extracellular Signal-Regulated Kinase 2 and CHOP Restrict the Expression of the Growth Arrest-Specific p20K Lipocalin Gene to G0.

The activation of the growth arrest-specific (gas) p20K gene depends on the interaction of C/EBPß with two elements of a 48-bp promoter region termed the quiescence-responsive unit (QRU). Here we identify extracellular signal-related kinase 2 (ERK2) as a transcriptional repressor of the p20K QRU in cycling chicken embryo fibroblasts (CEF). ERK2 binds to repeated GAAAG sequences overlapping the C/EBPß sites of the QRU. The recruitment of ERK2 and C/EBPß is mutually exclusive and dictates the expression of p20K. C/EBP homologous protein (CHOP) was associated with C/EBPß under conditions promoting endoplasmic reticulum (ER) stress and, to a lesser extent, in cycling CEF but was not detectable when C/EBPß was immunoprecipitated from contact-inhibited cells. During ER stress, overexpression of CHOP inhibited p20K, while its downregulation promoted p20K, indicating that CHOP is also a potent inhibitor of p20K. Transcriptome analyses revealed that hypoxia-responsive genes are strongly induced in contact-inhibited but not serum-starved CEF, and elevated levels of nitroreductase activity, a marker of hypoxia, were detected at confluence. Conditions of hypoxia (2% O2) induced growth arrest in subconfluent CEF and markedly stimulated p20K expression, suggesting that the control of proliferation and gas gene expression is closely linked to limiting oxygen concentrations associated with high cell densities.

Involvement of G-quadruplex structures in regulation of human RET gene expression by small molecules in human medullary thyroid carcinoma TT cells.

The RET (rearranged during transfection) proto-oncogene encodes a receptor tyrosine kinase for members of the glial cell line-derived neurotrophic factor family of extracellular signaling molecules. The activating germline point mutations in the RET, which are known to induce oncogenic activation of RET tyrosine kinase, are associated with the development of medullary thyroid carcinoma (MTC) and pathogenesis of multiple endocrine neoplasia type 2 (MEN2). The polypurine/polypyrimidine tract in the proximal promoter region of the human RET gene (-51 to -33 relative to transcription start site) is essential for basal transcriptional activity of this gene. This tract consists of a guanine-rich sequence containing five runs of at least three contiguous guanines separated by one or more bases, conforming to a general motif capable of forming an intramolecular G-quadruplex. Here, we show that specific G-quadruplex structures formed in the RET promoter region act to repress the transcription of this gene, and transcription of this gene can be controlled by ligand-mediated G-quadruplex stabilization. In this study, NSC194598, a derivative of indeno[1,2,3-de]quinazoline, was found to be a novel G-quadruplex interactive agent that interfered with transcriptional activation of mutated RET gene in human medullary thyroid carcinoma TT cells. This compound significantly reduced endogenous RET protein levels and increased apoptosis in these cells. Our results provide further support for the idea that G-quadruplex structures may have a critical role in transcriptional regulation of the RET gene in vivo, providing insight into a novel strategy for transcriptional repression of this gene by small molecules.

Diversity and composition of dengue virus type 2 in Venezuela.

Dengue is a mosquito-borne disease caused by four closely related dengue virus (genus Flavivirus)serotypes (DENV-1­4). The clinical outcomes vary from mild febrile illness to life-threatening haemorrhagic manifestations. DENVs are endemic in the tropics and subtropics globally and currently no specific treatment or vaccines are available. In Venezuela, the American-Asian genotype of DENV-2 is the most prevalent and has been associated with severe disease outcomes.We aimed to follow-up the molecular epidemiology of DENV-2 in Venezuela to investigate if the evolution of the virus has remained the same throughout time or if the same dynamics documented in Brazil (hyperendemic co-circulation) also occurred. The results show that whereas the epidemiology of DENV in several endemic areas is characterized by serotype replacements through time, in Venezuela the American-Asian genotype DENV-2 has evolved into several genetic lineages and has remained in hyperendemic co-circulation with the other serotypes.

Wildfires in bamboo-dominated Amazonian forest: impacts on above-ground biomass and biodiversity.

Fire has become an increasingly important disturbance event in south-western Amazonia. We conducted the first assessment of the ecological impacts of these wildfires in 2008, sampling forest structure and biodiversity along twelve 500 m transects in the Chico Mendes Extractive Reserve, Acre, Brazil. Six transects were placed in unburned forests and six were in forests that burned during a series of forest fires that occurred from August to October 2005. Normalized Burn Ratio (NBR) calculations, based on Landsat reflectance data, indicate that all transects were similar prior to the fires. We sampled understorey and canopy vegetation, birds using both mist nets and point counts, coprophagous dung beetles and the leaf-litter ant fauna. Fire had limited influence upon either faunal or floral species richness or community structure responses, and stems <10 cm DBH were the only group to show highly significant (p = 0.001) community turnover in burned forests. Mean aboveground live biomass was statistically indistinguishable in the unburned and burned plots, although there was a significant increase in the total abundance of dead stems in burned plots. Comparisons with previous studies suggest that wildfires had much less effect upon forest structure and biodiversity in these south-western Amazonian forests than in central and eastern Amazonia, where most fire research has been undertaken to date. We discuss potential reasons for the apparent greater resilience of our study plots to wildfire, examining the role of fire intensity, bamboo dominance, background rates of disturbance, landscape and soil conditions.

Low-impact chemical weed control techniques in UNESCO World Heritage Sites of Cuba.

Dichrostachys cinerea is a thorny, acacia-like, fast-growing woody bush which invades fields, wasteland, road sides and other disturbed areas. This gregarious species has become a very aggressive invasive weed in Cuba, where no native predators or pathogens are found. It often encroaches in fallows, overgrazed areas and mismanaged veld. D. cinerea is a very difficult weed to eliminate because of its active suckering, and is liable to produce dense thickets which are quite impenetrable on account of the density and abundance of its long, stiff, sharp thorns. In the Valle de los Ingenios area (Cuba Central), the tree is unchecked and forms veritable forests in areas on which cane growing has been discontinued. Physical management by cutting and burning the plants is not a very efficient control method, since the seeds survive in the soil, and they grow very fast. Therefore, chemical methods via the use of herbicides are often necessary to eradicate this weed. A preliminary study using glyphosate and auxin-like herbicides (2,4-D + picloram, MCPA, and MCPA + 2,4-D) plus adjuvants has been carried out in order to elucidate the best mixtures rendering maximum weed control with minimum herbicide rate and environmental stress. None of the herbicides used except glyphosate and 2,4-D + picloram showed acceptable mortality rates (75-80%) at the recommended doses tested. In the failed herbicide treatments, only the use of double herbicide rates succeeded in controlling marabou. The herbicide mixture of 2,4-D + picloram formulated with either a non-ionic surfactant or a mixture of fatty acid esters was the best option to control D. cinerea in terms of maximum effectiveness and minimum environmental stress, as the reduction in active ingredients applied to the environment was x3 in these two adjuvant-amended formulations compared to 2,4-D + picloram alone.

A phylogenetic analysis using full-length viral genomes of South American dengue serotype 3 in consecutive Venezuelan outbreaks reveals a novel NS5 mutation.

Dengue virus currently causes 50-100 million infections annually. Comprehensive knowledge about the evolution of Dengue in response to selection pressure is currently unavailable, but would greatly enhance vaccine design efforts. In the current study, we sequenced 187 new dengue virus serotype 3 (DENV-3) genotype III whole genomes isolated from Asia and the Americas. We analyzed them together with previously-sequenced isolates to gain a more detailed understanding of the evolutionary adaptations existing in this prevalent American serotype. In order to analyze the phylogenetic dynamics of DENV-3 during outbreak periods; we incorporated datasets of 48 and 11 sequences spanning two major outbreaks in Venezuela during 2001 and 2007-2008, respectively. Our phylogenetic analysis of newly sequenced viruses shows that subsets of genomes cluster primarily by geographic location, and secondarily by time of virus isolation. DENV-3 genotype III sequences from Asia are significantly divergent from those from the Americas due to their geographical separation and subsequent speciation. We measured amino acid variation for the E protein by calculating the Shannon entropy at each position between Asian and American genomes. We found a cluster of seven amino acid substitutions having high variability within E protein domain III, which has previously been implicated in serotype-specific neutralization escape mutants. No novel mutations were found in the E protein of sequences isolated during either Venezuelan outbreak. Shannon entropy analysis of the NS5 polymerase mature protein revealed that a G374E mutation, in a region that contributes to interferon resistance in other flaviviruses by interfering with JAK-STAT signaling was present in both the Asian and American sequences from the 2007-2008 Venezuelan outbreak, but was absent in the sequences from the 2001 Venezuelan outbreak. In addition to E, several NS5 amino acid changes were unique to the 2007-2008 epidemic in Venezuela and may give additional insight into the adaptive response of DENV-3 at the population level.

The structural properties of GaN/AlN core-shell nanocolumn heterostructures.

The growth and structural properties of GaN/AlN core-shell nanowire heterostructures have been studied using a combination of resonant x-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy experiments. For a GaN core of 20 nm diameter on average surrounded by a homogeneous AlN shell, the built-in strain in GaN is found to agree with theoretical calculations performed using a valence force field model. It is then concluded that for an AlN thickness up to at least 12 nm both core and shell are in elastic equilibrium. However, in the case of an inhomogeneous growth of the AlN shell caused by the presence of steps on the sides of the GaN core, plastic relaxation is found to occur. Consistent with the presence of dislocations at the GaN/AlN interface, it is proposed that this plastic relaxation, especially efficient for AlN shell thickness above 3 nm, is promoted by the shear strain induced by the AlN inhomogeneity.

The structural properties of GaN insertions in GaN/AlN nanocolumn heterostructures.

The strain state of 1 and 2.5 nm thick GaN insertions in GaN/AlN nanocolumn heterostructures has been studied by means of a combination of high resolution transmission electron microscopy, Raman spectroscopy and theoretical modeling. It is found that 2.5 nm thick GaN insertions are partially relaxed, which has been attributed to the presence of dislocations in the external AlN capping layer, in close relationship with the morphology of GaN insertions and with the AlN capping mechanism. The observed plastic relaxation in AlN is consistent with the small critical thickness expected for GaN/AlN radial heterostructures.

The effect of chlorhexidine and gentian violet on the adherence of Candida spp. to urinary catheters.

Urinary tract infection associated with catheters is the most common infection in the hospital environment. The adherence of microorganisms to the surface is a determining factor in colonization and infection. Antiseptics such as chlorhexidine and gentian violet have been shown to be effective against yeasts, as well as having low toxicity and being low-cost. The objective of the present study was to evaluate whether prior treatment of siliconized latex urinary catheters with antiseptics reduces the adherence of yeasts. Two reference strains of C. albicans (ATCC 645448 and ATCC 90028) and six strains isolated from catheter, two each of C. albicans, C. tropicalis, and C. parapsilosis, were used. An in vitro study of adherence was carried out with previously treated catheters, in separate experiments of 1 h and 24 h of incubation under continued shaking. The relative hydrophobicity of the cell surface of the yeasts before and after 1 h of exposure to chlorhexidine was determined. The results demonstrated that both treatments were effective in controlling the adherence of yeast to the catheter (P < 0.0001), and that the hydrophobicity of the eight strains significantly increased after contact with chlorhexidine (P < 0.0001). These results suggest that the antimicrobial activity of chlorhexidine and gentian violet reduces the adherence of the microorganisms to the catheter.

Variaciones por edad y sexo en el HOMAir, en los niveles de insulina y glucosa séricas en niños y adolescentes de Maracaibo-Estado Zulia / Variations for age and sex in the HOMAir, in the levels of insulin and glucose séricas in children and adolescents of Maracaibo-state Zulia

Las variaciones en el índice de insulina-resistencia y en las concentraciones séricas de glucosa e insulina han sido poco investigadas en la población pediátrica venezolana. Por esta razón el objetivo de este estudio fue describir las variaciones de los niveles básales de insulina y glucosa así como de los valores para el HOMAIR (sensibilidad a la insulina utilizando el Homeostatic model assessment) en una muestra de niños y adolescentes del Municipio Maracaibo-Zulia-Venezuela. Para el desarrollo de la presente investigación, se estudio una muestra de 256 niños y adolescentes (120 hembras y 136 varones) en edades comprendidas entre 2 y 18 años. A cada participante se le realizo una evaluación médica y nutricional la cual incluyó cálculo de índice de masa corporal, medición de la circunferencia de cintura, pliegues cutáneos y tensión arterial. Fueron determinados los niveles de glucosa e insulina séricas en ayuno y el índice HOMAIR fue calculado como un indicador de la insulina-resistencia. No se encontraron diferencias significativas en los niveles de glucosa al comparar los diferentes grupos por edad y sexo. Sin embargo los niveles de insulina y el índice HOMAIR fueron significativamente mayores en las niñas del grupo de 14-18 años al compararlo con los niños del mismo grupo de edad (p < 0.001). El promedio del valor del HOMAIR así como de los niveles de insulina fueron mayores en el grupo de hembras y varones de 10-13 años (p < 0.05) al comparar con el resto de los grupos del mismo sexo. Las concentraciones de glucosa mostraron una distribución bastante similar en todos los grupos por edad y sexo. Las concentraciones promedio de glucosa fueron menores en nuestra población que en otras poblaciones pediátricas. Los valores mas elevados de insulina y del índice HOMAIR se observaron en el grupo de 10-13 años de edad en ambos sexos

Apparent diffusion coefficients for differentiation of cerebellar tumors in children.

BACKGROUND AND PURPOSE: Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps provide information at MR imaging that may reflect cell attenuation and integrity. We hypothesized that cerebellar tumors in children can be differentiated by their ADC values. METHODS: Brain MR imaging studies that included ADC maps were retrospectively reviewed in 32 patients with histologically proved cerebellar neoplasm. There were 17 juvenile pilocytic astrocytomas (JPA), 8 medulloblastomas, 5 ependymomas, and 2 rhabdoid (atypical teratoid/rhabdoid tumor [AT/RT]) tumors. Absolute ADC values of contrast-enhancing solid tumor regions and ADC ratios (ADC of solid tumor to ADC of normal-appearing white matter) were compared with the histologic diagnosis. ADC values and ratios of JPAs, medulloblastomas, and ependymomas were compared by using a 2-tailed t test and one-way analysis of variance (ANOVA). RESULTS: ADC values were significantly higher in pilocytic astrocytomas (1.65 +/- 0.27) (mean +/- SD) than in ependymomas (1.10 +/- 0.11) (P = .0003) and medulloblastomas (0.66 +/- 0.15) (P < .0001). Ependymomas demonstrated significantly higher ADC values than medulloblastomas (P = .0005). The observed differences were statistically significant on ANOVA (P < .001). ADC ratios were also significantly different among these 3 tumor types. AT/RT ADC values were similar to medulloblastoma. The range of ADC values and ratios within JPAs and ependymomas did not overlap with that of medulloblastomas. CONCLUSION: Assessment of ADC values of enhancing solid tumor is a simple and reliable technique for preoperative differentiation of cerebellar tumors in pediatric patients. Our cutoff values of >1.4 x 10(3) mm(2)/s for JPA and <0.9 x 10(3) mm(2)/s for medulloblastoma were 100% specific.

Gastrotomy with anvil "dunk": a novel technique for gastrojejunostomy in the patient undergoing laparoscopic Roux-en-Y gastric bypass.

BACKGROUND: Many techniques for performing the gastrojejunostomy required in the laparoscopic roux-en-Y gastric bypass (LRYGB) have been described. The current study presents the results of a previously unreported method. METHODS: A total of 21 patients (2 men and 19 women) with morbid obesity underwent LRYGB over a period of 5 months. The gastrojejunostomy was created by performing a gastric transection to form a 20- to 30-ml pouch using a linear stapler. This was followed by gastrotomy using an ultrasonic scalpel along the anterior surface of the pouch. A purse-string suture then was placed circumferentially using standard laparoscopic intracorporeal suturing with an Endo-stitch device. Finally, a 25-mm circular stapler anvil was placed within the abdomen via the 15-mm left lower quadrant port site. The shaft of the anvil was grasped; the head of the anvil was "dunked" into the gastrotomy; and the purse-string suture was tied intracorporeally. RESULTS: A total of 21 patients have undergone LRYGB at the authors' institution using this technique. The early results have been excellent in all cases, with no leaks, no strictures, and no obstructions. CONCLUSION: Gastrotomy with anvil dunk is a reproducible and safe method for constructing the gastrojejunostomy. It is an advanced laparoscopic technique that closely resembles open surgical techniques and provides a safe alternative to existing methods.

Modelling and simulation for metabolomics data analysis.

The advent of large data sets, such as those produced in metabolomics, presents a considerable challenge in terms of their interpretation. Several mathematical and statistical methods have been proposed to analyse these data, and new ones continue to appear. However, these methods often disagree in their analyses, and their results are hard to interpret. A major contributing factor for the difficulties in interpreting these data lies in the data analysis methods themselves, which have not been thoroughly studied under controlled conditions. We have been producing synthetic data sets by simulation of realistic biochemical network models with the purpose of comparing data analysis methods. Because we have full knowledge of the underlying 'biochemistry' of these models, we are better able to judge how well the analyses reflect true knowledge about the system. Another advantage is that the level of noise in these data is under our control and this allows for studying how the inferences are degraded by noise. Using such a framework, we have studied the extent to which correlation analysis of metabolomics data sets is capable of recovering features of the biochemical system. We were able to identify four major metabolic regulatory configurations that result in strong metabolite correlations. This example demonstrates the utility of biochemical simulation in the analysis of metabolomics data.

Evaluación microbiológica y fisicoquímica de néctares pasteurizados elaborados con pulpa de tomate de árbol (Cyphomandra betaceae Sendth) / Microbiological and physicochemical evaluation of pasteurized nectar elaborated with tree tomato (Cyphomandra betaceae Sendth)pulp

Tree tomato (Cyphomandra betaceae Sendth) is a species from high tropical regions. In Venezuela, it is cultivate at the Andean and Aragua state but its consumption is restricted as fruit-fresh, though it a nutritious and industrial potential due its provitamin A content. In this research four nectars were elaborated in proportion I L pulp/4 L of water (1:4) and addition of ascorbic acid (I: 0 per cent; II: 0.5 per cent; III: 1.0 y IV: 1.5 per cent). The nectars were pasteurized (60 degrees C for 30 min), tuned into amber bottle, and stored under refrigeration conditions (7.0 +/- 1.0 degrees C). Weekly during 21 days the mesophilic bacteria, molds, yeasts, total coliforms (MPN/mL), pH, degree Brix, acidity, total carotenoids, vitamin C and total sugars were evaluated. The mesophilic bacteria content was < 200 UFC/mL for every formulation on the first day the evaluation, molds and yeasts were < 10 UFC/mL and the total coliforms (NPN/mL) < 3 until the third evaluation. No significant differences (P > 0.05) were founded on: pH. degree Brix and total sugars. Significant differences (P < 0.05) were founded in vitamin C and total carotenoids content. Sensorial analysis did not show significant differences between formulations for the smell and flavor attributes, when the color was discriminate during the evaluations. The formulation I (without acid ascorbic) had more preference due its color. In conclusion, the nectars showed useful life of 14-21 days under refrigeration condition storage due to the adequate physicochemical and microbiological quality of the product.

Molecular epidemiology of dengue virus type 3 in Venezuela.

During the past 40 years, dengue haemorrhagic fever and dengue shock syndrome (DHF/DSS) have emerged in humans, with approximately 3 million cases reported and over 58 000 deaths. Dengue virus serotypes 1, 2 and 4 (DENV-1, -2 and -4) have been co-circulating in Venezuela for at least the past 10 years, causing minor or major outbreaks of dengue fever (DF) and DHF/DSS. The first recorded outbreak due to DENV-3 in Venezuela dates to 1964 and the virus then seems to have disappeared. However, DENV-3 re-appeared recently (in July, 2000) in Venezuela after 32 years of absence and produced a prolonged major outbreak, which, by the end of 2001, involved 83 180 cases of dengue, mostly DF (92 %). Previous phylogenetic studies revealed that the DENV-3 circulating during the 1960s Latin American outbreak was a genotype V virus. To gain a better understanding of the nature of the current epidemic, the complete sequence was determined of the envelope (E) gene of 15 Venezuelan DENV-3 viruses isolated during 2000 and 2001 from patients presenting with different disease severity. Sequence data were used in phylogenetic comparisons with global samples of DENV-3. Analysis revealed that the strain circulating in Venezuela is closely related to isolates that were previously present in Panama and Nicaragua in 1994 and since then have spread through Central American countries and Mexico. This study also confirms previous reports showing that the DENV-3 strain currently circulating in the Americas is related to the strain that caused DHF epidemics in Sri Lanka and India in 1989-1991 (genotype III). Finally, no evidence of the re-emergence of the strain that circulated in Venezuela in the late 1960s and 1970s (genotype V) was found.

Molecular epidemiology of dengue type 2 virus in Venezuela: evidence for in situ virus evolution and recombination.

Epidemic outbreaks of dengue fever (DF) were first recorded in Venezuela in 1978 and were followed by the emergence of dengue haemorrhagic fever (DHF) outbreaks in 1989. To gain a better understanding of the nature of these epidemics, the complete envelope (E) gene sequence of 34 Venezuelan dengue type 2 (DEN-2) viruses, isolated between 1997 and 2000 was determined. Of these isolates, 16 were from patients with DF and 17 were from patients diagnosed with DHF. There were no diagnostic sequence differences between them, suggesting that the E gene alone does not determine disease severity. These sequence data were also used in phylogenetic comparisons with a global sample of DEN-2 viruses, including strains collected previously from Venezuela. This analysis revealed that the ancestors of the Venezuelan viruses were Asian in origin, implying that a DEN-2 virus strain from this region was introduced into Venezuela and the wider Caribbean region during the late 1970s or the early 1980s. The phylogenetic trees further indicate that evolution of DEN-2 virus in Venezuela has occurred in situ, with differentiation into a number of distinct but co-circulating lineages, rather than the repeated introduction of new strains from other localities. By incorporating additional sequence data from the virus capsid, premembrane and membrane genes, evidence is provided that a single Venezuelan strain sequenced previously, designated Mara4, is a recombinant virus, incorporating genome sequence from Venezuelan and Asian parental viruses.

The influence of surface padding properties on head and neck injury risk.

A validated computational head-neck model was used to understand the mechanical relationships between surface padding characteristics and injury risk during impacts near the head vertex. The study demonstrated that injury risk can be decreased by maximizing the energy-dissipating ability of the pad, choosing a pad stiffness that maximizes pad deformation without bottoming out, maximizing pad thickness, and minimizing surface friction. That increasing pad thickness protected the head without increasing neck loads suggests that the increased cervical spine injury incidence previously observed in cadaveric impacts to padded surfaces relative to lubricated rigid surfaces was due to increased surface friction rather than pocketing of the head in the pad.