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Resumen Introducción: El personal de otorrinolaringología presenta una elevada exposición al virus SARS-CoV-2, debido a los procedimientos que lleva a cabo. Es fundamental tomar las medidas de protección adecuadas. Determinar la seroprevalencia nos dará un mejor panorama sobre la exposición, contagios y efectividad de medidas de protección adoptadas. Objetivo: Determinar la prevalencia de resultados serológicos positivos en personal médico que presta servicio en la Cátedra de Otorrinolaringología de marzo del 2020 a marzo de 2021. Material y Método: Estudio observacional, descriptivo, corte transversal, retrospectivo con asociación cruzada. Muestreo no probabilístico de casos consecutivos. La población total fue de 38 médicos del Servicio de Otorrinolaringología del Hospital de Clínicas. Resultados: La media de edades fue 37,4 años, 63,5% refirió haber atendido a paciente conocido portador de COVID-19. Un 42% refirió no haber cumplido con todas las medidas de protección personal, mientras que un 23,7% de los sujetos de estudio dio positivo para IgG, interpretándose como infección previa por COVID-19. Conclusión: Más de las dos terceras partes de los médicos refirió dar consulta a paciente COVID-19 positivo. Casi la cuarta parte de los médicos resultó ser positivo para COVID-19 según la prueba de serología anti-N. No se halló asociación entre consulta ni cirugía a pacientes portadores de COVID-19 y el contagio al personal médico.

Abstract Introduction: Otolaryngology personnel have a high exposure to SARS-CoV-2 virus due to the procedures they perform. It is essential to take appropriate protective measures. Determining seroprevalence will give us a better picture of exposure, contagion and effectiveness of protective measures adopted. Aim: To determine the prevalence of positive serological results in medical staff serving in the otolaryngology department from March 2020 to March 2021. Material and Method: Observational, descriptive, cross-sectional, retrospective, retrospective study with cross-association. Non-probability sampling of consecutive cases. The total population was 38 physicians of the Otolaryngology Service of the Hospital de Clinicas. Results: The mean age was 37.4. 63.5% reported having seen a patient known to be a COVID-19 carrier, while 42% reported not having complied with all personal protection measures. A 23.68% of the study subjects tested positive for IgG, interpreting previous COVID-19 infection. Conclusion: More than two-thirds of the physicians referred to giving consultation to COVID-19 positive patients. Almost a quarter of the physicians were positive for COVID-19 according to the Anti-N serology test. No association was found between consultation or surgery of patients with COVID-19 and infection of medical personnel.

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OBJECTIVES: The Fueguians are descendants of the first settlers of America, a 'relict' isolated geographically for 10,000 years. We compared their cranial variation with other Americans, and samples from Asia and Australia to know whether the modern extinct Fueguians can be considered Paleoamericans or not. MATERIALS AND METHODS: Herein we study 176 Fuego-Patagonian skulls, the largest cranial sample to be studied, refined and well documented, using CVA, and the D2 of Mahalanobis. The affinities between populations and sexual dimorphism were jointly studied. RESULTS: Terrestrial hunters (Selknam) have a different cranial morphology from sea canoeists (Yamana, Alakaluf) particularly with regard to cranial size and robustness. In the American context, there are extreme differences between the canoeists of Santa Cruz (California) and the Eskimos and canoeists of Fuego-Patagonia in terms of cranial size, prognathism and development of the frontal region. Fueguian canoeists are cranially closer to the Californian ones than to their Fueguian neighbors, the Selknam. Our results favor the hypothesis of two different flows for the origin of the first populators of Tierra del Fuego. DISCUSSION: We concluded that the robusticity of some Fuegians (Selknam) might be the result of an allometric pattern of overall robusticity expression well as a result of epigenetics or differential reproduction (Larsen, 2015:264) or hypothetical endocrine changes (Bernal et al. in Am J Hum Biol 2006;18:748-765). When compared with three Australian-Melanesian series, the group comprising Amerindians, Ainu, and Eskimos clusters together as they are all extremely different from the former in terms of both cranial size and shape.

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The Peruvian Andes presents a climate suitable for many species of sandfly that are known vectors of leishmaniasis or bartonellosis, including Lutzomyia peruensis (Diptera: Psychodidae), among others. In the present study, occurrences data for Lu. peruensis were compiled from several items in the scientific literature from Peru published between 1927 and 2015. Based on these data, ecological niche models were constructed to predict spatial distributions using three algorithms [Support vector machine (SVM), the Genetic Algorithm for Rule-set Prediction (GARP) and Maximum Entropy (MaxEnt)]. In addition, the environmental requirements of Lu. peruensis and three niche characteristics were modelled in the context of future climate change scenarios: (a) potential changes in niche breadth; (b) shifts in the direction and magnitude of niche centroids, and (c) shifts in elevation range. The model identified areas that included environments suitable for Lu. peruensis in most regions of Peru (45.77%) and an average altitude of 3289 m a.s.l. Under climate change scenarios, a decrease in the distribution areas of Lu. peruensis was observed for all representative concentration pathways. However, the centroid of the species' ecological niche showed a northwest direction in all climate change scenarios. The information generated in this study may help health authorities responsible for the supervision of strategies to control leishmaniasis to coordinate, plan and implement appropriate strategies for each area of risk, taking into account the geographic distribution and potential dispersal of Lu. peruensis.

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Organ transplantation represents one of the medical fields with the largest impact and advances. Liver transplantation constitutes a constant challenge in finding viable options to maintain or recover an adequate function when faced with end-stage liver failure. Critical review of the literature was conducted in specific topics on liver transplantation and development in Mexico. We focused our review on medical and surgical topics such as liver procurement from a related living donor, liver transplantation options for patients with liver cancer, especially hepatocellular carcinoma and cholangiocarcinoma, as well as on cellular and molecular biology aspects, such as xenotransplantation and hepatocyte transplantation.

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About 20 years ago Drosophila subobscura, a native Palearctic species, colonized both North and South America. In Palearctic populations lethal genes are not associated in general with particular chromosomal arrangements. In colonizing populations they are not randomly distributed and usually are associated to a different degree with chromosomal arrangements caused by the founder event. The persistence of two lethal genes in the colonizing populations, one completely associated with the O(5) inversion and the other partially associated with the O(3+4+7) arrangement, has been analyzed. In all populations studied (five North American and six South American) the observed frequency of the lethal gene completely associated with the O(5) inversion is higher than expected, the difference being statistically significant in all South American and one North American populations. The observed frequency of the lethal gene partially associated with the O(3+4+7) arrangement is also significantly higher than expected. Taking into account that the O(5) inversion exhibits significant latitudinal clines both in North and South America, an overdominant model favoring the heterokaryotypes seems to be in operation. From this model, a polynomial expression has been developed that allows us to estimate the relative fitness and the coefficient of selection against all karyotypes not carrying the O(5) inversion. The relative fitness of the O(5) heterokaryotypes is higher in South American than in North American populations. Furthermore, the observed frequencies of the lethal genes studied are in general very close to those of the equilibrium. This case is an outstanding demonstration in nature of an heterotic effect of chromosomal segments associated with lethal genes on a large geographic scale.

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Variations in evoked potentials utilizing a photic stimulus in a sample of psychiatric patients compared to a healthy sample were evaluated. A group of patients diagnosed as schizophrenic was tested against a sample of healthy volunteers in a trial combining visual evoked potentials and a simultaneous cognitive processing. The stimulus was a checkerboard pattern presented under three different conditions. The results indicate diminished P100 and lack the reactivity associated with cognitive processes in schizophrenic group. The P200 component also lacked, in the inpatient group the changes associated with the performance of the trial. Finally the multiple P300 component was shortened in latency and decreased in amplitude in the schizophrenia group. Besides, P300 interhemispheric shifts related to trials, were commonly inverted in schizophrenics. Results are interpreted as a lacked interhemispheric coordination in schizophrenics, rather than a fixed hemispheric alteration. Likewise, an attenuation in processing from specific cortical areas to association cortex is concluded.

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