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Lifestyle modifications in preclinical Rheumatoid Arthritis (RA) could delay the ongoing pathogenic immune processes and potentially prevent its onset. Physical exercise (PE) benefits RA patients; however, its impact in reducing the risk of developing RA has scarcely been studied. The objective was to describe the effects of low-intensity PE applied at the disease's preclinical phase on the joints of DBA/1 mice with collagen-induced arthritis (CIA). Twelve mice with CIA were randomly distributed into two groups: the CIA-Ex group, which undertook treadmill PE, and the CIA-NoEx, which was not exercised. The effects of PE were evaluated through clinical, histological, transcriptomics, and immunodetection analyses in the mice's hind paws. The CIA-Ex group showed lower joint inflammation and damage and a decreased expression of RA-related genes (Tnf Il2, Il10, Il12a, IL23a, and Tgfb1) and signaling pathways (Cytokines, Chemokines, JAK-STAT, MAPK, NF-kappa B, TNF, and TGF-beta). TNF-α expression was decreased by PE in the inflamed joints. Low-intensity PE in pre-arthritic CIA reduced the severity through joint down-expression of proinflammatory genes and proteins. Knowledge on the underlying mechanisms of PE in preclinical arthritis and its impact on reducing the risk of developing RA is still needed.

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The fibroblast-like synoviocytes (FLS) have a crucial role in the pathogenesis of Rheumatoid Arthritis (RA); however, its precise mechanisms remain partially unknown. The involvement of the fibroblast in activating adjuvant-induced arthritis (AA) has not been previously reported. The objective was to describe the participation of footpads' fibroblasts in the critical initial process that drives the AA onset. Wistar rats were injected with Complete Freund's Adjuvant (CFA) or saline solution in the hind paws' footpads and euthanized at 24 or 48 h for genetic and histological analyses. Microarrays revealed the differentially expressed genes between the groups. The CFA dysregulated RA-linked biological processes at both times. Genes of MAPK, Jak-STAT, HIF, PI3K-Akt, TLR, TNF, and NF-κB signaling pathways were altered 24 h before the arrival of immune cells (CD4, CD8, and CD68). Key markers TNF-α, IL-1ß, IL-6, NFκB, MEK-1, JAK3, Enolase, and VEGF were immunodetected in fibroblast in CFA-injected footpads at 24 h but not in the control group. Moreover, fibroblasts in the CFA inoculation site overexpressed cadherin-11, which is linked to the migration and invasion ability of RA-FLS. Our study shows that CFA induced a pathological phenotype in the fibroblast of the inoculation site at very early AA stages from 24 h, suggesting a prominent role in arthritis activation processes.

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The dynamic behavior of the hydraulic actuator in a system for regulating the electrode's position is crucial for the operation of a Ladle Furnace. This work aims to identify, model, and control the hydraulic actuator in the Ladle Furnace of ACINOX Las Tunas. For identifying the system, input signals of Pseudo-Random Binary type and black box models were used. As a result, three models were obtained, two reflecting the process's asymmetric behavior according to the upward or downward movement. The third model approximates the process dynamic behavior around the operating point and includes the uncertainty caused by the weight variation during the electrode wear. The models obtained, with a fit greater than 85%, allow a better understanding of the study case behavior. In addition, these allowed the evaluation of the electrode's weight variation and tuning of several controllers. The optimal one was a novel non-linear PI controller of guaranteed robustness. In future works, the use of a non-linear function could be evaluated to compensate for the asymmetric behavior of the process.

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Resumen El artículo analiza, desde una perspectiva cualitativa, cómo la pandemia de COVID-19 ha reducido significativamente la atención médica de pacientes crónicos, en los tres niveles del sector salud de la Ciudad de México, debido a las estrategias de mitigación comunitaria; la percepción del riesgo de infección del personal de salud y los pacientes; la focalización en la atención a la pandemia, y a como estos procesos se articulan con las condiciones previas de desfinanciamiento del sistema público de salud. Para ello utilizamos el enfoque de la teoría fundamentada basándonos en la descripción y el análisis de las experiencias de 42 médicas y médicos entrevistados en los tres niveles de atención. Se propone el concepto de iatrogenia pandémica para abordar la interrelación entre la organización material y simbólica del modelo dominante de atención médica y ciertas dimensiones estructurales y culturales de la desatención masiva y sistémica desde la llegada de la pandemia. A partir de esta propuesta teórica y de las experiencias de las médicas y los médicos entrevistados, se señalan algunas estrategias y posibilidades para evitar escenarios futuros similares.

Abstract The paper analyzes, from a qualitative perspective, how the COVID-19 pandemic has significantly reduced medical care for chronic patients at the three levels of the Mexico City health sector due to community mitigation strategies, the perceived risk of infection of health personnel and patients, the focus on pandemic care, and how these processes are articulated with the previous underfunding conditions of the public health system. Thus, we adopted the Grounded Theory approach based on the description and analysis of the experiences of 42 doctors interviewed at the three care levels. The pandemic iatrogenesis concept is proposed to address the interrelation between the material and symbolic organization of the dominant model of medical care and specific structural and cultural dimensions of massive and systemic neglect since the arrival of the pandemic. We point out some strategies and possibilities to avoid similar future settings based on this theoretical proposal and the experiences of the doctors interviewed.

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The paper analyzes, from a qualitative perspective, how the COVID-19 pandemic has significantly reduced medical care for chronic patients at the three levels of the Mexico City health sector due to community mitigation strategies, the perceived risk of infection of health personnel and patients, the focus on pandemic care, and how these processes are articulated with the previous underfunding conditions of the public health system. Thus, we adopted the Grounded Theory approach based on the description and analysis of the experiences of 42 doctors interviewed at the three care levels. The pandemic iatrogenesis concept is proposed to address the interrelation between the material and symbolic organization of the dominant model of medical care and specific structural and cultural dimensions of massive and systemic neglect since the arrival of the pandemic. We point out some strategies and possibilities to avoid similar future settings based on this theoretical proposal and the experiences of the doctors interviewed.

El artículo analiza, desde una perspectiva cualitativa, cómo la pandemia de COVID-19 ha reducido significativamente la atención médica de pacientes crónicos, en los tres niveles del sector salud de la Ciudad de México, debido a las estrategias de mitigación comunitaria; la percepción del riesgo de infección del personal de salud y los pacientes; la focalización en la atención a la pandemia, y a como estos procesos se articulan con las condiciones previas de desfinanciamiento del sistema público de salud. Para ello utilizamos el enfoque de la teoría fundamentada basándonos en la descripción y el análisis de las experiencias de 42 médicas y médicos entrevistados en los tres niveles de atención. Se propone el concepto de iatrogenia pandémica para abordar la interrelación entre la organización material y simbólica del modelo dominante de atención médica y ciertas dimensiones estructurales y culturales de la desatención masiva y sistémica desde la llegada de la pandemia. A partir de esta propuesta teórica y de las experiencias de las médicas y los médicos entrevistados, se señalan algunas estrategias y posibilidades para evitar escenarios futuros similares.

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Introduction: The objective of this article was to explore, from an anthropological perspective, the social representations that doctors who treat covid-19 in specialized hospitals in Mexico City have, regarding the relationship between their professional performance and the deterioration of their mental health; as well as their social representations of the existing institutional resources to provide them mental health attention and their care-seeking and self-care strategies. Materials and Methods: For this, a quali-tative investigation was carried out with semi-structured interviews with 35 doctors who treat covid-19. Results: From the points of view of the doctors, various sociocultural and structural causes of mental illness related to their professional performance are documented and analyzed, as well as their repre-sentations about the inadequacy and/or ineffectiveness of the institution, group, or individual resources to provide them mental health attention; and some allopathic and non-biomedical forms of care-seeking and self-care. Conclusions: Recommendations are made to address the etiologies of the disease analyzed in a culturally and structurally appropriate way to the context of the pandemic.

Introducción: el objetivo de este artículo es explorar, desde una perspectiva antropológica, las representaciones sociales de los médicos que atienden covid-19 en hospitales especializados de la Ciudad de México, respecto a la relación entre su desempeño profesional y el deterioro de su salud mental, así como de los recursos institucionales existentes para atenderla y sus estrategias de búsqueda de atención y de autoatención. Materiales y métodos: para ello, se realizó una investigación cualitativa con entrevistas semiestructuradas a 35 médicos que atienden covid-19. Resultados: a partir de sus puntos de vista se documentan y analizan diversas causas socioculturales y estructurales del padecimiento mental relacionado con su desempeño profesional, así como sus representaciones sobre la inadecuación o ineficacia de los recursos institucionales, grupales o individuales, para atenderlo y algunas modalidades de búsqueda de atención y autoatención alopáticas y no biomédicas. Conclusiones: se realizan recomendaciones para abordar institucionalmente las etiologías del padecimiento reportadas por los entrevistados de una forma cultural y estructuralmente adecuada al contexto de la pandemia.

Introdução: O objetivo deste artigo é explorar, a partir de uma perspectiva antropológica, as represen-tações sociais que os médicos que tratam a covid-19 em hospitais especializados na Cidade do México, têm sobre a relação entre seu desempenho profissional e a deterioração de sua saúde mental; bem como os recursos institucionais existentes para cuidar da saúde mental e as estratégias de busca de cuidado e autocuidado. Materiais e métodos: Para isso, foi realizada uma pesquisa qualitativa com entrevistas semiestruturadas com 35 médicos que tratam da covid-19. Resultados: Do ponto de vista dos médicos, são documentadas e analisadas diversas causas socioculturais e estruturais do adoecimento mental relacio-nadas à sua atuação profissional, bem como suas representações sobre a inadequação e/ou ineficiência dos recursos institucionais, grupais ou individuais, disponíveis para atendê-los e algumas modalidades de busca de cuidado e autocuidado alopáticos e não biomédicos. Conclusões: São feitas recomendações para abordar institucionalmente as etiologias da doença relatadas pelos entrevistados de forma cultural e estruturalmente adequada no contexto da pandemia.

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In this work, an effective thermal conductivity (ETC) for living tissues, which directly affects the energy transport process, is determined. The fractal scaling and Monte Carlo methods are used to describe the tissue as a porous medium, and blood is considered a Newtonian and non-Newtonian fluid for comparative and analytical purposes. The effect of the principal variables-such as fractal dimensions DT and Df, porosity, and the power-law index, n-on the temperature profiles as a function of time and tissue depth, for one- and three-layer tissues, besides temperature distribution, are presented. ETC was improved by considering high tissue porosity, low tortuosity, and shear-thinning fluids. In three-layer tissues with different porosities, perfusion with a non-Newtonian fluid contributes to the understanding of the heat transfer process in some parts of the human body.

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Actualmente la asociación entre periodontitis y enfermedades o condiciones sistémicas es ampliamente reconocida. Sin embargo, el rol de la periodontitis en la severidad de COVID-19, se comienza a estudiar. El objetivo de esta revisión es relacionar la presencia de periodontitis como factor asociado en casos más severos de COVID-19. Se aborda el posible rol de la periodontitis y su conexión a través de las citoquinas y otros mecanismos asociados como la senescencia celular y la NETosis, que podrían explicar su influencia en el desarrollo y severidad de COVID-19. Además, se abordan aspectos complementarios como el rol de la higiene oral y mantención de la salud oral como medidas adicionales de prevención.

Currently, the association between periodontitis and systemic diseases is widely recognized. However, a potential role of periodontal inflammation on the severity of COVID-19 has recently been studied. The goal of this review is to highlight different mechanisms by which the presence of periodontitis could contribute to the increased severity of COVID-19. These mechanisms include the secretion of proinflammatory cytokines, accelerated cellular senescence, and NETosis. We also emphasize the importance of oral hygiene and maintenance of oral health as additional measures to avoid COVID-19 dissemination.

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Extensive anatomic variability of the coronary arteries in hearts with transposition of great arteries has been described. Usual coronary pattern is defined as right coronary artery arising from posterior facing sinus and left coronary artery from anterior facing sinus. Results of prior case series have suggested that certain coronary patterns are associated with adverse outcomes in surgery (arterial switch operation). We present the case of a neonate with prenatal diagnosis of transposition of great arteries. Postnatal transthoracic echocardiography showed great arteries in a side-by-side relationship (fig. 1). Coronary pattern was described as inverted or with double coronary looping, which represents less than 3% of the anatomical variants. The entire left coronary artery system arose from the posterior-facing sinus, whereas the right coronary artery arose from the aorta anteriorly. Left coronary artery pursued a retropulmonary course, dividing posteriorly into the circumflex and anterior descending arteries (fig. 2). The patient underwent arterial switch operation uneventfully.

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Bacula from 61 individual hutia (Rodentia) from five species were studied. The purpose was to investigate cross-sectional geometry as an indicator of mechanical behavior in order to answer questions around the origin and maintenance of the mammalian baculum. From images of the apical and basal cross sections, the following variables were calculated: perimeter, cross-sectional area, maximum second moment of area, and polar moment. An allometric analysis showed that these variables were related to body size. The orientation of the maximum second moment of area was analyzed by means of circular statistics. This orientation was transverse in both the apical and basal cross sections. Values for the second moment of area and polar moment, obtained from the predicted value of the allometric equations, showed that either the bending moment or the twisting moment of the baculum must be relatively low in hutias, compared with those of the radius in the same species. The results of the second moment of area predict that the main bending stress acting on the baculum is transverse. At the same time, shear stress would not be negligible. Anat Rec, 303:1346-1353, 2020. © 2019 American Association for Anatomy.

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The Mexico-Guatemala border is the site of significant movement of people whose principal destination is the USA. The first step, to cross Mexico, is considered as one of the most dangerous routes in the world for undocumented migrants. For some male migrants and displaced persons from Honduras, El Salvador and Guatemala, initiating sex work in the Mexican border city of Tapachula has become a way to earn money to survive during the trip northward - providing funds to keep traveling and decrease the danger of being killed or kidnaped by organized crime groups. Non-injected drug use during sex work with men and/or women is a common praxis for this purpose, and is linked to HIV risk activities such as unprotected sex. Our study is based on ethnographic fieldwork with observation and interviews and within a relational approach understanding the processes subject/structure, sociopolitical/cultural and global/local, not as oppositions, rather as linkages visible through actors' points of view and praxis. The productions of politics and cultures related to structural vulnerability to HIV infection are embedded in local and global borderization processes where legal and illegal transnational forces, states' frameworks and social groups play a linked role. The economies of structural, symbolic and direct violence affect migratory patterns, institutional interactions and social and cultural relations with the local population. In this context, social representations and praxis about unprotected sex and drug use are the locus of struggling bodies at the border.

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U.S.-Mexico border communities are uniquely vulnerable to sexually transmitted infection (STI) transmission given the economic and social challenges these communities face. This study examines how marginalized statuses of U.S. border residents are associated with STI awareness and sexual behaviors. We surveyed low-income residents receiving STI testing and/or HIV/AIDS care in the lower Rio Grande Valley of southernmost Texas. Respondents aged 18+ took a self-administered survey available in English or Spanish in a clinic waiting room (N = 282). Approximately 52% of respondents reported being HIV+, and 32% of respondents reported having a prior STI other than HIV. Although most respondents had heard of HPV (72%), awareness of the HPV vaccine was low across all subgroups (28%), including women (< 35%), reflecting previous findings that border residents are less knowledgeable about the HPV vaccine. Almost half of respondents reported always using a condom (45%), which is higher than elsewhere in the U.S. Male and non-Hispanic respondents had higher estimated prevalence ratios (PR) of lifetime partners [PR 1.39 (95% confidence interval 1.43-3.68), PR 1.88 (1.04-3.41), respectively] and sexual partners met online [PR 3.73 (1.00-14.06), PR 19.98 (5.70-70.10), respectively]. Sexual minority, non-Hispanic, and male respondents had higher adjusted odds ratios (AOR) of utilizing the internet to find sexual partners than their peers [AOR 2.45 (1.60-3.87), AOR 1.52 (1.11-2.07), AOR 1.97 (1.20-3.24), respectively], placing them at greater STI-transmission risk. We found diversity in dimensions of STI awareness and sexual behaviors in our sample. Results can help tailor public health interventions to the unique STI risks of marginalized groups in border communities.

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Hybrid bionanocomposites based on cellulose matrix, with silica nanoparticles as reinforcers, were prepared by one-pot synthesis of cellulose surface modified by solvent exchange method to keep the biopolymer net void for hosting inorganic nanoparticles. Neither expensive inorganic-particle precursors nor crosslinker agents or catalysts were used for effective dispersion of reinforcer concentration up to 50 wt %. Scanning electron microscopy of the nanocomposites shows homogeneous dispersion of reinforcers in the surface modified cellulose matrix. The FTIR spectra demonstrated the cellulose features even at 50 weight percent content of silica nanoparticles. Such a high content of silica provides high thermal stability to composites, as seen by TGA-DSC. The fungi decay resistance to Trametes versicolor was measured by standard test showing good resistance even with no addition of antifungal agents. This one-pot synthesis of biobased hybrid materials represents an excellent way for industrial production of high performance materials, with a high content of inorganic nanoparticles, for a wide variety of applications.

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Objective: To identify the most frequent Candida species in specimens from patients hospitalized in different medical centers of Mexico City, with suspected fungal infection. Methods: Specimens were grown on Sabouraud dextrose agar at 28°C for 72 h. In addition, DNA was extracted. Isolates were grown on CHROMagar Candida™, at 37°C for 48 h. The molecular identification was performed by polymerase chain reaction (PCR) using primers specific for four species. Results: Eighty one specimens were processed and included: bronchial lavage, pleural, cerebrospinal, peritoneal, ascites and bile fluids; blood, sputum, bone marrow, oro-tracheal cannula and ganglion. By culture, 30 samples (37%) were positive, and by PCR, 41 (50.6%). By PCR, the frequency of species was: Candida albicans 82.9%, Candida tropicalis 31.7%, Candida glabrata 24.4%, and Candida parapsilosis 4.9%. In 34.1% of specimens a species mixture was detected suggesting a co-infection: Two species in five specimens (C. albicans-C tropicalis and C. albicans-C glabrata), and three species in three specimens (C. albicans-C. glabrata-C. tropicalis). Conclusions: The PCR is an useful tool for detection the most common Candida species causing infection in hospitalized patients, it avoids the requirement of culture weather we start from clinical specimen and it favors the early diagnosis of invasive candidiasis.

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Se presentan los resultados de una investigación cuyo objetivo gene-ral fue describir y analizar la situación de prevalencia epidemiológica, prevención y tratamiento del VIH en los pueblos indígenas en Latinoa-mérica. Para ello, se revisaron un total de 304 materiales provenientes de 16 países de Latinoamérica. En este artículo se analizan algunas de las razones de la invisibilización del impacto de la epidemia del VIH en los pueblos indígenas de Latinoamérica, y se presenta la situación de 9 países de la región en los que se dispone de evidencia sobre la preva-lencia/incidencia de VIH en ciertas poblaciones indígenas. A partir del análisis del escaso material cuantitativo y cualitativo existente en la ac-tualidad, se evidencian determinantes multinivel que deben de ser es-tudiados detalladamente considerando, como eje exploratorio nodal, la vulnerabilidad diferencial asociada a la condición étnica

We present the results of an investigation whose general aim was to describe and analyze the situation of epidemiological HIV prevalence, prevention and medical treatment for indigenous peoples in Latin America. For that purpose, we reviewed a total of 304 materials from 16 countries of Latin America. This article analyzes some of the reasons why the HIV epidemic impact within indigenous peoples of Latin America is not visible, and presents the situation of 9 countries belonging to the region in which there is evidence on the HIV prevalence/incidence among this populations. The limited quantitative and qualitative material existing at present, highlight multilevel determinants that must be studied in detail taking into account, as a main exploratory line, the differential vulnerability associated with ethnicity

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Background: We evaluated the reliability, factorial validity and criteria validity of a psychometric test designed to measure eating behavior self-efficacy. Materials and methods: This construct was measured using a 21 item scale appplied to a sample of 300 between 14 and 74 years (M=29.89), from the Metropolitan Area of México City, Mexico. Results: Data analysis revealed a four factor structure with high reliability. These factors characterized 4 different types of eating behaviors: 1) high fat eating consumption; 2) healthy eating consumption; 3) sweets consumption and 4) drink consumption. Additionally, we measured physical activity as a factor that could be related with healthy eating. Conclusion. We analyzed feasibility of using this psychometric tool to assess self-efficacy in our sample and its potential implication for nutritional programs. It is also considered feasible to apply this scale in new settings, such as educational programs on nutrition and in the nutritionist practice, since it can provide a predictive tool for eating behaviors.

Objetivo: Evaluar la confiabilidad, la validez factorial y de criterio de un instrumento diseñado para medir autoeficacia alimentaria. Material y métodos: Se utilizó una escala de estimación de 21 ítems, aplicado a una muestra de 300 personas entre 14 y 74 años de edad (M= 29.89) de la Zona Metropolitana de la Ciudad de México, México. Resultados: El instrumento incorporó cuatro factores: 1) consumo de alimentos altos en grasa; 2) consumo de alimentos saludables; 3) consumo de alimentos dulces y 4) consumo de bebidas. Se encontró que la capacidad de alimentarse sanamente se encuentra presente en las personas que realizan actividad física frecuentemente. Conclusiones: Se plantea su utilidad en la evaluación de la autoeficacia de la conducta alimentaria en contextos como los programas de educación nutricional y la práctica del nutriólogo. Este instrumento puede proveer de una herramienta predictora de las conductas alimentarias.

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BACKGROUND: Factors such as cancer, HIV infection, use of corticosteroids and antibiotics, favors the increase in the number of invasive fungal infections (IFI) worldwide. METHODS: To determine the frequency and epidemiological aspects of IFI at a mexican, a review of the proven cases diagnosed over the past 21 years (1993-2013) in the Laboratory of Medical Mycology was performed. RESULTS: A total of 472 cases were identified as: 261 candidiasis, 82 mucormycosis, 60 cryptococcosis, 43 aspergillosis and 16 histoplasmosis. A decrease in the frequency of candidiasis was observed, with 74 cases in the first 6 years and 48 in the last five. C. albicans was the most common agent and pulmonary infection the most prevalent. Cryptococcosis also declined from 24 to 10 cases, mainly caused by C. neoformans; two cases of C. laurentii and C. terreus and C unigutulatus were isolated once. Mucormycosis remained steady, but aspergillosis increased significantly, and from 2 cases found in the first studied period, it rose to 23 in the last one. CONCLUSIONS: It is important that High Specialty Hospitals have well-equipped laboratories of Medical Mycology. We suggest the creation of a National Reference Center for Mycoses to collect all the data of these infections, in order to help to the development of strategies for health education, prevention, diagnosis and treatment of them.

Introducción: Factores como el cáncer, la infección por VIH, así como el uso de esteroides y antibióticos, incrementan el número de micosis invasivas (MI). Métodos: Para conocer la frecuencia y algunos aspectos epidemiológicos de las MI en un hospital del IMSS, se revisaron los casos probados diagnosticados en los últimos 21 años (1993-2013) en el Laboratorio de Micología Médica. Resultados: Se identificaron 472 casos, distribuidos en: 261 candidosis, 82 mucormicosis, 60 criptococosis, 43 aspergilosis y 16 histoplasmosis. La candidosis disminuyó de 74 casos en los primeros 6 años, a 48 en los cinco últimos. La localización principal fue pulmonar y el principal agente fue C. albicans. La criptococosis también disminuyó de 24 a 10 casos, principalmente fue causada por C. neoformans, aunque hubo dos casos de C. laurentii, uno de C. terreus y uno de C. unigutulatus. La mucormicosis se mantuvo constante, pero la aspergilosis se incrementó pasando de 2 casos en el primer periodo a 23 en el último. Conclusiones: Es importante que los hospitales de alta especialidad, cuenten con laboratorios de micología médica para realizar el diagnóstico de MI. Se sugiere crear un Centro Nacional de Referencia de Micosis donde se concentren los datos de estas infecciones y contribuya en la elaboración de planes de educación para la salud, prevención, diagnóstico y tratamiento de las mismas.

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We describe Sarmientosaurus musacchioi gen. et sp. nov., a titanosaurian sauropod dinosaur from the Upper Cretaceous (Cenomanian-Turonian) Lower Member of the Bajo Barreal Formation of southern Chubut Province in central Patagonia, Argentina. The holotypic and only known specimen consists of an articulated, virtually complete skull and part of the cranial and middle cervical series. Sarmientosaurus exhibits the following distinctive features that we interpret as autapomorphies: (1) maximum diameter of orbit nearly 40% rostrocaudal length of cranium; (2) complex maxilla-lacrimal articulation, in which the lacrimal clasps the ascending ramus of the maxilla; (3) medial edge of caudal sector of maxillary ascending ramus bordering bony nasal aperture with low but distinct ridge; (4) 'tongue-like' ventral process of quadratojugal that overlaps quadrate caudally; (5) separate foramina for all three branches of the trigeminal nerve; (6) absence of median venous canal connecting infundibular region to ventral part of brainstem; (7) subvertical premaxillary, procumbent maxillary, and recumbent dentary teeth; (8) cervical vertebrae with 'strut-like' centroprezygapophyseal laminae; (9) extremely elongate and slender ossified tendon positioned ventrolateral to cervical vertebrae and ribs. The cranial endocast of Sarmientosaurus preserves some of the most complete information obtained to date regarding the brain and sensory systems of sauropods. Phylogenetic analysis recovers the new taxon as a basal member of Lithostrotia, as the most plesiomorphic titanosaurian to be preserved with a complete skull. Sarmientosaurus provides a wealth of new cranial evidence that reaffirms the close relationship of titanosaurs to Brachiosauridae. Moreover, the presence of the relatively derived lithostrotian Tapuiasaurus in Aptian deposits indicates that the new Patagonian genus represents a 'ghost lineage' with a comparatively plesiomorphic craniodental form, the evolutionary history of which is missing for at least 13 million years of the Cretaceous. The skull anatomy of Sarmientosaurus suggests that multiple titanosaurian species with dissimilar cranial structures coexisted in the early Late Cretaceous of southern South America. Furthermore, the new taxon possesses a number of distinctive morphologies-such as the ossified cervical tendon, extremely pneumatized cervical vertebrae, and a habitually downward-facing snout-that have rarely, if ever, been documented in other titanosaurs, thus broadening our understanding of the anatomical diversity of this remarkable sauropod clade. The latter two features were convergently acquired by at least one penecontemporaneous diplodocoid, and may represent mutual specializations for consuming low-growing vegetation.

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Supraspinous ossified rods have been reported in the sacra of some derived sauropod dinosaurs. Although different hypotheses have been proposed to explain the origin of this structure, histological evidence has never been provided to support or reject any of them. In order to establish its origin, we analyse and characterize the microstructure of the supraspinous rod of two sauropod dinosaurs from the Upper Cretaceous of Argentina. The supraspinous ossified rod is almost entirely formed by dense Haversian bone. Remains of primary bone consist entirely of an avascular tissue composed of two types of fibre-like structures, which are coarse and longitudinally (parallel to the main axis of the element) oriented. These structures are differentiated on the basis of their optical properties under polarized light. Very thin fibrous strands are also observed in some regions. These small fibres are all oriented parallel to one another but perpendicular to the element main axis. Histological features of the primary bone tissue indicate that the sacral supraspinous rod corresponds to an ossified supraspinous ligament. The formation of this structure appears to have been a non-pathological metaplastic ossification, possibly induced by the continuous tensile forces applied to the element.