On the cosmological effects of the Weyssenhoff spinning fluid in the Einstein-Cartan framework

The effects of non-Riemannian structures in Cosmology have been studied long ago and are still a relevant subject of investigation. In the seventies, it was discovered that singularity avoidance and early accelerated expansion can be induced by torsion in the Einstein-Cartan theory. In this framework, torsion is not dynamical and is completely expressed by means of the spin sources. Thus, in order to study the effects of torsion in the Einstein-Cartan theory, one has to introduce matter with spin. In principle, this can be done in several ways. In this work we consider the cosmological evolution of the universe in the presence of a constant isotropic and homogeneous axial current and the Weyssenhoff spinning fluid. We analyse possible solutions of this model, with and without the spinning fluid.Comment: Work presented at the 7th Alexander Friedmann International Seminar on Gravitation and Cosmology, Joao Pessoa, Brazil, 29 Jun - 5 Jul 2008. No figures, 5 pages. New version with dynamical equation corrected, new reference and a brief comparison with its experimental bound

The clone size of peripheral CD8 T cells is regulated by TCR promiscuity

Positive selection in the thymus and peripheral T cell survival depend on T cell receptor (TCR)–major histocompatibility complex (MHC) interactions, but it is not yet clear if both events follow exactly the same rules. We studied peripheral T cell survival and clone sizes in conditions of progressive reduction of restricting MHC-bearing cells or progressive ablation of different MHC molecules. Different CD8+ T cell clones/polyclonal populations showed different survival and/or lymphopenia-driven proliferation requirements. We could correlate clone sizes to the capacity of each TCR to interact with different types of MHC complexes. Thus, although repertoire selection in the thymus is mainly conditioned by the affinity of TCR–MHC interactions, peripheral selection is determined by TCR cross-reactivity to environmental ligands

Competition controls the rate of transition between the peripheral pools of CD4+CD25− and CD4+CD25+ T cells

Recent reports have hinted that it is possible to regenerate CD4+CD25+ regulatory T cells (Treg) from CD4+CD25− cells, a phenomenon termed conversion. We evaluated the relative contribution of this process to the Treg pool by transferring purified populations of CD4+ T cells into T cell-deficient mice. We report that conversion of CD25− cells into the CD4+CD25+Treg pool is minor if other bona fide CD25+ Tregs are present. Moreover, in the same hosts, the loss of CD25 expression by a population of Tregs also decreases in the presence of co-injected CD4+CD25− cells. Thus, the rate of exchange between CD25− and CD25+ T-cell populations is determined by the presence or absence of T-cell competitors. Our results attest for the role of competition in the contribution of different T-cell subsets for the regeneration of the peripheral CD4+ T-cell pool during lymphopeni

Células de linhagem McCoy como um possível modelo contendo receptores CD4+ para estudos da replicação do HIV

Several studies have recently shown the use of recombinant rabies virus as potential vector-viral vaccine for HIV-1. The sequence homology between gp 120 and rabies virus glycoprotein has been reported. The McCoy cell line has therefore been used to show CD4+ or CD4+ like receptors. Samples of HIV-1 were isolated, when plasma of HIV-1 positive patients was inoculated in the McCoy cell line. The virus infection was then studied during successive virus passages. The proteins released in the extra cellular medium were checked for protein activity, by exposure to SDS Electrophoresis and blotting to nitro-cellulose filter, then reacting with sera of HIV positive and negative patients. Successive passages were performed, and showed viral replication, membrane permeabilization, the syncytium formation, and the cellular lysis (cytopathic effect). Flow cytometry analysis shows clear evidence that CD4+ receptors are present in this cell line, which enhances the likelihood of easy isolation and replication of HIV. The results observed allow the use of this cell line as a possible model for isolating HIV, as well as for carrying out studies of the dynamics of viral infection in several situations, including exposure to drugs in pharmacological studies, and possibly studies and analyses of the immune response in vaccine therapies.Recentes estudos demonstraram o uso do vírus raiva como modelo vetor para produzir vacinas expressando as glicoproteínas do vírus HIV-1. A homologia na seqüência entre gp120 do vírus HIV-1 e a glicoproteína G do vírus rábico já foi previamente relatada. Devido a estes fatos a linhagem de célula McCoy utilizada com sucesso para a replicação do vírus rábico foi utilizada para demonstrar a replicação do HIV-1. Amostra de HIV-1 foi isolada de plasma de um paciente soro positivo e inoculada em células de linhagem McCoy e então a infecção viral foi estudada em passagens sucessivas do vírus nesta célula. As proteínas liberadas no meio extra celular foram analisadas quanto a atividade biológica pela técnica de eletroforese em gel de poliacrilamida e imunotransferência em membrana de nitro-celulose reagindo com soros positivos para HIV-1 e soros de pacientes negativos. As passagens sucessivas do HIV-1 em células demonstraram a replicação viral, o aumento da permeabilidade da membrana citoplasmática, a formação de sinsício e lise celular. Análises com citometria de fluxo mostraram com clara evidência a presença de receptores CD4+ o que possivelmente deve ser a causa que possibilita a facilidade do isolamento e replicação do vírus HIV-1 nesta célula. Concluindo os resultados observados permitem utilizar esta linhagem celular como um possível modelo para isolamentos de HIV, bem como realizar estudos da dinâmica de infecção viral em diversas situações inclusive de exposição a drogas em estudos farmacológicos, e talvez estudos e análises da resposta imune em terapias vacinais

Orofacial Rhabdomyosarcoma : report of a case and review of the literature

Rhabdomyosarcomas (RMS) are among the most common soft-tissue tumors in children. These tumors are derived from mesenchymal tissue with a tendency toward myogenic differentiation that probably originates from immature and highly invasive satellite cells associated with the embryogenesis of skeletal muscle. Some of these tumors are associated with high rates of recurrence and metastasis. The diagnosis is made by microscopic analysis and auxiliary techniques such as immunohistochemistry, electron microscopy, cytogenetic analysis, and molecular biology. We report here a case of orofacial RMS in a 4-year-old child and provide an updated review of the literature, focusing mainly on the clinicopathological aspects, diagnosis and treatment of RMS of the head and neck

The Genetic Background of Metabolic Trait Clusters in Children and Adolescents

Background: It is well known that metabolic risk factors of cardiovascular diseases are correlated, but the background of this clustering in children is more poorly known than in adults. Thus, we studied the contribution of genetic and environmental factors to the clustering of metabolic traits in childhood and adolescence. Data and Methods: Nine metabolic traits were measured in 214 complete twin pairs aged 3-18 years in the Autonomous Region of Madeira, Portugal, in 2007 and 2008. The variation of and covariations between the traits were decomposed into genetic and environmental components by using classical genetic twin modeling. Results: A model, including additive genetic and environmental factors unique for each twin individual, explained the variation of metabolic factors well. Under this model, the heritability estimates varied from 0.47 (systolic blood pressure in children under 12 years of age) to 0.91 (high-density lipoprotein [HDL] cholesterol in adolescents 12 years of age or older). The most systematic correlations were found between adiposity (body mass index and waist circumference) and blood lipids (HDL cholesterol, low-density lipoprotein cholesterol, and triglycerides), as well as blood pressure. These correlations were mainly explained by common genetic factors. Conclusions: Our results suggest that obesity, in particular, is behind the clustering of metabolic factors in children and adolescents. Both general and abdominal obesity partly share the same genetic background as blood lipids and blood pressure. Obesity prevention early in childhood is important in reducing the risk of metabolic diseases in adulthood.Peer reviewe

Comparison of Apoptotic Cells Between Cryopreserved Ejaculated Sperm and Epididymal Sperm in Stallions

AbstractThe development of a reliable technique to freeze epididymal semen would provide a unique opportunity to preserve valuable genetic material from unexpectedly lost stallions. The aim of this study was to compare the apoptotic indices of sperm obtained from ejaculate, sperm recently recovered from the epididymides (EP), and sperm recovered from epididymides stored at 5°C for 24 hours (EP-stored). For the first category, two ejaculates from seven stallions were collected and then submitted to cryopreservation using an egg yolk-based extender. One week after the last semen collection, the stallions were submitted to bilateral orchiectomy, and sperm from one of the cauda epididymis was harvested immediately after castration (EP). The remaining testicle was stored in a passive refrigeration container at 5°C for 24 hours before the cauda epididymal sperm was harvested (EP-stored). Sperm harvesting from the epididymis for EP and EP-stored was performed by retrograde flushing of the caudal portion of the epididymis using a skim milk-based extender. The recovered sperm was then cryopreserved using the egg yolk-based extender. Sperm motility parameters were studied by computer-assisted semen analysis, and apoptosis was estimated by measuring caspase activity and membrane phospholipid translocation using epifluorescence microscopy. The samples were evaluated immediately (0 hour) and 8 hours after thawing. At 0 hour, no differences in sperm parameters were observed among the groups, but after 8 hours, significant statistical differences were observed in sperm motility parameters and plasma membrane integrity among the treatment groups. In addition, viable cells with no apoptotic signs were more prevalent in EP and EP-stored, suggesting that epididymal sperm is less sensitive to the cold shock caused by sperm cryopreservation

Factors related to survival in Intensive Care Unit patients with Covid-19: a study from a single center in Brazil

Introduction: Analysis of the outcome of 268 ICU patients in a single-center, as well the impact of viral infection on patients with preexisting medical conditions and how these factors affected survival and hospital stay. Methodology: Patients admitted to the ICU from March-August, 2020 were retrospectively analyzed under the same protocol at Hospital Alemão Oswaldo Cruz, São Paulo, Brazil. Several factors were considered and the results were presented using 95% confidence intervals. For statistical significance, p <0.05 was adopted. Results: Patient median age was 72 years, 64,2 years for discharged patients and 79.9 years for those deceased (p<0.001). The most common comorbidities were: systemic arterial hypertension, diabetes, thyroid disease, cardiovascular and kidney disease. Predictors of survival through univariate analysis: myalgia (p=0.001), cerebrovascular disease (p=0.002), COPD (p=0.003), dementia (p=0.000), mechanical ventilation (p=0.000), dialysis (0.000), vasopressor use (0.000), SAPS3 (0.000), lymphopenia (p=0.004), elevated D-dimer (P=0.011), time in ICU before tracheostomy (p=0.002), and performing a tracheostomy (p=0.000). The independent predictors of mortality were: advanced age (p=0.003) and tracheostomy performed in ICU (p=0.002). Discussion: COVID-19 affects usually older adults, where there already is a higher fatality rate. Acute respiratory distress syndrome is the primary cause of death and <5% of patients were reported as experiencing co-infection at admission. Conclusion: age, vasopressor use in patients with tracheostomy, and systemic coronary disease, heart failure, neoplasia, and COPD, were found to be significantly associated with COVID-19 severity