Search

Chromitite layers in mafic-ultramafic layered intrusions represent a special case of cumulate rock where chromite is the sole liquidus (cumulus) mineral. Different mechanisms for the formation of chromitite layers have been postulated. In order to provide geological and petrological constraints for these models, chromitites and hosting mafic and ultramafic rocks from the Bacuri, Niquelândia and Ipueira-Medrado layered complexes in Brazil were investigated. The Bacuri Complex (2·2 Ga) is a large layered intrusion of the Amazon Craton. Chromitite layers of the Bacuri mafic-ultramafic complex are restricted to a 30–120 m-thick sequence of ultramafic cumulates overlying mafic cumulates. Most of the chromite is concentrated in a several metres-thick chromitite layer (the main chromitite) located at the base of the ultramafic cumulates. Cryptic variation of olivine with stratigraphic height (from Fo89 at the base to Fo76 at the top) is consistent with extensive fractionation of the ultramafic sequence. The stratigraphic position of the main chromitite supports a model for its origin associated with a major new influx of primitive parental magma. The cause of chromite saturation must therefore result from changes in magma composition resulting from mixing new influxes of primitive magma with a fractionated magma resident in the magma chamber... [ABSTRACT FROM AUTHOR]

In many developed countries, insufficient birth weight (IBW) has been decreasing, but in developing countries these rates continue to be high and very few studies have assessed the factors associated with IBW infants and their long term consequences. The main objective is to investigate the possible factors associated with IBW in two cohorts of singleton newborn infants in one of the cities of Brazil, the first study in 1978-1979 and the second in 1994 and to identity the causes of the increase in IBW that occurred during this period.

Abstract The recovery or collection of postmortem semen raises relevant ethical and social concerns. In this study we report 2 cases witnessed by the authors in an organ procurement organization in Brazil. The patients had a diagnosis of brain death, were organ donors, and had no consent for the use of postmortem sperm. In Brazil, the diagnosis of brain death has been clearly established since 1997, with the most recent update in 2017, but has not considered the possibility of the collection of sperm or eggs from the donor. A review of the world literature has been carried out, as well as current legislation in different countries, including Brazil, with special interest in the impact on the autonomy of the deceased (informed consent or not), the wife, the generation of the child and their rights, and the ethical role of the physician. [ABSTRACT FROM AUTHOR]

Objective: To estimate the prevalence and factors associated with hepatitis A, B, and C in transgender women and travestis's networks, in 5 regions of Brazil., Methods: This cross-sectional study includedtransgender women and travestis in five Brazilian capitals (Campo Grande, Manaus, Porto Alegre, Salvador, and São Paulo), between December/2019 and July/2021. All samples were subjected to detection of serological markers of hepatitis virus A (HAV), B (HBV), and C (HCV) infections through rapid tests and chemiluminescent microparticle immunoassays. Positive samples in the screening tests were submitted to detect HBV DNA and HCV-RNA by real-time PCR and genotyped by Sanger sequencing., Results: Analysis of 1,317 samples showed network prevalence rates of 69.1%, 25.1%, and 1.5% for HAV, HBV, and HCV exposure, respectively. A high susceptibility rate to HBV infection (35.7%) and low prevalence of vaccine response markers (40%) were also observed. Age greater than 26 years, self-declared black/brown skin color, having only primary education, history of incarceration, and use of a condom in the last sexual intercourse with a casual partner were associated with total anti-HAV. Exposure to HBV was associated with age greater than 26 years, self-declared black/brown, history of being a sex worker, and incarceration. Age > 37 years, history of sexual abuse, and frequent alcohol consumption were associated with hepatitis C infection., Conclusion: The highest prevalence of HAV in this population was found in the North and Northeast regions, and the prevalence found was higher than that in the general population, suggesting greater vulnerability. The prevalence of HCV infection in our study was similar to that observed in the general population.