37 resultados para Science in Brazil
Resumo:
Native bees are important providers of pollination services, but there are cumulative evidences of their decline. Global changes such as habitat losses, invasions of exotic species and climate change have been suggested as the main causes of the decline of pollinators. In this study, the influence of climate change on the distribution of 10 species of Brazilian bees was estimated with species distribution modelling. We used Maxent algorithm (maximum entropy) and two different scenarios, an optimistic and a pessimistic, to the years 2050 and 2080. We also evaluated the percentage reduction of species habitat based on the future scenarios of climate change through Geographic Information System (GIS). Results showed that the total area of suitable habitats decreased for all species but one under the different future scenarios. The greatest reductions in habitat area were found for Melipona bicolor bicolor and Melipona scutellaris, which occur predominantly in areas related originally to Atlantic Moist Forest. The species analysed have been reported to be pollinators of some regional crops and the consequence of their decrease for these crops needs further clarification. (C) 2012 Elsevier B.V. All rights reserved.
Resumo:
Plasmodium malariae is a protozoan parasite that causes malaria in humans and is genetically indistinguishable from Plasmodium brasilianum, a parasite infecting New World monkeys in Central and South America. P. malariae has a wide and patchy global distribution in tropical and subtropical regions, being found in South America, Asia, and Africa. However, little is known regarding the genetics of these parasites and the similarity between them could be because until now there are only a very few genomic sequences available from simian Plasmodium species. This study presents the first molecular epidemiological data for P. malariae and P. brasilianum from Brazil obtained from different hosts and uses them to explore the genetic diversity in relation to geographical origin and hosts. By using microsatellite genotyping, we discovered that of the 14 human samples obtained from areas of the Atlantic forest, 5 different multilocus genotypes were recorded, while in a sample from an infected mosquito from the same region a different haplotype was found. We also analyzed the longitudinal change of circulating plasmodial genetic profile in two untreated non-symptomatic patients during a 12-months interval. The circulating genotypes in the two samples from the same patient presented nearly identical multilocus haplotypes (differing by a single locus). The more frequent haplotype persisted for almost 3 years in the human population. The allele Pm09-299 described previously as a genetic marker for South American P. malariae was not found in our samples. Of the 3 non-human primate samples from the Amazon Region, 3 different multilocus genotypes were recorded indicating a greater diversity among isolates of P. brasilianum compared to P. malariae and thus, P. malariae might in fact derive from P. brasilianum as has been proposed in recent studies. Taken together, our data show that based on the microsatellite data there is a relatively restricted polymorphism of P. malariae parasites as opposed to other geographic locations. (c) 2012 Elsevier B.V. All rights reserved.
Resumo:
The history of the quinine synthesis can be used as a case study to emphasize that science is influenced by social and historical processes. The first efforts toward the synthesis of this substance, which until recently was the only treatment for malaria, were by Perkin in 1856 when, trying to obtain quinine,,. he synthesized mauveine. Since then, the quest for the total synthesis of quinine involved several characters in a web of controversies. A major step in this process was made in 1918 by Rabe and Kindler, who proposed the synthesis of quinine from quinotoxine. Twenty-six years later, after obtaining the total synthesis of quinotoxine, Woodward and Doering announced the total synthesis of quinine. However, the lack of experimental details about Rabe and Kindler's process, associated with Woodward and Doering's failure to reproduce it, raised a series of doubts about the synthesis. Stork and colleagues questioned the veracity of the experimental data and even the scientific reputation of the involved researchers. Doubts remained alive until 2008, when Williams and Smith reported, not without reservations, the reproducibility of Rabe and Kindler's protocol. The scientific knowledge as a social and historical development, its legitimating process, and the absence of neutrality in science constitute aspects that can be discussed from this case study, providing significant contributions to science education, in particular, to the initial or continued training of chemistry teachers.
Resumo:
The global emergence of vancomycin-resistant Enterococcus faecium (VREfm) has been characterized by a clonal spread of strains belonging to clonal complex 17 (CC17). Genetic features and clonal relationships of 53 VREfm isolated from patients in 2 hospitals in Ribeirao Preto, Sao Paulo, Brazil, during 2005-2010 were determined as a contribution to the Brazilian evolutionary history of these nosocomial pathogens. All isolates were daptomycin susceptible, vancomycin-resistant, and had the vanA gene. The predominant virulence genes were acm and esp. Only 5 VREfm isolated in 2005-2006 had intact Tn1546, while 81% showed Tn1546 with deleted left extremity and insertion of IS1251 between the vanS and vanH genes. Multilocus sequence typing analysis permitted the identification of 9 different sequence types (STs), with 5 being new ones (656, 657, 658, 659, and 660). Predominant STs were ST412 and ST478, all belonging to CC17, except ST658. This is the first report of the ST78 in Brazil. (c) 2012 Elsevier Inc. All rights reserved.
Resumo:
Abstract Background Hepatitis C chronic liver disease is a major cause of liver transplant in developed countries. This article reports the first nationwide population-based survey conducted to estimate the seroprevalence of HCV antibodies and associated risk factors in the urban population of Brazil. Methods The cross sectional study was conducted in all Brazilian macro-regions from 2005 to 2009, as a stratified multistage cluster sample of 19,503 inhabitants aged between 10 and 69 years, representing individuals living in all 26 State capitals and the Federal District. Hepatitis C antibodies were detected by a third-generation enzyme immunoassay. Seropositive individuals were retested by Polymerase Chain Reaction and genotyped. Adjusted prevalence was estimated by macro-regions. Potential risk factors associated with HCV infection were assessed by calculating the crude and adjusted odds ratios, 95% confidence intervals (95% CI) and p values. Population attributable risk was estimated for multiple factors using a case–control approach. Results The overall weighted prevalence of hepatitis C antibodies was 1.38% (95% CI: 1.12%–1.64%). Prevalence of infection increased in older groups but was similar for both sexes. The multivariate model showed the following to be predictors of HCV infection: age, injected drug use (OR = 6.65), sniffed drug use (OR = 2.59), hospitalization (OR = 1.90), groups socially deprived by the lack of sewage disposal (OR = 2.53), and injection with glass syringe (OR = 1.52, with a borderline p value). The genotypes 1 (subtypes 1a, 1b), 2b and 3a were identified. The estimated population attributable risk for the ensemble of risk factors was 40%. Approximately 1.3 million individuals would be expected to be anti-HCV-positive in the country. Conclusions The large estimated absolute numbers of infected individuals reveals the burden of the disease in the near future, giving rise to costs for the health care system and society at large. The known risk factors explain less than 50% of the infected cases, limiting the prevention strategies. Our findings regarding risk behaviors associated with HCV infection showed that there is still room for improving strategies for reducing transmission among drug users and nosocomial infection, as well as a need for specific prevention and control strategies targeting individuals living in poverty.
Resumo:
Introduction and Objectives: Vancomycin is indicated to patients who have not responded to treatment with other antibiotics in serious infections caused by organisms susceptible to it and resistant to other antimicrobials. However, over the last five years, many adverse reactions have been reported with this medicine in the University Hospital of the University of Silo Paulo (HU/USP), such as nephrotoxicity and toxicity related to infusion. Some critical patients, for example surgical patients with sepsis and severe trauma are generally susceptible to renal failure due to the severity of the underlying disease. The-aim of this study is to quantify and delineate the epidemiological profile of confirmed adverse reactions caused by vancomycin. Material and Methods: We conducted a retrospective observational quantitative study of medical records of patients who had confirmed.adverse reactions occurred with vancomycin in the period from January 2007 to May 2012, at the HU/USP - Brazil. All notifications related to vancomycin were evaluated in the following items: age and sex of patients, type and ward where the adverse event occurred involving this drug. Results and Conclusions: During the analysed period, were confinued 37 adverse events with vancomycn. The adults represented 75,7% of the cases, and the children 24,3%. The present study shows that adult patients admitted to the medical clinic had greater susceptibility to adverse reactions to vancomycin and for pediatric patients its higher frequency was at ICU. Despite the adverse skin reactions performed with greater frequency, it is known that the most severe reactions were related to the kidney resulting in more complex clinical interventions.
Resumo:
The Light Steel Framing building technology was introduced in Brazil in the late 1990s for the construction of residential houses. Because the design system was imported from the United States and is optimised to work well in that temperate climate, some modi fi cations must be made to adapt it for the Brazilian climate. The objective of this paper was to assess the impact of thermal bridging across enclosure elements on the thermal performance of buildings designed with Light Steel Framing in Brazil. The numerical simulation program EnergyPlus and a speci fi c method that considered the effects of metallic structures in the hourly simulations were used for the analysis. Two air-conditioned commercial buildings were used as case studies. The peak thermal load increased approximately 10% when an interior metal frame was included in the numerical simulations compared to non-metallic structures. Even when a metal frame panel was used only for vertical elements in the facade of a building with a conventional concrete structure, the simulations showed a 5% increase in annual energy use.