973 resultados para genetic heterogeneity of environmental variation
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Critical Issues in Environmental Taxation: International and Comparative Perspectives: Volume VI, 699-715
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In the present study we report the results of an analysis, based on serotyping, multilocus enzyme electrophoresis (MEE), and ribotyping of N. meningitidis serogroup C strains isolated from patients with meningococcal disease (MD) in Rio Grande do Sul (RS) and Santa Catarina (SC) States, Brazil, as the Center of Epidemiology Control of Ministry of Health detected an increasing of MD cases due to this serogroup in the last two years (1992-1993). We have demonstrated that the MD due to N.meningitidis serogroup C strains in RS and SC States occurring in the last 4 years were caused mainly by one clone of strains (ET 40), with isolates indistinguishable by serogroup, serotype, subtype and even by ribotyping. One small number of cases that were not due to an ET 40 strains, represent closely related clones that probably are new lineages generated from the ET 40 clone referred as ET 11A complex. We have also analyzed N.meningitidis serogroup C strains isolated in the greater São Paulo in 1976 as representative of the first post epidemic year in that region. The ribotyping method, as well as MEE, could provide useful information about the clonal characteristics of those isolates and also of strains isolated in south Brazil. The strains from 1976 have more similarity with the actual endemic than epidemic strains, by the ribotyping, sulfonamide sensitivity, and MEE results. In conclusion, serotyping with monoclonal antibodies (C:2b:P1.3), MEE (ET 11 and ET 11A complex), and ribotyping by using ClaI restriction enzyme (Rb2), were useful to characterize these epidemic strains of N.meningitidis related to the increased incidence of MD in different States of south Brazil. It is mostly probable that these N.meningitidis serogroup C strains have poor or no genetic corelation with 1971-1975 epidemic serogroup C strains. The genetic similarity of members of the ET 11 and ET 11A complex were confirmed by the ribotyping method by using three restriction endonucleases.
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In the present study we report the results of an analysis, based on ribotyping of Corynebacterium diphtheriae intermedius strains isolated from a 9 years old child with clinical diphtheria and his 5 contacts. Quantitative analysis of RFLPs of rRNA was used to determine relatedness of these 7 C.diphtheriae strains providing support data in the diphtheria epidemiology. We have also tested those strains for toxigenicity in vitro by using the Elek's gel diffusion method and in vivo by using cell culture method on cultured monkey kidney cell (VERO cells). The hybridization results revealed that the 5 C.diphtheriae strains isolated from contacts and one isolated from the clinical case (nose case strain) had identical RFLP patterns with all 4 restriction endonucleases used, ribotype B. The genetic distance from this ribotype and ribotype A (throat case strain), that we initially assumed to be responsible for the illness of the patient, was of 0.450 showing poor genetic correlation among these two ribotypes. We found no significant differences concerned to the toxin production by using the cell culture method. In conclusion, the use of RFLPs of rRNA gene was successful in detecting minor differences in closely related toxigenic C.diphtheriae intermedius strains and providing information about genetic relationships among them.
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Journal of Cleaner Production, nº 17, p. 36-52
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PLos One, 4(11): ARTe7722
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The aim of the present study was to determine biological characteristics such as expression of fimbriae, Congo red binding, production of hemolysin and aerobactin, adhesion to HeLa and uroepithelial cells and invasion of HeLa cells by Escherichia coli isolates obtained from patients showing clinical signs of urinary tract infection (UTI). Also, the presence of genes (apa, afa, spa) for fimbria expression and cytotoxic necrotizing factors (CNF1, CNF2) was assayed using specific primers in PCR. The data obtained were compared with the clonal relationships obtained by analysis of multilocus enzyme electrophoresis (MLEE), restriction fragment length polymorphism (RFLP) of the rDNA (ribotyping) and enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). All isolates but one presented a combination of at least two of the characteristics studied, a fact suggesting the presence of pathogenicity islands (PAIs). Diffuse adherence type to HeLa cells was observed to occur in most of the strains, but adhesion to uroepithelial cells seems to be a more reliable test to verify pathogenicity. Although four strains seemed to be able to invade HeLa cells when assayed by light microscopy, electron microscopy studies demonstrated that these strains were not invasive. MLEE, RFLP and ERIC-PCR were able to group the isolates differently into main clusters that were not correlated with the presence of pathogenic traits.
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Random amplified polymorphic DNA (RAPD) technique is a simple and reliable method to detect DNA polymorphism. Several factors can affect the amplification profiles, thereby causing false bands and non-reproducibility of assay. In this study, we analyzed the effect of changing the concentration of primer, magnesium chloride, template DNA and Taq DNA polymerase with the objective of determining their optimum concentration for the standardization of RAPD technique for genetic studies of Cuban Triatominae. Reproducible amplification patterns were obtained using 5 pmoL of primer, 2.5 mM of MgCl2, 25 ng of template DNA and 2 U of Taq DNA polymerase in 25 µL of the reaction. A panel of five random primers was used to evaluate the genetic variability of T. flavida. Three of these (OPA-1, OPA-2 and OPA-4) generated reproducible and distinguishable fingerprinting patterns of Triatominae. Numerical analysis of 52 RAPD amplified bands generated for all five primers was carried out with unweighted pair group method analysis (UPGMA). Jaccard's Similarity Coefficient data were used to construct a dendrogram. Two groups could be distinguished by RAPD data and these groups coincided with geographic origin, i.e. the populations captured in areas from east and west of Guanahacabibes, Pinar del Río. T. flavida present low interpopulation variability that could result in greater susceptibility to pesticides in control programs. The RAPD protocol and the selected primers are useful for molecular characterization of Cuban Triatominae.
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The genetic diversity of 23 oral Fusobacterium nucleatum isolated from 15 periodontal patients, eight from seven healthy subjects, nine from nine AIDS patients and two from two Cebus apella monkeys were analyzed. EcoRI restricted the bacterial DNA and 28 ribotypes grouped from A to J groups were obtained. Isolates formed 24 ribotypes which were contained into A, B, C, D, E and F groups, and three reference strains and two clinical isolates of A. actinomycetemcomitans, and E. coli CDC formed four different ribotypes into the G, H, I and J groups. Moreover, from nine F. nucleatum from AIDS patients, six were ribotyped as group C and three as group D. By using ribotyping we distinguished F. nucleatum recovered from different sources. It is possible that isolates from AIDS patients may contain some phenotypic or genotypic factor did not observed in this study.
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Human exposure to persistent organic pollutants (POPs) is a certainty, even to long banned pesticides like o,p′-dichlorodiphenyltrichloroethane (o,p′-DDT), and its metabolites p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE), and p,p′-dichlorodiphenyldichloroethane (p,p′-DDD). POPs are known to be particularly toxic and have been associated with endocrine-disrupting effects in several mammals, including humans even at very low doses. As environmental estrogens, they could play a critical role in carcinogenesis, such as in breast cancer. With the purpose of evaluating their effect on breast cancer biology, o,p′-DDT, p,p′-DDE, and p,p′-DDD (50–1000 nM) were tested on two human breast adenocarcinoma cell lines: MCF-7 expressing estrogen receptor (ER) α and MDA-MB-231 negative for ERα, regarding cell proliferation and viability in addition to their invasive potential. Cell proliferation and viability were not equally affected by these compounds. In MCF-7 cells, the compounds were able to decrease cell proliferation and viability. On the other hand, no evident response was observed in treated MDA-MB-231 cells. Concerning the invasive potential, the less invasive cell line, MCF-7, had its invasion potential significantly induced, while the more invasive cell line MDA-MB-231, had its invasion potential dramatically reduced in the presence of the tested compounds. Altogether, the results showed that these compounds were able to modulate several cancer-related processes, namely in breast cancer cell lines, and underline the relevance of POP exposure to the risk of cancer development and progression, unraveling distinct pathways of action of these compounds on tumor cell biology.
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Context: Some chemicals used in consumer products or manufacturing (eg, plastics, pesticides) have estrogenic activities; these xenoestrogens (XEs) may affect immune responses and have recently emerged as a new risk factors for obesity and cardiovascular disease. However, the extent and impact on health of chronic exposure of the general population to XEs are still unknown. Objective: The objective of the study was to investigate the levels of XEs in plasma and adipose tissue (AT) depots in a sample of pre- and postmenopausal obese women undergoing bariatric surgery and their cardiometabolic impact in an obese state. Design and Participants: We evaluated XE levels in plasma and visceral and subcutaneous AT samples of Portuguese obese (body mass index ≥ 35 kg/m2) women undergoing bariatric surgery. Association with metabolic parameters and 10-year cardiovascular disease risk was assessed, according to menopausal status (73 pre- and 48 postmenopausal). Levels of XEs were determined by gas chromatography with electron-capture detection. Anthropometric and biochemical data were collected prior to surgery. Adipocyte size was determined on tissue sections obtained during surgery. Results: Our data show that XEs are pervasive in this obese population. Distribution of individual and concentration of total XEs differed between plasma, visceral AT, and subcutaneous AT, and the pattern of accumulation was different between pre- and postmenopausal women. Significant associations between XE levels and metabolic and inflammatory parameters were found. In premenopausal women, XEs in plasma seem to be a predictor of 10-year cardiovascular disease risk. Conclusions: Our findings point toward a different distribution of XE between plasma and AT in pre- and postmenopausal women, and reveal the association between XEs on the development of metabolic abnormalities in obese premenopausal women
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Although the main transmitters of rabies in Brazil are dogs and vampire bats, the role of other species such as insectivorous and frugivorous bats deserves special attention, as the rabies virus has been isolated from 36 bat species. This study describes the first isolation of the rabies virus from the insectivorous bat Eumops perotis. The infected animal was found in the city of Ribeirão Preto, São Paulo. The virus was identified by immunofluorescence antibody test (FAT) in central nervous system (CNS) samples, and the isolation was carried out in N2A cell culture and adult mice. The sample was submitted to antigenic typing using a panel of monoclonal antibodies (CDC/Atlanta/USA). The DNA sequence of the nucleoprotein gene located between nucleotides 102 and 1385 was aligned with homologous sequences from GenBank using the CLUSTAL/W method, and the alignment was used to build a neighbor-joining distance-based phylogenetic tree with the K-2-P model. CNS was negative by FAT, and only one mouse died after inoculation with a suspension from the bat's CNS. Antigenic typing gave a result that was not compatible with the patterns defined by the panel. Phylogenetic analysis showed that the virus isolated segregated into the same cluster related to other viruses isolated from insectivorous bats belonging to genus Nyctinomops ssp. (98.8% nucleotide identity with each other).
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Cryptococcus neoformans is the major cause of fungal meningitis, a potentially lethal mycosis. Bird excreta can be considered a significant environmental reservoir of this species in urban areas, thirty-three samples of pigeon excreta were collected within the city of Vitoria, Brazil. Cryptococcus neoformans was isolated and identified using standard biochemical assays in ten samples. PCR amplification with primer M13 and orotidine monophosphate pyrophosphorylase (URA5) gene-restriction fragment length polymorphism (RFLP) analysis discerned serotypes and genotypes within this species. All isolates were serotype A (C. neoformans var. grubii) and genotype VNI. The two alternative alleles a and α at the mating type locus were determined by PCR amplification and mating assays performed on V8 medium. All isolates were MAT α mating type but only 50% were able to mate in vitro with the opposite mating type MAT a tester strains (JEC20, KN99a and Bt63). This study adds information on the ecology and molecular characterization of C. neoformans in the Southeast region of Brazil.
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The Triatominae (Hemiptera:Reduviidae) contains the principal and potential Chagas disease vectors present in Mexico, Central America and South America. Triatoma flavida and T. bruneri are Cuban species. These species are closely related according to morphology and were considered synonyms until 1981, when they were separated on the grounds of external characters of the body and the morphology of male genitalia. The present study seeks to analyze genetic polymorphism of T. flavida and T. bruneri populations using RAPD techniques, and to assess the genetic relationship between these species. Ten random primers were used to evaluate the genetic variability among species using RAPD-PCR. The genetic flow among them was calculated. The dendrogram based on calculated Jaccard distances showed two clearly distinguishable clusters which coincided with the studied species. Within each species, moderate genetic differentiation (Fst 0.05-0.15) and migration rates (N > 1) were found among populations, that reveal gene flow and genetic homogeneity. Between species, the Fst value showed a high genetic differentiation and the migration rate was insufficient to maintain genetic homogeneity, and confirmed the absence of gene flow between them. Our results confirm the genetic variability among T. flavida and T. bruneri species.
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Cryptosporidium spp. and Cystoisospora belli are monoxenic protozoa that have been recognized as the causative agents of chronic diarrhea in immunocompromised individuals, especially HIV-infected subjects. The objective of this study was to evaluate the frequency of these intestinal protozoa in HIV-positive patients in the Triângulo Mineiro region of Brazil and to correlate the presence of these infections with clinical, epidemiological and laboratory data of the patients. Oocysts were detected in stool samples of 10 (16.9%) of the 59 patients studied, while Cryptosporidium spp. were present in 10.1% (6/59) and C. belli in 6.7% (4/59). The frequency of these parasites was higher among patients with diarrheic syndrome and CD4+ T lymphocyte counts < 200 cells/mm 3 , demonstrating the opportunistic characteristic of these infections. A significant association was observed between the lack of adherence to antiretroviral therapy and the presence of Cryptosporidium spp. and/or C. belli. Parasitism with Cryptosporidium spp. was more frequent in February and April, the months following the period of high rainfall. The same was not observed for C. belli. Genetic characterization of two isolates led to the identification of Cryptosporidium parvum, one of the main species associated with the zoonotic transmission of cryptosporidiosis.