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101.
Lucia Libanez Bessa Campelo Braga Maria Aparecida Alves de Oliveira Maria Helane Rocha Batista Gon?alves Fernando Kennedy Chaves Tiago Gomes da Silva Benigno Adriana Dias Gomes Cícero Igor Sim?es Moura Silva Charles Anacleto Sérgio de Assis Batista Dulciene Maria Magalh?es Queiroz 《Memórias do Instituto Oswaldo Cruz》2014,109(8):1045-1049
Helicobacter pylori infection is one of the most common infections
worldwide and is associated with gastric diseases. Virulence factors such as VacA and
CagA have been shown to increase the risk of these diseases. Studies have suggested a
causal role of CagA EPIYA-C in gastric carcinogenesis and this factor has been shown
to be geographically diverse. We investigated the number of CagA EPIYA motifs and the
vacA i genotypes in H. pylori strains from
asymptomatic children. We included samples from 40 infected children (18 females and
22 males), extracted DNA directly from the gastric mucus/juice (obtained using the
string procedure) and analysed the DNA using polymerase chain reaction and DNA
sequencing. The vacA i1 genotype was present in 30 (75%) samples,
the i2 allele was present in nine (22.5%) samples and both alleles were present in
one (2.5%) sample. The cagA-positive samples showed distinct
patterns in the 3’ variable region of cagA and 18 of the 30 (60%)
strains contained 1 EPIYA-C motif, whereas 12 (40%) strains contained two EPIYA-C
motifs. We confirmed that the studied population was colonised early by the most
virulent H. pylori strains, as demonstrated by the high frequency of
the vacA i1 allele and the high number of EPIYA-C motifs. Therefore,
asymptomatic children from an urban community in Fortaleza in northeastern Brazil are
frequently colonised with the most virulent H. pylori
strains. 相似文献
102.
Ernest J. M. Teo C. Michael Bull Dale Burzacott Myron P. Zalucki Michael J. Furlong Dayana Barker Stephen C. Barker 《Austral ecology》2023,48(3):563-584
Perhaps one of the central questions in ecology has been what limits the geographic distribution of species. The geographic distributions of the reptile-ticks Amblyomma limbatum, Bothriocroton hydrosauri and Amblyomma albolimbatum are a classic example of this problem: where these ticks meet, narrow regions-of-overlap often occur. Despite studies of interactions among these ticks, and of these ticks and their environment, we still do not understand what limits their geographic distributions. Many hypotheses have been proposed and tested, but all have seemingly been rejected. Our aim was to account for the abundance and the geographic distributions of A. limbatum and B. hydrosauri at Bundey Bore Station, South Australia, where these species come in contact and have been studied for over 35 years, leading to over 55 000 records of reptiles and their ticks using a capture-mark-recapture approach. We constructed models which had combinations of temperature and moisture indices from different months of the year to determine the relationship between climate and tick abundance, and between climate and the shifting local geographic distribution of A. limbatum and B. hydrosauri at Bundey Bore Station. We found that climate together with the abundance of ticks in the previous year and the abundance of the lizard host, accounted for 54%–77% of the variation in the abundance of A. limbatum and B. hydrosauri among years. We also found that the climate in late autumn to winter, together with the abundance of ticks and their host, accounted for 18%–84% of the variation in the geographic distributions of these ticks among years. Climate was central to the abundance and the geographic distributions of A. limbatum and B. hydrosauri at Bundey Bore Station. We speculate that the same mechanisms account for the geographic distributions of A. limbatum, B. hydrosauri and A. albolimbatum elsewhere in Australia; so, climate may explain the three-tick problem in Austral ecology. 相似文献