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Schwaiger FW; Weyers E; Buitkamp J; Ede AJ; Crawford A; Epplen JT 《Molecular biology and evolution》1994,11(2):239-249
Exon 2 sequences of an expressed MHC-DRB locus from sheep were examined for
polymorphisms in both the antigen-binding regions and the adjacent intronic
mixed simple tandem repeat. Twenty-one novel exon 2 Ovar-DRB alleles were
identified. Short nucleotide motifs are extensively shared between certain
exon 2 regions of Ovar-DRB alleles. The simple repeat variations, the
number of different amino acids at usually polymorphic sites, and the
number of silent substitutions were reduced in the intraspecies analyses of
sheep DRB sequences, compared with those of cattle and goats. It was
paradoxical that the abundance of different sheep alleles was similar to
that of cattle and goats. This paradox may be explained by postulating a
relatively small number of "ancient" alleles, with the present-day Ovar-DRB
alleles being generated by reciprocal exchange of nucleotide motifs. At the
antigen-binding sites, new combinations of amino acids were maintained in
Ovar-DRB alleles by strong positive selection. In sheep--and less
pronounced in goats and cattle--the DRB alleles can be divided into two
groups. In one group, silent substitutions are increased when compared with
the other. This suggests separate evolutionary pathways for certain groups
of DRB alleles within a species. The simple repetitive sequences are also
discussed with respect to the evolution of DRB alleles.
相似文献
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Babauta JT Nguyen HD Harrington TD Renslow R Beyenal H 《Biotechnology and bioengineering》2012,109(10):2651-2662
The limitation of pH inside electrode‐respiring biofilms is a well‐known concept. However, little is known about how pH and redox potential are affected by increasing current inside biofilms respiring on electrodes. Quantifying the variations in pH and redox potential with increasing current is needed to determine how electron transfer is tied to proton transfer within the biofilm. In this research, we quantified pH and redox potential variations in electrode‐respiring Geobacter sulfurreducens biofilms as a function of respiration rates, measured as current. We also characterized pH and redox potential at the counter electrode. We concluded that (1) pH continued to decrease in the biofilm through different growth phases, showing that the pH is not always a limiting factor in a biofilm and (2) decreasing pH and increasing redox potential at the biofilm electrode were associated only with the biofilm, demonstrating that G. sulfurreducens biofilms respire in a unique internal environment. Redox potential inside the biofilm was also compared to the local biofilm potential measured by a graphite microelectrode, where the tip of the microelectrode was allowed to acclimatize inside the biofilm. Biotechnol. Bioeng. 2012; 109: 2651–2662. © 2012 Wiley Periodicals, Inc. 相似文献
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David JT. Campbell Paul E. Ronksley Braden J. Manns Marcello Tonelli Claudia Sanmartin Robert G. Weaver Deirdre Hennessy Kathryn King-Shier Tavis Campbell Brenda R. Hemmelgarn for the Interdisciplinary Chronic Disease Collaboration 《PloS one》2014,9(4)
Background
Management of chronic diseases requires patients to adhere to recommended health behavior change and complete tests for monitoring. While studies have shown an association between low income and lack of adherence, the reasons why people with low income may be less likely to adhere are unclear. We sought to determine the association between household income and receipt of health behavior change advice, adherence to advice, receipt of recommended monitoring tests, and self-reported reasons for non-adherence/non-receipt.Methods
We conducted a population-weighted survey, with 1849 respondents with cardiovascular-related chronic diseases (heart disease, hypertension, diabetes, stroke) from Western Canada (n = 1849). We used log-binomial regression to examine the association between household income and the outcome variables of interest: receipt of advice for and adherence to health behavior change (sodium reduction, dietary improvement, increased physical activity, smoking cessation, weight loss), reasons for non-adherence, receipt of recommended monitoring tests (cholesterol, blood glucose, blood pressure), and reasons for non-receipt of tests.Results
Behavior change advice was received equally by both low and high income respondents. Low income respondents were more likely than those with high income to not adhere to recommendations regarding smoking cessation (adjusted prevalence rate ratio (PRR): 1.55, 95%CI: 1.09–2.20), and more likely to not receive measurements of blood cholesterol (PRR: 1.72, 95%CI 1.24–2.40) or glucose (PRR: 1.80, 95%CI: 1.26–2.58). Those with low income were less likely to state that non-adherence/non-receipt was due to personal choice, and more likely to state that it was due to an extrinsic factor, such as cost or lack of accessibility.Conclusions
There are important income-related differences in the patterns of health behavior change and disease monitoring, as well as reasons for non-adherence or non-receipt. Among those with low income, adherence to health behavior change and monitoring may be improved by addressing modifiable barriers such as cost and access. 相似文献46.
Spatial and temporal variation in malaria transmission in a low endemicity area in northern Tanzania
MJAM Oesterholt JT Bousema OK Mwerinde C Harris P Lushino A Masokoto H Mwerinde FW Mosha CJ Drakeley 《Malaria journal》2006,5(1):1-7
Background
Current detection or screening for malaria infection necessitates drawing blood by fingerprick or venipuncture, which poses risks and limitations for repeated measurement. This study presents PCR detection of Plasmodium falciparum in human urine and saliva samples, and illustrates this potential application in genotyping malaria infections.Methods
Urine and saliva were obtained from 47 thick film positive and 4 negative individuals one day after collection of blood slides and filter paper blood spots. P. falciparum DNA was extracted from blood, urine and saliva, in separate groups, using the Chelex method or Qiagen DNEasy® kit (urine and saliva only). Blood, urine and saliva extracts were subjected to PCR in separate batches. Amplicons from the various sample types were examined for MSP2 polymorphisms and restriction fragment patterns on DHFR amino acid codon 59.Results and discussion
Malaria infections exhibited primarily low-grade parasite densities, with a geometric mean of 775 asexual parasites/μl. Regularly matching polymorphic MSP2 genotypes were found between the corresponding urine, saliva and peripheral blood amplicons of each individual, with different inter-individual polymorphic genotypes. Amplicon yields were significantly dependent on DNA extraction method, parasite density and primer set (p < 0.001). A Qiagen® kit extraction had more than 2× higher amplicon yield than the Chelex method, for both urine and saliva. Amplicon yields were 1.6 fold higher from saliva than urine. For each unit increase in log parasite density, the probability of amplicon enhanced 1.8 fold. Highest amplicon yields were obtained from the primer set with the shortest PCR product.Conclusion
P. falciparum infection is detectable by PCR on human urine and saliva samples. Subject to further refinement of extraction technique and amplicon yields, large-scale malaria parasite screening and epidemiological surveys could be possible without the need to collect blood and use of needles or sharps. 相似文献47.
One of the methods of controlling biofilms that has widely been discussed in the literature is to apply a potential or electrical current to a metal surface on which the biofilm is growing. Although electrochemical biofilm control has been studied for decades, the literature is often conflicting, as is detailed in this review. The goals of this review are: (1) to present the current status of knowledge regarding electrochemical biofilm control; (2) to establish a basis for a fundamental definition of electrochemical biofilm control and requirements for studying it; (3) to discuss current proposed mechanisms; and (4) to introduce future directions in the field. It is expected that the review will provide researchers with guidelines on comparing datasets across the literature and generating comparable datasets. The authors believe that, with the correct design, electrochemical biofilm control has great potential for industrial use. 相似文献
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Wouter Meuleman Judith YMN Engwegen Marie-Christine W Gast Jos H Beijnen Marcel JT Reinders Lodewyk FA Wessels 《BMC bioinformatics》2008,9(1):88
Background
Mass spectrometry for biological data analysis is an active field of research, providing an efficient way of high-throughput proteome screening. A popular variant of mass spectrometry is SELDI, which is often used to measure sample populations with the goal of developing (clinical) classifiers. Unfortunately, not only is the data resulting from such measurements quite noisy, variance between replicate measurements of the same sample can be high as well. Normalisation of spectra can greatly reduce the effect of this technical variance and further improve the quality and interpretability of the data. However, it is unclear which normalisation method yields the most informative result. 相似文献49.
Statistical tests for multivariate bioequivalence 总被引:3,自引:0,他引:3
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Erdogan Taskesen Renee Beekman Jeroen de Ridder Bas J Wouters Justine K Peeters Ivo P Touw Marcel JT Reinders Ruud Delwel 《BMC bioinformatics》2010,11(1):275