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1.
Thorsten Thye Genevieve Scarisbrick Edmund N. L. Browne Margaret Amanua Chinbuah John Gyapong Ivy Osei Ellis Owusu-Dabo Stefan Niemann Sabine Rüsch-Gerdes Christian G. Meyer Rolf D. Horstmann 《PloS one》2009,4(7)
The gene of Cytotoxic T Lymphocyte-associated Antigen 4 (CTLA4), a negative regulator of T lymphocytes, contains a single-nucleotide polymorphism (SNP) at position +6230A->G (ct60A->G), which has been found associated with several autoimmune diseases and appears to reduce T-cell inhibitory activity. In Ghana, West Africa, we compared the frequencies of CTLA4 +6230 A/G and 6 haplotype-tagging SNPs in 2010 smear-positive, HIV-negative patients with pulmonary tuberculosis (TB) and 2346 controls matched for age, gender and ethnicity. We found no difference in allele frequencies between cases and controls. However, +6230A and a distinct CTLA4 haplotype and a diplotype comprising the +6230A allele were significantly less frequent among cases with large opacities in chest radiographs compared to those with small ones (Pcorrected [cor] = 0.002, Pcor = 0.00045, P = 0.0005, respectively). This finding suggests that an increased T-cell activity associated with the CTLA4 +6230G allele contributes to pathology rather than to protection in pulmonary TB. 相似文献
2.
A phosphotransferase-dependent aryl-β-glucoside uptake and utilisation system (abg) was isolated from the ruminal Clostridium (“C. longisporum”). The system is composed of three genes, abgG, abgF and abgA, and a number of regulatory regions, including terminator/antiterminator type stem-loop structures preceding the abgG and abgF genes. Similarity analysis of the proteins encoded by these genes indicated that they were responsible for the regulation
of the abg system through antitermination (AbgG), the uptake and phosphorylation of aryl-β-glucosides (AbgF) and the hydrolysis of the
intracellular phosphorylated glycosides (AbgA). Experimental evidence for the functions of AbgF and AbgA was obtained. Although
it was not possible to demonstrate any function for AbgG, a promoter 5′ to the abgG gene was identified which was responsible for expression of the downstream genes. The abg system is remarkably similar to operons from the gram negative Enterobacteriaceae, both in the coding and non-coding regulatory
regions.
Received: 3 April 1997 / Accepted: 8 September 1997 相似文献
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S. C. Thomson 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1998,353(1375):1595-1606
Speakman and co-workers suggested the diurnal Samoan flying fox, Pteropus samoensis, may be at risk of hyperthermia when flying during the day, particularly at high levels of insolation. We monitored activity of this bat and climate simultaneously at two different sites and four times of year in American Samoa. Flight activity varied significantly with time of day, between days, study sites and seasons. Out of the six data sets collected, the four with the highest mean levels of insolation showed a significant decrease in bat numbers with increasing temperature and sunlight. When each individual activity count was directly compared to the predictions of Speakman and co-workers'' biophysical model, 85 to 95% of bat flight activity was found to be in conditions the model suggested would not pose a risk of hyperthermia. This supports the suggestion that in extreme conditions the animals would not fly as they risked overheating. The 5 to 15% of counts in which animals were seen to fly in conditions the model predicted they should not may be explained by erroneous assumptions underlying the model predictions. 相似文献
5.
F S Apple M A Rogers D C Casal L Lewis J L Ivy J W Lampe 《European journal of applied physiology and occupational physiology》1987,56(1):49-52
Total creatine kinase (CK) and CK MB activities were determined in gastrocnemius muscle and serum obtained from 14 female marathon runners. The level of CK MB in muscle increased significantly (p less than 0.05) after chronic exercise training from 5.3% to 10.5% of the total CK activity, but not after acute exercise (post-marathon 8.9%). No significant differences in total CK activities were detected. However, the total CK activity in the muscles were significantly (p less than 0.05) less than those previously reported from the muscle of men runners (1800 U/g, 3000 U/g respectively). No significant correlation existed between fiber type and muscle CK MB activity. Additionally, trace amounts of mitochondrial CK and CK BB were present in muscle homogenates. A significant correlation was observed in the increase in mean serum total CK (597 UL-1) and CK MB (23 UL-1) activities 24 h after the race (r = 0.97, p less than 0.05). These results suggest that gastrocnemius muscle in women adapts to training with increased CK MB activities and imply that skeletal muscle is the major source of elevated serum CK MB activities in women marathon runners. 相似文献
6.
J M Al-Hassan M Afzal M Ali M Thomson T Fatima S Fayad R S Criddle 《Comparative biochemistry and physiology. B, Comparative biochemistry》1986,85(1):41-47
Lipids associated with a threat induced epidermal gel secretion from the catfish, Arius thalassinus, have been analyzed. Phospholipids, neutral lipids and glycolipids are all present and each of these subclasses has been analyzed by thin layer and gas chromatography with a general similarity with membrane lipids being noted. The epidermal gel lipids differed from total liver lipids of the catfish. Fatty acid analysis showed the gel lipid to be rich in the unsaturated fatty acids: oleate (omega 7, C18:1), arachidonate (omega 6, C20:4), and docosahexaenoate (omega 3, C22:6). Some prostaglandins were quantitated in lipid extracts from the epidermal gel. 相似文献
7.
Effect of chronic ethanol and food deprivation on intestinal villus morphology and brush border membrane content of lipid and marker enzymes 总被引:3,自引:0,他引:3
M Keelan K Walker A B Thomson 《Canadian journal of physiology and pharmacology》1985,63(10):1312-1320
Brush border membranes (BBM) were isolated from the jejunum and ileum of control, ad libitum (CAL); control, food-restricted (CFR); control, weight gain (CWG); and ethanol-fed (EF) rabbits. Jejunal alkaline phosphatase activity was similar among control groups, but higher in CAL than EF animals. Sucrase activity was higher in EF and CWG animals than in CAL and CFR. The alkaline phosphatase/sucrase ratio was lower in EF than control animals. Ileal enzyme marker activity was similar among EF and control animals. Sucrase (S) activity was lower in the ileum than in the jejunum. Jejunal free fatty acid and phospholipid/cholesterol (PL/C) were lower in EF than control animals, whereas ileal lipid content was generally similar among all animal groups. Total phospholipid content was similar between sites, but the cholesterol and free fatty acid content were lower in the ileum than the jejunum. The phospholipid/cholesterol ratio was increased only in the ileum of EF animals. The amount of lecithin was decreased in the jejunal BBM of EF animals resulting in a decreased choline/amine phospholipid ratio as compared with control animals. The ileal phospholipid composition was similar among all groups. A large increase in villus height is observed in the jejunum of EF animals. Villus surface area and mucosal surface area are altered with ethanol feeding and food deprivation. Thus, (i) there is a gradient of S and cholesterol between the BBM of jejunum and ileum; (ii) changes in food intake are associated with changes in the morphology as well as the enzyme marker and lipid content of BBM.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Ivy Liu 《Biometrical journal. Biometrische Zeitschrift》2003,45(6):730-750
For an r × ctable with ordinal responses, odds ratios are commonly used to describe the relationship between the row and column variables. This article shows two types of ordinal odds ratios where local‐global odds ratios are used to compare several groups on a c‐category ordinal response and a global odds ratio is used to measure the global association between a pair of ordinal responses. When there is a stratification factor, we consider Mantel‐Haenszel (MH) type estimators of these odds ratios to summarize the association from several strata. Like the ordinary MH estimator of the common odds ratio for several 2 × 2 contingency tables, the estimators are used when the association is not expected to vary drastically among the strata. Also, the estimators are consistent under the ordinary asymptotic framework in which the number of strata is fixed and also under sparse asymptotics in which the number of strata grows with the sample size. Compared to the maximum likelihood estimators, simulations find that the MH type estimators perform better especially when each stratum has few observations. This article provides variances and covariances formulae for the local‐global odds ratios estimators and applies the bootstrap method to obtain a standard error for the global odds ratio estimator. At the end, we discuss possible ways of testing the homogeneity assumption. 相似文献