| 21. |
- Karpman, Diana, et al.
(author)
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Antibodies to intimin and Escherichia coli secreted proteins A and B in patients with enterohemorrhagic Escherichia coli infections
- 2002
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In: Pediatric Nephrology. - : Springer Science and Business Media LLC. - 1432-198X .- 0931-041X. ; 17:3, s. 201-211
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Journal article (peer-reviewed)abstract
- Enterohemorrhagic Escherichia coli produce an attaching and effacing lesion upon adhering to the intestinal epithelium. Bacterial factors involved in this histopathology include the intimin adhesin and E. coli secreted proteins (Esps) A and B. In this study we investigated the serum antibody responses to recombinant E. coli O157:H7 intimin, EspA, and EspB by immuno-blotting. Canadian patients with O157:H7 infection (n=10), Swedish patients with 0157:H7 (n=21), non-O157 (n=18), or infection from which the serotype was not available (n=3), and asymptomatic household members (n=25) were studied and compared with Canadian (n=20) and Swedish controls (n=52). In Canadian patients, IgG antibodies to intimin, EspA, and EspB were analyzed, in Swedish patients and their household members I-A, IgG, and IgM antibodies to EspA and EspB were studied. Patients and household members mounted an antibody response to the antigens. Significantly more patients developed an acute response to EspB compared with controls (P<0.01 Canadian patients, P<0.0001 Swedish patients). EspB IgA, IgG, and IgM had a specificity of 100%, 86%, and 86%, positive predictive value of 100%, 83%, and 81%, and sensitivity of 57%, 69%, and 63%, respectively, and appear to be an appropriate assay for the detection of EHEC infection. In cases of hemolytic uremic syndrome or hemorrhagic colitis this assay may be useful when a fecal strain has not been isolated, or in epidemics of non-O157 infection.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Sigfrid, Louise A., et al.
(author)
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Antioxidant enzyme activity and mRNA expression in islets of Langerhans from the BB/S rat model of type 1 diabetes and an insulin-producing cell line
- 2004
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In: Journal of Molecular Medicine. - : Springer. - 0946-2716 .- 1432-1440. ; 82:5, s. 325-335
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Journal article (peer-reviewed)abstract
- It has been proposed that low activities of antioxidant enzymes in pancreatic beta cells may increase their susceptibility to autoimmune attack. We have therefore used the spontaneously diabetic BB/S rat model of type 1 diabetes to compare islet catalase and superoxide dismutase activities in diabetes-prone and diabetes-resistant animals. In parallel studies, we employed the RINm5F beta cell line as a model system (previously validated) to investigate whether regulation of antioxidant enzyme activity by inflammatory mediators (cytokines, nitric oxide) occurs at the gene or protein expression level. Diabetes-prone rat islets had high insulin content at the age used (58–65 days) but showed increased amounts of DNA damage when subjected to cytokine or hydrogen peroxide treatments. There was clear evidence of oxidative damage in freshly isolated rat islets from diabetes-prone animals and significantly lower catalase and superoxide dismutase activities than in islets from age-matched diabetes-resistant BB/S and control Wistar rats. The mRNA expression of antioxidant enzymes in islets from diabetes-prone and diabetes-resistant BB/S rats and in RINm5F cells, treated with a combination of cytokines or a nitric oxide donor, DETA-NO, was analysed semi-quantitatively by real time PCR. The mRNA expression of catalase was lower, whereas MnSOD expression was higher, in diabetes-prone compared to diabetes-resistant BB/S rat islets, suggesting regulation at the level of gene expression as well as of the activities of these enzymes in diabetes. The protein expression of catalase, CuZnSOD and MnSOD was assessed by Western blotting and found to be unchanged in DETA-NO treated cells. Protein expression of MnSOD was increased by cytokines in RINm5F cells whereas the expression of CuZnSOD was slightly decreased and the level of catalase protein was unchanged. We conclude that there are some changes, mostly upregulation, in protein expression but no decreases in the mRNA expression of catalase, CuZnSOD or MnSOD enzymes in beta cells treated with either cytokines or DETA-NO. The lower antioxidant enzyme activities observed in islets from diabetes-prone BB/S rats could be a factor in the development of disease and in susceptibility to DNA damage in vitro and could reflect islet alterations prior to immune attack or inherent differences in the islets of diabetes-prone animals, but are not likely to result from cytokine or nitric oxide exposure in vivo at that stage.
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| 26. |
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| 27. |
- Vrede, Tobias, et al.
(author)
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FUNDAMENTAL CONNECTIONS AMONG ORGANISM C:N:P STOICHIOMETRY, MACROMOLECULAR COMPOSITION, AND GROWTH
- 2004
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In: Ecology. ; 85:5, s. 1217–1229-
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Journal article (peer-reviewed)abstract
- Whereas it is acknowledged that the C:N:P stoichiometry of consumers and their resources affects both the structure and the function of food webs, and eventually influences broad-scale processes such as global carbon cycles, the mechanistic basis for the variation in stoichiometry has not yet been fully explored. Empirical evidence shows that the specific growth rate is positively related to RNA concentration both between and within taxa in both unicellular and multicellular organisms. Since RNA is rich in P and constitutes a substantial part of the total P in organisms, a high growth rate is also connected with a high P content. We argue that the reason for this pattern is that the growth of all biota is closely linked with their protein synthesis rate, and thus with the concentration of ribosomal RNA. Dynamic energy budget theory supports the positive relationship between RNA and specific growth rate in microorganisms, whereas the predictions concerning multicellulars only partially agrees with the observed pattern. In a simple model of consumer growth, we explore the consequences of various allocation patterns of RNA, protein, carbohydrates/lipids, and other biochemical constituents on organism potential growth rate and C:N:P stoichiometry. According to the model the percentage of N and especially percentage of P per dry mass increases with increasing specific growth rate. Furthermore, the model suggests that macromolecule allocation patterns and thus N:P stoichiometry are allowed to differ substantially at low growth rates whereas the stoichiometry at high growth rates is much more constricted at low N:P. The model fits empirical data reasonably well, but it is also acknowledged that complex life cycles and associated physiological constraints may result in other patterns. We also use a similar approach of modeling organism growth from basic biochemical principles to illustrate fundamental connections among biochemical allocation and C:N stoichiometry in autotroph production, which is based on allocation patterns between carbohydrates and rubisco. Similar to the RNA–protein model, macromolecular composition and C:N ratios are more constrained at high than at low growth rates. The models and the empirical data together suggest that organism growth is tightly linked with the organisms' biochemical and elemental composition. The stoichiometry of growth impinges on nutrient cycles and carbon fluxes at the ecosystem level. Thus, focus on the biological basis of organism C:N:P stoichiometry can mechanistically connect growth strategy and biochemical and cellular mechanisms of biota to major ecological consequences.
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