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61.
Natural selection and the molecular clock 总被引:13,自引:1,他引:12
62.
J Reed W E Hull C W von der Lieth D Kübler S Suhai V Kinzel 《European journal of biochemistry》1988,178(1):141-154
The primary sequence Arg-Gly-Asp has been found in a number of proteins which bind to cell surface receptors. Studies with synthetic peptides have shown that the presence of charged side chains alone is not sufficient to confer binding activity. Application of folding algorithms to proteins and peptides having similar sequences indicates that binding activity is strongly correlated with the presence of two or more closely spaced residues that each have a high probability of initiating a beta-bend. Circular dichroic studies on the hexapeptide GRGDSP, whose sequence is contained in fibronectin and which also shows binding activity, demonstrate that it adopts an unusual conformation in aqueous solution. 1H-NMR spectra of the peptide in aqueous solution show that the two amide hydrogens of Asp4 and Ser5 exchange very slowly. Computer-assisted modeling using restrained molecular dynamics and energy minimization results in conformations that include two beta-bends of type III-III or III-I (hydrogen bonds 4----1 and 5----2), fully consistent with constraints imposed by 1H- and 13C-NMR data. It is suggested that this unusual secondary structure provides an additional specificity determinant. 相似文献
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Daniel B Werz René Ranzinger Stephan Herget Alexander Adibekian Claus-Wilhelm von der Lieth Peter H Seeberger 《ACS chemical biology》2007,2(10):685-691
The diversity of three major classes of mammalian carbohydrates, mainly glycolipids and O- and N-linked glycans, deposited in the databank GLYCOSCIENCES.de was subjected to statistical analyses. Size, chain length, and branching complexity were accessed and revealed that the average oligosaccharide is composed of about eight monosaccharide units. About a quarter of all oligosaccharides are strictly linear, and the remainder are branched at least once. Glucosamine, galactose, and mannose are dominating and comprise ~75% of the monosaccharides within mammalian oligosaccharide frameworks. alpha-Linked sialic acid, alpha-linked fucose, and beta-linked galactose decorate the majority of reducing termini. Glucose as the most abundant carbohydrate in mammals plays only a very minor role within these structures. Particular emphasis was placed on analyzing the way the monosaccharide units are linked within the oligomeric framework. Just 11 monosaccharide connections account for >75% of all linkages. Thus, the number of structural combinations found in nature, the part of the occupied mammalian glycospace, is much smaller than expected. As a result, a potential set of building blocks for oligosaccharide assembly is presented. This potential building block set was correlated with the accessible 3299 mammalian carbohydrate structures in the GLYCOSCIENCES.de databank. Only 36 building blocks are required to construct 75% of the 3299 mammalian oligosaccharides. 相似文献
65.
Christie M Bartels Jessica M Saucier Carolyn T Thorpe Amy JH Kind Nancy Pandhi Karen E Hansen Maureen A Smith 《Arthritis research & therapy》2012,14(4):R166
Introduction
Diabetes mellitus is a key predictor of mortality in rheumatoid arthritis (RA) patients. Both RA and diabetes increase the risk of cardiovascular disease (CVD), yet understanding of how comorbid RA impacts the receipt of guideline-based diabetes care is limited. The purpose of this study was to examine how the presence of RA affected hemoglobin A1C (A1c) and lipid measurement in older adults with diabetes.Methods
Using a retrospective cohort approach, we identified beneficiaries ≥65 years old with diabetes from a 5% random national sample of 2004 to 2005 Medicare patients (N = 256,331), then examined whether these patients had comorbid RA and whether they received guideline recommended A1c and lipid testing in 2006. Multivariate logistic regression was used to examine the effect of RA on receiving guideline recommended testing, adjusting for baseline sociodemographics, comorbidities and health care utilization.Results
Two percent of diabetes patients had comorbid RA (N = 5,572). Diabetes patients with comorbid RA were more likely than those without RA to have baseline cardiovascular disease (such as 17% more congestive heart failure), diabetes-related complications including kidney disease (19% higher), lower extremity ulcers (77% higher) and peripheral vascular disease (32% higher). In adjusted models, diabetes patients with RA were less likely to receive recommended A1c testing (odds ratio (OR) 0.84, CI 0.80 to 0.89) than those without RA, but were slightly more likely to receive lipid testing (OR 1.08, CI 1.01 to 1.16).Conclusions
In older adults with diabetes, the presence of comorbid RA predicted lower rates of A1c testing but slightly improved lipid testing. Future research should examine strategies to improve A1c testing in patients with diabetes and RA, in light of increased CVD and microvascular risks in patients with both conditions. 相似文献66.
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Fungi were isolated monthly from collections of first year needles, second year needles, and both surface sterilized and non-sterilized abscised brown needles in the canopy and one-year-old litter on the forest floor. The vertical and phenological distribution of the 8 commonest fungi are reported. After the second growing season in the litterMortierella isabellina, Trichoderma spp., andPenicillium spp. overgrow these fungi on the primary isolation plates using the procedure adopted in this phase of the needle study.Presented at the Eighth International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel 相似文献
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