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101.
A quality control algorithm for DNA sequencing projects.   总被引:2,自引:0,他引:2       下载免费PDF全文
Heterologous DNA sequences from rearrangements with the genomes of host cells, genomic fragments from hybrid cells, or impure tissue sources can threaten the purity of libraries that are derived from RNA or DNA. Hybridization methods can only detect contaminants from known or suspected heterologous sources, and whole library screening is technically very difficult. Detection of contaminating heterologous clones by sequence alignment is only possible when related sequences are present in a known database. We have developed a statistical test to identify heterologous sequences that is based on the differences in hexamer composition of DNA from different organisms. This test does not require that sequences similar to potential heterologous contaminants are present in the database, and can in principle detect contamination by previously unknown organisms. We have applied this test to the major public expressed sequence tag (EST) data sets to evaluate its utility as a quality control measure and a peer evaluation tool. There is detectable heterogeneity in most human and C.elegans EST data sets but it is not apparently associated with cross-species contamination. However, there is direct evidence for both yeast and bacterial sequence contamination in some public database sequences annotated as human. Results obtained with the hexamer test have been confirmed with similarity searches using sequences from the relevant data sets.  相似文献   
102.
Ninety four patients with mild hypertension (average supine diastolic blood pressure (phase V) 95-110 mm Hg) were allocated at random to receive restriction of dietary sodium (maximum allowed 70 mmol(mEq)/24 h) or a normal diet. In addition, they received in random order 25 mg chlorthalidone, 200 mg metoprolol (slow release), and a fixed combination of these two drugs. Each drug treatment was given for four weeks and alternated with four weeks of placebo. Forty four patients were allocated to sodium restriction (group 1) and 50 to normal diet (group 2). The mean 24 hour urinary sodium excretion in group 1 was 74 (SD 31) mmol(mEq)/24 h, and in group 2 132 (51) mmol/24 h. Compared with the screening blood pressure the average decrement of the supine blood pressure in group 1 was 16.0/8.6 mm Hg with placebo, 21.7/11.5 mm Hg with the diuretic, 28.5/17.8 mm Hg with the beta blocker, and 28.9/18.4 mm Hg with the combined agent; in group 2 these values were 13.3/6.1, 20.3/9.7, 21.3/12.9, and 29.4/16.8 mm Hg, respectively. There was a sharp decrease of the average potassium concentration during chlorthalidone and combination treatment periods (average value 3.3 mmol(mEq)/1). These results suggest that moderate salt restriction used as sole treatment has a limited though demonstrable blood pressure lowering effect but that when it is used as an adjuvant to beta blocker treatment its value is greatly enhanced.  相似文献   
103.
Summary In several animal species, galanin occurs in pancreatic nerves and inhibits insulin secretion. However, the presence and action of galanin in the human pancreas have not been established. Therefore, we examined the presence and nature of human pancreatic galanin-like immunoreactive material (GLIR) and the effects of galanin on glucose-stimulated insulin secretion from isolated human islets. Immunofluorescent staining of human pancreas revealed GLIR in fine varicose fibers in both islets and exocrine parenchyma. Furthermore, acid extracts of pancreas (n=3) and isolated islets (n=3) contained 0.17±0.06 and 0.23±0.11 pmol GLIR/mg protein. Human pancreatic GLIR coeluted with synthetic porcine galanin from Sephadex G-50. Moreover, synthetic porcine galanin inhibited glucose-stimulated insulin secretion from collagenase-isolated human islets at dose rates >10-8 M. Thus, (1) human pancreas is innervated by galanin-containing nerves, (2) human pancreatic GLIR is of similar size as synthetic porcine galanin, and (3) porcine galanin inhibits glucose-stimulated insulin secretion from human islets. Therefore, galanin could be an important local regulator of insulin secretion in man.  相似文献   
104.
A hit to lead process to identify reversible, orally available ADP receptor (P2Y12) antagonists lead compounds is described. High throughput screening afforded 1. Optimization of 1, using parallel synthesis methods, a methyl scan to identify promising regions for optimization, and exploratory SAR on these regions, provided 22 and 23. Compound 23 is an orally available, competitive reversible antagonist (KB?=?94?nM for inhibition of ADP-induced platelet aggregation). It exhibits high metabolic stability in human, rat and dog liver microsomes and is orally absorbed. Although plasma level after oral dosing of 22 and 23 to rats is low, reasonable levels were achieved to merit extensive lead optimization of this structural class.  相似文献   
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Errors in the polymerase chain reaction.   总被引:20,自引:3,他引:17  
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107.
Pest damage to sugar beet, including that by birds, has been recorded since 1957. During that time damage by rooks has decreased almost to nil, but some other bird damage has greatly increased, most probably as a result of changing agronomic practices, especially the extensive use of herbicides, the introduction of monogerm seed, and the increasing practice of ‘planting-to-a-stand’. The most severe bird damage in the spring is grazing by several species, and in early summer localized felling of plants by pheasants. Observations in the mid–1960's of causes of seedling and plant losses suggested that birds were then of minor importance; the British Sugar Corporation currently consider that birds are the most serious pest of sugar beet. The distribution of the reported damage does not seem to follow any national pattern. In small-plot field trials possible repellent materials such as anthraquinone, methiocarb or thiram, applied to seed or foliage, did not decrease the extent of grazing.  相似文献   
108.
Uterine samples and flushings were obtained from 87 mares to compare endometrial bacteriology and biopsy with immunoglobulin and protein concentration and alkaline phosphatase activity in uterine flushings. Mares were designated as infected if both bacteriology and biopsies were positive. The immunoglobulin levels, protein concentration and alkaline phosphatase activity in uterine flushings from infected and non-infected mares were compared. Twenty (23%) of the mares were classified as infected. A significantly higher proportion of infected mares (cf. non-infected) had elevated IgA and protein concentrations. Levels of IgG, IgGT or alkaline phosphatase were not significantly elevated in infected mares. These results suggest that IgA and protein levels are elevated in the uterus in the presence of active infection.  相似文献   
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