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排序方式: 共有498条查询结果,搜索用时 15 毫秒
1.
This article addresses the results of the recent North and Fairchild article on observer metamerism. It reports on the results of a different experiment that produced similar results to those of North and Fairchild. The history of observer metamerism is outlined briefly and some possible sources of the large variations in inter-observer matches are suggested. Finally, a plea for a commercially viable special index of metamerism for change in observer is formulated. © 1995 John Wiley & Sons, Inc. 相似文献
2.
For complex genetic diseases involving incomplete penetrance, genetic heterogeneity, and multiple disease genes, it is often difficult to determine the molecular variant(s) responsible for the disease pathogenesis. Linkage and association studies may help identify genetic regions and molecular variants suspected of being directly responsible for disease predisposition or protection, but, especially for complex diseases, they are less useful for determining when a predisposing molecular variant has been identified. In this paper, we expand upon the simple concept that if a genetic factor predisposing to disease has been fully identified, then a parent homozygous for this factor should transmit either of his/her copies at random to any affected children. Closely linked markers are used to determine identity by descent values in affected sib pairs from a parent homozygous for a putative disease predisposing factor. The expected deviation of haplotype sharing from 50%, when not all haplotypes carrying this factor are in fact equally predisposing, has been algebraically determined for a single locus general disease model. Equations to determine expected sharing for multiple disease alleles or multiple disease locus models have been formulated. The recessive case is in practice limiting and therefore can be used to estimate the maximum proportion of putative susceptibility haplotypes which are in fact predisposing to disease when the mode of inheritance of a disease is unknown. This method has been applied to 27 DR3/DR3 parents and 50 DR4/DR4 parents who have at least 2 children affected with insulin dependent diabetes mellitus (IDDM). The transmission of both DR3 and DR4 haplotypes is statistically different from 50% (P < 0.05 and P < 0.001, respectively). An upper estimate for the proportion of DR3 haplotypes associated with a high IDDM susceptibility is 49%, and for DR4 haplotypes 38%. Our results show that the joint presence of non-Asp at DQ beta position 57 and Arg at DQ alpha position 52, which has been proposed as a strong IDDM predisposing factor, is insufficient to explain the HLA component of IDDM predisposition. 相似文献
3.
Tellegen Auke; Lykken David T.; Bouchard Thomas J.; Wilcox Kimerly J.; Segal Nancy L.; Rich Stephen 《Canadian Metallurgical Quarterly》1988,54(6):1031
We administered the Multidimensional Personality Questionnaire (MPQ) to 217 monozygotic and 114 dizygotic reared-together adult twin pairs and 44 monozygotic reared-apart adult twin pairs. A four-parameter biometric model (incorporating genetic, additive versus nonadditive, shared family-environment, and unshared environment components) and five reduced models were fitted through maximum-likelihood techniques to data obtained with the 11 primary MPQ scales and its 3 higher order scales. Solely environmental models did not fit any of the scales. Although the other reduced models, including the simple additive model, did fit many of the scales, only the full model provided a satisfactory fit for all scales. Heritabilities estimated by the full model ranged from .39 to .58. Consistent with previous reports, but contrary to widely held beliefs, the overall contribution of a common family-environment component was small and negligible for all but 2 of the 14 personality measures. Evidence of significant nonadditive genetic effects, possibly emergenic (epistatic) in nature, was obtained for 3 of the measures. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Judge Timothy A.; Jackson Christine L.; Shaw John C.; Scott Brent A.; Rich Bruce L. 《Canadian Metallurgical Quarterly》2007,92(1):107
The present study estimated the unique contribution of self-efficacy to work-related performance controlling for personality (the Big 5 traits), intelligence or general mental ability, and job or task experience. Results, based on a meta-analysis of the relevant literatures, revealed that overall, across all studies and moderator conditions, the contribution of self-efficacy relative to purportedly more distal variables is relatively small. Within moderator categories, there were several cases in which self-efficacy made unique contributions to work-related performance. For example, self-efficacy predicted performance in jobs or tasks of low complexity but not those of medium or high complexity, and self-efficacy predicted performance for task but not job performance. Overall, results suggest that the predictive validity of self-efficacy is attenuated in the presence of individual differences, though this attenuation does depend on the context. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
6.
Apolipoprotein E (apo E) is a component of all the classes of lipoproteins and can be distributed among apo B- (LpB) and non apo B-containing lipoproteins (Lp-non-B). Using a new electroimmunoassay kit, plasma apo E, apo E in Lp-non-B (apo E-Lp-non-B) and apo E in LpB (apo E-LpB) levels were measured in healthy control subjects (n=481) from 3 centers participating in the ECTIM study (Etude Cas-Témoins sur l'Infarctus du Myocarde), a population-based study on myocardial infarction. The distribution of apo E among lipoproteins was analyzed according to the apo E phenotype after adjustment for center, body mass index, tobacco use, alcohol consumption and triglycerides. Apo E was higher (average excess: + 0.32; P < 0.0001) and lower (average excess: -0.12; P < 0.0001) in subjects carrying the allele epsilon2 and the allele epsilon4 respectively, than in apo E3/3 subjects. These differences are the consequence of variations in apo E-Lp-non-B which clearly differed between the groups classified according to their apo E phenotype (P < 0.0001). The average excess of apo E Lp non-B compared to apo E3/3 subjects was + 0.43 (P < 0.0001) and -0.22 (P < 0.0001) for the epsilon2 and epsilon4 alleles respectively. Apo E-LpB was lower in subjects carrying the epsilon2 allele (P < 0.02) while the presence of the epsilon4 allele did not modify this parameter. The proportion of apo E within HDL was clearly higher and lower in subjects carrying apo E2 and apo E4 respectively than in apo E3/3 subjects. Although triglyceride levels were dependent on the apo E phenotype, the adjustment of the proportion of apo E in HDL for triglycerides hardly modified the results. For the first time, these results, using direct measurements on a large number of subjects, confirm the greater preference of apo E4 over apo E2 for LpB and vice versa for Lp-non-B. They also show a greater affinity of apo E2 for HDL compared to apo E3. This high affinity of apo E2 for HDL could be due to the formation of the apo E-A-II complex. These results indicate that apo E phenotype modulates the distribution of apo E among lipoproteins and suggest differences in lipoprotein metabolism between apo E2, apo E3 and apo E4. 相似文献
7.
8.
S Brown JN Rumbley AJ Moody JW Thomas RB Gennis PR Rich 《Canadian Metallurgical Quarterly》1994,1183(3):521-532
The carbon monoxide compounds of the fully reduced and mixed valence forms of cytochrome bo from Escherichia coli were laser photolysed under anaerobic conditions at room temperature. The carbon monoxide recombined with characteristic rate constants of 50 s-1 or 35 s-1 in the fully reduced and mixed valence forms, respectively. Rates of CO recombination with the fully reduced enzyme were examined in a variety of mutant forms of cytochrome bo, produced by site-directed mutagenesis. A method was developed to deconvolute cytochromes bo and bd, leading to some reassessment of histidine ligands to the metals. Significant changes in the rate constant of recombination of carbon monoxide occurred in many of these mutants and these results could be rationalised generally in terms of our current working model of the folding structure of subunit I. In the mixed valence form of the enzyme the transient photolysis spectra in the visible region are consistent with a rapid electron redistribution from the binuclear centre to the low-spin haem. This electron transfer is biphasic, with rate constants of around 10(5) and 8000 s-1. The process was also examined in the His-333-Leu mutant, in which a putative histidine ligand to CuB is replaced by leucine, and which results in the loss of the CuB. It appeared that rapid haem-haem electron transfer could still occur. The observation that CuB is apparently not required for rapid haem-haem electron transfer is consistent with the recently proposed model in which the two haems are positioned on opposite sides of transmembrane helix X in subunit I of the oxidase. 相似文献
9.
EL Alderman JH Levy JB Rich M Nili B Vidne H Schaff G Uretzky G Pettersson JJ Thiis CB Hantler B Chaitman A Nadel 《Canadian Metallurgical Quarterly》1998,116(5):716-730
OBJECTIVE: We examined the effects of aprotinin on graft patency, prevalence of myocardial infarction, and blood loss in patients undergoing primary coronary surgery with cardiopulmonary bypass. METHODS: Patients from 13 international sites were randomized to receive intraoperative aprotinin (n = 436) or placebo (n = 434). Graft angiography was obtained a mean of 10.8 days after the operation. Electrocardiograms, cardiac enzymes, and blood loss and replacement were evaluated. RESULTS: In 796 assessable patients, aprotinin reduced thoracic drainage volume by 43% (P < .0001) and requirement for red blood cell administration by 49% (P < .0001). Among 703 patients with assessable saphenous vein grafts, occlusions occurred in 15.4% of aprotinin-treated patients and 10.9% of patients receiving placebo (P = .03). After we had adjusted for risk factors associated with vein graft occlusion, the aprotinin versus placebo risk ratio decreased from 1.7 to 1.05 (90% confidence interval, 0.6 to 1.8). These factors included female gender, lack of prior aspirin therapy, small and poor distal vessel quality, and possibly use of aprotinin-treated blood as excised vein perfusate. At United States sites, patients had characteristics more favorable for graft patency, and occlusions occurred in 9.4% of the aprotinin group and 9.5% of the placebo group (P = .72). At Danish and Israeli sites, where patients had more adverse characteristics, occlusions occurred in 23.0% of aprotinin- and 12.4% of placebo-treated patients (P = .01). Aprotinin did not affect the occurrence of myocardial infarction (aprotinin: 2.9%; placebo: 3.8%) or mortality (aprotinin: 1.4%; placebo: 1.6%). CONCLUSIONS: In this study, the probability of early vein graft occlusion was increased by aprotinin, but this outcome was promoted by multiple risk factors for graft occlusion. 相似文献
10.
A number of targeted cytotoxic agents have been developed that selectively kill malignant or otherwise pathological cells. These engineered proteins consist of a potent cytotoxic element connected to a ligand domain that binds to specific molecules on the surface of the target cell. Several of these agents have shown promise in clinical trials and one is currently administered to patients. A significant technical obstacle that has impeded the development of some of these toxins is the difficulty of preparing certain recombinant proteins in properly folded forms. These fusion proteins have generally been produced in bacteria requiring them to be denatured and renatured in vitro. For some proteins this is an efficient process whereas for others it is not. We describe here a system to produce fusion toxins rapidly and efficiently by engineering mammalian cells to secrete them as properly folded molecules which can be purified in native form from cell culture medium. We have used this system to produce highly active preparations of DAB(389)-IL7, a molecule consisting of the catalytic and transmembrane domains of diphtheria toxin fused to interleukin 7. This system is generalizable and can be used to produce and evaluate rapidly fusion toxins incorporating novel or uncharacterized ligands. 相似文献