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81.
CJ Quaife EJ Kelly BA Masters RL Brinster RD Palmiter 《Canadian Metallurgical Quarterly》1998,148(1):148-157
Mice express four distinct metallothioneins (MTs) that have similar metal-binding properties. MT-I and MT-II are expressed coordinately in most organs, whereas MT-III is expressed predominantly in a subset of neurons and MT-IV is expressed in certain stratified epithelia. The restricted expression of MT-III suggests that it may severe a specialized function. To test this hypothesis, transgenic mice were generated that express MT-III in the wider expression domain of MT-I. Similar transgenic lines expressing extra MT-I under the same regulation were generated as controls for the effect of over-expression of MT. Transgenic mice that express MT-III ectopically frequently die at 2-3 months of age. The pancreata of moribund mice were abnormally small and histological examination, at various ages, revealed a progressive degeneration of the acinar cells. At early stages multifocal acinar cell eosinophilia and swollen nuclei were seen and this pathology progressed to multifocal acinar cell necrosis and fibrosis. The terminal stages were characterized by a loss of the acinar compartment, leaving the islets embedded in a fibrotic remnant. Other organs of these mice were grossly and histologically normal. All organs examined from mice expressing excess MT-I were unremarkable even though expression of either MT-I or MT-III transgenes resulted in similar accumulations of zinc and copper in the pancreata. This study indicates that pancreatic acinar cells are unusually sensitive to chronic expression of MT-III. The mechanism by which MT-III disrupts pancreatic function is unclear, but the results provide further evidence that MT isoforms exhibit distinct properties and probably serve distinct biological functions. 相似文献
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83.
DM Murray PJ Hannan RD Wolfinger WL Baker JH Dwyer 《Canadian Metallurgical Quarterly》1998,17(14):1581-1600
This study used Monte Carlo simulations to evaluate the performance of alternative models for the analysis of group-randomized trials having more than two time intervals for data collection. The major distinction among the models tested was the sampling variance of the intervention effect. In the mixed-model ANOVA, the sampling variance of the intervention effect is based on the variance among group x time-interval means. In the random coefficients model, the sampling variance of the intervention effect is based on the variance among the group-specific slopes. These models are equivalent when the design includes only two time intervals, but not when there are more than two time intervals. The results indicate that the mixed-model ANOVA yields unbiased estimates of sampling variation and nominal type I error rates when the group-specific time trends are homogenous. However, when the group-specific time trends are heterogeneous, the mixed-model ANOVA yields downwardly biased estimates of sampling variance and inflated type I error rates. In contrast, the random coefficients model yields unbiased estimates of sampling variance and the nominal type I error rate regardless of the pattern among the groups. We discuss implications for the analysis of group-randomized trials with more than two time intervals. 相似文献
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RD Smith L Hunyady JA Olivares-Reyes B Mihalik S Jayadev KJ Catt 《Canadian Metallurgical Quarterly》1998,54(6):935-941
Autosomal recessive juvenile parkinsonism (AR-JP) is a distinct clinical and genetic entity characterized by selective degeneration of nigral dopaminergic neurons and young-onset parkinsonism with remarkable response to levodopa. Recently, we mapped the gene locus for AR-JP to chromosome 6q25.2-q27 by linkage analysis and we identified a novel large gene, Parkin, consisting of 12 exons from this region; mutations of this gene were found to be the cause of AR-JP in two families. Now we report results of extensive molecular analysis on 34 affected individuals from 18 unrelated families with AR-JP. We found four different homozygous intragenic deletional mutations, involving exons 3 to 4, exon 3, exon 4, and exon 5 in 10 families (17 affected individuals). In addition to the exonic deletions, we identified a novel one-base deletion involving exon 5 in two families (2 affected individuals). All mutations so far found were deletional types in which large exonic deletion accounted for 50% (17 of 34) and the one-base deletion accounted for 6% (2/34); in the remaining, no homozygous mutations were found in the coding regions. Our findings indicate that loss of function of the Parkin protein results in the clinical phenotype of AR-JP and that subregions between introns 2 and 5 of the Parkin gene are mutational hot spots. 相似文献
87.
A random telephone survey was used to interview 598 employees about instances, if any, when they had been physically attacked or threatened in the workplace. Demographic and workplace characteristics are analyzed as correlates of these forms of violence. The only characteristic consistently associated with higher risk is a work schedule that included nighttime hours. However, although few strong or consistent correlates of workplace violence were found, there were clear negative consequences associated with being victimized at work: lower job satisfaction, greater job stress, increased considerations of job change, and an increased likelihood of bringing mace, a gun, or another weapon to work. 相似文献
88.
RD Howard RS Martens SA Innis JM Drnevich J Hale 《Canadian Metallurgical Quarterly》1998,55(5):1151-1163
A sexual size dimorphism usually occurs when size-dependent reproductive advantages exist in only one sex. Studies on Japanese medaka, Oryzias latipes, have demonstrated reproductive size advantages in females but not in males, even though males and females are similar in body size. We conducted mate-choice and mate-copying tests in which a female could first associate with, then mate with, either a large (>/=1 sd+X standard length) or a small male (=1 sd-X standard length). Large males obtained a mating advantage in both tests, and both mate choice and mate competition influenced their mating success. In the majority of trials, females associated with large males. Association preferences of females corresponded to their mating preferences when mate competition between males was weak; however, when mate competition was strong, large males obtained almost every mating regardless of female association preference. Preference for large males may provide females with a reproductive advantage if males mate multiply because small males become sperm-depleted sooner than large males. We found no indication that females copied the mating decisions of other females. Repeatability of female mating preference was low, not because females mated at random with respect to male size, but because most females consistently preferred large males. We also conducted mating tests at four density levels and found that large males maintained their mating advantage relative to small males at all densities. Thus, male and female medaka may be similar in body size because large size provides a fecundity advantage for females, as demonstrated in previous studies, and large size provides a mating advantage for males, as demonstrated in our study. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour. 相似文献
89.
CR Divgi AM Scott K McDermott PS Fallone S Hilton K Siler N Carmichael F Daghighian RD Finn AM Cohen 《Canadian Metallurgical Quarterly》1994,21(1):9-15
Ten patients with colorectal cancer metastases received 125I-B72.3 and 131I-CC49 prior to laparotomy (five patients received 1 mg, and five 20 mg of each mAb). Tumor:serum ratios of 131I-CC49 were better than those of 125I-B72.3 (P < 0.01 at 1 mg; P = 0.05 at 20 mg; P < 0.01 at both doses). All known lesions > or = 1 cm in diameter were visualized at the 20 mg dose. There was no difference in absolute tumor uptake of 125I-B72.3 or 131I-CC49. We conclude that mAb CC49 has better relative uptake in colorectal cancers than mAb B72.3. 相似文献
90.