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151.
T Lin J Blaisdell K W Barbour E A Thompson 《Biochemical and biophysical research communications》1988,157(1):121-126
This study evaluated the effects of in vivo administration of human chorionic gonadotropin (hCG) on c-myc oncogene expression in Leydig cells. Sprague-Dawley rats (46-50 days old) were treated with hCG (10 units, i.p.), and purified Leydig cells were isolated 1-24 h later. HCG caused a transient elevation of c-myc mRNA in 4 h and returned to normal or lower than normal levels at 24 h. There was no change in c-fos or beta-actin mRNA levels. Our results suggest that the growth promoting effects of hCG on Leydig cells may be mediated by the transient expression of c-myc protooncogene. 相似文献
152.
Melanie A. Marty Robert J. Blaisdell Rachel Broadwin Martin Hill Dorothy Shimer Margaret Jenkins 《人类与生态风险评估》2002,8(7):1723-1737
Data were combined from a study measuring breathing rates at various activities and two activity pattern studies to generate breathing rate distributions for children and adults. The children and adult breathing rate distributions were combined using a Monte Carlo technique to generate a breathing rate distribution for a lifetime spanning ages 0 to 70. The children's breathing rate distribution has a mean, standard deviation, median and 95th percentile of 452, 67.7, 441, and 581 L/kg-day, respectively. The adult breathing rate distribution has a mean, standard deviation, median and 95th percentile of 232, 64.6, 209, and 381 L/kg-day, respectively. The simulated 70-year distribution has a mean, standard deviation, median and 95th percentile of 271, 57.9, 253, and 393 L/kg-day, respectively. The adult breathing rate distribution is based on 24-hour recall activity data that would not necessarily capture average activity patterns and therefore breathing rates. We utilized the human energy expenditure literature to validate the breathing rate distribution. We conclude that the breathing rate distribution is reasonable for chronic long-term risk assessment in California's Air Toxics Hot Spots program. 相似文献
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Youcef Bouchekioua Aaron P. Blaisdell Yutaka Kosaki Iku Tsutsui-Kimura Paul Craddock Masaru Mimura Shigeru Watanabe 《Biological reviews of the Cambridge Philosophical Society》2021,96(1):52-65
The cognitive map has been taken as the standard model for how agents infer the most efficient route to a goal location. Alternatively, path integration – maintaining a homing vector during navigation – constitutes a primitive and presumably less-flexible strategy than cognitive mapping because path integration relies primarily on vestibular stimuli and pace counting. The historical debate as to whether complex spatial navigation is ruled by associative learning or cognitive map mechanisms has been challenged by experimental difficulties in successfully neutralizing path integration. To our knowledge, there are only three studies that have succeeded in resolving this issue, all showing clear evidence of novel route taking, a behaviour outside the scope of traditional associative learning accounts. Nevertheless, there is no mechanistic explanation as to how animals perform novel route taking. We propose here a new model of spatial learning that combines path integration with higher-order associative learning, and demonstrate how it can account for novel route taking without a cognitive map, thus resolving this long-standing debate. We show how our higher-order path integration (HOPI) model can explain spatial inferences, such as novel detours and shortcuts. Our analysis suggests that a phylogenetically ancient, vector-based navigational strategy utilizing associative processes is powerful enough to support complex spatial inferences. 相似文献
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In the multiple-dose bleomycin-hamster model of pulmonary fibrosis, combined treatment with taurine and niacin blocks the increase in lung collagen deposition. We investigated the effects of taurine and niacin on lung lysyl oxidase and type I collagenase activities in this model. Hamsters were intratracheally instilled with three weekly doses of saline or bleomycin sulfate. Animals were fed either a diet containing 2.5% niacin and 2.5% taurine, or a control diet throughout the experiment. The four groups were saline-instilled with the control diet (SCD), bleomycin-instilled with control diet (BCD), bleomycin-instilled with the diet containing taurine and niacin (BTN), and saline-instilled with the diet containing taurine and niacin (STN). Animals were sacrificed at 1, 4, and 8 weeks after the last bleomycin instillation. Hydroxyproline per lung in the BCD group was significantly elevated by 38, 56, and 60% over the SCD group at 1, 4, and 8 weeks, respectively. Lysyl oxidase activity per lung in the BCD group was significantly elevated by 57.5 and 91.4% over the SCD controls at 1 and 4 week time periods, respectively. Type I collagenase activity per lung in the BCD group was significantly elevated by 65 and 80% over the SCD controls at 1 and 4 weeks, respectively. The combined treatment with taurine and niacin abolished the bleomycin-induced increases in the lung hydroxyproline content and lysyl oxidase and collagenase activities. It was postulated that one of the mechanisms for the antifibrotic effect of taurine and niacin may be the blockage of bleomycin-induced increases in the lung lysyl oxidase and collagenase activities. © 1995 John Wiley & Sons, Inc. 相似文献