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21.
The R1.1 mouse thymoma cell line expresses a single class of kappa opioid receptors that is negatively coupled to adenylyl cyclase through a Bordetella pertussis toxin-sensitive inhibitory guanine nucleotide-binding protein. The aim of the present study was to determine whether chronic opioid treatment of R1.1 cells altered either the binding properties or the functional response associated with the kappa opioid receptor. Culturing of R1.1 cells with the kappa-selective agonist (trans)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl] benzeneacetamide methane-sulfonate hydrate (U50,488) for 3 hr and longer, followed by extensive washing of R1.1 cell membranes, produced a concentration- and time-dependent reduction in the binding of the kappa-selective ligand (5 alpha,7 alpha,8 beta)-(-)-N-methyl-N-(7-(1-pyrrolidinyl)-1- oxaspiro(4,5)dec-8-yl) benzeneacetamide ([3H]U69,593). Culturing of R1.1 cells with 100 nM U50,488 for 24 hr produced approximately a 50% reduction in the Bmax value for [3H]U69,593 and [3H]naloxone binding. In contrast to the reduction in binding, there was no change in the inhibition of adenylyl cyclase activity by (-)-U50,488. To determine whether kappa opioid receptor function was maintained by spare receptors after agonist-induced down-regulation, membranes from untreated R1.1 cells were incubated with 400 nM of the irreversible opioid antagonist beta-chlornaltrexamine (beta-CNA) followed by extensive washing. beta-CNA produced a 50% reduction in the [3H]U69,593 binding and a 6-fold increase in the IC50 value for (-)-U50,488 inhibition of adenylyl cyclase activity, with no change in the maximal inhibition of cyclic AMP levels.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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The injection of a strong organic base into milligram quantities of fats and oils dissolved in methylene chloride results
in a burst of chemiluminescence whose peak intensity is a function of the previous thermal oxidation history and of the degree
of unsaturation of the starting material. The flash of this induced chemiluminescence can be 108 times higher than the steady-state “spontaneous” chemiluminescence. The kinetics of the induced chemiluminescence are first
order in concentration and second order in time. The emission spectrum is broad and extends into the near infrared. A model
based on dioxetane chemiluminescence is proposed to explain the observed kinetics. 相似文献
26.
Smaller cities seeking new economic development vehicles have embraced the growth of minor league sports. In an attempt to eliminate the threat of competition and maintain a sense of stability, four local governments purchased their respective minor league baseball franchise. This action may serve as a model for local governments that have invested heavily in professional sports as an economic development strategy. This study investigates the benefits of ownership in terms of stability for development, economic gain, and increased civic spirit. The study finds that publicly owned teams can be successfully used to anchor comprehensive plans for economic development, and that public ownership provides a way to pay the costs of the sports facilities and the debt service. There is little evidence to show that publicly owned teams increase civic spirit. However, this model presents some challenges that may prevent its widespread utilization. 相似文献
27.
Does the medium matter? The interaction of task type and technology on group performance and member reactions. 总被引:2,自引:0,他引:2
Investigated the hypothesis that as group tasks pose greater requirements for member interdependence, communication media that transmit more social context cues will foster group performance and satisfaction. 72 3-person groups of undergraduates worked in either computer-mediated or face-to-face meetings on 3 tasks with increasing levels of interdependence: an idea-generation task, an intellective task, and a judgment task. Results showed few differences between computer-mediated and face-to-face groups in the quality of the work completed but large differences in productivity favoring face-to-face groups. Analysis of productivity and of members' reactions supported the predicted interaction of tasks and media, with greater discrepancies between media conditions for tasks requiring higher levels of coordination. Results are discussed in terms of the implications of using computer-mediated communication systems for group work. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
28.
Maren Stephen; DeCola Joseph P.; Fanselow Michael S. 《Canadian Metallurgical Quarterly》1994,108(3):645
Water-deprived and nondeprived rats were fear conditioned with a discrete tone CS and an aversive footshock unconditioned stimulus/stimuli (UCS). 24 and 48 hrs following conditioning, conditional fear to the tone CS and the context cues of the conditioning chamber, respectively, were assessed by measuring freezing behavior. Water deprivation had no effect on baseline responding to either tone or contextual stimuli. Following either 1 or 3 tone-shock pairings, however, water deprivation selectively enhanced conditional freezing to the contextual cues of the training chamber; conditional freezing to the tone was unaffected by water deprivation. These results are consistent with the view that water deprivation affects fear conditioning via an influence on the hippocampus. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
29.
This study examines why people choose to self-disclose on "Donahue" and what role television plays in their lives prior to disclosure. Focused interviews were conducted with 29 informants between the ages of 12 and 68 who had appeared on the program. Analysis revealed that an evangelical fervor underpinned their decision, overshadowing other concerns about disclosure in a public forum. Informants generally reported low levels of television viewing. They held a pragmatic view of talk shows as avenues to reach a dual audience that included the mainstream public and members of their out-groups. Television disclosure is a tactic in a counterhegemonic struggle. Respondents utilized numerous impression management techniques in their efforts to manage their stigmatized status. Participants on "Donahue" risk co-optation, but running the gauntlet of criticism and ridicule allows an opportunity for delabeling rarely afforded to out-groups. 相似文献
30.
Oxygen Tracer Diffusion in Vitreous Silica 总被引:2,自引:0,他引:2
Joseph D. Kalen Rethia S. Boyce James D. Cawley 《Journal of the American Ceramic Society》1991,74(1):203-209
Oxygen diffusion in vitreous silica glass is studied using the gas exchange technique. The tracer concentration profiles are consistent with a model based on two mechanisms, one network and the other interstitial. These processes are coupled through limited network–interstitial exchange. Nuclear reaction analysis and secondary ion mass spectrometry techniques are performed and compared. These results are compared to experiments on transport in thin silica films grown on single-crystal silicon. 相似文献