Resistance to the anti-anxiety effect of buspirone in patients with a history of benzodiazepine use.

New England Journal of Medicine (Impact Factor: 54.42). 04/1986; 314(11):719-20. DOI: 10.1056/NEJM198603133141121
Source: PubMed
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    ABSTRACT: It has been repeatedly reported that the anxiolytic action of benzodiazepines in the elevated plus-maze test is abolished in rats that have received a single prior experience of the test apparatus (one-trial tolerance effect). To analyze whether the one-trial tolerance effect of chlordiazepoxide can be influenced by administration of chlordiazepoxide or buspirone on trial 1, male Wistar rats received an IP injection of vehicle, chlordiazepoxide (8 mg/kg) or buspirone (2.5 mg/kg) 30 min. before testing for 5 min. in the plus-maze (trial 1). Seventy-two hours later, the rats received vehicle or chlordiazepoxide 30 min. before the re-exposure to the plus-maze for 5 min. (trial 2). Groups injected with chlordiazepoxide or buspirone on trial 1 and with chlordiazepoxide on trial 2 showed an anxiolytic effect of chlordiazepoxide on trial 2, as opposed to rats injected with vehicle on trial 1 and with chlordiazepoxide on trial 2. As opposed to previous studies, the present results suggest that the influence of prior experience with the plus-maze on the anxiolytic action of chlordiazepoxide during re-exposure seems to depend critically on the drug state in which trial 1 is experienced. These results are discussed with respect to the hypothesis proposed to explain the phenomenon of one-trial tolerance.
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    ABSTRACT: High- and commercial-purity specimens of Type 304 SS from BWR absorber rod tubes, irradiated during service to fluence levels of 6 à 10²° to 2 à 10²¹ n{center dot}cm⁻² (E > 1 MeV) in two reactors, were examined by Auger electron spectroscopy to characterize irradiation-induced grain boundary segregation and depletion of alloying and impurity elements, which have been associated with irradiation-assisted stress corrosion cracking (IASCC) of the steel. Ductile and intergranular fracture surfaces were produced by bending of hydrogen-charged specimens in the ultra-high vacuum of Auger microscope. The intergranular fracture surfaces in high-fluence commercial-purity material were characterized by relatively high levels of Si, P, and In segregation. An Auger energy peak at 59 eV indicated either segregation of an unidentified element or formation of an unidentified compound on the grain boundary. In contrast to the commercial-purity material, segregation of the impurity elements and intergranular failure in the high-purity material were negligible for a similar fluence level. However, grain boundary depletion of Cr was more significant in high-purity material than in commercial-purity material, which indicates that irradiation-induced segregation of impurity elements and depletion of alloying elements are interdependent. 7 refs., 10 figs., 2 tabs.
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    ABSTRACT: Acute and chronic toxicity tests were conducted with three aquatic species to determine the effects of metals combined as mixtures at proposed water quality criteria concentrations and at multiples of the LC50 and maximum acceptable toxicant concentration (MATC) obtained from tests on six metals. These studies were the first part of a larger research effort to derive water-quality criteria for combined pollutants by the U.S. Environmental Protection Agency.