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排序方式: 共有3685条查询结果,搜索用时 11 毫秒
191.
Carolyn Cidis Meltzer Gwenn Smith Julie C. Price Charles F. Reynolds III Chester A. Mathis Phil Greer Brian Lopresti Mark A. Mintun Bruce G. Pollock Doron Ben-Eliezer Michael N. Cantwell Walter Kaye Steven T. DeKosky 《Brain research》1998,813(1)
The serotonin (5-HT) neurotransmitter system, which has a widespread distribution in the central nervous system, has been implicated in regulating mood and many human behaviors. There is evidence from postmortem human studies and limited information from prior in vivo studies to support a decline in 5-HT2A receptor density with aging. We examined nine elderly (ages 61–76) and nine young (ages 18–29) healthy individuals with positron emission tomography (PET) and [
]altanserin, a ligand with high affinity for the 5-HT2A binding site. The PET data were corrected for differences in brain tissue volume between the young and elderly subjects using a magnetic resonance (MR) imaging-based partial volume correction method. Highly significant and widespread cortical reductions in 5-HT2A specific binding were demonstrated in the elderly group relative to young controls. Regional losses averaged 61% before and 57% following correction for effects of cerebral atrophy. This finding, which is consistent with prior postmortem and in vivo studies, has both etiological and potential therapeutic implications for behavioral changes commonly observed in the elderly, including geriatric depression. 相似文献
192.
Repeated administration of methamphetamine (METH) results in damage to nigrostriatal dopaminergic neurons. Both competitiveN-methyl-d-aspartate (NMDA) receptor antagonists and use-dependent cation channel blockers attenuate METH-induced damage. The objectives of the present study were to examine whether comparable reductions in METH-induced damage could be obtained by compounds acting at strychnine-insensitive glycine receptors on the NMDA receptor complex. Four injections of METH (5 mg/kg i.p.) resulted in a 70.9% depletion of striatal dopamine (DA) and 62.7% depletion of dihydroxyphenylacetic acid (DOPAC) content, respectively. A significant protection against METH-induced DA and DOPAC depletion was afforded by the use-dependent channel blocker, MK-801. The competitive glycine antagonist 7-chlorokynurenic acid (7-Cl-KA), the low efficacy glycine partial agonist (+)-3-amino-1-hydroxy-2-pyrrolidone ((+)-HA-966), and the high efficacy partial glycine agonist 1-aminocyclopropane-car☐ylic acid (ACPC) were ineffective against METH-induced toxicity despite their abilities to attenuate glutamate-induced neurotoxicity under both in vivo and in vitro conditions. These results indicate that glycinergic ligands do not possess the same broad neuroprotective spectrum as other classes of NMDA antagonists. 相似文献
193.
Jian M. Yu Robert Jrme Noel Overbergh Phil Hammond 《Macromolecular chemistry and physics.》1997,198(11):3719-3735
Poly(methyl methacrylate)-block-polybutadiene-block-poly(methyl methacrylate) (MBM) triblock copolymers and their hydrogenated counterparts with poly(ethylene-co-1,2-butylene) midblock (MEBM) were swollen by an aliphatic oil of high boiling point which is a selective solvent for the central block. Thermoreversible gels are accordingly formed by both MBM and MEBM copolymers above a critical polymer content (Cr), which depends on the nature of the midblock and not on the copolymer molecular weight, at least in the investigated range. Cr has been found to be 5 wt.-% for an MBM block copolymer and 2 wt.-% for MEBM copolymers of various molecular weights. Gels of MEBM triblock copolymers exhibit interesting mechanical properties, such as high elongation at break (up to 870%) and high tensile strength (32 kPa). The most interesting feature of the MEBM gels is an upper service temperature as high as 170°C, thus more than 100°C higher than the value (47°C) reported for gels of an SEBS copolymer (S = polystyrene) of comparable molecular weight (100000) and composition (ca. 30 wt.-% hard block). The morphology of MEBM gels was studied by scanning electron microscopy (SEM) and found to be cocontinuous in case of a gel containing 20 wt.-% copolymer. 相似文献
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195.
Ann Huang Jeffery L. Barker Steven M. Paul Victoria Moncada Phil Skolnick 《Brain research》1980,190(2):485-491
Primary cultures of fetal mouse brain and spinal cord were examined for the presence of binding sites for [3H]diazepam. Both brain and spinal cord cultures contain high affinity binding sites which resemble benzodiazepine receptors found in mammalian CNS with respect to both pharmacologic profile and response to exogenously applied GABA. These observations, coupled with the electrophysiologic properties of these cells suggest that primary cultures of fetal mouse brain and spinal cord may be valid models for studying the role and regulation of the benzodiazepine receptor. 相似文献
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197.
B. D. Hore B.Sc. M.B. B.S. M.R.C.P. M. Phil. F. V. Nicolle MB.B. Chir. F.R.C.S. J. S. Calnan M.R.C.P. F.R.C.S. 《Archives of sexual behavior》1975,4(1):81-88
The syndrome of transsexualism is now regarded as a distinct entity separate from transvestism and homosexuality (Benjamin, 1966; Green and Money, 1969). It refers to those patients who since childhood have been convinced of their wrong sex assignment and who wish to attain the sexual characteristics of the opposite sex and to live as a member of that sex. The present report is an initial one referring to the first group of transsexual patients studied at a postgraduate teaching hospital by a multidisciplinary team. Their study has three aims: first, to compare this group of patients with other series; second, to evolve a surgical technique of sex reassignment; and, finally, to assess the success of such surgery in allowing the patients to attain a satisfactory adjustment in their new gender role. 相似文献
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