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51.
Summary The periaqueductal gray is a brain region of considerable interest. It is innervated by monoamine-containing neurons as well as by a variety of peptidergic fiber systems, and it participates in the regulation of various functions. Virtually nothing is known about monoamine release in the periaqueductal gray and its receptor-mediated modulation. We therefore studied the release of radioactivity from periaqueductal gray slices preloaded with tritriated monoamines, using an in vitro superfusion method.The release of radioactivity from superfused periaqueductal gray slices after preloading of the tissue with [3H]noradrenaline increased upon electrical stimulation in a frequency-dependent manner. The stimulus-evoked release of radioactivity was Ca2+-dependent. Clonidine reduced and yohimbine enhanced the release. The inhibition curve for the effect of clonidine was shifted to the right in the presence of 10–6 M yohimbine. While phenylephrine, isoprenaline, SK&F 38393, quinpirole, carbachol, [Arg8]vasopressin, -MSH and ACTH-(1-24), at a concentration of 10–6 M, did not influence the electrically evoked release of radioactivity, [Leu5]enkephalin reduced it. The selective -opioid receptor agonists [d-Ala2,NMePhe4,Gly-ol5]enkephalin and [d-Arg2,Lys4]-dermorphin-(1–4)-amide reduced the release of radioactivity, whereas the selective opioid receptor agonist [d-Pen2,d-Pen5]enkephalin and the selective K opioid receptor agonist U-69593 had no effect. In the presence of naloxone, which by itself had no effect on the release of radioactivity, the effect of [d-Arg2,Lys4]dermorphin-(1–4)-amide was abolished. These results show that the release of noradrenaline from periaqueductal gray slices is via a Ca2+-dependent. exocytotic process, and that it is modulated through 2-adrenoceptors as well as via -opioid receptors. Though the overflow of radioactivity from slices preloaded with [3H]dopamine in the presence of desipramine was measurable, there are reasons to assume that we are dealing here with the release of tritiated catecholamines from a population of nerve endings consisting of noradrenergic and dopaminergic terminals.The release of radioactivity from periaqueductal gray slices preloaded with [3H]5-hydroxytryptamine upon elevation of the K+ concentration in the superfusion medium was much more pronounced than that induced by electrical stimulation. The K+-evoked release of radioactivity was almost completely abolished in the absence of Cat2+; showing that the release is via a Ca2+-dependent process. 5-Hydrotryptamine reduced the K+-evoked release of radioactivity in a concentration-dependent manner.Some of these data were presented at the XIth International Congress of Pharmacology, 1–6 July 1990, Amsterdam, The Netherlands (Eur J Pharmacol 183:408) Send offprint requests to D. H. G. Versteeg at the above address  相似文献   
52.
王洪军  吴扬  凡英搏 《河北医药》2003,25(12):891-892
目的 探讨前列腺特异性抗原 (PSA)与性激素及酸性磷酸酶 (PAP)在不同年龄组与前列腺体积的变化关系。方法 通过放射免疫分析检测了血清PAP、性激素 (睾酮、促黄体生成激素 )与血清PSA的含量 ,分析了四种指标随增龄变化及对前列腺体积的影响。结果 血清PAP含量随增龄而增高。血清睾酮 (T)含量随增龄下降 ,对照组 ( 2 0~ 3 9)岁睾酮含量为 ( 8.67± 3 .2 5 )ng/ml ,>40岁各组与之比较均明显降低。血清促黄体生成激素 (LH)含量进行性增高。血清PSA含量各年龄组均波动于同一水平上。结论 血清PAP和促黄体生成激素与前列腺体积呈极为显著的正相关关系 ,睾酮的变化亦相反 (r=-0 .45 ,P <0 .0 1)。PAP含量与前列腺体积无关 ,不受年龄影响。  相似文献   
53.
孕育铸铁中石墨分布与力学性能的定量关系   总被引:1,自引:0,他引:1  
本文利用图象分析技术,定量分析灰铸铁孕育处理后石墨相的分布情况。发现石墨相体积分率与灰铸铁综合性能有较为一致的关系,确定了孕育处理时孕育剂应用的最佳方案。  相似文献   
54.
Objectives: Trends in first-time and later PSA procedure rates are ascertained using longitudinal data from a population-based cohort. These trends are compared to trends in prostate cancer incidence to determine the role of PSA in the recent decline in prostate cancer incidence.Methods: Medicare data were linked with tumor registry data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program. A 5 percent random sample (n=39985) of Medicare beneficiaries from the SEER areas without a previous diagnosis of prostate cancer as of January 1, 1988 was followed through 1994. Trends in first-time PSA use were distinguished from those of second or later for men without diagnosed prostate cancer.Results: Trends in the rate of first-time PSA procedures track closely with trends in prostate cancer incidence rates, increasing until 1992 and decreasing thereafter. Similar patterns were observed by race and age group. Geographic variability in the dissemination of PSA screening was observed, yet the association between testing and incidence remained. Men in the cohort had a 4.7 percent chance of being diagnosed within three months of an initial PSA test, with the percentage falling for subsequent tests.Conclusions: It is informative to distinguish first from later tests when assessing the effect of the diffusion of a test in a population. Taking this approach was useful in illuminating the role of PSA testing in a reversal of a long-term increase in prostate cancer incidence rates.  相似文献   
55.
目的:探讨联合应用前列腺特异性抗原(PSA)、游离PSA(FPSA)检测和全身骨显像诊断前列腺癌骨转移的意义。方法:回顾性分析70例经临床确诊的前列腺癌患者,全部行血清PSA、FPSA测定,并作全身骨显像。结果:PSA〈4ng/ml在14例病人中,发生骨转移者7例,诊断阳性率为50%;PSA4ng/ml~20ng/ml共7例,发生骨转移者6例、诊断阳性率为87%;PSA〉20ng/ml组49例,发生骨转移45例,阳性率为92%。结论:PSA、FPSA检测结合全身骨显像,可尽早、全面地发现前列腺癌患者全身骨转移。  相似文献   
56.
Exposure to stressful or fear-inducing environmental stimuli activates descending antinociceptive systems resulting in a decreased pain response to peripheral noxious stimuli. Stimulating mu opioid receptors in the basolateral nucleus of the amygdala (BLA) in anesthetized rats produces antinociception that is similar to environmentally induced antinociception in awake rats. Recent evidence suggests that both forms of antinociception are mediated via projections from the amygdala to the ventral periaqueductal gray (PAG). In the present study, we examined the types of neurochemicals released in the ventral PAG that may be important in the expression of antinociception produced by amygdala stimulation in anesthetized rats. Microinjection of a mu opioid receptor agonist into the BLA resulted in a time dependent increase in tail flick latency that was attenuated by preadministration of a mu opioid receptor or a neurotensin receptor antagonist into the ventral PAG. Microinjection of a delta(2) opioid receptor antagonist or an NMDA receptor antagonist into the ventral PAG was ineffective. These findings suggest that amygdala stimulation produces antinociception that is mediated in part by opioid and neurotensin release within the ventral PAG.  相似文献   
57.
The ventrolateral periaqueductal gray (PAG) and pontine reticular formation (PRF) are implicated in the neuronal network for audiogenic seizures (AGS). The AGS of genetically epilepsy-prone rats (GEPR-9s) culminate in tonic hindlimb extension (TE), and elevated acoustically evoked neuronal firing and burst firing, immediately preceding TE, have been observed in PAG and PRF. This study examined changes in PAG and PRF neuronal firing and behavior in GEPR-9s, following phenytoin administration. Recordings involved 16 PAG and nine PRF neurons in GEPR-9s. Phenytoin in doses (mean, 6. 3 mg/kg) that suppressed TE selectively did not consistently alter PAG neuronal firing. However, these doses of phenytoin resulted in significant (51.6% of control) suppression of PRF neuronal firing. Doses of phenytoin (mean, 8.3 mg/kg), which completely blocked AGS, significantly reduced PAG neuronal firing (64.6% of control), and more greatly suppressed PRF firing (25.8% of control). These results are consistent with a critical role for PRF neurons in generation of TE not evident for PAG. The suppression of PAG and PRF neuronal firing induced by phenytoin with complete seizure blockade is consistent with vital roles for both structures in the seizure network. The differential effects of phenytoin on structures requisite to the seizure network indicate that this experimental approach may be able to identify the most sensitive therapeutic target for anticonvulsant drugs, which could be critical to pharmacological suppression of specific seizure behaviors manifest in various types of convulsions, potentially including human epilepsy.  相似文献   
58.
超声医学图像灰度校正方法的改进   总被引:3,自引:0,他引:3  
介绍了超声医学图像灰度校正常用方法的基本原理,这些方法主要有灰度级校正、灰度变换及直方图修正。对广泛应用且效果较好的直方图均衡化法作了较详细阐述,并针对其对于局部细节增强不显著及不具交互特征等缺点提出了改进方法,并将几种灰度校正方法级联起来对超声图像进行处理,实现了有选择地增强某个灰度值范围对比度的功能,增强了超声诊断图像的实用性。  相似文献   
59.
我国人口的灰色预测模型研究及其应用   总被引:6,自引:1,他引:6  
应用GM(1,1)模型,根据1982~1990年我国人口的实际统计数据建立了灰色预测模型,并对我国未来人口进行了预测。  相似文献   
60.
目的:探讨改良V-Y外眦开大成形新术式。方法:将Y形切口线设计在睑缘灰线,板层劈开上下睑,并在切口末端增加两条垂直于睑缘的辅助切口线,切开睑板及睑结膜;部分或完全切断外眦韧带,充分分离使外眦呈“游离状态”。在无张或微张力的情况下外移外眦。结果:102例外眦开大成形术99例达到预期效果,开大外眦达1.5~5mm。结论:改良V-Y外眦开大成形术相比传统手术,保留了外眦外形结构,术后外眦无变形,远期回缩轻微,是目前比较理想的合乎美学原理的外眦开大成形术式。  相似文献   
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