Spatiotemporal profile of synaptic activation produced by the electrical and visual stimulation of retinal inputs to the optic tectum: a current source density analysis in the pigeon (Columba livia)

The optic tectum of the pigeon is a highly organized, multilayered structure that receives a massive polystratified afference of at least five different populations of retinal ganglion cells and gives rise to various anatomically segregated efferent systems. The synaptic organization of retino-tectal circuitry is, at present, mostly unknown. To investigate the spatiotemporal profile of synaptic activation produced by differential (electrical and visual) stimulation of the retinal inputs, we performed a high-spatial-resolution current source density analysis in the optic tectum of the anaesthetized pigeon. Electrical stimuli consisted of brief pulses of different durations applied to the optic nerve head, while visual stimuli consisted of light flashes of different intensities. Electrical stimulation generated sinks confined to retinorecipient layers. The temporal structure, spatial location and thresholds of these sinks indicated that they are all due to primary tectal synapses of retinal fibers with different conduction velocities. Sinks evoked by the fastest retinal axons were more superficially located than sinks produced by slower retinal fibers. Visual stimulation, on the other hand, resulted in a more complex pattern of current sinks, with various sinks located in the retinorecipient layers and also well below. Visual stimulation induced action potentials at superficial as well as deep tectal levels. We conclude that electrical stimulation activates most of the populations of ganglion cells as well as their primary tectal synapses, but is unable to elicit a significant activation of secondary tectal synapses. Visual stimulation, on the contrary, activates just some of the incoming retinal populations, but in a way that produces noticeable secondary activation of intratectal circuits. Laminar segregation of retinally evoked tectal activity, as reported here, has also been found in other vertebrates. Similarities and differences with previous studies are discussed.     

Mapping of c-fos gene expression in the brain during morphine dependence and precipitated withdrawal, and phenotypic identification of the striatal neurons involved

The c-fos gene is expressed in the central nervous system in response to various neuronal stimuli. Using in situ hybridization, we examined the effects of chronic morphine treatment and withdrawal on c-fos mRNA in the rat brain, and particularly within identified striatal neurons. Morphine dependence was induced by subcutaneous implantation of two pellets of morphine for 6 days and withdrawal was precipitated by administration of naltrexone. Placebo animals and morphine-dependent rats showed a very weak c-fos mRNA expression in all the structures studied. Our study emphasized the spatial variations in c-fos mRNA expression, and also revealed a peak expression of c-fos mRNA at 1 h after naltrexone-precipitated withdrawal in the projection areas of dopaminergic neurons, noradrenergic neurons and in several regions expressing opiate receptors. Interestingly, morphine withdrawal induces c-fos mRNA expression in the two efferent populations of the striatum (i.e. striatonigral and striatopallidal neurons) both in the caudate putamen and nucleus accumbens. Moreover, the proportions of activated neurons during morphine withdrawal are different in the caudate putamen (mostly in striatopallidal neurons) and in the shell and core parts of the nucleus accumbens (mostly in striatonigral neurons). The activation of striatopallidal neurons suggests a predominant dopaminergic regulation on c-fos gene expression in the striatum during withdrawal. On the contrary, c-fos induction in striatonigral neurons during withdrawal seems to involve a more complex regulation like opioid-dopamine interactions via the mu opioid receptor and the D1 dopamine receptor coexpressed on this neuronal population or the implication of other neurotransmitter systems.     

Primary central nervous system immunocytoma: MRI and spectroscopy

We report on a young woman with a primary cerebral immunocytoma. Most primary cerebral nervous system lymphomas (PCNSL) are highly malignant undifferentiated B-cell tumours, there are few data on the clinical course, MRI and spectroscopy findings of this rare PCNSL subtype. MRI revealed a radially enhancing tumour with mild perifocal oedema. MR spectroscopy indicated low cell turnover. Slow clinical progression, no significant changes with treatment, and imaging findings were consistent with a low-grade malignant tumour. Received: 21 January 2000/Accepted: 15 February 2000     

The natural history of familial cerebral cavernomas: a retrospective MRI study of 40 patients

Our objective was to determine the natural history and prognostic factors of familial forms of cerebral cavernous malformations (CCM). Cavernomas are one of the most common central nervous system vascular malformations. Familial CCM is increasingly diagnosed, but little is known about its natural history. In a national survey, we analysed clinical and MRI features of 173 patients from 57 unrelated French families. Of these 40 had undergone at least two clinical and MRI examinations. Occurrence of haemorrhage, new lesions, change in signal intensity and size of lesions have been studied by comparison between first and last MRI studies. The CCM were classified according to Zabramski et al. Mean follow-up was 3.2 years (range 0.5–6.5 years). We followed 232 cavernomas (mean 5.9 per patient, range 1–17). Serial MRI demonstrated changes in 28 patients (70 %). Bleeding occurred in 21 lesions (9.1 %) in 14 patients (35 %). The haemorrhagic risk was 2.5 % per lesion-year, higher in type I and brain-stem CCM. We saw 23 new lesions appear in 11 patients (27.5 %), with an incidence of 0.2 lesions per patient year. Signal change was observed in 11 patients (27.5 %), in 14 lesions (6 %), while 9 lesions (3.9 %) in 9 patients (22.5 %) changed significantly in size. Received: 20 May 1999/Accepted: 1 September 1999     

开放性氩氦靶向冷冻治疗脑胶质瘤

目的 探索氩氮靶向冷冻治疗系统(氩氮刀)在脑胶质瘤治疗中的应用价值。方法 开颅后，根据MRI及CT设计冷冻范围，应用氩氮刀冷冻-复温-冷冻后切除胶质瘤，并取冷冻前后标本送病理检查。结果 8例Ⅱ～Ⅳ级胶质瘤患者肿瘤均达到全切，术中出血少，术后短期未见副作用及神经功能缺失。冷冻前后病理切片对比：与冷冻前对比，冷冻后标本在普通显微镜下见有明显出血灶；透射电镜下可见几乎所有细胞核膜肿胀，核形状不规则，染色质凝结为粗颗粒状，明显边聚，线粒体明显肿胀，部分破裂崩解。结论氩氮靶向冷冻治疗系统治疗脑胶质瘤具有能直接摧毁肿胀细胞、手术安全、出血少、全切率高的优点。     

医疗机构药品管理现状

本文对医疗机构、计划生育技术服务机构使用药品的现状与存在问题进行了分析，提出了管理对策，建议实行使用药品法律许可制度。     

凝血酶治疗新生儿上消化道出血的研究

目的　探讨凝血酶治疗新生儿上消化道出血的临床效果。方法　对 2 0 0 0年至今收住院的新生儿上消化道出血患儿 17例 ,除常规综合疗法外 ,静脉滴注维生素K1 10mg/d ,连用 4～ 7d。结果　治疗组 17例 ,显效 16例 ,显效率 97% ,对照组 15例 ,显效 7例 ,显效率 40 % ,两组比较有明显差异性 (P <0 0 0 1)。治疗组止血时间 1 3 5± 0 6d ,对照组平均止血时间 3 2±0 5d ,两组比较有明显差异性 (P <0 0 0 1)。结论　凝血酶治疗新生儿上消化道出血为一种安全、方便 ,无副作用的首选止血药物     

盐酸洛美沙星左氧氟沙星治疗泌尿生殖系感染

目的观察评价盐酸洛美沙星与左氧氟沙星治疗泌尿系感染的疗效及安全性.方法69例病人随机分成两组,治疗组38例,用盐酸洛美沙星0.2g,po,bid;对照组31例,用左氧氟沙星0.1g,po,tid,疗程均为7～14d.结果治疗组临床有效率为92.1%,细菌清除率为91.5%;对照组分别为90.3%和92.5%;两组间无显著性差异(P＞0.05).结论盐酸洛美沙星治疗泌尿生殖系感染疗效确切,安全方便,不良反应小.     

作用于消化系统药物应用分析

目的：统计分析我院消化科作用于消化系统药物用药情况，提高临床合理用药水平。方法：应用电脑统计2002年9月4日～2003年5月6日我院消化科用药有效数据，采用金额排序法和DDDs排序法，对作用于消化系统药物进行统计分析。结果：用药金额和DDDs最高的是抗酸药及治疗消化系溃疡药类，具体药物是奥美拉唑。结论：我院消化科对作用于消化系统药物的使用基本合理。     

乌头植株再生体系的建立

目的 建立乌头高效再生系统，短期内获得大量优质种苗。方法 以试管苗叶片为外植体，在添加不同激素配比的培养基上培养。结果 培养基MS BAl．0mg/L KT0．5mg/L NAA0．2mg/L最适合于乌头叶片不定芽的分化；培养基MS BAl．5mg/L NAA0．1mg/L有利于芽的增殖；培养基MS BA0．5mg/L NAA0．1mg/L有利于芽的伸长；不加激素的1／2MS培养基有利于根的诱导。结论 采用组织培养方式可进行乌头的快速繁殖，使乌头种苗的工厂化生产成为可能。