Development of specificity in corticospinal connections by axon collaterals branching selectively into appropriate spinal targets

Corticospinal projections in adult rodents arise exlusively from layer V neurons in the sensorimotor cortex. These neurons are topographically organized in their connections to spinal cord targets. Previous studies in rodents have shown that the mature distribution pattern of corticospinal neurons develops during the first 2 weeks postnatal from an initial widespread pattern that includes the visual cortex to a distribution restricted to the sensorimotor cortex. To determine whether specificity in corticospinal connections also emerges from an intially diffuse set of projections, we have studied the outgrowth of corticospinal axons and the formation of terminal arbors in developing hamsters. The sensitive fluorescent tracer 1, 1′, dioctadecyl-3, 3, 3′, 3′-tetramethylindocarbocyanine perchlorat (DiI) was used to label corticospinal axons from the visual cortex or from small regions of the forelimb or hindlimb sensorimotor cortex in living animals at 4–17 days postnatal. Initially axon outgrowth was imprecise. Some visual cortical axons extended transiently beyond their permanent targets in the pontine nuclei, by growing through the pyramidal decussation and in some cases extending as far caudally as the lumbar enlargement. Forelimb sensorimotor axons also extended past their targets in the cervical enlargement, in many cases growing in the corticospinal tract to lumbar levels of the cord. By about 17 days postnatal these misdirected axons or axon segments were withdrawn from the tract. Despite these errors in axon trajectories within the corticospinal tract, terminal arbors branching into targets in the spinal gray matter were topographically appropriate from the earliest stages of innervation. Thus visula cortical axons never formed connections in the spinal cord, forelimb sensorimotor axons arborized only in the cervical enlargement, and hindlimb cortical axons terminated only in the lumbar cord at all stages of development examined. Corticospinal arbors formed from collaterals that extended at right angles from the shafts of primary axons, most likely by the process of interstitial branching after the primary growth cone had extended past the target. Once collaterals extended into the spinal gray matter, highly branched terminal arbors formed within 2–4 days, beginning at about 4 and 8 days postnatal for the cervical and lumbar enlargements, respectively. These results show that specificity in connectivity is achieved by selectivty growth of axon collaterals in to appropriate spinal targets from the beginning and not by the later remodeling of intially diffuse connections. In contrast, errors occur in the initial outgrowth of axons in the corticospinal tract, which are subsequently corrected. Copyright © 1994 Wiley-Liss, Inc.     

精子尾部低渗肿胀试验、DNA荧光染色有效精子计数在精液分析中的意义

本文对１６０名有正常生育力的男性精液标本同时进行了精子尾部低渗肿胀率（ＨＯＳ）、精子头部ＤＮＡ荧光染色的有效精子计数（ＥＳＣ）、前向运动精子百分率（ＰＭＳ）、活动精子百分率（ＭＳ）的检测，分析它们之间的一致性。结果发现：ＨＯＳ与ＰＭＳ或ＭＳ间的符合率分别为７４％与８８％；ＥＳＣ与ＰＭＳ或ＭＳ间的符合率分别为６３％与６６％；ＥＳＣ与ＨＯＳ间的符合率为６７％。提示ＨＯＳ或ＥＳＣ可从不同角度去反映被测精子的生育力。     

体外丹参、藻酸双酯钠对脑血栓形成患者红细胞与内皮细胞粘附的影响

丹参、藻酸双酯钠是临床治疗脑血管病的常用药。本研究发现，在体外流场中用丹参、藻酸双酯钠分别处理脑血栓形成病人的红细胞后，此红细胞与培养的人脉静脉内皮细胞的粘附数目明显减少、粘附强度明显减弱；而且，在临床常用剂量下藻酸双酯钠的这种抗粘附作用优于丹参。认为丹参、藻酸双酯钠的这种抗粘附作用可能是临床用以治疗脑血栓形成的一个重要机理。     

医院感染及漏报率统计分析

目的　了解我院医院感染发生及漏报率。方法　将我院 2 0 0 3年 1～ 12月出院的所有病例进行回顾性调查。结果　医院感染率 7.3 2 %、漏报率 14 .93 %,均符合国家卫生部要求。结论　做好医院感染监测工作 ,严格执行各项工作制度 ,掌握医院感染与手术并发症的鉴别诊断 ,提高医院感染诊断的准确率     

前哨淋巴结活检术应用于外阴癌的初步研究

目的 探讨前哨淋巴结活检术(SLNB)应用于外阴癌的可行性.方法 选择2004年10月-2008年4月间于中国医学科学院肿瘤医院接受手术治疗、术中采用SLNB的外阴癌患者21例,其中处于研究前期(即2005年5月前)的11例患者采用染料法识别前哨淋巴结(SLN)、处于研究后期的10例患者采用核素-染料联合法识别SLN,术后行常规病理检查.以病理检查结果为金标准,观察SLNB的检测效果;并观察与SLNB相关的并发症的发生情况.结果 21例患者中,20例(95%)检出SLN,其中8例为单侧腹股沟、12例为双侧腹股沟.20例SLN阳性患者共检出83枚SLN,每例患者平均检出4.2枚(1～9枚),每侧腹股沟平均2.6枚(1～6枚).其中,染料法每例患者平均检出4.4枚、每侧腹股沟平均2.5枚,核素-染料联合法每例患者平均检出3.9枚、每侧腹股沟平均2.7枚,分别比较,差异均无统计学意义(t=0.459,P=0.652;t=-0.421,P=0.717).20例SLN阳性患者腹股沟浅组淋巴结中均检出SLN,其中1例双侧腹股沟深组淋巴结中也检出SLN.20例SLN阳性的患者中,8例(10侧腹股沟)术后病理检查显示腹股沟淋巴结转移,其中7例患者(9侧腹股沟)的转移淋巴结中均包括有SLN、1例(1侧腹股沟)出现假阴性.以SLN识别预测同侧腹股沟淋巴结转移的假阴性率为10%(1/10),阴性预测值为96%(22/23).未发现与SLNB相关的损伤及不良反应.结论 SLNB应用于外阴癌安全、可行,以SLN预测同侧腹股沟淋巴结转移具有较高准确性.     

2,7,12,18-四甲基-13,17-二(3-羟基丙基)卟啉的合成及其光敏化活性

由氯化高铁次卟啉经脱铁、酯化、还原合成了光敏剂２，７，１２，１８－四甲基－１３，１７－二（３－羟基丙基）卟啉，并测定其光敏活性     

视盘血管炎——关于混合型的研讨

对６０例（６３眼）视盘血管炎的临床分型进行了探讨，结果表明，除分为Ⅰ、Ⅱ两型外，尚存在混合型，当视盘睫状血管炎性病变波及中央静脉，或两个血管系统同时受炎症侵犯时，即可再现混合型的临床表现，视盘明显水肿，视网膜静脉迂张，散在渗出，出血，动脉狭细。眼底荧光血管造影可见视盘荧光早期充盈明显迟缓，后期渗漏面积〉２．０ＰＤ，视网膜循环时间延长，混合型兼有Ⅰ，Ⅱ两型的临床特征，应作为一个独立类型存在，同时观察     

UVB radiation induces phosphorylation of the epidermal growth factor receptor, decreases EGF binding and blocks EGF induction of ornithine decarboxylase gene expression in SV40-transformed human keratinocytes

Abstract We previously demonstrated that epidermal growth factor (EGF) induces a several-fold increase in ornithine decarboxylase (ODC) activity and the steady-state level of ODC mRNA in cultured SV40-transformed human keratinocytes (1). Pretreatment of cell cultures with ultraviolet B (UVB) radiation resulted in a reduction of EGF-induced ODC activity. To determine whether UVB inhibits the accumulation of ODC mRNA by EGF, cells were pretreated with 20 mJ/cm² UVB or sham-irradiated and then incubated with 100 ng/ml EGF. Northern blot analysis revealed that UVB irradiation entirely blocked the EGF induction of ODC mRNA. Since the binding of EGF to its plasma membrane receptor is the first step in initiating a biological response, the effect of UVB on EGF binding was evaluated. UVB treatment of cultured keratinocytes resulted in an immediate and dose-dependent reduction of EGF binding. Scatchard analysis revealed thai the reduction of EGF binding was due to a 52% decrease in the number of available receptors, from 6.2 × 10⁴/cell to 3.0 × 10⁴/cell. However, UVB decreased the EGF-binding affinity very little (Kd = 0.60 nM in control and Kd=0.75 nM in UVB-treated Z114 cells). In addition, UVB did not alter the rate of EGF internalization. These data suggest that UVB blocks the signal transduction pathway of EGF that is involved in regulation of ODC gene expression. Immunoblot analysis of extracts from irradiated cells showed that UVB induced tyro-sine phosphorylation of EGFR and that the quantity of EGFR protein was unaffected by UVB treatment. Phosphorylation of EGFR may be responsible for decreased binding of EGF to its receptor.     

A framework for automatic analysis of the dynamic behaviour of coronary angiograms

A framework for coronary vessels analysis in digital subtracted angiograms is described. This method combines the motion estimation with the frame-to-frame structure detection in a natural way such that they act interactively. The first step consists of the extraction of the vessel centrelines in one image and their organization into meaningful constituents or branches of the coronary arterial tree. The motion is then estimated along the centrelines through a gradient based method. These motion estimates supply an initial positioning of an active contour model (or snake) in the next image. This model adapts itself by changing its shape to accurately fit onto the new centrelines. This process is then reiterated on the subsequent images to depict the dynamic behaviour of all the relevant branches. The main interests of this scheme are: (1) the active models operate locally so a fast detection of the vessels can be performed; (2) the centrelines extraction is fully guided by the confluence of the motion estimation and the contour model; (3) both morphological and kinetic features are provided on a quantitative basis.