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 By about 17 days postnatal these misdirected axons or axon segments were withdrawn from the tract.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.     

PCNA在乳腺病变组织中的表达与病理学特性关系

本文运用增殖细胞核抗原(PCNA)单克隆抗体对88例乳腺病变组织进行免疫组化研究,并与乳腺癌组织学分级和淋巴结转移作了对比分析,结果显示:乳腺良性病变阳性率为16%,乳腺癌为73.02%,两者比较有显著性差异P<0.01),pCNA指数与乳腺癌组织学分级淋巴结转移密切相关.作者认为PCNA的表达对区分良恶性病变及组织学分级,淋巴(?)转移(?)为客观可靠,是(?)癌预后判断的良好指标.     

大肠癌组织中细胞胀亡及MMP-2检测

目的 :检测大肠癌组织中胀亡细胞及MMP - 2。方法 :应用透射电镜和免疫组化方法检测 5 1例大肠癌组织中胀亡细胞和MMP - 2的表达。结果 :①大肠癌组织中可检测到不同时期的胀亡细胞。②大肠癌组织中MMP- 2表达率 5 4 .9% (2 8/ 5 1 ) ,明显高于正常大肠粘膜 (P <0 .0 5 )。③MMP - 2在淋巴结转移组的阳性表达率为 6 9.5 7% (1 6 / 2 3) ,明显高于无淋巴结转移组的 4 2 .86 % (1 2 / 2 8) ;有淋巴结转移组胀亡指数明显低于无淋巴结转移组 (P<0 .0 5 )。④MMP - 2表达阳性组OI高于MMP - 2阴性组。结论 :大肠癌组织中存在胀亡细胞和MMP - 2的表达 ,2者关系密切 ,且均与大肠癌的转移有关。     

核素、多普勒和心尖搏动图反映冠心病左室舒张功能的比较——Fish判别分析

用电子计算机对核素、多普勒和心尖搏动图中的8项左室舒张功能指标进行判别分析,比较各指标与冠心病的密切程度。结果显示患者年龄和各项舒张功能指标明显不同于正常组。判别方程为:Z=0.21X_1+23.86X_2-22.88X_3-0.18X_4+2.83X_5+2.06X_6+66.86X_7+1.66X_8。临界值为42.99。判别正确率为100％。各指标的贡献率大小依次为EV/AV,1/3FF,A/E-O,PFR,DATI,EDC,IRT和1/3FFd。提示:多普勒EV/AV与冠心病的关系最为密切,核素的1/3FF次之,心尖搏动图的A/E～O亦是一个较好的指标。     

格林—巴利综合征患者血清和脑脊液中的抗硫脂抗体

探讨抗硫脂抗体与格林－巴利综合征（ＧＢＳ）的关系。方法采用固相酶联免疫吸附法对急性期ＧＢＳ患者血清和脑脊液（ＣＳＦ）中抗硫脂ＩｇＧ和ＩｇＭ抗体进行检测。结果ＧＢＳ患者血清和ＣＳＦ中抗硫脂ＩｇＧ及ＩｇＭ抗体的阳性率均明显高于正常对照组；血清中抗硫脂ＩｇＭ抗体滴度与标本收集时患者发病天数呈负相关（Ｐ＜０．０５），而血清中抗硫脂ＩｇＧ抗体滴度与临床分级（Ｐ＜０．０１）、ＣＳＦ中抗硫脂ＩｇＧ抗体滴度（Ｐ＜０．０１）呈正相关；血清中抗硫脂ＩｇＧ或ＩｇＭ阳性的ＧＢＳ患者，体检时有不同程度的感觉障碍患者为５６％，而血清中抗硫脂抗体阴性患者仅为１６％，两者之间差异有显著意义（Ｐ＜０．０５）。结论抗硫脂抗体可能在ＧＢＳ的病理过程中起重要作用     

2001年广西疟疾防治效果及流行特征分析

目的：分析2001年全区疟疾防治效果、流行趋势、流行特征，为疟疾防治与监测提供依据。方法：对全区2001年疟疾监测结果和调查结果资料进行分析研究。结果：2001年全区疟疾发病率、居民原虫阳性率分别比上年降低21．74％及16．67％，91．49％的当地感染的病人分布在山区县，86．02％的病灶村为1例病人。流动人口检出疟疾病例数占各类人群血检检出疟疾病例总数的87．89％，外出回归人员检出病例中84．79％的病人从事与野外作业相关的工种。结论：全区大部分地区为低疟区，局部地区疟疾传播仍未阻断。流动人口和山区复媒地区是当前疟疾监测的重点。     

棉尘对工人肺功能的影响

目的　评价棉尘对工人肺功能的影响。方法　对 14 6名接棉尘工人和 12 5名对照工人的肺活量(FVC)和第 1秒时间肺活量 (FEV1 0 )进行了检查。结果　前纺、后纺和细纱作业场所空气中的棉尘浓度几何均值分别为 (7 1± 8 7) ,(2 5± 1 7) ,(2 2± 2 4 )mg/m3 ,样品超标率 16 8%。接触组前纺、后纺工人的急性肺功能改变 (APFC)和前纺工人的慢性肺功能改变 (CPFC)检出率较对照组明显增高 (P <0 0 5 ) ,OR及 95 %CI分别为 4 7(1 4～ 16 3) ,4 5 (1 3～ 15 6 ) ,5 6 (1 1～ 2 9 8) ;4 0～岁年龄段接棉尘工人APFC检出率高于对照工人 (P <0 0 5 ) ,OR及 95 %CI为 9 0 (1 1～ 73 8) ;接棉尘女工APFC检出率也比对照女工高 (P <0 0 1)。结论　棉尘有损害肺通气功能的作用 ,以急性改变更为明显     

Sample size determination for an exponential survival model with an unrestricted covariate

We derive formulae for estimating sample size and power for detecting the effect of an unrestricted covariate on survival time. These are useful in designing survival studies with different patterns of recruitment and follow-up when survival time is exponentially distributed. We use the asymptotic covariance matrix, conditional expectation and Taylor's expansion techniques to develop these formulae. Computer simulations indicate that the asymptotic approximations used in developing the formulae are good over a range of parameter values and different patterns of recruitment and follow-up that are relevant to survival studies.     

二步冷冻保存同种异体骨-ACL-骨移植后排斥反应的影响

目的 :探讨新鲜异体和二步冷冻保存同种异体骨 前交叉韧带 (ACL) 骨移植后排斥反应的差异。方法 :将 6 0只新西兰兔和 6 0只日本大耳兔分别随机分成自体骨 ACL 骨移植组、新鲜异体骨 ACL 骨移植组和二步冷冻保存同种异体骨 ACL 骨移植组 ,分别于术前及术后 1周、2周、3周、4周各采血 2ml测定血清中白细胞介素 2 (IL 2 )水平 ,术后 4周、12周切取移植关节 ,作苏木精 -伊红染色。结果 :光镜下检查显示 ,自体移植组和二步冷冻保存移植组均未见明显炎性细胞浸润 ,胶原排列规则 ,分化成熟。新鲜异体移植组有大量淋巴细胞浸润 ,其IL 2水平明显高于自体移植组和二步冷冻保存同种异体移植组且高于术前水平 (P <0 .0 1)。结论 :二步冷冻减轻了同种异体骨 ACL 骨移植后排斥反应 ,移植后其组织学改变同自体移植相似     

准分子激光角膜原位磨镶术治疗近视合并中度以上散光疗效观察

目的 :评价小光斑飞点扫描准分子激光系统应用于准分子激光原位角膜磨镶术 (LASIK)治疗近视合并中度以上散光的疗效。　方法 :对 96例患者 14 4只眼按术前屈光度分成三组 ,Ⅰ组 75只眼 ,近视 0～ - 6D ,散光 - 2～ - 4DC ;Ⅱ组 5 7只眼 ,近视 - 6 .2 5～ 10 .0 0D ,散光 - 2～ - 4DC。Ⅲ组 12只眼 ,近视 - 10 .2 5D以上 ,散光 - 2～- 4DC ;术后随访半年以上 ,并将结果进行比较分析。　结果 :术后 1个月裸眼视力达到 0 .6以上者 ,Ⅰ组为5 .3% ,Ⅱ组为 15 .8% ,Ⅲ组为 6 6 .7% ;术后 1个月裸眼视力达到 1.0以上者 ,Ⅰ组为 94 .7% ,Ⅱ组为 84 .2 % ,Ⅲ组为 33.3%。术后半年裸眼视力达到 0 .6以上者 ,Ⅰ组为 4 % ,Ⅱ组为 14 % ,Ⅲ组为 75 % ;术后半年裸眼视力达到 1.0以上者 ,Ⅰ组为 96 % ,Ⅱ组为 86 % ,Ⅲ组为 2 5 %。术后屈光度在± 1.0D以内者 ,Ⅰ组中为 8% ,Ⅱ组为 14 % ,Ⅲ组为 5 8.3%。术后屈光度在± 0 .5 0D以内者 ,Ⅰ组为 92 % ,Ⅱ组为 86 % ,Ⅲ组为 4 1.7%。术后散光度在± 1.0DC以内者 ,Ⅰ组为 8% ,Ⅱ组为 10 .5 % ,Ⅲ组为 5 0 %。术后散光度在± 0 .5 0DC以内者 ,Ⅰ组为 92 % ,Ⅱ组为 89.5 % ,Ⅲ组为 5 0 %。平均实际切削区直径为 (8.0 2± 0 .0 6 9)mm。　结论 :使用小光斑飞点显像LASIK治疗低