丹参及血管内皮生长因子对动物肢体缺血模型侧支循环建立的作用

目的 :建立兔左后肢无主干及分支动脉供血的缺血模型 ,并观察丹参及血管内皮生长因子 ( VEGF)对兔后肢缺血模型侧支循环建立的作用。方法 :通过手术方法在兔后肢大腿段建立一个无主干及分支动脉供血的严重缺血模型。动物随机分为 5组 :未治疗组、丹参组、VEGF组、丹参加VEGF组及生理盐水对照治疗组。在解剖及生理水平上观察各组动物缺血肢体缺血及侧支循环建立情况。结果 :术后第 1天未治疗组动物左 /右小腿血压比为 0 ;动脉造影显示左侧只有髂外动脉中段以上显影、以下主干及分支均未显影。对侧后肢主干及分支动脉显影良好 ,即左侧毛细血管密度( 4 9.8± 1 7.6)个 /mm2 ,右侧为 ( 385 .7± 36.7)个 /mm2 ,P<0 .0 0 1 ;毛细血管数 /肌束数比值 :左侧( 0 .2 1± 0 .0 7) ,右侧 ( 0 .98± 0 .0 5 ) ,P<0 .0 0 1。治疗结束时 ,丹参加 VEGF组动物小腿血压比最高( 0 .74± 0 .1 7) ,它显著高于对照组、丹参组和 VEGF组 ;毛细血管密度与毛细血管数 /肌束数比值亦以丹参加 VEGF组为最高 ;动脉造影显示 ,丹参加 VEGF组中缺血组织处具有治疗意义的粗大的侧支循环形成。结论 :丹参与 VEGF联合应用具有强大的促进缺血模型侧支循环建立的作用     

反应停抗Lewis肺癌小鼠肿瘤血管生成的作用

目的 :研究具有抗血管生成作用的药物反应停对 Lewis肺癌小鼠皮下移植瘤和肺转移瘤的作用 ,并探讨其与肿瘤细胞凋亡的关系。方法 :2 4只皮下接种 Lewis肺癌肿瘤细胞 ( 1×1 0 6cell/mouse)的 C57BL/6小鼠随机分为两组 ,治疗组每日反应停 77.5 mg· kg-1灌胃 ,对照组每日生理盐水灌胃。第 2 1天处死动物 ,秤取瘤重、肺重 ,计数肺转移结节数 ,免疫组化染色后计数肿瘤组织微血管密度 ,流氏细胞仪测定分析肿瘤细胞凋亡率及细胞周期。结果 :反应停治疗组皮下移植瘤重量与对照组间差异无显著性 ( P>0 .0 5 ) ,但是肿瘤平均体积有下降趋势 ;反应停治疗组肺重、肺转移结节数目、肿瘤微血管密度低于对照组 ( P<0 .0 5 )。反应停治疗组肿瘤细胞凋亡率及 G1、S、G2 期肿瘤细胞百分数与对照组比较差异无显著性 ( P>0 .0 5 )。结论 :反应停有明显地抑制肿瘤细胞转移的作用 ,移植瘤体积有缩小的趋势 ,但不影响细胞的增殖周期     

脉冲Nd：YAG激光照射对大鼠炎症牙龈组织的作用

患实验性牙龈炎的大鼠牙龈（６例）经脉冲掺钕钇铝柘榴石激光（Ｎｄ：ＹＡＧ激光）照射后进行光镜及超微结构观察。目的在于了解低能量Ｎｄ：ＹＡＧ激光照射对牙龈炎症的治疗作用。炎症牙龈经输出能量为１．５Ｗ，脉冲数为２０ＰＰＳ的激光照射后与对照组相比较，形态学上有如下变化：上皮细胞无变性；牙龈上皮层数较炎症时减少；上皮下炎细胞浸润明显减少；上皮细胞间隙变小；上皮下结缔组织内产生大量的排列致密的胶原纤维。结果提     

苯妥英钠、苯巴比妥钠诱导建立难治性癫(癎)动物模型

目的探索性应用苯妥英钠（PHT）、苯巴比妥钠（PB）诱导建立难治性癫痫动物模型，并研究其多药耐药机制。方法将60只大鼠随机分为实验组50只和对照组10只；实验组给予亚抽搐剂量戊四氮腹腔注射，其中45只大鼠确定点燃．将其随机分为给药组35只和未给药组10只。给药组应用较大剂量PHT、PB腹腔注射，其间注射小剂量戊四氮．根据Racine行为分级以及脑电图改变，从中筛选出耐PHT和PB的难治性癫痫动物模型。应用免疫组化法观察比较P糖蛋白（Pgp）在各组脑组织中的表达。结果12只大鼠制成难治性癫痫动物模型（耐药组），11只为药物有效组，12只死亡。耐药组大鼠脑组织Pgp表达较对照组、未给药组和药物有效组增强，差异有高度统计学意义（P〈0．01）。结论应用较大剂量PHT和PB诱导点燃大鼠制作难治性癫痫的动物模型．方法可行。该模型可以用于研究难治性癫痫脑内PgP的表达。PgP的高表达与难治性癫痫发生密切相关。     

股骨头骨骺缺血再灌注模型的建立

目的：建立缺血再灌注引起幼年兔股骨头骨骺细胞损伤的模型。方法：取12只1kg左右幼年新西兰兔，月龄，性别不限。切开兔髋关节囊，切断圆韧带，显露股骨颈，取皮筋对股骨颈进行加压，皮筋拉力约0．5kg，阻断股骨头骺动静脉血供6h、24h。松开皮筋分别恢复血供6h、24h、168h后取兔股骨头标本。结果：在取标本前进行同位素骨扫描及腹主动脉造影，证实缺血及再灌注有效。常规HE染色及胶原染色病理切片显示：单纯股骨头骨骺缺血6h骨骺骨细胞变性不明显，缺血24h组骨骺骨细胞变性；缺血24h股骨头再灌注168h后骨细胞明显坏死。结论：缺血再灌注可加重幼年兔股骨头骨骺骨细胞损伤。     

Effects of angle and laminectomy on triangulated pedicle screws

We aimed to demonstrate the effect of angle and laminectomy on paired pedicle screws to determine whether a 90 degrees screw angle is optimal as has been previously suggested. According to the angle between right and left screws, 28 calf vertebrae were divided into three groups and instrumented as follows: Group I: 60 degrees screw angle; Group II: 90 degrees angle; Group III: 60 degrees angle with laminectomy. The screws were connected using rods and cross-fixators and tested to peak pullout force. Triangulated pedicle screws provided 76.5% more pullout strength than single screws. Most of the specimens failed through loss of convergence angle (toggling of screws on the rods) and subsequent uni- or bilateral screw pullout. Mean+/-SD peak loads were: Group I: 2071+/-622 N; Group II: 1753+/-497 N; Group III: 2186+/-587 N. The differences were not significant (p>0.05). 90 degrees triangulation was not associated with a superior pullout performance versus conventional 60 degrees triangulation, suggesting that achieving additional triangulation angle is not necessary to obtain increased pullout strength. Laminectomy did not alter the effect of triangulation on fixation strength.     

Causal models of attention-deficit/hyperactivity disorder: from common simple deficits to multiple developmental pathways.

Until recently, causal models of attention-deficit/hyperactivity disorder (ADHD) have tended to focus on the role of common, simple, core deficits. One such model highlights the role of executive dysfunction due to deficient inhibitory control resulting from disturbances in the frontodorsal striatal circuit and associated mesocortical dopaminergic branches. An alternative model presents ADHD as resulting from impaired signaling of delayed rewards arising from disturbances in motivational processes, involving frontoventral striatal reward circuits and mesolimbic branches terminating in the ventral striatum, particularly the nucleus accumbens. In the present article, these models are elaborated in two ways. First, they are each placed within their developmental context by consideration of the role of person x environment correlation and interaction and individual adaptation to developmental constraint. Second, their relationship to one another is reviewed in the light of recent data suggesting that delay aversion and executive functions might each make distinctive contributions to the development of the disorder. This provides an impetus for theoretical models built around the idea of multiple neurodevelopmental pathways. The possibility of neuropathologic heterogeneity in ADHD is likely to have important implications for the clinical management of the condition, potentially impacting on both diagnostic strategies and treatment options.     

子宫内膜异位症猕猴动物模型的建立

目的构建子宫内膜异位症(EM)猕猴动物模型。方法选择5只健康、月经规律的雌性猕猴(4只实验猴、1只对照猴),在月经第8~15天,雌激素高峰的第3~5天,手术将猕猴的子宫内膜种植到盆腔子宫腔以外的部位,对照猕猴用大网膜取代内膜种植。在术后第2、4个月动物月经周期的第8~15天开腹或腹腔镜探查。结果术后第2个月探查,4只实验猴中,3只异位内膜种植存活,其中2只形成异位囊肿。术后第4个月,对2只已形成EM的猕猴行腹腔镜再次探查,其盆腔粘连,异位内膜生长情况与术后第2个月基本相似;3只形成EM的猕猴精神状态、饮食、体质量增长情况均较对照猕猴差,2只发生肠套叠死亡。结论本研究根据种植学说原理成功地构建了子宫内膜异位症猕猴动物模型,但猕猴的个体差异是模型是否成功的一个关键因素,因而认为遗传因素是子宫内膜异位症发病中的另一重要机制,子宫内膜异位生长对机体的整体机能有较为明显的影响。     

The application of basic science concepts to clinical problem-solving

This study looks at the relationship between anatomical concepts held by medical students and their clinical application, and develops a testable model of how students use basic science concepts for clinical problem-solving. According to the model, the essential prerequisites to solve a clinical problem using basic science information include the appropriate basic science knowledge, the ability to collect and interpret clinical information, with the key concept being the link that must then be made between clinical data and basic science. A detailed analysis of the individual components of the model should help to clarify and resolve some of the debate about the nature and balance of basic science and clinical education. A neurological diagnostic problem was used to test the assumptions of the model in a group of medical students who had minimal clinical experiences. There was no demonstrable relationship between anatomical knowledge as assessed by conventional tests and the diagnosis. There was a powerful relationship between measures of organization of knowledge and diagnosis, suggesting that the organization and development of concepts is the key to correct diagnosis. The findings have significant implications for assessment purposes and suggest that standard methods as generally practised may not measure the appropriate conceptual development and are not congruent with curricular objectives. Through the examination of its different learning outcome measures, the model may also be used to provide a profile of individual students or classes, which should help teachers and students deal with difficulties that may be experienced in learning to link clinical and basic science concepts.