Fluid shear induced endothelial cell detachment from glass - influence of adhesion time and shear stress

In this study, human umbilical vein and human saphenous vein endothelial cells were seeded on glass and exposed to fluid shear in a parallel-plate flow chamber. Cell retention, morphology and migration were studied as a function of shear stress and of adhesion time prior to exposure to shear. Three-hour and 24-h adhesion times gave rise to comparable cell retention values after 2 h of flow for both cell types. Cell retention decreased from 85 to 20% as shear stress increased from 88 to 264 dynes cm⁻² (8.8 to 26 Pa). Mean spreading areas decreased after the onset of flow, but subsequently stabilized to plateau values, which were smaller at higher shear stresses. Shape factors increased faster to higher values as cells were exposed to higher shear stresses, without any obvious preference in orientation of the cells with respect to the direction of flow. Migration was unidirectional with flow and linear with time. Migration was faster for cells which had adhered for 24 h than for cells which had adhered for 3 h and was accompanied by the presence of fibrillar structures left behind on the surface upstream of migrating cells. It is concluded that after 3 h adhesion to glass, cells have adhered with an adhesion strength that does not substantially increase during the next 21 h. However, during this time changes in cell-substratum interactions seem to occur judging by the differences in, e.g., migration rates.     

Diffusion-weighted magnetic resonance imaging for demonstration of cerebral infarcts

Summary Forty-one patients demonstrating clinical symptoms for cerebral infarction were investigated by magnetic resonance imaging with diffusion-weighted echo-planar imaging (DWI) and T2-weighted imaging (T2WI). In 8 patients only DWI showed the cerebral lesions clearly. One patient with positive DWI and T2WI suffered from HSV encephalitis. DWI is superior to T2WI in assessment of small cortical infarcts and cerebral infarction in patients with preexisting vascular lesions. DWI is not specific, so other causes like cerebral hematoma and encephalitis have to be considered.      

Use of commercially available cell culture inserts for primary culture and electrophysiologic studies of guinea pig gastric mucous epithelial cells

Summary The adherence, growth, and electrophysiologic properties of guinea pig gastric mucous epithelial cells were investigated using porous membrane filters. We also tested three commercially available Ussing-type chambers that were designed to be used with the various porous membrane supports. Overall, the 0.45-µm Falcon-Cyclopore porous membrane was found to be very favorable for the consistent attachment and growth of our cells. This same filter also gave good results in the detection of periodic acid Schiff-positive mucous glycoprotein and Nile red neutral lipid fluorescence in the gastric mucous cells. Our cells grew poorly on collagen-coated Costar-Snapwells and Millipore Millicell-CM porous filters. For measurement of transepithelial potential difference resistance, and short-circuit current, the Costar-Snapwell with the Costar-Snapwell Diffusion-chamber system was superior in design and operation when compared to the Costar Transwell-COL, Falcon-Cyclopore, or Anotec-Anocell porous inserts used with conventional Ussing-chambers. The gastric mucous cells grew best on ICN-Cellagen membranes, but these filters routinely detached from their plastic holder and therefore could not be used for Ussing-chamber studies. The large 24.5-mm, 0.40-µm pore size Costar-Transwell-COL and the 24.1-mm, 0.45-µm Falcon-Cyclopore membranes gave good results when used in a modified horizontal-chamber for microelectrode analysis of membrane potentials and resistances of the gastric mucous cell monolayers.     

医用氧舱检验与安全

本文介绍了医用氧舱的检验，医用氧舱的检验包括舱体、供排气、氧系统、电气系统等“硬件”设备的检验和设计、安装与使用管理的“软件”方面的检验。同时，针对检验过程中发现的影响医用氧舱安全使用的常见问题，本文进行了详细的讨论。     

阶跃切应力对内皮细胞释放前列环素的影响

采用流室定量研究阶跃切应力对内皮细胞释放前列环素（ｐＧＩ＿２）的影响。对流室中的内皮细胞连续１００分钟施加１、１０、２０ｄｙｎｅ／ｃｍ￣２的阶跃剪切应力，用放免法测流室的８个时间段流出液的６－ｋｅｔｏ－ＰＧＦｉ＿（１ａ）。绘出切应力刺激内皮细胞释放ＰＧＩ＿２的曲线。结果表明：未施加切应力时，内皮细胞释放ＰＧＩ＿２的量在检测限以下，施加切应力后，ＰＧＩ＿２释放速率很快达极大值，且又在数分钟内减小．施加阶跃切应力越大，ＰＧＩ＿２释放速率曲线峰值越高，但衰减也越快，在８０～１００分钟时间内的前列环素释放速率平均值也越大。由此提示，在活体中血液流变学因素一血流切应力对血管内皮细胞释放前列环素有促进作用。     

青光眼小梁切除术后浅前房临床分析

目的 探讨青光眼小梁切除术后浅前房的原因及发生情况。方法 回顾总结我院1997年1月至2001年12月连续92例104只眼小梁切除术后发生浅前房的程度及原因。结果 本组发生术后浅前房16眼；占15.4％，其中结膜漏1眼(6．25％)，滤过过强11眼(68．75％)，脉络膜睫状体脱离4眼(25％)。结论 青光眼小梁切除术后浅前房原因复杂，与术前眼压关系密切，与患者年龄及青光眼类型无关，最常见的原因是房水滤过过强。     

颅内表皮样囊肿的常规T_1WI、T_2WI、FLAIR及DWI对比分析

目的:通过定性分析和定量比较来探讨颅内表皮样囊肿(ECs)的FLAIR和DWI特征。方法:ECs16例,测量其T1WI、T2WI、FLAIR及DWI上病灶信号强度和ADC值,计算组织间对比度(CR)和对比噪声比(CNR)。结果:在FLAIR上ECs平均信号强度高于脑脊液(CSF),低于脑组织。在T1WI上,表皮样囊肿与脑脊液间的CR和CNR分别是0.11±0.06和1.02±1.11;在T2WI上,ECs与CSF间的CR和CNR分别是0.05±0.04和1.05±0.58;而在DWI上,ECs与CSF间的CR是12.56±2.87,CNR是18.23±5.42。16例患者示踪DWI图像上均呈明显高信号。ECs平均ADC值明显低于CSF(P<0.001),而高于脑白质(P=0.002)。结论:FLAIR对颅内表皮样囊肿显示优于常规MRI序列,DWI描述ECs轮廓优于其它MRI序列。     

MR扩散加权成像鉴别脑结核瘤及高级星形细胞瘤和脑转移瘤的价值

目的探讨MR扩散加权成像（DWI）在脑结核瘤、高级星形细胞瘤和脑转移瘤鉴别诊断中的价值。方法14例脑结核瘤、15例脑高级星形细胞瘤和21例脑转移瘤患者，在术前或接受治疗前行常规MRI和DWI。测量并计算3种疾病瘤体、瘤周围水肿带的平均表观扩散系数（ADC）值和病灶与对侧相应部位正常脑白质区ADC值的比值（rADC值）。结果脑结核瘤瘤体平均ADC值和rADC值分别为（1．2±0．2）×10^-3mm^2·s^-1和1．6±0．3，高级星形细胞瘤瘤体平均ADC值和rADC值分别为（0．8±0．1）×10^-3mm^2·s^-1和1．1±0．1，转移瘤瘤体平均ADC值和rADC值分别为（0．8±0．1）×10^-3mm^2·s^-1和1．0±0．2。3种疾病瘤体平均ADC值（F=33．57，P〈0．01）之间和rADC值（F=33．27，P〈0．01）之间差异均有统计学意义。脑结核瘤瘤周水肿带平均ADC值和rADC值分别为（1．8±0．1）×10^-3mm^2·s^-1和2．5±0．2，脑高级星形细胞瘤瘤周水肿带平均ADC值和rADC值分别为（1．4±0．2）×10^-3mm^2·s^-1和1．8±0．3，脑转移瘤瘤周水肿带平均ADC值和rADC值分别为（1．9±0．2）×10^-3mm^2·s^-1和2．3±0．5。3种疾病瘤周围水肿带平均ADC值（F=23．17，P〈0．01）之间和rADC值（F=5．94，P〈0．01）之间差异均有统计学意义。结论结合MRI、DWI检测方法，根据病灶瘤体和瘤周水肿带的ADC和rADC值可帮助鉴别脑结核瘤、脑高级星形细胞瘤和脑转移瘤。     

弥散张量磁共振成像方法概述

弥散张量成像(diffusion tensor imaging,DTI)是一种根据组织内水分子的弥散特性来探测有机体的微观结构和病理改变的核磁共振成像方法,目前已经成为临床评估和生命科学研究重要的工具。本文结合近年来的文献综述了弥散张量成像的基本原理,列举了目前常用的成像方法,分析了它们的优缺点以及用途,并对弥散张量成像的发展方向作了一些展望。     

TIA磁共振弥散加权成像异常的相关因素分析

目的探讨短暂性脑缺血发作(TIA)磁共振弥散加权成像(DWI)异常的相关因素。方法对2006年1月～2006年12月临床诊断为TIA的住院患者45例进行回顾性分析,比较DWI异常组和正常组的临床特征,并采用Logistic回归分析判定与DWI异常有关的独立因素。结果DWI异常14例(31%);多元回归分析提示TIA症状持续时间≥1h(OR=2.5,95%CI:1.3～8.6)和症状表现为失语伴运动障碍(OR=8.9,95%CI:2.1～36.5)与DWI异常独立相关。结论TIA患者DWI异常与TIA症状持续时间和症状表现为失语伴运动障碍有关。