CARDIOVASCULAR RESPONSES TO SIMULATED MICROGRAVITY IN SPRAGUE-DAWLEY RATS

Microgravity is known to induce orthostatic intolerance and baroreflex impairment in astronauts. Cardiovascular responses observed in 30° head-down tilt rat models, whether 24 hr whole body suspension (WBS) or 7 day tail-suspension (TS), mimic observations made during exposure to microgravity. We evaluated the cardiovascular effects of simulated microgravity and the subsequent post-suspension in rats using the above models. Mean arterial pressure (MAP) of both WBS and TS rats did not change during suspension. In both models, MAP decreased post-suspension and this response lasted for 6 hrs. Salt-loaded animals did not show a post-suspension reduction in MAP. Plasma ionized calcium was decreased at 2 hr of WBS, with no change in sodium, potassium, magnesium, glucose, or hematocrit. Body weight changes were similar for all animals whether under suspension or control conditions. Both rat models demonstrate post-suspension hypotension and these results support the notion that salt-loading may have some beneficial effects in ameliorating this hypotension.     

应用Pentacam三维眼前段分析仪对虹膜夹型人工晶状体植入术后的研究

目的 应用Pentacam术后追踪测量虹膜夹型有晶状体眼人工晶状体(PIOL)中央和周边部与角膜内皮和自然晶体之间的距离,倾斜度、偏心值以及前房深度的变化,评价其在前房的位置.方法 收集自2006年1月以来接受虹膜夹型人晶状体植入术的22例33只眼.术后6个月全部患者行Pentacam检查,测量VRSM50和VRSM60两组不同类型虹膜夹型PIOL中央和周边部与角膜内皮和自然晶体之间的距离,并测量术后1d、1、3及6个月人工晶状体的偏心量、倾斜度及前房深度值.结果 角膜内皮至PIOL光学部前表面距离为(1.94±0.36)mm.PIOL后表面与自然晶状体间的距离为(0.76±0.12)mm.分别比较各组在不同时期的平均偏心量与平均倾斜度,差异无统计学意义(P>0.05).在术后1d、1、3及6个月,比较2组的平均偏心量与平均倾斜度,差异无统计学意义(P>0.05).结论 Pentacam三维眼前段分析仪为PIOL植入术后提供高质量的Scheimpflug摄像,可以为有晶状体眼前房型人工晶状体提供精确的眼内定位,在这一方面具有重要的临床应用价值.     

直立性T波改变与血管迷走性晕厥的相关研究

目的探讨无晕厥病史患者出现的直立性T波改变的发生机理及其与血管迷走性晕厥的相关性;方法利用活动平板运动试验初筛出直立性T波改变预检患者,经基础倾斜试验进一步确证,再行硝酸甘油倾斜试验。第2天,阳性患者经随机分组,双盲对照服用安慰剂(=22)或30mg普荼各尔(=21)60min后重复基础倾斜试验、硝酸甘油倾斜试验。结果100例直立性T波改变患者在基础倾斜试验中无1例阳性反应,在随后的NTTT中有43例出现阳性结果。第2天,安慰剂组直立性T波改变及NTTT阳性有比率明显高于普荼各尔组(依次为86.4%∶23.8%,P<0.01,72.7%∶28.6%,P<0.01)。结论直立性T波改变是人体由卧位到立位引起神经-体液变化所致的心室肌复极异常,它是血管迷走性晕厥形成过程中某一阶段出现的一种伴随现象,与血管迷走性晕厥有一定的相关性,心得安等β-受体阻滞剂作为首选药物来治疗直立性T波改变和伴随有直立性T波改变的血管迷走性晕厥患者,收到肯定的临床疗效。     

心脏神经症患者直立倾斜试验探讨

目的：探讨直立倾斜试验（HUTI＇）对心脏神经症的诊断价值。方法：对59例心脏神经症患者，在排除器质性心脏病后行HUTT。结果：43例呈阳性，阳性发生率为72．9％。不同性别间反应类型有显著差异（P〈0．05），女性多见血管抑制型（占76．9％）。不同反应类型间终末血压、心率有明显差异（P〈0．05）。结论：HUTT可作为心脏神经症有效的辅助诊断方法。     

Haemodynamic responses during head-up tilt and tilt reversal in two groups with chronic autonomic failure: pure autonomic failure and multiple system atrophy

Continuous haemodynamic responses to head-up tilt (HUT) and its reversal were studied in 21 subjects with sympathetic denervation due to primary chronic autonomic failure; 10 had pure autonomic failure (PAF; peripheral failure) and 11 had multiple system atrophy (MSA; central failure); 8 healthy subjects (controls) also were studied. Supine systolic, diastolic and mean arterial pressure (MAP) and total peripheral resistance (TPR) were highest in PAF. The MAP response to HUT and tilt reversal were different between groups. After HUT, MAP increased in controls (12±4 mmHg), but decreased in PAF and MSA (41±4 & 19±4 mmHg respectively); the fall in PAF was greater than in MSA. With tilt reversal, MAP returned promptly, but not entirely to pretilt levels in controls, with small (insignificant) overshoots in MSA and PAF. The TPR response to HUT and tilt reversal was different between groups. After HUT, TPR increased in controls (0.31±0.04 PRU), decreased in PAF (0.23±0.1 PRU) and was unchanged in MSA. With tilt reversal, TPR remained elevated (15 %) above baseline in the controls and rose in PAF (13 %) with no change in MSA. There were no differences in supine heart rate (HR), stroke volume (SV) or cardiac output (CO) between the three groups; HR, SV or CO responses to HUT or tilt reversal also did not differ between the groups. Thus, after HUT, MAP decreased, with greater hypotension induced in PAF than MSA. Since CO did not differ between groups, the decrease in TPR appears to account for the greater fall in BP in PAF than in MSA. The elevated TPR at rest pre-tilt and after tilt reversal probably contributed to supine hypertension in PAF. These haemodynamic observations may aid therapeutic strategies to reduce orthostatic hypotension and prevent supine hypertension. Received: 16 February 2001, Received in revised form: 12 July 2001, Accepted: 1 October 2001     

成人直立倾斜试验90例临床特点分析

目的 多方面探讨直立倾斜试验阳性患者的临床特征，评价直立倾斜试验在疑诊为心脏病患者中的诊断价值。方法 研究对象分为直立倾斜试验阳性组（n=48）及阴性组（n=42），t检验对比二组临床化验指标的差异；计数资料采用X^2检验。结果 以晕厥为主要症状者占62例（68．9％），倾斜试验阳性占54．8％；以胸闷、胸痛或心悸等循环系统症状为主要表现者28例（31．1％），其中倾斜试验阳性50．0％。直立倾斜试验阳性组与阴性组患者临床症状表现比率无统计学差异（P〉0．05）；晕厥患者与循环系统症状患者相比，各直立倾斜试验阳性率之间无统计学差异（P〉0．05）。直立倾斜试验阳性组伴有心电图ST-T改变患者22例（45．8％），77．3％为Ⅱ、Ⅲ、avF导联及（或）V4-6导联ST-T改变。结论 在严格排除心、脑器质性疾患后，应重视以胸闷、胸痛或心悸等循环系统症状为主要表现患者的直立倾斜试验检查，这类患者极有可能为血管迷走性晕厥。     

非接触生命参数检测系统扫描探测技术的研究

详细介绍非接触生命参数检测系统扫描探测技术研究的思路和软/硬件设计。解决了非接触生命参数检测系统中雷达探测方向和角度问题。该技术界面友好,操作简便,扩大了系统的用途。     

A theoretical study of intraocular lens tilt and decentration on perceptual image quality

Maps of perceptual image quality were generated for a range of intraocular (IOL) tilts and decentrations, using a perceptually based metric i.e. the square integral (SQRI) metric. Maps were generated for a well-corrected eye, and for hyperopic (-0.1 mm) and myopic (+0.1 mm) image planes (for 2 and 4 mm pupils). These perceptually based results were compared with a standard optical measure (i.e. the equivalent SQRI for given spectacle power added at the cornea). The image quality changes in maps were small, but detectable (exceeding the perceptual just noticeable difference (jnd) or 1 jnd threshold). Clockwise (negative) tilt combined with decenter fell below the 'contrast reserve' modulation transfer functions (MTFs) for 0.25 and 0.5 D defocus, 4 mm pupil. These errors were larger than those found previously, probably because of the shape-factor of the IOL used. Pupil size contributed the largest drop in SQRI value, followed by clockwise tilt combined with decenter. Anticlockwise tilt with decenter produced image quality improvements for the hyperopic eye. Spot diagrams confirmed defocus and the balance of coma-like aberration and astigmatism as causes of the changes in SQRI values. The SQRI maps conveniently summarize imaging, and may be a useful tool in assessing image quality in eye modelling applications.     

庆大霉素损伤小鼠前庭的实验模型

背景与目的建立一种操作简单、切实可行的前庭损伤小鼠模型。材料和方法小鼠皮下注射(Subcutaneous,sc)庆大霉素400mg/(kg·d)连续15d,每天两次。停药后12h以接触翻正反射恢复时间,头偏和游泳行为对小鼠前庭功能作评估并处死取前庭终器作病理学组织观察。结果庆大霉素400mg/(kg·d)组小鼠在最后一次给药后12h,接触翻正反射恢复时间明显延长,头偏明显且游泳能力显著降低,组织病理学检查证实前庭器的位觉斑和壶腹嵴出现明显损伤。结论该模型是一种操作简单、切实可行的前庭损伤小动物模型。     

头低位卧床对肺血流影响的试验研究

目的观察-6°头低位卧床(HDT-6°)对肺循环血流的影响,并探讨其与肺弥散功能的关系。方法采用YK-10循环系统监测仪和HP2500超声诊断仪,对16名健康男性受试者90minHDT-6°卧床及21dHDT-6°卧床前、后及卧床不同时间肺循环血流、肺血容量、右心输出量等有关指标分别进行了测试。结果在90min卧床试验中,HDT-6°卧床肺血容量较卧床前坐位显著增加,随卧床时间延长,肺血容量渐减少,90min左右已显著少于平卧位水平。在21d卧床中,第3天最低,第7天测量仍显著低于卧床前平卧位对照值,以后保持相对稳定。起床后第3天平卧位测量仍低于卧床前。右心输出量在卧床第3天即显著下降,之后保持相对稳定,在起床第3天测量基本恢复;每搏量在卧床第7天显著降低,一直持续到起床第3天,而在这个阶段,心率则逐渐增加,卧床第20天和起床第1、3天均比卧床前有显著增加。结论头低位卧床使肺血流量增加的同时,增加了肺循环的灌注压,有肺间质水肿的潜在危害。同时肺动脉压升高,以及机体通过神经体液的自我调节,反过来减少了肺灌注,肺毛细血管血量的减少,有自我保护的作用。