LA795小鼠肺腺癌细胞系不同肺转移率克隆株流变特性的研究

本文对 ＬＡ７９５小鼠肺腺癌细胞系进行克隆分离，并以不同克隆株接种于 Ｔ７３９同基因小鼠，从而得到非转移、低转移及中转移三个瘤株，而后测定其细胞电泳时间、膜脂流动性、粘附性及剪切应力耐受性。结果表明：转移瘤株的细胞电泳率及粘附性均高于非转移瘤株，三个瘤株膜脂流动性与其肺转移率呈负相关关系，中转移瘤株剪切应力耐受性低于非转移及低转移瘤株。结合我们过去对不同转移率及途径瘤株接种于实验动物后引起其血液宏观流变性变化的研究，我们认为：肿瘤侵袭、转移过程与血液、血细胞及肿瘤自身细胞流变特性变化密切相关，在肿瘤发展早期提高血液及血细胞流变性，而在晚期降低其流变性，对抑制肿瘤转移有一定意义。     

Predictive value of the echocardiographic left atrial dimension in isolated ventricular septal defect

Echocardiographic left atrial dimension has been reported to correlate with left-to-right shunt (Qp/Qs) in children with isolated ventricular septal defect (VSD) or patent ductus arteriosus (PDA). In 17 children with isolated VSD, we prospectively compared Qp/Qs with the ratio of echocardiographic left atrial dimension to aortic root diameter (LAD/Ao) and with the left atrial dimension corrected for body surface area (LAD/M²). The correlation between LAD/Ao and Qp/Qs was not statistically significant (r = 0.49, p > 0.05). The LAD/M² correlated significantly with Qp/Qs (r = 0.66, p < 0.01); however, prediction intervals were excessively wide. Our findings indicate that it is inappropriate to predict Qp/Qs in these patients from echocardiographic LAD.     

Changes in motor unit characteristics after eccentric elbow flexor exercise

Morphological evidence suggests that fast-twitch fibers are prone to disruption of their membrane structures by eccentric exercise. However, it is unclear how this is reflected in the discharge rate and action potential propagation of individual motor units, especially at high contraction levels. High-density surface electromyograms were recorded from biceps brachii muscle and decomposed to individual motor unit action potentials at isometric contraction levels between 10% and 75% of maximal voluntary contraction (MVC) before intermittent maximal elbow flexor eccentric exercise, and two hours (2H), two days (2D) and four days (4D) post-exercise. Maximal voluntary force decreased by 21.3±5.6% 2H and by 12.6±11.1% 2D post-exercise. Motor unit discharge rate increased and mean muscle fiber conduction velocity decreased, at the highest isometric contraction levels only (50% and 75% of MVC) at 2H post-exercise. These results indicate that eccentric exercise can disturb the function of motor units active at high contraction levels in the early stages after exercise, which seems to be compensated by the central nervous system with an increase in neural drive during submaximal isometric contractions.     

Beta-blocker use and the changing epidemiology of out-of-hospital cardiac arrest rhythms

BACKGROUND: The incidence of ventricular fibrillation (VF) as the presenting rhythm in out-of-hospital cardiac arrest (OHCA) is declining, whereas pulseless electrical activity (PEA) is increasing. This changing epidemiology has occurred concomitant with an increase in beta-blocker use. AIMS: The aim of this study was to measure the association of beta-blocker use among prehospital cardiac arrest patients with PEA versus VF as presenting rhythm. MATERIALS AND METHODS: In this retrospective cohort study, records of all OHCA patients presenting to a single municipal hospital between 1 January 2001 and 31 December 2006 were reviewed. Age, sex, race, first documented rhythm, estimated down time, presence of bystander CPR, return of spontaneous circulation, beta-blocker use, and comorbid illnesses were noted. A Mantel-Haenzel chi-square was computed to describe the association between beta-blocker use and PEA, compared to beta-blocker use and VF. A sensitivity analysis was also performed to account for missing data, misclassification of beta-blocker use, misclassification of initial rhythm, confounding by unknown factors, and random error. RESULTS: After exclusion of patients with asystole and patients in whom beta-blocker use was unclear/unknown, a cohort of 179 arrests was evaluated. The odds ratio for beta-blocker use among PEA versus VF patients was 3.7 (95% CI 1.9-7.2), and probabilistic adjustment for exposure and outcome misclassification, confounding, and random error increased the odds ratio to 5.0 (95% CI 1.1-31.0). CONCLUSIONS: There appears to be an association between beta-blockers and the changing epidemiology of arrest rhythms, which may account for the increasing incidence of PEA and concomitant decrease in VF.     

应变率成像评价冠状动脉搭桥对冠心病患者左心房功能的影响

目的 应用应变率成像(SRI)技术评价冠状动脉搭桥(CABG)对冠心病患者左心房功能的影响.方法 分别于CABG术前、术后1周、1月和3月应用SRI技术对23例冠心病患者左心房功能进行评价.结果 与术前比较,术后I周左心房收缩期前容积(LAVp)、最大容积(LAVmax)、最小容积(LAVmin)、主动排空分数(LAAEF)及被动排空分数(LAPEF)变化差异无统计学意义(P>0.05);术后1月,LAVp、LAVmax、LAVmin和LAAEF减小,LAPEF增加,差异均有统计学意义(P<0.05);术后3月,上述指标变化更为显著,差异均有统计学意义(P<0.01).与术前比较,术后1周SRs、SRe和SRa差异无统计学意义(P>0.05),术后1月SRs和SRe升高、SRa降低,差异均有统计学意义(P<0.05);术后3月SRs和SRe升高更为显著,SRa降低更明显,差异均有统计学意义(P<0.01).与术前比较,术后1月、3月左室射血分数的变化率分别与SRa的变化率呈显著负相关(r=-0.751,-0.783,均P<0.01).结论 CABG术可影响冠心病患者左心房功能,表现为储蓄功能和辅泵功能减低,管道功能增加.SRI可以评价左心房功能,动态观察CABG手术前、后左心房功能的变化.     

丙戊酸对致死性失血性休克犬器官功能和预后的影响

目的 探讨组蛋白去乙酰化酶抑制剂丙戊酸(VPA)对致死性失血性休克犬器官功能和预后的影响.方法 20只成年雄性Beagle犬,采用颈总动脉放血(按全身血容量的42%计算)制备失血性休克模型.将模型犬按随机数字表法分为休克对照组和VPA治疗组,每组10只.VPA治疗组于失血后1.5 h静脉注射(静注)VPA 100 mg/kg(溶于20 ml生理盐水),休克对照组在失血后24 h内静注20 ml生理盐水;失血后24 h起两组犬均实施延迟静脉补液.在非麻醉状态下测定犬失血前(0 h)和失血后不同时间点平均动脉压(MAP)及血浆丙氨酸转氨酶(ALT)、肌酐(Cr)和肌酸激酶同工酶(CK-MB),记录尿量及72 h生存率.结果 两组失血后2 h MAP均显著降低;随后VPA治疗组MAP(mm Hg,1 mm Hg=0.133 kPa)迅速回升,于失血后4、8和24 h显著高于相应休克对照组(58.4±7.6比40.3±5.0,84.4±8.0比56.4±4.4,92.6±10.3比72.6±8.9,P＜0.05或P＜0.01).VPA治疗组0～8、8～24、24～48和48～72 h尿量均显著多于休克对照组,但仍显著少于失血前(0 h).两组失血后血浆ALT、Cr和CK-MB均较0 h显著升高;VPA治疗组失血后4 h起器官功能指标显著低于休克对照组[ALT(U/L):80.1±9.8比112.2±10.1;Cr(μmol/L):74.5±8.3比88.0±7.6;CK-MB(kU/L):10.39±1.10比13.67±1.46,P＜0.05或P＜0.01],但失血后72 h仍显著高于0 h(ALT:79.5±7.1比40.5±4.4;Cr:85.6±7.1比46.6±4.8;CK-MB:7.63±0.86比1.66±0.21,均P＜0.01).VPA治疗组失血后72 h生存率显著高于休克对照组[70%(7/10)比20%(2/10),P＜0.05].结论 犬42%血容量失血后静注VPA能有效提高MAP,增加尿量,减轻器官功能损害,提高72 h早期生存率,有潜力成为战争或突发事故及灾害时低血容量休克现场救治的有效药物.     

Temporal Relationship Between Exercise and QT Shortening in Patients with QT Pacemakers

The present study was undertaken to examine the temporal relationship between exercise and QT interval shortening as one of the principal determinants for the functioning of QT pacemakers. Ten patients (mean age of 72.6 years) with implanted QT pacemakers were subjected to supine bicycle exercise with two different slopes, 90% and 80%. The QT interval as seen by the pacemaker was monitored by telemetry and stored on magnetic tape. After the beginning of exercise QT prolongation of a few msec occurred up to 40 sec in most patients. The earliest QT shortening of 4 msec was noted after 63.4 sec with 90% slope and 75.7 sec with 80% slope. The difference was not significant. The further time course was dependent on slope and pacemaker algorithm. Maximal QT shortening was 65.9 msec with 90% and 69.8 msec with 80% slope. It was seen 29.2 sec after termination of exercise with 90% slope and 69.5 sec with 80% slope (P < 0.05). There was no correlation of the measured delays with age. Earliest rate response in QT driven pacemakers is determined by earliest QT shortening on one hand and by the slope setting of the pacemaker on the other, where the limiting parameter appears to be QT shortening, which occurs after the first minute of exercise.