反复下体负压暴露对心脏泵血功能的影响

目的　探讨反复下体负压暴露对心脏泵血功能的影响及其与下体负压耐力的关系 .方法　 2 7名男性健康被试者随机分成 3组 ,分别进行 - 5 .33 k Pa 8min(A组 )、- 6 .6 7k Pa4min(B组 )、- 6 .6 7k Pa8m in(C组 )的下体负压锻炼 ,1次· d- 1 ,连续 8d,记录心率及血压 .锻炼前、后测量平卧位心脏泵血功能 .结果　 A组锻炼前后心脏功能各项指标无显著变化 (P>0 .0 5 ) ,B组锻炼后左室射血期 (L VET)、每搏输出量 (SV)、心输出量 (CO)、心指数 (CI)、血管顺应性 (C)分别为 :(2 97± 14) ms,(113± 37) m L,(7.3± 2 .3) L· min- 1 ,(4.2± 1.4) L·min- 1·m- 2 ,(2 .7± 1.0 ) m L·Pa- 1 ,较锻炼前显著增加 (P<0 .0 5 ) .而总外周阻力 (TPR)为 (7.6± 2 .9)L· Pa- 1·cm- 5,较锻炼前显著降低 (P<0 .0 5 ) .C组锻炼后较锻炼前上述指标变化趋势与 B组相同 ,但未达显著水平 .结论　 - 6 .6 7k Pa反复下体负压暴露可改善心脏泵血功能 ,其可能通过相对提高心水平动脉血压而提高下体负压耐力     

NADPH氧化酶家族在心血管疾病中作用的研究进展

烟酰胺腺嘌呤二核苷酸磷酸氧化酶是心血管系统中活性氧(reactive oxygen species,ROS)的主要来源,它包 括7种亚型并分别表达在不同的心血管细胞及其细胞器中,参与调节细胞增殖、迁移、分化、凋亡、衰老和炎症反应 等多种活动,其衍生的ROS参与高血压、动脉粥样硬化、糖尿病血管病变、心肌梗死后心室重构等多种心血管疾病 的病理过程。     

头高位倾斜时心血管反应的仿真

仿真头高位倾斜时心血管系统的反应,进一步研究有关立位应激的生理机制。方法以仿真下体负压时心血管反应的模型为基础,在血液重新分配子模中引入了重力致血液重新转移的环节,在压力反射控制子模型中考虑了心水平与颈动脉压力感受器间的流体静压差。     

Increasing physician involvement In cholesterol-lowering practices: The role of knowledge,attitudes and perceptions

The study evaluated a multifaceted educational intervention systematically designed to increase physician involvement in cholesterol-lowering practices. We hypothesized that knowledge, perceptions and behaviours would be enhanced in participating physicians, compared with controls. Method: Fifty-one family physicians were assigned randomly to three groups; the two experimental groups attended a training workshop, received physician and patient education materials and ongoing consultant support. One experimental group also received a “cuing” intervention. The control group received no interventions. Outcome measures included knowledge and attitude scores, self-efficacy perceptions, and physician dietary counselling behaviour. Measures were taken at pretest, 6 weeks and 15 months later. Results: Intervention group physicians achieved significantly higher knowledge scores than the control group at the six-week test; the differences disappeared at 15 months. Attitudes, self-reported practices and overall self-efficacy scores were similar across groups. Within group variation was highly significant. Physician dietary counselling scores were significantly higher in the intervention groups (p = 0.0001). Some associations were seen among knowledge, attitude, self-efficacy and dietary counselling scores. Conclusion: Physician behaviour change in cholesterol reduction may not depend entirely upon knowledge, attitudes and perceptions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of mental state on heart rate and blood pressure variability in men and women

Summary. The effect of different mental states on autonomic modulation of the cardiovascular system was assessed in healthy, normotensive men (n=18) and women (n=12). Heart rate variability (HRV), systolic blood pressure variability (BPV) and arterial baroreflex function were assessed during 4 tests at rest ((10 min+5 min recovery)×4):

• 1 Control (spontaneous breathing, (SB)
• 2 Mental distraction (SB+word puzzle)
• 3 Conscious control of breathing (paced at SB rate) and
• 4 Mental stress (SB+computer quiz).

There were no significant gender differences in the responses to the interventions in terms of arterial (spontaneous) baroreflex (SPBX) control of HR, and indices of time and frequency domains of HRV and BPV, with the exception of the sympathetic indicator of HRV (low frequency power/total power; P<0.01) which was lower in women during control and mental stress tests. Conscious control of breathing at SB did not alter HRV, BPV or SPBX in either men or women. Mental distraction and mental stress led to decreases in indices of time and frequency domains of HRV and BPV in all subjects, as well as increases in HR during distraction and in systolic BP during stress. These findings suggest that in studies of cardiovascular control:

• 1 Paced breathing at SB can be used for individuals with irregular breathing patterns
• 2 The extent of mental stress achieved is intervention-specific and for the most part, independent of gender and
• 3 Resting assessment of HRV, BPV and SPBX can be made by having subjects sit quietly without interventions in a controlled laboratory setting.

     

The recent saga of cardiovascular disease and safety of oral contraceptives

This review presents detailed risk estimates from relevant epidemiological and other studies on the comparative safety of second and third generation oral contraceptives (OC). Written with the intention of presenting a repository of the available information, it also discourses briefly into the symptomatology and diagnosis of diseases associated with OC use and presents some of the critical comments made about various epidemiological analyses. A general critique including observations and opinions of various investigators completes the review. We stress that our own opinions on the various studies, or an attempt to adjudge the relative safety of second and third generation OC, are not given since they form the substance of our second paper which completes this symposium.     

多普勒超声心动图评估左心室舒张末压的研究

目的探讨多普勒超声心动图评估左室舒张末压的有效方法与指标。方法对６８例病人采用左心导管测压及经胸多普勒超声心动图检测。结果对比研究显示,联合肺静脉与二尖瓣血流频谱分析优于二尖瓣血流频谱分析,肺静脉Ａ峰和二尖瓣Ａ峰时限差值（ＰＡｄ－Ａｄ）与左室舒张末压实测值呈最佳相关性（ｒ＝０．７２,Ｐ＜０．０１）。结论认为应用多普勒超声心动图测定ＰＡｄ与Ａｄ,并以其差值估测左室舒张末压,是一项简便、可靠的无创性评估左室舒张末压的方法。ＰＡｄ－Ａｄ≥０可作为临床判断左室舒张末压增高［≥２．０ｋＰａ（１５ｍｍＨｇ）］的一项半定量指标。     

Volume control during periodic changes of blood volume in the alert rat

Summary Blood (3.4–13.5% of blood volume) was pumped in and out of the circulation of rats at different rates and period lengths during continuous measurements of blood conductivity (reciprocally related to hematocrit) and arterial pressure. Hct followed the same zig-zag course as the induced changes of blood volume in every case, indicating that fluid shifts (v) between interstitium and intravascular space closely follow blood volume changes. As the het increase during reinfusion was not as great as the preceding decrease, hct dropped continuously during the 20–90 minutes of experimentation, so that a final volume increase (v) by about 4% was calculated, which was confirmed by a corresponding decrease of plasma protein concentration. Both final v and v during periodic volume change (% B.V.) were greater when arterial pressure dropped. v was directly related to % B.V. but not to its rate of change. Heart rate dropped slightly at the end of the reinfusion periods, whereas it rose to control at the end of the withdrawal periods. The results were regarded as evidence of blood volume regulation proportional to the absolute volume of blood lost in non-hypotensive hemorrhage.Supported by DFG-grant AZ 3/3     

Unaltered insulin sensitivity during calcium channel blockade with amlodipine

Summary The sensitivity of peripheral tissues to insulin is of pathophysiological, therapeutic and possibly also of prognostic relevance. Calcium channel blockers are widely used in the treatment of cardiovascular disorders that are commonly associated with decreased insulin sensitivity (S_I). To evaluate the effects of calcium channel blokkade on S_I, glucose homoeostasis and lipid profiles, studies were made of S_I (determined by the Minimal Model Method of Bergman), basal glucose and insulin levels, serum total triglyceride (Tg) and lipoprotein cholesterol (C) fractions and certain other variables in 38 healthy young men (24 y) during placebo and after 3 weeks of calcium channel blockade with amlodipine 5 mg once daily. Measurements were made after 3 days on a standard diet (2200 kcal · day^–1, 45% carbohydrates, 40% fat and 15% proteins) and after an overnight fast. Compared to placebo, amlodipine decreased supine systolic blood pressure (P<0.01). Heart rate, body weight and 24 h urinary sodium excretion were unaltered, and so were fasting plasma glucose (placebo vs amlodipine: 4.86 vs 4.83 mmol·1^–1, respectively) and insulin levels (7.7 vs 7.9 U·ml^–1), S_I (10.5 vs 9.6·10^–4 × min^–1 pro U·ml^–1), serum total Tg, C and lipoprotein C fractions.The findings demonstrate unchanged insulin sensitivity and secretion, as well as lipoprotein regulation, during maintenance administration of 5 mg amlodipine daily to healthy young men.This work was supported in part by the Swiss National Science Foundation     

The impact of anticipation of job loss on psychological distress and worksite blood pressure.

The impact of occupational stressful life events on psychological distress and blood pressure was examined among employees of a major New York City brokerage firm undergoing massive layoffs. One hundred thirty-nine employees of the firm, who had participated in a blood pressure screening in 1986, were rescreened during the period of layoffs within their company in 1989. About two-thirds of the 139 employees reported being "somewhat" or "very" anxious or upset in 1989 during the period of layoffs, and psychological distress was significantly elevated among those employees reporting possible or definite layoff or job change and/or difficulty in obtaining a comparable job. However, we found no increase in overall blood pressure level, and no effect of anticipation of job loss on 1989 blood pressure when controlling for 1986 blood pressure level, age, body mass index, work hours, and other demographic variables. On the other hand, employment in a department sold to another employer on the day of screening, as well as employment in a clerical job title, were both associated with significant increases in diastolic blood pressure of about 5 mm Hg.