Effects of synchronization in the pacemaker during high-frequency atrial stimulation

I. M. Sechenov Medical Academy, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. D. Ado.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 111, No. 5, pp. 454–456, May, 1991.     

Effect of prior exercise in Pi/PC ratio and intracellular pH during a standardized exercise. A study on human muscle using [31P]NMR

Seven subjects underwent a standard localized exercise of calf muscles in order to investigate whether the metabolic exercise-induced steady-state, as revealed by the evaluation of inorganic phosphate/phosphocreatine ratio, depends on the conditioning of the muscle just prior to the exercise. The experimental protocols consisted of two separate experiments using first [³¹P]nuclear magnetic resonance spectroscopy and second (on 3 subjects) infrared oxyphotometry to respectively follow variation of energy metabolism and tissular deoxygenation. The exercise consisted of 240 successive plantar flexions (0.5 Hz frequency) against a high load equivalent to SO% of the maximal voluntary contraction. This exercise was accomplished before cold exercise and after warm exercise, a warming-up period bringing to approximately 50% of Vo_2max. The results showed that: (1) steady-state level of phosphate/phosphocreatine and intracellular acidosis was significantly lowered by warming-up; (2) cold and warm exercise steady-state of calculated adenosine diphosphate values were not significantly different; (3) cold exercise rapidly induced a high tissular deoxygenation that is not observed during warm exercise; and (4) time-constant of phosphocreatine resynthesis is lowered after warm exercise but the initial slope of time-evolution is not modified. Parallel experiments also showed that phosphate/phosphocreatine steady-state was not modified in comparison with warm exercise when the same power of exercise was reached by stepwise incrementation of the charge. From these results we postulate that a better tissue oxygenation due to a global or localized warming-up allows to reach the same mechanical performance with a lower decrease of PCr content, owing to a faster adjustment of oxidative metabolism during the transitional period. However the aerobic pathway flux during the steady-state is probably the same before and after the warming-up despite different values of phosphate/phosphocreatine. As a consequence it can be assumed that this ratio is not a good indicator of the rate of muscle oxidative metabolism during the steady-state phase of the exercise.     

Preoperative metoprolol improves cardiovascular stability and reduces oxygen consumption after thoracotomy

Background : Increased sympathetic activity perioperatively and associated cardiovascular effects play a central role in cardiovascular complications. High thoracic epidural blockade attenuates the sympathetic response, but even with complete pain relief, haemodynamic and endocrine responses are still present. Beta–adrenoceptor blockade is effective in situations with increased sympathetic activity. This study was designed to evaluate the perioperative haemodynamic effect of preoperative βblockade and its influence on the haemodynamic aspects of the surgical stress response.
Methods : Thirty–six otherwise healthy patients undergoing elective thoracotomy for lung resection were randomised doubleblinded to receive either 100 mg metoprolol or placebo preoperatively. Anaesthesia was combined high thoracic epidural block and general anaesthesia. The epidural analgesia was continued during recovery. Patients were monitored with ECG, pulse oximetry, invasive haemodynamic monitoring, arterial blood gases and electrolytes.
Results : After induction of anaesthesia the mean arterial pressure (MAP) decreased in both groups, and decreased further in the placebo group after initiation of the epidural block. The heart rate (HR) was slightly less throughout the observation period after metoprolol. Peroperatively, the only difference in measured haemodynamics was a marginally higher MAP after metoprolol. Postoperative cardiac index (CI) was lower with a lower variability and cardiac filling pressures were slightly higher in the metoprolol group. The oxygen consumption index was higher after placebo throughout the observation period, with no difference in the oxygen delivery.
Conclusion. We found that preoperative β–blockade during combined general anaesthesia and high thoracic epidural blockade stabilised perioperative HR and CI and decreased total oxygen consumption.     

Acetylcholinesterase Adaptation to Voluntary Wheel Running is Proportional to the Volume of Activity in Fast, but not Slow, Rat Hindlimb Muscles

Chronic enhancement of neuromuscular activity by forced exercise training programmes results in selective adaptation of the G₄ acetylcholinesterase (AChE) molecular form in hindlimb fast muscles of the rat, with only minor and non-selective AChE changes in the soleus. In order to shed further light on the physiological significance of this G₄ adaptation to training, we turned to a voluntary exercise model. The impact of 5 days and 4 weeks of voluntary wheel cage running on AChE molecular forms was examined in four hindlimb fast muscles and the slow-twitch soleus from two rat strains. Inbred Fisher and Sprague– Dawley rats, placed in live-in wheel cages, exercised spontaneously for distances which progressively increased up to an average of ∼3 and 18 km/day, respectively, by the end of week 4. Fast muscles responded to this voluntary activity by massive G₄ increases (up to 420%) with almost no changes in A₁₂, so that by week 4 the tetramer became the main AChE component of these muscles. The additional G₄ was composed primarily of amphiphilic molecules, suggesting a membrane-bound state. The G₄ content of fast muscles was highly correlated with the distance covered by the rats during the 5 days before they were killed ( r = 0.850-0.879, P < 0.001 in three muscles). The soleus muscle, in turn, responded to wheel cage activity by a marked selective reduction of its asymmetric forms—up to 45% for A₁₂. This A₁₂ decline, already maximal by day 5 of wheel cage running, showed no relationship with the distance covered. The present results constitute strong new evidence suggesting that the role of AChE in neuromuscular transmission is not limited solely to the rapid inactivation of just-released acetylcholine.     

儿童边缘性锌缺乏症综合判断的研究

对沈阳市某幼儿园９９例３～６岁锌缺乏儿童的营养调查和生物样品（血液、尿液和毛发）的分析发现：同对照组儿童相比，锌缺乏儿童除Ｆｅ、维生素Ａ外，其他主要营养素的摄入明显不足；缺锌儿童的发锌、ＲＢＣ锌水平、血清ＡＬＰ活性、尿锌／尿肌酐比值均明显低于对照组。经补锌治疗后血浆锌水平、血清ＡＬＰ活性、尿锌／尿肌酐比值显著升高。应用临床诊断实验的评价方法分析发现结合血浆锌水平，联合使用发锌，血清ＡＬＰ和尿锌／尿肌酐比值３项指标可以准确判断儿童边缘性锌缺乏，这时并联的灵敏度为９６．１８％，串联的特异度可高达到１００％（血清ＡＬＰ活性＜１０４ＩＵ／Ｌ，同时发锌含量＜１１０ｐｐｍ．尿锌／尿肌酐比值＜０．３μｇ／ｇ）。     

Fractionation of a chalone-containing preparation from Ehrlich's ascites tumor by high performance liquid chromatography

Department of Biology, Medico-Biological Faculty, and Applied Research Laboratory of Ecology, Toxicology, and Metabolism of Medicinal Preparations, attached to the Department of Biochemistry, Medico-Biological Faculty, N. I. Pirogov Second Moscow Medical Institute. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 10, pp. 418–419, October, 1991.     

Low peripheral plasma renin activity as a critical marker in pediatric hypertension

In evaluating hypertensive children and adolescents, the etiological considerations should include a set of inherited disorders that share very low plasma renin activity (PRA) as a common feature. In particular among these disorders, glucocorticoid remediable aldosteronism (GRA) appears to be emerging as an important etiology of hypertension in the pediatric population. We report the evaluation of a 9-year-old Caucasian girl who presented with severe hypertension and a strong family history of early-onset hypertension. Her suppressed PRA, her family history, and her failure to respond to conventional antihypertensive therapy raised GRA as a potential etiology. The diagnosis was confirmed by an elevated ratio of urinary 18-oxotetrahydrocortisol to urinary tetrahydroaldosterone and genetic testing, which demonstrated the chimeric gene duplication. The molecular pathogenesis of GRA and the clinical implications are reviewed. Received May 15, 1996; received in revised form and accepted September 16, 1996     

复合酶中糖化酶活力的测定

复合糖化酶的酶活力检测是主要的质量控制指标,只有选用合理的糖化酶活力检测方法,才能真实反映出复合酶中糖化酶活力的高低.为避免因协同作用而产生的复合酶中其他酶制剂对糖化酶活力检测的干扰,作者总结了以往的研究成果,结合4种不同酶制剂的作用机理,最终否定了常用的淀粉底物法,确定了麦芽糖底物法为首选方法.     

参加社会活动和锻炼对冠心病并发抑郁的影响1

目的：研究参加社会活动和锻炼对新兴工业化农村社区冠心病患者并发抑郁的影响。方法：对114例在我院就医、属三角镇户籍常住人口的冠心病（CHD）患者进行Zung量表（SDS量表）检测，同时调查其经济状况、健康习惯、参加社会活动和锻炼情况等。用SPSS13．0版统计软件进行统计分析。结果：抑郁发生率37．7％，女性44．3％（27／61）高于男性30．2％（16／53）。70岁以上者47．6％（30／63）高于70岁以下者25．5％（13／51）。缺少社会活动（几乎不参加社会活动）、缺少锻炼（几乎不锻炼身体）都抑郁发生率高，可能是冠心病并发抑郁的独立预测因素。结论：适度参加社会活动和锻炼对CHD患者并发抑郁可能有预防作用。