The leveling-off of oxygen uptake is related to blood lactate accumulation. Retrospective study of 94 elite rowers

To assess whether the ability to demonstrate a plateau in oxygen consumption VO2 could be related to adaptation to exercise, the data obtained over a period of 10 years on 94 elite oarsmen who had participated in annual testing were re-evaluated. The test consisted in an incremental step protocol until volitional exhaustion. VO2, heart rate (HR), blood lactate ([La]b) and respiratory exchange ratio (RER) were measured at each step. The maximal oxygen consumption (VO2max), the power corresponding to VO2maxPamax and the maximal power achieved (Ppeak) were recorded. Thirty-eight oarsmen achieved a VO2 plateau and were designated as Pla; 56 did not and were designed as N-Pla. The Pla and N-Pla VO2max, Pamax and maximal HR values were similar. In comparison with N-Pla, the Pla group displayed a rightward shift of the [La]b versus power curve, accounted for by both the increased percentage of VO2max corresponding to 4 mmol l(-1) and the decreased value of [La]b corresponding to Pamax (P<0.05). Pla oarsmen attained a higher Ppeak expressed as % of Pamax (P<0.05) and also showed better ergometer performance (P<0.05). In a sub-group of 53 oarsmen constituted on the basis of Pamax values close to 400 W, for a given power output, the Pla subjects had significantly lower HR, RER, and [La]b values at each sub-maximal stage of the test. These results suggest that achieving a [Formula: see text] plateau during completion of an incremental step protocol accounts for greater muscle ability to maintain homeostasis during exercise. These differences give the oarsmen an advantage in rowing competitions.     

Effect of prior heavy exercise on muscle deoxygenation kinetics at the onset of subsequent heavy exercise

This study examines the effect of prior heavy exercise on muscle deoxygenation kinetics at the onset of heavy-intensity cycling exercise. Ten young male adults (20 +/- 2 years) performed two repetitions of step transitions (6 min) from 35 W to heavy-intensity exercise preceded by either no warm-up or by a heavy-intensity exercise. VO2 was measured breath-by-breath, and muscle deoxygenation (HHb) and total hemoglobin (Hb(tot)) were monitored continuously by near-infrared spectroscopy. We used a two-exponential model to describe the VO2 kinetics and a mono-exponential model for the HHb kinetic. The parameters of the phase II VO2 kinetics (TD1 VO2, tau1 VO2 and A1 VO2) were unaffected by prior heavy exercise, while some parameters of local muscle deoxygenation kinetics were significantly faster (TD HHb: 7 +/- 2 vs. 5 +/- 2 s; P < 0.001, MRT HHb: 20 +/- 3 vs. 15+/- 4 s; P < 0.05). Blood lactate, heart rate and Hb(tot) values were significantly higher before the second bout of heavy exercise. These results collectively suggest that the prior heavy exercise probably increased muscle O2 availability and improved O2 utilization at the onset of a subsequent bout of heavy exercise.     

Two new monoterpenoid glycosides from Mentha spicata L.

Two new monoterpenoid glycosides, spicatoside A and spicatoside B, were isolated from the whole herbs of Mentha spicata L. which have anti-inflammatory and hemostatic activities. Their structures have been determined on the basis of spectral and chemical analysis. They are (+)-5-[1-(g -D-glucopyranosyloxymethyl)ethenyl]-2-methyl-2-cyclohexen-1-one (1), and (m )-5-{[2-( g -D-glucopyranosyloxy)-1-hydroxy-1-methyl]ethyl}-2-methyl-2-cyclohexen-1-one (2).     

新化合物TG-6对大鼠心肌缺血-再灌注损伤的保护作用

目的 探讨新化合物3-硝基-4-{[4-(2,3,4-三甲氧基苯基)哌嗪-1-基]甲基}-苯甲酰基胍(TG-6)对大鼠心肌缺血-再灌注(I-R)损伤的保护作用.方法 结扎大鼠冠状动脉左前降支40 min,再灌注120 min建立心肌I-R损伤模型.48只大鼠分为A组(假手术组)、B组(I-R模型组)、C组(模型组+卡立泊来德1 mg/kg)、D组(模型组+TG-61 mg/kg)、E组(模型组+TG-60.5 mg/kg)、F组(模型组+TG-60.25 mg/kg),每组8只.观察TG-6对大鼠心功能学、心肌梗死面积及血清生化指标的影响.结果 与B组比较,D、E、F组左心室内压最大上升与下降速率(±dP/dtmax)、血清超氧化物歧化酶(SOD)活力增高,左心室舒张末期压力(LVEDP)、血清肌酸激酶(CK)活力、乳酸脱氢酶(LDH)活力、丙二醛(MDA)含量降低(P＜0.05);D、E组心率、左心室内压(LVSP)增加,心肌梗死面积缩小(P＜0.05).结论 TG-6明显减轻大鼠心肌I-R损伤,有望成为治疗心肌I-R损伤新型药物.     

Therapeutic effects of SMND-309, a new metabolite of salvianolic acid B, on experimental liver fibrosis

(2E)-2-{6-[(E)-2-carboxylvinyl]-2,3-dihydroxyphenyl}-3-(3,4-dihydroxyphenyl) propenoic acid, a novel compound designated SMND-309, is a new metabolite of salvianolic acid B. The present study was carried out to investigate the effects of SMND-309 on experimental liver fibrosis in rats induced by subcutaneous injection of carbon tetrachloride and explore its possible mechanisms on the basis of biochemical, histopathologic and immunohistochemical studies. The results showed that intragastrical treatment with SMND-309 ameliorated liver function and decreased the elevation of serum hyaluronic acid, laminin, procollagen type III levels and hydroxyproline content in liver tissue. It also decreased the elevation in the malondialdehyde level and restored the decrease in superoxide dismutase and glutathione peroxidase activities. Upon histopathologic examination, the SMND-309-treated rats reduced the liver damage and the liver fibrosis grade. Moreover, the results of immunohistochemical examination showed that SMND-309 powerfully down-regulated the expression of connective tissue growth factor (CTGF) rather than transforming growth factor-beta1 (TGF-β1) in serum and liver. Meanwhile, SMND-309 exhibits significantly higher potency compared with salvianolic acid B (Sal B) at the same dose. The antifibrotic mechanisms of SMND-309 might be associated with its ability to suppress the expression of CTGF as well as scavenge lipid peroxidation products and increase endogenous antioxidant enzyme activity.     

同时测定蔬菜中的49种农药残留量的气相色谱／三重四极杆质谱法

目的建立一种同时测定蔬菜中49种农药残留量的固相萃取气相色谱一三重四极杆质谱（GC—MS／MS）的方法。方法样品经乙腈提取,43℃水浴中旋转蒸发近干,固相萃取小柱净化,样品液氮吹浓缩后,用气相色谱GC—MS／MS法测定,外标法定量。结果49种农药在36min内完全分离,在0．01—10μg／ml范围内相关系数,。均在0．99以上,加标回收率在71．60％-109．3％之间,相对标准偏差均小于12％,定性检出限为0．001～0．006μg／ml。结论该方法操作简单,准确度和精密度高,适用于各种蔬菜中农药多残留量的检测和确证。     

A computer model of human ventricular myocardium for simulation of ECG,MCG, and activation sequence including reentry rhythms

Summary A computer model is presented for simulation of the spread of activation and repolarization in ventricular myocardium. The program calculating the activation sequence is based on an algorithm similar to Huygen’s principle of constructing wavefronts. Physiological parameters of the heart, such as areas of early activation on the endocardium, conduction velocity, anisotropy of propagation, duration of action potentials and refractory periods are taken into account. The time-course of ECG and MCG is calculated using the equations of the bidomain model. Simulation of pathologic cases of activation is performed through variation of the physiological heart parameters. The simulations presented here show good agreement of ECG and MCG with measurements in the normal case, the case of bundle branch block and abnormal repolarization. A special feature of the model is the possibility of simulating reentry rhythms following a premature stimulus in ventricular myocardium. Two kinds of reentry are simulated: reentry around an anatomical obstacle and the leading-circle model. The widespread capability for investigating not only ECG but also MCG and various kinds of pathologic activation patterns including reentry rhythms indicates that the model may be useful in studying numerous problems in cardiologic research.     

面颊缺损分类及修复方法选择（附223例报告）

面颊缺损的修复历史悠久、方法很多、效果不一,尚缺公认的最佳方案,原因是面颊缺损的范围、形状具有多样性,又缺乏明确分类。作者总结1964～1090年223例,根据面颊缺损范围及程度提出Ⅴ类分类法,并与之相联系的5种修复方法,总成功率92.83％。讨论了不同类型缺损的特点、手术适应证及修复方法的选择。认为这Ⅴ类5法便于对面颊缺损的统一认识,便于适应证、修复方法的选择和治疗效果的对比评价。     

Bidimensional passive and active mechanical behavior of rat tail artery segments in vitro

Summary The arterial wall mainly contains elastin, collagen, and smooth muscle arranged in concentric layers that are interconnected. Because of their interrelated architecture, circumferential and longitudinal deformations affect each other. Therefore, to develop a complete picture of arterial mechanics, whole vessel segments have to be studied under bidimensional states of deformation. The purpose of this study is to examine the passive and active mechanical behavior of intact segments of rat tail arteries subjected in vitro to various levels of pressures and longitudinal loads. Using photographic methods of deformation measurement, diameter and length of the segments were analyzed as a function of pressure and of longitudinal force under passive and active smooth muscle conditions. The passive pressure-diameter relationship shows maximum compliance around 6.6 kPa for all longitudinal loads investigated, while maximal contraction occurs at 13.3 kPa under in vivo longitudinal loads. The segment length increases with pressure at small longitudinal loads not only under passive, but even more markedly so under active smooth muscle conditions. On the other hand, at large longitudinal forces the artery length decreases on pressurization, both under passive as well as under active states of the smooth muscle. For the particular range of longitudinal loads corresponding to the individual prestretches found in situ, the length of the vessel segment not only remains constant with pressure, but also remains the same in magnitude, both under passive and active smooth muscle conditions.