Relationship between frequency and amplitude of myocardial contractions in rats adapted to heat

After preliminary adaptation of rats to heat (for 3 h daily at 35°C for 1 month) the amplitude of contractions of the isolated papillary muscles from the left ventricle at 28°C at high frequency was higher than in control animals. This difference persisted at 36°C and disappeared at 25°C. It is postulated that adaptation to heat leaves a definite structural imprint in heart muscle cells.Laboratory of Pathophysiology of the Heart, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. Institute of Physiology and Experimental Pathology of the Arid Zone, Academy of Sciences of the Turkmenian USSR, Ashkhabad. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 10, pp. 1168–1170, October, 1976.     

样本量对等位基因检出数量的影响

以中国37个不同民族9个常染色体STR基因座的群体遗传研究数据资料为例，探讨群体遗传学研究中常染色体STR基因座等位基因检出数量与样本量之间的关系，即样本量对等住基因检出数量的影响。结果显示在一定范围之内，样本量的大小与所观测到的不同基因座等位基因检出数量之间存在正相关关系。当超过一定范围时，样本量的继续增加不再明显影响等位基因的检出数量。杂合度较低的位点随样本量的变化波动较大，杂合度较高的位点随样本量的变化波动较小。     

我院2004年～2006年6月抗感染药物应用分析

目的 了解我院2004年～2006年6月抗感染药物的应用情况，分析抗感染药物使用的特点和趋势。为其合理应用和科学管理提供依据。方法 对我院2004年～2006年6月抗感染药的销售金额排序。并采用WHO药物统计合作中心设定的限定日剂量（defined daily dose，DDD）方法计算我院抗茵药物的用药频度。结果 我院临床较常用的抗感染药物为头孢菌素类、青霉素类、大环内酯类、喹诺酮类；2004年～2006年6月我院抗感染药物消耗金额，在年度药品消耗总金额中，都排在临床用药第1位：但比例逐年下降；大部分抗感染药物日均费用逐年递减。结论 2004年-2006年6月我院抗感染药物使用基本合理．新上市的抗感染药物以及药品价格昂贵的抗感染药物使用较少。     

Skeletal muscle contractility is preserved in COPD patients with normal fat‐free mass

Aim: Peripheral muscle dysfunction often occurs in patients with chronic obstructive pulmonary disease (COPD). The muscle dysfunction may be caused by a loss of force‐generating capacity, resulting from a loss of muscle mass, as well as by other alterations in contractile properties of skeletal muscle. Methods: The maximal isometric voluntary strength and fatigability were determined in hand‐grip and quadriceps muscles from nine male COPD patients (FEV₁ 30–50% predicted) and control subjects matched for fat‐free mass (FFM), physical activity level and age. Contractile properties and fatigability of the quadriceps muscle were also studied with electrically evoked isometric contractions. Results: The maximal voluntary force (MVC) and fatigability of the handgrip muscle did not differ between the COPD patients and control subjects. Also the MVC of the quadriceps muscle and the rate of force rise, contraction time, force–frequency relationship and fatigability, as determined with electrically evoked contractions, were similar in patients with COPD and control subjects. Conclusion: Skeletal muscle strength, contractile properties and fatigability are preserved in patients with moderate COPD and a normal FFM and activity level. This suggests that skeletal muscle dysfunction does not take place during moderate COPD until cachexia and/or a decline in physical activity occur.     

高频电刀对家兔活体肌肉组织的作用

目的 :探讨高频电刀对肌肉组织结构的作用。方法 :用高频电极在不同输出功率时测定大白家兔活体肌肉组织的电流强度 ,灼伤中心区汽化深度和汽化表面积 ,光镜和电镜下观察创面下 0～ 6mm深度的组织结构变化。结果 :随着电流输出功率的增强 ,肌肉组织的电流强度 ,中心区汽化深度和汽化表面积也随之增加 ,创面深部组织显微和超微结构发生了热凝固性改变 ,损伤程度随着离中心区距离的延长而减弱 ,但在 6mm深处仍有较明显的损伤性改变。结论 :用高频电刀操作时应注意对深部肌肉组织的损伤性作用 ,为减少损伤应注意操作时的电流强度和电灼时间。     

Relationship between shock attenuation and stride length during running at different velocities

The purpose of the study was to investigate the characteristics of shock attenuation during high-speed running. Maximal running speed was identified for each subject [n=8 males, 25 (SD 4.6) years; 80 (8.9) kg; 1.79 (0.06) m] as the highest speed that could be sustained for about 20 s on a treadmill. During testing, light-weight accelerometers were securely mounted to the surface of the distal antero-medial aspect of the leg and frontal aspect of the forehead. Subjects completed running conditions of 50, 60, 70, 80, 90, and 100% of their maximal speeds with each condition lasting about 20 s. Stride length, stride frequency, leg and head peak impact acceleration were recorded from the acceleration profiles. Shock attenuation was analyzed by extracting specific sections of the acceleration profiles and calculating the ratio of head to leg power spectral densities across the 10–20 Hz frequency range. Both stride length and stride frequency increased across speeds (P<0.05) and were correlated with running speed (stride length r=0.92, stride frequency r=0.89). Shock attenuation increased about 20% per m·s^–1 across speeds (P<0.05), which was similar to the 17% increase in stride length per m·s^–1. Additionally, shock attenuation was correlated with stride length (r=0.71) but only moderately correlated with stride frequency (r=0.40) across speeds. It was concluded that shock attenuation increased linearly with running speed and running kinematic changes were characterized primarily by stride length changes. Furthermore, the change in shock attenuation was due to increased leg not head peak impact acceleration across running speeds. Electronic Publication     

THE EFFECTS OF CHANGES IN AROUSAL LEVEL ON CRITICAL FLICKER FUSION FREQUENCY AND FIGURAL REVERSAL TASKS

The present study was designed to investigate the relationship between intra-and inter-individual differences in arousal level and performance on both critical flicker fusion frequency and figural reversal tasks. Forty male undergraduate Ss were used. Electrical skin conductance was used as the indicant of arousal level. For the intra-individual comparisons white noise was used to increase the Ss’arousal levels. Significant inverted U-shaped relationships were found between both flicker fusion thresholds and rates of figural reversal and skin conductance between individuals. A significant curvilinear relationship was found between rates of figural reversal and level of conductance within individuals. No significant curvilinear relationship was found between flicker fusion thresholds and level of conductance within individuals.     

A role for glucose and insulin preprandial profiles to differentiate meals and snacks

A physiological distinction between eating occasions may help account for contradictory findings on the role of eating frequency in energy homeostasis. We assessed this issue using a midafternoon eating occasion known in France as the goûter that often consists of snack foods. Among the 24 male subjects, 8 habitually consumed four meals per day, i.e., were usual goûter eaters (GE) and 16 habitually took 3 meals per day, i.e., usual non-goûter non-snack eaters (NGNSE). All subjects were time blinded from lunchtime and had to request subsequent meals. Blood was continuously withdrawn and collected with a change of tube every 10 min until dinner request. During the session, 8 of the non-goûter eaters (NGE) were offered a snack 210 min after lunch and were designated as non-goûter snack eaters (NGSE) if they ate. Results showed that the goûter was preceded by high hunger scores and a linear decline in plasma glucose (−9.0±3.0%, P<.05) and insulin concentrations (−22.9±6.0%, P<.05). These profiles were not observed before the snack. The dinner of GE was requested later and was smaller compared to NGNSE, whereas the snack altered neither time of request nor energy intake (EI) at dinner. Among blood variables, leptin at the onset of eating was the only factor that was predictive of both intermeal interval and EI. The glucose and insulin profiles indicate that snacks should not be considered as meals in studies on the role of eating frequency in energy homeostasis.     

Interpretation of skeletal muscle four-electrode impedance measurements using spatial and temporal frequency-dependent conductivities

Spatial and temporal frequency-dependent conductivities are used to interpret four-electrode conductivity measurements on skeletal muscle. The model qualitatively explains the observed dependence of the experimental data on the temporal frequency of the injected current, the angle between the electrode array and the fibre direction and the distance between the electrodes.     

Optimum cycle frequencies in hand-rim wheelchair propulsion

Summary To study the effect of different cycle frequencies on cardio-respiratory responses and propulsion technique in hand-rim wheelchair propulsion, experienced wheelchair sportsmen (WS group; n=6) and non-wheel chair users (NW group; n=6) performed wheelchair exercise tests on a motor-driven treadmill. The WS group wheeled at velocities of 0.55, 0.83, 1.11 and 1.39 m · s^–1 and a slope of 2°. The NW group wheeled at 0.83, 1.11 and 1.39 m · s^–1 and a 1° slope. In each test, a 3-min period at a freely chosen cycle frequency (FCF: 100%) was followed by four 3-min blocks of paced cycle frequencies at 60%, 80%, 120% and 140% FCF. Effects of both cycle frequency and velocity on physiological and propulsion technique parameters were studied.Analysis of variance showed a significant effect (p<0.05) of cycle frequency on oxygen cost and gross mechanical efficiency in both the WS and NW group. This indicated the existence of an optimum cycle frequency which is close to the FCF at any given velocity. The optimum cycle frequency increased with velocity from 0.67 to 1.03 cps over the range studied (p< 0.05). Oxygen cost was 10% less at 100% FCF than at 60% or 140% FCF. Gross mechanical efficiency for the WS group at 100% FCF was 8.5%, 9.7%, 10.4% and 10.1%, respectively, at the four velocities. The similarity in the trend of oxygen cost and gross mechanical efficiency data in both the WS and NW groups suggests that an optimum cycle frequency is not merely a consequence of practice alone, but also reflects a physiologically determined optimum, dependent on muscle mechanics, e.g. velocity of contraction and power output of the muscles used.