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991.
992.
Gelation of Proteins from Washed Muscle of Threadfin Bream (Nemipterus japonicus) under Mild Acidic Conditions 总被引:7,自引:0,他引:7
Gelation of proteins of washed mince of threadfin bream was induced by the organic acids: acetic, lactic, tartaric, and citric. Washing of mince was essential for gelation. The strength of acetic acid-induced gel was affected by setting conditions and heat treatment. Gelation was associated with degradation of myosin heavy chain and appearance of a new protein band of about 160 kDa. Solubility studies of the gel in various solvents suggested structural changes. Gelation was also associated with oxidation of sulfhydryl groups. Salts negatively influenced gelation. 相似文献
993.
31P saturation-transfer nuclear magnetic resonance spectroscopy was used to study skeletal muscle phosphocreatine (PCr) flux
in healthy male volunteers. Data analysis included consideration of effects from incomplete saturation and radiofrequency
spillover. Spectra were recorded from the resting gastrocnemius muscle before and after 6 days of creatine monohydrate (Cr·H2O) intake (20 g/day). Parallel to an improved muscle performance during maximal intermittent exercise following Cr·H2O supplementation, the concentration of PCr increased(P = 0.01) by 23% (34.9 ± 2.8 mmol/ 1 vs. 28.6 + 2.7 mmol/1), whereas other metabolites were unaffected (inorganic phosphate:
4.3± 1.4 mmol/1, free intracellular Mg2+: 1.1 ±0.7 mmol 1, cytosolic pH: 7.04 ± 0.02). Forward and reverse fluxes through the creatine kinase (CK) reaction did not
change significantly from their baseline levels (vfor: 11.8 ± 5.4 mmol/1 per second vs. 15.3 ± 6.8 mmol 1 per second. (vrev: 9.5 ± 3.4 mmol/1 per second vs. 10.9 ± 3.7 mmol/ 1 per second). The rate of PCr resynthesis in resting muscle is not limited
by the CK reaction, which is near equilibrium. Consequently, the post-load increase in total creatine has no effect on the
unidirectional CK reaction rates. 相似文献
994.
Interaction of rat tumor cells with blood vessels and lymphatics of the avian chorioallantoic membrane 总被引:6,自引:0,他引:6
It has generally been assumed that tumors do not induce lymphangiogenesis and only very recently animal models have been presented showing tumor-induced lymphangiogenesis. We have grown two types of rat tumor cells, 10AS pancreatic carcinoma and C6 glioma cells, on the chorioallantoic membrane (CAM) of chick and quail embryos. The suspended tumor cells rapidly formed solid tumors which invaded the CAM and were vascularized by CAM vessels. When grown on the CAM of quail embryos intratumoral endothelial cells could be specifically stained with the QH1 antibody. In C6 gliomas the vascular pattern was more regular than in 10AS carcinomas. The vessels often grew radially into the glioma and many of them were invested by smooth muscle alpha-actin-positive periendothelial cells. Lymphatics, which were identified by vascular endothelial growth factor receptor-3 (VEGFR-3) in situ hybridization were absent from C6 gliomas, although a weak expression of the lymphangiogenic growth factor, VEGF-C, could be detected in the C6 cells by Northern blot analysis. In contrast, 10AS cells, which expressed high levels of VEGF-C, induced ingrowth of lymphatics into the tumors, with BrdU-labeling rates of about 9% of lymphatic endothelial cells. Our studies demonstrate the heterogeneity of interactions of tumor cells with blood vessels and lymphatics and show that sufficient quantities and/or quality of lymphangiogenic growth factors are crucial for the induction of lymphatics in tumors. 相似文献
995.
The superb ability of animals to negotiate rough terrain has caused engineers to focus on mechanical properties of muscle and other unique features in order to design improved robots for exploration. This paper reviews recent work in artificial muscle actuators, as well as a new sensor based on a robotic model of the muscle spindle cell. The actuator contains a pneumatic force generator in parallel with a non-linear damping element and in series with a non-linear elastic tendon. Work loop experiments were performed to characterize this actuator under conditions similar to real locomotion at different speeds. The robotic muscle spindle is an 8 × 1 cm device which simulates the response of the physiological muscle spindle to stretch. Its non-linear properties are thought to contribute to stable accurate control over a wide range of motion. 相似文献
996.
为实现仿真手在运动过程中符合人手的生理特性及运动特点,文中通过分析手的解剖结构,总结控制手部运动和形状的约束参数.采用层次建模方法,先建立用线段表示的含有约束参数的手部骨骼模型,然后在此基础上根据手部的特征横截面确定特征多边形,采用NURBS面片拟合的方法建立依附于骨骼之上的肌肉模型。此方法建立的手部模型在运动仿真过程中,手部肌肉以对应的骨骼为轴线并随着骨骼各个参数的变化而发生相应的变化,最终取得良好的仿真效果。 相似文献
997.
H. Wackerhage K. Mueller U. Hoffmann D. Leyk D. Essfeld J. Zange 《Magma (New York, N.Y.)》1996,4(3-4):151-155
In an oxygen-depleted muscle, glycolytically produced ATP is inversely related to the ([ATP] + creatine phosphate [PCr]) decrease because ATP, PCr, and glycolysis are virtually the only energy sources under these conditions. In particular, the onset of glycolysis or any appreciable increase in the rate of glycolytic ATP production will lead to a slower rate of ([ATP] + [PCr]) breakdown at a given energy consumption. To quantify this relationship, endurance athletes performed isometric foot plantar flexion (20% of a test force [TF],n=10; 50% TF,n=5) during local arterial occlusion. Parameters of energy metabolism were measured with31P magnetic resonance spectroscopy (31P-MRS). During exercise, [PCr] decreased to 80±10 (20% TF) and 11±4% (50% TF) of its resting concentration, and pH dropped from 7.04 0.01 to 6.98±0.10 (20% TF) and from 7.03±0.02 to 6.70 0.10 (50% TF). In both experiments, two phases of ([ATP] + [PCr]) decrease were observed: an initial faster decrease was followed by a slower decline. The latter phase started at about the time when the pH began to drop. The difference between a line extrapolated from the slope of the initial phase and the measured ([ATP] + [PCr]) decrease was used as an estimate for glycolytically produced ATP. This estimate and pH were significantly correlated withr=–0.97 (20% TF) andr=–0.99 (50% TF). These results indicate that glycolytically produced ATP can be estimated from the ([ATP] + [PCr]) decrease during exercise. 相似文献
998.
Kimmo T. Mattila Markku Komu Reima Karsikas Pasi Hatakka Olli J. Heinonen Martti Kormano 《Magma (New York, N.Y.)》1996,4(2):115-122
In the present study we introduce a new device for exercise magnetic resonance spectroscopy (MRS). It operates in a standard whole-body scanner. Mechanical exertion unit allows maximal 10° to 15° short-arc knee extensions. The device operates hydraulically and is based on isokinetic movement. The force and work conducted are automatically controlled by the electronic control and computer unit. A small surface coil placed on the vastus medialis muscle allows the collection of spectra without interfering spectra from nearby resting muscles. The force used for the extensions can be followed simultaneously as a curve on the screen in the operator's room and the data is transferred to a personal computer for later analysis. Total work and fatigue percentage are also calculated by the device. It also allows the use of different isokinetic exercise protocols. The measurements of force proved reliable in repeat measurements using an isokinetic test device as a control.This device has been used clinically for over a year, is easy to operate, and offers reliable measurements. It is well suited to trials where muscle energy states versus time are followed since it allows noninvasive simultaneous quantification of muscle performance and collecting MRS spectra at rest, during exercise, and in the recovery phase. 相似文献
999.
基于尺蠖的移动机理,研制了一种具有柔性移动机构的微小气动机器人内窥镜诊疗系统。描述了微机器人系统的本体结构和运动机理,并通过分析机器人系统的驱动力学特性和机器人的移动控制特性,给出了基于模糊自适应PID的气压-位置伺服控制方法,计算机仿真实验结果表明基于模糊自适应PID算法可实现机器人系统的有效控制。 相似文献
1000.