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排序方式: 共有259条查询结果,搜索用时 15 毫秒
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Work capacity during 30 days of bed rest with isotonic and isokinetic exercise training 总被引:4,自引:0,他引:4
Greenleaf J. E.; Bernauer E. M.; Ertl A. C.; Trowbridge T. S.; Wade C. E. 《Journal of applied physiology》1989,67(5):1820-1826
The purpose was to test the hypothesis that twice daily, short-term, variable intensity isotonic and intermittent high-intensity isokinetic leg exercise would maintain peak O2 uptake (VO2) and muscular strength and endurance, respectively, at or near ambulatory control levels during 30 days of -6 degrees head-down bed rest (BR) deconditioning. Nineteen men (aged 32-42 yr) were divided into no exercise control (peak VO2 once/wk, n = 5), isokinetic (Lido ergometer, n = 7), and isotonic (Quinton ergometer, n = 7) groups. Exercise training was conducted in the supine position for two 30-min periods/day for 5 days/wk. Isotonic training was at 60-90% of peak VO2, and isokinetic training (knee flexion-extension) was at 100 degrees/s. Mean (+/- SE) changes (P less than 0.05) in peak VO2 (ml.m-1.kg-1) from ambulatory control to BR day 28 were 44 +/- 4 to 36 +/- 3, -18.2% (3.27-2.60 l/m) for no exercise, 39 +/- 4 to 40 +/- 3, +2.6% (3.13-3.14 l/min) for isotonic, and 44 +/- 3 to 40 +/- 2, -9.1% (3.24-2.90 l/min) for isokinetic. There were no significant changes in any groups in leg peak torque (right knee flexion or extension), leg mean total work, arm total peak torque, or arm mean total work. Mean energy costs for the isotonic and isokinetic exercise training were 446 kcal/h (18.8 +/- 1.6 ml.min-1.kg-1) and 214 kcal/h (8.9 +/- 0.5 ml.m-1.kg-1), respectively. Thus near-peak, variable intensity, isotonic leg exercise maintains peak VO2 during 30 days of BR, while this peak, intermittent, isokinetic leg exercise protocol does not. 相似文献
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Louis Faso Richard S. Trowbridge Wei Quan Xiu-Lan Yao Edmund C. Jenkins Alma Maciulis Thomas D. Bunch Henry M. Wisniewski 《In vitro cellular & developmental biology. Animal》1994,30(4):226-235
Summary A strain of cerebral endothelial cells was established from isolated cortical microvessels of caprine brain. These cells,
which are referred to as ECl cells, can be routinely subcultured to 32 passages without the loss of differentiated morphologic
and immunologic traits. The ability to routinely subculture ECl cells is an important asset, given that isolated cerebral
endothelial cells in mammals generally lose their differentiated traits after only 2 to 3 passages.
ECl cells were shown to contain Factor VIII-related antigen, which is a specific marker for cells of endothelial origin. ECl
cells morphologically demonstrated a scarcity of pinocytotic vesicles on their apical surfaces, a lack of trans-cytoplasmic
vesicles, and the ability to form in culture confluent monolayers with tight junctional complexes. Therefore, ECl cells possess
specific antigenic and ultrastructural features which classify them as being small vessel endothelial cells of the blood-brain
barrier type. Cytogenetic evaluation of ECl cells demonstrated a normal female goat 60,XX karyotype and confirmed the apparent
non-transformed nature of ECl cells due to the lack of chromosome abnormalities or rearrangements. Using scanning electron
microscopy, ECl cells were also shown to form confluent monolayers on mixed nitrocellulose filters, a feature that will enable
the development of an in vitro system to study trans-endothelial transport. Given that ECl cells are readily subcultured and
grow well on nitrocellulose filters, and that they resemble cerebral endothelium in vivo, it seems evident that ECl cells
can be used as a versatile model for the study of blood-brain barrier function, regulation, and pathology. 相似文献
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C Crone J Frokjaer-Jensen JJ Friedman O Christensen 《The Journal of general physiology》1978,71(2):195-220