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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,153 records · Page 64
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Recovery of skeletal muscle after 3 mo of hindlimb immobilization in rats

During immobilization, skeletal muscle undergoes decreases in size and strength with concomitant atrophic and degenerative changes in slow-twitch muscle fibers. Currently there are no objective data in slow-twitch muscle demonstrating recovery of biochemical or physiological indices following termination of immobilization. The purpose of this study was to determine whether the soleus, a slow-twitch muscle, could recover normal biochemical or physiological levels following termination of immobilization. Adenosine triphosphate, glycogen, and protein concentration (mg/g wet wt) all significantly decreased following 90 days of hindlimb immobilization, but these three values returned to control levels by the 60th recovery day. Similarly, soleus muscle wet weight and protein content (mg protein/muscle) returned to control levels by the 14th recovery day. In contrast, maximal isometric tension did not return to normal until the 120th day. These results indicate that following muscular atrophy, which was achieved through 90 days of hindlimb immobilization, several biochemical and physiological values in skeletal muscle are recovered at various times after the end of immobilization.

Booth, F. W.↗
NASA NTRS1980

Effect of the enzymatic inhibitor of Kunitz on the gastric lesions from reserpine, from phenylbutazone, from pyloric ligation and by restraint in the rat

The protective effects of certain polypeptides on gastric ulcerations caused from reserpine and phenylbutazone in the rate were studied. It was found that the Kunitz enzymatic inhibitor exerts a protective action in regard to gastric lesions. However, the inhibitor did not change the development of Shay ulcers and stress ulcers from restraint.

Guerrin, F.↗
NASA NTRS1980

Role of adrenals in the mobilization of carbohydrate and fat resources after overstimulation of rats

The role of the cortical and cerebral layers of the adrenal glands in mobilizing carbohydrate and fatty resources in response to the effect of an extreme stimulant was investigated. It is shown that following adrenodemedullation and adrenalectomy, the leading role is played by the secretion of the adrenal medullary layer, whereas the role of suprarenals in the mobilization of fats is only slightly pronounced.

Khechninashvili, G. G.↗
NASA NTRS1981

Experiment K305: Quantitative analysis of selected bone parameters. Supplement 1: Effects of weightlessness on osteoblast differentiation in rat molar periodontium

The morphometric analysis of periodontal ligament (PDL), the osteogenic interface between tooth and bone, is described. Immediately post-flight, PDL width and total cell number were decreased. Frequency distributions of nuclear volume revealed that presumptive preosteoblasts were particularly depressed. Depleted numbers of preosteoblasts may be an important factor in the mechanism of inhibited bone formation during weightlessness.

Roberts, W. E.↗
NASA NTRS1982

Effect of prolonged hypokinesia on resistance of resistive vessels in rats

Under the effect of prolonged hypokinesia, the perfusion pressure in resistive vessels, measured under conditions of deep anesthesia and complete denervation, increased by approximately the same degree as arterial pressure in non-anesthetized animals. The increase in arterial, perfusion pressure and the resistance of resistive vessels in animals subjected to prolonged hypokinesia was accompanied by an increase in adrenoreactivity. During prolonged hypokinesia, partial obliteration of the vascular bed of the skeletal muscles plays a significant role in the observed increase in resistance of vessels of the extremities. The increase in adrenoreactivity of the vessels during hypokinesia may be realized as a partial case of an increase in the adrenoreactivity of structures whose innervation is disturbed.

Saltykova, V. A.↗
NASA NTRS1981

Microdisc gel electrophoresis in sodium dodecyl sulfate of organic material from rat otoconial complexes

The gravity receptors of all vertebrates utilize a 'test mass' consisting of a complex arrangement of mineral and organic substance that lies over the sensory receptor areas. In most vertebrates, the mineral is a polymorph of calcium carbonate in the form of minute, single crystals called otoconia. An investigation is conducted to determine the number of proteins in otoconial complexes and their molecular weights. The investigation makes use of a microdisk gel electrophoresis method reported by Gainer (1971). The most important finding of the reported research is that analysis of the proteins of the organic material of the otoconial complexes is possible when sensitive microanalytical methods are employed. Further modification of the basic technique employed and the inclusion of other sensitive staining methods should mean that, in the future, protein separation by molecular weight will be possible in sample pools containing only two otoconial masses.

Ross, M. D.↗
NASA NTRS1982

Effects of hypergravity on rat liver regeneration

The effects of centrifugation on liver regrowth were examined by measuring mitotic activity. The results indicate that the increased gravity caused a delay in the onset of mitotic activity and a significant decrease in overall mitotic activity.

Feller, D. D.↗