ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295375

出版商:Wiley    

年代:1990

数据来源: WILEY

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2403951

出版商:Wiley    

年代:1990

数据来源: WILEY

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2403949

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Light microscopy, electron microscopy, and enzyme histochemistry were used to study the effects of spaceflight on metaphyseal and cortical bone of the rat tibia. Cortical cross‐sectional area and perimeter were not altered by a 12.5‐day spaceflight in 3‐month‐old male rats. The endosteal osteoblast population and the vasculature near the periosteal surface in flight rats compared with ground controls showed more pronounced changes in cortical bone than in metaphyseal bone. The osteoblasts demonstrated greater numbers of transitional Golgi vesicles, possibly caused by a decreased cellular metabolic energy source, but no difference in the large Golgi saccules or the cell membrane‐associated alkaline phosphatase activity. The periosteal vasculature in the diaphysis of flight rats often showed lipid accumulations within the lumen of the vessels, occasional degeneration of the vascular wall, and degeneration of osteocytes adjacent to vessels containing intraluminal deposits. These changes were not found in the metaphyseal region of flight animals. The focal vascular changes may be due to ischemia of bone or a developing fragility of the vessel walls as a result of spaceflight.—Doty, S. B., Morey‐Holton, E. R., Durnova, G. N.,andKaplansky, A. S. Cosmos 1887: morphology, histochemistry, and vasculature of the growing rat tibia.FASEB J.4: 16‐23; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2153083

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

The influence of 12.5 days of spaceflight and a 55 h stressful recovery period (at 1g) on fibroblastlike osteoblast precursor cells was assessed in the periodontal ligament (PDL) of rats that were 91 days old at launch. Nuclear morphometry was used as a marker for precursor cell differentiation in 3 μm sections cut in the midsagittal plane from the maxillary first molar. According to nuclear volume, cells were classified as pre‐osteoblasts (C + D cells, ≥120 μm3) and less differentiated progenitor cells (A+A' cells, 40‐79 μm3). Compared with synchronous controls (simulated flight conditions), the 55 h postflight recovery period at 1gresulted in a 40% decrease in the A+A' cell population, a 42% increase in the C+D cells, and a 39% increase in the number of PDL fibroblastlike cells near the bone surface. These results are consistent with a postflight osteogenic response in PDL. This recovery response occurred despite physiological stress in the flight animals that resulted in a highly significant (P≤ 0.001) increase in adrenal weight. The data suggest that after spaceflight there is a strong and rapid recovery mechanism for osteoblast differentiation that is not suppressed by physiological stress.— Garetto, L. P.; Gonsalves, M. R.; Morey, E. R.; Durnova, G.; Roberts, W. E. Preosteoblast production 55 hours after a 12.5‐day spaceflight on Cosmos 1887.FASEB J.4: 24‐38; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295374

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

We have studied the chemistry, hydroxyapatite crystal size, and maturational changes in bone and dentin from rats exposed to microgravity for 12 days in a Soviet biosatellite (Cosmos 1887). Bone ash was reduced in vertebrae (L5) but not in the non‐weight‐bearing calvaria or mandibles. All tissues had a relatively normal percentage composition of Ca, P, and Mg. Nevertheless, flight rat calvaria and vertebral tissues tended to exhibit lower Ca/P and higher Ca/Mg ratios that any of their weight‐matched control groups, and gradient density analysis (calvaria) indicated a strong shift to the fractions of lower specific gravity that was commensurate with impaired rates of matrix‐mineral maturation. X‐ray diffraction data were confirmatory. Bone hydroxyapatite crystal growth in the mandibles of flight rats was preferentially altered in such a way as to reduce their size (C‐axis dimension). But in the mandibular diastemal region devoid of muscle attachments, flight rat bone and dentin were normal with respect to the Ca, P, Mg, and Zn concentrations and Ca/P and Ca/Mg ratios of age‐matched controls. These observations affirm the concept that while microgravity most adversely affects the maturation of newly formed matrix and mineral moieties in weight‐bearing bone, such effects occur throughout the skeleton.—Simmons, D. J.; Grynpas, M. D.; Rosenberg, G. D. Maturation of bone and dentin matrices in rats flown on the Soviet biosatellite Cosmos 1887.FASEB J.4: 29‐33; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2153084

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

We combined biochemical measurements with novel techniques for image analysis in the rat femur to characterize the location and nature of the defect in mineralization known to occur in growing animals after spaceflight. Concentrations of mineral and osteocalcin were low in the distal half of the diaphysis and concentrations of collagen were low with evidence of increased synthesis in the proximal half of the diaphysis of the flight bones. X‐ray microtomography provided semiquantitative data in computer‐generated sections of whole wet bone that indicated a longitudinal gradient of decreasing mineralization toward the distal diaphysis, similar to the chemistry results. Analysis of embedded sections by backscattered electrons in a scanning electron microscope revealed distinct patterns of mineral distribution in the proximal, central, and distal regions of the diaphysis and also showed a net reduction in mineral levels toward the distal shaft. Increases in mineral density to higher fractions in controls were less in the flight bones at all three levels, with the most distal cross‐sectional area most affected. The combined results from these novel techniques identified the areas of femoral diaphysis most vulnerable to the mineralization defect associated with spaceflight and/or the stress of landing.—Mechanic, G. L.; Arnaud, S. B.; Boyde, A.; Bromage, T. G.; Buckendahl, P.; Elliott, J.; Katz, E. P.; Durnova, G. N. Regional distribution of mineral and matrix in the femurs of rats flown on Cosmos 1887 biosatellite.FASEB J.4: 34‐40; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295376

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Previous studies have shown that the changes seen in the bones of growing rats exposed to microgravity are due in part to changes that occur in the growth plate during spaceflight. In this study, growth plates of rats flown aboard Cosmos 1887 (12.5‐day flight plus 53.5‐h recovery at 1g) were analyzed using light and electron microscopy and computerized planimetry. The proliferative zone of flight animals was found to be significantly (P≤ 0.01) larger than that of controls, while the reserve and hypertrophic/calcification zones were significantly reduced. Flight animals also had more cells per column in the proliferative zone than did controls and less in the hypertrophic/calcification region. The total number of cells, however, was significantly greater in flight animals. No difference was found in perimeter or in shape factor, but area was significantly less in flight animals. Electron microscopy showed that collagen fibrils in flight animals were wider than in controls. Since the time required for a cell to cycle through the growth plate is 2‐3 days at 1g, the results reported here represent both the effects of exposure to microgravity and the initial stages of recovery from that exposure.—Duke, P. J.; Durnova, G.;andMontufar‐Solis, D. Histomorphometric and electron microscopic analyses of tibial epiphyseal plates from Cosmos 1887 rats.FASEB J.4: 41‐46; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295377

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

The effects of a 12.5‐day spaceflight (Cosmos 1887 biosatellite) on the geometric, biomechanical, and biochemical characteristics of humeri of male specific pathogen‐free rats were examined. Humeri of age‐matched basal control, synchronous control, and vivarium control rats were contrasted with the flight bones to examine the influence of growth and space environment on bone development. Lack of humerus longitudinal growth occurred during the 12.5 days in spaceflight. In addition, the normal mid‐diaphysial periosteal appositional growth was affected; compared with their controls, the spaceflight humeri had less cortical cross‐sectional area, smaller periosteal circumferences, smaller anterior‐posterior periosteal diameters, and smaller second moments of area with respect to the bending and nonbending axes. The flexural rigidity of the flight humeri was comparable to that of the younger basal control rats and significantly less than that of the synchronous and vivarium controls; the elastic moduli of all four groups, nonetheless, were not significantly different. Generally, the matrix biochemistry of the mid‐diaphysial cross sections showed no differences among groups. Thus, the spaceflight differences in humeral mechanical strength and flexural rigidity were probably a result of the differences in humeral geometry rather than material properties.—Vailas, A. C.; Zernicke, R. F.; Grindeland, R. E., Kaplansky, A.; Durnova, G. N., Li, K.‐C.;andMartinez, D. A. Effects of spaceflight on rat humerus geometry, biomechanics, and biochemistry.FASEB J.4: 47‐54; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.2295378

出版商:Wiley    

年代:1990

数据来源: WILEY

摘要:

Eleven enzymes were measured in individual fibers of soleus and tibialis anterior (TA) muscles from two flight and two control (synchronous) animals. There were five enzymes of glycogenolytic metabolism: phosphorylase, glucose‐6‐phosphate isomerase, glyccrol‐3‐phosphate dehydrogenase, pyruvate kinase, and lactate dehydrogenase (group GLY); five of oxidative metabolism: citrate synthase, malate dehydrogenase, β‐hydroxyacyl‐CoA dehydrogenase, 3‐ketoacid CoA‐transferase, and mitochondrial thiolase (group OX); and hexokinase, subserving both groups. Fiber size (dry weight per unit length) was reduced about 35% in both muscles. On a dry weight basis, hexokinase levels were increased 100% or more in flight fibers from both soleus and TA. Group OX enzymes increased 56‐193% in TA without significant change in soleus. Group GLY enzymes increased an average of 28% in soleus fibers but underwent, if anything, a modest decrease (20%) in TA fibers. These changes in composition of TA fibers were those anticipated for a conversion of about half of the originally predominant fast glycolytic fibers into fast oxidative glycolytic fibers. Calculation on the basis of fiber length, rather than dry weight, gave an estimate of absolute enzyme changes: hexokinase was still calculated to have increased in both soleus and TA fibers, but only by 50 and 25%, respectively. Three of the OX enzymes were, on this basis, unchanged in TA fibers, but 3‐ketoacid CoA‐transferase and thiolase had still nearly doubled, whereas TA GLY enzymes had fallen about 40%. In soleus fibers, absolute levels of OX enzymes had decreased an average of 25% and GLY enzymes were marginally decreased.—Manchester, J. K.; Chi, M. M.‐Y.; Norris, B.; Ferrier, B.; Krasnov, I.; Nemeth, P. M.; McDougal, D. B., Jr.;andLowry, O. H. Effect of microgravity on metabolic enzymes of individual muscle fibers.FASEB J.4: 55‐63; 1990.

ISSN:0892-6638    

DOI:10.1096/fasebj.4.1.1967237

出版商:Wiley    

年代:1990

数据来源: WILEY