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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

For studying the mechanism of hyperoxia toxic effect on metabolism in the rat brain localization of lysosomes enzymes - acid phosphatase, DNase II and acid peptid-hydrolases were investigated in the brain subcellular fractions under different phases of oxygen poisoning and in the in vitro experiments. Under hyperoxia redistribution of the lysosome enzymes is found between the fraction enriched with lysosomes and the soluble one. The character of redistribution evidences for disturbance of permeability in the brain lysosome membranes under hyperoxia. Urea possessing a protective effect under these conditions prevents from labilization of lysosome enzymes which is evoked by the effect of oxygen hyperoxia. When studying manifestation of the effect of lysosome hydrolases release on the substrate level there were found constancy of DNA content in the brain under hyperoxia and a decrease in polymeric property of the brain DNA an hour after the beginning of the terminal phase of oxygen poisoning.
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PMID:[Lysosome enzymes of brain in hyperoxia and under the effect of urea]. 120 6

The present study was conducted on bone tissue responses to irradiation towards a treatment model of mandibular irradiation injury by comparing the results of experimental observations of irradiation effects on rabbit hind legs and rat mandibular bones (paper I, II and III) with clinical observations of irradiation effects on the human mandible (paper IV, V and VI). The main results of the study were as follows: Bone marrow haemorrhage, eosinophilia and incipient edema were encountered in the rabbit leg one day after a single irradiation dose. Edema and fibrosis were the salient features after five weeks, while both regenerative and fibrotic changes predominated eleven weeks after irradiation. The changes were the more extensive the greater the irradiation dose was. Empty lacunae as a sign of cell damage in cortical bone already appeared on the first day after irradiation; this effect reached its maximum when the dose was 20 Gy or more. Bone marrow and subcutaneous tissue pO2 and pCO2 were measured by means of implanted Silastic tonometers in irradiated and nonirradiated rabbit hind legs. Single dose irradiation was followed by a rapid, dose dependent decrease of marrow pO2. The corresponding effect on pCO2 was weaker and appeared later. The response to hyperoxia in the bone marrow became weaker when the irradiation dose increased. Less significant was the response of CO2 tension to hyperoxia. O2 and CO2 tensions were recovered after single dose irradiation both in subcutaneous tissue and in bone marrow, but the reduction was less in bone marrow. During the twelve weeks observation period clearly better recovery in tissue gas tensions was observed in subcutaneous tissue than in bone marrow. Nonirradiated periosteal grafts on irradiated bone cavities in the rabbit tibia induced more rapid and intense mature bone formation than irradiated periosteal grafts. The irradiated periosteum, even after a single dose of 20 Gy, had some osteogenetic capacity. The alkaline phosphatase content was lowered eight weeks after surgery in irradiated legs but clearly exceeded control values twelve weeks after surgery indicating new bone formation. Lysosomal enzyme DAP II contents were increased in all irradiated specimens as a sign of disturbed bone formation. The tissue concentrations of acid phosphatase, cytochrome oxidase, lactate dehydrogenase, isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase and succinate dehydrogenase in the immediate postirradiation period showed a greater increase in activity in the cut lines of the irradiated rat mandibles than in those of the nonirradiated mandibles.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Bone tissue response to irradiation and treatment model of mandibular irradiation injury. An experimental and clinical study. 309 Aug 54

We studied the influence of normobaric hyperoxia on bone metabolism in 3- and 12-month-old male Wistar rats. Maintaining young rats (3 months) during the 14-hour daily sessions under normobaric hyperoxia (90% O2) was accompanied by a significant decrease in the concentration of C-terminal propeptides of collagen type I (by 36%), the acid phosphatase activity (by 32%), an increased activity of alkaline phosphatase (by 64%), an increased concentration of pyridinoline (by 37%) and 3-CrossLaps (by 8%), glycosaminoglycans (by 72%) in the blood serum. We believe that normobaric hyperoxia (90%) is accompanied by the disturbance of collagen synthesis. In adult rats under the same conditions for 14 sessions, the concentration ofglycosaminoglicans significantly increased by 60% relative to the control values. After 28 sessions of breathing the normobaric gas mixture containing 90% O 2 this parameter increased by 195%. Breathing normobaric gas mixture containing both 40% and 90% of O2 for 14 and 28 days decreased the acid phosphatase activity and the tartrat-resistant acid phosphatase activity by 18-25%. We believe that in adult animals 90% hyperoxia does not affect the activity of osteoblasts, but breaks the link between glycosaminoglicans and collagen fibrils, decreases the activity oflysosomal enzymes which are produced by osteoclasts and which can inhibit osteogenesis.
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PMID:[Normobaric hyperoxia affects osteogenesis in rats]. 2287 53