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 296,593 document(s) hit in 31,850,051 MEDLINE articles (0.02 seconds)

Four male and four female, fully conscious, M. mulatta were exposed twice each to diphasic accelerations of 3 or 4 +Gz (3 min) with a 10-min, 1-G intersession. One polarographic electrode was inserted intracortically and another one into neck subcutaneous tissue. With the first of two 3 or 4 +Gz exposures, cerebral PO2 fell from 15.11 to 5.73 and 2.92 torr, respectively; subcutaneous PO2 fell from 27.6 to 7.72 and 4.8 torr, respectively. Cerebral tissue exhibits post-G hyperoxia, related to initial stress intensity; even after the 10-min intersession, it is capable of mitigating the O2 desaturation effect of the second stress. Cerebral and subcutaneous tissue oxygen desaturation with G onset are comparable, but re-oxygenation in the latter tissue is apparently inertia-ridden and a simple relationship between the overall responses of cerebral and subcutaneous PO2 to +Gz acceleration could not be demonstrated.
Aviat Space Environ Med 1979 Jul
PMID:Determination of cerebral and neck subcutaneous tissue PO2 with 3 and 4 +Gz in M. mulatta. 11 59

1. The influence of ammonia and ornithine on the oxygen uptake and the formation of citrulline was investigated with isolated rat liver mitochondria. The experiments were performed in a cytosol-like saline medium at 38 degrees C. 2. Under these conditions an increase of the respiration rate by ammonia and ornithine was observed, but a small response to external ADP, only. The missing stimulation by ADP was due to a partial inhibition of the respiratory chain by traces of zinc (approximately 1 microM) present in the medium. This inhibition was only detected at low concentrations of mitochondria. 3. For activation of respiration by ammonia plus ornithine two different processes were responsible: (i) chelation of the inhibiting zinc by ornithine, which could be prevented by EDTA; (ii) ADP production in the matrix space during formation of carbamoyl phosphate, which could be prevented by oligomycin but not by carboxyatractyloside. 4. This stimulus of the carbamoyl phosphate formation and of the equivalent citrulline synthesis on the mitochondrial respiration ran to 12% of that increase caused by phosphorylation of external ADP. The maximum rate of citrulline formation was limited by the activity of carbamoyl phosphate synthetase. 5. Added ADP suppresses the production of citrulline probably by the exchange of extramitochondrial ADP versus intramitochondrial ATP. The data suggest a common adenine nucleotide pool delivering ATP to the adenine nucleotide translocase as well as to the carbamoyl phosphate synthetase.
Acta Biol Med Ger 1979
PMID:The stimulation of the mitochondrial respiration by citrulline synthesis. 11 92

Changes in rheological properties of the blood were produced by intravenous injection of a high-molecular weight dextran and lysin-vasopressin. The animals were decapitated in one hour. Oxygen absorption by mitochondria of the heart in oxidation of 2.5-10 mM of the succinate increased by 90-120%, as compared to control. Stimulation of respiration by ADP was decreased 1.5-2 times. Simultaneous administration of the succinate and glutamic acid normalized the respiration and phosphorylation. A possibility of inhibition of succinic-dehydrogenase by the oxalo-acetic acid was suggested. Switching of respiration to succinic acid and limiting of the SDG activity can be considered as adaptive factors under conditions of changes in rheological properties of the blood, and are directed to the maintenance of cardiac activity, this being evidenced by the absence of changes in the ATP-asic activity and in the myosin content of the heart.
Biull Eksp Biol Med 1975 Mar
PMID:[The influence of rheologic properties of the blood on adaptive processes in the myocardium]. 12

Increased pressure of O2, N2,or He exert inhibitory or stimulatory effects on activity of Na-K-Mg ATPase obtained from beef brain cortex. Oxygen at 2 ATA and N2 at 4 ATA exert significant inhibitory effects whereas 3 & 4 ATA O2, 1-3 ATA N2 exert significant stimulatory effects. Effects of He on ATPase activity are qualitatively similar to those of N2. The effects of the gases are not qualitatively altered by the presence or absence of ATP. A pressure compensated analysis reveals that at the same pressures, O2 and N2 exert different effects of ATPase activity.
Aviat Space Environ Med 1977 Jan
PMID:Effect of increased pressures of oxygen, nitrogen, and helium on activity of a Na-K-Mg ATPase of beef brain. 13 12

1. Rats kept in a hypoxic chamber (10% O2) for 3 or more weeks developed right ventricular hypertrophy, muscularization of pulmonary arterioles and polycythaemia. These changes resemble those found in human hypoxic disease and, in particular, in patients dying from chronic airways obstruction. 2. Resolution of these changes was studied in a normal environment and in an intermittently normal, intermittently hypoxic environment. The latter regimen modelled the situation of patients with cor pulmonale receiving long-term intermittent oxygen therapy. 3. In a normal environment right ventricular hypertrophy and polycythaemia were resolved in 6 weeks but vessel changes were not resolved in 12 weeks. 4. In the intermittently normoxic environment (40 or 80 h in air per week) there was some resolution of right ventricular hypertrophy in 6 weeks but no significant reduction in vessel thickening or in polycythaemia in 12 weeks.
Clin Sci Mol Med 1977 Feb
PMID:Resolution of hypoxic changes in the heart and pulmonary arterioles of rats during intermittent correction of hypoxia. 13 24

Mass screening in the Geok-chai region of Azerbaijan covered 264 persons. 2 families with abnormal hemoglbin were detected. Electrophoresis in PAG and on cellulose acetate films as well as sickling test showed that in 3 out of 9 members of one of the families HbS was detected. 6 out of 8 members of the others family appeared to be HbD-carriers. In 4 members of this family abnormal hemoglobin was found out in combination with G-6-PDH deficiency. No clinical manifestations were found. A number of beta-thalassemia cases were detected in screened children as well as in adults. Hemoglobin oxygen equilibrium curves were studied in patients with heterozygous beta-thalassemia. In case of G-6-PDH deficiency when it is not possible to obtain active enzyme zones on the columns with PAG these zones can be detected when CoCl2 (2 mM) is added into the incubation medium.
Acta Biol Med Ger 1977
PMID:Hemoglobinopathies and glucose-6-phosphate dehydrogenase deficiency in one of the regions of Azerbaijan: mass screening and laboratory investigations. 14 87

A turnover of glycogen was distinctly increased in hypertrophic rat heart within 2 months after coarctation of aorta; this was corroborated by increased 4.5-fold incorporation of 14C-glucose into glycogen and by removing of label from glycogen in heart perfusion using Langendorf preparation. Due to stationary activation of glycolysis secretion of lactate from isolated hypertrophic heart was twice more than that from intact one in aerobic contitions. Activities of glycolytic enzymes, extracted from intact and hypertrophic heart muscles in optimal conditions of incubation, were approximately of the same value; this suggests the distinct potential activity of glycolytic system in myocardium in vivo. Decrease in oxygen utilization is apparently the reason of glycolytic system activation in development of heart hypertrophy.
Vopr Med Khim
PMID:[State of the glycolytic system in the hypertrophied heart]. 14 27

Collagen metabolism was studied in rat lungs during prolonged intermittent exposure to oxygen. After an initial of 2-d exposure to oxygen, the rats alternately breathed air and oxygen in 24-h periods up to 30 d. Lung histology showed perivascular edema as an early sign of oxygen toxicity. Increased capillary permeability was followed by a marked perivascular leukocytosis that was prominent between the 5th and 11th d of the treatment. During the further course of the experiment, the inflammatory response gradually diminished, and finally a network of collagen fibres filled the perivascular areas. The inflammatory process elevated the amounts of DNA and RNA in lung tissue, and the ratio of RNA to DNA was maximal on the 5th day. Studies on metabolism of lung collagen with intraperitoneally injected 3H-proline as label showed that, after the initial inflammatory reaction, both synthesis and degration of collagen were increased in oxygen-treated lungs. The increase in synthesis exceeded the rise in degradation and, therefore, collagen was accumulated. The activation of lung collagen synthesis coincided in time with a rise in the activity of lung protocollagen proline hydroxylase.
Aviat Space Environ Med 1975 May
PMID:Collagen metabolism in rat lungs during chronic intermittent exposure to oxygen. 16 7

A series of coumarins and delta3-isoflavenes was prepared. Although antifertility activity was shown by all of these compounds, the required dosage in mice varied from 13.5 mug/kg/day to 50 mg/kg/day. The most potent compounds were the 2-methyl-4-ethylisoflavenes, two of which (2a and 2b) were about equipotent with DES on a molar basis. They were followed by the 2,2-dimethylisoflavenes, the 2-unsubstituted isoflavene, and the coumarins. The most active compounds possessed an acetoxy group at C-7 and an oxygen function at C-4'. Presence of fluorine at C-4' or diethylaminoethoxy at C-M decreased the antifertility activity. The uterotropic activity followed the same trends as the antifertility activity with some evidence for the separation of the two effects in the 2,2-dimethylisoflavene series. Based on a limited study it appears that two phenolic hydroxyl groups are required for the presence of good estrogen receptor binding activity. An apparent lack of correlation between the estrogen binding activity and uterotropic or antifertility effects is probably explained by in vivo metabolism.
J Med Chem 1975 Oct
PMID:Flavonoids. 8. Synthesis and antifertility and estrogen receptor binding activities of coumarins and delta3-isoflavenes. 16 52

Skeletal muscle adapts to endurance excerise, such as long distance running, with an increase in the capacity for aerobic metabolism. This is reflected in an increased capacity of whole homogenates and of the mitochondrial fraction of muscle to oxidize pyruvate and long chain fatty acids. Underlying this increase in the ability to obtain energy by respiration is an increase in the levels of a number of mitochondrial enzymes. These include the enzymes involved in fatty acid oxidation, the enzymes of the citric acid cycle, the components of the respiratory chain that link the oxidation of succinate and NADH to oxygen, and coupling factor 1. These increases in mitochondrial enzyme activity appear to be due to an increase in enzyme protein as evidenced by a doubling of the concentration of cytochrome c and a 60% increase in the protein content of the mitochondrial fraction skeletal muscle. Electronmicroscopic studies suggest that increases in both the size and number of mitochondria are responsible for the increase in mitochondrial protein. An alteration in mitochondrial composition also occurs, with some mitochondrial enzymes increasing 2-fold, others increasing only 35% to 60%, while others, including mitochondrial alpha-glycerophosphate dehydrogenase, creatine phosphokinase and adenylate kinase do not increase at all. As a result of these and other exercise induced biochemical adaptations skeletal muscle tends to become more like heart muscle in its enzyme pattern.
Med Sci Sports 1975
PMID:Adaptation of skeletal muscle to endurance exercise. 17 69


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