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

A refined classification of the stages of the retinopathy of prematurity (RLF) based on the experience of over 7500 examinations during the past decade is presented. We have been using the basic elements of this classification since 1972 in order to evaluate the influence of vitamin E on retrolental fibroplasia (RLF). It is our impression that it provides a more accurate clinical method of following the course of the retinopathy and a tool for assessing the factors other than prematurity and hyperoxia that may play a subtle role in the development of RLF.
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PMID:A classification of retrolental fibroplasia to evaluate vitamin E therapy. 58 96

The effects of hyperoxia at ambient pressure on thyroid function and thyroid hormone metabolism have been assessed. Thyroidal activity was depressed in mice and rats by exposure to hyperoxia, due at least in part to a decrease in the rate of secretion of pituitary thyrotropin. The effects of hyperoxia on the peripheral deiodination of thyroxine (T4) were dependent on the concentration of oxygen employed and/or the duration of exposure; exposure to 40--80% oxygen for 96 h resulted in decreases in the rate of deiodination and in the deiodinative clearance of [125I]T4. Hyperoxia also resulted in a marked fall in the serum concentration of endogenous T4 and a decrease in T4-binding activity in serum. Many of these effects of hyperoxia were prevented by the concomitanat administration of large amounts of vitamin E (alpha-tocopherol acetate). These decreases in thyroid function and T4 metabolism were associated with a decrease in the rate of whole body oxygen consumption. Thus, the deleterious effects of oxygen in the rat were not due, even in part, to an oxygen-induced hyperthyroid state in the peripheral tissues.
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PMID:Role of thyroid gland in oxygen toxicity. 73 22

The effect of oxygen (O2) exposure on the ability of the isolated, perfused rat lung to clear serotonin (5-hydroxytryptamine, 5-HT) from the perfusate was evaluated in normal or vitamin E-deficient Sprague-Dawley rats. Rats were exposed to 100% O2 at 1 ATA for 4-48 h. Lungs were subsequently isolated, artificially ventilated, and perfused in a recirculating system with Krebs-Ringer bicarbonate solution, pH 7.4 containing 3% bovine serum albumin and 0.25 muM [14C] 5-HT. 5HT clearance was calculated from the disappearance rate of [ 14C] 5-HT from the perfusate. In normal rats exposed to 100% O2, there was a progressive reduction in the clearance of 5-HT with increasing duration of O2 exposure. Compared to lungs from air-exposed controls, clearance was depressed 20% (P less than 0.01) after 18 h, 22% (P less than 0.01) after 24 h, and 35% (P less than 0.001) after 48 h. With vitamin E-deficient rats, the reduction in 5-HT clearance occurred after a shorter exposure time and was of greater magnitude than in rats on a normal diet. Depression of 5HT clearance by the lungs is an early alteration of lung function fue to hyperoxia and is potentiated by vitamin E deficiency. The most likely mechanism for the depression of 5-HT clearance is interference with the transport properties of lung endothelium.
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PMID:Depression of serotonin clearance by rat lungs during oxygen exposure. 83 74

Clearance of 5-hydroxytryptamine (5-HT) by the lungs of normal and vitamin E-deficient rats was evaluated following a 60-min exposure to 100% oxygen (O2) at 4 ATA (HBO). After exposure, lungs were isolated, ventilated, and perfused, with a recirculating system used for measurement of 5-HT clearance. Control lungs were obtained from rats exposed to air at 1 ATA. In control normal rats, fractional clearance of 5-HT was 0.78+/-0.03 (mean+/-SE). Following HBO 5-HT clearance was 0.55+/-0.04 (P less than 0.01). In control vitamin E-deficient rats. 5-HT clearance was 0.85+/-0.05 and was decreased to 0.46+/-0.03 (P less than 0.001) following HBO. To evaluate the effect of recovery time after HBO on 5-HT clearance, separate groups of rats were killed at varying intervals post-HBO. In normal rats, 5-HT clearance had returned to control levels by 3-4 after HBO; in vitamin E-deficient rats, clearance remained unchanged 4 h after HBO and was only 74% (P less than 0.001) of control values 24 h post-HBO. These results indicate that depression of pulmonary 5-HT clearance occurs in rats due to hyperoxia and is potentiated by vitamin E deficiency. This represents a reversible alteration of lung function which requires vitamin E for complete recovery.
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PMID:Effect of hyperbaric oxygen exposure on pulmonary clearance of 5-hydroxytryptamine. 89 79

The changes of free radicals and the effect of anisodamine and vitamin E on hyperoxic lung injury were studied. Ninety adult Wistar rats were exposed to greater than 95% O2. Nine a normal rats served as controls. The animals in group A were only exposed to hyperoxia, while in group B and C, they were treated intramuscularly with anisodamine (15 mg/kg, bid) and vitamin E (75 mg/kg, bid) respectively. The rats in each group were killed after 12, 24 or 48 hours oxygen exposure. The blood and lung were examined for SOD, GSH-PX and MDA. In Group A, the quantity of peroxide free radical increased 20%. The activity of SOD and GSH-PX decreased and MDA increase were in lower degree. Changes of SOD, GSH-PX, MDA, PaO2 and lung damage were also in lower degree. The results indicated that the increase of oxygen free radicals may be the pathophysiological factor in hyperoxic lung injury.
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PMID:[The mechanism of the effects of 654-2 and vitamin E on hyperoxic lung injury]. 166 87

Neonatal rabbits were exposed to either normoxia (21% oxygen) or hyperoxia (. 95% oxygen) for 2-4 days, and isolated ventilated perfused lung preparations from the various animals were studied. 5-Hydroxytryptamine (5HT) uptake, perfusion pressure, alveolar lavage protein and lung tissue vitamin E concentrations were measured. There was no difference in mortality between the two groups at any time point. There was no difference in perfusion pressures at any time point. There were no differences between normoxic and hyperoxic animals in alveolar lavage protein or 5 HT uptake at 2 and 3 days. At 4 days, 5HT uptake (fractional) was lower in the hyperoxia group than in controls (0.65 +/- 0.033 v. 0.75 +/- 0.013 (mean +/- SE); p less than or equal to 0.05) and alveolar lavage protein was higher compared to normoxia (1111 +/- 415 micrograms/ml v. 481 +/- 78 micrograms/ml; p less than or equal to 0.05). Lung vitamin E concentrations were higher at 3 days in rabbits exposed to hyperoxia compared to normoxia (16.5 +/- 1.8 micrograms/gm v. 12.3 +/- 0.6 micrograms/gm; p less than or equal to 0.05). In air exposed animals there was a decrease in lung vitamin E concentration after 2 days, whereas hyperoxia exposed animals had no significant decrease in lung vitamin E concentrations from 2-4 days exposure. These studies establish that the decrease in 5HT uptake, albeit delayed compared to that described previously in adult animals, is a reasonable measure of pulmonary oxygen toxicity in newborn rabbits.
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PMID:Effect of hyperoxia on 5-hydroxytryptamine uptake by the neonatal rabbit lung. 182 Nov 73

The pulmonary endothelium is known to be sensitive to oxidant injury, including that of hyperoxia. Similar to effects of exposure to 80-95% O2, porcine platelet transforming growth factor (TGF)-beta 1 at concentrations of greater than or equal to 0.3 ng/ml inhibited proliferation and caused enlargement of bovine pulmonary artery endothelial cells after 24 h of incubation in room air. Uptake of [3H]thymidine, but not of [3H]deoxycytidine, was suppressed by both hyperoxia and TGF-beta 1. The cellular enlargement produced by TGF-beta 1 in room air was attenuated in the presence of anoxia, indicating a need for O2 for TGF-beta 1 to have an effect on cell size. In the presence of 20 microM FeCl3, both TGF-beta 1 and 80% O2 produced marked cellular desquamation from culture dishes. The antioxidants dimethyl sulfoxide and vitamin E partially counteracted the growth inhibitory effect of TGF-beta 1 on endothelial cells. In contrast to its effect on endothelial cells, TGF-beta 1 only moderately altered size and proliferation of smooth muscle cells from the same pulmonary vessels. Uptake of [3H]thymidine by smooth muscle cells was uninfluenced in 48 h by TGF-beta 1, and little, if any, desquamation of these cells occurred with TGF-beta 1 in the presence of 20 microM FeCl3. We propose from these experiments that TGF-beta 1 may produce an oxidant effect on vascular endothelium that is capable of causing injury to this tissue.
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PMID:TGF-beta 1 produces a "prooxidant" effect on bovine pulmonary artery endothelial cells in culture. 192 58

Newborn rats were injected with vitamin E or placebo daily until 6 days after birth. The effect of vitamin E pretreatment on in vitro surfactant phospholipid synthesis was examined in isolated type II cells exposed to oxygen or air form 24 h in vitro. Type II cells were also isolated from untreated 6-day-old rats and cultured for 24 h in oxygen or air with control medium or vitamin E supplemented medium. These cells were used to examine the effect of vitamin E exposure in vitro on type II cell phospholipid synthesis and ultrastructure. Phosphatidylcholine (PC) synthesis was reduced in cells cultured in oxygen as compared with air. This decrease was not prevented by in vivo pretreatment or in vitro supplementation with vitamin E. Vitamin E pretreatment increased the ratio of disaturated PC to total PC and increased phosphatidylglycerol synthesis. The volume density of lamellar bodies in type II cells was increased in cells maintained in oxygen. Vitamin E did not affect the volume density of lamellar bodies. We conclude that in vitro hyperoxia inhibits alveolar type II cell phosphatidylcholine synthesis without decreasing lamellar body volume density and that supplemental vitamin E does not prevent hyperoxia-induced decrease in phosphatidylcholine synthesis.
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PMID:Vitamin E alters alveolar type II cell phospholipid synthesis in oxygen and air. 208 5

Major advances on the therapeutic use and the toxicity of two fat-soluble micronutrients, vitamin A and vitamin E, have taken place in recent years. High dosages of vitamin A and retinoids are teratogenic. The use of isotretinoid in pregnancy is associated with a high risk of congenital malformations. Retinoid metabolites (4-oxo-transretinoic acid and retinyl palmitate) have been related to teratogenicity. Studies in premature infants support the concept that supplementation of vitamin A (to achieve normal serum retinol concentrations) reduces the pulmonary damage caused by hyperoxia. Much controversy has surrounded the use of vitamin E in the low-birth-weight infant. Accumulation occurs with repeated administration and serious toxicity ensues. Thus, on the side of potential therapeutic applications, injudicious use of these vitamins is associated with previously unsuspected toxicity in the fetus and newborn.
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PMID:Micronutrients and drug response: vitamin A and vitamin E in the fetus and in the newborn. 209 98

Freshly isolated rat hepatocytes suspensions were incubated under an atmosphere of 95% O2/5% CO2 or 95% air/5% CO2 for 10 h. Cell injury and death were observed between the 6th and 10th hour of incubation, only in 95% O2-treated hepatocytes. Oxygen-induced injury was preceded by marked lipid peroxidation and rapid depletion of cellular alpha tocopherol content. The exogenous administration of unesterified alpha tocopherol (T, 25 microM) resulted in a 20-fold increase in cellular T levels (4.2 nmol/10(6) cells) but failed to protect these hepatocytes from the toxic effects of oxygen. In contrast, hepatocytes incubated with 25 microM of the succinate ester of alpha tocopherol (TS) contained both TS (3.0 nmol/10(6) cells) and T (1.4 nmol/10(6) cells) and were completely protected from the toxic effects of oxygen, including the induction of lipid peroxidation. These findings suggest that TS cytoprotection results not from the cellular accumulation of T but rather, from cellular TS accumulation. The data also indicate that the depletion of cellular T is not the critical cellular event that is responsible for hyperoxia (reactive oxygen intermediate)-induced injury. Instead, it appears that TS possesses unique cytoprotective properties that intervene in the critical cellular events that lead to oxygen toxicity. Thus, vitamin E succinate and our hyperoxic hepatocyte preparation provide a promising new model system for the study and prevention of tissue damage resulting from the toxic effects of hyperoxia and reactive oxygen intermediates.
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PMID:Oxygen toxicity: unique cytoprotective properties of vitamin E succinate in hepatocytes. 228 88


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