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

In female Sprague Dawley rats, the tissue protein is homogeneously distributed and significantly increased in 7,12-dimethylbenz[a]anthracene-initiated mammary carcinoma. At the centre and margin of the carcinoma, the concentration of superoxide dismutase is 54 +/- 10 and 117 +/- 38 microgram/g, respectively, while in the tumour as a whole it is 104 +/- 32 microgram/g. The latter value is not significantly different from 113 +/- 35 microgram/g, the enzyme concentration in mammary tissue from lactating rats. Exposure of the tumour-bearing rats to hyperoxia does not increase the tumour protein but raises the enzyme concentration at the centre and margin of the carcinoma to 162 +/- 73 and 286 +/- 103 microgram/g, respectively.
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PMID:Modification of superoxide dismutase in rat mammary carcinoma. 40 51

Pulmonary exchange of O2 and CO2 was measured in unidirectionally ventilated ducks in an attempt to determine lung O2 diffusing capacity, DO2. Perfusion shunt (= venous admixture) was estimated from O2 exchange in hyperoxia, and the ventilation shunt (ventilation of non-perfused parallel lung units) was estimated from exchange of the highly soluble inert gas, chloroform. Differences in the ventilation/perfusion ratio of parallel lung units were assessed from measurement of CO2 exchange using a parallel two-compartment model. DO2 values were calculated accounting for ventilation shunt, perfusion shunt, and inhomogeneity. Perfusion shunt averaged 2.7% and ventilation shunt, 9.4%. The ventilation/perfusion ratio in the two compartments differed on the average by a factor of 2.6. The uncorrected values of DO2, not accounting for lung inhomogeneities, progressively declined with increasing inspired PO2, but this dependence was less pronounced after correcting for lung inhomogeneities. The corrected value of DO2 averaged 100 mumol . min-1 . torr-1 for ducks of 1.8 kg mean body weight. DO2 did not differ when nitrogen was replaced by helium in the ventilatory gas indicating that diffusion within the air capillaries did not contribute a significant resistance to O2 uptake. The results suggest that neither functional inhomogeneities nor diffusion between lung gas and blood limit O2 uptake of the resting duck. Under conditions of elevated metabolism, however, these parameters may become rate-limiting for O2 supply.
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PMID:Gas exchange in the parabronchial lung of birds: experiments in unidirectionally ventilated ducks. 41 39

Before exposure of man to hyperbaric hyperoxia the blood plasma possessed marked erythropoietic activity. Erythropoietins disappeared completely and erythropoiesis inhibitors appeared in the plasma of persons untrained to hyperbaric hyperoxia after a 24-hour exposure to hyperoxic conditions (25% of oxygen in the inhaled air) in the high pressure chamber corresponding to the depth of 63 metres. A reduction of the peripheral red blood indices was observed by that time.
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PMID:[Plasma erythropoiesis inhibitors in humans during hyperbaric hyperoxia]. 42 Sep 29

The Authors studied the behaviour of acid-base balance in subjects with chronic obstructive lung disease undergoing Maximal Aerobic Work following the method of Pasargiklian e Coll., 1955. For the research two different experimental pattern were adopted: 1) patients were subjected, in two different sessions, to the muscular work in room air and in hyperoxia (60%) breathing for the evaluation of acid-base balance. During hyperoxia Authors observed rising of paO2 and decrease of paCO2, pH and lactic acid concentration. 2) In the second pattern the muscular test was performed in room air only with the use of an antiphosphodiesterasic drug e.v. administration in each patient. Together with acid-base balance behaviour of plasmatic electrolytic assessment was controlled in order to evaluate adaptation to work. The data, although preliminary, show an increase of paO2 with decrease of paCO2 in both test; potassium and bicarbonates concentration increase more in the first test without theophyllin whereas this drug forbid these increments. The Authors even if the experimental program must be developed suggest that the evaluation of these data is interesting in diagnosis and prognosis in chronic lung disease for the cellular adaptation to work and offers interesting elements to carry on the rehabilitation of chronic obstructive lung disease.
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PMID:[Changes in the acid-base equilibrium and the water-electrolyte balance during maximum aerobic work in patients with chronic broncho-pulmonary disease]. 43 34

The content of homocarnosine, gamma-amino butyric acid and histidine was studied in the brain of newborn, 1, 7, 14, 21 and 30-day rabbits in normalcy and under hyperoxia. For 30 days of the postnatal life the amount of peptide in the animal brain is 2.5, histidine 1.6, gamma-amino butyric acid--2.2 times as high. At the preconvulsive stage of oxygen poisoning the content of homocarnosine lowers sharply in the brain of rabbits of all age groups. The most considerable decrease is observed in the brain of 14, 21 and 30-day rabbits by 53, 60 and 85%, respectively. The content of gamma-amino butyric acid lowers only in the brain of 21 and 30-day animals by 39 and 47%, respectively; the content of histidine in these animals under hyperoxia, vice versa, increases by 10 and 25%.
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PMID:[Content of homocarnosine, gamma-amino butyric acid and histidine in brain tissue of different age normal rabbits and under hyperoxia]. 45 27

Substrate specificity of monoamine oxidase (MAO) of the A type from rat brain and liver tissues was altered after exposure of rats to an increased oxygen pressure [4 ati O2, 1 hr]. Simultaneously with a decrease in monoamine deaminating activity the enzyme acquired an ability to deaminate several substances, which are not MAO substrates in normal state, in particular, aminosugars. Activity of MAO of the B type was not altered in brain under hyperoxia. Alterations in catalytic properties of MAO of the A type were apparently important in development of the oxygen intoxication.
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PMID:[Type A and B monoamine oxidase activity in hyperbaric oxygenation]. 45 1

Equipment has been developed for the servo-control of arterial oxygen tension in sick, newborn babies. Using an indwelling umbilical arterial oxygen electrode as sensor, the equipment successfully regulated the administration of oxygen to 12 newborn babies with respiratory distress syndrome, significantly improving the stability of arterial oxygen tension and lessening the duration of episodes of hypoxia and hyperoxia.
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PMID:New technique for servo-control of arterial oxygen tension in preterm infants. 45 11

Pulmonary ventilation (V) and alveolar gas composition (PACO2, PAO2) were studied in 12 healthy men who performed gradual muscular work under conditions of controlled hypercapnia, hypoxia, hyperoxia or their combinations. The respiratory response was estimated by absolute values of ventilation at the given PACO2 value and by its rise by 1 mm Hg of increased PACO2 (delta V/delta PACO2) under rest and under transitional and steady-state exercise. The exercise on-switch was accompanied by displacement to the top and an increased slope of the response curve (delta V/delta PACO2) not related to the work load. These changes suggest multiplicative interaction of the neurogenic and hypercapnic drives in the load switch-on. During steady-state exercise an important role of the hypoxic drive was revealed: hypoxemia induced a shift of the delta V/delta PACO2 response curve to a higher level, especially with the great work load. Thus the positive interaction between the hypercapnic and hypoxic respiratory drive augments with muscular exercise.
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PMID:[Relationship between hypercapnic and hypoxic stimuli of respiration during muscular activity]. 45 11

Changes of the oxygen tension in the surface layers of cerebral cortex (PtO2) and arterial blood (PaO2) in the conditions of hyperoxia occurred in anesthetized rabbits: raising of O2 partial pressure in altitude chamber to 1.0 and 2.0 kgs/cm2 increased PaO2 from 76.5 +/- 11.4 mm Hg to 472.3 +/- 63.1 and 1138.0 +/- 79.4 mm Hg respectively. Raising of O2 partial pressure in altitude chamber from 0.2 to 6.0 kgs/cm2 increased PtO2 from 34.9 +/- 12.0 to 1087.5 +/- 149.8 mm Hg. Obvious defence reactions of the organism developed at the moment of transition from air breathing to pure oxygen breathing under the pressure of 1.0 kgs/cm2. High effectiveness of these reactions preserved with the raising of pressure to 3.0 kgs/cm2 and weakened with the further raising of pressure to 4.0-6.0 kgs/cm2. With prolongation of exposure to the 2.0-3.0 kgs/cm2 pressure the defence reactions slackened as well.
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PMID:[Effect of hyperoxia on oxygen tension in the blood and brain tissue]. 45 65

Recent data demonstrate that the magnitude of the heat loss that occurs from the respiratory tract during exercise correlates with the degree of post-exertional obstruction that develops in asthmatics. Respiratory heat loss relates directly to the minute ventilation and heat capacity of the inspired gas and inversely to its water content and temperature. Because it has been shown that inhaling 100% oxygen during exercise blunts the obstructive response, we wondered if this effect could be accounted for by differing values of heat exchange with air and oxygen breathing. To examine this question, we studied 10 asthmatics by measuring multiple aspects of pulmonary mechanics before and after four bouts of exhausting leg work during which the subjects inhaled either air or oxygen conditioned to provide widely differing thermal burdens on their airways. Under all inspired gas conditions, oxygen breathing produced significantly less obstruction than air. Minute ventilation was also significantly less with oxygen as was the total heat lost. As the latter fell, so did the magnitude of the postexercise obstruction. When the differences in ventilation and respiratory heat loss between air and oxygen were eliminated by eucapnic hyperventilation, the differences in the obstructive responses also disappeared. Thus, the effects of hyperoxia on exercise-induced asthma can be accounteed for solely by alterations in heat exchange.
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PMID:A critical assessment of the mechanism by which hyperoxia attenuates exercise-induced asthma. 45 67


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