Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitric oxide (NO) may either protect against or contribute to oxidant-induced lung injury. In this study, we sought to determine whether either inhaled NO in concentration of 10 and 100 parts per million (ppm) or inhibition of endogenous NO formation with L-NG nitroarginine methyl ester (L-NAME) or aminoguanidine alters the extent of lung injury in rats breathing 100% O2. Lung thiobarbituric acid reactive substances (TBARS), wet to dry lung weight ratio (Q(W)/Q(D)), vascular and epithelial permeability (assessed by simultaneous intravenous administration of 131I-labeled albumin and intraalveolar instillation of 125I-labeled albumin), alveolar liquid clearance (evaluated based on the increase in alveolar protein concentration), and lung liquid clearance (gravimetric method) were determined after 40 h exposure to either 100% or 21% O2. Exposure to hyperoxia caused increases in lung TBARS from 10.5 +/- 0.7 to 13.7 +/- 1.5 micromol/mg protein (p < 0.05); in blood hemoglobin concentration (Hb) from 14 +/- 1 g/dl to 17 +/- 1 g/dl (p < 0.05); in the Q(W)/Q(D) ratio from 4.02 +/- 0.3 to 5.31 +/- 0.5 (p < 0.05); and in alveolar-arterial oxygen tension difference from 124 +/- 14 mm Hg to 241 +/- 61 mm Hg (p < 0.05); as well as a decrease in blood pressure, from 131 +/- 15 mm Hg to 72 +/- 26 mm Hg (p < 0.05). Hyperoxia also increased vascular albumin leakage and moderately altered epithelial barrier permeability to protein. Inhalation of 10 ppm NO prevented the increases in TBARS and Q(W)/Q(D), had no effect on the alveolar barrier impermeability to protein, and improved alveolar liquid clearance. Inhalation of 100 ppm NO did not alter the increases in TBARS and Q(W)/Q(D) but increased vascular permeability to protein. Survival of rats exposed to hyperoxia was not improved by inhaled NO. Treatment with L-NAME or aminoguanidine reduced survival. L-NAME, but not aminoguanidine, increased lung TBARs. These results suggest that, depending on its concentration, inhaled NO can either reduce or increase the early consequences of hyperoxic lung injury. Treatment with L-NAME, and to a lesser extent aminoguanidine, worsened hyperoxic lung injury, indicating a protective effect of endogenous NO.
 ...
PMID:Effects of inhaled nitric oxide or inhibition of endogenous nitric oxide formation on hyperoxic lung injury. 919 2

A newly developed microscope using acousto-optic tunable filters (AOTFs) was used to generate in vivo hemoglobin saturation (SO2) and oxygen tension (PO2) maps in the cerebral cortex of mice. SO2 maps were generated from the spectral analysis of reflected absorbance images collected at different wavelengths, and PO2 maps were generated from the phosphorescence lifetimes of an injected palladium-porphyrin compound using a frequency-domain measurement. As the inspiratory O2 was stepped from hypoxia (10% O2), through normoxia (21% O2), to hyperoxia (60% O2), measured SO2 and PO2 levels rose accordingly and predictably throughout. A plot of SO2 versus PO2 in different arterial and venous regions of the pial vessels conformed to the sigmoidal shape of the oxygen-hemoglobin dissociation curve, providing further validation of the two mapping procedures. The study demonstrates the versatility of the AOTF microscope for in vivo physiologic investigation, allowing for the generation of nearly simultaneous SO2 and PO2 maps in the cerebral cortex, and the frequency-domain detection of phosphorescence lifetimes. This class of study opens up exciting new possibilities for investigating the dynamics of hemoglobin and O2 binding during functional activation of neuronal tissues.
 ...
PMID:Near-simultaneous hemoglobin saturation and oxygen tension maps in mouse brain using an AOTF microscope. 928 90

Red cell oxygen affinity, red cell nucleoside triphosphate (NTP) levels and blood oxygen-carrying capacity were determined for male, nonpregnant and pregnant female, and fetal garter snakes Thamnophis elegans exposed to hypoxia (5 % oxygen) and hyperoxia (100 % oxygen). Male and nonpregnant female snakes were maintained under these conditions for up to 3 weeks and exhibited an apparent maximal change in oxygen affinity after 14 days of hypoxia and hyperoxia. Red cell NTP levels decreased and oxygen affinity increased with exposure to hypoxia, while exposure to hyperoxia promoted an increase in red cell NTP concentrations and a decrease in red cell oxygen affinity in the males. Hyperoxia-exposed nonpregnant females did not show a significant change in oxygen affinity. After 14 days of hypoxia, the pregnant females showed an increase in red cell oxygen affinity which was associated with a decrease in red cell NTP concentration and in the molar ratio of NTP/hemoglobin relative to normoxic controls. Fourteen days of hyperoxia did not result in a change in oxygen affinity of red cells from the pregnant female, but did promote a slight increase red cell NTP concentrations. The blood parameters of fetuses from females exposed to hypoxia or hyperoxia did not differ from those of normoxic control fetuses. The fetuses of females exposed to hypoxia suffered greater mortality, appeared less developed and had a lower average wet mass than the fetuses of normoxic- and hyperoxic-exposed females. Neither hypoxia nor hyperoxia altered the oxygen-carrying capacity of the blood in any group of snake.
 ...
PMID:Effects of hypoxia and hyperoxia on oxygen-transfer properties of the blood of a viviparous snake 931 71

In order to evaluate cerebral oxygenation and perfusion during deep hypothermic circulatory arrest (DHCA) and selective cerebral perfusion (SCP), continuous measurement of regional cerebral oxygen saturation (rSO2) by near-infrared spectroscopy (NIRS) was performed. Two patients undergoing aortic arch surgery performed under DHCA and SCP were studied. 1) Circulatory arrest produced a continuous decrease in rSO2. Introduction of SCP increased rSO2 to even above the pre-circulatory arrest level (reperfusion hyperoxia). 2) During SCP, changes in rSO2 correlated well with the naso-pharyngeal temperature, SCP flow rate, and level of carbon-dioxide insufflation to SCP. 3) These changes in rSO2 paralleled with those of jugular venous hemoglobin saturation (SjO2) measured simultaneously, although SjO2 frequently exhibited artifacts. We conclude that rSO2 measurement may be a non-invasive and continuous measure in the evaluation of cerebral oxygenation and perfusion during DHCA and SCP.
 ...
PMID:[Regional cerebral oxygen saturation as a monitor of cerebral oxygenation and perfusion during deep hypothermic circulatory arrest and selective cerebral perfusion]. 956 May 47

Heme oxygenase (HO)-1, which catalyzes heme breakdown, is induced by oxidative stress and may protect against oxidative injury. We hypothesized that induction of HO-1 by hemoglobin (Hb) in the lung would protect the rat from pulmonary O2 toxicity. Rats given intratracheal (i.t.) Hb showed lung-specific induction of HO-1 by 8 h by Western analysis. Rats were then pretreated for 8 h before 60 h of exposure to 100% O2 with either IT normal saline, HB, or Hb plus the HO-1 inhibitor tinprotoporphyrin (SnPP). Both the Hb + O2 and Hb + O2 + SnPP animals had less lung injury than normal saline controls as indicated by lower pleural fluid volumes and wet-to-dry weight ratios (P < 0.01). The improvement in injury in the two Hb-treated groups was the same despite a 61% decrease in HO enzyme activity in the Hb + SnPP group after 60 h of O2. In addition, inhibition of HO activity with SnPP alone before O2 exposure did not augment the extent of hyperoxic lung injury. These results demonstrate that IT Hb induces lung HO-1 in the rat and protects against hyperoxia; however, the protection is not mediated by increased HO enzyme activity.
 ...
PMID:Lung-specific induction of heme oxygenase-1 and hyperoxic lung injury. 957 77

The importance of diffusion and perfusion in terms of oxygen transport was evaluated by chronically altering environmental O2 availability (hypoxia or hyperoxia) and blood O2 content (carbon monoxide) through development in Xenopus laevis. Oxygen consumption (MO2), individual wet mass, heart rate (fH), and stroke volume (SV) were measured in animals raised from eggs to pre-metamorphic climax while maintained at 11, 21 and 35 kPa O2, combined with and without 2 kPa carbon monoxide. Additionally, cardiac output (Q), and a recently defined O2 consumption/transport quotient (MO2 x QO2(-1)) were calculated. Wet mass, MO2, and fH, were not significantly different between controls and experimental treatments at any developmental stage. However, with hemoglobin oxygen transport blocked by carbon monoxide, the exposed larvae showed an increased SV, Q and MO2 x QO2(-1). Combined, these data suggest that in spite of impaired blood O2 convection, normal aerobic metabolism was maintained, indicating that direct diffusion of O2 plays an important role in supplying oxygen during early development.
 ...
PMID:The ontogeny of cardio-respiratory function under chronically altered gas compositions in Xenopus laevis. 962 36

We hypothesized that near-infrared spectroscopy (NIRS) measures of hemoglobin and/or myoglobin O2 saturation (IR-SO2) in the vascular bed of exercising muscle would parallel changes in femoral venous O2 saturation (SfvO2) at the onset of leg-kicking exercise in humans. Six healthy subjects performed transitions from rest to 48 +/- 3 (SE)-W two-legged kicking exercise while breathing 14, 21, or 70% inspired O2. IR-SO2 was measured over the vastus lateralis muscle continuously during all tests, and femoral venous and radial artery blood samples were drawn simultaneously during rest and during 5 min of exercise. In all gas-breathing conditions, there was a rapid decrease in both IR-SO2 and SfvO2 at the onset of moderate-intensity leg-kicking exercise. Although SfvO2 remained at low levels throughout exercise, IR-SO2 increased significantly after the first minute of exercise in both normoxia and hyperoxia. Contrary to the hypothesis, these data show that NIRS does not provide a reliable estimate of hemoglobin and/or O2 saturation as reflected by direct femoral vein sampling.
 ...
PMID:Comparison of femoral blood gases and muscle near-infrared spectroscopy at exercise onset in humans. 993 Dec 9

The accepted importance of circulatory impairment to sickle cell anemia remains to be verified by in vivo experimentation. Intravital microscopy studies of blood flow in patients are limited to circulations that can be viewed noninvasively and are restricted from deliberate perturbations of the circulation. Further knowledge of sickle blood flow abnormalities has awaited an animal model of human sickle cell disease. We compared blood flow in the mucosal-intestinal microvessels of normal mice with that in transgenic knockout sickle cell mice that have erythrocytes containing only human hemoglobin S and that exhibit a degree of hemolytic anemia and pathological complications similar to the human disease. In sickle cell mice, in addition to seeing blood flow abnormalities such as sludging in all microvessels, we detected decreased blood flow velocity in venules of all diameters. Flow responses to hyperoxia in both normal and sickle cell mice were dramatic, but opposite: Hyperoxia promptly slowed or halted flow in normal mice but markedly enhanced flow in sickle cell mice. Intravital microscopic studies of this murine model provide important insights into sickle cell blood flow abnormalities and suggest that this model can be used to evaluate the causes of abnormal flow and new approaches to therapy of sickle cell disease.
 ...
PMID:In vivo blood flow abnormalities in the transgenic knockout sickle cell mouse. 1007 13

The hypotransferrinemic mouse (trf (hpx)) is a mutant strain exhibiting transferrin deficiency, marked anemia, hyperabsorption of iron, and elevated hepatic iron stores. We set out to investigate the relative roles of anemia and of transferrin in the malregulation of intestinal iron absorption in these animals. Transfusion of erythrocytes obtained from littermate controls increased hemoglobin levels and reduced reticulocyte counts in recipient animals. Although mucosal to carcass (59)Fe transfer was reduced, total duodenal iron uptake was not significantly affected. Iron absorption in homozygotes, in contrast to littermate controls, was not reduced by hyperoxia. Mouse transferrin injections, in the short term, increased delivery of iron to the marrow and raised hemoglobin levels. Although mucosal transfer and total iron uptake were reduced at the higher transferrin doses, total uptake was still higher than in controls. Daily injections of mouse/human transferrin for 3 weeks from weaning, normalized hemoglobin values, and markedly reduced liver iron and intestinal iron absorption values in trf (hpx) animals. When such daily-injected mice were left for a week to allow transferrin clearance, iron absorption values were significantly enhanced; hemoglobin or hepatic iron levels were, however, not significantly altered. These data indicate that hyperabsorption of iron in trf (hpx) mice is not solely because of the anemia; transferrin levels per se do affect iron absorption, possibly via a direct effect on the intestinal mucosa.
 ...
PMID:Importance of anemia and transferrin levels in the regulation of intestinal iron absorption in hypotransferrinemic mice. 1055 6

The activities of superoxide dismutase (SOD) isoenzymes were measured in fourth instar larvae of Chironomus riparius Mg. Three types of superoxide dismutase were identified: Cu,Zn-SOD in hemolymph and postmitochondrial fraction; Mn-SOD in mitochondrial fraction and presumably Fe-SOD in postmitochondrial fraction. The latter could have an endosymbiotic or a parasitic origin. Extracellular and cytosolic SOD activities, especially Cu,Zn-SOD, tended to increase in the last phase of larval development, independently of protein or hemoglobin contents. This supposes that SOD activity in Ch. riparius larvae is probably activated at the end of fourth instar stage. Cu,Zn-SOD and Mn-SOD activities showed a significant increase under severe hypoxia and slight hyperoxia. Oxygen radical scavengers such as SOD may play a role in the increased tolerance of Ch. riparius to oxidative stress. These results suggest that the specific induction of some SOD isoenzymes could be used as a biomarker of environmental disturbance such as oxidative stress initiated by xenobiotics.
 ...
PMID:Characterization of superoxide dismutase activity in Chironomus riparius Mg. (Diptera, Chironomidae) larvae--a potential biomarker. 1057 51


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>