Search results for "partial pressure"
showing 10 items of 145 documents
Cooperative Transition in the Conformation of 24-Mer Tarantula Hemocyanin upon Oxygen Binding
2005
Hemocyanins are large respiratory proteins of arthropods and mollusks, which bind oxygen with very high cooperativity. Here, we investigated the relationship between oxygen binding and structural changes of the 24-mer tarantula hemocyanin. Oxygen binding of the hemocyanin was detected following the fluorescence intensity of the intrinsic tryptophans. Under the same conditions, structural changes were monitored by the non-covalently bound fluorescence probe Prodan (6-propionyl-2-(dimethylamino)-naphthalene), which is very sensitive to its surroundings. Upon oxygen binding of the hemocyanin a red shift of 5 nm in the emission maximum of the label was observed. A comparison of oxygen binding c…
Geo-economic variations in epidemiology, patterns of care, and outcomes in patients with acute respiratory distress syndrome: insights from the LUNG …
2017
Background Little information is available about the geo-economic variations in demographics, management, and outcomes of patients with acute respiratory distress syndrome (ARDS). We aimed to characterise the effect of these geo-economic variations in patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE). Methods LUNG SAFE was done during 4 consecutive weeks in winter, 2014, in a convenience sample of 459 intensive-care units in 50 countries across six continents. Inclusion criteria were admission to a participating intensive-care unit (including transfers) within the enrolment window and receipt of invasive or non…
Blood flow, oxygenation, metabolic and energetic status in different clonal subpopulations of a rat rhabdomyosarcoma.
1998
Differentiation of a tumor plays an important role in terms of biological aggressiveness. The question arises as to whether this is reflected in differences in the metabolic and energetic status of solid tumors. The aim of this study was to analyze the influence of clonal tumor cell differentiation on the microenvironment of rat rhabdomyosarcomas. Two distinct lines of a rhabdomyosarcoma (BA-HAN-1) with different histomorphological properties were used (line F1, co-existence of mononuclear stellate cells and multinuclear myotube-like giant tumor cells; G8, polygonal, mononuclear tumor cells). Solid tumors were grown s.c. on the hind food dorsum of Lewis rats. Tumor oxygenation was measured …
Influence of intracellular convection on the oxygen release by human erythrocytes
1972
There is general agreement today that intracellular diffusive transport of HbO2 and O2 limits the rate of oxygen uptake or release by the blood in the exchange vessels. Recent hemorheological results have shown that the mammalian erythrocyte exhibits fluidity as its most unique rheological property: it can be deformed continuously and rapidly, shear and normal stresses can be transmitted to the interior of the cell where systems of laminar flow are induced. These mechanical properties lead to the question whether or not intracellular convection does take place in the erythrocyte and to what extent it plays a part in gas exchange. A method was developed which subjects oxygen-saturated soluti…
Surgical procedure affects physiological parameters in rat myocardial ischemia: need for mechanical ventilation.
1999
Several surgical approaches are being used to induce myocardial ischemia in rats. The present study investigated two different operative procedures in spontaneously breathing and mechanically ventilated rats under sham conditions. A snare around the left coronary artery (LCA) was achieved without occlusion. Left lateral thoracotomy was performed in spontaneously breathing and mechanically ventilated rats (tidal volume 8 ml/kg) with a respiratory rate of 90 strokes/min at different levels of O2 supplementation (room air and 30, 40, and 90% O2). All animals were observed for 60 min after thoracotomy. Rats operated with exteriorization of the heart through left lateral thoracotomy while breat…
The Effects of Sodium Nitroprusside-Induced Hypotension on Splanchnic Perfusion and Hepatocellular Integrity
1999
UNLABELLED The purpose of our study was to investigate the effects of sodium nitroprusside-induced hypotension on splanchnic perfusion and hepatocellular integrity. Thirty patients undergoing radical prostatectomy were allocated randomly to a sodium nitroprusside (SNP) or control group (control). Regional pco2 was measured using gastric tonometry, and the regional to arterial difference in partial pressure of CO2 and intramucosal pH were calculated. The cytosolic liver enzyme alpha-glutathione S-transferase and standard liver enzyme markers (alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyltransferase) were also measured. Mean arterial pressure in the SNP group was 50…
Pulmonary function and complications after laparoscopic cholecystectomy
1998
Objective: To investigate the impairment of pulmonary function and complications after laparoscopic compared with open cholecystectomy through an upper midline incision.Design: Prospective randomised trial.Setting: Teaching hospital, Spain.Subjects: 40 patients, 20 in each group.Interventions: Clinical examination, spirometry, arterial blood gas analysis, and chest radiographs before and after operation.Results: 48 hours postoperatively FVC and FEV had decreased to 56.7% and 53%, respectively, in the patients who had had open cholecystectomy, compared with 85.3% and 84.8% in the laparoscopic group (p < 0.0001). The mean (SD) postoperative percentage reductions in both Pa02 (86.1 (11.1) comp…
Modulation of Spatial O2Tension Distribution in Experimental Tumors by Increasing Arterial O2Supply
1995
Tumor oxygenation has been measured polarographically in s.c. implanted DS-sarcomas on the dorsum of the hind foot of male Sprague-Dawley rats. pO2 was determined in all 3 spatial dimensions and 3-dimensional pO2 distributions as well as the mean extent of confluent areas with pO25 mmHg were calculated. Finally, the effect of elevating arterial pO2 (by carbogen breathing) as well as of increasing tumor blood flow (by angiotensin infusion) on the spatial pO2 distribution was analyzed. Depending on the tumor volume, the spatial pO2 distribution is more or less anisotropic. In smaller tumors, areas with physiological pO2 values are found adjacent to large hypoxic areas whereas larger tumors ar…
Tumor Oxygenation in Anemic Rats: Effects of Erythropoietin Treatment Versus Red Blood Cell Transfusion
1995
Anemia was induced in rats by the development of a hemorrhagic ascites. These animals also bore solid tumors (DS-sarcomas) on the hind foot dorsum. The effects of two methods for anemia correction on oxygenation in the solid tumors were compared in this study. Anemia was corrected either chronically by erythropoietin administration (1000 IU/kg) over 14 days (EPO) or acutely by transfusion with red blood cells (TR). Non-anemic and untreated anemic animals served as controls. Tumor oxygenation was determined in anesthetized animals using polarographic needle electrodes and pO2 histography. The reduction in hematocrit and hemoglobin content found in anemic animals could successfully be correct…
Changes inα-tocopherol and retinol levels during cardiopulmonary bypass correlate with maximal arterial partial pressure of oxygen
2007
Cardiopulmonary bypass (CPB) is associated with oxidative stress. This study examined antioxidant levels in adults undergoing CPB surgery and their correlation with clinical variables. Arterial blood samples were obtained from 27 patients undergoing CPB. The time-course variation of vitamin C (spectrofluorimetry), alpha-tocopherol and retinol (HPLC) levels were determined. Plasma vitamin C rose initially but gradually decayed during reperfusion until 60% reduction of baseline values post-surgery. alpha-Tocopherol and retinol were reduced along CPB with post-operative values approximately 25% lower than baseline. No significant changes were found for selenium and glutathione peroxidase. PaO(…