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Biomedical subjects

T Ostrem

Publications and source records attributed to T Ostrem.

13 recordsLinked to original sources
PubMed1978

Plasma cholesterol esterification and plasma lipoproteins in bile-duct-ligated dogs.

To study the lipoprotein changes in cholestasis while the capacity for plasma cholesterol esterification was normal, the common bile duct was ligated in dogs and plasma investigated 8 h and 48 h later. The plasma concentration of cholesteryl esters was slightly increased, concomitant with a tendency toward an increase in the activity of lecithin:cholesterol acyltransferase (LCAT). The content of cholesteryl esters in the main lipoprotein classes was normal. Marked alteration in the low density lipoproteins (LDL) and the high density lipoproteins (HDL) took place and were essentially similar 8 h and 48 h after bile duct ligation. In LDL, (density 1.006--1.019 g/ml) and LDL2 (density 1.019--1.063 g/ml) an increase in the content of polar lipids was observed, and in LDL2 heterogeneity in particle size was demonstrated by gelfiltration on 2% agarose and by electron microsopcy. Large myelin structures, flattened disc-shaped particles, and particles with the appearance of normal LDL2 were present. HDL isolated after operation was characterized by a decreased protein/lipid ratio and an increased content of phospholipids. By gelfiltration on Sephadex G-200 and by electron microscopy changes in particle size were observed, with the presence of disc-shaped particles with a tendency in form rouleaux. These results demonstrate that marked lipoprotein changes occur as early as 8 h after bile duct-ligation in dogs and indicate that a deficient LCAT mechanism is present in cholestasis even with normal or high plasma LCAT activity.

Animals↗
PubMed1977

Determination of effective orifice area in mitral stenosis from non-invasive ultrasound Doppler data and mitral flow rate.

Ten patients with mitral stenosis, but without mitral insufficiency, have been studied during cardiac catheterization. The mitral orifice blood velocities, the mitral pressure gradient, and the mitral flow rate were determined with ultrasound, manometry, and the direct Fick method, respectively. The effective orifice area was calculated from the ultrasound data and the mitral flow rate. The geometric orifice area was calculated from the pressure gradient and the mitral flow rate, using a revised Gorlin formula. A comparison of the two methods showed a correlation coefficient of 0.975. The investigation demonstrated that the ultrasound method represents an alternative to the conventional catheterization methods used for the quantification of mitral flow obstruction.

Blood Flow Velocity↗
PubMed1977

Hypoxanthine levels of plasma during hypoxemia in dogs.

Tissue hypoxia was induced in one group of dogs by clamping of the endotracheal tube and in another group by artificial ventilation with a mixture of nitrogen and air. The hypoxanthine concentration of venous and arterial plasma increased significantly during severe hypoxemia. When the hypoxemia was relieved, an increased venous-arterial hypoxanthine difference appeared indicating that the lung metabolism of hypoxanthine was slowed down during alveolar hypoxia. It is concluded that the level of plasma hypoxanthine in dogs during hypoxemia is dependent on the degree of tissue hypoxia, peripheral vasoregulation, and lung metabolism.

Animals↗
PubMed1977

Hypoxanthine and urate levels of plasma during and after hemorrhagic hypotension in dogs.

The plasma hypoxanthine concentrations increased during hemorrhagic hypotension in dogs. A venous-arterial hypoxanthine difference was found indicating metabolism of hypoxanthine in the lungs. A maximal hypoxanthine level was found during the hypotension, then the level decreased. This probably reflects peripheral vasoconstriction. During reinfusion of the blood, a new hypoxanthine peak was observed. The urate levels also increased during the hypotension. An arterial venous difference was found. This probably illustrates that hypoxanthine is metabolized to urate in the lungs. It is concluded that the increase of plasma hypoxanthine concentrations might reflect tissue hypoxia.

Animals↗
PubMed1975

Conjugation of non-erythroid bilirubin in chronic experimental cholestasis in the dog.

The dynamics of conjugation of 14C-bilirubin injected intravenously during cholestasis is known from studies in rats and dogs. No studies have been performed concerning the conjugation of non-erythroid bilirbuin (NEB), i.e. the 10-20% of bilirubin synthesized from tissue haemes, mainly in the liver. This study reports the results of experiments in four dogs subjected to extra-hepatic cholestasis of 7-14 days' duration. delta-Aminolevulinic acid-5-C14HCi was injected intravenously as a NEB precursor. The appearances of unconjugated and conjugated labelled NEB as well as of the different azopigments were followed in systemic blood, liver vein blood, and thoracic duct lymph. The first NEB to appear was unconjugated; maximal concentration of unconjugated NEB in peripheral and liver vein blood was reached within one hour. The amount of conjugated NEB in both vascular compartments increased for two to three hours, after which time the degree of conjugation stabilized. The degree of conjugation was higher in liver vein than in peripheral blood for the first two hours. The same azopigments of NEB were found as for injected 14C-bilirubin. The a0 azopigment (azobilirubin) was present in higher amounts in peripheral than in liver vein blood, all the other azopigments were present in higher amounts in liver vein blood.

Aminolevulinic Acid↗