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Biomedical subjects

P Ortenwall

Publications and source records attributed to P Ortenwall.

44 records · Page 3Linked to original sources
PubMed1988

Splenic platelet kinetics and platelet production after major reconstructive vascular surgery.

By using 111In-labelled platelets and dynamic gamma camera scintigraphy, platelet production rate and intrasplenic platelet kinetics were determined in 13 patients at 1 and 4 months after aortic reconstructive vascular surgery with implantation of dacron prostheses. A significant decrease in platelet production rate and venous platelet count was recorded over time after surgery. Irrespective of whether the exchangeable splenic platelet pool was estimated from initial recovery of platelet-bound radioactivity or from compartmental analysis, the size of this pool was significantly lower at the first study; a change in intrasplenic platelet transit time accounted for the observed difference. Platelet mean life-span increased over time after surgery but the difference between the duplicate studies was not statistically significant. It can be concluded that there is a reduction of platelet production rate and venous platelet count over time after major reconstructive vascular surgery. The early postoperative elevation in the platelet count is mainly the result of an increased platelet production and to a lesser degree due to redistribution of platelets between the splenic platelet pool and general circulation.

Aged↗
PubMed1988

Seeding of ePTFE carotid interposition grafts in sheep and dogs: species-dependent results.

Autologous endothelial seeding of thin-walled ePTFE vascular prostheses (I.D.4 mm), interposed in the carotid artery, was performed in 10 dogs and 14 sheeps. Aspirin (250 mg/day) and dipyridamole (75 mg/twice daily) were given throughout the study as antiplatelet therapy. Animals were killed 2 and 5 weeks after surgery. Patency rates for seeded grafts in dogs were 75% (6:8) and 83% (10:12) at 2 and 5 weeks, respectively. In control grafts the patency rates were identical. Patency rates for seeded grafts in sheep were 0% (0:5) and 11% (1:9) at 2 and 5 weeks, respectively. Control grafts in sheep had a patency rate of 40% (2:5) and 0% (0:9) at corresponding times. Scanning electron microscopy showed an almost complete endothelialization of seeded grafts in dogs after 5 weeks. Platelet deposition was studied in the dogs by means of chromium-51-labeled autologous platelets. Significantly fewer platelets accumulated on seeded grafts, and the ratio of 6-keto-PCF1 alpha to thromboxane B2 was significantly higher, compared with unseeded grafts, which indicated the presence of a functionally active endothelial lining in seeded grafts. Differences in the hemostatic system could account for the high clotting incidence in sheep, compared with that in dogs. Such species differences make extrapolations to the clinical situation from autologous endothelial seeding in experimental animals hazardous.

Animals↗
PubMed1987

Comparison of oxidative metabolism in vitro in endothelial cells from different species and vessels.

Oxygen consumption was compared in confluent cultures of endothelial cells from human umbilical cord veins, rat pulmonary arteries, and bovine aortas. A microrespirometric method utilizing oxygenated hemoglobin as oxygen supply and indicator of respiration was used. Respiratory rate was equal in human and murine cells (2.0 X 10(-6) and 2.2 X 10(-6) microliters O2/cell/hour respectively), compared on a cell-to-cell basis, while respiratory rate of the bovine endothelium was significantly lower (0.4 X 10(-6) microliters O2/cell/hour) (P less than .001).

Animals↗
PubMed1987

Reduction in deposition of indium 111-labeled platelets after autologous endothelial cell seeding of Dacron aortic bifurcation grafts in humans: a preliminary report.

Autologous endothelial seeding (AES) of vascular prostheses in dogs increases thrombus-free surface and improves prosthetic prostacyclin production, patency, and the ability to withstand hematogenous challenge with bacteria. No such information is available in human subjects. In the present study one limb of an aortic Dacron bifurcation prosthesis was seeded with autologous endothelial cells (ECs) harvested from the distal portion of the saphenous vein by enzymatic treatment. The deposition of indium 111-labeled platelets on the vascular prostheses was studied 1 and 4 months after operation. In seven of nine patients seeding resulted in decreased accumulation of radiolabeled platelets compared with sham-seeded control limbs (p less than 0.04), when studied 1 month after surgery. A decrease in platelet accumulation occurred over the whole prosthesis between 1 and 4 months, and no significant difference was noted at 4 months between seeded and nonseeded graft limbs. Although the seeding density was very low (440 ECs/cm2), the observed difference in platelet accumulation for AES-treated graft limbs in the early postoperative course merits further investigation of this technique in human beings.

Aged↗
PubMed1987

Prognostic value of consecutive peripheral pressure registration after reconstructive peripheral arterial surgery.

A reliable predictive test as a guide in selection for arterial reconstruction vs. primary amputation would be of great value. An ideal test should also be simple and noninvasive. We evaluated prediction based on preoperative and early postoperative (repeatedly in the first week) measurements of ankle and toe pressure in relation to patency 6 months after reconstructive peripheral vascular surgery in 39 patients. Occlusion occurred within 6 months in ten patients. In eight of them the preoperative ankle-brachial pressure index (ABI) was less than 0.4, but seven other patients with ABI less than 0.4 had maintained patency. In six of the ten with occlusion the toe-brachial pressure index (TBI) was less than 0.1, but in three others with TBI less than 0.1 the grafts were patent. During the first postoperative week there was progressive rise in pressure indices, reaching statistical significance on day 6, though with greatest rise on day 1. Although preoperative ABI less than 0.4 and TBI less than 0.1 were associated with high occlusion risk, the specificity of these indices was too low for predictive value. The repeated measurements during postoperative week 1 added no useful information to that obtained on day 1.

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PubMed1985

Effects of 5-hydroxytryptamine and related agents on endothelial cell oxidative metabolism in vitro.

A recently described microrespirometric method was used to determine the influence of 5-hydroxytryptamine (5-HT), nialamide, imipramine and ouabain alone and in combinations on oxidative metabolism in monolayer cultures of endothelial cells from the rat pulmonary artery. It was found that exposure to 5-HT increased oxygen uptake in the cultures, while imipramine or ouabain decreased respiration; nialamide had no obvious effect. When used in combinations, the effect of ouabain or imipramine dominated over the 5-HT effect. The explanation for this 5-HT stimulating effect on endothelial cell oxidative metabolism, previously undescribed, is suggested to be that 5-HT exposure stimulated individual cells to contract. This active contraction resulted in an increased energy demand reflected in elevated oxygen consumption, an effect inhibited by ouabain or imipramine.

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