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Biomedical subjects

M Aberg

Publications and source records attributed to M Aberg.

At least 55 records · Page 3Linked to original sources
PubMed1980

Blood flow in small arteries after end-to-end and end-in-end anastomoses: an experimental quantitative comparison.

Microvascular anastomoses were performed under standardized conditions on the central artery of the ear in 23 rabbits. Fifteen end-to-end and 13 end-in-end anastomoses were compared. No anticoagulants or vasodilating agents, other than the local application of lidocaine, were used. Blood flow was measured by electromagnetic flowmetry before anastomosis and after anastomosis at intervals of 30 minutes for 4 hours and at 1 and 3 days. The validity of the electromagnetic flowmetry method was established in a control group of 7 rabbits. The mean volume of blood flow after end-to-end anastomosis was 93% of the preoperative value (P greater than 0.05). The corresponding mean volume of blood flow after end-to-end anastomosis was 47% of the preoperative value (P less than 0.001). The difference in flow between end-to-end and end-in-end anastomosis was highly significant (P less than 0.001). Microangiography demonstrated marked stenosis in the end-in-end anastomoses but not in the end-to-end anastomoses.

Animals↗
PubMed1979

Effect of dextran on factor VIII (antihemophilic factor) and platelet function.

Three different properties of factor VIII (antihemophilic globulin) were studied after infusion of 500 ml of six per cent Dextran 70 to healthy volunteers. This dose caused no change in the factor VIII coagulant activity while there was a significant but temporary decrease of factor VIII related antigen. The Ristocetin induced platelet aggregation analysed with native as well as with formalin-fixed platelets, also decreased significantly. The maximal decrease was found a few hours after the infusion. The decrease was seen only if Dextran was infused in vivo and not if Dextran was added to blood in vitro. The dysfunction of factor VIII caused by Dextran resembles that found in one variant of von Willebrand's disease. This finding probably explains the platelet function inhibiting properties of Dextran, and may be of significance for its antithrombotic effects.

Adolescent↗
PubMed1979

The effect of dextran on the platelet distribution and lysability of ex vivo thrombi in dogs.

Dextran infusion causes an increased lysability of ex vivo thrombi. This increased lysability is shown to be accompanied by a change in the distribution of 51Cr-labelled platelets. Rather than being localized to the head of the thrombus, after dextran infusion the platelets are found to be more evenly distributed. This change in platelet distribution is secondary to an effect of dextran on platelet function, probably via previously demonstrated impairment of the function of factor VIII. It is suggested that the increase in thrombus lysability is due to the change in platelet function.

Animals↗
PubMed1978

Fibrinolytic activity in the vein wall after surgery.

The fibrinolytic system, including the fibrinolytic activator activity of vein wall and fibrinolytic activity in blood after venous occlusion, was analysed in 43 patients before and on the third day after operation. Twenty-two of the patients underwent abdominoperineal amputation of the rectum and 21 had a cholecystectomy. The incidence of postoperative thrombosis was asssessed by means of the isotope method and phlebography. The results indicate that a decrease in fibrinolytic activity of the vein wall and/or in the release of fibrinolytic activator from the vein wall is a regular postoperative phenomenon, especially after major surgery. Malignant tumour of the rectum did not have any depressing effect on the fibrinolytic activator. All the patients with thrombosis after operation had a postoperative fibrinolytic defect of the vein wall compared with about 60 per cent of the other patients. It is concluded that postoperative changes in the parameters studied might be of significance for the development of thrombosis after operation.

Aged↗
PubMed1977

Effect of dextran on factor VIII and thrombus stability in humans. Significance of varying infusion rates.

The in vivo effect of dextran 70 on Factor VIII (antihemophilic factor) and thrombus stability has been studied in human volunteers after infusion at various rates. Varying the infusion time of dextran from 15 minutes to 2 hours did not result in any differences in the concentrations of dextran, fibrinogen and hematocrit, thus indicating similar degrees of hemodilution. Nor were any differences found in the effect of dextran on Factor VIII and thrombus stability. With regard to the antithrombotic function of dextran by hemodilution and effect on Factor VIII, there does not seem to be any advantage in giving dextran rapidly. This information could be of value in the treatment of elderly patients, for whom thrombosis prophylaxis is especially indicated and whose tolerance for hypervolemia is limited.

Clinical Trials as Topic↗
PubMed1977

Effect of dextran and induced thrombocytopenia on the lysability of ex vivo thrombi in dogs.

The lysability of thrombi and clots was studied in intact and thrombocytopenic dogs. The thrombi were formed in ex vivo in rotating. Chandler loops, the clots were formed in plastic tubes. Infustion of dextran 70 to the intact dogs was followed by a significant increase in the lysability of the thrombi but not of the clots. Thrombocytopenia caused an increase in the lysability of both thrombi and clots. After infusion of dextran to thrombocytopenic dogs a further increase was noted in the lysability of thrombi but not of clots. The results indicate that dextran and induced thrombocytopenia increase the lysability of thrombi by different mechanisms. The different behaviour between thrombi and clots is probably due to the difference in structure between them particularly with regard to the distribution of platelets. It is suggested that dextran decreased the thrombus statility by impairing the platelet surface function.

Animals↗
PubMed1976

Fibrinolytic activity in wound secretions.

Debrisan, a highly hydrophilic dextran polymer, was previously shown to be effective in cleaning infected wounds. The dry beads remove wound secretions from the wound surface under gel formation. The gel can then be analysed. A high fibrinolycic activity on fibrin plates and high levels of fibrin/fibrinogen degradation products were found in the secretions from 12 wounds. Low of plasminogen, antithrombin III and the absence of coagulable fribinogen also indicated a high fibrinolytic activity. A higher fibrinolytic activity on heated than on unheated fibrin plates, and the insignificant effect of local application of EACA suggest the presence of other proteolytic enzymes than plasmin.

Dextrans↗
PubMed1975

The effect of dextran on the lysability of ex vivo thrombi.

The lysability was determined of thrombi formed in Chandler tubes before and after infusion of 500 ml dextran 70 to patients undergoing cholecystectomy. 125I-labelled fibrinogen was given the day before operation. Following incubation of the thrombi formed in plasmin, radioactivity remaining in the thrombi and released to the supernatant was determined, as well as fibrinolytic degradation products in the supernatant, using an immunoelectrophoretic method. The dextran infusion was found to increase the radioactivity released from the thrombi to the supernatant from 15.5 plus or minus 7.6% to a maximum of 27.3 plus or minus 8.2% four hours after the infusion (P less than 0.001). A corresponding significant rise of the FDP concentration in the supernatant from 16.8 mug/ml to 44.1 mug/ml was found at the same time. After 24 hours the radioactivity had returned to initial values. The results indicate that dextran infused into patients during surgery increases the lysability of thrombi. It is suggested that this finding at least partly explains the antithrombotic effect of dextran.

Cholecystectomy↗
PubMed1975

Mechanism of plasminogen activator and factor VIII increase after vasoactive drugs.

Adrenaline, nicotinic acid (NA), vasopressin (LVP) and other drugs affecting vascular motility are known to increase plasminogen activator (PA) and factor-VIII plasma levels in man. To evaluate the hypothesis that NA, LVP and adrenaline release PA from the endothelial cells of the vessel wall through their common effect on vascular motility, PA has been characterized by means of a histochemical technique on vein biopsies obtained from human volunteers after infusion of the compounds. Furthermore, the effect of single and repeated administration has been compared in order to investigate whether the pattern of PA and factor-VIII variations in plasma is similar with the three drugs. There was no major difference in the PA content of the veins following the marked and sustained increase of the corresponding plasma activities. A simple explanation is that the intensity and duration of the stimulus may not be sufficient to deplete the large stores of the vessel walls. The magnitude, time course and duration of the plasmatic response after single and repeated infusions was on the whole different and peculiar for each drug. A derivative of LVP which is free of vasoactive actions was more effective than LVP in inducing the responses, which could also be elicited in two anephric subjects. These findings suggest that vasoactivity is unlikely to provide the clue to a common pathway for the fibrinolysis and coagulation response after the compounds, and support the existence of different specific receptors.

Adult↗