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Biomedical subjects

F Fabris

Publications and source records attributed to F Fabris.

At least 163 records · Page 9Linked to original sources

Normal and low molecular weight heparins: interaction with human platelets.

Porcine mucosal heparin was chemically depolymerized. The depolymerization was stopped at different steps to obtain two low molecular weight (LMW) heparins with a molecular weight of 10 000 and 6000, respectively. The LMW heparins were tested in vitro for anti-clotting activities and for platelet serotonin release in different systems in comparison with normal heparins, dermatan and heparan sulphate. After addition of various amounts of heparin preparations to washed platelets, no significant release was observed for all tested heparins. On the contrary, different heparins showed an inhibition of serotonin-release induced by collagen in platelet rich plasma, whereas the ADP-induced release was increased. The effect on the platelet release appears related to the molecular weight. In fact, it is significant only for normal heparins whereas it is not for LMW heparins. A good relation was observed, also, between anti-activated factor X activity/antiglobal clotting activity (Xa/APTT) ratio of different heparins and the effect on platelet release.

Adenosine Diphosphate↗

Clotting changes in Cushing's syndrome: elevated factor VIII activity.

Thirteen women and 2 men affected by Cushing's syndrome were investigated. The following parameters were used: plasma and urinary cortisol levels, factor VIII assay (antigen, activity and von Willebrand factor) together with other coagulative assays. Samples were taken before surgery or before medical and/or radiation therapy and every 30-50 days after treatment and continued for 11 months. Cortisol and factor VIII were increased before treatment and decreased slowly after treatment to become normal in 3-4 months. Other clotting tests did not show any significant changes. High plasma cortisol levels seem to stimulate the production of factor VIII. Patients with Cushing's syndrome often exhibit thromboembolic complications after surgery. The clotting abnormalities responsible for such complications may be due to increased factor VIII activities.

Adrenalectomy↗

Failure of sulphinpyrazone to affect platelet survival in patients with rheumatic heart valvular disease: a double blind study using 75Se-methionine labeled platelets.

We have investigated platelet survival time in 18 patients suffering from valvular heart disease. Platelet survival was performed using the 75Se-methionine method modified by us. Nine of our eighteen patients underwent surgery for heart valve replacement. Platelet survival time was performed before treatment and six months afterwards with placebo or sulfinpyrazone in a double blind study. Before treatment and surgery, platelet survival time was significantly reduced in patients with a history of embolism (P less than 0.0048). In patients receiving valve replacement, platelet survival time was shortened both in the sulfinpyrazone and placebo groups six months after surgery. Of the nine patients not receiving prostheses and with a thrombotic history, treatment with placebo and sulfinpyrazone resulted in improved platelet survival times.

Adult↗

Increased factor VIII associated activities in Cushing's syndrome: a probable hypercoagulable state.

Thirteen women and 2 men affected by Cushing's syndrome were investigated. The following parameters were used: plasma and urinary cortisol levels, factor VIII assay (antigen, activity and von Willebrand factor) together with other coagulative assays. Samples were taken before surgery or before medical and/or radiation therapy and every 30-50 days after treatment and continued for 11 months. Cortisol and factor VIII were increased before treatment and decreased slowly after treatment to become normal in 3-4 months. Other clotting tests did not show significant changes. It seems that high plasma cortisol levels may stimulate the production of factor VIII. Patients with Cushing's syndrome often exhibit thromboembolic complications after surgery. It is likely that the clotting abnormalities responsible for such complications is the increased factor VIII activities level.

Blood Coagulation Disorders↗

Potentiation of anticoagulant response to warfarin by sulphinpyrazone: a double-blind study in patients with prosthetic heart valves.

The effect of Sulphinpyrazone on the anticoagulant response to Warfarin was evaluated by a double-blind study in 11 patients with prosthetic heart valves. Six patients received Warfarin and Sulphinpyrazone and 5 Warfarin and placebo. Sulphinpyrazone potentiated the anticoagulant effect of Warfarin. Patients receiving Sulphinpyrazone needed about half the amount of Warfarin as compared to the control group. There were four bleeding episodes in the Sulphinpyrazone group and one episode in the control group. It was difficult to regulate the dose of Warfarin in patients also receiving Sulphinpyrazone.

Adult↗

75Se-methionine platelet survival studies: a proposal for a mathematical correction of the curve.

We studied platelet survival in 14 cardiac before heart valve replacement using 75Se-methionine 'cohort label'. The temporal variation of plasma and platelet activity was plotted by a continuous curve by means of a computerized interaction of the single points. Then we computed the plasmatic radioactivity fraction used daily for thrombopoiesis and made a subtraction of this aliquot from a experimental activity in the catabolic phase of the slope. Platelet life span obtained after this 'correction' is comparable with the values of random label using 51Cr.

Adult↗

The possible value of platelet aggregation studies in patients with increased platelet number.

ADP, adrenalin and collagen platelet aggregation studies were performed in 54 patients with elevated platelet counts: 38 patients showed primary thrombocythemia and 16 secondary thrombocytosis. Patients with primary thrombocythemia (78.7%) showed a decrease aggregation pattern while in patients with secondary thrombocytosis platelet aggregation response was entirely normal. An increase in platelet aggregation was obtained in four patients with primary thrombocythemia. The platelet aggregation response did not appear to be related to circulating platelet number. A relationship between increased platelet aggregation and the occurrence of thrombosis was demonstrated. Similarly, a correction between impaired platelet aggregation and bleeding was also present. These results emphasize the diagnostic value of platelet aggregation studies in patients with elevated platelet number.

Adenosine Diphosphate↗

In vitro and in vivo effects of ditazol on human platelets malonylaldehyde (MDA) production.

Ditazol (4,5-diphenyl-2 bis-hydroxyethylaminoxazol) was tested with regard to its effect in vivo and in vitro on platelet malonyladehyde (MDA) production which seems to be a good marker of prostaglandins metabolism. The drug is a powerful inhibitor of platelet MDA Production induced by thrombin in vitro and this action seems to be due to a "competitive" type effect. "In vivo" experiments showed a significant inhibitory effect on platelet MDA production 4--6 hours after administration of the drug, with return to basal levels within 24 hours.

Adult↗

Improvement of platelet aggregation abnormalities in thrombocytosis after thrombocytopheresis.

Platelet function tests were performed in three patients with thrombocytosis in myeloproliferative disorders before and after a swift reduction of platelet count by thrombopheresis. The decrease of platelet count obtained after the procedure was reversed in six days. In two patients with platelet aggregation defects, the normalization of aggregation abnormalities was observed after pheresis, followed by a progressive decrease of platelet response until the pre-pheresis values on 6th day. In the third patient with normal platelet aggregation, a progressive increase of platelet aggregation response was noted on the days following thrombopheresis with ischaemic symptoms of a foot toe. In all three patients, the changes of platelet aggregation were accompanied by a related increase of megathrombocytes. In the two patients with platelet aggregation abnormalities, plasma and platelet beta-thromboglobulin levels were related to changes in platelet count and aggregation.

Adult↗