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Biomedical subjects

T Barbui

Publications and source records attributed to T Barbui.

At least 271 records · Page 15Linked to original sources
PubMed1981

Platelet activation in myeloproliferative disorders.

Beta-thromboglobulin (beta-TG) and platelet factor four (PF4) are specific platelet proteins released when a process of platelet activation occurs. The present study was undertaken in order to measure beta-TG and PF4 both as absolute plasma value and ratio to platelet number in 69 patients with myeloproliferative disorders (MD). The aim was to establish whether the increase of the two proteins could depend on platelet number or indicated an "in vivo" platelet activation. In 74% of patients beta-TG was found elevated and PF4 was high in 68% of cases. However in 34.7% and in 31.9% of cases respectively, the elevation of the two platelet markers was correlated to platelet number and the ratio was normal. Only in about one third of cases an "in vivo" platelet activation could be admitted and this finding provides a more rational use of antiaggregating agents.

Adolescent↗
PubMed1981

Reduced generation of procoagulant activity by endotoxin-stimulated mononuclear cells from patients with chronic myeloid leukaemia.

The capacity of blood mononuclear cells to produce procoagulant activity upon stimulation with bacterial endotoxin in vitro was studied in 21 untreated patients with chronic myeloid leukaemia (CML). Procoagulant activity developed by patients' cells after prolonged incubation with endotoxin was significantly lower than that produced by cells from a matched control group (P less than 0.001). Reduced activity was seen in all patients when each of them was compared to a matched control studied simultaneously. It was below 50% of the control in 19 patients, and in eight of these it was less than 10%. These findings suggest that qualitative abnormalities in mononuclear cell function may exist in CML and might explain why these patients are less prone to thrombotic complications than those with other myeloproliferative diseases.

Adult↗
PubMed1981

Reduced platelet factor X-activating activity: a possible contribution to bleeding complications in polycythaemia vera and essential thrombocythaemia.

A recently described platelet coagulant activity, factor X-activating activity (FXAA), was studied in 33 patients with polycythaemia vera and in 5 with essential thrombocythaemia, in order to gain information about possible mechanisms responsible for the haemostatic disorders observed in myeloproliferative diseases. Other parameters of platelet function including bleeding time, spontaneous and ADP-, epinephrine- or collagen-induced platelet aggregation, serotonin content and malondialdehyde (MDA) production in response to thrombin, were investigated simultaneously. Compared to the range obtained from 27 control subjects (60-150%), FXAA was low in all 9 patients with bleeding complications (range: 5-39%), in 1 out of 7 patients with thrombotic manifestations (range: 38-200%) and in 9 out of 22 patients without symptoms (range: 38-500%). Only the bleeding group differed significantly from each of the others. Moreover, of all patients with reduced FXAA, those with bleeding could be clearly distinguished from those without such symptoms on the basis of the degree of the defect. Increased FXAA (above 150%) was found in 2 out of 7 thrombotic patients and in 2 out of 22 asymptomatics. MDA production was significantly lower in the haemorrhagic group and enhanced in the thrombotic one as compared to control subjects or asymptomatic patients. However, a large area of overlap was observed between the four groups. None of the other platelet function parameters studied (bleeding time, platelet aggregation, platelet serotonin content) correlated with the clinical type of haemostatic complication. Our results suggest a significant association between reduced FXAA and bleeding tendency. These findings may be of relevance in understanding the pathogenesis of abnormal bleeding in patients with polycythaemia vera and essential thrombocythaemia.

Adolescent↗
PubMed1981

Subunit A of factor XIII regulates subunit B plasma concentration.

Subunit a of Factor XIII is found absent in homozygotes and reduced in heterozygotes. Since a concomitant reduction of subunit b occurs in these cases, an interaction between the loci controlling the synthesis of the two subunits was suggested. However in the present study we have shown that the administration of subunit a in two totally devoid homozygotes produced an increase of subunit b, reaching the maximum concentration five days after infusion. This strongly suggests that subunit b plasma level is regulated on the subunit a plasma amount.

Biological Availability↗
PubMed1980

Abnormal aggregation and increased size of platelets in myeloproliferative disorders.

Platelet aggregation is frequently impaired in myeloproliferative disorders (MPD). The presence of spontaneous platelet aggregation (SPA) or alterations of the aggregation pattern after ADP, epinephrine and collagen have been a frequent feature in the series of 52 patients here presented. The occurrence of SPA was not related to the findings obtained with the aggregating agents or to the number of circulating platelets. The aggregation results did not correlate with the number of megathrombocytes. The presence of platelet abnormalities, not completely corrected after busulfan therapy, and the increased size of platelets should aid in diagnosis of myeloproliferative disorders.

Adult↗
PubMed1980

Fibrin cross-linking in congenital factor XIII deficiency.

Homozygous patients with factor XIII deficiency are devoid of immunologically identifiable A protein, the active enzymatic component. Quantitative studies of transamidase activity of the factor are available in only a few cases, and the fibrin cross-linking pattern is not well known. The present paper deals with the quantitative estimation of factor XIII transamidase activity (dansylcadaverine system), factor XIII molecular subunits, and the corresponding fibrin cross-linking pattern in seven homozygous patients with factor XIII deficiency. The results indicate that transamidase activity was present in all patients, and the range was 0.5-1.7%. The pattern of fibrin stabiisation showed an absence of cross-linking in two patients, the presence of gamma-gamma-dimers (traces) in four, and gamma-gamma-dimers plus incomplete alpha-polymers (traces) in one patient. In conclusion, the homozygous patients reported here were not completely devoid of functioning factor XIII.

Electrophoresis, Polyacrylamide Gel↗
PubMed1978

Subunits A and S inheritance in four families with congenital factor XIII deficiency.

Previous studies of the inheritance of the two molecular subunits of fibrin stablizing factor (factor XIII) refer to isolated cases. The present work investigates the hereditary mode of transmission of subunits A and S, measured by the Laurell technique, in seven homozygotes and in 29 heterozygotes belonging to four families with factor XIII deficiency. The results indicate that the homozygotes were devoid of immunologically identifiable A subunit, whereas the heterozygotes could be identified by measuring this protein. The subunit S has been found to be decreased both in homozygous and in heterozygous patients, so that it seems that the two subunits, even if their synthesis is controlled by different genes, are genetically related. The mode of transmission of this disorder, supported by quantitative determinations of plasma subunit A, is autosomal recessive.

Factor XIII↗
PubMed1977

The aspirin tolerance test in von Willebrand's disease.

Opinions about the clinical value of aspirin tolerance test proposed by Quick von Willebrand's disease are conflicting. The results of the present study seem to support the view that a platelet defect, induced by aspirin, causes a significant lengthening of bleeding time only in the cases with severe von Willebrand factor deficiency.

Aspirin↗