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Biomedical subjects

M Samama

Publications and source records attributed to M Samama.

At least 181 records · Page 10Linked to original sources
PubMed1984

Congenital protein C deficiency and thrombotic disease in nine French families.

Investigation of 118 patients for protein C deficiency using an immunological and a functional assay, and subsequent investigation of those (nine) found to be deficient, identified 22 patients (14 women, eight men) with protein C deficiency, of whom six were asymptomatic, 15 had histories of venous thromboembolism, and one had a history of arterial thromboembolism. Protein C deficiency was associated in the nine probands with young age at first episode of thromboembolic disease (mean 24.1 (SD 11.9) years), absence of a precipitating condition (five (56%], and a family history of thromboembolic disease (six (66%]. Investigation of the nine families suggested autosomal dominant transmission of the defect. Thromboembolic episodes were seen in patients with protein C antigen concentrations below 0.6 U/ml. Mean (SD) protein C antigen concentrations were 0.48 (0.12) U/ml in 18 patients not receiving oral anticoagulant treatment and 0.28 (0.05) U/ml in four receiving such treatment. One patient with severe protein C deficiency (0.16 U/ml) developed skin necrosis soon after starting oral anticoagulant treatment.

Adolescent↗
PubMed1984

Plasma beta-thromboglobulin in patients with valvular heart disease with or without valve replacement: relationship with thromboembolic accidents.

Plasma beta-thromboglobulin (BTG) was measured in 132 patients with valvular heart disease: 43 were studied before, 89 after surgery (78 mechanical valves and 11 bioprostheses). In this group of 89 selected patients, a history of thromboembolism was present in 53 (5 of them had bioprosthesis). Some abnormalities have been observed in patients with valvular heart disease as compared with controls: decreased platelet count and retention on glass column, and increased BTG. There is no statistically significant difference in BTG level between patients with (m +/- SD: 62.4 +/- 42.0 ng ml-1), or without (59.5 +/- 41.0 ng ml-1) a prosthesis; in the small series of 11 patients with a bioprosthesis, BTG was slightly lower than in other patients (44.5 +/- 14.1 ng ml-1), but still higher than in controls (26.8 +/- 13.3 ng ml-1). In the patients with a history of thromboembolism, BTG was significantly higher (66.7 +/- 47.9 ng ml-1 than in patients without this complication (49.9 +/- 21.0 ng ml-1). Thus, BTG evaluation may have some value in valvular heart disease but, at present, it should be confined to systematic research including prospective studies.

Adult↗
PubMed1984

Discriminant study of platelet volume indices in the etiological diagnosis of thrombocytopenia.

Platelet volume distribution was examined in 47 thrombocytopenic subjects with a platelet count between 20 X 10(9) and 150 X 10(9)/1. Thrombocytopenia was attributed to defective production in 19 cases (12 acute leukemia) and to accelerated destruction in 28 cases (27 idiopathic thrombocytopenic purpura). Six volume variables were retained from the platelet volume distribution curves. A multivariate discriminant analysis has shown that the median of the curves was the most discriminant parameter between the two types of thrombocytopenia: the value of the median was less than 7 micron 3 in 89.5% of patients with defective platelet production and greater than 7 micron 3 in 85.7% of those with excessive platelet destruction. Thus, platelet volume measurement and the median value in particular allows a rapid orientation of the etiological diagnosis of thrombocytopenia.

Acute Disease↗
PubMed1984

Spontaneous platelet aggregation in heparin-treated patients.

To evaluate the influence of heparin on spontaneous platelet aggregation (SPA) two groups of patients, one treated with heparin and the other without heparin, were compared. The frequency of SPA is highly increased in patients with prosthetic heart valves treated with heparin as compared to patients not treated with heparin. Thus, the high frequency of SPA in prosthetic heart valve carriers treated with heparin might be due either to the prosthesis itself or to heparin. In contrast, in patients with thromboembolic disease, SPA does not seem to be more frequent in heparin-treated than in untreated patients.

Adult↗
PubMed1984

Studies of the pathophysiology of acquired von Willebrand's disease in seven patients with lymphoproliferative disorders or benign monoclonal gammopathies.

In seven patients with acquired von Willebrand's disease (AvWD) associated with lymphoproliferative disorders or benign monoclonal gammopathies, the platelet contents of von Willebrand factor antigen and ristocetin cofactor (vWF:Ag and vWF:RiCof, respectively) were normal. All the multimers of vWF:Ag could be seen in the 1.6% SDS-agarose gel electrophoresis patterns of plasma and platelet lysates. Infusion of 1-deamino-8-D-arginine vasopressin (DDAVP) augmented plasma levels of vWF:Ag and vWF:RiCof of all patients and corrected prolonged bleeding times (BT). However, compared with patients with congenital vWD type I and comparable degrees of baseline abnormalities treated in the same way, vWF:Ag and vWF:RiCof were increased less and cleared more rapidly from plasma and the BT remained normal for a shorter period of time. These studies provide evidence that these AvWD patients have qualitatively normal vWF in plasma, but at lower concentrations, that vWF in platelets is normal both qualitatively and quantitatively, and that cellular vWF can be rapidly released into plasma by DDAVP to correct the hemostatic abnormalities. However, vWF is removed rapidly from plasma, making the correction more transient than in congenital vWD type I.

Adult↗
PubMed1984

[Biology of recurrent venous thrombosis].

Important recent advances in the field of the biology of recurrent venous thrombosis include greater understanding of congenital deficiency states involving antithrombin III (AT III) and protein C. Other disturbances demonstrated were related to fibrinolysis frequently, and rarely platelet function and coagulation factors. Possible existence of these anomalies requires investigation during biologic tests in cases of recurrent venous thrombosis, particularly in the presence of a family history or onset of the initial affection before 40 years of age. Confirmation of the importance of screening for such anomalies is supplied by results of a study of 11 families with antithrombin III deficiency and 9 families deficients in protein C, and a literature review of cases. However, currently available biologic tests provide data enabling only partial explanation of the mechanism underlying recurrent venous thrombosis accidents.

Antithrombin III Deficiency↗
PubMed1984

[Diagnosis of defibrination syndromes in infectious pathology].

Severe infections and particularly infectious shock are frequently accompanied by a varying degrees of disseminated intra-vascular coagulation (DIC). The mechanism at work is complex, involving endotoxin or bacterial lipopolysaccharide constituents that damage vascular endothelium and activate intrinsic coagulation, platelet function and the release of leucocyte coagulation-promoting compounds. The activation of coagulation in turn activates prekallikrein and complement and plays a part in shock. The laboratory plays an essential role in diagnosing DIC, determining its repercussions on the parameters of haemostasis and in monitoring its course under antibiotics, which in some cases may be combined with carefully controlled heparin treatment. Sensitive and specific tests are the assays for fibrinogen-fibrin degradation products (FDP) and soluble complexes (SC) using the haemagglutination test or the ethanol test. The platelet count should be combined with measurement of the bleeding time. A varying degree of thrombopenia is frequent but non specific. In cases of septicemia, it is an early warning sign. A selective fall in proaccelerin is an indirect early sign. A fall in antithrombin III (AT III) is considered a good sign of DIC but it does not occur in every case, and is most liable to be present in liver failure. From the FDP and fibrinogen results, it should be clear whether one is dealing with compensated, decompensated or even over-compensated DIC. Diagnosis should be complemented by a careful search for the clinical signs of coagulation and haemorrhage. It is indispensable for investigations to be repeated every 6-12 hours, for the sake both of treatment strategy, which can be extremely difficult, and DIC monitoring.

Antithrombin III Deficiency↗
PubMed1983

Intra-coronary thrombolysis with streptokinase or lys-plasminogen/urokinase in acute myocardial infarction: effects on recanalization and blood fibrinolysis.

Forty-two patients with total occlusion of a coronary vessel were treated with intracoronary fibrinolytic agents. Four therapeutic protocols were compared: group I received streptokinase (SK) as a continuous infusion; group II and III received SK as a bolus at different doses and group IV received lysplasminogen (Pg) plus urokinase (UK); maximal doses were 350,000 IU of SK and 250,000 IU of UK plus 75 microK of Pg. Thrombolysis was assessed by coronary angiography. Coagulation studies were performed prior to, 15 min and 6 hr after the end of the thrombolytic treatment. Recanalization was achieved in 27 of the 31 SK-treated patients (87%) and in 7 of the 11 Pg-UK-treated patients (63.6%). The recanalization frequency was the same in the three SK-treated groups, even though when SK was administered as a bolus, the dose was significantly less than when administered on a continuous infusion. Although systemic fibrinolysis occurred in all 4 groups of patients, this effect was less pronounced in the UK-treated patients than in the three SK-treated groups. This study also shows that recanalization can be achieved with a dose of SK lower than the anti-SK antibody level. Haemorrhagic side effects were minimal in all patients studied. Severe defibrination is usually considered a risk of haemorrhage. These preliminary results suggest that bolus injection of SK or the use of UK plus lys-Pg can reduce the level of defibrination and thus the haemorrhagic risk.

Adult↗
PubMed1983

[Congenital dysfibrinogenemia. Apropos of 13 cases].

Approximately 100 families with congenital dysfibrinogenemia have already been reported in the literature. We have had the opportunity to study 13 affected families in France. The study of these dysfibrinogenemias has two purposes: 1) analysis of the relationships between the structural and functional abnormalities of the fibrinogen defect, since it appears that, in a significant percentage of dysfibrinogenemias, recurrent thrombosis has been observed. The diagnosis of dysfibrinogenemia is easily presumed in hemostasis laboratories since it rests upon prolonged thrombin and/or reptilase clotting times and the discrepancy between the fibrinogen levels obtained by an immunological method and a coagulation method. Many studies have been carried out during the last few years, and in at least seven cases the fibrinogen molecular defect has been elucidated.

Adolescent↗