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Biomedical subjects

M Samama

Publications and source records attributed to M Samama.

At least 235 records · Page 13Linked to original sources
PubMed1980

Standardization of platelet counts--problems and pitfalls.

In a previous work, we have compared two automated techniques for platelet-rich plasma using a thrombocounter or whole blood with the continuous flow instrument Auto-analyzer (AA). More recently, we have tested two instruments using whole blood: the first one, fully automated: Coulter S+; and the other one, semi-automated: Clay-Adams. In the present work, these 4 methods are compared to the phase contrast microscope technique, used as reference. The coefficients of variation ranged between 2 and 13 per cent. The coefficients of correlation between the different methods were between 0.92 and 0.96. Platelet distribution curves for platelet volumes obtained in parallel with platelet-rich plasma and with whole blood in 30 controls, show that platelet population are not significantly different. These instruments count particles and, therefore, necessitate a calibration made by means of platelet standards. Different platelet standards have been studied: these containing latex particles seem to give better results than suspensions of human or animal platelets.

Blood Platelets↗
PubMed1980

Platelet aggregation related to age in diabetes mellitus.

Platelet aggregation induced by ADP and collagen was studied in 174 diabetic patients before entering a controlled clinical trial. The clinical characteristics have been precisely defined. The degree of retinal abnormality was assessed by fundus angiofluorography in every patient. Most patients had background retinopathy; the remainder were normal. All results were computer analysed. The only significant relationship observed was between platelet sensitivity to ADP which increases regularly in relation to age in both insulin- and non-insulin-treated diabetic patients with or without background retinopathy. Spontaneous platelet aggregation was observed in 13 subjects and was not correlated to the existence of a neuropathy or any other clinical characteristics.

Adenosine Diphosphate↗
PubMed1980

[Congenital deficiency of factor XI: diagnosis and therapy in surgical patients (author's transl)].

Factor XI deficiency has to be diagnosed preoperatively since it may be symptomless until revealed by bleeding after surgical procedures. Replacement therapy prior to operation is advocated and its management defined; because the effects of plasma infusion on factor XI level are not constant and because of the wide variation in the half life of infused factor, it is strongly advised that regular measurement should be made when possible. Ovariectomy in a factor XI deficient patient was carried out with correct haemostasis.

Aged↗
PubMed1979

[Haemorrhagic complications using streptokinase during 98 treatments. Place of the biological surveillance (author's transl)].

Streptokinase was administered to 98 patients, 75 of them with arterial occlusion of the limbs, in accordance with the classical protocol of high and continuous doses (150,000 international units per hour for 48 to 78 hours after an initial standard dose of 500,000 units). There were a total of 15 haemorrhagic complications: --related to a non-respected contraindication (1 case) --traumatic (4 cases) --spontaneous (10 cases), responsible for or contributing to a fatal outcome in 4 instances. In addition, there were 13 spontaneous or provoked haemorrhagic side effects. Retrospective analysis of laboratory results shows that it is difficult to predict haemorrhage: the degree of fibrinopaenia and fibrin breackdown product levels are not closely related to the onset of bleeding. Nevertheless, the combination of a residual fibrin level of less than 1.50 g/l approximately with an amount of fibrinogen broken down (difference between fibrinogen levels before treatment and during treatment) of more than 3 grams was present in the great majority of patients in whom complications developed. The absence of bleeding seen when plasma thrombolytic activity, assessed by the Blix test, is inadequate, suggests the existence of a relationship between biological effectiveness and the risk of haemorrhage. In practice, apart from strict observation of contraindications, the risk of haemorrhage must be born in mind when the therapeutic decision is made. Careful clinical surveillance is today more important than laboratory studies in the prevention of haemorrhagic complications, the price which must be paid for the thrombolytic activity of streptokinase. The latter is capable of acting not only upon the vascular obstruction but also upon haemostatic clots.

Adolescent↗