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Biomedical subjects

R C Franz

Publications and source records attributed to R C Franz.

32 records · Page 2Linked to original sources
PubMed1981

Venous thrombo-embolism and raised alpha-1-antitrypsin levels. A possible causal relationship between excessive neutral protease inhibition and defective granulocyte-induced fibrinolysis.

The finding of 4 cases of venous thrombosis in patients with raised serum alpha 1-antitrypsin (AAT) levels has focused attention on the role of the inhibitors of leucocyte protease or granulocyte-induced fibrinolysis. A composite fibrin plate assay was devised to determine the fibrinolytic and fibrinolytic-inhibitor potential of viable circulating granulocytes, mononuclear cells and platelet-free plasma. A plasmin-dependent and a plasmin-independent pathway were identified in circulating granulocytes, a biological function which appeared to be completely absent from the mononuclear fraction. In order to explore the effect of AAT on the cellular fibrinolytic pathway, viable granulocyte and plasma fractions were exposed to the inhibitor in a purified system as well as to several aliquots of plasma containing an excess of AAT obtained from a patient with venous thrombo-embolic disease. The unequivocal inhibition of granulocyte fibrinolytic activity by pure AAT solutions as well as by plasma with a raised AAT level would seem to provide further evidence that by counteracting protease liberated by cellular elements, notably the granulocyte, the patient is deprived of a vital component of the fibrinolytic defence mechanism.

Adult↗
PubMed1981

The thrombelastographic diagnosis of hemostatic defects.

The thrombelastogram as designed by Hartert has now been in use for more than 30 years. Within 30 minutes, it provides a global account of clot formation and fibrinolysis or the time and degree of the interaction between the activators and inhibitors of both systems. On the basis of our own experience, it seems justifiable to assert that although its sensitivity to technical variables requires stringent laboratory control, the TEG offers a simple, reliable method of defining the key areas of hemostatic incompetence or for assessing the efficacy of a therapeutic program. Thrombelastographic hypercoagulability, which has deservedly been given prominence in the recent literature, may add an exciting dimension to the diagnostic spectrum of an elegantly conceived instrument.

Adolescent↗
PubMed1979

A possible causal relationship between defective fibrinolysis and pulmonary hypertension.

Pulmonary hypertension may be associated with multiple thrombi in the pulmonary arteries or with diffuse microembolization from a cryptic source. A 27-year-old man without any of the recognized clinical risk factors for venous thrombo-embolic disease presented with repeated attacks of chest pain and dyspnoea. Haemodynamic studies were compatible with the diagnosis of primary pulmonary hypertension. Despite intensive study there was no evidence of peripheral venous thrombosis. A survey of the plasma fibrinolytic profile showed unequivocal evidence of low spontaneous plasma fibrinolytic activity. The plasminogen activator activity of the venous wall was also markedly reduced. From these findings it would seem that a defective fibrinolytic defence mechanism may be an important predisposing factor in the pathogenesis of 'primary' pulmonary hypertension.

Adult↗
PubMedDate not supplied

Mechanism of thrombosis caused by sclerotherapy of esophageal varices using sodium tetradecyl sulphate.

The mechanism of thrombosis following intravariceal injection of sodium tetradecyl sulphate (S.T.D.) was investigated with respect to effects on the vascular endothelium, the coagulation cascade, and platelet function. Using an umbilical cord model designed to simulate blood flow over the endothelium, it was found that S.T.D. is a potent toxin for endothelial cells in that brief exposure to even low concentrations of the agent were effective in stripping endothelium over a considerable distance, exposing highly thrombogenic endothelium in the process. Effects on coagulation and platelet function were found to be dependent on concentration. Diluted S.T.D. induced a hypercoagulable state, possibly in consequence of a selective inhibition of the physiological anticoagulant, protein C, and promoted platelet aggregation. Higher concentrations inactivated the coagulation cascade and lysed platelets completely. These results suggest that intravariceal infusion of S.T.D. at considerable dilution may be at least as effective in inducing thrombosis as standard dosage, and possibly more so.

Blood Coagulation↗
PubMedDate not supplied

Structural changes in the fibrin network of a pretoria family with dysfibrinogenemia: a scanning electron microscopical study.

Inborn errors of fibrinogen structure are by definition congenital dysfibrinogenemias. The present study assesses the scanning electron microscope characteristics in the fibrin network morphology in a Pretoria family with an amino-acid substitution defect at position 139 on the gamma chain where the cystein residue is replaced by tyrosine. This anomaly results in a disturbance of the interchain disulfide bond, an ultrastructural defect that interferes with fibrin polymerization. Clinical manifestations showed that 2 of the family members presented with thrombosis, as well as a bleeding tendency, while 2 were asymptomatic. Fibrin clot analysis revealed that in all 4 family members a tighter fibrin network with increased fibrin density and reduced pore size was present. The fibers showed a "stellate" appearance where they converge and some were fused longitudinally to form sheets of "matted" fibrin. Furthermore, there was a conspicuous absence of platelets. Fibrin dysfunction is associated with the development of vascular complications, while proneness to the formation of tight and rigid fibrin networks is independently associated with thrombotic disease. Although this does not explain the proneness of some family members who present with excess bleeding, bleeding might be related to the defective binding of fibrin to activated platelets, resulting in inadequate prothrombotic stimulus that is normally enhanced by the second wave of thrombin generation, which occurs on the platelet surface.

Afibrinogenemia↗
PubMedDate not supplied

Thromboxane B2 production during erection.

The effect of erection on 6-keto-PGF1 alpha and thromboxane B2 in penile blood during electrically evoked erection was studied in the chacma baboon. 6-keto-PGF1 alpha remained at a low concentration, but thromboxane B2 showed a statistically significant rise 8-10 minutes after commencement of erection. Elevated thromboxane B2 during erection may potentiate platelet aggregation and may be one of the key events in the pathogenesis of ageing impotence.

6-Ketoprostaglandin F1 alpha↗