György Blaskó

Action of heparin on thrombin-antithrombin reaction

Thrombin partially purified from bovine plasma can be inactivated at 60 degress C. In the presence of 10 units of heparin the extent of inactivation decreases. When thrombin and heparin are mixed and incubated for 5 min at 0 degrees C before gel filtration on Sephadex G-200, thrombin with heparin is eluted prior to either thrombin or heparin laone. These data suggest a complex formation between thrombin and heparin. Immobilized heparin binds thrombin. The enzyme can be eluted with 0.05 M Tris-HCl buffer, pH 7.3, containing an ion mixture of Na+, K+ and Ca2+ at 73, 3 and 11 mM, respectively, at 0 degrees C and with 0.05 M Tris-HCl buffer, pH 7.3, containing 0.5 M NaCl at 20 degrees C. During the same chromatographic procedure, antithrombin-III (heparin cofactor) partially purified from human plasma is eluted with 0.05 M Tris-HCl buffer, pH 7.3, at 0 degrees C as well as 20 degrees C. Although, as described in the literature, heparin binds to antithrombin, our findings suggest another possibility, i.e. that the binding of heparin to thrombin induces a conformational change in the enzyme facilitating a complex formation between thrombin and antithrombin-III.

The effect of drotaverine hydrochloride in acute colicky pain caused by renal and ureteric stones

To assess the spasmolytic effect of drotaverine hydrochloride in colicky pain caused by renal and ureteric stones.

Serum levels of platelet released CD40 ligand are increased in early onset occlusive carotid artery disease

Objective: Soluble CD40 ligand (sCD40L) has been suggested as a key mediator between inflammation and atherosclerosis, and the CD40-CD40L interaction has a role in atherosclerotic lesion progression. We evaluated if platelet released serum sCD40L and sCD40 levels differ between patients with early onset occlusive carotid artery disease and age-matched controls. Methods: sCD40L and sCD40 levels were measured in serum samples of 60 patients with occlusive carotid artery disease and 30 age-matched controls using ELISA. Degree of stenosis of the internal carotid artery (ICA), and intima-media thickness (IMT) in the common carotid artery were measured by high resolution ultrasound. Values are given as mean ± SD. Results: Mean age was 50.9 ± 3.5 and 50.1 ± 3.5 years in the patient and control groups. IMT was significantly thicker in patients than in controls (0.89 ± 0.14 vs. 0.78 ±0.12 mm, p = 0.0003). Serum levels of sCD40L were significantly higher (6.9 ± 5 vs. 4.5 ± 3.0 ng/mL, p = 0.038) in patients, whereas sCD40 did not differ significantly between patients and controls (85 ± 56.9 vs. 79.3 ± 18.7 pg/mL, p = 0.34). IMT did not correlate with sCD40L or sCD40 levels (R = −0.03, p = 0.77; and R = 0.109, p = 0.308, respectively). Conclusions: sCD40L but not sCD40 levels are significantly higher in patients with occlusive carotid artery disease. Platelet derived sCD40L may be a key mediator among inflammation, thrombosis and atherosclerosis.

Common definition for categories of clinical research: a prerequisite for a survey on regulatory requirements by the European Clinical Research Infrastructures Network (ECRIN)

BackgroundThorough knowledge of the regulatory requirements is a challenging prerequisite for conducting multinational clinical studies in Europe given their complexity and heterogeneity in regulation and perception across the EU member states.MethodsIn order to summarise the current situation in relation to the wide spectrum of clinical research, the European Clinical Research Infrastructures Network (ECRIN) developed a multinational survey in ten European countries. However a lack of common classification framework for major categories of clinical research was identified, and therefore reaching an agreement on a common classification was the initial step in the development of the survey.ResultsThe ECRIN transnational working group on regulation, composed of experts in the field of clinical research from ten European countries, defined seven major categories of clinical research that seem relevant from both the regulatory and the scientific points of view, and correspond to congruent definitions in all countries: clinical trials on medicinal products; clinical trials on medical devices; other therapeutic trials (including surgery trials, transplantation trials, transfusion trials, trials with cell therapy, etc.); diagnostic studies; clinical research on nutrition; other interventional clinical research (including trials in complementary and alternative medicine, trials with collection of blood or tissue samples, physiology studies, etc.); and epidemiology studies. Our classification was essential to develop a survey focused on protocol submission to ethics committees and competent authorities, procedures for amendments, requirements for sponsor and insurance, and adverse event reporting following five main phases: drafting, consensus, data collection, validation, and finalising.ConclusionThe list of clinical research categories as used for the survey could serve as a contribution to the, much needed, task of harmonisation and simplification of the regulatory requirements for clinical research in Europe.

D-dimer as a potential prognostic marker.

Malignant tumors are often accompanied by increased risk for procoagulant activity, thrombosis and embolism. As a marker indicating such disturbancies is D-dimer, a product of fibrinolysis. In this retrospective study almost 300 patients with malignant tumors were evaluated. During LMWH treatment (as thromboprophylaxis) the highest frequency of VTE with worst prognosis occurred in pancreatic cancer (partly due to the late discovery) followed by ovarian, colonic and breast cancers. Also, increased D-dimer level correlated with progression (stages) and high mortality rate. Furthermore, D-dimer showed very similar or better prognostic activity than the clinically widely used classic tumor markers and suggested to use it as an additional value..

Natural coagulation inhibitor proteins in young patients with cerebral ischemia

Disturbances of coagulation and fibrinolytic pathways were studied in 53 young patients with cerebral ischemia. Upon admission 26 of 53 patients had abnormality in at least one of the antithrombin-III, protein C, protein S activities or in activated protein C (APC) ratios. Three months after the first examination the majority of the previously detected abnormalities returned to normal values and the most frequent alterations were decrease in protein S activity (3 patients) and APC resistance (3 patients). Conditions resulting in impaired fibrinolysis were frequently detected upon admission. Elevation of plasminogen activator inhibitor-1, lipoprotein (a), and alpha-2-antiplasmin was present in 23, 10, and 4 cases, respectively. It is concluded that abnormalities of coagulation as well as of the fibrinolytic systems are prevalent in the acute phase of cerebral ischemia, however, the results may be significantly influenced by the disease process or the acute phase effect.

Investigation of Thr715Pro P-selectin gene polymorphism and soluble P-selectin levels in type 2 diabetes mellitus

Increased levels of soluble P-selectin (sP-selectin) have been shown in a number of different disorders, e.g. diabetes mellitus (DM) and cardiovascular disease (CVD). Several studies have attempted to demonstrate the association of the most intensively examined variant of P-selectin gene polymorphism (Thr715Pro) with sP-selectin levels in healthy subjects and in CVD, but contradictory data have been reported. To clarify the effect of Pro715 allele on the sP-selectin levels in type 2 DM, we analysed this polymorphism in diabetic patients and compared these data with sP-selectin levels. Type 2 DM patients (n = 119), 48 BMImatched non diabetic individuals - consisting mostly of overweight subjects - and 57 healthy volunteers were included in the study. TheThr715Pro polymorphism was analysed by PCR-RFLP, while sP-selectin levels were measured by ELISA. Significantly elevated sP-selectin levels were found in both DM and in overweight subjects compared to healthy controls. We confirmed previous reports that in healthy Pro715 allele carriers lower sPselectin levels could be measured; however, this difference was only significant in case of lean subjects. No significant difference was detected in sP-selectin level among DM and overweight individuals according to this genotype. However, significant difference was observed in sP-selectin levels in older DM patients compared to younger ones, but these levels were not accounted for by the Thr715Pro polymorphism. We suggest that in type 2 DM individuals, the significantly elevated sP-selectin levels are not due to the Thr715Pro P-selectin gene polymorphism.

Monocytes Express Tissue Factor in Young Patients with Cerebral Ischemia

Activation of blood coagulation and fibrinolysis has previously been detected in stroke patients. It is unknown, however, what factors contribute to the acceleration of coagulation reactions, especially in cases where no obvious predisposing factors exist. We therefore postulated and tested the hypothesis that in such patients monocytes may trigger the pathway leading to thrombosis by expressing tissue factor (TF). TF antigen was determined in 48 patients and 40 controls by flow cytometry using an indirect immunofluorescent technique. TF antigen expression was significantly increased on monocytes in young stroke patients in both the acute (p < 0.01) and chronic (p < 0.05) phases of the disease. The TF antigen also possessed functional activity, quantitated by a one-stage clotting assay. TF expression on monocytes was not associated with an elevation in C-reactive protein values. In both acute and chronic phases, blood coagulation activation markers, e.g. the thrombin-antithrombin complex and F1+2 fragments, were significantly elevated. However, in the acute phase D-dimer levels were similar to those in controls and were only elevated in the chronic phase of the disease (p < 0.05). In conclusion, in cerebral ischemia TF expression on monocytes suggests enhanced activation of blood coagulation and subsequent fibrinolysis.

The interaction of thrombin and heparin. Heat inactivation kinetics

Abstract Kinetic analysis of heat inactivation of thrombin in the presence of varying concentrations of heparin suggests that two forms of thrombin exist with respect to heparin sensitivity. One of them is inactivated by heat easily and cannot be stabilized with heparin. The other one interacts with heparin and is protected against heat inactivation at 54°C.

Effect of sodium and potassium ions on the activity of human antithrombin-heparin cofactor

Abstract A method was developed for partial purification of human antithrombin-heparin cofactor and the effect of sodium and potassium ions on its activity was determined. It was found that the thrombin-antithrombin complex formation facilitated with heparin was further accelerated by sodium or potassium chloride. The rate of thrombin inactivation showed a maximum between 0.1 and 0.2 M ion concentration in the presence of 0.012 units heparin per ml.