Myosin: a noncovalent stabilizer of fibrin in the process of clot dissolution

Myosin modulates the fibrinolytic process as a cofactor of the tissue plasminogen activator and as a substrate of plasmin. We report now that myosin is present in arterial thrombi and it forms reversible noncovalent complexes with fibrinogen and fibrin with equilibrium dissociation constants in the micromolar range (1.70 and 0.94 microM, respectively). Competition studies using a peptide inhibitor of fibrin polymerization (glycl-prolyl-arginyl-proline [GPRP]) indicate that myosin interacts with domains common in fibrinogen and fibrin and this interaction is independent of the GPRP-binding polymerization site in the fibrinogen molecule. An association rate constant of 1.81 x 10(2) M(-1) x s(-1) and a dissociation rate constant of 3.07 x 10(-4) s(-1) are determined for the fibrinogen-myosin interaction. Surface plasmon resonance studies indicate that fibrin serves as a matrix core for myosin aggregation. The fibrin clots equilibrated with myosin are stabilized against dissolution initiated by plasminogen and tissue-type plasminogen activator (tPA) or urokinase (at fibrin monomer-myosin molar ratio as high as 30) and by plasmin under static and flow conditions (at fibrin monomer-myosin molar ratio lower than 15). Myosin exerts similar effects on the tPA-induced dissolution of blood plasma clots. Covalent modification involving factor XIIIa does not contribute to this stabilizing effect; myosin is not covalently attached to the clot by the time of complete cross-linking of fibrin. Thus, our in vitro data suggest that myosin detected in arterial thrombi binds to the polymerized fibrin, in the bound form its tPA-cofactor properties are masked, and the myosin fibrin clot is relatively resistant to plasmin.     

Increased prevalence of platelet glycoprotein IIb/IIIa PLA2 allele in ischaemic stroke associated with large vessel pathology

Introduction: Platelet glycoprotein IIb/IIIa is a membrane receptor with a central function in the platelet adhesion and ultimately in the thrombus formation. Two major variants of the gene encoding the IIIa subunit, called PLA1 (A1) and PLA2 (A2), have been identified in the general population. There are indications that the A2 allele can also be associated with acute thrombosis or stroke. The purpose of this study was to study the distribution of the A2 allele in different vascular subtypes of stroke disease. Materials and methods: A total of 638 consecutive patients were analyzed and classified as having large vessel pathology (n=168) or a small vessel infarct (n=210). Localization of the vascular occlusions was deducted from analysis of the magnetic resonance imaging (MRI) scan results in stroke patients. The remainder patients were listed into a mixed vascular pathology group (n=167). Patients with other or poorly characterized stroke etiology were excluded from the study (n=93). Results: In the small vessel and mixed vascular pathology groups, the PLA2 allele frequency was similar to that in the controls. By contrast, PLA2 allele frequency was approximately two-fold higher in patients with large vessel pathology (23.3%) than in the stroke-free control subjects (11.7%, p<0.0005). Multivariate logistic regression analysis of data confirmed this association with an odds ratio (OR) of 2.9 (95% confidence interval [CI]: 1.6–4.9, p<0.0005). Conclusions: These data suggest that the PLA2 allele is more frequent in brain infarcts associated with large-vessel occlusion.     

Effectiveness of standardized direct suggestions in dental hypnosis

The frequency of occurrence of amnesia, analgesia and time distortion during hypnotic dental treatments (n = 60) was investigated on high dental anxiety patients. Hypnosis with and without standardised direct suggestions related to amnesia, analgesia and time distortion were compared. Treatment of alert patients without direct suggestions (n = 10) were also used for comparison. Amnesia and time distortion was higher (p < or = 0.05) with the use of suggestions under hypnotic conditions, but analgesia was not significantly different. Alert appearance of the events were in all cases less (p < or = 0.01) than under hypnotic conditions.     

Surgical treatment for primary and secondary tumors of the liver

We performed liver resection for focal liver disease in 266 patients between January 1, 1992 and December 31, 2001 at the University of Debrecen Medical and Health Science Center, Medical School of Medicine, 2nd Department of Surgery in Debrecen, Hungary. The indication was primary liver cancer in 35 cases, liver metastasis in 97 cases. The primary tumour and its liver metastases were removed synchronously in 28 patients (29.9%). Comparing the results of different operating methods we found the need of transfusion significantly less in "anterior" liver resections. Regarding operating time, complications and survival time there were no significant differences between the different operations. One patient died in the perioperative period because of cardiac failure and one because of DIC (1.5%). There were 4 complications which needed reoperation in the early postoperative period. Eighty of the patients were treated with systemic adjuvant chemotherapy (Mayo protocol), with added chemoembolisation in another 26 patients. This has not increased life expectancy significantly. Thirty-two patients are still alive, their average survival time is 21.2 (5 to 59) months. The average survival time of the 78 patients' who died is 16.5 (3 to 58) months. Twenty-two patients were lost out of our follow-up.     

Mucolipidosis II with unusual biochemical parameters

INTRODUCTION: A clinical diagnosis of I-cell disease was established in an infant with coarse face, hyperplastic gums, severe growth deficiency, skeletal deformities and retarded psychomotor development. PATIENT/METHOD: Albeit, enzyme measurements in our patient leukocytes and serum including arylsulfatase, hexosaminidase, alpha-fucosidase, iduronate-sulphatase and beta-galactosidase showed no significant alteration, in serum an increased activity of beta-glucuronidase was detected. Enzyme studies in fibroblasts showed an abnormal intracellular/extracellular distribution of enzyme activities, and significantly decreased activity of UDP-N-acetylglucosamine-1-phosphotransferase confirming the diagnosis of I-cell disease. RESULTS/DISCUSSION: In the mother's next pregnancy at 15th week of gestation lysosomal enzyme activities were determined in amniotic fluid and cultured amniotic cells, and the diagnosis of an unaffected fetus was established. Based on our experience we suggest the use of cell cultures for the diagnostics of this rare disease.     

Results of mammographic screening at the Mammary Center of Debrecen in 1999 and 2000

INTRODUCTION: The screening mammography decreases the mortality of female breast cancer. METHODS: A complex, independent centre of screening mammography has been operating in Debrecen since 1999. RESULTS: The number of the examinations were 10,399 in 1999 and 13,800 in 2000. The number of explored breast cancer cases were 43 (0.41%) in 1999 and 62 (0.45%) in 2000. CONCLUSION: Although the mortality reduction can be exactly measured after several years, we are convinced that the chances for a better life of these 107 women operated on with breast cancer in early state increased thanks to our project. The results of the breast cancer screening program in Debrecen fulfilled the professional requirements of mammographic service-screening.     

Risk of cancer and malignant transformation in hematology practice

The cancer-morbidity growing year by year is in the focus of investigations all over the world. Beyond inherited factors this could be related to the environmental harm posed to men day by day. In this study questions will be discussed especially concerning carcinogenicity of cytostatic therapy being paradoxically a part of this process. The newly recognised relation between the hemochromatosis gene mutation and myelodysplasia opens new avenues in the understanding process of the pathomechanism of myelodysplastic syndromes. Deliberation tissues from iron of oxidative potential may reduce transfusion need and postpone blastic transformation. The aim of the study is to call for attention on the group of multiple myeloma patients and their first degree relatives having high risk for cancer emphasizing the importance of their follow up.     

Role of osteopontin in the formation of microcalcifications in breast cancer

INTRODUCTION: Osteopontin, a non-collagen, Ca-binding phosphoprotein, plays roles in both physiological and pathological mineralisation processes. Its expression may be severely altered in malignant tumours. AIM: To investigate the presence of this protein in breast tumours showing mammographic microcalcifications. MATERIAL: In this study the authors investigated immunohistochemically the osteopontin expression in 26 breast tumours. The elemental composition of the microcalcifications of the same tumours was also examined with energy dispersive spectrometer linked to a scanning electron microscope. RESULTS: Osteopontin expression was found within the tumours in the tumour cells, in vascular smooth muscle cells, in the myoepithelial cells of the normal ducts, and in macrophages. Extracellular osteopontin positivity was seen around calcified foci. There was no correlation between osteopontin positivity and the examined prognostic factors: grade, type and size of the tumour, axillary lymph nodes status, or age. Two types of microcalcifications were seen: 1. Ca-phosphate only, 2. Those composed of various other elements. CONCLUSION: The presence of osteopontin in the vicinity of calcified foci and in the vessel walls seems to support the hypothesis that osteopontin takes part in calcification process.     

In vitro antioxidant properties of pentoxifylline, piracetam, and vinpocetine

Oxygen-free radicals play an important role in several physiologic and pathophysiologic processes. In pathologic circumstances, they can modify and damage biologic systems. Because oxygen-free radicals are involved in a wide range of diseases (cerebrovascular, cardiovascular, etc.), scavenging these radicals should be considered as an important therapeutic approach. In our in vitro study, we investigated the antioxidant capacity of three drugs: pentoxiphylline (Sigma Aldrich, St. Louis, MO, USA) piracetam (Sigma Aldrich), and vinpocetine (Richter Gedeon RT, Budapest, Hungary). Phenazine methosulphate was applied to generate free radicals, increasing red blood cell rigidity. Filtration technique and potassium leaking were used to detect the cellular damage and the scavenging effect of the examined drugs. According to our results, at human therapeutic serum concentration, only vinpocetine (Richter Gedeon RT) had significant (p < 0.01) scavenging activity with a protective effect that increased further at higher concentrations. Pentoxiphylline (Sigma Aldrich) and piracetam (Sigma Aldrich) did not have significant antioxidant capacity at therapeutic concentrations, but increasing their concentrations (pentoxiphylline at 100-times, and piracetam at 10-times higher concentrations) led to a significant (p < 0.01) scavenger effect. Our findings suggest that this pronounced antioxidant effect of vinpocetine and even the milder scavenging capacity of pentoxiphylline and piracetam may be of value in the treatment of patients with cerebrovascular disorders, but merits further investigations.