Effect of metformin on fibrinolysis in type 2 diabetes mellitus: an explorative study

Type 2 diabetes mellitus (T2DM) is associated with a high incidence of vascular disease which can cause significant morbidity and mortality. The risk of cardiovascular mortality in T2DM patients is observed to be more compared to the age-matched subjects. This is attributed to depression of the fibrinolytic system which maintains patency of blood vessels. Endogenous inhibitors such as plasminogen activator inhibitor-1 (PAI-1) inhibit the activation of plasminogen and thus prevent the degradation of fibrinogen. In T2DM there is increased levels of PAI-1. Such a state of altered fibrinolysis is attributed to insulin resistance. A previous study done at our institute demonstrated higher euglobulin lysis time (ELT) in T2DM patients than controls, suggesting altered fibrinolytic activity in the former group. D-dimer is a degradation product of fibrin. Its presence indicates a state of hypercoagulability. In a study by Nwose et al rise in D-dimer levels were observed in diabetics, especially with cardiovascular complications as compared to controls indicating D-dimer could be a useful marker for predicting the complications in T2DM.

Phenomenon of attraction to alcohol and fibrinogen

Введение. Фибриноген, как и многие белки системы гемостаза и фибринолиза, участвует во многих физиологических процессах, при этом его содержание может увеличиваться или уменьшаться при различных патологических состояниях, и эти модуляции часто служат диагностическим признаком заболевания. Цель исследования: определить уровень фибриногена и время лизиса эуглобулиновой фракции плазмы крови в зависимости от степени влечения к этанолу у крыс. Материалы и методы. Работа выполнена на 300 крысах-самцах линии Вистар весом 250–350 г, у которых после двух-недельного периода акклиматизации ежедневно в течение 7 дней проводили тестирование потребления 10% раствора этанола и воды в индивидуальных боксах. Эти жидкости были доступны в течение 23 часов без доступа к пище. Позиции 2 питьевых пипеток объемом 50 мл случайным образом менялись местами через каждые 24 часа. Результаты. Установлено, что чем выраженнее была исходная степень влечения к этанолу, тем выше оказывалось содержание фибриногена и ниже фибринолитическая активность. Заключение. Случаи повышенного содержания фибриногена у исходно отвергающих, не имевших контакта с этанолом крыс указывает на возможность генетически обусловленной гиперфибриногенемии, которая может стать источником предтромбозных состояний в случае предрасположенности к потреблению алкоголя в качестве энергетической самокоррекции. Introduction. Fibrinogen, like many proteins of hemostasis and fi brinolysis system, participates in many physiological processes, and its content may increase or decrease under various pathological conditions, and these modulations often serve as a diagnostic sign of the disease. Aim: to determine fi brinogen level and euglobulin lysis time as function of attraction degree to ethanol in rats. Materials and methods. The work was performed on male Wistar rats (n = 300) weighing 250–350 g. After 2 weeks of acclimatization the consumption of 10% ethanol and water in individual boxes was daily tested for 7 days. These fl uids were available for 23 hours without access to food. Positions of 2 drinking pipettes of 50 ml volume randomly changed every 24 hours. Results. It was found that fi brinogen content was higher but fi brinolytic activity was lower in rats with more expressed initial degree of attraction to ethanol. Conclusion. The cases of increased fi brinogen content in initially refused rats that did not contact with ethanol indicate the possibility of genetically determined hyperfi brinogenemia that can become a source of prethrombotic conditions in case of predisposition to alcohol consumption as an energy self-correction.

Hyperfibrinolysis and the risk of hemorrhage in stable cirrhotic patients

Background: Bleeding is an important complication of cirrhosis. Currently, there is no coagulation test that can reliably predict clinical hemorrhage. However, previous studies demonstrated significant correlations between hyperfibrinolysis and following bleeding in advanced cirrhotic patients. Objectives: Estimate the prevalence of hyperfibrinolysis in cirrhotic patients at stable conditions and to assess its role in predicting subsequent hemorrhage. Methods: The prospective cohort study included 58 consecutive cirrhotic patients at the Liver Clinic, Chulalongkorn Hospital. Assays for liver functions, PT, APTT, fibrinogen, fibrin degradation products (FDPs) and euglobulin lysis time (ELT) were performed at baseline. The subjects were followed-up for 10 months to observe clinical hemorrhage and survival. Results: The mean age was 56.4 years and 47% were male. The etiologies of liver diseases were virus (62.1%), alcohol (24.1%) or unknown (8.6%). Hyperfibrinolysis as reflected by ELT<120 minutes or FDPs>10 μg/mL was present in 32.8% and 74.1%, respectively. Fibrinolytic activity was significantly correlated with platelet counts and coagulation times, but not as much with liver function tests. By 10 months, 13 cases (22.4%) showed hemorrhagic episodes and 7 (12.1%) were expired, including 2 from bleeding. The significant predictors for death were Child class B or C, presence of ascites, hyperbilirubinemia, hypoalbuminemia, and prolonged APTT. However, none of the clinical, biochemical, or hemostatic factors was associated with clinical bleeding. Conclusion: Hyperfibrinolysis is common in cirrhotic outpatients. However, it cannot predict subsequent hemorrhage or survival. Novel hemostatic tests are required to assess the probability of bleeding in this disorder.

Fibrinolytic and biochemical factors in patients with venous insufficiency

Long-term metabolic changes in vein tissue of the limbs and feet have been reported in the course of chronic venous insufficiency (CVI). Low fibrinolytic potential was first demonstrated using fibrin-embedded vein rings (Todd's biopsy), then in blood via increased euglobulin lysis time. This defect is especially pronounced when blood is taken from foot veins of patients with grades 5 and 6 of CVI or skin lesions. Haemorrheological disorders such as increased blood viscosity and red cell aggregation, related mainly to high fibrinogen levels, have also been shown in patients with CVI. Such disorders, particularly observed in blood from foot veins, play an important role in the interaction between the blood cell components and the vessel wall. More recently, the margination and adhesion of white cells to the endothelium and the subsequent activation of white cells have been assumed. Adhesion molecules such as ICAM-1, VCAM-1 and P-selectin have been identified surrounding skin ulceration. There is also evidence that markers of neutrophil degranulation reach high levels in blood taken from foot veins after exposure to experimental venous hypertension. White cell activation results in elevated plasma levels of L-selectin, increased production of oxygen free radicals, pseudopods, CD11b integrin, platelet-monocyte aggregates and abnormal lymphocyte L-selectin. Increased nitric oxide, presumably due to monocyte activation, as well as increased urine haemosiderin related to skin microvessel leakage have also been reported. VCAM-1 and metalloproteinase MMP9 activity have been stated as sensitive markers in relation to endothelium activation and white cell trapping, which follows hypoxia and/or alterations in wall shear stress, mainly in skin venulae and in the region of valves.

Tissue Factor Pathway Inhibitor is a Potent Inhibitor of Plasmin

Recombinant tissue factor pathway inhibitor (TFPI) was found to be a potent inhibitor of plasmin. In an amidolytic assay the inhibition constant K i was found to be 2.86 x 10-8 M. TFPI in the same concentration range also inhibited the activation of plasminogen by tissue plasminogen activator (tPA). The amidolytic activity of tPA was not inhib ited by TFPI. Other proteinases relevant to fibrinolysis such as urokinase, α-factor XIIa, and β-factor XIIa were not inhibited by TFPI. Plasma kallikrein was weakly inhibited by TFPI. When added to plasma, TFPI also prolonged the euglobulin lysis time. The interaction of TFPI with heparin and a muco polysaccharide polysulfuric ester, a heparin-like glycosamino glycan, was studied. Heparin augmented plasmin inhibition by TFPI, while mucopolysaccharide polysulfuric ester had no ef fect. Key Words: Tissue factor pathway inhibitor (TFPI)— Plasmin—Inhibition—Fibrinolysis.

4G/5G Polymorphism of PAI-1 Gene Promoter and Fibrinolytic Capacity in Patients with Deep Vein Thrombosis

SummaryA deletion/insertion polymorphism (4G or 5G) in the promoter of the plasminogen activator inhibitor type 1 gene has been suggested to be involved in regulation of the synthesis of the inhibitor, the 4G allele being associated with enhanced gene expression. A relationship between 4G/5G polymorphism and PAI-1 levels was found in patients with cardiovascular and metabolic diseases, but not in healthy subjects. In the present work we studied the distribution of PAI-1 4G/5G geno-type and its relation to fibrinolytic capacity in 70 unrelated patients with deep vein thrombosis. Each patient was assayed before and after 20 min. Venous occlusion for euglobulin lysis time, t-PA antigen and activity, and PAI-1 antigen and activity. The prevalence of 5G homozygous carriers was significantly lower in patients than in controls (10% vs. 26%, p = 0.009). The 5G allele frequency was reduced, even though not significantly, in DVT patients compared to healthy subjects (0.40 vs. 0.51, respectively). In the patient group, the mean PAI-1 antigen and activity levels were significantly higher than among controls and related to the 4G/5G polymorphism. In patients with 4G/5G and 4G/4G genotype a significant correlation was found between PAI-1 levels and the global fibrinolytic activity as evaluated by euglobulin lysis time. The prevalence of a reduced fibrinolytic potential due to PAI-1 excess was 45.7% among DVT patients. Moreover, the prevalence of PAI-1 induced hypofibrinolysis was strongly related to PAI-1 polymorphism, since it was significantly lower in 5G homo-zygous patients (28.6%) than in both 4G/5G carriers (55.3%, p <0.001) and 4G homozygous patients (57.9%, p <0.001).In conclusion, in patients with deep vein thrombosis the 4G polymorphism of PAI-1 gene promoter may influence the expression of PAI-1 and it should be taken into consideration as a facilitating condition for pathological fibrinolysis together with other environmental and genetic factors. Whether this has any significance in regard to the pathogenesis of venous thrombosis remains to be proven.

Venostasis but not DDAVP Infusion Provokes the Plasma Fibronectin Increase

SummaryPlasma fibronectin (pFN), von Willebrand factor antigen (vWf: Ag), factor VIII procoagulant activity, fibrinogen, euglobulin lysis time (ELT) and hematocrit were determined in healthy blood donors before and after venostasis as well as after intravenous infusion of l-deamino-8-D-arginine vasopressin (DDAVP). Both venostasis and DDAVP provoked an increase in vWf : Ag and shortening in the ELT. In contrast, venostasis only but not DDAVP induced an increase in pFN levels which was statistically significant with and without correction for a concomitant hematocrit increment. The results indicate that there is a distinct difference in the patterns of venostasis and DDAVP mediated release of proteins from the vessel wall.