The effect of thrombin on the dynamic exchange between intraplatelet and extraplatelet fibrinogen

We examined the distribution of platelet fibrinogen and the exchange between intra- and extra-platelet fibrinogen in unstimulated and thrombin-stimulated platelets. In unstimulated platelets 60% of platelet fibrinogen was found in the soluble platelet fraction and 40% in the insoluble one. In platelets activated with thrombin, changes took place in the distribution of intraplatelet fibrinogen but not in the total fibrinogen content. At 0.5 U/ml of thrombin the fibrin(ogen) content of the insoluble and soluble fractions was approximately 80% and 20%, respectively. When we evaluated how extraplatelet fibrinogen affects the content and distribution of intraplatelet fibrinogen, we found that when unlabelled fibrinogen was added to unstimulated and thrombin-stimulated platelets the content and distribution of intraplatelet fibrinogen remained unaltered. However, when ¹²⁵I-fibrinogen was added, it was incorporated into unstimulated and thrombin-stimulated platelets. In unstimulated platelets, 70% of the incorporated ¹²⁵I-fibrinogen was in the soluble fraction and 30% in the insoluble. In thrombin-stimulated platelets the distribution of the incorporated ¹²⁵I-fibrinogen was 62% and 38% in soluble and insoluble fractions respectively. MoAb to GPIIb–IIIa produced 80% and 60% inhibition of ¹²⁵I-fibrinogen incorporation by unstimulated and thrombin-stimulated platelets. Our data showed dynamic exchange between intraplatelet and extraplatelet fibrinogen both in unstimulated and thrombin-stimulated platelets mediated mainly by GPIIb–IIIa.     

Inflammation,fibrinogen and thrombin generation in patients with previous myocardial infarction

BACKGROUND AND OBJECTIVES: It has been reported that the influence of plasma fibrinogen on the incidence of myocardial infarction is related to inflammatory processes. The aim of this study was to investigate the relationship between inflammatory activity, fibrinogen and thrombin generation in patients 5 years after the acute phase of myocardial infarction. DESIGN AND METHODS: Sixty-seven patients 5 years after a myocardial infarction and 67 control subjects were studied. Plasma fibrinogen protein (Fg-protein) and function (Fg-function), prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT), total sialic acid (TSA) and C-reactive protein (CRP) were measured. RESULTS: The levels of Fg-protein, Fg-function, F1+2, TAT, TSA and CRP were significantly higher in patients than in the control subjects. Plasma TSA correlated with CRP (r=0.31, p<0.05). There was a significant correlation between TSA and Fg-protein or Fg-function (r=0.48, p<0.01). CRP correlated with Fg-function (r=0.32, p<0.05) while there was no correlation between CRP and Fg-protein. CRP also correlated with F1+2 and TAT (r= 0.4, p<0.01). INTERPRETATION AND CONCLUSIONS: Five years after myocardial infarction there was clear evidence of low-grade inflammation that was accompanied by an increase in thrombin formation. The increase of the plasma fibrinogen level is mainly related to TSA and the increase of CRP, which is associated with thrombin generation.     

Potential of soluble CD26 as a serum marker for colorectal cancer detection

Colorectal cancer is characterized by a low survival rate even though the basis for colon cancer development, which involves the evolution of adenomas to carcinoma, is known. Moreover, the mortality rates continue to rise in economically transitioning countries although there is the opportunity to intervene in the natural history of the adenoma-cancer sequence through risk factors, screening, and treatment. Screening in particular accounted for most of the decline in colorectal cancer mortality achieved in the USA during the period 1975-2000. Patients show a better prognosis when the neoplasm is diagnosed early. Among the variety of screening strategies, the methods range from invasive and costly procedures such as colonoscopy to more low-cost and non-invasive tests such as the fecal occult blood test (guaiac and immunochemical). As a non-invasive biological serum marker would be of great benefit because of the performance of the test, several biomarkers, including cytologic assays, DNA and mRNA, and soluble proteins, have been studied. We found that the soluble CD26 (sCD26) concentration is diminished in serum of colorectal cancer patients compared to healthy donors, suggesting the potential utility of a sCD26 immunochemical detection test for early diagnosis. sCD26 originates from plasma membrane CD26 lacking its transmembrane and cytoplasmic domains. Some 90%-95% of sCD26 has been associated with serum dipeptidyl peptidase IV (DPP-IV) activity. DPP-IV, assigned to the CD26 cluster, is a pleiotropic enzyme expressed mainly on epithelial cells and lymphocytes. Our studies intended to validate this test for population screening to detect colorectal cancer and advanced adenomas are reviewed here.     

Interictal mood disorder and quality of life in active epilepsy

Although it is known that depressive symptoms have significant impact on quality of life (QOL) in epilepsy and that atypical symptoms are common in interictal depression, less is known about the clinical significance of the atypical form of interictal depression as opposed to major depressive disorder (MDD). We compared quality of life among 30 patients with epilepsy (1) with major depressive disorder (group D), (2) with interictal dysphoric disorder (group ID), and (3) without MDD or IDD (group ND). The mean t scores on the 31-item Quality of Life in Epilepsy questionnaire were lower in groups D (20.3, 95% CI 9.02–31.7, n = 3) and ID (38.7, 95% CI 34.2–43.2, n = 19) compared with group ND (59.1, 95% CI 52.2–66.1, n = 8). These results underscore the clinical significance of IDD that not only accounts for a large portion of mood symptoms in the population with epilepsy, but also is not adequately captured by the DSM-IV criteria for MDD [1].     

Effect of oral anticoagulant therapy on thrombospondin-1 and von Willebrand factor in patients with stable heart failure

INTRODUCTION: Heart failure (HF) is associated with coagulation activation, abnormal inflammation and endothelial dysfunction. High levels of von Willebrand factor (VWF) may manifest endothelial dysfunction and hypercoagulable state. The haemostatic activity of VWF is a function of multimers size; only large multimers of VWF are haemostatically active. Thrombospondin-1 (TSP-1) reduces the average multimer size of VWF. Patients with HF are in risk of thromboembolic events and oral anticoagulation therapy (OAT) has been shown to prevent it. This study was designed to evaluate whether VWF and TSP-1 levels are modified by OAT in stable HF patients. The effect of OAT on markers of inflammation and coagulation was also investigated. MATERIALS AND METHODS: Fifty-nine patients with stable HF were studied and 33 of them received OAT. VWF, TSP-1, fibrinogen, prothrombin fragment 1+2 (F1+2), tissue factor (TF), D-dimer, endogenous thrombin generation (ETG), C reactive protein (CRP), tumour necrosis factor alpha (TNFalpha) and interleukin 6 (IL-6) were measured. RESULTS: Stable HF patients receiving OAT had higher VWF (p=0.02) and lower TSP-1 (p=0.02), ETG and F1+2 (p=0.003) than patients without OAT. However, there were no significant differences in the levels of fibrinogen, TF, D-dimer, CRP, IL6 and TNFalpha. The TSP-1/VWF ratio in patients receiving AOT was significantly lower than in patients without OAT (p=0.005). CONCLUSION: OAT may have a dual effect on the haemostatic profile in stable HF by reducing thrombin generation and increasing the VWF. The decrease of TSP-1 induced by OAT may be clinically effective in neoangiogenesis. The increase of VWF in patients receiving anticoagulant treatment may also reflect an effect of OAT on endothelial dysfunction.