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Background: Earlier studies have indicated that inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is associated with thromboembolic complications, whereas inherited disorders of coagulation occur less often than expected in IBD patients. The point mutation Arg506Gln of factor V (Factor V Leiden), resulting in resistance to activated protein C, is the commonest inherited form of thrombophilia. Alterations in circulating levels of factor XIII (FXIII) have been reported among IBD patients. We investigated whether Factor V Leiden or inherited Val34Leu polymorphism of FXIII would associate with IBD or its clinical outcome. Methods: Factor V Leiden mutation and FXIII Val34Leu polymorphism were assayed in 328 unrelated Finnish patients with UC and 235 patients with CD by solid-phase minisequencing techniques. The control groups comprised 142 apparently healthy Finnish subjects and 120 Finnish blood donors. Results: The frequency of Factor V Leiden mutation among IBD patients (4.5%) was not significantly different from that in subjects living in the same area (2.1%). No significant differences could be observed in the FXIII Val34Leu polymorphism allele frequencies between patients and controls. Clinical features of IBD, including the disease extent, requirement for immunosuppressive drugs, and occurrence of complications, seemed to be independent of these two clotting factor variants analyzed. Conclusions: Our data do not support an aetiologic or disease-modifying role for the factor V mutation or factor XIII Val34Leu polymorphism in IBD. [ABSTRACT FROM AUTHOR]

Aim: Our aim was to evaluate the early efficacy and variability of the platelet inhibition exerted by 300 mg clopidogrel for the purpose of acute percutaneous coronary interventions using platelet function tests., Methods and Results: Elective percutaneous coronary intervention was used as a timely model in which clopidogrel was added to ongoing acetylsalicylic acid (aspirin) (100 mg/day) at 2.5 h prior to procedure. Blood samples were collected before administration of clopidogrel and immediately before the intervention from 50 patients. Platelet functions were assessed with traditional aggregation and PFA-100. At baseline, 14 (28%) patients were poor responders to aspirin according to PFA and 9 (18%) continued to show arachidonic acid-induced aggregation. After clopidogrel ADP-triggered aggregation was only modestly inhibited in 40% of the patients. Eight percent of the study population was left without any measurable antiplatelet effect. The patients with modest response to clopidogrel had higher levels of c-peptide (1.5 nmol/L) than the ones responding well (0.9 nmol/L, P<0.05)., Conclusion: Neither ongoing aspirin treatment nor added clopidogrel did reach an expected extent of platelet inhibition. This study shows that aspirin-treated patients undergoing PCI gain highly variable levels of platelet inhibition with short-term clopidogrel 300 mg. At 2 h after adding clopidogrel it failed to enhance platelet inhibition in 40% of the patients. In future, targeted platelet function tests may be helpful to individually select an effective antiplatelet medication for these patients. This study suggests that for acute PTCA clopidogrel does not reach the optimal antithrombotic efficacy in all patients.

Val34Leu polymorphism of the A subunit of coagulation factor XIII (FXIII-A) is located in the activation peptide (AP) just 3 amino acids away from the thrombin cleavage site. This mutation has been associated with a protective effect against occlusive arterial diseases and venous thrombosis; however, its biochemical consequences have not been explored. In the current study it was demonstrated that the intracellular stability and the plasma concentration of FXIII of different Val34Leu genotypes are identical, which suggests that there is no difference in the rate of synthesis and externalization of wild-type and mutant FXIII-A. In contrast, the release of AP by thrombin from the Leu34 allele proceeded significantly faster than from its wild-type Val34 counterpart. By molecular modeling larger interaction energy was calculated between the Leu34 variant and the respective domains of thrombin than between the Val34 variant and thrombin. In agreement with these findings, the activation of mutant plasma FXIII by thrombin was faster and required less thrombin than that of the wild-type variant. Full thrombin activation of purified plasma FXIII of different genotypes, however, resulted in identical specific transglutaminase activities. Similarly, the mean specific FXIII activity in the plasma was the same in the groups with wild-type, heterozygous, and homozygous variants. Faster activation of the Leu34 allele hardly could be associated with its presumed protective effect against venous thrombosis. No such protective effect was observed in a large group of patients with familial thrombophilia.

High plasminogen activator inhibitor-1 (PAI-1) plasma levels increase future risk of myocardial infarction (MI). The 4G allele of the 4G/5G polymorphism of the PAI-1 gene has been associated with increased plasma levels of PAI-1. The association of the PAI-1 polymorphism with coronary narrowings, coronary thrombosis and myocardial infarction (MI) was studied in a prospective autopsy series of 300 middle-aged Caucasian Finnish men (33 to 69 yrs) suffering sudden out-of-hospital death (Helsinki Sudden Death Study). The 4G allele was found in 76.8% of men with sudden cardiac death (SCD) compared to 67.5% in men who died accidentally and 63.2% in men who died of other diseases (p = 0.08 and p = 0.055, respectively). Men possessing the 4G allele had more often acute MI (OR 3.5; p <0.05) and coronary thrombosis (OR 5.5. p = 0.01) compared to 5G homozygotes. 5G homozygotes, comprising one third of the men in our study, seem to be at a decreased risk of thrombosis, whereas carriers of the common 4G allele have an increased risk of thrombosis, AMI and possibly SCD compared to 5G homozygotes.

VEGF-C is a recently characterised endothelial growth factor structurally related to vascular endothelial growth factor (VEGF). We studied the expression of VEGF-C and VEGF in the cells of peripheral blood and in the umbilical cord blood CD 34+ cells, representing haematopoietic progenitor cells. Expression of VEGF-C was detected in the CD34+ cells. In peripheral blood VEGF-C mRNA was restricted to platelets and T-cells. In contrast to the expression pattern of VEGF-C, VEGF mRNA was detected in all peripheral blood cell fractions studied, and also in CD34+ cells. VEGF-C mRNA was also detected in fresh bone marrow samples of acute leukaemia patients, but the expression did not show lineage specificity. VEGF-C and VEGF polypeptides were present in platelets and they were released from activated platelets together with the release of beta-thromboglobulin, suggesting that VEGF-C and VEGF reside in the alpha-granules of platelets. VEGF-C and VEGF, released from activated platelets, may have a role in angiogenesis during wound healing, and possibly also in other pathological conditions, such as atherosclerosis, tumour growth, and metastasis formation.

We generated a panel of monoclonal antibodies against the extracellular domain of the Tie receptor tyrosine kinase and studied its expression in human haemopoietic and tumour cell lines and in samples from leukaemia patients. Most of the erythroblastic/megakaryoblastic (6/8), 2/7 myeloid and 3/6 B-lymphoblastic leukaemia cell lines were Tie-positive. The erythroblastic/megakaryoblastic leukaemia cell lines also expressed the related Tie-2/Tek gene and, surprisingly, its recently cloned ligand gene angiopoietin-1, which was located in chromosome 8q23.1. In addition, 16% of freshly isolated leukaemia samples were Tie positive. Peripheral blood mononuclear cells were Tie negative, but a few Tie positive cells were found in immunoperoxidase staining of mobilized peripheral blood stem cells. Long-term culture of isolated umbilical cord blood CD34+ Tie+ and CD34+ Tie- cells indicated that the Tie+ fraction contained a slightly higher frequency of cobblestone area forming cells (CAFC). Thus, Tie is expressed on haemopoietic progenitor cells and some leukaemic blasts. The coexpression of Tie-2 and angiopoietin-1 in megakaryoblastic leukaemia cell lines suggests the existence of an autocrine ligand/receptor signalling loop in these cells.