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In a large proportion of patients with mild bleeding disorders (MBDs) no diagnosis can be established by routine coagulation tests. We investigated whether alterations in plasma clot properties account for MBDs of unknown cause. Ninety-five patients with MBDs of unknown origin and 98 age- and sex-matched healthy controls were investigated. Furthermore, data of 25 patients with a deficiency of factor VIII were analyzed. Plasma clot characteristics in the absence and presence of recombinant tissue plasminogen activator (rtPA) represented by the lag phase, rate of protofibril formation (Vmax), fibrin structure (ΔAbs), time to peak (TTP), half lysis time (t 50 and area under the curve (AUC) were measured in turbidometric clot formation and lysis assays. In the fibrinolysis assay, Vmax was lower in patients than in healthy controls. No differences in the other parameters of clot formation and lysis were detected between the groups. There was no clear association of plasma clot properties with the clinical severity of bleeding in patients with MBDs. Patients with known decreased factor VIII levels also showed a lower Vmax. Fibrinogen levels were positively associated with each of the assessed parameters in both groups, with the strongest association with ΔAbs, indicating altered fibrin structure. Factor VIII activity correlated with altered clot characteristics similar to fibrinogen, especially in patients, with the strongest positive correlation to Vmax. This cohort of patients with MBDs of unknown origin showed a lower rate of fibrin formation in the fibrinolysis assay, but otherwise similar plasma clot properties compared to healthy controls.

We retrospectively analysed the data of 1519 antiphospholipid antibody (APLA) positive patients between 1986 and 1999. Among them 637 were considered to have antiphospholipid syndrome (APS) based on the 1999 preliminary classification criteria, while 704 patients had no clinical signs of the syndrome. Our aim was to compare the autoantibody profile and clinical characteristics of primary and secondary APS, moreover to evaluate the associations between different APLA and specific symptoms attributable to APS. In our results, the APLA profiles for primary and SLE-associated secondary APS were similar. Among the evaluated clinical symptoms, cerebrovascular thrombosis was found to be more frequent in the SLE-associated, than in the primary APS group (P = 0.04). We identified important differences in the clinical profile of patient populations with various types of APLA. Venous thrombosis occurred more frequently in subjects with lupus anticoagulant (LA), than in those with IgG or IgM type ACLA (P < 0.0001), while coronary, carotid and peripheral artery thrombosis occurred more often in subjects with IgG or IgM ACLA (P < 0.0001). These findings may support the role of antibodies to cardiolipin or its cofactor, b2glycoprotein I (b2-GPI) in the initiation and progression of atherosclerosis. Cerebrovascular thrombosis was detected in larger proportion of LA or IgG ACLA-positive patients compared with to IgM ACLA-positive subjects, while the occurrence of foetal loss was similar in all three groups.

Antiphospholipid syndrome (APS) is a distinct clinical entity characterized by arterial and venous thromboembolic events, recurrent fetal loss and the presence of antiphospholipid antibodies in the patients’ sera. In primary APS, there is no detectable underlying disease, while overlap APS is associated with clinical syndromes including systemic autoimmune diseases, infections, or malignancies. We carried out a retrospective analysis of serological and clinical manifestations as well as assessed outcome-measures in 165 patients with primary APS. Thrombotic manifestations and possible signs of autoimmune diseases were determined at the time of the diagnosis, followed by the analysis of recurrent thrombotic events and effects of therapy during the follow-up period. Among the 165 patients with primary APS at onset, 105 patients (63%) remained primary APS after a mean 5.2 years of follow-up. In 14% of the patients, subsequently APS became associated with various characteristics of undifferentiated connective tissue disease. Finally 23% of patients evolved into a definitive systemic autoimmune disease during a mean 9.75 years of follow-up. Recurrent thrombotic events were registered in 24% of patients. Our results suggest that primary APS may be considered as a potential early phase of a dynamic transition towards a well-defined systemic autoimmune disease.

Aims. To identify intracardiac hemostasis or fibrinolysis abnormalities, which are associated with atrial fibrillation (AF) and increase the risk of thromboembolism. Patients and Methods. Patient group consisted of 24 patients with AF and control group included 14 individuals with other supraventricular tachycardia undergoing transcatheter radiofrequency ablation. Blood samples were drawn from the femoral vein (FV), left atrium (LA), and left atrial appendage (LAA) before the ablation procedure. Fibrinogen, factor VIII (FVIII) and factor XIII activity, von Willebrand factor (VWF) antigen, thrombin-antithrombin (TAT) complex, quantitative fibrin monomer (FM), plasminogen, α2-plasmin inhibitor, plasmin-α2-antiplasmin (PAP) complex, PAI-1 activity, and D-dimer were measured from all samples. Results. Levels of FVIII and VWF were significantly elevated in the FV and LA of AF patients as compared to controls. TAT complex, FM, PAP complex, and D-dimer levels were significantly elevated in the LA as compared to FV samples in case of both groups, indicating a temporary thrombotic risk associated with the catheterization procedure. Conclusions. None of the investigated hemostasis or fibrinolysis parameters showed significant intracardiac alterations in AF patients as compared to non-AF controls. AF patients have elevated FVIII and VWF levels, most likely due to endothelial damage, presenting at both intracardiac and systemic level.

Cell Death and Differentiation (2003) 10, 262-265. doi:10.1038/sj.cdd.4401198

Mutations in the GJB2 gene encoding the gap‐junction protein connexin 26 have been identified in many patients with childhood hearing impairment (HI). One single mutation, c.35delG, accounts for the majority of mutations in Caucasian patients with HI. In the present study we screened 500 healthy control individuals and a group of patients with HI from Northeastern Hungary for GJB2 mutations. The patients' group consisted of 102 familial from 28 families and 92 non‐familial cases. The most common mutation in the Hungarian population is the c.35delG, followed by the c.71G>A (p.W24X) mutation. 34.3% of the patients in the familial group were homozygous, and 17.6% heterozygous for 35delG. In the non‐familial group the respective values were 37% and 18% (allele frequency: 46.2%). In the general population an allele frequency of 2.4% was determined. Several patients were identified with additional, already described or new GJB2 mutations, mostly in heterozygous state. The mutation c.380G>A (p.R127H) was formerly found only in heterozygous state and its disease relation was controversial. We demonstrated the presence of this mutation in a family with three homozygous patients and 4 heterozygous unaffected family members, a clear indication of recessively inherited HI. Furthermore, we provided evidence for the pathogenic role of two new mutations, c.51C>A (p.S17Y) and c.177G>T (p.G59V), detected in the present study. In the latter case the pattern of inheritance might be dominant. Our results confirm the importance of GJB2 mutations in the Hungarian population displaying mutation frequencies that are comparable with those in the Mediterranean area. © 2004 Wiley‐Liss, Inc.

Paraffin embedded sections of human liver, lymph node, and placenta showed that certain connective tissue cells were positive for factor XIII subunit a. These cells were further characterised by double immunofluorescence labelling and by combined immunofluorescence and enzyme cytochemical staining on frozen sections. They were labelled by the monoclonal antibodies RFD7 and anti-Leu M3 (markers of the macrophage cell line) but gave a negative reaction for the fibroblast marker IIG10 and showed no alkaline phosphatase activity. Immunoblotting detected factor XIII subunit a in macrophages isolated from placenta but not in human fibroblasts. At lower dilutions, the commercially available antibody against the b subunit of factor XIII also positively reacted with the same cell population. The facts that immunoblotting showed that the antiserum crossreacted with the a subunit and that placental macrophages did not stain strongly for the b subunit also indicate that this antigen is not present in adult connective tissue cells.

The goals of this investigation were, first, to develop a chemical strategy to identify and quantitate the mass of fatty acid which is covalently bound to proteins by thioester linkage in unactivated platelets, and, second, to determine whether exogeneously added fatty acids can alter the fatty acid composition of thioester bound fatty acids. Studies with radio‐labeled fatty acids cannot identify and quantitate the actual fatty acids bound to proteins because they permit analysis of only the radiolabeled fatty acids added and their metabolites. Therefore, in the absence of metabolic labeling by radiolabeled fatty acids, we isolated the thioester‐linked fatty acids from platelet proteins using hydroxylamine at neutral pH to form fatty acid hydroxamates. The hydroxamates were subsequently converted to fatty acid methyl esters by acid methanolysis for quantitation by gas chromatography‐mass spectrometry. Using platelet specimens from 14 subjects, 74% of the fatty acid recovered from the unactivated platelet proteins as thioester linked was palmitate. Importantly, however, 22% was stearic acid, and oleate was 4% of the total thioester bound fatty acid. There was minimal variability (2.6‐fold at maximum) between the subjects in the amount of the thioester‐linked palmitate and thioester‐linked stearate. However, there was substantial variability (>100‐fold at maximum) between subjects in the amount of thioester‐linked oleate. We also demonstrated that incubation of platelets with exogenous fatty acids can alter the profile of fatty acids bound to platelet proteins by thioester linkages. Incubation of platelets with 100 µM palmitate for 3 h increased the amount of thioester‐linked palmitate by up to 26%, and incubation of platelets with 100 µM stearate increased the amount of thioester‐linked stearate up to 30%. In support of the observation that radiolabeled fatty acids other than palmitate were shown to be capable of binding to platelet proteins by thioester linkage, our results indicate that the fatty acids actually bound to unactivated platelet proteins include a significant amount of stearate, and variable amounts of oleate, as well as palmitate. In addition, the data show that palmitate and stearate can be increased, as a percentage of total protein‐bound fatty acid, by incubation with exogenous palmitate and stearate, respectively.

Under certain conditions actin can be split by thrombin. Actin prepared in the presence of excess Ca++was found to be resistant to thrombin. However, if actin was purified without added Ca++, both G- and F-actin underwent thrombic digestion, although a considerable proportion of actin molecules remained intact. Similar results were obtained with actin (in 50% sucrose) devoid of nucleotide and divalent cations but retaining its native characteristic. The removal of tightly bound Ca++from actin by EDTA accelerated the thrombic splitting and made the complete fragmentation of G-actin possible. Thrombin first cleaves actin into two pieces and subsequently one of them, fragment K (molecular weight 37,000 on sodium dodecyl sulfate-polyacrylamide gel), splits further, resulting in fragments L (molecular weight 27,000) and M (molecular weight about 10,000).