Patients with systemic lupus erythematosus (SLE) have an increased risk of thrombosis and this is increased in the presence of antiphospholipid antibodies (APA). These APA are also associated with thrombosis in patients who do not have SLE. We compared haemostatic parameters in SLE patients with and without APA, and also compared patients who had APA but not SLE with healthy normal controls. No relationships between the natural anticoagulants, antithrombin III, heparin cofactor II, protein C and protein S, and the presence of APA were found. In the patients with SLE both tissue plasminogen activator antigen and plasminogen activator inhibitor (PAI) were increased, but these changes were not due to APA which had no effect on fibrinolysis in these patients. In the patients with APA who did not have SLE the fibrinolytic response to venous occlusion was reduced due to raised levels of PAI; similar changes have, however, been reported in some patients with idiopathic thrombosis.
19788 -19794). The current studies were undertaken to further examine the interactions between vitronectin and fibrin(ogen). Comparison of vitronectin levels in plasma with those in serum indicates that ϳ20% of plasma vitronectin is incorporated into the clot. When the time course of biotinylated-vitronectin incorporation into clots formed from 125 I-fibrinogen is monitored, vitronectin incorporation into the clot parallels that of fibrinogen in the absence or presence of activated factor XIII. Vitronectin binds specifically to fibrin matrices with an estimated K d of ϳ0.6 M. Additional vitronectin subunits are assembled on fibrin-bound vitronectin multimers through self-association. Confocal microscopy of fibrin clots reveals the globular vitronectin aggregates anchored at intervals along the fibrin fibrils. This periodicity raised the possibility that vitronectin interacts with the ␥A/␥ variant of fibrin(ogen) that represents about 10% of total fibrinogen. In support of this concept, the vitronectin which contaminates fibrinogen preparations co-purifies with the ␥A/␥ fibrinogen fraction, and clots formed from ␥A/␥ fibrinogen preferentially bind vitronectin. These studies reveal that vitronectin associates with fibrin during coagulation, and may thereby modulate hemostasis and inflammation.Vitronectin is a multifunctional plasma glycoprotein that participates in the regulation of coagulation, fibrinolysis, and the complement cascade (reviewed in Refs. 1 and 2). Vitronectin also regulates cell adhesion and pericellular proteolysis on surfaces of cells and extracellular matrices (1-5). Like fibrinogen, vitronectin is found in plasma at micromolar concentrations (6), and is stored in megakaryocyte and platelet ␣-granules (7-9). In plasma, vitronectin circulates as a native, monomeric form that is a mixture of 72-kDa single-chain and two-chain disulfide-linked species (10 -12). Under normal conditions, less than 3% of plasma vitronectin is comprised of more reactive oligomeric forms that display enhanced affinity for heparin or heparin-like molecules, and for the conformationsensitive monoclonal antibody 8E6 (10 -12).During acute phase response, plasma vitronectin levels increase (6), with a relative increase in the percentage of oligomeric vitronectin (13). Levels of the oligomeric forms of vitronectin in serum relative to plasma also increase; indicating the process of coagulation alters vitronectin structure and function (10 -12, 14). The altered, oligomeric form of vitronectin is generated, at least in part, by interactions with other plasma proteins such as thrombin-antithrombin complexes (11, 12, 14, 15, and complement C5b-9 complexes (11, 12, 16).A portion of vitronectin in plasma (17,18), and in platelets is complexed with type 1 plasminogen activator inhibitor (PAI-1) 1 (8,9,19), an interaction that induces the formation of higher order complexes (4,5,20,21) and influences the structure and function of both PAI-1 and vitronectin. Thus, when bound to vitronectin, PAI-1 is stabilized in its active conforma...
Culture procedures for isolation of thermophilic campylobacters from food matrices are complex, labor intensive, and time-consuming. Most available methods include the use of antibiotics as selective agents to prevent the growth of competing microflora. A simple procedure for isolation of thermophilic campylobacters after enrichment in Rosef's enrichment broth was developed using a hydrophobic grid membrane filter (HGMF) on semisolid medium (SSM). SSM contains no antibiotics, and the HGMF physically separates Campylobacter from the enrichment broth, allowing isolation based on differential motility. The HGMF-SSM method was compared to the Agriculture and Agri-Food Canada Food Safety Procedures Manual (FSPM-10) method (Isolation of Thermophilic Campylobacters from Fresh Pork, Beef Veal, Poultry and Ready-to-Eat Meat Products), which includes the use of selective antibiotics. During the initial study, after enrichment the HGMF-SSM method yielded pure cultures of campylobacters after 16 to 18 h (overnight) compared with 48 h for the FSPM-10 method. Ninety-four turkey samples collected at local retail stores and 38 frozen pig fecal samples were processed by both methods. Thirty-five samples (26.5%) were positive by the HGMF-SSM method; 24 (18.2%) of these positive samples contained Campylobacter jejuni and 11 (8.3%) contained Campylobacter coli. With the FSPM-10 method, 25 samples (18.9%) were positive: 21 (15.9%) with C. jejuni and 4 (3%) with C. coli. For a subsequent field study, only the HGMF-SSM method was used to isolate Campylobacter from 1,200 chicken samples and 454 turkey samples sold at retail. Analysis of five subisolates from various samples indicated that only one type of Campylobacter was recovered by the HGMF-SSM method, as ascertained by MICs for 10 antimicrobials, sequencing of the short variable region of the flaA gene, and fingerprinting based on amplified fragment length polymorphism. The absence of antibiotics in the SSM may explain the higher recovery of thermophilic campylobacters. The HGMF-SSM method resulted in improved isolation of campylobacters and is simpler, faster, cheaper, and less labor intensive than the FSPM-10 method. The recovery of one type of Campylobacter from the chicken samples may have important implications, particularly in epidemiological studies.
Objective To study the fibrinolytic pathways and their relationship with the contact system in women using combined oral contraceptives (COCs).Design Serial plasma samples were collected from 18 women before treatment with COCs containing 30 μg oestrogen during treatment cycles 3 and 6, and 2 weeks after stopping treatment. Fibrinolysis was measured before and after dextran sulphate mediated contact activation using fibrin plates.Results Fibrinolysis increased significantly during cycles 3 and 6 (from 77% to 100% and 113%, respectively, P<0.01) and showed a further increase after dextran sulphate activation (from 134% to 158% and 167%, respectively, P<0.01). Tissue‐plasminogen activator, urokinase‐plasminogen activator and plasminogen activator inhibitor did not change significantly. There were significant elevations of Factor XII (from 0.92 μ/ml to 1.43 u/ml, P<0.01) and prekallikrein (0.94 u/ml to 1.10 u/ml, P<0.05) in cycle 3, which both remained high at cycle 6 (P<0.01) and decreased after stopping the COC. Alpha‐2‐macroglobulin and C1‐esterase inhibitor showed no significant change, but alpha‐1‐antitrypsin increased from 0.85 u/ml to 1.11 u/ml by cycle 3 (P<0.01), and returned to near normal levels after stopping the COC.Conclusions The increase in fibrinolysis may be due to increased levels of Factor XII and prekallikrein without a corresponding increase in their natural inhibitors (C1‐esterase inhibitor and alpha‐2‐macroglobulin). A parallel increase in the intrinsic pathway of coagulation may be limited by elevated alpha‐1‐antitrypsin at the level of activated Factor XI. The increase in fibrinolysis caused by oral contraceptives may balance any potential thrombotic risk due to increased fibrinogen or vitamin K dependent coagulation factors.
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