Enhanced mucosal fibrinolytic activity in gastroduodenal ulcer haemorrhage and the beneficial effect of acid suppression.

BACKGROUND: The high mortality rate in patients with upper gastrointestinal bleeding appears to be particularly related to re-bleeding. The haemostatic mechanisms that may influence the re-bleeding of ulcers are largely unknown. AIM: We studied and analysed fibrinolytic activity in bleeding ulcer patients and the effect of acid suppression on this activity. METHODS: Fibrinolytic activity was analysed in mucosal biopsies from 29 bleeding gastroduodenal ulcer patients and six controls. We analysed levels of D-Dimer, fibrin plate lysis area, plasminogen activator activity, plasminogen activator inhibitor activity, and plasmin antiplasmin complexes. RESULTS: Significantly more fibrinolytic activity was detected in biopsies from patients with bleeding ulcers compared to controls. Moreover, in patients with endoscopic stigmata of recent haemorrhage, mucosal fibrinolytic activity was higher compared to patients without stigmata of recent haemorrhage. In mucosal biopsies of patients that had used acid suppression before admission, a decreased fibrinolytic activity was found compared to patients without such therapy. This effect of acid suppression on fibrinolytic activity was confirmed in nine patients before and after a 24-h ranitidine infusion. CONCLUSIONS: Fibrinolytic activity is enhanced in patients with bleeding gastroduodenal ulcers. Acid suppressive therapy decreases this increased activity, which may be one of the mechanisms explaining the potential beneficial effect of this therapy.

Differential display identification of 40 genes with altered expression in activated human smooth muscle cells. Local expression in atherosclerotic lesions of smags, smooth muscle activation-specific genes.

Detailed knowledge on the molecular and cellular mechanisms that control (re)-differentiation of vascular smooth muscle cells (SMCs) is critical to understanding the pathological processes underlying atherogenesis. We identified by differential display/reverse transcriptase-polymerase chain reaction 40 genes with altered expression in cultured SMCs upon stimulation with the conditioned medium of activated macrophages. This set of genes comprises 10 known genes and 30 novel genes, which we call "smags" (for smooth muscle activation-specific genes). To determine the in vivo significance of these (novel) genes in atherogenesis, we performed in situ hybridization experiments on vascular tissue. Specifically, FLICE (Fas-associated death domain-like interleukin-1beta-converting enzyme)-like inhibitory protein (FLIP) is expressed in neointimal SMCs as well as in lesion macrophages and endothelial cells, whereas the expression of the novel genes smag-63, smag-64, and smag-84 is restricted to neointimal SMCs. Characterization of full-length smag-64 cDNA revealed that it encodes a novel protein of 66 amino acids. smag-82 cDNA comprises the complete, unknown, 3'-untranslated region of fibroblast growth factor-5. Collectively, our results illustrate the complex changes of SMC gene expression that occur in response to stimulation with cytokines and growth factors secreted by activated macrophages. Moreover, we identified interesting candidate genes that may play a role in the differentiation of SMCs during atherogenesis.

Antiplatelet therapy and other interventions after revascularisation procedures in patients with peripheral arterial disease: a meta-analysis.

OBJECTIVES: To evaluate the efficacy of conservative adjuvant therapy after revascularisation procedures in patients with peripheral arterial disease. DESIGN: meta-analysis. MATERIALS: English-language studies published from 1976 to 1997. METHODS: Reports on conservative therapies in patients with peripheral arterial disease after percutaneous transluminal angioplasty, endarterectomy, thromboendarterectomy or bypass grafting were eligible. Uncontrolled or retrospective studies, double reports or trials without clinical outcomes were excluded. Included studies were graded as level 1 (randomised and double- or assessor-blind), level 2 (open randomised), or level 3 (non-randomised comparative). (Loss of) patency, amputation, vascular events and mortality were the outcomes considered. When feasible, end-of-treatment results, either continuous or binary, were combined with appropriate statistical methods. RESULTS: Thirty-two studies were included. Compared to non-active control, aspirin with dipyridamole improved (loss of) patency (odds ratio (OR) 0.69, 95% confidence interval (CI), 0.53 to 0.90) and mortality (OR 0.80, 95% CI, 0.57 to 1.14); ticlopidine improved (loss of) patency (OR 0.53, 95% CI, 0.33 to 0.85) and amputation (OR 0.29, 95% CI, 0.08 to 1.01). Data on the effectiveness of vitamin-K inhibitors were not conclusive. CONCLUSIONS: Patients with peripheral arterial disease improve their outcome by receiving aspirin with dipyridamole or ticlopidine after a revascularisation procedure.

Evolution of therapies in deep vein thrombosis management.

Recent years have witnessed significant advances in the prevention and treatment of deep vein thrombosis (DVT). Although anticoagulants have been available for over 60 years, thromboprophylaxis has been widely adopted only over the last decade, mainly in surgical patients. Unfractionated heparin (UFH) and oral anticoagulants are effective as thromboprophylaxis and in the treatment of DVT, but significant drawbacks with both methods, combined with improved understanding of the pathogenesis of thromboembolism, have prompted investigation of novel physical and pharmacological approaches. In particular, the development since 1976 of low-molecular-weight heparins (LMWHs), with their increased convenience and superior benefit:risk ratio, has revolutionized the approach to DVT prophylaxis. However, persistent treatment failure in some patient groups and underlying trends in medical care, such as the increasing move toward outpatient management, are fuelling continuing efforts to develop improved agents. This review provides a brief overview of DVT prophylaxis and treatment, focusing on the historical developments in the use of heparin, and highlighting the likely direction of future progress.

[Clinical research and pharmaceutical industry. A relationship with advantages and disadvantages]. / Klinisch onderzoekers en farmaceutische industrie. Een relatie met voor- en nadelen.

Medical specialists and biomedical scientists are increasingly participating in research into the efficacy and safety of new drugs developed by the pharmaceutical industry. Participation may mean a position as an independent member of committees that monitor safety and effectiveness of the research for the patient, or are responsible for publication after termination of the research. This co-operation with the pharmaceutical industry has substantial advantages, such as the occupation of a prominent scientific position in developing and protocolling trials, promotion of employment and doctoral research, and of the quality of the research, particularly if it is followed by inspection by drugs registration colleges. However, the co-operation has adverse effects as well, especially if personal financial interests of the research workers become the main motivation. This applies also to an excessively dominant position of industry-sponsored research, diminishing the chances of medical scientific research which, although necessary, is difficult or almost impossible to finance.

[Clinical researchers and the pharmaceutical industry]. / Klinisch onderzoekers en farmaceutische industrie.

The diminished financial support by the government of clinical investigation has led to clinical units that depend for their infrastructure largely on contract research for the pharmaceutical industry. This poses a threat to the independence of scientific research, to the freedom to publish scientific results and to the continuity of the research. Moreover, it is not easy for a researcher to retain a position of integrity and independence in the face of a jungle of conflicting interests and not to let personal interests prevail. The difficult relation between the physician and the pharmaceutical industry is the subject of a forthcoming short series of articles.

Review: infectious diseases and coagulation disorders.

Infection, both bacterial and nonbacterial, may be associated with coagulation disorders, resulting in disseminated intravascular coagulation and multiorgan failure. In the last few decades a series of in vivo and in vitro studies has provided more insight into the pathogenetic mechanisms and the role of cytokines in these processes. Because of the growing interest in this field, the complexity of the subject, and the fact that many physicians must deal with a variety of infections, current data are reviewed on the association between infectious diseases and the coagulation system. Novel therapeutic intervention strategies that will probably become available in the near future are mentioned, along with those of special interest for infectious disorders for which only supportive care can be given.

Antithrombotic drugs in the primary medical management of intermittent claudication: a meta-analysis.

BACKGROUND: There is no consensus on the efficacy of the antithrombotic drugs available for patients with intermittent claudication. METHODS: A Medline and manual search was used to identify relevant publications. Uncontrolled or retrospective studies, double reports or trials without clinical outcomes were excluded. Included studies were graded as level 1 (randomised and double- or assessor-blind), level 2 (open randomised), or level 3 (non-randomised comparative). Mortality, cerebro- or cardiovascular events, amputations, arterial occlusions or number of revascularization procedures performed in the lower limbs, pain-free and total walking distance, ankle brachial index and calf blood flow, were the main outcomes considered. When feasible, end of treatment results, either continuous or binary, were combined with appropriate statistical methods. RESULTS: Mortality was significantly decreased by ticlopidine compared to placebo (common odds ratio 0.68, 95% C.I., 0.49 - 0.95); clopidogrel decreased vascular events in comparison to aspirin (odds ratio 0.76, 95% C.I., 0.63 - 0.92) in level 1 studies. Arterial occlusions and the number of revascularization procedures performed were statistically significantly decreased by aspirin and ticlopidine, respectively. A small but statistically significant improvement in pain-free walking distance was determined by picotamide, indobufen, low molecular weight heparins, sulodexide and defibrotide, in small studies. CONCLUSIONS: Clopidogrel and ticlopidine do reduce clinically important events in patients with intermittent claudication and could be added to the primary medical treatment of these patients. The use of aspirin in these patients cannot be based on direct evidence, but only on analogy with coronary and cerebral atherosclerosis, where it has documented efficacy. Other antithrombotic drugs were not properly evaluated in patients with intermittent claudication.

Beneficial effects of conversion from cyclosporine to azathioprine on fibrinolysis in renal transplant recipients.

Cyclosporin A (CsA) has been implicated as one of the factors contributing to the high cardiovascular morbidity and mortality after renal transplantation. This may be mediated by either a high prevalence of conventional risk factors for atherosclerosis, such as hypertension, hypercholesterolemia, and diabetes mellitus, or by impairment of the fibrinolytic activity evoked by CsA, possibly through interference with prostanoid metabolism. We therefore assessed the impact of conversion of CsA to azathioprine immunosuppressive treatment on parameters of fibrinolytic activity and plasma concentration of the prostanoids prostaglandin E2 and thromboxane B2 in 18 stable renal transplant recipients. During CsA, mean arterial pressure and serum creatinine were significantly higher than during azathioprine (116+/-15 mm Hg versus 106+/-13 mm Hg, P=0.0003; and 147+/-34 micromol/L versus 127+/-35 micromol/L, P=0.002; mean+/-SD). On conversion, the plasma tissue plasminogen activator activity increased from 1.2 (1.1 to 1.7; median, 95% CI) to 1.8 (1.6 to 2.0) IU/mL (P=0.011), without a significant change of the plasminogen activator antigen concentration. This was associated with a substantial decrease in plasminogen activator inhibitor-1 activity from 10.4 (8.5 to 16.7) to 6.4 (5.6 to 9.2) IU/mL (P=0.009). Furthermore, plasma levels of prostaglandin E2 and thromboxane B2 markedly decreased (from 9.7 [7.4 to 12.9] to 4.6 [4.3 to 8.1] pg/mL, P=0.0006; and from 106.1 [91.7 to 214.2] to 70.2 [50.3 to 85.6] pg/mL, P=0.002, respectively). During CsA, but not azathioprine, plasma tissue plasminogen activator antigen and plasminogen activator inhibitor-1 levels correlated significantly with prostaglandin E2 (r=0.53, P=0.02; and r=0.60, P=0.008, respectively), and thromboxane B2 (r=0.75, P=0.0001; and r=0.77, P=0.0001, respectively) levels. In conclusion, CsA induced substantial impairment of fibrinolytic activity, which recovered after conversion to azathioprine. The impaired fibrinolysis observed during CsA treatment may be caused by modulation of eicosanoid production or metabolism in vascular endothelial cells and possibly contributes to the high incidence of cardiovascular disease after kidney transplantation.

Vascular endothelial genes that are responsive to tumor necrosis factor-alpha in vitro are expressed in atherosclerotic lesions, including inhibitor of apoptosis protein-1, stannin, and two novel genes.

Activation and dysfunction of endothelial cells play a prominent role in patho-physiological processes such as atherosclerosis. We describe the identification by differential display of 106 cytokine-responsive gene fragments from endothelial cells, activated by monocyte conditioned medium or tumor necrosis factor-alpha. A minority of the fragments (22/106) represent known genes involved in various processes, including leukocyte trafficking, vesicular transport, cell cycle control, apoptosis, and cellular protection against oxidative stress. Full-length cDNA clones were obtained for five novel transcripts that were induced or repressed more than 10-fold in vitro. These novel human cDNAs CA2_1, CG12_1, GG10_2, AG8_1, and GG2_1 encode inhibitor of apoptosis protein-1 (hIAP-1), homologues of apolipoprotein-L, mouse rabkinesin-6, rat stannin, and a novel 188 amino acid protein, respectively. Expression of 4 novel transcripts is shown by in situ hybridization on healthy and atherosclerotic vascular tissue, using monocyte chemotactic protein-1 as a marker for inflammation. CA2_1 (hIAP-1) and AG8_1 are expressed by endothelial cells and macrophage foam cells of the inflamed vascular wall. CG12_1 (apolipoprotein-L like) was specifically expressed in endothelial cells lining the normal and atherosclerotic iliac artery and aorta. These results substantiate the complex change in the gene expression pattern of vascular endothelial cells, which accompanies the inflammatory reaction of atherosclerotic lesions.

Treatment of intermittent claudication with physical training, smoking cessation, pentoxifylline, or nafronyl: a meta-analysis.

BACKGROUND: There is no consensus on the efficacy of physical training, smoking cessation, and pharmacological therapy (pentoxifylline or nafronyl oxalate) in the treatment of patients with intermittent claudication at Fontaine stage II of disease. METHODS: A MEDLINE and manual search was used to identify relevant publications. Uncontrolled or retrospective studies, double reports, and trials without clinically meaningful outcomes were excluded. Included studies were graded level 1 (randomized and double- or assessor-blind), level 2 (open randomized), or level 3 (nonrandomized). Pain-free and total walking distance were the main outcomes considered; when feasible, end-of-treatment results were combined with appropriate meta-analytical procedures. RESULTS: In 5 level 2 studies, physical training increased pain-free and total walking distance significantly (139.0 m [95% confidence interval {CI}, 31.0 to 246.9 m] and 179.1 m [95% CI, 60.2 to 298.1 m], respectively). In a level 3 study, smoking cessation resulted in a nonsignificant increase in total walking distance of 46.7 m (95% CI, -19.3 to 112.7 m). In 6 level 1 studies, pentoxifylline increased both pain-free and total walking distance by 21.0 m (95% CI, 0.7 to 41.3 m) and 43.8 m (95% CI, 14.1 to 73.6 m), respectively. In 4 level 1 trials, nafronyl significantly increased pain-free walking distance (58.6 m [95% CI, 30.4 to 86.8 m]) and total walking distance (71.2 m [95% CI, 13.3 to 129.0 m]). CONCLUSIONS: Physical training increased pain-free and total walking distance in level 2 studies. Only level 3 studies support the usefulness of smoking cessation. In level 1 studies, pentoxifylline and nafronyl increased pain-free and total walking distance, but the average effects were relatively small.

Fibrinogen-coated albumin microcapsules reduce bleeding in severely thrombocytopenic rabbits.

Severe thrombocytopenia frequently occurs in patients receiving chemotherapy and in patients with autoimmune disorders. Thrombocytopenia is associated with bleeding, which may be serious and life threatening. Current treatment strategies for thrombocytopenia may require transfusion of allogeneic platelets, which is associated with serious drawbacks. These include the occurrence of anti-platelet antibodies, which may result in refractoriness to further platelet transfusions, and the potential risk of transfer of blood-borne diseases. Therefore, we have recently developed a platelet substitute product (Synthocytes), which is composed of human albumin microcapsules with fibrinogen immobilized on their surface. Here we show that the intravenous administration of these microcapsules not only corrects the prolonged bleeding time in rabbits rendered thrombocytopenic either by anti-platelet antibodies or by chemotherapy, but also reduces bleeding from surgical wounds inflicted in the abdominal skin and musculature. No potential systemic prothrombotic effect of the microcapsules was observed in a model of rabbit venous thrombosis. As for the mechanism of action, experiments with normal and thrombocytopenic human blood in an endothelial cell matrix-coated perfusion chamber demonstrated an interaction between the fibrinogen-coated albumin microcapsules and native platelets. It was shown that the fibrinogen-coated albumin microcapsules could facilitate platelet adhesion to endothelial cell matrix and correct the impaired formation of platelet aggregates in relatively platelet-poor blood. This study indicates that fibrinogen-coated albumin microcapsules can act to improve primary hemostasis under thrombocytopenic conditions and may eventually be a promising agent for prophylaxis and treatment of bleeding in patients with severe thrombocytopenia.

Rational antithrombotic therapy and prophylaxis in elderly, immobile patients.

The aging process is associated with increased coagulation and fibrinolysis parameters, resulting in an overall 'prethrombotic state'. This probably explains the increased baseline susceptibility of elderly patients to the development of thromboembolic disease. Additional factors such as major surgery or malignant disease multiply the risk of thromboembolism in this population. Even when adequate antithrombotic therapy is instituted, the mortality associated with thromboembolic disease remains considerable; this underlines the importance of adequate thromboembolic prophylaxis. At present, the use of low molecular weight heparins (LMWHs) in elderly immobile patients appears to be the most effective approach to prophylaxis. The use of compression stockings seems to be effective in the prevention of venous thrombosis, at least in moderate risk surgical patients. In patients undergoing orthopaedic surgery, additional prophylaxis (e.g. with an LMWH) is necessary. In the management of venous thrombosis, patients can initially be treated with a bodyweight-adjusted dosage of an LMWH. In patients with deep vein leg thrombosis or pulmonary embolism, oral anticoagulant therapy should be started as soon as possible, and should be continued for 6 months. However, before starting prophylaxis or therapy, an individual risk assessment should be performed in which the benefits and disadvantages are balanced. Most of the large trials that have studied the effects of thromboembolic prophylaxis have focused on postsurgical patients. However, it will be of great interest to develop more specific prophylactic and therapeutic regimens for different nonsurgical high risk subgroups of patients, particularly the elderly.

Are safety committees really safe?

In an increasing number of recent major clinical trials, independent safety committees or safety monitors have been involved. Their role and function is not yet defined and continues to evolve. The aim of this paper is to discuss the role and tasks of safety committees as a result of our collective experience as members of three safety committees of studies evaluating antithrombotic prophylaxis against postoperative deep vein thrombosis. We believe that the type of pharmacological intervention used is of less importance than the general experiences gained, which can be extrapolated to other studies and should stimulate a more general debate.

Use of a heparin nomogram for treatment of patients with venous thromboembolism in a community hospital.

BACKGROUND: The application of a heparin dosing nomogram in the treatment of patients with venous thromboembolism resulted in improvement of heparin therapy in clinical research settings. In 1992 a heparin nomogram was introduced in our hospital, which is a community hospital where anticoagulant therapy is supervised by the attending physicians. We studied whether comparable improvements were achieved in such a non-surveyed clinical setting. METHODS: Patients were identified from computerized discharge records, and classified into a pre-nomogram (discharged in 1990 or 1991) and a nomogram patient group (discharged in 1993 or 1994). The use of the nomogram was encouraged but the application remained on a voluntary basis. Since the definition of the target APTT range was different in the pre-nomogram period as compared to the nomogram period, a formal analysis of pre- and post-nomogram results was not considered justified. RESULTS: The APTT ratio, six hours after the start of heparin treatment, was below the predefined lower limit in 72% of 127 patients in the pre-nomogram group and in 13% of 127 patients in the nomogram group. During 1043 days heparin therapy in the nomogram group the morning APTT ratio was subtherapeutic in 8%. In 58% of all APTT results the physician responded according to the nomogram. The subsequent APTT was in the target range in 64% of the cases compared to 31% if the adjustement was not performed according to the nomogram (P<.0001). Major bleeding episodes occurred in 3.1% in the pre-nomogram period and in 0.7% in the nomogram period. CONCLUSION: The present study shows that the introduction of a heparin dosing nomogram in a non-research clinical setting results in more adequate heparin anticoagulation with low risks of bleeding.

Differential effects of anti-cytokine treatment on bronchoalveolar hemostasis in endotoxemic chimpanzees.

Activation and inhibition of coagulation and fibrinolysis was analyzed in bronchoalveolar lavage (BAL) fluids obtained from endotoxin-challenged chimpanzees. The mediatory role of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) on endotoxin-induced changes in bronchoalveolar coagulation and fibrinolysis was investigated in experiments in which the infusion of endotoxin was combined with the administration of monoclonal anti-TNF-alpha or anti-IL-6 antibodies. Endotoxin infusion elicited a marked increase in bronchoalveolar thrombin generation as measured by levels of prothrombin activation fragment F1+2 and thrombin-antithrombin complexes. Markers for intrinsic pathway activation were not detectable, suggesting that the thrombin generation was mediated by the tissue factor-dependent route. Levels of antithrombin were low before the injection of endotoxin and not detectable hereafter. The administration of anti-IL-6 antibody completely abolished the endotoxin-induced activation of bronchoalveolar coagulation, whereas treatment with anti-TNF-alpha antibody only partly inhibited this effect. Bronchoalveolar fibrinolytic activity, due to urokinase-type plasminogen activator (u-PA), was significantly depressed after endotoxin injection, mainly due to a striking increase in plasminogen activator inhibitor-2 levels in BAL fluid. The endotoxin-induced effects on bronchoalveolar fibrinolysis could be blocked by the simultaneous administration of anti- TNF-alpha antibodies. We conclude that endotoxemia results in the activation of bronchoalveolar coagulation, which is apparently mediated by the tissue factor route of coagulation activation and which may be amplified by consumption of antithrombin III. Bronchoalveolar fibrinolytic activity is significantly abolished by increased levels of mainly PAI-2 after the injection of endotoxin. The endotoxin-induced effects on bronchoalveolar coagulation appears to be mediated by IL-6, whereas TNF-alpha seems to be the pivotal mediator of the endotoxin-induced depression of bronchoalveolar fibrinolysis.

A human alloantibody interferes with binding of factor IXa to the factor VIII light chain.

Inhibitory antibodies directed against factor VIII develop in a substantial number of patients with hemophilia A as a consequence of factor VIII replacement therapy. These antibodies usually recognize discrete epitopes within the A2 and/or the C2 domains of factor VIII. Here, we have characterized the antibodies present in the plasma of a patient affected by severe hemophilia A. The antibodies reacted readily with the metabolically labeled factor VIII light chain and fragments thereof when analyzed by immunoprecipitation. The inhibitory activity could be neutralized by the complete light chain, whereas only slight neutralization occurred with a fragment comprising the isolated C2 domain. Binding of the majority of antibodies to in vitro synthesized factor VIII fragments was dependent on the presence of amino acid residues Gln1778-Met1823, a region known to contain a factor IXa binding site. Functional characterization showed that purified IgG from the patient's serum inhibited binding of factor IXa to immobilized factor VIII light chain in a dose-dependent manner. These data indicate that human alloantibodies may inhibit factor VIII activity by interfering with factor IXa-factor VIIIa complex assembly.

Impaired haemostasis by intravenous administration of a gelatin-based plasma expander in human subjects.

The aim of this study was to investigate the effects of a gelatin-based plasma expander on blood coagulation and haemostasis in human subjects. Six healthy men were studied in a randomised, controlled cross-over study to investigate the effects of a 60 min intravenous infusion of either 1 l gelatin-based plasma substitute (Gelofusine) or 0.9% NaCl (control). The infusion of gelatin resulted in a 1.7 fold increase in bleeding time at 60 min and a 1.4 fold increase at 120 min, while saline had no effect (p <0.05). Aggregation studies revealed a significant impairment of ristocetin-induced platelet aggregation (p <0.05), associated with a substantial decrease of vWF:ag (-32% vs. -5%, p <0.05) and ristocetin co-factor (-29% vs. +1%, p <0.05) and without in vitro impairment of the platelet glycoprotein 1b receptor. Gelatin caused a decrease in thrombin-antithrombin complexes (-45% vs. -4%, p <0.05) and F1+2 (-40% vs. +1%, p <0.05). The decrease in circulating levels of vWF:ag, vWF R:Co, thrombin-antithrombin complexes and F1+2 was more than could be expected by the calculated plasma-dilution generated by Gelofusine. Our results demonstrated that the administration of a gelatin-based plasma substitute results in a significant impairment of primary haemostasis and thrombin generation. The defect in primary haemostasis appears to be related to a gelatin-induced reduction in von Willebrand factor, whereas the decreased thrombin generation may be due to the dilution of coagulation factors induced by Gelofusine.