Biomedical subjects
Publications and source records attributed to F W Leebeek.
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Deep venous thrombosis of the upper extremity (DVTUE) is a rare thrombotic disorder that may occur spontaneously but is most often related to predisposing factors, such as an indwelling central venous catheter, malignancy, or exercise. The role of coagulation disorders, i.e., a hypercoagulable state in the pathogenesis of DVTUE is not well known. We have evaluated both genetic and acquired thrombophilia parameters in consecutive patients with DVTUE. A hypercoagulable state was found in 32% of the patients. The most frequent coagulation abnormality was the presence of lupus anticoagulant or anticardiolipin antibodies (27%). Factor V Leiden mutation was detected in two patients, antithrombin deficiency in one, and none of the patients had the prothrombin G20210A gene variant or protein C or S deficiency. The prevalence of coagulation abnormalities was not significantly different in a subgroup of patients with spontaneous DVTUE as compared to those with an obvious predisposing factor, such as an indwelling central venous catheter. We conclude that antiphospholipid antibodies are frequently found in patients with DVTUE. Factor V Leiden mutation, prothrombin 20210A gene variant, protein C deficiency, and protein S deficiency do not seem to play a major pathogenetic role in DVTUE.
BACKGROUND AND AIMS: The bleeding tendency of patients suffering from cirrhosis is in part ascribed to accelerated fibrinolysis. In this study, the role of the recently discovered inhibitor of fibrinolysis, thrombin-activatable fibrinolysis inhibitor (TAFI) in cirrhosis was examined. METHODS: In 64 patients with cirrhosis of varying severity, TAFI antigen levels were measured by enzyme-linked immunosorbent assay and compared with TAFI levels in control subjects. Furthermore, a plasma-based fibrinolysis assay was performed in the presence and absence of a specific inhibitor of activated TAFI. RESULTS: TAFI levels were decreased in cirrhosis. Mean TAFI levels were 66% in Child's A, 55% in Child's B, 47% in Child's C cirrhosis, and 26% in acute liver failure. Decreased TAFI antigen levels were highly correlated with antithrombin and alpha(2)-antiplasmin activity levels. Clot lysis times and clot lysis ratio (defined as ratio between clot lysis time in the absence and presence of a specific inhibitor of activated TAFI) of cirrhotics were not significantly different from healthy controls. CONCLUSIONS: Despite decreased levels of TAFI and other components of the fibrinolytic system, no evidence of increased plasma fibrinolytic potential in cirrhosis is observed using the plasma-based assay of this study. The reduction of antifibrinolytic factors in cirrhosis is compensated by the concomitant reduction in profibrinolytics.
Cardiovascular risk is increased in GH deficiency (GHD). GHD adults are frequently abdominally obese and display features of the metabolic syndrome. Otherwise healthy abdominally obese subjects have low GH levels and show features of the metabolic syndrome as well. We investigated in healthy nonobese males the effect of the GH receptor antagonist pegvisomant in different metabolic conditions. This is a model for acute GHD without the alterations in body composition associated with GHD. We compared the effect of pegvisomant with that of placebo before and after 3 d of fasting. In addition, we investigated the effect of pegvisomant under normal, i.e. fed, conditions. Three days of fasting as well as pegvisomant alone decreased serum free IGF-I levels (1.0 +/- 0.15 vs. 0.31 +/- 0.05 ng/ml and 0.86 +/- 0.23 vs. 0.46 +/- 0.23 ng/ml, respectively). Fasting in combination with pegvisomant also decreased serum free IGF-I levels (1.0 +/- 0.15 vs. 0.31 +/- 0.07 ng/ml). Treatment with pegvisomant had no additional influence on the decline of free IGF-I induced by fasting. Pegvisomant alone had no influence on insulin sensitivity. The increase in insulin sensitivity induced by fasting was comparable to the increase in insulin sensitivity induced by fasting combined with pegvisomant. Among serum lipid concentrations, only serum triglycerides increased significantly as a result of pegvisomant alone (1.0 +/- 0.2 vs. 1.6 +/- 0.4 mmol/liter). The changes in lipid concentrations induced by fasting alone or pegvisomant were not different from those induced by pegvisomant alone. von Willebrand factor antigen levels declined significantly under the influence of pegvisomant alone (1.1 +/- 0.07 vs. 0.8 +/- 0.06 U/ml). In conclusion, in different metabolic conditions the GH receptor antagonist pegvisomant induces no significant acute changes in the major risk markers for cardiovascular disease. These data suggest that the secondary metabolic changes, e.g. abdominal obesity or inflammatory factors, that develop as a result of long-standing GHD are of primary importance in the pathogenesis of atherosclerosis in patients with GHD.
Thrombosis of the upper extremity is frequently (30-52%) related to the use of an indwelling venous catheter, but it can also occur in healthy individuals after exercise. In the past it was considered a relatively benign thrombotic event, which was treated conservatively, sometimes even without anticoagulant therapy. Recent studies have shown that complications of deep venous thrombosis of the upper extremity occur frequently: pulmonary embolism (8-36%), recurrence thrombosis after cessation of anticoagulant treatment (2-15%) and post-thrombotic syndrome (up to 50%). Therefore when thrombosis of the upper extremity is clinically suspected, it should be objectively diagnosed by compression echography followed if negative by phlebography, with anticoagulant treatment directly afterward, preferably with low-molecular heparin and then acenocoumarol or phenprocoumon.
Portal vein thrombosis (PVT) has a heterogeneous aetiology. Recently discovered thrombotic risk factors such as latent myeloproliferative disorders and prothrombotic genetic defects are important in the aetiology of PVT. At least one-third of the PVT patients exhibit a combination of thrombotic risk factors. Treatment with anticoagulant drugs has not proved beneficial for most PVT patients. Therapy with anticoagulants is only recommended in those with acute PVT, in those who recently underwent a portosystemic shunt procedure and in those with other thrombotic manifestations, particularly in case of proved hypercoagulability. Due to intact coagulation, oesophageal varices bleeding in patients with PVT has a better prognosis than in cirrhotics.
We describe a 33-year-old woman, who presented with lowered consciousness level and seizures, due to cerebral venous sinus thrombosis with venous haemorrhagic infarcts. The patient. who was taking oral contraceptives, appeared to be heterozygous for a prothrombin gene variant, which is due to a G-->A transition at position 20210. This 20210A prothrombin has recently been established as an important risk factor for cerebral venous sinus thrombosis, which interacts with oral contraceptive use.
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We present the first case of Budd-Chiari syndrome in association with portal and mesenteric vein thrombosis in a patient homozygous for the factor V Leiden mutation. She was treated by transjugular intrahepatic portosystemic stent (TIPS) placement followed by local thrombolytic therapy. Venous outflow from the liver was established and the thrombi in the portal and mesenteric veins were lysed completely. This therapeutic approach may be used for such patients with this severe thrombotic event, who generally have a poor prognosis.
BACKGROUND: Bladder instillations with Bacillus Calmette-Guerin (BCG) are commonly used as immunotherapy for bladder carcinoma. Sometimes patients experience serious systemic side effects, such as sepsis or pneumonitis. Granulomatous hepatitis is a rare serious side effect, which has been considered a hypersensitivity reaction to BCG. PATIENT: The first case of granulomatous hepatitis after BCG bladder instillation in which mycobacteria were identified by staining techniques and mycobacterial DNA was detected in liver tissue using the polymerase chain reaction is reported. CONCLUSION: The granulomatous hepatitis was caused by BCG infection of the liver after haematogenous dissemination of BCG, rather than hypersensitivity.
Rhabdomyolysis is characterized by local or generalized skeletal muscle necrosis. It is caused by many clinical conditions and drug or alcohol abuse. Clinical symptoms are muscle pain and muscle weakness. Laboratory investigations show a rise in serum creatine phosphokinase and electrolyte disturbances. The most serious complication is acute renal failure. We present a patient with rhabdomyolysis and renal failure associated with a recent Influenza A virus infection.
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We have studied the response of haemostatic reaction products in peripheral blood of patients with acute ischaemic heart disease receiving combined recombinant tissue type plasminogen activator/heparin therapy. We have found evidence that formation of excessive amounts of plasmin in vivo in relation to such therapy significantly enhances the degradation of fibrin, and of fibrinogen as well as the formation of thrombin. We conclude that excessive plasmin formation by thrombolytic therapy causes systemic effects including activation of coagulation.
BACKGROUND: We and others have demonstrated that administration of thrombolytic agents causes the generation of thrombosis-promoting agents. At present, we have studied whether formation in vivo of excessive amounts of plasmin is responsible for the activation of coagulation in patients treated with recombinant tissue-type plasminogen activator. METHODS: Modified crossed immunoelectrophoresis was used for determination of the plasminogen-binding form of alpha 2-antiplasmin. Enzyme-linked immunosorbent assay methods were used for determination of hemostatic reaction products. RESULTS: The association between the generation of hemostatic reaction products and the exhaustion of the plasminogen-binding form of alpha 2-antiplasmin (PB alpha 2AP) was studied in 21 patients with acute myocardial infarction and 11 patients with unstable angina pectoris who were given a 3-hour, 100-mg intravenous infusion of recombinant tissue-type plasminogen activator (rt-PA). We observed in all patients a fall in blood concentrations of PB alpha 2AP (P < 0.01) after 2.25 hours of treatment and, simultaneously, a significant increase in fibrin degradation products (P < 0.01), D-dimer (P < 0.01), fibrinogen degradation products (P < 0.01), prothrombin fragment 1 + 2 (P < 0.01), and thrombin-antithrombin III complexes (P < 0.01). When we evaluated individual data, we observed high concentrations of the reaction products when the PB alpha 2AP concentration after 2.25 hours of treatment was lower than 25% of the pretreatment values. Also, we observed highly significant associations between the increase in the plasma concentrations of fibrin degradation products and thrombin-antithrombin III complexes (rs = 0.72; P < 0.01), the increase in plasma concentrations of fibrin degradation products and prothrombin fragment 1 + 2 (rs = 0.63; P < 0.01), the increase in plasma concentrations of D-dimer and thrombin-antithrombin III complexes (rs = 0.78; P < 0.01), and the increase in plasma concentrations of D-dimer and prothrombin fragment 1 + 2 (rs = 0.79; P < 0.01). CONCLUSIONS: Generation of excessive amounts of plasmin is the main factor in producing the procoagulant response in patients who receive thrombolytic therapy with rt-PA, and intravenous heparin does not abolish this response. Plasmin inhibitors might be used in relation to thrombolytic therapy as indirect "antithrombotics."
To identify a receptor binding site of human interleukin-6 (IL-6), we created a library of IL-6 variants with single amino acid substitutions in the last 15 residues (171-185) in the COOH terminus of IL-6. Twenty-seven IL-6 variants were tested for biological activity on a human hepatoma and a mouse hybridoma cell line. Most variants were additionally tested in a receptor binding assay using a human myeloma cell line. Several single amino acid substitutions in the COOH terminus of IL-6 were found to decrease biological activity significantly. This is especially seen in variants with amino acid substitutions that alter the postulated amphipathical alpha-helix structure between residues 178 and 183. The two highly conserved Arg residues at positions 180 and 183 seem to play a very important role in biological activity. The loss of biological activity in all inactive variants is completely paralleled by a decrease of IL-6 receptor binding, as determined by competition binding experiments. One mutant (Leu171) displayed a higher activity on human cells and a higher binding affinity to the receptor and can be considered an IL-6 agonist. It is concluded that the amphipathical alpha-helix structure in the COOH terminus of IL-6 is critical for ligand receptor interaction. Furthermore, the region between residues Ser178 and Arg183 (Ser-Leu-Arg-Ala-X-Arg) is identified as a receptor binding site in the COOH terminus of human IL-6.
We have constructed several hybrid human interleukin-6 (IL-6) variants in which the carboxyl-terminus, which includes a receptor binding site of IL-6 has been replaced with the C-terminus of various proteins homologous to human IL-6. IL-6 hybrids with the C-terminus of human growth hormone and human granulocyte-colony stimulating factor maintain part of the biological activity of human IL-6. Replacing the C-terminus of human IL-6 with the C-terminus of mouse and rat IL-6 resulted in a normal or increased activity on a mouse cell line; however, this gave a low (to 200-fold less) activity on a human cell line compared to wild-type human IL-6. We therefore conclude that the C-terminus of IL-6 plays an important role in the species specificity of IL-6.
In view of reported associations between increased bleeding tendency and systemically decreased alpha 2-antiplasmin in patients with systemic amyloid deposition we studied alpha 2-antiplasmin, fibrinogen, C-reactive protein and blood levels of locally produced endothelial hemostasis factors in the acute and quiescent phase in 16 patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D). None of the factors measured in the quiescent phase of the disease was abnormal. In the acute phase, shortly after a stroke, only factor VIII:Ag was evidently elevated. We concluded that systemic abnormalities in the part of the fibrinolysis system studied are not likely to be responsible for multifocal and recurrent cerebral hemorrhages in HCHWA-D. The role of an elevated factor VIII:Ag level in the acute phase is unclear.
We have examined the functional importance of the two disulfide bonds formed by the four conserved cysteines of human interleukin (IL-6). Using a bacterial expression system, we have synthesized a series of recombinant IL-6 mutants in which the constituent cysteines of the first (Cys45-Cys51), second (Cys74-Cys84), or both disulfide bonds of recombinant human interleukin-6 were replaced by other amino acids. Each mutant was partially purified and tested in four representative bioassays. While mutants lacking Cys45 and Cys51 retained activity similar to nonmutated recombinant IL-6, the activity of mutants lacking Cys74 and Cys84 was significantly reduced, especially in assays involving human cell lines. These results indicate that the first disulfide bond of human interleukin-6 is not required for maintenance of normal biologic activity. However, the fact that mutants lacking Cys45 and Cys51 were more active than corresponding cysteine-free mutants indicates that the disulfide bond formed by these residues contributes to biologic activity in the absence of the second disulfide bond. Competition binding studies with representative mutants indicate that their affinity for the human IL-6 receptor parallels their biologic activities on human cells.