Hepatitis C virus presumably associated bilateral consecutive anterior ischemic optic neuropathy.

PURPOSE: To report a case of bilateral nonarteritic anterior ischemic optic neuropathy (NAION) in a hepatitis C (HCV) infected patient and demonstrate the relationship between HCV and the development of NAION. METHODS: Case report. RESULTS: A 43-year-old woman with chronic HCV infection and long-term euthyroid autoimmune thyroiditis suddenly lost vision in her right eye, and 6 months later in her left eye, due to NAION. Slightly elevated levels of aminotransferases suggested liver infection activity. Anti-HCV antibody was detected; the genotype of the virus was 1b and the viral RNA level was 1.8 x 106 IU/mL. Liver biopsy proved chronic active hepatitis (Ishak score grading: 7, staging: 2). Except for the elevated levels of antithyroid antibodies and a weak antinuclear factor, the detailed laboratory examinations (thrombophilia, cryoglobulin, anticardiolipin antibodies, co-infections) revealed no other abnormalities; a causative relationship between the underlying chronic hepatitis C and bilateral NAION therefore seems probable. The patient was treated with pegylated interferon and ribavirin for 1 year and a sustained viral remission could be achieved. Her vision has neither improved nor deteriorated further. CONCLUSIONS: This appears to be the first reported case of bilateral NAION presumably caused by HCV infection.

A monoclonal antibody directed against human von Willebrand factor induces type 2B-like alterations.

We have previously described a monoclonal antibody (mAb), 1C1E7, against von Willebrand factor (VWF), that increases ristocetin-induced platelet aggregation (RIPA) and induces a preferential binding of the high-molecular-weight multimers of VWF to platelet GPIb. Further investigations using a rotational viscometer at a shear rate of 4000 s(-1) could now demonstrate that shear-induced platelet aggregation (SIPA) is significantly increased with 1C1E7 and that this could be completely inhibited by the anti-GPIb mAb 6D1. In contrast, platelet adhesion to a collagen surface at a shear rate of 2600 s(-1), using a rectangular perfusion chamber, was significantly inhibited in the presence of 1C1E7. When citrated whole blood was incubated with 1C1E7, a spontaneous binding of VWF to the platelet GPIb could be demonstrated by flow cytometric analysis. Parallel to this, a decrease of the highest molecular weight multimers of VWF in the plasma was found. Platelets with bound VWF on their surface were able to form macroaggregates but were no longer able to adhere. These phenomena are very similar to the alterations described in von Willebrand's disease type 2B. The epitope of this mAb could be localized to the N-terminal part of the subunit; therefore a distant conformational change in the A1 domain of VWF is suggested.

Fc-receptor dependent platelet aggregation induced by monoclonal antibodies against platelet glycoprotein Ib or von Willebrand factor.

In this paper we describe two pathways leading to platelet activation by crosslinking glycoprotein (GP) Ibalpha to the platelet Fc-receptor (FcgammaRII). First the monoclonal antibody (MoAb) 9C8, raised against human platelet GPIbalpha, dose-dependently induced platelet aggregation of citrate-anticoagulated platelet-rich plasma, an effect that can be inhibited by several activation inhibitors. The FcgammaRII-inhibitory MoAb IV.3 was able to prevent the aggregatory effects of MoAb 9C8, indicating that crosslinking of the antigen GPIbalpha to the FcgammaII-receptor is necessary for the activating effect. Secondly we observed a synergistic activating effect of two anti-von Willebrand factor (vWF) MoAbs IC1E7 and B724, both known to enhance vWF binding to GPIbalpha in the presence of shear or ristocetin. When these antibodies are added together to PRP, platelet aggregation is induced without further need for an additional modulator. This effect can be blocked by either MoAb IV.3 or an inhibitory anti-GPIb MoAb, indicating that again the platelet activation results from signaling through FcgammaRII crosslinked to vWF bound to GPIbalpha. In addition, both the anti-GPIb MoAb 9C8, or the two anti-vWF MoAbs 1C1E7 and B724 induce genuine platelet activation, as evidenced by the secretion of ATP and protein tyrosine phosphorylation. These findings with both anti-GPIb and anti-vWF MoAbs add further proof to recent reports demonstrating an interaction between the platelet receptors GPIb and FcgammaRII, suggesting a role for the FcgammaII-receptor in GPIb-related signaling.

[Porphyria cutanea tarda and hepatitis C virus]. / Porphyria cutanea tarda és hepatitis C-vírus.

The development of clinically overt porphyria cutanea tarda (PCT) can be attributed to joint effects of genetic predisposition and environmental factors. Regarding exogen factors, studies from several countries published in the last years gave an account of significantly higher frequency of chronic hepatitis C virus (HCV) infection in PCT patients compared to the normal population. At the Department of Dermatology of University of Debrecen the prevalence of positive anti-HCV antibodies has been found in approximately 55% of PCT patients diagnosed from 1990 to 1999, which is comparable to the average prevalence rate seen in Southern-European countries. The majority of male patients were anti-HCV positive and consumed regularly alcohol, whereas every female patient had taken contraceptives. Liver enzymes were only slightly elevated in the majority of the patients and liver biopsy had to be performed only in three patients duo to chronic hepatitis. Our findings emphasise how important the screening of PCT patients for anti-HCV antibody considering that it might be important quo ad vitam for young men.

[Hemostasis in liver diseases]. / Májbetegségek és haemostasis.

Liver plays central role in the synthesis and metabolism of the pro- and anticoagulant enzymes of blood coagulation. Acute or chronic liver failure frequently result in different bleeding phenomena. Thrombocytopenia due to hypersplenism and lack of haemopoietic factors seems to be common, but in spite of thrombocytopenia and more or less platelet malfunction thrombocytopenic bleeding is usually less prominent feature. Bleeding esophageal varices, clotting abnormalities with peritonejugular shunts may pose many difficulties in clinical practice. Transjugular intrahepatic shunt (TIPS) has been a major step forward treating refractory esophageal bleeding or ascites, however to keep the stent patent seems to be still unresolved. Along with the bleeding tendency or symptoms concommittant venous thromboembolic events are may not be considered as rare events in cirrhosis. Special problems are also coupled with ascites, which contains an almost full inventory of coagulation proteins, also with the medical and interventional therapy of Budd-Chiari syndrome, and other veno-occlusive conditions with or without transplantation.

Acquired Bernard-Soulier syndrome: a case with necrotizing vasculitis and thrombosis.

We describe a patient with positive antinuclear antibodies, polyclonal gammopathy and high level of circulating immunocomplexes, resulting in vascular purpura. In addition, the patient had a slightly prolonged bleeding time and an isolated defect of ristocetin-induced platelet aggregation (RIPA) in platelet-rich plasma (PRP). The patient's plasma also inhibited RIPA in normal PRP and in normal platelet suspension. The activity and multimeric structure of plasmatic von Willebrand factor showed no alteration. We could demonstrate an autoantibody against platelet membrane glycoprotein (GP) Ib, using an ELISA-type assay. These data suggest an acquired Bernard-Soulier syndrome. We suggest that the patient had an immunocomplex-mediated leukocytoclastic vasculitis accompanied by production of antinuclear autoantibodies as well as the presence of an autoantibody against GPIb. The titer of the anti-GPIb antibody, however, was too low to induce significant platelet-type bleeding tendency, only laboratory alterations were found. Moreover, in a later stage of her disease, she developed a severe necrotizing vasculitis which was followed by a deep venous thrombosis.

[Thrombophilia, anticoagulant therapy and pregnancy]. / Thrombophilia, antikoaguláns terápia és terhesség.

Thromboembolic complications during pregnancy are the most common causes of maternal death. Here we report on thromboembolic prophylaxis of 60 pregnancies of 32 pregnant women with familial thrombophilia. Long-term Fraxiparine (Sanofi-Chinoin) as thromboprophylaxis was applied in 26 cases throughout pregnancy. UFH (Heparin-Ca inj.) was used in 11 cases, and there were 23 pregnancies without thromboembolic prophylaxis in our patient's case histories. Artificial abortions were not included in this paper. The ratio of successful pregnancies were: with Fraxiparine: 24/26 (92.3%), with UFH (Heparin-Ca): 8/11 (72.7%), without prophylaxis: 4/23 (17.4%). In the patient group treated with Fraxiparine there were no foetopathy, thrombocytopenia or bleeding complication. LMWH is recommended for pregnant women with familial thrombophilia. According to literature data and our own experiences the doses of LMWH in patients with familial thrombophilia, and -antiphospholipid syndrome, and -artificial heart value are suggested.

Increased in vivo platelet activation and reduced intravascular endothelium-derived relaxing factor and nitrate/nitrite production in patients with insulin-dependent diabetes mellitus.

Limited information seems to be available about the role of reduced endothelial production of endotheliumderived relaxing factor (EDRF)-nitrate/nitrite (NO) in the pathogenesis of diabetic angiopathy in insulindependent diabetes. A report of urinary and serum nitrate/nitrite, glucometabolic parameters, endothelial and in vivo platelet activation markers of 22 insulin dependent diabetics (IDDM) patients are given. Urinary and serum nitrate/nitrite concentrations were reduced in IDDM. This was independent of disease duration, presence of angiopathy and the glucometabolic parameters. A significant and inverse correlation of nitrate/nitrite excretion with endothelial markers (von Willebrand factor, soluble thrombomodulin) was documented. Moreover, reduced nitrate/nitrite excretion was strongly associated with elevated plasmatic beta -thromboglobulin levels. EDRF-NO production is reduced in IDDM and this reduction correlates with endothelial damage. Decreased nitrate/nitrite excretion may also influence in vivo platelet function, which results in increased in vivo platelet activation and suggests that the reduced intravascular production of EDRF-NO might play a role in the pathogenesis of angiopathy in IDDM.

The association of reduced endothelium derived relaxing factor-NO production with endothelial damage and increased in vivo platelet activation in patients with diabetes mellitus.

The role of reduced endothelial production of EDRF-NO in the pathogenesis of diabetic angiopathy has received much attention, however, most of the rather conflicting data were gained from animal experiments. Limited human experience seems to be available in insulin dependent diabetes, calling attention to decreased EDRF-NO production. Hereby the clinical, as well as laboratory investigation (urinary and serum nitrate/nitrite, lipid peroxidation, glucometabolic parameters, endothelial and in vivo platelet activation markers, etc.) of 35 non-insulin dependent (NIDDM) and 15 insulin dependent diabetics (IDDM) patients are given. Urinary and serum nitrate/nitrite concentrations were proven to be reduced in both patients groups. This change was independent of diabetes duration, presence of macroangiopathy, coronary heart disease and the glucometabolic parameters, however, correlation was registered with lipid peroxidation (total antioxidant status). An inverse correlation of nitrate/nitrite excretion with endothelial markers (von Willebrand factor, soluble thrombomodulin) was documented in NIDDM, this correlation was much stronger in IDDM. Moreover, in IDDM patients reduced nitrate/nitrite excretion was strongly associated with elevated plasmatic beta-thromboglobulin levels. The data presented here support to the hypothesis, that EDRF-NO production is reduced in diabetes and this reduction seems to correlate with endothelial damage. In IDDM the decreased nitrate/nitrite excretion may also lead to increased in vivo platelet activation, which suggests that the reduced amount of EDRF-NO might play a role in the pathogenesis of angiopathy in IDDM.

Studies of the platelet filter test (shear dependent platelet aggregation) in patients with uncommon haemorrhagic disorders.

Platelets of anticoagulated whole blood forced at 40 mmHg through a fine filter are activated, aggregated and retained, so block the filter (platelet filter test, O'Brien JR, Salmon GP. Blood 1987; 1354-1361). Our clinical experiences with this simple and quick haemostasis test are summarized. Patients were investigated with different types of vWD (type-1 = 35, type-2A = 7, type-2B = 7, type-3 = 1), Glanzmann's thrombasthenia, congenital deficiency of cyclo-oxygenase, acquired Bernard-Soulier syndrome, FXII-, FXIII-deficiency and a control group. The cumulative drop count and the platelet retention were carefully measured during two phases of the filter test. Platelet count, bleeding time, vWF:Ag and vWF:Rcof activity were measured along with the platelet filter test. The filter was not blocked and the platelet retention was abnormally low in all patients with thrombasthenia, type-2a, type-2B, type-3 vWD. Treatment with 1-desamino-8-D-arginine-vasopressin (DDAVP) caused enhanced platelet retention in 16 patients with type-1 vWD. The test is simple, quick and cheap, has good reproducibility, and may be useful in clinical haemostasis laboratories for examination of high shear induced platelet functions.

[Low-molecular-weight heparin in the prevention of thromboembolism in pregnant thrombophilic patients]. / Thromboembolia prophylaxis kis molekulatömegü heparin alkalmazásával thrombophiliás terhesekben.

Prophylaxis of thromboembolism with low molecular weight heparin (LMWH) may offer some advantages over unfractionated heparin during pregnancy. Controlled studies with LMWH for thromboprophylaxis in pregnancy are failing, although according to some recent studies LMWH did not cross the placental barrier. LMWH as thromboprophylactic agent was used in three young pregnant women with familial thrombophilia (two with PC one with AT-III deficiency). According to the bodyweight of patients the applied doses of LMWH were 5,000-10,000 ICU once daily. Laboratory control (determination of anti-FXa activity in plasma samples) was made monthly. The three pregnancies were uneventful, thromboembolic or haemorrhagic complications did not develop. Newborns were healthy, with no coincide of disturbances of haemostasis. The LMWH-demand is certainly increased at the late period of pregnancy. LMWH as thromboprophylaxis is recommended for pregnants with familial thrombophilia. The necessary dose of Fraxiparine may be 70 ICU/kg/day in the first and 100 ICU/kg/day in the second half of pregnancy.

[Fibrinolysis in chronic liver diseases studied by in vitro blood coagulation tests]. / A fibrinolysis vizsgálata krónikus májbetegségekben in vitro alvadékoldási próba segítségével.

A simple and easily reproducible in vitro clot lysis test less frequently indicated increased rate of fibrinolysis in chronic hepatic disease than expected. In hepatic cirrhosis clot lysis slows down as the condition deteriorates or as the plasma concentration of von Willebrand factor increases, thus the test may have certain prognostic value. The present observations suggest that the occasional acceleration of fibrinolysis in cirrhosis may be related to either increased production or decreased clearance of tPA, and is not due to impaired fibrinolysis inhibitor system.

An echistatin-like Arg-Gly-Asp (RGD)-containing sequence in the heavy chain CDR3 of a murine monoclonal antibody that inhibits human platelet glycoprotein IIb/IIIa function.

We describe the production and biochemical characterization of the first GPIIb/IIIa-inhibiting monoclonal antibody that contains an RGD sequence in the CDR3 region of the heavy chain. Monoclonal antibodies obtained by immunizing mice with human platelets were screened using consecutive ELISAs based on human platelets and immuno-affinity-purified glycoprotein (GP) IIb/IIIa coated on microtitre plates. Out of 30 monoclonal antibodies reacting with GPIIb/IIIa, one, MA-16N7C2, potently inhibited platelet aggregation induced by ADP, thrombin, arachidonic acid, collagen, U46619, adrenaline and platelet-activating factor, whereas ristocetin-induced aggregation was unaffected. MA-16N7C2 (IgG2a) bound approximately 4 times faster to activated than to resting platelets, with a Kdcalc of 6.6nM and of 17.5nM, respectively. Equilibrium binding studies to non-activated platelets showed a Kd of 18.2nM with 41 x 10(3) binding sites per platelet. The antibody recognized GPIIb/IIIa only as a Ca(2+)-dependent complex. MA-16N7C2 blocked fibrinogen and von Willebrand factor binding to GPIIb/IIIa in a competitive manner with a Ki of 8.5nM and 13.2nM, respectively. Sequence analysis revealed a RGD-containing sequence with homology to disintegrins, in the CDR3 region of the heavy chain. That this RGD-containing sequence could be involved in the interaction of the antibody to GPIIb/IIIa was finally indicated by showing that the binding is completely and competitively inhibited by echistatin.

Megakaryocyte markers in myeloproliferative disorders.

Identification of megakaryocyte precursors with immunohistochemical methods in bone marrow trephine biopsy specimens (embedded in a plastic resin, Immuno-Bed) was performed from patients with blastic phase of chronic granulocytic leukaemia (five cases), from chronic megakaryocytic-granulocytic myelosis (four cases) and from acute megakaryoblastic leukaemia (11 cases). In megakaryoblasts of bone marrow biopsies immunohistochemical reactions using the ABC method and monoclonal antibodies against von Willebrand antigen and GpIIb/IIIa (CD41) were visible in various percentages depending on the maturation's degree of megakaryocyte precursors. The number of circulating blast cells determined by flow cytophotometry was nearly similar to those of observed in biopsies. The greatest bone marrow reticulin content could be detected in acute megakaryoblastic leukaemia cases. Despite the different clinicopathological entities, the presence of the same phenotype (megakaryoblasts) was associated with a short survival in these haematological malignancies (in CGL MKB phase 4.0, in CMGM MKB phase 4.2, and in AML M7 5.8 months, respectively).

A monoclonal antibody recognizes a von Willebrand factor domain within the amino-terminal portion of the subunit that modulates the function of the glycoprotein IB- and IIB/IIIA-binding domains.

We developed a monoclonal antibody, 1C1E7, against vWf that increases ristocetin-induced platelet aggregation in a dose-dependent manner and lowers the threshold concentration of ristocetin needed to obtain a full aggregatory response. The platelet aggregatory effect of asialo vWf (ASvWf) also is enhanced by 1C1E7, in the presence or absence of glycoprotein (GP) IIb/IIIa receptor antagonism. In the presence of ristocetin, both intact 1C1E7 and its Fab fragments enhance specific binding of 125I-vWf to platelets. With 1C1E7, the intermediate and higher molecular weight multimers of vWf are preferentially bound to both GP Ib and GP IIb/IIIa. Thrombin-induced 125I-vWf binding to GP IIb/IIIa also is increased by 1C1E7. Maximal binding of 1C1E7 to vWf corresponds to 0.97 mol/mol vWf monomer with a Kd of 4.7 x 10(-10) M. 1C1E7 reacts with a 34/36-kD tryptic fragment (III-T4) and a 34-kD plasmic fragment (P34), which localizes the epitope between amino acid residues 1 and 272; this was confirmed by NH2-terminal amino acid sequencing. Finally, platelet aggregation by ASvWf was associated with a sharp rise in intracellular Ca2+ only in the presence of 1C1E7. An antibody-mediated conformational change of vWf may result in an improved presentation of the GP Ib- and GP IIb/IIIa-binding domains of mainly the larger multimers; the increased density of vWf on the platelet surface leads to platelet activation. The antibody may thus recognize a domain of relevance for vWf physiology.

Endothelium releases more von Willebrand factor and tissue-type plasminogen activator upon venous occlusion in patients with liver cirrhosis than in normals.

Venous occlusion was used in 8 patients with liver cirrhosis and in 10 normals to investigate the pathomechanism of long-term elevation of plasma von Willebrand factor antigen (vWFAg) in liver cirrhosis. The following parameters were determined at baseline, and immediately, 60 min and 24 h after 10 min venous occlusion: vWFAg, ristocetin cofactor (RiCoF), in vitro platelet retention (Adeplat T), and tissue-type plasminogen activator (t-PA). Every baseline value in the liver cirrhosis group was significantly higher than in the controls. In both groups the 10-min values were significantly higher than their corresponding baseline results. Hence, comparing the two groups, in liver cirrhosis a significantly higher release of vWFAg and t-PA could be observed. These findings suggest on the one hand that the increased release contributes substantially to the sustained elevation of plasma vWF level in liver cirrhosis. On the other hand, the results indicate that not only the vascular surface of the diseased liver but most probably the total endothelium plays an important role in this phenomenon.

Measurement of von Willebrand factor antigen in plasma and platelets with an enzyme-linked immunosorbent assay based on two murine monoclonal antibodies.

Two murine monoclonal antibodies, raised against von Willebrand factor (vWF), were used to construct an enzyme-linked immunosorbent assay (ELISA), for quantitation of vWF antigen (vWFAg) in human plasma and platelets. This assay had a lower limit of sensitivity of 0.0001 IU/ml in buffer, and thus is one to two orders of magnitude more sensitive than other ELISA assays which have been reported. The intraassay, interassay and interdilution coefficients of variation were 4.1, 10.4 and 9.9%, respectively. In normal plasma (n = 20), the vWFAg level was 0.83 (range: 0.42-1.25) IU/ml. In normal washed platelets (n = 10), 0.35 (0.25-0.49) IU/10(9) platelets was found. In plasma obtained from various patient groups the following vWFAg levels (geometric mean and range) were observed: von Willebrand's disease (n = 19): 0.18 (0.02-0.77) IU/ml; patients with liver cirrhosis (n = 20): 3.73 (1.68-9.20) IU/ml; patients with pregnancy-induced hypertension (n = 20): 4.14 (2.28-7.44) IU/ml and patients with malignant disease (n = 10), 2.54 (1.51-5.60) IU/ml. A linear correlation was found between vWFAg levels measured with a polyclonal antibody based Laurell electroimmunoassay (r = 0.92, n = 58) or with a polyclonal antibody based ELISA (r = 0.94, n = 64). The present assay is based on stable and reproducible reagents and allows the specific measurement of vWFAg in plasma and in platelets. This assay may constitute a useful tool for the further investigation of clinical conditions associated with changes in vWFAg levels. In addition, its high sensitivity may facilitate a more detailed study of platelet vWFAg in normal and in pathological conditions.