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Biomedical subjects

F Violi

Publications and source records attributed to F Violi.

At least 109 records · Page 6Linked to original sources
PubMed1995

Increased rate of thrombin generation in hepatitis C virus cirrhotic patients. Relationship to venous thrombosis.

BACKGROUND: Venous thrombosis may complicate the clinical course of liver cirrhosis (LC), but the pathogenesis is still uncertain. We have previously demonstrated that antiphospholipid (aPL) antibodies were a risk factor for thrombosis. In the same study it was also evident that there was a higher prevalence of hepatitis C virus (HCV) infection in patients with thrombosis, and an association between anti-HCV positivity and aPL. METHODS: In a case-control study, 18 consecutive patients with LC, who had suffered from splanchnic venous thrombosis (n = 12), or thrombophlebitis (n = 6), were matched for age, sex, and degree of liver failure with 36 LC patients without thrombosis. RESULTS: In comparison to patients without thrombosis, patients with thrombosis had higher prevalence of HCV infection (p = 0.0027), positivity for aPL antibodies (p = 0.0003), and higher values of fragment F1+2, a marker of thrombin generation (p = 0.0083). While F1+2 values were similar in aPL (+) and aPL (-) patients, HCV patients had significantly higher values of F1+2 than patients with hepatitis B virus (HBV) infection and/or alcoholism (2.6 +/- 0.94 vs 1.5 +/- 0.66, p = 0.0001). CONCLUSIONS: These data suggest that in LC, HCV infection may contribute to clotting system activation, thus predisposing patients to venous thrombosis.

Adult↗
PubMed1994

Role of hydroxyl radicals in the activation of human platelets.

Platelets primed by exposure to subthreshold concentrations of arachidonic acid or collagen are known to be activated by nanomolar levels of hydrogen peroxide. We here demonstrate that this effect is mediated by hydroxyl radicals (OHzero) formed in an extracellular Fenton-like reaction. H2O2-induced platelet aggregation, serotonin release and thromboxane A2 productions were inhibited by OHzero scavengers and by the iron chelator desferrioxamine; hydroxyl radicals were detected directly by ESR measurements of the spin-trapped OHzero adduct. The role of OHzero was confirmed in experiments with exogenously added iron; free or EDTA-bound ferrous iron activated platelets in a process blocked by deoxyribose, mannitol or catalase, whereas ferric iron was without effect unless reductants were included. The activation by OHzero depended on concomitant release of arachidonic acid and was blocked by the phospholipase A2 inhibitors mepacrine and aristolochic acid, and by the Na+/K+ antiporter inhibitor ethylisopropylamiloride. In contrast, neomycin and staurosporin were without effects, indicating that phospholipase C and protein kinase C were not involved in the initial phase of activation. Neither radical formation nor arachidonic acid release was blocked by aspirin. In whole blood aggregation of platelets could be induced by H2O2 generated upon specific stimulation of neutrophils by N-formyl-methionyl-leucyl-phenylalanine; platelet activation and radical formation were blocked by the NADPH oxidase inhibitor diphenyliodonium as well as by catalase and mannitol. These results suggest that reactive oxygen species act as 'second messengers' during the initial phase of the platelet activation process.

Arachidonic Acid↗
PubMed1994

Relationship between lipoprotein(a) levels in serum and some indices of protein synthesis in liver cirrhosis.

Recent research has demonstrated that the major site of apolipoprotein(a) synthesis, the characteristic protein of lipoprotein(a) (Lp(a)), is the liver and that patients affected by liver cirrhosis have low serum concentrations of Lp(a). Nevertheless, it is still not clear whether Lp(a) behaviour in these patients is related to reduced hepatic protein synthesis, or to decreased serum lipid levels or to both these conditions. In order to investigate further the behaviour of Lp(a) and, in particular, its relationship with some indices of blood lipids and coagulation, 30 patients affected by liver cirrhosis have been studied. Significantly low serum values of Lp(a) were observed in patients with more severe hepatic injury included in classes B and C according to the Child-Pugh score. Lipoprotein(a) was directly correlated with prothrombin plasma activity and with apolipoprotein B-100 and albumin concentrations in serum. This study confirms low serum levels of Lp(a) in cirrhotic patients and suggests that its decrease could be partly due to impaired liver protein synthesis.

Apolipoprotein B-100↗
PubMed1994

Bleeding time in patients with cirrhosis: relation with degree of liver failure and clotting abnormalities. C.A.L.C. Group. Coagulation Abnormalities in Cirrhosis Study Group.

Patients with cirrhosis suffer from a complex haemostatic disturbance, due to abnormalities in clotting and fibrinolytic system activation and in primary haemostasis. The latter is indicated by a prolongation of bleeding time, which is a reliable indicator of platelet function in vivo. To further assess the relationship between bleeding time, degree of liver failure and clotting abnormalities in patients with cirrhosis, bleeding time was investigated in a prospective study of 70 consecutive patients with cirrhosis diagnosed by liver-needle biopsy, of whom 19 belonged to Child-Pugh class A, 29 to B and 22 to C. Among patients with cirrhosis, 40% had an abnormal bleeding time (> 10 min), and 42% had a platelet count < 100,000/microliters. Patients with severe liver failure (class C) had a lower platelet count and a more prolonged bleeding time than patients in classes A and B. Bleeding time was significantly inversely correlated to platelet count, fibrinogen, prothrombin activity and packed cell volume, and directly correlated to serum bilirubin and D-dimer. However, in class C patients, only a significant inverse correlation between bleeding time and fibrinogen was observed. These findings indicate that in cirrhosis worsening of platelet function is closely related to the degree of liver failure. The inverse correlation between bleeding time and fibrinogen indicates that a low value of this clotting parameter may account in part for platelet dysfunction.

Bleeding Time↗
PubMed1994

Prevalence of lupus anticoagulant in patients with cirrhosis: relationship with beta-2-glycoprotein I plasma levels.

We have previously demonstrated that patients with cirrhosis may be positive for lupus anticoagulant and anticardiolipin antibodies. The prevalence and clinical value of antiphospholipid antibodies in cirrhosis have never been described. Besides, it has not yet been determined if serum levels of beta-2-glycoprotein I, which is synthesized by the liver and mediates the interaction between cardiolipin and anticardiolipin antibodies affects lupus anticoagulant detectability in cirrhosis. We evaluated the prevalence of lupus anticoagulant in 63 patients with cirrhosis and related it to beta-2-glycoprotein I serum levels. We also analyzed whether lupus anticoagulant and anticardiolipin antibodies were associated with previous thrombotic complications. Eleven patients (18%) were lupus anticoagulant positive; 14 (22%) had high values of anticardiolipin antibodies. Fourteen patients had a previous history of splanchnic venous thrombosis (n = 9) or thrombophlebitis (n = 5). A significant association between lupus anticoagulant (p = 0.0001), anticardiolipin antibodies (p = 0.0001) and venous thrombosis was found. Patients with severe liver failure had significantly lower beta-2-glycoprotein I levels than those with moderate (p < 0.01) or low (p < 0.001) hepatic insufficiency. Among 14 anticardiolipin antibodies positive patients, six with severe liver failure were lupus anticoagulant negative and had beta-2-glycoprotein I values below 100 micrograms/ml. In four of these, basal values of dilute activated partial thromboplastin time were not modified by the addition of 50 micrograms/ml of exogenous beta-2-glycoprotein I. This study shows that antiphospholipid antibodies are relatively frequent in cirrhosis and that beta-2-glycoprotein I levels are not so low as to affect lupus anticoagulant detectability.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Rationale for the use of antiplatelet drugs in patients with peripheral vascular disease.

Peripheral vascular disease (PVD) is complicated by progression of atherosclerotic disease of lower limbs and by cardiovascular events occurring in cardiac and cerebral area. Antiplatelet treatment seems to be able to retard the atherosclerotic progression of peripheral vessel. This was demonstrated by angiographic studies and by a clinical trial showing that aspirin reduced the need of surgical intervention in PVD patients. Three large clinical trials have been planned to assess the effect of antiplatelet treatment on cardiovascular complications. By intention-to-treat analysis, no study showed a beneficial effect for this treatment. Conversely, by on-treatment analysis, antiplatelet treatment showed a significant reduction of global cardiovascular events. Until now, no study has had the power to assess the effect of antiplatelet treatment on major cardiovascular events. The evaluation of patients at high risk of major events by antiplatelet treatment should be an important issue of future clinical trials.

Arteriosclerosis↗
PubMed1994

Hypercoagulability state in patients with chronic obstructive pulmonary disease. Chronic Obstructive Bronchitis and Haemostasis Group.

Since there is some clinical evidence that the clinical course of patients with chronic obstructive pulmonary disease (COPD) may be complicated by thrombosis in the pulmonary vessels, we studied whether a hypercoagulability state (HS) does occur in COPD. Plasma levels of prothrombin F1 + 2 fragment, a marker of thrombin generation, D-dimer, a marker of in vivo thrombin and plasmin activation, and fibrinogen were measured in 37 COPD patients and in 30 controls matched for sex and age. COPD patients had significantly higher values of F1 + 2 (p = 0.0001) and fibrinogen (p = 0.0005) than healthy subjects. The difference persisted after excluding smoking patients. F1 + 2 was not correlated with PaO2 (r = 0.02, p > 0.05) and PaCO2 (p = 0.12, p > 0.05). In six patients with stable COPD and F1 + 2 greater than 1.65 nM (mean + 2 SD of controls) subcutaneous calcium-heparin therapy (5000 IU t.i.d. for 15 days) significantly reduced F1 + 2 (p = 0.03) and PaCO2 (p = 0.01). This study shows that COPD patients have an ongoing prothrombotic state which could potentially account for thrombosis occurring in pulmonary vessels. The effect of calcium-heparin treatment on clotting system activation and blood gas may suggest this treatment as potential candidate for prospective study in COPD patients.

Adult↗
PubMed1993

The hyperfibrinolytic state of liver cirrhosis: possible pathogenetic role of ascites.

We evaluated coagulation and fibrinolytic parameters in both plasma and ascitic fluid of 39 patients with ascites secondary to liver cirrhosis and in 14 cirrhotic patients without ascites, in order to verify if the peritoneal compartment could be involved in the pathogenesis of the hyperfibrinolytic state of the disease. An activation of fibrinolysis, as suggested by increased levels of FDP, D-dimer and tissue plasminogen activator (t-PA) was demonstrated in both ascitic fluid and to a lesser extent in plasma. A positive correlation was also observed between plasma and ascitic fluid plasminogen, anti-plasmin and fibrinogen, while a negative correlation was found between plasma and ascitic fluid plasminogen activator inhibitor-1 (PAI-1). Moreover, plasma PAI-1 was significantly lower in patients with ascites than in those without ascites and among ascitic patients in those who had bleeding into soft tissues when compared to those who did not present haemorrhagic events. Finally, a significant association was also shown between positivity for plasma D-dimer (> 200 ng/ml) and the presence of ascites. Taken together, our data suggest an exchange of some coagulation and fibrinolytic proteins between plasma and ascitic fluid and point out the key role of PAI-1 in regulating plasma fibrinolytic potential and in bleeding complications in cirrhotic patients.

Adult↗
PubMed1993

Polymorphonuclear leukocyte-derived O2-reactive species activate primed platelets in human whole blood.

The activation of human platelets by polymorphonuclear leukocytes (PMN) was investigated in human whole blood challenged with "priming" concentrations of arachidonic acid or collagen in the presence or absence of N-formyl-Met-Leu-Phe (FMLP), a selective activator of PMN. With the use of arachidonic acid or collagen alone at priming concentrations or FMLP alone, no platelet response was observed. In contrast, FMLP in combination with arachidonic acid or collagen caused irreversible platelet aggregation with thromboxane A2 production. Platelet response to FMLP-activated PMN was enhanced by superoxide dismutase and blocked by catalase or the NADPH oxidase inhibitor diphenyliodonium, suggesting a role for the O2-.-H2O2 system in this cellular interaction. This was corroborated by experiments with exogenously added H2O2, which mimicked FMLP effects in the activation of primed platelets in whole blood. The present investigation indicates that platelets primed with minute amounts of arachidonic acid or collagen can be activated, in human whole blood, by oxygen-reactive species released by PMN.

Arachidonic Acid↗
PubMed1993

Effect of picotamide on the clinical progression of peripheral vascular disease. A double-blind placebo-controlled study. The ADEP Group.

BACKGROUND: Patients with peripheral vascular disease (PVD) undergo a clinical course that can be complicated by cardiovascular events occurring in several areas of the circulation. METHODS AND RESULTS: In the present study we investigated the ability of picotamide, a substance that inhibits platelet thromboxane A2 (TxA2) synthase and antagonizes TxA2 receptors, to reduce cardiovascular complications in PVD patients. The study was double blind and placebo controlled. After a 1-month run-in period, 2,304 patients were randomly allocated to either placebo or picotamide (300 mg t.i.d.) and followed for 18 months. Major and minor events were analyzed. Results of an "intention-to-treat analysis" were that patients on picotamide suffered 45 major events (3.9%) and 77 minor events (6.7%), whereas those taking placebo suffered 52 major (4.5%) and 99 minor events (8.6%). There was borderline statistical difference between the two groups with respect to the sum of the major and minor events (risk reduction, 18.9%; p = 0.056, log-rank test). Results of an "on-treatment" analysis were that patients on picotamide suffered 40 major (3.8%) and 66 minor events (6.3%), whereas those taking placebo suffered 45 major (4.2%) and 95 minor events (8.9%). The sum of both major and minor events was 106 (10.1%) in the picotamide group and 140 (13.1%) in the placebo group. This difference was significant (risk reduction, 23%; p = 0.029, log-rank test). CONCLUSIONS: The results of this study indicate that picotamide reduces cardiovascular complications in PVD patients. The apparently low effect of this drug in reducing major events suggests that further studies be made with picotamide in PVD patients who are at high risk of cardiovascular complications so as to further assess its clinical efficacy.

Aged↗
PubMed1993

Lupus anticoagulant and the fibrinolytic system in young patients with stroke.

BACKGROUND AND PURPOSE: Our purpose was to assess the presence of lupus anticoagulant and fibrinolytic system abnormalities in young patients with stroke. METHODS: We studied 33 consecutive ischemic patients aged < 50 years. Lupus anticoagulant was screened by four different coagulation tests, and the fibrinolytic system was studied by analyzing tissue plasminogen activator antigen and plasminogen activator inhibitor activity. RESULTS: Six patients (18%), two of whom were affected by systemic lupus erythematosus, had lupus anticoagulant. Plasminogen activator inhibitor activity was significantly higher in those positive for lupus anticoagulant than in those negative for lupus anticoagulant and control subjects (p < 0.001). CONCLUSIONS: In young patients with stroke, lupus anticoagulant is associated with an imbalance of the fibrinolytic system as a result of higher levels of plasminogen activator inhibitor.

Adult↗
PubMed1993

Hyperfibrinolysis resulting from clotting activation in patients with different degrees of cirrhosis. The CALC Group. Coagulation Abnormalities in Liver Cirrhosis.

This study explored the relationship between clotting activation and tissue plasminogen activator and its inhibitor in cirrhotic patients with different degrees of liver failure. Sixty-seven patients (40 men, 27 women; age = 31-77 yr) with cirrhosis diagnosed by liver biopsy were divided into three subgroups (A, B and C) on the basis of Child-Pugh classification. Tissue plasminogen activator antigen and activity, plasminogen activator inhibitor antigen and activity, fibrin/fibrinogen degradation products, and D-dimer were measured in each patient. Forty-two patients with normal levels of fibrin/fibrinogen degradation products and D-dimer showed significant progressive decreases of plasminogen activator inhibitor antigen levels (p < 0.01) and activity (p < 0.0001) from class A to class C. This decrease was significantly related to prothrombin time (p < 0.003). Tissue plasminogen activator values were not different in the three Child classes. Twenty-five patients (7 class B and 18 class C) with high circulating values of fibrin/fibrinogen degradation products and D-dimer had higher values of tissue plasminogen activator antigen (20.0 +/- 10.1 ng/ml vs. 5.9 +/- 3.0 ng/ml; p < 0.0001) and activity (6.9 +/- 2.2 U/ml vs. 2.1 +/- 1.3 U/ml; p < 0.0001) and lower values of plasminogen activator inhibitor antigen (6.9 +/- 4.1 ng/ml vs. 14.8 +/- 5.6 ng/ml; p < 0.0001) and activity (4.1 +/- 2.8 U/ml vs. 9.8 +/- 3.7 U/ml; p < 0.0001) than did patients with normal values of fibrin/fibrinogen degradation products and D-dimer.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Mechanism of reaction of a suggested superoxide-dismutase mimic, Fe(II)-N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine.

The interaction of a recently developed intracellular superoxide dismutase analogue, Fe(II)-N,N,N',N'-tetrakis(2- pyridylmethyl)ethylenediamine (Fe(II)-TPEN), with reactive oxygen species was investigated under in vitro conditions. The complex catalyzed the dismutation of enzyme- or radiolysis-generated superoxide with the production of H2O2; under steady-state conditions the equilibrium was strongly shifted toward Fe(III)-TPEN. Fe(II)-TPEN reacted with H2O2 to generate hydroxyl radicals in a Fenton reaction. The oxidized Fe(III)-TPEN was readily reduced by ascorbate or glutathione. Given the capacity to produce hydroxyl radicals and the reaction with cellular reductants it seems unlikely that Fe-TPEN may find widespread use as an intracellular superoxide dismutase substitute.

Ascorbic Acid↗