Hyperhomocysteinemia in patients with pulmonary embolism is associated with impaired plasma fibrinolytic capacity.

Hyperhomocysteinemia (HHcy) affects haemostasis and shifts its balance in favour of thrombosis. In vitro and in vivo studies suggested that HHcy may impair fibrinolysis either by influencing the plasma levels of fibrinolytic factors or by altering the fibrinogen structure. We investigated the influence of mild HHcy levels on plasma fibrinolytic potential by using clot lysis time (CLT) and fibrin susceptibility to plasmin-induced lysis in 94 patients with previous pulmonary embolism and no pulmonary hypertension. CLT was measured as lysis time of tissue factor induced clots exposed to exogenous tissue plasminogen activator (t-PA). The rate of in vitro plasmin-mediated cleavage of fibrin ß-chain was assessed over a 6-h period on fibrin clots, which were obtained by exposition to thrombin of purified fibrinogen. Homocysteine plasma levels were measured by Abbott Imx immunoassay and we considered as altered the values above 15 µmol/L according to the literature. In 68 patients homocysteine levels were below 15 µmol/L (NHcy) and in 26 they were above (HHcy). Significant differences were observed between the two groups regarding plasma fibrinolytic potential (p = 0.016), TAFIact (expressed as clot lysis ratio) (p = 0.02), t-PA (0.008) and PLG (0.037), but not for the other assessed components. The HHcy-patients had a threefold higher risk to have an impaired fibrinolysis. Instead, a multivariate logistic regression analysis adjusted for significances of univariate showed that HHcy (OR 5.2 95% CI 1.7-15.9; p = 0.003) and BMI (OR 5.0 95% CI 1.6-15.9; p = 0.006) resulted independently associated with impaired fibrinolytic activity. HHcy affects TAFI-mediated hypofibrinolysis but not fibrin(ogen) structure or function as documented by fibrin degradation analysis.

Atherosclerotic and thrombophilic risk factors in patients with ischemic central retinal vein occlusion.

PURPOSE: To investigate atherosclerotic and thrombophilic risk factors in patients affected by acute ischemic and nonischemic central retinal vein occlusions (CRVOs). METHODS: One hundred and three patients with acute unilateral CRVO (41 ischemic and 62 nonischemic) were studied. The frequency of traditional cardiovascular risk factors was assessed, and the plasma levels of a variety of thrombophilic markers were measured. Univariate logistic regression was performed to determine risk factors for ischemic CRVO. RESULTS: Arterial hypertension, hypercholesterolemia, postmethionine hyperhomocysteinemia (HHcy), elevated factor VIII, and reduced folic acid and B6 plasma levels were more frequent in patients with ischemic CRVO than in those with nonischemic CRVO (P = 0.030, P = 0.025, P = 0.011, P < 0.001, P < 0.001, and P = 0.044, respectively). Risk factors for ischemic CRVO were arterial hypertension (odds ratio [OR], 3.22; 95% confidence interval [CI], 1.13-9.21; P = 0.037), hypercholesterolemia (OR, 3.03; 95% CI, 1.06-8.65; P = 0.042), reduced folic acid levels (OR, 6.77; 95% CI, 1.59-28.79; P = 0.011), and elevated FVIII levels (OR, 6.17; 95% CI, 2.56-14.82; P < 0.001). Postmethionine HHcy was associated with low folic acid levels (r = -0.413; P = 0.007; OR, 9.33; 95% CI, 2.06-42.18; P = 0.005). CONCLUSION: The results of the present study suggest that some atherosclerotic and thrombophilic risk factors may increase the risk of having an ischemic form of CRVO.

Evaluation of traditional and emerging cardiovascular risk factors in patients with non-arteritic anterior ischemic optic neuropathy: a case-control study.

BACKGROUND: Non-arteritic anterior ischemic optic neuropathy (NAION) is a multifactorial disease that is caused by an infarction of the vessels that supply the optic nerve head. This study aims at evaluating the role of traditional and emerging cardiovascular risk factors on the development of NAION. METHODS: A total of 85 newly diagnosed NAION patients and 107 age- and gender-matched healthy controls were studied. All participants underwent blood testing for homocysteine and lipoprotein(a). Plasma levels of vitamin B6 and B12, and folic acid were also determined. Plasma values of all these parameters were evaluated as continuous variables, by a logarithmic transformation. In addition, traditional cardiovascular risk factors were considered. RESULTS: With univariate analysis, higher values of homocysteine and Lp(a) (OR 4.24, 95% CI 2.01-8.94, p < 0.0001; OR 1.32, 95% CI 1.04-1.67, p = 0.03, respectively) and lower values of vitamin B6 (OR 0.44, 95% CI 0.25-0.76, p = 0.003) were significantly associated with NAION. At multivariate analysis, adjusted for age, gender, smoking habit, hypertension, dyslipidemia, diabetes, sleep apnea, and thrombophilic risk factors, the higher homocysteine and Lp(a) values (OR 5.74, 95% CI 2.41-13.67, p = 0.0001; OR 1.27, 95% CI 1.01-1.63, p = 0.04) and lower vitamin B6 values (OR 0.42, 95% CI 0.23-0.77, p = 0.005) maintained their significant relationship with NAION. CONCLUSIONS: This study demonstrated that elevated plasma homocysteine and lipoprotein(a) levels, as well as low vitamin B6 levels, may increase the risk of developing NAION. A screening for these thrombophilic markers could be useful in subjects experiencing NAION.

Thrombotic events in high risk patients are predicted by evaluating different pathways of platelet function.

A higher rate of clinical events in poor clopidogrel and/or aspirin responders was documented by using different methods to measure platelet function, but no conclusive data about the appropriate methodology to explore platelet reactivity are available. A total of 746 patients included in the cohort of the RECLOSE trial who had successful drug-eluting stent implantation were assessed for post-treatment residual platelet reactivity (RPR) in platelet-rich plasma by 10 microM adenosine 5'-diphosphate (ADP), 1 mM arachidonic acid (AA) and 2 microg/ml collagen-induced platelet aggregation and in whole blood by the PFA-100 system. At six-month follow-up, RPR by two stimuli (ADP and AA or ADP and collagen) and by three stimuli (ADP, AA and collagen) is significantly associated with higher percentage of primary (definite or probable stent thrombosis) and secondary (cardiac mortality and stent thrombosis) end-points than RPR by ADP, AA, collagen and PFA-100 system. According to the primary and secondary end points, the specificity values for RPR identified by two (ADP and AA:94%; ADP and collagen:97%) and three stimuli were higher with respect to RPR by ADP (88%), or RPR by AA (83%) or RPR by collagen (90%). The positive likelihood ratio values of RPR by three stimuli (9.55) or of RPR by ADP and collagen (8.08) were higher than those of RPR by ADP (2.59), by AA (2.05), by collagen (4.73), or by PFA-100 (2.63). This prospective study documents that the evaluation of platelet reactivity addressed to identify patients at risk of thrombotic events on dual antiplatelet treatment has to be carried out by methods able to explore different pathways.

Fine specificity of antibodies against phospholipids and beta-2-glycoprotein I in monoclonal gammopathy associated neuropathies.

Phospholipids are abundantly represented within the nervous system. Aim of our study was to evaluate the presence and fine specificity of anti phospholipid antibodies (aPLAb) among patients with monoclonal gammopathy associated neuropathy. Thirty nine percent of these patients had high titers of aPLAb, mostly associated with low levels of anti beta2 glycoprotein I, which suggests different antibody specificity compared to patients with anti phospholipid syndrome. Further 6/48 patients with dysimmune neuropathy without monoclonal gammopathy had positive aPLAb titers. APLAb strongly cross-reacted with sulfatide. These findings suggest an adjuntive role of aPLAb on nerve damage and may help to better understand the nerve binding properties of anti-sulfatide antibodies.

Low protein Z levels in patients with peripheral arterial disease.

Conflicting findings regarding the association between protein Z and atherosclerotic disease have been reported. The aim of this case-control study was to evaluate the role of protein Z in a peripheral localization of atherosclerosis. We studied protein Z levels in 120 patients (102 male, 18 female; median age: 75 years) admitted to the Unit of Vascular Surgery of the University of Florence with a clinical manifestation of peripheral arterial disease (PAD), and in 360 healthy subjects selected to be comparable to the patients group in terms of age and gender. Protein Z levels were found to be significantly (p<0.05) lower in PAD patients [1,594 (89-3,635) ng/ml] compared to the healthy control group [1,728 (300-3,736) ng/ml]. A logistic regression analysis showed, at univariate analysis, a significantly increased risk of PAD in patients with low levels of protein Z (<5th percentile of our control group: <601 ng/ml) (OR: 5.72, 95%CI 3.07-10.66; p<0.0001). After adjustment for age, gender and traditional cardiovascular risk factors the association was confirmed (OR: 5.83, 95%CI 2.83-12.01; p<0.0001). Moreover, a significant association between low protein Z levels and clinical severity of the disease, evaluated through Fontaine's stages, was reported after adjustment for age, gender, and traditional cardiovascular risk factors (general linear model, p for trend: 0.03). In conclusion, our data shows an association between low protein Z levels and the occurrence of PAD. These findings provide evidence for the role of protein Z in the pathogenesis of the atherosclerotic disease.

Comparison of different methods to evaluate the effect of aspirin on platelet function in high-risk patients with ischemic heart disease receiving dual antiplatelet treatment.

Patients with coronary artery disease (CAD) receiving aspirin therapy with a residual platelet reactivity (RPR) may be at increased risk of ischemic vascular events. Point-of-care (POC) methods PFA-100 (Dade-Behring, Marburg, Germany) and VerifyNow (Accumetrics, San Diego, CA) assays have been suggested as rapid tools to evaluate RPR. We compared PFA-100 closure times by collagen/epinephrine and VerifyNow Aspirin assays with light transmission aggregation (LTA) induced by 1 mmol/L of arachidonic acid in 484 patients with CAD undergoing percutaneous coronary intervention and receiving dual antiplatelet therapy. RPR was detected in 30.0% of patients by LTA, in 32.4% by PFA-100, and in 14.3% by VerifyNow. Significant correlations were found among 3 methods (all P < .0001). In relation to the presence or absence of RPR by LTA and PFA-100, by LTA and VerifyNow, and by PFA-100 and VerifyNow, samples were significantly concordant (all P < .0001). Assuming LTA as the reference method, PFA-100 and VerifyNow showed sensitivity of 62.1% and 39.3% and specificity of 80.2% and 96.4%, respectively. The cutoff values for POC methods need to be defined for clinical use.

Usefulness of aspirin resistance after percutaneous coronary intervention for acute myocardial infarction in predicting one-year major adverse coronary events.

Recently, great interest has focused on the phenomenon of aspirin resistance, which may be defined as clinical or laboratory resistance. Monitoring the antiplatelet effect appears to be relevant in the presence of clinical implications, but no data are available on the possible clinical implications of the failure of aspirin to inhibit tests of platelet function in the setting of acute coronary syndromes. This study evaluated the role of aspirin resistance in the occurrence of 1-year major adverse coronary events (MACEs) in patients with acute myocardial infarction (AMI) who have undergone percutaneous coronary intervention (PCI). We prospectively evaluated 146 patients (115 men and 31 women; median age 65 years, range 30 to 84) with AMI who underwent primary PCI. Exclusion criteria were the use of glycoprotein IIb/IIIa inhibitors, hematocrit

TAFI activity and antigen plasma levels are not increased in acute coronary artery disease patients admitted to a coronary care unit.

INTRODUCTION: Hypofibrinolysis, at least in part due to high levels of plasminogen activator inhibitor-1 (PAI-1), has been reported to occur frequently in patients with coronary artery disease (CAD). A recently described carboxypeptidase, thrombin-activatable fibrinolysis inhibitor (TAFI), is involved in the regulation of the balance between coagulation and fibrinolysis. High TAFI plasma levels may therefore contribute to a hypofibrinolytic state and to an increased risk for thrombotic disorders. There are contradictory results regarding TAFI levels in CAD patients, possibly because the characteristics of patients investigated and the time of blood sampling were different among different studies. MATERIALS AND METHODS: Fibrinolytic inhibitors (TAFI activity, TAFI antigen and PAI-1 activity plasma levels) were measured in 44 consecutive patients admitted to the Coronary Care Unit of the University of Florence and in a group of 44 healthy controls, matched for age and sex, to detect a possible association of their levels with acute CAD. RESULTS: No differences were found in TAFI levels, either activity or antigen, between patients and controls. PAI-1 activity was significant different between patients and controls (p=0.0001). The frequencies of TAFI activity and antigen over cut-off levels were similar in patients and controls. Instead, higher PAI-1 levels were more frequent (p=0.04) in patients respect to controls. The univariate analysis confirmed the association of increased PAI-1 levels with acute CAD [OR=3.3; p=0.04]. Among the patients, TAFI and PAI-1 levels were not different according to clinical presentation of symptoms or indication to immediate percutaneous revascularization. CONCLUSION: Our study suggests that in acute phase of CAD no increased levels of TAFI are detectable in plasma.

Hyperhomocysteinemia and hypercoagulability in primary biliary cirrhosis.

AIM: To assess the hypercoagulability in PBC and its relationship with homocysteine (HCY) and various components of the haemostatic system. METHODS: We investigated 51 PBC patients (43F/8M; mean age: 63+/-13.9 yr) and 102 healthy subjects (86 women/16 men; 63+/-13 yr), and evaluated the haemostatic process in whole blood by the Sonoclot analysis and the platelet function by PFA-100 device. We then measured HCY (fasting and after methionine loading), tissue factor (TF), thrombin-antithrombin complexes (TAT), D-dimer (D-D), thrombomodulin (TM), folic acid, vitamin B6 and B12 plasma levels. C677T 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphism was analyzed. RESULTS: Sonoclot RATE values of patients were significantly (P<0.001) higher than those of controls. Sonoclot time to peak values and PFA-100 closure times were comparable in patients and controls. TAT, TF and HCY levels, both in the fasting and post-methionine loading, were significantly (P<0.001) higher in patients than in controls. Vitamin deficiencies were detected in 45/51 patients (88.2%). The prevalence of the homozygous TT677 MTHFR genotype was significantly higher in patients (31.4%) than in controls (17.5%) (P<0.05). Sonoclot RATE values correlated significantly with HCY levels and TF. CONCLUSION: In PBC, hyper-HCY is related to hypovitaminosis and genetic predisposing factors. Increased TF and HCY levels and signs of endothelial activation are associated with hypercoagulability and may have an important role in blood clotting activation.

A proinflammatory state is associated with hyperhomocysteinemia in the elderly.

BACKGROUND: The mechanism by which high circulating homocysteine concentrations are a risk factor for atherothrombosis is incompletely understood. A proinflammatory state is related to atherosclerosis, and recent studies suggest that acute phase reactants correlate with circulating concentrations of homocysteine. OBJECTIVE: We determined whether high concentrations of inflammatory markers are associated with hyperhomocysteinemia independently of dietary vitamin intakes, vitamin concentrations, and cardiovascular disease risk factors in a large, representative sample of the general population. DESIGN: Five hundred eighty-six men and 734 women were randomly selected from the inhabitants of 2 small towns near Florence, Italy. RESULTS: After adjustment for multiple potential confounders, interleukin 1 receptor antagonist (IL-1ra) and interleukin 6 (IL-6) concentrations were significantly (P < 0.001) associated with plasma homocysteine concentrations in older (>65 y) populations. Compared with participants in the lowest IL-6 tertile, those in the highest tertile had a higher risk of having homocysteine concentrations that were high (>30 micromol/L; odds ratio: 2.6; 95% CI: 1.1, 5.6; P = 0.024) or in the intermediate range 15-30 micromol/L (odds ratio: 1.6; 95% CI: 1.2, 2.2; P = 0.0014). Sedentary state, intakes of vitamin B-6 and folic acid, and serum folate, vitamin B-12, vitamin B-6, and alpha-tocopherol concentrations were significant independent correlates of homocysteine. CONCLUSIONS: High circulating concentrations of IL-1ra and IL-6 are independent correlates of hyperhomocysteinemia and may explain, at least in part, the association between homocysteine and atherosclerosis.

Increased plasma levels of lipoprotein(a) and the risk of idiopathic and recurrent venous thromboembolism.

PURPOSE: Elevated lipoprotein(a) [Lp(a)] levels are a recognized risk factor for cardiovascular disease; however, little is known about their effects on venous thromboembolism. METHODS: We conducted a case-control study of 603 adult patients with a history of venous thromboembolism (at least 6 months after the acute event) and 430 healthy subjects. We measured Lp(a), homocysteine, and antithrombin levels, factor V Leiden and factor II (prothrombin) polymorphisms, and anticardiolipin antibodies. RESULTS: Lp(a) levels >300 mg/L were found in 24% (n = 146) of the patients and in 13% (n = 58) of the controls (P = 0.005). In a multivariate analysis adjusted for acquired and hemostasis-related risk factors, there was an independent association between elevated (>300 mg/L) Lp(a) levels and venous thromboembolism (odds ratio = 2.1; 95% confidence interval: 1.4 to 3.2; P = 0.002). These results were confirmed in the 341 patients with idiopathic venous thromboembolism, as well as in those with recurrent thromboembolism. CONCLUSION: These results show that Lp(a) is an independent risk factor for venous thromboembolism in adults, suggesting that it may be involved in the pathogenesis of idiopathic and recurrent disease.

Influence of endothelial nitric oxide synthase gene polymorphisms (G894T, 4a4b, T-786C) and hyperhomocysteinemia on the predisposition to acute coronary syndromes.

BACKGROUND: Nitric oxide is an endothelium-derived relaxing factor that contributes significantly to vascular tone regulation. In this study we investigated the role of endothelial nitric oxide synthase (eNOS) polymorphisms as predisposing factors to acute coronary syndromes (ACS). METHODS: In 477 consecutive patients admitted to the coronary intensive therapy unit of the University of Florence and in 537 unrelated controls, genotypes of eNOS G894T and T-786C polymorphisms were determined by polymerase chain reaction-restriction fragment length polymorphism analysis and the repeat polymorphism 4a/4b was analyzed by polymerase chain reaction. The genotype distribution was in Hardy-Weinberg equilibrium for all variants. RESULTS: The multivariate analysis showed that the homozygosity for the eNOS 4a rare variant represented an independent predisposition factor to ACS (odds ratio [OR] 2.5, 95% CI 1.1-5.4, P =.02) and in particular influenced the risk of acute myocardial infarction (OR 3.6, 95% CI 1.2-11.5, P =.03). Subjects carrying the 4a4a/-786CC haplotype showed a higher predisposition to the disease (OR 6.1, 95% CI 1.3-29.6, P =.02). The contemporary presence of hyperhomocysteinemia and homozygosity for the -786C variant influenced the predisposition to ACS (OR 9.1, 95% CI 1.7-46.7, P =.008). CONCLUSIONS: The presence of the eNOS 4a4a genotype represents a predisposing condition to ACS and in particular to acute myocardial infarction. Moreover, our data provide the evidence that the -786CC pattern modulates the susceptibility to ACS in 4a4a homozygotes and in hyperhomocysteinemic patients.

Hyperhomocysteinemia and vitamin B6 deficiency: new risk markers for nonvalvular atrial fibrillation?

BACKGROUND: A recent "ex-vivo" study showed that nonvalvular atrial fibrillation (NVAF) is associated with enhanced activity of metalloproteinases at the atrial level, and in animal models homocysteine (Hcy) is able to activate metalloproteinases. The aim of this case-control study was to investigate the association of total Hcy plasma levels, vitamin status (folate, vitamin B6, and vitamin B12), and methylenetetrahydrofolate reductase C677T and CBS 844ins68 polymorphisms with NVAF. Furthermore, the role of these variables in the occurrence of ischemic events was investigated. METHODS: We studied 310 NVAF patients on oral anticoagulant treatment (168 patients with previous ischemic events and 142 without) and 310 controls. RESULTS: Hyperhomocysteinemia (highest quartile) and vitamin B6 deficiency (lowest quartile) were independently associated with NVAF after multivariate analysis (Hcy: odds ratio [OR] 6.40, 95% CI 3.29-12.46; vitamin B6: OR 3.02, 95% CI 1.02-8.95). A significant correlation was found between Hcy levels and left atrial diameter (r = 0.46; P <.001). As shown by multivariate analysis, elevated Hcy levels were an independent risk factor for ischemic complications during NVAF (OR 2.66, 95% CI 1.15-6.20). CONCLUSIONS: This study demonstrates a significant association of both elevated Hcy levels and low vitamin B6 levels with the presence of NVAF; in addition, it confirms the role of Hcy as a risk factor for ischemic events during NVAF.

Vitamin supplementation reduces the progression of atherosclerosis in hyperhomocysteinemic renal-transplant recipients.

BACKGROUND: We previously demonstrated among renal-transplant recipients (RTRs) a high prevalence of hyperhomocysteinemia, which might account for their elevated cardiovascular risk. The purpose of our study was to document, in hyperhomocysteinemic RTRs, the effect of vitamin supplementation on carotid intima-media thickness (cIMT), which is an early sign of atherosclerosis. METHODS: A total of 56 stable hyperhomocysteinemic RTRs were randomly assigned to vitamin supplementation (folic acid 5 mg/day; vitamin B(6) 50 mg/day; vitamin B(12) 400 microg) (group A) or placebo treatment (group B) for 6 months. All subjects underwent cardiovascular risk-factor assessment, including fasting homocysteine (Hcy) levels assay, and high resolution B-mode ultrasound to measure the intima-media thickness of common carotid arteries, at time of enrollment and after 6 months. RESULTS: Fasting Hcy levels markedly decreased in group A after treatment (21.8 [15.5-76.6] micromol/L vs. 9.3 [5.8-13] micromol/L; P<0.0001), whereas no significant changes were observed in group B (20.5 [17-37.6] micromol/L vs. 20.7 [15-34] micromol/L; P=not significant). In group A, cIMT significantly decreased after treatment (0.95+/-0.20 mm vs. 0.64+/-0.17 mm; P<0.0001). All except one patient showed a reduction of cIMT and the mean percentage of cIMT decrease was -32.2+/-12.9%. Patients with methylenetetrahydrofolate reductase (MTHFR) C677T +/+ genotype, with higher Hcy levels, had the major percentage of decrease of Hcy with respect to the other genotypes (mean decrease: MTHFR +/+ 74.8+/-5.7%; MTHFR +/- 58.1+/-10%; MTHFR -/- 56.3+/-8.6%). In hyperhomocysteinemic patients without vitamin supplementation (group B) we documented a significant increase in cIMT after 6 months (0.71+/-0.16 mm vs. 0.87+/-0.19 mm; P<0.05). In 19 of 28 subjects we observed an increase in cIMT, and in 9 of 28 the cIMT was unmodified. The mean percentage of cIMT increase was + 23.3+/-21.1%. CONCLUSIONS: Our results demonstrate a beneficial effect of the treatment of hyperhomocysteinemia by vitamin supplementation on cIMT in a group of RTRs.

Low protein Z plasma levels are independently associated with acute coronary syndromes.

Protein Z (PZ) is a single chain vitamin-K-dependent glycoprotein synthesized by the liver. Studies in vivo and in vitro suggest that PZ plays an important role in inhibiting coagulation as it serves as cofactor for the inactivation of factor Xa by forming a complex with the plasma PZ-dependent protease inhibitor. Recently, conflicting findings on plasma PZ levels in patients with ischemic stroke have been published. Aim of our study was to investigate the role of PZ in acute coronary syndromes (ACS). PZ plasma levels were determined in 223 (189 M; 34 F) patients with ACS referring to the Coronary Intensive Therapy Unit of University of Florence and in 265 (219 M; 46 F) healthy subjects. Patients under oral anticoagulation treatment as well as subjects with positivity for antiphospholipid antibodies were excluded. None had liver or kidney dysfunction. The mean PZ plasma level was lower in patients (1508 +/- 730 ng/mL) than in controls (1728 +/- 594 ng/mL) (p < 0.0001). PZ levels below the 5th percentile (565 ng/mL) of normal values distribution in control subjects were found in 15.7% of patients and in 4.9% of controls (p <0.0001). At multivariate analysis, PZ levels below 565 ng/mL were associated with ACS (OR=3.3; 99%CI 1.1-9.7; p = 0.004). The contemporary presence of low PZ levels and smoking habit leads to an increased risk of ACS (OR=9.5; 99%CI 2.4-37.2; p < 0.0001). In conclusion, our results suggest a possible role of PZ in the occurrence of arterial thrombosis.

Plasma and serum levels of D-dimer and their correlations with other hemostatic parameters in pregnancy.

The measurement of D-dimer in serum samples (s-DD) after standardized coagulation has been reported as a possible single global test for fibrinolysis in unstimulated conditions in healthy subjects and in patients with ischemic heart disease and with different metabolic disorders. No study has been performed on the use of this test in pregnancy, a condition characterized by physiological changes both in coagulation and in fibrinolysis. In this preliminary study, we have evaluated in 28 women with physiological pregnancy and in 23 comparable controls s-DD and a number of markers of coagulation and fibrinolysis. In nonpregnant women s-DD showed a good correlation with fibrinolytic parameters [euglobulin lysis time (ELT) and type 1 inhibitor of tissue plasminogen activator (PAI-1) act: P<.01; tissue plasminogen activator (t-PA) ag and PAI-1 ag: P<.05], confirming previous data, whereas in pregnant women no correlation was observed. Plasma DD (pls-DD) and s-DD levels were not correlated either in pregnant or in control women. s-DD levels were significantly higher than pls-DD in controls and in 15/28 pregnant women whose pls-DD values were in normal range or mildly increased (<110 ng/ml; P<.05), whereas in the 13 pregnant women with high pls-DD levels no significant differences were found between pls-DD and s-DD levels. Because in pregnancy high pls-DD levels are frequently found, possibly only as a consequence of enhanced clotting activation and fibrin deposition, we cannot exclude that D-dimer measured in serum reflects, at least in part, cross-linked fibrin degradation products (FDP) already present in blood before standardized coagulation. Therefore, D-dimer generated in vitro would account only in part for s-DD measured. This can explain why in pregnant women, differently from controls, s-DD does not correlate with fibrinolytic parameters. In conclusion, this preliminary study indicates that baseline pls-DD levels may be an important potential confounder in the interpretation of s-DD results in pregnant women and that s-DD cannot be proposed as a tool for a rapid evaluation of fibrinolytic activity in pregnancy.

Genetic determinants of fasting and post-methionine hyperhomocysteinemia in patients with retinal vein occlusion.

INTRODUCTION: Moderate hyperhomocysteinemia is considered a risk factor for both venous and arterial thrombosis. A prevalence of up to 30% of fasting hyperhomocysteinemia has been recently reported in patients with retinal vein occlusion (RVO) whereas conflicting data exist on the role of C677T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene as a risk factor for RVO. No report has been published on cystathionine beta-synthase (CBS) 844ins68 polymorphism (another genetic determinant of blood Hcy levels) in RVO patients. Moreover, scarce information is available on the usefulness of measuring homocysteine also after methionine loading to increase the diagnostic efficacy of hyperhomocysteinemia in RVO patients. MATERIALS AND METHODS: In 55 consecutive patients with diagnosis of RVO and 65 matched controls, plasma fasting total homocysteine (Hcy) levels and CBS and MTHFR polymorphisms were evaluated. In patients with normal fasting Hcy levels, post-methionine Hcy levels were determined. RESULTS: Moderate fasting hyperhomocysteinemia was detected in 18/55 patients (32.7%). In the remaining 37 patients, Hcy was measured again post-methionine loading (PML). Only 3/37 (8.1%) patients had PML hyperhomocysteinemia. Thus, the total prevalence of moderate hyperhomocysteinemia in this cohort of RVO patients was 21/55 (38.2%). The prevalence of homozygosity for C677T MTHFR genotype, but not that of heterozygosity for CBS844ins68, was significantly higher in RVO patients than in controls. CONCLUSIONS: Differently from what has been reported for arterial and/or venous thrombosis, a single fasting Hcy measurement is able to detect most of RVO patients (85.7%) with moderate hyperhomocysteinemia. C677T MTHFR, but not CBS 844ins68, genotype may play a role as risk factor for RVO.

Hypercoagulability, high tissue factor and low tissue factor pathway inhibitor levels in severe ovarian hyperstimulation syndrome: possible association with clinical outcome.

During ovarian gonadotrophin stimulation for ovulation induction or in vitro fertilization, a clinical severe ovarian hyperstimulation syndrome (OHSS) may occur. Only few studies have investigated the mechanism responsible for the alterations of the haemostatic system in women affected by severe OHSS. The aim of the present study was to investigate the correlation between the magnitude of ovarian stimulation and the increase in fibrin formation and degradation in severe OHSS. Twenty-five patients (age range 23-43 years) who were hospitalized for severe OHSS, 25 women undergoing in vitro fertilization who did not develop OHSS (case-control group) and 25 healthy age-matched women (healthy control group) were investigated. On the day of admission a number of haemostatic markers, including D-dimer, thrombin-antithrombin complexes (TAT), prothrombin fragment 1 + 2 (F1 + 2), plasmin-antiplasmin complexes (PAP), tissue factor (TF), tissue factor pathway inhibitor (TFPI) and von Willebrand factor antigen (vWF), were examined. In patients with severe OHSS, TF, D-dimer, TAT, F1 + 2, PAP and vWF antigen plasma levels were significantly higher than those observed both in the case-control group and in healthy controls, whereas TFPI levels were significantly lower (P < 0.005) with respect to both case-controls and healthy controls. D-Dimer levels were related with serum oestradiol levels and oocyte number recovered (r = 0.45, P < 0.001 and r = 0.47, P < 0.001, respectively). D-Dimer and TAT levels were significantly (P < 0.05 and P < 0.005, respectively) higher in OHSS patients with unsuccessful pregnancy outcome (D-dimer, 226.5, 56-1449 ng/ml; TAT, 19.8, 3.1-82.6 microg/l) with respect to those with successful outcome of pregnancy (D-dimer, 145, 29-330 ng/ml; TAT, 5.0, 1.0-19.6 microg/l). Our data indicate that a marked hypercoagulability with alterations of TF and TFPI levels is detectable in patients with severe OHSS and that it is related to the clinical outcome.

Protein Z: "light and shade" of a new thrombotic factor.

Protein Z is a vitamin K-dependent plasma protein described in its human form in 1984. The amino acid sequence of protein Z shows wide homology with many coagulation factors, such as VII, IX, X, and protein C. However, in contrast to other vitamin K-dependent coagulation factors, protein Z is not a serine protease because of the lack of the active centre in its amino acid sequence. The physiological function of protein Z has been uncertain for many years. In vitro and in vivo studies recently suggested that protein Z plays an important role in inhibiting coagulation, as it serves as cofactor for the inactivation of activated factor X by forming a complex with the plasma protein Z-dependent protease inhibitor. The role of alterations of the protein Z levels has been evaluated in different disease states, with conflicting findings. Most of these studies were performed on ischemic vascular diseases. Recently, the possible role of protein Z deficiency in the occurrence of cardiovascular diseases has been evaluated.