Relevance of post-methionine homocysteine and lipoprotein (a) in evaluating the cardiovascular risk in young CAD patients.

BACKGROUND: Aims of our study were to evaluate the prevalence of high lipoprotein (a) [Lp(a)] and homocysteine levels - both in the fasting state (FHcy) and post-methionine (PMHcy) - in young coronary artery disease (CAD) patients, and to investigate the role of genetic and environmental factors for hyperhomocysteinaemia. MATERIALS AND METHODS: We studied 140 patients with angiographically documented CAD (24 women

ACE DD genotype: an independent predisposition factor to venous thromboembolism.

BACKGROUND: The renin angiotensin system affects haemostasis through different mechanisms; data on the possible role of angiotensin-converting enzyme I/D polymorphism in the pathogenesis of deep venous thrombosis are conflicting, and no information is available regarding the A1166C polymorphism of the angiotensin type 1 receptor gene. In order to investigate this issue, angiotensin-converting enzyme and AT1R polymorphisms were genotyped in 336 consecutive venous thromboembolism patients and 378 controls. MATERIALS AND METHODS: Haemostasis-related risk factors have been evaluated by routine tests. Factor V Leiden, Factor II (G20210A), angiotensin-converting enzyme (I/D), and angiotensin type 1 receptor (A1166C) polymorphisms have been identified by molecular analysis. RESULTS: We documented a significant association between angiotensin-converting enzyme DD genotype and venous thromboembolism (OR=2.19 95%CI 1.51-3.17 adjusted for acquired and haemostasis-related risk factors, P<0.0001); in patients with haemostasis-related risk factors, angiotensin-converting enzyme DD genotype modified the risk of venous thromboembolism in hyperhomocysteinaemic and Factor V Leiden patients and was associated with the risk of recurrent venous thromboembolism (OR=1.83 95%CI 1.06-3.17 P=0.03). In patients without haemostasis-related risk factors the angiotensin-converting enzyme DD genotype was still an independent predictor of venous thromboembolism (OR=3.29 95%CI 2.17-4.98 adjusted for acquired risk factors, P<0.0001). No significant association between the angiotensin type 1 receptor CC genotype and venous thromboembolism was found. CONCLUSIONS: This study shows that angiotensin-converting enzyme DD genotype represents a susceptibility marker of thrombosis in subjects apparently without predisposing factors and traditional thrombophilic alterations, and increases the risk of venous thromboembolism in subjects in whom a thrombogenic condition occurs. Moreover, angiotensin-converting enzyme DD genotype may be considered a new predisposing factor to venous thromboembolism recurrence.

Comparison between NRT-based MAPs and behaviourally measured MAPs at different stimulation rates--a multicentre investigation.

Seventeen adult subjects participated in a multicentre trial to compare the performance between an NRT-based MAP and their behavioural MAP. The NRT-based MAP was made using a correction factor to predict T/C levels, calculated from the difference between the ECAP threshold ('T-NRT') and the measured T/C levels at electrode 10, as described by Brown et al. (2000). A secondary aim was to compare T/C levels in behavioural MAPs at different stimulation rates with the predicted T/C levels in NRT-based MAPs. Performance with both MAPs was evaluated using CNC words and sentences. Variations in the T/C levels between all MAPs were found, although results of the speech discrimination tests demonstrated no statistically significant difference between behavioural and NRT-based MAPs.

The C677T methylenetetrahydrofolate reductase mutation is not associated with Alzheimer's disease.

The methylenetetrahydrofolate reductase (MTHFR) gene has been recently considered as a candidate gene for Alzheimer's disease (AD). MTHFR is a key enzyme in the metabolism of homocysteine and elevated levels of that amino acid have been associated to Vascular Dementia and AD. A T-->C transition at codon 677 produces a thermolabile type of the enzyme. However, contrasting results on the distribution of the MTHFR C677T common polymorphism in AD have been published. We analyzed the distribution of the MTHFR and apolipoprotein E (APOE) polymorphisms in Italian patients with sporadic AD. The distribution of the C677T polymorphism did not differ in AD and controls. Our data suggest that the MTHFR polymorphism does not contribute to genetic susceptibility in Italian sporadic AD and does not mitigate the effect of ApoE epsilon4 allele on AD risk.

Thrombophilic risk factors in patients with central retinal vein occlusion.

Few and contrasting data are available on the prevalence of hemostatic risk factors in patients with central retinal vein occlusion (CRVO). Aim of this study was to investigate the metabolic and inherited risk factors for venous thrombosis in 100 CRVO patients (age: 59 yrs; range 18-77) and in 100 controls (age: 56 yrs; range 18-84). In patients homocysteine (Hcy) levels were significantly higher than in controls and were affected by the C677T methylenetetrahydrofolate reductase (MTHFR) polymorphism (p < 0.001). The prevalences of activated protein C resistance (APCR), factor V Leiden positivity, elevated PAI-1 and Lp(a) levels were significantly higher in patients with respect to controls. At multivariate analysis, only hyperhomocysteinemia (OR 11, 95% CI 3.6-36.2; p < 0.0001) and elevated PAI-1 levels (OR 8.9, 95% CI 3.5-41.3; p < 0.01), in addition to hypertension (OR 40.5, 95% CI 8.6-188.8; p < 0.00001) and hypercholesterolemia (OR 3.1, 95% CI 1.6-20.5; p < 0.05), were independent risk factors for CRVO. These data demonstrate a potential role of hemostatic risk factors in the pathophysiology of CRVO.

Comparison of three methods for total homocysteine plasma determination.

Hyperhomocysteinemia is a well established risk factor for atherothrombotic disease, and the request for homocysteine determinations and the number of laboratories that need to perform this assay to assess individual risk profile is increasing. Different methods to evaluate homocysteine plasma levels are at present available. In the present study three methods, an in-house high-pressure liquid chromatographic (HPLC) method (considered as reference method) and two commercial immunoassays, an enzyme-linked immunoassay (EIA) and an automated fluorescence polarization immunoassay (FPIA), were used to measure homocysteine plasma levels in 100 samples. The median of homocysteine plasma levels obtained by HPLC was 9.0 micromol/L (range 4.2-23.0); the median of values obtained by EIA and FPIA were 10.6 micromol/L (range 3.3-21.5) and 9.6 micromol/L (4.8-20.2), respectively. The FPIA method showed the lowest within-run and between-run coefficients of variation (3.6% and 4.1%, respectively). There was a significant correlation between EIA and HPLC (r=0.81; p<0.0001), and between FPIA and HPLC (r=0.85; p<0.0001). The Bland-Altman analysis showed that FPIA agreed best with HPLC; EIA displayed a relatively wide scatter of difference data points. The present results indicate that the technological characteristics of the FPIA assay make this method suitable for the determination of Hcy in clinical laboratories.

The role of cysteine and homocysteine in venous and arterial thrombotic disease.

Hyperhomocysteinemia is a risk factor for arterial and venous thrombosis, whereas few data are available on the total cysteine (tCy) levels in thrombophilic patients. We studied 82 patients with a previous myocardial infarction (MI; group 1), 68 patients with a previous deep venous thrombosis (group 2), and 100 control subjects (group 3). We assayed total homocysteine (tHcy) and tCy levels by high-performance liquid chromatography with fluorimetric detection. The odds ratios (ORs) for high levels of tCy and tHcy in venous thrombosis and MI were markedly increased in group 1 (fasting tCy: OR, 3.6; 95% confidence interval [CI], 1.6-11.2; postmethionine tCy: OR, 0.97; CI, 0.3-4.0; fasting tHcy: OR, 8.3; CI, 3.9-18.6; postmethionine tHcy: OR, 12.5; CI, 6.8-27.2) and in group 2 (fasting tCy: OR, 2.9; CI, 1.1-7.8; postmethionine tCy: OR, 0.86; CI 0.2-2.6; fasting tHcy: OR, 8.0; CI 3.6-18.0; postmethionine tHcy: OR, 11.0; CI, 6.0-22.1). Our data suggest that plasma tCy levels are a risk factor for venous thrombosis and MI independently of tHcy levels and that it may be appropriate to study both variables simultaneously to thoroughly study the methionine metabolism.

Fibrillin-1 (FBN1) gene frameshift mutations in Marfan patients: genotype-phenotype correlation.

Marfan syndrome (MFS) is a multisystemic disease associated with mutations in the fibrillin-1 gene. Most of the reported mutations are missense substitutions mainly affecting the epidermal growth factor (EGF)-like protein domain structure and the calcium-binding (cb) site. The aim of our study was to investigate the correlation between fibrillin-1 frameshift mutations and the clinical phenotype in patients affected by MFS. In 48 out of 66 Marfan patients a pathogenetic mutation was found. We detected novel mutations causing premature termination codon in exons 19, 37, 40 and 41 of four Italian patients. The first mutation in exon 19 (cbEGF #8 domain) results in a clinical phenotype involving mainly the skeletal and cardiovascular systems. Interestingly, we noticed that, while mutations in exons 37 and 41 (eight cysteine domains #4 and #5) are milder, the mutation in exon 40 (cbEGF #24 domain) is more severe and causes major cardiovascular involvement with thoracic and abdominal aortic aneurysms. It is noteworthy that the degree of the severity in the phenotype of one of our patients and another from the literature carrying a mutation in exon 41 could be explained with alterations in mRNA expression.

High cysteine levels in renal transplant recipients: relationship with hyperhomocysteinemia and 5,10-MTHFR polymorphism.

BACKGROUND: Long-term survival of renal transplant recipients seems to be influenced by the occurrence of thromboembolic complications and cardiovascular disease. Preliminary data available in the literature found high levels of cysteine (Cy) as a risk factor for deep venous thrombosis independently of high homocysteine (tHcy) levels, but no data are available about Cy levels in renal transplant recipients. METHODS: To investigate Cy, tHcy, and plasminogen activator inhibitor-1 (PAI-1) levels and the prevalence of 5,10-methylenetetrahydrofolate reductase (MTHFR) in renal transplantation, we studied 70 stable renal transplant recipients and 66 age- and sex-matched normal subjects as controls. RESULTS: Cy, tHcy, and PAI-1 levels were significantly higher in renal transplant recipients with respect to controls (Cy: 254 micromol/L [117-466] vs. 198 micromol/L [99-331], P<0.001; tHcy: 17.0 micromol/L [4.0-68] vs. 8.1 micromol/L [2.0-24.0], P<0.00001; PAI-1: 16.8 IU/ml [5.1-45.5] vs. 7.9 IU/ml [4.0-18.0], P<0.00001). High Cy levels were detected in 35.8% of patients. Hyperhomocysteinemia, both in the fasting state and postmethionine loading test, was diagnosed in 90% of cases. The odds ratios for Cy and tHcy levels within the fourth quartile with respect to the other quartiles were markedly increased in renal transplant recipients even after adjustment for prevalent cardiovascular risk factors, glomerular filtration rate, tHcy and, Cy, respectively (Cy: 29.0 micromol/L [95% CI 7.0-111]; tHcy: 29.9 micromol/L [95% CI 7.5-118.1]). Fasting tHcy levels correlated well with PAI-1 (r=0.65; P<0.0001) but not with Cy levels (r=0.10; P=0.4). The prevalence of the MTHFR 677TT genotype in renal transplant recipients was not significantly higher in patients than in controls (mutant allele frequency: 0.48 in patients and 0.47 in controls) and was associated with significantly higher fasting and postmethionine tHcy levels both in controls and patients. After 2 months of vitamin supplementation, tHcy (Pre: 17.0 micromol/L [4.0-68]; Post: 7.5 micromol/L [2.3-21.9]; P<0.0001) and PAI-1 levels (Pre: 16.8 IU/ml [5.1-45.5]; Post: 10 IU/ml [2.0-25]; P<0.001) were significantly decreased, whereas Cy levels showed a small decrease that did not reach statistical significance (Pre: 254 micromol/L [117-466]; Post: 209 micromol/L [168-300]; P=0.3). Patients with the MTHFR 677TT genotype had the major percentage of decrease of tHcy levels with respect to the other genotypes. CONCLUSION: In conclusion, this study demonstrates the presence of elevated Cy plasma levels in renal transplant recipients. Vitamin supplementation reduces tHcy but not Cy levels, and the amount of decrease seems to be influenced by the MTHFR genotype.

Hyperhomocysteinemia in renal transplant patients: an independent factor of cardiovascular disease.

Hyperhomocysteinemia (Hcy) is an independent factor of cardiovascular disease, which is the main cause of morbidity and mortality both in uremic and kidney transplant patients. The aim of the study was to determine Hcy, plasminogen activator inhibitor (PAI-1) and lipoprotein (a) (Lp(a)) serum levels in 70 patients with a well functioning renal transplant. We also verified whether these levels were modified by a multivitamin therapy. The genetic polymorphism of the methylenetetrahydrofolate reductase (MTHFR) enzyme which plays a main role in Hcy metabolism, was studied as well. We found Hcy, PAI-1 and Lp(a) levels significantly elevated with respect to healthy control subjects. The thermolabile form of the MTHFR enzyme was linked to higher Hcy levels. After a short time on therapy with B6, B12 and folic acid vitamins, Hcy and PAI-1 decreased to normal levels. The authors conclude that high Hcy levels could be a relevant covariate for cardiovascular disease in transplant patients and they suggest that vitamin supplementation be recommended as a part of therapy.

Activation of the immune system and coronary artery disease: the role of anti-endothelial cell antibodies.

On the basis of the role of immuno-mediated inflammation in atherosclerosis we investigated, (1) the prevalence of anti-endothelial cell antibodies (AECA) in ischaemic heart disease (IHD); (2) if beta2-glycoprotein I (beta2-GPI) was the target antigen of AECA; (3) the relationship between AECA, tissue factor (TF) and tissue factor pathway inhibitor (TFPI). In 93 consecutive IHD patients undergoing percutaneous transluminal coronary angioplasty (PTCA) and 105 controls AECA were detected by ELISA on human umbilical vein endothelial cells (HUVEC). AECA positive sera were evaluated for anti-beta2-GPI antibodies by ELISA. TF and TFPI plasma levels were assessed by ELISA. Twelve of 93 (12.9%) IHD patients and only one of 105 controls (0.95%) were AECA positive. The prevalence of AECA was higher in unstable angina (UA) than in effort angina (EA) (P=0.01). Three of 12 AECA positive sera resulted positive for anti-beta2-GPI and showed a marked decrease in EC-binding when tested on HUVEC cultured in serum-free medium. The binding was restored by the addition of beta2-GPI. TF and TFPI levels were similar in AECA positive and AECA negative patients. The rate of angiographically documented clinical recurrences was 66.7% in the AECA positive and 14.8% in the AECA negative group (P=0.0004) with a significant relationship between restenosis and AECA (P<0.0001), unchanged by the inclusion of cardiovascular risk factors in the regression model. Our results suggest a 'role' for AECA in the immune-mediated inflammation in UA beta2-GPI is not the only AECA target antigen. AECA are not responsible for high TF and TFPI levels. The high rate of clinical recurrences after PTCA, confirmed by angiography, in AECA positive patients is in line with such a role and suggests further large-scale 'ad hoc' studies.

Risk factors for cardiovascular disease in renal transplant recipients: new insights.

Long-term survival of renal transplant recipients appears to be influenced by the occurrence of thromboembolic complications and cardiovascular disease. In order to investigate the prevalence of new hemostasis-related risk factors for venous and arterial thrombosis, we investigated 63 renal transplant recipients and 66 age- and sex-matched control subjects. We assayed antiphospholipid antibodies [lupus anticoagulant (LA) and anticardiolipin antibodies (aCL)], lipoprotein (a) [Lp(a)], plasminogen activator inhibitor-1 (PAI-1), and total homocysteine (tHcy) levels. We found a significantly higher prevalence of positivity for LA (P < 0.001); no difference was detected in the prevalence of aCL between patients and controls. PAI-1 levels were significantly higher in renal transplant recipients than in controls [12.3 IU/ml (2-45.5) vs 7.9 IU/ml (4-18.0); P < 0.0001] with an odd ratio (OR) of 11.8 (4.9-28.5) in univariate analysis and of 5.8 (2.1-15.4) in multivariate analysis. Lp(a) levels were higher in patients then in controls [159 mg/l (1-992) vs 100.5 mg/l (10-412); P < 0.005] with an OR of 5.9 (1.9-18.4) in univariate analysis and of 3.5 (0.9-13.4) in multivariate analysis. Fasting levels of tHcy were significantly higher in renal transplant recipients [7.0 micromol/l (4.0-68) vs 8.1 micromol/l (2.0-24.0); P < 0.00001] with an OR of 40.4 (14.7-111) in univariate analysis and of 33.1 (11.1-115.5) in multivariate analysis. After methionine loading test, we documented levels of tHcy above the 90th percentile of controls in 60/63 patients (95%). Finally, we found a significant correlation between tHcy and PAI-1 plasma levels (r = 0.76; P < 0.000001). Our results show a high prevalence of hemostasis-related risk factors for arterial and venous thrombosis in renal transplant recipients, suggesting the need for the investigation of these patients for the presence of these risk factors in order to improve their long-term survival and to tailor therapy.

Angiotensin-converting enzyme DD genotype, angiotensin type 1 receptor CC genotype, and hyperhomocysteinemia increase first-trimester fetal-loss susceptibility.

Complications of pregnancy have been found to be related with thrombophilic polymorphisms that explain about 30% of obstetric complications. We evaluated the angiotensin converting enzyme (ACE) and the angiotensin type 1 receptor (AT1R) gene polymorphisms in the renin-angiotensin system (RAS) as possible risk factors for fetal loss. Fifty-nine women with a history of three or more first-trimester fetal losses and 70 healthy women with a history of normal pregnancies were enrolled in this study. Thrombophilic factors, ACE insertion/deletion (I/D) and AT1R A1166C polymorphisms, prothrombin G20210A and factor V Leiden mutations were analyzed. At univariate and multivariate analysis, a significant association between ACE DD and AT1R CC genotype and fetal loss was observed. The effect of the ACE DD genotype on the risk of fetal loss was higher in AT1R C allele carriers. The prevalence of hyperhomocysteinemia (Hcy) (defined as baseline plasma levels higher than the 95% percentile; cut-off, 10.5 micromol/l per l) was significantly higher in women with fetal loss, and an association between Hcy and fetal loss was detected. All patients showed normal antithrombin, protein C, protein S, and plasminogen activator inhibitor-1 (PAI-1) values. The presence of one risk factor not associated with others was found in 33 out of 59 patients (56%); ACE DD genotype was the most prevalent risk factor. Our results identify new possible predictive markers for fetal loss in RAS polymorphisms and Hcy. Large-scale studies are warranted to attribute clinical relevance to these polymorphisms as risk factors for complicated pregnancies.

High prevalence of mild hyperhomocysteinemia in patients with abdominal aortic aneurysm.

PURPOSE: In vitro studies have recently demonstrated that homocysteine interacts with the aortic wall by inducing both elastolysis and endothelial perturbation. The aim of this study was to evaluate homocysteine plasma levels and their relationships with aortic diameter and endothelial damage in patients with abdominal aortic aneurysm. SUBJECTS AND METHODS: Fifty-eight consecutive male patients (mean age, 69.5 +/- 6.6 years; age range, 49-78 years) who underwent abdominal aortic aneurysm surgery were enrolled in the study. Twenty-two of 58 patients had no clinical or instrumental evidence of atherosclerosis. Sixty control subjects were age matched and sex matched with the patients. In all of the subjects, we evaluated total homocysteine and thrombomodulin plasma levels and the distribution of the C677T methylenetetrahydrofolate reductase gene mutation. RESULTS: Hyperhomocysteinemia was found in 26 (48%) of the 58 patients with abdominal aortic aneurysm, and homocysteine plasma levels were significantly higher in patients than in control subjects (15.7 +/- 6.5 micromol/L vs 9.6 +/- 3.9 micromol/L; P <. 0001). In addition, the subgroup of patients with abdominal aortic aneurysm who did not show evidence of atherosclerosis showed homocysteine plasma levels significantly higher than those in the controls (14.8 +/- 6.1 micromol/L vs 9.6 +/- 3.9 micromol/L; P <. 001). A larger aneurysmal size was detected in hyperhomocysteinemic patients than in those with normal homocysteine plasma levels (5.09 +/- 0.84 cm vs 5.79 +/- 1.5 cm; P <.05). The genotype distribution of the C677T methylenetetrahydrofolate reductase mutation was as follows: TT 21%, TC 55%, and CC 24% in the patients; TT 10%, TC 58%, and CC 32% in the controls. Moreover, in patients a significant correlation (P <.005) between homocysteine plasma level and 677TT methylenetetrahydrofolate reductase genotype was found. Thrombomodulin plasma levels were significantly higher (P <.00005) in patients (median, 30 ng/mL; range, 10-164 ng/mL) than in controls (median, 19 ng/mL; range, 13-44 ng/mL), and thrombomodulin levels were significantly higher (P <.005) in hyperhomocysteinemic patients (median, 39.5 ng/mL; range, 15-164 ng/mL) than in normohomocysteinemic patients (median, 27.5 ng/mL; range, 10-85 ng/mL). In addition, in patients with abdominal aortic aneurysm, a direct significant correlation (P <.005) was found between homocysteine and thrombomodulin. CONCLUSIONS: These data indicate an association between the presence of AAA in patients selected for surgical treatment of AAA and elevated homocysteine plasma levels and suggest that homocysteine may induce endothelial perturbation and stimulation in these patients.

Tissue factor and homocysteine levels in ischemic heart disease are associated with angiographically documented clinical recurrences after coronary angioplasty.

BACKGROUND: In ischemic heart disease (IHD) patients high plasma levels of Tissue Factor (TF), the trigger of coagulation cascade, are present. Homocysteine (Hcy) is a risk factor for coronary artery disease, and several different pathophysiological mechanisms by which Hcy may play a role in thrombus formation have been postulated in "in vitro" studies. We investigated the "in vivo" role of Hcy in affecting plasma levels of TF, its inhibitor Tissue Factor Pathway Inhibitor (TFPI) and hypercoagulability. METHODS AND RESULTS: We investigated 119 IHD patients who underwent PTCA and compared them with 103 healthy subjects. TF, TFPI, Thrombin-Antithrombin complexes (TAT) and Hcy levels were significantly higher in the patients than in the controls. A positive correlation was found between Hcy and TF (r = 0.54; p < 0.0001), Hcy and TFPI (r = 0.26; p <0.05) as well as Hcy and TAT (r = 0.33; p <0.0001) levels. An inverse correlation existed between folate intake and Hcy levels (r = -0.28; p = 0.001). Hcy levels within the first quartile and in the highest quartile were associated with a lower (p < 0.001) and higher (p <0.0001) rate of clinical recurrences, respectively. Patients with TF values in the first quartile had a lower rate of angiographically documented clinical recurrences as compared to those in the fourth quartile (p <0.01); those in the highest quartile of TF showed a higher rate of recurrences (p = 0.001). Multivariate analysis confirmed these results (first quartile of Hcy: OR 0.02, C1 0.002-0.27; fourth quartile of Hcy: OR 36.5, C1 3.6-365/first quartile of TF: OR 0.006, C1 0.001-0.44; fourth quartile of TF: OR 16.4, C1 3.0 - 90.0), also after adjustment for risk factors and Hcy and TF respectively. CONCLUSIONS: In this study we show that TF, TFPI and TAT levels are correlated with Hcy plasma levels in IHD patients, providing evidence of an "in vivo" pathophysiological mechanism of hyperhomocysteinemia. The observed association between angiographically documented clinical recurrences and TF and Hcy values awaits confirmation in studies designated to evaluate this issue on a larger number of patients.

A novel de novo mutation in the triple helix of the COL6A3 gene in a two-generation Italian family affected by Bethlem myopathy. A diagnostic approach in the mutations' screening of type VI collagen.

Bethlem myopathy is an autosomal dominant inherited disease producing a mild neuromuscular disorder, characterized mainly by muscular weakness and multiple joint contractures. Bethlem myopathy is caused by mutations in one of the three chains of collagen type VI. Here we report the clinical description and the molecular characterization of the defect in a two-generation Italian family in which a Gly-->Arg substitution disrupts the triple helix structure of the alpha 3 chain of collagen type VI, an ubiquitous glycoprotein of the extracellular matrix. In this family the identification of the mutation also allowed one to exclude the disease in the grandfather. It is noteworthy that the father of the proband carries a de novo mutation, the first described for Bethlem myopathy.

Acquired activated protein C resistance in postmenopausal women is dependent on factor VIII:c levels.

Activated protein C (APC) resistance is an established risk factor for venous thromboembolism. In 5% to 10% of patients with venous thromboembolism, the APC resistance phenotype is observed in the absence of factor V Leiden mutation. Moreover, some physiologic and pathologic conditions are associated with an "acquired" APC resistance, not caused by the Leiden mutation, such as inflammatory diseases, pregnancy, or oral contraceptive therapy. Several studies have demonstrated the effect of menopause on the hemostatic system, but no data are available about APC resistance. We found a high prevalence of APC resistance in postmenopausal women, not associated with factor V Leiden mutation. The mechanism that underlies this acquired APC resistance may be related to the higher levels of factor VIII, which showed a strong inverse correlation with APC resistance, whereas no correlation was found between the normalized APC ratio, factor V levels, and protein S values. Higher levels of factor VIII correlated with a marker of coagulation activation, such as prothrombin fragments 1 plus 2. Therefore, to identify women receiving hormone replacement therapy who have a greater risk for deep venous thrombosis, the APC resistance coagulation test should be used instead of the genetic study.

Tissue factor reduction and tissue factor pathway inhibitor release after heparin administration.

Elevated plasma levels of tissue factor (TF) and tissue factor pathway inhibitor (TFPI) and large amounts of monocyte procoagulant activity (PCA) have been documented in unstable angina (UA) patients. In in vitro experiments heparin is able to blunt monocyte TF production by inhibiting TF and cytokine gene expression by stimulated cells and after in vivo administration it reduces adverse ischemic outcomes in UA patients. TF and TFPI plasma levels and monocyte PCA have been investigated in 28 refractory UA patients before and during anticoagulant subcutaneous heparin administration (thrice daily weight- and PTT-adjusted for 3 days) followed by 5000 IU X 3 for 5 days. After 2-day treatment, immediately prior to the heparin injection, TF and TFPI plasma levels [(median and range): 239 pg/ml, 130-385 pg/ ml and 120 ng/ml, 80-287 ng/ml] were lower in comparison to baseline samples (254.5 pg/ml, 134.6-380 pg/ml and 135.5 ng/ml, 74-306 ng/ml). Four h after the heparin injection TF furtherly decreased (176.5 pg/ml, 87.5-321 pg/ml; -32.5%. p<0.001) and TFPI increased (240.5 ng/ml, 140-450 ng/ml; +67%, p<0.0001). After 7-day treatment, before the injection of heparin, TF and TFPI plasma levels (200 pg/ml, 128-325 pg/ml and 115 ng/ml, 70-252 ng/ml) significantly decreased (p<0.05) in comparison to the pre-treatment values. On the morning of the 8th day, 4 h after the injection of heparin TF plasma levels and monocytes PCA significantly decreased (156.5 pg/ml, 74-259 pg/ml and from 180 U/105 monocytes, 109-582 U/10(5) monocytes to 86.1 U/10(5) monocytes, 28-320 U/10(5) monocytes; - 38% and -55% respectively) and TFPI increased (235.6 ng/ml, 152-423 ng/ ml; +70%, p<0.001). In conclusion, heparin treatment is associated with a decrease of high TF plasma levels and monocyte procoagulant activity in UA patients. These actions of heparin may play a role in determining the antithrombotic and antiinflammatory properties of this drug.

Microheterogeneity in the distribution of the 844ins68 in the cystathionine beta-synthase gene in Italy.

Cystathionine beta-synthase (CBS) is an important enzyme for methionine metabolism. A common 844ins68 insertion variant in the CBS gene has been described. This 68-bp duplication of the intron 7-exon 8 boundary within the CBS gene already has been reported to be associated in cis with the T833C mutation. Heterozygosity for CBS deficiency is considered an important cause of hyperhomocysteinemia that strongly relates to cardiovascular disease, as well as homozygosity for another common variant, the C677T mutation of 5,10-methylene tetrahydrofolate reductase. We analysed the prevalence of the 844ins68 variant in the CBS gene in 595 unrelated apparently healthy individuals from nine Italian regions and in 133 patients with coronary artery disease. Our data confirm that the T833C mutation cosegregates in cis with the 844ins68 in all carriers of the insertion. Furthermore, no statistical difference was found in the insertion variant allele frequency between controls and coronary artery disease patients. Our study indicates a microheterogeneity in the distribution of the 844ins68 in the Italian population.