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.

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.

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.

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.

Fibrinogen and factor VIIag in healthy adolescents: the Floren-teen (Florence teenager) Study.

At least five studies based on more than twenty thousand healthy subjects indicated that fibrinogen is an independent risk factor for cardiovascular events; less clear-cut is the relation between factor VII and risk for arterial thrombotic disorders, which was demonstrated in two of the three studies investigating this association. However, no study has investigated the behaviour of fibrinogen and factor VII in an adolescent population. In a study of Preventive Medicine and Education Program, fibrinogen (clotting method) and factor VIIag (ELISA), in addition to other metabolic parameters, life-style and familial history, were investigated in 451 students (313 females and 138 males, age 15-17 years) from two high schools of Florence. Fibrinogen levels were significantly higher in women than in men, whereas factor VIIag levels did not significantly differ. Both fibrinogen and factor VIIag significantly correlated with total cholesterol (p < 0.05) while only fibrinogen correlated with body mass index (p < 0.01). Factor VIIag was significantly correlated with systolic blood pressure (p < 0.001). This study provides information on coagulation risk factors in a population of adolescents which may be of importance in planning coronary heart disease prevention programs.

Prevalence of factor V Leiden mutation in non-European populations.

A difference in the prevalence of venous thromboembolism (TE) in major human groups has been described and an uneven distribution of FV Leiden mutation over the world has recently been reported. We investigated FV Leiden mutation in 584 apparently healthy subjects mostly from populations different from those previously investigated: 170 Europeans (Spanish, Italians), 101 sub-saharan Africans (Fon, Bariba, Berba, Dendi), 115 Asians (Indonesians, Chinese, Tharus), 57 Amerindians (Cayapa), 84 Afroamericans (Rio Cayapa, Viche), and 57 Ethiopians (Amhara, Oromo). The mutation was detected in only 1/115 Asian (Tharu) and in 5/170 Europeans (4 Italians, 1 Spanish). These data confirm that in non-Europeans the prevalence of FV mutation is at least 7 times lower than in Europeans and provide indirect evidence of a low prevalence not only of the FV Leiden gene but also of other genes leading to more severe thrombophilia. Finally, findings from the literature together with those pertaining to this study clearly show a marked heterogeneity among Europeans.

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.

Cytokine gene expression in human LPS- and IFNgamma-stimulated mononuclear cells is inhibited by heparin.

In addition to its well-understood anticoagulant activity, heparin is known to modulate a variety of biological functions including immunologic responses. In order to investigate whether heparin influences the humoral immunity by interacting with cellular elements and affecting gene expression in blood circulating cells. we studied the effect of heparin on IL-1beta, IL-6 and TNFalpha mRNAs in human lipopolysaccharide-(LPS)- or interferon-gamma(IFN-gamma)-stimulated mononuclear cells. The study of mRNA was carried out by an initial PCR screening followed by a Northern blot quantitative analysis. Heparin (0.5 U/ml) turned out to inhibit all three cytokine gene expressions. The mRNA decrease was 37 +/- 6% for IL-1beta, 53 +/- 3% for IL-6 and 47 +/- 4% for TNFalpha with LPS stimulus. No differences could be observed in the inhibitory effect of heparin on IFNgamma-stimulated cells. This effect of heparin was confirmed in a subset of experiments performed on purified monocytes. These results suggest an important immunosuppressive effect of heparin on cell-mediated immune responses.

The high prevalence of thermolabile 5-10 methylenetetrahydrofolate reductase (MTHFR) in Italians is not associated to an increased risk for coronary artery disease (CAD).

Mild hyperhomocysteinemia was found to be related to venous thrombosis, cerebrovascular and coronary artery disease (CAD). Some recent studies suggested that a mutation in the gene encoding for 5-10 methylenetetrahydrofolate reductase (MTHFR), due to a transition C-->T at nucleotide 677, is a genetic risk factor for vascular disease. However, several further studies could not confirm this association. We investigated 84 patients with CAD who underwent percutaneous transluminal coronary angioplasty (PTCA) and 106 healthy subjects. The prevalence of the mutated homozygous genotype was much higher than in other Italian populations, Europeans or other major human groups, but no excess of the Val/Val homozygotes was found in patients (28.5%) with respect to healthy subjects (30.2%). Mutated homozygous MTHFR genotype (+/+) was not found to be related to the clinical manifestations of CAD, to the prevalence of the common risk factors and to the rate of restenosis. In conclusion, thermolabile MTHFR does not appear to be associated "per se" with the risk for CAD or for restenosis after PTCA. The high frequency of the +/+ genotype in our Italian population (from Tuscany) confirms a wide macroheterogeneity and suggests a microheterogeneity in the genotype frequencies of the different ethnic populations.

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.

Lupus anticoagulant and monocyte procoagulant activity in polyabortive women.

Monocyte stimulation may be induced by various agents. Monocytes generate procoagulant activity (PCA) in response to stimulation; they widely interact with the hemostatic system and participate in thrombin formation. Extensive placental thrombotic infarction has been implicated in fetal death in polyabortive patients with lupus anticoagulant (LA). We investigated 38 polyabortive women: 17 LA negative (LA-) and 18 LA positive (LA+). We compared the results with 25 clinically normal women. After four hours of incubation, the mean value of monocyte PCA in the LA+ women was significantly higher than in either the LA- or the control group (p < 0.0001). The monocyte PCA was out of the range of the controls in 9 of the 18 LA+ women. No correlation was observed between the levels of LA and monocyte PCA (r = 0.02; p = 0.94). No differences were found in monocyte PCA increase when induced by LA-, LA+ or control plasma; in all cases the increase was about five-six fold. Our results indicate that an increased monocyte PCA is present in some LA+ polyabortive women, thus suggesting that monocyte activation might be involved in the formation of thrombotic placental infarction and the consequent fetal loss in some patients. It might also suggest that these patients, in particular, could benefit from corticosteroid treatment, which is known to inhibit the formation of monocyte PCA.

Euglobulin lysis time in fresh and stored samples.

Euglobulin lysis time is a global test for the study of fibrinolysis. The aim of this study was to evaluate the influence of storage of plasma and euglobulin precipitates on euglobulin lysis time, by testing samples stored in different conditions. In 20 healthy subjects, euglobulin lysis time was measured by (1) euglobulin precipitates prepared within 90 minutes from blood withdrawal (reference euglobulin lysis time); (2) euglobulin precipitates obtained from platelet-poor plasma stored for 24 hours at either -80 degrees C or at -20 degrees C; (3) euglobulin precipitates frozen for 24 hours at either -80 degrees C or at -20 degrees C; (4) euglobulin precipitates dissolved in Owren's buffer and frozen for 24 hours at either -80 degrees C or at -20 degrees C. Euglobulin lysis time measured on euglobulin precipitates dissolved in Owren's buffer and stored at -20 degrees C and at -80 degrees C, and euglobulin lysis time measured on platelet-poor plasma stored at -20 degrees C were significantly longer than the reference euglobulin lysis time (at least P < .05). On the contrary, no changes were observed in euglobulin lysis time measured on platelet-poor plasma stored at -80 degrees C, and on euglobulin precipitates undissolved and stored at -20 degrees C and at -80 degrees C versus reference euglobulin lysis time. The pattern was similar in samples obtained both before and after venous occlusion. These data indicate that the freezing of samples of platelet-poor plasma or euglobulin precipitates at -80 degrees C and of euglobulin precipitates at -20 degrees C makes the simultaneous determination of a large number of samples collected at different times the previous day possible.

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.

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.

Cyclooxygenase and lipoxygenase metabolite generation in nasal polyps.

A role of prostaglandins (PGs) and leukotrienes (LTs) in the pathogenesis of nasal polyps has been recently suggested. Cyclooxygenase (CO) products (thromboxane B2, PGE2 and 6-keto PGF1 alpha) and lipoxygenase (LO) products (LTB4 and LTC4) were investigated by radioimmunoassay in polyps, hypertrophic turbinates and nasal mucosa from 14 patients with non-allergic (n = 6), allergic chronic rhinitis (n = 6) and aspirin-sensitive asthma (ASA) (n = 2), who underwent polypectomy. In all tissues CO metabolite levels were found higher than LO products (P < 0.01). Nasal polyps showed a significantly lower (P < 0.05) arachidonic acid (AA) metabolism in comparison to nasal mucosa. In polyps of allergic patients significantly higher LTB4 levels (P < 0.001) and a tendency to produce higher amounts of CO products in comparison to non-allergic subjects were observed, whereas in turbinates of non-allergic patients LT levels were significantly higher in comparison to those of allergic ones (P < 0.01). In ASA patients a decreased CO/LO ratio was found supporting the hypothesis of an imbalance of AA metabolism in this syndrome. These findings seem to indicate that the occurrence of nasal polyps may represent the result of different chronic inflammatory stimuli, regulated in part by AA metabolites.

Platelet activation and platelet lipid composition in pulmonary cancer.

In order to investigate the possible mechanisms underlying platelet functional changes in patients affected by neoplasms, platelet lipid composition, plasma beta-thromboglobulin (Beta-TG) and serum thromboxane B2 (TXB2) were investigated in 16 male patients affected by pulmonary carcinoma and in 16 comparable control subjects. In patients high levels of plasma Beta-TG (67 +/- 9 versus controls 14 +/- 4 ng/ml, p < 0.001) and serum TXB2 (434 +/- 56 versus 223 +/- 48 ng/ml, p < 0.001) were observed. Also platelet lipid composition was found altered in patients with respect to controls (lower percent levels in n-3 fatty acids and in linoleic acid esterified in the main platelet phospholipid fractions: at least p < 0.05). These results indicate that in vivo platelet activation is detectable in neoplastic patients and it is associated with alterations in platelet lipid composition. In the light of the important role played by membrane lipids in platelet functions related to thrombosis and haemostasis we conclude that platelet lipid changes could cooperate in platelet activation and increased thrombotic risk so frequently observed in neoplastic disease.

n-3 PUFA supplementation, monocyte PCA expression and interleukin-6 production.

n-3 polyunsaturated fatty acids (PUFA) can affect several monocyte functions and the biochemistry of blood cells, thus possibly influencing the initiation of thrombosis, inflammatory disease and atherosclerosis. In this study, we have investigated the effect of dietary supplementation with n-3 PUFA ethyl esters on procoagulant activity (PCA) and interleukin-6 (IL-6) production by human mononuclear cells. Nine healthy volunteers received 4 g/d of n-3 PUFA ethyl esters (4 x 1 g capsules with at least 85% eicosapentaenoic + docosahexaenoic acid ethyl esters) for 18 weeks. Before and at the end of the treatment, mononuclear cells were obtained from peripheral citrated blood by Ficoll-Hypaque density gradient centrifugation. Cellular suspensions (10(7) cells/ml) were incubated at 37 degrees C for 4 h in the absence and presence of lipopolysaccharide (10 micrograms/ml); PCA was determined by one-stage clotting assay and IL-6 concentrations were assayed in supernatants by specific ELISA. After 18-week treatment, both unstimulated and stimulated monocyte PCA were significantly reduced by 66% and 63%, respectively (P < 0.01). Similarly, a significant inhibitory effect by n-3 PUFA treatment on basal and LPS-stimulated IL-6 monocyte production was observed (50% and 46%, respectively, P < 0.05). These data indicate that 18-week n-3 PUFA supplementation may influence monocyte activities, which play a specific role in atherosclerosis and its thrombotic complications.

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.

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.

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.