Restriction of mast cell proliferation through hyaluronan synthesis by co-cultured fibroblasts.

Appropriate culture models for tissue mast cells are required to determine how they are involved in regulation of local immune responses. We previously established a culture model for cutaneous mast cells, in which bone marrow-derived immature mast cells were co-cultured with Swiss 3T3 fibroblasts in the presence of stem cell factor. In this study, we focused on the roles of hyaluronan, which is produced by the feeder fibroblasts and forms the extracellular matrix during the co-culture period. Hyaluronan synthesis was found to be mediated by hyaluronan synthase 2 (HAS2) expressed in Swiss 3T3 cells. A decreases in the amount of hyaluronan, which was achieved by retroviral expression of short hairpin RNA for Has2 or by addition of hyaluronidase, significantly enhanced the proliferation of the cultured mast cells without any obvious effects on their maturation. Although we previously demonstrated that CD44 is required for proliferation of cutaneous mast cells, the deficiency of hyaluronan did not affect the proliferation of the cultured mast cells that lack CD44. These findings suggest that the extracellular matrix containing hyaluronan may have a potential to restrict proliferation of cutaneous mast cells in a CD44-independent manner.

Serum soluble lectin-like oxidized low-density lipoprotein receptor-1 correlates with oxidative stress markers in stable coronary artery disease.

BACKGROUND: Although serum soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) is reported to be associated with acute coronary syndrome (ACS), its correlation with oxidative stress markers has not been elucidated. We therefore investigated the association of serum sLOX-1 with the severity of CAD, and serum biomarkers for oxidative stress and inflammation, as well as extracellular superoxide dismutase (EC-SOD), which is protective against oxidative stress in the vascular wall. METHODS AND RESULTS: Ninety-four patients with stable CAD were enrolled in this study. Serum sLOX-1, serum high-sensitivity C-reactive protein (hs-CRP), urinary 8-isoprostane, plasma BNP and serum lipid levels were measured. We also measured EC-SOD at baseline and post-heparin injection. Heparin-released EC-SOD (DeltaEC-SOD) was calculated as the difference between these two values. No significant correlation was found between log (sLOX-1) and log (basal EC-SOD) (p=0.096), log (hs-CRP) (p=0.108), or log (BNP) (p=0.908) levels, log (sLOX-1) had a significant correlation with DeltaEC-SOD (r=-0.325, p=0.0014) levels and urinary 8-isoprostane levels (r=0.243, p=0.020). In the multivariable analysis, DeltaEC-SOD (p=0.0177) and 8-isoprostane (p=0.0318) were independent predictors for log (sLOX-1). CONCLUSION: Serum sLOX-1 levels were positively correlated with urinary 8-isoprostane levels and inversely correlated with EC-SOD levels. These results thus suggest that increased serum sLOX-1 levels may reflect enhanced oxidative stress in vascular walls.

Derivatives of reactive oxygen metabolites correlates with high-sensitivity C-reactive protein.

AIM: High-sensitivity C-reactive protein (hsCRP) is a predictor of cardiovascular events. Although oxidative stress may also be related to cardiovascular disease, there are few studies comparing the two. We therefore examined the association of hsCRP, serum lipids, and derivatives of reactive oxygen metabolites (D-ROMs) in coronary artery disease. METHODS: We measured the levels of serum lipids, hsCRP, plasma brain natriuretic peptides (BNP) and D-ROMs in 131 consecutive patients undergoing cardiac catheterization. We divided these subjects into three groups according to their levels of hsCRP. RESULTS: In group C (hsCRP>3.0 mg/L), mean levels of serum D-ROMs were significantly higher than in groups A (hsCRP<1.0 mg/L) and B (hsCRP 1.0 to 3.0 mg/L). Serum levels of D-ROMs and log (hsCRP) correlated in the total population (r=0.479, p<0.0001), and D-ROMs, HDL-C, LDL-C and log-transformed plasma BNP were independent predictors of hsCRP (p<0.0001). CONCLUSION: We concluded that oxidative stress increases in patients at high risk for cardiovascular events based on their hsCRP.

Intracoronary administration of isosorbide dinitrate induced severely slow flow and transient ST-segment elevation.

Nitroglycerin is one of the most widely used drugs in the treatment of angina. However, nitroglycerin fails to relieve angina in patients with syndrome X who have microvessel dysfunction. Microvessel function is impaired in several diseases. In this article, the authors report that despite normal coronary angiograms at control, intracoronary administration of isosorbide dinitrate induced severe coronary slow flow and transient ST-segment elevation with mild chest pain in a patient with congestive heart failure. The authors speculated that functional stenosis and a delay in the dilatation of microvessels less than 100 microm in diameter because of their dysfunction resulted in a severely slow flow after intracoronary administration of isosorbide dinitrate.

Gene transfer of extracellular superoxide dismutase ameliorates pulmonary hypertension in rats.

RATIONALE: Pulmonary hypertension (PH) is a life-threatening disease, characterized by vascular remodeling and vasoconstriction. Evidence suggests that oxidative stress may contribute to the pathogenesis and/or development of PH. OBJECTIVES: In the present study, we examined whether intratracheal gene transfer of human extracellular superoxide dismutase (EC-SOD) could ameliorate monocrotaline (MCT)-induced PH in rats. METHODS: MCT-injected rats were intratracheally administered vehicle (MCT group) or an adenovirus encoding beta-galactosidase (Adbetagal group) or human EC-SOD (AdEC-SOD group). MEASUREMENTS AND MAIN RESULTS: After intratracheal gene transfer, EC-SOD was successfully expressed in lung tissue, bronchoalveolar lavage fluid, and plasma. Twenty-eight days after MCT injection, right ventricular systolic pressure and the weight ratio of the right ventricle to the left ventricle plus septum were significantly lower in the AdEC-SOD group (42.50 +/- 1.46 mm Hg and 0.453 +/- 0.029, respectively) than in the MCT group (59.89 +/- 1.61 mm Hg and 0.636 +/- 0.022, respectively) or the Adbetagal group (61.50 +/- 2.61 mm Hg and 0.653 +/- 0.038, respectively). Moreover, vascular remodeling and proliferation of vascular smooth muscle cells in pulmonary arteries were markedly suppressed in the AdEC-SOD group. Importantly, 8-isoprostane in lung tissue was also significantly reduced in the AdEC-SOD group. CONCLUSIONS: EC-SOD overexpression to the lung ameliorated MCT-induced PH in rats. We suggest that EC-SOD may act as an antioxidant in PH and that increased oxidative stress may be important in the pathogenesis of MCT-induced PH.

Angiotensin receptor blocker improves coronary flow velocity reserve in hypertensive patients: comparison with calcium channel blocker.

Large-scale clinical studies have indicated that angiotensin receptor blockers (ARBs) have beneficial effects against cardiovascular diseases. We designed this study to compare the effects of an ARB and a calcium channel blocker (CCB) on coronary flow velocity reserve (CFVR), a predictor of cardiovascular events, as estimated using transthoracic Doppler echocardiography. Sixteen hypertensive patients (63.1+/-9.6 years old; 10 males) were randomly allocated in a double-blind fashion to valsartan (n=8, 40-80 mg/day) or nifedipine (n=8, 20-40 mg/day) groups. Age- and gender-matched subjects without hypertension were enrolled as a control group (n=12). CFVR was calculated by dividing the adenosine triphosphate-induced hyperemic flow velocity by the basal flow velocity in the left anterior descending coronary artery. Baseline characteristics and reduction in systolic and diastolic blood pressure after 6 months were similar in both groups. CFVR in the valsartan group increased from 2.34+/-0.38 to 3.10+/-0.84 at 2 months (p<0.05), and to 3.04+/-1.09 at 6 months (p<0.01). Both values became comparable to that in the control group (2.81+/-0.60). CFVR in the valsartan group was significantly higher (p<0.001) than that in the nifedipine group, which was little changed at 6 months. This discrepancy was derived from the significant increase of hyperemic velocity in the valsartan group, from 36.6+/-17.3 cm/s to 41.1+/-12.7 cm/s at 2 months, and to 48.1+/-20.2 cm/s at 6 months. We concluded that the ARB valsartan not only reduced high blood pressure but improved CFVR in hypertensive patients. However, these effects were not seen with the CCB nifedipine.

Decreased plasma extracellular superoxide dismutase level in patients with vasospastic angina.

OBJECTIVE: Extracellular superoxide dismutase (EC-SOD) is the major extracellular scavenger of superoxides, and one of the main regulators of nitric oxide bioactivity in vessel walls. Here, we examined whether plasma EC-SOD level was associated with vasospastic angina (VSA), and if it was a risk factor for VSA. METHODS AND RESULTS: We assigned 105 patients with normal or mildly stenotic coronary arteries into either a VSA (n=58) or chest pain syndrome (CPS) (n=47) groups. Plasma EC-SOD and other biochemical variables were measured, and major coronary risk factors were assessed. Results showed that apart from smoking status there were no significant differences in patient characteristics and biochemical variables between the two groups. In the VSA group, prevalence of smoking was significantly higher (53% versus 26%, p=0.0055), and plasma EC-SOD level was significantly lower (68.9+/-18.5 ng/ml versus 83.8+/-25.9 ng/ml; p=0.0009). Not only smoking (OR 2.742, 95% CI 1.032-7.287, p=0.0431) but also plasma EC-SOD (OR 0.971, 95% CI 0.949-0.993, p=0.0102) was an independent risk factor for VSA. CONCLUSIONS: In patients with VSA, plasma EC-SOD level was substantially reduced. Furthermore, plasma EC-SOD level followed by cigarette smoking was the most predictive risk factor for coronary spasms.

Detection of patency of internal mammary artery grafts to the left anterior descending artery by transthoracic Doppler echocardiography.

BACKGROUND: To determine whether a coronary artery bypass graft (CABG) is patent, we examined the flow of the left internal mammary artery (LIMA) to the left anterior descending artery (LAD) by transthoracic Doppler echocardiography (TTDE). PATIENTS AND METHODS: Eighty-seven patients with CABG (LIMA to distal LAD) were enrolled in the study. The flows from each subject were analyzed by three criteria: mosaic flow at the anastomosis site, distal anterograde flow (ante flow), and proximal retrograde flow (retro flow). RESULTS: On angiography, 79 grafts were patent and eight were not. TTDE study of 79 patent grafts demonstrated mosaic, ante, and retro flow in 63 (79.7%), 74 (93.7%), and 35 grafts (49.4%), respectively. The averaged diastolic peak velocity of ante flow was 26.3 +/- 11.0 cm/sec, significantly higher than that (4.8 +/- 7.1 cm/sec, P < or = 0.0001) in eight patients without patent grafts. These eight patients had no mosaic or retro flow and only three had ante flow. The accuracies to predict patency were 81.6%, 90.8%, and 49.4% for mosaic, ante, and retro flows, respectively. CONCLUSIONS: The existence of mosaic, retro, or sufficient ante flows strongly indicated the patency of LIMA to the LAD. When symptoms are possible to be derived from the occlusion of CABG to LAD, TTDE is a promising method to examine whether a LIMA to LAD bypass is patent.

Low-density lipoprotein apheresis therapy with a direct hemoperfusion column: a Japanese multicenter clinical trial.

Low-density lipoprotein (LDL) apheresis has been applied to patients with familial hypercholesterolemia (FH) with coronary artery disease (CAD). To examine the efficacy and safety of a new type of LDL adsorption column (KLD01, Kaneka, Osaka, Japan), which deals with whole blood without separating plasma, the new system was evaluated in a multicenter trial. The present study included 33 FH patients with CAD (24 males, 9 females, 57 +/- 13 years) who were treated five times with a mean interval of 2.12 +/- 0.60 weeks between treatments. We studied the removal efficacies for serum LDL cholesterol, Lipoprotein(a) (Lp(a)) and triglyceride, the times for the preparation of the system and for treatment, symptoms, and the biochemical data. The scheduled treatments were completed by 31 patients. Serum levels of LDL cholesterol, Lp(a) and triglycerides were all significantly reduced with KLD01; 61.5 +/- 6.2%, 72.4 +/- 5.9% and 69.5 +/- 9.7%, respectively. The times for both setting up the column system (26 +/- 7 min) and treatment (138 +/- 20 min) were shorter with KLD01 than conventional methods. Adverse reactions occurred in eight cases (17 episodes), but the patients fully recovered immediately after each apheresis therapy session. We conclude that the new type of LDL adsorption column, one that deals with whole blood, is a promising apheresis therapy for FH patients in view of its efficacy, reduced time for treatment, and safety.

Heparin-released extracellular superoxide dismutase is reduced in patients with coronary artery atherosclerosis.

OBJECTIVES: We studied whether the amount of heparin-released extracellular superoxide dismutase (EC-SOD), which is an antioxidative enzyme, is associated with coronary artery disease (CAD). METHODS AND RESULTS: EC-SOD was measured in plasma at basal and at post-heparin injection in 315 patients. Heparin-released EC-SOD was calculated as the difference between the two values. After exclusion of a mutant EC-SOD group (n = 27:8.6%), 288 patients were divided into three groups by angiographic findings; those with normal coronary (the normal group; n = 63), those with atherosclerosis without significant stenosis (the mild atherosclerosis group; n = 36), and those with significant stenosis (the atherosclerosis group; n = 189). Although the basal values were similar among the three groups, heparin-released EC-SOD levels were significantly lower in the atherosclerosis group (131.0 +/- 42.8 ng/ml, p = 0.0003) than in the normal group (156.9 +/- 66.2 ng/ml). Moreover, logistic analysis revealed that heparin-released EC-SOD independently contributed to CAD. The coronary score showed a significant correlation with heparin-released EC-SOD. As for factors affecting the level of heparin-released EC-SOD, the level of high-density lipoprotein cholesterol and age showed a positive correlation. CONCLUSIONS: The results suggest that heparin-released EC-SOD is significantly reduced in CAD and that the tissue-bound location of this enzyme might be important for antioxidative function.

Cross-over trial of intensive monotherapy with atorvastatin and combined therapy with atorvastatin and colestimide for Japanese familial hypercholesterolemia.

BACKGROUND: In familial hypercholesterolemia (FH), low-density lipoprotein-cholesterol (LDL-C)-lowering therapy is important to avoid predisposition to coronary artery disease. This study investigated the advantages of combined therapy with atorvastatin and colestimide vs intensive monotherapy with atorvastatin. METHODS AND RESULTS: The trial used a randomized cross-over design consisting of 2 16-week periods of open-label drug therapy. Among the 24 initial patients, 17 heterozygous FH patients (age: 54.1 years; 5 males) were enrolled after 20 mg/day atorvastatin failed to achieve their target level. The patients received 20 mg/day atorvastatin and 3 g/day colestimide or 40 mg/day atorvastatin. Fifteen patients completed the trial and their LDL-C reduced from 5.07 +/- 1.10 mmol/L to 3.76 +/- 0.90 mmol/L with the combined therapy and to 3.81 +/- 0.50 mmol/L with the intensive monotherapy. Although the 2 therapies showed comparable mean effects for decreasing LDL-C, similar adverse reaction and cost, each therapy was predominantly more effective in some patients than in others. The triglyceride and high-density lipoprotein cholesterol levels were similar in both therapies. CONCLUSIONS: To achieve the therapeutic target of LDL-C level for refractory FH, the LDL-C-lowering therapy selected can be either intensive monotherapy or combined therapy as the next to standard statin therapy.

Bosentan improved syncope in a hemodialysis patient with pulmonary hypertension and mild aortic stenosis.

Pulmonary arterial hypertension (PAH), caused by collagen diseases, Eisenmenger syndrome or of idiopathic etiology, generally has a poor prognosis. Recently, bosentan, a dual endothelin receptor antagonist, has become available for treating PAH. This report describes a bosentan-effective case of combined PAH, hemodialysis and mild aortic stenosis. A 71-year-old woman on hemodialysis was referred to our hospital because of repetitive syncope. Although neurological examinations revealed no etiological diseases, echocardiography and cardiac catheterization showed PAH and mild aortic valve stenosis. Bosentan abolished syncope with improvement of hemodynamic parameters. This report suggests bosentan was clinically useful in a hemodialysis patient with pulmonary hypertension and mild aortic valve stenosis.

Experimental hyperhomocysteinemia impairs coronary flow velocity reserve.

BACKGROUND: Hyperhomocysteinemia has been identified as an independent risk factor for coronary artery disease. One mechanism is considered to be deteriorated endothelial function that is recovered by vitamin C. However, its direct action on coronary circulation has yet to be examined. This study was designed to test the hypothesis that experimental acute hyperhomocysteinemia would impair coronary flow velocity reserve (CFR) by increasing oxidative stress. METHODS: Eleven healthy male volunteers (aged 23.3+/-0.9 years) were enrolled. CFR induced by intravenous 5'-adenosine triphosphate infusion was measured by transthoracic-Doppler echocardiography. Measurements were taken before and 4 h after administration of a placebo, oral methionine (L-methionine 0.1 g/kg) or oral methionine plus vitamin C (2 g) on 3 separate days. RESULTS: The baseline average diastolic peak velocity (APV) was similar in all 3 groups. In the methionine group, plasma homocysteine increased (12.9+/-7.0 to 32.1+/-9.4 nmol/ml, p<0.0001), while APV under hyperemic conditions (APV-hyp) and CFR significantly decreased (87.2+/-11.4 cm/sec and 4.02+/-0.70 to 73.2+/-10.2 cm/sec and 3.35+/-0.52, p=0.0022 and 0.0030, respectively). Moreover, there was a significant inverse correlation between the plasma homocysteine and CFR (r=-0.620, p=0.0021). However, upon simultaneous administration of vitamin C, APV-hyp and CVR did not decrease despite an elevation in plasma homocysteine. CONCLUSIONS: Experimentally induced acute hyperhomocysteinemia significantly decreased CFR, and this decrease was significantly reversed by vitamin C administration. Oxidative stress is suggested to play a major role in the deleterious effects of homocysteine on the coronary microcirculation.

Prolonged survival in a female with untreated tetralogy of Fallot.

It has been reported that most patients with untreated tetralogy of Fallot (TOF) die by the time they reach adulthood. We report the case of a 72-year-old female diagnosed by echocardiography and cardiac cathetherization as having TOF and diagnosed at birth with a ventricular septal defect (VSD). During childhood, she was very thin and lacking in physical strength. On first consultation at our hospital, she was suffering from mild dyspnea, classified as NYHA functional class III, and her fingers were clubbed and cyanotic. Her PaO2 was 48.0 mmHg under room air, and hypoxia was recognized. An echocardiography and cardiac cathetherization showed a VSD, hypertrophy of the right ventricle, over-riding of the aorta and stenosis of the right ventricular outflow tract with a pressure gradient of 84 mmHg. There was a bidirectional shunt with 24% flow from the left to right and 43% from the right to left ventricle. Her Qp/Qs was 0.75. Surgical treatment was recommended. However, the patient refused, because her symptoms were alleviated with home oxygen therapy. This report shows the prolonged survival of this 72-year-old female with untreated TOF.

Extracellular superoxide dismutase overexpression reduces cuff-induced arterial neointimal formation.

The mechanisms of neointimal formation in cuff-injury models are still uncertain. To examine whether extracellular superoxide dismutase (EC-SOD) can reduce neointimal formation in a cuff-injury model, adenoviruses expressing EC-SOD (AxCAEC-SOD) or Escherichia coli beta-galactosidase (AxCALacZ) was injected between the cuff and the adventitia of rat femoral arteries. As a result, EC-SOD protein was effectively produced in the adventitia, as assessed by immunohistochemical staining. In comparison with cuff-treated control arteries and AxCALacZ-transfected arteries, neointimal formation was significantly reduced in AxCAEC-SOD-transfected arteries. Furthermore, proliferating smooth muscle cells in neointima and media were reduced by EC-SOD treatment. Similarly, augmented iNOS expression, apoptosis and collagen content in the vascular wall were also reduced by EC-SOD treatment. Reactive oxygen species (ROS) generation in tissue was reduced by EC-SOD expression, as assessed by dihydroethidium staining and coelenterazine chemiluminescence. These results suggest that ROS, especially superoxide anions at an adventitia, are responsible for neointimal formation in a cuff-injury model.

Oxidized low-density lipoprotein-induced apoptosis is attenuated by insulin-activated phosphatidylinositol 3-kinase/Akt through p38 mitogen-activated protein kinase.

1. The aim of the present study was to investigate whether p38 mitogen-activated protein kinase (p38 MAPK) is involved in oxidized low-density lipoprotein (oxLDL)-induced apoptosis of human umbilical vein endothelial cells (HUVECs). We also sought to determine whether this apoptosis is regulated by the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. 2. Low-density lipoprotein was oxidized with CuSO4 and used as oxLDL. Using HUVEC, we determined whether LDL/oxLDL induces apoptosis by DNA fragmentation and the cell cycle distribution (SubG1 method). The mechanism and activation of p38 MAPK and Akt were determined by western blot analysis. 3. The results showed that oxLDL induced DNA fragmentation, whereas cell cycle distribution showed that it also significantly increased the rate of cell death compared with the LDL group. SB203580 significantly inhibited cell death induced by oxLDL, as did the administration of insulin. Western blot analysis showed the activation of p38 MAPK by oxLDL, but not with LDL. It was found that Akt was activated in the presence of insulin. In the presence of either SB203580 or insulin, activation of p38 MAPK was significantly inhibited compared with stimulation by oxLDL alone. However, application of both insulin and wortmannin resulted in no significant difference compared with HUVEC stimulated by oxLDL only. 4. The results showed that apoptosis in HUVEC can be induced by oxLDL and involves p38 MAPK. It was also demonstrated that insulin inhibited oxLDL-induced apoptosis and may inhibit the activation of p38 MAPK through the PI3K/Akt pathway.

Two cases of familial primary pulmonary hypertension.

Case 1, a 28-year-old woman (third daughter of Case 2) delivered her first child in September 2000, but leg edema and dyspnea on exertion appeared the following January. At the time of our first examination of the patient in May 2001, a chest X-ray showed cardiomegaly and pulmonary artery enlargement. Echocardiography demonstrated enlargement of the right ventricle and small left ventricular dimensions, and an electrocardiogram revealed right ventricle hypertrophy. After perfusion-ventilation lung scintigraphy and cardiac catheterization, she was diagnosed as having primary pulmonary hypertension (PPH). Although she was discharged with prescriptions for a diuretic, warfarin and beraprost sodium, she died of a pulmonary hypertensive crisis twenty days after readmission. Case 2, a 60-year-old woman(mother of Case 1) developed the same symptoms as those in Case 1, in May 2001, but recovered after medication. PPH is a rare disease and only a few familial cases are reported. In this family, the eldest daughter of Case 2 had also died of pulmonary hypertension ten years ago, several months after her first delivery. In contrast to the daughters, the mother's symptoms developed gradually.

Infective tricuspid valve endocarditis due to abscess of an endogenous arteriovenous fistula in a chronic hemodialysis patient.

Patients on chronic hemodialysis are at high risk for endocarditis due to prosthetic access devices. Right-sided endocarditis without any predisposing factors is rare in dialysis patients. A 76-year-old female, who had chronic renal failure had been treated by hemodialysis and had a permanent pacemaker implanted, was admitted to our hospital with a high fever and lumbago after abscess formation at an autogenous arteriovenous fistula for hemodialysis. Methicillin Resistant Staphylococcus Aureus was identified by blood culture examination. Echocardiography revealed vegetation attached to the tricuspid valve. Chest X-ray and perfusion lung scintigraphy showed pulmonary infarction, perhaps due to vegetation-derived emboli. Computed tomography also showed pyogenic spondylitis in L4 and L5. Repeated vascular punctures even of autogenous grafts expose dialysis patients to bacteremia and imply a higher risk of infectious endocarditis.

Successful thromboendarterectomy for severe chronic thromboembolic pulmonary hypertension caused by primary antiphospholipid syndrome.

Pulmonary hypertension is one of the lethal complications in the antiphospholipid syndrome due to chronic recurrence of embolism or thrombosis. We experienced a 19-year-old man suffering from severe chronic thromboembolic pulmonary hypertension (CTEPH) caused by primary antiphospholipid syndrome. According to the guideline, pulmonary thromboendarterectomy was decided on after combined therapy with warfarin, beraprost and oxygen inhalation had not been effective enough to improve severe CTEPH. By an operation, the mean pressure of the pulmonary artery was decreased from 50 mmHg to 16 mmHg, while his New York Heart Association (NYHA) functional class classification significantly improved from class III to class I. We concluded that pulmonary thromboendarterectomy could dramatically improve hemodynamic indices, NYHA functional status and quality of life in patients with CTEPH.

Hyperhomocysteinemia is associated with human coronary atherosclerosis through the reduction of the ratio of endothelium-bound to basal extracellular superoxide dismutase.

BACKGROUND: Homocysteine is involved in coronary atherosclerosis through oxidative stress, so the present study investigated the association between plasma concentrations of homocysteine and extracellular superoxide dismutase (EC-SOD) in coronary artery disease (CAD). METHODS AND RESULTS: The study group comprised 154 consecutive male patients with suspected CAD who had undergone angiography. Plasma concentrations of homocysteine and EC-SOD, which was determined before (basal) and after heparin therapy, were measured and the difference was designated as endothelium-bound EC-SOD. The EC-SOD ratio (endothelium-bound/basal EC-SOD) was also evaluated as an index of binding capacity. The plasma homocysteine concentration in the stenosis (+) group (n=97, 12.0+/-4.6 micromol/L) was significantly higher than that of the stenosis (-) group (n=57, 10.2+/-3.0 micromol/L, p=0.004). Plasma homocysteine correlated positively with the basal EC-SOD (r=0.377, p<0.001) and negatively with the EC-SOD ratio (r=-0.199, p=0.014). When the group was subdivided according to either homocysteine or the EC-SOD ratio, there were 2 groups with high homocysteine concentration and of these atherosclerosis was reduced in the group with a high EC-SOD ratio. CONCLUSIONS: In CAD patients, homocysteine is involved in the significant release of EC-SOD from the endothelium. Furthermore, the higher EC-SOD binding capacity, even at high concentrations of homocysteine, suggested that homocysteine-induced atherosclerosis was suppressed.