Frequency and predictors of bleeding complications associated with anti-coagulant therapy using dabigatran in Japanese patients with atrial fibrillation.

BACKGROUND: Few data exist regarding frequency and predictors of bleeding complications associated with anticoagulant therapy using dabigatran in Japanese patients with atrial fibrillation (AF). METHODS AND RESULTS: We retrospectively studied 184 patients with AF who were administered dabigatran from April 2011 to August 2012 in our institution. Twenty-eight patients (15%) developed some type of bleeding complication. In the Bleeding group, age, CHADS2 and HAS-BLED score were higher (75 vs. 71 years, p=0.067, 2.7 vs. 1.9, p=0.006 and 2.3 vs. 1.8, p=0.01, respectively), hemoglobin concentration was lower (13.1 vs. 13.7 g/dL, p=0.04), casual activated partial thromboplastin time (APTT) was longer (60.2 vs. 47.4 sec., p<0.0001) and frequency of aspirin use was higher (29 vs. 15%, p=0.09) than those in the Non-bleeding group. Multivariate regression analysis showed that casual APTT was an independent significant predictor of any type of bleeding complications (ß=0.431, p<0.0001). Moreover, casual APTT (ß=0.359, p=0.049), pre-existing anemia (ß=0.457, p=0.02) and aspirin use (ß=0.597, p=0.02) were significant predictors of major bleeding. ROC analysis showed that casual APTT exhibited 83.3% sensitivity and 72.5% specificity as predictors of major bleeding and its cut-off value was 54.7 sec. CONCLUSION: Casual APTT level can serve as a predictor of bleeding complications, while pre-existing anemia and aspirin use may be associated with major bleeding in patients with AF treated with dabigatran.

Elevation of urinary liver-type fatty acid-binding protein as predicting factor for occurrence of contrast-induced acute kidney injury and its reduction by hemodiafiltration with blood suction from right atrium.

Although contrast-induced acute kidney injury (CI-AKI) has a great impact on patients' prognosis, few data exist regarding predictors of CI-AKI in patients with severe renal dysfunction who have undergone contrast angiography. Therefore, we prospectively studied 25 patients with renal dysfunction, which was defined as the estimated glomerular filtration rate (eGFR) level <45 ml/min/1.73 m(2), undergoing coronary angiography (CAG) or percutaneous coronary intervention (PCI). We performed hemodiafiltration with blood suction from the right atrium (RA-HDF). The mean level of urinary liver-type fatty acid-binding protein (L-FABP) at baseline was significantly higher in the CI-AKI group than in the non-CI-AKI group (59.8 ± 45.6 vs 13.4 ± 11.9 µg/gCr, P = 0.0003). Multivariate regression analysis demonstrated that baseline urinary L-FABP was an independent significant predictor of CI-AKI (ß = 0.741, P = 0.013). Receiver-operating characteristic analysis showed that baseline urinary L-FABP exhibited 100 % sensitivity and 81.8 % specificity for predicting CI-AKI when the cutoff value was defined as 19.0 µg/gCr. Interestingly, the incidence of CI-AKI after CAG or PCI was reduced in the RA-HDF group in a comparison with 41 control patients (12 % vs 27 %) with eGFR level <45 ml/min/1.73 m(2) who underwent PCI before the introduction of RA-HDF. In conclusion, baseline L-FABP levels can be a predictor for occurrence of CI-AKI. We suggest that RA-HDF may prevent the development of CI-AKI in patients with severe renal dysfunction undergoing coronary procedures, although further large-scale prospective study is necessary to confirm our conclusions.

Association of seasonal variation in the prevalence of metabolic syndrome with insulin resistance.

The aim of this study was to examine the hypothesis that seasonal variation in the prevalence of metabolic syndrome (MetS) is associated with increased insulin resistance. Among 840 Japanese male workers who were evaluated using the homeostasis model assessment of insulin resistance (HOMA-IR) in June (summer) 2010, we prospectively studied a total of 758 subjects (40-65 years of age) who underwent an assessment in December (winter) 2010. MetS was defined according to the criteria proposed by the International Diabetes Federation (IDF) and the Japanese Society of Internal Medicine (JSIM). The median level of HOMA-IR in the study subjects was 0.84 (interquartile range: 0.60-1.19). The prevalence rates of IDF- and JSIM-MetS significantly increased from 12.4 and 9.6% in the summer to 16.6 and 13.3% in the winter, respectively (each P<0.05). Our data suggest that these increases are mainly due to increases in blood pressure (BP) and glucose during the winter assessment. The prevalence rates of IDF-MetS in the first, second, third and fourth quartiles of HOMA-IR were 1.1, 5.8, 14.3 and 29.1% in the summer and 3.1, 10.6, 21.9, and 31.3% in the winter, respectively. Similar results were obtained when using the JSIM criteria. In the third quartile, the frequency of elevated BP increased from 42.4% in the summer to 61.2% in the winter (P<0.05), and these values were mainly correlated with significant variations in IDF- and JSIM-MetS prevalence rates. This study demonstrates that seasonal variation in MetS prevalence is associated with mildly to moderately increased insulin resistance in middle-aged Japanese men.

Proposed cutoff level of waist circumference in Japanese men: evaluation by homeostasis model assessment of insulin resistance levels.

OBJECTIVE: The aim of this study is to propose the cutoff level of waist circumference (WC) on the basis of homeostasis model assessment of insulin resistance (HOMA-IR) levels in order to diagnose metabolic syndrome (MetS). METHODS: We examined a total of 798 non-diabetic men (40-65 years of age) by using a receiver operating characteristic (ROC) curve to determine the cutoff level that yielded the maximum sensitivity plus specificity. According to the criteria proposed by the International Diabetes Federation (IDF), and the Japanese Society of Internal Medicine (JSIM), subjects with ≥ 2 metabolic components other than abdominal obesity, were considered to have MetS. RESULTS: The overall prevalence rates of IDF- and JSIM-MetS were 17.4% (n=139) and 15.5% (n=124), respectively. The median levels of WC and HOMA-IR were 83.1 [interquartile range (IQR): 78.5-88.4] cm and 0.84 (IQR: 0.61-1.19), respectively. HOMA-IR was highly correlated with each metabolic parameter (each p<0.05), and in addition, multiple linear regression analysis of HOMA-IR (adjusted R2=0.459) showed that WC level was the strongest independent predictors of HOMA-IR level (F=141.1, p<0.05). According to ROC curve analysis, the cutoff level of HOMA-IR for predicting IDF- and JSIM-MetS was 0.92 for both (sensitivity: 79.9% and 78.2%, specificity: 64.9% and 63.6%). Based on the HOMA-IR level, the proposed WC cutoff level was 82.7 cm (sensitivity: 75.4%, specificity: 63.8%). CONCLUSION: This study suggests that WC level should be more strictly managed than current criteria, for preventing the development of MetS in non-diabetic middle-aged Japanese men.

Elevated depressive symptoms are associated with hypertriglyceridemia in Japanese male workers.

OBJECTIVE: The aim of this study was to determine whether elevated depressive symptoms are associated with metabolic syndrome and its components in the Japanese population. METHODS: Out of 1,386 male workers who underwent measurements of variables of metabolic syndrome components in their health checkup, 1,186 subjects (44.5 ± 9.6 years) completed the Zung self-rating depression scale (ZSDS) (response rate 85.6%). In this study, metabolic syndrome was defined according to the joint scientific statement proposed by 6 major organizations, including the International Diabetes Federation. RESULTS: The overall frequency of elevated depressive symptoms (ZSDS scores ≥40) was 42.1% (n=499). The incidence of metabolic syndrome was significantly higher in subjects with elevated depressive symptoms than in those without (13.2% vs. 8.9%, p<0.05). Of all the metabolic syndrome components, mean triglyceride levels were significantly higher in subjects with elevated depressive symptoms than in those without [124.7 (95% confidence interval (CI): 117.8-131.7) mg/dL vs. 111.5 (95% CI: 107.2-115.9) mg/dL, p<0.05]. Consequently, hypertriglyceridemia (28.9% vs. 21.0%, p<0.01) was the main component correlated with the between-group difference of metabolic syndrome incidence. In the logistic regression analysis after adjustment for potential confounders, the odds ratio of the total ZSDS scores for the diagnosis of hypertriglyceridemia was 1.52 (95% CI: 1.13-2.04; p<0.01), and the major depressive symptom was psychomotor agitation (odds ratio: 1.47; 95% CI: 1.10-1.94; p<0.01). CONCLUSION: This study showed that elevated depressive symptoms were associated with hypertriglyceridemia in Japanese male workers, which affected the clinical diagnosis of metabolic syndrome.

Spontaneous development of left ventricular hypertrophy and diastolic dysfunction in mice lacking all nitric oxide synthases.

BACKGROUND: The role of the nitric oxide synthase (NOS) system in cardiac architecture and function remains unknown. This point was addressed in mice that lack all 3 NOS genes. METHODS AND RESULTS: Morphological, echocardiographic, and hemodynamic analyses were performed in wild-type (WT), singly nNOS(-/-), iNOS(-/-), eNOS(-/-), and triply n/i/eNOS(-/-) mice. At 5 months of age, but not at 2 months of age, significant left ventricular (LV) hypertrophy was noted in n/i/eNOS(-/-) mice and to a lesser extent in eNOS(-/-) mice, but not in nNOS(-/-) or iNOS(-/-) mice, compared with WT mice. Importantly, significant LV diastolic dysfunction (as evaluated by echocardiographic E/A wave ratio and hemodynamic -dP/dt and Tau), with preserved LV systolic function (as assessed by echocardiographic fractional shortening and hemodynamic +dP/dt), was noted only in n/i/eNOS(-/-) mice, and this was associated with enhanced LV end-diastolic pressure and increased lung wet weight, all of which are characteristics consistent with diastolic heart failure in humans. Finally, long-term oral treatment with an angiotensin II type 1 (AT(1)) receptor blocker, olmesartan, significantly prevented all these abnormalities of n/i/eNOS(-/-) mice. CONCLUSIONS: These results provide the first direct evidence that the complete disruption of all NOSs results in LV hypertrophy and diastolic dysfunction in mice in vivo through the AT(1) receptor pathway, demonstrating a pivotal role of the endogenous NOS system in maintaining cardiac homeostasis.

A direct measurement for LDL-cholesterol increases hypercholesterolemia prevalence: comparison with Friedewald calculation.

Direct measurement by homogenous assays has recently been applied to measuring low-density lipoprotein-cholesterol (LDL-C) and has replaced the Friedewald calculation in Japan, but it remains unclear how direct measurement compares with the Friedewald calculation in evaluating hypercholesterolemia. The aim of this study was to determine the effect of the two methods on the diagnosis of hypercholesterolemia. In a total of 1655 workers from our institution (1451 men, 43.6 +/- 10.2 years; 204 women, 38.3 +/- 10.4 years), we investigated the LDL-C levels by the direct and Friedewald methods. In this study, we excluded workers whose triglyceride levels exceeded 400 mg/dl (n=18). Direct LDL-C showed a significantly positive correlation with Friedewald LDL-C (R2 = 0.975, P < 0.0001). On the other hand, the mean direct LDL-C was 5.9 mg/dl higher than the mean Friedewald LDL-C (126.7 +/- 30.6 mg/dl vs. 120.8 +/- 30.5 mg/dl, P < 0.0001), and direct LDL-C was higher in 89.1% of the study population. The frequency of study subjects diagnosed with hypercholesterolemia, defined as LDL-C > or =140 mg/dl, was significantly higher in the direct measurement than in the Friedewald calculation (31.7% vs. 25.1%, P < 0.0001). In conclusion, we demonstrated that the direct measurement showed a higher rate of hypercholesterolemia prevalence than the Friedewald calculation indicated. This result suggests that we have to give careful consideration to the method for measuring LDL-C in the clinical diagnosis and management decisions of hypercholesterolemia.

Severe dyslipidaemia, atherosclerosis, and sudden cardiac death in mice lacking all NO synthases fed a high-fat diet.

AIMS: The precise role of the nitric oxide synthase (NOS) system in lipid metabolism remains to be elucidated. We addressed this point in mice that we have recently developed and that lack all three NOS isoforms. METHODS AND RESULTS: Wild-type (WT), singly, doubly, and triply NOS(-/-) mice were fed either a regular or high-cholesterol diet for 3-5 months. The high-cholesterol diet significantly increased serum low-density lipoprotein (LDL) cholesterol levels in all the genotypes when compared with the regular diet. Importantly, when compared with the WT genotype, the serum LDL cholesterol levels in the high-cholesterol diet were significantly and markedly elevated only in the triply NOS(-/-) genotype, but not in any singly or doubly NOS(-/-) genotypes, and this was associated with remarkable atherosclerosis and sudden cardiac death, which occurred mainly in the 4-5 months after the high-cholesterol diet. Finally, hepatic LDL receptor expression was markedly reduced only in the triply NOS(-/-) genotype, accounting for the diet-induced dyslipidaemia in the genotype. CONCLUSION: These results provide the first direct evidence that complete disruption of all NOS genes causes severe dyslipidaemia, atherosclerosis, and sudden cardiac death in response to a high-fat diet in mice in vivo through the down-regulation of the hepatic LDL receptor, demonstrating the critical role of the whole endogenous NOS system in maintaining lipid homeostasis.

Spontaneous myocardial infarction in mice lacking all nitric oxide synthase isoforms.

BACKGROUND: The roles of nitric oxide (NO) in the cardiovascular system have been investigated extensively in pharmacological studies with NO synthase (NOS) inhibitors and in studies with NOS isoform-deficient mice. However, because of the nonspecificity of the NOS inhibitors and the compensatory interactions among NOS isoforms (nNOS, iNOS, and eNOS), the ultimate roles of endogenous NO derived from the entire NOS system are still poorly understood. In this study, we examined this point in mice deficient in all 3 NOS isoforms (triply n/i/eNOS(-/-) mice) that we have recently developed. METHODS AND RESULTS: The triply n/i/eNOS(-/-) mice, but not singly eNOS(-/-) mice, exhibited markedly reduced survival, possibly due to spontaneous myocardial infarction accompanied by severe coronary arteriosclerotic lesions. Furthermore, the triply n/i/eNOS(-/-) mice manifested phenotypes that resembled metabolic syndrome in humans, including visceral obesity, hypertension, hypertriglyceridemia, and impaired glucose tolerance. Importantly, activation of the renin-angiotensin system was noted in the triply n/i/eNOS(-/-) mice, and long-term oral treatment with an angiotensin II type 1 receptor blocker significantly suppressed coronary arteriosclerotic lesion formation and the occurrence of spontaneous myocardial infarction and improved the prognosis of those mice, along with ameliorating the metabolic abnormalities. CONCLUSIONS: These results provide the first direct evidence that genetic disruption of the whole NOS system causes spontaneous myocardial infarction associated with multiple cardiovascular risk factors of metabolic origin in mice in vivo through the angiotensin II type 1 receptor pathway, demonstrating the critical role of the endogenous NOS system in maintaining cardiovascular and metabolic homeostasis.

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.

Spontaneous myocardial infarction and nitric oxide synthase.

Myocardial infarction (MI) is caused by coronary atherosclerosis and/or arteriosclerosis. Because endothelial nitric oxide synthase (eNOS) exerts powerful anti-atherosclerotic/anti-arteriosclerotic effects, it is speculated that blockade of eNOS activity might result in MI. However, neither genetic disruption of eNOS nor pharmacologic inhibition of eNOS activity induces MI in animals. On the other hand, intriguingly, genetic disruption of all three nitric oxide synthase (NOS) isoforms (neuronal NOS, inducible NOS, and eNOS) spontaneously caused MI accompanied by multiple cardiovascular risk factors of metabolic origin in mice. This is the first in vivo demonstration showing that the defective NOS system is involved in the pathogenesis of spontaneous MI. Based on the evidence, this review summarizes our current knowledge of spontaneous MI and NOS.

[Development of genetically engineered mice lacking all three nitric oxide synthase isoforms].

The nitric oxide (NO) synthases (NOSs) system consists of three different isoforms, including neuronal (nNOS), inducible (iNOS), and endothelial NOSs (eNOS). The roles of NO in vivo have been extensively investigated in pharmacological studies with NOS inhibitors and in studies with mice lacking each NOS isoform. However, in the pharmacological studies, the specificity of NOS inhibitors continues to be an issue of debate, while in the studies with mice lacking each NOS isoform, compensatory mechanism by other NOSs appears to be involved. Thus, the ultimate roles of endogenous NO in our body still remain to be fully elucidated. To address this important issue, we have successfully developed mice in which all three NOS genes are completely disrupted. NOS expression and activities were totally absent in the triply n/i/eNOS(-/-) mice before and after treatment with lipopolysaccharide. While the triply n/i/eNOS(-/-) mice were viable, their survival and fertility rates were markedly reduced as compared with wild-type mice. The first noticeable phenotypes were polyuria, polydipsia, and renal unresponsiveness to vasopressin, characteristics consistent with nephrogenic diabetes insipidus. We subsequently observed that in those mice, arteriosclerosis is spontaneously developed with a clustering of cardiovascular risk factors. These results provide the first evidence that genetic disruption of all three NOSs causes a variety of cardiovascular diseases in mice in vivo, demonstrating the critical role of the endogenous NOSs system in maintaining cardiovascular homeostasis.

Histamine upregulates the expression of inducible nitric oxide synthase in human intimal smooth muscle cells via histamine H1 receptor and NF-kappaB signaling pathway.

OBJECTIVE: Histamine increases endothelial nitric oxide (NO) production as an endothelium-dependent vasodilator, which acts as a vasoconstrictor in atherosclerotic coronary arteries. To investigate the relation between histamine and NO production in intimal smooth muscle cells (SMCs), we studied the effect of histamine on inducible NO synthase (iNOS) expression in the SMCs. METHODS AND RESULTS: In cultured human intimal SMCs, histamine increased NO production, iNOS expression, and NF-kappaB nuclear translocation, which were inhibited by histamine H1 blocker and NF-kappaB inhibitor. Luciferase assay using -8.3 kb upstream of human iNOS promoter region and electrophoretic mobility shift assay suggested that a NF-kappaB motif located at -3922 to -3914 would be necessary for histamine-inducible promoter activity. In addition, H1 blocker, NF-kappaB inhibitor, and dominant negative IkappaB alpha or IkappaB kinase beta downregulated the histamine-induced iNOS promoter activity. In the human aorta, histamine content was estimated to be 310+/-66 pmol/mg protein in the atherosclerotic intima, while that was to be 43+/-22 pmol/mg protein in the media (P<0.001). CONCLUSIONS: Histamine stimulates intimal SMCs to increase iNOS expression via H1 receptors and NF-kappaB signaling pathway. Histamine could be one of NO-regulating factors, by inducing iNOS expression in intimal SMCs, and may be related to atherogenesis.

Statin treatment upregulates vascular neuronal nitric oxide synthase through Akt/NF-kappaB pathway.

OBJECTIVE: Three-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are known to enhance vascular expression of endothelial (eNOS) and inducible nitric oxide synthase (iNOS). In this study, we examined whether statins also upregulate vascular expression of neuronal NOS (nNOS). METHODS AND RESULTS: In cultured rat aortic smooth muscle cells, treatment with atorvastatin significantly increased nNOS expression, associated with activation of Akt and NF-kappaB. Inhibition of Akt by dominant-negative Akt suppressed atorvastatin-induced nNOS expression as well as Akt and NF-kappaB activation. Inhibition of NF-kappaB by dominant-negative IkappaB also attenuated atorvastatin-induced nNOS expression and NF-kappaB activation, but not Akt activation. We further examined whether atorvastatin also enhances nNOS expression in isolated mouse aorta, and if so, how much nNOS-derived NO accounts for atorvastatin-induced NOx production. In isolated aortas of wild-type mice, atorvastatin significantly increased all three NOS isoform expression and NOx production. In isolated aortas of doubly i/eNOS(-/-), n/eNOS(-/-), and n/iNOS(-/-) mice, which express only nNOS, iNOS, and eNOS, respectively, atorvastatin-induced NOx production was approximately 25%, 25%, and 50% to that of wild-type mice, respectively, suggesting that nNOS accounts for 25% of the atorvastatin-mediated NOx production. CONCLUSIONS: These results indicate that atorvastatin upregulates vascular nNOS through Akt/NF-kappaB pathway, demonstrating a novel nNOS-mediated vascular effect of the statin.

Long-term treatment with imidapril but not with nifedipine enhances plasma NOx concentration in patients with essential hypertension.

We investigated whether long-term treatment with the angiotensin-converting enzyme (ACE) inhibitor imidapril or the calcium channel antagonist nifedipine increases systemic nitric oxide (NO) production in patients with essential hypertension. Twenty-nine patients with essential hypertension were randomly divided into two groups, and they were treated with either imidapril or nifedipine once daily p.o. for 4 weeks. Long-term treatment with imidapril significantly decreased blood pressure and increased plasma NOx concentration. Long-term treatment with nifedipine also caused a comparable extent of significant decrease in blood pressure, but failed to alter plasma NOx levels. The imidapril treatment significantly inhibited serum ACE activity and increased plasma bradykinin concentration. Furthermore, the extent of inhibition of serum ACE activity and the extent of increase in plasma bradykinin concentration in response to the imidapril treatment were both significantly correlated with the extent of increase in plasma NOx concentration. In contrast, no such changes were noted after the nifedipine treatment. These results provide the first evidence that long-term treatment with imidapril enhances plasma NOx concentration in patients with essential hypertension. This effect does not seem to be due to the decrease in blood pressure. The increase in bradykinin concentration may be involved in the enhancing effect of the ACE inhibitor on NOx production in vivo.

Vascular neuronal NO synthase is selectively upregulated by platelet-derived growth factor: involvement of the MEK/ERK pathway.

OBJECTIVE: We demonstrated recently that neuronal NO synthase (NOS) is expressed in arteriosclerotic lesions and exerts important vasculoprotective effects in vivo. In this study, we examined the molecular mechanism(s) for vascular neuronal NOS (nNOS) expression. METHODS AND RESULTS: In cultured rat aortic smooth muscle cells, treatment with platelet-derived growth factor (PDGF) selectively upregulated nNOS expression but not inducible NOS (iNOS) or endothelial NOS (eNOS) expression. Treatment with PDGF also significantly caused activation of mitogen-activated protein kinase (MAPK) family, including extracellular signal-regulated kinase (ERK), p38MAPK, and c-Jun N-terminal kinase (JNK). ERK kinase (MAPK kinase [MEK]) inhibitors inhibited PDGF-induced nNOS expression, whereas a p38MAPK inhibitor or JNK inhibitor was without effects. Importantly, gene transfer of MEK per se elicited nNOS induction, and gene transfer of dominant-negative MEK abolished PDGF-induced nNOS expression. In isolated aortas of wild-type, eNOS(-/-), and iNOS(-/-) mice, but not in those of nNOS(-/-) mice, treatment with PDGF significantly enhanced nNOS expression and nitrite plus nitrate production, both of which were again attenuated by a MEK inhibitor. CONCLUSIONS: These results provide the first evidence that vascular nNOS expression is upregulated selectively in response to PDGF through the MEK/ERK pathway. Upregulated nNOS may play an important compensatory role under arteriosclerotic/inflammatory conditions associated with eNOS dysfunction to maintain vascular homeostasis.

Nephrogenic diabetes insipidus in mice lacking all nitric oxide synthase isoforms.

Nitric oxide (NO) is produced in almost all tissues and organs, exerting a variety of biological actions under physiological and pathological conditions. NO is synthesized by three different isoforms of NO synthase (NOS), including neuronal, inducible, and endothelial NOSs. Because there are substantial compensatory interactions among the NOS isoforms, the ultimate roles of endogenous NO in our body still remain to be fully elucidated. Here, we have successfully developed mice in which all three NOS genes are completely deleted by crossbreeding singly NOS-/- mice. NOS expression and activities were totally absent in the triply NOS-/- mice before and after treatment with lipopolysaccharide. Although the triply NOS-/- mice were viable and appeared normal, their survival and fertility rates were markedly reduced as compared with the wild-type mice. Furthermore, these mice exhibited marked hypotonic polyuria, polydipsia, and renal unresponsiveness to an antidiuretic hormone, vasopressin, all of which are characteristics consistent with nephrogenic diabetes insipidus. In the kidney of the triply NOS-/- mice, vasopressin-induced cAMP production and membranous aquaporin-2 water channel expression were reduced associated with tubuloglomerular lesion formation. These results provide evidence that the NOS system plays a critical role in maintaining homeostasis, especially in the kidney.

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.

Early and mid-term outcome of anastomosis of gastroepiploic artery to left coronary artery.

BACKGROUND: The performance of a bypass made to the left coronary artery using the gastroepiploic artery was examined. METHODS: Sixty-nine cases of bypass operation in which the gastroepiploic artery had been anastomosed to the left coronary artery at least 3 years prior were examined. All cases were performed by the same surgeon during the period from April 1989 to April 2000. Performance immediately after the operation and performance at least 3 years after the operation were examined on the basis of graft patency rate. RESULTS: Graft patency rates in cases with an anastomosis to the left anterior descending coronary artery and cases with an anastomosis to the circumflex artery were favorable immediately after the operation, at 96.0% (24 of 25) and 100% (18 of 18), respectively. However, over the mid-term, the patency rate dropped to 58.8% (10 of 17) in cases with an anastomosis to the left anterior descending artery, and two cases of cardiogenic sudden deaths occurred during the course of follow-up. The graft patency rate in cases with an anastomosis to the circumflex artery, on the other hand, remained favorable, at 93.3% (14 of 15). In a sequential bypass grafting through the right coronary artery, the graft between the left anterior descending coronary artery and the right coronary artery was closed, and the graft patency rate between the right coronary artery and the circumflex artery was 71.4% (10 of 14). CONCLUSIONS: The mid-term patency rate was poor for cases in which the gastroepiploic artery had been anastomosed to the left anterior descending coronary artery, which suggests that the procedure should be avoided. On the other hand, the patency rate was relatively favorable when the gastroepiploic artery had been anastomosed to the circumflex artery.

Asymmetric dimethylarginine produces vascular lesions in endothelial nitric oxide synthase-deficient mice: involvement of renin-angiotensin system and oxidative stress.

OBJECTIVE: Asymmetric dimethylarginine (ADMA) is widely believed to be an endogenous nitric oxide synthase (eNOS) inhibitor. However, in this study, we examined our hypothesis that the long-term vascular effects of ADMA are not mediated by inhibition of endothelial NO synthesis. METHODS AND RESULTS: ADMA was infused in wild-type and eNOS-knockout (KO) mice by osmotic minipump for 4 weeks. In wild-type mice, long-term treatment with ADMA caused significant coronary microvascular lesions. Importantly, in eNOS-KO mice, treatment with ADMA also caused an extent of coronary microvascular lesions that was comparable to that in wild-type mice. These vascular effects of ADMA were not prevented by supplementation of l-arginine, and vascular NO production was not reduced by ADMA treatment. Treatment with ADMA caused upregulation of angiotensin-converting enzyme (ACE) and an increase in superoxide production that were comparable in both strains and that were abolished by simultaneous treatment with temocapril (ACE inhibitor) or olmesartan (AT(1) receptor antagonist), which simultaneously suppressed vascular lesion formation. CONCLUSIONS: These results provide the first direct evidence that the long-term vascular effects of ADMA are not solely mediated by simple inhibition of endothelial NO synthesis. Direct upregulation of ACE and increased oxidative stress through AT(1) receptor appear to be involved in the long-term vascular effects of ADMA in vivo. This study demonstrates that asymmetrical dimethylarginine (ADMA) causes arteriosclerotic coronary lesions in mice in vivo through mechanisms other than simple inhibition of endothelial NO synthesis. Our findings should contribute to a better understanding of the pathophysiological role of ADMA in arteriosclerosis.