Hyperuricemia is closely associated with the mobility and mortality of patients with cardiovascular diseases. However, how hyperuricemia accelerates atherosclerosis progression is not well understood. The balance between asymmetric dimethylarginine (ADMA) and dimethylarginine dimethylaminotransferases (DDAHs) is crucial to regulate vascular homeostasis. Therefore, we investigated the role of the ADMA/DDAH pathway in hyperuricemia-induced endothelial dysfunction and atherosclerosis and the underlying molecular mechanisms in endothelial cells (ECs) and apolipoprotein E–knockout (apoe^−/−) mice. Our results demonstrated that uric acid at pathological concentrations increased the intracellular levels of ADMA and downregulated DDAH-2 expression without affecting DDAH-1 expression. Excess uric acid also reduced NO bioavailability and increased monocyte adhesion to ECs, which were abolished by using the antioxidant N-acetylcysteine, the nicotinamide adenine dinucleotide phosphate oxidase inhibitor apocynin, or DDAH-2 overexpression. In apoe^−/− mice, treatment with oxonic acid, a uricase inhibitor, increased the circulating level of uric acid, cholesterol, and lipid peroxidation; exacerbated systemic and aortic inflammation; and worsened atherosclerosis compared with vehicle-treated apoe^−/− mice. Furthermore, oxonic acid–treated apoe^−/− mice exhibited elevated ADMA plasma level and downregulated aortic expression of DDAH-2 protein. Notably, DDAH-2 overexpression in the ECs of apoe^−/− mice prevented hyperuricemia-induced deleterious effects from influencing ADMA production, lipid peroxidation, inflammation, and atherosclerosis. Collectively, our findings suggest that hyperuricemia disturbs the balance of the ADMA/DDAH-2 axis, results in EC dysfunction, and, consequently, accelerates atherosclerosis.

In congestive heart failure the balance between cell death and cell survival in cardiomyocytes is compromised. Sirtuin 1 (Sirt1) activates cell survival machinery and has been shown to be protective against ischemia/reperfusion injury in murine heart. The role of Sirt1 in heart failure, especially in human hearts is not clear.

Background/Aims: Olanzapine, an atypical antipsychotic drug, has therapeutic effects for schizophrenia. However, clinical reports indicate that patients taking atypical antipsychotic drugs are at high risk of metabolic syndrome with unclear mechanisms. We investigated the effect of olanzapine on atherosclerosis and the mechanisms in apolipoprotein E-null (apoE^-/-) mice. Methods: ApoE^-/- mice were used as in vivo models. Western blot analysis was used to evaluate protein expression. Conventional assay kits were applied to assess the levels of cholesterol, triglycerides, free cholesterol, cholesteryl ester, fatty acids, glycerol, and cytokines. Results: Daily treatment with olanzapine (3 mg/kg body weight) for four weeks increased mean arterial blood pressure and the whitening of brown adipose tissue in mice. In addition, olanzapine impaired aortic cholesterol homeostasis and exacerbated hyperlipidemia and aortic inflammation, which accelerated atherosclerosis in mice. Moreover, lipid accumulation in liver, particularly total cholesterol, free cholesterol, fatty acids, and glycerol, was increased with olanzapine treatment in apoE^-/- mice by upregulating the expression of de novo lipid synthesis-related proteins and downregulating that of cholesterol clearance- or very low-density lipoprotein secretion-related proteins. Conclusion: Olanzapine may exacerbate atherosclerosis by deregulating hepatic lipid metabolism and worsening hyperlipidemia and aortic inflammation.

Elevated plasma asymmetric dimethylarginine (ADMA) levels have been observed in patients with insulin resistance and diabetes, and have been reported to predict adverse cardiovascular events in type 2 diabetic patients. However, the relationship between ADMA and glycemic control in patients with type 2 diabetes remained controversial. We evaluated 270 patients with type 2 diabetes and measured their plasma ADMA and hemoglobin A1c (HbA1c) levels by high performance liquid chromatography. The mean age was 67 ± 12 years. The mean plasma ADMA and HbA1c level were 0.46 ± 0.09 μmol/l and 7.8 ± 1.6%, respectively. There was no significant correlation between plasma ADMA level and HbA1c level (r = −0.09, p = 0.13). During the median follow-up period of 5.7 years (inter-quartile range: 5.0 − 7.3 years), major adverse cardiovascular event (MACE, including cardiovascular death, myocardial infarction and stroke) was observed in 55 patients (20.4%). Multivariate Cox regression analysis revealed that the ADMA tertile was an independent risk factor for MACE (ADMA tertile III versus ADMA tertile I: p = 0.026, HR: 2.31, 95% CI: 1.10 − 4.81). The prognosis predictive power of ADMA disappeared in patients with well glycemic control (HbA1c ≤6.5%), and the ADMA-HbA1c interaction p value was 0.01. In patients with type 2 diabetes, ADMA might be an independent risk factor for long-term adverse cardiovascular events. However, ADMA was not correlated with serum HbA1c level, and in diabetic patients with HbA1c ≤6.5%, elevated ADMA level was no longer associated with increased risk of long-term prognosis. Our findings suggested that the prognosis predictive value of ADMA in type 2 diabetes might be modified by the glycemic control.

Background: Contrast medium-induced acute kidney injury (CI-AKI) is one of the most common causes of hospital-acquired acute renal failure. However, the pathogenesis of CI-AKI remains unclear. Asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide synthase (NOS) inhibitor that is largely metabolised by dimethylarginine dimethylaminohydroxylase (DDAH) in humans. Two isoforms of DDAH exist, namely, DDAH-1 and DDAH-2. In the present study, we examined whether the DDAH-2/ADMA/NOS pathway is involved in the pathogenesis of CI-AKI. Methods and Results: Exposure to the contrast medium iopromide led to increase in creatinine and blood urea nitrogen (BUN) levels, accumulation of ADMA, increase in reactive oxygen species (ROS) generation, and an inflammatory response in mice kidney tissue. The injection of adenovirus-harbouring DDAH-2 lowered renal ADMA levels and had a reno-protective effect against contrast-medium injury by decreasing cell apoptosis, ROS, and fibrosis. By contrast, contrast medium-induced renal injury was exacerbated in heterozygous DDAH-2 knockout mice. In the in vitro study, overexpression of DDAH-2 increased the levels of nitrite and intracellular cGMP, while the DDAH-2 knockdown induced the opposite effect. These findings were also observed in the in vivo sample. Conclusions: Our findings provide the first evidence that the DDAH-2/ADMA/NOS pathway is involved in the pathogenesis of CI-AKI and that the protective effect of DDAH-2 probably arises from the modulation of NOS activity, oxidative stress, and the inflammatory process.

Background: The transcatheter edge-to-edge mitral valve repair, using MitraClip, has been a safe and effective treatment for severe mitral regurgitation (SMR) in the westerners. However, the therapeutic results of the MitralClip in Taiwan remained elucidated. Methods: Patients with symptomatic SMR were evaluated by the heart team. For those with high or prohibitive surgical risks, transcatheter mitral valve repair was performed in hybrid operation room. During procedure, continuous hemodynamic monitoring was conducted. Transthoracic echocardiography (TTE), blood tests, and six-minute walk test (6MWT) were performed before and 1-month after surgery. Results: A total of 20 patients (73.4 ± 11.1 years, 85% male) with a mean Euroscore II of 13.2 ± 17.7% and a mean STS score of 8.7 ± 9.0% for mortality were enrolled. After a mean procedural time of 239 ± 95 min, an average of 1.8 ± 0.7 clips were used in each procedure. The procedural successful rate was 95% to achieve mild residual mitral regurgitation. Cardiac output was increased from 3.6 ± 0.9 to 4.6 ± 1.4 (p = 0.008) and V-wave of left atrial pressure declined from 24.4 ± 9.8 to 19.3 ± 7.1 (p = 0.030) immediately during the index procedure. There was no peri-procedural death, myocardial infarction, stroke or any events requiring emergent cardiac surgery. All patients experienced significant improvement in heart failure symptoms. The 6-min walk distance increased from 219.6 ± 118.4 m to 279.1 ± 111.6 (p = 0.04) at 1 month. The echocardiogram further showed significant improvements of mitral regurgitation, pulmonary artery systolic pressure, and the left ventricular end-diastolic volume. Conclusion: Trans-catheter edge-to-edge mitral valve repairs are safe and effective in Asians with symptomatic SMR, regarding the improvements of clinical symptoms and exercise capacities. MitraClips is also associated with reverse remodeling of pulmonary hypertension and left ventricular size in patients with SMR.