Role of asymmetric dimethylarginine in the progression of carotid atherosclerosis in renal transplant patients

Effects of dialysis solution on the cardiovascular function in peritoneal dialysis patients

Objective Peritoneal dialysis (PD) patients have an increased cardiovascular burden. In this study, we aimed to compare certain PD solutions (Physioneal(®) and Dianeal(®)) in terms of the ambulatory blood pressure, echocardiographic parameters (ECHO), carotid atherosclerosis, endothelial function and serum asymmetric dimethylarginine (ADMA) level. Methods A total of 45 PD patients were enrolled in this prospective randomized controlled study: 23 patients in the Dianeal(®) group and 22 patients in the Physioneal(®) group. Ambulatory blood pressure measurements, echocardiography, carotid artery intima-media thickness measurements and flow mediated dilatation (FMD) and ADMA values were obtained at baseline and 12 months. Results The baseline parameters were similar between the groups with respect to the echocardiographic parameters, 24-hour ambulatory blood monitoring measurements and ADMA and FMD levels. All 24-hour blood pressure monitoring measurements, except for the average daytime systolic blood pressure, were significantly decreased in both groups at the first year. In the Physioneal(®) group, a significant decrease was observed with regard to the ADMA levels. Considering the FMD values, significant augmentation was seen at the end of the first year in both groups. Improvements in the FMD measurements were prominent in the Physioneal(®) group; however, this finding was not statistically significant. Conclusion The use of solutions with a neutral pH in PD patients results in decreased ADMA levels, which may be an important contributor to reductions in the incidence of cardiovascular events and deaths in this population.

A longitudinal study of inflammation, CKD-mineral bone disorder, and carotid atherosclerosis after renal transplantation

BACKGROUND AND OBJECTIVES

The role of reversibility of nontraditional risk factors, like inflammation and CKD-mineral bone disorder, in the reduction of cardiovascular risk after renal transplantation is still scarcely defined.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

The longitudinal relationship between C-reactive protein, CKD-mineral bone disorder biomarkers, and intima media thickness was investigated in a series of 178 patients (age=32±10 years) with stage 5 CKD maintained on chronic dialysis who underwent echo-color Doppler studies of the carotid arteries before and after renal transplantation. Smokers and patients with diabetes were excluded from the study. In all patients, immunosuppression was performed by a standard regimen on the basis of calcineurin inhibitors. Healthy controls were specifically selected to match the age and sex distribution of the patients. Biochemical and intima media thickness assessments were repeated 6 months after transplantation.

RESULTS

Before transplantation, intima media thickness in patients with stage 5 CKD on dialysis (average=0.9±0.2 mm) was higher (P<0.001) than in well matched healthy controls (0.6±0.1 mm) and reduced substantially (-22%; 95% confidence interval, -24% to -20%) after transplantation (P=0.001). GFR (multivariable-adjusted β=0.23; P<0.001), C-reactive protein (β=0.15; P<0.001), and fibroblast growth factor 23 (β=0.28; P<0.001) were the strongest independent correlates of intima media thickness before transplantation. Similarly, longitudinal changes in the same biomarkers were the sole independent correlates of simultaneous changes in intima media thickness (C-reactive protein: β=0.25; fibroblast growth factor 23: β=0.26; P<0.001 for both) after renal transplantation. The evolution of intima media thickness after transplantation was largely independent of classic risk factors, including BP, LDL cholesterol, and insulin resistance, as measured by homeostatic model assessment.

CONCLUSIONS

Intima media thickness improves after renal transplantation. Such an improvement associates with parallel changes in serum C-reactive protein and fibroblast growth factor 23. These observations are in keeping with the hypothesis that the decline in cardiovascular risk after transplantation, in part, depends on partial resolution of nontraditional cardiovascular risk factors, like inflammation and CKD-mineral bone disorder.

Plasma arginine/ADMA ratio as a sensitive risk marker for atherosclerosis: Shimane CoHRE study

BACKGROUND

Asymmetric dimethylarginine (ADMA), which acts an endogenous inhibitor of nitric oxide synthase (NOS), is involved in the pathogenesis of cardiovascular disease. Arginine (Arg) may regulate vascular endothelial function, since Arg is the substrate of NO competing with ADMA. In our previous study, low Arg/ADMA ratio is an independent risk for microangiopathy-related cerebral damage.

PURPOSE

Here, we performed a cross-sectional study to evaluate the association between the Arg/ADMA ratio and the maximal intima-media thickness (IMT) in the carotid artery.

SUBJECTS AND METHODS

Participants were 785 community-dwelling Japanese people without any severe disorders. Plasma concentration of Arg and ADMA in fasting blood sample was determined using HPLC. IMT was measured in the bilateral carotid artery by ultrasonography.

RESULTS

Among quartiles stratified by the Arg/ADMA ratio, ANOVA showed a significant difference in IMT and the IMT in Q1 (the lowest quartile) was significantly higher than that in Q4 (the highest quartile). In multiple linear regression analysis, age, the male gender, lower BMI, the presence of hypertension and lower Arg/ADMA ratio were independently correlated with IMT, while IMT was not correlated with Arg or ADMA alone. In addition, the Arg/ADMA ratio was associated with IMT independent of age, sex, BMI and the presence of hypertension with odds ratio 0.21 (95%CI: 0.05-0.88) in multiple logistic regression analysis for IMT 1.5 mm or more.

CONCLUSION

Imbalance of Arg and ADMA is independently involved in the progression of atherosclerosis, and the Arg/ADMA ratio may be a sensitive marker for atherosclerosis.

Circulating CD133+ CD34+ progenitor cells and plasma stromal-derived factor-1alpha: predictive role in ischemic stroke patients

Circulating progenitor cells and stromal-derived factor-1alpha (SDF-1α) have been suggested to participate in tissue repair after ischemic injury. However, the predictive role of circulating CD133+ CD34+ progenitors and plasma SDF-1α in ischemic stroke (IS) patients remains unknown. In this study, we recruited 95 acute IS patients, 40 at-risk subjects, and 30 normal subjects. The National Institutes of Health Stroke Scale (NIHSS), infarct volume, and carotid intima-media thickness (IMT) were determined at day 1 and the modified Rankin scale (mRS) of functional outcome was assessed at day 21. The levels of circulating CD133+ CD34+ cells and plasma SDF-1α were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively. Our data showed that: (1) the levels of CD133+ CD34+ cells were lower in at-risk subjects and IS patients at admission (day 1) when compared with normal controls; (2) the day 1 level of CD133+ CD34+ cells varied in IS subgroups and inversely correlated with NIHSS and carotid IMT and the level of SDF-1α inversely correlated with NIHSS and infarct volume; (3) the increment rates of circulating CD133+ CD34+ cells and plasma SDF-1α within the first week were correlated; and (4) patients with a higher level of CD133+ CD34+ cells at day 7 had a low mRS. The increased rate of CD133+ CD34+ cells in the first week was inversely associated with mRS. In conclusion, our findings demonstrate that the circulating CD133+ CD34+ progenitor cells and plasma SDF-1α can be used as predictive parameters for IS severity and outcome.

Asymmetric dimethylarginine attenuates serum starvation-induced apoptosis via suppression of the Fas (APO-1/CD95)/JNK (SAPK) pathway

Asymmetric dimethylarginine (ADMA) is synthesized by protein arginine methyltransferases during methylation of protein arginine residues and released into blood upon proteolysis. Higher concentrations of ADMA in blood have been observed in patients with metabolic diseases and certain cancers. However, the role of ADMA in colon cancer has not been well investigated. ADMA serum levels in human patients diagnosed with colon cancer were found to be higher than those present in healthy subjects. ADMA treatment of LoVo cells, a human colon adenocarcinoma cell line, attenuated serum starvation-induced apoptosis and suppressed the activation of the Fas (APO-1/CD95)/JNK (SAPK) (c-Jun N terminal protein kinase/stress-activated protein kinase)pathway. ADMA also suppressed the activation of JNK triggered by death receptor ligand anti-Fas mAb and exogenous C₂-ceramide. Moreover, we demonstrated that ADMA pretreatment protected LoVo cells from doxorubicin hydrochloride-induced cell death and activation of the Fas/JNK pathway. In summary, our results suggest that the elevated ADMA in colon cancer patients may contribute to the blocking of apoptosis of cancer cells in response to stress and chemotherapy.