Cardiovascular disease (CVD) is prevalent in patients with chronic kidney disease (CKD). In hemodialysis (HD) patients, some protein-bound uremic toxins are considered to be associated with CVD. However, it is not yet known which uremic toxins are important in terms of endothelial toxicity. Serum samples were obtained from 45 HD patients before and after HD. Total and free serum concentrations of indoxyl sulfate, indoxyl glucuronide, indoleacetic acid, p-cresyl sulfate, p-cresyl glucuronide, phenyl sulfate, phenyl glucuronide, phenylacetic acid, phenylacetyl glutamine, hippuric acid, 4-ethylphenyl sulfate, and 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF) were simultaneously measured by liquid chromatography/electrospray ionization-mass spectrometry/mass spectrometry (LC/ESI-MS/MS). The effects of these solutes at their pre-HD mean and maximum serum concentrations on reactive oxygen species (ROS) production in human umbilical vein endothelial cells (HUVEC) were measured with a ROS probe. Serum levels of 11 of the solutes (all except 4-ethylphenyl sulfate) were significantly increased in HD patients compared to healthy subjects. All 12 solutes showed changes in their protein-binding ratios. In particular, indoxyl sulfate, p-cresyl sulfate, CMPF, and 4-ethylphenyl sulfate showed high protein-binding ratios (>95 %) and low reduction rates by HD (<35 %). Indoxyl sulfate at its mean and maximum pre-HD serum concentrations-even with 4 % albumin-stimulated ROS production in HUVEC most intensely, followed by CMPF. In conclusion, the serum levels of 11 protein-bound uremic toxins were increased in HD patients. Indoxyl sulfate, p-cresyl sulfate, and CMPF could not be removed efficiently by HD due to their high protein-binding ratios. Indoxyl sulfate most intensely induced endothelial ROS production, followed by CMPF.

Coronary artery calcification is an index of the severity of atherosclerotic vascular disease, and may predict future adverse cardiovascular events in uremic patients undergoing hemodialysis (HD). HD patients are exposed to oxidative stress, and show high plasma levels of advanced glycation end products (AGEs). The association between oxidative stress, AGEs, established cardiovascular risk factors, and coronary artery calcification score (CACS) was studied in 225 HD patients (123 male, 102 female patients). CACS was measured by using multi-detector row computed tomography. Age, systolic blood pressure, calcium, calcium x phosphate, malondialdehyde, lipid peroxides, and pentosidine were significantly and positively correlated with CACS. Duration on HD tended to be positively correlated with CACS. From the independent variables included in the forward stepwise multiple linear regression analysis, only age, systolic blood pressure, lipid peroxides, calcium, and pentosidine were independently associated with CACS. The odds ratios for past history of coronary artery disease and the presence of diabetes mellitus for high CACS (> or =100) were 6.25 (95% confidence interval; 1.83-21.4) and 2.03 (95% confidence interval; 1.02-4.05), respectively. The plasma pentosidine was significantly and positively correlated with indoxyl sulfate. In conclusion, in addition to such traditional cardiovascular risk factors as past history, diabetes mellitus, aging, systolic blood pressure and calcium overload, oxidative stress (lipid peroxides), and AGE (pentosidine) are associated with extensive coronary artery calcification in HD patients. Lipid peroxidation and glycoxidation may be involved in the pathogenesis of coronary artery calcification.

Background: Indoxyl sulfate is a uremic toxin that accelerates the progression of chronic kidney disease (CKD). Serum levels of indoxyl sulfate are increased in dialysis patients. It was reported that indoxyl sulfate plays a role in endothelial dysfunction in uremic patients, and stimulates proliferation of rat vascular smooth muscle cells (VSMC). We examined associations between indoxyl sulfate and several markers related to atherosclerosis. Methods: The association between indoxyl sulfate and atherosclerotic risk factors was studied in 224 hemodialysis (HD) patients (123 male, 101 female). Serum levels of indoxyl sulfate were measured by using high-performance liquid chromatography (HPLC). Results: There were significant differences in serum levels of creatinine, calcium × phosphate and pentosidine between high- and lowindoxyl sulfate level groups. Indoxyl sulfate showed significant positive correlations with pentosidine, creatinine, and protein catabolic rate, and a significant negative correlation with high-density lipoprotein (HDL) cholesterol. Further, pentosidine, creatinine, and HDL-cholesterol were independently associated with indoxyl sulfate by multiple linear regression analysis. Conclusion: In addition to creatinine, pentosidine and HDL-cholesterol, the risk factors of atherosclerosis, were associated with indoxyl sulfate in HD patients. Indoxyl sulfate may be involved in the pathogenesis of atherosclerosis.

Objective: Nrf2 is a transcription factor that regulates the expression of antioxidant genes. This study aimed to investigate the association of Nrf2 gene single nucleotide polymorphisms (SNPs), rs35652124 (-653A/G) and rs6721961 (-617C/A), with laboratory data and mortality in hemodialysis (HD) patients. Methods: Blood samples were obtained from 216 HD patients (119 males and 97 females; 60 diabetics and 156 non-diabetics) with mean age of 60.3±13.3 (SD) years, and mean HD duration of 9.10±8.28 years. Genotyping was performed using polymerase chain reaction with confronting two-pair primers (PCR-CTPP) assay.Results: As for rs35652124, diastolic blood pressure (BP) was significantly high in total AA carriers. β2-microglobulin was significantly low in male AA carriers. Systolic BP, diastolic BP and albumin were significantly high in female AA carriers. As for 6721961, systolic BP and diastolic BP were significantly high in female AA carriers. Cox proportional hazard analysis adjusted for age, HD duration, diabetes and Kt/V demonstrated that rs35652124 AA carriers showed higher cardiovascular mortality than (GG+GA) carriers.Conclusion: Nrf2 SNPs were associated with BP in Japanese HD patients. More notably, rs35652124 was associated with cardiovascular mortality in these patients.

We evaluated the relationship between the volume of parathyroid glands estimated by ultrasonography (US) and response of 22-oxa calcitriol (Maxacalcitol, OCT) in patients with secondary hyperparathyroidism (2HPT) to evaluate whether the volume can be a predictor of the OCT response. Eleven institutes participated in this study. Ninety-four patients with advanced 2HPT were enrolled. The volume of the parathyroid glands were estimated by US before and 6 months after OCT treatment. The response of OCT treatment was classified into three groups (Group A: i-PTH < 300 pg/mL; Group B: 300 pg/mL < or = i-PTH < 500 pg/mL; Group C: i-PTH > or = 500 pg/mL). Forty-eight patients were in Group A, 28 patients in Group B, and 18 patients in Group C. The PTH levels at the beginning and 6 months were 458.3-199.1 pg/mL (P < 0.0001) in Group A, 524.6-403.2 pg/mL (P = 0.007) in Group B and 736.7-613.6 pg/mL (ns) in Group C, respectively. The volume of the largest gland in Group B was significantly larger than that in Group A (96.2 vs. 343.2 mm3: P < 0.001). Clinical factors affecting response of OCT was evaluated by logistic regression analysis and only the volume of the largest gland was a significant factor. In the patients whose volume was less than 300 mm3, the OCT response was significantly effective. We conclude that the glandular volume of the largest parathyroid gland estimated by US can be a useful factor to predict the OCT response in patients with moderate or severe renal HPT.