Hiroyuki Terawaki

Plasma α-Oxoaldehyde Levels in Diabetic and Nondiabetic Chronic Kidney Disease Patients

BACKGROUND alpha-Oxoaldehydes such as glyoxal (GO), methylglyoxal (MG), and 3-deoxyglucosone (3DG) are precursors of advanced glycation end products and exert direct toxicity to cells and tissues. Plasma levels of these substances are reportedly elevated in diabetes and dialysis patients, but the data on exact levels and clinical significance in chronic kidney disease (CKD) are limited. METHODS We evaluated plasma alpha-oxoaldehyde levels using liquid chromatography mass spectrometry methods in 19 healthy controls and 99 CKD patients with or without diabetes (n = 46 and n = 53, respectively). RESULTS Mean plasma GO levels in control, CKD stage 1-2, CKD stage 3-5 and CKD stage 5D groups were 285 +/- 59, 339 +/- 88, 483 +/- 172 and 1,178 +/- 309 nM, respectively (p < 0.001). MG levels were 249 +/- 17, 265 +/- 27, 461 +/- 188 and 922 +/- 354 nM, respectively (p < 0.001). Moreover, significantly higher MG levels were observed in patients with cardiovascular disease history compared to those without. Plasma 3DG levels did not differ among CKD groups and were significantly higher in diabetic patients than in nondiabetic patients. CONCLUSIONS Plasma GO and MG levels increase as the CKD stages progress and high plasma MG levels may be associated with an increased risk of CVD in CKD patients.

The redox state of albumin and serious cardiovascular incidence in hemodialysis patients.

Human serum albumin is composed of human mercaptoalbumin (HMA) with cysteine residues having reducing powers and oxidized human non‐mercaptoalbumin. The aim of this study is to clarify whether such redox state of albumin (HSA‐redox) influences the incidence of cardiovascular disease (CVD) in chronic kidney disease patients on regular hemodialysis (HD). We measured HSA‐redox using high‐performance liquid chromatography in 86 anuric HD patients. The association between HSA‐redox and incidental CVD events was evaluated. Twenty patients experienced symptomatic CVD events (16 patients died) at the 2‐year follow‐up. The fraction of HMA (f(HMA)) showed a significantly lower value in patients with CVD than that without CVD, in both pre‐HD (36.5 ± 5.8% and 44.6 ± 9.8%, respectively) and post‐HD (57.2 ± 6.2% and 67.2 ± 7.4%, respectively). The adjusted odds ratio (OR) for the incidental CVD event in patients with pre‐HD f(HMA) < 40% was 5.0 (95% CI; 1.2 to 21.3), and that in patients with post‐HD f(HMA) < 60% was 20.6 (3.2 to 134.7). Likewise, the adjusted OR for the CVD death in patients with pre‐HD f(HMA) < 40% was 2.5 (0.6 to 12.5), and that in patients with post‐HD f(HMA) < 60% was 25.6 (2.5 to 262.8). In conclusion, HSA‐redox is closely related to serious CVD incidence and mortality among HD patients.

Biological Effects of Electrolyzed Water in Hemodialysis

Background/Aims: The application of electrolyzed water (EW) at the cathode side to manufacture reverse osmosis (RO) water and hemodialysis (HD) solution can actually lead to less oxidative capacity in chemical terms. The present study examined the biological actions of this water on human polymorphonuclear leukocytes (PMNs), and the clinical feasibility of applying this technology to HD treatment. Methods: RO water using EW (e-RO) exhibited less chemiluminescence in luminol-hydrogen peroxide and higher dissolved hydrogen levels (–99.0 ppb) compared with control RO water. The effects of e-RO on PMN viability were tested. HD using e-RO was performed for 12 consecutive sessions in 8 patients for the feasibility test. Results: Basal cellular viability and function to generate superoxide radicals of PMNs were better preserved by e-RO application. In the clinical trial, reductions of blood pressure were noted, but no adverse events were observed. There were no changes in the blood dialysis parameters, although methylguanidine levels were significantly decreased at the end of study. Conclusion: The present study demonstrated the capacity of e-RO to preserve the viability of PMNs, and the clinical feasibility of applying this water for HD treatment. The clinical application of this technology may improve the bio-compatibility of HD treatment.

Polymorphonuclear leukocyte injury by methylglyoxal and hydrogen peroxide: a possible pathological role for enhanced oxidative stress in chronic kidney disease

BACKGROUND Accelerated burst of polymorphonuclear leukocytes (PMNs) may be involved in the primary pathology of enhanced oxidative stress in patients with chronic kidney disease (CKD); however, the precise mechanism remains unknown. Methylglyoxal (MGO), an alpha-oxoaldehyde reportedly elevated in CKD, could induce apoptosis in several cell lines, and generates radicals by the reaction with hydrogen peroxide (H(2)O(2)). Thus, we tested if a high MGO of uraemic milieu could play a role in PMN injury by interaction with H(2)O(2). METHOD Cellular viability of PMNs, isolated from healthy volunteers, was tested by ATP chemiluminescence levels under MGO and/or H(2)O(2), or 4-beta phorbol 12-beta-myristate 13-alpha-acetate (PMA). Superoxide anion (O(2)(-)) generation and apoptosis were measured by the reduction of ferricytochrome C and fluorocytometric analysis, respectively. Plasma MGO levels were measured by mass spectometry in 29 CKD patients. RESULTS At low levels of MGO (1-10 microM) and H(2)O(2) (12.5 microM), no differences were found in cellular viability as compared to controls, whereas their combination significantly decreased PMN viability. PMA stimulation enhanced cellular injury of MGO by a function of MGO levels and preincubation with 5,5-dimethyl-1-pyrroline-N-oxide (free radical trap agent) attenuated it. MGO suppressed O(2)(-) generation by PMA, while it accelerated apoptotic ratios in PMNs. Significant increases of plasma MGO and C-reactive protein levels were found by a function of CKD stage, and clinical level of MGO could induce PMN injury in combination with H(2)O(2). CONCLUSION These results indicate the combinatory effect of MGO and H(2)O(2) on PMN oxidative injury, and this pathology may be linked to enhanced oxidative stress in CKD.

Less-oxidative hemodialysis solution rendered by cathode-side application of electrolyzed water

Electrolyzed water (EW) generated on the cathode side reportedly displays anti‐oxidative properties, and application of EW to hemodialysis (HD) systems supposedly suppresses oxidative markers in patients on HD. However, most of the chemical properties and biological effects of such solutions remain unclear. This study aimed to examine those issues to clarify the scientific background for the clinical use of EW solution. Reverse osmosis water comprising EW from the cathode side (e‐RO) was prepared and used to process a test HD solution (e‐HD). Chemical and biological properties of these solutions were compared with controls. Redox properties were examined by chemiluminescence (CL) of the luminol‐H2O2 system. Biological effects of e‐RO on human polymorphonuclear leukocytes (PMNs) were tested with respect to the cellular protection against methylglyoxal, and with respect to the preservation of cellular function as to radical generation. Control HD solution presented the highest CL, followed by e‐HD, control RO, suggesting a lower oxidative capacity for EW‐based solutions. Increased levels of dissolved hydrogen were characteristic of e‐RO and e‐HD. Application of e‐RO tended to be associated with less injury of PMNs by methylglyoxal, and with significantly higher levels of radical generation compared with the control. Compared with control HD, e‐RO‐based HD solution displays less‐oxidative capacity in chemical terms, and may at least partly facilitate preservation of PMN viability. These results appear to offer a scientific basis for supporting the clinical challenge of applying this technology to HD treatment.

Translational Research of Peritoneal Dialysis Solution with Dissolved Molecular Hydrogen

BACKGROUND Improved biocompatibility of peritoneal dialysis solution (PDS) is crucial for peritoneal membrane preservation, thereby ensuring long-term peritoneal dialysis (PD) and preventing encapsulating peritoneal sclerosis. We previously reported the protective effect of molecular hydrogen (H2) on mesothelial cells from PDS in nonuremic rats. SUMMARY In the present study, we examined the effect of H2-containing PDS (commercially available neutral pH type) regarding the protection of peritoneal tissue in experimental chronic kidney disease rats. Furthermore, we conducted a 2-week clinical trial in which H2-containing PDS was used in place of standard PDS and its feasibility was examined. In the experimental study, test solutions were injected through the subcutaneous port into the abdomen for 3 weeks. Histological study revealed a significant increase in the number of mesothelial cells and a significant decrease in peritoneal thickness in the H2-PD group as compared to the control and PD groups. Also, results of immunostaining analysis revealed increased vimentin and apoptotic cells in the membrane of the PD group, indicating that H2 may play a role in ameliorating PDS-induced peritoneal injury and preserving peritoneal integrity. In the clinical trial with 6 prevalent PD patients, all subjects completed the study with no adverse effects. Moreover, there were substantial changes in surrogate markers, such as increased CA125 and mesothelin, in the effluent in selected cases, suggesting enhanced mesothelial regeneration by H2. Key Message: H2-enriched PDS is a candidate novel PDS with improved biocompatibility. Further, our results support the significance of H2-PD clinical trials in the future.

Effect of successful renal transplantation on coronary AGE accumulation of uremic heart

Abstract In order to investigate the effect of successful renal transplantation (RTx) on uremic heart, we examined (1) immunohistochemical AGE (CML-AGE) accumulation on cardiac arterial walls from well-functioning RTx patients (n=8), patients on maintenance dialysis (DY) (n=10) and nondiabetic subjects with normal renal function as control (n=7), and (2) the changes in cardiovascular functions before and after RTx. Results: (1) Coronary atherosclerotic lesions were detected in both DY and RTx patients (diffuse intimal thickenings of all patients and partial fatty streaks of two DY patients). (2) In 9 of 10 DY patients, AGE accumulation was observed in coronary arteries (intima or media), although this was true in only two of seven control subjects (p