Toshinobu Sato

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.

Increased risk of cardiovascular events and mortality among non-diabetic chronic kidney disease patients with hypertensive nephropathy: the Gonryo study

To examine the clinical significance of hypertensive nephropathy (HN) among non-diabetic chronic kidney disease (CKD) patients. The study comprised 2692 CKD patients recruited from 11 outpatient nephrology clinics; these included 1306 patients with primary renal disease (PRD), 458 patients with HN, 283 patients with diabetic nephropathy (DN) and 645 patients with other nephropathies (ONs). All patients fulfilled the criteria of CKD, with a persistent low estimated glomerular filtration rate (eGFR) <60 ml min−1 per 1.73 m2 or proteinuria as determined by a urine dipstick test. The risk factors for cardiovascular disease (CVD), such as ischemic heart disease, congestive heart failure and stroke; all-cause mortality; and progression to end-stage renal failure (dialysis induction) were analyzed using a Cox proportional hazards model in each group. During a mean follow-up period of 22.6 months from recruitment, 100 patients were lost to follow-up and 192 patients began chronic dialysis therapy. A total of 115 CVD events occurred (stroke in 37 cases), and 44 patients died. Regarding CVD events and death, there were significant differences in the hazard ratios (HRs) for the groups of patients with different underlying renal diseases as determined by both univariate and multivariate analysis adjusted for confounding factors including estimated glomerular filtration rate: PRD, 1.0 (reference); HN, 3.33 (95% confidence interval, 1.82–6.09); DN, 5.93 (2.80–12.52); and ON, 2.22 (1.22–4.05). However, there were no differences in the hazard ratio for dialysis induction for the groups of patients with different underlying renal diseases. HN is associated with an increased risk of CVD events and death among non-diabetic CKD patients, which highlights the clinical significance of HN.

Endothelin receptors in ischemic rat brain and Alzheimer brain.

Summary: Endothelin (ET) binding sites in male Wistar rat brains subjected to a 20-min four-vessel occlusion (transient forebrain ischemia model) which induces hip-pocampal neuron death, and in human brains with Alzheimer disease, were mapped by quantitative in vitro autoradiography employing [125I]ET-1 as a radioligand. Rats were decapitated 4 or 7 days after ischemia. In the rat brain, the [125I]ET-1 binding sites were remarkably increased in the hippocampal CA1 and dentate gyrus, ventral thalamic nucleus, and cortical vessels 4 and 7 days after ischemia, when many reactive astroglia were observed. The [125I]ET-1 binding sites decreased in the cerebral cortex affected by Alzheimer disease. The binding was abolished by 1 μM unlabeled ET-1, ET-3, sarafotoxin S6b, and BQ788 (an ETB antagonist) but not by BQ123 (an ETA antagonist), suggesting that the [125I]ET-1 binding sites are as ETB receptors. The present findings raise the possibility that a glial ET system could be responsible for the occurrence of ischemic neuron cell death.

Night-time blood pressure is associated with the development of chronic kidney disease in a general population: the Ohasama Study.

Objective: Ambulatory blood pressure (BP) is reportedly associated with target organ damage. However, whether ambulatory BP carries prognostic significance for the development of chronic kidney disease (CKD) has not been confirmed. Method: We measured ambulatory BP in 843 participants without CKD at baseline from a general Japanese population and examined the incidence of CKD defined as positive proteinuria or an estimated glomerular filtration rate (eGFR) less than 60 ml/min per 1.73 m2 at health checks. The association between baseline ambulatory BP and CKD incidence was examined using the Cox proportional hazard regression model adjusted for sex, age, BMI, habitual smoking, habitual alcohol consumption, diabetes mellitus, hypercholesterolemia, a history of cardiovascular disease, antihypertensive medication, eGFR at baseline, the number of follow-up examinations, and the year of the baseline examination. Results: The mean age of the participants averaged 62.9 ± 8.1 years, 71.3% were women and 23.7% were under antihypertensive medication. During a median follow-up of 8.3 years, 220 participants developed CKD events. The adjusted hazard ratios for CKD in a 1-standard deviation increase in daytime and night-time SBP were 1.13 [95% confidence interval (CI) 0.97–1.30] and 1.21 (95% CI 1.04–1.39), respectively. When night-time and daytime BP was mutually adjusted into the same model, only night-time BP persisted as an independent predictor of CKD. Conclusion: Night-time BP is a better predictor of CKD development than daytime BP in the general population. Ambulatory BP measurement is considered useful for evaluating the risk of progression to CKD.

Intake of water with high levels of dissolved hydrogen (H2) suppresses ischemia-induced cardio-renal injury in Dahl salt-sensitive rats

BACKGROUND Hydrogen (H(2)) reportedly produces an antioxidative effect by quenching cytotoxic oxygen radicals. We studied the biological effects of water with dissolved H(2) on ischemia-induced cardio-renal injury in a rat model of chronic kidney disease (CKD). METHODS Dahl salt-sensitive rats (7 weeks old) were allowed ad libitum drinking of filtered water (FW: dissolved H(2), 0.00 ± 0.00 mg/L) or water with dissolved H(2) produced by electrolysis (EW: dissolved H(2), 0.35 ± 0.03 mg/L) for up to 6 weeks on a 0.5% salt diet. The rats then underwent ischemic reperfusion (I/R) of one kidney and were killed a week later for investigation of the contralateral kidney and the heart. RESULTS In the rats given FW, unilateral kidney I/R induced significant increases in plasma monocyte chemoattractant protein-1, methylglyoxal and blood urea nitrogen. Histologically, significant increases were found in glomerular adhesion, cardiac fibrosis, number of ED-1 (CD68)-positive cells and nitrotyrosine staining in the contralateral kidney and the heart. In rats given EW, those findings were significantly ameliorated and there were significant histological differences between rats given FW and those given EW. CONCLUSION Consumption of EW by ad libitum drinking has the potential to ameliorate ischemia-induced cardio-renal injury in CKD model rats. This indicates a novel strategy of applying H(2) produced by water electrolysis technology for the prevention of CKD cardio-renal syndrome.

Dialyzable Uremic Solutes Contribute to Enhanced Oxidation of Serum Albumin in Regular Hemodialysis Patients

Background: Oxidative stress (OS) is reportedly enhanced in patients receiving regular hemodialysis (HD). However, the in vivo redox state of HD patients, particularly after HD sessions, remains unclear. This study aimed to clarify the influence of HD on OS using the albumin redox state as a marker. Method: Blood samples of 8 regular HD patients were obtained during the course of study. The redox state of albumin was determined using high-performance liquid chromatography. Results: The mean fraction of reversibly oxidized albumin [f(HNA-1)] declined significantly over the course of the session and reached a minimum 4 h after the session had ended (pre-HD, 36.16 ± 7.50%; 4 h after HD, 25.71 ± 6.41%), then gradually rose to predialytic levels. The proportion of irreversibly oxidized albumin did not change significantly over time. Positive correlations were demonstrated between f(HNA-1) and uremic small solutes in each case. Conclusion: Accumulation of dialyzable uremic solutes may contribute to OS in HD patients.

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.

The involvement of advanced glycation endproducts (AGEs) in renal injury of diabetic glomerulosclerosis: association with phenotypic change in renal cells and infiltration of immune cells.

AbstractBackground. Glycation of proteins is regarded as one of the major causes of the progression of diabetic nephropathy (DN) and of the phenotypic changes in glomerular mesangial cells (MC) and the cellular infiltration that occurs in MC from DN. It thus is very important to study the interrelationships and interaction between these causes. Methods. The localization of advanced glycation endproducts (AGEs), cytoskeletal proteins, and immune cell infiltration was evaluated by immunohistochemical study in patients with DN. Results. NΕ-(carboxymethyl)lysine (CML), Α-smooth muscle actin (SMA), and low-molecular-weight caldesmon (L-CLD) were localized in the mesangial area in DN. The intensity of mesangial SMA and L-CLD expression was significantly correlated with the index of diabetic glomerulosclerosis (IDGS), while the expression of pentosidine was correlated with the IDGS and with 24-h urinary protein. Pentosidine was localized in glomerular basement membrane (GBM) only in DN and had a significant correlation with the mesangial expression of SMA and L-CLD. Pyrraline deposition on the tubular basement membrane, and the expression of SMA and L-CLD, and the infiltration of immune cells were observed in interstitial areas in DN. The intensity of L-CLD expression had a close relationship with pyrraline deposition and immune cell infiltration. The expression of SMA and L-CLD in interstitial areas was significantly correlated with the percent interstitial volume. Conclusions. AGEs are involved in renal injury in DN, and their effect is, at least in part, exercised via phenotypic changes in intrinsic renal cells and by the infiltration of immune cells.

Transport phenomena of microbial flora in the small intestine with peristalsis.

The gastrointestinal tract of humans is colonized by indigenous prokaryotic and eukaryotic microbial cells that form a complex ecological system called microbial flora. Although the microbial flora has diverse functions, its homeostasis inside the gastrointestinal tract is still largely unknown. Therefore, creating a model for investigating microbial flora in the gastrointestinal tract is important. In this study, we developed a novel numerical model to explore the transport phenomena of microbial flora in the small intestine. By simultaneously solving the flow field generated by peristalsis, the concentrations of oxygen and nutrient, and the densities of moderate anaerobes and aerobes, the effects of fluid mechanics on the transport phenomena of microbial flora are discussed. The results clearly illustrated that fluid mechanics have considerable influence not only on the bacterial population, but also on the concentration distributions of oxygen and nutrient. Especially, the flow field enhances the radial variation of the concentration fields. We also show scaling arguments for bacterial growth and oxygen consumption, which capture the main features of the results. Additionally, we investigated the transport phenomena of microbial flora in a long tube with 40 constrictions. The results showed a high growth rate of aerobes in the upstream side and a high growth rate of anaerobes in the downstream side, which qualitatively agrees with experimental observations of human intestines. These new findings provide the fundamental basis for a better understanding of the transport phenomena of microbial flora in the intestine.

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.