Kazuhiro Sumitomo

An Oral Adsorbent, AST-120, Suppresses Oxidative Stress in Uremic Rats

Background: The production of reactive oxygen species (ROS) has been suggested to play an important role in the progression of chronic kidney disease (CKD). An oral adsorbent, AST-120, removes uremic toxins such as indoxyl sulfate (IS) and delays the progression of CKD, but the effect on ROS production is unknown. The present study aimed to determine whether AST-120 reduces oxidative stress in uremic rat kidneys using markers of ROS production such as acrolein and 8-hydroxy-2′-deoxyguanosine (8-OHdG). Methods: Daily administration of AST-120 was started 6 weeks after 5/6 nephrectomy and continued for 18 weeks. The changes in metabolic data, serum and urine IS levels, urinary excretion of markers of oxidative stress, and renal histological findings were investigated in uremic rats with or without AST-120 treatment. Results: In parallel with the increase in serum and urine IS, the serum creatinine, urinary protein and acrolein levels started to increase at 6 weeks, but urinary 8-OHdG remained unchanged and significantly increased at 18 weeks in uremic rats. AST-120 markedly and significantly attenuated increases in uremic toxins and oxidative stress levels as well as the histological changes in glomerular sclerosis, interstitial fibrosis, and the tubular staining of 8-OHdG. Conclusion: AST-120 suppressed the progression of CKD, at least in part, via attenuation of oxidative stress induced by uremic toxin.

Oral Pretreatment with Ebselen Enhances Heat Shock Protein 72 Expression and Reduces Myocardial Infarct Size

Reactive oxygen species (ROS) enhance myocardial ischemia-reperfusion (I/R) injury. Ebselen, a seleno-organic glutathione peroxidase (GPx) mimetic, has a protective effect against tissue injury induced by ROS. However, the cardio-protective effect of orally administered ebselen has never been investigated in cardiac I/R injury. We investigated the effects and mechanisms of orally administered ebselen on experimental myocardial infarction. Isolated perfused rabbit hearts underwent 30 min of global ischemia and 60 min of reperfusion, with or without oral administration of ebselen 24 h before I/R, with or without enhanced oxidative stress by H2O2 infusion for the first 1 min of reperfusion. The recovery of left ventricular developed pressure (LVDP) was significantly improved, and the myocardial infarct size was significantly reduced by ebselen. The recovery of LVDP and the myocardial infarct size were markedly aggravated by H2O2 infusion. These enhancements by H2O2 were dose-dependently suppressed by ebselen, along with a reduction in myocardial 8-hydroxydeoxyguanosine levels, a marker for oxidative DNA damage. The myocardial reduced glutathione (GSH) level was preserved by ebselen. Ebselen markedly enhanced myocardial heat shock protein (HSP) 72 expression. The cardioprotective effect of ebselen-induced HSP72 was confirmed by MTT assay in isolated cardiomyocytes using KNK437, a novel HSP inhibitor. In conclusion, an oral administration of ebselen 24 h before I/R provided excellent cardioprotective effects, at least in part through HSP72 induction and GSH preservation.

Effects of MCI-186 upon neutrophil-derived active oxygens.

Abstract Reactions of 3-methyl-1-phenyl-2-pyrazoline-5-one (MCI-186) with hypochlorous acid and superoxide were analysed by spectrophotometry and mass spectrometry. The results were applied to the neutrophil system to evaluate the scavenging activity of neutrophil-derived active oxygen species by MCI-186. MCI-186 reacted rapidly with hypochlorous acid (1 × 106 M−1s−1) to form a chlorinated intermediate, followed by a slow conversion to a new spectrum. MCI-186 consumed 3 moles of hypochlorous acid and did not react with superoxide. The newly synthesized fluorescence probes, 2-[6-(4′-amino)-phenoxy-3H-xanthen-3-on-9-yl]benzoic acid (APF) and 2-[6-(4′-hydroxy)phenoxy-3H-anthen-3-on-9-yl]benzoic acid (HPF) successfully detected neutrophil-derived active oxygens (Setsukinai K, Urano Y, Kakinuma K, Majima HJ, Nagano T. Development of novel fluorescence probes that can reliably detect reactive oxygen species and distinguish specific species. J Biol Chem 2003; 278: 3170–3175). The rate constants for the reaction of hypochlorous acid with MCI-186 and fluorescence probes was in the order of MCI-186 > APF > HPF. Fluorescence due to the oxidation of APF and HPF was observed with the stimulated neutrophils. The result that the intensity from APF oxidation was higher than that from HPF oxidation is compatible with reports that APF selectively reacts with hypochlorous acid. Fluorescence due to oxidation of both APF and HPF decreased when the reactions were carried out in the presence of a fluorescence probe and MCI-186 in a dose-dependent manner. These results indicate that MCI-186 effectively scavenges neutrophil-derived hypochlorous acid and other active oxygens.

Visit-to-visit variability and seasonal variation in blood pressure: Combination of Antihypertensive Therapy in the Elderly, Multicenter Investigation (CAMUI) Trial subanalysis

Abstract Background: Combination antihypertensive therapy with an angiotensin receptor blocker (ARB) and a calcium channel blocker (CCB) or diuretics is common. This subanalysis investigated blood pressure (BP) variability in patients receiving ARB-based combination therapy. Methods: In a prospective, randomized, open-label trial, hypertensive outpatients (≥65 years) who did not achieve their target BP with ARB monotherapy switched to losartan 50 mg/hydrochlorothiazide 12.5 mg (ARB + D) or ARB plus amlodipine 5 mg (ARB + C) for 12 months. Clinic BP and heart rate (HR), measured every 3 months, visit-to-visit variability and seasonal variation were evaluated. Results: No significant between-group differences in average, maximum, or minimum systolic or diastolic BP, or HR, were found. Visit-to-visit BP variability (systolic) was significantly higher in the ARB + D group than in the ARB + C group. When each group was subdivided into two seasonal groups (summer and winter), no significant between-group differences in BP were found. Multivariate regression analyses showed a tendency toward negative correlation between outdoor temperature and urinary albumin:creatinine ratio and estimated glomerular filtration rate at 12 months in the ARB + D group. Conclusion: Combination therapy with an ARB plus a CCB may be preferable to that with an ARB plus diuretics for decreasing BP variability. As for seasonal variability, both treatments can be used safely regardless of season.

Combination of antihypertensive therapy in the elderly, multicenter investigation (CAMUI) trial: results after 1 year.

Objective: Combination therapy with angiotensin receptor blockers (ARBs) and calcium channel blockers or diuretics is common for hypertensive patients. This study aimed to determine which combination is better for elderly hypertensive patients. Methods: In this prospective, randomized, open-label trial, hypertensive outpatients aged at least 65 years who had not achieved their target blood pressure (BP) with standard ARB dosages were randomly assigned to receive either a fixed-dose combination of losartan (50 mg) and hydrochlorothiazide (12.5 mg) (ARB+D; n = 72) or a combination of amlodipine (5 mg) and the typical dosage of ARBs (ARB+C; n = 68) to evaluate the change in the BP, laboratory values and cognitive function. Results: At 3 months, the SBP/DBP was found to have significantly decreased from 156/83 ± 15/11 mmHg to 139/76 ± 14/10 mmHg in the ARB+D group and 155/83 ± 11/10 mmHg to 132/72 ± 14/10 mmHg in the ARB+C group. The BP reduction efficacy was greater in the ARB+C group than in the ARB+D group. At 6 months, the SBP/DBP reached the same level in both groups. At 12 months, the urine albumin/creatinine ratio was significantly decreased from the geometric mean of 17.1 to 9.6 mg/g in the ARB+D group, whereas it was increased from 19.8 to 23.7 mg/g in the ARB+C group. Conversely, the estimated glomerular filtration rate tended to show a decrease in the ARB+D group. There was no significant difference in mini-mental state examination after 1 year. Conclusion: ARB+amlodipine (5 mg) yielded a greater BP reduction, whereas ARB+HCTZ (12.5 mg) resulted in a greater reduction in the albuminuria, suggesting that each combination therapy is advantageous in a different manner for elderly hypertensive patients.

Impaired Glutathione Redox System Paradoxically Suppresses Angiotensin II-Induced Vascular Remodeling

Background Angiotensin II (AII) plays a central role in vascular remodeling via oxidative stress. However, the interaction between AII and reduced glutathione (GSH) redox status in cardiovascular remodeling remains unknown. Methods In vivo: The cuff-induced vascular injury model was applied to Sprague Dawley rats. Then we administered saline or a GSH inhibitor, buthionine sulfoximine (BSO, 30 mmol/L in drinking water) for a week, subsequently administered 4 more weeks by osmotic pump with saline or AII (200 ng/kg/minute) to the rats. In vitro: Incorporation of bromodeoxyuridine (BrdU) was measured to determine DNA synthesis in cultured rat vascular smooth muscle cells (VSMCs). Results BSO reduced whole blood GSH levels. Systolic blood pressure was increased up to 215±4 mmHg by AII at 4 weeks (p<0.01), which was not affected by BSO. Superoxide production in vascular wall was increased by AII and BSO alone, and was markedly enhanced by AII+BSO. The left ventricular weight to body weight ratio was significantly increased in AII and AII+BSO as compared to controls (2.52±0.08, 2.50±0.09 and 2.10±0.07 mg/g respectively, p<0.05). Surprisingly, the co-treatment of BSO totally abolished these morphological changes. Although the vascular circumferential wall stress was well compensated in AII, significantly increased in AII+BSO. The anti-single-stranded DNA staining revealed increasing apoptotic cells in the neointima of injured arteries in BSO groups. BrdU incorporation in cultured VSMCs with AII was increased dose-dependently. Furthermore it was totally abolished by BSO and was reversed by GSH monoethyl ester. Conclusions We demonstrated that a vast oxidative stress in impaired GSH redox system totally abolished AII-induced vascular, not cardiac remodeling via enhancement of apoptosis in the neointima and suppression of cell growth in the media. The drastic suppression of remodeling may result in fragile vasculature intolerable to mechanical stress by AII.

Conifer-Derived Monoterpenes and Forest Walking.

Conifer and broadleaf trees emit volatile organic compounds in the summer. The major components of these emissions are volatile monoterpenes. Using solid phase microextraction fiber as the adsorbant, monoterpenes were successfully detected and identified in forest air samples. Gas chromatography/mass chromatogram of monoterpenes in the atmosphere of a conifer forest and that of serum from subjects who were walking in a forest were found to be similar each other. The amounts of α-pinene in the subjects became several folds higher after forest walking. The results indicate that monoterpenes in the atmosphere of conifer forests are transferred to and accumulate in subjects by inhalation while they are exposed to this type of environment.

Respiratory function in healthy ever-smokers is impaired by smoking habits in a dose-dependent manner

BACKGROUND There is limited information about the respiratory function of ever-smokers without lung disorders. We sought to assess the effects of smoking habits on respiratory function in subjects without lung disorders. METHODS Subjects were recruited from among patients without any evidence of respiratory disorders who visited rural primary care clinics. Each participant was asked to answer a questionnaire that included questions smoking history. Their forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured. RESULTS We analyzed 802 subjects (364 men and 438 women). The means of the lambda-mu-sigma method derived z-score of FEV1 (zFEV1) both in current-smokers and ex-smokers were lower than that in never-smokers. The mean zFEV1 in the ever-smokers with more than 30 pack-years of smoking history were lower than that in the ever-smokers with less smoking history. Univariate analysis showed that there were significant negative correlations between pack-years and zFEV1 both in the ex-smokers and current-smokers. There was no significant correlation between the duration of smoking cessation and zFEV1 in the ex-smokers. CONCLUSIONS Our data suggests that respiratory function in healthy ever-smokers is decreased based on smoking habits in a dose-dependent manner. Even after a long period of smoking cessation, the decreased respiratory function seems to be maintained in ex-smokers.

PS 14-43 CHRONOTHERAPY WITH AN ARB AND CCB COMBINATION: COMPARISON OF THE MORNING AND BEDTIME ADMINISTRATION OF OLMESARTAN AND AZELNIPINE

Objective: Recently, great attention has been focused on chronotherapy and bedtime administration for uncontrolled hypertension. The present study aimed to determine which type of chronotropic administration is better for ARB-based combination therapies. Design and Method: We conducted a prospective, cross-over trial in hypertensive outpatients not achieving target blood pressures. Ten participants (61 ± 15 years) were assigned to switch treatment to a morning ARB (olmesartan 20 mg)+bedtime CCB (azelnidipne 16 mg) (group AC), morning CCB+bedtime ARB (group CA), or morning fixed dose combination of an ARB+CCB (group FD). We measured the average BP (ABP), daytime BP (DBP) and nighttime BP (NBP) with ambulatory BP monitoring (ABPM) of the three groups, and compared those values with each home blood pressure (HBP) measurement. We also measured the heart rate (HR), central blood pressure (CBP), and augmentation index (AI). We further measured the changes in the BP, albuminuria, and laboratory values. Results: There were no significant differences among the groups regarding each of the BP parameters, HR, CBP, and AI. However, there was a decreasing tendency of the average BP and nighttime BP in group AC, and decreasing tendency of the CBP and AI in group FD. Regarding the coeffcient variant of the SBP in the ABPM, group AC had the lowest value of the three groups. There was no significant difference regarding the urine albumin/creatine ratio. Conclusions: The morning ARB+bedtime CCB administration was effective in controlling the nighttime to morning BP control, whereas a morning fixed dose combination of an ARB+CCB was effective in controlling the CBP and AI. The application of chronotherapy with ARB and CCB combinations would be useful for a better BP control.