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S Mashiko

Publications and source records attributed to S Mashiko.

30 records · Page 2Linked to original sources
PubMed1994

Enhancement of endothelium-dependent relaxation in the aorta from stroke-prone spontaneously hypertensive rats at developmental stages of hypertension.

1. Endothelium-dependent relaxation (EDR) in aortic rings from young (8 weeks) and adult (16 weeks and 20 weeks) stroke-prone spontaneously hypertensive rats (SHRSP) was investigated in comparison with age-matched Wistar-Kyoto rats (WKY). 2. At 8 weeks, acetylcholine (3 x 10(-9)-10(-5) mol/L) and ionomycin (4 x 10(-8)-10(-6) mol/L)-induced EDR in SHRSP aortae was significantly enhanced compared to that in WKY aortae. Mechanical denudation of the endothelium completely abolished, and pretreatment of aortae with NG-monomethyl L-arginine (1 mmol/L), an inhibitor of nitric oxide formation, greatly reduced the relaxation in both strains. Indomethacin (10(-5) mol/L), a cyclo-oxygenase inhibitor that blocks the production of endothelium-derived contracting factors, did not significantly alter the relaxation by acetylcholine at this age. There was no difference in endothelium-independent relaxation of denuded aortae by sodium nitroprusside (10(-9)-10(-6) mol/L) and 8-bromoguanosine 3', 5'-cyclic monophosphate (10(-6)-10(-3) mol/L). 3. In adult SHRSP with established hypertension, however, the acetylcholine (10(-8)-10(-5) mol/L)-induced relaxation markedly diminished at any of the concentrations tested compared to that observed in 8 weeks old SHRSP and WKY at 8-20 weeks of age. This finding differed from other observations where the relaxation in SHRSP was impaired only at higher concentrations of acetylcholine. Indomethacin pretreatment of aortae from 20 week old SHRSP restored acetylcholine-induced EDR to a level comparable with that in age-matched WKY.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1990

The first observation of O2- generation in in situ lungs of rats treated with drugs to induce experimental acute respiratory distress syndrome.

To investigate O2- generation in in situ lungs of rats treated with drugs to induce experimental acute respiratory distress syndrome, phorbol myristate acetate (PMA) or endotoxin were injected into rats, who had been continuously infused with 2(methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo[1,2-alpha]pyraz in-3-one (MCLA) and the chemiluminescence in in situ lung was detected by a sensitive photon counter. In PMA-treated rats, two phases of chemiluminescence over non-specific chemiluminescence were observed. The first phase luminescence was sensitive to Cu-Zn superoxide dismutase, while the second phase chemiluminescence was less sensitive to Cu-Zn superoxide dismutase. Similar chemiluminescence was detected in the rats treated with endotoxin instead of PMA, but not in neutropenic rats.

Animals↗
PubMed1990

Augmentation of superoxide generation in phagocytosing murine peritoneal macrophages by dietary restriction.

The effects of dietary restriction on the generation of superoxide anion (O2-) in phagocytosing mouse peritoneal macrophages (MPs) were investigated. MPs obtained from diet-restricted mice generated larger amount of O2- during phagocytosis of opsonized zymosan than those from unrestricted mice. This augmentation of the O2- generation was not inhibited by the protein kinase C (PKC) inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7). However, the augmentation was clearly disappeared when the calmodulin (CaM) antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) was added. These results strongly suggest that the augmentation of O2- generation in phagocytosing MPs by dietary restriction is due to the increased activity of CaM in the MPs, and that PKC is not involved in the augmentation. It is thought that one of the major factors for the reduced incidence of tumor and infection in diet-restricted animals is the augmentation of O2- generation in MPs.

Animals↗
PubMed1989

Generation of O2- and tyrosine cation-mediated chemiluminescence during the fertilization of sea urchin eggs.

Sea urchin eggs emit light in the visible region during their fertilization. Judging from the chemiluminescence spectra, one of the excited species generated is considered to have originated from a tyrosine cation radical-mediated reaction. Chemiluminescence probes such as luminol or a cypridina luciferin analog (See text) are useful for detecting the ovoperoxidase +H2O2 reaction associated with membrane hardening and O2- generation, respectively, during fertilization of sea urchin eggs.

Animals↗
PubMed1989

Plasma insulin levels in Japanese and Japanese-American men with type 2 diabetes may be related to the occurrence of cardiovascular disease.

Sixty-eight second-generation Japanese-American (Nisei) men 45-74 years old and 26 Tokyo Japanese men 40-72 years old with type 2 diabetes were given 75 g glucose by mouth, and their venous blood levels of glucose and insulin were measured at 0, 30, 60, 90, 120, and 180 min. Blood glucose levels were similar for the two groups but the Nisei had higher levels of insulin at all time points (P less than 0.006). The Nisei men had a higher mean body mass index (P less than 0.001) and the Tokyo men had had diabetes for a longer duration (P less than 0.001). Data were also compared following selection of a subgroup of Nisei men (n = 39) with a diabetes duration of 2-25 years, making this group more similar to the Tokyo men with respect to this variable. The Nisei still had significantly higher plasma insulin levels. Because of a significant (P less than 0.01) positive correlation between plasma insulin and body mass index in Nisei, but not in Tokyo men, data comparing the Nisei subgroup and Tokyo men were re-examined by analysis of covariance. With an adjustment for body mass index in the analysis, all differences in plasma insulin, except for the fasting insulin level, were no longer significant between the Nisei and Tokyo men, suggesting that body mass index was responsible for these differences.

Aged↗
PubMed1989

Dietary restriction augments superoxide generation in mouse peritoneal macrophages: an investigation using a chemiluminescence probe specific for superoxide anion.

It has not been clarified whether dietary restriction alters macrophage functions, although the augmentation of T cell functions by dietary restriction is well known. Forty percent dietary restriction on 9-week-old male C3H/He mice caused a decrease of body weight. However, one of the major macrophage functions, the generation of superoxide anion (O2), was augmented in proteose peptone-elicited peritoneal macrophages (MPs) from diet-restricted mice. This increase was more striking when the cells were stimulated by 12-o-tetradecanoylphorbol-13-acetate (TPA), which directly activated protein kinase C, than by opsonized zymosan which binded to receptors on the cells. These results strongly suggest that the augmentation of O2- generation in MPs by dietary restriction is due to the increased activity of protein kinase C which phosphorylate and activate O2-generating enzyme system NADPH oxidase. It is thought that one of the major factors for the reduced incidence of tumor and infection in diet-restricted animals is the augmentation of O2-generation in MPs.

Animals↗
PubMed1986

Familial disorder with increased number of insulin receptors: a new category of insulin receptor abnormality.

We found a family in which 6 of 13 family members had extremely high insulin binding to their erythrocytes. The specific binding values of these patients were 3- to 4-fold higher (22.8-28.6% of added [125I]insulin) than normal (mean +/- SD, 7.1 +/- 0.8%; r = 44). Scatchard analysis revealed that in each patient increased insulin binding was due to increased binding capacity, with little change in affinity. In all patients, reticulocyte counts were within the normal range. From the pedigree analysis, the pattern of inheritance was considered to be autosomal dominant. The propositus was more extensively studied. His mononuclear leukocytes and Triton X-100-solubilized preparations of erythrocyte ghosts also had high (approximately 3-fold) insulin-binding capacity compared to that of normal subjects. In contrast, the number of ouabain-binding sites and kinetics of sugar transport were normal. From these findings, we propose a new type of inherited abnormality of the insulin receptor.

Adult↗
PubMed1984

Reciprocal changes of plasma apo AI and apo E levels in streptozotocin-induced diabetic rats.

Amounts of plasma lipids, apolipoprotein AI (apo AI) and apolipoprotein E (apo E) were measured in streptozotocin-induced diabetic rats. Plasma triglyceride and cholesterol levels of diabetic rats were not significantly different from those of control rats. Plasma apo AI levels of diabetic rats were significantly higher than those of control rats (78.2 +/- 29.3 vs 27.2 +/- 3.4 mg/dl, P less than 0.001), while plasma apo E levels of diabetic rats were significantly lower than those of control rats (4.2 +/- 1.0 vs 13.9 +/- 5.3 mg/dl, P less than 0.001). Insulin treatment (12U/day) of diabetic rats decreased plasma apo AI levels significantly (treated: 32.8 +/- 3.4, untreated: 48.7 +/- 6.2, control: 28.5 +/- 2.4 mg/dl) and normalized plasma apo E levels (treated: 16.1 +/- 1.7, untreated: 5.4 +/- 0.7, control: 15.8 +/- 1.3). Insulin injection (4U/day) to normal rats did not cause any changes in both plasma apo AI and apo E levels. The data indicate that diabetes is not always accompanied by hyperlipidemia, however this inevitably carries apoprotein abnormalities characterized by the high plasma apo AI and low apo E levels, which are reversible with insulin treatment. The changes in the levels of plasma apo AI and apo E could be related to the development of atherosclerosis in diabetes.

Animals↗
PubMed1983

Reduction of C-peptide secretion in noninsulin-dependent diabetic patients with long duration of insulin treatment.

We examined the responses of serum free C-peptide immunoreactivity (CPR) during a 100 g oral glucose tolerance test (OGTT) on diabetic patients undergoing different kinds and durations of treatment. None of the patients were ketosis-prone or had any history of nephropathy and they all developed diabetes when over the age of 30. The sigma serum free CPR (the sum of serum free CPR values during OGTT) of group A (duration of insulin treatment was less than 5 years, N = 10) was found to be higher than that of group B (duration of insulin treatment was 5 years or more, N = 10) (p less than 0.005). On the other hand, the sigma serum free CPR of group C (treatment with an oral hypoglycemic agent for less than 5 years, N = 9) was not statistically different from that of group D (treatment with an oral hypoglycemic agent for 5 years or more, N = 11). There were no statistical differences between group A and group B in age at onset, duration of diabetes, daily insulin dose, relative body weight index, serum creatinine or sigma BG (the sum of blood glucose values during OGTT). Just before the start of insulin treatment, there were no significant differences between the two groups in the following: 1. fasting blood glucose values (all 10 patients measured in group A and 9 patients in group B) 2. blood glucose and plasma immunoreactive insulin (IRI) responses (7 patients measured in group A and 6 in group B). Among those with plasma IRI measured on the previous occasion, sigma serum free CPR was found to be higher in group A than in group B (p less than 0.025) at the time of the present study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Measurement of rate constants for quenching singlet oxygen with a Cypridina luciferin analog (2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo [1,2-a]pyrazin-3-one) and sodium azide.

The rate constants for [1O2] [MCLA] and [1O2] [NaN3] were measured by quenching the near-infrared emission (1 delta g----3 sigma g) in steady state with MCLA and NaN3, respectively. 1O2 was constantly generated by energy transfer to O2 from Ar laser-excited Rose Bengal. The Stern-Volmer plots yielded the second-order rate constants of 2.94 x 10(9) M-1 S-1 and 3.83 x 10(8) M-1 S-1 for quenching 1O2 with MCLA and NaN3 in water at pH 5.4, respectively. The 1O2 + MCLA reaction emitted light with maximum at 465 nm at pD 4.5 identical to the O(2-) + MCLA reaction.

Azides↗