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Biomedical subjects

S Kurihara

Publications and source records attributed to S Kurihara.

At least 127 records · Page 7Linked to original sources
PubMed1989

Effects of isoprothiolane and phytosterol on serum lipids and adipose tissue of rats given saturated fat diet.

Rats received hardened-tallow (HT) diet continuously for 18 weeks. After 8 weeks of feeding, isoprothiolane (50 mg/kg) or phytosterol (20 mg/kg) was administered orally to the rats once a day consecutively for 10 weeks. In the rats given isoprothiolane, serum high density lipoprotein (HDL) phospholipid concentration increased. Decreased serum very low density lipoprotein (VLDL) cholesterol concentration was seen in the rats given phytosterol. Isoprothiolane increased the level of palmitoleic acid (16:1), while phytosterol increased the level of palmitic acid (16:0) in phospholipid of adipose tissue. In the frozen tissue sections, the multiple crystals were seen in fat cells of the rats fed HT diet. Less crystals were seen in the rats given either drug when compared with the rats fed HT diet without drug.

Adipose Tissue↗
PubMed1989

Left ventricular regional function after acute anterior myocardial infarction in diabetic patients.

To elucidate the pathophysiological role of diabetes mellitus in determining the left ventricular regional function of the noninfarcted area, 55 patients with acute Q wave anterior myocardial infarction (MI) were studied. The regional ejection fraction of the noninfarcted area was obtained by radionuclide angiocardiography and was used to estimate the left ventricular regional function of the noninfarcted area. Multiple regression analysis was performed to determine the important variables contributing to the regional ejection fraction based on 10 clinical variables: age, sex, QRS score, diabetes mellitus, hypertension, smoking, postinfarction angina, body mass index, serum cholesterol, and coronary atherosclerosis. A high QRS score (P less than .001) and the association of diabetes mellitus (P less than .05) were the important factors contributing to regional left ventricular dysfunction. The regional ejection fraction and QRS score had an inverse linear relationship in the diabetic and nondiabetic groups, and the regional ejection fraction was significantly lower in diabetic patients at every QRS score (P less than .05). The association of hypertension, severity of coronary atherosclerosis, serum cholesterol level, age, and body mass index did not differ between diabetic and nondiabetic patients, which indicates that diabetes mellitus was not mediated through these atherogenic traits. Thus, diabetes mellitus is another discrete cause of regional left ventricular dysfunction of the noninfarcted area after acute MI.

Diabetes Mellitus, Type 2↗
PubMed1989

[Observation on calcification of necrotic tissue in pressure side of periodontal membrane incident to experimental tooth movement].

In an orthodontic point of view, it is said that necrotic tissues cause a standstill of tooth movement until they disappear and that term of the standstill is related to the size of the necrotic tissues. Although remodeling processes of a periodontal membrane in compressed area were reported as series of phenomena like degeneration, coagulative necrosis, calcification and histiolysis, there is no direct evidence that the necrotic tissue is really calcified. The purpose of this study is to clarify histologically whether the necrotic tissues in the periodontal membrane are calcified or not and to know when appearance and disappearance of the calcification occur during an experimental tooth movement. Twenty eight rats were used for this study. For the experimental tooth movement, the orthodontic elastics were inserted into the interproximal space between the maxillary right 1st and 2nd molars during 1, 2, 3, 5, 7 and 14 days respectively (Waldo's method). The periodontal tissues were observed on undecalcified sections by vital staining in which oxytetracycline (3 mg/kg), alizarin red (8 mg/kg) and calcein (0.8 mg/kg) were applied as well as by contact micro radiography (CMR). Findings were as follows: 1) After 2 days of tooth movement, a part of the periodontal membrane in compressed area showed fluorescence by vital staining and was radiopaque by CMR. This means that the necrotic tissues are really calcified at least after 2 days of experimental tooth movement. 2) After 7-14 days no calcified tissue could be found in the periodontal membrane. The calcified tissues may disappear under processes of resorption in this area.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Steroid hormone production in testis, ovary, and adrenal gland of immature rats irradiated in utero with 60Co.

Pregnant rats received whole-body irradiation at 20 days of gestation with 2.6 Gy lambda rays from a 60Co source. Endocrinological effects before maturation were studied using testes and adrenal glands obtained from male offspring and ovaries from female offspring irradiated in utero. Seminiferous tubules of the irradiated male offspring were remarkably atrophied with free germinal epithelium and containing only Sertoli cells. Female offspring also had atrophied ovaries. Testicular tissue obtained from intact and 60Co-irradiated rats was incubated with 14C-labeled pregnenolone, progesterone, 17 alpha-hydroxyprogesterone, and androstenedione as a substrate. Intermediates for androgen production and catabolic metabolites were isolated after the incubation. The amounts of these metabolites produced by the irradiated testes were low in comparison with the control. The activities of delta 5-3 beta-hydroxysteroid dehydrogenase, 17 alpha-hydroxylase, C17,20-lyase, and delta 4-5 alpha-reductase in the irradiated testes were 30-40% of those in nonirradiated testes. Also, the activities of 17 beta- and 20 alpha-hydroxysteroid dehydrogenases were 72 and 52% of the control, respectively. In adrenal glands, the 21-hydroxylase activity of the irradiated animals was 38% of the control, but the delta 5-3 beta-hydroxysteroid dehydrogenase activity was comparable to that of the control. On the other hand, the activity of delta 5-3 beta-hydroxysteroid dehydrogenase of the irradiated ovary was only 19% of the control. These results suggest that 60Co irradiation of the fetus in utero markedly affects the production of steroid hormones in testes, ovaries, and adrenal glands after birth.

Adrenal Glands↗
PubMed1988

Mechanism of action of 2, 3-butanedione 2-monoxime on contraction of frog skeletal muscle fibres.

The mechanism of the inhibitory effect of 2,3-butanedione 2-monoxime (BDM) on contraction of frog skeletal muscles was studied using skinned fibres and aequorin-injected intact fibres. The tension development of skinned fibres directly activated with calcium was strongly inhibited by BDM. This agent also had effects on the sarcoplasmic reticulum in the skinned preparations, suppressing the calcium pump function and enhancing the activity of the 'calcium-induced calcium release' mechanism. In electrically stimulated intact fibres, although BDM slightly suppressed the elevation of the intracellular calcium ion concentration, this effect was so weak that it would not explain the strong inhibitory effect of the agent on the tension development by the intact fibres. It was concluded that the tension reducing effect of BDM on intact fibres was due mainly to its direct action on the contractile system. The mode of this action of BDM was further examined with skinned fibres in view of its effects on the maximum shortening speed and isometric tension in low MgATP environments.

Animals↗
PubMed1988

Inactivation of rat testicular NADPH-cytochrome P-450 reductase by 2,4,6-trinitrobenzenesulfonate.

Rat testicular NADPH-cytochrome P-450 reductase was inactivated by treatment with 2,4,6-trinitrobenzene sulfonate (TNBS) or with 2',3'-dialdehyde derivatives of 5'-ATP and NADP+. The inactivation rates were dependent on reaction time and followed pseudo-first order kinetics. The rate of inactivation of cytochrome c reducing activity by TNBS was faster than that of reducing activities for K3Fe(CN)6 and for dichlorophenol indophenol (DCPIP). Cytochrome c and DCPIP prevented NADPH-cytochrome P-450 reductase from inactivation by TNBS, but NADP(H) protected to a lesser extent. Stoichiometry indicated that two residues of amino acid modified with TNBS were essential for the enzyme activity. The 2',3'-dialdehyde derivatives of 5'-ATP and NADP+ were specific ligands for the modification of lysine residues, whereas TNBS would possibly modify residues of lysine and/or cysteine. By differential and sequential modification by 5,5'-dithio-bis(2-nitrobenzoic acid), TNBS and dithiothreitol, the residues of lysine and cysteine were identified in the active site of NADPH-cytochrome P-450 reductase. These results suggest that lysyl and cysteinyl residues are located at or near the active region of NADPH-cytochrome P-450 reductase from the rat testicular microsomal fraction.

Animals↗
PubMed1987

Effects of beta-adrenoceptor stimulation on intracellular Ca transients and tension in rat ventricular muscle.

Effects of beta-adrenoceptor stimulation on intracellular Ca2+ transients and tension were explored in rat ventricular muscles injected with aequorin. Adrenaline (0.05-5.0 microM) and isoproterenol (0.05-1.0 microM) increased the peak of twitch tension and accelerated relaxation. The former effect depended on Ca2+ concentration in Tyrode's solution ([Ca2+]o) and the stage of the experiment. Low concentrations of these drugs added to normal Tyrode's solution containing 2 mM [Ca2+]o did not potentiate twitch tension in the early stage of the experiments. These drugs increased the peak of the aequorin light signal and slightly accelerated the falling phase of the light especially the tail. Effects of dibutyryl-cyclic AMP (DB-cAMP)(0.1-5.0 mM) and 3-isobutyl-1-methylxanthine (IBMX) (0.01-0.5 mM) were qualitatively similar to those of adrenaline and isoproterenol. Isoproterenol applied at the peak of Na-deficient contracture decreased tension without significantly changing the light signal; similar results were obtained in the presence of ryanodine (1 microM). The results were interpreted as follows: The increase of intracellular cAMP induced by beta-adrenoceptor stimulation facilitated Ca2+ uptake by sarcoplasmic reticulum (SR) and decreased Ca2+ sensitivity of contractile elements. Faster relaxation induced by cAMP was considered to be due to the decrease of Ca2+ sensitivity of contractile elements and faster Ca2+ uptake by SR. The slightly faster falling phase of light transient might be due to the faster Ca2+ uptake by SR, which predominates over the slower fall of [Ca2+]i induced by the decreased Ca2+ sensitivity of the contractile element.

1-Methyl-3-isobutylxanthine↗
PubMed1987

Effects of caffeine on intracellular calcium concentrations in frog skeletal muscle fibres.

1. The mechanism of twitch potentiation by caffeine was studied in single muscle fibres dissected from m. tibialis anterior of Rana temporaria. Fibres were injected with a Ca2+-sensitive photo-protein, aequorin, and the resultant light signal and tension were simultaneously recorded. 2. In twitch responses triggered every 60 s, peaks of light and tension were maintained at a constant level. Low concentrations of caffeine (0.2-0.4 mM) potentiated twitch tension accompanied by a slight increase in light signal. 3. Although peak twitch tension was dose-dependently potentiated by caffeine, light peaks were suppressed at relatively higher concentrations of caffeine (0.6-1.5 mM) with prolonged decay of the light and tension signals. 4. Light intensity in the resting muscle (resting glow) was elevated by caffeine (0.2-1.5 mM) dose-dependently without detectable tension development. This effect of caffeine was suppressed by 0.5-1.0 mM-procaine or 10 mM-adenine, inhibitors of Ca2+-induced Ca2+ release. 5. In caffeine-treated preparations, peaks of light and tension were augmented by application of procaine (0.5-1.0 mM). Adenine (10 mM) affected the light signal in essentially the same way as procaine, but the effect varied from fibre to fibre. 6. From these results, the following hypothesis is proposed: low concentrations of caffeine directly induce Ca2+ release from sarcoplasmic reticulum (s.r.) in in the resting state, and facilitates Ca2+ release from s.r. induced by the action potential during twitch. At relatively higher concentrations of caffeine (0.6-1.5 mM), rise of resting [Ca2+]i (intracellular free Ca2+ concentration) before activation might be an important factor in twitch potentiation by caffeine. If the rise of resting [Ca2+]i induced by caffeine is inhibited by procaine and the content of Ca2+ in s.r. is well maintained, caffeine could facilitate Ca2+ release by depolarization and thus potentiate twitch tension.

Action Potentials↗
PubMed1987

Serum cholesterol level in normal people: association of serum cholesterol level with age and relative body weight.

Serum cholesterol level was studied in normal subjects in Kasakake Village. The serum cholesterol levels increased significantly with age, from the third to the fifth decade in males and from the third to the seventh decade in females. Thereafter, the levels were maintained in males while declined in females. The mean peak values (+/- SD) were 178 +/- 31 mg/100 ml in males and 207 +/- 37 mg/100 ml in females. The presumptive values of the zero-year-old obtained from the regression lines calculated from the plot of serum cholesterol values against age were 129 mg/100 ml and 112 mg/100 ml in males and females respectively. Throughout the age-range examined in females, the serum cholesterol level was well correlated with the relative body weight determined with modified Broca's method. A similar, but less obvious correlation was demonstrated in males. However, there was not comparable change in the relative body weight against the trend of the serum cholesterol level in both sexes. In the babies normally delivered with full term, the mean cholesterol level (+/- SD) in the umbilical cord blood serum was 65 +/- 13 mg/100 ml and it increased to 150 +/- 46 mg/100 ml during one to three months after birth which was very close to the presumptive values obtained from the regression lines in the adults. There also was significant correlation between the cholesterol value and the body weight. It is concluded that in normal people, age and relative body weight are major and independent determinants of serum cholesterol level from the start of their life.

Aged↗