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Biomedical subjects

I Oshima

Publications and source records attributed to I Oshima.

At least 55 records · Page 3Linked to original sources
PubMed1988

Specific radioimmunoassay of glucitol-lysine--application to lens proteins in streptozotocin-diabetic rats.

A radioimmunoassay using antibody against glucitol-lysine was developed to quantitate glycated proteins in the lens of diabetic rats. The amount of glycated protein was expressed as molar equivalents of reduced glycated hippuryl lysine (GlcRED-Hip-Lysine). Significant differences (p less than 0.01) were found in the amounts of glycated protein in the lenses of rats with streptozotocin-induced diabetes (3.92 +/- 0.59 nmol/mg protein, n = 5), those with streptozotocin-induced diabetes treated with insulin (2.94 +/- 0.36 nmol/mg protein, n = 4) and normal rats (1.23 +/- 0.22 nmol/mg protein, n = 5). There was a significant correlation between the concentration of glycated protein in the lens and the HbA1c level at the end of the 12 week experiment (r = 0.957, p less than 0.001). These results indicate that glycation of lens protein is parallel with the severity of diabetes in rats.

Animals↗
PubMed1988

Loss of the circadian rhythms of locomotor activity, food intake, and plasma melatonin concentration induced by constant bright light in the pigeon (Columba livia).

Locomotor activity and feeding activity were measured together with circulating levels of melatonin in pigeons which were exposed to constant bright light (LLbright, 2000 lux) following light-dark (LD) cycles. Although all the pigeons showed daily rhythms of locomotor activity, feeding activity, and melatonin levels under LD cycles, they lost all the rhythms in prolonged LLbright. Acute exposure to bright light (2000 lux) during darkness reduced plasma melatonin levels. The half-time for the suppression in melatonin levels was about 30 min after short-term light exposure. These results support the hypothesis that melatonin may control the circadian rhythms of locomotor activity and feeding activity in the pigeon.

Animals↗
PubMed1988

The measurement and analysis of circadian locomotor activity and body temperature rhythms by a computer-based system.

A new computer-based system for collection and analysis of circadian body temperature and locomotor activity rhythms is described. This system makes possible the simultaneous measurements of body temperature and locomotor activity rhythms from 16 animals kept in separate cages. Several programs were developed for measurement and analysis of the data. This system is available not only in the study of circadian rhythms but also in other biological studies where long-term recordings of rest-activity cycles and body temperature are required.

Animals↗
PubMed1988

Comparison of half-disappearance times, distribution volumes and metabolic clearance rates of exogenous glucagon-like peptide 1 and glucagon in rats.

The pharmacokinetics of glucagon-like peptide-1 (GLP-1) in vivo after bolus and continuous i.v. administrations of the peptide were compared with those of glucagon in rats. The half-disappearance time (t1/2) distribution volume (Vd) and metabolic clearance rate (MCR) of GLP-1 given as a bolus injection and by constant infusion, were, respectively, as follows: t1/2 (min), 47.7 +/- 14.5 and 39.5 +/- 15.5 (mean +/- S.D.); Vd (ml), 903.8 +/- 62.4 and 516.3 +/- 92.1 and MCR (ml kg-1 min-1), 27.4 +/- 10.8 and 18.6 +/- 8.6. These values differed significantly from the respective values for glucagon (t1/2, 3.3 +/- 0.6 and 5.8 +/- 1.0; Vd, 206.5 +/- 25.9 and 240.0 +/- 76.1; and MCR, 83.1 +/- 8.2 and 46.7 +/- 13.3). These findings demonstrate that GLP-1 is degraded more slowly than glucagon in vivo.

Animals↗
PubMed1988

Different responses of the circadian system to GABA-active drugs in two strains of mice.

Recent work in our laboratory has shown that sodium pentobarbital injections can induce phase-dependent phase shifts of the circadian rhythm of locomotor activity with the maximum advance at circadian time (CT) 8 and the maximum delay at CT0 in SK/Nga mice but no phase shifts in C57BL/6 mice. In the present study, the possibility that the differences in the effects of pentobarbital on the circadian rhythm may be due to different contributions of the GABA-ergic system to circadian organization in the two strains was tested by comparing the responses of SK mice with those of C57BL mice to muscimol (2 mg/kg), a GABA receptor agonist, and triazolam (25 mg/kg), which is thought to act by potentiating the action of GABA. The hypothesis that pentobarbital-induced phase shifts of SK mice are mediated by the GABA receptor system was also tested by observing whether the phase-shifting effects of pentobarbital were blocked by bicuculline (0.5 mg/kg), a selective antagonist of GABA, injected 3 min prior to pentobarbital (30 mg/kg). The results indicated that muscimol induced phase advances at CT8 and phase delays at CT0, and triazolam induced phase advances at CT8 in SK mice. No phase shifts were induced by any treatment in C57BL mice. These results suggest that the role of GABA-ergic systems in circadian organization may be different in SK and C57BL mice. In addition, bicuculline could block the phase-shifting effects of pentobarbital in SK mice, suggesting that the GABA receptor system may mediate phase-shifting effects of pentobarbital in SK mice.

Animals↗
PubMed1988

Asymptomatic hyperbromidaemia detected as pseudohyperchloridaemia measured with an ion selective electrode meter.

Six patients were found to have increased serum chloride concentrations when these concentrations were determined with an ion-selective electrode, but not when determined by continuous flow mercuric thiocyanate colorimetry or amperometric-coulometric titration. Their serum bromide levels of 1.8-8.0 mmol/l were much higher than those of 0.07-0.13 mmol/l in normal controls. The urinary bromide excretion, measured in two of these patients, was higher than that in normal subjects. No common symptoms or abnormalities in laboratory findings except hyperbromidaemia were found in these patients, who claimed not to have taken any drugs containing bromide. For determination of the incidence of subclinical hyperbromidaemia, the serum bromide concentrations were measured in sera of 1,323 outpatients sent to Tokushima University Hospital for routine measurements of blood chemistry over a one-month period. Five samples showed abnormally high bromide levels. It is concluded that subclinical hyperbromidaemia is not as rare as generally thought, though the aetiology of this state is unknown. Chloride determination with an ion-selective electrode can be used to screen for hyperbromidaemia, since increased levels of bromide ion result in apparently high chloride values.

Adult↗
PubMed1987

The phase relationship between the circadian rhythms of locomotor activity and circulating melatonin in the pigeon (Columba livia).

The phase relationship between the circadian rhythms of locomotor activity and circulating melatonin levels under LD 12:12 and constant dim light conditions (LLdim) was examined in pigeons. Our new radioimmunoassay technique had sufficient sensitivity to detect the concentration of melatonin from a small quantity of plasma, which enabled us to measure locomotor activity simultaneously with circulating melatonin rhythms from each individual pigeon. The relationship of phase between the two circadian rhythms in LLdim was the same as in LD. The rhythms of locomotor activity and melatonin levels free-run but maintain the relation of 180 degrees out of phase in LLdim. These results do not contradict the hypothesis that melatonin may entrain the circadian rhythm of locomotor activity in the pigeon.

Animals↗
PubMed1987

Effect of exercise training on insulin and glucagon release from perfused rat pancreas.

The effect of physical training on insulin and glucagon release in perfused rat pancreas was examined in the spontaneously exercised group running in a wheel cage an average of 1.4 km/day for 3 weeks and in the sedentary control group kept in the cage whose rotatory wheel was fixed on purpose. Pancreatic immunoreactive insulin (IRI) responses to glucose and arginine were reduced by 28% and 47.8% respectively in trained rats compared with untrained rats, while IRI content of the pancreas was similar in these two groups. The demonstrated decrease in insulin secretion of the beta-cell of the trained rats, in response to the glucose and arginine stimulations, may be functional in nature. On the other hand, neither pancreatic glucagon immunoreactivity (GI) response to glucose and arginine nor GI content of the pancreas was modified by exercise training. These results demonstrate that exercise training reduces IRI responses to glucose as well as to arginine stimulations, but does not modify any secretory response of pancreatic GI.

Animals↗
PubMed1984

Hypothalamic function in women during the first month post-partum.

Plasma LRH-immunoreactive substance in puerperal women was very low on days 5 and 10 post-partum and significantly increased between days 10 and 20 post-partum, but remained at a similar level on day 30 post-partum, which was significantly lower than that in eumenorrhoeic women on day 8 or 9 of the normal cycle. Although LRH administration did not significantly increase serum FSH on day 11 post-partum, daily injections of LRH from days 5 through 10 post-partum caused a significantly increased secretion of FSH on day 11 post-partum, both basally and in response to LRH. No significant difference was observed in serum oestradiol and Prl levels on day 11 post-partum between the two groups of women with and without LRH pre-treatment. It is concluded that the amount of hypothalamic LRH secretion may be small during the first month post-partum, and low basal FSH and unresponsiveness of the pituitary to LRH observed in the early puerperium may result from hypothalamic hypofunction.

Estradiol↗
PubMed1983

Kinetic study on disappearance of gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide (DN-1417) from plasma using a radioimmunoassay for DN-1417 isobutylamide.

Kinetic study of disappearance of gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide (DN-1417) from human plasma has been performed by a sensitive and specific radioimmunoassay (RIA) using antiserum against DN-1417 isobutylamide. Antibody against N-[2-hydroxy-4-(isobutylcarbamoyl)butyryl]-L-histidyl-L-prolinamide (DN-isobutylamide) did not cross-react with any other TRH-related peptides tested. DN-isobutylamide was radioiodinated with 125I by the chloramine T method and the product had a specific activity of about 160 microCi/microgram. The sensitivity of the RIA was 50 pg per tube, and the intra- and inter-assay coefficients of variation at concentrations of 1-10 ng/ml were 7.0-11.6%. DN-1417 in the plasma was converted to a stable form, DN-isobutylamide, by incubation with isopropanol-isobutylamine at room temperature for 2 h. DN-Isobutylamide was separated from 2-hydroxy-4-carboxybutyryl-L-histidyl-L-prolinamide (DN-COOH) using a SEP-PAKTM C18 cartridge before RIa. The recovery of DN-isobutylamide from plasma was 86.2-98.2%. The half-life, volume of distribution and plasma clearance rate of DN-1417 examined in 6 normal male volunteers by intravenous injection of 500 micrograms DN-1417 citrate were 11.5 +/- 5.6 min in the first phase and 89.5 +/- 33.5 min in the second phase, 25.3 +/- 10.0 liters and 745.8 +/- 278.6 1/d, respectively. These results indicate that RIA of DN-isobutylamide is useful for analysing DN-1417 metabolism in humans.

Adolescent↗