Ichiyo Oshima

Effect of transection on choline acetyltransferase, thyrotropin releasing hormone and substance P in the cat cervical spinal cord

The effects of a transection on the choline acetyltransferase activity, the thyrotropin releasing hormone and substance P contents in the cat cervical spinal cord have been investigated. Seven days after the hemitransection at the C1 level, the grey matter of the C6-7 levels of the spinal cord were dissected for the biochemical measurements. The choline acetyltransferase activity and the thyrotropin releasing hormone content remained unchanged in any regions in the grey matter following the high cervical transection. On the other hand, the substance P content was decreased by approx. 70% in the ventral horn. These results suggest that the fibers originating the supraspinal structures and terminating in the grey matter of the spinal cord, contain the substance P-releasing fibers, whereas there seems to be little cholinergic or thyrotropin releasing hormone-containing fibers.

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.

Effect of poly(ADP-ribose) synthetase inhibitor administration to streptozotocin-induced diabetic rats on insulin and glucagon contents in their pancreas

This study was conducted in order to clarify whether the poly(ADP-ribose) synthetase inhibitors, nicotinamide and 3-aminobenzamide, have any influence upon the content and physicochemical properties of insulin and glucagon in streptozotocin (STZ)-treated rat pancreas. STZ-treated rats received intraperitoneal injection of 350 mg/kg nicotinamide or 50 mg/kg 3-aminobenzamide 15 min before and 180 min after the administration of STZ and once a day thereafter for 23 weeks. The blood glucose levels and body weight of nicotinamide- and 3-aminobenzamide-treated rats did not differ from those of the control rats at the end of the experiment. The insulin content in poly(ADP-ribose) synthetase inhibitor-treated rat pancreas was restored partially and reached approximately 60% of the control level, while the glucagon content did not differ from that in the normal rats. Treatment with poly(ADP-ribose) synthetase inhibitor resulted in no alteration in the physicochemical properties of extracted insulin and glucagon. Immunohistological examination of the pancreas revealed that insulin- and glucagon-containing cells in the islets in the poly(ADP-ribose) synthetase inhibitor-treated rat appeared to be normalized. These results suggest that poly(ADP-ribose) synthetase inhibitor normalizes the function but not the insulin content of B cells and that it does not act on A cells in STZ-treated rat pancreas. Restoration of the insulin content would be large enough to keep the function of B cells normal.

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.

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

SummaryA 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<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<0.001). These results indicate that glycation of lens protein is parallel with the severity of diabetes in rats.

Radioimmunoassay of Human Pancreatic Amylase with Monoclonal Antibody

A monoclonal antibody (E-21) was obtained that specifically binds to human pancreatic amylase and shows negligible cross-reaction with human salivary amylase. Using this antibody a radioimmunoassay was developed for pancreatic amylase in human serum. The assay was shown to be sensitive (detectable up to 7 mg/L), reproducible, and specific for pancreatic amylase. In normal subjects, the mean concentration of serum pancreatic amylase determined by this method was 36·3 mg/L with a 95% confidence range of 16·5 to 79·2 mg/L. A good correlation was observed between the concentrations of immunoreactive pancreatic amylase (IR-PA) and enzymatic activities in 20 serum samples (r = 0·97). The concentration of serum IR-PA was below the detectable limit in pancreatectomised patients, and was greatly increased in patients with acute pancreatitis; the latter was accompanied by parallel changes in total enzymic activity. In patients with mumps, the serum IR-PA level was within the normal range whereas the total enzymic activity was elevated.

Endocrine Function Before and After Treatment in Patients with Anorexia Nervosa

In order to investigate changes in endocrine function, various tests were performed on eleven patients with anorexia nervosa. In two of them, endocrine function before and after treatment was also studied. The responses of plasma LH and FSH to LH-RH were decreased in the patients as were plasma LH-RH, and LH and FSH responses to the oral administration of clomiphene citrate. In more than half of the cases, plasma TSH showed a delayed response to TRH. The basal levels of plasma GH were elevated, and plasma GH responses to hypoglycemia or 1-arginine were lowered in half of the patients. Plasma GH showed a paradoxical rise after glucose load in three out of six cases. Plasma IRI responses to 1-arginine load were decreased in some cases, but plasma IRG responses to 1-arginine were rather excessive. Plasma IRI after glucose load showed low or delayed responses in most of the cases. After the body weight was increased to normal levels by the treatment, pituitary and pancreatic endocrine functions were normalized. These findings indicate that hypothalamic function is primarily impaired in this disease and causes nutritional disorder followed by the dysfunction of some endocrine organs. Such a possibility could be supported by the improvement of endocrine function after body weight has been recovered.

Endocrinological Studies on Hyperprolactinemia during Sleep

Clinical findings and plasma concentrations of pituitary hormones during sleep were measured in 15 normal subjects and 58 patients to study the cause and the clinical significance of hyperprolactinemia. Thirteen of 58 cases (22.4%) showed hyperprolactinemia with 2SD values higher than the control values. PRL showed episodic secretion during sleep in all cases. Sleep-associated augmentation of PRL, more than 150% over the value during waking, was not found in 3 cases (5.2 %). Hyperprolactinemia observed during sleep was classified into three types, but there was no relationship among the type, underlying diseases and PRL response to TRH. Six of the 13 cases with hyperprolactinemia showed abnormal secretion of Gn: 3 cases of hypersecretion and 3 cases of insufficient secretion. Excessive and independent secretion of PRL and TSH was observed in patients with primary hypothyroidism during sleep. These results suggest as follows; 1) Measurement of plasma PRL levels during sleep reflects morphological and functional abnormality in the central nervous system which regulates PRL secretion, 2) Hyperprolactinemia in children may be accompanied with abnormal rhythm of Gn secretion, 3) No synchronization of PRL release with TSH release may indicate that PRF differs from TRH, and 4) Hyperprolactinemia should be taken into consideration in childhood since symptoms of hyperprolactinemia do not appear easily.