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Biomedical subjects

K Takeuchi

Publications and source records attributed to K Takeuchi.

At least 1,351 records · Page 75Linked to original sources
PubMed1979

Mucosal gastrin receptor. I. Assay standardization and fulfillment of receptor criteria.

Using iodinated gastrin with demonstrable biological activity, this study has shown that optimal specific gastrin binding occurs in rat gastric mucosal 270--30,000 g membrane preparations after an incubation period of 30 min at 30 degrees C (pH 7.4) with a protein concentration of 150--200 micrograms per assay tube. The gastrin binding was shown to be saturable with an equilibrium Ka of approximately 0.25 X 10(10) M-1 and an equilibrium Kd of approximately 4 X 10(10) M. The binding capacity was approximately 4 fmol/mg protein. Specific gastrin binding was shown to be present in the oxyntic gland and duodenal mucosa and to be absent from the antral mucosa, liver, spleen, and kidney. In order to decrease the specific binding of gastrin by 50% the competitors in order of potency are 15-Leu G-17 greater than cholecystokinin greater than caerulein greater than pentagastrin; secretin did not display a response similar to the other four competitors tested, indicating that its inhibition may be non-competitive. Fasting decreased the binding capacity of the gastrin receptor and refeeding brought the receptor levels back to control range; this result parallels the decrease seen in serum gastrin after fasting and the return to normal levels with refeeding. This suggests that rat gastric mucosal gastrin receptors may exhibit autoregulation. This study is the first to meet all the criteria for establishing the existence of a mucosal gastrin receptor.

Animals↗
PubMed1979

Mucosal gastrin receptor. II. Physical characteristics of binding.

Gastrin binding to rat gastric mucosal membrane preparations revealed a linear Scatchard plot, suggesting the existence of a single class of binding sites. Further studies revealed the absence of a positive cooperative effect. Because the system appeared to satisfy the conditions for Michaelis-Menten type kinetics, the determination of a Kd of approximately 3.6 X 10(-10) M was justified. These studies also demonstrated the efficacy of the specific activity of our iodinated gastrin. Trypsin treatment abolished specific binding of gastrin to the membrane preparation, indicating the protein nature of the receptor. The importance of maintaining extremely low temperatures during the incubation and wash period is demonstrated by the decrease in both the rate and the amount of dissociation at 0 degrees C compared with 30 degrees C.

Animals↗
PubMed1979

Effects of three-day oral cholecystography on serum iodothyronines and TSH concentrations: comparison of the effects among some cholecystographic agents and the effects of iopanoic acid on the pituitary-thyroid axis.

The effects of repeated doses of oral cholecystographic agents on serum thyroxine (T4), 3,3',5-triiodothyronine (T3), 3,3',5'-triiodothyronine (rT3) and thyrotrophin (TSH) concentrations were studied in 37 euthyroid male subjects. Iobenzamic acid, tyropanoic acid, iopanoic acid, and ipodate sodium, in a dosage of 3 g for 3 days, respectively, induced a significant decrease in serum T3 and an increase in rT3 within 24 h after the initial dose, followed by an increase in TSH and a slight increase in T4. The extent of the changes in rT3 varied between the agents, ipodate causing the greatest change, but without any relation to the changes in T3 or T4. Responses of serum T4, T3, rT3 and TSH concentrations to exogenous thyrotrophin-releasing hormone (TRH) and bovine TSH were also studied before and after 3-day doses of iopanoic acid. In 11 subjects given iopanoic acid, the response to TSH to TRH (500 micrograms, iv) was increased but the T3 response was unchanged. A dose of TSH (10 U.S.P. units, im) caused a significant increase in serum T3 and a decrease in TSH concentrations in 5 subjects both before and after cholecystography. It is thus suggested that in euthyroid subjects given multiple doses of oral cholecystographic agents, (1) the primary and consistent events are the reciprocal changes of serum T3 and RT3, although the extent of the changes is not coordinately reciprocal; (2) the responsiveness of the pituitary thyrotrophs and thyroid to TRH is preserved; and (3) the high basal and TRH-induced TSH in the serum may be ascribed to the decrease in the serum T3 concentration.

Administration, Oral↗
PubMed1979

Presystolic pulmonary valve opening in constrictive pericarditis.

Right heart pressure tracings were studied in 5 cases with constrictive pericarditis. The pressure of the A-wave in the right atrium of these cases was higher than the pulmonary arterial diastolic pressure. In addition, a presystolic wave appeared in the pulmonary arterial and the right ventricular pressure tracings, in coincidence with atrial systole. The pressure of this presystolic wave was similar to that of the right atrial A-wave. This suggests that the pulmonary valve opens following atrial systole, and then the blood flows into the pulmonary artery in the presystolic phase in patients with constrictive pericarditis. In 2 cases, pulmonary valve echograms were recorded. The a-dip in these 2 cases was as deep as 8.4 mm and 9.6 mm (1.8-4.1 mm with a mean of 2.80 mm for normal men), and its duration was prolonged to 0.17 sec and 0.18 sec (0.10-0.13 sec with a mean of 0.115 sec for normal men). In conclusion, such a deep and prolonged a-dip on pulmonary valve echogram is presumably a sign of presystolic pulmonary valve opening.

Adult↗
PubMed1979

[Mutagenicity test of antithyroid agent, methimazole--dominant lethal mutation test on male mice (author's transl)].

Mutagenicity test of Methimazole (MMI) was performed by means of dominant lethal mutation test in the male mice. Male mice were treated with a single s.c. injection of 45 mg/kg or 90 mg/kg MMI. Mean body weights were slightly decreased and mating rates were low immediately after treatment of MMI. Mean numbers of living implants at any periods examination up to 6 weeks after the treatment were compared with Salin Control, indicating lack of dominant lethality of MMI. On the other hand, EMS and MMC known mutagens and reference agents used in the present study, induced dominant lethalities at a single s.c. injection respectively.

Animals↗
PubMed1979

[Glioma in the aged (author's transl)].

Glioma is the most frequent primary brain tumor in the aged which is originally much less frequent comparing that of younger generations. A large majority of gliomas in the aged is malignant. Besides the result of operation and follow-up result have been heretofore reported as more unfavorable. Fourteen cases of glioma in the aged, over 60 years of age, including 7 glioblastomas, 6 anaplastic astrocytomas and one unspecified malignant glioma, have been reported. Preoperative period varied from one month to 15 years and in 6 cases the period was less than 3 months. Poor preoperative state especially disturbance of consciousness mostly due to a markedly increased intracranial pressure, observed in 71% of the cases. The malignant gliomas which were frequently seen among the aged might be transformed tumors of more benign gliomas which originated in the younger generations and developed slowly and silently. Unfavorable prognosis of glioma in the aged might be closely related to the histological nature and poor preoperative state. However, delay of making correct diagnosis and rapidly progressive onset both of which have been mentioned as the speciality of brain tumor in the aged, were not closely related to the unfavorable prognosis.

Aged↗
PubMed1979

Clinical studies of thyrotropin-releasing hormone tartrate (TRH-T) as a direct stimulant to the central nervous system.

Thyrotropin-releasing hormone tartrate (TRH-T) was administered in 17 cases of organic brain lesions and 2 cases of disturbed mental activity (psychical depression), and its effect, mainly on the level of consciousness and electroencephalogram, was examined. Ten consecutive administrations of 0.5--1.0 mg/day TRH-T, as TRH, resulted in improvement of disturbance of consciousness in 8 of 16 cases. This effect was not necessarily correlated with the degree of disturbance or the site of the lesion. Improvement was seen even in those cases where disturbance of consciousness had been fixed over a long period. The effect on the electroencephalogram was small and did not parallel the degree of improvement of the level of consciousness. Abnormal TSH and thyroid hormone values were not seen despite the continued administration of TRH-T. These results would appear to indicate that the continuous administration of TRH-T has a mild activating effect directly on the central nervous system, and not through the endocrine mechanism, and exerts no damage on the internal environment in vivo.

Adolescent↗
PubMed1979

[Pharmacokinetic analysis of ACNU in brain tumors (author's transl)].

In order to establish the standard of administration of ACNU against brain tumors, pharmacokinetic analysis of ACNU in tumor tissue, cystic fluid, cerebrospinal fluid and blood was performed. The sample specimens were obtained sequentially after intravenous administration of 1--2 mg/kg/BW of ACNU and quantitatively analysed by high-performance liquid chromatography in 3 cases of glioblastoma and each one case of astrocytoma, meningioma and brain metastasis. Concentrations of ACNU in blood was calculated by two compartment open model and those in cystic fluid was calculated by one compartment model using BMDP-3R program. The half-time in blood was 2.6--4.1 min, and its distribution was very fast. The penetration of ACNU into the tumor tissue was sufficient, because the central compartment was 23% and the tissue compartment was 77%. The transmission rate constant into the cyst was 1.8 and the elimination rate constant was 0.96. The maximum concentration in the cystic fluid 42 min after intravenous injection of 2 mg/kg/BW of ACNU was 0.27--0. 35 mg/dl. In conclusion, 3--4 mg/kg/BW of ACNU should be injected intravenously at one time.

Astrocytoma↗