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Biomedical subjects

T Okabayashi

Publications and source records attributed to T Okabayashi.

At least 73 records · Page 4Linked to original sources
PubMed1982

Ethyl beta-carboline-3-carboxylate reverses the diazepam effect on cerebellar cyclic GMP.

The administration of ethyl beta-carboline-3-carboxylate (beta-CCE), a ligand for benzodiazepine receptors, did not affect the cerebellar cyclic GMP level in mice, but giving beta-CCE together with diazepam significantly inhibited the diazepam-induced decrease in cyclic GMP. The fact that no antagonism was observed when beta-CCE was given 15 min before the diazepam treatment indicates that beta-CCE is short-acting. These biochemical observations support the conclusions from behavioral and electrophysiological studies which indicated that beta-CCE is a short-acting antagonist of benzodiazepines.

Animals↗
PubMed1982

Comparison of the effects of GABA and chloride ion on the affinities of ligands for the benzodiazepine receptor.

The effects of gamma-aminobutyric acid (GABA), Cl- ion, and their combination were examined on the affinity for the benzodiazepine (BDZ) receptor of various ligands including BDZ's, putative endogenous ligands, and CL218872. When the binding was performed at 0 degrees, the ligands could be classified into four types according to the action of the modulators. The affinity of the first type including some BDZ's increased with GABA, Cl- ion, or their combination while that of the second type consisting of 3-hydroxy-benzodiazepines, CL218872, and inosine increased only with GABA. In the third type, designated as the beta-carboline type, only Cl- ion increased the affinity of the ligands. The fourth inactive type included pentylenetetrazole and nicotinamide and the affinities of these ligands were not affected by GABA or Cl- ion. At 37 degrees, although GABA still retained the property to increase the affinity of prototype compounds of the first and second types, the effect of C1- ion became somewhat ambiguous. Comparison of the present results with published data on the pharmacological and electrophysiological activities of the ligands suggested that the compounds with affinity increased by GABA act as BDZ-mimetics, while those belonging to types 3 and 4 act as antagonists. Also, our results seem to throw some additional light upon the relationships among the benzodiazepine receptor, the GABA receptor, and the chloride ionophore.

Animals↗
PubMed1979

Antihypertensive effect of intravenously and orally administered bunitrolol (Kö 1366).

1. Hypotensive effect of O-[3-(tert, butylamino-2-hydroxypropoxy]-benzonitrile hydrochloride (bunitrolol, Kö 1366) was examined by intravenous administration of 5 mg to 20 cases of essential hypertension and by longterm oral administration of 15-30 mg to 27 cases of essential hypertension. 2. It was found that bunitrolol given either i.v. or p.o., produced a significant decrease of systolic, diastolic and mean blood pressure at rest. 3. Inhibitory effect of bunitrolol on exercise-induced increase of blood pressure was remarkable, while there was little inhibitory effect on the cold pressor-induced one. 4. Bunitrolol decreased blood pressure and lowered plasma renin activity in high renin hypertensive patients, suggesting that the hypotensive mechanism based, at least in part, on its capacity of inhibiting renin secretion. 5. However, the main hypotensive mechanism of bunitrolol seemed, in the case of i.v. use, related to the cardiac inhibitory action. Regarding the hypotensive mechanism of this drug in the long-term use, further investigation will be required.

Administration, Oral↗
PubMed1977

Effects of various types of vagotomy on gastrin release and gastric secretion in dogs.

Changes of serum gastrin and acid secretory responses to histamine, feeding and insulin stimulation before and after various types of vagotomy (TV, SV, SPV and SAV) were investigated in Heidenhain pouch dogs. The following results were obtained: (1) The acid secretory response to histamine slightly decreased after various types of vagotomy. (2) The responses of serum gastrin and acid secretion to feeding were elevated after various types of vagotomy. (3) The serum gastrin response to insulin was highly increased after SPV and TV, whereas the response was slightly increased and decreased after SV and SAV, respectively. The acid secretion in response to insulin was increased only after SPV, while it was decreased after the other types of vagotomy. These results led to the condition that there might be no correlation between serum gastrin and acid secretory responses to feeding and insulin after various types of vagotomy.

Animals↗
PubMed1977

A radioimmunoassay method for 1-beta-D-arabinofuranosyluracil using antibodies directed against 1-beta-D-arabinofuranosylcytosine.

Above pH 7.0 1-beta-D-arabinofuranosyluracil (ara-U) shows marked pH-dependent cross-reactivity with antibodies directed towards 1-beta-D-arabinofuranosylcytosine. Since this peculiar phenomenon has not been observed with other nucleosides and nucleotides thus far tested, it is probably the result of base-catalyzed tautomerism of ara-U to its enolic form which renders it more structurally similar to 1-beta-D-arabinofuranosylcytosine. By performing the radioimmunoassay at both pH 6.2 and 8.6 we could determine 1-beta-D-arabinofuranosylcytosine and ara-U simultaneously. This method for ara-U assay is simple, fairly reliable, and applicable to blood level studies.

Animals↗
PubMed1977

A radioimmunoassay for 1-beta-D-arabinofuranosyluracil with reference to cross-reactivity of 1-beta-D-arabinofuranosylcytosine with an antibody.

Antibodies directed against 1-beta-D-arabinofuranosyluracil have been produced in rabbits by immunization with a conjugate of 1-(5-O-succinyl-beta-D-arabinofuranosyl)uracil with human serum albumin. Two of four antibodies so obtained showed high specificity for 1-beta-D-arabinofuranosyluracil and allowed the development of a sensitive and reliable radioimmunoassay for this substrate. On the other hand, one antibody had a high affinity for 1-beta-D-arabinofuranosylcytosine. The binding of 1-beta-D-arabinofuranosylcytosine to this antibody was practically constant between pH 5.2 and 9.0, whereas 1-beta-D-arabinofuranosyluracil binding was affected drastically by pH. The pH-binding profile for 1-beta-D-arabinofuranosylcytosine and 1-beta-D-arabinofuranosyluracil was reminiscent of the specificity of ara-C-specific antibodies, which we previously obtained after immunization of rabbits with 1-(5-O-succinyl-beta-D-arabinofuranosyl)cytosine as a hapten.

Antibodies↗
PubMed1977

A radioimmunoassay for 1-beta-D-arabinofuranosylcytosine.

A rapid and reliable radioimmunoassay method for 1-beta-D-arabinofuranosylcytosine (ara-C) has been developed using antibody induced in rabbits, [3H]ara-C, and a Millipore filtration technique. The sensitivity of this assay was such that ara-C, 0.02 mug/ml, in plasma could be detected, and the assay was practically free from interference by deoxycytidine, cytidine, 1-beta-D-arabinofuranosyluracil, and other nucleosides, as well as from various antibiotics. Blood levels of ara-C in C57BL X DBA/2F1 mice were determined after injection of 1-(3-O-octanoyl-beta-D-arabinofuranosyl) cytosine. Relatively high ara-C levels could be maintained for a fairly long period. Plasmas of mouse, rat, and rabbit contained high esterase activity which hydrolyzed the 3'-octanoyl group in 1-(3-O-octanoyl-beta-D-arabinofuranosyl)cytosine, whereas this activity was relatively low in dog and human plasmas.

Animals↗