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Biomedical subjects

M Takai

Publications and source records attributed to M Takai.

At least 109 records · Page 6Linked to original sources
PubMed1982

Measurement of plasma renin activity by a simple solid phase radioimmunoassay.

A solid phase RIA in which an antibody adsorbed onto polystyrene balls was developed to determine PRA. Complete inhibition of converting enzyme and angiotensinase during enzymatic reaction was achieved by phenyl methyl sulfonyl fluoride and EDTA combination. Pepstatin A was found to be an effective agent to block angiotensin I generation during the RIA, and the sample can be directly incubated at room temperature for RIA without any special treatment to inhibit renin activity. The intra- and interassay coefficients of variation (CV) were 5.5-6.9% and 3.7-8.2%, respectively. The recovery was 91.9-117% of added angiotensin I. The assay is sufficiently sensitive and reliable for routine use and correlates acceptably (r = 0.996) with an established RIA. The antibody-adsorbed balls were compared to the soluble antibody with respect to thermodynamic parameters. It was found that the apparent equilibrium constant of the antibody-adsorbed ball was reduced to approximately 1/2 sec of soluble antibody, which was predominately due to the decrease in unitary entropy change by adsorption.

Angiotensin I↗
PubMed1982

The predominance of flunisolide in the topical use of anti-inflammatory steroids.

Local and systemic anti-inflammatory effects of topically applied flunisolide on hind footpad edema induced by subplantar injection of 1 microgram of serotonin in mice were evaluated in comparison with those of three related steroids. The order of the potency for local anti-inflammatory effect observed in the foot injected with the steroids was flunisolide, dexamethasone, betamethasone valerate and beclomethasone dipropionate in decreasing order. In contrast, potency for systemic effect of flunisolide observed on the opposite foot was rather weak compared with its strong local effect. When steroids were administered orally, the order of the anti-inflammatory potency as dexamethasone, beclomethasone dipropionate, flunisolide and betamethasone valerate in decreasing order. All of the data demonstrate that flunisolide is highly active in topical use, while systemically it is relatively weak, especially by oral administration. Those characteristics of flunisolide could be attributable to its rapid metabolic inactivation in the liver, which suggests a great advantage of its topical use in the clinical medicine.

Administration, Topical↗
PubMed1982

[Gastrin radioimmunoassay with polyethylene glycol method].

125I-labelled gastrin with high immunological activity and high specific radioactivity of 22.2 approximately 25.9 GBq (600 approximately mCi)/mg (0.5 iodine atom/1 gastrin molecule) was prepared by chloramine-T method using the amount of 100 molar ratio of chloramine-T to gastrin. As results of gastrin radioimmunoassay with polyethylene glycol (PEG) method, intra- and interassay coefficient of variation (C.V.) were 3.6 approximately 7.6% and 5.7 approximately 10.4%, respectively. The average recoveries of 2 levels of gastrin added to serum samples were 104 +/- 11.9% and 105 +/- 9.7%. The correlation coefficient of gastrin values obtained with dextrancoated charcoal (DCC) method and present method was r = 0.973. Antibody used in this study have a characteristic to strongly recognize the tyrosin residue at 12 position and the methionyl residue at 15 position on gastrin (1-17).

Antibody Specificity↗
PubMed1981

[A simple solid phase radioimmunoassay for plasma renin activity (author's transl)].

A solid phase radioimmunoassay (RIA) in which plasma renin activity (PRA) can be measured in a single test tube throughout enzymatic reaction and determination of angiotensin-I (A-I) generated was developed. Two hundred micro 1 of plasma samples was incubated with phenylmethylsulfonyl fluoride (PMSF) and ethylenediamine tetraaceticacid (EDTA) at pH 6.0 or 7.4 at 37 degrees C for 1 hr, then the generated A-I was determined by solid phase RIA under 3 hr of incubation time at room temperature. An antibody absorbed onto polystyrene beads was used for B/F separation of RIA. The combination of PMSF and EDTA gave significant inhibition of angiotensinase and converting enzyme. Pepstatin A, proteolytic enzyme inhibitor, was found to be effective to block the renin activity during the incubation for RIA at room temperature. Recoveries of A-I added at two levels of 1.0 4.0 ng/ml to plasma sample incubated at 37 degrees C for 1 hr were 102 +/- 28.6% and 105 +/- 15.2%, respectively. Intra-assay precision (CV) ranged from 2.5 to 10.3% and inter-assay from 7.0 to 13.7% with four pooled sera. PRA obtained under enzymatic reaction of pH 6.0 showed approximately twice as much as that of pH 7.4. The assay correlated closely with the other established solid phase radioimmunoassay kit (r = 0.996). Normal values of PRA were 1.03 +/0 0.78 ng/mg/hr (n = 66) at supine position and 1.33 +/- 1.15 ng/ml/hr at upright position. The method for the measurement of PRA, described in this paper, can be clinically used as one of convenient methods froms its simplicity and reproducibility.

Female↗
PubMed1981

Acetylcholine release from the myenteric plexus of guinea-pig ileum by prostaglandin E1.

Release of acetylcholine (ACh) by prostaglandin E1 from the nerve terminals of the guinea-pig longitudinal muscle strip was studied in order to reveal the effect of PGE1 on myenteric plexus activity. The ACh released was collected in the presence of physostigmine (2.1 microgram ml-1) and choline (0.1 microgram ml-1) at 38 degrees C. Five to 100 ng ml-1 PGE1 enhanced the release dose-dependently. The effect was maintained during the presence of PGE1 in the organ bath, while rapid tachyphylaxis was observed with the ACh-releasing action of nicotine. Tetrodotoxin or morphine almost completely inhibited the effect of PGE1 on ACh release. Hexamethonium, in a concentration which completely blocked the effect of nicotine, partially inhibited the effect of PGE1. In the late phase of nicotine action, the tissue was still sensitive to PGE1 despite the continued exposure to nicotine. These data suggest the presence in the myenteric plexus of PG receptors which can increase ACh release.

Acetylcholine↗
PubMed1980

Synthesis and antitumor activity of analogues of the antitumor antibiotic chartreusin.

First isolated in 1953 from a fermentation broth, chartreusin (1) has received renewed interest as a result of substantial antitumor activities recently demonstrated in several murine test systems. Poor water solubility frustrated formulation attempts, and rapid biliary excretion observed in mice made 1 an improbable candidate for clinical development but an excellent candidate for an analogue synthesis program. From a common intermediate, which was prepared from 1, three analogues were synthesized wherein the disaccharide moiety of 1 was systematically replaced with fucose (6), glucose (7), and the disaccharide maltose (8). Each of the three analogues had a cytotoxic potency against cultured L1210 cells which was equal to, or better than, that shown by 1. Based on the structural similarity with the parent, an improved water solubility, and a favorable accessibility through synthesis, maltoside 8 was choe P388 leukemia, 8 showed reproducible activity comparable to chartreusin at similar dose levels. Although 8 caused no observable toxic effects at therapeutic dose levels when given ip, neither 1 nor 8 produced active indications when administered subcutnaeously.

Animals↗