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Biomedical subjects

M Fujiwara

Publications and source records attributed to M Fujiwara.

At least 937 records · Page 52Linked to original sources
PubMed1975

Extradiol cleavage of 3-substituted catechols by an intradiol dioxygenase, pyrocatechase, from a Pseudomonad.

Pyrocatechase (catechol 1,2-oxidoreductase (decyclizing), EC 1.13.11.1), a ferric ion-containing dioxygenase from Pseudomonas arvilla C-1, catalyzes the intradiol cleavage of catechol with insertion of 2 atoms of molecular oxygen to form cis,cis-muconic acid. The enzyme also catalyzed the oxidation of various catechol derivatives, including 4-methylcatechol, 4-chlorocatechol, 4-formylcatechol (protocatechualdehyde), 4,5-dichlorocatechol, 3,5-dichlorocatechol, 3-methylcatechol, 3-methoxycatechol, and 3-hydroxycatechol (pyrogallol). All of these substrates gave products having an absorption maximum at around 260 nm, which is characteristic of cis,cis-muconic acid derivatives. However, when 3-methylcatechol was used as substrate, the product formed showed two absorption maxima at 390 and 260 nm. These two absorption maxima were found to be attributable to two different products, 2-hydroxy-6-oxo-2,4-heptadienoic acid and 5-carboxy-2-methyl-2,4-pentadienoic acid (2-methylmuconic acid). The former was produced by the extradiol cleavage between the carbon atom carrying the hydroxyl group and the carbon atom carrying the hydroxyl group and the carbon atom carrying the methyl group; the latter by an intradiol cleavage between two hydroxyl groups. Since these products were unstable, they were converted to and identified as 6-methylpyridine-2-carboxylic acid and 2-methylmuconic acid dimethylester, respectively. Similarly, 3-methoxycatechol gave two products, namely, 2-hydroxy-5-methoxycarbonyl-2,4-pentadienoic acid and 5-carboxy-2-methoxy-2,4-pentadienoic acid (2-methoxymuconic acid). With 3-methylcatechol as substrate, the ratio of intradiol and extradiol cleavage activities of Pseudomonas pyrocatechase during purification was almost constant and was about 17. The final preparation of the enzyme was homogeneous when examined by disc gel electrophoresis and catalyzed both reactions simultaneously with the same ratio as during purification. All attempts to resolve the enzyme into two components with separate activities, including inactivation of the enzyme with urea or heat, treatment with sulfhydryl-blocking reagents or chelating agents, and inhibition of the enzyme with various inhibitors, proved unsuccessful. These results strongly suggest that Pseudomonas pyrocatechase is a single enzyme, which catalyzes simultaneously both intradiol and extradiol cleavages of some 3-substituted catechols.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed1975

Automutilation induced by clonidine in mice.

Clonidine (2-(2,6-dichlorophenylamino)-2-imidazoline hydrochloride, St155, Catapres), after administration of a single large dose, was found to induce automutilation in mice housed individually in the absence of objects to bite. This abnormal behavior was not significantly altered with chronic administration of the drug, and showed no behavior induced by the same drug in mice caged in groups.

Animals↗
PubMed1975

Gamma-aminobutyric acid receptor on vascular smooth muscle of dog cerebral arteries.

Gamma-aminobutyric acid (GABA) had a relaxant effect on dog cerebral arteries which was blocked only by picrotoxin, a known antagonist of GABA receptors. Other agents, adrenoceptor and ganglion blocking agents, atropine, reserpine, tetrodotoxin and ouabain, had no effect on the inhibitory action suggesting the existence of GABA receptors in the vascular smooth muscle of dog cerebral arteries.

Aminobutyrates↗
PubMed1975

Circumvention of immunological tolerance to bovine serum albumin by diazotized antigen as a function of hapten density.

Immunological tolerance was induced in adult guinea pigs by the injection of 10-100 mg of centrifuged BSA. The tolerant state was readily circumvented, in terms of both humoral antibody response and delayed hypersensitivity, by the immunization with sulfanilated BSA with different degree of conjugation. The level of anti-BSA and intensity of the skin reactions to BSA evolked in animals with circumvented tolerance responding to the challenge immunization with sulfanilated BSA were inversely related to the number of sulfanil groups per BSA molecule. On the basis of the experimental data, the mechanism of the circumvention of tolerance is discussed.

Aniline Compounds↗
PubMed1975

[Behavior pharmacology of maprotiline, a new antidepressant].

The effect of maprotiline (N-methyl-9, 10-ethanoanthracene-9 (10H)-propylamine) on animal behavior was investigated in mice and rats and compared with those of amitriptyline and imipramine. Maprotiline inhibited reserpine hypothermia in mice and tetrabenazine ptosis in rats, while it potentiated the effects of methamphetamine, L-DOPA and apomorphine in mice, in a similar manner to that of amitriptyline and imipramine. Maprotiline was more potent than anitriptyline and imipramine in antagonizing haloperidol-induced catalepsy as well as in suppressing muricide induced by either olfactory bulbectomy or delta-9-tetrahydrocannabinol in rats. Maprotiline potentiated anesthesia induced by thiopental or ether in mice to a lesser degree than did amitriptyline, and failed to counteract the lethal effect of physostigmine or oxotremorine tremor in mice, indicating that this drug has no central anti-cholinergic effect. Maprotiline markedly inhibited hyperemotionality of the rat with either septal lesions or olfactory bulb ablations, suggesting that it does have a tranquilizing effect. Inhibition of conditioned avoidance response of the rat in the shuttle box and reduction of methamphetamine group toxicity with maprotiline were similar to those with amitriptyline. Maprotiline exaggerated pentetrazol convulsion, decreased muscle tone and impaired coordinated motor activity in mice to a much lesser degree than amitriptyline and imipramine. LD50 of maprotiline was approximately twice that of imipramine and three times that of amitriptyline. These results indicate that maprotiline is a new type of antidepressant, has a low toxicity and shares both potent antidepressant and some tranquilizing effect, without possessing central anticholinergic action.

Aggression↗
PubMed1975

Mechanism of termination of immunological tolerance.

Mice were rendered tolerant to bovine serum albumin (BSA) by means of cyclophosphamide. The effect of immunization with sulphanilated BSA with different degrees of hapten conjugation on this tolerant state was examined. It was shown that the tolerant state was readily terminated with sulphanilated BSA with a low degree of chemical modification. Specificities of antibodies produced in response to sulphanilated BSA were tested by absorption and PHA inhibition test, demonstrating that there were antibodies directed to new antigenic determinant(s) on sulphanilate BSA as well as those reacting with unmodified BSA. To explore the cellular mechanism of termination, lethally irradiated syngeneic mice were reconstituted with thymus-derived cells (T cells) together with bone marrow-derived cells (B cells) from either normal mice or mice rendered tolerant to BSA, and were immunized with BSA or sulphanilate BSA. Tolerance termination was clearly observed in the recipient mice reconstituted with tolerant T cells plus normal B cells. From these experimental data, it was proposed that the termination was effected by means of the co-operation of the T-cell population tolerant to BSA but capable of responding to new antigenic determinant(s) on sulphanilated BSA, with non-tolerant B cells responsive to BSA.

Animals↗