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Biomedical subjects

S Kitagawa

Publications and source records attributed to S Kitagawa.

At least 361 records · Page 20Linked to original sources
PubMed1975

The synthesis and pharmacology of a novel benzodiazepine derivative, 1-(beta-methylsulfonylethyl)-5-(o-fluorophenyl)-7-chloro-1,3-dihydro-2H-1,4-benzodiazepin-2-one (ID-622).

The pharmacological profiles of a new benzodiazepine derivative, 1-(beta-methylsulfonylethyl)-5-(o-fluorophenyl)-7-chloro-1,3-dihydro-2H-1,4-benzodiazepin-2-one (ID-622), were shown. In anti-convulsant test, ID-622 was more potent than diazepam and medazepam when tested with pentylenetetrazol or bemegride, but was less potent than diazepam tested with strychnine or MES in mice. Taming effects of ID-622 were more potent than diazepam in both electroshock- and isolation-induced fighting mice tests, but were less potent in both septal rats and O.B. rats tests. ID-622 had only a weak influence on the spontaneous locomotor activity, and did not cause the righting reflex loss. In EEG, ID-622 increased fast activity and depressed hippocampal I-waves and amygdala after-discharge in cats. Acute toxicity of ID-622 was very low.

Animals↗
PubMed1975

Comparative metabolic study of nimetazepam and its desmethyl derivative (nitrazepam) in rats.

1. Nimetazepam distributed more rapidly in the brain than its desmethyl derivative (nitrazepam). The brain concentration of the active metabolites of the former was about twice that of the latter at 1h after oral administration. 2. At least four kinds of reactions were involved in the biotransformation of nimetazepam and its desmethyl derivative (nitrazepam) : (i) demethylation at N-1, (ii) hydroxylation at C-3, (iii) reduction of the nitro group at C-7 to the amino group and (iv) subsequent acetylation of the amino group. 3. The 1-N-demethylation of nimetazepam was slow compared with the other three reactions. 4. Nimetazepam was rapidly hydroxylated at C-3, while the 3-hydroxylation of its desmethyl derivative (nitrazepam) was very slow. 5. The reduction of the nitro group at C-7 and subsequent acetylation were important routes for the excretion of these drugs.

Acetylation↗
PubMed1975

Electrophysiological and behavioral effects of 1-methyl-5-(o-fluorophenyl)-7-chloro-1,3-dihydro-2H-1,4-benzodiazepin-2-one (ID-540) in cats and rabbits.

Effects of ID-540 (1-methyl-5-(o-fluorophenyl)-7-chloro-1,3-dihydro-2H-1,4-benzodiazepin-2-one) on the central nervous system were evaluated electrophysiologically and behaviorally in cats and rabbits. The reference compound used was diazepam. 1. ID-540 as well as diazepam produced muscle relaxation, grooming, facilitation of appetite and suppression of defensive behaviors. ID-540 made the animals lie on their side during sleep, but diazepam did not. 2. Though more effectively inducing an increase in fast activity and a decrease in frequency of hippocampal theta-waves than diazepam, ID-540 scarcely affected the amplitude of subcortical EEG (hippocampus, amygdala and hypothalamus), which diazepam decreased in cats. 3. ID-540 and diazepam increased the waking phase and decreased the paradoxical sleep phase. 4. ID-540 and diazepam at a dose of 1 mg/kg decreased the duration of amygdala after-discharge for 1 h in cats. Diazepam increased the duration of the after-discharge after it had been decreased, but ID-540 did not. ID-540 did not affect the duration of hippocampal after-discharge whereas diazepam prolonged it. 5. ID-540 depressed more effectively the hippocampal arousal response to stimulation of the ventro-medial hypothalamus than did diazepam in rabbits. 6. ID-540 depressed amygdalo-hippocampal evoked potential in cats. 7. ID-540 did not affect norepinephrine-induced pressor response but reduced hypothalamic pressor response in cats.

Animals↗
PubMed1968

Electron microscopic investigations of actomyosin as a function of ionic strength.

Natural actomyosin at micro = 0.6 appears in various forms, including the regular arrowhead structures originally reported by Huxley (1), when it has been stained negatively with 1% uranyl acetate. In addition to the arrowheads, thin whiskers, 700-1200 A in length and 20 A in width, attached to the arm of the arrowheads have been demonstrated. The dimensions of the whiskers and arms of the arrowheads are practically the same as those of the light meromyosin (LMM) and the heavy meromyosin (HMM) moieties of the single myosin molecule, respectively. Changes in the electron microscopically distinguishable elements during aggregation of natural actomyosin on reduction of the ionic strength have been observed. At micro = 0.4, partial aggregation of the LMM whiskers begins to result in some parallel alignment of the arrowhead-bearing filaments (acto-HMM). In the range of micro = 0.3-0.1, the LMM whiskers merge into smooth filaments which are arranged alternatingly with arrowhead-bearing filaments. Thus, lateral aggregation of composite actomyosin filaments (acto-HMM + LMM whiskers) results with the LMM moieties as links. This view is supported by the following facts: (a) acto-HMM is devoid of whiskers and does not show lateral aggregation at micro = 0.1; (b) natural actomyosin digested with trypsin at micro = 0.6, which was followed by removal of LMM aggregates at low ionic strength, is essentially the same as acto-HMM at micro = 0.1; and (c) digestion with trypsin of natural actomyosin at micro = 0.2 for varying periods of time leads to a separation of arrowhead-bearing filaments from LMM aggregates.

Microscopy, Electron↗