Biomedical subjects
Publications and source records attributed to K Tawara.
The specific thiol protease inhibitor, NCO-700, which is related to L-trans-epoxysuccinylpeptides, inhibited oxidant production by chemoattractant-stimulated rabbit polymorphonuclear leukocytes. NCO-700 could also scavenge active oxygen generated from sodium hypochlorite-hydrogen peroxide and hypoxanthine-xanthine oxidase systems.
The chronotropic response to a single oral dose of propranolol in 23 healthy subjects has been related to the plasma propranolol concentration and the density of beta-adrenoceptors on peripheral polymorphonuclear leucocytes. The percentage reduction in exercise-induced tachycardia was significantly correlated with the log plasma propranolol concentration within subjects but not between subjects. Taking the concentration of the active metabolite 4-hydroxypropranolol into account did not improve the interindividual correlation. The reduction in exercise-induced tachycardia was significantly correlated with the maximum binding density of (125I)-hydroxybenzylpindolol on polymorphonuclear leucocyte membrane fragments measured before medication. A response index (% reduction in exercise-induced tachycardia/plasma propranolol concentration) was correlated with the maximum binding density of (125I)-hydroxybenzylpindolol (pre-drug) at 2 h (rs = 0.72), 4 h (rs = 0.84) and 6 h (rs = 0.73) after dosing. The data suggest that interindividual variation in the response to propranolol after a single oral dose is determined by interindividual differences both in plasma propranolol and adrenoceptor density.
To find orally active antifungal agents, novel imidazolyl- and 1,2,4-triazolylpropanolones I and related compounds II-IV were synthesized. Compounds I were derived from ketones V (method A), alpha-diketone IX (method B), alpha-hydroxy ketones X (method C), alpha-chloro ketone XII (method D), and enones VI (method E). Diols II, synthesized from I with NaBH4, were cyclized to five-membered cyclic compounds III by using N,N'-carbonyldiimidazole, thionyl chloride, N,N'-(thiocarbonyl)diimidazole, bromochloromethane, 2,2-dimethoxypropane, and cyclohexanone dimethyl ketal. Diols IV were synthesized from I by Grignard reaction (method F), hydroxymethylation of X (method G), and reaction of ketones XXI with 1-[(trimethylsily)methyl]-1,2,4-triazole (method H). Compounds I-IV were examined for their antifungal activities in vitro by evaluation of broth dilution MIC values against three species of fungi and the inhibitory effect on pseudomycelium of Candida albicans, and they were examined for oral efficacy in vivo against subacute systemic candidiasis in mice and superficial dermatophytosis in guinea pigs. Compounds 2, 12, 38, 39, and 92 exhibited strong oral antifungal activity. An asymmetric synthesis and the structure-activity relationships of the compounds examined are discussed.
Carbonyl compounds I were subjected to an imidazole transfer reaction with N,N'-sulfinyldiimidazole or N,N'-carbonyldiimidazole to obtain the diimidazole II and the monoimidazole III. Various 1-vinylimidazoles IV, derived from o-hydroxyacetophenones by imidazole transfer reaction, were alkylated to furnish the title compounds V. The structure-activity relationships of these 1-vinylimidazole compounds V are described.
To find an antifungal agent other than those of the imidazole and triazole series, a new class of 1,2-disubstituted propenones I and II was prepared and tested for antifungal activity. Comparison of the structure-activity relationships showed that the conjugated structure of carbonyl and exomethylene groups in I and II plays an important role in potent antifungal activity. However, it is noteworthy that compounds 53, 54, and 56, which have a hydroxymethyl or methoxymethyl group instead of an exo-methylene group in I, also showed potent activity. Although many compounds exhibited strong antifungal activity in vitro, none showed activity in vivo of oral efficacy against subacute systemic candidiasis in mice.
The mode of action of probucol in reducing serum cholesterol was studied in normal and cholesterol-fed mice. Probucol did not affect intestinal absorption of radioactive cholesterol in normal and cholesterol-fed mice. In normal mice, probucol treatment resulted in inhibition of incorporation of [14C]-acetate into cholesterol in the liver, while it stimulated the incorporation in the small intestines. Incorporation of [14C]-mevalonate into cholesterol was not affected by the treatment. These results were consistent with the finding that the HMG-CoA reductase activity was decreased in the liver, but increased in the intestinal tissues of the treated mice. In cholesterol-fed mice, probucol treatment had no effect on cholesterol synthesis in the liver, while it increased the intestinal cholesterol synthesis. The over-all effect of this drug on cholesterol synthesis was not significant, although it tended to be inhibitory in normal mice and stimulatory in cholesterol-fed mice. On the other hand, probucol treatment resulted in acceleration of the clearance of [14C]-cholesterol-derived radioactivity from the circulation and resulted also in a significant increase in fecal excretion of the radioactivity, cholesterol and bile acids without changes in lipid composition of the bile. Cholesterol content in and radioactivity distribution among the tissues were not affected by probucol. Hepatic cholesterol 7 alpha-hydroxylase activity was increased by probucol. These findings indicate that probucol lowers serum cholesterol mainly by increasing catabolic excretion of cholesterol into bile.
Effect of probucol, pantethine and their combinations on serum lipoprotein metabolism and on the incidence of atheromatous lesions in aorta and coronary artery was studied in cholesterol-fed rabbits. Probucol treatment (0.5% in diet) resulted in reducing HDL cholesterol and serum apo A-I levels significantly, while pantethine treatment (0.25%-0.75% in diet) tended to increase HDL cholesterol and serum apo A-I levels. Combined treatment with these two drugs showed a significant prevention in the reduction of HDL cholesterol and serum apo A-I levels by probucol alone. Probucol or pantethine treatment reduced effectively (V) LDL cholesterol and serum apo B levels, and these effects were accelerated additively when the two drugs were given concurrently. Atheromatous lesions in aorta and coronary artery in cholesterol-fed rabbits were prevented by the treatment with probucol (0.5% in diet) or pantethine (0.75% in diet) for 24 weeks. The combined treatment with these two drugs showed more marked prevention than either drug alone. From these findings, it is concluded that the combined treatment of probucol with pantethine is effective for improvement of serum lipoprotein disorders and for prevention of the incidence of atheromatous lesions in aorta and coronary artery in cholesterol-fed rabbits.
Explore the source record for details and available documents.
Both threo and erythro 1-fluorodehydroxylated chloramphenicol analogues were synthesized and tested for antimicrobial activity. None showed antibacterial or antifungal activity, clearly demonstrating that substitution of the secondary hydroxyl group with fluorine abolishes the antibacterial activity of the parent compound, chloramphenicol. This finding sharply contrasts with that of previous workers, in which fluorination of the 3-hydroxyl group enhanced antibacterial activity against many chloramphenicol-resistant strains.
The mode of action of malotilate in normalizing serum cholesterol in hypocholesterolemic rats with fatty liver was examined by determination of biosynthesis, catabolism and excretion of cholesterol. Fatty liver was produced by subcutaneous injection of CCl4 at the dose of 1 ml/kg into male rats (SLC-SD) twice a week for 3 weeks. Daily administration of malotilate (100 mg/kg) in rats with hypocholesterolemia resulted in a rapid normalization of lowered serum cholesterol. Such a recovery of cholesterol level in serum coincided in time with normalization of the decreased cholesterol level of each lipoprotein fraction, VLDL-triglycerides secretion and the decreased apolipoprotein A1 value. Histopathological improvement in liver was also confirmed by a decrease in the size of fat droplets stored within the hepatocytes. The malotilate treatment gave a tendency to facilitate hepatic cholesterol synthesis in rats with fatty liver. Malotilate at a concentration of 0.5-2 micrograms/ml also stimulated cholesterol biosynthesis in cultured normal hepatocytes. The drug had the action to accelerate the catabolic excretion of 3H-labeled cholesterol into feces. These results suggest that the mode of action by which serum cholesterol is normalized in rats with fatty liver is probably due to a stimulative effect of malotilate on hepatic cholesterol synthesis and cholesterol secretion from the liver.
We investigated the characteristics of adrenergic receptor binding in peripheral blood cells from 6 patients with cystic fibrosis(CF) and 20 age-matched control subjects. There was a tendency (p = 0.08) towards a difference in dissociation constant of specific (125I)-hydroxybenzylpindolol (IHYP) binding in polymorphonuclear leukocytes (beta 2-adrenoceptor) from CF patients (113.0 pM +/- 32.8, SD) and controls (84.3 pM +/- 30.4, SD). We found no consistent differences in maximum binding capacity (Bmax) for either (3H)-yohimbine(YOH) binding in platelets (alpha 2-adrenoceptor) or IHYP bindings between the two groups. The ratio of YOH versus IHYP binding sites was significantly greater in CF patients (1.51 +/- 0.48) than in controls (1.07 +/- 0.34) (P less than 0.05). This might provide a possible explanation for the increased vasoconstriction and decreased heart rate response to adrenergic agonists in CF patients.
The synthesis and antifungal properties of 1-[1-[2-[(3-chlorobenzyl)oxy]phenyl]vinyl]-1H-imidazole hydrochloride (1 . HCl) are described. Topical application of cream and gel formulation of 1 . HCl showed high efficacy against guinea pig dermatophytosis.
A slow-release formulation of 40 mg furosemide as capsules (Eutensin) was investigated for its pharmacokinetic and pharmacodynamic properties in comparison with conventional tablets containing 40 mg furosemide (Lasix) in a single-blind clinical pharmacological trial in 6 healthy subjects. The following results were obtained: 1. The AUC0-24 after the administration of slow-release (SR) furosemide was about 42% of that after furosemide tablets. 2. Urine volume and urinary excretion of Na and Cl were significantly greater after furosemide tablets than after SR furosemide during the first 10 h after administration. No significant difference was observed between the two formulations in the urinary excretion of K, creatinine and uric acid. No significant difference was noted in every tested pharmacodynamic parameter during the cumulative 24 h after administration. It was concluded that SR furosemide may be used in the treatment of hypertension due to its characteristics of a slow-release diuretic feature, delayed peak blood concentration, delayed maximum diuretic effect and prolonged duration of action.
Repeated doses of a new beta-adrenoceptor blocking agent, befunolol, were administered orally to adult male volunteers for a cross-over comparison with propranolol. The beta-adrenoceptor blocking activity of befunolol was greater than that of propranolol when assessed by the percentage reduction in exercise-induced tachycardia. The elimination half-life of drug was significantly prolonged on repeated administration of propranolol, but not of befunolol. The percentage reduction in exercise-induced tachycardia was highly correlated with the log plasma level of each drug. Both drugs produced a significant reduction in pre-exercise systolic and diastolic blood pressure, and significant attenuation of exercise-induced rise in systolic blood pressure.
A high-cholesterol diet caused in rabbits a great increase in beta-migrating VLDL and a significant decrease in HDL 2 (43% of normal) and HDL 3 masses (64% of normal), without significant changes in HDL cholesterol values. Chemical analysis of the HDL subfractions indicated an abnormal lipid-protein composition in the hypercholesterolemic rabbits, an increase in cholesterol and a decrease in the contents of triglycerides and phospholipid. When these rabbits were treated for about 1 month with pantethine, and intermediate precursor of coenzyme A, the increase in cholesterol levels was effectively prevented in the beta-VLDL (11%) and LDL fractions (43%) but, conversely, HDL-cholesterol was significantly increased (151%). In a separate experiment, HDL 2 and HDL 3 masses were calculated to be increased to 186% and 193%, respectively, by pantethine treatment, when compared with those in control cholesterol-fed rabbits. Serum apolipoprotein AI antigen levels were also significantly increased by the treatment.
1 We have given fifteen healthy volunteers single doses of racemic (+/-)-propranolol orally (40 mg) and intravenously (5-10 mg) to find out how large the variation was of the ratio between (-)- and (+)-propranolol plasma levels in relation to that of total levels of propranolol and 4-hydroxypropranolol. 2 Total propranolol (+/-)-levels 2 h after a 40 mg oral dose of (+/-)-propranolol varied from 21 to 580 nmol/l and those of 4-hydroxypropranolol from 0 to 33 nmol/l. Their levels did not correlate. The ratio between (-)- and (+)-propranolol levels varied from 0.99 to 2.04. The plasma half-lives of the two isomers were usually similar. 3 We conclude that in most single doses studies on relationships between plasma concentrations and effects (beta-adrenoceptor blockade) it is not necessary to quantitate (+)- and (-)-propranolol levels separately since total (+/-) plasma propranolol levels varied much more than the ratio between (-)- and (+)-propranolol.
Explore the source record for details and available documents.
The disposition of propranolol stereoisomers after administration of a single oral dose of the racemic drug was investigated in seven hyperthyroid patients before and after antithyroid drug therapy. The possibility of hypersensitivity to propranolol in the patients was evaluated by constructing plasma propranolol concentration -- beta-blocking effect curves. There was no statistically significant difference in elimination half-life (t1/2) between (+/-)- and (-)-propranolol before and after antithyroid drug therapy. However, the plasma clearance (Vp) of (-)-propranolol was smaller than that of (+/-)-propranolol, and the difference was statistically significant after antithyroid drug therapy. Vp decreased or did not change in young patients after therapy. No significant difference was observed in the relationship between the tilt-induced pulse rate response and plasma propranolol concentration when treated patients became euthyroid compared to their response in the hyperthyroid state.