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Biomedical subjects

Y W Cho

Publications and source records attributed to Y W Cho.

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

Free radical damage to sarcoplasmic reticulum of masseter muscle by arachidonic acid and prostaglandin G2.

In vitro generation of free radicals by xanthine oxidase acting on hypoxanthine as a substrate induced a decreased calcium uptake velocity and reduced calcium-dependent ATPase activity of isolated sarcoplasmic reticulum (SR) vesicles from canine masseter muscle at pH 7.0. At pH 5.5 calcium uptake velocity was also reduced but ATPase activity was unaffected. Application of arachidonic acid or prostaglandin G2 induced the depression of both calcium uptake velocity and ATPase activity. The effect of arachidonic acid and prostaglandin G2 on ATPase activity depended on the pH. At pH 7.0, ATPase activity was decreased, but at pH 5.5 it was unchanged. These effects were reversed by superoxide dismutase (SOD) at pH 7.0, and by SOD plus mannitol at pH 5.5. Prostaglandin H2, prostaglandin E2 and 11,14,17-eicosatrienoic acid had no effect on calcium uptake velocity and ATPase activity at both pH 7.0 and pH 5.5. These results suggest that damage to the masseter muscle is caused by a free radical superoxide anion generated as a result of increased prostaglandins synthesis, and by the production of more lethal hydroxyl radical switched from the production of superoxide anion at low pH.

Adenosine Triphosphatases↗
PubMed1981

Effects of perhexiline on myocardial phosphorylase activity, myocardial catecholamine content and heart rate.

A study was conducted on the effects of perhexiline on myocardial phosphorylase activity, myocardial catecholamine content and heart rate. Phosphorylase a activity and heart rate were investigated as an indicator of sympathetic nerve tone in order to clarify the characteristic of perhexiline with regard to the effects on myocardial metabolism in hyperthyroid rats and catecholamine deficient rats. Myocardial catecholamine and phosphorylase a activity were measured by von Euler's method and Cori's method respectively. Conclusion of this study are summarized as follows: 1) Perhexiline reduces the heart rate, and its effect is not always dependent upon the changes in myocardial norepinephrine content. 2) Perhexiline reduces myocardial phosphorylase a activity. It cannot be always said that the reduction is dependent upon the changes in myocardial norepinephrine. 3) Though slightly different from propranolol and dichloroisoproterenol, perhexiline possesses cardiac effects resembling beta-blockers.

Animals↗
PubMed1981

A double-blind, placebo-controlled evaluation of (dl)-3,7-dihydro-1,8-dimethyl-3-(2-methylbutyl)-1H-purine-2,6-dione in exercise-induced bronchospasm.

The investigational drug, (dl)-3, 7-dihydro-1, 8-dimethyl-3-(2-methylbutyl)-1 H-purine-2, 6-dione, has been proven to be an active bronchodilator and antiallergic compound in animal and clinical studies. Adult asthmatic patients who demonstrated greater than or equal to 20% improvement in FEV1 after inhalation of aerosolized isoproterenol or its equivalent and greater than or equal to 20% reduction in FEV1 after a graded treadmill exercise received theophylline (3, 6 mg/Kg, every 6 h) for 4 days. Further selection of patients was made by demonstrating that theophylline effectively blocked exercise-induced reduction in FEV1 and was effective in increasing FEV1 by 20% when measured 2 h after oral administration. Thus, these adult asthmatics entered a double-blind, placebo-controlled, two-dose cross-over study with the investigational drug at dosage 0.075 mg/kg twice daily and 0.125 mg/kg twice daily. At both dosages studied the investigational drug was found to be an effective bronchodilator in blocking exercise-induced reduction in FEV1 by improving asthma disability scores and increasing FEV1 2 h after oral administration. The incidence and severity of the side effects observed were less than those observed with theophylline.

Adult↗
PubMed1978

Cardiovascular effects of isoproterenol and possible antagonistic actions of propranolol and perhexiline.

A beta-adrenergic blocking activity of perhexiline was compared with that of propanolol. In the Langendorff's preparation of rabbits, canine heart-lung preparations, open-chest dog preparations and hind-limbs of dogs, perhexiline failed to block isoproterenol-induced changes in cardiovascular functions, which were effectively blocked by propranolol. These data suggest that perhexiline is not a beta-adrenergic receptor blocking agent.

Adrenergic beta-Antagonists↗
PubMed1978

Comparative bronchodilatory activity of cetiedil citrate monohydrate, theophylline, orciprenaline and placebo in adult asthmatics.

In 40 patients, a seven day observation period in which oral bronchodilators and corticosteroids were eliminated, cetiedil (100 mg, t.i.d.), theophylline (200 mg, t.i.d.) or orciprenaline (20 mg, t.i.d.) and placebo (100 mg Lactose, t.i.d.) were given for one week each, according to a double blind, crossover randomized code. Wheezing scores were improved by all three active drugs. Twenty five of these patients undertook a moderate degree of exercise. Cetiedil was the most effective drug in blocking exercise-induced bronchospasm of the drugs studied. At rest, FEV1/VC was improved by theophylline, while PEFR improved after orciprenaline. Cetiedil improved both parameters, significantly. In another 21 patients, cetiedil (100 mg, t.i.d.) was given, according to the 'patient blinded' method for two weeks. PEFR and Asthma Disability Scores steadily improved. Clinical effectiveness was observed as early as the 3rd or 4th day of cetiedil therapy, with maximum improvement detected on the 14th day. No major side effects or abnormalities in clinical laboratory tests were noted. Cetiedil also had a 'liquidifying effect' on bronchial mucous in these asthmatics.

Adolescent↗
PubMed1978

Comparison of soft gelatin capsule vs. sustained release formulation of papaverine HCl: vasodilation and plasma levels.

The vasodilatory action, plasma papaverine levels achieved, and the incidence of side effects after oral administration of papaverine hydrochloride as a soft gelatin capsule, were compared to those of a sustained release formulation. The incidence of side effects observed after 150 mg, two or three times per day, of the soft gelatin capsule was similar to that observed after 150 mg, twice per day, of the sustained release form in 15 patients with arteriosclerosis obliterans. A relatively higher plasma papaverine concentration was achieved, 120 minutes after 150 mg administration of the soft gelatin form, compared to an equivalent dose of the sustained release form. The degree of vasodilation obtained after four doses (150 mg X 4) of soft gelatin within 24 hrs., was significantly superior than that induced after four doses (150 mg X 4) of the sustained release form in 6 patients with a severe degree of arteriosclerosis obliterans.

Adult↗
PubMed1978

Exercise, induced bronchospasm in asthmatic children as a dose-response model for theophylline.

Efficacy and dose-response activity of oral theophylline were evaluated in 21 asthmatic children, using inhibition of exercise-induced bronchospasm (EIB) as a therapeutic marker. An aqueous theophylline suspension free of alcohol, sugar, and dye was found to be effective for prevention of EIB when given in usual maintenance doses of 4 to 6 mg/kg every 6 hours for 3 weeks, following single loading doses of 8 mg/kg. Pulmonary function measurements (FEV1, FEF25%-75%, PEFR) following standardized treadmill exercise stress were signifcantly improved during both acute and chronic theophylline administration compared to pre-drug control evaluations. There were no signs of developing tolerance to theophylline. The drug produced at least 50% inhibition of EIB in 16 to 21 patients treated. Individualized adjustment of maintenance dosage resulted in optimal theophylline serum concentrations of 10 to 18 microgram/ml in 17 patients. Signs of drug toxicity were observed only when serum levels exceeded 20 microgram/ml following loading doses in 6 patients. Although some children required higher maintenance dosage because of variability in theophylline pharmacokinetics, no child experienced adverse effects after dosage adjustment. Serum half-life ranged between 86 and 351 minutes (mean, 259 minutes); mean peak serum concentration of theophylline after 3 weeks of treatment was 14.9 microgram/ml.

Adolescent↗