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Biomedical subjects

A Nagy

Publications and source records attributed to A Nagy.

At least 361 records · Page 20Linked to original sources
PubMed1976

The preparation and characterization of synaptic vesicles of high purity.

Very pure preparations of synaptic vesicles have been obtained from guinea pig cerebral cortex and from the electromotor synapses of Torpedo marmorata by density gradient centrifugation in a zonal rotor followed by chromatography on columns of glass beads of controlled pore size. Markers for soluble cytoplasm (lactate dehydrogenase), plasma and endoplasmic membranes membranes (Na-K-ATPase; acetylcholinesterase, NADPH-cytochrome c reductase], mitochondrial membranes [cytochrome oxidase] and lysosomes [acid phosphatase] were used to assess contamination and were undetectable. The only enzymes detected in the highly purified preparations from guinea pig cerebral cortex were Mg- and Ca-activated ATPases, but their content relative to acetylcholine fell on chromatography suggesting that they may be constituents of non-cholinergic vesicles. Lipids analyses of the highly purified vesicles confirmed earlier results and showed that glycolipids and lysolecithin are present in negligible amounts; this suggests that lysolecithin is not required for exocytosis of synaptic vesicles. A discussion of the probable limiting concentration of acetycholine in cerebral cortical vesicles derived solely from cholinergic terminals suggests that from 13 to 56% of the vesicles isolated are cholinergic, depending on the assumptions made.

Acetylcholine↗
PubMed1976

Potentiation of the antidepressant action of clomipramine by tryptophan.

In a double-blind study of 24 patients with endogenous depressiona group treated with clomipramine hydrochloride (chlorimipramine) plus tryptophan was compared with a group treated with clomipramine plus placebo. The sum of the ratings for depressed mood, suicidal intent, depressive thought content, and anxiety showed a more rapid improvement in the former group, the difference being already significant after 12 days of treatment. On the other hand, the ratings for retardation decreased about equally in both groups during the three-week treatment period. Side-effect ratings showed no significant increase but seemed to be partly influenced by the improvement of depressive symptoms. Plasma levels of clomipramine appeared to reach a plateau within a few days, whereas the monodesmethylated metabolite continued to rise for a longer period of time, and reached considerably higher values than the parent compound. In the tryptophan group the degree of improvement seemed to be positively correlated to these levels, suggesting that further improvement might have been reached in some patients by increasing the dose of clomipramine. The levels of 5-hydroxyindoleacetic acid in the cerebrospinal fluid appeared to be reduced by clomipramine administration. This effect was prevented by the additional treatment with tryptophan.

Adolescent↗
PubMed1976

Plasma levels and antidepressive effect of imipramine.

The relationship between the antidepressive effect of imipramine and the plasma concentrations of imipramine and the active metabolite desipramine was studied in 24 patients suffering from endogenous depression. After a placebo period of 7 days, the patients received imipramine, 75 mg 3 times a day. The dose was reduced in patients with pronounced side effects. Blood samples for drug assay were drawn in the morning, 15 hr after the last drug intake. Imipramine and desipramine in plasma were assayed by quantitative in situ thin-layer chromatography. Individual variations in plasma concentration were 20- to 30-fold in both imipramine and desipramine. Severity of depression was assessed on the Hamilton Rating Scale (HRS). Eleven of 12 patients who responded satisfactorily to the treatment (HRS post-treatment score less than 8) had plasma concentration of imipramine greater than or equal to 45 mug/L, and desipramine greater than 75 mug/L, whereas the 12 patients not responding satisfactorily (post-treatment score on HRS greater than or equal to 8) all had concentrations of imipramine or desipramine or both below these limits.

Adult↗
PubMed1976

Intestinal absorption, demethylation, and enterohepatic circulation of imipramine.

The intestinal absorption and metabolism of single oral doses of imipramine (ip) have been studied in man by portal catheterization. The concentration of ip and the formed desipramine (dmi) was followed in blood-plasma obtained from the portal and cubital veins. The absorption of ip seemed to be completed 80 min after the administration of the drug. There was no sign of demethylation of ip during the passage across the intestinal wall. Evidence was found of an enterohepatic circulation of both ip and dmi.

Dealkylation↗
PubMed1975

Plasma levels of imipramine and desipramine in man after different routes of administration.

With the object of studying the kinetics of imipramine and desipramine five healthy volunteers received single intramuscular, oral and intravenous doses and multiple oral doses of imipramine hydrochloride on different occasions. Two of the volunteers also received single intramuscular and oral doses of desipramine hydrochloride. Great interindividual differences were noted in the plasma concentrations of imipramine and the formed desipramine after single doses of imipramine hydrochloride. In all subjects more desipramine was formed after oral than after parenteral adminstration of imipramine. The bioavailability of an orally administered dose of imipramine ranged between 29.5 and 54.7%. The concentration of imipramine was generally lower in the blood cells than in the plasma, unlike the concentration of desipramine which was considerably higher in the blood cells. The half-lives of imipramine ranged from 4.0-17.6 hrs (M = 7.6 +/- 2.5) after single oral doses and between 9.2 and 20.2 hrs (M = 14.0 +/- 1.9) after multiple oral doses. The half-lives of the formed desipramine ranged between 13.5 and 61.5 hrs (M = 29.9 +/- 8.7) after multiple oral doses of imipramine hydrochloride. The observed mean steady-state plasma concentration after multiple oral doses of imipramine hydrochloride, 50 mg t.i.d. varied from 21.4-69.0 mug/1 (M = 38.2 +/- 8.7) for imipramine and from 33.7-136.0 mug/1 (M 72.3 +/- 19.5) for desipramine. The great difference in the ability to form desipramine after oral and parenteral administration of imipramine hydrochloride may have therapeutic consequences as imipramine and desipramine have differing pharmacological properties.

Administration, Oral↗
PubMed1975

Incidence of congenital heart disease in Hungary.

A survey was planned for establishing the point prevalence at birth of congenital heart disease and for assessing at the same time the efficacy of a screening for such anomalies. This model included: (1) exact determination of the population under survey; (2) approximately complete ascertainment of all persons in the population studied; (3) identical principles of cardiologic screening; (4) application of modern cardiologic diagnostic methods, and (5) a sample of over 2,000 persons. 23 cases of congenital heart diseases were found among 2,259 children born 1963 in a defined Hungarian territory. This means a point prevalence of 10.2+/-2.1% live births. (An additional 6 doubtful cases were not taken into account.) From the 12 cases diagnosed in vivo, 10 were detected by the screening.

Child↗