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H Coper

Publications and source records attributed to H Coper.

31 records · Page 2Linked to original sources
PubMed1976

Critical evaluation of measurement of platelet monoamine oxidase in man.

Some biochemical characteristics such as substrate specificity, substrate affinity and inhibitor sensitivity of monoamine oxidase of human blood platelets were investigated. Tyramine, tryptamine and beta-phenylethylamine were used as substrates. The apparent Michaelis constants, maximal velocity rates and I50 for the inhibitor tranylcypromine were determined. The data were analyzed according to Lineweaver-Burk and Dixon. The influence of amitriptyline, a prototype of tricyclic antidepressants, on the selected variables (Km, V, I50), was studied. The parameters investigated showed remarkably low interindividual differences when healthy volunteers were tested. The inhibitor activity of amitriptyline towards platelet monoamine oxidase depends on the substrate used. Amitriptyline concentrations which showed a pronounced effect on the enzyme characteristics are significantly higher than plasma levels of the drug found under therapeutic conditions.

Adult↗
PubMed1976

[Comparative pharmacological effects of dl-amphetaminil and dl-amphetamine in the rat].

The present investigation shows that amphetamine and amphetaminil produce identical pharmacological effects (increase in motility and body temperature, anorexia, stereotypic behaviour). There was neither a qualitative difference under "open field" conditions nor a difference in the capacity of modifying the reserpine induced syndrome. In isomolar doses amphetamine was somewhat more effective. Almost the same amounts of amphetamine were found in blood and brain following amphetamine or amphetaminil administration, with exception of somewhat higher peak levels after amphetamine. These results favor the hypothesis that amphetaminil effects are produced by the amphetamine molecule.

Acetonitriles↗
PubMed1976

[Determination of monoamine oxidase and catechol-O-methyltransferase in human blood components: methodical aspects (author's transl)].

Controversal findings are reported with respect to alternations in activity of monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) in psychoses. Initially we determined the interindividual differences of some biochemical properties of the two enzymes in normal control subjects. Platelet rich plasma and lysate of red blood cells, respectively, were used for assay. Enzyme activity was referred to mg of protein or mg hemoglobin and number of platelets, respectively. Substrates used for COMT assay were: 3,4-dihydroxybenzaldehyde and 3,4-dihydroxybenzoic acid; for MAO determination: tyramine, tryptamine and phenylethylamine. Interindividual as well as intraindividual differences in the biochemical characteristics (apparent Km, Vmax, IC50, meta/para ratio of O-methylation in vitro) were remarkably low, the coefficient of variation was in the range of 30%.

Affective Symptoms↗
PubMed1975

Kinetics and metabolism of amphetamine in the brain of rats of different ages.

The kinetics and tissue distribution of amphetamine and its metabolites p-hydroxyamphetamine (p-PH-A) and p-hydroxynorephedrine (p-OH-NE) were investigated in young adult (3-4 months) and old (20-25 months) male rats, after i.p. injection of 5 mg/kg tritium labelled D-amphetamine. The concentrations of these drugs were determined in plasma, cerebral cortex, brainstem and hypothalamus, by thin layer chromatography. 1. From 60 min up to 4 hrs after injection of amphetamine the concentration of amphetamine in plasma and brain tissue of old rats was significantly (P less than 0.05 higher than in young adult animals. In both age groups the levels of amphetamine in cerebral cortex greater than brain stem greater than hypothalamus. 2. The blood-brain barrier is permutle to p-OH-A; 10 to 20 min afer i.v. injection of 10 muCi/kg of p-OH-A (10 mCi/m mole) the ratio of brain/blood plasma was found to be 1:3. The half life of p-OH-A in blood plasma was almost identical after injection of amphetamine and p-OH-A (90 min and 98 min respectively). 3. The levels of p-OH-NE in different brain areas were significantly lower (P less than 0.05) in old animals than in young adult rats 4 hrs after application of amphetamine. This metabolite of amphetamine shows a higher concentration in the hypothalamus earlier than in other brain regions.

Age Factors↗
PubMed1975

The rate of excretion of VMA in depressed patients before and after the administration of methionine.

The results of a previous experiment in which the relationship between VMA-excretion in the 24-hr-urine and a depressive syndrome was found were examined on the basis of the following hypothesis: 1. The patients of the present study show an increased VMA-excretion, because there are more depressed patients than in the previous experiment. 2. The amount of excreted VMA correlates positively with the degree of severity of their depression. The mean value of the VMA-excretion in the urine of 20 depressive patients of the present study corresponds to that obtained from the depressive patients in the previous exploratory experiment. The degree of severity of depression of the patients correlated with the VMA-excretion. Patients with an increased VMA-excretion were significantly more often treated with antidepressive drugs than those with normal VMA-values.

Depression↗
PubMed1975

[Stability of amphetaminil. 1. In-vitro studies].

The decomposition of alpha-phenyl-alpha-N-(beta-phenyl-isopropyl)-aminoacetonitrile (amphetaminil, AN 1¿) in different solvent mixtures seems to depend on their polarity. The rate of hydrolysis of amphetaminil is much higher when the compound is dissolved in a methanol/0.1 N HCl (75/25; v/v) or in methanol containing traces of concentrated HCl (36%) (97.5/2.5; v/v). Using radioactively labelled amphetaminil we were able to demonstrate the decomposition of the compound on TLC plates coated with silica gel--independent from the solvent applied. When plates with cellulose as stationary phase were used for chromatography, amphetaminil proved to be stable in cyclohexan/ethylacetate but underwent decomposition in more polar solvents, for example, methanol and chloroform, respectively.

Aminoacetonitrile↗
PubMed1975

[Stability of amphetaminil. 2. In vivo studies].

The metabolism of radioactively labelled alpha-phenyl-alpha-N-(beta-phenyl-isopropyl)-aminoacetonitrile (amphetaminil, AN 1-R) (tritium-labelled in the amphetamine-part, 14C-labelled in the benzaldehyde-part of the molecule) in the rat was examined. In the body amphetaminil is cleft very quickly into the original compounds of its chemical synthesis (amphetamine, benzaldehyde and hydrocyanic acid) independent of the mode of application (i.p. or oral). Blood: In the interval from 5-90 min after application of amphetaminil only 1-2 percent of the total radioactivity are received from amphetaminil. The main part of the tritium- and 14C-radioactivity is distributed among amphetamine, p-OH-amphetamineglucuronide and hippuric acid. Brain: In the brain only a minimum amount of amphetaminil can be present, if any. The share of amphetamine of the total activity amounts to more than 90 percent. Adipose tissue: In the adipose tissue the ratio of the two isotopes of the substances extracted at pH 5 is almost equal to that of the administered amphetaminil. It seems that the substance is enriched there because of its pronounced lipophilia. After i.p. application the concentration is about 12 times higher than after oral application. Urine: In the urine there could be detected amphetamine, p-OH-amphetamineglucuronide and hippuric acid but no amphetaminil.

Acetonitriles↗
PubMedDate not supplied

An attempt to correlate the development of tolerance to delta-9-tetrahydrocannabinol and d-amphetamine with their subcellular distribution in rat brain.

The daily application in rats of d-amphetamine during 4 weeks in increasing doses from 16-80 mg/kg/day developed a tolerance. The quantitative evaluation of the relative accumulation of unchanged d-amphetamine in different subcellular brain fractions estimated with 3H labelled d-amphetamine showed that the development of tolerance to amphetamine is not associated with a decreased accumulation of the unchanged drug in any subcellular fraction of the brain. Synthetic delta-9-tetrahydrocannabinol (THC) was injected (10 mg/kg) to rats twice daily. After the 9th injection the intensity of the initial depressant effect was approximately similar to that after one injection but completely disappeared after 3 hrs of treatment. The specific activities of delta-9-THC and its metabolites in brain subcellular fractions were estimated with use of 3H-delta-9-THC. The tolerance to delta-9-THC in contrast to amphetamine seems to be mainly metabolic.

Animals↗