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Biomedical subjects

L Demisch

Publications and source records attributed to L Demisch.

52 records · Page 3Linked to original sources
PubMed1981

Low platelet MAO activity in psychiatric patients and plasma factors: no evidence for inhibitory influences on MAO in the circulating platelet population.

The influence of plasma and low and high molecular weight plasma fraction on MAO activity in platelets from controls were studied. Plasmas were obtained from patients with decreased platelet MAO activity and suffering from chronic schizophrenia of different syndrome subtypes, unipolar depressions, and alcoholism. Up to 50% inhibition and activation of MAO activity alterations were not different between the plasmas from schizophrenic, depressive, and alcoholic patients. Plasmas from schizophrenic patients without medication or on neuroleptics showed similar inhibition and/or activation of MAO activity in platelets from controls. The results indicate, in accordance with recent findings, that a number of low and high molecular weight substances can trigger platelet MAO activity changes. These plasma factors do not appear to be characteristic of schizophrenic patients with low platelet MAO activity.

Adult↗
PubMed1979

Stimulation of human prolactin secretion by mescaline.

Prolactin (PRL) and Growth Hormone (GH) secretions were studied in human serum after the oral administration of 5 mg/kg mescaline (3,4,5-trimethoxy-beta-phenylethylamine) or 2,3,4-trimethoxy-beta-phenylethylamine (2,3,4-TMPEA) respectively. Mescaline stimulated the secretion of PRL more than four-fold above base-line levels. Peak concentrations were found 90--120 min after drug intake. Five hours later serum PRL was still markedly increased. Mescaline also triggered GH secretion. There was no alteration of serum PRL and GH concentrations after intake of the non-hallucinogenic 2,3,4-TMPEA.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1979

Factors altering platelet monoamine oxidase. The influence of oral glucose intake.

The specific activity of human platelet monoamine oxidase from control subjects undergoing glucose tolerance tests is reduced drastically. Three hours after intake of 100 g of glucose only 25%-30% of the MAO-baseline activity was measured with tryptamine. beta-phenylethylamine and p-tyramine as substrates. At about 5 hr, platelet MAO activity has increased again. Inhibition was not due to small molecular weight inhibitors or other diffusible factors. Studies of other platelet enzymes, including succinate dehydrogenase and isocitrate dehydrogenase (NADP+ dependent) showed no parallel reductions; hGH, insulin, blood glucose and platelet glycogen concentrations did not correlate with platelet MAO activity. The changes of MAO activity in respect with p-tyramine and tryptamine as substrates 24 hr after glucose ingestion suggest changes of the lipid microenvironment of this enzyme of the outer mitochondrial membrane.

Adult↗
PubMed1978

[On improved prophylaxis of endogenous-phasic psychoses. Influence of L-aspartate on lithium transport (author's transl)].

The influence of aspartate on lithium transport was studied with humna red blood cells (rbc) in vitro and after i.p. injection of Li-DL-asp or LiCl in different tissues of the rat. After administration of Li-asp the lithium concentrations in brain and rbc of the rats increased more slowly compared to rat treated 3 to 6 days with Li-asp were more than two times higher than those of rats treated with LiCl. After daily injection of the two salts, lithium levels in the brains of rats teated with LiCl. Results of in vitro experiments with human rbc indicate that the effect of aspartate on lithium transport is specific for L-aspartate. In addition a similar but smaller effect has been observed with l-glutamate.

Amino Acids↗
PubMed1977

Substrate-typic changes of platelet monoamine oxidase activity in sub-types of schizophrenia.

Monoamine oxidase (MAO) activity has been measured in the platelets of controls (n = 42) and schizophrenic patients (n = 49) of three subtypes, using beta-phenylethylamine, p-tyramine, and tryptamine as substrates. Characteristic differences of MAO activity were observed between platelets of patients and controls; the differences were substrate-typic: decreased enzyme activity was found with all three substrates in platelets of the parnaoid subtype. With tryptamine, MAO activity was decreased in the platelets of all three sub-types of schizophrenia. With p-tyramine, MAO was low in patients with affective psychoses and paranoid schizophrenia. The value of MAO activity measurements as a means for distinguishing sub-types of schizophrenic disorders is improved by using two substrates; tryptamine and p-tyramine. Possible mechanisms of the substrate-typic changes of platelet MAO activity in schizophrenia are discussed.

Adult↗
PubMed1976

A routine assay procedure for monoamine oxidase and its application to human blood platelets.

In the radiometric assay procedure for monoamine oxidase separation of the reaction products by ion-exchange column chromatography was optimized. A device was constructed that allowed the separation of 48 samples at the same time. This device can be applied for a great variety of analytical methods. With a 0.1 mM substrate concentration in the incubation mixture, reaction products could be determined with a reproducibility of 2-5%, where the standard deviation depends on the substrate. Using beta-phenylethylamine as substrate 20 mug of platelet protein was sufficient for monoamine oxidase activity determinations. The dependence of human blood platelet monoamine oxidase on age and sex were studied using the method.

Adolescent↗
PubMed1976

[On improved prophylaxis of endogenous-phasic psychoses: aspects of parallel determination of lithium in serum and erythrocytes (author's transl)].

In 30% of the psychiatric patients investigated the lithium concentration in erythrocytes (RBC-lithium) is a more reliable indicator for the evaluation of the clinical response and the risk of toxicity. After lithium administration the lithium RBC levels increased within the first three weeks. Lithium RBC/plasma ratios are not different between unipolar, bipolar and schizo-affective psychoses. It was found that low lithium RBC/plasma ratios correspond with low monoamine oxidase (MAO) activity in platelets.

Affective Symptoms↗
PubMedDate not supplied

[Process and phasic psychoses according to ICD-9 classification].

101 in-patients were diagnosed according to the ICD-9 and the Frankfurt (FC) classifications. The latter classification used the glossary of the AMDP system, and the Andreasen scale (SANS). 94% of the FC process psychoses were diagnosed as schizophrenia according to ICD-9 and 78% of the atypical phasic psychoses (FC) as schizoaffective schizophrenia (ICD-9). On the other hand, only 55% of the ICD-9 schozophrenias could be classified as a FC process psychosis. The results confirm the assumption that the ICD-9 classification is not helpful in distinguishing phasic from non-phasic psychoses. Advantages of a classification based on phasic or non-phasic course are mentioned. Finally it is emphasized that the operationalization of concepts (either classic or new), the polydiagnostic, and the use of international glossaries (like the AMDP system) are an unavoidable step for the development and extension of the psychiatric research in Latin America.

Adolescent↗
PubMedDate not supplied

3,4,5-Trimethoxybenzoic acid, a new mescaline metabolite in humans.

After ingestion of 400 mg of mescaline sulfate by human volunteers, 3,4,5-trimethoxybenzoic acid was isolated from urine and identified by gas chromatography-mass spectrometry. The amount of this anionic mescaline metabolite was found to be very low as compared with that of the well-konwn 3,4,5-trimethoxyphenylacetic acid. The significance of this finding is discussed.

Adult↗
PubMedDate not supplied

Pharmacodynamics of levodopa coadministered with apomorphine in parkinsonian patients with end-of-dose motor fluctuations.

The modification of the pharmacodynamic response to a single oral dose of levodopa/benserazide by the coadministration of the dopamine agonist apomorphine was investigated in parkinsonian patients with end-of-dose motor fluctuations. The relation between levodopa plasma concentrations and motor response was examined in a double-blind, randomized, crossover design in 10 patients with idiopathic Parkinson's disease with end-of-dose motor fluctuations. Oral single-dose challenges with 100 mg of levodopa/25 mg of benserazide were carried out twice in each patient, under coadministration with apomorphine (1 mg/h) or 0.9% saline (placebo) subcutaneously. The sum scores (sigma score) of the Columbia University Rating Scale (CURS) were used as effect parameters for pharmacodynamic assessment. A sigmoidal Emax model was fitted to the data using a semiparametric pharmacokinetic-pharmacodynamic approach. Levodopa pharmacokinetics were not significantly modified by the coadministration of apomorphine. The area under the curve was 1599 +/- 615 ng.ml-1 h. (levodopa + saline) and 1821 +/- 625 ng.ml-1.h (levodopa + apomorphine). Cmax was 1094 +/- 476 ng.ml-1 (levodopa + saline) and 1129 +/- 435 ng.ml-1 (levodopa + apomorphine). Under both experimental regimens, the maximum clinical response to levodopa (Emax) yielded a decrease in the CURS sigma rating of about 20 score points. Estimates of the EC50 of levodopa decreased significantly from 430 +/- 163 ng.ml-1 (levodopa + saline) to 315 +/- 123 ng+ml-1 (levodopa + apomorphine) (95% confidence interval [CI] 0.51 -0.98, point estimator 0.75). The mean duration of the motor response rose from 1.9 +/- 0.5 h (levodopa + saline) to 3.0 +/- 0.9 h (levodopa + apomorphine (95% CI 1.23 to 2.06, point estimator 1.60). Thus, a reduction of the threshold levels for levodopa (EC50) was accompanied by approximately 50% gain in on-phase duration, but not in an increased magnitude of the motor response (Emax).

Adult↗