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Biomedical subjects

M Sandler

Publications and source records attributed to M Sandler.

At least 235 records · Page 13Linked to original sources
PubMed1979

Urinary phenylethylamine excretion: gas chromatographic assay with electron-capture detection of the pentafluorobenzoyl derivative.

Phenylethylamine was extracted into n-hexane from alkaline urine saturated with sodium chloride, and back-extracted into dilute acid. The extract was freeze-dried and the residue converted to a pentafluorobenzoyl derivative for analysis by gas chromatography on a column of OV-225 with electron-capture detection. Quantification was achieved by adding an internal standard of tolylethylamine to each sample prior to extraction. Output values in normal subjects and in some patients with phenylketonuria and hyperphenylalaninaemia were in agreement with those in some other recent reports.

Adult↗
PubMed1979

Decreased cerebrospinal fluid concentration of free phenylacetic acid in depressive illness.

Cerebrospinal fluid free phenylacetic acid concentration in a series of depressive patients was significantly lower than values in control subjects. This acid derives from phenylethylamine and the findings may reflect a decrease in its brain formation. Such a deficit may be related to other recent observations of a decrease in urinary output of the major metabolites of the "trace amines", octopamine and tyramine: phenylethylamine is thought to be the precursor of these "trace amines".

Adult↗
PubMed1979

An improved method for the differential assay of 3-O-methylated catecholamines in human urine using ion-pair extraction and gas chromatography electron capture detection.

A gas chromatographic method is described for the quantitative determination of urinary normetadrenaline, metadrenaline and 3-methoxytyramine using electron capture detection. The N,O-dipentafluoropropionyl beta-O-ethyl derivatives of normetadrenaline and metadrenaline and the N,O-dipentafluoropropionyl derivative of 3-methoxytyramine were prepared. The amines were purified by ion exchange chromatography and ion pair extraction. Amine derivatives from urine extracts were identified definitively by mass fragmentography. The 24-h excretion value for normetadrenaline in human urine is 167 +/- 95 micrograms (mean +/- S.D.), for metadrenaline is 116 +/- 74 micrograms (mean +/- S.D.) and for 3-methoxytyramine is 82 +/- 68 micrograms (mean +/- S.D.).

Catecholamines↗
PubMed1979

A coupled peroxidatic oxidation technique for the histochemical localization of monoamine oxidase A and B and benzylamine oxidase.

A coupled peroxidatic oxidation technique is presented which employs benzylamine and tyramine as substrates and clorgyline, deprenyl, phenelzine and pargyline as specific inhibitors. Using this technique with frozen sections of human term placenta and rat liver, the histochemical localization of monocamine oxidase A and B and bnezylamine oxidase has been demonstrated.

Animals↗
PubMed1978

Phenylethylamine overproduction in aggressive psychopaths.

Plasma concentrations of free and conjugated phenylacetic acid, the major metabolite of phenylethylamine, were higher in ten prisoners serving long terms of imprisonment for violent crimes than in pair-matched non-violent control prisoners. Since amphetamine, a compound closely related to phenylethylamine, can reduce aggressiveness in some violent subjects, the increase in phenylethylamine production may be an attempt to compensate for the unknown derangement of function responsible for increased aggression.

Adult↗
PubMed1978

Deprenyl administration in man: a selective monoamine oxidase B inhibitor without the 'cheese effect'.

After pretreatment with the selective monoamine oxidase B inhibitor, (-)-deprenyl, in doses sufficient for complete inhibition of the platelet enzyme, 4 normal and 6 parkinsoniam volunteers (2 receiving levodopa and 2 levodopa plus carbidopa) suffered no adverse pressor reaction ('cheese effect') after challenge with oral tyramine in amounts considerably greater than those likely to be encountered in a normal diet. Nor did the levodopa-deprenyl combination itself result in a pressor response. Normal human intestinal mucosa was shown predominantly to contain the deprenyl-insensitive A form of the enzyme, which presumably degraded administered tyramine in the deprenyl-treated volunteers; even those receiving the drug for prolonged periods manifested no 'cheese effect', suggesting that the A form remained uninhibited. Intestinal monoamine oxidase A was able to oxidise dopamine, whereas in human platelet or striatum the amine is a monoamine oxidase B substrate. Like tyramine, oral phenylethylamine challenge with amounts greater than those known to be present in a normal diet similarly gave rise to no adverse reaction in (-)-deprenyl-treated subjects; the reasons for this remain to be determined.

Adult↗
PubMed1978

The effect of urinary pH and flow rate on monoamine output.

Three-hour urinary output values of dopamine, noradrenaline, adrenaline, 2-phenylethylamine and p-tyramine were measured in normal volunteers who had been induced, by pretreatment with ammonium chloride or sodium bicarbonate, to excrete maximally acid or alkaline urine. There were significant effects on the excretion of dopamine, adrenaline and 2-phenylethylamine, inversely proportional to urinary pH value. Adrenaline output increased with increasing urinary flow rate. There was a significant correlation between urinary concentrations of 2-phenylethylamine and p-tyramine. These findings may have important clinical implications.

Biogenic Amines↗
PubMed1978

Absence of "cheese effect" during deprenyl therapy: some recent studies.

Although the selective monoamine oxidase (MAO) B inhibitor, (-)deprenyl, has been shown to be free from the "cheese effect" in man after tyramine challenge, the reason for this is far from clear: it may well be independent of the selective inhibitory action of the drug, for during chronic administration there is some evidence to suggest that both A and B forms of the enzyme are equally inhibited. By-passing the putative MAO A gut barrier in the pig (chosen because it possesses MAO B alone in all other tissues) by intravenous tyramine administration into the deprenyl-pretreated animal failed to provoke a pressor response, despite substantial MAO inhibition. Conversely, clorgyline (MAO A inhibitor) pretreatment, which resulted in minimal MAO inhibition, produced a profound hypertensive response, resembling that observed with the non-MAO-inhibiting drug, isoniazid. The most parsimonious explanation for these findings may be that two separate but closely associated pharmacological effects are normally found with "orthodox" MAO inhibitors, enzyme inhibition proper and facilitation of noradrenaline release from its binding sites during tyramine challenge.

Amphetamines↗
PubMed1978

Amphetamine and 2-phenylethylamine in post-mortem Parkinsonian brain after (-)deprenyl administration.

Deprenyl is an inhibitor of monoamine oxidase type B, the enzyme responsible for 2-phenylethylamine oxidation, and is used in conjunction with L-Dopa therapy in Parkinson's disease. Post-mortem studies in human brain tissue have shown that after (-)deprenyl administration to parkinsonian patients amphetamine is present in concentrations up to 56 ng/g. It also could be shown that phenylethylamine concentrations are substantially increased in such patients. Phenylethylamine and amphetamine have been investigated using a gas chromatographic technique.

Amphetamines↗