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Biomedical subjects

M Sandler

Publications and source records attributed to M Sandler.

At least 181 records · Page 10Linked to original sources

Monoamines, monoamine oxidase and alcoholism.

The alcohol-addictive metabolite hypothesis of alcohol addiction is reviewed. The status of monoamine oxidase in this clinical condition is also discussed and possible reasons for low platelet activity proposed. An endogenous monoamine oxidase inhibitor, which is also a benzodiazepine receptor ligand, denominated tribulin, is produced in excess following alcohol withdrawal and may, in fact, be a predisposing factor for or the actual agent precipitating delirium tremens. Alcohol suppresses tribulin production and predisposed individuals may drink it to counter the dysphoric effects of a baseline overproduction of this compound.

Alcohol Drinking↗

Diagnostic problems in renal hypertension. A case report.

A case of severe hypertension due to fibromuscular dysplasia of the renal artery in a young adult woman is described. Several atypical features (both clinical and biochemical) are presented, and a guideline is suggested for investigations in younger adults with severe hypertension who are unresponsive to adequate drug therapy. Current concepts and features of fibromuscular dysplasia of arterial vessels are discussed.

Adult↗

Home parenteral nutrition in a patient with Crohn's disease. A case report.

Total parenteral nutrition (TPN) carried out by the patient at home is a new concept in the treatment of intestinal failure. We describe a patient with Crohn's disease who has extensive involvement of the small intestine with resultant severe malabsorption, and who was therefore treated with 'home' TPN for 4 months. During this treatment there were no serious complications. The disabling symptoms present before hyperalimentation was commenced disappeared, and overall clinical improvement has been maintained for a further 6 months after TPN therapy. This case illustrates the feasibility of safe TPN at home in selected patients who have access to specialized hyperalimentation units.

Adult↗

Platelet monoamine oxidase: specific activity and turnover number in headache.

Monoamine oxidase turnover numbers (molecules of substrate converted to product per minute per active site) have been calculated for the human platelet enzyme using [3H]pargyline. Headache patients with high and low monoamine oxidase specific activities relative to controls were found to have turnover numbers very close to those for controls. This finding suggests that their specific activities vary because of differences in the concentration of active monoamine oxidase molecules, rather than differences in the ability of those enzyme molecules to catalyse the deamination reaction.

Binding Sites↗

Multiple forms of phenolsulphotransferase in human tissues: selective inhibition by dichloronitrophenol.

Evidence is presented for two functional forms of phenolsulphotransferase in human tissues: (1) activity ratios, using dopamine and phenol as substrates, varied 30-fold between different tissues, whereas the dopamine to tyramine activity ratio was relatively constant; (2) incubation at 37 degrees caused a selective decrease in activity towards dopamine compared with phenol; and (3) phenol sulphoconjugation was selectively inhibited by dichloronitrophenol and pentachlorophenol compared with that of dopamine and tyramine. The two forms, which have been designated M (monoamines) and P (phenol), were both present in platelets, jejunum, adrenal and brain.

Arylsulfotransferase↗

Pulmonary fibrosis following long-term nitrofurantoin therapy.

Three patients who developed pulmonary fibrosis following prolonged treatment with nitrofurantoin for chronic urinary tract infections are presented. They had received the drug for 3--4 years; all gave histories of 2--3 years of progressive shortness of breath and an unproductive cough. On examination, all 3 patients had bilateral crackles and 1 had finger clubbing. Chest radiographs showed bilateral shadowing and lung function tests a restrictive defect with reduced gas transfer. Lung biopsies showed extensive fibrosis in 2 patients and advanced honeycomb formation in 1. The response to steroid therapy in 2 patients was excellent, with resolution of symptoms, clearing of the chest radiographs and improvement in lung function. It is proposed that nitrofurantoin has no place in the long-term treatment of chronic urinary tract infections and that its use in acute infections should be questioned.

Adult↗

Platelet phenolsulphotransferase deficiency in dietary migraine.

Patients with dietary migraine were found to have significantly lower levels of platelet phenolsulphotransferase activity than either migrainous patients without a history of dietary provocation or normal controls. Of the two known human variants of this enzyme, the phenol-inactivating P form, for which no endogenous substrate has so far been identified, was more severely involved than the M enzyme, which inactivates monoamines (including tyramine). Such commonly implicated dietary triggering agents as chocolate and cheese may contain as-yet-unidentified phenolic substrates of phenolsulphotransferase P; if the platelet enzyme deficiency were mirrored by low gut activity, abnormally large amounts of potentially toxic substances might gain access to the circulation in consequence.

Adult↗

Monoamine-oxidizing enzymes in human pregnancy.

The activity of benzylamine oxidase (BzAO) was investigated in human maternal blood at all stages of gestation, including parturition, as well as in the puerperium. In addition, BzAO and monoamine oxidase (MAO) A and B activities were assayed in amniotic fluid, placenta, placental vessels and umbilical vessels. No correlation was found between BzAO values in maternal blood and fetal growth. Highly significant variations in maternal plasma BzAO activity were seen by the end of the first trimester, at parturition and at 6-72 h post-partum. The predominance of MAO A in placenta was again confirmed, whereas in vascular tissue and amniotic fluid, BzAO was clearly preponderant; in the latter, no MAO A activity could be detected. Placental vessels showed significantly higher MAO A activity than umbilical vessels. BzAO and what appears to be a true, soluble MAO B were demonstrated in amniotic fluid. The physiological implications of these findings are discussed.

Amniotic Fluid↗

The contribution of amphetamine metabolites of (-)-deprenyl to its antiparkinsonian properties.

Although (-)-deprenyl is known to be metabolized to methamphetamine and amphetamine, two small-scale double-blind trials indicate that neither metabolite contributes to all therapeutic benefit conferred by this drug in certain patients with Parkinson's disease: the manipulation of urinary pH, which alters the rate of excretion of these metabolites, failed to change the response pattern; substitution of a metabolite mixture for active drug caused a falling off in benefit.

Amphetamine↗

beta-Carbolines as selective monoamine oxidase inhibitors: in vivo implications.

The inhibitory action of a range of beta-carbolines on human and rat monoamine oxidase (MAO) A and B has been studied. Concentrations of 5-hydroxytryptamine and phenylethylamine, approximately at their Km values, were used as substrates for MAO A and B respectively. A wide variation in selectivity was found, with harmaline being 10,000 times more potent an inhibitor of A than B whereas, using tetrahydro-beta-carboline and harmane, the difference was nearer to ten-fold. Of the carbolines which have been found endogenously, tetrahydro-beta-carboline, 6-methoxytetrahydro-beta-carboline and harmane are all sufficiently potent inhibitors of human MAO A, with I50 values of 5 X 10(-6), 10(-6), 5 X 10(-7) M respectively, for this property to be of possible physiological significance. Harmane, with an I50 of 5 X 10(-6) M, might also play a role as an inhibitor of MAO B.

Animals↗

Phenylacetic acid in human body fluids: high correlation between plasma and cerebrospinal fluid concentration values.

In a group of six Parkinsonian patients and 13 "controls" with non-Parkinsonian neurological disease, there was a high correlation between both free and conjugated phenylacetic acid concentrations in plasma and cerebrospinal fluid taken at about the same time. This compound is the major metabolite of phenylethylamine, the production of which may be disturbed in a number of neuropsychiatric illnesses. Thus plasma measurements might be employed clinically to provide an estimate of central changes in phenylethylamine economy. A small but significantly higher proportion of conjugated phenylacetic acid was present in the plasma (but not cerebrospinal fluid) of Parkinsonians compared with controls.

Female↗

Platelet size: no correlation with migraine or monoamine oxidase activity.

A Coulter Model "S Plus" counter has been used to study platelets from 39 migrainous patients between attacks, six during attacks, eight with active cluster headache and 26 controls. None of the patient groups showed any abnormality in platelet size profile. There was no correlation between platelet monoamine oxidase activity and mean platelet volume in any of the groups.

Adult↗

Raised endogenous monoamine oxidase inhibitor output in postwithdrawal alcoholics: effects of L-dopa and ethanol.

Urinary output of endogenous monoamine oxidase inhibitor was significantly greater in a group of postwithdrawal alcoholics than in controls. An oral dose of 0.5 g of L-dopa reduced output to control values in the alcoholics, but in the controls themselves output was unaffected. A similar excretion pattern to unextracted samples was observed in ethyl acetate extracts of these urine samples, acidified to pH 1. In a second group of postwithdrawal alcoholics, where the L-dopa effect was confirmed, ethanol administration brought about a small but not significant reduction in inhibitor output.

Adult↗