Human platelet phenolsulphotransferase M and P: substrate specificities and correlation with in vivo sulphoconjugation of paracetamol and salicylamide

Human platelet phenolsulphotransferase exists in two functional forms. M and P. In this study the substrate specificity of the two forms has been further delineated by correlating activities in different individuals with various substrates. m-Tyramine, noradrenaline, adrenaline, 5-hydroxytryptamine, p-hydroxyamphetamine, isoprenaline, salbutamol and l-naphthol were all specific substrates for the M form of the enzyme. Paracetamol, a mixed substrate, was predominantly metabolized by the M form. Salicylamide at 5 microM was a substrate for the P form but became and M substrate at higher concentration. Phenol itself, a specific substrate for phenolsulphotransferase P at 10 microM, also became an M substrate at 1 mM concentration. These substrate specificities were confirmed with the selective inhibitor, dichloronitrophenol. In this study, we measured phenolsulphotransferase activity in platelets from 13 individuals selected on the basis of their wide variation in ability to sulphoconjugate paracetamol and salicylamide in vivo. There was no significant relationship between the in vivo pattern with either drug and the activity of platelet phenolsulphotransferase assayed with paracetamol or salicylamide respectively.

Platelet phenolsulphotransferase activity in Parkinson's disease

Mean platelet phenolsulphotransferase activity was significantly increased in L-dopa-treated parkinsonian patients compared with controls. The degree of rise was associated with dose of and duration of treatment with L-dopa and may thus represent an adaptive increase to circulating dopamine. Alternatively, the increase may reflect changes supervening with duration of illness.

Output of endogenous monoamine oxidase inhibitor in rats: effect of ethanol, tryptamine and tryptophan

Contrary to prediction, loading rats with tryptamine, tryptophan or methanol failed to produce any rise in endogenous monoamine oxidase inhibitor output, whilst ethanol administration resulted in a significantly decreased excretion. These findings, which provide no support for the hypothesis that the inhibitor is a beta-carboline, may shed some light on the tranquilizing effect of ethanol in man.

Primary hyperparathyroidism and osteoporosis. A case report

A case of osteoporosis secondary to primary hyperparathyroidism is reported. A 55-year-old woman presented with a history of persistent lumbar backache for 3 years; numerous radiographs taken during this period had shown 'osteoporosis in keeping with age'. Referral to the Endocrine Clinic to evaluate the osteoporosis resulted in baseline investigations which revealed a raised serum calcium level, further investigation of which led to the diagnosis of primary hyperparathyroidism. Recent studies have shown that, over the past two decades, diffuse undermineralization of the bones (osteopenia) is the most common radiological feature in primary hyperparathyroidism.

Phenylethylamine and phenylacetic acid in CSF of schizophrenics and healthy controls

Phenylethylamine (PEA) is an endogenous substance with amphetamine-like stimulant properties. On the basis of this ability an abnormal brain PEA metabolism has been proposed as an etiological factor in some forms of schizophrenia. In the present study 28 schizophrenic patients and 15 healthy controls were investigated. No significant difference from control values was found in PEA concentration in cerebrospinal fluid (CSF) of either untreated of neuroleptic-treated schizophrenics. However, 2 schizophrenics with highest BPRS scores had extremely high PES concentrations. Free phenylacetic acid (PAA), the major metabolite of PEA, was significantly decreased in ummedicated but not in drug-treated schizophrenics. Because of the assumed neuromodulatory properties of PEA, it is suggested that lowered PAA concentrations and the tendency for PEA to be elevated may imply that altered central neurotransmission occurs in certain forms of schizophrenia.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Corynebacterium diphtheriae endocarditis in an adult with congenital cyanotic heart disease. A case report

Corynebacterium diphtheriae is a very rare cause of both septicaemia and endocarditis. A case of endocarditis due to C. diphtheriae is reported and the clinical features and course of this case and other similar cases previously reported in the literature are compared.

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.

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.

A genetic study of platelet phenolsulphotransferase activity in normal and schizophrenic twins

In a series of 19 identical and 16 fraternal twin pairs, the activities of the two forms of the enzyme, phenolsulphotransferase, denominated M and P, were investigated in blood platelets. Both were shown to be under a high degree of genetic control. No differences were found between 11 schizophrenic patients from discordant twin pairs, compared with their well cotwins and 12 male and female volunteer twin pairs, for either form of the enzyme.