Attempts to attenuate the 'cheese effect'. Combined drug therapy in depressive illness

Although earlier results, employing intravenous tyramine challenge, had indicated that a tricyclic antidepressant plus monoamine oxidase inhibitor drug combination might be free from the 'cheese effect', the experiments reported here, involving oral tyramine challenge during the combined therapy, showed that relaxation of a tyramine-free diet during such a drug regimen might be unsafe. Preliminary observations indicated that combined (-)-deprenyl plus nonselective monoamine oxidase inhibitor therapy might lead to an unacceptable degree of orthostatic hypotension without reduction in tyramine sensitivity.

Triazolam, an anomalous benzodiazepine receptor ligand: in vitro characterization of alprazolam and triazolam binding

Both alprazolam and triazolam displaced clonazepam (but not Ro 5-4864) from rat brain membranes with high affinity, showing them to act at central but not peripheral benzodiazepine receptors. At 0 degrees C, 10 microM gamma-aminobutyric acid (GABA) increased the ability of alprazolam, but not of triazolam, to displace ethyl-beta-carboline-3-carboxylate (beta-CCE) and Ro 15-1788 from these receptors. At 37 degrees C, GABA increased the affinity of the receptors for both drugs, with a +GABA/-GABA ratio of 1.5 for each in promoting Ro 15-1788 binding displacement. As both triazolam and alprazolam act as anxiolytics in vivo, the results at 37 degrees C would be compatible with the hypothesis that GABA causes an increase in affinity of drugs that act in this way, but the results at 0 degrees C would not be compatible. At 37 degrees C, alprazolam had a higher IC50 for the benzodiazepine receptor than at 0 degrees C, whereas triazolam showed the reverse effect. The relative IC50 values in vitro at 37 degrees C correlated better with the potency in vivo than those obtained at 0 degrees C. At 0 degrees C, both drugs showed Hill plots with slopes of 0.9-1 with beta-CCE and Ro 15-1788. At 37 degrees C, the slopes with triazolam were much reduced, indicating that the drug may have a selective action on a subclass of central benzodiazepine receptors. In the studies reported here, alprazolam behaved like other benzodiazepines, whereas triazolam showed several anomalous properties. It would be of interest if these properties could be related either to the drug's use as a hypnotic or to the side effects it sometimes induces.

Red wine contains a potent inhibitor of phenolsulphotransferase

Many ethanolic drinks, especially red wine, contain potent inhibitors of phenolsulphotransferase. At a dilution of 1/75 from the original beverage, extracts from six types of red wine inhibited human platelet phenolsulphotransferase P by a mean of 99% and human platelet phenolsulphotransferase M by 12%. Such extracts had no significant effect on rat liver monoamine oxidase A or human platelet monoamine oxidase B. The inhibitors, which have not yet been identified, can be extracted into ethyl acetate at acid or neutral pH. Thus, they are not monoamines. Flavonoid phenols are plausible candidates. As phenolsulphotransferase M and P are involved in the metabolism of many phenols, including drugs, the inhibition of these enzymes could result in the enhancement of pharmacological potency and have important clinical consequences.

Advanced osteitis fibrosa cystica in the absence of phalangeal subperiosteal resorption. A case report and review of the literature

A case of primary hyperparathyroidism with advanced osteitis fibrosa cystica but without any subperiosteal phalangeal bone resorption is described. A review of this unusual radiological feature is presented. High-detail magnification radiography (microradiography) is advocated for the early diagnosis of bony defects in hyperparathyroidism.

The genetics of diabetes mellitus, including the South African perspective

By and large, essential diabetes mellitus is thought to be 50% inherited and 50% environmental. In insulin-dependent diabetes mellitus (IDDM) there is a strong link with the HLA system with regard to the inheritance of 'susceptible' diabetic genes, especially the DR3 and DR4 alleles. In IDDM environmental factors act in a predisposed individual to initiate an immune response with resultant beta-cell damage and destruction. Non-insulin-dependent diabetes mellitus (NIDDM) has no clear HLA link, but has been shown in studies of twins to have a stronger genetic basis than IDDM. In NIDDM environmental factors (race, ethnicity, diet, obesity) have an important influence on the clinical expression of the disease and the severity of complications in a genetically predisposed individual. The non-insulin-dependent diabetes of the young (NIDDY) variant and the phenomenon of chlorpropamide-primed alcohol-induced flushing both underline the heterogeneity of NIDDM. Because of the heterogeneous nature and multifactorial inheritance pattern of diabetes mellitus, accurate genetic counselling is not possible as yet. However, data to date suggest that it is unwise to advise prospective parents not to procreate, since the overall risk of the development of clinical diabetes mellitus is extremely low.

The prevalence of diet-induced migraine

Nineteen percent of about 490 patients with classical or common migraine reported that headaches can be precipitated by chocolate, 18% by cheese and 11% by citrus fruit, and a highly significant majority of these patients were sensitive to all three foods. Twenty-nine percent of the patients reported sensitivity to alcohol; again this was significantly associated with sensitivity to the three food stuffs, though a substantial number of patients were sensitive to alcohol but not foods. Thirty-one percent of 331 female patients believed that oral contraceptives precipitated headaches, but this could not be related to any dietary response. Patients with affected relatives were significantly more likely to report sensitivity to alcohol and chocolate; sensitivity to cheese and citrus fruit was less strongly related, and there was no relationship at all for oral contraceptives. These correlations suggest that food induced headaches are mediated by chemical constituents common to these foods.

Exercise increases endogenous urinary monoamine oxidase benzodiazepine receptor ligand inhibitory activity in normal children

This study shows that in normal children the stress of maximal exercise induced not only activation of the sympathetic nervous system but also an increased urinary output of both MAO inhibitory activity and [3H]flunitrazepam binding to rat cerebellar membranes inhibitory activity.

Platelet monoamine oxidase and phenolsulphotransferase M and P in cancer

Phenolsulphotransferase and monoamine oxidase inactivate a wide range of dietary and endogenous phenols/monoamines by sulphoconjugation and oxidative deamination respectively. In this study, both enzymes were measured in platelets from cancer patients and controls. Of the two variants of phenolsulphotransferase, activity of the P form was normal in all groups. Activity of the M form was, however, significantly less than control values in patients with cancer of the rectum and bowel but not in other cancer patient groups. If this finding reflects enzyme activity elsewhere in the body and is not merely a manifestation of an abnormal platelet population, the deficit could expose affected subjects to the action of potentially carcinogenic dietary phenols. Platelet monoamine oxidase activity was significantly raised in the cancer group as a whole, and in all sub-types investigated apart from breast cancer. The increase in the cancer group as a whole was independent of sex, age, drugs, radiotherapy, smoking or platelet count. Its mechanism and significance are unknown but there may be links with the patients' psychiatric state.

Excretion of catecholamines and their metabolites in transplantable rat phaeochromocytoma

The urinary excretion pattern of catecholamines and their metabolites was studied in rats bearing a subcutaneous transplantable phaeochromocytoma. Compared with normal rats, tumour-bearing animals showed a markedly raised excretion of dopamine, noradrenaline and adrenaline, together with certain of their major acidic and alcoholic metabolites. No evidence of increased octopamine production could be obtained. There was a significant correlation between the output of dopamine and its metabolites, allowing accurate assessment of dopamine turnover rates which were comparable with those observed in human phaeochromocytoma. Tumour development, as determined by tumour weight, also correlated significantly with urinary excretion of noradrenaline and dopamine. Rat phaeochromocytoma appears to be a useful model for the human tumour.

Low platelet monoamine oxidase activity in headache: no correlation with phenolsulphotransferase, succinate dehydrogenase, platelet preparation method or smoking

Platelet monoamine oxidase activity in male migrainous and cluster headache patients was significantly lower than in male controls, confirming our previous study. The activity range showed a normal distribution and low mean values could not be attributed to a subgroup with particularly low activity. When Corash 's platelet preparation method was used, with its high platelet yield, specific enzyme activities of a similar order were obtained. Thus, the low values encountered were not due to abnormal recovery within the platelet population. Two other enzyme activities, phenolsulphotransferase M and succinate dehydrogenase, were also measured in the same platelet samples. Although low succinate dehydrogenase activity was identified in the headache groups, it appeared to represent a separate phenomenon and there was no significant correlation between activity of either enzyme and that of monoamine oxidase. This shows that the low activity of platelet monoamine oxidase in headache is not related to a generalised platelet enzyme deficit. It was also shown that the low monoamine oxidase activity in the headache patients could not be attributed to smoking.

Variation of the spleen-liver activity ratio due to a change in position

The ratio of splenic to hepatic activity in the posterior view of a Tc-99m SC liver-spleen scan has been used as an indicator of parenchymal disease. Analysis of liver-spleen scans from a series of patients acquired in both the supine and erect positions revealed that the spleen-liver ratio varied considerably with a change in the patient position. Qualitatively there was a shift of colloid from the liver to the spleen in five of 18 supine views and ten of 18 erect views. Quantitative analysis of 37 cases showed that the median erect spleen-liver ratio was 20% greater than the spleen-liver ratio observed in supine patients. Criteria for an abnormal spleen-liver ratio need to be established in each position.

Isolated adrenocorticotrophic hormone deficiency in the absence of polyglandular endocrinopathy. A case report

A 64-year-old woman presented with recurrent episodes of confusion and nonspecific abdominal symptoms associated with hyponatraemia, which prompted a provisional diagnosis of the syndrome of inappropriate antidiuretic hormone secretion. Further investigation revealed evidence of hypocortisolaemia secondary to isolated adrenocorticotrophic hormone (ACTH) deficiency, which was successfully treated with steroid therapy. The clinical spectrum and aetiological associations of isolated ACTH deficiency are reviewed.

Characterization of human brain phenolsulphotransferase

Both human phenolsulphotransferase M (for monoamines) and P (for phenol) were detected in eight out of twelve brains examined postmortem. Activity values were low compared with those in other human tissues and in brains from other species. The activity of both forms was unevenly distributed in different brain regions in a pattern different from that of the monoamines. From a study of substrate specificity, Km values, and inhibitor sensitivity, the two forms of the human brain enzyme did not appear to differ from their counterparts in platelet.

The CT detection of thymic hyperplasia in association with thyrotoxicosis: case report

A thymic mass was diagnosed by computed tomography in a young male with an anterior mediastinal mass demonstrated by chest X-ray. The association of thymic hyperplasia and thyrotoxicosis is discussed and the importance of CT in the evaluation of anterior mediastinal masses in patients with thyrotoxicosis is emphasized. Micronodular enlargement of the thymus is a common association of Graves' disease in contradistinction to the rare detection of radiologically visible thymic masses in this condition.

Pressor sensitivity to tyramine in patients with headache: relationship to platelet monoamine oxidase and to dietary provocation

The pressor responses to oral and intravenous tyramine were not different from controls in migrainous patients with or without a history of attacks triggered by foods. However, patients who reported a dietary trigger were more likely to develop headache after tyramine administration than those without such a dietary history. Pressor responses to intravenous tyramine in patients with cluster headache were indistinguishable from controls. A group of five males with platelet monoamine oxidase activity one standard deviation or more below that of male controls required less intravenous tyramine to raise blood pressure by 30 mm Hg than males with monoamine oxidase levels within one standard deviation of the controls. This finding suggests that platelet monoamine oxidase activity to some extent reflects that of total body monoamine oxidase A plus B.

Tyramine-induced noradrenaline release from rat brain slices: prevention by (-)-deprenyl

Clorgyline (1 and 10 microM) and (+)-deprenyl (10 microM) both significantly potentiated the tyramine (100 microM)-induced release of [3H]-noradrenaline from rat cerebral cortex slices. (-)-Deprenyl (50 microM) significantly reduced it, while lower concentrations had no effect on noradrenaline release. However, in combination, 1 microM (-)-deprenyl blocked the release-facilitating action of 1 microM clorgyline, and 10 microM (-)-deprenyl that of 10 microM (+)-deprenyl. Low concentrations of (+)- and (-)-deprenyl (1 and 10 microM), both selectively inhibited phenylethylamine oxidation by monoamine oxidase B. Higher concentrations of (-)-deprenyl (20 and 50 microM) also inhibited 5-hydroxytryptamine oxidation by monoamine oxidase A. Clorgyline (1 and 10 microM) inhibited both enzymes. Thus, the effects of these drugs on noradrenaline-release cannot be explained solely in terms of irreversible inhibition of monoamine oxidase A and B, and other possible mechanisms are discussed. If the brain-slice model faithfully mirrors the sequence of events manifesting peripherally as the tyramine hypertensive response ('cheese effect'), then it is possible that low doses of (-)-deprenyl, administered with antidepressant monoamine oxidase inhibitors, can prevent this adverse reaction.

New endogenous benzodiazepine receptor ligand in human urine: identity with endogenous monoamine oxidase inhibitor?

Normal human urine contains both monoamine oxidase-inhibiting and benzodiazepine receptor-binding material. Each was extracted into ethyl acetate at pH 1 and subjected to high performance liquid chromatography: they ran similarly, showing three major peaks. The correlation coefficient between the pattern of MAO inhibition and inhibition of 3H-flunitrazepam binding to benzodiazepine receptors in the second half of the elution process was 0.78 (p less than 0.001): most UV-absorbing material present was eluted earlier in the run. These results are compatible with, although they do not prove, the hypothesis that the endogenous MAO inhibitor, previously shown to be increased in stress, is also an endogenous inhibitor of 3H-flunitrazepam binding to the benzodiazepine receptor. This material is different from other putative endogenous ligands: it migrates more rapidly than the potent but artefactual beta-carboline-3-carboxylic acid ethyl ester previously isolated from human urine; nor can the effect we have identified derive from harmane, inosine, hypoxanthine or nicotinamide which fail to extract into ethyl acetate at pH 1.

Monoamine oxidase inhibitors and their pharmacological significance

The role of deprenyl, a selective monoamine oxidase B inhibitor, in the treatment of Parkinson's disease has been evaluated with special reference to the multiple pharmacological actions of the monoamine oxidase-inhibitory group of drugs.

Clinical and pharmacological problems of deprenyl (selegiline) treatment in Parkinson's disease

The clinical pharmacology concerned in the evolution of deprenyl as an adjuvant in the treatment of Parkinson's disease is briefly reviewed, with an assessment of its therapeutic potential. Experiments to clarify its mode of action are described, indicating that its clinical effects do not depend upon its amphetamine metabolites.

Scintigraphic and sonographic diagnosis of neonatal mesoblastic nephroma. Case report

The morphologic characteristics of mesoblastic nephroma result in a scintigraphic appearance which distinguishes this benign neonatal tumor from Wilms' tumor. This case report describes a patient in whom the use of scintigraphy and real-time sonography permitted preoperative diagnosis of mesoblastic nephroma.