Studies of selective and reversible monoamine oxidase inhibitors

Several selective and reversible monoamine oxidase inhibitors (MAOIs) have recently become available. Preliminary studies suggest that these compounds have antidepressant effects and may offer significant safety and side effect advantages over classical MAOIs. Pilot studies with 1-deprenyl, a selective MAO-B inhibitor, indicate that it may be most effective for patients with nonendogenous depression and for those (endogenous or nonendogenous) who present with certain reverse vegetative signs. The drug appears ineffective in depressed patients with associated panic attacks and phobic symptoms. An alternative approach in the development of safer, effective MAOIs is the use of rapidly reversible MAO-A inhibitors, such as moclobemide, that carry less risk of a hypertensive reaction and yet appear to be effective antidepressants. As selective MAO-A and MAO-B inhibition may be effective in different depressive subtypes and may have different side effects, these drugs are valuable pharmacologic probes for studying the biochemical bases of depressive disorders.

Postmortem monoamine oxidase enzyme kinetics in the frontal cortex of suicide victims and controls

Serotonin, a preferred monoamine oxidase (MAO) A substrate may be deficient centrally in suicide victims. In postmortem samples of frontal cortex from suicide victims we demonstrated receptor changes in the serotonergic system supportive of this hypothesis. These changes were not accompanied in this series of brain samples by alterations in either MAO A or B enzyme kinetics. Thus brain MAO A is not a useful indicator of altered serotonergic function in suicide victims. We did confirm an age-related increase in cortical MAO B but not MAO A enzyme concentrations in both controls and suicide victims.

Low prevalence of mitral valve prolapse in patients with panic disorder

In 25 patients with panic attacks the prevalence of mitral valve prolapse was 8%, close to that in the general population. The higher rates in previous reports may be due to differences in prolapse criteria, sampling techniques, or the samples' sex ratios.

Characterization of serotonin binding sites on human platelets

A high affinity, saturable 3H-spiroperidol binding site was identified for the first time on the intact human platelet, with drug affinities comparable to the serotonin-2 (S-2) receptor in human frontal cortex. The site was characterized by a KD of 2.7 +/- 0.3nM and a Bmax of 1.4 +/- 0.2 pmoles/10(8) platelets. A 3H-serotonin binding site was also found, with a KD of 42 +/- 8 nM, which appeared to represent the serotonin uptake site. No 3H-serotonin binding site with features of the serotonin-1 (S-1) receptor in brain was found on the platelet. Assay of 3H-spiroperidol binding to platelets may serve as an easily applied model for studying S-2 receptor function in man, and its relationship to age, hormonal, drug, and disease effects.

Central catecholamine metabolism in vivo and the cognitive and motor deficits in Parkinson's disease

Cerebrospinal fluid levels of homovanillic acid (HVA) in unmedicated patients with Parkinson's disease were 45% of levels in control subjects. Levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) and platelet monoamine oxidase activity (MAO) did not differ. Within the Parkinson's disease group platelet MAO B activity correlated with HVA (an MAO B substrate) but not MHPG (an MAO A substrate). A mild global dementia was found that did not correlate with the more severe motor deficit. There was a negative correlation between the motor deficit and HVA levels but not with MHPG. Cognitive functioning correlated positively with platelet MAO, and the ratio of HVA to MHPG levels and negatively with MHPG alone. It is postulated that dopaminergic and noradrenergic activity or the functional balance between these systems may contribute to the observed cognitive dysfunction.

Psychotic vs. nonpsychotic depression: comparison of treatment response

This retrospective study compared the treatment responses of 34 primary, unipolar depressives without psychotic features and 30 with psychotic features. Patients were diagnosed by Research Diagnostic Criteria and received trials of tricyclic antidepressants, antipsychotics, the combination of the two, electroconvulsive therapy, or placebo and psychotherapy. Only three of 18 psychotic patients vs. 17 of 23 nonpsychotic patients responded to antidepressants alone. Electroconvulsive therapy and the combination of antipsychotic and antidepressant medication gave better responses. These data suggest that major depressive disorder with psychotic features is best considered as a distinct subtype rather than a severe variant of major depression.

Trazodone hydrochloride: a wide spectrum antidepressant with a unique pharmacological profile. A review of its neurochemical effects, pharmacology, clinical efficacy, and toxicology

Trazodone is a new antidepressant agent that was recently introduced in the United States. It has a unique pharmacological profile that is not typical of either tricyclic or monoamine oxidase inhibitor antidepressants. As such it represents a new class of antidepressant drugs. The efficacy of trazodone has been clearly established in comparative studies with imipramine and amitriptyline. Major depression is the principal indication for its use, but good results have been shown in a wide variety of depressive subtypes. Of particular importance is the low frequency of adverse reactions seen with this drug.

Altered platelet serotonin uptake kinetics in schizophrenia and depression

Platelet uptake of serotonin (5-HT) was studied in drug-free groups of normal controls, depressives and schizophrenics. The Michaelis constant was significantly higher in both the schizophrenics and the depressives than in the controls. The Vmax did not differ significantly between the three groups. Uptake velocity at low substrate concentrations was significantly lower in the schizophrenic group and showed a similar trend in the depressives. There were no significant differences in Km or Vmax when depressives wee subclassified as unipolar and bipolar. There were no significant correlations between 5-HT uptake kinetics and severity of illness. These findings raise the possibility of a structural defect inthe 5-HT reuptake system in the major psychoses that reduces the affinity of the carrier for the amine. This alteration, if present in central serotonergic neurons, may play a role in the etiology and pathogenesis of depression and schizophrenia.

Effect of lithium ingestion on water and electrolyte transport in rat intestine

The effect of lithium ingestion on intestinal electrolyte and water transport was studied in adult Sprague-Dawley rats. We fed animals a lithium-supplemented diet for 1, 2, 4, or 16 wk before in vivo perfusion of the jejunum and colon. Lithium feeding did not alter jejunal transport of water, electrolytes, or glucose, However, at 4 and 16 wk (16-wk data given) the colon increased net water (168%), sodium (160%), and chloride (140%) absorptions, and the transmural potential difference (396%) as compared with control animals. In addition, the colon absorbed both bicarbonate and potassium against an unfavorable electrochemical gradient. The increased colonic sodium absorption was not associated with an increase in mucosal Na+, K+-ATPase activity. Furthermore, in lithium-fed animals deoxycorticosterone acetate stimulated mucosal Na+, K+-ATPase activity, but it did not further increase net sodium absorption. Neither jejunal nor colonic electrolyte transport was affected 24 h after being gavage-fed lithium. These results suggest that chronic lithium ingestion has a unique mechanism of action as other means of chronically increasing sodium absorption are associated with increased mucosal Na+, K+-ATPase activity.

Central amine metabolism in Alzheimer's disease: in vivo relationship to cognitive deficit

Levels of the amine metabolites homovanillic acid (HVA) and methoxyhydroxyphenylglycol (MHPG) were measured in the cerebrospinal (CSF) fluid of drug-free patients with Alzheimer's disease and compared to levels in a group of controls. No significant differences were found in CSF HVA and MHPG, although the Alzheimer's group was severely demented. Platelet monoamine oxidase (MAO) enzyme kinetics were measured and did not differ between controls and Alzheimer patients. The degree of dementia did not show any significant correlation with the levels of HVA or MHPG. It was concluded that, unlike previous reports in the literature, the dementia of Alzheimer's disease was not related to changes in central catecholamine metabolism nor was it associated with increased platelet MAO activity.

A controlled study of trazodone, imipramine, and placebo in outpatients with endogenous depression

A 4-wk double-blind controlled study of the antidepressant efficacy of the triazolopyridine derivative trazodone, in contrast to imipramine and placebo, was carried out in 30 endogenously depressed outpatients. Trazodone was found to be equivalent in efficacy to imipramine and statistically significantly superior to placebo. Trazodone showed a significant antidepressant effect relative to placebo when outcome was measured after only 7 days of treatment. This antidepressant effect was sustained for at least 5 mo as indicated by an open study phase following the double-bind study. Side effects, particularly anticholinergic properties, were significantly less apparent on trazodone compared to imipramine. A limited study of the relationship of trazodone plasma levels to therapeutic outcome revealed no simple linear relationship and represents a direction for future research.

Monoamine oxidase activity and enzyme kinetics in three subpopulations of density-fractionated platelets in chronic paranoid schizophrenics

Platelet monoamine oxidase (MAO) activity was studied in three subpopulations of density-fractionated platelets in 15 unmedicated chronic paranoid schizophrenic patients and contrasted with normal controls. No significant difference in MAO activity was found in any of the three platelet fractions in schizophrenics compared to controls. Enzyme kinetic studies performed on the intermediate-density platelet fraction demonstrated no significant differences in Vmax or Michaelis' constant (Km) between schizophrenics and controls, but showed that the higher platelet MAO activity reported in females compared to male is due to a significantly greater Vmax rather than altered Km. It is suggested that conflicting results reported in the literature regarding platelet MAO in schizophrenia are not related to the platelet subpopulations studied but are largely due to the selected patient populations.

Mental symptoms in Huntington's disease and a possible primary aminergic neuron lesion

Monoamine oxidase activity was higher in the cerebral cortex and basal ganglia of patients dying from Huntington's disease than in controls. Enzyme kinetics and multiple substrate studies indicated that the increased activity was due to elevated concentrations of monoamine oxidase type B. Concentrations of homovanillic acid were increased in the cerebral cortex but not in the basal ganglia of brains of patients with Huntington's disease. These changes may represent a primary aminergic lesion that could underlie some of the mental symptoms of this disease.

Fever with dissecting aneurysm of the aorta

Following acute aortic dissection, it two of the four cases we describe the patients experienced a prolonged febrile syndrome which spontaneously resolved five and 11 weeks later. Because of fever and a murmur of aortic regurgitation, the two other patients with aortic dissection were initially treated for acute bacterial endocarditis. These four cases serve to re-emphasize fever as an important clinical manifestation of dissecting aneurysm of the aorta.

Combination antibiotic therapy in staphylococcal endocarditis. The use of methicillin sodium-gentamicin sulfate therapy

The addition of gentamicin therapy in a case of S aureua endocarditis, in which the response to methicillin therapy alone was unsatisfactory, resulted in clinical improvement, enhanced serum bactericidal activity, and a bacteriologic cure. Gentamicin and methicillin were synergistic in vitro. Since the mortality in staphlococcal endocarditis remains exceedingly high, we suggest that the combination of a cell wall active antibiotic, such as methicillin, and an aminoglycoside may prove to be effective alternate theraphy for this disease.

Unusual manifestation of tuberculosis: TE fistula

Fistulas between the tracheobronchial tree and the esophagus (TE fistula) caused by tuberculosis are rare; usually they are associated with readily apparent pulmonary and/or mediastinal infection, and require surgical management. The patient we describe presented with a TE fistula as the only manifestation of active tuberculosis. This case represents the first report of successful nonsurgical treatment of tuberculous TE fistulas.