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Biomedical subjects

I M McIntyre

Publications and source records attributed to I M McIntyre.

At least 73 records · Page 4Linked to original sources
PubMed1985

Interpatient variations in antipsychotic therapy.

There is wide interpatient variability not only in therapeutic response to a given dose of antipsychotic drug but also in steady-state plasma levels and the presence and degree of unwanted pharmacologic effects. Such variations have been attributed to individual metabolism, pharmacologic differences, and age--all of which may need careful consideration in prescribing an appropriate dosage regimen for a given patient.

Age Factors↗
PubMed1984

The effect of 5,7-dihydroxytryptamine on the serum corticosterone resistance to suppression by dexamethasone.

The effect of serotonin (5-HT) deficiency on hypothalamic-pituitary-adrenal (HPA) activity was investigated by using 5,7-dihydroxytryptamine (5,7-DHT) for the selective destruction of central 5-HT neurons, and corticosterone response to suppression by dexamethasone as the index of HPA activity. Dexamethasone was shown to significantly suppress serum corticosterone levels in sham-treated rats, but did not suppress corticosterone in the 5,7-DHT-lesioned animals. This finding supports the conclusion that 5-HT is involved in the negative feedback mechanism of HPA regulation.

5,7-Dihydroxytryptamine↗
PubMed1984

Postmortem and regional changes of serotonin, 5-hydroxyindoleacetic acid, and tryptophan in brain.

Using a specific and sensitive high pressure liquid chromatographic technique for the measurement of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), and tryptophan (TRP), we found that there were no changes in 5-HT or 5-HIAA in the rat cortex when left in situ for 6 h at room temperature or 24 h at 4 degrees C. Only a minimal 14% increase in 5-HT was observed after 24 h at 4 degrees C in the striatum of the same animals. Concentrations of TRP, however, were increased significantly in both brain regions by these postmortem delay procedures. A second study revealed that there were significant regional 5-HT and 5-HIAA concentration differences within the cerebral cortex. The frontal cortex was shown to have the highest concentrations of 5-HT and 5-HIAA. Further, within the frontal cortex, 5-HIAA levels varied, showing apparent progressive rostral to caudal increases. 5-HT concentrations, however, remained constant within the frontal cortex. These results are discussed in reference to the conflicting reports of the previous human suicide and postmortem studies.

Animals↗
PubMed1984

Effects of pinealectomy and aging on the serum corticosterone circadian rhythm in rats.

Male Sprague-Dawley rats were housed in alternate light/dark conditions (light on, 7:00 AM, light off, 7:00 PM). Corticosterone was determined by radioimmunoassay from blood samples that were obtained by tail clip at 4-h intervals. Pinealectomized animals have shown significant increase of corticosterone levels at 7:00 AM, 11:00 AM and 7:00 PM in comparison with 2-month-old intact rats. There were no differences in serum corticosterone rhythm between 24-month-old and pinealectomized animals. Twelve-month-old rats have shown significant increase of corticosterone levels at 7:00 and 11:00 AM in comparison with 2-month-old animals. The age-associated increase of serum corticosterone and the similarity between serum corticosterone circadian rhythm in aged and pinealectomized animals suggest that an age-related decrease in melatonin production [Reiter et al., 1981] may contribute to age related changes of hypothalamic-pituitary adrenal axis regulation.

Aging↗
PubMed1984

Electroconvulsive shock: effect on pineal and hypothalamic indoles.

Chronic electroconvulsive shock (ECS) did not significantly alter pineal concentrations of melatonin. Statistically significant decreases of serotonin, however, were found in both the pineal and hypothalamus. These results support the previous reports of serotoninergic receptor supersensitivity following repeated ECS, and suggest serotoninergic involvement but do not necessarily exclude adrenergic involvement in the antidepressant effect of electroconvulsive therapy.

Animals↗
PubMed1984

Differential effect of carbidopa on the concentration of rat pineal and hypothalamic indoleamines.

Carbidopa, an aromatic acid decarboxylase inhibitor, has been shown to significantly decrease the pineal concentration of melatonin, N-acetyl serotonin (NAS), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) but not the hypothalamic concentrations of these indoles. Increased levels of 5-hydroxytryptophan (5-HTP) indicate that carbidopa directly inhibits 5-HTP decarboxylation, thus limiting 5-HT production. Possible practical implications of selective inhibition of pineal indoleamines by carbidopa are discussed.

5-Hydroxytryptophan↗
PubMed1983

Modulating role of lithium on dopamine turnover, prolactin release, and behavioral supersensitivity following haloperidol and reserpine.

The effects of haloperidol, reserpine, and concomitant lithium were evaluated in biochemical, endocrine, and behavioral studies in the rat. Concomitant administration of a chronic regimen of haloperidol and lithium did not prevent the development of tolerance as noted by dopamine metabolites in the striatum or olfactory tuberculum. Nor did chronic lithium alter behavioral response in rats treated with reserpine and challenged with the dopamine agonist apomorphine. Additionally, prolactin release was increased by haloperidol, but was not altered by acute or chronic lithium treatment. These findings are discussed in the light of present knowledge of pre- and postsynaptic receptor changes and the effects of lithium.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1983

Maprotiline in affective illness. Plasma concentration and clinical response.

Twenty patients suffering from endogenous depression were treated with maprotiline for 4 weeks. Blood samples were collected at weekly intervals and severity of depression assessed using the Hamilton Depression Rating Scale. No simple relationship between plasma maprotiline concentration and amelioration score was observed at week 3 (rs = 0.25) or week 4 (rs = -0.05). No significant difference in plasma concentrations between responders and non-responders was observed at week 4. Maprotiline was effective as an antidepressant in some patients.

Adolescent↗
PubMed1983

Zimelidine: a placebo-controlled trial in depression.

Twenty-eight hospital inpatients with a primary major depressive disorder were treated with either zimelidine or placebo. Patients were matched for age, sex, and initial severity of depression and assigned double blind to the treatment regimen. An initial dosage of 150 mg/day was used for up to 6 weeks. Zimelidine was significantly more effective in alleviating the symptoms of depression than placebo, with 82% of zimelidine and 25% of placebo patients showing clinical improvement. There were few complaints of severe side effects in zimelidine-treated patients, and few effects on the cardiovascular system. Two zimelidine-treated patients were withdrawn for suspected drug-related adverse events. Zimelidine was a safe, effective antidepressant in this group of patients.

Adolescent↗
PubMed1983

Aging and cortisol resistance to suppression by dexamethasone: a positive correlation.

Cortisol resistance to suppression by 0.5 mg of dexamethasone given at 11 p.m. was studied in 30 normal subjects, 17 to 78 years of age. Serum cortisol concentrations were determined by radioimmunoassay. A strong positive correlation was found between age and cortisol concentrations 9 hours after dexamethasone administration. The data suggest that aging, per se, might contribute to the increased cortisol resistance to suppression by dexamethasone reported in depression and dementia.

Adolescent↗
PubMed1981

Determination of nomifensine plasma concentrations: a comparison of radioimmunoassay and gas chromatography.

1 A gas-liquid chromatography (g.l.c.) method for measurement of the antidepressant nomifensine was developed and compared for precision, accuracy, sensitivity and convenience with radioimmunoassay (RIA). 2 No significant difference was found between the two techniques for unconjugated nomifensine (y = 1.07x = 2.7; r = 0.996) or total nomifensine (y = 1.;02x + 0.02; r = 0.999). 3 RIA proved more sensitive than g.l.c. (detection limit of RIA being 1 microgram/l and g.l.c. 5 micrograms/l). 4 RIA was found to be a more convenient technique (up to 50 samples per day with RIA, and 16 samples with g.l.c.).

Chromatography, Gas↗
PubMed1980

Plasma nomifensine concentration. Cardiological effects and clinical response.

Cardiological effects of nomifensine were studied in 10 endogenously depressed in-patients receiving up to 200 mg/day for 3 weeks. No significant cardiac effects were observed using His' bundle electrography and electrocardiography. 9 of the 10 patients showed a significant recovery from their depressive illness. Plasma nomifensine concentrations at day 22 were not correlated with clinical response, blood pressure, or electrocardiographic parameters. A negative correlation between A-H interval, in the His' bundle electrogram, and day 22 nomifensine concentration was observed.

Adolescent↗