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Biomedical subjects

A Robertson

Publications and source records attributed to A Robertson.

At least 217 records · Page 12Linked to original sources
PubMed1984

Effect of 5-hydroxytryptophan on serum cortisol levels in major affective disorders. I. Enhanced response in depression and mania.

The serum cortisol concentration following administration of 5-hydroxytryptophan (5-HTP), 200 mg orally, a precursor of serotonin (5-HT), was significantly greater in unmedicated depressed and manic patients than in normal controls. Increases in serum cortisol levels greater than 5 micrograms/dL were significantly more frequent in both unmedicated depressed and manic patients than in the normal controls. There was significant test-retest reliability. Baseline serum cortisol concentration correlated negatively with the cortisol response to 5-HTP in normal controls. These results suggest increased 5-HT receptor sensitivity may be present, possibly in the hypothalamus or pituitary, in some patients with affective disorders. These results are consistent with the hypothesis that decreased serotonergic activity, which would be expected to produce increased 5-HT receptor sensitivity, may be present in both depression and mania.

5-Hydroxytryptophan↗
PubMed1984

Effect of 5-hydroxytryptophan on serum cortisol levels in major affective disorders. II. Relation to suicide, psychosis, and depressive symptoms.

Serum cortisol levels were significantly higher after administration of 5-hydroxytryptophan (5-HTP), 200 mg orally, in unmedicated patients with affective disorders than in controls. The magnitude of the serum cortisol increase correlated positively with the Schedule for Affective Disorders and Schizophrenia-Change (SADS-C) depression syndrome ratings and correlated negatively with psychotic symptoms in 26 patients with major depression. The serum cortisol response was greater in four depressed and three manic patients who made suicide attempts than in 33 patients who were not suicidal or only had suicidal thoughts. The cortisol response was also greater in patients with bipolar depression than in those with unipolar depression and those with a first-degree relative with an affective disorder. Absence of psychotic symptoms and commission of suicidal acts were associated with an increased cortisol response to 5-HTP in the depressed patients. The cortisol response to 5-HTP in the manic patients also tended to correlate with the SADS-C manic syndrome score.

5-Hydroxytryptophan↗
PubMed1984

Effect of 5-hydroxytryptophan on serum cortisol levels in major affective disorders. III. Effect of antidepressants and lithium carbonate.

Serum cortisol levels were significantly increased following administration of 5-hydroxytryptophan (5-HTP), 200 mg orally, to patients with affective disorders. A three- to five-week period of treatment with lithium carbonate or monoamine oxidase (MAO) inhibitor augmented the mean 5-HTP-induced increase in serum cortisol concentration in manic or depressed patients, respectively: tricyclic antidepressant (TCA) and second-generation antidepressant treatment diminished the mean serum cortisol response in patients with major depression. These results are consistent with the hypothesis that lithium carbonate may enhance serotonin (5-HT) receptor sensitivity, whereas TCA and second-generation antidepressants diminish 5-HT receptor sensitivity. The enhancement of the cortisol response to 5-HTP by MAO inhibitors may be due to decreased metabolism of 5-HT. It is important to assess the effect of thymoleptic drug treatment on various responses to biogenic amine precursors or agonists in patients rather than laboratory animals.

5-Hydroxytryptophan↗
PubMed1984

Growth hormone and prolactin response to apomorphine in schizophrenia and the major affective disorders. Relation to duration of illness and depressive symptoms.

The responses of serum prolactin (PRL) and growth hormone (GH) to the dopamine agonist apomorphine hydrochloride (0.75 mg subcutaneously) were studied in a large group of unmedicated hospitalized patients with functional psychoses. There were no differences in the GH response in various diagnostic groups. The PRL response was greater in patients with affective disorders. The GH response was inversely related to total duration of illness in the entire sample of patients, but this correlation was independent of age effect only in the group of patients with major depression. In schizophrenics, the effect of the two factors, age and duration of the illness, could not be separated. The apomorphine-induced GH response was significantly correlated with psychosis ratings and negative symptom scale scores. The apomorphine-induced PRL suppression correlated significantly with various measures of depression across diagnostic groups.

Adolescent↗
PubMed1984

Atypical neuroleptics clozapine and thioridazine enhance amphetamine-induced stereotypy.

The effects of the atypical neuroleptics clozapine and thioridazine and the typical neuroleptic pimozide on amphetamine-induced behavior were examined. Pimozide, as expected, blocked both amphetamine-induced locomotion and stereotypy. Thioridazine and clozapine antagonized the increases in locomotion produced by amphetamine, but produced increases in amphetamine-induced stereotypy and lowered the threshold dose for stereotypy. It is suggested that the increased stereotypy might partly account for the decreased locomotion, and that this might be a primary effect of these atypical neuroleptics. The data would also suggest that the use of amphetamine-induced stereotypy as a model for psychosis is inappropriate, as clozapine and thioridazine, which enhance stereotypy, are antipsychotic.

Animals↗
PubMed1984

Deviations from Hardy-Weinberg proportions: sampling variances and use in estimation of inbreeding coefficients.

An analysis is made of the distribution of deviations from Hardy-Weinberg proportions with k alleles and of estimates of inbreeding coefficients (f) obtained from these deviations. If f is small, the best estimate of f in large samples is shown to be 2 sigma i(Tii/Ni)/(k - 1), where Tii is an unbiased measure of the excess of the ith homozygote and Ni the number of the ith allele in the sample [frequency = Ni/(2N)]. No extra information is obtained from the Tij, where these are departures of numbers of heterozygotes from expectation. Alternatively, the best estimator can be computed from the Tij, ignoring the Tii. Also (1) the variance of the estimate of f equals 1/(N(k - 1] when all individuals in the sample are unrelated, and the test for f = 0 with 1 d.f. is given by the ratio of the estimate to its standard error; (2) the variance is reduced if some alleles are rare; and (3) if the sample consists of full-sib families of size n, the variance is increased by a proportion (n - 1)/4 but is not increased by a half-sib relationship. If f is not small, the structure of the population is of critical importance. (1) If the inbreeding is due to a proportion of inbred matings in an otherwise random-breeding population, f as determined from homozygote excess is the same for all genes and expressions are given for its sampling variance. (2) If the homozygote excess is due to population admixture, f is not the same for all genes. The above estimator is probably close to the best for all f values.

Alleles↗
PubMed1984

Exposure to oxides of nitrogen: respiratory symptoms and lung function in British coalminers.

Five hundred and sixty British coalminers with relatively high or relatively low exposures to oxides of nitrogen, based on measurements of concentrations of these gases at nine collieries over four years, and records of the men's places of work and colliery mining conditions over a total of eight years have been studied. Data on these men's respiratory symptoms and ventilatory capacity (FEV1), obtained as part of an epidemiological study of British coalminers, have been used to investigate possible adverse effects of exposure to oxides of nitrogen. Exposures to oxides of nitrogen were generally well below threshold limit values, though occasional peaks after shotfiring and during diesel locomotive use did exceed short term limits. No relationship was found between exposure and respiratory symptoms or decline in FEV1 nor was there any evidence of differences in symptoms of FEV1 between 44 pairs of men matched for age, dust exposure, smoking habit, coal rank, and type of work, but differing in respect of exposure to oxides of nitrogen. It has not been possible to detect any adverse effects on the health of this working population of the levels of nitrogen oxides that have occurred in British mines over the past decade. With the current levels of these gases, any long term effects on respiratory health are so small as to be undetectable in the presence of smoking and dust exposure.

Coal Mining↗
PubMed1983

Enhanced serum cortisol response to 5-hydroxytryptophan in depression and mania.

The serum cortisol responses to D,L-5-hydroxytryptophan (5-HTP), 200 mg per oral, in unmedicated depressed and manic patients, were both significantly greater than that of normal controls. The cortisol response to 5-HTP in depressed patients was significantly correlated with ratings of specific symptoms of depression. It was also greater in non-psychotic than in psychotic depressed patients as well as in those manic or depressed patients who attempted suicide compared to those who had not. In view of evidence for decreased brain serotonergic activity in depression and perhaps mania, the results suggest at least some serotonin receptors may be supersensitive in some patients with affective disorders.

Adult↗
PubMed1983

Drinking behavior following electrical stimulation of the subfornical organ in the rat.

Electrical stimulation of the subfornical organ (SFO) through implanted stainless-steel electrodes produced drinking in water-sated rats. Drinking was elicited primarily during the interstimulation (OFF) periods. Water intake in rats with hippocampal electrode placements occurred during both ON and OFF periods at current intensities (24-100 microA) similar to rats with SFO placements. These findings support the hypothesis that the SFO is involved in the central control of fluid balance.

Animals↗
PubMed1983

The effect of buspirone on prolactin and growth hormone secretion in man.

Buspirone hydrochloride, a compound with novel chemical structure, has been reported to be anxiolytic in man. Its mechanism of action as an anxiolytic is unknown, but preclinical studies have shown that it produces effects consistent with both a dopamine agonist and antagonist. In man, buspirone hydrochloride at doses of 30, 60, and 90 mg orally significantly elevated plasma prolactin (PRL) and growth hormone (GH) concentrations. The apparent increase in PRL secretion was dose dependent, but that of GH was not. The increase in PRL secretion could be due to a dopamine antagonist effect at the pituitary gland. A dopamine agonist action at hypothalamic dopamine receptors could account for the increase in GH secretion. Benzodiazepine anxiolytic drugs also increase serum GH levels in man, by a mechanism that has not been clearly established. It may be that buspirone and benzodiazepine drugs stimulate GH secretion by a common mechanism that is related to their anxiolytic actions.

Adult↗
PubMed1983

Effect of low-dose bromocriptine in treatment of psychosis: the dopamine autoreceptor-stimulation strategy.

Bromocriptine (0.5-6.0 mg/day) was administered to seven unmedicated chronic schizophrenic and two schizoaffective patients. Transient slight improvement was noted in four patients and marked improvement in one other. Clinical improvement was associated with nausea and drowsiness. These doses of bromocriptine stimulated serum growth hormone and inhibited serum prolactin levels in some subjects. These results suggest that bromocriptine may stimulate dopamine autoreceptors and, through this mechanism, attenuate symptoms in a small proportion of psychiatric patients.

Brain Chemistry↗