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Biomedical subjects

R D Gibbons

Publications and source records attributed to R D Gibbons.

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

Efficacy of ECT: a meta-analysis.

The authors analyzed several rigorously controlled studies that compared the efficacy of ECT with that of simulated ECT, placebo, and antidepressants. The data from these studies were combined statistically (with the Mantel-Haenszel method for the combination of fourfold tables), showing ECT's clear superiority over all these other forms of treatment for severe depression. The authors similarly analyzed the data from several studies comparing the efficacy of unilateral nondominant ECT with that of bilateral ECT and found no significant difference in their efficacy.

Antidepressive Agents, Tricyclic↗
PubMed1985

Volatile organic compounds in exhaled air from patients with lung cancer.

Using a specially developed breath collection technique and computer-assisted gas chromatography/mass spectrometry (GC/MS), we have identified in the exhaled air of lung cancer patients several volatile organic compounds that appear to be associated with the disease. The GC/MS profiles of 12 samples from lung cancer patients and 17 control samples were analyzed by using general computerized statistical procedures to distinguish lung cancer patients from controls. The selected volatile compounds had sufficient diagnostic power in the GC/MS profiles to allow almost complete differentiation between the two groups in a limited patient population.

Adenocarcinoma↗
PubMed1984

Influence of age, sex and osteogenesis imperfecta on count, protein content, and monoamine oxidase activity of human thrombocytes.

We determined the effect of count, age (2 to 24 year), sex, and osteogenesis imperfecta (OI) on the protein content and monoamine oxidase activity in human platelets. The reaction rate in presence of paramethoxybenzylamine was assessed in a sensitive and continuously recording spectrophotometric system. Platelets harvested from control subjects and OI patients displayed significant inverse linear correlations between count and protein content; there was near-constancy of the products of the two variables. The effects of age, sex, and osteogenesis imperfecta on protein content, count, and MAO activity were assessed by multivariate analysis of variance. It was found that, with increasing age, the count increased linearly and the protein content decreased. In patients with OI the protein content was depressed and monoamine oxidase activity elevated regardless of whether the latter was calculated on the basis of pellet protein or of count. The data suggest that, in osteogenesis imperfecta, thrombocytic monoamine and protein metabolism deviate from that of controls.

Adolescent↗
PubMed1984

Evaluation of lithium therapy for alcoholism.

The efficacy of lithium therapy for alcoholism was examined in 84 alcoholic volunteers admitted for rehabilitation. Subjects were randomly assigned to a lithium or placebo treatment condition for 18 months, and were reinterviewed monthly to document their compliance, drinking status, and mood. Two separate factors contributed to abstinent outcome: therapeutic serum lithium levels (greater than or equal to 0.4 mEq/L) and medication compliance. Recommendations are proposed for studying compliance effects in future treatment studies.

Adult↗
PubMed1984

Mixture distributions in psychiatric research.

This paper describes the application of Gaussian mixture distributions to biological marker research in psychiatry. Mixtures of univariate and multivariate normal distributions can be used to determine if diagnostically similar psychiatric patients belong to biologically distinct subpopulations. The resulting biological subtypes may be important in understanding the etiology of psychiatric disorders. The general model and estimation procedure are described (EM algorithm; Dempster, Laird and Rubin 1977). The method is illustrated using two examples of biological data: (1) red cell membranes and monoamine oxidase activity data in normal individuals having no family history of psychiatric illness, the first-degree relatives of bipolar depressed patients and a heterogeneous patient population; and (2) smooth pursuit eye movements that classify relatives of schizophrenics, nonschizophrenics and normal controls into biologically distinct populations.

Bipolar Disorder↗
PubMed1983

Assessing anhedonia in psychiatric patients.

In two studies of depressed, manic, schizophrenic, and normal subjects, a scale for measuring the intensity of subjects' pleasureable responses to normally emjoyable situations (the Pleasure Scale) evidenced good internal reliability and moderate agreement with the Chapman Anhedonia Scale and Indexes of depressive symptom severity. Only the depressed patients showed extremely anhedonic responses. Although more than half the depressed patients evidenced pleasure scores in the normal range, about 185 of them seemed more anhedonic than any norma subject. A mixture analysis resolved depressed patient scores into two distinct distributions: a normal-range distribution (88% of depressives) and an extremely anhedonic distribution (12%). The findings provide some support for the existence of a qualitatively distinct subtype of major depression that has been variously defined an "endogenomorphic" or "melancholic."

Bipolar Disorder↗
PubMed1983

Lithium ion transport and affective disorders within families of bipolar patients. Identification of a major gene locus.

We have identified a genetic polymorphism in which one allele results in elevated RBC lithium ion ratios and also contributes to vulnerability to some forms of affective disorders. Interindividual variability in the lithium ion ratio (the ratio of the RBC to the plasma lithium ion concentration) is determined by variability in a lithium ion ratio (the ratio of the RBC to the plasma lithium ion concentration) is determined by variability in a lithium-sodium ion counterflow mechanism. Segregation analyses were conducted on lithium ion ratios in vitro in members of 120 normal families and on both the lithium ion ratio and the history of affective disorder in first-degree relatives of 31 bipolar patients. These analyses provided evidence for an autosomal major gene locus that influences the lithium ion ratio both in members of normal families and in relatives of bipolar patients. The allele at the major locus resulting in elevated lithium ion ratios was associated with an increased likelihood of psychiatric hospitalization among relatives of bipolar patients.

Alleles↗
PubMed1983

Depressive symptoms associated with dexamethasone resistance.

Using split sample discriminant function analysis on a series of 63 consecutive depressed outpatients, the authors identified several items on the Hamilton Depression Rating Scale that were associated with dexamethasone resistance (late and middle insomnia, retardation, somatic and psychic anxiety, and obsessive-compulsive symptoms), and several items that were associated with dexamethasone suppression (genital symptoms, somatic-general symptoms, hypochondriasis, early insomnia, and depersonalization). The accuracy of the classification function was 100% for the index split sample, 84% for the overall sample, and 72% for the other split sample. The implications of these findings are discussed.

Adult↗
PubMed1983

Relatives of unipolar and bipolar patients have normal pursuit.

Impaired smooth pursuit eye movements are significantly less prevalent among the first-degree relatives of patients who have major affective disorders than among the first-degree relatives of schizophrenics. The distribution of normal and abnormal smooth pursuit among the relatives of unipolar and bipolar patients does not differ from that of normal individuals having no family history of major psychosis. Smooth pursuit impairment is thus specific to relatives of schizophrenic patients and is not characteristic of relatives of patients with major affective disorders.

Adult↗
PubMed1983

The core symptoms of depression in medical and psychiatric patients.

The internal consistency of the Beck Depression Inventory (BDI) is assessed in 335 randomly selected medical inpatients, and in another sample of 101 depressed psychiatric inpatients with 104 interviewed normals. The data for the two samples were analyzed separately using a latent trait model. The analysis confirms that the BDI measures a single underlying dimension of depressive severity for both patient samples. Fourteen symptoms discriminate well for severity of depression in the psychiatric-normal sample, seven symptoms in the medical sample, and six symptoms in both samples. The latter six symptoms (suicidal ideation, sense of failure, sense of punishment, loss of social interest, indecision, and dissatisfaction) may represent criteria for depressive severity that are not confounded by the presence of physical illness or the attendant distress.

Adolescent↗
PubMed1982

A statistical model for the classification of imipramine response in depressed inpatients.

We present a statistical model, recently developed for application in mathematical economics, that yields empirical evidence for the existence of two distinct subtypes of depression. We reanalyze previously reported data on 65 depressed patients treated with imipramine and repeatedly rated on the Hamilton Rating Scale (HRS). The estimated model parameters suggest two underlying response processes. Patients in the first subgroup were initially more severely depressed (as measured by the total HRS score), but exhibited a rapid rate of symptomatic response over time. In contrast, patients in the second subgroup were initially less severely depressed, yet showed a much slower rate of improvement. These findings recommend a refinement of the clinical definitions of endogenous depression. While this model suggests that there are two underlying response processes, it does not classify individual patients. Subject classification was made possible by fitting an item-response model to the data. This model relates the 17 individual symptom ratings, at baseline, to the total post-treatment HRS scores. The results of this analysis suggest that the previously described relationship between high initial severity of depression and more rapid improvement over time is characteristic of subjects who exhibit initial motor retardation and decreased sexual interest. Graphical analysis clearly indicates that subjects who exhibit both motor retardation and decreased sexual interest at baseline have higher total HRS scores at baseline and show more pronounced improvement in total HRS scores in response to treatment with imipramine. Patients not exhibiting motor retardation and decreased sexual interest were less severely depressed initially and show virtually no clinical response over time.

Depressive Disorder↗
PubMed1982

Ion transport and adrenergic function in major affective disorder.

Altered functional levels of norepinephrine (NE) have been implicated in the etiology of affective disorders. Abnormalities of membrane ion transport have been postulated to underlie such neurotransmitter imbalances. To evaluate the role of these systems in the pathophysiology of specific affective syndromes, we have examined the NE metabolite MHPG and ion transport function in a cross-section of affective patients in different mood states. Analysis of those data reveals that plasma MHPG levels are dependent on mood state, with bipolar patients in the manic phase having significant elevations of this metabolite. In contrast, the red cell: plasma lithium ratio (LR) was independent of mood state and significantly elevated in a group of bipolar patients.

Affective Disorders, Psychotic↗
PubMed1980

Lateral eye movement and handedness as measures of functional brain asymmetry in learning disability.

Evidence is presented which suggests that learning disability is related to lateral asymmetry. Significant differences were found in lateral eye movement and handedness between a learning disabled group and a control group of normal learners. Left lateral eye movement and right handedness was the predominant pattern exhibited in learning disability. These results support Day's notion that left lateral eye movement is associated with educational difficulties. They also provide evidence concerning Orton's hypothesis that mixed cerebral dominance characterizes the learning disabled.

Child↗
PubMed1977

Comparative toxicities of enflurane, fluroxene and nitrous oxide at subanaesthetic concentrations in laboratory animals.

We compared the toxicities of subanesthetic concentrations of fluroxene, enflurane and nitrous oxide in mice, rats and guinea pigs which were in an active growth phase. Fluroxene produced a greater mortality and decrement in weight gain than enflurane and nitrous oxide despite administration of far lower concentrations. Enflurane, 0.1 MAC, resulted in a detrimental effect on weight and early mortality in mice but not in rats or guinea pigs. Nitrous oxide, 0.1 MAC, resulted in only a minor effect on weight gain in guinea pigs and an increased incidence of focal inflammatory liver changes in mice. No consistent injury to any organs other than liver or kidney were found.

Animals↗
PubMed1975

Comparative toxicities of halothane, isoflurane, and diethyl ether at subanesthetic concentrations in laboratory animals.

Effects of 35-day exposures to subanesthetic concentrations of halothane, isoflurane, and diethyl ether were measured in mice, rats, and guinea pigs which were in a phase of rapid body growth. Halothane produced a greater decrement in weight gain and a greater incidence of hepatic degenerative changes than isoflurane or diethyl ether despite its administration at lower anesthetic concentrations. Isoflurane results were intermediate between those of halothane and diethyl ether. No consistent injury to any organ other than the liver was found.

Anesthesia, Inhalation↗