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Biomedical subjects

S Bloch

Publications and source records attributed to S Bloch.

At least 73 records · Page 4Linked to original sources

Teaching psychiatric ethics.

In the last decade, we have witnessed a burgeoning of interest in ethical issues amongst psychiatrists. Teaching of the subject, however, remains at a rudimentary stage. Various approaches to such instruction are available, particularly modelling (students observe their experienced counterpart), the case method (examining specific clinical situations which involve a need for ethical decision-making), and the seminar approach (trainees are exposed to a core body of knowledge, mainly theoretical in nature). Faced with these different teaching models, the University of Oxford Department of Psychiatry has opted for a blend of all three approaches, which incorporates two goals: an increase in the trainees' sensitivity to the many intricate moral dilemmas facing the psychiatric profession; and their familiarity with salient concepts in moral philosophy which constitute a basis for ethical reasoning and which have a bearing on clinical practice. The teaching programme comprises the following: a pair of trainees prepares a presentation on an aspect of psychiatric ethics under the supervision of a senior psychiatrist. A moral philosopher assumes the role of discussant of the ethical problems raised by the trainees; this is followed by a general discussion. Topics have included involuntary hospitalization, dual loyalty, suicide, psychiatric diagnosis, and ethical issues in various spheres of psychiatric practice such as sex therapy, psychotherapy and child psychiatry. The approach has worked effectively and proved rewarding to all participants involved.

England↗

Psychotherapy and dysmorphophobia: a case report.

The treatment of patients with dysmorphophobia remains a confused matter, probably because of clinical heterogeneity. Our experience with the case reported in this paper suggests that psychodynamic psychotherapy is indicated for certain carefully selected patients.

Adult↗

Goals of treatment in diabetes: a comparison of doctors and parents of children with diabetes.

Treatment failure is usually understood as a problem of patient compliance. This paper suggests another approach: to see this problem as resulting from a difference in the goals of the two parties involved, the doctor and the patient. Comparison was made between the goals of doctors and those of parents in treating children with diabetes. Significant differences emerged between the goals. Parents' goals of treatment were governed more by avoidance of the short-term threat of diabetes (hypoglycemia); doctors' goals more by the long-term threat of diabetes (diabetic complications). The outcome of treatment (diabetic control) was more closely related to parents' than doctors' goals of control. These results indicate that doctors and patients do not always share the same goals in treatment. It is suggested that a more effective clinical alliance would result if the goals of the clinical team were at least made explicit, even if they were not always shared.

Adolescent↗

Chick brain glutamine synthetase and Mn2+-Mg2+ interactions.

Glutamine synthetase (GS) from the chick brain was purified to apparent homogeneity by ammonium sulfate fractionation followed by affinity chromatography, electrofocusing and Sephadex G-150 chromatography. The purified enzyme showed a single band on sodium dodecyl sulfate analysis in polyacrylamide gel. By sedimentation equilibrium analysis and gel electrophoresis analysis, it was shown that the enzyme has a subunit molecular weight of 45,000 and a native molecular weight of 364,000, which is consistent with an octameric structure. Sedimentation analysis in the presence of Mg2+ revealed three different forms of macromolecules corresponding respectively to a monomer, a tetramer and an octamer. Among eight cations tested (Ca2+, Co2+, Fe2+, Li+, Mg2+, Mn2+, Ni2+, Zn2+) only Co2+, Mg2+ and Mn2+ supported GS activity; the order of activatory ability was Mg2+ greater than Co2+ greater than Mn2+. The maximum activating effect of Mn2+ occurs only within a very narrow range of concentration: with an excess of cation causing strong inhibition of GS activity. For each cation, maximal GS activity occurs at a defined cation/ATP ratio. A regulatory system in which Mn2+, modulates the Mg2+ dependent GS activity, is proposed; such cation interactions may be of significance in the intracellular control of glutamine synthesis.

Animals↗

Glutamine synthetase and energy metabolism enzymes in cultivated chick neurons and astrocytes: modulation by serum and hydrocortisone.

Primary cultures of astroglial cells and of neurons obtained from chick embryos were grown in culture medium with and without serum added. The expression of glutamine synthetase (GS) in the cultured nerve cells was investigated immunocytochemically and biochemically. The cellular localization of GS in cerebellar tissue sections and in cerebral cortex of chick embryos was investigated by immunohistochemical staining. In tissue sections the enzyme is only present in astrocytes and their processes; neurons and their structures do not express the enzyme. In contrast, in pure neuronal primary cultures, a high level of GS was detected by biochemical and immunochemical methods. Thus, our results clearly indicate the presence of GS in pure neuronal cell cultures and its absence in this type of cells in vivo. Removal of serum from the culture medium enhanced GS levels in primary astrocyte cultures, but was without effect on GS activity in neurons. Addition of calf serum to the culture medium induces a two-fold increase of cellular lactate dehydrogenase (LDH) activity in neurons by increasing specifically the M subunit containing isoenzymes. The sensitivity of chick astroglial cells and neurons toward the GS inducing effect of hydrocortisone and modulation of its effect by serum was also investigated. Differences in the sensitivity of the two types of nerve cells in culture toward the GS inducing effect of hydrocortisone, and the effect of serum could be demonstrated.

Animals↗

Family life and diabetic control.

Seventy two children with diabetes and their parents were studied to examine the relationship between family functioning and diabetic control. Children in families characterised by cohesion, emotional expressiveness, lack of conflict and a mother satisfied with her marriage, had better diabetic control than children living in families with opposing characteristics. Children living with both biological parents or with a single parent had significantly better diabetic control than those living with a step-parent or adoptive parents. There was no relationship between social class, family income, employment status or educational attainment of either parent, and diabetic control.

Adaptation, Psychological↗

Informed consent and the psychiatric patient.

Informed consent is reviewed as it applies to psychiatric patients. Although new legislation, such as the Mental Health Act 1983, provides a useful safeguard for the protection of the civil rights of patients, it could actually reduce their humane care unless applied with sensitivity for the nature of their unique difficulties. In order to guard against this possibility, we suggest that legal requirements should be considered in light of the ethical principles which underlie them. Three principles are considered: those of autonomy (freedom); beneficence (paternalism); and the fiduciary principle (partnership). Psychotherapy is offered as a model for informed consent, which might be generalised to other clinical situations.

Beneficence↗

Glutamine synthetase and energy metabolism enzymes in cultured chick glial cells: modulation by dibutyryl cyclic AMP, hydrocortisone, and trypsinization.

Modifications induced by dibutyryl cyclic AMP (diBcAMP) and hydrocortisone in the energy metabolism of chick astroblasts in culture have been investigated. DiBcAMP does not modify the levels of enolase, malate dehydrogenase (MDH), total lactate dehydrogenase (LDH) and glutamine synthetase (GS) activities in these cultured glial cells. However, these cells can be sensitized to the nucleotide analog by trypsinization before seeding. The phenomenon affects specifically GS activity and the synthesis, with an inhibitory effect, of the H subunit of LDH. Addition of hydrocortisone to the culture medium stimulates MDH and GS activities of the cells; trypsinization accentuates the stimulatory effect on GS. This hormone also modifies the synthesis of H and M subunits of LDH in a positive and negative way respectively. The phenomenon is increased by trypsin treatment. The present studies indicate clearly that hydrocortisone generates in cultured chick glial cells metabolic modifications qualitatively different from those obtained by diBcAMP. It is suggested that trypsin treatment, by altering some protein constituents of the cell surface, modifies the adhesiveness of different cell types present in the cell suspension after dissociation of the brain and thus leads to select, in culture, a specific astroglial subpopulation.

Animals↗

Pigeon's eyes converge during feeding: evidence for frontal binocular fixation in a lateral-eyed bird.

Pigeons' head-in-space and eye-in-head positions were simultaneously recorded (EOG) in video during feeding. A linear correlation was found between the experimentally measured eye convergence (sum of both EOGs ) and grain parallax (calculated from interocular and eye-to-grain distances). This graded convergence of the eyes on approaching a target is considered evidence of frontal binocular fixation. Since such convergence prevails when the animal is forced to rely on frontal monocular or on lateral vision, a central mechanism controlling frontal fixation in the pigeon must be presupposed .

Animals↗

Interhemispheric differences in regional density of the normal brain.

In a study of regional variations in cerebral X-ray attenuation as measured by computed tomography, a relationship between bone-related beam hardening and lateralized hemispheric density differences was sought. The CT scans of 22 normal right-handed individuals were evaluated by calculating regional mean attenuation values and regional left-right differences in attenuation, comparing these to regional measurements of skull thickness. A statistically insignificant number of significant correlations was found. This is interpreted to mean that observed left-right hemispheric density differences are not due to beam-hardening through bone. It was also found that left-right differences in density persisted over the entirety of the evaluated slices, suggesting that this finding is due to inherent hemispheric structural differences.

Adult↗

Comparing frontal and lateral viewing in the pigeon. III. Different patterns of eye movements for binocular and monocular fixation.

The presence in the pigeon's retina of two areas of higher cellular density which we have shown mediate different visual functions, suggests the existence of two modes of fixation: a lateral monocular and a frontal binocular one. The participation of eye movements in these modes of fixation remained unexplored. We analyzed oculomotor behaviour in awake head-restrained pigeons by means of EOG and video film. Orienting saccades attaining up to 17 degrees from the resting positions could be elicited by presenting stimuli in different parts of the visual field. Two typical ocular patterns were consistently observed to the sudden presentation of large and novel stimuli: coordinated vergence of both eyes (even with one eye occluded) to stimulation within the frontal binocular field, and uncoordinated ipsilateral saccades to stimuli moving in one lateral field. Results point towards two different and reciprocally exclusive mechanisms of oculomotor control in the pigeon. The relevance of a trident mode of vision correlated to retinal organization and living praxis of some lateral-eyed vertebrates is discussed.

Animals↗

[Purification and characterization of glutamine synthetase from chicken brain].

A procedure for the isolation and purification to homogeneity of glutamine synthetase (E.C. 6.3.1.2.) from chick brain is described. The physico-chemical properties of the purified enzyme preparation are similar to those of other eucaryotic glutamine synthetases. The optimum activity of glutamine synthetase is dependent on the Mg++ to ATP ratio in the reaction mixture rather than on the magnesium or ATP concentrations. The characteristics of the enzyme studied through various phylogenetic trees suggest that this enzyme is preserved during evolution.

Animals↗

Trypsinization of chick glial cells before seeding: effects on energy metabolism enzymes and glutamine synthetase.

In order to test the possible involvement of surface proteins on some metabolical aspects of chick glial cell differentiation in culture, perturbations were induced on the glial cell surface membrane by limited trypsinization before seeding. The developmental changes of enzymes involved in the energy metabolism of the cell: malate dehydrogenase (MDH), glutamate dehydrogenase (GDH), hexokinase (HK), lactate dehydrogenase (LDH), enolase as well as glutamine synthetase (GS) were determined in trypsin treated cells and controls. The total protein and DNA content per dish was higher in treated cells than in controls, however the protein ratio towards DNA remained unchanged. The levels of GS, GDH, LDH, and enolase activities were significantly enhanced after trypsin treatment of the cells compared to controls. The enhanced value of total LDH activity is essentially the result of the increase of M subunit containing isoenzymes. Considering that a higher level of GS activity characterizes some maturation of the glial cells (as observed during the maturation of the chick brain) it is apparent that modifications of cell surface located factors, by trypsin treatment, induce differentiation phenomena at the functional state of the glial cells in culture. This may indicate that interactions located at the cell surface are involved in the modulation of key enzymes of the energy metabolism pathway.

Animals↗

Comparing frontal and lateral viewing in the pigeon. II. Velocity thresholds for movement discrimination.

Pigeons have been described as poor movement detectors when tested in the frontal binocular field. Retinal organization and behaviour suggest that motion sensitivity may be better in the lateral field. Pigeons were trained to discriminate the direction of moving square gratings (0.3 cyc/deg) appearing briefly (250 msec) contingent upon pecking a key (behavioural fixation). Stimuli were presented at isoacuity distance (40 cm) 25 degrees below the beak for frontal and 80 degrees back from the beak for lateral viewing. The animal had to discriminate the direction of movement for decreasing angular velocities. Results show that lateral motion sensitivity in the pigeon is 3 times better than frontal motion sensitivity. The fovea centralis, looking laterally, seems to be adapted for motion detection and may play a special role in the recognition of moving predators.

Animals↗

Humour in group psychotherapy.

The role of humour in group psychotherapy has received scant attention from both clinician and researcher. We have identified, and attempted to classify, several uses to which humour can be put in a group. We also point out the destructive potential of humour, and categorize its misapplications. We hope our scheme will serve as a framework within which systematic research can be conducted.

Defense Mechanisms↗

Cerebellopontine angle lipoma: a review.

Lipomas located in the cerebellopontine angle (CPA) have rarely been reported. With the advent of computed tomographic scanning and more sophisticated physiological diagnostic techniques, CPA lipomas are being reported more frequently. This paper reviews the world's literature on this lesion and summarizes the symptoms and signs, diagnostic studies, pathology, and surgical results. Recommendations regarding the therapy of this lesion are presented.

Adult↗