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Biomedical subjects

A Dickinson

Publications and source records attributed to A Dickinson.

108 records · Page 6Linked to original sources
PubMed1983

Natural history of patients with hyperprolactinaemia.

One hundred and nineteen women with sustained hyperprolactinaemia were followed for a mean duration of 5.5 years. Where pregnancy was desired, treatment with bromocriptine (+/- clomiphene) was effective in 86% of subjects. Following cessation of bromocriptine therapy one third of subjects whose initial serum prolactin (PRL) level was less than 4 times normal had a 'spontaneous' resolution of their hyperprolactinaemia and resumed cyclical menstrual activity and fertility. Subjects with higher PRL levels or those not treated with bromocriptine, did not show this beneficial effect. Pituitary or hypothalamic tumours were identified in 11% of subjects at the time of presentation and developed in a further 15.1% during follow-up. Most of these tumours were small, occurred more commonly when the PRL level was greater than 4 times normal, and were less likely to develop when treatment with bromocriptine had been administered. Bromocriptine therapy can thus be justified in hyperprolactinaemic subjects to reduce troublesome galactorrhoea, achieve pregnancy, improve the chance of a 'spontaneous' return of menstruation and fertility, control or reduce tumour growth where a pituitary tumour has been identified, and reduce the risk of tumour development in patients with normal plain X-rays of the pituitary fossa at the time of presentation.

Bromocriptine↗
PubMed1982

Atypical T lymphoproliferative disorder demonstrating in vitro suppressor and helper characteristics.

A patient initially diagnosed on surface marker status as having T cell chronic lymphatic leukaemia (T-CLL) was found to have arthropathy and recurrent pulmonary infarction associated with a high anti-DNA antibody titre. The T cell from this patient, on assessment in an in vitro pokeweed mitogen driven B cell system, demonstrated suppressor and helper characteristics but lacked antibody dependent cellular cytotoxicity (ADCC) activity and natural killer (NK) activity. Using peripheral blood mononuclear cells (PBM) from patients with Hashimoto's thyroiditis and normals, it was shown that the patient's T cells suppressed both IgG and thyroid autoantibody production. Irradiation of the patient's PBM inhibited the suppressor effect and a residual helper effect remained. The patient was treated with systemic steroids for exacerbations of arthropathy which caused a fall in lymphocyte count. After 36 months the DNA binding activity spontaneously improved and the lymphocytosis disappeared. It is indicated that T-cell proliferations demonstrating functional activity must be assessed within the context of any underlying non-haematological clinical and laboratory findings.

Adult↗
PubMed1975

Pavlovian counterconditioning: changing the suppressive properties of shock by association with food.

Two experiments are described in which rats received a series of shock and food presentations in a Pavlovian counterconditioning sequence. Subsequently, the capacity of the shock to act as a reinforcer during conditioned emotional response (CER) training was assessed. In the first experiment, following each shock during counterconditioning by a food presentation was found to retard the development of suppression during CER training relative to control conditions in which different groups of rats received either a sequence of explicitly unpaired shock and food presentations, shock presentations alone, or food presentations alone. The second experiment demonstrated that when the magnitude of the food presentations is held constant, the attenuation of the suppressive properties of shock by pairing with food depends on the magnitude of the shock. The results are interpreted as demonstrations of Pavlovian counterconditioning, which, it is suggested, modifies the general aversiveness of a noxious stimulus.

Animals↗
PubMed1975

Suppressive and enhancing effects of footshock on food-reinforced operant responding following septal lesions in rats.

Effect of septal lesions on suppression of an intermittently food-reinforced lever press by contingent and noncontingent footshock was measured. Rats with septal damage maintained higher response rates than did intact animals under both contingent and noncontingent shock. Furthermore, the difference in suppression produced by the contingent and noncontingent conditions was approximately the same for the experimental and control groups. In a second experiment, performance was measured during counter-conditioning in which the correlation between contingent shock and positive reinforcement was varied. Rats with septal lesions responded at higher rates than did controls. When only reinforced responses were punished, this lesion-induced elevation represented an increase above baseline performance without punishment. This finding suggests that the effect of septal damage on appetitive instrumental performance cannot be due solely to a deficit in response inhibition.

Animals↗
PubMedDate not supplied

Goal-directed instrumental action: contingency and incentive learning and their cortical substrates.

Instrumental behaviour is controlled by two systems: a stimulus-response habit mechanism and a goal-directed process that involves two forms of learning. The first is learning about the instrumental contingency between the response and reward, whereas the second consists of the acquisition of incentive value by the reward. Evidence for contingency learning comes from studies of reward devaluation and from demonstrations that instrumental performance is sensitive not only the probability of contiguous reward but also to the probability of unpaired rewards. The process of incentive learning is evident in the acquisition of control over performance by primary motivational states. Preliminary lesion studies of the rat suggest that the prelimbic area of prefrontal cortex plays a role in the contingency learning, whereas the incentive learning for food rewards involves the insular cortex.

Adaptation, Psychological↗
PubMedDate not supplied

Clinical involvement of midwife teachers.

Changes in management and educational structures have severely curtailed opportunities for midwifery teachers to engage in clinical practice outside their commitment to teaching students in clinical areas. The author outlines the past and current positions in this regard, and explains how a team of teachers from her department devised a system which ensures that 20 per cent of their time (or 45 days a year) can be spent in clinical practice.

Female↗