Biomedical subjects

J D Nunn

Publications and source records attributed to J D Nunn.

5 recordsLinked to original sources

PubMed1997

Selective processing of concern-related information in depression.

OBJECTIVES: The major question examined in this paper is whether selective attentional and interpretative processing of emotional information occurs in depression, and if so, whether it depends on a close match between the material used and current concerns. DESIGN: Twenty-four depressed patients and the same number of matched controls were tested using two selective processing tasks (described below), and their performance related to self-reported sociotropic and autonomy-related concerns. METHODS: Colour-naming interference and interpretation of ambiguous situations were assessed using material judged relevant to each of the Sociotropy-autonomy Scales. RESULTS: Depression was associated with a general interference effect for all negative concern words, and more negative interpretations of ambiguous situations, while controls showed a converse bias in favour of all positive interpretations. There was no convincing evidence that this negative processing bias was proportional to the match between material and self-reported sociotropic or autonomous concerns. CONCLUSIONS: Depressed patients showed evidence of cognitive biases favouring all negative self-related information, on both attentional and interpretative tasks. We suggest that such effects in depression may occur only under conditions allowing the elaborative processing of negative material related to oneself.

Adjustment Disorders↗

PubMed1987

Dendritic cells from human tissues express receptors for the immunoregulatory vitamin D3 metabolite, dihydroxycholecalciferol.

Dendritic cells have been isolated from human tonsillar tissue and shown to act as accessory cells in a mitogenic response. The dendritic cells will induced receptors for the active metabolite of vitamin D3, 1,25(OH)2D3, in the responder E+ T cells. The dendritic cells themselves constitutively express receptors for the metabolite, and this distinguishes them from other non-T cells in lymphomedullary tissue. Expression of the 1,25(OH)2D3 receptor may be a dendritic cell property that facilitates their accessory cell role within the tissue microenvironment.

Calcitriol↗

PubMed1986

Regulation of human tonsillar T-cell proliferation by the active metabolite of vitamin D3.

We have examined the effects of 1,25(OH)2D3 on T-cell populations isolated by buoyant density and E rosetting from human tonsils. Cell proliferation was assessed by measuring the incorporation of 125iododeoxyuridine; interleukin-2 (IL-2) production was measured using an IL-2-dependent cell line, and the number of 1,25(OH)2D3 receptors was measured by whole-cell nuclear association assay. At a concentration of 10(-7) M, 1,25(OH)2D3 inhibited mitogen-induced T-cell proliferation in all E+ T-cell populations. This effect was more pronounced in the cells from the intermediate and high density layers and was reflected both in cell proliferative responses and in relative IL-2 synthesis. By adding the 1,25(OH)2D3 during the course of the mitogen assay, we demonstrated that activation of the T cell precedes the 1,25(OH)2D3-mediated inhibition. Cells that had been preincubated with mitogen in the presence of the 1,25(OH)2D3 were refractory to further stimulation by mitogens. Receptors for 1,25(OH)2D3 could not be detected in unstimulated T cells. However, activation led to the expression of high-affinity receptors for 1,25(OH)2D3. Co-incubation of the cells with mitogen and 1,25(OH)2D3 increased the number of receptors compared with mitogen alone. The effects provide further evidence for the hypothesis that 1,25(OH)2D3 is an important potential modulator of the immune system through its action on T cells. Taking our observations in conjunction with the known capacity of monocytes to hydroxylate the precursor metabolite (and thus synthesize the active form of cholecalciferol), the results support the suggestion that 1,25(OH)2D3 plays a role as a local mediator of mononuclear phagocyte-T cell interaction in human lymphomedullary tissues.

Calcitriol↗

PubMed1985

Differential expression of class II MHC antigens on cells derived from human tissue.

Human lymphomedullary tissue cells, separated on the basis of density, Fc and E receptors, show characteristic and consistent differences in their expression of class II MHC antigens. A low density, FcR-ve cell type displays high expression of HLA-DR and acts as the most efficient accessory cell in the induction of a Con A driven proliferative response. Exposure of cells to Con A inhibits subsequent binding of anti-HLA-DR antibodies. Addition of -methyl-D-mannoside reverses both the proliferative response to Con A and returns binding of anti-class II MHC antibodies to normal levels. This experimental system can be used to study: the nature of the association between cell bound molecules and class II MHC products, both spatially and functionally; and the relative functional importance of these products in antigen presentation.

Antibodies, Monoclonal↗

PubMed1984

Selective memory effects in agoraphobic patients.

Two experiments tested the view that agoraphobic patients would show superior recall for phobic-related material relative to neutral material. In Expt 1, subjects were required to recall a series of five passages; three contained potentially phobic information and two contained neutral information. The results showed that phobic patients recalled more propositions from the phobic passages than did controls. In Expt 2, subjects completed four study-test trials with a list of 20 words: 10 phobic words and 10 neutral words. The results showed that the patients recalled more phobic than neutral words while the reverse was the case for controls. The results are discussed in terms of the cognitive organization of phobic patients and are related to Beck & Rush's proposal that phobics have a cognitive organization of situations labelled as dangerous. The possible sources of these selective memory effects are also considered.

Adult↗