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Biomedical subjects

D Mumford

Publications and source records attributed to D Mumford.

17 recordsLinked to original sources
PubMed1998

Development and evaluation of an inner city mental health team.

The objective of this study was to examine the development and activity of a Community Mental Health Team, originally targeted to meet the needs of African Caribbean, Asian and homeless populations in an inner city area. The study was based on all (n = 1046) client referrals to the Bristol Inner City Community Mental Health Team between 1987 and 1994. Additional qualitative interviews were held with general practitioners (GPs) from each of the nine practices in the area. The setting was the inner city area of Bristol, an area with a population of around 35,000 27% of whom are from ethnic minority communities. This is an area shown in previous research to have a high level of mental health problems. Trends in referral rates, demographic characteristics and seriousness of psychiatric illness amongst those referred to the Inner City Mental Health Team were the main outcome measures used. In the years studied there were significant increases in the number and proportion of overall referrals from GPs and psychiatrists and decreases in referrals from other agencies. In particular, there were reductions in the referral both of clients from the originally identified target groups and of patients with serious mental illness. GPs tended to refer a greater proportion of patients with less serious mental illness. The results of the study showed that a team originally developed to meet the needs of the homeless and those from ethnic minorities has, with the removal of special project funding, shifted its focus away from the client groups for whom it was originally developed to those with less serious mental health problems. These changes are partially attributable both to changes in the remit of the team, making it more acceptable to GPs, and to a growing acceptance of community-based mental health services among GPs and their patients. Changes in the geographic catchment area served by the team has also played a role in the observed trends. Commissioners of mental health services need to bear in mind the needs of high-risk groups when making contracts. It may be that in order to meet effectively the needs of inner city populations with a high prevalence of mental health problems, there is a need for specialist teams with a specific remit.

Adult↗
PubMed1998

The role of the primary visual cortex in higher level vision.

In the classical feed-forward, modular view of visual processing, the primary visual cortex (area V1) is a module that serves to extract local features such as edges and bars. Representation and recognition of objects are thought to be functions of higher extrastriate cortical areas. This paper presents neurophysiological data that show the later part of V1 neurons' responses reflecting higher order perceptual computations related to Ullman's (Cognition 1984; 18:97-159) visual routines and Marr's (Vision NJ: Freeman 1982) full primal sketch, 2 1/2D sketch and 3D model. Based on theoretical reasoning and the experimental evidence, we propose a possible reinterpretation of the functional role of V1. In this framework, because of V1 neurons' precise encoding of orientation and spatial information, higher level perceptual computations and representations that involve high resolution details, fine geometry and spatial precision would necessarily involve V1 and be reflected in the later part of its neurons' activities.

Action Potentials↗
PubMed1992

On the computational architecture of the neocortex. II. The role of cortico-cortical loops.

This paper is a sequel to an earlier paper which proposed an active role for the thalamus, integrating multiple hypotheses formed in the cortex via the thalamo-cortical loop. In this paper, I put forward a hypothesis on the role of the reciprocal, topographic pathways between two cortical areas, one often a 'higher' area dealing with more abstract information about the world, the other 'lower', dealing with more concrete data. The higher area attempts to fit its abstractions to the data it receives from lower areas by sending back to them from its deep pyramidal cells a template reconstruction best fitting the lower level view. The lower area attempts to reconcile the reconstruction of its view that it receives from higher areas with what it knows, sending back from its superficial pyramidal cells the features in its data which are not predicted by the higher area. The whole calculation is done with all areas working simultaneously, but with order imposed by synchronous activity in the various top-down, bottom-up loops. Evidence for this theory is reviewed and experimental tests are proposed. A third part of this paper will deal with extensions of these ideas to the frontal lobe.

Animals↗
PubMed1991

On the computational architecture of the neocortex. I. The role of the thalamo-cortical loop.

This paper proposes that each area of the cortex carries on its calculations with the active participation of a nucleus in the thalamus with which it is reciprocally and topographically connected. Each cortical area is responsible for maintaining and updating the organism's knowledge of a specific aspect of the world, ranging from low level raw data to high level abstract representations, and involving interpreting stimuli and generating actions. In doing this, it will draw on multiple sources of expertise, learned from experience, creating multiple, often conflicting, hypotheses which are integrated by the action of the thalamic neurons and then sent back to the standard input layer of the cortex. Thus this nucleus plays the role of an 'active blackboard' on which the current best reconstruction of some aspect of the world is always displayed. Evidence for this theory is reviewed and experimental tests are proposed. A sequel to this paper will discuss the cortico-cortical loops and propose quite different computational roles for them.

Animals↗
PubMed1987

Discriminating figure from ground: the role of edge detection and region growing.

Three general classes of algorithms have been proposed for figure/ground segregation. One class attempts to delineate figures by searching for edges, whereas another class attempts to grow homogeneous regions; the third class consists of hybrid algorithms, which combine both procedures in various ways. The experiment reported here demonstrated that humans use a hybrid algorithm that makes use of both kinds of processes simultaneously and interactively. This conclusion follows from the patterns of response times observed when humans tried to recognize degraded polygons. By blurring the edges, the edge-detection process was selectively impaired, and by imposing noise over the figure and background, the region-growing process was selectively impaired. By varying the amounts of both sorts of degradation independently, the interaction between the two processes was observed.

Adult↗
PubMed1986

Left atrial myxoma in the elderly. Report of four patients over the age of 70 and review of the literature.

Myxoma of the atrium presents distinctive clinical profile, yet precise diagnosis of the tumor on the basis of clinical findings is often not made in the elderly patient as the symptoms are often attributed to "generalized arteriosclerosis of the elderly." The authors report the clinical findings in four elderly patients with left atrial myxoma in whom the diagnosis had not been clinically suspected before echocardiographic evaluation.

Aged↗
PubMed1979

Apparent quinidine-induced digoxin toxicity after withdrawal of pentobarbital: a case of sequential drug interactions.

Accelerated quinidine metabolism was observed in a 94-year-old woman also receiving daily doses of digoxin and pentobarbital sodium. Discontinuation of pentobarbital produced a sharp increase in serum digoxin concentrations coupled with symptoms highly suggestive of digoxin toxicity. Associated with these findings was 3.8-fold increase in quinidine half-life. These data seemed consistent with an interaction between quinidine and digoxin that was precipitated by pentobarbital withdrawal.

Aged↗
PubMed1976

Lactate and malate dehydrogenase and alpha-esterases in oligospermia.

Lactate dehydrogenase (LDH), malate dehydrogenase, and alpha-esterase were studied electrophoretically in a total of 99 semen samples obtained from normal, vasectomized, oligospermic, and infertile males. The enzymatic patterns were compared with total sperm count and percentage sperm motility. Lactate dehydrogenase X was absent in semen samples from oligospermic as well as vasectomized males. An extra LDH band (between the second and third LDH bands) was detectable in samples which had a low sperm count but higher motility (80 to 90%). This extra band was absent in samples with higher sperm count regardless of the level of percentage motility, suggesting that the extra band possibly may be related to motility factors of low sperm count but not normal sperm count. The fastest moving alpha-esterase bands were absent in samples from oligospermic or vasectomized males. These bands were also absent in samples from infertile patients having a very low sperm count. It is not clear whether the fast-moving esterase bands are related to sperm count or possible differences in hormonal levels of individuals with low or zero sperm count samples. The patterns of malate dehydrogenase did not differ in individuals with zero, low, or normal sperm count.

Electrophoresis, Starch Gel↗
PubMed1975

An EBV-genome-negative cell line established from an American Burkitt lymphoma; receptor characteristics. EBV infectibility and permanent conversion into EBV-positive sublines by in vitro infection.

An in vitro line was derived from an American Burkitt lymphoma, designated Ra No. 1, which produced malignant tumors when inoculated into thymus-deficient nude mice. The cells have B-lymphocyte characteristics, with surface-associated mu and kappa chains and Epstein-Barr virus (EBV) receptors, and can be readily infected with EBV in vitro. B95-8 virus induced EBV-determined nuclear antigen (EBNA) but not early antigen (EA) in Ra No. 1 cells, whereas P3HR-1 virus induced both EBNA and EA, but the EA level was much lower than in the prototype Raji strain, EBNA and EA levels were comparable in Ra No. 1 and in the previously established, EBV-infection-sensitive BJA-B lymphoma. The two lines differed, however, because BJA-B could be converted into a permanent EBV-carrying line by the B95-8 but not by the P3HR-1 virus strain, whereas Ra No. 1 could be converted by the P3HR-1 virus. This demonstrates that different B-lymphocyte-derived lymphoma lines can vary with regard to the restrictive control they can exert on the same virus strain. Furthermore, virus strains vary in their sensitivity to the restrictions of the same host cell. Permanent EBV conversion of the Ra No. 1 cell did not appear to change the cellular controls, as judged by the unchanged sensitivity of the cell to viral antigen (EA, viral capsid antigen) induction by P3HR-1 virus superinfection.

Animals↗