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Biomedical subjects

D M Walker

Publications and source records attributed to D M Walker.

At least 109 records · Page 6Linked to original sources
PubMed1985

The retention of 59Fe and 65Zn by preruminant lambs given milk-substitutes based on either casein or soya-bean-protein isolate.

Eight newborn lambs were given milk-substitutes based on casein (n 4) or a soya-bean-protein isolate (n 4). On the morning before a 10 d collection period, the milk-substitutes were supplemented with 59Fe as ferric chloride and 65Zn as zinc chloride. Faeces and urine were collected daily and determinations of 59Fe and 65Zn were made on these separately. During a second 10 d period the dosing procedure and collection were repeated but the diet of each lamb was reversed. Mean retention of 59Fe in lambs given the casein diet was 0.50 (SE 0.12) and in those given the soya-bean-protein diet 0.06 (SE 0.05). There were large variations among animals but the treatment effect was significant at P less than 0.05. Retention of 65Zn was significantly greater than that of 59Fe for all lambs but the effect of dietary treatment was similar to that for Fe. 65Zn retention values for casein and soya-bean-protein diets were 0.84 (SE 0.06) and 0.52 (SE 0.03) respectively, and the difference was significant at P less than 0.01. There were only very small amounts of 59Fe and 65Zn in urine, representing 0.002-0.003 of the dose.

Animals↗
PubMed1985

Reticuloendothelial Fc receptor function in patients with Sjogren's syndrome.

The functional status of the reticuloendothelial Fc receptor in patients with Sjogren's Syndrome was examined by determining the clearance from the circulation of IgG coated erythrocytes which had been obtained from a single donor. 18 patients with Sjogren's Syndrome were studied and the results compared with those obtained from 18 patients with Rheumatoid Arthritis and 27 healthy controls. Abnormal Fc mediated clearance was observed in 3 individuals with Sjogren's Syndrome and 2 patients with Rheumatoid Arthritis. Extraglandular disease was not associated with abnormal Fc function and there was no correlation between the clearance rates and the immune complex levels, complement levels or rheumatoid factor titre. A comparison of the clearance rates obtained using the patients own red cells with those derived from using a single donor showed that the source of cells used had a significant effect on the clearance rate. Our findings provide no support for the idea that defective Fc function may be of pathogenic significance in the development of more extensive disease in patients with Sjogren's Syndrome.

Adult↗
PubMed1984

Tobacco smoking and denture wearing as local aetiological factors in median rhomboid glossitis.

The importance of tobacco smoking and denture wearing in the aetiology of median rhomboid glossitis (MRG) has been evaluated in 39 patients. Significantly more of the MRG patients (85%) smoked tobacco compared with the corresponding proportion (41%) of the 39 healthy age-and sex-matched control subjects. Their tobacco consumption was also heavier. A significantly greater proportion of the MRG patients wore their dentures continuously compared with the controls. The number of MRG patients who were both tobacco smokers and denture wearers was significantly increased above that of the control group, as was the number who both smoked and wore dentures continuously. Only 1 patient neither smoked nor wore dentures and she was taking an antidepressant (imipramine hydrochloride) with a reported association with oral candidosis. It is suggested that these local factors may play a part in the development of MRG by favouring the local proliferation of Candida albicans on the dorsum of the tongue. Although conservative or surgical treatment may provide relief, management should also include attention to possible predisposing local factors.

Adult↗
PubMed1984

Identification and characterization of the glucose transporter of the blood-brain barrier by cytochalasin B binding and immunological reactivity.

[3H]Cytochalasin B was used as a ligand to identify and characterize the glucose transporter in cerebral microvessels of the rat and the pig. Specific cytochalasin B binding, defined as that fraction of the total binding that is stereospecifically displaced by excess (500 mM) D-glucose, is saturable. Kinetic studies of this specific binding to cerebral microvessel preparations showed a dissociation constant (Kd) of 0.65-0.88 microM and a maximal binding (Bmax) of 60-80 pmol/mg of protein. In comparison, the Bmax of particulate fractions of the cerebral cortex was about one-tenth that of cerebral microvessels. The ability of various hexoses to displace specific cytochalasin B binding to cerebral microvessels in vitro correlated well with the capability of these hexoses to cross the blood-brain barrier in vivo. Irreversible photoaffinity labeling of the glucose transporter of cerebral microvessels with cytochalasin B followed by solubilization and polyacrylamide gel electrophoresis labeled a polypeptide(s) with a molecular weight of about 53,000. Antibodies prepared against the glucose transporter of human erythrocytes also reacted with a polypeptide(s) with a molecular weight of about 53,000 on electrophoresed preparations of cerebral microvessels. These results indicate that cerebral microvessels are richly endowed with a glucose transporter moiety of similar molecular weight and antigenic characteristics as the glucose transporter of human erythrocytes and other mammalian tissues.

Animals↗
PubMed1982

The effect of secretory immunoglobulin A on the in-vitro adherence of the yeast Candida albicans to human oral epithelial cells.

Secretory immunoglobulin A (s-IgA) isolated from human breast milk inhibited the adherence of C. albicans to human oral epithelial cells. This inhibitory effect of s-IgA was maximal at 1 1/2 hours, it was concentration-dependent and was still detectable at subagglutinating antibody concentrations. The inhibitory action of s-IgA was due to its content of specific candidal antibody. Non-specifically bound s-IgA enhanced adherence of the yeast and presumably tends to impair the immune disposal of candida by specific antibody. The reduced adherence of candida pre-treated with 0.4 per cent formol saline at a concentration which kills the organism but leaves its surface antigens intact suggests that, although dead organisms may form an initial loose attachment to the epithelial surface, only viable organisms bind irreversibly. The specific-s-IgA appears to block surface sites on C. albicans involved in epithelial adherence but this action of s-IgA cannot be attributed solely to its agglutinating properties.

Candida albicans↗
PubMed1981

Candidal infections and populations of Candida albicans in mouths of diabetics.

The prevalence of oral candidosis and the frequency of isolation of Candida albicans and its density and distribution have been determined in the mouths of 50 patients with diabetes mellitus and 50 healthy volunteers matched for age, sex, dental status and smoking habits. Three of the diabetic patients were found to have a chronic oral candidosis. According to an imprint culture technique, the oral carrier rate and density of C albicans were both higher in the diabetic group as a whole than in the control subjects. Smoking was associated with an increased prevalence of the yeast in diabetes mellitus. Diabetics wearing dentures had higher candidal density than those without a prosthesis. No differences in candidal status could be detected according to the degree of control of diabetes, mode of treatment, duration of diabetes or the patient's age. Local factors such as smoking and the presence of dentures, particularly when worn continuously, interact with diabetes mellitus in promoting candidal colonisation of the mouth. Attention to these predisposing factors could reduce the incidence of thrush in diabetics.

Adolescent↗