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Biomedical subjects

R Mitchell

Publications and source records attributed to R Mitchell.

At least 361 records · Page 20Linked to original sources
PubMed1983

The accuracy of the plain abdominal radiograph in assessing colonic faecal contamination.

A prospective study of 333 out-patients assessed the accuracy of determining colonic cleansing from the plain abdominal radiograph. The results indicate that the amount of colon contaminated with faeces was significantly underestimated and the difference in efficacy between the best and worst preparation regimens could not be detected from the plain film. Nevertheless, plain films have been used in comparative studies of preparation regimens for barium enema. It is suggested that results so obtained are misleading and that comparisons are best made on barium films alone.

Barium Sulfate↗
PubMed1983

Apparent reversal frequencies in squares and trapezia: the effect of invariant and variant information.

Three studies of apparent reversals (ARs) in rotating rectangular and trapezoid arrays are reported, together with a mathematical analysis. Study 1 explores the effect of different degrees of outline suppression on the frequency and distribution of ARs in squares and trapezia. Study 2 examines how modifications in both types of array reduce AR frequency, demonstrates a manipulation whereby ARs in rotating squares are eliminated, and suggests that ARs in squares and trapezia are of different origins. In the mathematical analysis, an invariant characteristic of the transformations of rotating rectangles is reported, and from this a numerical index is developed that expresses the extent to which a rotating trapezium may appear to pause just before each point of oscillation. In study 3 it is shown that this measure is a better predictor of AR frequencies than the heuristic proposed by Braunstein.

Adult↗
PubMed1983

The effect of alcohol on the visual and ocular motor systems.

Alcohol is generally considered to be a central nervous system (CNS) depressant. This effect is progressive from higher cortical centres through to fundamental body functions. The effect of alcohol ingestion on the visual and ocular motor systems of ten healthy subjects was the basis of this study. Significant changes in the following resulted from the ingestion of 0.375 g/kg of 10% ethanol alcohol: prism measurements of deviations for near and distance, ocular movements, convergence near point, and visual acuity at six metres. No significant change was observed following testing of stereopsis or near visual acuity.

Adult↗
PubMed1983

Monoclonal anti-B produced by the immunization of mice with soluble salivary glycoproteins.

IgM and IgG mouse monoclonal antibodies with specificity for the blood group B determinant have been produced by immunization of mice with a partially purified salivary glycoprotein. These antibodies have been characterized and one of the IgM antibodies showed potential as a grouping reagent. The ready availability of these salivary blood group substances offers the potential to produce a wide range of related monoclonal antibodies.

ABO Blood-Group System↗
PubMed1983

Endogenous GABA receptor ligands in hypophysial portal blood.

The concentrations of endogenous gamma-aminobutyric acid (GABA) receptor ligands were measured in hypophysial portal plasma by a sensitive and specific radioreceptor assay. Portal plasma contained higher concentrations of GABA receptor ligands than peripheral controls, although this increase was not due to authentic GABA but an unknown low-affinity ligand. Evidence is presented to support the hypothesis that the dipeptide homocarnosine may represent at least a part of this unknown. Electrical stimulation of median eminence evoked a massive (7.8-fold) increase in the rate of release of GABA (but not the low-affinity component) into portal blood. These results suggest that GABA and possibly other low-affinity ligands such as homocarnosine could serve as factors involved in the central control of anterior pituitary function.

4-Aminobutyrate Transaminase↗
PubMed1982

Mouse monoclonal anti-N. I. Production and serological characterization.

Two examples of mouse monoclonal anti-N are described. The antibodies were derived from mice immunized with sialoglycoprotein extracts of group O MM ss erythrocyte membranes and the probable stimulus for immunization was glycophorin B associated N-antigen. Both antibodies reacted as direct agglutinins but appeared to recognize different epitopes with one having a greater dependence on sialic acid. The antibodies could prove to be valuable alternatives to those reagents used currently for N-blood grouping.

Animals↗
PubMed1982

Mouse monoclonal anti-N. II. Physicochemical characterization and assessment for routine blood grouping.

The precise physicochemical conditions under which two examples of mouse monoclonal anti-N can be used as blood grouping reagents have been defined. The antibodies were shown to belong to the IgG1 and IgG2b subclasses respectively and both reacted within discrete ranges of temperature and pH with optimal reactions occurring at 20 degrees C or less and pH 8.5. Under these conditions and at concentrations of 2-3 micrograms/ml, the antibodies were used, in parallel with conventional polyclonal antisera, to type a series of random blood donors. The results obtained with one of the monoclonal antibodies and the polyclonal reagents were in perfect agreement and the monoclonal antibody was judged to have considerable potential as an N-grouping reagent.

Animals↗
PubMed1982

Contribution of particle-bound bacteria to total microheterotrophic activity in five ponds and two marshes.

We examined the abundance and heterotrophic uptake of bacteria attached to particulate matter suspended in five coastal ponds and two marshes near Woods Hole, Mass. Although the number of particle-bound bacteria was low (<10%), these bacteria incorporated a large proportion (>40%) of [C]glucose and [C]glutamate in selected aquatic systems. The uptake per cell was significantly higher for epibacteria than for unattached bacteria in all systems. Two groups of the aquatic environments sampled were statistically different in the contribution made by particle-bound bacteria to total bacterial abundance and to total assimilation of [C]glucose and [C]glutamate. Particle-bound bacteria were more important in those waters with a high particle concentration and not flushed regularly by tides than in waters with a low particle concentration and flushed regularly.

Journal Article↗