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Biomedical subjects

W B Davidson

Publications and source records attributed to W B Davidson.

At least 19 recordsLinked to original sources
PubMed1995

Personality inferences drawn about abusive mothers.

This study investigated the personality inferences people draw about abusive mothers by having 287 subjects view videotapes of four female targets engaged in social discourse with other adults. Some subjects were primed beforehand to believe that the female targets had physically abused or neglected their child and other subjects viewed the tapes without being primed. Afterward, all subjects rated the targets' personalities using 17 bipolar trait scales and estimating the likelihood of six social behaviors. Analyses compared the ratings of the two types of abuse groups (physical abuse and neglect) with each other and with the unprimed control group. Analysis showed that ratings of one or both of the abuse groups differed from those of the control group on 10 of the 17 trait dimensions and four of six social behaviors. Implications are drawn about the social forces experienced by abusive mothers and the possible role of such forces in therapeutic change.

Adult↗
PubMed1993

Synthesis of [75Se]selenoproteins is greater in selenium-deficient sheep.

Three Se-deficient and three Se-sufficient sheep with mean erythrocyte glutathione peroxidase activities of 30 and 249 mumol NADPH oxidized.min-1.g hemoglobin-1, respectively, were each labeled intraperitoneally with 555 MBq of sodium [75Se]selenite. All animals were killed and necropsied after 7 d. Peak plasma radioactivity occurred from 1 to 3 h post-labeling. Radioactivity in plasma associated with [75Se]selenoproteins was significantly higher in the Se-deficient sheep than in the Se-sufficient sheep 3 and 6 d after isotope administration. SDS-PAGE analysis of plasma followed by autoradiography indicated five selenoproteins, all of which were present in both groups. The molecular weights were 21.0, 23.0, 48.0, 55.5 and > 100 kDa. The protein with a mass of 55.5 kDa accounted for > 40% of the total radioactivity in both groups of sheep. Nine selenoproteins with molecular weights of 15.7, 18.8, 22.9, 26.8, 37.3, 42.4, 56.1, 62.7 and 71.3 kDa were detected in extracts from a range of tissues. Liver, kidney, heart and pituitary retained more radioactivity than the other tissues examined and the total amount of protein-associated 75Se in the liver, kidney and pituitary of Se-deficient sheep was significantly greater than that in Se-sufficient controls.

Animals↗
PubMed1992

Development and application of an alpha-face-specific radioimmunoassay for vitamin B12.

The first development of an alpha-face-specific radioimmunoassay for vitamin B12 is described. Sheep, fed a cobalt-deficient diet, and immunized with a conjugate between Co-beta carboxypropyl cobalamin and keyhole limpet hemocyanin, were used to produce antisera. The antisera crossreacted with Co-beta derivatives of vitamin B12, but did not crossreact with the alpha-face vitamin B12 analog cobinamide. The antisera were used to develop a sensitive and reproducible radioimmunoassay that was free from contamination with the nonspecific vitamin B12 binding protein, R-protein. Both the radioimmunoassay and measurements of plasma concentrations of methylmalonic acid were applied to the diagnosis of cobalt/vitamin B12 deficiency in sheep. The assay correlated well with a commercially available radioassay and did not falsely detect normal vitamin B12 concentration in plasma samples containing elevated concentrations of methylmalonic acid.

Animals↗
PubMed1990

The stability of glutathione peroxidase activity in plasma from cattle, pigs and sheep on storage in the presence and absence of glutathione.

Ovine, bovine and porcine plasma glutathione peroxidase (GSH-Px) activity decreased on storage at both 4 degrees C and 20 degrees C. The ovine and bovine enzymes were significantly less stable than the porcine enzyme. The addition of GSH to a final concentration of 2 mmol/L to plasma samples at the commencement of storage retarded the loss of both ovine and bovine plasma GSH-Px activity. The ovine enzyme was unique in that after inactivation by storage at 4 degrees C, incubation with GSH restored the enzyme activity. It is recommended that plasma GSH-Px should be assayed fresh, or otherwise stored at -20 degrees C.

Animals↗
PubMed1988

75Selenium-labeled sheep plasma: the time course of changes in 75selenium distribution.

Sheep fed rations containing 0.1 ppm selenium were labeled by intravenous injection of radioactive sodium selenite or selenocystine. Gel filtration of serially collected plasma samples indicated that, with time, there was a transition from mercaptan sensitive to high mol wt mercaptan and protein solubilizer resistant selenoproteins. Radiolabeled plasma samples collected from selenite and selenocystine labeled sheep were dialyzed against buffer containing 2-mercaptoethanol or protein solubilizer. No difference in the stability between selenite- and selenocystine-labeled plasma could be detected.

Animals↗
PubMed1988

Emotionality as a moderator of cognitive style on the Matching Familiar Figures Test in adults.

This study examined whether an emotional temperament moderated scores on the Matching Familiar Figures Test (MFFT) in adults. It was predicted that people who were high in fear would score in the impulsive and reflective quadrants of the MFFT, and those who were low in fear would score in the other two quadrants of the MFFT. Eighty-five college students completed the EASI Temperament Survey and later the MFFT. The results supported the prediction. Relative to others, subjects who scored in the impulsive and reflective quadrants of the MFFT also scored significantly higher on the Fear subscale of the EASI Temperament Survey. Implications for the role of fear in interpreting scores on the MFFT were drawn.

Adolescent↗
PubMed1987

An electrophoretic analysis of sheep plasma protein labeled with Na2 75SeO3 in vivo.

Following an intravenous injection of 75Se, sodium selenite plasma samples were analyzed by two-dimensional electrophoresis. 75Se was detected by indirect autoradiography. From 0.5 to 53 hr postinjection of 75Se, 21 75Se peptides were detected. Both the isoelectric points and molecular weights of these peptides are reported. The molecular weights of the peptides ranged from 20,000 to 70,000 daltons.

Animals↗
PubMed1987

Experimental myopathy in vitamin E- and selenium-depleted calves with and without added dietary polyunsaturated fatty acids as a model for nutritional degenerative myopathy in ruminant cattle.

Fourteen calves, 14 weeks old, fed a low vitamin E and selenium diet based on sodium hydroxide-treated, selenium-deficient barley showed a rapid decline in plasma alpha-tocopherol, a gradual decline in erythrocyte glutathione peroxidase (GSHPX) activity, elevated plasma creatine kinase (CK) activity, teeth grinding and (in three cases) electrocardiographic changes, but no clinical abnormalities after 127 to 137 days. Necropsy of six depleted calves at that stage revealed pale muscles in two animals and mild histopathological lesions of skeletal myopathy in all six calves. Ten control calves were fed a similar diet supplemented with alpha-tocopherol and selenium. Plasma alpha-tocopherol and erythrocyte GSHPX activity remained high in these calves and no clinical abnormalities or evidence of myodegeneration were observed. When protected linseed oil was fed as a source of polyunsaturated fatty acids to the remaining eight depleted calves, rapid elevations in plasma CK activity and linolenic acid associated with a variety of cardiopulmonary and locomotory signs, electrocardiographic changes and myoglobinuria occurred within six to 11 days. Necropsy revealed widespread severe skeletal myodegeneration (eight calves) and myocardial lesions (five calves) with preferential involvement of the left ventricular myocardium. Clinical signs and pathological changes were similar to those reported in field outbreaks of nutritional degenerative myopathy in ruminant cattle and establish the experimental regime as the first successful model for reproduction of this disease.

Animals↗
PubMed1986

Characterisation of an antiserum and development of an ELISA for glutathione peroxidase.

Sheep red blood cells were fractionated by ion exchange and gel filtration chromatography to yield glutathione peroxidase approximately 99% pure. An antiserum against glutathione peroxidase was raised in the rabbit. The antiserum has been shown to cross-react with both bovine and human glutathione peroxidase by double diffusion. An enzyme linked immunosorbent assay has been developed for glutathione peroxidase which detected 6.15 X 10(-5) IU of the enzyme. The antiserum has also been shown to be effective in the detection of glutathione peroxidase immobolised on strips of nitrocellulose, subsequent to sodium dodecyl sulphate polyacrylamide gel electrophoresis, by second antibody conjugate. Avidin-biotin was also used to detect nitrocellulose immobolised enzyme. These techniques provide an alternative highly sensitive and specific means of assaying glutathione peroxidase which is not dependent on the lability of enzymatic activity nor the chemical specificity of the assay.

Animals↗
PubMed1984

Personality correlates of the Matching Familiar Figures Test in adults.

The Matching Familiar Figures Test (MFFT) measures a dimension of cognitive style known as reflection-impulsivity. Interpretations of the MFFT sometimes supplement its cognitive implications with one of two personality models, impulsivity and/or ego-resilience. Both models have received some research support from studies that used preadolescent subjects. The applicability of these two personality models to adults was evaluated in this research. In three studies on college students, one personality characteristic within the ego-resilience position, independent-oriented achievement, was found to differentiate between impulsive and reflective scorers on the MFFT. No support was found for the impulsivity position. Implications were drawn for the influence of personality on the MFFT.

Journal Article↗
PubMed1979

In vitro metabolism of selenite in sheep blood: factors controlling the distribution of selenium and the labelling of plasma protein.

Some factors controlling the distribution of Na275SeO3 in sheep blood were studied in vitro. After centrifuging Na275SeO3-incubated blood most of the radioactivity was found in the plasma. The labelling of plasma protein by 75Se was dependent on the presence of erythrocytes. The degree of labelling of plasma protein increased with erythrocyte concentration. When phosphate-buffered saline-washed erythrocytes were suspended in phosphate-buffered saline and incubated with Na275SeO3 the majority of the 75Se was detected in the erythrocytes. On incubating these labelled erythrocytes with unlabelled plasma there was a transfer of radioactivity to the plasma. The calculated activation energy for the labelling of plasma was 107.52 kJ/mol. Albumin was shown not to be a principal acceptor of 75Se from the erythrocytes by ammonium sulphate precipitation of radioactive plasma. Addition of Na2SeO3 to the labelled blood resulted in the transfer of 75Se from plasma to the erythrocytes. Radioactive plasma incubated at 37 degrees C was thermolabile with respect to its 75Se content whereas in whole blood the degree of 75Se binding to plasma protein did not vary suggesting that a recycling of selenium was occurring in blood. From the results presented an in vitro model of selenium metabolism in blood is postulated.

Animals↗
PubMed1978

Influence of reflection-impulsivity and cognitive style on time estimation under different ambient conditions.

120 college students estimated seven different durations of a light by the method of reproduction. Each duration reproduction was performed while either counting fast auditory clicks, slow clicks, or with no clicks. The subjects had previously been assessed for cognitive style with the Group Embedded Figures test and for reflection-impulsively with the impulsivity scale from the Personality Research Form. Multivariate analyses of variance indicated that the rapid-tempo ambient conditions had a greater effect on estimation of duration than did either the slow tempo or control condition. There were significant differences in time estimation between reflectives and impulsives for estimations of 10, 30, and 50 sec. No interactions were observed for reflection-impulsivity by ambient conditions. Although cognitive style did not interact with ambient conditions as was predicted, it did interact with sex for three durations, 10, 20, and 30 sec. It was concluded that impulsive students tend to underestimate the brief times more than do reflective students but are not affected differently by the ambient circumstances in which the estimation is made. Cognitive style, apparently, does not have a profound influence on estimation of brief durations. However, sex and cognitive style in interaction do affect these estimations, this requires further research.

Acoustic Stimulation↗
PubMed1977

The role of defective interfering particles in persistent infection of Vero cells by measles virus.

Persistent infections by measles virus were rapidly established in the majority of Vero cells when monolayers were infected with virus stocks that had been passed three to five times from an undiluted inoculum. These virus stocks had low infectivity titres but normal haemagglutinin titres and were able to cause interference. The ability of such virus stocks to establish persistent infections seems to be due to the presence of defective interfering particles rather than of virus mutants. Measles virus released from a persistently infected Vero cell line at the 93rd passage had properties similar to the undiluted passage virus that generated persistent infections.

Animals↗
PubMedDate not supplied

The incorporation of Na2 75SeO3 into sheep erythrocytes.

Injection of Na2 75SeO3 into untreated, phlebotomized, and phenylhydrazine treated sheet has shown that the rate of 75SeO3-incorporation into erythrocytes is dependent on the degree of stimulation. Analysis of labeled erythrocytes by gel filtration and two-dimensional electrophoresis has indicated that the transient labeling of a hemoglobin-like peptide is the only protein labeled in addition to glutathione peroxidase.

Animals↗