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Biomedical subjects

R Baldy

Publications and source records attributed to R Baldy.

6 recordsLinked to original sources
PubMed1995

Representation and performance: reproduction of form and quality of movement in dance by eight- and 11-year-old novices.

This study examined the effects of age on the cognitive representations in modelling. A total of 48 eight- and 11-year-olds were asked to watch a dancer performing a ballet sequence of three steps in order to reproduce it. They were able to see the film as many times as they wanted. All subjects were novices to dance. Both quantitative (number of observations required to learn the sequence, number of steps executed) and qualitative (form and quality of the performance) factors were assessed. The results indicated an effect of age on the number of requested observations and on the number of subjects able to perform the entire movement series. The mean form scores did not differ significantly between the two groups, but the mean quality score was higher for the 11-year-olds. We also noted a great heterogeneity in the performances. The results are discussed in terms of the role of cognitive and motor factors in observational learning by age and of the possibilities that cognitive representations offer for coding the different properties of movement.

Age Factors↗
PubMed1987

Left cerebral hemisphere hypodensity in discordant schizophrenic twins. A controlled study.

Eleven identical (monozygotic) twin pairs discordant for schizophrenia and 18 unselected control monozygotic twin pairs received a computed tomographic scan. Brain absorption density was determined on quadrants at five slice levels using a fully automatic program that eliminated cerebrospinal fluid spaces from analysis. There was no difference in brain density among schizophrenics, co-twins, and controls. There was a significant difference in right vs left hemisphere asymmetry of density across diagnostic groups. Overall, the left hemisphere was less dense than the right in the schizophrenics, while the reverse was found for the co-twins and controls. These results support the hypothesis of left hemisphere dysfunction in schizophrenia and suggest that it is an environmentally acquired, rather than genetic trait.

Absorptiometry, Photon↗
PubMed1983

Quantitative computed tomography in elderly depressed patients.

An index of brain tissue density was obtained from the CT scans of 37 elderly depressed patients by measuring Hounsfield Units (HU) in 12 predefined brain areas. Comparisons were made with 23 patients suffering from senile dementia and 36 healthy controls. As a group the depressed patients resembled the dements more than the controls, although analysis of variance indicated differences between all three groups, controls showing the highest HU values and dements the lowest. In the depressed patients ventricular dilatation, which had already been shown to predict increased mortality, was also associated with lower HU levels. The significance of these and other findings is discussed.

Affective Disorders, Psychotic↗
PubMed1981

Quantitative computed tomography in senile dementia.

Mean computed tomography (CT) numbers or Hounsfield units (HU) were computed in 15 regions of the brain in routine CT scans of 25 patients with senile dementia and 29 normal community volunteer controls. Mean HU values were significantly lower bilaterally in the medial temporal lobe, anterior frontal lobe, and head of the caudate in the group of patients with senile dementia. There was no correlation between mean HU values and age, and covariate analysis showed that the differences between patients and controls were not attributable to the size of the ventricles. These data suggest that the determination of mean HU values from selected technically suitable regions of CT scans of the brain may have clinical applications of the diagnosis of senile dementia and provide a reliable means of monitoring changes in brain tissue density during the course of senile dementia.

Aged↗
PubMed1970

A monophenol oxidase activity in extracts of sorghum.

A p-hydroxycinnamic acid oxidase activity was present in enzyme preparations from first internodes of Sorghum vulgare variety Wheatland milo when incubated in phosphate buffer at pH 7.5. This preparation had no classical polyphenolase activity but had both peroxidase and catalase activities. Since horseradish preparations catalyzed the same reaction, the oxidation probably is another example of a peroxidase-oxidase reaction. A second substrate was p-hydroxyphenylpyruvic acid. Ferulic acid was slightly active at low concentrations and inhibitory at higher ones. Diphenols such as caffeic and chlorogenic acids were inactive and inhibitory to p-hydroxycinnamic acid oxidation. A variety of monophenols such as tyrosine and cinnamic acid were inactive. An active substrate must have a free monophenolic group and para to this a C(3) side chain with a double bond and probably a free terminal acid group. A sulfhydryl reducing agent at the 5 millimolar level such as mercaptoethanol, reduced glutathione, or dithiothreitol was obligatory. Products were varied and were found in both the ethyl acetate-soluble and insoluble fractions after acidification of the incubation mixtures. With internode extracts, about 1 micromole of O(2) was consumed per micromole of p-hydroxycinnamic acid that disappeared in the presence of mercaptoethanol. Tetrahydrafolic acid plus mercaptoethanol were required for a second step oxidation or a parallel reaction; about 2 micromoles of O(2) were consumed per micromole of p-hydroxycinnamic acid that disappeared. Potassium cyanide, diethyldithiocarbamate, ascorbic acid, and ethylenediaminetetraacetate were inhibitory. A similar mercaptoethanol-dependent monophenol oxidase was present in preparations from green shoots that also contained a classical polyphenolase activity. The activity was present in both soluble and particulate (500 to 100,000 gravity) fractions of internodes. Preliminary studies were made of enzyme complexes in the particulate fractions capable of converting phenylalanine and tyrosine to the level of ferulic acid when the above p-hydroxycinnamic acid oxidase was blocked with ascorbic acid. The ratelimiting step was the hydroxylation of p-hydroxycinnamic acid.

Journal Article↗