PubMed Health⌕ Search

Biomedical subjects

S Petry

Publications and source records attributed to S Petry.

12 recordsLinked to original sources
PubMed1992

A spacer-modified disaccharide as a photoaffinity reagent for the acceptor-binding area of bovine (1----4)-beta-D-galactosyltransferase: comparison of its acceptor properties with those of other 2-acetamido-2-deoxy-beta-D-glucopyranosides.

The spacer-modified disaccharide 1,10-di-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-2-azi-1,10- decanediol (10) that mimics the biantennary core heptasaccharide of N-glycoproteins has been synthesised. Compound 10 is an excellent acceptor in galactosyltransferase-catalysed galactosylation by UDP-galactose, is superior (7-8-fold) to analogues that have only one GlcNAc unit, and is an efficient photoaffinity reagent for galactosyltransferase. In the presence of UDP-Gal, no photoaffinity labelling by 10 takes place, which agrees with the mechanism of galactosyltransferase action.

Animals↗
PubMed1992

Spacer-modified trisaccharide glycosides that mimic the biantennary Asn-linked oligosaccharide acceptor of (1----4)-beta-D-galactosyltransferase and can be used as competitive inhibitors and for irreversible deactivation.

The biantennary spacer-modified trisaccharide glycoside methyl 3,6-di-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyloxyethyl)-alpha -D- mannopyranoside (5) was synthesised and used together with several 2-acylamino-2-deoxy-D-glucose derivatives in competition experiments with beta-D-galactosyltransferase. Compound 5 was an acceptor substrate (KM 0.18 mM) comparable to the biantennary core heptasaccharide of glycoproteins (KM 0.13 mM). Replacing the N-acetyl group by other N-acyl groups did not alter the kinetic parameters significantly. When the N-acyl group was iodoacetyl, the compound was an irreversible inhibitor.

Asparagine↗
PubMed1991

Evidence for independent processing of subjective contour brightness and sharpness.

Subjective contours have been of considerable interest because of their importance to theories and physiological models of form perception. In particular, they have recently been characterized as the result of magnocellular cortical processing. There is, however, a paucity of parametric data relating to basic psychophysical parameters in this field. Two experiments are reported in which the roles of subjective contour size, retinal eccentricity, and flicker rate in subjective contour salience were investigated. Eleven observers estimated subjective contour magnitude using an Ehrenstein configuration. Configurations ranging in size from 0.25 to 3 deg were presented to three retinal loci (fovea, 2 deg, and 4 deg) at flicker rates ranging from 5 to 15 Hz. Subjective contour brightness and distinctness were measured separately. Brightness was greatest at a subjective contour size of about 1.25 deg, at flicker rates of 5-7 Hz, and at 3 deg peripheral for all flicker rates and all but the smallest stimulus sizes. Distinctness decreased with eccentricity and flicker, but remained high at small diameters (thus implicating spatially sensitive mechanisms). Taken together, the results support a magnocellular processing of subjective contours with respect to brightness, but also suggest that there is a parvocellular contribution to subjective contour sharpness.

Adult↗
PubMed1990

Comparison of four methods for testing high-level aminoglycoside resistance in enterococci.

In a prospective study the prevalence of high-level aminoglycoside resistance (MIC greater than or equal to 2,000 micrograms/ml) among 62 clinically significant enterococci was investigated. A total of 10(5) organisms were inoculated a) onto a plate containing 2,000 micrograms/ml of gentamicin or streptomycin; b) into a microtube for dilution MIC determinations for gentamicin, amikacin, tobramycin and streptomycin; and c) into a single tube containing 500 micrograms/ml of gentamicin, amikacin, tobramycin or streptomycin in supplemented Mueller-Hinton broth. In addition, tubes containing 500 micrograms/ml of gentamicin, amikacin, tobramycin or streptomycin were inoculated with five enterococcal colonies ("crude" method). For 45 of the 62 isolates, MICs of gentamicin, amikacin and tobramycin were less than or equal to 500 micrograms/ml, while 17 (27%) showed high-level resistance. The MICs of streptomycin were less than or equal to 500 micrograms/ml for 42 of 62 isolates, and greater than or equal to 2,000 micrograms/ml for 20 (32.3%). For 8 of the 17 (47%) isolates showing high-level gentamicin resistance, MICs of streptomycin were less than or equal to 500 micrograms/ml. There was complete agreement between the results of the plate method, the microtube dilution MIC and the tube inoculated with 10(5) CFU, but the crude method gave discordant results for two isolates. It is concluded that a tube containing 500 micrograms/ml of aminoglycoside is a simple, accurate and inexpensive method for determining high-level aminoglycoside resistance.

Amikacin↗
PubMed1990

Personality alterations in multi-infarct dementia.

Multi-infarct dementia (MID) produces changes in intellectual function and in overt behavior, but alterations in demeanor have received little systematic investigation. In this study, an assessment of personality change occurring after the onset of the dementia was performed using an inventory completed by the subjects' spouses. Personality alterations in MID were compared to those occurring in a group of healthy elderly individuals. Twelve of the 18 inventory items changed more in the MID patients than in normal control subjects. Personality changes are a consistent part of the clinical syndrome of MID and occur early in the course of the disease.

Aged↗
PubMed1990

Organic personality disorder in dementia syndromes: an inventory approach.

Personality alterations were investigated in patients with dementia of the Alzheimer type (DAT), multi-infarct dementia (MID), and normal control subjects, using a standardized informant-rated personality inventory. Personality alterations were observed in all patients, and the two diagnostic groups exhibited many similar behavioral alterations. DAT patients had significantly greater alterations in maturity and exhibited less personal control compared with the MID patients; the latter manifested more apathy and remained more affectionate and easy-going. Few correlations were found between the severity of dementia and the magnitude of behavioral changes. Personality alterations are an important and consistent aspect of the phenomenology of dementing disorders.

Aged↗
PubMed1988

Personality alterations in dementia of the Alzheimer type.

Personality alterations in dementia of the Alzheimer type (DAT) are common but have received little systematic or quantitative investigation. In this study, changes in personality in patients with DAT were compared with those of nondemented retirees using a personality inventory. The inventory used information obtained from each subject's spouse. No personality changes were identified in the control subjects when pre- and post-retirement inventory scores were compared, whereas patients with DAT had highly significant alterations on 12 of the 18 inventory items. The results demonstrate that patients with DAT become more passive, more coarse, and less spontaneous as a result of the disease. Personality changes are a consistent part of the clinical syndrome of DAT and occur early in the course of the disease.

Aged↗
PubMed1979

Decrease in metacontrast masking following adaptation to flicker.

Selective adaptation was used to explore the characterisitcs of a metacontrast masking stimulus which contribute to its effectiveness in masking the test stimulus. Subjects adapted for 10 s to a configuration like the masking stimulus that was either continuously on or flickering. Following this they viewed a metacontrast presentation and estimated the brightness of the test stimulus. Prior adaptation to a continuously present stimulus did not appreciably affect metacontrast masking; however, masking was greatly reduced following adaptation to flickering stimuli. These results are consistent with recent models of metacontrast masking based on transient and sustained visual channels.

Adaptation, Ocular↗
PubMedDate not supplied

Personality alterations in dementia of the Alzheimer type: a three-year follow-up study.

Alterations in personality accompany the onset and progression of dementia of the Alzheimer type. Longitudinal investigations of these changes using systematic quantifiable documentation have been infrequent. In this 3-year follow-up study, we report longitudinal observations of changes in personality in dementia of the Alzheimer type. Four response patterns were observed: (1) change at onset with little change as the disease continued, (2) ongoing change as the disorder progressed, (3) no change, and (4) regression of previously more disturbed behaviors. Repeated characterizations of the premorbid personality profile as determined by this inventory were found to be reliable.

Aged↗