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D W Chung

Publications and source records attributed to D W Chung.

59 records · Page 4Linked to original sources
PubMed1977

The mechanism of ADP-ribosylation of elongation factor 2 catalyzed by fragment A from diphtheria toxin.

Measurements of the initial rate of ADP-ribosylation of elongation factor 2 (EF-2) catalyzed by Fragment A from diphtheria toxin support a sequential mechanism and suggest that the reaction proceeds through a central ternary complex involving Fragment A and the substrates, EF-2 and NAD. The Michaelis constants for EF-2 and NAD are 0.15 and 1.4 muM, respectively. As determined by equilibrium gel permeation, EF-2 does not bind Fragment A significantly, alone or in the presence of adenine, ADPribose, nicotinamide or NADH. Based on these and earlier results, we propose an ordered sequential mechanism for the reaction; the sequence of binding of substrates is NAD, followed by EF-2.

Adenine↗
PubMed1977

Enzymatically active peptide from the adenosine diphosphate-ribosylating toxin of Pseudomonas aeruginosa.

A nontoxic peptide (molecular weight, 26,000), which is active in catalyzing the adenosine diphosphate (ADP)-ribosylation of elongation factor 2, has been isolated from the culture supernatant of Pseudomonas aeruginosa strain 103 in stationary phase. Like fragment A from diphtheria toxin, the active peptide catalyzed the hydrolysis of nicotinamide adenine dinucleotide as well as the ADP-ribosylation of elongation factor 2 and showed similarities to fragment A in specific activity, kinetic constants, pH optimum, and ionic sensitivity. These results provide strong evidence for a high degree of homology in the structures of their active sites. That the peptide is not identical to fragment A is shown by the fact that it was not neutralized by fragment A-specific antiserum and was different in amino acid composition and pH and thermal labilities. Although definitive evidence is lacking, there are data suggesting that this peptide is a proteolytic fragment from the ADP-ribosylating toxin (exotoxin A; molecular weight, 66,000) produced by the same strain of P. aeruginosa.

Adenosine Diphosphate Sugars↗
PubMedDate not supplied

The Zung Self-rating Depression Scale: screening for depression among the Hong Kong Chinese elderly.

Two studies were conducted respectively to examine the reliability and validity of the standard Zung Self-rating Depression Scale (SDS), and a 10-item shorter version of the same test. In particular, the scale's usefulness as a screening instrument for depression among the Hong Kong Chinese elderly was investigated. In addition to the SDS, the Geriatric Depression Scale and the Chinese Hamilton Depression Scale were used to assess the convergent validity of the SDS. Data were collected from 113 nondepressed community-dwelling and 80 depressed elderly subjects. The findings showed that both the original and the shorter version of the SDS were highly reliable and valid. Both versions were appropriate for use as screening instruments for geriatric depression in Hong Kong. When compared with the original scale, the shorter version appeared to be slightly superior in its sensitivity and specificity in discriminating between the depressed and nondepressed subjects.

Age Factors↗
PubMedDate not supplied

Life-threatening tardive dyskinesia.

We present the case of a patient with severe tardive dyskinesia that led to dehydration. Clinicians need to recognise that tardive dyskinesia is a potentially life-threatening condition, and familiarise themselves with its management.

Adult↗