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N Tsang

Publications and source records attributed to N Tsang.

4 recordsLinked to original sources

Trends in peptic ulcer mortality in Sydney from 1971 to 1987.

Gastric and duodenal ulcer (GU,DU) mortality in Western countries has varied over time by age and sex. Temporal variation raises the question of whether these ulcers have an environmental etiology. Using death certificate data, we investigated peptic ulcer mortality time trends from 1971 to 1987 in Sydney, Australia, and whether ulcer mortality and overall mortality in Sydney were similar with regard to time trends and associations with demographic and environmental factors. In men in all age groups and in women age < 65, GU and DU mortality decreased. In women age > or = 70, GU mortality remained constant and DU mortality increased. Average age at ulcer death increased: from 1971 to 1987, ulcer deaths at age > or = 70 rose from 52 to 80% of all ulcer deaths. In men who died at age 30-54, GU and DU mortality decreased relative to overall mortality. In women who died at age > or = 55, DU mortality increased relative to overall mortality. Compared with overall mortality, the ulcer mortality rate was affected more adversely by lower social class and lack of the marriage tie, and smoking rates tended to correlate more strongly with GU mortality. The greater-than-expected decrease in GU and DU mortality in younger men and the increase in DU mortality in elderly women suggest important changes in as yet unidentified environmental risk factors for ulcer mortality within the young adult male and elderly female general populations.

Adult↗

Common mechanism for repellents and attractants in bacterial chemotaxis.

The migrational response of Salmonella typhimurium away from compounds such as phenol, indole, acetic acid, and leucine occurs because the bacteria tumble less frequently while descending gradients of repellents. This contrasts with their response of tumbling less frequently while ascending gradients of attractants. The results of competition experiments suggest that repellents, like attractants, operate through specific receptors, and the algebraic additivity experiments indicate that repellents and attractants utilize a common memory mechanism for taxis.

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