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Biomedical subjects

A M Preston

Publications and source records attributed to A M Preston.

27 records · Page 2Linked to original sources
PubMed1979

Effect of palytoxin and serotonin on murine tumor cells.

In vitro and in vivo effects of two fractions of a crude extract from the marine invertebrate Palythoa were investigated in Novikoff hepatoma and Ehrlich ascites tumor cells. These fractions, previously identified as serotonin and a partially purified toxin, inhibited thymidine incorporation into acid-precipitable material by tumor cells. Results from respiration studies indicated that the inhibitory effect was not toxic. The data suggested that: a) The partially purified toxin exerted its inhibitory effect at the membrane level; b) this inhibitory effect might have been accomplished through the Na+K+ transport mechanism, this conclusion being supported by data on the uptake of labeled amino acids by Ehrlich ascites tumor cells; and c) in an unconfirmed experiment, the partially purified toxin increased the survival time of 50% of 6 palytoxin-treated mice at least three times as long as 6 untreated control mice. All 12 mice had received 1 X 10(6) viable Ehrlich ascites tumor cells.

Amino Acids↗
PubMed1976

Effect of dietary chromium on glucose tolerance and serum cholesterol in guinea pigs.

The effects of feeding three levels of dietary chromium (Cr) to non-pregnant guinea pigs, guinea pigs during pregnancy and lactation and F-1 offspring guinea pigs on weight gain, glucose tolerance, glucose peak time value and serum cholesterol concentration has been investigated. Dietary levels of Cr were: Basal Diet (B) = 0.125 ppm; B supplemented with 0.5 ppm Cr (S1 Diet) and B supplemented with 50 ppm Cr (S2 Diet). All groups had similar weight gain patterns and daily feed intake levels. Parent generation guinea pigs fed the B diet consumed less than 10 mug Cr/kg body weight/day while F-U guinea pigs consumed more than this amount. Mortality rates during pregnancy were greater in guinea pigs fed the B diet than in the Cr supplemented groups suggesting a possible protective effect by Dr. Glucose tolerance, glucose peak time values and serum cholesterol appeared to be more affected by pregnancy and generation of guinea pigs than by the level of dietary Cr. Results suggest that species differences may exist between Cr requirements of guinea pigs and rodents for avoiding glucose tolerance.

Animals↗
PubMedDate not supplied

Exposure of Puerto Rican children to environmental tobacco smoke.

BACKGROUND: Many studies of environmental tobacco smoke (ETS) have been conducted in northern, industrialized countries. As yet, however, no studies have been carried out on ETS exposure with nonsmokers living in tropical environments. METHODS: Urine specimens were collected from 175 healthy Puerto Rican children (2-11 years) living in an industrial area and were analyzed for cotinine, a quantitative biomarker for exposure to ETS. Their parents completed a questionnaire covering smoking habits. RESULTS: Seventy percent of children were exposed to ETS. Quantitatively, exposure to smoke in households consuming more than 1 pack per day (ppd) caused a doubling of cotinine excretion compared with households consuming less than 1 ppd. Smoke from mothers made the greatest contribution to cotinine, followed by smoke from fathers, with smoke from other persons having no effect. Degree of exposure was inversely related to age of the child. CONCLUSIONS: Young children (2-4 years) were detected to have significantly greater exposure to ETS than older children (5-11 years) and in the younger group the effect seemed to be from the mother's smoking much more than the father's, with other persons contributing negligible amounts. This suggests an obvious strategy for prevention of exposure to ETS in young children.

Age Distribution↗