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D I Walker

Publications and source records attributed to D I Walker.

6 recordsLinked to original sources
PubMed1979

Effect of ionizing radiation on 15-hydroxy prostaglandin dehydrogenase (PGDH) activity in tissues.

Whole body irradiation of mice with 200-1000 R of unfiltered X-radiation (230 kV, 15 mA, 140 R/min) produced extensive falls of 15-hydroxy prostaglandin dehydrogenase (PGDH) activity in the spleen within 4 hours. A transient recovery between 4 and 72 hours was followed by a second reduction in PGDH levels which was still evident 7 days after exposure. In the jejunum and kidney, the falls were smaller. High doses (1000 R) increased PGDH activity in the lung. Effects of radiation on the other cellular enzymes, including other dehydrogenases in the cytosol, were less pronounced, and in some cases the opposite of the effects on PGDH. The loss of PGDH may contribute to the increase in prostaglandin concentrations in the spleen and jejumun, and thereby to some features in radiation sickness.

Animals↗
PubMed1977

Prostaglandins and complement changes in some conditions related to inflammation.

Exposure to ionizing radiation produces several systemic and local reactions which could be mediated by prostaglandins. Prostaglandin levels were therefore studied in blood and tissues of mice which had been exposed to x-rays. Significant increases were found in spleens after 200 to 700 R, and in lungs after 600 to 700 R. These changes were most pronounced 4-7 days after irradiation. Ionizing radiation promptly and potently reduced the activity of prostaglandin dehydrogenase in the spleen, whereas prostaglandin synthesis was less affected. Evidence was obtained for the activation and consumption of haemolytic complement in serum in the course of heart-lung operations involving extracorporeal circulation. Activation involved primarily the classical pathway, and only slightly the alternate pathway.

Animals↗
PubMed1976

Effect of ionizing radiation on prostaglandin-like activity in tissues.

One to 7 days after whole body exposure of mice to a single dose of 700 R of x-rays, little or no change was detected in prostaglandin-like activity in the brain, blood and seminal vesicles. Slight increases in intestinal and renal tissue were not significant. In the lung, mean activity rose from 62 ng/g to a transient peak of 145 ng/g wet weight on the fourth day (P less than 0.05). In the spleen, mean levels rose steadily from 13.2 ng/g to 259 ng/g on the fourth day (P less than 0.01), and were still 184.4 ng/g on the seventh day. 2 Prostaglandin-like activity was measured 4 days after single doses of 200-700 R. In the lung, a significant rise was produced by 600 and 700 R, and in the spleen by 200-700 R. 3 Thin layer chromatography showed that part of the prostaglandin-like activity in spleen extracts had RF similar to that of [3H]-prostaglandin E1, and part to that of [3H]-prostaglandin F2alpha. 4 Splenic tissue from mice exposed to 700 R four days earlier, inactivated prostaglandin E1 less potently than did tissue from non-irradiated mice.

Animals↗