|Regional Gamma Irradiation of Pigs
|Published: Open access to everyone
|BIOLOGICAL SAMPLE AVAILABLE
|Purpose: To study the gastro-intestinal syndrome in pigs exposed to the posterior part of the body with the aim to improve the management of accidental over-exposure in man.
Status: 1970 - 1978, terminated
Treatment: Single partial body irradiation of the posterior half part of the body of pigs from the xyphoid appendix downwards; the upper part of the body was shielded with lead plates. The midplane dose from eight Co-60 sources delivered at dose rates from 0.3 to 1 Gy/min ranged from 8 to 18.5 Gy. The animals were followed up to 1 year. Intestinal mucosa biopsies were performed using a cannula indwelling in the jejunal lumen.
Dosimetry: Ferro-sulfate dosemeter, LiF thermoluminescence detectors, ionization chamber
Endpoints: Histological and histo-enzymological evolution of the irradiated intestinal mucosa dependent on time and dose; gastric secretion, intestinal absorption and balance of dietary minerals, nitrogen and lipids; treatment with pharmaceutics and/or surgery (graft and exeresis) in some animals
Animal: Large white pigs 4-5 months old, weighing 25-45 kg;
Adult miniature pigs, Pitman-Moore or Corsican as well as crossbreds, 1-2 years old, weighing 30-70 kg
Results: Supralethal doses (>15 Gy) result in a gastrointestinal syndrome with diarrhoea, increased Na excretion and dehydration and a survival of 4-5 days in large white pigs and 5-7 days in Pitman Moore pigs. Based on studies on DNA content in the ileum after different doses, it appears that at doses above 15 Gy recovery is impossible. Large white pigs supplied with a Pavlov pouch and exposed to 15 Gy show an immediate fall in gastric secretion with abnormalities still present at 3 days whereas histamine- stimulated secretion is but little altered. Corsican pigs provided with an indwelling gastric catheter had long lasting hypochlorhydria as well as an increase of DNA and exudative proteins during the regenerative phase. Induced hyperglycaemia also remained abnormal although insulin secretion was not affected. Exocrine pancreatic function declined progressively leading to poor absorption of feed. Although the intestinal mucosa recovered after doses of 11 Gy, nutritional balance, electrolyte metabolism and pancreatic functions did not recover fully until at least 5 months after exposure. Attempts to treat the gastrointestinal syndrome showed that antibiotics may help to avoid infections and that pigs given parenteral nutrition after 10 Gy with supplements of minerals and water recover more rapidly. Intestinal grafts shortened rather than prolonged survival. Ileoectomy seemed to result in somewhat longer lifespan.
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