Sam L. Hansard

Blood Volume of Swine.

Summary The P32 labeled red blood cell method has proven satisfactory for the determination of blood volumes in swine. Values obtained ranged in regular fashion from 7.4 to 4.6 ml/100 g body weight for 10 to 344 lb animals^ respectively.

Copper, molybendum and zinc interrelationships in rats and swine.

Summary and Conclusions Substantial increases in tissue copper concentrations and radiocopper accumulation resulted when a: level of 1000 p.p.m. of molybdenum as sodium molybdate was fed to rats and swine on a natural ration. This increase was especially pronounced in the kidneys and livers and is in accord with the hypothesis that excess copper, which is not physiologically effective, may be accumulated when a high level of molybdenum is fed. A dietary level of 1000 p.p.m. of zinc did not appear to have any appreciable effect upon copper metabolism. Growth depression in rats produced by 1000 p.p.m. of added molybdenum to a natural or synthetic ration was not counteracted by the addition of 200 p.p.m. dietary copper. Swine appeared to be more resistant to molybdenum toxicity than did rats. No degenerative changes were observed in the spinal cord, leg joints or muscle tissues of swine fed levels of 1000 p.p.m. of molybdenum or 1000 p.p.m. zinc for a 7-month experimental period. With the criteria of these experiments it appears that dietary zinc was not involved in copper-molybdenum imbalance.

Effect of calcium status, mass of calcium administered and age on Ca45 metabolism in the rat.

Summary (1) The fecal excretion of orally administered Ca45 is a sensitive indication of the calcium status of the rat; (2) placing normal rats on a low calcium diet for as little as 2 days greatly increased their ability to absorb Ca45 from the tract; (3) the specific activity of labeled calcium at the site of absorption had little effect upon its absorption; (4) in general, younger rats absorbed more Ca45 than did older ones although there was no significant difference between 6 1/2 and 16-month-old animals; (5) for meaningful studies of this type, interpretations must include consideration of exchange reactions, and care must be given to initial selection of diets and animals, preparation of animals for the experiment, and dietary management during the experimental period.

Placental Transfer of Iron in Swine as a Function of Gestation Age.

Summary Results of radio-chemical studies with 9 pregnant and 3 control gilts dosed intravenously with a single tracer injection 6f Fe59 citrate, and sacrificed after 48 hours, indicated Fe59 values to increase 7-fold between 35 and 70, and 5-fold from 70 to 105 days gestation, respectively. Total fetal iron content increased from 0.18 mg at 35 days to 4.3 and 14.9 mg at 70 and 105 days, respectively. Fetal liver and spleen exhibited greatest contribution to hematopoiesis during early gestation, while these organs and red bone marrow became increasingly important as pregnancy advanced. Results of this study indicated that iron is transferred across the placental membranes of swine at each trimester, with quantity and rate increasing progressively with each stage of gestation.

EFFECTS OF HYDROBIOTITES UPON STRONTIUM-89 AND CESIUM-137 RETENTION BY RUMINANT ANIMALS

Summary Radiochemical studies with ruminant animals indicate that activated verxites, a nearly pure hydrobiotite, effectively bind Sr-89 and Cs-137 in vitro and in vivo, thus increasing excretion rate and quantity of these radio-nuclides injected or ingested at tracer levels. Appreciation is expressed to L. Young and B. Patterson for technical assistance, and to Zonolite Division, W. R. Grace & Co. for hydrobiotites and grant-in-aid support of this research.

Relationship Between Circulating Red Cell Volume and Endogenous Thyroxine in Sheep.

Summary Radiochemical procedures with 31 castrated male sheep employed to investigate relationships between thyroxine degradation rate and total red cell volume (RCV) permitted procurement of accurate and dependable results without use of substitution therapy. The significant relationship (P< 0.01) between degradation and RCV in these intact animals, under physiological conditions and independent of body weight, would suggest environmental factors to affect red cells through the thyroid axis. The nature and mechanisms of these relationships, though considered speculative, were discussed.