Thesis (M.Ag.Sc. 1972)--University of Adelaide, based on a study done in the South Australian Department of Agriculture.

Thesis (Ph. D.)--Virginia Polytechnic Institute, 1970. / Also available via the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Last two leaves of Table of Contents misnumbered v, vi instead of x, xi. Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2004. / Last two leaves of Table of Contents misnumbered v, vi instead of x, xi. Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)-- Florida State University, 2006. / Advisor: Cathy W. Levenson, Florida State University, College of Human Sciences, Dept. of Nutrition, Food, and Exercise Science. Title and description from dissertation home page (viewed Jan. 2, 2007). Document formatted into pages; contains xi, 83 pages. Includes bibliographical references.

Young Wistar female rats weaned at 25 days were placed on a control diet, or a diet extremely deficient in phosphorus but adequate in all other respects. After five weeks on the diet they were injected with 10 microcuries of high specific activity radiocalcium. The animals were killed at varying periods after injection and samples of bone, teeth and soft tissues were taken for chemical, radio-isotope, and histological analysis. The phosphorus deficient animals showed a marked demineralization of the skeleton, lower radiocalcium uptake by bone and higher radiocalcium uptake by the teeth. The accretion and resorption rate of bone in the phosphorus deficient animals was markedly reduced. The resorption rate, however, was higher than the accretion rate and accounted for the reduced mineralization of the bone. The femur of the rachitic animal had an exchangeable calcium portion of 13% as compared to 4-8% in the control animal. The teeth of the phosphorus deficient animal showed a reduced accretion and attrition rate, and a statistically evident difference in the chemical calcium and phosphorus content. The accretion rate was higher than the attrition rate, so that the teeth remained well mineralized. The depression of the accretion rate was not as marked as that observed in the bone, therefore, the marked demineralization of the rachitic animals' bones was not evident in the teeth. The serum plasma levels for calcium and phosphorus were 9.43 mg.% and 2.86 mg.% in the rachitic animal and 9.91 mg.% and 7.24 mg.% in the control animal. The disappearance of plasma radiocalcium was not as rapid in the rachitic animals. Starvation of phosphorus deficient animals resulted in a lower plasma calcium and raised plasma phosphorus level similar to that observed in parathyroidectomized animals. The soft tissue calcium concentration in the rachitic animals as compared to the control animals was higher for all soft tissues examined with exception of the kidney and blood plasma where there was no significant difference. The amount of calcium in the various muscle compartments was calculated. The rachitic animal had a higher intra-cellular calcium concentration and the same extra-cellular concentration when compared with the control animal. There was no difference in the phosphorus concentration of the control and rachitic animals' soft tissues. Histological studies of the femur of the rachitic and control animal showed that the rachitic femur had a wider epiphyseal cartilage which was not uniform in width. The bone trabeculae showed wide irregular seams of uncalcified osteoid matrix. Histological and calcium analysis of the kidneys of the phosphorus deficient animals showed no evidence of calcium deposits or nephrocalcinosis. Histological studies of the parathyroid glands of rachitic animals showed a decrease, in the volume of the glands, in the size of the nuclear surface, and in the amount of cytoplasm present, when compared to the glands of the control animals. This study of calcium kinetics in the phosphorus deficient animal coupled with the histological findings shows the possibility that phosphorus deficiency in rats produces a hypoparathyroid condition as a homeostatic mechanism to conserve phosphorus for the soft tissues. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

The incidence of cleft palate was observed in 1361 F₁, 1531 F₂, and 2275 backcross embryos and chicks from a reciprocal cross between an inbred Leghorn line selected for high incidence (30 to 50%) of cleft palate and a non-cleft palate (New Hampshire; zero %) line. Cleft palate appeared in the F₁ at frequencies less than 1%, in the F₂ at approximately 1%, and in the backcrosses at approximately 8%. When dams were fed a diet deficient in riboflavin, the incidence of cleft palate was shown to increase for the F₂ and backcross progeny to 4% and 12% respectively. The response of cleft palate incidence to riboflavin deficiency was shown to be in large part a genetic characteristic of the embryo itself and not the dam. The reduced hatchability of eggs during maternal riboflavin deficiency was shown to be similar to earlier reports. No evidence of any unusual response of cleft palate line hens to riboflavin deficiency was found for hatchability, chick body weight, nor maternal effect on cleft palate. The cleft palate condition was shown to be semi-lethal, the lethality being partially due to severe expression of the trait. Genetic models were considered and it was suggested that the model to be further tested should be that of 3 recessive loci, one of which involves a fault in the normal metabolism of riboflavin, and a few additive loci controlling penetrance and expressivity of the trait. / Land and Food Systems, Faculty of / Graduate

The study of thyroid metabolism usually involves the employment of antithyroid compounds and exogenous thyroid hormones in order to elucidate the thyroid function through the understanding of the effects of these compounds. In this study, the effects of die thiouracil and rapeseed meal goitrogens were examined in chicks. The goitrogenic effects of the thiouracil were manifested rapidly by increased thyroid weight, thyroid epithelium and uptake of radioiodine. The goitrogenic effects of rapeseed meal were similar to the effect of thiouracil except that at the level of meal fed, the effects were less pronounced and evident only after prolonged feeding. When an iodine deficient diet was fed to growing chicks, the goitrogenic effect was less than when thiouracil or rapeseed meal was fed. Histological studies of the thyroid glands of adult birds fed an iodine deficient diet showed slight hyperplasia without thyroidal enlargement and with persistence of colloid,whereas growing chicks fed an iodine deficient diet displayed severe hyperplasia and loss of colloid. By contrast, the effects of thiouracil were independent of the age of chicks. A combination of thiouracil and rapeseed meal produced goitrogenic effects greater than those occurring when thiouracil or rapeseed meal was fed singly. Thiouracil fed in an iodine deficient diet, on the other hand, showed no goitrogenicity for chicks. High doses (4.0 μg) of thyroxine administered daily to thiouraci1-treated chicks alleviated the antithyroid effects of thiouracil as indicated by the decrease in thyroid weight, thyroid epithelium and radioiodine uptake. Low doses (1.0 ug or less) of thyroxine administration, however, produced the opposite effects. Nevertheless, high doses of thyroxine did not relieve the growth depressing effects of thiouracil completely. Autoradiographic studies on thyroids of thiouraci1-treated or rapeseed meal-fed chicks showed a uniform distribution of radioiodine in the colloid within five hours of administration of tracer. Differences in activity were observed among the individual follicles in each gland. The smaller follicles concentrated more iodine than the larger ones. Furthermore, very little iodine was observed in the epithelial cells. These findings, together with previous reports that inorganic iodine was present in the thyroid after its administration, suggested that iodination did not occur in the apical membrane of the follicular cells bordering the colloid. Different rapeseed cultivars contain different amounts of glucosinolates which are responsible for the goitrogenic effect of the rapeseed meal. Goitrogenicity of three different kinds of rapeseed meals was compared in growing chicks and the results indicated that Candle meal had the least goitrogenic activity than the Tower and Span meal. / Land and Food Systems, Faculty of / Graduate

No description available.

Call number: LD2668 .T4 1964 A55 / Master of Science