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Calcium-binding protein (CaBP) has been localized with the immunoperoxidase method using antiserum against purified chick duodenal CaBP. Different preparative procedures were employed to investigate the experimental conditions possibly responsible for the contradictory reports in the literature of the precise cellular localization of CaBP. Freeze substitution, frozen sections followed by fixation and coagulant and non-coagulant fixatives were used with appropriate control sections to demonstrate that the true localization of CaBP in the chick duodenum is in the absorptive cell cytoplasm. The goblet cell localization reported in the literature seems to be a diffusion artifact due to inadequate fixation. CaBP was also localized in several other tissues. In the hen uterus, the tubular glands beneath the surface epithelium showed intense reaction. In the kidney, CaBP was present in the cells of the straight and convoluted segments of distal tubules. The cortex of the chick cerebellum showed the CaBP in Purkinje cells. The entire dendritic trees contained the reaction product. No other neurons in the molecular or the granular layer were stained. In the deep cerebellar nuclei, all neurons were negative and these were outlined by deeply staining axons of the Purkinje cells and their synaptic endings.

A survey was conducted among graduates of two Canadian medical schools who have been in practice for more than 9 years. The purpose of the study was to test the hypothesis that graduates of a problem-based curriculum differ from graduates of a traditional curriculum in their attitude to and participation in continuing medical education (CME) activities. Differences were noted in the rate of participation in certain CME activities (attendance at national and international conferences and meetings) between specialists and family doctors in both groups of alumni. However, the data indicate that the differences in learning-teaching methods employed in the course of the undergraduate medical curriculum do not exert a decisive influence upon the learning habits of the graduates.

White Leghorn chick embryos were injected on the 15th day of incubation with 70 to 300 pmoles 1,25-(OH)2D3. All doses produced hypercalcemia; with the highest dose, the concentration of calcium in serum started to rise 4 h after the injection, reached a peak 20 h after, and was still high 48 h after. Twenty hours after the injection of the same dose, the concentration of inorganic phosphorus in the serum was significantly lower than in the corresponding controls. The tibias from 17-day-old chick embryos injected with 300 pmoles on day 15 were shorter, lighter, and had a lower ash content than those from controls. Histological signs of resorption appeared to be reduced with respect to controls, but no precise quantitation was conducted. The fact that hypercalcemia was not accompanied by hyperphosphatemia may suggest that the vitamin stimulates resorption of calcium from the shell, which is mainly formed by calcium carbonate rather than from the bone from which calcium and phosphate are usually resorbed together.

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