Decrease in bone levels of 1,25-dihydroxyvitamin D in women with subcapital fracture of the femur.

In a previous study we were able to show that in women over the age of 45 the level of 1,25-dihydroxyvitamin D (1,25(OH)2D) in bone, but not in serum, is significantly reduced when compared with younger women. In the present study we measured the concentration of 1,25(OH)2D in sera and bones of 19 female patients with subcapital fractures of the femur, mean age 78 +/- 2 years. We were able to show that serum levels of 1,25(OH)2D were within the normal range, while bone levels were markedly reduced compared to levels in femoral bone obtained from young female cadavers or to the previously reported levels in non-osteoporotic elderly women.

The effect of enamel de- and remineralization on permeability to iodide and urea.

Blocks of bovine enamel subjected to de- and remineralization were measured for changes in permeability to iodide and urea. Results were similar, indicating that the diffusion pathways for the two species were comparable, and that sites for iodide binding did not appear to exit.