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The binding of [ 3 H]l,25-dihydroxyvitamin D 3 (1,25-(OH) 2 -[ 3 H]D3) was examined in the cytosol of epidermal keratinocytes and dermal fibroblasts grown from normal human skin. Both cell types contained macromolecules with high affinity for 1,25-(OH) 2 D 3 , as demonstrated by sucrose density gradient centrifugation, saturation binding analysis, and DNAcellulose chromatography. Scatchard analysis of cytosol binding of the hormone yielded affinity constants of 1.0 x 10" 10 and 0.8 x 10" 10 M and binding capacities of 6.4 and 8.7 fmol/mg protein for fibroblasts and keratinocytes, respectively. In parallel studies, binding of 1,25-(OH) 2 -[ 3 H]D3 was evaluated in the cytosol from keratinocytes and fibroblasts cultured from a skin biopsy of a patient with vitamin D-dependent rickets, type II (DDR-II), an inheritable disorder characterized by extreme end-organ resistance to the action of 1,25-(OH)2D 3 . Multiple analyses by sucrose density gradient or saturation binding assays failed to reveal specific saturable binding of hormone, suggesting that in this disease the lack of an effective cytosolic receptor protein may account for end-organ insensitivity to the hormone. To evaluate the responsiveness of fibroblasts to 1,25-(OH) 2 D3, we studied the effect of 1,25-(OH) 2 D 3 on cell growth. 1,25-(OH) 2 D 3 (10~1 0 -10~6 M) caused a dose-dependent inhibition of cell growth in receptor-positive normal fibroblasts, whereas these doses of hormone did not affect the growth of receptor-defective DDR-II cells. Hence, the presence of an effective cytosolic receptor in normal skin fibroblasts may be necessary for expression of the growth inhibitory effect of 1,25-(OH) 2 D 3 . (J Clin Endocrinol Metab 56: 824, 1983) V ITAMIN D 3 is synthesized photochemically in the skin and then sequentially hydroxylated to 1,25-dihydroxyvitamin D 3 [1,25-(OH) 2 D 3 ], the biologically active form of the vitamin (1). This hormone acts on target tissues, such as the intestine, after binding to a specific cytosolic receptor protein. Recently, receptor-like binding proteins for 1,25-(OH) 2 D 3 have been demonstrated in intact mammalian skin (2-5), raising the possibility that the hormone might function in this tissue. Subsequent studies by Eil and Marx (6) have shown that

Using the photoacoustic effect of interference fringes scanned at the phase velocity of surface acoustic waves (SAW), we excited tone bursts of SAW with a center frequency of around 30 MHz on a 8 mm φ steel bearing ball. A surprisingly large number (around 20 turns) of round-trip propagations was observed. The time interval between the SAW at the first and the twelfth turn was as large as 93 μs, however it could be determined with a 2 ns resolution since an exact overlapping of the two wave forms was possible. Thus, we achieved a very high resolution of 0.002% in the velocity measurement, and a velocity change of 2 m/s due to the deposition of a 50-nm-thick Ag film was easily detected. Because of its noncontact nature, this method would be useful for nondestructive evaluation of bearing balls.