Progressive decrease in hair diameter in Japanese with male pattern baldness.

Fifty-six Japanese with male pattern baldness were evaluated for changes in their hair diameters over three years. The mean hair diameter significantly decreased each year. The average decrease was 1.1 microns per year. Although the percentage of vellus hair increased by 3.6% over three years, this increase rate was lower than that found in Caucasians. To precisely examine the change in hair diameter, the mean distribution of this diameter was investigated. At the beginning of the study, clear peaks were observed at 95 microns in the twenties and 45 microns in the fifties. The number of thicker hairs decreased and the high frequency peak shifted to a thinner hair diameter over 3 years. To quantify the change in the distribution of hair diameter, the percentage of hairs of more than 60 microns was examined. There was a statistically significant 5.61% decrease in the percentage of hairs with a diameter of more than 60 microns over three years. Our findings suggest that the progression of male pattern baldness in Japanese is slower than that of Caucasians and that the percentage of hairs of more than 60 microns is a sensitive index to evaluate the progression of male pattern baldness and the effects of hair growth or hair loss preventive agents.

Quantitative evaluations of male pattern baldness.

Several methods for the evaluation of hair growth have been reported; however, none of the hitherto reported methods are satisfactory as unbiased double blind studies to evaluate the efficacy of hair growth agents. In the present paper, we describe quantitative evaluation methods for hair growth by measuring the anagen ratio and hair diameters in 56 Japanese subjects aged 23-56 for 3 years. The average anagen ratio decreased by 3.8% in 3 years. The average hair diameters showed a statistically significant decrease each year totalling 3.4 microns. Subjects were sorted according to their anagen ratio into 4 groups. Each group showed different distribution patterns of hair diameters. The higher anagen ratio group has a high frequency peak at thicker hair diameters and the lower anagen ratio group has a high frequency peak at thinner hair diameters. The number of thicker hairs decreased and the high frequency peak shifted to thinner hair diameters in 3 years. These methods are useful to evaluate both the progression of male pattern baldness and the effects of hair growth agents with double blind studies in an unbiased quantitative fashion.

The effects of vitamin E deficiency on rat skin.

The effect of vitamin E deficiency on the levels of lipid peroxide and solubility of collagen was investigated in Wistar rats that were fed a vitamin E deficient diet for 3 and 6 months. The lipid peroxide content in the skin and subcutaneous tissue was markedly increased as compared with that of control rats on a normal diet. The lipid peroxide content in the tissues of rats deficient in vitamin E for 3 months, was greater than that found in those on the diet for 6 months. The effect of UV irradiation on the lipid peroxide content in the skin of control rats was not significant, but there was a marked difference in lipid peroxide content in those animals on a deficient diet. The amount of insoluble collagen in the skin of rats on a vitamin E deficient diet for 6 months was increased and by more than in those animals on the diet for 3 months. The amount of soluble collagen in the rats deficient in vitamin E for 6 months was markedly reduced when compared with those on the diet for 3 months. These results suggest that vitamin E deficiency promotes the peroxidation of lipids and accelerates the cross-linking of collagen in the skin.

Induction of hyaluronic acid synthetase by estrogen in the mouse skin.

Hyaluronic acid synthetase activity was measured in male mouse skin following the topical application of estradiol in vivo. The enzyme activity increased in parallel with the hyaluronic acid content of the skin, and showed a similar response in the skin of ovariectomized female mice. The increase in enzyme activity was reduced by the anti-estrogen agents, tamoxifene citrate and clomiphene citrate, which block competitively the binding of estrogen to the estrogen receptor. The increase in hyaluronic acid synthetase activity was also reduced by topical application of cycloheximide or by subcutaneous injection of actinomycin D. The results suggest that the stimulation of hyaluronic acid synthesis in mouse skin in response to estrogen treatment is mediated through estrogen receptors and involves the induction of the enzyme hyaluronic acid synthetase.

The mechanism of estrogen-induced increase in hyaluronic acid biosynthesis, with special reference to estrogen receptor in the mouse skin.

The increase in hyaluronic acid and water contents induced by estradiol treatment in the mouse skin was dependent on dose and the number of treatments of estradiol. The anti-estrogen administered together with estradiol blocked the increase in hyaluronic acid content produced by treatment with estradiol alone. It was suggested that the anti-estrogen may act as an antagonist by competing for the cytoplasmic estrogen receptor on increase in hyaluronic acid synthesis. It was observed that the sensitivity in increase in hyaluronic acid biosynthesis by estradiol was related to the age of the mouse and the content of the cytoplasmic estrogen receptor in the mouse skin. It was suggested that there was a possible relationship between the increase in hyaluronic acid and cytoplasmic estrogen receptor in the mouse skin.

Epidermal adenylate cyclase systems: the retention of hormone responsiveness after enzymatic separation of pure epidermis.

Although it has been shown that keratome-sliced skin contains active adenylate cyclase systems which respond to various hormones and drugs, unequivocal proof that the epidermis contains these hormone-responsive systems is still lacking. We demonstrate in this study that "pure" epidermis obtained after either collagenase or trypsin treatment does contain the hormone-sensitive adenylate cyclase systems.

In vitro growth of mouse hair root.

Hair roots from mouse dorsal skin continued to grow in culture medium for 10 h or more after isolation. Under observation by time-lapse cinematography, the cultured hair roots appeared to grow downward. We observed both the downward growth of the cultured hair roots as well as the transfer of melanosomes from melanocytes to cortical cells. The hair roots were also capable of incorporating the labelled amino acid and thymidine.

Transfer mechanism of melanosomes in epidermal cell culture.

The mode of melanosome transfer from melanocytes to keratinocytes in epidermal cell cultures has been examined with time-lapse cinematography and electron microscopy. A tip of a melanocyte dendrite containing melanosomes became enfolded by a recipient keratinocyte. It was then pinched off to form a cluster of melanosomes which initially seemed to be surrounded by two layers of membranes. The phagocytized dendrite was gradually decomposed and became an aggregate of melanosomes surrounded by a single membrane of the keratinocyte. The individual melanosomes were dispersed from the aggregate into the keratinocyte cytoplasm, depending on the size of melanosomes. The larger ones were single and smaller ones were complex. The mechanism of melanosome transfer in vitro is a type of cytophagocytosis. The entire process consists of two steps: the first is a cytophagic process and the second a melanosome dispersion process. The process is influenced by various exogenous factors.