References: Hair growth and hair loss
Differentiation. 1993 Jul;53(3):191-200.
Tissue-specific and differentiation-appropriate expression of the human involucrin gene in transgenic mice: an abnormal epidermal phenotype.
Crish JF, Howard JM, Zaim TM, Murthy S, Eckert RL.
Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106.
Involucrin is a precursor of the keratinocyte cornified envelope that is specifically expressed in the suprabasal layers of the epidermis and other stratifying squamous epithelia. To study involucrin gene expression and the function of involucrin, we expressed a 6 kb DNA fragment of the human involucrin gene, containing approximately 2.5 kb of upstream sequence and 0.5 kb of downstream sequence, in transgenic mice. The transgene produces a 68 kDa protein that is detected by a human involucrin-specific antibody, and is expressed in a tissue-specific and differentiation-appropriate manner (i.e., expression is confined to the suprabasal layers of the epidermis, extocervix, trachea, esophagus and conjunctiva). Soluble involucrin levels are two to four times higher in transgenic epidermal keratinocytes compared to human foreskin keratinocytes. Newborn heterozygous animals have a normal birth weight and a normal appearing epidermis and hair growth begins at 4 to 5 days of age (i.e., the same time as hair growth in non-transgenic animals). In a subpopulation of the newborn homozygous animals birth weight is reduced, the epidermis is scaly and hair growth begins late, at around 9 to 10 days of age. In addition, the hair tends to stand erect on both heterozygous and homozygous adult animals giving the appearance of diffuse alopecia. Immunofluorescent and electron microscopy localize involucrin in the hair follicle and cornified envelope, respectively. These results suggest that overexpression of involucrin may cause abnormalities in hair follicle structure/function and cornified envelope structure. These animals provide a new model for the study of cornified envelope structure and function.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8405770&dopt=Abstract
akh-wien.ac.at
Production rates of dihydrotestosterone (DHT) were determined in healthy men (n = 8), in healthy women during the follicular phase of their menstrual cycle (n = 7), and in young men with male pattern baldness (n = 8) using the stable isotope dilution technique and mass spectrometry. [2,3,4-(13)C]DHT was infused for 10 h at doses of 15 microg/h (men) and 2 microg/h (women), and blood samples were obtained at 20-min intervals during the last 4 h of the observation period. Production rates estimated between April and June were 2.9 +/- 1.1 microg/h (women) and 17.8 +/- 6.2 microg/h (men). In men production rates of DHT were similar (16.2 +/- 7.7 microg/h) when the investigation was repeated between October and December. Mean production rates of DHT in young men with male pattern baldness (60 +/- 50 microg/h) were higher than those in healthy men (P < 0.005). Although this group included two individuals with normal production rates of DHT, the production rate of DHT was markedly elevated (range, 32.0-161.0 microg/h) in the remaining patients. Stable isotope-labeled infusions of DHT are suitable for clinical use in a routine setting to obtain analytically correct estimates of DHT production in vivo. In the majority of men with male pattern baldness endogenous production of DHT is markedly increased, providing a rationale for therapeutic 5 alpha-reductase inhibition in this disorder.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11739436&dopt=Abstract
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