Chalone Epidermal

The onset of diflEerentiation and its subsequent control is attributed to inhibitory feedback by varying concentrations of cellular products or epidermal chalone 30, 88). However, the specific means for initiating cell lysis of desmosomes and intercellular cement to accomplish desquamation is unexplained, although it is known that normal cholesterol metabolism is required for proper separation (2, 62). 

Chalone The Search for Regulators of Epidermal Mitotic Activity... 350... 

Using the mouse ear epidermis in vitro as an assay system and counting mitoses arrested by Colcemid in the medium over a 4-hour period, the same workers showed that the epidermal chalone is not species specific, but is tissue specific (B49, B52) that it requires epinephrine for effect (B48), and perhaps glucocorticoids (B50) and that it is most likely a glycoprotein with a molecular weight of about 30,000 (B25). This work has been recently reviewed and the additional comment made that epidermal chalone is present in active form in human urine (B45). 

Marrs, J., and Voorhees, J., Studies on chalone in epidermal proliferation. Presented at the meeting of the Amer. Fed. for Clin. Res., Atlantic City, New Jersey, May 1970. Clin. Res. 18, P350 (1970). Abstr. 

Voorhees JJ, Duell EG, Bass LJ, Harrell ER (1973) Role of Cyclic AMP in the Control of Epidermal Cell Growth and Differentiation, Chalones Concepts and Current Researches. Natal Cancer Inst Monogr 38 47 and refs, therein... 

A chalone extracted from the skin inhibits epidermal mitosis it is tissue-specific in that it inhibits cell division in the epidermis but not in other tissues, but it is not species specific. 

It is suggested that the intracellular concentration of chalone is responsible for controlling the rate of cell division within a tissue after injury to the skin, chalone is lost from the epidermal cells in the region of the wound and the mitotic machinery becomes activated until the wound is sealed and intracellular chalone levels have been restored. Such substances that cause specific inhibition of tissue growth could be of great significance in the treatment of cancer. 

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