Bioassay

While immunological methods measure the mass of circulating testosterone, the overall androgenic bioactivity in serum and peripheral tissues results frombioavail-able testosterone and other androgens. An in vitro androgen bioassay has been recently developed, based on the androgen-dependent interaction between the ligand-binding domain and the N-terminal region of the androgen receptor, which were fused to Gal4 DNA-binding domain of Saccharomyces cerevisiae and to the transcriptional activation domain of herpes simplex VP16 protein, respectively. These plasmids are transfected in COS-1 cells together with the coexpression of AR-interacting protein 3, which amplifies the interaction, and with the reporter plasmid containing five Gal4-binding sites upstream of the luciferase gene. Luciferase activity measured in cell lysates results from androgen bioactivity in serum added to the cell cultures (Raivio etal. 2001). This bioassay has a sensitivity of 0.8 nM testosterone equivalents and correlates significantly with total testosterone and free testosterone index. In addition, the bioassay measures androgen levels three to four times lower than total serum testosterone measured by RIA, suggesting that only free and albumin-bound testosterone, i.e. bioavailable testosterone, are detected as bioactive. The use of this novel bioassay is as yet limited to the experimental field (Raivio etal. 2002; Raivio etal. 2003a and b).

Hair Loss Prevention

Hair Loss Prevention

The best start to preventing hair loss is understanding the basics of hair what it is, how it grows, what system malfunctions can cause it to stop growing. And this ebook will cover the bases for you. Note that the contents here are not presented from a medical practitioner, and that any and all dietary and medical planning should be made under the guidance of your own medical and health practitioners. This content only presents overviews of hair loss prevention research for educational purposes and does not replace medical advice from a professional physician.

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