Dating testosterone

There has been some speculation that estrogenic compounds may adversely affect the fertility of men by reducing testosterone levels and sperm counts (Atanassova et al, 2000). To date, however, the limited information available suggests that consumption of phytoestrogens does not affect reproductive hormones or semen quality (Nagata, 2000 Nagata et al., 2001 Mitchell et... 

Testosterone is available as oral testosterone undecano-ate, buccal testosterone, intramuscular testosterone esters, testosterone implants, and testosterone transdermal patches and gel. Proponents of transdermal testosterone products, such as gels and scrotal or non-scrotal dermal patches, claim that they have a good safety profile (101). Transdermal testosterone replacement certainly improves bone mass and lean body mass, reduces fat mass, and improves mood and sexual function. There are said to be no harmful effects on the prostate and lipids. Acne, polycythemia, and gynecomastia are stated to be less common with this form of therapy than with the intramuscular esters. To date these claims must be regarded with some reservations it is not at all clear that in equieffective doses the local or topical forms of administration dissociate wanted and unwanted effects. 

There are many techniques that can be employed to assess the immuno-genicity of a vaccine candidate, and laboratories interested in pursuing this objective should also explore other assays suited to their purposes. In this model, vaccine immunogenicity is measured by determining levels of anti-LHRH antibodies induced in mice immunized with lipopeptide or a nonlipi-dated peptide control. It is important to correlate vaccine immunogenicity with biological function, and we measure the reproductively capability of vaccinated female mice as an indication of vaccine efficacy. Techniques that determine testosterone and oestrogen levels are also useful. 

The differentiation of normal from abnormal concentrations of plasma testosterone in women requires the use of either electron-capture GLC, isotopic-displacement methods, double-isotope methods, or fluorometric methods. Evidence to date suggests that the isotopic-displacement method is preferable (K3, M3). Existing fluorometric methods are adequate in analytical characteristics, but much more laborious (F2). This differentiation is crucial in cases of simple, provisionally idiopathic, hirsutism (cf. however. Cl). In many cases, however, an elevated excretion of urinary testosterone glucuronide would be equally satisfactory despite the uncertainty of its metabolic precursors (B2, II). This measurement is also desirable in cases of provisionally idiopathic amenorrhea. 

GC-(high resolution)MS after enzymatic hydrolysis of the glucuro- and sulphoconjugates and trimethyl-silylation is the most widely used method for the determination of anabolic steroids and their metabolites in the urine of athletes. The most up-to-date technique for the solution of the difficult problem of differentiating between endogenous and exogenous testosterone is gas chromatography - combustion/ isotope ratio (C /C ) mass spectrometry (GC-C-IRMS). 

In the biosynthesis of estrone from J -androstenedione, or estradiol from testosterone, or estriol from 17a-hydroxytestosterone (Ryan, 1959), the aromatization of ring A is initiated by reactions designed to remove the angular C-19 methyl group (Meyer, 1955). It is now well-established that the first step is the hydroxylation of this carbon. The progression of reactions beyond this point is not yet clearly defined. However, from information available to date a pathway which appears most probable has been proposed (Fig. 16) (Longchampt et al., 1960b). 

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