Dispersal and attenuation of trace contaminants downstream of the Ajka bauxite residue (red mud) depository failure, Hungary.

This paper identifies the spatial extent of bauxite processing residue (red mud)-derived contaminants and modes of transport within the Marcal and Rába river systems after the dike failure at Ajka, western Hungary. The geochemical signature of the red mud is apparent throughout the 3076 km² Marcal system principally with elevated Al, V, As, and Mo. Elevated concentrations of Cr, Ga, and Ni are also observed within 2 km of the source areas in aqueous and particulate phases where hyperalkalinity (pH < 13.

Molecular profiling of the human testis reveals stringent pathway-specific regulation of RNA expression following gonadotropin suppression and progestogen treatment.

Gonadotropin withdrawal induces changes in gene expression in all 3 major cell types of the testis. Knowledge of the genes affected, in both the presence and absence of additional progestogen, will give insight into the regulation of human testicular function and aid development of novel contraceptive methods. We have undertaken a whole-genome analysis of RNA expression in testicular biopsies from normal men and after 4 weeks of gonadotropin suppression induced by gonadotropin-releasing hormone antagonist plus testosterone administration sufficient to cause marked suppression of spermatogenesis.

7alpha-methyl-19-nortestosterone (MENT) vs testosterone in combination with etonogestrel implants for spermatogenic suppression in healthy men.

Testosterone with a progestogen can suppress spermatogenesis for contraception. The synthetic androgen 7alpha-methyl-19-nortestosterone (MENT) may offer advantages because it is resistant to 5alpha-reduction and is therefore less active at the prostate. This study aimed to investigate MENT implants in combination with etonogestrel on spermatogenesis, gonadotropins, and androgen-dependent tissues in comparison with a testosterone/etonogestrel regimen.

A diurnal variation in testicular hormone production is maintained following gonadotrophin suppression in normal men.

Objective: A diurnal variation in serum testosterone in adult men is well recognized, but whether this occurs during exogenous testosterone administration and the degree to which it is endogenous to the testis is unclear.

Design: A clinical research centre investigation of testicular function in normal men.

Patients: Twenty normal men were recruited, 10 of whom were investigated during administration of testosterone with etonogestrel to suppress gonadotrophin secretion.

Calculated free testosterone in men: comparison of four equations and with free androgen index.

Background: Serum testosterone remains the most important investigation in the diagnosis of androgen deficiency in men. Most of the circulating testosterone is bound to albumin and sex hormone-binding globulin (SHBG), whereas free testosterone accounts for approximately 2% of total testosterone. Because direct measurement of free testosterone is impractical in routine practice, several equations are used to provide clinically useful estimates of free testosterone concentration.

Direct effect of progestogen on gene expression in the testis during gonadotropin withdrawal and early suppression of spermatogenesis.

Context: Testicular production of steroids and gametes is under gonadotropin support, but there is little information as to the molecular mechanisms by which these are regulated in the human. The testicular response to gonadotropin withdrawal is important for the development of effective contraceptive methods.

Objective: Our objective was investigation of expression of genes in the normal human testis reflecting steroidogenesis, Sertoli cell function, and spermatogenesis after short-term gonadotropin withdrawal and the effects of activating testicular progesterone receptors.

Male hormonal contraception: a safe option?

Hormonal male contraception is based on the administration of testosterone alone or more likely with a progestogen. Testosterone has been used for several decades for the treatment of male hypogonadism, with an excellent safety record. Use as part of a contraceptive regimen by healthy people for prolonged periods will necessitate careful re-examination of safety issues.

Hormonal contraception in men.

All major advances in the development of hormonal methods of contraception over the past 40 years have been exclusively female orientated with male hormonal contraception forever "just around the corner". Despite this, the last few years have seen a significant increase in the pace of research and increased involvement from the pharmaceutical industry. This is essential if the progress derived from the public sector is to be translated into a real product for widespread use.

Update on the male hormonal contraceptive agents.

There remains a need for new acceptable and effective male contraceptives to increase the choice for couples throughout the world. There have been no recent advances in available male contraceptive methods although a number of promising approaches have been identified, of which the hormonal approach is currently undergoing clinical investigation. In recent years the pace of research in this area has quickened significantly with increasing interest and now investment by the pharmaceutical industry.