Effect of testosterone replacement on response to sildenafil citrate in men with erectile dysfunction: a parallel, randomized trial.

Background: Erectile dysfunction and low testosterone levels frequently occur together.

Objective: To determine whether addition of testosterone to sildenafil therapy improves erectile response in men with erectile dysfunction and low testosterone levels.

Design: Randomized, double-blind, parallel, placebo-controlled trial.

Adverse events associated with testosterone administration.

Background: Testosterone supplementation has been shown to increase muscle mass and strength in healthy older men. The safety and efficacy of testosterone treatment in older men who have limitations in mobility have not been studied.

Methods: Community-dwelling men, 65 years of age or older, with limitations in mobility and a total serum testosterone level of 100 to 350 ng per deciliter (3.

The effects of injected testosterone dose and age on the conversion of testosterone to estradiol and dihydrotestosterone in young and older men.

Background: During testosterone (T) therapy, T is partly converted to 17beta-estradiol (E2) and 5alpha-dihydrotestosterone (DHT). Effects of age, testosterone dose, and body composition on total and free E2 and DHT levels are unknown.

Objective: We evaluated age and dose-related differences in E2 and DHT levels in response to graded doses of testosterone enanthate in young and older men.

Sex hormone-binding globulin as an independent predictor of incident type 2 diabetes mellitus in men.

Background: Low levels of sex hormone-binding globulin (SHBG) and total testosterone (T) in men have been associated with increased risk of type 2 diabetes mellitus (T2DM). As total T and SHBG levels are highly correlated, we determined whether SHBG influences the risk of T2DM through T or whether SHBG is an independent predictor of T2DM.

Methods: Longitudinal analyses were conducted on men participating in the Massachusetts Male Aging Study, a population-based study of men aged 40-70 years.

Safety and efficacy of testosterone gel in the treatment of male hypogonadism.

Transdermal testosterone gels were first introduced in the US in 2000. Since then, they have emerged as a favorable mode of testosterone substitution. Serum testosterone levels reach a steady-state in the first 24 hours of application and remain in the normal range for the duration of the application.

Measurement of myostatin concentrations in human serum: Circulating concentrations in young and older men and effects of testosterone administration.

Unlabelled: Methodological problems, including binding of myostatin to plasma proteins and cross-reactivity of assay reagents with other proteins, have confounded myostatin measurements. Here we describe development of an accurate assay for measuring myostatin concentrations in humans. Monoclonal antibodies that bind to distinct regions of myostatin served as capture and detector antibodies in a sandwich ELISA that used acid treatment to dissociate myostatin from binding proteins.

The physiological and pharmacological basis for the ergogenic effects of androgens in elite sports.

Androgen doping in power sports is undeniably rampant worldwide. There is strong evidence that androgen administration in men increases skeletal muscle mass, maximal voluntary strength and muscle power. However, we do not have good experimental evidence to support the presumption that androgen administration improves physical function or athletic performance.

Effects of graded doses of testosterone on erythropoiesis in healthy young and older men.

Context: Erythrocytosis is a dose-limiting adverse effect of testosterone therapy, especially in older men.

Objective: Our objective was to compare the dose-related changes in hemoglobin and hematocrit in young and older men and determine whether age-related differences in erythropoietic response to testosterone can be explained by changes in erythropoietin and soluble transferrin receptor (sTfR) levels.

Design: We conducted a secondary analysis of data from a testosterone dose-response study in young and older men who received long-acting GnRH agonist monthly plus one of five weekly doses of testosterone enanthate (25, 50, 125, 300, or 600 mg im) for 20 wk.