Biomedical subjects

Susan M Wishart

Publications and source records attributed to Susan M Wishart.

5 recordsLinked to original sources

PubMed2003

Physiological testosterone replacement and arterial endothelial function in men.

OBJECTIVE: The vascular effects of fluctuations in testosterone levels within the physiological range in otherwise healthy men are not known. We therefore aimed to study arterial function in hypogonadal men receiving long-term physiological androgen replacement therapy, at trough and peak testosterone levels. PATIENTS AND DESIGN: We recruited nine hypogonadal men (aged 35 +/- 4 years) receiving androgen replacement therapy, each treated with 800 mg testosterone (T) depot preparations every 6 months. MEASUREMENTS: Serum lipid and hormone levels and arterial reactivity were measured, prior to (trough T) and 2-4 weeks following testosterone administration (peak T). Each subject therefore served as their own control. Vessel diameter was measured by ultrasound at rest, during reactive hyperaemia [leading to flow-mediated dilatation (FMD), an endothelium-dependent response] and after sublingual nitroglycerin (GTN, an endothelium-independent dilator). RESULTS: Serum T (13 +/- 2 nmvs. 27 +/- 3 nm for trough and peak serum T, respectively, P < 0.001; normal adult male range 11-35 nm), and free T (195 +/- 23 pmvs. 510 +/- 93 pm, P < 0.005) significantly increased following subcutaneous depot T administration, as did serum oestradiol (100 +/- 10 pmvs. 175 +/- 9 pm, P = 0.001; normal adult male range < 250 pm). There was a significant decrease in FMD (3.6 +/- 1.1%vs. 3.0 +/- 0.8%, P < 0.01), but GTN responses were similar (9.5 +/- 0.8%vs. 10.4 +/- 1.0%, P > 0.2). Lipid, blood pressure and vessel diameter measurements were also similar before and after testosterone administration. CONCLUSION: Physiological replacement of testosterone is associated with decreased endothelium-dependent dilatation, in hypogonadal men.

Adult↗

PubMed2003

The short-term effects of high-dose testosterone on sleep, breathing, and function in older men.

Androgen therapy may precipitate obstructive sleep apnea in men. Despite increasing androgen use in older men, few studies have examined sleep and breathing. Randomized, double-blind, placebo-controlled studies examining effects of testosterone simultaneously on sleep, breathing, and function in older men are not available. Seventeen community-dwelling healthy men over the age of 60 yr were randomized to receive three injections of im testosterone esters at weekly intervals (500 mg, 250 mg, and 250 mg) or matching oil-based placebo and then crossed over to the other treatment after 8 wk of washout. Polysomnography, anthropometry, and physical, mental, and metabolic function were assessed at baseline and after each treatment period. Testosterone treatment reduced total time slept ( approximately 1 h), increased the duration of hypoxemia ( approximately 5 min/night), and disrupted breathing during sleep (total and non-rapid eye movement respiratory disturbance indices both increased by approximately seven events per hour) (all P < 0.05). Despite expected effects on body composition (increase in total and lean mass, reduction in fat mass, P < 0.05, bioimpedance method), upper airway dimensions did not change (acoustic reflectometry). Driving ability (computer simulation), physical activity (accelerometry, Physical Activity Scale in the Elderly), quality of life (SF36, Functional Outcomes of Sleep Questionnaire), mood (Profile of Mood States Questionnaire), sleepiness (Epworth, Stanford scales), and insulin resistance (homeostasis model) also were not changed by treatment. Short-term administration of high-dose testosterone shortens sleep and worsens sleep apnea in older men but did not alter physical, mental, or metabolic function. These changes did not appear to be due to upper airway narrowing. Further study of longer-term lower-dose androgen therapy on sleep and breathing is needed to evaluate its safety in older men.

Aged↗

PubMed2003

Do reproductive hormones modify insulin sensitivity and metabolism in older men? A randomized, placebo-controlled clinical trial of recombinant human chorionic gonadotropin.

OBJECTIVE: In order to assess the hormonal determinants of insulin sensitivity and related components of the metabolic syndrome, we evaluated the effect of subcutaneous recombinant human chorionic gonadotropin (r-hCG; Ovidrel) on insulin sensitivity, vascular reactivity, leptin, insulin-like growth factor-I (IGF-I) and lipids in ambulant, community dwelling men >60 Years of age with serum testosterone <or= 15 nmol/l on two occasions. DESIGN: Forty eligible men were randomized to receive 250 microg (5000 IU) r-hCG subcutaneously twice each week (n=20) or placebo (n=20) injections for 3 Months, and all subjects (mean age 67 (range 60-85) Years) completed the study. METHODS AND RESULTS: Groups were well matched for height, weight, anthropometry and insulin sensitivity. Insulin sensitivity was assessed by homeostasis model (HOMA) and euglycemic hyperinsulinemic clamp at baseline and at the end of the treatment period in the first 30 men who did not have diabetes mellitus. Insulin sensitivity (HOMA and euglycemic clamp) or beta cell function (HOMA) were not significantly changed by r-hCG despite a significant increase in lean body mass (approximately 2 kg, P<0.001) and reduced fat mass (approximately 1 kg, P<0.05). Subcutaneous fat (skinfold measurements), abdominal girth and serum leptin all decreased and IGF-I tended to increase, but these changes were not significant. Recombinant hCG significantly reduced total and low density lipoprotein cholesterol, and triglycerides, but did not significantly alter high density lipoprotein cholesterol. Endothelial function (vascular reactivity) was not significantly worsened. We conclude that three-Months of treatment with r-hCG demonstrates expected hormonal effects, improved lipids and did not worsen vascular endothelial function. Insulin sensitivity was not altered despite suggestive changes in body composition. CONCLUSIONS: These findings suggest short-term metabolic and cardiovascular safety and argue against an important role for androgens in the hormonal control of insulin sensitivity in older men.

Aged↗

PubMed2002

Predicting pregnancy and spermatogenesis by survival analysis during gonadotrophin treatment of gonadotrophin-deficient infertile men.

BACKGROUND: Predictors of fertility or spermatogenesis during gonadotrophin therapy of gonadotrophin-deficient men remain poorly defined. METHODS AND RESULTS: In order to evaluate potential predictors, this study evaluated 29 consecutive gonadotrophin-deficient men all desiring paternity who received 43 courses of therapy in one centre between 1982 and 1998. The Kaplan-Meier survival analysis estimates of median (SE) time to a sperm concentration of >0, >5 and >20 x 10(6)/ml were 5.5 (1.1), 12.4 (2.3) and 29.1 (1.9) months respectively. Conception occurred in 22/43 cycles (with eight men achieving two pregnancies) with a median (SE) Kaplan-Meier estimate of 20.5 (4.7) months. The median sperm concentration at conception was 5.0 (SE 2.0; range 0.0-59.5) x 10(6)/ml. Multivariate correlated Cox proportional hazards models predicting these same sperm thresholds and conception were developed by forward stepwise variable selection with verification of the model by backward stepping. Larger testicular volume, prior gonadotrophin therapy, completion of puberty, older age, the absence of adverse fertility factors and the absence of multiple pituitary hormone deficiency predicted a favourable response. Multivariate modelling suggests that the two most important predictors of sperm output are testicular volume and pubertal status. The most important potentially modifiable predictor was prior gonadotrophin therapy. The efficacy of recombinant and urinary FSH were similar. Prior androgen therapy and partner's age did not appear to be significant. CONCLUSIONS: Since prolonged treatment may be required to induce spermatogenesis, attention to these predictors may allow appropriate early use of advanced reproductive technologies.

Adult↗

PubMed2002

A double-blind, placebo-controlled, randomized clinical trial of recombinant human chorionic gonadotropin on muscle strength and physical function and activity in older men with partial age-related androgen deficiency.

Despite partial androgen deficiency, the safety and efficacy of androgen therapy in older men remains controversial because controlled studies of testosterone have given equivocal results. Human chorionic gonadotropin (hCG) can be conveniently and infrequently self-administered, and it increases not only circulating testosterone but also estradiol and other testicular steroids. We evaluated the efficacy and safety of 3 months of treatment with sc recombinant hCG (r-hCG, Ovidrel) on muscle mass, strength, mobility, and physical activity in ambulant, community-dwelling men more than 60 yr old having partial androgen deficiency (testosterone < or = 15 nmol/liter, twice). Forty eligible men (mean age, 67 yr; range, 60-85 yr) were randomized to receive r-hCG (5000 IU, 250 microg) or placebo by twice weekly sc self-injection and were studied before treatment, monthly during treatment, and 1 month after treatment. All completed the study, and treatment groups were well matched. r-hCG significantly increased body weight (approximately 1 kg; P < 0.05) and lean body mass ( approximately 2 kg; P < 0.001) and reduced fat mass (approximately 1 kg, P < 0.05). However, anthropometric measures of skinfold thickness (biceps, triceps, subscapular, suprailiac) and circumferences (midarm, waist, hip, and midthigh), including the waist-hip ratio, did not change significantly. Shoulder and knee strength (peak torque), as measured by isokinetic and isometric dynamometry, was not significantly increased, nor was physical activity (accelerometry and Physical Activity Scale for Elderly self-report) or gait and balance (modified Guralnik and Frailty and Injuries: Cooperative Studies of Intervention Techniques performance batteries) altered. Total and free testosterone and estradiol were markedly (150%; P < 0.001) and stably increased, whereas LH, FSH, and urea were significantly decreased. Testis volume was significantly decreased (approximately 5 ml; P < 0.05). There were no significant changes in hemoglobin, osteocalcin, or prostate-specific antigen, and the International Prostate Symptom Score did not change. Three men developed nipple tenderness that did not progress to gynecomastia. We conclude that 3 months of treatment with twice weekly r-hCG demonstrates sustained androgenic effects on hormones and muscle mass but has no effect on muscle strength or physical functioning.

Aged↗