Cross-sectional association between physical activity and serum testosterone levels in US men: results from NHANES 1999-2004.

Testosterone levels and physical activity each play important roles in men's health, but the relationship between the two remains unclear. We evaluated the cross-sectional association between self-reported total physical activity and serum testosterone levels in 738 men (mean age 42.4 years, range 20-≥85 years) who participated in National Health and Nutrition Examination Survey 1999-2004. We compared geometric mean testosterone concentrations measured by radioimmunoassay (RIA) and calculated the odds ratio (OR) of having low or low normal testosterone (≤3.46 ng/mL) across tertiles of total physical activity in all men, and men stratified by age (20-49, ≥50 years), and obesity status (BMI < 30, ≥30 kg/m(2) ). The geometric mean testosterone concentration was 5.31 ng/mL; 18.6% of the men had low or low normal serum testosterone levels. Physical activity tertiles were not associated with testosterone levels overall, or when stratified by age or obesity status. Similarly, there was no association between physical activity tertiles and the odds of low or low normal testosterone, overall or by age. However, among non-obese men, those in the highest physical activity tertile were significantly less likely to have low or low normal testosterone than those in the lowest tertile (OR 0.50; 95% CI = 0.26-0.95); there was no association among obese men. Greater physical activity was not associated with testosterone levels, but may be associated with a reduced odds of low or low normal testosterone in non-obese men, but not in obese men.

Association between endogenous sex steroid hormones and inflammatory biomarkers in US men.

Sex steroid hormones and inflammatory biomarkers are both associated with the development and progression of chronic diseases, but their interrelationship is relatively uncharacterized. We examined the association of sex hormones and sex hormone-binding globulin (SHBG) with biomarkers of inflammation, C-reactive protein (CRP) and white blood cell (WBC) count. The study included data from 809 adult men in the National Health and Nutrition Examination Survey 1999-2004. Geometric means and 95% confidence intervals were estimated separately for CRP and WBC concentrations by sex steroid hormones and SHBG using weighted linear regression models. Higher concentrations of total (slope per one quintile in concentration, -0.18; p-trend, 0.001) and calculated free (slope, -0.13; p-trend, 0.03) testosterone were statistically significantly associated with lower concentrations of CRP, but not with WBC count. Men in the bottom quintile of total testosterone (≤3.3 ng/mL), who might be considered to have clinically low testosterone, were more likely to have elevated CRP (≥3 mg/L) compared with men in the top four quintiles (OR, 1.61; 95% CI, 1.00-2.61). Total and calculated free estradiol (E2) were positively associated with both CRP (Total E2: slope, 0.14; p-trend, <0.001; Free E2: slope, 0.15; p-trend, <0.001) and WBC (Total E2: slope, 0.02; p-trend, 0.08; Free E2: slope, 0.02; p-trend, 0.02) concentrations. SHBG concentrations were inversely associated with WBC count (slope, -0.03; p-trend, 0.04), but not with CRP. These cross-sectional findings are consistent with the hypothesis that higher androgen and lower oestrogen concentrations may have an anti-inflammatory effect in men.

Trends in sex hormone concentrations in US males: 1988-1991 to 1999-2004.

Previous studies suggest that male testosterone concentrations have declined over time. To explore this in a large US population, we examined testosterone and free testosterone concentrations in National Health and Nutrition Examination Surveys (NHANES) from 1988-1991 and 1999-2004. We also examined sex hormone-binding globulin (SHBG), estradiol, and androstanediol glucuronide (3α-diol-G) over the same period. Non-Hispanic white, non-Hispanic black, and Mexican-American men from 1988-1991 and 1999-2004 NHANES surveys who were ≥20 years old and had serum from morning blood draws were included in this analysis (1988-1991: N = 1,413; 1999-2004: N = 902). Testosterone, estradiol and SHBG were measured by competitive electrochemiluminescence immunoassays and 3α-diol-G was measured by enzyme immunoassay. Free testosterone was calculated using testosterone and SHBG values. Adjusted mean hormone concentrations were estimated using linear regression, accounting for NHANES sampling weights and design, age, race/ethnicity, body mass index, waist circumference, alcohol use and smoking. Differences in adjusted mean concentrations (Δ) and two-sided p-values were calculated; p < 0.05 was statistically significant. Overall, 3α-diol-G and estradiol declined between 1988-1991 and 1999-2004, but there was little change in testosterone, free testosterone, or SHBG (Δ: 3α-diol-G = -1.83 ng/mL, p < 0.01; estradiol = -6.07 pg/mL, p < 0.01; testosterone = -0.03 ng/mL, p = 0.75; free testosterone = -0.001 ng/mL, p = 0.67; SHBG = -1.17 nmol/L, p = 0.19). Stratification by age and race revealed that SHBG and 3α-diol-G declined among whites 20-44 years old (Δ: SHBG = -5.14 nmol/L, p < 0.01; 3α-diol-G = -2.89 ng/mL, p < 0.01) and free testosterone increased among blacks 20-44 years old (Δ: 0.014 ng/mL, p = 0.03). Estradiol declined among all ages of whites and Mexican-Americans. In conclusion, there was no evidence for testosterone decline between 1988-1991 and 1999-2004 in the US general population. Subgroup analyses suggest that SHBG and 3α-diol-G declined in young white men, estradiol declined in white and Mexican-American men, and free testosterone increased in young black men. These changes may be related to the increasing prevalence of reproductive disorders in young men.

Coinfection with hepatitis C virus, oxidative stress and antioxidant status in HIV-positive drug users in Miami.

BACKGROUND: The pathogenesis of HIV/hepatitis C virus (HCV) coinfection is poorly understood. We examined markers of oxidative stress, plasma antioxidants and liver disease in HIV/HCV-coinfected and HIV-monoinfected adults. METHODS: Demographics, medical history, and proof of infection with HIV, hepatitis A virus (HAV), hepatitis B virus (HBV) and HCV were obtained. HIV viral load, CD4 cell count, complete blood count (CBC), complete metabolic panel, lipid profile, and plasma concentrations of zinc, selenium, and vitamins A and E were determined. Malondialdehyde (MDA) and glutathione peroxidase concentrations were obtained as measures of oxidative stress. Aminotransferase to platelet ratio index (APRI) and fibrosis index (FIB-4) markers were calculated. RESULTS: Significant differences were found between HIV/HCV-coinfected and HIV-monoinfected participants in levels of alanine aminotransferase (ALT) (mean±standard deviation: 51.4±50.6 vs. 31.9±43.1 U/L, respectively; P=0.014), aspartate aminotransferase (AST) (56.2±40.9 vs. 34.4±30.2 U/L; P<0.001), APRI (0.52±0.37 vs. 0.255±0.145; P=0.0001), FIB-4 (1.64±.0.91 vs. 1.03±0.11; P=0.0015) and plasma albumin (3.74±0.65 vs. 3.94±0.52 g/dL; P=0.038). There were no significant differences in CD4 cell count, HIV viral load or antiretroviral therapy (ART) between groups. Mean MDA was significantly higher (1.897±0.835 vs. 1.344± 0.223 nmol/mL, respectively; P=0.006) and plasma antioxidant concentrations were significantly lower [vitamin A, 39.5 ± 14.1 vs. 52.4±16.2 µg/dL, respectively (P=0.0004); vitamin E, 8.29±2.1 vs. 9.89±4.5 µg/mL (P=0.043); zinc, 0.61±0.14 vs. 0.67±0.15 mg/L (P=0.016)] in the HIV/HCV-coinfected participants than in the HIV-monoinfected participants, and these differences remained significant after adjusting for age, gender, CD4 cell count, HIV viral load, injecting drug use and race. There were no significant differences in glutathione peroxidase concentration, selenium concentration, body mass index (BMI), alcohol use or tobacco use between groups. Glutathione peroxidase concentration significantly increased as liver disease advanced, as measured by APRI (ß=0.00118; P=0.0082) and FIB-4 (ß=0.0029; P=0.0177). Vitamin A concentration significantly decreased (ß=-0.00581; P=0.0417) as APRI increased. CONCLUSION: HIV/HCV coinfection is associated with increased oxidative stress and decreased plasma antioxidant concentrations compared with HIV monoinfection. Research is needed to determine whether antioxidant supplementation delays liver disease in HIV/HCV coinfection.

Effects of testosterone therapy on cardiovascular risk markers in androgen-deficient women with hypopituitarism.

CONTEXT: Low-dose testosterone replacement therapy in women with relative androgen deficiency has been shown to have beneficial effects on body composition, bone mass, and psychosexual function. However, the safety of chronic testosterone administration on cardiovascular risk and insulin resistance is unknown. OBJECTIVE: The aim of the study was to determine the effects of physiological testosterone replacement on cardiovascular risk markers and insulin resistance in women. DESIGN: A 12-month, randomized, placebo-controlled study was conducted. SETTING: A General Clinical Research Center was the setting for the study. STUDY PARTICIPANTS: A total of 51 women of reproductive age with androgen deficiency due to hypopituitarism participated. INTERVENTION: Study participants were randomized to physiological testosterone administration, 300 mug daily, or placebo, by patch. MAIN OUTCOME MEASURES: We measured fasting glucose, fasting insulin, insulin-resistance homeostasis model of assessment (IRHOMA), quantitative insulin sensitivity check index (QUICKI), high-sensitivity C-reactive protein, vascular cell adhesion molecule (VCAM), leptin, lipoprotein (a), apolipoprotein A1, and homocysteine. RESULTS: At 12 months, fasting insulin and IRHOMA were significantly lower in the testosterone compared with the placebo group, and there was a trend toward a higher QUICKI level at 12 months in the testosterone compared with the placebo group. These differences were no longer significant after controlling for baseline levels. We observed no effect, either positive or negative, of testosterone administration on high-sensitivity C-reactive protein, VCAM leptin, lipoprotein (a), or apolipoprotein A1. CONCLUSIONS: Our data suggest that physiological testosterone replacement in women with hypopituitarism for 12 months does not increase, and may improve, insulin resistance. Chronic low-dose testosterone administration does not increase markers of cardiovascular disease reflecting several different mechanistic pathways. Large, randomized, placebo-controlled, long-term prospective studies are needed to determine whether low-dose testosterone replacement affects cardiovascular risk and event rates in women.

Simultaneous Cre catalyzed recombination of two alleles to restore neomycin sensitivity and facilitate homozygous mutations.

Cells homozygous for neo-expressing mutations can be derived by culturing heterozygotes with elevated G418. We demonstrate that this strategy is significantly less efficient if hyg is substituted for neo. Therefore, to introduce additional mutations Cre recombinase was used to remove floxed neo from both alleles of homozygotes at two different loci. The rate-determining step in Cre excision appeared independent of substrate copy number. Incorporating cytosine deaminase and Herpes simplex virus thymidine kinase allowed negative selection for both targeting and Cre excision. The resulting G418-sensitive homozygous mutants should allow mutagenesis at additional loci and avoid untoward effects of retained selection markers.

Aldosterone-producing adenomas do not contain glucocorticoid-remediable aldosteronism chimeric gene duplications.

In glucocorticoid-remediable aldosteronism (GRA) a chimeric gene has been described with the activity of aldosterone synthase, but the promoter of 11 beta-hydroxylase leading to ectopic expression of aldosterone synthase activity in the zona fasciculata. Similar to GRA, in aldosterone-producing adenomas (APA), the primary regulation of aldosterone production is ACTH, and there is increased production of the 18-oxygenated cortisol compounds, 18-oxocortisol and 18-hydroxycortisol. Because of these hormonal similarities, we tested whether a chimeric GRA-like gene was present in APA from 11 patients. A GRA-like chimeric gene was not found in the DNA from these tumors and, therefore, is not the mechanism responsible for hyperaldosteronism in APA.