Search results for "testosterone"
showing 10 items of 420 documents
The Interplay between Magnesium and Testosterone in Modulating Physical Function in Men
2014
The role of nutritional status as determinant of successful aging is very well recognized. There is recent evidence that nutrition may exert its beneficial effects through the modulation of the hormonal anabolic milieu. Under-nutrition and anabolic hormonal deficiency frequently coexist in older individuals determining an increased risk of mobility impairment and adverse outcomes. Mineral dietary assessment has received attention as key component of the nutritional modulation of anabolic status and physical performance. There is evidence that several minerals, including magnesium, exert a positive influence on Insulin-like Growth Factor-1 (IGF-1) secretion in both sexes, and Testosterone (T…
Relationship between heart rate variability and the serum testosterone-to-cortisol ratio during military service
2009
Abstract The autonomic nervous system and circulating hormones control a stress reaction through a complex interaction. We tested the hypothesis that changes in cardiac vagal regulation may be positively associated with the serum testosterone-to-cortisol ratio during the first week of military service in 24 conscripts aged 19.0±0.3 years. Cardiac autonomic function was assessed by measuring high-frequency (HF: 0.15–0.4 Hz) and low-frequency (LF: 0.04–0.15 Hz) power spectral indices of R-R intervals during supine rest and during a controlled standing condition (5 min for both) from the second to the seventh mornings at the beginning of military service. Blood samples were collected to analys…
Heart rate variability in prediction of individual adaptation to endurance training in recreational endurance runners
2011
The aim of this study was to investigate whether nocturnal heart rate variability (HRV) can be used to predict changes in endurance performance during 28 weeks of endurance training. The training was divided into 14 weeks of basic training (BTP) and 14 weeks of intensive training periods (ITP). Endurance performance characteristics, nocturnal HRV, and serum hormone concentrations were measured before and after both training periods in 28 recreational endurance runners. During the study peak treadmill running speed (Vpeak) improved by 7.5 � 4.5%. No changes were observed in HRV indices after BTP, but after ITP, these indices increased significantly (HFP: 1.9%, P 5 0.026; TP: 1.7%, P 5 0.007)…
Selective muscle hypertrophy, changes in EMG and force, and serum hormones during strength training in older women.
2001
Effects of strength training (ST) for 21 wk were examined in 10 older women (64 ± 3 yr). Electromyogram, maximal isometric force, one-repetition maximum strength, and rate of force development of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) and of vastus lateralis (VL), medialis (VM), intermedius (VI) and rectus femoris (RF) throughout the lengths of 3/12–12/15 (Lf) of the femur, muscle fiber proportion and areas of types I, IIa, and IIb of the VL were evaluated. Serum hormone concentrations of testosterone, growth hormone (GH), cortisol, and IGF-I were analyzed for the resting, preexercise, and postexercise conditions. After the 21-wk ST, maximal for…
Hormonal adaptations and modelled responses in elite weightlifters during 6 weeks of training.
1992
The concentrations of serum testosterone, sex-hormone-binding-globulin (SHBG) and luteinizing hormone (LH) were examined throughout 1-year of training in six elite weightlifters. A systems model, providing an estimation of fatigue and fitness, was applied to records of training volume and performance levels in clean and jerk. The analysis focused on a 6-week training period during which blood samples were taken at 2-week intervals. A 4-week period of intensive training (period I) could be distinguished from the following 2-week period of reduced training (period II). During period I, decreases in serum testosterone (P less than 0.05) and increases in serum LH concentrations (P less than 0.0…
The effects of transdermal testosterone and oestrogen therapy on dry eye in postmenopausal women: a randomised, placebo-controlled, pilot study
2016
Aims Sex hormones could provide a future treatment avenue for dry eye post menopause. However, there are few well-controlled studies. This study investigates the impact of testosterone and oestrogen on dry eye symptoms and signs in postmenopausal women. Methods A randomised double-blind placebo-controlled pilot study was conducted involving 40 women with dry eye (age 63.9±5.1 years, 13.2±6.3 years post menopause). Ten women were assigned to each of four treatment groups: transdermal testosterone, oestradiol, testosterone/oestradiol combination and placebo. Assessment at baseline and after 8 weeks: ocular symptoms, tear osmolarity, tear stability, tear secretion, meibomian gland assessment, …
Social control of testicular steroidogenic capacities in the Siamese fighting fishBetta splendens Regan
1987
Male Siamese fighting fish (Betta splendens Regan) of the veiltail variety were raised. At the age of 4 ½ months they were either isolated or community-housed for 2 ½ months. After that time the relative fin lengths were determined, and the in vitro metabolism of testosterone by the testes of the fishes was investigated. Community-housed specimens had shorter fins than the isolated males. Their testes formed less 11-oxy- and more 5β-steroids than those of the isolated males. This difference was even larger when high- and low-ranking community-based specimens were compared. The appearance of low-ranking males resembled that of females, and the main products of their testes were 5β-reduced st…
Product of aromatase activity in intact LNCaP and MCF-7 human cancer cells
1997
We investigated conversion rates of androgens to estrogens in cultured, hormone-responsive prostate (LNCaP) and breast (MCF-7) human cancer cells. For this purpose, we adopted an intact cell analysis, whereby cells were incubated for different incubation times in the presence of close-to-physiological (1 nM) or supraphysiological (1 μM) concentrations of labelled androgen precursors, i.e. testosterone (T) and androstenedione (Δ4Ad). The aromatase activity, as measured by estrogen formation, was detected in LNCaP cells (0.5 pmol/ml), even though to a significantly lower extent than in MCF-7 cells (5.4 pmol/ml), using 1 μM T after 72 h incubation. Surprisingly, LNCaP cells displayed a much hi…
Preliminary identification and quantification of steroid hormones in the red palm weevil, Rhynchophorus ferrugineus
2012
In the present preliminary study, we used a gas chromatography–mass spectroscopy (GC-MS) method to identify and quantify steroid hormones, their precursors and metabolites in whole body of red palm weevil (RPW) R. ferrugineus adults. We identified a total of seven steroids by single ion monitoring mode (SIM) analysis and compared them to the National Institute of Standards and Technology (NIST) library. The steroids include: dehydroepiandrosterone (DHEA), estrone, estradiol-17β, testosterone, progesterone, cortisol and cholesterol, whereas pregnenolone, pregnan-20-one-17-hydroxy and corticosterone were not detected. This study shows that some invertebrate groups seem to use partially or tot…
Quantitative Bestimmungen von Dehydroepiandrosteron, Androsteron, �tiocholanolon, Gesamtoestrogen und Testosteron im Plasma und Hauteluaten bei Acne …
1969
Bei acnekranken Mannern und Frauen sowie bei einer Kontrollgruppe wurden Dehydroepiandrosteron, Androsteron, Atiocholanolon und Oestrogene im Plasma und in Hauteluaten quantitativ bestimmt, im Hauteluat zusatzlich noch Testosteron.