Testosterone concentrations in human seminal plasma and saliva and its correlation with non-protein-bound and total testosterone levels in serum

The role of total antioxidant capacity and malondialdehyde of seminal plasma in the association between air pollution and sperm quality

Accumulating evidence has suggested that men exposed to air pollution are associated with decreased sperm quality, and seminal plasma plays a pivotal role in maintaining sperm viability. However, the role of seminal plasma in air pollution related sperm quality decline remain unestablished. In current study, we recruited 524 participants from couples who underwent in vitro fertilization treatment due to female factors at a fertility clinic in China from March to August 2020. Conventional sperm parameters, total antioxidant capacity (T-AOC), malondialdehyde (MDA) and testosterone were measured using semen samples. The six main air pollutants (PM2.5, PM10, NO2, SO2, CO, O3) during four key periods of sperm development (meiotic stage, spermiogenesis stage, epididymal stage and total sperm cycle period) were estimated using inverse distance weighting method. Multiple linear regression models were employed to investigate the exposure-outcome relationships. And we found that PM10 exposures were negatively related to sperm total motility and the exposures of PM2.5 and PM10 were inversely associated with sperm progressive motility during epididymal stage. Furthermore, PM2.5 and PM10 exposures were positively associated with seminal plasma MDA and PM10 was negatively related to seminal plasma T-AOC during epididymal stage. PM2.5, PM10 and CO exposures during total sperm cycle period might relate to increased seminal plasma testosterone. Mediation analysis indicated seminal plasma MDA and T-AOC partially mediated PM10 associated reduction of sperm motility during epididymal stage. Our study suggested MDA and T-AOC of seminal plasma played a role in air pollution associated decline of sperm motility.

An improved sample extraction method reveals that plasma receptor for advanced glycation end-products (RAGE) modulates circulating free oxytocin in mice

The receptor for advanced glycation end-products (RAGE) binds oxytocin (OT) and transports it from the blood to the brain. As RAGE's OT-binding capacity was lost in RAGE knockout (KO) mice, we predicted that circulating concentrations of unbound (free) OT should be elevated compared to wild-type (WT) mice. However, this hypothesis has not yet been investigated. Unfortunately, the evaluation of the dynamics of circulating free and bound plasma OT is unclear in immunoassays, in part because of interference from plasma proteins. A radioimmunoassay (RIA) is considered the gold standard method for overcoming this issue, but is more challenging to implement; thus, commercially available enzyme-linked immunosorbent assays (ELISAs) are more commonly used. Here, we developed a pre-treatment method to remove the interference-causing components from plasma before performing ELISA. The acetonitrile protein precipitation (PPT) approach was reliable, with fewer steps needed to measure free OT concentrations than by solid-phase extraction of plasma samples. PPT-extracted plasma samples yielded higher concentrations of OT in RAGE KO mice than in WT mice using ELISA. After peripheral OT injection, free OT plasma levels spiked immediately then rapidly declined in WT mice, but remained high in KO mice. These results suggest that plasma samples with PPT pre-treatment appear to be superior and that circulating soluble RAGE can most likely serve as a buffer for plasma OT, which indicates a novel physiological function of RAGE.

Alternative and promising targets of biochemical analysis in sport (review of literature)

Current literature review provides an evaluation of advantages and limitations of biochemical control objects representing functional state of athletes as well as the outlook for using alternative targets regarding sports medicine. Traditionally, invasive procedures (venous blood collection, muscle biopsy) have been known as the gold standard for analyzing a wide range of biomarkers which could be employed as effective diagnostic tools to control the course of adaptation processes, monitor performance, overtraining and physical well-being of athletes, but these techniques are painful, time-consuming and place demands on storage and shipment. In this behalf finding an alternative objects for biochemical research that does not have disadvantages given above is the question of present interest. Saliva and dry blood spots (DBS) could serve as equally informative and promising targets for monitoring athletes' condition. The non-invasive nature of saliva collection allows to shorten sample collection time, reduce stress hormones levels and possible infection contamination. Moreover, collecting saliva process does not require special equipment and trained medical staff which is particularly important when athletes are at training camps. The DBS method has successfully proven itself with regard to neonatal screening and pharmacokinetics studies. Its key benefits are simplicity, small volume of bioliquid, enhanced stability of adsorbed biomarkers on the card surface, lack of special storage and transportation requirements and low costs for samples shipment to the laboratory. Taken together outlined advantages will provide the opportunity to increase the frequency of biomaterial collection to perform selective observation of training loads effects on various systems of athletes' body. The combination of DBS with immunochemical and mass-spectrometric approaches could serve as an efficient instrument to investigate the role of various biomarkers in monitoring the functional state of athletes. We searched for articles in MedLine database with the key words «dry blood spots», «saliva», «sports medicine», «sample collection», «sports biochemistry».

Sex difference in the relationship between salivary testosterone and inter-temporal choice

Humans often prefer a small immediate reward to large reward in the future. This myopic tendency in inter-temporal choice is termed delay discounting, and has been the focus of intensive research in the past decades. Recent studies indicate that the neural regions underlying delay discounting are influenced by the gonadal steroids. However, the specific relationship between the testosterone levels and delay discounting is unclear at this point, especially in females. The present study investigated the relationship between salivary testosterone concentrations and discounting rates in delay- and probability-discounting tasks with healthy males and females. The results revealed a positive correlation between testosterone concentrations and delay-discounting rates in females and a negative correlation in males. Testosterone concentrations were unrelated to probability-discounting rates. Although causal effects of testosterone cannot be certain in this correlational study, if testosterone directly influenced this behavior, observed sex differences in delay discounting may be evidence of a curvilinear effect of testosterone. Alternatively, the findings may reflect inverse pattern of responsiveness to testosterone between male and female neural systems, or basic sex-difference in the neural mechanism underlying delay-discounting independent of testosterone itself.

Metabolomics of salivary fatigue markers in soccer players after consecutive games

Strenuous and consecutive exercise leads to fatigue symptoms in athletes. Metabolomics is a comprehensive method to assess metabolites that involves the measurements of the overall metabolic signature of biological samples. Using metabolomic analysis, we investigated the identification of salivary fatigue markers in soccer players after 3 consecutive days of a game program. One hundred twenty-two male soccer players participated in 3 consecutive days of a game program. To detect fatigued athletes, we measured indices of traditional fatigue symptoms, i.e., heart rate, body mass and mood, before and after the program. We detected 37 fatigued players throughout the program. Before and after the program, the saliva in these players was analyzed using capillary electrophoresis and time-of-flight mass spectrometry (CE-TOFMS) and a multivariate statistical technique, principal component analysis, was used to process the data. CE-TOFMS was used to identify 144 metabolites in the saliva of fatigued players. A significant metabolomic difference was observed before and after 3 consecutive days of a soccer game program. Interestingly, metabolites were all increased after the program (P < 0.001). The identified metabolites, including 3-methylhistidine, glucose 1- and 6-phosphate, taurine, and some amino acids, were involved in skeletal muscle catabolism, glucose metabolism, lipid metabolism, amino acid metabolism, and energy metabolism. Our work demonstrated some salivary metabolites were significantly increased in the fatigued players after consecutive days of short soccer matches. We propose that the detected salivary metabolites may be new fatigue markers in athletes.

Testosterone levels and androgen receptor gene polymorphism predict specific symptoms of depression in young men

BACKGROUND

Testosterone (T) has been hypothesized to modulate the expression of depressive symptoms in men; however, support for this proposition is mixed.

OBJECTIVE

To investigate bioavailable T, measured from saliva, and androgen receptor gene (AR) polymorphism (the number of glutamine [CAG] repeats in exon 1 of AR) and their relation to discrete symptoms of depression in 150 men aged 17 to 27 years who varied in mood status from depressed to nondepressed.

METHODS

Participants completed the Center for Epidemiologic Studies Depression Scale and the Patient Health Questionnaire-9. Principal components analysis of the scales identified 5 factors: Negative Affect, Social/Evaluative, Cognitive, Sleep, and Appetite.

RESULTS

Across the sample as a whole, higher ratings on sleep symptoms of depression were predicted by lower T concentrations and shorter CAG lengths. The association between T, CAG length, and sleep symptoms was confirmed among the subgroup of men who reported moderate to severe depression. In this subgroup, CAG repeats and T concentrations also emerged as significant predictors of negative affect scores, with the number of CAG repeats making the primary contribution.

CONCLUSIONS

These findings suggest that androgens may influence specific symptoms of depression in men.

Hand preference in humans is associated with testosterone levels and androgen receptor gene polymorphism

Exposure of the central nervous system to androgens during the early developmental period has been proposed to play a role in the establishment of hand preference in males. Existing data, however, are inconclusive. In the present investigation, handedness was assessed in a large sample of left-, mixed-, and right-handed men (N=180) using a standardized handedness inventory. Saliva sampling was used to assay levels of bioavailable testosterone and DNA genotyping was carried out to quantify AR-CAG repeat length, a genetic marker of the capacity of the androgen receptor to respond to testosterone. Strongly left-handed males were found to have lower levels of bioavailable testosterone than right-handed males, while males with mixed handedness exhibited a weaker androgen receptor, but no significant difference from right-handers in circulating testosterone levels. These findings support the view that testosterone could play a role in the development of hand preference in males. Furthermore, because the AR gene lies on the X chromosome, it provides a potential theoretical bridge to genetic theories of handedness that postulate the existence of an X-linked locus important in the establishment of hand preference.

Salivary testosterone concentrations in pubertal ICSI boys compared with spontaneously conceived boys

BACKGROUND To date, no data exist about Leydig cell function of pubertal boys born after ICSI. To evaluate a potential risk of gonadal dysfunction in children born from fathers with compromised fertility, testicular function was assessed by the measurement of salivary testosterone. METHODS Morning salivary testosterone levels at the age of 14 years were compared between 58 ICSI teenagers who are part of the oldest ICSI cohort, and 62 boys born after spontaneous conception (SC). RESULTS Salivary testosterone levels were comparable between ICSI (113 ± 42 pg/ml) and SC (123 ± 56 pg/ml) teenagers at the age of 14 years. In the ICSI group, testosterone levels in boys from fathers with severe oligozoospermia were not different from concentrations in boys from fathers without severe oligozoospermia (115.5 ± 43 and 109 ± 41 pg/ml, respectively). CONCLUSIONS At the age of 14 years, pubertal ICSI boys show testosterone levels comparable to their peers born after SC. ICSI adolescents fathered from men with severely compromised spermatogenesis show testosterone levels comparable to those from fathers with normal spermatogenesis. This notwithstanding, further follow-up of ICSI teenagers into adulthood is mandatory to confirm a normal gonadal function.

Salivary testosterone: a reliable approach to the diagnosis of male hypogonadism

OBJECTIVE

This study was to demonstrate that Sal-T is a reliable biomarker of androgen status in the diagnosis of male hypogonadism.

DESIGN

In order to validate the salivary testosterone assay (Sal-T), its reproducibility, the agreement with serum free testosterone levels (Free-T), the correlation with other circulating androgen markers (bioavailable testosterone, total testosterone) and cut-off values were defined.

PATIENTS AND METHODS

We studied 52 eugonadic (E) and 20 hypogonadic (Hy) men. Sal-T was assayed using an adapted radioimmunoassay for serum testosterone. Sal-T concentrations were compared in nine cases before and after citric acid stimulation of salivary flow rate. Free-T and bioavailable testosterone (Bio-T) were calculated by Vermeulen equation and SHBG were determined by binding assay.

RESULTS

Sal-T did not depend on salivary flow rate and morning samples from 07.00 h to 09.00 h were stable. Agreement between Sal-T and Free-T measurements was confirmed in all subjects. Sal-T levels correlated positively with all circulating androgens, showing the best correlation with Free-T in E (r = 0.92) as well as in Hy (r = 0.97). A cut-off value of Sal-T < or = 0.195 nm showed 100% sensibility and specificity to rule out hypogonadism.

CONCLUSIONS

Our data showed that Sal-T is a reliable marker of testosterone bioavailability. The results support the inclusion of this biomarker as a noninvasive approach in the diagnosis of male androgen deficiency.

Cortisol moderates the relationship between testosterone and aggression in delinquent male adolescents

BACKGROUND

In animals, strong evidence exists for an association between testosterone and aggression. In humans, and particularly in children and adolescents, findings have been less consistent. Previous research has suggested that this may partly be due to moderating effects of other factors, e.g., hormones. This study aims to investigate the moderating effect of cortisol on the relationship between testosterone and subtypes of aggression in delinquent male adolescents.

METHODS

Participants were 103 boys (mean age 13.7) referred to a delinquency diversion program. Testosterone and cortisol levels were determined from saliva samples collected during resting conditions and related to self-report scores on overt and covert aggression.

RESULTS

Linear regression analyses revealed a significant interaction between cortisol and testosterone in relation to overt aggression, with a significant positive relationship between testosterone and overt aggression in subjects with low cortisol levels but not in subjects with high cortisol levels. Using the same model for covert aggression, no significant effects of testosterone, cortisol, or testosterone x cortisol interaction were found.

CONCLUSIONS

These results indicate a moderating effect of cortisol on the relationship between testosterone and overt aggression in delinquent male adolescents. Implications and directions for future research are discussed.

Possible Stimuli for Strength and Power Adaptation

The endocrine system plays an important role in strength and power development by mediating the remodelling of muscle protein. Resistance training scheme design regulates muscle protein turnover by modifying the anabolic (testosterone, growth hormone) and catabolic (cortisol) responses to a workout. Although resistance exercise increases the concentrations of insulin-like growth factor 1 in blood following exercise, the effect of scheme design is less clear, most likely due to the different release mechanisms of this growth factor (liver vs muscle). Insulin is non-responsive to the exercise stimulus, but in the presence of appropriate nutritional intake, elevated blood insulin levels combined with resistance exercise promotes protein anabolism. Factors such as sex, age, training status and nutrition also impact upon the acute hormonal environment and, hence, the adaptive response to resistance training. However, gaps within research, as well as inconsistent findings, limit our understanding of the endocrine contribution to adaptation. Research interpretation is also difficult due to problems with experimental design (e.g. sampling errors) and various other issues (e.g. hormone rhythms, biological fluid examined). In addition to the hormonal responses to resistance exercise, the contribution of other acute training factors, particularly those relating to the mechanical stimulus (e.g. forces, work, time under tension) must also be appreciated. Enhancing our understanding in these areas would also improve the prescription of resistance training for stimulating strength and power adaptation.

Testosterone and child and adolescent adjustment: the moderating role of parent-child relationships

In a sample of established middle- and working-class families with normally developing children and adolescents ranging in age from 6 to 18 years, sons' and daughters' testosterone levels showed little direct connection to risk behavior or symptoms of depression. In contrast, testosterone's positive relation with risk behavior and negative relation with depression were conditional on the quality of parent-child relations. As parent-child relationship quality increased, testosterone-related adjustment problems were less evident. When relationship quality decreased, testosterone-linked risk-taking behavior and symptoms of depression were more in evidence. Few relations were found between parents' testosterone and child behavior. Boys' and girls' ages and stages of pubertal development were important for understanding the expression of hormone-related problem behavior in some cases but not in others.

Testosterone, sexuality and antisocial personality in rapists and child molesters: a pilot study

Morning and afternoon levels of saliva testosterone levels in Finnish imprisoned rapists (n = 10) and child molesters (n = 10) were compared to those in randomly selected control subjects (n = 31). The associations of saliva testosterone with sexual behavior and antisocial personality traits were explored in all groups. The sexual offenders and control subjects did not differ in the between-subjects main effect estimated for the averaged morning and afternoon testosterone levels. Seven rapists and three child molesters met the criteria for antisocial personality disorder (ASP). In the sexual offenders, a summed ASP index was positively correlated with mean saliva testosterone. Sexual activity as estimated from self-reports of sexual intercourse and masturbation was significantly related to testosterone in both rapists and child molesters but not in the control males. The implications of these results are discussed.

Testosterone is correlated with regional morphology of the human corpus callosum

Theoretical speculation in humans (S.F. Witelson, Psychoneuroendocrinology 16 (1991) 131-153) and empirical findings in animals (R.H. Fitch, P.E. Cowell, L.M. Schrott, V.H. Denenberg, Int. J. Dev. Neurosci. 9 (1991) 35-38) suggest that testosterone (T) may play a significant role in the development of the corpus callosum (CC). However, there are currently no empirical studies directly relating T concentrations to callosal morphology in humans. The purpose of the present study was to investigate the relationship between free T concentrations as determined by radioimmunoassay, and the mid-sagittal area of the corpus callosum, as determined by magnetic resonance imaging (MRI). Subjects were 68 young adult (20-35 years), neurologically normal, right-handed males. All subjects underwent MRI and provided two samples of saliva for radioimmunoassay of T and cortisol. Anatomical regions of interest included total brain volume, left and right hemisphere volume and regional areas of the CC. CC regions were defined using two different measurement techniques, each dividing the CC into six sub-sections. Anatomical measurements were performed blind with respect to the hormone levels of subjects. A significant positive correlation between T concentration and cross-sectional area of the posterior body of the CC was found. This finding was consistent across the two measurement techniques and was not attributable to individual differences in total brain volume. All correlations between cortisol and CC sub-regions were non-significant. The results of this study are consistent with the notion that T, at an earlier stage in development, may play a significant role in modulating cortical/callosal architecture in humans.

Hormone measures in finger-prick blood spot samples: new field methods for reproductive endocrinology

Comparative endocrine studies have notably advanced understanding of ecological factors that contribute to variation in human reproductive function. Such research has relied on methodological advances that permit hormone determinations in samples that are easily and safely collected, stored, and transported, most recently on measurement of steroids in saliva. This report seeks to further expand the scope of endocrine research by demonstrating the value of blood spot samples collected by finger prick. As a sampling strategy, finger-prick blood spot collection offers the advantages of short collection time, low invasiveness, repeatability, absence of postcollection processing, low biohazard risk, and ease of sample storage and transport. We document good sample stability and present sensitive assay methods for a range of steroids and proteins (FSH, LH, PRL, T, E2, DHEAS, androstenedione, cortisol, SHGB) in blood spots that require sample volumes of 3-12 microliters and display good reliability, specificity, precision, accuracy, and convertibility of results to plasma/serum equivalent concentrations. Laboratory evaluation was augmented by a feasibility study at a remote site in Papua New Guinea that confirmed validity and stability of blood spot collections under field conditions. Research applications of blood spot sampling are illustrated with a series of studies, including cross-sectional surveys for developmental and life span endocrinology, a longitudinal, population-based developmental epidemiologic study of puberty, and serial sampling in a dynamic study of neuroendocrine response to suckling. We conclude that the sampling features and wide range of measurable biomolecules of blood spots do constitute a methodological advance for endocrine research.

CSF testosterone and 5-HIAA correlate with different types of aggressive behaviors

We studied the potential roles of testosterone and serotonin in various forms of aggressive and violent behaviors by measuring each biochemical and behaviour in free-ranging adolescent male nonhuman primates. Our results showed that (1) CSF free testosterone concentrations were positively correlated with overall aggressiveness, but not with measures of impulsivity. (2) CSF 5-HIAA concentrations were negatively correlated with impulsive behavior, and severe, unrestrained aggression, but not with overall rates of aggression. High rates of impulsive behavior were positively correlated with severe, unrestrained aggression, but not overall rates of aggression. (3) Dimensional analyses showed that while subjects with low CSF 5-HIAA exhibited high rates of aggression, high CSF testosterone further augmented rates and intensity of aggression in subjects with low CSF 5-HIAA. We conclude that high CSF free testosterone concentrations are associated with competitive aggression, while low CSF 5-HIAA concentrations are associated with severe aggression which results from impaired impulse control, and perseverance.

Ratios of plasma and salivary testosterone throughout puberty: production versus bioavailability

Because diffusion of testosterone (T) into the salivary gland is thought to be largely limited to the free, biologically active fraction, salivary testosterone is expected to provide a better measure of testosterone bioavailability in the body than is plasma testosterone. Matched saliva and blood spot samples were collected from 218 Zimbabwean males (age 11-23) who were at different stages of puberty, as assessed by self-reported Tanner genital stage ratings. Testosterone concentrations in these matched samples were highly correlated (r = 0.83). Both salivary and plasma testosterone (converted from blood spot value) showed expected significant increases across puberty. However, plasma testosterone distinguished among subjects at different stages of genital development more effectively than did salivary testosterone, suggesting the former to be a better marker of testosterone bioavailability. Sex hormone-binding globulin (SHBG) levels were also measured in a subgroup of 93 of these subjects. After controlling for plasma T concentrations, we found a small but significant inverse correlation between blood spot SHBG levels and the proportion of plasma testosterone recovered in salvia, supporting the hypothesis that SHBG-related changes in T bioavailability are detectable in saliva. We conclude that salivary testosterone accurately reflects testicular production of testosterone, but that neither salivary testosterone nor plasma testosterone is clearly superior to the other as a measure of testosterone bioavailability.

Salivary testosterone levels in left- and right-handed adults

It has been proposed that prenatal testosterone (T) may contribute to the development of hand preference and cerebral functional asymmetry in humans. To investigate any persisting association between T and asymmetry in adulthood, left-handed (LH) and right-handed (RH) men and women were administered a hand preference questionnaire and the Fused Dichotic Words Test. Testosterone was measured in samples of saliva. Results showed that LH subjects of both sexes had lower salivary T concentrations than their RH counterparts. Among LH males, subjects with a right-ear advantage in dichotic listening tended to have lower T concentrations than subjects with a left-ear advantage. These results are consistent with the notion that T may be involved in the development of hand preference and cerebral functional asymmetry.

Congenital anorchism: diagnostic and therapeutic aspects

Eight patients with congenital anorchism were examined and treated. Plasma LH, FSH, and testosterone concentrations and the saliva testosterone level were measured by RIA in 3 patients. The results showed a 2.75 times increase in LH level, a 1.66 times increase in FSH level, and hardly measurable serum and saliva testosterone amounts. A dynamic provocating test was applied in 4 patients by Pregnyl (2000 and 4000 IU) and the results showed absence of the gonads. The semen quality control manifested a low volume of ejaculate and aspermia. Scyntiscanning of 6 patients demonstrated no functional testicular parenchyma. Substitute androgen therapy in patients with diagnosed anorchism gave good results, which suggests that this treatment is appropriate and promising. Implantation of testiculo-prostheses by using silicon alloplastic material corrects the cosmetic defect and overcomes the physiological barrier caused by the biological inferiority complex.

Steroid assays in saliva: a method to detect plasmatic contaminations

Plasmatic and salivary levels of six steroid hormones in adult males and females are given and compared to the data of the literature. These steroids are: cortisol (F), dehydroepiandrosterone (DHA) and its sulphate (DHAS), androstenedione (A), testosterone (T) and 11 beta OH androstenedione (OHA). The salivary assay of the last compound is an original. The correlations between salivary and plasmatic values are presented and confirm that this method is a reliable alternative for hormonal investigations. From these data and from those of the literature, the salivary versus plasmatic ratio are calculated. From the fact that high concentrations of DHAS in saliva generally stem from blood contamination, we derive a method to estimate the amount of this contamination and its impact on other steroids measured on the same saliva sample.

Changes in the characteristics of anaerobic exercise in the upper limb during puberty in boys

The aim of this study was to examine the relationships between the characteristics of anaerobic exercise in the upper limb and important indicators of growth and developmental age such as height (h), body mass (mb), skeletal age (SA), plasma testosterone (T) and pubertal stage (PS). We used the force-velocity (F-v) relationship test in a population of 66 healthy adolescent male junior jockeys, with considerable variation in these indicators but of the same physical fitness level (training effect). The mean values of the maximal anaerobic power (Wan,max) were 391 (SD 93) W. The values of the variables in the F-v relationship for the upper limb were only slightly or uncorrelated with the chronological age, but highly correlated with h, mb and SA (P < 0.001). The correlation with T was less significant. Using ANOVA a highly significant effect of PS on the variables in the F-v relationship was found (P < 0.001). The absolute or relative (normalized to mb) increase in Wan,max during puberty was greater from PS P2 and P3 than at other stages. Therefore PS would appear to be a significant factor for developmental changes in anaerobic characteristics during puberty in the adolescent. The PS P3 determined only by public hair might be an easy and accurate indicator for sports category classification of adolescents during puberty.

Analysis of performance of prepubertal swimmers assessed from anthropometric and bio-energetic characteristics

The relationship between anthropometric and bio-energetic data and timed performance over 50 to 400 m was studied in 25 young male swimmers [11.3 (SD 1) years]. Anthropometric measurements included height, body mass, body fat mass, body area, thoracic section area (Ats) thoracic circumferences, lengths of upper limb, bi-acromial and bi-iliac diameters. Maximal oxygen consumption (VO2max; direct method), maximal anaerobic power (W(an),max; force-velocity test) and mean power in 30 s sprint (W30 s; Wingate test) were also measured. Each of these bio-energetic variables was expressed in absolute terms, relating to body mass, body area and Ats. The stepwise regression method was used to determine contribution of the variables (anthropometric and/or bio-energetic) of the time achieved over the distance. The W30 s/Ats accounted for 46% of the time over 50 m (negative correlation). The VO2max/Ats and height were negatively correlated with the times of performances over 100 m, 200 m and 400 m, these two variables accounted for 71% to 77% of the performance. These results would indicate that even in young boys, anthropometric and bio-energetic characteristics are both important in swimming performance, particularly the bio-energetic variables expressed per Ats.

Bio-energetic profile in 144 boys aged from 6 to 15 years with special reference to sexual maturation

The effects of growth and pubertal development on bio-energetic characteristics were studied in boys aged 6-15 years (n = 144; transverse study). Maximal oxygen consumption (VO2max, direct method), mechanical power at VO2max (PVO2max), maximal anaerobic power (Pmax; force-velocity test), mean power in 30-s sprint (P30s; Wingate test) were evaluated and the ratios between Pmax, P30s and PVO2max were calculated. Sexual maturation was determined using salivary testosterone as an objective indicator. Normalized for body mass VO2max remained constant from 6 to 15 years (49 ml.min-1.kg-1, SD 6), whilst Pmax and P30s increased from 6-8 to 14-15 years, from 6.2 W.kg-1, SD 1.1 to 10.8 W.kg-1, SD 1.4 and from 4.7 W.kg-1, SD 1.0 to 7.6 W.kg-1, SD 1.0, respectively, (P less than 0.001). The ratio Pmax:PVO2max was 1.7 SD 3.0 at 6-8 years and reached 2.8 SD 0.5 at 14-15 years and the ratio P30s:PVO2max changed similarly from 1.3 SD 0.3 to 1.9 SD 0.3. In contrast, the ratio Pmax:P30s remained unchanged (1.4 SD 0.2). Significant relationships (P less than 0.001) were observed between Pmax (W.kg-1), P30s (W.kg-1), blood lactate concentrations after the Wingate test, and age, height, mass and salivary testosterone concentration. This indicates that growth and maturation have together an important role in the development of anaerobic metabolism.

Free testosterone levels in plasma and saliva as determined by a direct solid-phase radioimmunoassay: a critical evaluation

We compared unbound (free) testosterone radioimmunoassay concentrations in plasma and saliva from men, using a direct radioimmunoassay kit involving a ligand analog of testosterone as tracer. The assay failed to reveal detectable testosterone concentrations in saliva. In plasma the free testosterone levels were about 4 times lower than those obtained by calculation or ultrafiltration methods. Moreover, unexpected similar free testosterone levels were obtained in samples comparable in their total testosterone content but distinct in their steroid binding protein content (buffered testosterone dilutions). We suspect that free testosterone levels determined with this direct radioimmunoassay probably do not reflect the true free testosterone values and conclude that their significance remains to be established.

Salivary testosterone levels and the progress of puberty in the normal boy

Salivary testosterone (ST) levels were measured in 84 boys aged 7.3-16.2 from the Edinburgh Growth Study. The correlation coefficient between matched plasma/saliva samples was 0.88. Six samples were collected over the course of one day from 0900 to 2100 h each month in the majority of the children for 4 consecutive months. Mean daily ST levels showed a significant rise between each pubertal stage (genital (G) and pubic hair (PH]. The rise in ST became more rapid once a mean testicular volume (MTV) of 10 ml had been reached. The diurnal rhythm was assessed by individual curve fitting on the log scale and by cosinor analysis. A rhythm was present prepubertally and developed into a pattern similar to that of the adult rhythm by stage G3. The monthly rate of rise of ST was greatest at stage G4. A significant rise in ST levels was detectable immediately prior to an increase in MTV to 3 ml. This allowed earlier recognition of the clinical onset of puberty at testicular volume of 3 ml, which in this group occurred at 10.9 (SD 0.9) years. ST is a non-invasive and sensitive method for the serial monitoring of gonadal function in the prepubertal and adolescent boy.

Salivary testosterone levels in infertile men

Salivary testosterone levels were measured in 18 normal men, 29 oligospermic and six azoospermic subjects, using a specific and sensitive radioimmunoassay (RIA). There was a significant reduction (P less than 0.001) in salivary testosterone levels in the group of oligospermic (0.266 +/- 0.086 nmol/l) and azoospermic (0.234 +/- 0.055 nmol/l) subjects when compared with controls (0.348 +/- 0.070 nmol/l). A good correlation was found between salivary and plasma testosterone levels in normal (r = 0.62, P less than 0.01) and infertile men (r = 0.58, P less than 0.01). This study demonstrates that salivary testosterone levels, a non-invasive means of sample collection, may be used for evaluation of androgen status in male infertility.

A symmetric dialysis method for the determination of free testosterone in human plasma

We describe a symmetric dialysis (SYD) method for the determination of the fraction (fT), and the concentration (FT) of non-protein-bound testosterone (T) in human plasma. In SYD fT is estimated from the rate at which radiolabelled testosterone redistributes between two identical (undiluted) plasma aliquots separated by a dialysis membrane. We compared the effect of tracer contamination and sample dilution on FT as measured by SYD and equilibrium dialysis (EQD) in five plasma pools differing in Sex Hormone Binding Globulin (SHBG) and total T concentration. In addition, FT was calculated by computer simulation of the interaction between binding proteins and steroid hormones. With SYD relatively small decreases in FT were observed following two- to tenfold dilution (14.3 +/- 4.4%). A comparable decrease was calculated by computer simulation (13.3 +/- 2.2%). The apparent fall in FT as estimated by EQD was much larger (44.7 +/- 2.2%) and, contrary to assessment by SYD, this fall depended on the radiochemical purity of the 3HT-tracer. Moreover, since SYD allows the assessment of fT in undiluted samples, problems relating to the interference of buffer components with T-binding are circumvented. We conclude that SYD is to be preferred over EQD for the accurate and precise measurement of fT and consequently FT.

Comparison of saliva and plasma 17-hydroxyprogesterone time-course response to hCG administration in normal men

17-Hydroxyprogesterone (17-OHP) time-course response to hCG (5000 IU) was studied simultaneously in the saliva and the plasma of 12 adult healthy men. Baseline levels in plasma and saliva were: 1.0 +/- 0.1 ng/ml (mean +/- SEM) and 24 +/- 2 pg/ml respectively. After hCG, a biphasic pattern was observed in both fluids with a similar early response but the peak elicited at 33 h in plasma was not observed in saliva where the levels were lower than those recorded at 24 h. Since saliva steroids are believed to reflect the plasma non-protein bound fraction, this difference was assumed to be due to the decrease of the unbound fraction of plasma 17-OHP in the late afternoon as a consequence of the increase of CBG-bound fraction since at that time cortisol levels are low. The ratio of saliva to plasma 17-OHP levels was significantly correlated with plasma cortisol levels: r = 0.44 (P less than 0.01; n = 140). However the similar response in saliva at 24 and at 48 h after hCG allows the evaluation of the endocrine testicular function using saliva instead of plasma.

Saliva testosterone time-course response to hCG in adult normal men. Comparison with plasma levels

Testosterone time-course response to 5000 IU hCG was studied simultaneously in the saliva and the plasma of 13 adult normal men. Baseline levels in saliva and plasma were: 93 +/- 9 pg/ml (mean +/- SEM) and 4.9 +/- 0.3 ng/ml respectively. After hCG the same biphasic pattern was observed in both fluids with a similar early response but the delayed peak at 72 h was relatively higher in saliva than in plasma. Thus it was suggested to collect saliva instead of plasma for the evaluation of testicular secretion of testosterone after hCG administration.

Hormones in saliva

Since the collection of saliva is noninvasive, nonstressful and usually very convenient there have been many recent studies examining the clinical relevance of measuring various hormones in saliva. It now appears that the measurement of most unconjugated steroids in saliva will provide clinically useful data whereas the measurement of conjugated steroids, thyroid hormones, and protein hormones is unlikely to be clinically relevant. The key factors determining whether the salivary concentration of a hormone or drug is likely to be clinically relevant are the mechanisms by which the material enters the saliva; the "free to protein bound" ratio for the material; and the structure of the material, i.e., its molecular weight, polarity and the presence of ionizable groups.

Comparisons of the intra- and inter-individual variability in sex hormone levels of men

Six blood samples were taken from each of 33 healthy young men during the course of 2 weeks. From these, the testosterone, dihydrotestosterone, and oestradiol levels were determined. In addition, free testosterone was measured using saliva samples obtained from 23 of the subjects. Both coefficients of variation and variance analyses showed that the inter-individual variability is greater than the intra-individual for all of the hormones. No influence of the day of the week could be ascertained. However, it was discovered that the serum hormone levels dropped with age (weakly significant for oestradiol, insignificant for the androgens) in spite of the subjects being in or near their third decade. The pooled intra-individual correlations between the hormones all fell within the moderate to middle-high positive domain, whereas the inter-individual correlations ranged between highly positive (testosterone to dihydrotestosterone), middle highly positive (free testosterone to total testosterone), and slightly negative (free testosterone to oestradiol).

Direct radioimmunoassay (RIA) of salivary testosterone: correlation with free and total serum testosterone

Simple and sensitive direct RIA for determination of salivary testosterone was developed by using RSL NOSOLVEX TM (125 1) kit produced by Radioassay System Laboratories (Carson, California). In addition, a relationship between salivary and serum free and total testosterone concentrations was studied in randomly selected 45 healthy subjects, 5 females on oral contraceptive pills and 28 hypertensive patients on various treatment regimens. The lowest weight of testosterone detectable by our modified method was equivalent to 1 pg/ml of saliva, taking into account analytical variability. Intra- and interassay coefficients of variation were 5.09 +/- 2.7% and 8.2 +/- 5.9% respectively. Statistically significant correlations were found between salivary and serum free testosterone (r = 0.97) and salivary and serum total testosterone concentrations (r = 0.70-0.87). The exception to this was a group of hypertensive females in which no correlation (r = 0.14) between salivary and total serum testosterone was found. It is also of interest that, while salivary testosterone was significantly increased in subjects taking oral contraceptives and most of the hypertensive patients the total serum testosterone concentration was in normal range. Our findings suggest that determination of salivary testosterone is a reliable method to detect changes in the concentration of available biologically active hormone in the circulation.