Assessment of exercise-induced stress via automated measurement of salivary cortisol concentrations and the testosterone-to-cortisol ratio: a preliminary study.

In this study, our aim was to validate whether the automated measurement of salivary testosterone and cortisol concentrations and the testosterone-to-cortisol (T/C) ratio, considering their individual circadian rhythms can be used to assess the stress response of male athletes to different exercise intensities accurately and effectively. We measured the salivary testosterone and cortisol concentrations and their respective serum concentrations that were collected from 20 male long-distance runners via passive drooling in the morning and evening for two consecutive days involving different exercise intensities. An electrochemiluminescence immunoassay was performed to evaluate the salivary testosterone and cortisol concentrations. The results showed a positive correlation between the salivary testosterone and cortisol concentrations and their respective serum concentrations. The participants were divided into two groups: with and without interval training. The interval training group showed a significantly higher rate of change in the salivary cortisol concentration and a significantly lower rate of change in the T/C ratio in the evening interval training on day 1 than lower-intensity running on day 2. Our results indicated that the salivary cortisol concentrations and the T/C ratio could distinguish between exercises at different intensities, which may be beneficial for detecting differences in stress responses among athletes.

Age-Related Sex Differences in Glucose Tolerance by 75 g Oral Glucose Tolerance Test in Japanese.

To elucidate the age-related sex difference in glucose tolerance, we conducted 75 g oral glucose tolerance tests in 1156 participants. Participants were divided into four groups, namely, young (22−29) males, young females, middle-aged (>50) males, and middle-aged females. According to the Japanese Clinical Practice Guideline for Diabetes 2019, the prevalence of normal glucose tolerance (NGT) was significantly lower in middle-aged than in young participants. The prevalence of high-normal fasting plasma glucose (FPG) was higher, and NGT was lower in young males (high-normal FPG 15.2%, NGT 82.0%) than young females (high-FPG 3.9%, NGT 94.3%). Combined glucose intolerance (CGI) was higher and NGT was lower in middle-aged males (CGI 10.2%, NGT 25.2%) than in middle-aged females (CGI 3.3%, NGT 39.8%). FPG and body mass index (BMI) were the lowest and Homeostatic model assessment beta cell function (HOMA-ß) was the highest in young females, followed by young males, middle-aged females, and middle-aged males. Multiple linear regression analysis revealed that BMI weakly correlated with HOMA-ß and Matsuda index in all subjects except young females. The superior glucose tolerance in females was apparent in young, but attenuated in middle-aged females. The differences are due to the higher insulin secretion potential and lower BMI in young females.

Significance of serum branched-chain amino acid to tyrosine ratio measurement in athletes with high skeletal muscle mass.

BACKGROUND: Few nutritional markers reflect the hypermetabolic state of athletes with high levels of skeletal muscle. Although branched-chain amino acids (BCAA) play crucial roles in protein metabolism in skeletal muscle, the relationship between skeletal muscle mass and amino acid imbalances caused by the metabolism of BCAA and aromatic amino acids remains unclear. The aim of this study is to test the hypothesis that athletes with high levels of skeletal muscle mass have plasma amino acid imbalances, assessed by serum BCAA to tyrosine ratio (BTR) which can be measured conveniently. METHODS: The study enrolled 111 young Japanese men: 70 wrestling athletes and 41 controls. None of them were under any medications, extreme dietary restrictions or intense exercise regimens. Each participant's body composition, serum concentrations of albumin and rapid turnover proteins including transthyretin and transferrin, BTR, and thyroid function were assessed. RESULTS: Compared to the controls, the athletes had significantly higher skeletal muscle index (SMI) (p < 0.001), and lower serum albumin concentration (p < 0.001) and BTR (p < 0.001). Kruskal-Wallis tests showed that serum albumin concentration and BTR were significantly lower in the participants with higher SMI. Serum albumin concentration and BTR were inversely correlated with SMI by multiple regression analysis (logarithmic albumin, ß = - 0.358, p < 0.001; BTR, ß = - 0.299, p = 0.001). SMI was inversely and transthyretin was positively correlated with serum albumin (SMI, ß = - 0.554, p < 0.001; transthyretin, ß = 0.379, p < 0.001). Serum concentration of free 3,5,3'-triiodothyronine (FT3) was inversely correlated with BTR, and, along with SMI and albumin, was independent predictor of BTR (SMI, ß = - 0.321, p < 0.001; FT3, ß = - 0.253, p = 0.001; logarithmic albumin, ß = 0.261, p = 0.003). However, FT3 was not correlated with SMI or serum albumin. Serum concentrations of rapid turnover proteins were not correlated with BTR. CONCLUSIONS: Increased skeletal muscle mass enhances the circulating amino acid imbalances, and is independently facilitated by thyroid hormones. Serum BTR may be a useful biomarker to assess the hypermetabolic state of wrestling athletes with high levels of skeletal muscle.

Assessment of exercise-induced stress by automated measurement of salivary cortisol concentrations within the circadian rhythm in Japanese female long-distance runners.

BACKGROUND: Overtraining syndrome, caused by prolonged excessive stress, results in reduced performance and cortisol responsiveness in athletes. It is necessary to collect saliva samples sequentially within circadian rhythm for assessing exercise stress by measuring cortisol concentrations, and automated cortisol measurements using electrochemiluminescence immunoassay (ECLIA) may be useful for measuring a large number of saliva samples. In this study, we evaluated the appropriate use of cortisol-based exercise stress assessment within the circadian rhythm, which may diagnose and prevent overtraining syndrome in athletes. METHODS: We collected saliva and sera from 54 healthy participants and analyzed the correlation between salivary cortisol concentrations measured by ECLIA and enzyme-linked immunosorbent assay (ELISA) or serum cortisol analysis. We also collected saliva continuously from 12 female long-distance runners on 2 consecutive days involving different intensities and types of exercise early in the morning and in the afternoon and measured salivary cortisol concentrations using ECLIA. Each exercise intensity of runners was measured by running velocities, Borg Scale score, and rate of change in the pulse rate by exercise. RESULTS: ECLIA-based salivary cortisol concentrations correlated positively with those detected by ELISA (ρ = 0.924, p < 0.001) and serum cortisol (ρ = 0.591, p = 0.001). In long-distance runners, circadian rhythm of salivary cortisol, including the peak after waking and the decrease promptly thereafter, were detected on both days by continuous saliva sampling. The rates of change in salivary cortisol concentrations were significantly lower after an early morning exercise than after an afternoon exercise on both days (day 1, p = 0.002, and day 2, p = 0.003). In the early morning exercise, the rate of change in salivary cortisol concentration was significantly higher on day 1 than on day 2 (p = 0.034), similar to a significant difference in running velocities (p = 0.001). CONCLUSIONS: Our results suggest that automated ECLIA-based salivary cortisol measurements are able to detect the athletes' circadian rhythm and compare the exercise stress intensities at the same times on different days, even in the early morning, possibly leading to the prevention of overtraining syndrome.

Association between skeletal muscle mass and serum concentrations of lipoprotein lipase, GPIHBP1, and hepatic triglyceride lipase in young Japanese men.

BACKGROUND: Two important regulators for circulating lipid metabolisms are lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL). In relation to this, glycosylphosphatidylinositol anchored high-density lipoprotein binding protein 1 (GPIHBP1) has been shown to have a vital role in LPL lipolytic processing. However, the relationships between skeletal muscle mass and lipid metabolism, including LPL, GPIHBP1, and HTGL, remain to be elucidated. Demonstration of these relationships may lead to clarification of the metabolic dysfunctions caused by sarcopenia. In this study, these relationships were investigated in young Japanese men who had no age-related factors; participants included wrestling athletes with abundant skeletal muscle. METHODS: A total of 111 young Japanese men who were not taking medications were enrolled; 70 wrestling athletes and 41 control students were included. The participants' body compositions, serum concentrations of lipoprotein, LPL, GPIHBP1 and HTGL and thyroid function test results were determined under conditions of no extreme dietary restrictions and exercises. RESULTS: Compared with the control participants, wrestling athletes had significantly higher skeletal muscle index (SMI) (p < 0.001), higher serum concentrations of LPL (p < 0.001) and GPIHBP1 (p < 0.001), and lower fat mass index (p = 0.024). Kruskal-Wallis tests with Bonferroni multiple comparison tests showed that serum LPL and GPIHBP1 concentrations were significantly higher in the participants with higher SMI. Spearman's correlation analyses showed that SMI was positively correlated with LPL (ρ = 0.341, p < 0.001) and GPIHBP1 (ρ = 0.309, p = 0.001) concentration. The serum concentrations of LPL and GPIHBP1 were also inversely correlated with serum concentrations of triglyceride (LPL, ρ = - 0.198, p = 0.037; GPIHBP1, ρ = - 0.249, p = 0.008). Serum HTGL concentration was positively correlated with serum concentrations of total cholesterol (ρ = 0.308, p = 0.001), low-density lipoprotein-cholesterol (ρ = 0.336, p < 0.001), and free 3,5,3'-triiodothyronine (ρ = 0.260, p = 0.006), but not with SMI. CONCLUSIONS: The results suggest that increased skeletal muscle mass leads to improvements in energy metabolism by promoting triglyceride-rich lipoprotein hydrolysis through the increase in circulating LPL and GPIHBP1.

Vaccination Status and Antibody Titers against Rubella and Measles among Japanese Female College Students Majoring in Childcare between 2015 and 2018.

In 2014, for the protection of medical workers against measles and rubella infection, the Japanese Society for Infection Prevention and Control (JSIPC) recommended either maintaining antibody titers of seroprotective range or two-dose vaccination. JSIPC defined antibody titers into 3 ranges: seroprotective as expected prevention of infection, seronegative as under detection levels, and seropositive as antibody titers ranged between seronegative and seroprotective. This study aimed to explore the association between the number of vaccine doses received and the antibody titers against measles and rubella among Japanese college students majoring in childcare. A total of 841 female students with no history of measles or rubella were serologically screened at the time of college admission between 2015 and 2018. All 841 students had been vaccinated against measles; 738 (87.8%) received two doses of the measles vaccine and 103 (12.2%) received one dose. Likewise, 839 students, except for two, had been vaccinated against rubella; 719 (85.7%) received two doses of the rubella vaccine and 120 (14.3%) received one dose. We thus found that 107 students (12.7%) were seropositive for measles-specific IgG and 731 (86.9%) attained seroprotective titers. By contrast, in case of rubella-specific IgG, only 462 students (55.1%) attained seroprotective titers, and 371 students (44.1%) were seropositive. The two students without receiving rubella vaccination were classified as seronegative. In conclusion, despite that > 85% of students surveyed had received two doses of measles and rubella vaccines, a substantial number of students remain susceptible to measles and especially rubella at the time of college admission.

Frequency and clinical implication of the R450H mutation in the thyrotropin receptor gene in the Japanese population detected by Smart Amplification Process 2.

In Japanese pediatric patients with thyrotropin (TSH) resistance, the R450H mutation in TSH receptor gene (TSHR) is occasionally observed. We studied the frequency and clinical implication of the R450H mutation in TSHR in the general population of Japanese adults using smart amplification process 2 (SmartAmp2). We designed SmartAmp2 primer sets to detect this mutation using a drop of whole blood. We analyzed thyroid function, antithyroid antibodies, and this mutation in 429 Japanese participants who had not been found to have thyroid disease. Two cases without antithyroid antibodies were heterozygous for the R450H mutation in TSHR. Thus, the prevalence of this mutation was 0.47% in the general population and 0.63% among those without antithyroid antibodies. Their serum TSH concentrations were higher than the average TSH concentration not only in subjects without antithyroid antibodies but also in those with antithyroid antibodies. The R450H mutation in TSHR is relatively common in the Japanese population and potentially affects thyroid function. The present study demonstrates that the SmartAmp2 method is useful to detect the R450H mutation in TSHR, which is one of the common causes of TSH resistance in the Japanese population.

Association between accumulation of visceral fat and the combination of ß3 adrenergic receptor Trp64Arg, ß2 adrenergic receptor Arg16Gly and uncoupling protein 1 -3826A>G polymorphisms detected by Smart Amplification Process 2.

ß2 and ß3 adrenergic receptors (ß2AR, ß3AR) and uncoupling protein 1 (UCP1) have been considered as candidate genes for obesity. Although each polymorphism of ß3AR Trp64Arg, ß2AR Arg16Gly and UCP1 -3826A>G is known to be associated with obesity, the interaction among these polymorphisms is not fully understood. We analyzed ß3AR Trp64Arg, ß2AR Arg16Gly and UCP1 -3826A>G polymorphisms by the Smart Amplification Process 2 in 222 Japanese subjects without the medication of hypertension, dyslipidemia or diabetes, and investigated the association between the physical and metabolic characteristics and the combination of these polymorphisms. In analysis of the genotypes combination, only the carriers of both ß2AR Arg/Arg and UCP1 G/G genotypes had significantly higher waist to hip ratio (p=0.014). In analysis of the alleles combination, a significant difference was observed in waist to hip ratio among the groups stratified by the carrying number of the alleles of ß3AR Arg, ß2AR Arg and UCP1 G (p=0.026), and the waist to hip ratio was significantly higher in the carriers of four and five risk alleles than in the carriers from zero to three risk alleles (p=0.005). The present study demonstrated the interaction among ß3AR Trp64Arg, ß2AR Arg16Gly and UCP1 -3826A>G for the accumulation of visceral fat.

Oxidative stress associated with rapid weight reduction decreases circulating adiponectin concentrations.

The effect of stress associated with acute weight reduction on adipocytokine production is incompletely understood. In the present study, we have investigated the changes in circulating adipocytokine concentrations and urinary concentrations of stress markers in male collegiate wrestlers during acute weight reduction for a competition. Twenty healthy Japanese male wrestlers (18-22 years of age) who participated in the national collegiate wrestling tournament were studied. Body weight, body fat amount, serum testosterone, serum leptin, serum adiponectin, urinary 8-hydroxy-2'- deoxyguanosine (8-OHdG) and urinary biopyrrins were analyzed during acute weight reduction for the competition. Body weight, body fat amount and the serum concentrations of testosterone, leptin and adiponectin significantly decreased on the day of weigh-in compared with the levels 12 days before weigh-in. In contrast, urinary concentrations of 8-OHdG and biopyrrins significantly increased on the day of weigh-in compared with the concentrations 12 days before weigh-in. A positive correlation was observed between the serum concentrations of adiponectin and testosterone, and a negative correlation was observed between the concentrations of serum adiponectin and urinary biopyrrins. The present results suggest that rapid weight reduction increases the urinary concentrations of stress markers, which is associated with a decrease in serum concentrations of adiponectin.