Comparative analysis of salivary cortisol measurements using different assay methods in relation to serum-free cortisol measurement.

Objectives: Salivary cortisol reflects the biologically active form of serum cortisol, offering a noninvasive evaluation method for the diurnal rhythm of the hypothalamic-pituitary-adrenal (HPA) axis. While liquid chromatography-tandem mass spectrometry (LC-MS/MS) is known for its specificity, immunoassays (IA) are commonly used because of their simplicity. This study aimed to assess the performance of salivary cortisol measurement using both IA and LC-MS/MS in comparison to serum-free cortisol measurement. Methods: Assay results for 188 saliva and 94 serum samples from 47 participants were analyzed. Salivary samples collected at different time points were analyzed using IA and LC-MS/MS. Serum samples were analyzed for cortisol, cortisol-binding globulin, and free cortisol. The statistical analyses included correlations and method comparisons. Results: The diurnal salivary cortisol profiles exhibited a comparable circadian rhythm pattern; however, the concentrations measured using IA were consistently higher than those measured using LC-MS/MS. The correlation analysis revealed robust associations among salivary cortisol (IA), salivary cortisol (LC-MS/MS), and serum-free cortisol levels (LC-MS/MS). However, the method comparison revealed a systematic bias between IA and LC-MS/MS in salivary cortisol measurement. Conclusions: This study contributes to the ongoing debate on assay techniques by affirming the suitability of IA and LC-MS/MS for salivary cortisol measurement to assess dynamic changes in HPA axis activity. The identified systematic bias emphasizes the importance of selecting methods based on specific research or clinical requirements.

The association between phthalate exposure and pubertal development.

Antiandrogenic effect of phthalates have been reported; however, results regarding the effect of phthalate exposure in pubertal children have been inconsistent. We aimed to investigate the relationship between phthalate exposure and pubertal development, especially whether high molecular weight phthalates (HMWP) and low molecular weight phthalates (LMWP) are differently associated in boys and girls. Urinary phthalate metabolites (4 HMWPs and 3 LMWPs) in Korean children (236 boys and 202 girls, aged 10 to 12 years) were measured. The association between phthalate levels and pubertal development (pubertal stages self-reported by parents and sex steroid levels) was analyzed by generalized linear regression after adjusting for age, body mass index z score, and premature birth and/or low birth weight. Both the highest quartile of HMWP (Q4 vs Q1, adjusted odds ratio [OR], 0.238; 95% confidence interval [CI], 0.090-0.627; p = 0.004) and LMWP (Q4 vs Q1, adjusted OR, 0.373; 95% CI, 0.151-0.918; p = 0.032) were inversely associated with pubertal stages in boys, whereas the highest quartile of LMWP (Q4 vs Q1, adjusted OR, 2.431; 95% CI, 1.024-5.768; p = 0.044) was significantly related to advanced pubertal stages in girls. Testosterone levels in boys were significantly lower at the highest quartile of HMWP (adjusted ß = - 0.251; 95% CI, - 0.476 to - 0.027; p = 0.028). However, in girls, we could not find any significant relationship between HMWP or LMWP and estradiol levels. CONCLUSIONS: Our results suggest that phthalate exposure, especially exposure to the HMWP, may have inverse association with male pubertal development. Further investigation is required to verify the relationship of phthalate exposure and pubertal development in girls. WHAT IS KNOWN: • Exposure to phthalates may have antiandrogenic effects. • Studies on the association between phthalates and pubertal development have yielded inconsistent results. WHAT IS NEW: • Phthalate levels were inversely associated with self-reported pubertal stages in boys. • Exposure to phthalates might have a negative influence on male pubertal development.

Cancer signature ensemble integrating cfDNA methylation, copy number, and fragmentation facilitates multi-cancer early detection.

Cell-free DNA (cfDNA) sequencing has demonstrated great potential for early cancer detection. However, most large-scale studies have focused only on either targeted methylation sites or whole-genome sequencing, limiting comprehensive analysis that integrates both epigenetic and genetic signatures. In this study, we present a platform that enables simultaneous analysis of whole-genome methylation, copy number, and fragmentomic patterns of cfDNA in a single assay. Using a total of 950 plasma (361 healthy and 589 cancer) and 240 tissue samples, we demonstrate that a multifeature cancer signature ensemble (CSE) classifier integrating all features outperforms single-feature classifiers. At 95.2% specificity, the cancer detection sensitivity with methylation, copy number, and fragmentomic models was 77.2%, 61.4%, and 60.5%, respectively, but sensitivity was significantly increased to 88.9% with the CSE classifier (p value < 0.0001). For tissue of origin, the CSE classifier enhanced the accuracy beyond the methylation classifier, from 74.3% to 76.4%. Overall, this work proves the utility of a signature ensemble integrating epigenetic and genetic information for accurate cancer detection.

Short-Term Effects of Weight-Loss Meal Replacement Programs with Various Macronutrient Distributions on Gut Microbiome and Metabolic Parameters: A Pilot Study.

It has emerged the gut microbiome is crucially linked to metabolic health and obesity. Macronutrient distribution has been discussed as a key parameter in weight-loss programs, but little is known about its impact on the gut microbiome. We investigated the effects of weight-loss meal replacement programs with different macronutrient ratios on the gut microbiota and metabolic parameters in subjects with overweight and obesity. Three low-calorie meal replacement programs with different ratios of carbohydrates, proteins, and lipids were designed: a balanced diet (Group B, 60:15:30), a high-lipid-low-carbohydrate diet (Group F, 35:20:55), and a protein-enriched diet (Group P, 40:25:35). Sixty overweight or obese participants were provided with the meals twice daily for 3 weeks. In all groups, diet intervention resulted in reduced body weight and BMI. The relative abundance of Bacteroidetes and Firmicutes phyla decreased and increased, respectively, which increased the Firmicutes/Bacteroidetes (F/B) ratio in all subjects, particularly in Groups B and P. Alpha- and beta-diversity were augmented at the phylum level in Group P. In conclusion, short-term interventions with weight-loss meal replacement programs increased butyrate-producing bacteria and the F/B ratio. Moreover, the protein-enriched diet significantly increased alpha- and beta-diversity compared to the balanced diet and the high-lipid-low-carbohydrate diet.

Identification of genetic variants related to metabolic syndrome by next-generation sequencing.

BACKGROUND: Metabolic syndrome (MetS) is a cluster of conditions associated with glucose intolerance, hypertension, abdominal obesity, dyslipidemia, and insulin resistance that increase the risk of cardiovascular diseases (CVD) and type 2 diabetes (T2D). Since MetS is known as a complex symptom with a high incidence of genetic factors, it is important to identify genetic variants for each clinical characteristic of MetS. METHODS: We performed targeted next-generation sequencing (NGS) to identify genetic variants related to obesity, blood glucose, triacylglycerol (TG), and high-density lipoprotein (HDL)-cholesterol level, and hypertension in 48 subjects with MetS and in 48 healthy subjects. RESULTS: NGS analysis revealed that 26 of 48 subjects (54.2%) with MetS had putative non-synonymous variants related to the clinical features of MetS. Of the subjects with MetS, 8 (16.7%) had variants in 4 genes (COL6A2, FTO, SPARC, and MTHFR) related to central obesity, 17 (35.4%) had variants in 6 genes (APOB, SLC2A2, LPA, ABCG5, ABCG8, and GCKR) related to hyperglycemia, 3 (6.3%) had variants in 4 genes (APOA1, APOC2, APOA4, and LMF1) related to hypertriglyceridemia, 8 (16.7%) had variants in 4 genes (ABCA1, CETP, SCARB1, and LDLR) related to low HDL-cholesterolemia, and 5 (10.4%) had variants in ADD1 related to hypertension. CONCLUSIONS: Our findings may contribute to broadening the genetic spectrum of risk variants related to the development of MetS.

Genetic Variants Associated with Elevated Plasma Ceramides in Individuals with Metabolic Syndrome.

Metabolic syndrome (MetS) is a complex condition of metabolic disorders and shows a steady onset globally. Ceramides are known as intracellular signaling molecules that influence key metabolism through various pathways such as MetS and insulin resistance. Therefore, it is important to identify novel genetic factors related to increased plasma ceramides in subjects with MetS. Here we first measured plasma ceramides levels in 37 subjects with MetS and in 38 healthy subjects by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Specifically, levels of C16 ceramide (Cer-16), C18 ceramide (Cer-18), C20 ceramide (Cer-20), C18 dihydroceramide (DhCer-18), C24 dihydroceramide (DhCer-24), and C24:1 dihydroceramide (DhCer-24:1) were significantly increased in MetS group (p < 5.0 × 10−2). We then performed single nucleotide polymorphism (SNP) genotyping to identify variants associated with elevated plasma ceramides in MetS group using Axiom® Korea Biobank Array v1.1 chip. We also performed linear regression analysis on genetic variants involved in ceramide synthesis and significantly elevated plasma ceramides and dihydroceramides. Ten variants (rs75397325, rs4246316, rs80165332, rs62106618, rs12358192, rs11006229, rs10826014, rs149162405, rs6109681, and rs3906631) across six genes (ACER1, CERS3, CERS6, SGMS1, SPTLC2, and SPTLC3) functionally involved in ceramide biosynthesis showed significant associations with the elevated levels of at least one of the ceramide species in MetS group at a statistically significant threshold of false discovery rate (FDR)-adjusted p < 5.0 × 10−2. Our findings suggest that the variants may be genetic determinants associated with increased plasma ceramides in individuals with MetS.

Sex differences in body composition affect total airway resistance during puberty.

BACKGROUND: During puberty, changes in body composition due to sex hormones are associated with lung mechanics. However, little is known about the mediation effect of sex differences in body composition during puberty with total airway resistance. METHODS: We prospectively recruited 620 children (10-12 years old) from the general population and conducted a cross-sectional study. This study assessed pubertal status according to the five Tanner stages using a questionnaire, line drawings, and each subject's blood sex hormone profile. Both the impulse oscillation system for total lung mechanics and multifrequency bioelectrical impedance for body composition analyses were conducted. The effects of puberty on body composition and subsequent total lung resistance were evaluated using mediation analysis. RESULTS: Among the 503 children enrolled, there were 261 males (51.9%) and 242 females (48.1%). In males, higher testosterone levels corresponded with reduced total lung resistance (ß = -0.13, 95% CI = -0.21 to -0.05, p < 0.001), and the proportion of the mediating effect through the muscle-fat ratio was 19% (95% CI = 4 to 59, p = 0.02). In contrast, in females, pubertal status reduced total lung resistance (ß = -0.27, 95% CI = -0.58 to -0.05, p = 0.04), however, the proportion of the mediating effect through the body mass index was -51% (95% CI = -244 to -4%, p = 0.04). CONCLUSION: The muscle-fat ratio in adolescent males had a synergistic effect with testosterone on improving total airway resistance, whereas improvements in lung resistance by pubertal status were partially masked by body mass index in adolescent females. In conclusion, body composition changes during puberty between males and females have differing effects on total airway resistance.

Identification of Single Nucleotide Polymorphisms as Biomarkers for Recurrent Pregnancy Loss in Korean Women.

BACKGROUND: Single nucleotide polymorphisms (SNPs) are reportedly associated with repeated abortion. Thus, genetic analysis based on race is the key to developing accurate diagnostic tests. This study analyzed the genetic polymorphisms of recurrent pregnancy loss (RPL) patients among Korean women compared to the controls. METHODS: In 53 women of RPL group and 50 controls, the genetic analysis was performed. The genotype distribution and allele frequency were analyzed statistically for the difference between the two groups. The association between each SNP marker and RPL risk was analyzed. RESULTS: The genotypes of LEPR, endothelial nitric oxide synthase (eNOS), KDR, miR-27a, miR-449b, and tumor necrosis factor-alpha (TNF-α) were analyzed using odds ratio (OR) with 95% confidence intervals (CIs). Only the AG genotype of miR-449b (A>G) polymorphism showed significant association with the risk of RPL when compared to the AA genotype (OR, 2.39). The combination of GG/AG+GG/CA+AA genotypes for eNOS/miR-449b/TNF-α was associated with 7.36-fold higher risk of RPL (OR, 7.36). The GG/AG+GG combination for eNOS/miR-449b showed 2.43-fold higher risk for RPL (OR, 2.43). The combination of AG+GG/CA+AA genotypes for miR-449b/TNF-α showed a significant association with the risk of RPL (OR, 7.60). From the haplotype-based analysis, the G-G-A haplotype of eNOS/miR-449b/TNF-α and the G-A haplotype of miR-449b/TNF-α were associated with increased risk of RPL (OR, 19.31; OR, 22.08, respectively). CONCLUSION: There is a significant association between the risk of RPL and miR-449b/TNF-α combination, and therefore, genetic analysis for specific combined genotypes can be an important screening method for RPL in Korean women.

Trend Analysis of the Profiles of 12 Sexually Transmitted Disease Pathogens in the Republic of Korea in 2019.

BACKGROUND: Sexually transmitted diseases (STDs) are common infectious diseases in humans transmitted through unprotected sexual activities. In South Korea, despite the high annual incidence of STDs, detailed examinations of pathogen-specific factors and causes for delays in diagnosis and treatment are still lacking. Furthermore, STD prevalence patterns and important pathogen-specific factors remain unclear. Herein, we retrospectively analyzed the epidemiology of STDs in South Korea in 2019 by analyzing the association of pathogen-specific infection patterns with factors such as sex, age, region, and month. METHODS: We obtained the STD test results of 172,973 individuals from the Seoul Clinic Laboratory in 2019, most of whom had multiple infections; hence, 275,296 STD-positive cases were included in this analysis. Through deoxyribonucleic acid (DNA) amplification, they were categorized by pathogen type. Subsequently, they were further classified by month, region, and age while concurrently being stratified according to sex. RESULTS: Among the 12 pathogens detected in this study, Gardnerella vaginalis had the highest prevalence, with 92,490 cases in both sex groups; moreover, many of them were concurrently infected by two or more pathogens. The prevalence of STDs did not differ according to month or region. Conversely, the pathogen-specific prevalence rates significantly differed according to age. Older adults had higher prevalence rates of Chlamydia trachomatis, Trichomonas vaginalis, Candida albicans, and herpes simplex virus type 1 infections than younger adults. CONCLUSION: These pathogen-specific prevalence patterns provide information that helps to understand population vulnerability according to region and age and helps develop STD prevention and treatment strategies in South Korea.

Comparative analysis of mutational hotspots in the spike protein of SARS-CoV-2 isolates from different geographic origins.

The spike (S) protein mutations of SARS-CoV-2 are of major concern in terms of viral transmission and pathogenesis. Hence, we developed a PCR-based method to rapidly detect the 6 mutational hotspots (H49Y, G476S, V483A, H519Q, A520S, and D614G) in the S protein and applied this method to analyze the hotspots in the viral isolates from different geographical origins. Here, we identified that there was only the D614G mutation in the viral isolates. As of September 30, 2020, the analysis of 113,381 sequences available from the public repositories revealed that the SARS-CoV-2 variant carrying G614 has become the most prevalent form globally. Our results support recent epidemiological and genomic data demonstrating that the viral infectivity and transmission are enhanced by the S protein D614G mutation.

Novel indel mutation in the N gene of SARS-CoV-2 clinical samples that were diagnosed positive in a commercial RT-PCR assay.

Commercially available reverse transcription-polymerase chain reaction (RT-PCR) kits are being used as an important tool to diagnose SARS-CoV-2 infection in clinical laboratories worldwide. However, some kits lack sufficient clinical evaluation due to the need for emergency use caused by the current COVID-19 pandemic. Here we found that a novel insertion/deletion mutation in the nucleocapsid (N) gene of SARS-CoV-2 samples is a cause of negative results for the N gene in a widely used assay that received emergency use authorization (EUA) from US FDA and Conformite Europeenne-in vitro diagnostics (CE-IVD) from EU. Although SARS-CoV-2 is diagnosed positive by other target probes in the assay, our findings provide an evidence of the genetic variability and rapid evolution of SARS-CoV-2 as well as a reference in designing commercial RT-PCR assays.

The Level of Serum and Urinary Nephrin in Normal Pregnancy and Pregnancy with Subsequent Preeclampsia.

PURPOSE: The aim of this study was to evaluate serum and urinary nephrin levels of normal pregnancy to establish a standard reference value and to compare them with patients who subsequently developed preeclampsia (PE). MATERIALS AND METHODS: In this prospective study, 117 healthy singleton pregnancies were enrolled between 6 to 20 weeks of gestation at 2 participating medical centers during October 2010 to March 2012. Urine and serum samples were collected at the time of enrollment, each trimester, and at 4 to 6 weeks postpartum. Enzyme-linked immunosorbent assay for nephrin was performed and samples from patients who subsequently developed PE were compared to the normal patients. RESULTS: Of 117 patients initially enrolled, 99 patients delivered at the study centers and of those patients, 12 (12.1%) developed PE at a median gestational age of 34⁺4 weeks (range 29⁺5-36⁺6). In the normal patients (n=68), serum nephrin level decreased and urinary nephrin level increased during the latter of pregnancy. In 12 patients who subsequently developed PE, a significant rise in the 3rd trimester serum and urinary nephrin levels, compared to the controls, was observed (p<0.001), and this increase occurred 9 days prior to the onset of clinical disease. CONCLUSION: As the onset of PE was preceded by the rise in the serum and urinary nephrin in comparison to normal pregnancy, serum and urinary nephrin may be a useful predictive marker of PE.

A Rapid and Simple Liquid-Chromatography-Tandem Mass Spectrometry Method for Measuring 25-Hydroxyvitamin D2 and 25-Hydroxyvitamin D3 in Human Serum: Comparison with Two Automated Immunoassays.

BACKGROUND: Total 25-hydroxyvitamin D (25(OH)D) is well-known to be a reliable biomarker of human vitamin D status, with the recognition of widespread vitamin D insufficiency in general populations. The aims of this study are to validate a fast and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying 25(OH)D2 and 25(OH)D3 in serum and to compare two automated immunoassays with the LC-MS/MS method. METHODS: Samples were prepared by protein precipitation with ethanol including 25(OH)D3-d6, followed by a liquid-liquid extraction with hexane. The analytes were separated within a total run time of 3 min. Accuracy was evaluated with standard reference materials (SRM) 972a. Using 150 samples, the LC-MS/MS method was compared with the LIAISON® assay and ADVIA Centaur® assay. RESULTS: The LC-MS/MS method had a limit of quantitation of 1 ng/mL for the 25(OH)D2 and 25(OH)D3 with linear responses between 1 and 100 ng/mL. Intra- and inter-assay precision were <8.8% and <13.2%, respectively. It also showed a smallest mean difference (+0.9%) for the SRM level 1 to 3, compared to the two immunoassays. Compared to the LC-MS/MS, the mean biases of the RIAISON and ADVIA were +2.4 and +7.9 ng/mL, respectively. Also, the agreement of the LC-MS/MS with the RIAISON was better than that with the ADVIA. CONCLUSION: This study suggests that the LC-MS/MS method traceable to the SRM can be reliably applied in routine quantification of 25(OH)D2 and 25(OH)D3.

Simultaneous determination of cortisol and cortisone from human serum by liquid chromatography-tandem mass spectrometry.

A fast, sensitive, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was validated and then the levels of cortisol and cortisone from sera of healthy adults were determined by the LC-MS/MS method. One hundred µ L of serum sample was directly extracted by adding 2 mL ethyl acetate, followed by chromatographic separation on a C18 column with a mobile phase consisting of 5 mM ammonium acetate and methanol (25 : 75, v/v). The precision, accuracy, and average recovery of the method were 1.5-5.3%, 95.4-102.5%, and 96.4% for cortisol, and 1.9-6.0%, 89.2-98.8%, and 79.9% for cortisone, respectively. The method was linear from 1.0 to 500.0 ng/mL (r(2) = 0.999) for cortisol and 2.5 to 100.0 ng/mL (r(2) = 0.998) for cortisone. The limits of detection (LOD) and quantification (LOQ) were 0.2 and 1.0 ng/mL for cortisol, and 1.0 and 2.5 ng/mL for cortisone, respectively. The average cortisol concentration (133.9 ± 63.7 ng/mL) of samples collected between 9:00 and 11:00 a.m. was higher approximately 4.4 times than that of cortisone (30.5 ± 10.7 ng/mL) (P < 0.0001). The average cortisone/cortisol ratio was 0.225. Therefore, the LC-MS/MS method may be useful for the diagnosis of some adrenal diseases and the assessment of 11 ß -hydroxysteroid dehydrogenase (11 ß -HSD) activity in clinical laboratories.

Biotinylation of the rhizobial cyclic ß-glucans and succinoglycans crucial for symbiosis with legumes.

The cyclic ß-glucans and succinoglycans produced by rhizobia are required for nodulation during symbiosis with legume hosts. However, only gene deletion analyses have been used to investigate their biological importance. For future studies on the physiological activity of those during symbiosis, biochemical methods need to be developed with separate carbohydrate compounds. Here, we isolated and purified rhizobial cellular carbohydrates using various chromatographic methods. Purified cyclic ß-glucans, cyclosophoraoses, were monofunctionalized with biotin using the following three steps: tosylation, azidation, and amination. The mono-6-amino-cyclosophoraoses were linked with biotinamidohexanoic acid N-hydroxysuccinimide ester. Succinoglycans and monomers were tagged with biotinamidocaproyl hydrazide at the reducing sugar via reductive amination. The resulting biotinylated rhizobial carbohydrates were characterized by Fourier transform infrared and nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy, and electrospray ionization mass spectrometry. The resulting neoglycoconjugates can be used as solid probes to study putative plant receptors and for non-invasive imaging for in vivo tracing.

Comparison of serum and urinary nephrin levels between normal pregnancies and severe preeclampsia.

OBJECTIVE: To compare the levels of urinary excretion of nephrin in women experiencing either normotensive or severe preeclamptic pregnancies, and to examine the relationship between urinary nephrin levels and clinical parameters of preeclampsia. STUDY DESIGN: In a case control study we collected serum and urine specimens from women with normal pregnancy (n=30) and from women with severe preeclampsia (n=43). Serum nephrin levels and urinary nephrin concentrations were measured in all patients. RESULTS: Both serum and urine concentrations of nephrin were significantly higher in the severe preeclamptic group than in the normal pregnancy group. In addition, we identified a significant relationship between urinary nephrin levels and urine protein concentrations in the severe preeclamptic group. Urine nephrin concentrations were also correlated with serum creatinine levels and with diastolic blood pressure in the severe preeclamptic group. CONCLUSION: The positive correlations observed in this study suggest that urinary nephrin excretion might play an important role in the pathogenesis of proteinuria during preeclampsia and could be a good indicator of renal damage.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometric behavior of succinoglycan monomers, dimers, and trimers isolated from Sinorhizobium meliloti 1021.

Low-molecular-weight (LMW) succinoglycans (monomers, dimers, and trimers) were isolated from Sinorhizobium meliloti 1021 and have been firstly investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) using 2,4,6-trihydroxyacetophenone (THAP) as an optimal matrix in the negative ion mode. The main fractions of LMW succinoglycans contain molecules assembled of octasaccharide subunits. MALDI-TOF mass spectra of the LMW succinoglycan monomers, the dimers, and the trimers showed the daughter ions resulting from the losses of the terminal galactose residues at the reducing ends, clearly indicating that the galactosyl linkages are more labile than the other glucosyl linkages. Furthermore, the losses of the acetyl groups as substituents rather than the succinyl and pyruvyl ester linkages by prompt fragmentation primarily occurred during MALDI-TOF analysis, suggesting the greater instability of acetyl linkages compared to pyruvyl and succinyl linkages.

Quantitative measurement of salivary testosterone in Korean adults by stable isotope-dilution liquid chromatographyelectrospray-tandem mass spectrometry.

Salivary testosterone levels in Korean adults were quantitatively measured for the first time by liquid chromatography-electrospray-tandem mass spectrometry (LC ESI MS/MS). Salivary testosterone was separated on a multiple reaction monitoring (MRM) chromatogram within 7 min. The LC ESI MS/MS assay was validated over the linearity range of 0.01-2.00 ng/ml (r=0.99987) using testosterone-d(3) as an internal standard. The lower limit of quantification (LOQ) was 0.01 ng/ml. The intra- and inter-assay precisions were 1.54% to 4.09% and 0.96% to 4.29%, respectively. The mean recovery was 93.32% (range 88.43-98.05%). The validated assay was then applied to measure the salivary testosterone levels of Korean adults. In men, the salivary testosterone level collected between 9:00-11:00 am was approximately 2.8 times higher than that in women (P < 0.0001). Salivary testosterone levels in both sexes negatively correlated with age. The present assay would also be useful in measuring salivary testosterone levels in clinical laboratories.

Simultaneous quantitative analysis of salivary cortisol and cortisone in Korean adults using LC-MS/MS.

The levels of salivary cortisol and cortisone in Korean adults were measured for the first time using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The salivary cortisol and cortisone were separated within 10 min. The regression coefficients (r) of the calibration curves were greater than 0.999 for the two steroids. The limits of quantitation (LOQ) were 0.2 ng/ml for cortisol and 1 ng/ml for cortisone. The intra-day precisions of the assay were <3.9% and 8.6% for cortisol and cortisone respectively, and the inter-day precisions were <1.9% and 4.3% for cortisol and cortisone, respectively. The salivary cortisone concentrations were approximately 4-9 times higher than those of salivary cortisol during the daytime. Diurnal rhythms, during which the cortisol and cortisone concentrations were higher in the morning than in the afternoon, were also observed. The present assay may be useful for the diagnosis of several adrenal dysfunctions in clinical biochemistry.

Synthesis of selenium nanowires morphologically directed by Sinorhizobial oligosaccharides.

Shinorhizobial cyclosophoraose (cyclic beta-(1-->2)-glucan) or succinoglycan monomer (SGM 2), which has one acetyl, pyruvyl, and succinyl group, functions as a morphology-directing agent for the synthesis of pure trigonal selenium nanowires by using ascorbic acid (vitamin C) as the reducing agent. The synthesis was achieved in water at room temperature. Under these experimental conditions, the diameters of the as-prepared Se nanowires were varied in the range of 34-120 nm by cyclosophoraose and of 33-66 nm by SGM 2, in which the nanowires were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Through this study, we propose that Shinorhizobial cyclic and linear oligosaccharides have morphologically directing functions for the synthesis of single-crystalline selenium nanowires by green chemical methods.