Sulfur Compounds Inhibit High Glucose-Induced Inflammation by Regulating NF-κB Signaling in Human Monocytes.

High glucose-induced inflammation leads to atherosclerosis, which is considered a major cause of death in type 1 and type 2 diabetic patients. Nuclear factor-kappa B (NF-κB) plays a central role in high glucose-induced inflammation and is activated through toll-like receptors (TLRs) as well as canonical and protein kinase C-dependent (PKC) pathways. Non-toxic sulfur (NTS) and methylsulfonylmethane (MSM) are two sulfur-containing natural compounds that can induce anti-inflammation. Using Western blotting, real-time polymerase chain reaction, and flow cytometry, we found that high glucose-induced inflammation occurs through activation of TLRs. An effect of NTS and MSM on canonical and PKC-dependent NF-κB pathways was also demonstrated by western blotting. The effects of proinflammatory cytokines were investigated using a chromatin immunoprecipitation assay and enzyme-linked immunosorbent assay. Our results showed inhibition of the glucose-induced expression of TLR2 and TLR4 by NTS and MSM. These sulfur compounds also inhibited NF-κB activity through reactive oxygen species (ROS)-mediated canonical and PKC-dependent pathways. Finally, NTS and MSM inhibited the high glucose-induced expression of interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α and binding of NF-κB protein to the DNA of proinflammatory cytokines. Together, these results suggest that NTS and MSM may be potential drug candidates for anti-inflammation therapy.

Validating a single-question depression measure among older adults.

BACKGROUND: A single-item depression measure may not be adequate in capturing the complex entity of mental health, despite wide use of this indicator in community studies. This study evaluated the accuracy of a single-question depression measure in comparison to two composite indices-the Center for Epidemiologic Studies Depression Scale (CESD) and the Geriatric Depression Scale (GDS). MATERIALS AND METHODS: A total of 800 elderly participants ranging from 60 to 89 years of age and residing in Seoul were recruited using a multistage sampling scheme in 2015. The survey was conducted by trained interviewers with a constructed questionnaire. Reliability and validity measures such as the Kappa index, sensitivity, specificity, PPV, NPV, and AUC were used to evaluate the accuracy of the single question measure. Socio-demographic group differences in accuracy were compared by age, sex, marital status, education, employment, and financial status. RESULTS: The prevalence of depression by a single-question measure was much lower than those of CESD and GDS (5.5%, 12.3%, and 12.1%, respectively). The sensitivity of the single-item measure, based on CESD and GDS, was extremely low at 30.6% and 36.1%. In the subgroup analysis, however, there was a marked educational discrepancy in all accuracy measures; in sensitivity, people with a university degree or higher showed about 2.4 times higher sensitivity than those having only a primary school education. CONCLUSIONS: The results show that a single-question depression measure should be used with caution. In addition, the single-question measure could substantially underestimate depression among the risk group of older adults.

Racial/ethnic variations in the main and buffering effects of ethnic and nonethnic supports on depressive symptoms among five ethnic immigrant groups in Toronto.

OBJECTIVES: This study examined variations in the main and buffering effects of ethnic and nonethnic social support on depressive symptoms associated with discrimination among five immigrant groups in Toronto. DESIGN: Data were taken from the Toronto Study of Settlement and Health, a cross-sectional survey of adult immigrants from five ethnic communities (Vietnamese, Ethiopian, Iranian, Korean, and Irish) in Toronto. A total of 900 surveys were collected through face-to-face interviews conducted between April and September 2001. RESULTS: Significant ethnic variations were observed in the effects of both ethnic and nonethnic social supports on discrimination-related depressive symptoms. Regarding the main effect, ethnic social support was significantly stronger for Iranian, Ethiopian, and Korean immigrants than for Irish immigrants. The benefits of nonethnic support were stronger for Iranian immigrants compared to the effect found in the Irish sample. With respect to stress-buffering or stress-moderating effects of social support, ethnic support was significant in all ethnic groups, except the Vietnamese group. Nonethnic support aggravated the negative impact of discrimination on depressive symptoms in the Irish group, but exerted a stress-buffering effect in the Iranian group. CONCLUSIONS: Overall, social supports received from fellow ethnic group members had significant main effects (suppressing depressive symptoms) and stress-buffering effects and were most pronounced in the minority ethnic immigrant groups of Ethiopians, Koreans, and Iranians. The effects were least evident among the Vietnamese and Irish. Evidence for the stress-suppressing and stress-buffering role of cross-ethnic group supports was unclear, and even inverted among Irish immigrants. Empirical evidence from the current study seems to support the sociocultural similarity hypothesis of social support.

Phase Transitions and Thermoelectric Properties of Charge-Compensated ZnxCu12-xSb4Se13.

In this study, we investigated the phase transitions and thermoelectric properties of charge-compensated hakite (ZnxCu12-xSb4Se13) as a function of Zn content. Based on X-ray diffraction and a differential scanning calorimetric phase analysis, secondary phases (permingeatite and bytizite) transformed into hakite depending on the Zn content, while Zn2Cu10Sb4Se13 existed solely as hakite. Nondegenerate semiconductor behavior was observed, exhibiting increasing electrical conductivity with a rising temperature. With an increase in Zn content, the presence of mixed phases of hakite and permingeatite led to enhanced electrical conductivity. However, Zn2Cu10Sb4Se13 with a single hakite phase exhibited the lowest electrical conductivity. The Seebeck coefficient exhibited positive values, indicating that even after charge compensation (electron supply) by Zn, p-type semiconductor characteristics were maintained. With the occurrence of an intrinsic transition within the measured temperature range, the Seebeck coefficient decreased as the temperature increased; at a certain temperature, Zn2Cu10Sb4Se13 exhibited the highest value. Thermal conductivity showed a low temperature dependence, obtaining low values below 0.65 Wm-1K-1. A power factor of 0.22 mWm-1K-2 and dimensionless figure of merit of 0.31 were achieved at 623 K for ZnCu11Sb4Se13.

Ethnicity and postmigration health trajectory in new immigrants to Canada.

OBJECTIVES: In this prospective cohort study, we examined the trajectory of general health during the first 4 years after new immigrants' arrival in Canada. We focused on the change in self-rated health trajectories and their gender and ethnic disparities. METHODS: Data were derived from the Longitudinal Survey of Immigrants to Canada and were collected between April 2001 and November 2005 by Statistics Canada. We used weighted samples of 3309 men and 3351 women aged between 20 and 59 years. RESULTS: At arrival, only 3.5% of new immigrants rated their general health as poor. Significant and steady increases in poor health were revealed during the following 4 years, especially among ethnic minorities and women. Specifically, we found a higher risk of poor health among West Asian and Chinese men and among South Asian and Chinese women than among their European counterparts. CONCLUSIONS: Newly arrived immigrants are extremely healthy, but the health advantage dissipates rapidly during the initial years of settlement in Canada. Women and minority ethnic groups may be more vulnerable to social changes and postmigration settlement.

Emotional demands and the risks of depression among homecare workers in the USA.

PURPOSE: Homecare workers' diversity of emotional demands and their relation to mental health problems have not yet been fully explored. The purpose of this study is to investigate the types of emotional demands on homecare workers and the association of these demands with depression. METHOD: Data were collected from two surveys of a random sample of 1,599 homecare workers (June 2003-September 2003 and December 2003-February 2004). Depression was assessed using a 20-item RCES-D screening scale. RESULTS: Homecare workers appeared to have a variety of emotional demands: unfair treatment, client's family abuse, unmet care needs, client health, and emotional suppression. In general, homecare workers were more likely to be exposed to their client health and emotional suppression (mean scores = 1.46-3.07) than to be exposed to unmet care needs, unfair treatment, and client's family abuse (mean scores = 1.02-1.38). After adjusting for potential confounders, four emotional-demand factors (excluding the client health factor) were significantly associated with a high risk of subthreshold depression at Wave 1. In particular, the factor "unmet care needs" was an essential predictor of 6-month subthreshold depression at Wave 2. CONCLUSION: This study illustrated the diversity of emotional demands among homecare workers and their association with depression. Our mixed findings regarding the cross-sectional and longitudinal analyses suggested that further research should refine the measurement of emotional demands and their relationship with mental health among homecare workers.

The Trajectory of Depressive Symptoms Across Years of Community Care Utilization Among Older Adults: A 14-Year Follow-up Study Using the 'Korean Welfare Panel Survey'.

OBJECTIVES: While older adults using community care services are known to be vulnerable for depression, community care utilization (CCU) may help to improve the mental health of these elderly. To date, however, it is much less clear how CCU affects depressive symptoms in the elderly population. This study focuses on the trajectory of depressive symptoms across years of CCU among older adults in Korea. METHODS: Using the 2006-2019 Korean Welfare Panel Survey, this study is focused on elderly born in 1940 or earlier and selected 3281 persons for baseline interviews in 2006. This consisted of 35 800 person-year observations during a period of 14 years. Panel data analysis were employed to construct years of CCU. RESULTS: After controlling for covariates, linear term of years using community care was negatively associated with depressive symptoms, but a quadratic term was positively significant. The trajectory of depressive symptoms across the years of CCU follows a U-shaped curve. Older adults in the first year of using community care reported the highest level of depressive symptoms. However, a significant and steady decrease in depressive symptoms was observed during the following 9 years of CCU, which then gradually increased. The level of depressive symptoms at the 14th year of using community care remains significantly lower than the level at the outset of its utilization. CONCLUSIONS: This finding implies that CCU could be beneficial for improving mental health among older adults.

"Leisure Life Satisfaction:" Will It Have a Beneficial Impact on Depression Among Older Adults in Community Care Settings in Korea?

OBJECTIVES: While the risk of depression is expected to substantially increase among older adults receiving community care, leisure life satisfaction can be regarded as a key component in enhancing the mental health of those receiving community care. However, it is not yet known whether community care utilization increases the risk of depression, or what role is played by leisure life satisfaction in these settings. This study investigated the relationship between community care utilization and depression, as well as the main effect and the moderating role of leisure life satisfaction on the link between community care utilization and depression among older adults. METHODS: This study, using the 2019 Korean Welfare Panel Survey, conducted multiple regression analysis on data from 4494 elderly people aged 65 years or older. RESULTS: After controlling for potential covariates, older community care recipients were more likely to report symptoms of depression than those who did not receive community care. Meanwhile, leisure life satisfaction was negatively associated with depression in older adults. The test for interaction between community care utilization and leisure life satisfaction revealed that leisure life satisfaction significantly attenuated the link between depression and community care utilization. CONCLUSIONS: The findings of this study imply that leisure life satisfaction could play a meaningful role in improving the mental health of older adults receiving community care. Welfare policies affecting older adults should consider leisure life satisfaction as an important resource for reducing depression in community care settings.

Gender differences in the effect of obesity on chronic diseases among the elderly Koreans.

The objective of this study is to investigate gender differences of obesity on major chronic diseases in elderly Korean males and females. This study applied a cross sectional design using the 2005 Korean National Health and Nutrition Examination Survey (KNHNES). We selected 508 elderly males and 830 elderly females who were 60 or more years old. Obesity was defined using Body Mass Index (BMI) (≥ 25) or Waist Circumference (WC) (≥ 90 for men and ≥ 85 for women). We applied a surveylogistic regression to determine gender differences in relation to the effect of obesity on eleven major chronic diseases. Using WC, 46.2% of females were obese compared to 34.3% for males. Similarly, using BMI, 42.2% of females were obese compared to 31.7% for males. While obese males and females had similar profiles for developing metabolic syndrome components including hypertension, dyslipidemia, and diabetes (odds ratios [ORs] were 1.8-2.6 for males and 1.7-2.5 for females), obese elderly females had additional risks for arthritis and urinary incontinence (ORs 1.5-1.8 for females) as well as higher prevalence for these diseases. A clearer understanding of gender differences in relation to the association between obesity and chronic diseases would be helpful for reducing the social burden of chronic diseases in the elderly.

Thermoelectric and Transport Properties of Permingeatite Cu3SbSe4 Prepared Using Mechanical Alloying and Hot Pressing.

Permingeatite (Cu3SbSe4) is a promising thermoelectric material because it has a narrow band gap, large carrier effective mass, and abundant and nontoxic components. Mechanical alloying (MA), which is a high-energy ball mill process, has various advantages, e.g., segregation/evaporation is not required and homogeneous powders can be prepared in a short time. In this study, the effects of MA and hot-pressing (HP) conditions on the synthesis of the Cu3SbSe4 phase and its thermoelectric properties were evaluated. The electrical conductivity decreased with increasing HP temperature, while the Seebeck coefficient increased. The power factor (PF) was 0.38-0.50 mW m-1 K-2 and the thermal conductivity was 0.76-0.78 W m-1 K-1 at 623 K. The dimensionless figure of merit, ZT, increased with increasing temperature, and a reliable and maximum ZT value of 0.39 was obtained at 623 K for Cu3SbSe4 prepared using MA at 350 rpm for 12 h and HP at 573 K for 2 h.

Is Job Insecurity Worse for Mental Health Than Having a Part-time Job in Canada?

OBJECTIVES: A growing number of people depend on flexible employment, characterized by outsider employment status and perceived job insecurity. This study investigated whether there was a synergistic effect of employment status (full-time vs. part-time) and perceived job insecurity on major depressive disorder. METHODS: Data were derived from the 2012 Canadian Community Health Survey-Mental Health of 12 640 of Canada's labor force population, aged 20 to 74. By combining employment status with perceived job insecurity, we formed four employment categories: full-time secure, full-time insecure, part-time secure, and part-time insecure. RESULTS: Results showed no synergistic health effect between employment status and perceived job insecurity. Regardless of employment status (full-time vs. part-time), insecure employment was significantly associated with a high risk of major depressive disorder. Analysis of the interaction between gender and four flexible employment status showed a gender-contingent effect on this link in only full-time insecure category. Men workers with full-time insecure jobs were more likely to experience major depressive disorders than their women counterparts. CONCLUSIONS: This study's findings imply that perceived job insecurity may be a critical factor for developing major depressive disorder, in both men and women workers.

Analysis of the 2012 Canadian Community Health Survey-Mental Health demonstrates employment insecurity to be associated with mental illness.

ABSTRACT: A growing number of people depend on flexible employment, characterized by outsider employment and lower levels of job security. This study investigated whether there was a synergistic effect of employment status and job insecurity on mental disorders.This study used data from the 2012 Canadian Community Health Survey-Mental Health (CCHS) of 13,722 Canada's labor force population aged 20 to 70. Data were collected from January to December, 2012, using computer-assisted personal interviewing. As combining employment status with perceived job insecurity, we formed five job categories: secure full-time, full-time insecure, part-time secure, part-time insecure employment, and unemployment.Results showed that, regardless of employment status (full-time vs part-time), insecure employment was significantly associated with high risk of mental disorders. Furthermore, the odds ratios for insecure employment were similar to those for unemployment. Male workers who are full-time, but with insecure jobs, were more likely to experience mental disorders than female workers.This study's findings imply that while perceived job insecurity may be a critical factor for developing mental health problems among workers, providing effective health care services can mitigate an excessive health risk for the most vulnerable employment, especially for insecure part-time employment and unemployment.

Non-toxic sulfur inhibits LPS-induced inflammation by regulating TLR-4 and JAK2/STAT3 through IL-6 signaling.

Janus kinase 2 (JAK2) and STAT3 signaling is considered a major pathway in lipopolysaccharide (LPS)­induced inflammation. Toll­like receptor 4 (TLR­4) is an inflammatory response receptor that activates JAK2 during inflammation. STAT3 is a transcription factor for the pro­inflammatory cytokine IL­6 in inflammation. Sulfur is an essential element in the amino acids and is required for growth and development. Non­toxic sulfur (NTS) can be used in livestock feeds as it lacks toxicity. The present study aimed to inhibit LPS­induced inflammation in C2C12 myoblasts using NTS by regulating TLR­4 and JAK2/STAT3 signaling via the modulation of IL­6. The 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide assay was conducted to analyze cell viability and reverse transcription polymerase chain reaction and western blotting performed to measure mRNA and protein expression levels. Chromatin immunoprecipitation and enzyme­linked immunosorbent assays were used to determine the binding activity of proteins. The results indicated that NTS demonstrated a protective effect against LPS­induced cell death and inhibited LPS­induced expression of TLR­4, JAK2, STAT3 and IL­6. In addition, NTS inhibited the expression of nuclear phosphorylated­STAT3 and its binding to the IL­6 promoter. Therefore, NTS may be a potential candidate drug for the treatment of inflammation.

Area deprivation, individual socioeconomic position and smoking among women in South Korea.

BACKGROUND: The objective of this study was to examine how area deprivation and individual socioeconomic position affect smoking among women using national survey data. METHODS: Smoking and individual sociodemographic characteristics were gathered from the Third Korea National Health and Nutrition Examination Survey, 2005. The Carstairs index was derived for each area using the 2005 census data. The data were analysed using multilevel logistic regression models. RESULTS: After adjusting for age and marital status, low education and manual jobs were significantly associated with a higher likelihood of smoking. In addition, the effect of manual jobs on smoking was modified by area deprivation. When individual occupation and area deprivation were examined together, results indicated that women with manual occupation had much greater odds of smoking when they lived in the least-deprived areas (OR, 4.03; CI, 2.00 to 8.14) than did women with manual job who lived in the middle- or most-deprived areas (OR, 2.19; CI, 1.15 to 4.16), compared to the reference group (housewives in the middle- or most-deprived areas). CONCLUSION: The results of the present study show that among Korean women, manual work is associated with smoking, and the association is strongest among those living in the least-deprived areas. This interaction between manual work and area deprivation resulted in a higher smoking prevalence among women in affluent urban areas.

Chronic kidney disease and metabolic syndrome in a general Korean population: the Third Korea National Health and Nutrition Examination Survey (KNHANES III) Study.

BACKGROUND: The aims of this study are to examine the prevalence of chronic kidney disease (CKD) with metabolic syndrome (MS) and to investigate the association between CKD and MS after adjustment for socioeconomic position and health behavior factor. METHODS: The random sample used in this study included 5136 Korean subjects ≥20 years of age. We divided the subjects into two groups based on the presence of MS, for which the criteria described in the NCEP ATP III and International Diabetes Federation were used. Also, CKD was defined as an estimated glomerular filtration rate <60 ml/min/1.73 m(2). RESULTS: The prevalence of CKD in our study was 6.8%. The age-adjusted prevalence of CKD among those with MS was 9.0% whereas those without MS was 5.6%. After adjusting for age and confounders, people with MS had a 1.77 times greater risk of CKD than those without MS. The adjusted OR increased as the number of MS components increased (P < 0.05). CONCLUSION: The age-adjusted prevalence of CKD in the MS group was higher than that in the non-MS group. After adjustment for socioeconomic position and health behavior factor, MS showed significant association with CKD.

Case studies on employment-related health inequalities in countries representing different types of labor markets.

The authors selected nine case studies, one country from each cluster of their labor market inequalities typology, to outline the macro-political and economic roots of employment relations and their impacts on health. These countries illustrate variations in labor markets and health, categorized into a global empirical typology. The case studies illustrated that workers' health is significantly connected with labor market characteristics and the welfare system. For a core country, the labor market is characterized by a formal sector. The labor institutions of Sweden traditionally have high union density and collective bargaining coverage and a universal health care system, which correlate closely with positive health, in comparison with Spain and the United States. For a semi-periphery country, the labor market is delineated by a growing informal economy. Although South Korea, Venezuela, and El Salvador provide some social welfare benefits, a high proportion of irregular and informal workers are excluded from these benefits and experience hazardous working conditions that adversely affect their health. Lastly, several countries in the global periphery--China, Nigeria, and Haiti--represent informal work and severe labor market insecurity. In the absence of labor market regulations, the majority of their workers toil in the informal sector in unsafe conditions with inadequate health care.

Unemployment, informal work, precarious employment, child labor, slavery, and health inequalities: pathways and mechanisms.

The study explores the pathways and mechanisms of the relation between employment conditions and health inequalities. A significant amount of published research has proved that workers in several risky types of labor--precarious employment, unemployment, informal labor, child and bonded labor--are exposed to behavioral, psychosocial, and physio-pathological pathways leading to physical and mental health problems. Other pathways, linking employment to health inequalities, are closely connected to hazardous working conditions (material and social deprivation, lack of social protection, and job insecurity), excessive demands, and unattainable work effort, with little power and few rewards (in salaries, fringe benefits, or job stability). Differences across countries in the social contexts and types of jobs result in varying pathways, but the general conceptual model suggests that formal and informal power relations between employees and employers can determine health conditions. In addition, welfare state regimes (unionization and employment protection) can increase or decrease the risk of mortality, morbidity, and occupational injury. In a multilevel context, however, these micro- and macro-level pathways have yet to be fully studied, especially in middle- and low-income countries. The authors recommend some future areas of study on the pathways leading to employment-related health inequalities, using worldwide standard definitions of the different forms of labor, authentic data, and a theoretical framework.

Highly Flexible Graphene Derivative Hybrid Film: An Outstanding Nonflammable Thermally Conductive yet Electrically Insulating Material for Efficient Thermal Management.

In modern society, advanced technology has facilitated the emergence of multifunctional appliances, particularly, portable electronic devices, which have been growing rapidly. Therefore, flexible thermally conductive materials with the combination of properties like outstanding thermal conductivity, excellent electrical insulation, mechanical flexibility, and strong flame retardancy, which could be used to efficiently dissipate heat generated from electronic components, are the demand of the day. In this study, graphite fluoride, a derivative of graphene, was exfoliated into graphene fluoride sheets (GFS) via the ball-milling process. Then, a suspension of graphene oxide (GO) and GFSs was vacuum-filtrated to obtain a mixed mass, and subsequently, the mixed mass was subjected to reduction under the action hydrogen iodide at low temperature to transform the GO to reduced graphene oxide (rGO). Finally, a highly flexible and thermally conductive 30-µm thick GFS@rGO hybrid film was prepared, which showed an exceptional in-plane thermal conductivity (212 W·m-1·K-1) and an excellent electrical insulating property (a volume resistivity of 1.1 × 1011 Ω·cm). The extraordinary in-plane thermal conductivity of the GFS@rGO hybrid films was attributed to the high intrinsic thermal conductivity of the filler components and the highly ordered filler alignment. Additionally, the GFS@rGO films showed a tolerance to bending cycles and high-temperature flame. The tensile strength and Young's modulus of the GFS@rGO films increased with increasing the rGO content and reached a tensile strength of 69.3 MPa and a Young's modulus of 10.2 GPa at 20 wt % rGO. An experiment of exposing the films to high-temperature flame demonstrated that the GFS@rGO films could efficiently prevent fire spreading. The microcombustion calorimetry results indicated that the GFS@rGO had significantly lower heat release rate (HRR) compared to the GO film. The peak HRR of GFS@rGO10 was only 21 W·g-1 at 323 °C, while that of GO was 198 W·g-1 at 159 °C.

Non­toxic sulfur enhances growth hormone signaling through the JAK2/STAT5b/IGF­1 pathway in C2C12 cells.

Insulin­like growth factor­1 (IGF­1) regulates cell growth, glucose uptake and protein metabolism, and is required for growth hormone (GH) signaling­mediated insulin production and secretion. IGF1 expression is associated with STAT5, which binds to a region (TTCNNNGAA) of the gene. Although sulfur is used in various fields, the toxicity of this element is a significant disadvantage as it causes indigestion, vomiting, diarrhea, pain and migraine. Therefore, it is difficult to conduct in vitro experiments to directly determine the effects of dietary sulfur. Additionally, it is difficult to dissolve non­toxic sulfur (NTS). The present study aimed to identify the role of NTS in GH signaling as a Jak2/STAT5b/IGF­1 pathway regulator. MTT assay was used to identify an optimum NTS concentration for C2C12 mouse muscle cells. Western blotting, RT­PCR, chromatin immunoprecipitation, overexpression and small interfering RNA analyses were performed. NTS was dissolved in 1 mg/ml DMSO and could be used in vitro. Therefore, the present study determined whether NTS induced mouse muscle cell growth via GH signaling. NTS notably increased STAT5b binding to the Igf1 promoter. NTS also promoted GH signaling by upregulating GH receptor expression, similar to GH treatment. NTS enhanced GH signaling by regulating Jak2/STAT5b/IGF­1 signaling pathway factor expression in C2C12 mouse muscle cells. Thus, NTS may be used as a GH­enhancing growth stimulator.

Methylsulfonylmethane inhibits cortisol-induced stress through p53-mediated SDHA/HPRT1 expression in racehorse skeletal muscle cells: A primary step against exercise stress.

Cortisol is a hormone involved in stress during exercise. The application of natural compounds is a new potential approach for controlling cortisol-induced stress. Tumour suppressor protein p53 is activated during cellular stress. Succinate dehydrogenase complex subunit A (SDHA) and hypoxanthine phosphoribosyl transferase 1 (HPRT1) are considered to be two of the most stable reference genes when measuring stress during exercise in horses. In the present study cells were considered to be in a 'stressed state' if the levels of these stable genes and the highly stress responsive gene p53 were altered. It was hypothesized that a natural organic sulphur-containing compound, methylsulfonylmethane (MSM), could inhibit cortisol-induced stress in racing horse skeletal muscle cells by regulating SDHA, HPRT1 and p53 expression. After assessing cell viability using MTT assays, 20 µg/ml cortisol and 50 mM MSM were applied to horse skeletal muscle cell cultures. Reverse transcription-quantitative PCR and western blot analysis demonstrated increases in SDHA, HPRT1 and p53 expression in cells in response to cortisol treatment, which was inhibited or normalized by MSM treatment. To determine the relationship between p53 and SDHA/HPRT1 expression at a transcriptional level, horse gene sequences of SDHA and HPRT1 were probed to identify novel binding sites for p53 in the gene promoters, which were confirmed using a chromatin immunoprecipitation assay. The relationship between p53 and SDHA/HPRT1 expression was confirmed using western blot analysis following the application of pifithrin-α, a p53 inhibitor. These results suggested that MSM is a potential candidate drug for the inhibition of cortisol-induced stress in racehorse skeletal muscle cells.