Kyoung-Bok Min

The Impact of the Components of Metabolic Syndrome on Heart Rate Variability: Using the NCEP‐ATP III and IDF Definitions

Background: This study examined the relationship between metabolic syndrome (MetS) and heart rate variability (HRV) in Korean adults.

Serum lycopene, lutein and zeaxanthin, and the risk of Alzheimer's disease mortality in older adults.

Background: Oxidative stress is implicated in the pathogenesis of Alzheimers disease (AD). Accumulating evidence shows that antioxidant-rich food reduces the risk of AD by inhibiting oxidative stress. This study investigates whether serum levels of carotenoids were associated with the risk of AD mortality in a nationally representative sample of US adults. Methods: We used data from the Third Nutrition and Health Examination Survey (NHANES III) database and the NHANES III Linked Mortality File. A total of 6,958 participants aged older than 50 years were included in this study. Results: We found that high serum levels of lycopene and lutein+zeaxanthin at baseline were associated with a lower risk of AD mortality after adjustment for potential covariates. The reduction in the mortality risk was progressively raised by increasing serum lycopene (HR = 0.26, 95% CI 0.10-0.69) and lutein+zeaxanthin (HR = 0.43, 95% CI 0.22-0.85) levels. In contrast, no associations with AD mortality were observed for other serum carotenoids, including alpha-carotene, beta-carotene, and beta-cryptoxanthin. Conclusion: High serum levels of lycopene and lutein+zeaxanthin are associated with a lower risk of AD mortality in adults. Our findings suggest that a high intake of lycopene- or lutein+zeaxanthin-rich food may be important for reducing the AD mortality risk.

Association between Job Stress and Insomnia in Korean Workers

Association between Job Stress and Insomnia in Korean Workers: Hwan‐Cheol Kim, et al. Department of Occupational and Environmental Medicine, Inha University Hospital, Korea—

Exposure to environmental carbon monoxide may have a greater negative effect on cardiac autonomic function in people with metabolic syndrome

Carbon monoxide (CO) has been recognized as a risk factor for adverse cardiovascular outcomes. We investigated the effects of CO on cardiac autonomic function by measuring the heart rate variability (HRV) in patients with and without metabolic syndrome (MetS). We also explored the relationship between CO exposure and specific components of MetS. Data were obtained from air pollution measurements and from health examinations on a total of 986 subjects, from a Korean community. Measurements of the 5-min HRV and examinations for MetS were conducted, and a linear regression model with a time lag was evaluated for any association. The group with MetS showed a significant reduction in the standard deviation of the normal-to-normal intervals (SDNN) and in the high frequency domain of HRV. After adjusting for age, sex, smoking status, day of the week effect, month effect, temperature, and relative humidity, these declines were significantly associated with exposure to CO for 25 to 48 h prior to the HRV measurement. Evidence for effect-modification by two specific MetS components, fasting blood glucose and triglycerides, was also observed in relation to CO exposure. These results suggest that CO exposure may trigger changes in cardiac autonomic function, and that subjects at high risk for heart disease may be more susceptible to CO effects.

Precarious employment and the risk of suicidal ideation and suicide attempts

OBJECTIVE Although the effect of occupation or employment status on suicide risk is notable, there are few studies on the effect of precarious employment on suicide. We compared suicidal ideation and suicide attempts in precarious workers and their non-precarious counterparts using a representative sample from South Korea. METHOD The 2008 Korean Community Health Survey data were used for this study. Information was obtained on 52,161 participants (41,063 employees with non-precarious work and 11,098 employees with precarious work). The outcome of the logistic regression model was the presence of suicidal thoughts and attempts, and the independent variables were the demographics, socioeconomic status, and health status. RESULTS Employees with precarious work were more likely to exhibit suicidal ideation (OR=1.41; 95% CI, 1.28-1.55) and suicide attempts (OR=1.52; 95% CI, 1.02-2.27) than employees with non-precarious work. After controlling for income and education (Model 2) depressive feelings (Model 6), compared with unadjusted model, remained significant but the odds ratio was largely attenuated, indicating a strong association between suicidal risk and socioeconomic and feelings of depression. CONCLUSION Precarious workers had a higher risk of suicidal ideation and suicide attempts than non-precarious workers. Our study suggests that precarious employment is an important risk for suicide.

The Relationship Between Air Pollutants and Heart-Rate Variability Among Community Residents in Korea

Air pollution, both particulate and gaseous, is known to cause adverse health effects and is associated with increased cardiovascular mortality and morbidity. With a growing recognition in the importance of the autonomic nervous system in air pollution, we examined the effects of air pollutants, namely, particulate matter (PM10), sulfur dioxide (SO2), and nitric dioxide (NO2), on cardiac autonomic function by measuring heart-rate variability (HRV) among community residents. This study was conducted at Taein Island, located off the southern coast of South Korea; 1349 subjects (596 males and 753 females) were included in this analysis. Subjects responded to the interview about general characteristics and an HRV examination was conducted. Exposure data were collected from the Environmental Management Corporation during the same period of HRV measurement. Linear regression analyses were carried out to evaluate the association over 72 h, and the parameters of HRV indices were presented as the percentage change. The exposures to PM10, SO2, and NO2 were associated with reduced HRV indices, and significant decreases in the standard deviation of the normal to normal interval (SDNN) and low frequency (LF) domain effect, and the effect was largely continued until 12 h. Our results suggest that air pollutants stimulate the autonomic nervous system and provoke an imbalance in cardiac autonomic control. Thus, these subclinical effects may lead to pathological consequences, particularly in high-risk patients and susceptible subjects.

Lead and Cadmium Levels and Balance and Vestibular Dysfunction among Adult Participants in the National Health and Nutrition Examination Survey (NHANES) 1999-2004

Background: Few studies have been conducted to identify risk factors for balance and vestibular dysfunction in general populations, but previous studies have reported evidence of adverse effects of lead and cadmium on balance control in high-risk groups. Objective: We evaluated the relationship between blood lead and cadmium levels and balance and vestibular dysfunction in a general population study. Methods: We analyzed data from the 1999–2004 National Health and Nutrition Examination Survey (NHANES) of 5,574 adults ≥ 40 years of age. Balance dysfunction was evaluated by the Romberg Test of Standing Balance on Firm and Compliant Support Surfaces, which examines the ability to stand unassisted using four test conditions to evaluate vestibular system, vision, and proprioception inputs that contribute to balance. Blood levels of lead and cadmium were measured by atomic absorption spectrometry. Associations were estimated using logistic regression models adjusted for potential confounders. Associations with time to loss of balance were estimated using adjusted Cox proportional hazard models. Results: The adjusted odds ratio (OR) for balance dysfunction in association with the highest quintile (3.3–48 µg/dL) versus the lowest quintile (< 1.2 µg/dL) of lead was 1.42 [95% confidence interval (CI): 1.07, 1.89]. The corresponding OR for cadmium (0.9–7.4 µg/L vs. < 0.2 µg/L) was 1.27 (95% CI: 1.01, 1.60). The adjusted hazard ratio for time to failure for the most physiologically challenging balance test among subjects with the highest vs. lowest quintiles of blood lead was 1.24 (95% CI: 1.04, 1.48). Cadmium levels were not associated with time to failure. Conclusions: Our findings suggest that blood lead and cadmium levels may be associated with balance and vestibular dysfunction in a general sample of U.S. adults.

Serum carotenoid levels and risk of lung cancer death in US adults.

Lung cancer is one of the most common cancers worldwide and is the leading cause of cancer‐induced death in the USA. Although much attention has been focused on the anti‐carcinogenic effect of consuming carotenoid‐containing food or supplements, the results have been inconsistent. We investigated whether serum carotenoid levels were associated with the mortality risk of lung cancer in US adults using data from a nationally representative sample. The data were obtained from the Third Nutrition and Health Examination Survey (NHANES III) database and the NHANES III Linked Mortality File. A total of 10 382 participants aged over 20 years with available serum carotenoid levels and no other missing information on questionnaires and biomarkers at baseline (NHANES III) were included in the present study. Of the 10 382 participants, 161 subjects died due to lung cancer. We found that high serum levels of alpha‐carotene and beta‐cryptoxanthin at baseline were significantly associated with a lower risk of lung cancer death. When we stratified the risk by current smoking status, the risk of death of current smokers was significantly decreased to 46% (95% confidence interval, 31–94%) for alpha‐carotene and 61% (95% confidence interval, 19–80%) for beta‐cryptoxanthin. By contrast, no association was observed among never/former smokers at baseline. High serum levels of alpha‐carotene and beta‐cryptoxanthin are associated with a lower risk of lung cancer death in US adults.

Exposure–Response Relationship Between Aircraft Noise and Sleep Quality: A Community-based Cross-sectional Study

Objectives Exposure to aircraft noise has been shown to have adverse health effects, causing annoyance and affecting the health-related quality of life, sleep, and mental states of those exposed to it. This study aimed to determine sleep quality in participants residing near an airfield and to evaluate the relationship between the levels of aircraft noise and sleep quality. Methods Neighboring regions of a military airfield were divided into three groups: a high exposure group, a low exposure group, and a control group. A total of 1082 participants (aged 30–79 years) completed a comprehensive self-administered questionnaire requesting information about demographics, medical history, lifestyle, and the Pittsburgh Sleep Quality Index. Results Of the 1082 participants, 1005 qualified for this study. The prevalence of sleep disturbance was 45.5% in the control group, 71.8% in the low exposure group, and 77.1% in the high exposure group (p for trend < 0.001). After adjusting for potential confounding factors, we determined the exposure–response relationship between the degree of aircraft noise and sleep quality. Of the participants with a normal mental status, the prevalence of sleep disturbance was 2.61-fold higher in the low exposure group and 3.52-fold higher in the high exposure group than in the control group. Conclusion The relationship between aircraft noise and health should be further evaluated through a large-scale follow-up study.

Serum C-peptide levels and risk of death among adults without diabetes mellitus

Background: Connecting peptide (C-peptide) plays a role in early atherogenesis in patients with diabetes mellitus and may be a marker for cardiovascular morbidity and mortality in patients without diabetes. We investigated whether serum C-peptide levels are associated with all-cause, cardiovascular-related and coronary artery disease–related mortality in adults without diabetes. Methods: We used data from the Third Nutrition and Health Examination Survey (NHANES III) and the NHANES III Linked Mortality File in the United States. We analyzed mortality data for 5902 participants aged 40 years and older with no history of diabetes and who had available serum C-peptide levels from the baseline examination. We grouped the participants by C-peptide quartile, and we performed Cox proportional hazards regression analysis. The primary outcome was all-cause, cardiovascular-related and coronary artery disease–related mortality. Results: The mean serum C-peptide level in the study sample was 0.78 (± standard deviation 0.47) nmol/L. The adjusted hazards ratio comparing the highest quartile with the lowest quartile was 1.80 (95% confidence interval [CI] 1.33–2.43) for all-cause mortality, 3.20 (95% CI 2.07–4.93) for cardiovascular-related mortality, and 2.73 (95% CI 1.55–4.82) for coronary artery disease–related mortality. Higher C-peptide levels were associated with increased mortality among strata of glycated hemoglobin and fasting serum glucose. Interpretation: We found an association between serum C-peptide levels and all-cause and cause-specific mortality among adults without diabetes at baseline. Our finding suggests that elevated C-peptide levels may be a predictor of death.