Youn-Hee Lim

Air pollution and symptoms of depression in elderly adults.

Background: Although the effect of air pollution on various diseases has been extensively investigated, few studies have examined its effect on depression. Objectives: We investigated the effect of air pollution on symptoms of depression in an elderly population. Methods: We enrolled 537 participants in the study who regularly visited a community center for the elderly located in Seoul, Korea. The Korean version of the Geriatric Depression Scale-Short Form (SGDS-K) was used to evaluate depressive symptomatology during a 3-year follow-up study. We associated ambient air pollutants with SGDS-K results using generalized estimating equations (GEE). We also conducted a factor analysis with items on the SGDS-K to determine which symptoms were associated with air pollution. Results: SGDS-K scores were positively associated with interquartile range (IQR) increases in the 3-day moving average concentration of particulate matter with an aerodynamic diameter ≤ 10 μm (PM10) [17.0% increase in SGDS-K score, 95% confidence interval (CI): 4.9%, 30.5%], the 0–7 day moving average of nitrogen dioxide [NO2; 32.8% (95% CI: 12.6%, 56.6%)], and the 3-day moving average of ozone [O3; 43.7% (95% CI: 11.5%, 85.2%)]. For these three pollutants, factor analysis showed that air pollution was more strongly associated with emotional symptoms such as feeling happy and satisfied than with somatic or affective symptoms. Conclusions: Our study suggests that increases in PM10, NO2, and O3 may increase depressive symptoms among the elderly. Of the symptoms evaluated, ambient air pollution was most strongly associated with emotional symptoms.

Associations of Bisphenol A Exposure With Heart Rate Variability and Blood Pressure

Bisphenol A (BPA) is a high-volume production chemical that has been suspected to have adverse health effects. Recent studies have suggested that cardiovascular diseases are associated with the BPA exposure. The aim of present study was to investigate the associations of urinary BPA with heart rate variability and blood pressure. We recruited 560 noninstitutionalized elderly citizens from August 2008 to August 2010 in Seoul. All of the participants were ≥60 years old. The participants took medical examinations ⩽5 times. Urinary BPA concentration, heart rate variability, and blood pressure were measured at each time. A total of 1511 observations from 521 participants were included in the analyses. We observed that urinary BPA was associated negatively with the root mean square of successive differences for heart rate and positively with blood pressure. The odds ratio of showing hypertension (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg) was 1.27 (95% CI, 0.85–1.88) in the fourth quartile compared with the first quartile of urinary BPA concentration. When the analyses were restricted to participants who did not report previous history of hypertension (n=258), the odds ratio was increased to 2.35 (95% CI, 1.33–4.17).

Ceramic bioactivity: progresses, challenges and perspectives

Bioactivity is a property of the ceramic surface which induces biological integration of living soft and hard tissues. The core mechanism of bioactivity is surface biomineralization of calcium phosphate nanocrystallites on ceramics with specific compositions and structures, inspiring acellular and cellular strategies for bio-interactive materials with new physical, chemical and biological functions. These include bioactive surface functionalizations on metallic, ceramic and polymeric substrata for biomedical materials with different mechanical properties, bioactive ceramic-polymer nanohybrids for soft tissue replacements and engineering, template-textured depositions of biomimetic nano-calcium phosphate for hybridization of bio-macromolecular and cellular functions, concerning which this paper reviews with in vivo and in vitro fundamentals and perspectives in tissue engineering.

Effects of diurnal temperature range on cardiovascular and respiratory hospital admissions in Korea.

The effects of heat and cold waves have been studied as risk factors for cardiovascular and respiratory diseases. However, few studies have examined the effect of diurnal temperature changes on health. We hypothesized that the diurnal temperature range (DTR) may affect the rate of hospital admissions for cardiovascular- and respiratory-related diseases, and therefore investigated the risk of hospital admissions of cardiovascular (stroke, myocardial infarction, ischemic heart disease, cardiac failure, cardiac disease, and arrhythmia) and respiratory (asthma, chronic obstructive pulmonary disease, and pneumonia) diseases attributable to DTR in four metropolitan areas in Korea during 2003-2006. The area-combined effects of DTR on some cardiovascular and respiratory diseases were significantly increased by an increment of DTR. In particular, the effects on cardiac failure and asthma were significant with the percentage change of hospital admissions per 1 °C increment of DTR at 3.0% (95% CI, 1.4-4.6) and 1.1% (95% CI, 0.1-2.0), respectively, among 9 diseases. For those 75 years and older, the DTR effect on asthma admissions was greater than in those aged under 75 years. These results support the hypothesis of a positive association between DTR and cardiovascular and respiratory hospital admission.

Modifiers of diurnal temperature range and mortality association in six Korean cities

Rapid temperature changes within a single day may be critical for populations vulnerable to thermal stress who have difficulty adjusting themselves behaviorally and physiologically. We hypothesized that diurnal temperature range (DTR) is associated with mortality, and that this association is modified by season and socioeconomic status (SES). We evaluated meteorological and mortality data from six metropolitan areas in Korea from 1992 to 2007. We applied generalized linear models (GLM) for quantifying the estimated effects of DTR on mortality after adjusting for mean temperature, dew point temperature, day of the week, and seasonal and long-term trends. Most areas showed a linear DTR–mortality relationship, with evidence of increasing mortality with increasing DTR. Deaths among the elderly (75xa0years or older), females, the less educated, and the non-hospital population were associated more strongly with DTR than with the corresponding categories. DTR was the greatest threat to vulnerable study populations, with greater influence in the fall season. DTR was found to be a predictor of mortality, and this relationship was modified by season and SES.

Diethylhexyl Phthalates Is Associated with Insulin Resistance via Oxidative Stress in the Elderly: A Panel Study

Background Insulin resistance (IR) is believed to be the underlying mechanism of metabolic syndrome and type 2 diabetes mellitus (DM). Recently, a few studies have demonstrated that phthalates could cause oxidative stress which would contribute to the development of IR. Therefore, we evaluated whether exposure to phthalates affects IR, and oxidative stress is involved in the phthalates-IR pathway. Methods We recruited 560 elderly participants, and obtained blood and urine samples during repeated medical examinations. For the determination of phthalate exposure, we measured urinary levels of mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) as metabolites of diethylhexyl phthalates (DEHP), and mono-n-butyl phthalate (MnBP) as a metabolite of di-butyl phthalate (DBP). Malondialdehyde (MDA), an oxidative stress biomarker, was also measured in urine samples. We measured serum levels of fasting glucose and insulin, and derived the homeostatic model assessment (HOMA) index to assess IR. A mixed-effect model and penalized regression spline were used to estimate the associations among phthalate metabolites, MDA, and IR. Results The molar sum of MEHHP and MEOHP (∑DEHP) were significantly associated with HOMA (βu200a=u200a0.26, Pu200a=u200a0.040), and the association was apparent among participants with a history of DM (βu200a=u200a0.88, Pu200a=u200a0.037) and among females (βu200a=u200a0.30, Pu200a=u200a0.022). However, the relation between MnBP and HOMA was not found. When we evaluated whether oxidative stress is involved in increases of HOMA by ∑DEHP, MDA levels were significantly associated with increases of ∑DEHP (βu200a=u200a0.11, P<0.001) and HOMA (βu200a=u200a0.49, Pu200a=u200a0.049). Conclusions Our study results suggest that exposure to DEHP in the elderly population increases IR, which is related with oxidative stress, and that participants with a history of DM and females are more susceptible to DEHP exposure.

Short-term exposure to fine and coarse particles and mortality: A multicity time-series study in East Asia.

Few studies on size-specific health effects of particulate matter have been conducted in Asia. We examined the association between both fine and coarse particles (PM2.5 and PM10-2.5) and mortality across 11 East Asian cities from 4 countries (Korea, Japan, Taiwan, and China). We performed a two-stage analysis: we generated city-specific estimates using a time-series analysis with a generalized additive model (Quasi-Poisson distribution), and estimated the overall effects by conducting a meta-analysis. Each 10-μg/m(3) increase in PM2.5 (lag01) was associated with an increase of 0.38% (95% confidence intervalxa0=xa00.21%-0.55%) in all causes mortality, 0.96% (0.46%-1.46%) in cardiovascular mortality, and 1% (0.23%-1.78%) in respiratory mortality. Each 10-μg/m(3) increase in PM10-2.5 (lag01) was associated with cardiovascular mortality (0.69%, [0.05%-1.33%]), although this association attenuated after controlling for other pollutants, especially PM2.5. Increased mortality was associated with increasing PM2.5 and PM10-2.5 concentrations over 11 East Asian cities.

Renal Hyperfiltration as a Novel Marker of All-Cause Mortality

Although renal hyperfiltration (RHF) or an abnormal increase in GFR has been associated with many lifestyles and clinical conditions, including diabetes, its clinical consequence is not clear. RHF is frequently considered to be the result of overestimating true GFR in subjects with muscle wasting. To evaluate the association between RHF and mortality, 43,503 adult Koreans who underwent voluntary health screening at Seoul National University Hospital between March of 1995 and May of 2006 with baseline GFR≥60 ml/min per 1.73 m(2) were followed up for mortality until December 31, 2012. GFR was estimated with the Chronic Kidney Disease Epidemiology Collaboration creatinine equation, and RHF was defined as GFR>95th percentile after adjustment for age, sex, muscle mass, and history of diabetes and/or hypertension medication. Muscle mass was measured with bioimpedance analysis at baseline. During the median follow-up of 12.4 years, 1743 deaths occurred. The odds ratio of RHF in participants with the highest quartile of muscle mass was 1.31 (95% confidence interval [95% CI], 1.11 to 1.54) compared with the lowest quartile after adjusting for confounding factors, including body mass index. The hazard ratio of all-cause mortality for RHF was 1.37 (95% CI, 1.11 to 1.70) by Cox proportional hazards model with adjustment for known risk factors, including smoking. These data suggest RHF may be associated with increased all-cause mortality in an apparently healthy population. The possibility of RHF as a novel marker of all-cause mortality should be confirmed.

Variation in mortality of ischemic and hemorrhagic strokes in relation to high temperature

Outdoor temperature has been reported to have a significant influence on the seasonal variations of stroke mortality, but few studies have investigated the effect of high temperature on the mortality of ischemic and hemorrhagic strokes. The main study goal was to examine the effect of temperature, particularly high temperature, on ischemic and hemorrhagic strokes. We investigated the association between outdoor temperature and stroke mortality in four metropolitan cities in Korea during 1992–2007. We used time series analysis of the age-adjusted mortality rate for ischemic and hemorrhagic stroke deaths by using generalized additive and generalized linear models, and estimated the percentage change of mortality rate associated with a 1°C increase of mean temperature. The temperature-responses for the hemorrhagic and ischemic stroke mortality differed, particularly in the range of high temperature. The estimated percentage change of ischemic stroke mortality above a threshold temperature was 5.4xa0% (95xa0% CI, 3.9–6.9xa0%) in Seoul, 4.1xa0% (95xa0% CI, 1.6–6.6xa0%) in Incheon, 2.3xa0% (−0.2 to 5.0xa0%) in Daegu and 3.6xa0% (0.7–6.6xa0%) in Busan, after controlling for daily mean humidity, mean air pressure, day of the week, season, and year. Additional adjustment of air pollution concentrations in the model did not change the effects. Hemorrhagic stroke mortality risk significantly decreased with increasing temperature without a threshold in the four cities after adjusting for confounders. These findings suggest that the mortality of hemorrhagic and ischemic strokes show different patterns in relation to outdoor temperature. High temperature was harmful for ischemic stroke but not for hemorrhagic stroke. The risk of high temperature to ischemic stroke did not differ by age or gender.

Mortality Related to Extreme Temperature for 15 Cities in Northeast Asia

Background: Multisite time-series studies for temperature-related mortality have been conducted mainly in the United States and Europe, but are lacking in Asia. This multisite time-series study examined mortality related to extreme temperatures (both cold and hot) in Northeast Asia, focusing on 15 cities of 3 high-income countries. Methods: This study includes 3 cities in Taiwan for 1994–2007, 6 cities in Korea for 1992–2010, and 6 cities in Japan for 1972–2009. We used 2-stage Bayesian hierarchical Poisson semiparametric regression to model the nonlinear relationship between temperature and mortality, providing city-specific and country-wide estimates for cold and heat effects. Various exposure time frames, age groups, and causes of death were considered. Results: Cold effects had longer time lags (5–11 days) than heat effects, which were immediate (1–3 days). Cold effects were larger for cities in Taiwan, whereas heat effects were larger for cities in Korea and Japan. Patterns of increasing effects with age were observed in both cold and heat effects. Both cold and heat effects were larger for cardiorespiratory mortality than for other causes of death. Several city characteristics related to weather or air pollution were associated with both cold and heat effects. Conclusions: Mortality increased with either cold or hot temperature in urban populations of high-income countries in Northeast Asia, with spatial variations of effects among cities and countries. Findings suggest that climate factors are major contributors to the spatial heterogeneity of effects in this region, although further research is merited to identify other factors as determinants of variability.