Kai Jen Chuang

Long-term air pollution exposure and risk factors for cardiovascular diseases among the elderly in Taiwan.

Objectives To investigate changes in blood pressure, blood lipids, blood sugar and haematological markers of inflammation associated with changes in long-term exposure to ambient air pollutants. Methods We conducted secondary analyses of data on blood pressure and blood biochemistry markers from the Social Environment and Biomarkers of Aging Study in Taiwan and air pollution data from the Taiwan Environmental Protection Administration in 2000. Associations of 1-year averaged criteria air pollutants (particulate matter with aerodynamic diameters <10 μm (PM10) and <2.5 μm (PM2.5), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide and carbon monoxide) with systolic blood pressure, diastolic blood pressure, total cholesterol, triglycerides, high-density lipoprotein cholesterol, fasting glucose, haemoglobin A1c (HbA1c), interleukin 6 (IL-6) and neutrophils were explored by applying generalised additive models. Results After controlling for potential confounders, we observed that increased 1-year averaged particulate air pollutants (PM10 and PM2.5) and NO2 were associated with elevated blood pressure, total cholesterol, fasting glucose, HbA1c, IL-6 and neutrophils. Associations of increased 1-year averaged O3 with elevated blood pressure, total cholesterol, fasting glucose, HbA1c and neutrophils were also observed. In particular, our two-pollutant models showed that PM2.5 was more significantly associated with end-point variables than two gaseous pollutants, O3 and NO2. Conclusions Changes in blood pressure, blood lipids, blood sugar and haematological markers of inflammation are associated with long-term exposure to ambient air pollutants. This might provide a link between air pollution and atherosclerotic cardiovascular diseases.

Personal exposure to submicrometer particles and heart rate variability in human subjects

We conducted a study on two panels of human subjects—9 young adults and 10 elderly patients with lung function impairments—to evaluate whether submicrometer particulate air pollution was associated with heart rate variability (HRV). We measured these subjects’ electrocardiography and personal exposure to number concentrations of submicrometer particles with a size range of 0.02–1 μm (NC0.02–1) continuously during daytime periods. We used linear mixed-effects models to estimate the relationship between NC0.02–1 and log10-transformed HRV, including standard deviation of all normal-to-normal intervals (SDNN), square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD), low frequency (LF, 0.04–0.15 Hz), and high frequency (HF, 0.15–0.40 Hz), adjusted for age, sex, body mass index, tobacco exposure, and temperature. For the young panel, a 10,000-particle/cm3 increase in NC0.02–1 with 1–4 hr moving average exposure was associated with 0.68–1.35% decreases in SDNN, 1.85–2.58% decreases in r-MSSD, 1.32–1.61% decreases in LF, and 1.57–2.60% decreases in HF. For the elderly panel, a 10,000-particle/cm3 increase in NC0.02–1 with 1–3 hr moving average exposure was associated with 1.72–3.00% decreases in SDNN, 2.72–4.65% decreases in r-MSSD, 3.34–5.04% decreases in LF, and 3.61–5.61% decreases in HF. In conclusion, exposure to NC0.02–1 was associated with decreases in both time-domain and frequency-domain HRV indices in human subjects.

Effects of Particle Size Fractions on Reducing Heart Rate Variability in Cardiac and Hypertensive Patients

It is still unknown whether the associations between particulate matter (PM) and heart rate variability (HRV) differ by particle sizes with aerodynamic diameters between 0.3 μm and 1.0 μm (PM0.3–1.0), between 1.0 μm and 2.5 μm (PM1.0–2.5), and between 2.5 μm and 10 μm (PM2.5–10). We measured electrocardiographics and PM exposures in 10 patients with coronary heart disease and 16 patients with either prehypertension or hypertension. The outcome variables were standard deviation of all normal-to-normal (NN) intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD), low frequency (LF; 0.04–0.15 Hz), high frequency (HF; 0.15–0.40 Hz), and LF:HF ratio for HRV. The pollution variables were mass concentrations of PM0.3–1.0, PM1.0–2.5, and PM2.5–10. We used linear mixed-effects models to examine the association between PM exposures and log10-transformed HRV indices, adjusting for key personal and environmental attributes. We found that PM0.3–1.0 exposures at 1- to 4-hr moving averages were associated with SDNN and r-MSSD in both cardiac and hypertensive patients. For an interquartile increase in PM0.3–1.0, there were 1.49–4.88% decreases in SDNN and 2.73–8.25% decreases in r-MSSD. PM0.3–1.0 exposures were also associated with decreases in LF and HF for hypertensive patients at 1- to 3-hr moving averages except for cardiac patients at moving averages of 2 or 3 hr. By contrast, we found that HRV was not associated with either PM1.0–2.5 or PM2.5–10. HRV reduction in susceptible population was associated with PM0.3–1.0 but was not associated with either PM1.0–2.5 or PM2.5–10.

Associations between particulate sulfate and organic carbon exposures and heart rate variability in patients with or at risk for cardiovascular diseases.

Objective: It is still unknown whether specific components in fine particles are associated with heart rate variability (HRV) reduction. Methods: We recruited 46 patients with or at risk for cardiovascular diseases to measure 24-hour HRV by ambulatory electrocardiographic monitoring. Fixed-site air-monitoring stations were used to represent participants’ exposures to particles with aerodynamic diameters less than 10 &mgr;m (PM10) and 2.5 &mgr;m (PM2.5), and particulate components of sulfate, nitrate, organic carbon (OC) and elemental carbon, and gaseous pollutants. Results: We found that HRV reduction was associated with sulfate, OC, and PM2.5 but not with the other five pollutants in single-pollutant models. Sulfate was found to remain in significant association with HRV reduction adjusting for OC and PM2.5 in three-pollutant models. Conclusions: Exposures to sulfate and OC in PM2.5 were associated with HRV reduction in patients with or at risk for cardiovascular diseases.

Association between nitrogen dioxide and heart rate variability in a susceptible population

Background Panel studies have shown a consistent association between changes in the cardiac autonomic nervous system with particulate matters (PM) but less with gaseous pollutants. This study examined the linkage between nitrogen dioxide (NO2) and heart rate variability (HRV) in a susceptible population. Methods We recruited a panel of 83 patients from the National Taiwan University Hospital Cardiology Clinic to measure their 24-h HRV by ambulatory electrocardiography. Thirty-nine patients had coronary heart disease (CHD) and another 44 patients had more than one major CHD risk factor. Ambient concentrations of NO2, sulphur dioxide (SO2), carbon monoxide (CO), ozone, and PM less than 10μm in diameter (PM10) at each participants close-by monitoring station were used to represent study participants’ exposures. We used linear mixed-effects models to analyse the association between individual air pollutants and log10-transformed HRV, with key personal and environmental attributes and co-pollutants being adjusted. Results We found that an increase in 10 ppb NO2 at 4-h to 8-h moving averages was associated with 1.5–2.4% decreases in the standard deviation of all normal-to-normal intervals (SDNN) in our participants. For every 10 ppb NO2 at 5 and 7-h moving averages, our participants’ low frequency was decreased by 2.2 and 2.5%, respectively. In contrast, HRV was not associated with PM10, CO, SO2, or O3. Conclusion Increasing NO2 exposure was found to be associated with decreasing SDNN and low frequency in susceptible populations.

Respiratory symptoms among residents of a heavy-industry province in China: Prevalence and risk factors

OBJECTIVE In China, significant levels of environmental pollution, substandard worksite quality and high rates of smoking predispose the population to potentially high risks of respiratory illnesses and other diseases. We assessed the prevalence of respiratory symptoms and their risks in relation to personal, occupational and environmental risk factors in a heavy-industry province of northeastern China. METHODS Lifestyle, health, residential and occupational data were obtained in 2002 from 31,704 adults of six cities in Liaoning, China, using self-assessment questionnaires. General linear and multi-level models were used to evaluate prevalence rates and risks of respiratory symptoms, related to both individual and combined exposures to environmental and occupational risk factors. RESULTS The crude prevalence rates (PRs) for persistent cough, persistent phlegm, wheeze and asthma were 2.3, 3.8, 2.1 and 1.0%, respectively. The odds ratios (ORs) of all four respiratory symptoms examined were increased by: smoking (ORs from 2.06 to 5.02), occupational dust (ORs from 1.35 to 1.72), occupational gas (ORs from 1.48 to 1.72) and presence of irritating smoke during cooking (ORs from 1.54 to 2.22). An index combining proximity of residence to road, factory or chimney, indoor coal use and presence of irritating smoke during cooking was associated with up to 3.9-fold increased risks of all symptoms. Increasing values of each risk factor were generally associated with dose-response trends in prevalence rates and risks (all p for trend <0.01). CONCLUSION The crude PRs of symptoms were lower than those reported by European and American studies but closer to those of previous Chinese studies. The risks of respiratory symptoms in this population were increased by smoking, occupational exposures to dust and gas, and combined residence-related exposures such as living close to a main road, factory or chimney, indoor coal use and the presence of irritating smoke during cooking, among other risk factors.

Comparative proteomics of inhaled silver nanoparticles in healthy and allergen provoked mice

Background Silver nanoparticles (AgNPs) have been associated with the exacerbation of asthma; however, the immunological basis for the adjuvant effects of AgNPs is not well understood. Objective The aim of the study reported here was to investigate the allergic effects of AgNP inhalation using proteomic approaches. Methods Allergen provoked mice were exposed to 33 nm AgNPs at 3.3 mg/m3. Following this, bronchoalveolar lavage fluid (BALF) and plasma were collected to determine protein profiles. Results In total, 106 and 79 AgNP-unique proteins were identified in the BALF of control and allergic mice, respectively. Additionally, 40 and 26 AgNP-unique proteins were found in the plasma of control and allergic mice, respectively. The BALF and plasma protein profiles suggested that metabolic, cellular, and immune system processes were associated with pulmonary exposure to AgNPs. In addition, we observed 18 proteins associated with systemic lupus erythematosus that were commonly expressed in both control and allergic mice after AgNP exposure. Significant allergy responses were observed after AgNP exposure in control and allergic mice, as determined by ovalbumin-specific immunoglobulin E. Conclusion Inhaled AgNPs may regulate immune responses in the lungs of both control and allergic mice. Our results suggest that immunology is a vital response to AgNPs.

Personal Exposure to Household Particulate Matter, Household Activities and Heart Rate Variability among Housewives

Background The association between indoor air pollution and heart rate variability (HRV) has been well-documented. Little is known about effects of household activities on indoor air quality and HRV alteration. To investigate changes in HRV associated with changes in personal exposure to household particulate matter (PM) and household activities. Methods We performed 24-h continuous monitoring of electrocardiography and measured household PM exposure among 50 housewives. The outcome variables were log10-transformed standard deviation of normal-to-normal (NN) intervals (SDNN) and the square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD). Household PM was measured as the mass concentration of PM with an aerodynamic diameter <2.5 µm (PM2.5). We used mixed-effects models to examine the association between household PM2.5 exposure and log10-transformed HRV indices. Results After controlling for potential confounders, an interquartile range change in household PM2.5 with 1- to 4-h mean was associated with 1.25–4.31% decreases in SDNN and 0.12–3.71% decreases in r-MSSD. Stir-frying, cleaning with detergent and burning incense may increase household PM2.5 concentrations and modify the effects of household PM2.5 on HRV indices among housewives. Conclusions Indoor PM2.5 exposures were associated with decreased SDNN and r-MSSD among housewives, especially during stir-frying, cleaning with detergent and burning incense.

Physicochemical and biological characterization of single-walled and double-walled carbon nanotubes in biological media

To study the toxicity of nanoparticles under relevant conditions, it is important to reproducibly disperse nanoparticles in biological media in in vitro and in vivo studies. Here, single-walled nanotubes (SWNTs) and double-walled nanotubes (DWNTs) were physicochemically and biologically characterized when dispersed in phosphate-buffered saline (PBS) and bovine serum albumin (BSA). BSA-SWNT/DWNT interaction resulted in a reduction of aggregation and an increase in particle stabilization. Based on the protein sequence coverage and protein binding results, DWNTs exhibited higher protein binding than SWNTs. SWNT and DWNT suspensions in the presence of BSA increased interleukin-6 (IL-6) levels and reduced tumor necrosis factor-alpha (TNF-α) levels in A549 cells as compared to corresponding samples in the absence of BSA. We next determined the effects of SWNTs and DWNTs on pulmonary protein modification using bronchoalveolar lavage fluid (BALF) as a surrogate collected form BALB/c mice. The BALF proteins bound to SWNTs (13 proteins) and DWNTs (11 proteins), suggesting that these proteins were associated with blood coagulation pathways. Lastly, we demonstrated the importance of physicochemical and biological alterations of SWNTs and DWNTs when dispersed in biological media, since protein binding may result in the misinterpretation of in vitro results and the activation of protein-regulated biological responses.

In-car particles and cardiovascular health: An air conditioning-based intervention study

Exposure to traffic-related particulate matter (PM) is considered a potential risk for cardiovascular events. Little is known about whether improving air quality in car can modify cardiovascular effects among human subjects during commuting. We recruited a panel of 60 healthy subjects to commute for 2 h by a car equipped with an air conditioning (AC) system during the morning rush hour in Taipei. Operation modes of AC system using outside air (OA-mode), circulating inside air (IA-mode) and turning off (Off-mode) were examined. Repeated measurements of heart rate variability (HRV) indices, PM≤2.5 μm in aerodynamic diameter (PM2.5) and noise level were conducted for each participant in different modes during the commute. We used linear mixed-effects models to associate HRV indices with in-car PM2.5. We found that decreases in HRV indices were associated with increased levels of in-car PM2.5. For Off-mode, an interquartile range (IQR) increase in in-car PM2.5 with 15-min moving average was associated with 2.7% and 4.1% decreases in standard deviation of NN intervals (SDNN) and the square root of the mean of the sum of the squares of differences between adjacent NN intervals (r-MSSD), respectively. During OA and IA modes, participants showed slight decreases in SDNN (OA mode: 0.1%; IA mode: 1.3%) and r-MSSD (OA mode: 1.1%; IA mode: 1.8%) by an IQR increase in in-car PM2.5 with 15-min moving average. We concluded that in-car PM2.5 is associated with autonomic alteration. Utilization of the cars AC system can improve air quality and modify the effects of in-car PM2.5 on HRV indices among human subjects during the commute.