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Biomedical subjects

Chang-Chuan Chan

Publications and source records attributed to Chang-Chuan Chan.

At least 19 recordsLinked to original sources
PubMed2024

Long-term PM2.5 exposure is associated with asthma prevalence and exhaled nitric oxide levels in children.

BACKGROUND: Exhaled nitric oxide concentration (FENO) is a marker of airway inflammation. This study aimed to evaluate the association of air pollution exposure with FENO levels and asthma prevalence with respiratory symptoms in school children. METHODS: We analyzed 4736 school children who reside in six townships near industrial areas in central Taiwan. We evaluated asthmatic symptoms, FENO, and conducted the environmental questionnaire. The personal exposure of PM2.5, NO, and SO2 was estimated using land-use regression models data on children's school and home addresses. RESULTS: Annual exposure to PM2.5 was associated with increased odds of physician-diagnosed asthma (OR&#x2009;=&#x2009;1.595), exercise-induced wheezing (OR&#x2009;=&#x2009;1.726), itchy eyes (OR&#x2009;=&#x2009;1.417), and current nasal problems (OR&#x2009;=&#x2009;1.334) (P&#x2009;<&#x2009;0.05). FENO levels in the absence of infection were positively correlated with age, previous wheezing, allergic rhinitis, atopic eczema, near the road, and for children with high exposure to PM2.5 (P&#x2009;<&#x2009;0.05). An increase of 1 &#x3bc;g/m3 PM2.5 exposure was significantly associated with a 1.0% increase in FENO levels for children after adjusting for potential confounding variables, including exposures to NO and SO2. CONCLUSIONS: Long-term exposures to PM2.5 posed a significant risk of asthma prevalence and airway inflammation in a community-based population of children. IMPACT: Annual exposure to PM2.5 was associated with increased odds of physician-diagnosed asthma and nasal problems and itchy eyes. Long-term exposures to PM2.5 were significantly associated with FENO levels after adjusting for potential confounding variables. This is first study to assess the association between FENO levels and long-term air pollution exposures in children near coal-based power plants. An increase of 1 &#x3bc;g/m3 annual PM2.5 exposure was significantly associated with a 1.0% increase in FENO levels. Long-term exposures to PM2.5 posed a significant risk of asthma prevalence and airway inflammation in a community-based population of children.

Humans↗
PubMed2006

Urban air pollution and emergency admissions for cerebrovascular diseases in Taipei, Taiwan.

AIMS: This study was designed to evaluate the association between urban air pollutants and emergency admissions for cerebrovascular diseases. METHODS AND RESULTS: Daily emergency admissions for cerebrovascular diseases (ICD-9-CM, 430-437) to the National Taiwan University Hospital were regressed against daily concentrations of carbon monoxide (CO), nitrogen dioxide (NO(2)), sulphur dioxide (SO(2)), ozone (O(3)), and particulate matters with aerodynamic diameter <2.5 (PM(2.5)) and 10 microm (PM(10)) from 12 April 1997 to 31 December 2002 in Taipei metropolitan areas by the Poisson regression models adjusting for meteorological conditions and temporal trends. Single-pollutant models showed O(3) lagged 0 day, CO lagged 2 days, and PM(2.5) and PM(10) lagged 3 days were significantly associated with increasing emergency admissions for cerebrovascular diseases and CO lagged 2 days was significantly associated with increasing emergency admissions for strokes (ICD-9-CM, 430-434). Such association remained significant for O(3), CO, and cerebrovascular admissions after adjusting for PM(2.5) and PM(10) in two-pollutant models. The odds ratios were 1.021-1.022 per 31.3 ppb O(3) and 1.023-1.031 per 0.8 ppm CO, respectively. However, only CO was significantly associated with emergency admissions for stroke in the three-pollutant models with CO, O(3), and PM(2.5) or PM(10). CONCLUSION: Emergency admissions for cerebrovascular diseases among adults were positively associated with increasing urban air pollution levels of O(3) lagged 0 day and CO lagged 2 days in Taipei.

Aged↗
PubMed2006

Workplace air quality and lung function among dental laboratory technicians.

BACKGROUND: Dental laboratory technicians are exposed to dust and/or methyl methacrylate (MMA) in the workplace. Potential effects of the exposures on lung function merit further clarification. METHODS: This study measured lung function of 45 dental technicians, before and after shifts, on 3 workdays and monitored workplace concentrations of particulate matter with aerodynamic diameter less than 2.5 mm (PM2.5) and MMA in five dental laboratories in Taiwan. Base metals in particles were analyzed by X-ray fluorescence. Repeated measurement analysis was applied to estimate potential effects of PM2.5 on pulmonary function. RESULTS: PM2.5 ranged from 26 microg/m3 to 664 microg/m3 and levels of MMA were low in these laboratories. Nickel, cobalt, and chromium were detected in the particles. After controlling for important factors, PM2.5 was associated with a small decrease in forced vital capacity and forced expiratory flow in one second. CONCLUSION: Workplace PM2.5 was associated with a non-significant decrease in lung function of dental technicians.

Air Pollution, Indoor↗
PubMed2006

Exhaled carbon monoxide level as an indicator of cigarette consumption in a workplace cessation program in Taiwan.

BACKGROUND: Smoking cessation programs are critical to the safety and health of workers. Exhaled carbon monoxide (CO) is an effective indicator of smoking in clinics and hospitals. Its application in the community and workplace, however, remains limited. This study assessed whether exhaled CO concentration can be used as an objective indicator of the amount of daily cigarette consumption among smokers in the workplace in Taiwan. METHODS: A total of 150 workers from a chemical manufacturer in Taiwan were included; there were 27 nonsmokers and 123 current smokers. The number of cigarettes smoked daily by each subject was reported, and exhaled CO concentration was measured in each subject using the Micro CO meter (Micro Medical Ltd, Chatham, Kent, UK). RESULTS: Exhaled CO levels were associated with the number of cigarettes consumed daily, with a correlation coefficient of 0.73 (p < 0.01) and an adjusted R-square (simple linear regression model) of 0.44. The mean exhaled CO level of nonsmokers was 4.2 ppm (95% confidence interval, 3.3-5.1). A reading of > 6 ppm had a sensitivity of 84% and specificity of 85% in detecting workplace smoking. CONCLUSION: Exhaled CO level can be used as an objective, noninvasive indicator to determine the smoking status of an individual in the workplace.

Adult↗
PubMed2006

Urban air pollution increases plasma fibrinogen and plasminogen activator inhibitor-1 levels in susceptible patients.

BACKGROUND: The cardiovascular effects on fibrinolytic activity by urban air pollution are still unknown. METHODS: Paired fasting blood samples during high and low air pollution days in Taipei were taken from a panel of 49 patients with coronary heart disease or multiple risk factors to study their fibrinolytic and inflammatory response to urban air pollution. Paired t-tests and mixed-effects models were used to determine the air pollution effects. RESULTS: Patients' plasma plasminogen activator inhibitor-1 levels were significantly increased when hourly concentrations of particulate matter with diameters less than 10 microm (PM10) were greater than 100 microg/m during the period 0800 to 1800 h. CONCLUSION: Urban air pollution has an adverse effect on plasma fibrinolytic function in a susceptible population.

Adult↗
PubMed2006

Grand rounds: outbreak of hematologic abnormalities in a community of people exposed to leakage of fire extinguisher gas.

CONTEXT: Although there are ample data on the respiratory effects of exposure to fire extinguisher gas, the potential hematologic effects have not been fully documented. We conducted this study to determine the possible etiologic agent(s) for a decrease in red blood cells among community residents in Taipei, Taiwan, after they were exposed to leakage of mixed fire extinguishants containing bromotrifluoromethane (CF3Br, Halon 1301), bromochlorodifluoromethane (CF2BrCl, Halon 1211), and dichlorodifluoromethane (CCl2F2, CFC-12). CASE PRESENTATION: We studied 117 exposed residents who came into one hospital for physical examinations. We also selected age- and sex-matched referents for comparison from residents who came to the same hospital for health examinations. Nine months after the exposure to mixed fire extinguishants, 91 of the exposed residents came back for a second physical examination. In the first examination of the exposed residents, we found a significant reduction in red blood cell count and hemoglobin and a relationship between dose and response. DISCUSSION: After excluding iron-deficiency anemia, thalassemia, and other possible agents, we suspected that the hematologic effects might have resulted from pyrolytic products of CFC-12 and Halon 1211, which may contain phosgene, among other products. RELEVANCE TO CLINICAL PRACTICE: The acute transient hematologic effects observed in the exposed residents were associated with the incident of leakage of mixed fire-extinguisher gases and were most likely caused by a small amount of pyrolytic products, probably phosgene. Nine months after the exposure, we found a significant improvement in the abnormalities without any specific treatment.

Adult↗
PubMed2005

Workers' exposures and potential health risks to air toxics in a petrochemical complex assessed by improved methodology.

OBJECTIVE: This study was designed to comprehensively evaluate workers' potential health risks of exposure to 39 air toxics in the Ta-sher Petrochemical Complex. METHODS: Open-Path Fourier Transform Infrared Spectroscopy (OP-FTIR) was used to measure concentrations of air toxics. We used the measured worksite concentrations between 1997 and 1999 at 11 companies in the petrochemical complex, employing 3,100 on-site workers. The 39 measured air toxics included 10 chemicals with acute reference exposure levels (RELa), 19 chemicals with chronic reference exposure levels (RELc), and 3 chemicals classified as Class 1 or 2A human carcinogens by the International Agency for Research on Cancer (IARC). We then used RELa to calculate the hazard index of acute health effects (HI ( A )) for workers in individual plants. We also calculated the hazard index of chronic health effects (HIc) and cancer risks for all workers in the entire petrochemical complex. RESULTS: Workers in five companies had HI ( A ) greater than 1 because of toluene, benzene, methyl ethyl ketone, chloroform and isopropanol exposures. Workers in this petrochemical complex had HIc greater than 1 because of acrylonitrile, 1,3-butadiene, hydrogen cyanide, and n,n-dimethylformamide exposures. Risk of hematopoietic system cancer because of benzene and ethylene oxide exposure, and respiratory system cancer because of 1,3-butadiene exposure was estimated to be 3.1-6.1 x 10(-4) and 5.2-7.1 x 10(-4), respectively. CONCLUSIONS: Our findings indicated that workers in the petrochemical complex might have excess cancer and noncancer risks due to acute or chronic exposures to air toxics from multiple emission sources.

Air Pollutants↗
PubMed2005

Health information system for community-based multiple screening in Keelung, Taiwan (Keelung Community-based Integrated Screening No. 3).

BACKGROUND: Community-based multiple screening for common cancers and chronic diseases has increasingly gained attention. However, as infrastructure and evaluation system are more diversified and complicated compared with single screening, the development of a novel health information system is paramount. METHODS: The main goal of our health information system was to support the multiple screening program not only from technical aspect but also from a broad range of perspectives including quality assurance system, organized features appertaining to screening, economic evaluation (cost-effectiveness or cost-utility analysis), epidemiological applications, behavior risk factor surveillance system, and social impact due to the introduction of the Keelung Community-Based Integrated Screening (KCIS) program. RESULTS: Health information system was designed and programmed on the basis of the demand derived from KCIS within which five cancers and three chronic diseases were included. In addition to the detailed description of infrastructure and process, design, relevant database and security involved in health information system, an innovative and extensive evaluation system in accordance with the main goals was included in our health information system. CONCLUSION: Our information system proposed several aspects regarding organized screening system that has never been addressed in computerized system supporting for single screening. These included quality assurance system, organization features, co-morbidity profiles, epidemiological applications and social and economic considerations.

Community Health Services↗
PubMed2005

Reduction of post-shift traffic injuries among gasoline station workers: Are they related to the reduction of occupational gasoline vapor exposure?

AIMS: Solvents exposure is known to impair psychomotor performances. With gasoline vapor recovery devices (GVRD) installed, this study should observe a decrease of traffic injuries after shift among gasoline workers. METHODS: The occupational injury registry data of 1991-2000 in a petrochemical company containing 20,000 workers were analyzed. Cumulative injury rate (CIR) was calculated to estimate lifetime risk. The potential workday loss (PWDL) and the potential salary loss (PSL), which summed up the expected workdays and salary loss assuming a uniform retirement age of 65, were calculated for traffic injuries. Workers of gasoline sales were compared with those without gasoline exposure for commuting traffic injuries. The rate ratio (RR) was calculated based on a person-time data. RESULTS: The CIR dropped 3.14 times during 1997-2000 for commuting accidents on the way back home compared with that during 1991-1992, and the PWDL and PSL dropped 25.2 and 21.5 times, respectively, which corresponded with the time of installments of GVRD. The RRs of commuting accidents on the way back home in the exposed group significantly decreased from 2.15 to 0.53. CONCLUSIONS: The decrease of commuting injuries on journey back home for gasoline workers were probably related to the effective reduction of solvent exposure.

Accidents, Traffic↗
PubMed2005

Enhanced oxidative stress and endothelial dysfunction in streptozotocin-diabetic rats exposed to fine particles.

The association between ambient particulate matter (PM) and cardiovascular diseases has been demonstrated in epidemiological studies. Recent studies suggest that diabetic patients are at greater risk for PM-associated cardiovascular events. Although diabetes and PM exposure individually have been reported to be associated with increased oxidative stress, inflammation, and endothelial dysfunction, it is not clear whether PM may induce synergistic interaction effects on these parameters in diabetics. Strepotozotocin-induced diabetic (n=4) and healthy (n=4) rats were intratracheally administered with PM2.5 collected from a busy traffic area in a dose of 200 microg suspended in 0.5 mL phosphate-buffered saline (PBS). The same number of rats was exposed to PBS as controls. Cell and differential counts and protein and lactate dehydrogenase activity were determined in bronchoalveolar lavage. Markers of 8-hydroxydeoxy-guanosine (8-OHdG), endothelin-1 (ET-1), and [nitrate+nitrite], an indicator of nitric oxide (NO) production, in addition to C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in peripheral blood were also determined. Our results showed that diabetic rats were associated with increased 8-OHdG, IL-6, and ET-1 decreased [nitrate+nitrite]. In nondiabetic rats PM exposure was also associated with increased 8-OHdG, IL-6, TNF-alpha, and CRP but decreased [nitrate+nitrite]. Interestingly, increases of 8-OHdG and ET-1 after PM exposure were more prominent in diabetic rats than in nondiabetic rats. The general linear model further indicated that there were interactions between diabetes and PM on 8-OHdG (P<0.01) and ET-1 (P=0.08). We suggest that PM exposure may enhance the risk of cardiovascular diseases through interaction between PM and diabetes on excess reactive oxygen species generation and endothelial dysfunction. These findings provide further support for previous epidemiological studies.

Animals↗
PubMed2005

Saved by a material safety data sheet.

BACKGROUND: We present the case of a young female laboratory worker who developed acute hepatic encephalopathy. OBJECTIVE: To show that knowledge of occupational exposures to causative agents can alter therapeutic management. METHODS: Although the patient was in a deep coma, her family members examined the workplace material safety data sheet, revealing exposure to chloroform. Since most chemical-induced hepatitis is self-limiting, a scheduled liver transplantation was postponed. RESULTS: The patient recovered. Subsequent air sampling suggested that the patient had been exposed to chloroform at a concentration of more than 15 ppm for 2 weeks. CONCLUSION: Our case report demonstrates the importance of obtaining an occupational history and how the patient's family can be important in this process.

Adult↗
PubMed2005

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 10 microm in diameter (PM10) at each participant's 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.

Adult↗
PubMed2005

Associations between submicrometer particles exposures and blood pressure and heart rate in patients with lung function impairments.

OBJECTIVE: The objective of this study was to evaluate whether submicrometer particle is associated with elevated blood pressure (BP) and heart rate (HR). METHODS: We measured ambulatory systolic BP (SBP), diastolic BP (DBP), and HR using a portable BP monitoring system and number concentrations of submicrometer particle with a size range of 0.02 to 1 microm (NC0.02-1) by a P-TRAK Ultrafine Particle Counter for 10 patients with lung function impairments. RESULTS: We found NC0.02-1 exposures at 1- to 3-hour moving averages were associated with the elevation of SBP, DBP, and HR. There were 1.4 to 3.4-mm-Hg increases in SBP, 1.4 to 2.2-mm-Hg increases in DBP, and 0.3 to 3.5-beats/min increases in HR for 10,000 particles/cm increases in NC0.02-1 at 1- to 3-hour moving averages. CONCLUSIONS: Exposures to submicrometer particles were associated with short-term increases in BP and HR in patients with lung function impairments.

Adult↗
PubMed2005

Effects of ambient ozone exposure on mail carriers' peak expiratory flow rates.

The extent to which occupational exposure to ozone in ambient air can affect lung function remains unclear. We conducted a panel study in 43 mail carriers by measuring their peak expiratory flow rates (PEFRs) twice daily for 6 weeks in 2001. The daily exposure of each mail carrier to O3, particulate matter < 10 microm in aerodynamic diameter (PM10), and nitrogen dioxide was estimated by one air monitoring station in the center of the mail carrier's delivery area. Hourly concentrations of air pollutants during their exposure periods were 6-96 ppb for O3, 11-249 microg/m3 for PM10, and 14-92 ppb for NO2. Linear mixed-effects models were used to estimate the association between air pollution exposures and PEFR after adjusting for subject's sex, age, and disease status and for temperature and humidity. We found that night PEFR and the deviation in night PEFR were significantly decreased in association with 8-hr O3 exposures with a lag 0-2 days and by daily maximum O3 exposures with a lag of 0-1 day in our multipollutant models. By contrast, neither PM10 nor NO2 was associated with a PEFR reduction. Daily 8-hr mean concentrations of O3 had greater reduction effects on PEFR than did daily maximum concentrations. For a 10-ppb increase in the 8-hr average O3 concentration, the night PEFR was decreased by 0.54% for a 0-day lag, 0.69% for a 1-day lag, and 0.52% for a 2-day lag. We found that an acute lung function reduction occurs in mail carriers exposed to O3 concentrations below current ambient air quality standards and occupational exposure limits.

Adult↗
PubMed2005

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 microm and 1.0 microm (PM(0.3-1.0)), between 1.0 microm and 2.5 microm (PM(1.0-2.5)), and between 2.5 microm and 10 microm (PM(2.5-10)). 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 PM(0.3-1.0), PM(1.0-2.5), and PM(2.5-10). 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 PM(0.3-1.0) 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 PM(0.3-1.0), there were 1.49-4.88% decreases in SDNN and 2.73-8.25% decreases in r-MSSD. PM(0.3-1.0) 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 PM(1.0-2.5) or PM(2.5-10). HRV reduction in susceptible population was associated with PM(0.3-1.0) but was not associated with either PM(1.0-2.5) or PM(2.5-10).

Aged↗
PubMed2005

Effects of concentrated ambient particles on heart rate variability in spontaneously hypertensive rats.

In the present study, the cardiovascular toxicity of PM(2.5) was determined in spontaneously hypertensive (SH) rats using the standard deviation of normal-to-normal intervals (SDNN) and root mean square of successive differences of adjacent normal-to-normal intervals (RMSSD) as outcome measurements. Four SH rats implanted with radiotelemetry transmitters were repeatedly exposed to concentrated PM(2.5) in nose-only exposure chambers. Gravimetric analysis revealed the mean post-concentrating mass concentration of particles during the 5 h of exposure was 202 mug/m(3). Using each animal as its own control and linear mixed-effects model, to adjust for circadian nature and individual differences, we found that SDNN decreased by 15% initially then gradually decreased to 60% of the initial value at the end of exposure. Our results indicate that concentrated PM(2.5) may decrease SDNN on SH rats during PM exposure. The study also showed that SDNN is more sensitive to PM induced effects than RMSSD.

Air Pollutants↗
PubMed2004

An in vitro short time-high dose drug exposure assay for predicting 5FU-resistance of colorectal cancer.

The goal of this study was to develop a simple and rapid in vitro drug resistance assay to ascertain the effectiveness of 5-fluorouracil (5-FU) for the individual therapy of colorectal cancer. Colorectal cancer cells were isolated from tumor specimens and, after 4h exposure to high doses of 5-FU cell viability was measured with an ATP assay. The average IC50 concentration for 5-FU was calculated as 4000 microg/ml from 35 patients' tumors. The tumor cells were defined as extreme drug resistance with a survival rate 1 standard deviation (SD) over IC50, low drug resistance (LDR) with a survival rate 1 SD below IC50, and intermediate drug resistance (IDR) with survival rate between these two. The drug resistant assay for 102 patients' cancer cells showed that the proportion of patients with LDR to 5-fluorouracil was 19%. The in vitro drug resistance of the cancer cells was not correlated with cancer stages or by patient sex or age. However, most mucinous and poor differentiated cancer cells showed extreme or IDR. The in vitro ATP assay values for 25 Duke's D patients receiving postoperative 5-FU chemotherapy were comparable with clinical postchemotherapy responses. The sensitivity and specificity of the assay were 100 and 95%, respectively. This short time-high dose drug exposure assay may serve as an aid to improve 5-FU treatment for individual chemotherapy.

Adenosine Triphosphate↗