Soo-Hun Cho

Effects of Ambient Air Pollution on Daily Mortality in a Cohort of Patients with Congestive Heart Failure

This study was planned to test the hypothesis that patients with congestive heart failure are more susceptible to the harmful effects of ambient air pollution than the general population. We used both general additive Poisson regression and the case-crossover approach to test the hypothesis. The effect of air pollution on daily mortality of patients with congestive heart failure among residents of Seoul, South Korea, during the period 1994–1998 was compared with that of the general population in the same area and the same period. The odds ratios and 95% confidence intervals (95% CIs) estimated from general additive models in the general population for an interquartile range increase of particulate matter less than 10 &mgr;m in diameter (42.1 &mgr;g/m3), carbon monoxide (0.59 ppm), nitrogen dioxide (14.6 ppb), sulfur dioxide (9.9 ppb), and ozone (20.5 ppb) were 1.014 (95% CI = 1.006–1.022), 1.022 (95% CI = 1.017–1.029), 1.021 (95% CI = 1.014–1.029), 1.020 (95% CI = 1.012–1.028), and 1.010 (95% CI = 1.002–1.017), respectively. The estimated effects appeared larger among the congestive heart failure patients than among the general population (2.5 ∼ 4.1 times higher depending on the pollutants). The results from the case-crossover analysis were similar. The finding of a stronger association in the patients with congestive heart failure reinforces the evidence that a harmful effect of air pollution is mediated by cardiovascular mechanisms.

Combined effect of glutathione S-transferase M1 and T1 genotypes on bladder cancer risk

To evaluate the association between genetic polymorphism of GSTM1, GSTT1 and development of bladder cancer, a hospital-based case-control study was conducted in South Korea. The study population consisted of 232 histologically confirmed male bladder cancer cases and 165 male controls enrolled from urology departments with no previous history of cancer or systemic diseases in Seoul during 1997-1999. The GSTM1 null genotype was significantly associated with bladder cancer (OR: 1.6, 95% CI: 1.0-2.4), whereas the association observed for GSTT1 null genotype did not reach statistical significance (OR: 1.3, 95% CI: 0.9-2.0). There was a statistically significant multiple interaction between GSTM1 and GSTT1 genotype for risk of bladder cancer (P=0.04); the risk associated with the concurrent lack of both of the genes (OR: 2.2, 95% CI: 1.2-4.3) was greater than the product of risk in men with GSTM1 null/GSTT1 present (OR: 1.3, 95% CI: 0.7-2.5) or GSTM1 present/GSTT1 null (OR: 1.1, 95% CI: 0.6-2.2) genotype combinations.

Correlation of Urinary 1-Hydroxypyrene and 2-Naphthol with Total Suspended Particulates in Ambient Air in Municipal Middle-School Students in Korea

Abstract The authors investigated Korean municipal middle school students to ascertain whether urinary 1-hydroxypyrene (1-OHP) and 2-naphthol–markers for polycyclic aromatic hydrocarbon (PAH) exposure–reflect PAHs in ambient air. The authors used the β-ray absorption method, which is an index of ambient-air PAH exposure, to collect total suspended participate (TSP) data. The authors measured urinary 1-OHP and 2-naphthol concentrations in 137 nonsmoking students in 4 municipal middle schools within 1 km of ambient air monitoring stations. The median concentrations of urinary 1-OHP and 2-naphthol in the study were 0.09 nmole/mol creatinine and 2.19 μmol/mol creatinine, respectively, and the geometric means were 0.10 nmole/mol creatinine and 2.47 μmol/mol creatinine, respectively. Urinary 1-OHP concentration did not correlate significantly with any TSP index. There were significant correlations between urinary 2-naphthol level and the daily mean TSP level calculated for 2 days before survey, for 1 day before survey, and for the day of survey. These data suggest that urinary 2-naphthol may be a good marker for inhalation exposure to PAHs in ambient air.

Formaldehyde exposure levels and serum antibodies to formaldehyde-human serum albumin of Korean medical students.

In our study, we estimated formaldehyde exposure levels of Korean medical students during their cadaver dissection practice hours. In addition, we examined the prevalence rates of formaldehyde-specific immunoglobulin E or immunoglobulin G antibodies and compared the results with the symptoms the students experienced as a result of formaldehyde exposure. There were 167 Korean medical students (i.e., subjects) aged 23.8+/-2.5 y (mean+/-standard deviation) and a control group of 67 premedical students aged 20.1+/-2.8 y (mean+/-standard deviation). Concentrations of formaldehyde in the cadaver dissection practice laboratory ranged from 0.194 to 11.245 mg/m3 (3.736+/-3.478 mg/m3 [mean+/-standard deviation]). Students reported by self-administered questionnaires that eye soreness (92.8%) and lacrimation (74.9%) were the most common symptoms they experienced during the laboratory sessions. One (0.6%) of the 167 medical students had a history of wheezing during dissection. Fourteen (8.4%) had specific immunoglobulin G antibody, but none had specific immunoglobulin E antibody. These results suggest that (a) Korean medical students are exposed to formaldehyde at a relatively high levels in their dissection practice hours, (b) specific immunoglobulin G is not related to adverse eye or respiratory symptoms, and (c) specific immunoglobulin E is rarely induced as a result of exposure to formaldehyde.

Long working hours and cardiovascular disease: a meta-analysis of epidemiologic studies.

Objective: To conduct a meta-analysis from published studies to evaluate the relationship between long working hours and the risk of cardiovascular disease (CVD). Methods: Among a total of 341 published studies found from publicly accessible databases, five cohort studies and six case–control studies were analyzed for the study. Results: Statistically significant heterogeneity has been observed (P = 0.037). The effect of longer working hours was significantly associated with the risk of CVD in the random-effects model of all 11 studies (odds ratio, 1.37; 95% confidence interval, 1.11 to 1.70). On the basis of meta-regression analysis, the result was not affected by the mean age, region, or the study year. The P value using Eager test was 0.701 suggesting this analysis was unlikely to have any publication bias. Conclusions: These findings provide evidence of increased CVD with long working hours.

Effects of environmental cadmium exposure on liver function in adults

Background There is inconsistency regarding the effects of cadmium exposure on liver function between the positive results found in animal studies and the negative results highlighted in epidemiological studies. We investigated whether environmental cadmium exposure is associated with an elevation in serum liver enzyme activity in Korean adults. Methods This cross-sectional study evaluated adult participants without liver disease from the Korean National Health and Nutrition Examination Survey for 2008–2009. Multiple linear regression was conducted to investigate the association between blood cadmium concentration and the serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) adjusting for age, sex, body mass index and the amount of alcohol consumption. Subjects were stratified into quartiles by their cumulative cadmium exposure rank. We estimated the multivariate-adjusted ORs for liver enzyme elevation using logistic regression models with the first quartile as the reference group. Results Total number of the subjects in the analysis was 3914. The blood cadmium concentrations were significantly associated with liver enzyme levels (AST, β=2.677, p value <0.0001; ALT, β=3.696, p value <0.0001; ALP, β=11.730, p value <0.0001). As the cadmium levels approached higher quartiles, the ORs for an elevated AST, ALT and ALP was increased significantly. Conclusions Environmental cadmium exposures are associated with an elevation in serum liver enzyme levels in Korean adults.

Ultrasound therapy facilitates the recovery of acute pressure-induced conduction block of the median nerve in rabbits.

Though the use of ultrasound for the treatment of carpal tunnel syndrome (CTS) or compression neuropathy has been described, its effect remains controversial. A test model of acute CTS was developed using rabbits. Acute median nerve compression was induced by the infusion of saline into the carpal tunnel under general anesthesia to elevate the intracarpal pressure. A reduction in the compound muscle action potential (CMAP) amplitude of the abductor pollicis was noted after intracarpal pressure increased. To investigate the efficacy of ultrasound in acute CTS, rabbits with acute median nerve compression were divided into 3 groups (10 each) and ultrasound was applied at different intensities to each group as follows: 1.5 W/cm2 to group 1; 0.2 W/cm2 to group 2; 0.0 W/cm2 (sham) to group 3. A total of 10 treatment sessions were given over a period of 2 weeks. Following ultrasound application, the CMAP amplitudes showed significant improvement in group 1 compared to the other two groups (P < 0.05), indicating facilitated recovery from acute CTS in this pressure‐induced median nerve compression rabbit model. The benefits of ultrasound application in a clinical setting must be verified by further clinical trials.

Urinary bisphenol A concentrations are associated with abnormal liver function in the elderly: a repeated panel study

Background Bisphenol A (4,40-isopropylidenediphenol, BPA) is known to adversely affect various organs. The liver is reported to be affected by BPA in animal studies. However, there are few studies in humans on the effects of BPA on the liver. Therefore, we evaluated the relationship between urinary BPA levels and liver function in elderly subjects using repeated measurements. Methods From 2008 to 2010, a total of 560 elderly subjects residing in Seoul were each evaluated up to three times. At the first visit, demographic data, environmental exposure and lifestyle information were obtained from a systemised questionnaire. At each visit, blood and urine samples were collected and stored for analysis. Linear mixed and GLIMMIX model analyses were performed after adjusting for age, sex, Body Mass Index, alcohol consumption, urinary cotinine concentrations, exercise frequency, and low-density lipoprotein cholesterol level. Results The mean urinary BPA concentration was 1.13 μg/g creatinine. Significant relationships were observed between urinary BPA and aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase after adjusting for potential confounders (p<0.05). When subjects were grouped according to urinary BPA concentrations divided by the median value, higher urinary BPA concentrations were associated with increased abnormal liver function (OR 2.66; 95% CI 1.15 to 5.90). Conclusions Community-level exposure to BPA was associated with abnormal liver function in the elderly, indicating that more stringent control of BPA is necessary to protect susceptible populations.

Glycophorin A mutant frequency in radiation workers at the nuclear power plants and a hospital

We studied to assess the validity of the glycophorin A (GPA) mutant assay as a biological marker of the cumulative effects of chronic low doses of ionizing radiation. In 144 nuclear power plants workers and 32 hospital workers, information on confounding factors, such as age and cigarette smoking, was obtained through a self-administered questionnaire. The information on physical exposure doses was obtained from the registries for radiation exposure monitoring and control at each facility. The range of cumulative exposure doses were 0-12.02cGy. GPA mutant assay was performed by the BR6 method with modification using a FACScan flow cytometer. Potential confounders, such as, age and cigarette smoking habits showed increasing trends with GPA variants, but were not of statistical significance. The hospital workers showed higher frequency of the GPA NO variant than nuclear power plant workers. Significant dose-response relationships were found between cumulative exposure to radiation and variants levels by simple and multiple linear regression models. The slope of regression equation of the dose-response of nuclear power plants workers was much smaller than that of hospital workers. These findings suggest that there may be dose-rate effects. In a population exposed to chronic low-dose radiation, the GPA assay shows potential to be used as an effective biologic marker for assessing the cumulative exposure dose although it could not be able to see a dose relation below 10cGy of cumulative exposure dose.

Dose-responsiveness of electrophysiologic change in a new model of acute carpal tunnel syndrome.

This study was done to determine the dose-responsiveness during the development of acute pressure-induced median neuropathy in rabbits and to develop a new animal model of acute carpal tunnel syndrome. Twenty-three rabbits were used. Carpal tunnel syndrome was induced by infusing a controlled saline solution into the carpal tunnel of rabbits using a 21-gauge needle under general anesthesia to elevate the carpal tunnel pressure. The changes in the amplitude and latency of the compound muscle action potential obtained by abductor pollicis recording were observed after a complete conduction block, and after the release of pressure at various pressure levels. Pressures greater than 30 mm Hg applied to the carpal tunnel caused a remarkable electrophysiologic change. A higher pressure level resulted in a shorter time required for a complete conduction block and also for recovery after the release of pressure. Complete conduction block occurred between 40 and 50 minutes at a pressure of 100 mm Hg. The degree of recovery after a conduction block was related inversely to the pressure-time integrals. Our animal model reflects the pathophysiology of acute carpal tunnel syndrome and shows a regular dose-responsiveness during the development of acute pressure-induced neuropathy.