Jung-Duck Park

Chung-Ang University, Sŏul, Seoul, South Korea

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Publications (33)76.57 Total impact

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    ABSTRACT: Cadmium (Cd) is a metal that is toxic to renal tubules. If renal tubules are damaged by Cd, urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) and beta 2-microglobulin (β2-MG) increases. The aim of this study was to describe the changing patterns of urinary Cd, NAG, and β2-MG levels over a 3-year period in individuals living in a Cd-contaminated area. This follow-up study included 191 residents (65.6 ± 9.3 years) who were living in the vicinity of a copper refinery. Urinary levels of Cd, NAG activity, and β2-MG levels were measured, and their determinants and changing patterns were analyzed statistically. The natural logarithm of urinary Cd levels decreased significantly over time. Sex and intake of locally cultivated rice were significant determinants of urinary Cd concentration. Urinary NAG activity decreased over time. Age and urinary Cd concentration were significant determinants of urinary NAG activity in subjects with urinary Cd concentrations >5 μg/g creatinine. In subjects whose urinary Cd concentrations were >2 μg/g creatinine, diabetes was found to be a significant risk factor for high urinary NAG activity. The slope for temporal changes in urinary β2-MG levels was negative in subjects whose urinary Cd levels were <2 μg/g creatinine but was positive in those whose urinary Cd levels were 2–5 μg/g creatinine or >5 μg/g creatinine. The urinary β2-MG levels found in individuals whose urinary Cd levels were >2 μg/g creatinine suggest that previous Cd-induced renal tubular damage had occurred.
    Environmental Toxicology and Pharmacology. 11/2014;
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    ABSTRACT: The purpose of this study was to investigate demographic and lifestyle variables and blood cadmium concentrations in residents living near abandoned metal mines in Korea. Blood cadmium concentrations were measured in 15,161 subjects living around abandoned metal mines (exposed group, n = 14,464) and compared with those living in designated control areas (control group, n = 697). A questionnaire was provided to all subjects to determine age, gender, mine working history, times of residence, smoking habits and dietary water type. The geometric mean (95% confidence intervals) of blood cadmium concentration (1.25 [1.24-1.27] µg/L) in the exposed group was significantly higher than in the control group (1.17 [1.13-1.22] µg/L). Mean residence time and mine working history in the exposed group were significantly higher than in the control group. Blood cadmium concentrations increased with increasing age, and residence time in both groups, and blood cadmium concentrations were higher in current-smokers than in non-smokers in both groups. This study shows the geometric mean of blood cadmium concentration in abandoned mining areas are higher than in non-mining areas in the general adult Korean population.
    Epidemiology 05/2014; 29(5):633-9. · 5.74 Impact Factor
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    ABSTRACT: We analyzed national data on blood lead levels (BLL) and blood cadmium levels (BCL) in residents living near 38 abandoned metal mining areas (n = 5,682, 18-96 years old) in Korea that were collected by the first Health Effect Surveillance for Residents in Abandoned Metal mines (HESRAM) from 2008 to 2011. The geometric mean BCL and BLL were 1.60 μg/L (95 % CI = 1.57-1.62 μg/L) and 2.87 μg/dL (95 % CI = 2.84-2.90 μg/dL), respectively, notably higher than levels in the general population in Korea and other countries. We found significantly higher BLL and BCL levels in people living within 2 km of an abandoned metal mine (n = 3,165, BCL = 1.87 μg/L, BLL = 2.91 μg/dL) compared to people living more than 2 km away (n = 2,517, BCL = 1.31 μg/L, BLL = 2.82 μg/dL; P < 0.0001) and to the general population values reported in the literature.
    Environmental Monitoring and Assessment 04/2014; · 1.68 Impact Factor
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    ABSTRACT: Malondialdehyde (MDA), used as an oxidative stress marker, is commonly assayed by measuring the thiobarbituric acid reactive substances (TBARS) using HPLC, as an indicator of the MDA concentration. Since the HPLC method, though highly specific, is time-consuming and expensive, usually it is not suitable for the rapid test in large-scale environmental epidemiologic surveys. The purpose of this study is to develop a simple and rapid method for estimating TBARS levels by using a multiple regression equation that includes TBARS levels measured with a microplate reader as an independent variable. Twelve hour urine samples were obtained from 715 subjects. The concentration of TBARS was measured at three different wavelengths (fluorescence: λ-ex 530 nm and λ-ex 550 nm; λ-ex 515 nm and λ-ex 553 nm; and absorbance: 532 nm) using microplate reader as well as HPLC. 500 samples were used to develop a regression equation, and the remaining 215 samples were used to evaluate the validity of the regression analysis. The induced multiple regression equation is as follows: TBARS level (μM) = -0.282 + 1.830 × (TBARS level measured with a microplate reader at the fluorescence wavelengths λ-ex 530 nm and λ-em 550 nm, μM) -0.685 × (TBARS level measured with a microplate reader at the fluorescence wavelengths λ-ex 515 nm and λ-em 553 nm, μM) + 0.035 × (TBARS level measured with a microplate reader at the absorbance wavelength 532 nm, μM). The estimated TBARS levels showed a better correlation with, and are closer to, the corresponding TBARS levels measured by HPLC compared to the values obtained by the microplate method. The TBARS estimation method reported here is simple and rapid, and that is generally in concordance with HPLC measurements. This method might be a useful tool for monitoring of urinary TBARS level in environmental epidemiologic surveys with large sample sizes.
    Toxicological research. 03/2014; 30(1):7-11.
  • Dong-Kyeong Kim, Jung-Duck Park, Byung-Sun Choi
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    ABSTRACT: According to a recent study, mercury (Hg) exposure contributes to Alzheimer's disease (AD). However, the underlying mechanisms are not understood. This study investigated the effect of methylmercury (MeHg) treatment on the generation, degradation, and transport of amyloid β-protein (Aβ) in the brain. Wistar rats were administered MeHg by gavage (0, 20, 200, and 2,000 μg Hg/kg/day) for 4 weeks. The total Hg in the blood and brain regions was measured, and the levels of Aβ42 in plasma, cerebrospinal fluid (CSF), and brain regions were estimated. The expression of amyloid precursor protein (APP), beta-site APP-cleaving enzyme 1 (BACE1), and neprilysin (NEP) in the brain regions was determined, in addition to the expression of low-density lipoprotein receptor-related protein 1 (LRP1) and the receptor for advanced glycation end products (RAGE) in the brain capillary endothelium (BCE). Finally, the amount of soluble low-density lipoprotein receptor-related protein (sLRP) in the plasma was determined. Aβ42 levels were decreased in the CSF of the 2,000 μg Hg/kg/day group compared with controls, and Aβ42 levels increased in the hippocampus (HC) in a dose-dependent manner. MeHg decreased LRP1 expression but increased RAGE levels in BCE. sLRP levels were decreased in the plasma of the MeHgtreated rats. They were positively correlated with CSF Aβ42 and negatively correlated with Aβ42 and Hg levels in HC. These results imply that MeHg reduces the transportation of Aβ, thereby resulting in the accumulation of the protein in the HC. Plasma sLRP levels may be an early biomarker of Hg-induced Aβaccumulation in the brain.
    The Journal of Toxicological Sciences 01/2014; 39(4):625-35. · 1.38 Impact Factor
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    ABSTRACT: This study aimed to estimate the risks for renal tubular damage and osteoporosis in individuals with long-term environmental Cd exposure. This cross-sectional study comprised 1,086 residents living in the vicinity of a copper refinery plant. As the urinary Cd levels increased, the proportion of female subjects with β2-MG ≥ 300 μg/g creatinine also increased significantly, but this was not observed in the male subjects. The prevalence of osteoporosis was significantly higher in men with urinary Cd >5 μg/g creatinine than in those with urinary Cd ≤5 μg/g creatinine. This difference was not observed in the corresponding female groups. The association between increased urinary excretion of β2-MG and decreased BMD was statistically significant only in the female subjects. We suggest that an increased Cd body burden directly decreases the BMD in male subjects; however, in female subjects, it first induces renal microtubular damage, which can lead to osteoporosis.
    Environmental Toxicology and Pharmacology. 01/2014;
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    ABSTRACT: Mercury (Hg) is a nonessential and toxic metal that is widely distributed in the environment. This study was performed to estimate the representative blood Hg level, to determine the contributing factors to Hg exposure, and to analyze the association of blood Hg with metabolic syndrome in Korean adults. Mercury exposure is assessed by total Hg concentration in blood. A total of 2,114 healthy adults who have not been exposed to Hg occupationally were sampled by the multistaged, sex-, and age-stratified probability method. Information was collected regarding the subjects' demographic characteristics, lifestyles, and past medical history. The participants then underwent physical examination and blood sampling. The geometric mean concentration of Hg in whole blood was 3.90 μg/L, which was significantly influenced by sex, age, smoking, alcoholic consumption, residence area, and seafood intake after adjustment for confounders. Significant increases in body mass index, waist circumference, diastolic blood pressure, total cholesterol, and triglyceride were observed according to the blood Hg levels after adjustment for covariates. Also, Hg exposure was significantly associated with metabolic syndrome and their components such as obesity and increased fasting glucose. The blood Hg level in Korean adults is higher than that in USA and other Western countries, while it is similar to or lower than that in other Asian countries. The blood Hg level is influenced by sociodemographic factors and individual lifestyles including dietary habits. Furthermore, blood Hg is associated with metabolic syndrome, in which Hg exposure may play a role as a possible risk factor for cardiovascular diseases.
    International Archives of Occupational and Environmental Health 07/2013; · 2.10 Impact Factor
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    ABSTRACT: Arsenic (As) is a well-known human carcinogen and its dietary exposure has been found to be the major route of entry into general population. This study was performed to assess the body levels of As and their associated factors in Korean adults by analyzing total As in urine. Urine and blood samples were collected from 580 adults aged 20 years and older, who had not been exposed to As occupationally. Demographic information was collected with the help of a standard questionnaire, including age, smoking, alcohol intake, job profiles, and diet consumed in the last 24 hrs of the study. Total As, sum of As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), in urine was determined using atomic absorption spectrometer involving hydride generation method. The geometric mean concentration of total As in urine was 7.10 μg/L. Urine As was significantly higher in men (7.63 μg/L) than in women (6.75 μg/ L). Age, smoking, alcohol consumption, and job profiles of study subjects did not significantly affect the concentration of As in urine. No significant relationship was observed between body mass index (BMI), Fe, and total cholesterol in serum and urinary As. Urine As level was positively correlated with seaweeds, fishes & shellfishes, and grain intake. A negative correlation between urinary As level and HDL-cholesterol in serum and meat intake was observed. Overall, these results suggest that urinary As concentration could be affected by seafood consumption. Therefore, people who frequently consume seafood and grain need to be monitored for chronic dietary As exposure.
    Toxicological research. 06/2013; 29(2):137-142.
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    ABSTRACT: Little is yet known about the determinants of bone mineral density (BMD) in young adults. Thus, in this study, we aimed to determine the factors that have an impact on BMD in young men. Questionnaires were sent out to 111 male medical students. Information on age, socio-economic status, medical history, lifestyle, physical activity during adolescence, school club participation, current physical activity, and dietary intake were collected by the survey. Height, weight, percent body fat and muscle mass were estimated by bioelectrical impedance, and BMD was obtained using calcaneal quantitative ultrasound. Using the Poisson regression model, prevalence ratios (PRs) were used to estimate the degree of association between risk factors and osteopenia. The height and current physical activity showed a correlation to the Osteoporosis Index. Among the categorized variables, past physical activity during adolescence (p=0.002) showed a positive effect on the bone mineral content. In the multivariate model, past physical activity (≥1 time/wk) had a protective effect on osteopenia (PR, 0.37; 95% confidence interval [CI], 0.18 to 0.75) and present physical activity (1000 metabolic equivalent of task-min/wk) decreased the risk of osteopenia (PR, 0.64; 95% CI, 0.44 to 0.91). Past physical activity during adolescence is as important as physical activity in the present for BMD in young men.
    Journal of preventive medicine and public health = Yebang Ŭihakhoe chi. 03/2013; 46(2):89-95.
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    ABSTRACT: Di(2-ethylhexyl) phthalate (DEHP) is one of the common phthalate plasticizers used primarily in soft polyvinyl chloride, which is a plastic polymer that makes up the total weight of goods from 1% up to 40% in many consumer products. The aims of this study were to examine the urinary DEHP metabolites in South Korean children and to investigate the correlation between mother and child DEHP urine excretion. Three kinds of urinary DEHP metabolites: mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (5-OH-MEHP) and mono(2-ethyl-5-oxohexyl) phthalate (5-oxo-MEHP), were analyzed. The total of 954 samples (n(Children)=392, n(Mothers)=265, n(Aadults)=297), including 258 mother and child pairs, were analyzed using isotope dilution gas chromatography-mass spectrometry. Many studies present higher concentration of DEHP metabolites detected from adults in reproductive age than adults in other ages. Therefore, adults who are age-matched to mothers were evaluated to serve as a standard of comparison against mothers. All statistical analysis was made by adjusting detected volume concentrations (μg/L) with respect to creatinine concentrations (mg/dL) since urinary DEHP metabolites were studied using human reference. The difference in median levels of sum of urinary DEHP metabolites was only significant when children were analyzed in relation to region (p-value≤0.005). Among the three DEHP metabolites, only MEHP of children was significantly correlated to that of paired mothers (p-value≤0.01). The present paper defines the relative metabolic rate (RMR) of DEHP metabolism for the first time in study on phthalates. Children had faster RMR than mothers and adults, specifically in the first step of DEHP metabolism (RMR(1): MEHP hydroxylation to 5-OH-MEHP), and RMR(1) of children between 1 and 24months was the fastest. The above results may be used to study and assess human health risk from DEHP exposures, especially among mothers and children in Korea.
    Environment international 02/2013; 54C:65-73. · 6.25 Impact Factor
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    Jung-Duck Park, Wei Zheng
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    ABSTRACT: Mercury is a toxic and non-essential metal in the human body. Mercury is ubiquitously distributed in the environment, present in natural products, and exists extensively in items encountered in daily life. There are three forms of mercury, i.e., elemental (or metallic) mercury, inorganic mercury compounds, and organic mercury compounds. This review examines the toxicity of elemental mercury and inorganic mercury compounds. Inorganic mercury compounds are water soluble with a bioavailability of 7% to 15% after ingestion; they are also irritants and cause gastrointestinal symptoms. Upon entering the body, inorganic mercury compounds are accumulated mainly in the kidneys and produce kidney damage. In contrast, human exposure to elemental mercury is mainly by inhalation, followed by rapid absorption and distribution in all major organs. Elemental mercury from ingestion is poorly absorbed with a bioavailability of less than 0.01%. The primary target organs of elemental mercury are the brain and kidney. Elemental mercury is lipid soluble and can cross the blood-brain barrier, while inorganic mercury compounds are not lipid soluble, rendering them unable to cross the blood-brain barrier. Elemental mercury may also enter the brain from the nasal cavity through the olfactory pathway. The blood mercury is a useful biomarker after short-term and high-level exposure, whereas the urine mercury is the ideal biomarker for long-term exposure to both elemental and inorganic mercury, and also as a good indicator of body burden. This review discusses the common sources of mercury exposure, skin lightening products containing mercury and mercury release from dental amalgam filling, two issues that happen in daily life, bear significant public health importance, and yet undergo extensive debate on their safety.
    Journal of preventive medicine and public health = Yebang Ŭihakhoe chi. 11/2012; 45(6):344-52.
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    ABSTRACT: Cadmium (Cd) is a nonessential toxic metal which is widely distributed in the environment. The general population is exposed to low levels of Cd and the kidney is the organ most sensitive to Cd toxicity. This study was performed to simultaneously evaluate Cd exposure, kidney function, and oxidative stress biomarkers in the general population. A total of 643 adults were interviewed to document demographic characteristics, lifestyles, past-medical history, and diet during the last 24 h. We estimated daily Cd intake based on the diet of study subjects who had not been exposed to Cd occupationally. Whole blood and urine samples were collected and analyzed to determine Cd concentrations and kidney function indices (β2-microglobulin [β2-MG], N-acetyl-β-D-glucosaminidase [NAG], metallothionein [MT]). The oxidative stress index (malondialdehyde [MDA]) was determined from the urine. The daily Cd intake from diet was established as 7.07 μg/day. The mean concentration of Cd measured in the blood was 1.22 μg/L and urine was 0.95 μg/g creatinine. The concentrations of Cd in blood and urine were higher in females than in males. The blood levels of Cd were affected by sex, age, and smoking, and urine Cd was influenced by sex, age, and blood Cd. The urine Cd was positively correlated with MT, NAG activity, and MDA in females, but with NAG only in males. The blood Cd was associated with MT in males. Increased NAG activity was observed when Cd in urine reached 1.0 μg Cd/g creatinine and was also affected by age, hypertension, and diabetes mellitus. Urinary MT only responded to Cd in urine or blood. In summary, exposure to Cd in the general population was influenced by various factors including sex, age, and smoking habits. Such exposure might eventually cause tubular damage in the kidneys through the oxidative stress mechanism, and females might be more susceptible than males to Cd exposure under the environment. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2011
    Environmental Toxicology 07/2011; · 2.71 Impact Factor
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    ABSTRACT: Objectives: Biomarkers in urine are important in assessing exposures to environmental or occupational chemicals and for evaluateing renal function by exposure from these chemicals. Spot urine samples are needed to adjust the concentration of these biomarkers for variations in urine dilution. This study was conducted to evaluate the suitability of adjusting the urinary concentration of cadmium (uCd) and arsenic (uAs) by specific gravity (SG) and urine creatinine (uCr). Methods: We measured the concentrations of blood cadmium (bCd), uCd, uAs, uCr, SG and N-acetyl--D-glucosaminidase (NAG) activity, which is a sensitive marker of tubular damage by low dose Cd exposure, in spot urine samples collected from 536 individuals. The value of uCd, uAs and NAG were adjusted by SG and uCr. Results: The uCr levels were affected by gender (p < 0.01) and muscle mass (p < 0.01), while SG levels were affected by gender (p < 0.05). Unadjusted uCd and uAs were correlated with SG (uCd: r = 0.365, p < 0.01; uAs: r = 0.488, p < 0.01), uCr (uCd: r = 0.399, p < 0.01; uAs: r = 0.484, p < 0.01). uCd and uAs adjusted by SG were still correlated with SG (uCd: r = 0.360, p < 0.01, uAs: r = 0.483, p < 0.01). uCd and uAs adjusted by uCr and modified uCr () led to a significant negative correlation with uCr (uCd: r = -0.367, p < 0.01; uAs: r = -0.319, p < 0.01) and (uCd: r = -0.292, p < 0.01; uAs: r = -0.206, p < 0.01). However, uCd and uAs adjusted by conventional SG () were disappeared from these urinary dilution effects (uCd: r = -0.081; uAs: r = 0.077). Conclusions: adjustment appears to be more appropriate for variations in cadmium and arsenic in spot urine.
    Korean Journal of Environmental Health Sciences. 01/2011; 37(6).
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    ABSTRACT: Catalase protects cells from reactive oxygen species-induced damage by catalyzing the breakdown of hydrogen peroxide to oxygen and water. Arsenite decreases catalase activity; it activates phosphatidylinositol 3-kinase (PI3K) and its key downstream effector Akt in a variety of cells. The PI3K pathway is known to inhibit catalase expression. c-Met, an upstream regulator of PI3K and Akt, is also involved in the regulation of catalase expression. To examine the involvement of c-Met and PI3K pathways in the arsenite-induced downregulation of catalase, catalase mRNA and protein expression were analyzed in the human hepatoma cell line HepG2 treated with arsenite and either an inhibitor of c-Met (PHA665752 (PHA)) or of PI3K (LY294002 (LY)). Arsenite treatment markedly activated Akt and decreased the levels of both catalase mRNA and protein. Both PHA and LY attenuated arsenite-induced activation of Akt. PHA and LY treatment also prevented the inhibitory effect of arsenite on catalase protein expression but did not affect the level of catalase mRNA. These findings suggest that arsenite-induced inhibition of catalase expression is regulated at the mRNA and post-transcriptional levels in HepG2 cells, and that the post-transcriptional regulation is mediated via c-Met- and PI3K-dependent mechanisms.
    Biological & Pharmaceutical Bulletin 01/2011; 34(11):1748-52. · 1.85 Impact Factor
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    ABSTRACT: While it's been shown that arsenic impairs male reproductive function, it remains unclear whether the mechanism involves an effect on testosterone (T) production. We examined plasma T and luteinizing hormone (LH) levels in mice given water containing either 20 or 40 mg/L sodium arsenite (SA). The plasma T levels were lower in SA-treated mice than in controls and correlated well with testicular T levels within individuals. However, SA treatment did not significantly affect plasma LH levels. The ratio of plasma T to LH was reduced by the treatment with 40 mg/L SA. These results suggest arsenic-induced defect in testicular testosterone production in mice.
    Biomolecules and Therapeutics 01/2010; 18(3):257-261. · 0.79 Impact Factor
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    ABSTRACT: Arsenic (As) is a known human carcinogen and widely distributed in the environment. The main route of As exposure in the general population is through food and drinking water. Seafood harvested in Korea contains high-level organoarsenics such as arsenobetaine, arsenocholine, and arsenosugars, which are much less harmful than inorganic arsenics. However, for those who eat large amounts of seafood it is important to understand whether seafood consumption affects urinary levels of inorganic As metabolites such as arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). In this study we investigated urinary As metabolites (inorganic As, MMA[V], DMA[V]) and some biological indexes such as AST, GSH, GPX, lipid peroxidation, and uric acid in volunteer study subjects (seven males and nine females). Total urinary As metabolites were analyzed by the hydride generation method, followed by arsenic speciation using HPLC with ICP-mass spectrometry. Study subjects refrained from eating seafood for 3 days prior to the first urine collection and then ingested seafood daily for 6 consecutive days. The first voided urine of the morning was collected from each subject the first day of the consecutive 6 days of seafood ingestion but prior to the first seafood meal. The first voided urine of the morning was also collected on days 1, 2, 3, 4, 5, 6, 7, 10, and 14 after seafood ingestion. The daily mean intake of total As was 6.98 mg, comprised of 4.71 mg of seaweed (67%), 1.74 mg of flat fish (25%), and 0.53 mg of conch (8%). We observed a substantial increase in total urinary As metabolites for subjects consuming seafood from day 1, which recovered to control level at day 10. The increase in total urinary As metabolites was attributed to the increase in DMA, which is a more harmful metabolite than organoarsenics. However, no significant changes in response biological indexes were observed. These results suggest that it is necessary to evaluate As metabolism when assessing the exposure to inorganic As and potential chronic health effects of seafood consumption in Korea.
    Archives of Environmental Contamination and Toxicology 06/2009; 58(1):222-9. · 2.01 Impact Factor
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    ABSTRACT: The mechanism of the adverse health effects of ambient particulate matter on humans has not been well-investigated despite many epidemiologic association studies. Measurement of personal exposure to particulate pollutants and relevant biological effect markers are necessary in order to investigate the mechanism of adverse health effects, particularly in fragile populations considered to be more susceptible to the effects of pollutants. We measured personal exposure to PM(2.5) and examined oxidative stress using urinary malondialdehyde three times in 51 preschoolers and 38 elderly subjects. A linear mixed-effects model was used to estimate PM(2.5) effects on urinary MDA levels. Average personal exposure of the children and elderly to PM(2.5) was 80.5 +/- 29.9 and 20.7 +/- 12.7 mug/m(3), respectively. Mean urinary MDA level in the children and the elderly was 3.6 +/- 1.9 and 4.0 +/- 1.6 mumol/g creatinine. For elderly subjects the PM(2.5) level was significantly associated with urinary MDA after adjusting for age, sex, BMI, passive smoking, day-care facility site, alcohol consumption, cigarette smoking, and medical history (heart disease, hypertension and bronchial asthma). However, there was no significant relationship for children. The elderly were more susceptible than young children to oxidative stress as a result of ambient exposure to PM(2.5). Identification of oxidative stress induced by PM(2.5) explains the mechanism of adverse health effects such as cardiovascular or respiratory diseases, particularly in the elderly.
    Environmental Health and Preventive Medicine 02/2009; 14(1):60-6.
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    ABSTRACT: Cadmium (Cd) and arsenic (As) are widely distributed in the environment and are known human carcinogens. Several studies reported that chronic exposure to Cd and As produced renal injuries in humans. As one of the mechanisms, oxidative stress was suggested to play a role in the early process of Cd- and/or As-induced tubular damage in the kidney. This study was performed to evaluate the significance of urinary biomarkers, role of oxidative stress, and effect of coexposure to environmental low-level exposure to Cd and/or As in the general population. Urine samples were collected from 290 adults (86 males and 204 females). Urinary concentrations of Cd and As were measured, and kidney biomarkers of toxicity such as beta(2)-microglobulin and N-acetyl-beta-D-glucosaminidase (NAG) activity determined in urine. Urinary malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were measured as oxidative stress indices. The mean concentration of Cd was 1.21 microg/L, 0.84 microg/g creatinine, and As was 5.7 microg/L, 3.95 microg/g creatinine in urine. NAG, MDA, and 8-OHdG were positively correlated with both Cd and As in urine. Positive correlations were also observed between NAG and oxidative indices. The effects of coexposure to Cd and As on biomarkers are more pronounced than for exposure to each metal alone. These findings suggest that chronic exposure to low levels of Cd and/or As might produce tubular damage in the kidney through oxidative stress in humans.
    Journal of Toxicology and Environmental Health Part A 01/2009; 72(21-22):1493-8. · 1.73 Impact Factor
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    ABSTRACT: It has been suggested that the altered iron metabolism in liver tumors, characterized by the iron-deficient phenotype, is of importance for tumor growth. This study was performed to elucidate the mechanisms underlying iron deficiency in liver tumors by examining how the liver tumor development affects the expression of iron metabolism-related genes. Iron metabolism reference values were analyzed in the sera of diethylnitrosamine-induced hepatocellular adenoma-bearing mice. Expression of iron metabolism-related genes was analyzed in adenomas and surrounding non-tumor tissues, and a subgroup of adenoma-bearing mice loaded with iron 72h before sacrifice. Iron content of the adenoma tissues was 2.0-2.5-fold lower compared to surrounding and age-matched control tissues. There was no significant difference in serum iron levels between the adenoma-bearing and control mice, while the adenoma-bearing mice exhibited a 2.4-fold lower level of serum transferrin saturation. Expression of iron metabolism-related genes was dysregulated in the adenomas. Iron loading affected protein expression similarly in the adenomas and surrounding tissues suggesting that iron-responsive regulation of the proteins was not impaired. However, the mRNA expression for ceruloplasmin and divalent metal transporter 1 (DMT1) IRE(+) in the adenomas was altered independently of iron status, and the dysregulation may contribute to diminished iron content. These findings suggest that diethylnitrosamine-induced liver adenoma-bearing mice have abnormal iron metabolism and that dysregulation of iron metabolism-related genes contributes to iron deficiency in the adenomas.
    Toxicology Letters 12/2008; 184(3):151-8. · 3.15 Impact Factor
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    ABSTRACT: We investigated the association of genetic polymorphisms of NQO1, ALDH2, CYP2E1, and the combined genotype of these genes on lung cancer risk, and also evaluated the association after stratification by cumulative smoking amounts and alcohol drinking levels. The case-control study was performed in 387 lung cancer patients and 387 age- and sex-matched cancer-free controls. Direct interview was conducted and the genotypes of NQO1, ALDH2, and CYP2E1 were investigated using PCR-RFLP or 5'-nuclease activity assay. The proportion of individuals with occupational history of mining was significantly higher in cases than in controls. The risk of lung cancer was significantly lower in light-drinkers (<108 g/week) than non-drinkers. The NQO1 Pro/Ser + Ser/Ser genotype showed an increased risk for lung cancer with a marginal significance (OR = 1.35, 95% CI = 0.99-1.86) compared with NQO1 Pro/Pro genotype. In heavy-smokers, the combination of NQO1 Pro/Ser + Ser/Ser and CYP2E1 c1/c1 genotype was associated with a significantly increased risk for lung cancer (OR = 2.25, 95% CI = 1.14-4.43) compared with those of NQO1 Pro/Pro and CYP2E1 c1/c2 + c2/c2 genotype. We found a significant interaction between alcohol drinking level and the CYP2E1 genotype (P = 0.0227). Our result suggests that the risk of lung cancer is affected by smoking, alcohol drinking, and the genetic polymorphism of NQO1. In particular, genetic polymorphisms for NQO1, CYP2E1, and ALDH2 synergistically with cumulative smoking amounts and alcohol drinking levels interact in the carcinogenesis of lung cancer in Koreans.
    Cancer Causes and Control 09/2008; 20(2):137-45. · 3.20 Impact Factor

Publication Stats

324 Citations
76.57 Total Impact Points

Institutions

  • 2004–2014
    • Chung-Ang University
      • • College of Medicine
      • • Department of Medicine
      Sŏul, Seoul, South Korea
  • 2013
    • Chung-Ang University Hospital
      Sŏul, Seoul, South Korea
  • 2008–2013
    • Chungbuk National University
      • College of Medicine
      Chinch'ŏn, North Chungcheong, South Korea
  • 2003–2011
    • Seoul National University
      • • College of Veterinary Medicine
      • • College of Pharmacy
      Seoul, Seoul, South Korea