Jae-Seok Song

Risk assessment of low-level cadmium and arsenic on the kidney.

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 ß2-microglobulin and N-acetyl-β-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 μg/L, 0.84 μg/g creatinine, and As was 5.7 μg/L, 3.95 μg/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.

Synthesis of substituted triazolyl curcumin mimics that inhibit RANKL-induced osteoclastogenesis.

Some promising new antiresorptive agents of potential utility for treating osteoporosis were uncovered in a curcumin mimics library possessing a substituted triazole moiety, which is synthesized by the Cu(I)-catalyzed Huisgen 1,3-cycloaddition reaction between two azido intermediates (9 and 10) and various alkynes (a-k). A tartarate-resistant acid phosphatase (TRAP) activity assay was carried out with RANKL-induced osteoclastogenesis of mouse monocyte/macrophage RAW264.7 cells; the results indicated that the curcumin mimics derived from intermediate 10 exhibited stronger inhibitory activity than 9. In particular, curcumin mimics 12h, 13c, and 13e strongly inhibited osteoclast differentiation.

Long Working Hours and Emotional Well-Being in Korean Manufacturing Industry Employees

ObjectivesKorea is well known for its long work hours amongst employees. Because workers of the manufacturing industry are constantly exposed to extended work hours, this study was based on how long work hours affect their emotional well-being.MethodsThe analysis was done using the secondary Korean Working Condition Survey (KWCS). Long work hours were defined to be more than 48 hours, and they were subcategorized into units of 52 hours and 60 hours. Based on the WHO (five) well-being index, emotional state was subdivided into three groups - reference group, low-mood group, and possible depression group- where 28 points and 50 points were division points, and two groups were compared at a time. Association between long work hours and emotional state was analyzed using binary and multinomial logistic regression analysis.ResultsWorking for extended working hours in the manufacturing industry showed a statistically significant increase (t test p < 0.001) in trend among the possible depression group when compared to the reference group and the low-mood group. When demographical characteristics, health behaviors, socioeconomic state, and work-related characteristics were fixed as controlled variables, as work hours increased the odds ratio of the possible depression group increased compared to the reference group, and especially the odds ratio was 2.73 times increased for work hours between 48–52 and 4.09 times increased for 60 hours or more and both were statistically significant. In comparing the low-mood group and possible depression group, as work hours increased the odds ratio increased to 1.73, 2.39, and 4.16 times, and all work hours from working 48–52 hours, 53–60 hours, and 60 hours or more were statistically significant. Multinomial logistic regression analysis also showed that among the reference group and possible group, the possible depression group was statistically significant as odds ratio increased to 2.94 times in working 53–60 hours, and 4.35 times in 60 hours or more.ConclusionsLong work hours have an adverse effect on emotional well-being. A more diversified research towards variables that affect long work hours and emotional well-being and how they interact with each other and their relationship to overall health is imperative.

Serum 2,3,7,8-Tetrachlorodibenzo-p-dioxin Levels and Their Association With Age, Body Mass Index, Smoking, Military Record-based Variables, and Estimated Exposure to Agent Orange in Korean Vietnam Veterans

Objectives The aim of this study was to examine the levels of serum 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and evaluate their association with age, body mass index, smoking, military record-based variables, and estimated exposure to Agent Orange in Korean Vietnam veterans. Methods Serum levels of TCDD were analyzed in 102 Vietnam veterans. Information on age, body mass index, and smoking status were obtained from a self-reported questionnaire. The perceived exposure was assessed by a 6-item questionnaire. Two proximity-based exposures were constructed by division/brigade level and battalion/company level unit information using the Stellman exposure opportunity index model. Results The mean and median of serum TCDD levels was 1.2 parts per trillion (ppt) and 0.9 ppt, respectively. Only 2 Vietnam veterans had elevated levels of TCDD (>10 ppt). The levels of TCDD did not tend to increase with the likelihood of exposure to Agent Orange, as estimated from either proximity-based exposure or perceived self-reported exposure. The serum TCDD levels were not significantly different according to military unit, year of first deployment, duration of deployment, military rank, age, body mass index, and smoking status. Conclusions The average serum TCDD levels in the Korean Vietnam veterans were lower than those reported for other occupationally or environmentally exposed groups and US Vietnam veterans, and their use as an objective marker of Agent Orange exposure may have some limitations. The unit of deployment, duration of deployment, year of first deployment, military rank, perceived self-reported exposure, and proximity-based exposure to Agent Orange were not associated with TCDD levels in Korean Vietnam veterans. Age, body mass index and smoking also were not associated with TCDD levels.

Detection and Quantification of Pharaoh Ant Antigens in Household Dust Samples as Newly Identified Aeroallergens

Background:The widespread house ant, Monomorium pharaonis (pharaoh ant, PA), was recently identified as a potential cause of respiratory allergies. However, there are no reports of the distribution of PA allergens in various environments. We developed specific ELISA inhibition assays and measured the distribution and amount of PA antigens in household dust samples. Methods:Floor dust was collected at 3-month intervals from 56 homes in Seoul over a 1-year period. PA antigens in fine dusts were quantified by ELISA inhibition assays using rabbit anti-PA sera, and specific IgE to PA antigens in residents’ serum was measured by ELISA. Results: In 18 of the 56 homes (32.1%), PA antigen was detected in at least 1 floor dust sample either from the living room or the kitchen. Levels of PA antigens showed seasonal variations with peaks in autumn and winter. The detection rate of PA antigens was significantly higher in homes with visual evidence of PA infestations (70%) than in homes without such infestations (23.9%; p < 0.05). However, a significant amount of PA antigens was still detected in uninfested homes. Thirteen of 113 (11.5%) residents were positive for PA-specific IgE. PA-specific IgE was detected more frequently in residents living in PA antigen-positive homes (19.6%) than in antigen-negative homes (4.8%; p < 0.05). Conclusion: A considerable level of PA antigens is distributed in the indoor environment. Therefore, inhalant exposure to PA antigens can occur during domestic activities. These results suggest that PAs might be a significant source of aeroallergens in households.