Yu-Mi Lee

Excitation functions of the proton induced nuclear reactions on natZn up to 40 MeV

We have measured the production cross-sections of the residual radionuclides for proton-induced reactions on natural tin by using a stacked-foil activation technique in the energy range from threshold energy to 40 MeV at the MC-50 cyclotron of the Korea Institute of Radiological and Medical Sciences. The results were compared with the earlier reported experimental data and theoretical calculations based on the TALYS and the ALICE-IPPE codes. The present results are in general good agreement with the available literature data and calculated results by using the computer codes TALYS and ALICE-IPPE. The thick target integral yields were also deduced from the measured excitation functions of the produced radionuclides.

Associations of organochlorine pesticides and polychlorinated biphenyls in visceral vs. subcutaneous adipose tissue with type 2 diabetes and insulin resistance.

Background exposure to organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) has been linked to type 2 diabetes. As OC pesticides and PCBs mainly accumulate in adipose tissue and there are physiological and clinical differences between visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT), we explored if there were associations of OC pesticides and PCBs in VAT or SAT with type 2 diabetes and insulin resistance. Participants were 50 patients with or without type 2 diabetes who underwent surgery for either cancer or benign liver or gallbladder lesions. We analyzed 14 OC pesticides and 22 PCB congeners in both VAT and SAT. Insulin resistance was estimated using homeostasis model assessment (HOMA). Although concentrations of OC pesticides and PCBs were strongly correlated between VAT and SAT, absolute concentrations differed substantially between them. In particular, concentrations of all PCBs were consistently about 5-10 times higher in VAT than SAT, but these patterns were independent of diabetes status. Some OC pesticides or PCBs, such as dichlorodiphenyltrichloroethanes (DDTs), chlordanes, and PCBs with 5 or less chlorides showed significant associations with diabetes or insulin resistance. For example, when tertiles of concentration-based summary measures were used, adjusted ORs were 1.0, 2.3, and 9.0 (P trend=0.02) for DDTs in VAT and 1.0, 2.1, and 5.7 (P trend=0.08) for PCBs with 5 or less chlorides. This study generally confirmed previous findings using serum concentrations. It would be useful to study pharmacodynamics of POPs in VAT and SAT further.

Prospective associations between persistent organic pollutants and metabolic syndrome: A nested case–control study

OBJECTIVEnExposure to persistent organic pollutants (POPs) has recently been linked to metabolic syndrome (MetS) and some MetS components. However, prospective evidence in humans is scarce, and the nature of the dose-response relationship is unclear. We evaluated the association between POPs and MetS using a nested-case control study within a community-based Korean cohort.nnnMETHODnThe study subjects were 64 patients newly diagnosed with MetS during a 4-year follow-up, and the controls were 182 subjects without MetS. Concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured in stored serum collected at baseline.nnnRESULTSnThe concentrations of most PCBs and some OCPs such as β-hexachlorocyclohexane, hexachlorobenzene, oxychlordane, and heptachlor epoxide predicted the risk for MetS. The POP exposure and MetS showed an inverted U-shaped or a linear association with plateau rather than a linear dose-response association. When the summary measure of the PCBs and OCPs was used, the adjusted odds ratios (ORs) across the quartiles of the summary measure were 1.0, 1.3, 3.8 (95% confidence interval, 1.3-10.7), and 2.1 (Pquadratic=0.013) after adjusting for potential confounders. In the analyses of each of the five MetS components, POP exposure was mainly associated with an increased risk for glucose and lipid metabolism disturbances.nnnCONCLUSIONnThis study demonstrated that chronic exposure to a mixture of PCBs and OCPs can increase the risk for MetS within the low-dose background exposure range of POPs. As the findings of this study suggest a nonmonotonic dose-response relationship, in vitro and in vivo experimental studies are needed to understand the underlying mechanisms.

Effect of a Brown Rice Based Vegan Diet and Conventional Diabetic Diet on Glycemic Control of Patients with Type 2 Diabetes: A 12-Week Randomized Clinical Trial

Objective Several intervention studies have suggested that vegetarian or vegan diets have clinical benefits, particularly in terms of glycemic control, in patients with type 2 diabetes (T2D); however, no randomized controlled trial has been conducted in Asians who more commonly depend on plant-based foods, as compared to Western populations. Here, we aimed to compare the effect of a vegan diet and conventional diabetic diet on glycemic control among Korean individuals. Materials and Methods Participants diagnosed with T2D were randomly assigned to follow either a vegan diet (excluding animal-based food including fish; n = 46) or a conventional diet recommended by the Korean Diabetes Association 2011 (n = 47) for 12 weeks. HbA1c levels were measured at weeks 0, 4, and 12, and the primary study endpoint was the change in HbA1c levels over 12 weeks. Results The mean HbA1c levels at weeks 0, 4, and 12 were 7.7%, 7.2%, and 7.1% in the vegan group, and 7.4%, 7.2%, and 7.2% in the conventional group, respectively. Although both groups showed significant reductions in HbA1C levels, the reductions were larger in the vegan group than in the conventional group (-0.5% vs. -0.2%; p-for-interaction = 0.017). When only considering participants with high compliance, the difference in HbA1c level reduction between the groups was found to be larger (-0.9% vs. -0.3%). The beneficial effect of vegan diets was noted even after adjusting for changes in total energy intake or waist circumference over the 12 weeks. Conclusion Both diets led to reductions in HbA1c levels; however, glycemic control was better with the vegan diet than with the conventional diet. Thus, the dietary guidelines for patients with T2D should include a vegan diet for the better management and treatment. However, further studies are needed to evaluate the long-term effects of a vegan diet, and to identify potential explanations of the underlying mechanisms. Trial Registration CRiS KCT0001771

Different associations between obesity and impaired fasting glucose depending on serum gamma-glutamyltransferase levels within normal range: a cross-sectional study

BackgroundDespite the consistent relationship between serum γ-glutamyltransferase (GGT) and type 2 diabetes (T2D), one unsolved issue is the role of serum GGT in the well-known association between obesity and T2D. This study was performed to investigate whether the association between body mass index (BMI) and impaired fasting glucose (IFG) differed depending on serum GGT levels within the normal range.MethodsStudy subjects were 2,424 men and 3,652 women agedu2009≥u200940, participating in the Fifth Korean National Health and Nutrition Examination Survey. Serum GGT levels within the normal range were classified into gender-specific tertiles.ResultsAmong men and women belonging to the lowest tertile of serum GGT, BMI showed statistically non-significant weak associations with the risk of IFG. However, among persons in the highest tertile of serum GGT, the risk of IFG was 3u2009−u20094 times higher among persons with BMIu2009≥u200925xa0kg/m2 than those with BMIu2009<u200923xa0kg/m2 (Pinteractionu2009=u20090.032 in men and 0.059 in women).ConclusionsThe well-known strong association between BMI and IFG was observed mainly among persons with elevation of serum GGT to certain physiological levels, suggesting a critical role of serum GGT in the pathogenesis of IFG. This finding has an important clinical implication because serum GGT can be used to detect high-risk obese persons.

Associations between Cigarette Smoking and Total Mortality Differ Depending on Serum Concentrations of Persistent Organic Pollutants among the Elderly

There are substantial variations of relative risks (RR) in smoking-related mortality by country and time. We hypothesized the RRs in smoking-related mortality might differ depending on serum concentrations of persistent organic pollutants (POPs). We evaluated the associations of cigarette smoking with total mortality in 610 elderly (aged ≥ 70 yr) (702 elderly for organochlorine pesticides [OCPs]) after stratification by serum concentration of POPs, in the National Health and Nutrition Examination Survey (NHANES) 1999-2004 followed through 2006. Summary measures of POPs subclasses showed significant or marginally significant interaction with cigarette smoking on the risk of total mortality. P values for interaction were 0.069 for polychlorinated dibenzo-p-dioxins (PCDDs), 0.008 for polychlorinated biphenyls (PCBs), and 0.024 for OCPs. The effect of smoking on total mortality showed different patterns according to the serum concentration of some POPs. Former or current smokers had 1.4 to 2.9 times higher mortality rates compared with never smokers among participants with higher serum concentrations of POPs (2nd or 3rd tertiles). However, when the level of PCBs or OCPs were low (1st tertile), there were little positive associations between smoking and mortality. Our study suggests that the background exposure to several POPs may be related to variability in smoking-related total mortality.

Paradoxical Associations of Insulin Resistance With Total and Cardiovascular Mortality in Humans

BACKGROUNDnInsulin resistance is linked to many human chronic diseases. Paradoxically, however, impaired insulin signaling contributes to longevity in various organisms and is suggested as an adaptive mechanism against external stressors, including obesity. We formulated a novel hypothesis that insulin resistance can be beneficial in obese humans, insofar as it does not cause glucose dysmetabolism.nnnMETHODSnN = 5,241 participants aged ≥40 with normal fasting glucose were combined across the 1988-1994 and 1999-2004 National Health and Nutrition Examination Survey datasets. Mean follow-up period was 6.6 years. Insulin resistance was measured with homeostasis model assessment (HOMA-IR). Outcomes were all causes (n = 724), cardiovascular diseases (CVD, n = 316), and cancer mortality (n = 190).nnnRESULTSnSupporting the hypothesis, obese persons with high HOMA-IR showed a decreased risk of total and CVD mortality compared to those with the lowest HOMA-IR. Adjusted hazard ratios were 1.0, 0.8, 0.4, and 0.4 (p(trend) = .02) for all death and 1.0, 0.6, 0.2, and 0.2 (p(trend) < .01) for CVD death. On the other hand, lean persons with high HOMA-IR showed about twice the total and CVD mortality compared to persons with the lowest HOMA-IR (p(trend) < .01, respectively).nnnCONCLUSIONSnInsulin resistance in obese individuals may begin as an adaptive mechanism and can be beneficial if it is not associated with glucose dysmetabolism. In contrast, insulin resistance in lean individuals associated with higher risk of total and CVD mortality. Insulin resistance may be multifaceted and conventional approaches to regard insulin resistance itself as a pathological condition may be reconsidered in this light.

Persistent Organic Pollutants Impair Insulin Secretory Function of Pancreatic Beta-Cells: Human and in Vitro Evidence

Low-dose persistent organic pollutants (POPs), especially organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), have emerged as a new risk factor for type 2 diabetes. We evaluated whether chronic exposure to low-dose POPs affects insulin secretory function of β-cells in humans and in vitro cells. Serum concentrations of OCPs and PCBs were measured in 200 adults without diabetes. Mathematical model–based insulin secretion indices were estimated by using a 2-h seven-sample oral glucose tolerance test. Insulin secretion by INS-1E β-cells was measured after 48 h of treatment with three OCPs or one PCB mixture. Static second-phase insulin secretion significantly decreased with increasing serum concentrations of OCPs. Adjusted means were 63.2, 39.3, 44.1, 39.3, 39.7, and 22.3 across six categories of a summary measure of OCPs (Ptrend = 0.02). Dynamic first-phase insulin secretion remarkably decreased with increasing concentrations of OCPs among only insulin-sensitive individuals (Ptrend = 0.02); the insulin levels among individuals with high OCPs were ∼30% of those with low OCPs. Compared with OCPs, PCBs showed weaker associations. The decreased insulin secretion by INS-1E β-cells was observed for even 1 pmol/L OCP. The data from human and in vitro cell experiments suggest that chronic exposure to low-dose POPs, especially OCPs, can induce pancreatic β-cell dysfunction.

Factors related to intentional and unintentional medication nonadherence in elderly patients with hypertension in rural community

Purpose We assessed medication nonadherence, categorized as intentional or unintentional, and related factors in elderly patients with hypertension, correlating the data with measurement of blood pressure as the final target of medication adherence and other possible influencing factors, such as lifestyle. Patients and methods Subjects were aged ≥65 years, resided in a rural area, and were taking antihypertensive drugs. The survey was conducted in July 2014. Participants were divided into the following three groups: “Adherence”, “Unintentional nonadherence”, and “Intentional nonadherence”. Individual cognitive components, such as necessity and concern as well as self-efficacy and other related factors, were compared according to adherence groups. The interrelationships between those factors and nonadherence were tested using structural equation modeling analysis. Results Of the 401 subjects, 182 (45.6%) were in the adherence group, 107 (26.7%) in the unintentional nonadherence group, and 112 (27.9%) in the intentional nonadherence group. Necessity and self-efficacy were found to have a significant direct influence on unintentional nonadherence behaviors (necessity β=−0.171, P=0.019; self-efficacy β=−0.433, P<0.001); concern was not statistically significant (β=−0.009, P=0.909). Necessity was found to have significant direct and indirect impact on intentional nonadherence (direct β=−0.275, P=0.002; indirect β=−0.113, P=0.036). Self-efficacy had no significant direct effect on intentional nonadherence though it had the only significant indirect effect on intentional nonadherence (direct β=−0.055, P=0.515; indirect β=−0.286, P<0.001). Concern had no significant influence on intentional or on unintentional nonadherence (direct β=0.132 0.132, P=0.151; indirect β=−0.006, P=0.909). Conclusion Unintentional nonadherence should be regularly monitored and managed because of its potential prognostic significance. Interventions addressing cognitive factors, such as beliefs about medicine or self-efficacy, are relatively difficult to implement, but are essential to improve medication adherence.

Serum Concentration and Exposure History of Dioxins and Organochlorine Pesticides among Residents around the Camp Carroll Area

Objectives: This study was performed in order to evaluate whether 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) could be detected among residents living near Camp Caroll in Waegwan and whether serum concentrations of dioxins, including 2,3,7,8-TCDD, and organochlorine pesticides (OCPs) are associated with length of residence. Methods: Study subjects totaled 113 (for dioxins) and 190 (for OCPs) adults who were selected from participants in a medical investigation. Serum concentrations of dioxins and OCPs were measured using HRGC/HRMS. Information on length of residence was obtained through questionnaires. Results: 2,3,7,8–TCDD was not detected in serum among all subjects. When length of residence was classified as a categorical variable, after adjusting for confounding variables, only residents living in Waegwan for 40 years or longer tended to have high total TEQ values and 2,3,4,7,8-PeCDF with marginal significances. There was no dose-response relation between length of residence and serum concentrations of these chemicals. In multiple regression models with continuous values of the length of residence, total TEQ value and 1,2,3,4,6,7,8-HpCDF were positively associated with length of residence. However, they explained about 3-5% of total variations of serum concentrations of these compounds, while age, consumption of fatty fish, body mass index, alcohol drinking, and cigarette smoking were main variables affecting serum concentrations of dioxins or OCPs. *Corresponding author: Hyun-Sul Lim, Tel: 054-770-2401, E-mail: wisewine@dongguk.ac.kr Department of Preventive Medicine, College of Medicine, Dongguk University. 123 Dongdae-ro, Gyeongju-si, Gyeongbuk 38066 Received: August 25, 2016, Revised: September 22, 2016, Accepted: September 24, 2016 This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 278 배상근ᆞ김근배ᆞ조용성ᆞ이유미ᆞ이덕희ᆞ양원호ᆞ주영수ᆞ이관ᆞ민영선ᆞ임현술 http://www.kiha.kr Journal of Korean Society of Occupational and Environmental Hygiene, 2016: 26(3): 277-285 I. 서 론 2011년 5월 19일 퇴역 미군의 ‘베트남 지역에서 사용한 Agent Orange’ 표시가 부착된 드럼통을 1978 년경 캠프 캐럴에 매립했다는 인터뷰가 보도된 이후 한미공동조사단이 캠프 캐럴 주변에 대한 환경조사 를 실시하였다. 캠프 캐럴 내외의 토양 및 지하수를 조사한 결과 고엽제가 매립되었다는 것을 확인하지 는 못하였으며, 기지내부 지하수 조사 결과 고엽제 주요 오염물질인 2,3,7,8-tetrachlorodibenzo-ρ-dioxin (2,3,7,8-TCDD)은 정량한계 미만이었다. 그러나 일부 관측정에서 다이옥신류가 극미량 검 출되었으며, 그 외 유기염소계 농약, Perchloroethylene (PCE), Trichloroethylene(TCE)도 일부 검출되었다. 또한 기지 외부 토양 및 하천퇴적물 오염조사 결과 도 지하수 검사결과와 비슷한 결과를 보여 주민들의 생체시료에서 이러한 유해화학물질의 노출 정도를 평가해야 할 필요성이 제기되었다(Lim et al., 2011; The ROK-US Joint Investigation Team, 2011). 이 연구는 캠프 캐럴 인근 주민들의 생체시료에서 2,3,7,8-TCDD를 포함한 다이옥신류와 유기염소계 농 약의 노출을 평가하고, 이러한 물질들의 혈중 농도가 왜관읍 총 거주기간과 관련성이 있는지를 분석하기 위해 시행되었다. 또한 일반인구집단에서 다이옥신 을 비롯하여 이러한 화학물질의 노출은 음식, 공기, 토양, 물 등 여러 환경매체를 통하여 발생할 수 있으 므로 이들 혈중 농도는 식이습관을 포함하여 다양한 건강행태와 관련성이 있는 것으로 보고되고 있다 (Devine et al., 1990; Ibarluzea et al., 2011). 따라서 이러한 화학물질들의 혈중 농도와 건강행태와의 관 련성에 비하여 거주기간이 미치는 영향의 크기를 상 대적으로 비교 평가하고자 하였다. II. 연구 방법