• Asian Pacific Journal of Cancer Prevention
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• v.14 no.1
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• pp.523-528
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• 2013

Background: The possibility that electromagnetic fields (EMF) exposure may increase male breast cancer risk has been discussed for a long time. However, arguments have been presented that studies limited by poor quality could have led to statistically significant results by chance or bias. Moreover, data fo the last 10 years have not been systematically summarized. Methods and Results: To confirm any possible association, a meta-analysis was performed by a systematic search strategy. Totals of 7 case-control and 11 cohort studies was identified and pooled ORs with 95% CIs were used as the principal outcome measures. Data from these studies were extracted with a standard meta-analysis procedure and grouped in relation to study design, cut-off point, exposure assessment method, adjustment and exposure model. A statistical significant increased risk of male breast cancer with EMF exposure was defined (pooled ORs = 1.32, 95% CI = 1.14-1.52, P < 0.001), and subgroup analyses also showed similar results. Conclusions: This meta-analysis suggests that EMF exposure may be associated with the increase risk of male breast cancer despite the arguments raised.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.1
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• pp.38-49
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• 2000

The purpose of this study was to evaluate the effects of thermocycling on the shear bond strength of Co-Cr alloy to denture base resin. PMMA denture base resin such as heat-cured $Vertex-RS^{(R)}$, self-cured $Vertex-SC^{(R)}$ and 4-META denture base resin such as heat-cured $Meta-Dent^{(R)}$, self-cured $Meta-Fast^{(R)}$ was bonded to Co-Cr alloy. Samples were divided into 3 groups : no thermocycling group as control, thermocycling between $5^{\circ}C\;and\;55^{\circ}C$ with 15 second dwell time as group 1, thermocycling with 1 minute dwell time as group 2. The shear bond strength was measured and the interface between metal and resin was observed by SEM. The results were as follows. 1. The shear bond strength decreased significantly according to thermocycling and dwell time(P<0.001). 2. The bond strength of Co-Cr alloy and 4-META denture base resin was significantly higher than that of Co-Cr alloy and PMMA denture base resin(P<0.001) 3. In SEM, there was no gap in control group, but there was much and large gap in group 1, 2. The longer dwell times, the lower bond strength. PMMA denture base resin had more gap than 4-META denture base resin in the interface. These results revealed that thermocycling decreased the bond strength between Co-Cr alloy and denture base resin and dwell time of thermocycling changed the effect of thermocycling. The results suggested that oral temperature change affect the bond strength of prosthesis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.191-193
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• 2015

Recently, with the economy and the information communication technology developed, the e-commerce market grows continuously. A meta-analysis refers to a statistical literature synthesis method from the quantitative results of many known empirical studies. We conducted a meta-analysis and review of between perceived risk to criterion variable on e-commerce researches. This study focused a total of 25 research papers that established causal relationships in between perceived risk to criterion variable on e-commerce published in Korean academic journals during 2000 and 2014. The result of the meta-analysis might be summarized that the effect size in the path from perceived risk to the criterion variable with the effect size -0.251. Based on these findings, several theoretical and practical implications were suggested and discussed with the difference from previous researches.

• Journal of Korean Critical Care Nursing
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• v.9 no.1
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• pp.51-65
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• 2016

Purpose: This study aimed to estimate the pooled prevalence of workplace bullying among nurses and examine the effect of moderate factors. Methods: Studies that assessed nursing workplace bullying using the negative act questionnaire developed by Einarsen et al. were searched for in 8 databases. The pooled prevalence was calculated with overall event rate and meta-ANOVA was performed for subgroup analysis. A funnel plot and Egger's linear regression asymmetry test were performed to confirm the publication bias of meta-analyzed studies. Results: A total of 23 studies (N=11,748) were included in the systematic review, and 14 studies (N=4,585) that reported prevalence using operational criteria of victim were selected for meta-analysis. The pooled prevalence of workplace bullying was 22.2% (95% CI: 19.0~25.7). Domestic studies reported lower prevalence than international studies (18.6% vs. 27.0%, Q=8.75, p=.003). The prevalences were different according to publication year (30.6% in 2008~2010, 19.5% in 2011~2014, 21.8% in 2015, Q=11.89, p=.003). Studies that recruited only new nurses reported higher prevalence than others (28.4% vs. 20.6%, Q=3.92, p=.048). Publication bias was not found. Conclusions: Workplace bullying is prevalent in the nursing profession, and is more serious for new graduate nurses. Individual and organizational measures for preventing workplace bullying among nurses need to be sought.

• The Journal of Internal Korean Medicine
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• v.38 no.4
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• pp.419-432
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• 2017

Objectives: This study provides an evaluation of the effectiveness of acupuncture for the treatment of essential tremors (ETs) using randomized controlled trials (RCTs). Methods: Nine databases (PubMed, CINAHL, EMBASE, OASIS, NDSL, CNKI, Wanfang, J-STAGE, and CiNii) and the keywords "Essential tremor", "Benign tremor", "Familial tremor", and "Acupuncture" were used to compile RCTs that used acupuncture to treat ETs. Studies that were not RCTs, such as case studies, reviews, and essays, were excluded. The methodological quality of each RCT was assessed using the Cochrane risk-of-bias tool, and where appropriate, meta-analyses were performed. Results: Initially, 819 studies were found, but 773 were excluded after title and abstract screening. After further screening of the resulting 46 papers, eight RCTs were selected that had been published between 2003 and 2016, and the total effective rate (TER) was used as the primary evaluation method for all eight studies. It was found that the TER was significantly higher in treatment groups (83.33-96.7%) than in control groups (56.5-80.0%), and seven studies included in the meta-analysis showed positive results for acupuncture for ETs (Risk Ratio: 1.43, 95% Confidence Interval: 1.21-1.69, P<0.0001) Confidence Interval. Conclusions: This meta-analysis of clinical trials suggests that acupuncture is effective for treating ET patients; however, further studies are needed or larger populations to prove its effectiveness.

• Journal of Preventive Medicine and Public Health
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• v.49 no.6
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• pp.367-375
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• 2016

Objectives: The established theory that breast density is an independent predictor of breast cancer risk is based on studies targeting white women in the West. More Asian women than Western women have dense breasts, but the incidence of breast cancer is lower among Asian women. This meta-analysis investigated the association between breast density in mammography and breast cancer risk in Asian women. Methods: PubMed and Scopus were searched, and the final date of publication was set as December 31, 2015. The effect size in each article was calculated using the interval-collapse method. Summary effect sizes (sESs) and 95% confidence intervals (CIs) were calculated by conducting a meta-analysis applying a random effect model. To investigate the dose-response relationship, random effect dose-response meta-regression (RE-DRMR) was conducted. Results: Six analytical epidemiology studies in total were selected, including one cohort study and five case-control studies. A total of 17 datasets were constructed by type of breast density index and menopausal status. In analyzing the subgroups of premenopausal vs. postmenopausal women, the percent density (PD) index was confirmed to be associated with a significantly elevated risk for breast cancer (sES, 2.21; 95% CI, 1.52 to 3.21; $I^2=50.0%$). The RE-DRMR results showed that the risk of breast cancer increased 1.73 times for each 25% increase in PD in postmenopausal women (95% CI, 1.20 to 2.47). Conclusions: In Asian women, breast cancer risk increased with breast density measured using the PD index, regardless of menopausal status. We propose the further development of a breast cancer risk prediction model based on the application of PD in Asian women.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.3
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• pp.1141-1148
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• 2016

Background: A large number of studies have been published to investigate the association between the null genotype of glutathione S-transferase T1 (GSTT1) with gastric cancer. However, the results were inconsistent and conflicting. The aim of this study was to estimate the relationship between this polymorphism in the GSTT1 gene and gastric cancer risk in Asian populations by meta-analysis. Materials and Methods: A literature search was performed in PubMed, Embase, Chinese Biomedical database (CBM), Weipu database, Wanfang database, and China National Knowledge Infrastructure database (CNKI). Statistical analysis was conducted by using Review Manager 5.3. Results: Thirty-nine studies with a total of 7,737 gastric cancer cases and 10,823 controls were included in this meta-analysis. The meta-analysis of total studies showed that the null genotype in GSTT1 was associated with increased risk of gastric cancer in Asians (OR=1.19, 95% CI=1.08-1.31, p=0.0002). Subgroup analysis showed a significant relationship between GSTT1 null genotype and gastric cancer in East-Asians, as well as in subgroup analysis of hospital-based design. On subgroup analysis by smoking status, alcohol status, Helicobacter pylori infection status, and histology type, no significant association of this polymorphism with susceptibility to gastric cancer was found. Conclusions: In conclusion, the results showed that the null genotype of GSTT1 is significantly associated with an increased risk in gastric cancer in Asian populations.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.3937-3942
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• 2012

Background: Many studies have investigated possible association between the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and ovarian cancer risk, but the impact is still unclear owing to the obvious inconsistencies. This study was performed to quantify the strength of the association with a metaanalysis. Methods: We searched the PubMed, Embase, and CNKI databases for studies relating the association between MTHFR C677T polymorphism and ovarian cancer risk and estimated summary odds ratios (ORs) with confidence intervals (CIs) for assessment. Results: Finally, eight studies with a total of 3,379 ovarian cancer cases and 4,078 controls were included into this meta-analysis. Overall the showed that MTHFR C677T polymorphism was not associated with ovarian cancer risk under all genetic models ($OR_{T\;versus\;C}$ = 1.03, 95%CI 0.90-1.18; $OR_{TT\;versus\;CC}$ = 1.08, 95%CI 0.79-1.47; $OR_{TT\;versus\;TC+CC}$ = 1.05, 95%CI 0.80-1.37; $OR_{TT+TC\;versus\;CC}$ = 1.05, 95%CI 0.86-1.21). Meta-analyses of studies with confirmation of HWE also showed no significant association. Subgroup analyses by ethnicity showed there was no significant association in the Caucasians but MTHFR C677T polymorphic variant T contributed to increased risk of ovarian cancer in East Asians. No evidence of publication bias was observed. Conclusion: Meta-analyses of available data show that MTHFR C677T polymorphism is not associated with ovarian cancer risk in Caucasians, but the MTHFR polymorphic variant T may contribute to increased risk in East Asians.

• Korean Journal of Clinical Pharmacy
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• v.30 no.3
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• pp.169-176
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• 2020

Background: Most meta-analyses of risk factors for severe or critical outcomes in patients with COVID-19 only included studies conducted in China and this causes difficulties in generalization. Therefore, this study aimed to systematically evaluate the risk factors in patients with COVID-19 from various countries. Methods: PubMed, Embase, and Web of Science were searched for studies published on the mortality risk in patients with COVID-19 from January 1 to May 7, 2020. Pooled estimates were calculated as odds ratio (OR) with 95% confidence interval (CI) using the random-effects model. Results: We analyzed data from seven studies involving 26,542 patients in total in this systematic review and meta-analysis. Among the patients, 2,337 deaths were recorded (8.8%). Elderly patients and males showed significantly higher mortality rates than young patients and females; the OR values were 3.6 (95% CI 2.5-5.1) and 1.2 (95% CI 1.0-1.3), respectively. Among comorbidities, hypertension (OR 2.3, 95% CI 1.1-4.6), diabetes (OR 2.2, 95% CI 1.2-3.9), cardiovascular disease (OR 3.1, 95% CI 1.5-6.3), chronic obstructive pulmonary disease (OR 4.4, 95% CI 1.7-11.5), and chronic kidney disease (OR 4.2, 95% CI 2.0-8.6) were significantly associated with increased mortalities. Conclusion: This meta-analysis, involving a huge global sample, employed a systematic method for synthesizing quantitative results of studies on the risk factors for mortality in patients with COVID-19. It is helpful for clinicians to identify patients with poor prognosis and improve the allocation of health resources to patients who need them most.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.1
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• pp.327-332
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• 2015

Background: Gastric cancer is one of the frequently seen cancers in the world and it is the second most common reason for death due to cancer. The prognostic role of expression of p53 detected by immunohistochemistry in gastric cancer remains controversial. This meta-analysis aimed to explore any association between overexpression and survival outcomes. Materials and Methods: We systematically searched for studies investigating the relationships between expression of p53 detected by immunohistochemistry and prognosis of gastric cancer patients. Study quality was assessed using the Newcastle-Ottawa Scale. After careful review, survival data were extracted from eligible studies. A meta-analysis was performed to generate combined hazard ratios for overall survival and disease-free survival. Results: A total of 4.330 patients from 21 studies were included in the analysis. Our results showed tissue p53 overexpression in patients with gastric cancer to be associated with poor prognosis in terms of overall survival (HR, 1.610; 95% CI, 1.394 -5.235; p:<0.001). Pooled hazard ratio for disease free survival showed that p53 positivity or negativity were not statitistically significant (HR, 1.219; 95%CI, 0.782-1.899; p:0.382). Conclusions: The present meta-analysis indicated overexpression of p53 detected by immunohistochemistry to be associated with a poor prognosis in patients with gastric cancer.