• Journal of Periodontal and Implant Science
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• v.51 no.3
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• pp.163-178
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• 2021

Purpose: The aim of this study was to evaluate clinical factors affecting the longevity of fixed retainers and the influence of fixed retainers on periodontal health in periodontitis patients. Methods: In total, 52 patients with at least 2 years of follow-up after periodontal and orthodontic treatment were included in this study. After scaling and root planing, orthodontic treatment with fixed appliances or clear aligners was performed. Fixed retainers with twist-flex stainless steel wires were bonded to the palatal or lingual sides of anterior teeth. Changes in clinical parameters, including the plaque index, gingival index, calculus index (CI), probing pocket depth, and radiographic bone levels, were evaluated before bonding of fixed retainers and at a 12-month follow-up. Cumulative survival rates (CSRs) for retainer failure were evaluated according to sex, site, CI, stage of periodontitis, and the severity of the irregularity with the log-rank test and hazard ratios (HRs). Results: Twelve months after bonding of fixed retainers, improvements were observed in all clinical parameters except CI and radiographic bone gain. The overall CSR of the retainers with a CI <1 at the 12-month follow-up after bonding of fixed retainers was significantly higher than that of the retainers with a CI ≥1 at the 12-month follow-up (log-rank test; P<0.001). Patients with stage III (grade B or C) periodontitis had a higher multivariate HR for retainer failure (5.4; 95% confidence interval, 1.22-23.91; P=0.026) than patients with stage I (grade A or B) periodontitis. Conclusions: Although fixed retainers were bonded in periodontitis patients, periodontal health was well maintained if supportive periodontal treatment with repeated oral hygiene education was provided. Nonetheless, fixed retainer failure occurred more frequently in patients who had stage III (grade B or C) periodontitis or a CI ≥1 at 12-month follow-up after bonding of fixed retainers.

• Korean Circulation Journal
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• v.53 no.9
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• pp.606-618
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• 2023

Background and Objectives: The prognostic or safety implication of renin-angiotensin-aldosterone system inhibitors (RASi) in hypertrophic cardiomyopathy (HCM) are not well established, mainly due to concerns regarding left ventricular outflow tract (LVOT) obstruction aggravation. We investigated the implications of RASi in a sizable number of HCM patients. Methods: We enrolled 2,104 consecutive patients diagnosed with HCM in 2 tertiary university hospitals and followed up for five years. RASi use was defined as the administration of RASi after diagnostic confirmation of HCM. The primary and secondary outcomes were all-cause mortality and hospitalization for heart failure (HHF). Results: RASi were prescribed to 762 patients (36.2%). During a median follow-up of 48.1 months, 112 patients (5.3%) died, and 94 patients (4.5%) experienced HHF. Patients using RASi had less favorable baseline characteristics than those not using RASi, such as older age, more frequent history of comorbidities, and lower ejection fraction. Nonetheless, there was no difference in clinical outcomes between patients with and without RASi use (log-rank p=0.368 for all-cause mortality and log-rank p=0.443 for HHF). In multivariable analysis, patients taking RASi showed a comparable risk of all-cause mortality (hazard ratio [HR], 0.70, 95% confidence interval [CI], 0.43-1.14, p=0.150) and HHF (HR, 1.03, 95% CI, 0.63-1.70, p=0.900). In the subgroup analysis, there was no significant interaction of RASi use between subgroups stratified by LVOT obstruction, left ventricular (LV) ejection fraction, or maximal LV wall thickness. Conclusions: RASi use was not associated with worse clinical outcomes. It might be safely administered in patients with HCM if clinically indicated.

• Korean Circulation Journal
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• v.52 no.12
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• pp.890-900
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• 2022

Background and Objectives: Some individuals exhibit discrepancies between risk classifications assessed using clinical factors and those obtained by vascular imaging. We aimed to evaluate whether statins provide clinical outcome benefits in patients classified as having low to moderate cardiovascular risk but with carotid plaque. Methods: This was a retrospective propensity score matching study. A total of 12,158 consecutive patients undergoing carotid ultrasound between January 2012 to February 2020 were screened. Individuals with low to moderate cardiovascular risk who were not currently recommended for statin therapy but had carotid plaques were included. Among 1,611 enrolled individuals, 806 (statin group: 403, control group: 403) were analyzed. The primary outcomes were major adverse cardiovascular and cerebrovascular events (MACCEs: cardiovascular death, myocardial infarction, coronary revascularization, and ischemic stroke or transient ischemic attack) and all-cause mortality. Results: During the median follow-up of 6.0 years, the incidence of MACCEs did not differ between the groups (6.1 and 5.7/1,000 person-years in the control and statin groups, respectively; adjusted hazard ratio [HR], 0.95; p=0.90). The incidence of all-cause mortality did not differ (3.9 and 3.9/1,000 person-years, respectively; adjusted HR, 1.02; p=0.97). Kaplan-Meier curves revealed similar rates of MACCEs (log-rank p=0.72) and all-cause mortality (log-rank p=0.99) in the 2 groups. Age and smoking were independent predictors of MACCEs. Subgroups exhibited no differences in clinical outcomes with statin use. Conclusions: Benefit of statin therapy was likely to be limited in low to moderate risk patients with carotid plaques. These results could guide physicians in clinical decision-making regarding cardiovascular prevention.

• Journal of Gastric Cancer
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• v.24 no.4
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• pp.451-463
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• 2024

Purpose: Although laparoscopic distal gastrectomy has rapidly replaced open distal gastrectomy, laparoscopic total gastrectomy (LTG) is less frequently performed owing to technical difficulties. Robotic surgery could be an appropriate minimally invasive alternative to LTG because it alleviates the technical challenges posed by laparoscopic procedures. However, few studies have compared the oncological safety of robotic total gastrectomy (RTG) with that of LTG, especially for advanced gastric cancer (AGC). Herein, we aimed to assess the oncological outcomes of RTG for AGC and compare them with those of LTG. Materials and Methods: We retrospectively reviewed 147 and 204 patients who underwent RTG and LTG for AGC, respectively, between 2007 and 2020. Long-term outcomes were compared using inverse probability of treatment weighting (IPTW). Results: After IPTW, the 2 groups exhibited similar clinicopathological features. The 5-year overall survival was comparable between the 2 groups (88.5% [95% confidence interval {CI}, 79.4%-93.7%] after RTG and 87.3% [95% CI, 80.1%-92.0%]) after LTG; log-rank P=0.544). The hazard ratio (HR) for death after RTG compared with that after LTG was 0.73 (95% CI, 0.40-1.33; P=0.304). The 5-year relapse-free survival was also similar between the 2 groups (75.7% [95% CI, 65.2%-83.4%] after RTG and 76.4% [95% CI, 67.9%-83.0%] after LTG; log-rank P=0.850). The HR for recurrence after RTG compared with that after LTG was 0.93 (95% CI, 0.60-1.46; P=0.753). Conclusions: Our findings revealed that RTG and LTG for AGC had similar long-term outcomes. RTG is an oncologically safe alternative to LTG and has technical advantages.

• Journal of Food Hygiene and Safety
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• v.14 no.4
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• pp.319-326
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• 1999

Recently, it is continuously rising to concern about the health risk being induced by microorganisms in food such as Escherichia coli O157:H7 and Listeria monocytogenes. Various organizations and regulatory agencies including U.S.FPA, U.S.DA and FAO/WHO are preparing the methodology building to apply microbial quantitative risk assessment to risk-based food safety program. Microbial risks are primarily the result of single exposure and its health impacts are immediate and serious. Therefore, the methodology of risk assessment differs from that of chemical risk assessment. Microbial quantitative risk assessment consists of tow steps; hazard identification, exposure assessment, dose-response assessment and risk characterization. Hazard identification is accomplished by observing and defining the types of adverse health effects in humans associated with exposure to foodborne agents. Epidemiological evidence which links the various disease with the particular exposure route is an important component of this identification. Exposure assessment includes the quantification of microbial exposure regarding the dynamics of microbial growth in food processing, transport, packaging and specific time-temperature conditions at various points from animal production to consumption. Dose-response assessment is the process characterizing dose-response correlation between microbial exposure and disease incidence. Unlike chemical carcinogens, the dose-response assessment for microbial pathogens has not focused on animal models for extrapolation to humans. Risk characterization links the exposure assessment and dose-response assessment and involve uncertainty analysis. The methodology of microbial dose-response assessment is classified as nonthreshold and thresh-old approach. The nonthreshold model have assumption that one organism is capable of producing an infection if it arrives at an appropriate site and organism have independence. Recently, the Exponential, Beta-poission, Gompertz, and Gamma-weibull models are using as nonthreshold model. The Log-normal and Log-logistic models are using as threshold model. The threshold has the assumption that a toxicant is produce by interaction of organisms. In this study, it was reviewed detailed process including risk value using model parameter and microbial exposure dose. Also this study suggested model application methodology in field of exposure assessment using assumed food microbial data(NaCl, water activity, temperature, pH, etc.) and the commercially used Food MicroModel. We recognized that human volunteer data to the healthy man are preferred rather than epidemiological data fur obtaining exact dose-response data. But, the foreign agencies are studying the characterization of correlation between human and animal. For the comparison of differences to the population sensitivity: it must be executed domestic study such as the establishment of dose-response data to the Korean volunteer by each microbial and microbial exposure assessment in food.

• Korean Journal of Radiology
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• v.21 no.6
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• pp.695-706
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• 2020

Objective: To investigate the technical and clinical efficacy of the percutaneous insertion of a biliary metallic stent, and to identify the factors associated with biliary stent dysfunction in patients with malignant duodenobiliary obstruction. Materials and Methods: The medical records of 70 patients (39 men and 31 women; mean age, 63 years; range, 38-90 years) who were treated for malignant duodenobiliary obstruction at our institution between April 2007 and December 2018, were retrospectively reviewed. Variables found significant by univariate log-rank analysis (p < 0.2) were considered as suitable candidates for a multiple Cox's proportional hazard model. Results: The biliary stents were successfully placed in all 70 study patients. Biliary stent insertion with subsequent duodenal stent insertion was performed in 33 patients and duodenal stent insertion with subsequent biliary stent insertion was performed in the other 37 study subjects. The median patient survival and stent patency time were 107 days (95% confidence interval [CI], 78-135 days) and 270 days (95% CI, 95-444 days), respectively. Biliary stent dysfunction was observed in 24 (34.3%) cases. Multiple Cox's proportional hazard analysis revealed that the location of the distal biliary stent was the only independent factor affecting biliary stent patency (hazard ratio, 3.771; 95% CI, 1.157-12.283). The median biliary stent patency was significantly longer in patients in whom the distal end of the biliary stent was beyond the distal end of the duodenal stent (median, 327 days; 95% CI, 249-450 days), rather than within the duodenal stent (median, 170 days; 95% CI, 115-225 days). Conclusion: The percutaneous insertion of the biliary metallic stent appears to be a technically feasible, safe, and effective method of treating malignant duodenobiliary obstruction. In addition, a biliary stent system with a distal end located beyond the distal end of the duodenal stent will contribute towards longer stent patency in these patients.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.157-163
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• 2005

Because of their widespread occurrence and substantial biological activity, halogenated aromatic hydrocarbons are one of the important classes of contaminants in the environment. We have performed comparative molecular field analysis (CoMFA) on structurally diverse ligands of Ah (dioxin) receptor to explore the physico-chemical requirements for binding. All CoMFA models have given $q^{2}$ value of more than 0.5 and $r^{2}$ value of more than 0.83. The predictive ability of the models was validated by an external test set, which gave satisfactory predictive $r^{2}$ values. Best predictions were obtained with CoMFA model of combined modified training set ($q^{2}=0.631,\;r^{2}=0.900$), giving predictive residual value = 0.002 log unit for the test compound. We have suggested a model comprises of four structurally different compounds, which offers a good predictability for various ligands. Our QSAR model is consistent with all previously established QSAR models with less structurally diverse ligands. The implications of the CoMFA/QSAR model presented herein are explored with respect to quantitative hazard identification of potential toxicants.

• Korean journal of food and cookery science
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• v.27 no.2
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• pp.61-71
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• 2011

This study was conducted to estimate the shelf-life of Kimbab manufactured using a Hazard Analysis and Critical Control Point (HACCP). We performed a microbiological verification after applying the HACCP plan to Kimbab. Additionally, the shelf-life of Kimbab at each holding temperature was calculated as a regression equation between the aerobic plate counts and holding time during the storage period. The critical control points of the HACCP plan, that were applied to Kimbab, included: cold-holding of refrigerated foods, checking the endpoint cooking temperature of heated food, and cold-holding of cooked foods. As a result of the microbiological verification of Kimbab, the aerobic plate counts averaged 3.46 log CFU/g. In contrast, the coliforms, E. coli, Staphylococcus aureus, and Salmonella spp. were not detected in any of the samples. The estimated shelf-life of Kimbab was calculated to be 45 hours at $10^{\circ}C$, 29 hours at $15^{\circ}C$, 6 hours at $25^{\circ}C$ and 3 hours at $35^{\circ}C$. In conclusion, manufacturers should apply a prerequisite program and a HACCP system for a safe consumption of ready-to-eat foods and label products with a proper shelf-life. Distributors should control the proper holding time-temperature until sale and consumers should eat immediately after purchasing ready-to-eat foods.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.21-34
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• 2006

The simulation of tsunami inundation using detailed bathymetry and topography is required to establish the countermeasure of disaster mitigation and the tsunami hazard map. In this study, a simulation of the 1983 tsunami event in the East Sea using parallel finite element model, which is possible to simulate with suitable accuracy by the Beowulf parallel computation method, is performed to produce detailed features of coastal inundation. Results of simulations are compared with measured data. The evolution of statistic distribution of tsunami heights is studied numerically and the distribution functions of tsunami heights show a tendency to the log-normal curve along coastal area.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.174-174
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• 2011

강우의 공간적 변동성을 파악하기 어려운 우량계 관측방법의 한계를 극복하기 위한 방법으로 레이더를 이용한 강우관측이 주목받고 있다. 레이더는 실시간으로 넓은 지역의 강우 현황을 파악하는 것이 가능하므로 강우 예측에 있어 매우 큰 장점을 갖는다. 그러나 레이더를 통해 관측된 강우는 실제값을 의미하지는 않는 것이 사실이다. 이에 본 연구에서는 레이더 및 우량계 강우자료가 대수정규분포를 따른다고 가정하는 경우의 편의보정 문제를 살펴보았다. 이를 위해 대수정규분포를 따르는 자료에 대한 평균값, 중앙값 및 최빈값에 대한 회귀선을 유도하여 검토하였다. 본 연구에서는 2003년에 발생한 태풍 매미로 인해 발생한 강우 사상이 대상 호우사상으로 적용되었으며, 이에 대한 강우자료는 관악산 레이더 강우 자료와 레이더의 관측 반경 내 존재하는 국토해양부 산하 127개 우량계 시강우 자료이다. 그 결과, 독립변수로 사용된 강우자료에 따라 그 차이가 매우 큰 것으로 나타났다. 독립변수로 레이더 강우를 사용한 경우에는 G/R 보정된 레이더 강우의 과소추정 문제가 나타날 것으로 보인다. 반대로 우량계 강우를 독립변수로 한 회귀선에서는 레이더 강우의 보정결과가 어떻게 나타날지는 뚜렷하지 않다. 따라서 위와 같은 회귀선을 통해 보정한 레이더 강우의 검토가 추가적으로 필요할 것으로 보인다. 그러나 이 경우에서는 독립변수로 레이더 강우를 사용한 경우에서 나타나는 레이더 강우의 과소추정 문제가 어느 정도 극복될 것으로 보인다. 아울러 일반적으로 적용되고 G/R 보정계수에 대한 검토 및 이에 대한 비교가 또한 필요할 것으로 판단된다.