Suggested Inhalation Toxicity Reference Value for Lanthanum Oxide and Neodymium Oxide

본 연구는 희토류 중 노출기준이 제정되지 않은 산화 란타넘(Lanthanum Oxide)과 산화 네오디뮴(Neodymium Oxide)에 대해 흡입독성참고치(Reference Concentration, RfC)를 제안하고자 하였다. RfC 제안을 위해 Sprague-Dawley(SD) Rat를 이용한 28일 산화란타넘 및 산화네오디뮴 흡입독성시험을 RfC산출 자료로 선정하였고, 흡입독성시험의 결과로 LOAEL 0.5 ㎎/㎥이 제안되었다. 처음에는 Lowest Observed Adverse Effect Level(LOAEL)을 시작값(Point of Departure, POD)으로 하여 한국산업안전보건공단, 미국 환경보호청(Environmental Protection Agency, US EPA), REACH(Registration, Evaluation, Authorization and restriction of Materials), ECETOC TRA(European Center for Ecotoxicology and Toxicology of Materials Target Risk Assessment) 총 네 기관의 독성참고치 산출방식을 가지고 계산하였다 위 기관들이 제안하는 방식으로 계산한 결과 한국산업안전보건공단의 RfCw(RfC for workers)는 0.139 ㎍/㎥, REACH TGD(Technical Guidance Document)의 DNEL(Derived No Effect Level)은 0.465 ㎍/㎥, ECETOC TRA의 DNEL은 0.775 ㎍/㎥의 결과가 산출되었다. 다만, US EPA의 RfC 산출 방식의 경우 불확실성 계수(Uncertainty Factor, UF)가 최대 기준인 3,000을 초과하여 RfC의 신뢰성이 떨어지기에 이를 수정하여 신뢰할만한 RfC를 제안하고자 하였고, 이에 UF를 낮춰 신뢰성을 확보하고자 세 가지 방법을 적용하였다. 첫 번째는 RDDR(Regional Deposited Dose Ratio) 산출로 시작값을 재환산하여 보다 적절한 수치로 인체에 적용하는 방법. 두 번째는 폐 내 화학물질의 침착률을 계산한 독성동태학으로 종 간 차이에 의한 UF를 감소시키는 방법. 세 번째는 기존 시작값인 LOAEL대신 Benchmark dose lower bound confidence limit(BMDL)을 제시하여 LOAEL 적용에 대한 불확실성을 감소시키는 방법이다. 위 세 가지 방법의 적용 결과 산화란타넘의 RDDR과 BMDL은 0.474, 0.073 ㎎/㎥, 산화네오디뮴의 RDDR과 BMDL은 0.682, 0.269 ㎎/㎥으로 계산되었고, 새롭게 RfC를 계산한 결과 산화란타넘은 0.288 ㎍/㎥, 산화네오디뮴은 1.529 ㎍/㎥로 산출되었다. 이 결과 산출에 이용된 UF를 PPRTVs에 제시된 타 희토류의 UF 값을 비교하였으며, 비교결과 PPRTVs에 적용된 UF범위는 300~10,000이고, 산화란타넘과 산화네오디뮴의 UF는 90인 것을 알 수 있었다. In this study, Reference Concentration(RfC) is proposed for Lanthanum Oxide and Neodymium Oxide for the establishment of exposure criteria. For the RfC proposal, 28days repeated inhalation toxicity studies of nano-sized Lanthanum Oxide and Neodymium Oxide in male Sprague-Dawley rats were selected as the RfC calculation data which include LOAEL(0.5 mg/㎥) as POD. Toxicological reference values were calculated by conventional methods. For example, RfC of US EPA, RfCw of KOSHA, DNEL of REACH TGD, ECETOC TRA. However, the reliability of the calculated RfC value was low, and three methods were proposed to increase the reliability. First, the method of converting POD using RDDR calculation. Second, the method to reduce UF by toxicokinetics about interspecies differences. Third, the method to reduce UF about severity by presenting BMDL instead of LOAEL. As a result of the application of the above three methods, the RfC of Lanthanum Oxide was calculated as 0.288 ㎍/㎥, and the RfC of Neodymium Oxide was 1.529 ㎍/㎥. And the calculated UFs of Lanthanum Oxide and Neodymium Oxide is 90.open석

Preventing and Controlling Bleeding in Gastric Endoscopic Submucosal Dissection

Although techniques and instruments for endoscopic submucosal dissection (ESD) have improved, bleeding is still the most common complication. Minimizing the occurrence of bleeding is important because blood can interfere with subsequent procedures. Generally, ESD-related bleeding can be divided into intraprocedural and postprocedural bleedings. Postprocedural bleeding can be further classified into early post-ESD bleeding which occurs within 48 hours after ESD and late post-ESD bleeding which occurs later than 48 hours after ESD. A basic principle for avoiding intraprocedural bleeding is to watch for vessels and coagulate them before cutting. Several countertraction devices have been designed to minimize intraprocedural bleeding. Methods for reducing postprocedural bleeding include administration of proton-pump inhibitors or prophylactic coagulation after ESD. Medical adhesive spray such as n-butyl-2-cyanoacrylate is also an option for preventing postprocedural bleeding. Various endoscopic treatment modalities are used for both intraprocedural and postprocedural bleeding. However, hemoclipping is infrequently used during ESD because the clips interfere with subsequent resection. Bleeding that occurs as a result of ESD can usually be managed easily. Nonetheless, more effective ways to prevent bleeding, including reliable ESD techniques, must be developed.ope

Effects of the New Prokinetic Agent DA-9701 Formulated With Corydalis Tuber and Pharbitis Seed in Patients With Minimal Change Esophagitis: A Bicenter, Randomized, Double Blind, Placebo-controlled Study.

BACKGROUND/AIMS: DA-9701 (Motilitone) is a new prokinetic agent formulated with Corydalis Tuber and Pharbitis Seed. We assessed the efficacy of DA-9701 in symptomatic patients with minimal change esophagitis. METHODS: Patients with minimal change esophagitis presenting with reflux or dyspeptic symptoms were randomly assigned to receive either DA-9701 30 mg or placebo t.i.d. (means 3 times a day). After 4 weeks of treatment, the primary efficacy end point determined by changes of the Nepean dyspepsia index questionnaire-Korean version (NDI-K) symptom scores, was analyzed. RESULTS: Forty-two and 39 patients were assigned to the treatment and control groups, respectively. After 4 weeks, NDI-K symptom scores were reduced from 35.4 to 13.5 (P < 0.001) and from 43.0 to 27.7 (P < 0.001) in the treatment and the control groups, respectively. However, changes in the symptom scores did not differ between the 2 groups (P = 0.741). Although the quality of life scores were significantly improved after 4 weeks in both groups, changes in the quality of life score between the baseline value and that at 4 weeks did not differ between the 2 groups. The reflux symptom score was significantly improved in the treatment group compared to the placebo group in patients aged 65 years or older (P = 0.035). CONCLUSIONS: Although NDI-K symptom scores and quality of life scores were improved after 4 weeks of treatment compared with baseline values in patients with minimal change esophagitis, DA-9701 did not improve the symptom scores or quality of life scores compared with the placebo.ope

Role of Long Non-coding Ribonucleic Acid in Gastrointestinal Cancer

With the improvement of high-throughput genomic technology such as microarray and next-generation sequencing over the last ten to twenty year, we have come to know that the portion of the genome responsible for protein coding constitutes just approximately 1.5%. The remaining 98.5% of the genome not responsible for protein coding have been regarded as 'junk DNA'. More recently, however, 'Encyclopedia of DNA elements project' revealed that most of the junk DNA were transcribed to RNA regardless of being translated into proteins. In addition, many reports support that a lot of these non-coding RNAs play a role in gene regulation. In fact, there are various functioning short non-coding RNAs including rRNA, tRNA, small interfering RNA, and micro RNA. Mechanisms of these RNAs are relatively well-known. Until recently, however, little is known about long non-coding RNAs which consist of 200 nucleotides or more. In this article, we will review the representative long non-coding RNAs which have been reported to be related to gastrointestinal cancers and to play a certain role in its pathogenesis.ope

Assessing the stability and safety of procedure during endoscopic submucosal dissection according to sedation methods: A randomized trial

BACKGROUND: Although endoscopic submucosal dissection (ESD) is routinely performed under sedation, the difference in ESD performance according to sedation method is not well known. This study attempted to prospectively assess and compare the satisfaction of the endoscopists and patient stability during ESD between two sedation methods. METHODS: One hundred and fifty-four adult patients scheduled for ESD were sedated by either the IMIE (intermittent midazolam/propofol injection by endoscopist) or CPIA (continuous propofol infusion by anesthesiologist) method. The primary endpoint of this study was to compare the level of satisfaction of the endoscopists between the two groups. The secondary endpoints included level of satisfaction of the patients, patient's pain scores, events interfering with the procedure, incidence of unintended deep sedation, hemodynamic and respiratory events, and ESD outcomes and complications. RESULTS: Level of satisfaction of the endoscopists was significantly higher in the CPIA Group compared to the IMIE group (IMIE vs. CPIA; high satisfaction score; 63.2% vs. 87.2%, P=0.001). The incidence of unintended deep sedation was significantly higher in the IMIE Group compared to the CPIA Group (IMIE vs. CPIA; 17.1% vs. 5.1%, P=0.018) as well as the number of patients showing spontaneous movement or those requiring physical restraint (IMIE vs. CPIA; spontaneous movement; 60.5% vs. 42.3%, P=0.024, physical restraint; 27.6% vs. 10.3%, P=0.006, respectively). In contrast, level of satisfaction of the patients were found to be significantly higher in the IMIE Group (IMIE vs. CPIA; high satisfaction score; 85.5% vs. 67.9%, P=0.027). Pain scores of the patients, hemodynamic and respiratory events, and ESD outcomes and complications were not different between the two groups. CONCLUSION: Continuous propofol and remifentanil infusion by an anesthesiologist during ESD can increase the satisfaction levels of the endoscopists by providing a more stable state of sedation.ope

The association between the use of proton pump inhibitors and the risk of hypomagnesemia: a systematic review and meta-analysis.

BACKGROUND: Although many case reports have described patients with proton pump inhibitor (PPI)-induced hypomagnesemia, the impact of PPI use on hypomagnesemia has not been fully clarified through comparative studies. We aimed to evaluate the association between the use of PPI and the risk of developing hypomagnesemia by conducting a systematic review with meta-analysis. METHODS: We conducted a systematic search of MEDLINE, EMBASE, and the Cochrane Library using the primary keywords "proton pump," "dexlansoprazole," "esomeprazole," "ilaprazole," "lansoprazole," "omeprazole," "pantoprazole," "rabeprazole," "hypomagnesemia," "hypomagnesaemia," and "magnesium." Studies were included if they evaluated the association between PPI use and hypomagnesemia and reported relative risks or odds ratios or provided data for their estimation. Pooled odds ratios with 95% confidence intervals were calculated using the random effects model. Statistical heterogeneity was assessed with Cochran's Q test and I2 statistics. RESULTS: Nine studies including 115,455 patients were analyzed. The median Newcastle-Ottawa quality score for the included studies was seven (range, 6-9). Among patients taking PPIs, the median proportion of patients with hypomagnesemia was 27.1% (range, 11.3-55.2%) across all included studies. Among patients not taking PPIs, the median proportion of patients with hypomagnesemia was 18.4% (range, 4.3-52.7%). On meta-analysis, pooled odds ratio for PPI use was found to be 1.775 (95% confidence interval 1.077-2.924). Significant heterogeneity was identified using Cochran's Q test (df = 7, P<0.001, I2 = 98.0%). CONCLUSIONS: PPI use may increase the risk of hypomagnesemia. However, significant heterogeneity among the included studies prevented us from reaching a definitive conclusion.ope

Feasibility of terahertz reflectometry for discrimination of human early gastric cancers

We have investigated the feasibility of THz time-domain reflectometry for the discrimination of human early gastric cancer (EGC) from the normal gastric region. Eight fresh EGC tissues, which were resected by endoscopic submucosal dissection, were studied. Of them, six lesions were well discriminated on THz images and the regions well correlated with tumor regions on pathologically mapped images. Four THz parameters could be suggested for quantitative discrimination of EGCs.ope

Clinical efficacy of endoscopic treatment for benign colorectal stricture: balloon dilatation versus stenting

BACKGROUND/AIMS: There has been a lack of research comparing balloon dilatation and self-expandable metal stent (SEMS) placement to determine which is better for long-term clinical outcomes in patients with benign colorectal strictures. We aimed to compare the clinical efficacy and complication rates of balloon dilatation and SEMS placement for benign colorectal strictures from a variety of causes. METHODS: Between January 1999 and January 2012, a total of 43 consecutive patients who underwent endoscopic treatment for benign colorectal stricture (balloon only in 29 patients, SEMS only in seven patients, and both procedures in seven patients) were retrospectively reviewed. RESULTS: Thirty-six patients underwent endoscopic balloon dilatation, representing 65 individual sessions, and 14 patients received a total of 17 SEMS placements. The initial clinical success rates were similar in both groups (balloon vs SEMS, 89.1% vs 87.5%). Although the reobstruction rates were similar in both groups (balloon vs SEMS, 54.4% vs. 57.1%), the duration of patency was significantly longer in the balloon dilatation group compared with the SEMS group (65.5±13.3 months vs. 2.0±0.6 months, p=0.031). CONCLUSIONS: Endoscopic balloon dilatation is safe and effective as an initial treatment for benign colorectal stricture and as an alternative treatment for recurrent strictures.ope

Development of Arthrobacter woluwensis Bacteremia in a Patient with Multiple Myeloma: A Case Report and Comprehensive Literature Review.

Arthrobacter spp., which are coryneform gram-positive bacilli, are widely distributed in the environment, including soil. In humans, infection with Arthrobacter is recognized as an opportunistic infection. In particular, since the first reported case in 1996, human infection by A. woluwensis has been reported only four times. We report on a case of A. woluwensis bacteremia in a 76-year-old female patient with multiple myeloma. Performance of 16S rRNA gene sequence analyses resulted in identification of A. woluwensis. The patient was treated with teicoplanin, and the central venous port was removed. Since then, no growth has been observed on repeated blood cultures. The patient was discharged well after the fever subsided.ope

병렬컴퓨팅을 이용한 램가속기의 3차원 유동해석

학위논문(석사)--서울대학교 대학원 :기계항공공학부,2003.Maste