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화학공장에서는 설비의 노후화 등으로 화재, 폭발, 독성물질 누출과 같은 중대산업사고의 발생위험성이 증대되고 있으며, 특히 중합반응공정에서 폭주반응에 의한 사고가 자주 발생되고 있다. 이와 같은 폭주반응은 반응공정이 열적 불안정 상태(thermal instability)에서 발생되므로 화학반응에 대한 열역학과 반응속도론으로 해석할 수 있다. 본 연구는 스티렌 회분식 현탁중합반응에서 폭주반응에 영향을 미치는 인자 중에서 총괄열전달계수의 영향을 해석하기 위해 다양한 실험조건(단량체/분산매 비, 개시제/단량체 비, 단량체질량, 냉각속도, 교반속도 등)에서 반응시간에 따른 온도변화를 측정하여 최대발열온도, 최대발열시간, 최대발열속도 등을 산출하고, 해석하였다. 그리고 자유라디칼 반응속도식과 에너지수지식으로부터 반응온도를 모사하고, 폭주반응에 미치는 총괄열전달계수의 영향을 해석하였다. 그 결과, 반응전화율 변화에 따른 반응조건의 변화를 고려한 총괄열전달계수와 열전달 면적을 사용한 경우에 이론 온도곡선은 실험값과 매우 잘 일치하여 제시된 모델식은 자유라디칼중합반응의 폭주반응을 예측하는데 사용이 가능하였다. 또한 모델식의 모사를 통해 공정제어적인 측면에서 중합반응의 안전적인 조업조건을 결정할 수 있었다.
Background: Restriction of dietary sodium intake for peritoneal dialysis (PD) patients is recommended, but there is limited information on the measurement and monitoring of sodium intake. We have developed a simple method to estimate daily sodium intake during the measurement of dialysis adequacy in PD patients. Methods: A total of 83 PD patients from the Asan Medical Center were enrolled into the study. The patients were divided into two groups based on residual renal function (RRF). We measured total sodium removal and estimated daily sodium intake using dietary recall for 1 day, during the assessment of dialysis adequacy. Results: There were 39 patients in the RRF(-) group and 44 in the RRF(+) group. In both groups, and all patients, there were significant positive correlations between sodium intake and total sodium removal: RRF(-) group, r = 0.598; RRF(+) group, r = 0.577; total patients, r = 0.595. There were linear relationships between dietary sodium intake and total sodium removal in both groups: RRF(-) group, sodium intake (mg/d) = 19.28 × peritoneal sodium removal (mEq/d) + 211; RRF(+) group, sodium intake (mg/d) = 15.40 × total sodium removal (mEq/d) + 609. All PD patients, sodium intake (mg/d) = 15.64 × total sodium removal (mEq/d) + 646. Conclusions: The measurement of total sodium removal during the assessment of dialysis adequacy could be an effective and simple method to estimate dietary sodium intake in PD patients. A dietary intake of 2,000 mg of sodium corresponds to a total sodium removal of approximately 87 mEq/d.
Introduction: Trace element, selenium deficiency is known to associate with impairment of thyroid hormone and cardiovascular diseases such as coronary artery disease, cardiomyopathy or sudden death. In hemodialysis (HD) patients, various causes may contribute to selenium deficiency, including decreased dietary intake, malabsorption, alteration of metabolism, and removal through dialysis itself. Therefore, we tried to investigate the effect of selenium deficiency on thyroid hormone and cardiovascular diseases in HD patients Methods: This cross-sectional study enrolled 83 end-stage renal disease patients who underwent HD in Jeju National University Hospital. The patients were divided into two groups based on serum selenium levels: 62 patients were normal level and 22 patients were selenium deficient. Thyroid hormones such as TSH, free T4 were measured. And presence of cardiovascular diseases, including ischemic heart disease (IHD), heart failure or cardiomyopathy using echocardiography, coronary computed tomography or coronary angiography were evaluated. Results: There were no significant differences in baseline characteristics including age, sex, presence of diabetes mellitus, hypertension medication between the two groups. Thyroid hormone impairment, including hypothyroidism and subclinical hypothyroidism showed higher tendency in selenium deficient group than that in non- selenium deficient group. ( 27 % vs 10 % P=0.06) The prevalence of ischemic heart disease was significantly higher in selenium deficient group than that in the non-selenium deficient group. ( 59 % vs 21 %, P=0.04 ) But there was no difference in heart failure defined as ejection fraction with below 40 %, and cardiomyopathy between the two groups. All patients with thyroid hormone impairment showed high prevalence of IHD and the coincidence of thyroid impairment and IHD was significantly higher than that in selenium deficient group than that in non-selenium deficient group. ( 18 % vs 4 % , p=0.014) Conclusion: This study showed the significant high prevalence of thyroid hormone impairment and IHD in HD patients with selenium deficiency. Selenium deficiency may be affect heart disease, associating with thyroid hormone impairment
Gastrointestinal cyst found within the oral cavity has been reported as a rare occurrence with less than 40 cases. The tongue is the preferred site with almost 60% of cysts occurring within oral cavity. The cyst usually shows an asymptomatic swelling in the floor of the mouth, about 30% of affected individuals have symptoms related to difficulties with feeding, swallowing and respiration. The histopathologic features of the cyst vary with respect to the type of epithelium lining; gastric, squamous, intestinal and respiratory epithelium. The pathogenesis is not known, but it may be related to entrapment of undifferentiated endoderm within oral cavity during early fetal development. In this article, we report a case of a gastrointestinal cyst of the tongue in a 16-month-old girl.
Endoscopic resection is currently accepted as a standard therapy for colon polyp because of its safety and efficiency. The indications for endoscopic resection have been expanded to treat mucosal colon cancer and submucosal tumor. The major complications of endoscopic resection are hemorrhage, perforation and post- polypectomy coagulation syndrome. Hemorrhage is the most common complication, and this can occur immediately following colonoscopic polypectomy or it can be delayed after completion of the procedure. Delayed hemorrhage usually occurs within 7 days and this can stop by itself or the hemorrhage can be controlled endoscopically in the majority of patients, with only the unusual and serious cases requiring transfusion, angiography and surgery. We experienced a case of delayed massive hemorrhage with hypotension that required transfusion 12 days after performing endoscopic resection for rectal carcinoid tumor. We report here on this case to provide a good example and to place emphasis on delayed massive hemorrhage after endoscopic resection. 내시경적 용종 절제술은 대장 용종의 표준 치료로 인정받고 있으며, 내시경 술기 및 기기의 발달로 내시경적 점막절제술 및 내시경적 점막하 박리술을 이용하여 점막에 국한된 조기 대장암 및 일부 점막하 종양의 치료로 발전하고 있다. 이와 같은 내시경적 절제술은 비교적 안전하며 삶의 질을 높일 수 있어 수술적 치료를 대체하고 있으나 출혈, 천공 및 용종 절제술 후 응고 증후군 등의 합병증이 발생할 수 있다. 내시경적 용종 절제술과 관련된 가장 흔한 합병증은 출혈로서 약 0.3∼6.1%에서 발생하며 시술 중에 발생하는 즉시 출혈과 시술 이후에 발생하는 지연 출혈로 나눌 수 있다. 지연 출혈의 경우 대부분 일주일 내에 소출혈의 양상을 보이게 된다. 저자들은 1.2 cm 크기의 직장 유암종을 내시경적 절제술로 제거한 후 조기 출혈 없이 퇴원하였으나, 시술 12일째 불안정한 활력 징후를 보이며 수혈 치료가 필요했던 대량 지연 출혈 1예를 경험하여 문헌 고찰과 함께 보고한다.
Understanding the underlying mechanisms of memory formation and maintenance has been a major goal in the field of neuroscience. Memory formation and maintenance are tightly controlled complex processes. Among the various processes occurring at different levels, gene expression regulation is especially crucial for proper memory processing, as some genes need to be activated while some genes must be suppressed. Epigenetic regulation of the genome involves processes such as DNA methylation and histone post-translational modifications. These processes edit genomic properties or the interactions between the genome and histone cores. They then induce structural changes in the chromatin and lead to transcriptional changes of different genes. Recent studies have focused on the concept of chromatin remodeling, which consists of 3D structural changes in chromatin in relation to gene regulation, and is an important process in learning and memory. In this review, we will introduce three major epigenetic processes involved in memory regulation: DNA methylation, histone methylation and histone acetylation. We will also discuss general mechanisms of long-term memory storage and relate the epigenetic control of learning and memory to chromatin remodeling. Finally, we will discuss how epigenetic mechanisms can contribute to the pathologies of neurological disorders and cause memory-related symptoms.