• Tribology and Lubricants
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• 제23권4호
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• pp.162-169
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• 2007

This paper deals with friction effects on the performance of double-bumped AFBs. The stiffness and damping coefficients of the double bump vary depending on the external load and its friction coefficient. The double bump can be either in the single or double active region depending on vertical deflection. The equivalent stiffness and damping coefficients of the bump system are derived from the vertical and horizontal deflection of the bump, including the friction effect. A static and dynamic performance analysis is carried out by using the finite difference method and the perturbation technique. The results of the performance analysis for a double-bumped AFB are compared with those obtained for a single-bumped AFB. This paper successfully proves that a double bumped AFB has higher load capacity, stiffness, and damping than a single-bumped AFB in a heavily loaded condition.

• 한국식품영양과학회지
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• 제19권2호
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• pp.156-162
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• 1990

Antimutagenic effect of doenjag (Korean fermented soy paste) on mutagenesis induced by aflatoxin B1 (AFB1) in Salmonella typhimurium strains TA98 and TA100 was studied. AFB1 revealed maximum mutagenicity at dose level of 1 $\mu$g/plate with metabolic activation system in both strains. Strong antiutagenic activity toward AFB1 was completely inhibited at the level of 50% of the doenjang extract. At the same concentration 64-66% and 39-53% of the AFB1 induced mutageneses were blocked when the methanol extracts of raw and cooked soybeans were added in the system respectively Raw soybeans showed higher ihhibition rate to the mutagenicity than cooked soybeans but the fermented soybeans(doenjang) was the most effective (p<0.05) Other soybean fermented foods such as commercial doenjang natto and miso were also exhibited some antimutagenic activities however the traditional doenjang was the most effective and then commercial doenjang. Natto and miso were less effective.

• Journal of Chest Surgery
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• 제25권8호
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• pp.856-862
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• 1992

The author reviewed 50 cases of positive sputum AFB patients following pulmonary resection of pulmonary tuberculosis [total 617 cases] operated on at the National Kongju Hospital during 6 years period, from January, 1985 to December, 1990. 1. There were 36 male and 14 female patients ranging from 20 to 50 years old[mean age, 33.8 years] 2. An average duration of pulmonary tuberculosis history was 7.5 years. 35 cases[76%] had many drug resistance of tuberculosis [above 5 drugs]. 3. The majority indication for pulmonary resection were persistent positive sputum AFB with cavity or destroyed lung or hemoptysis. 23 cases[46%] underwent pneumonectoy and 13 cases[23%] lobectomy. The postoperative complications occured in 19 cases [38%]. 4. 34 cases[68%] occured sputum AFB positive following operation unitil 6 months, and 6 cases[12%] occured 2 years later 5. 21 cases[42%] got conversion to negative sputum, and then 29 cases[58%] remained persistent positive sputum.

• Journal of Korean Biological Nursing Science
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• 제2권1호
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• pp.49-63
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• 2000

Aflatoxin $B_1(AFB_1)$ is a potent hepatotoxic and hepatocarcinogenic mycotoxin in human beings. It is accumulated in animal tissues and injured cell through variable metabolic pathway. This study was conducted to determine the effect of antioxidant vitamins on liver function enzymes and hepatic damage of $AFB_1$ treated mice. The 6 weeks old male ICR mice were randomly separated 6 groups, vehicle solvent or vitamin C(10 mg/kg/day) and vitamin E(63.8 mg/kg/day) were administered by intraperitoneal(i.p.) injection and 1 hr later, vehicle solution(DMSO) or $AFB_1$(0.4 mg/kg) were injected. The results obtained as follow ; The levels of liver function enzymes such as GOT, GPT, LDH, and alkaline phosphatase, in sera of mice were remarkably elevated by treatment with $AFB_1$ only. However, those enzymes were significantly alleviated by co-treatment with antioxidant vitamins(p<0.01). Especially the levels of LDH and ALK phosphatase were similar to those of control groups(p<0.01). The transmission electron microscopy(TEM) image of intracellular microrganelles on the liver cell of mice was also degenerated extremely by treatment with $AFB_1$, but vitamin C and vitamin E gave good effects on cellular deformation. The intracellular microrganelles such as mitochondria, endoplasmic reticulum, nucleus and nucleic membrane were nearly disappeared the cellular deformation by antioxidant vitamins co-administration. With above results, we could estimated that antioxidant vitamins blocked AFB1 induced hepatic cell damage.

• Asian-Australasian Journal of Animal Sciences
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• 제28권5호
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• pp.691-696
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• 2015

The objective of this study was to evaluate the quality of five commercial enzyme linked immunosorbent assay (ELISA) kits (A, B, C, D, and E) from different suppliers for detecting aflatoxin $B_1$ ($AFB_1$). $AFB_1$-free corn samples supplemented with different levels of $AFB_1$ (5, 10, and $20{\mu}g/kg$) were used as positive controls and 6 replicates of each control sample were tested to evaluate the accuracy and precision of these kits. In addition, we also evaluated the performance of these ELISA kits for $AFB_1$ in 30 feed samples, including corn, distillers dried grains with soluble, wheat samples, soybean meal, and poultry feed, which were verified by high performance liquid chromatography. Results showed that the coefficients of variation ranged from 1.18% to 16.22% in intra-plate and 2.85% to 18.04% in inter-plate for the determination of $AFB_1$. The half maximal inhibitory concentration for five kits ranged from 3.72 to $7.22{\mu}g/kg$. The quantitation limits of $AFB_1$ were all under the legal limit in China but somewhat inconsistent with kit instructions. Although the recovery rate of four of the five kits were either less than 90% or more than 110%, all these values were acceptable in practice. Two kits had high false positive rates (C and E). In conclusion, our results revealed that the qualities of five tested ELISA kits were significantly different.

• Tuberculosis and Respiratory Diseases
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• 제84권3호
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• pp.237-244
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• 2021

Background: The emergence of drug-resistant tuberculosis (TB), is a major menace to cast off TB worldwide. Line probe assay (LPA; GenoType MTBDRplus ver. 2) and Xpert MTB/RIF assays are two rapid molecular TB detection/diagnostic tests. To compare the performance of LPA and Xpert MTB/RIF assay for early diagnosis of rifampicin-resistant (RR) TB in acid-fast bacillus (AFB) smear-positive and negative sputum samples. Methods: A total 576 presumptive AFB patients were selected and subjected to AFB microscopy, Xpert MTB/RIF assay and recent version of LPA (GenoType MTBDRplus assay version 2) tests directly on sputum samples. Results were compared with phenotypic culture and drug susceptibility testing (DST). DNA sequencing was performed with rpoB gene for samples with discordant rifampicin susceptibility results. Results: Among culture-positive samples, Xpert MTB/RIF assay detected Mycobacterium tuberculosis (Mtb) in 97.3% (364/374) of AFB smear-positive samples and 76.5% (13/17) among smear-negative samples, and the corresponding values for LPA test (valid results with Mtb control band) were 97.9% (366/374) and 58.8% (10/17), respectively. For detection of RR among Mtb positive molecular results, the sensitivity of Xpert MTB/RIF assay and LPA (after resolving discordant phenotypic DST results with DNA sequencing) were found to be 96% and 99%, respectively. Whereas, specificity of both test for detecting RR were found to be 99%. Conclusion: We conclude that although Xpert MTB/RIF assay is comparatively superior to LPA in detecting Mtb among AFB smear-negative pulmonary TB. However, both tests are equally efficient in early diagnosis of AFB smear-positive presumptive RR-TB patients.

• Tuberculosis and Respiratory Diseases
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• 제47권6호
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• pp.747-756
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• 1999

연구배경: 폐결핵을 확진하는 방법은 결핵균의 증명이며 결핵균 동정을 하는 고전적인 방법인 항산균 도말 검사와 결핵균 배양 검사에 대해 상호 보완적으로 폐결핵의 보다 신속한 진단을 하는데 있어서 MTD의 유용성을 알아보고자 하였다. 방 법: 1997년 11월부터 1998년 5월까지 부산대학교 병원에 내원하여 폐결핵이 의심된 187명의 환자로부터 얻은 호흡기검체 267건(객담 187건, 기관지 세척액 94건)에 대해 각각 항산균 도말, 결핵균 배양 검사, MTD를 시행한 결과를 임상 소견과 연관지어 비교 분석하였다. 결 과: 1) 객담 검체에서 항산균 도말 검사, 결핵균 배양 결과와 비교하였을 때 항산균 도말 양성인 경우 결핵균 배양 검사와 비교한 MTD의 민감도는 75.6%, 도말 음성인 경우 결핵균 배양 검사와 비교한 MTD의 민감도는 61.9%, 특이도는 85.6%였다. 2) 기관지 세척액에서 항산균 도말 검사, 결핵균 배양 결과와 비교하였을 때 항산균 도말 양성인 경우 결핵균 배양 검사와 비교한 MTD의 민감도는 89.5%, 특이도는 28.6%, 도말 음성인 경우 결핵균 배양 검사와 비교한 MTD의 민감도는 89.5%, 특이도는 67.3%였다. 3) 객담과 기관지 세척액을 합한 경우 항산균 도말검사, 결핵균 배양 결과와 비교하였을 때 항산균 도말 양성인 경우에서 결핵균 배양 검사와 비교한 MTD의 민감도는 79.7%, 특이도는 20.0%를 보였으며, 항산균 도말 음성인 경우 결핵균 배양 검 사와 비교한 MTD의 민감도는 75.0%, 특이도는 80.3%를 보였다. 4) 결핵균 배양 결과와 비하여 MTD의 결과가 일치하지 않는 경우 MTD의 민감도는 67.5%, 특이도는 84.3%였으나 불일치 해결후에 MTD의 민감도는 79.2%, 특이 도는 84.4%를 보여 향상된 결과를 보였다. 5) 항산균 도말 음성, 결핵균 배양 음성이며 MTD만 양성인 31예에서 임상 경과 추적 및 항결핵제 치료 반응 웅의 분석에서 14예에서만 최종 폐결핵으로 진단되었으며 이 경우 MTD의 민감도는 45.2%였으며 진성 양성을 확인할 수 있었다. 6) 항산균 도말 음성, MTD 음성에서 mycobacterium species로 자란 13 건의 검체에서 Mycobacterium tuberculosis와 nontuberculous mycobacteria를 분리하기 위해 accuprobe M.tuberculosis complex culture kit를 이용하여 11건에서 M.tuberculosis로 배양되었으며 2건(17.3%)에서 비결핵 항산균이 배양되었다. 결 론: 이상의 결과로 볼 때 MTD는 빠르고 정확한 결핵균 진단에 유용한 것으로 생각되며, 폐결핵 진단에 있어서 MTD는 항산균 도말 검사 및 배양 검사와 병행함으로써 유용성이 높으며, 고전적인 진단 방법을 대체하기 보다는 상호 보완적인 방법으로 판단된다.

• 대한수의학회지
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• 제44권4호
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• pp.507-513
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• 2004

Aflatoxins are produced mainly by Aspergillus flavus and Aspergillus parasiticus that grow in improperly stored cereals. Aflatoxin B1 ($AFB_1$) is a potent hepatocarcinogen in a variety of experimental animals including human beings. In spite of a high attention to the hepatocarcinogenecity of $AFB_1$, the relative toxicity of aflatoxins ($AFB_2$ and $AFG_1$) is not fully clarified. Sprague-Dawley male rats were orally administered with $AFB_1$, $AFB_2$, and $AFG_1$ at the dose of 250 ${\mu}g/kg$ (additionally including a dose of $1250{\mu}g/kg $ for $AFB_1$) body weight. Animals were then killed at 12, 24 or 48 hrs following aflatoxin exposure. Subsequently the immunohistochemical examination of p53, cytochrome p450 1A1 (CYP450 1A1), and glutathione-S-transferase placental form (GST-P) were performed. The level of the 8-OxodG in the liver was determined. Expressions of CYP450 1A1 and p53 were high in the liver of rats through 48 hrs after treatment of $AFB_1$ at the single dose of $250{\mu}g/kg $. This pattern was more clear as increasing doses. The treatment of $AFB_2$ and $AFG_1$ did not affect the expression of CYP450 1A1 but it caused weak expression of p53. The activity of GST were not found in the liver of rats treated with aflatoxins. The formation of 8-OxodG by $AFB_1$ increased in a dose-dependent manner up to 24 hrs after a single treatment of $AFB_1$ thereafter decreased to the level of control. The treatment of $AFB_2$ and $AFG_1$ did not affect the levels of 8-OxodG in the liver of rats with increasing time. These results in the present study indicate that $AFB_1$ among aflatoxins with low comparable levels is the most toxic as determined by early biomarkers such as CYP450 1A1, p53, GST-P, and 8-OxodG.

• Asian-Australasian Journal of Animal Sciences
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• 제27권6호
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• pp.907-915
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• 2014

Alpha-lipoic acid (${\alpha}$-LA) is not only involved in energy metabolism, but is also a powerful antioxidant that can protect against hepatic oxidative stress induced by some drugs, toxins, or under various physiological and pathophysiological conditions. Here, we investigated the effect of ${\alpha}$-LA against liver oxidative damage in broilers exposed to aflatoxin $B_1$ ($AFB_1$). Birds were randomly divided into four groups and assigned different diets: basal diet, 300 mg/kg ${\alpha}$-LA supplementation in basal diet, diet containing 74 ${\mu}g/kg$ $AFB_1$, and 300 mg/kg ${\alpha}$-LA supplementation in diet containing 74 ${\mu}g/kg$ $AFB_1$, for 3 weeks. The results revealed that the addition of 300 mg/kg ${\alpha}$-LA protected against the liver function damage of broilers induced by chronic low dose of $AFB_1$ as estimated by a significant (p<0.05) change in levels of plasma total protein, albumin, alkaline phosphatase and the activities of liver glutamic-oxalacetic transaminase and glutamic-pyruvic transaminase. The histopathological analysis also showed that liver tissues were injured in the $AFB_1$ diet, but this effect was alleviated by the addition of 300 mg/kg ${\alpha}$-LA. Additionally, $AFB_1$ induced a profound elevation of oxidative stress in birds, as indicated by an increase in malondialdehyde level, a decrease in glutathione peroxidase activity and a depletion of the glutathione content in the liver. All of these negative effects were inhibited by treatment with ${\alpha}$-LA. Our results suggest that the inhibition of $AFB_1$-induced excess production of lipid peroxides and the maintenance of intracellular antioxidant status may play important roles in the protective effects of ${\alpha}$-LA against $AFB_1$-induced oxidative damage in the liver.

• 한국식품영양과학회지
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• 제34권5호
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• pp.581-585
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• 2005

김치의 발효와 숙성 에 관여하는 2종의 유산균과 3종의 유제품으로부터 분리된 유산균을 Caco-2 세포 부착성과 $AFB_1$ 흡착능에 대해 비교 검토하여 보았다. 또한 유산균을 생균군, 열처리군, 강산처리군으로 나누어 유산균의 부착성 및 흡착력이 세포벽의 구조와 관련이 있다는 보고를 재확인하고자 하였다. L. plantarum KCTC 3099의 경우 Caco-2 세포 부착성이나 $AFB_1$ 흡착능이 높게 나타났으며 이것은 양성 대조군으로 사용된 L. rhamnosus GG와 유사한 수준을 나타내었다. 하지만 L. mesenteroides KCTC 3001은 Caco-2 부착성은 다소 높게 나타났으나 $AFB_1$ 흡착능은 낮게 나타났다. 이것은 Caco-2세포에 결합하는 부위와 $AFB_1$에 결합하는 부위가 일치하지는 않는다는 것을 암시하는 것으로 사료된다. 또한 유산균의 처리방법에 따라서도 다양한 차이를 보였는데 본 실험에서는 강산처리군의 경우 보다 효과적인 것으로 나타났으며 세포벽의 주된 구조인 peptidoglycan과 polysaccharides이 강산의 처리에 의해 결합이 파괴되면서 Caco2 세포 부착성이나 $AFB_1$ 흡착능의 상승에 영향을 미쳤으리라 여겨진다. 하지만 강산처리에 의한 세포벽의 변화는 비특이적으로 발생하기 때문에 동일한 형태로 모든 유산균에 적용 되기는 어려울 것이며 각 유산균종의 세포벽 구조와 특이 성분의 함량에 따라 다양하게 변화가 일어날 것으로 사료된다.