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Comparative Study of the Antioxidative Potential of Common Natural Flavonoids and Isoflavonoids
라메쉬,Niranjan Koirala,이주호,이희철,송재경 한국미생물·생명공학회 2013 한국미생물·생명공학회지 Vol.41 No.3
2,2'-diphenylpicrylhydrazyl (DPPH•) assay와 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS+) decolorization assay는 자연상태의 플라보노이드와 이소플라보노이드의 항산화 활성을 확인하는데 사용된다. 억제중간값(half maximal inhibitory concentration(IC50) values)과 트롤록스당량 항산화능값(trolox equivalent antioxidant capacity (TEAC) values)은 DPPH• assay와 ABTS+ assay로 계산되었다. DPPH assay 결과, 쿼세틴(quercetin)은 가장 강한 항산화 능력을 가졌고 뒤이어 피세틴(fisetin), 7,8-디하이드록시플라본(7,8-dihydroxyflavone), 모린(morin), 캠퍼롤(kaempferol) 순이었다. 쿼세틴, 피세틴, 7,8-디하이드록시플라본은 부틸하이드록시 아니솔(butyl hydroxyl anisole)보다 더 높은 항산화 능력을 가졌다. 쿼세틴은 플라보노이드와 이소플로보노이드 중에서 TEAC 값이 가장 높았고 뒤이어 3-하이드록시플로본(3-hydroxyflavone), 피세틴, 7,8-디하이드록시플라본과 모린 순이었다. 다른 나머지 플라보노이드와 이소플라보노이드는 트롤록스 보다 더 약한 ABTS+ 분해능력(scavenging potential)을 가졌다. 테스트된 13개 플라보노이드/이소플라보노이드에서 이소플라보노이드는 플라보노이드보다 매우 약한 항산화 능력을 보였다. The half maximal inhibitory concentration (IC50) values and trolox equivalent antioxidant capacity (TEAC) values were calculated by a 2,2'-diphenylpicrylhydrazyl (DPPH)· assay and a 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS+·)assay, in order to determine the antioxidative activities of the compounds. On the basis of the DPPH assay, quercetin had the strongest antioxidative potential of the flavonoids, followed in order by fisetin, 7,8-dihydroxyflavone, morin and kaempferol. Quercetin, fisetin and 7,8-dihydroxyflavone had higher antioxidant potentials than butyl hydroxyl anisole. Quercetin had the highest TEAC value amongst the flavonoids and isoflavonoids, followed in order by 3-hydroxyflavone, fisetin, 7,8-dihydroxyflavone and morin. Comparatively, isoflavonoids were found to have significantly weaker antioxidative potential than the flavonoids.
Biosynthesis of a novel fisetin glycoside from engineered Escherichia coli
라메쉬,Prakash Parajuli,Luan Luong Chu,김승영,송재경 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.43 No.-
Escherichia coli BL21(DE3)/DpgiDzwfDgalU mutant was engineered by overexpressing thymidinediphosphate (dTDP)-D-glucose synthase (tgs), dTDP-D-glucose 4,6-dehydratase (dh), and a sugaraminotransferase (wecE) from different sources to produce a pool of dTDP-4-amino-4,6-dideoxy-Dgalactosein the cell cytosol. To this recombinant mutant, two Arabidopsis thaliana glycosyltransferases(ArGT-3 and ArGT-4) were overexpressed to generate two glycosylation platforms (E. coli BL21(DE3)/DpgiDzwfDgalUTDW-3 and E. coli BL21(DE3)/DpgiDzwfDgalUTDW-4), which were accessed for theglycosylation offisetin. As a result, one of the two systems, E. coli BL21(DE3)/DpgiDzwfDgalUTDW-3, wasable to conjugate 4-amino-4,6-dideoxy-D-galactose sugar at the 3-OH position offisetin, producing anunnaturalfisetin 3-O-4-amino-4,6-dideoxy-D-galactoside.
라메쉬 쿠마 라마,권구락 한국차세대컴퓨팅학회 2015 한국차세대컴퓨팅학회 논문지 Vol.11 No.5
MRI 영상에 있어 노이즈를 제거하기 위한 새로운 방법을 제안한다. MRI영상은 실영상과 허상영상으로부터 계산되어진 영상과의 의존적인 Rician 노이즈가 포함되어져 만들어진다. NLM 필터는 추가적인 노이즈에 대해 효과적인 것으로 증명되어진다. 비슷하게도 디노이징 기반 웨이브렛 변환은 더 좋은 노이즈 추정을 한다. 제안된 알고리듬은 기능적 3단계로 디노이징 과정을 수행한다. 첫 번째로 노이즈 영상은 웨이블렛 변환을 적용에 의한 다수의 서브밴드에 나타난다. NLM 필터는 웨이브렛 필터 뱅크를 사용한 신호 분해의 저주파 성분의 서브밴드에 적용되어진다. 실 노이즈 영상에 있어 제거될 노이즈에 매우 효과적으로 판명되어질 다중해상도 NLM 필터는 새로운 디노이징 영상 프레임워크를 만들기 위해 웨이브렛 임계와 결합되어진다. 실험은 알고리듬이 영상 질적 통계에 의해 효과적으로영상 노이즈를 줄일 수 있는 것으로 나타난다. We propose a new method for the reduction of noise present in the magnetic resonance (MR) images. Magnetic resonance imaging (MRI) is corrupted by Rician noise, which is image dependent and computed from both real and imaginary images. Rician noise makes image-based quantitative measurement difficult. The non-local means (NLM) filter has been proven to be effective against additive noise. Similarly, Wavelet transform (WT) based denoising produces a better noise estimation. The proposed algorithm performs denoising in three functional steps. First, the noisy image is decomposed into multiple subbands by using the wavelet transform. NLM filter is applied to the approximation (low-frequency) subbands of a signal decomposed using a wavelet filter bank. The multiresolution NLM filter is combined with wavelet thresholding to form a new image denoising framework, which turns out to be very effective in eliminating noise in real noisy images. Experiments show that the algorithm can reduce image noise effectively in terms of image quality metrics.
Multiresolution Non-Local Means Filtering for Image Denoising of MRI
라메쉬 쿠마 라마,권구락 한국차세대컴퓨팅학회 2015 한국차세대컴퓨팅학회 논문지 Vol.11 No.5
We propose a new method for the reduction of noise present in the magnetic resonance (MR) images. Magnetic resonance imaging (MRI) is corrupted by Rician noise, which is image dependent and computed from both real and imaginary images. Rician noise makes image-based quantitative measurement difficult. The non-local means (NLM) filter has been proven to be effective against additive noise. Similarly, Wavelet transform (WT) based denoising produces a better noise estimation. The proposed algorithm performs denoising in three functional steps. First, the noisy image is decomposed into multiple subbands by using the wavelet transform. NLM filter is applied to the approximation (low-frequency) subbands of a signal decomposed using a wavelet filter bank. The multiresolution NLM filter is combined with wavelet thresholding to form a new image denoising framework, which turns out to be very effective in eliminating noise in real noisy images. Experiments show that the algorithm can reduce image noise effectively in terms of image quality metrics.
Loss of MeCP2 causes subtle alteration in dendritic arborization of retinal ganglion cells
이우제,라메쉬 마리압판,Koushitak De,온탁범 한국통합생물학회 2021 Animal cells and systems Vol.25 No.2
Methyl-CpG-binding protein (MeCP2) is highly expressed in neurons. It plays an important role in the development of synapses and the formation of circuits in the central nervous system (CNS). Mutations in MECP2 cause neurodevelopmental disorders and mental retardation in humans. Therefore, it has become important to determine the distribution and function of MeCP2 in vivo. The retina consists of three nuclear cell layers and two layers of synapses; neurons in each layer are connected to form fine circuits necessary for visual signal transduction. Using immunohistochemical analysis, we found that MeCP2 was expressed in all nuclear cell layers, with differences in the levels of MeCP2 expression observed among the layers. To understand the structural defects in the retina due to the loss of MeCP2, we sought to elucidate the organization of the retinal structure in the Mecp2 knockout (KO) mouse. Overall, we found a normal retinal structure in Mecp2 KO mice. However, because Mecp2 mutations have a highly variable effect on neuronal architecture, we analyzed morphological changes in a subset of retinal ganglion cells of Mecp2 KO mice. In Thy1-GFP mice crossed with Mecp2 mutant mice, Sholl intersections analyses showed a subtle increase in number of intersections due to increased branching proximal to the soma in Mecp2 KO mice. Our results demonstrate that the expression of MeCP2 and the effects of Mecp2 mutations are highly specific to tissue and cell types.