• 통합자연과학논문집
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• 제7권2호
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• pp.79-86
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• 2014

Amyloid oligomers are believed to play important causal roles in many types of amyloid-related degenerative diseases. Many different laboratories have reported amyloid oligomers that differ in size, morphology, toxicity, and method of preparation or purification, raising the question of the structural relationships among these oligomer preparations. The structural plasticity that has been reported to occur in amyloid formed from the same protein sequence indicates that it is quite possible that different oligomer preparations may represent distinct structural variants. In view of the difficulty in determining the precise structure of amyloids, conformation- and epitope-specific antibodies may provide a facile means of classifying amyloid oligomer structures. Conformation-dependent antibodies that recognize generic epitopes that are specifically associated with distinct aggregation states of many different amyloid-forming sequences indicate that there are at least two fundamentally distinct types of amyloid oligomers: fibrillar and prefibrillar oligomers. Classification of amyloid oligomers according to their underlying structures may be a more useful and rational approach than relying on differences in size and morphology.

• 펄프종이기술
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• 제45권6호
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• pp.88-95
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• 2013

Effects of beating and water immersion time on fiber swelling and paper properties were elucidated for the fundamental study of producing high bulk paper. Chemical pulps were beaten for various freeness and the beaten pulp was immersed in water up to 24 hours. Fiber swelling was evaluated by measuring water retention value (WRV). It was found that fiber swelling, bulk and paper strength were quickly changed at the initial stage of beating. Immersion in water did not significantly increase WRV, paper density and strength, implying that soaking in water alone could not effectively swell fiber wall. In order to swell further, hydrogen bonds between fibrils in fiber wall and hence fiber wall structure shall be broken by mechanical force during beating.

• 펄프종이기술
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• 제30권3호
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• pp.7-14
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• 1998

It is well known that the recycling of pulp generates a lot of fines, and cause the hornification of fiber. Both phenomena have been contributed to a limited use of recycled fiber. Among several means which can improve the properties of recycled fiber, enzymatic treatments are considered as an effective means. Thus the effects of xylanase on the properties of recycled pulp were investigated in this study Xylanase treatment showed some refining effect at a small dosage while the fines and fibrils were reduced at higher dosage as shown in the treatment with cellulase-hemicellulase. The interesting finding is that the WRV of recycled fiber treated with xylanase was higher than that treated with the mixture of cellulase and hemicellulase. Breaking length and tear index of recycled fiber treated with xylanase were also higher.

• International Journal of Industrial Entomology and Biomaterials
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• 제44권2호
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• pp.29-36
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• 2022

Over the past decades, silk sericin (SS) received increasing attention in the academic and industrial fields. In nature, SS acts as a glue that holds the two strands of silk fibrils together. However, recent works suggest that SS might have a more diverse role during the silk spinning process, such as stabilizing the SF in the silk gland. On the other hand, the sericulture industry has been trying to find novel applications for SS discarded from the silk fabric manufacturing process. Recovery and refining of SS would be the first step of the recycling of SS. Using a proper solvent SS could be shaped into various forms, such as spherical beads, microparticles, fibers, and films. Moreover, the applicability of these SS materials has been investigated in various fields such as cosmetics, templates for nanomaterials, drug delivery, heavy metal adsorption, and enzyme immobilization.

• 한국자기공명학회논문지
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• 제26권1호
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• pp.17-20
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• 2022

High-pressure (HP) NMR is a versatile tool to investigate diverse features of proteins. This technique has been particularly powerful to elucidate structural dynamics that only populates sufficiently in a pressurized condition. Amyloidogenic proteins, which are prone to aggregate and form amyloid fibrils, often maintains highly dynamic states in its native or aggregation-prone states, and HP NMR contributed much to advance our understandings of the dynamic behaviors of amyloidogenic proteins and the molecular mechanisms of their aggregation. In this mini review, we therefore summarize recent HP NMR studies on amyloid-beta (Aβ), the representative amyloidogenic intrinsically disordered protein (IDP).

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권1호
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• pp.24-39
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• 2000

Various methods and graft materials have been used to fill in the defect adjacent to the implants and considered as clinically acceptable. But it is not clear whether the regenerated bone increases the implant-bone contact and supports the implant. The purpose of this study is to evaluate regenerated bone surrounding implants using bone morphogenetic protein(BMP) and demineralized freeze-dried bone(DFDB), and the interfaces between implants and regenerated bone. bBMP was extracted and partially purified from the bovine bone matrix using heparine chromatography. Demineralized freeze-dried bone was made from the dog. Inactive insoluble collagenous bone matrix(IBM) of dog was used as carrier of bBMP. Interfaces of titanium coated epoxy resin implants were processed for demineralized section for transmission electron microscopy(TEM) and those of screw type implants were for nondemineralized section for light and fluoromicroscopic examination. Implants were inserted in the inferior border of mandible of adult dogs and artificial bony defects($3{\times}3{\times}4mm$) were made at the mesial and distal side of implants. Defects were filled with BMP(BMP group) and DFDB(DFDB group). For the fluoromicroscopic examination, the fluorescent dyes(oxytetracycline, calcein green, alizarin red) were injected 2, 4, 6, 8, 12 weeks after implantation. The experimental animals were sacrificed at the 6th and the 12th week and their mandible were extirpated and processed for examination with light microscopy, fluoromicroscopy and TEM. The obtained results were as follows : 1. By the light microscopic findings, the defects were filled with woven bone at the 6th week and compact bone at the 12th week, and the osseointegrations were seen in both groups. There was no histological difference between them. 2. On the basis of the histomorphometric analysis, BMP group(6th week: 40.25%, 12th week: 56.04%) had higher bony contact ratio than DFDB group(38.37%, 42.63%). There was significant difference between two groups at the 12th week(p<0.05). 3. The amount of bone formation in BMP group was more prominent than in DFDB group. Significant difference was noted among two groups at the 6th and the 8th week(p<0.05). 4. By the transmission electron microscopic findings, $0.4-2{\mu}m$ soft tissue layer was found in adjacent to the interfaces and over the collagen fibrils of bone at the 6th week. However, about 100nm amorphous layer was noted at the interface or collagen fibrils directly extended to the titanium surface at the 12th week. There was no significant difference between two groups. 5. These results suggest that BMP and DFDB can be used as good graft materials in the regeneration of bone adjacent to implant, and BMP is more valuable as a bone inducer than DFDB.

• 천문학회보
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• 제37권2호
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• pp.113.1-113.1
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• 2012

The characteristics of Doppler shifts in a quiet region of the Sun are investigated by comparing between the $H{\alpha}$ line and the Caii infrared line at 854.2 nm. A small area of $16^{\prime\prime}{\times}40^{\prime\prime}$ was observed for about half an hour with the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New Solar Telescope (NST) at Big Bear Solar Observatory. The observed area contains a network region and an internetwork region, and identified in the network region are $H{\alpha}$ fibrils, Caii fibrils and bright points. We infer the Doppler velocity from each line profile at a point with the lambdameter method as a function of half wavelength separation ${\Delta}{\lambda}$. It is confirmed that the bisector of the spatially-averaged Caii line profile has an inverse C-shape of with a significant peak redshift of +1.8 km/s. In contrast, the bisector of the spatially-averaged $H{\alpha}$ line profile has a different shape; it is almost vertically straight or, if not, has a C-shape with a small peak blueshift of -0.5 km/s. In both the lines, the bisectors of bright network points are much different from those of other features in that they are significantly redshifted not only at the line centers, but also at the wings. We also find that the spatio-temporal fluctuation of Doppler shift inferred from the Caii line is correlated with those of the $H{\alpha}$ line. The strongest correlation occurs in the internework region, and when the inner wings rather than the line centers are used to determine Doppler shift. In this region, the RMS value of Doppler shift fluctuation is the largest at the line center, and monotonically decreases with ${\Delta}{\lambda}$. We discuss the physical implications of our results on the formation of the $H{\alpha}$ line and Caii 854.2 nm line in the quiet region chromosphere.

• Molecules and Cells
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• 제42권6호
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• pp.480-494
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• 2019

Aggregates of disease-causing proteins dysregulate cellular functions, thereby causing neuronal cell loss in diverse neurodegenerative diseases. Although many in vitro or in vivo studies of protein aggregate inhibitors have been performed, a therapeutic strategy to control aggregate toxicity has not been earnestly pursued, partly due to the limitations of available aggregate models. In this study, we established a tetracycline (Tet)-inducible nuclear aggregate (${\beta}23$) expression model to screen potential lead compounds inhibiting ${\beta}23$-induced toxicity. High-throughput screening identified several natural compounds as nuclear ${\beta}23$ inhibitors, including peucedanocoumarin III (PCIII). Interestingly, PCIII accelerates disaggregation and proteasomal clearance of both nuclear and cytosolic ${\beta}23$ aggregates and protects SH-SY5Y cells from toxicity induced by ${\beta}23$ expression. Of translational relevance, PCIII disassembled fibrils and enhanced clearance of cytosolic and nuclear protein aggregates in cellular models of huntingtin and ${\alpha}$-synuclein aggregation. Moreover, cellular toxicity was diminished with PCIII treatment for polyglutamine (PolyQ)-huntingtin expression and ${\alpha}$-synuclein expression in conjunction with 6-hydroxydopamine (6-OHDA) treatment. Importantly, PCIII not only inhibited ${\alpha}$-synuclein aggregation but also disaggregated preformed ${\alpha}$-synuclein fibrils in vitro. Taken together, our results suggest that a Tet-Off ${\beta}23$ cell model could serve as a robust platform for screening effective lead compounds inhibiting nuclear or cytosolic protein aggregates. Brain-permeable PCIII or its derivatives could be beneficial for eliminating established protein aggregates.

• Macromolecular Research
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• 제9권4호
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• pp.238-246
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• 2001

Properties of ternary blends of nylon 6 (Ny6), a thermotropic liquid crystalline polymer (TLCP, poly(ester amide), 20 wt%) and a maleic anhydride grafted polypropylene (2 wt%) (MAPP) were studied under various processing conditions. TLCP was pre-blended with MAPP first and then the binary one blended again with Ny6. The processing temperature of the second mixing was varied. Thermal properties show the partial miscibility of the ternary blend. The morphology of the TLCP phase in the first blending shows mostly in the fibril bundle shape, but varies between droplets and oriented fibrils after the second processing. Some of TLCP phase lost the fibril morphology during the second processing stage. The morphology variation invokes the change in tensile properties. Low extrusion temperature (270$\^{C}$) provides more fibril shapes, which are associated with less deformation in the second stage. The processing temperature effect was more evident when the draw ratio was high. High drawing was applicable due to the stabilizing action of tile compatibilizer.

• BMB Reports
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• 제42권9호
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• pp.541-551
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• 2009

Amyloidogenesis defines a condition in which a soluble and innocuous protein turns to insoluble protein aggregates known as amyloid fibrils. This protein suprastructure derived via chemically specific molecular self-assembly process has been commonly observed in various neurodegenerative disorders such as Alzheimer's, Parkinson's, and Prion diseases. Although the major culprit for the cellular degeneration in the diseases remains unsettled, amyloidogenesis is considered to be etiologically involved. Recent recognition of fibrillar polymorphism observed mostly from in vitro amyloidogeneses may indicate that multiple mechanisms for the amyloid fibril formation would be operated. Nucleation-dependent fibrillation is the prevalent model for assessing the self-assembly process. Following thermodynamically unfavorable seed formation, monomeric polypeptides bind to the seeds by exerting structural adjustments to the template, which leads to accelerated amyloid fibril formation. In this review, we propose another in vitro model of amyloidogenesis named double-concerted fibrillation. Here, two consecutive assembly processes of monomers and subsequent oligomeric species are responsible for the amyloid fibril formation of $\alpha$-synuclein, a pathological component of Parkinson's disease, following structural rearrangement within the oligomers which then act as a growing unit for the fibrillation.