Atomic-scale dents on cellulose nanofibers: the origin of diverse defects in sustainable fibrillar materials

セルロースナノファイバーに生じた原子レベルの欠陥構造を発見 --理想的なバイオポリマー材料の生産にむけて--. 京都大学プレスリリース. 2022-10-07.Atomic-scale dent structures on the surfaces of cellulose nanofibers were detected. These dent parts constituted at least 30–40% of the total length of the dispersed nanofibers, and deep dents induced the kinking and fragmentation of nanofibers

セルロースナノフィブリル表面改質による新規バイオ系高分子ナノ複合体の調製

学位の種別:課程博士University of Tokyo(東京大学

Telmisartan improves nonalcoholic steatohepatitis in medaka (Oryzias latipes) by reducing macrophage infiltration and fat accumulation

We investigated the efficacy of the antihypertensive drug telmisartan (Tel) and the mechanisms underlying the progression from simple steatosis to nonalcoholic steatohepatitis (NASH) in a medaka (Oryzias latipes) NASH model. We used the NASH activity score (NAS) developed in humans to assess the histology of the medaka NASH model and found that NAS increased with time. Further, TUNEL-positive apoptosis hepatocytes were found in the medaka NASH model. Tel administration resulted in the increased expression of liver peroxisome proliferator-activated receptor-γ, carnitine palmitoyltransferase 1 and acyl-CoA oxidase 1 and decreased the number of 8-hydroxydeoxyguanosine-positive hepatocytes and the migration of macrophages positive for diastase-periodic-acid-Schiff. Medaka NAS was improved by Tel administration but fatty acid content was not affected. Tel reduced the infiltration of macrophages into the liver and ameliorated NASH pathology

Cross-polarization dynamics and conformational study of variously sized cellulose crystallites using solid-state 13C NMR

Cellulose forms crystalline fibrils, via biosynthesis, that can be just a few nanometers wide. The crystallinity is a structural factor related to material performance. Recently, many routes to isolate these fibrils as nanocellulose have been developed, and there exist various types of nanocellulose with different crystallinities. Quantitative assessment of the crystallinity of nanocellulose is thus essential to advance knowledge in the high performance and functionality of such materials. Solid-state 13C cross-polarization/magic-angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy is a strong tool to investigate the structural features and dynamics of solid cellulose. The crystallinity is often evaluated by using the NMR signal ratio of the C4 crystalline and noncrystalline regions as a crystallinity index (CI) value. To calculate the CI value, it is necessary to examine the dependence of the contact time (CT) for CP on the signal intensity and set the optimum CT at a maximum of the signal intensity. However, the dependence has not been investigated for evaluation of the CI value of various cellulose samples with different crystal sizes. Here, we optimized the CT for evaluation of the CI value of cellulose with different crystal sizes. The error in the CI at the optimized CT was ~ 3%. At the optimized CT, the structural change after surface modification by TEMPO-oxidation was also analyzed from the NMR spectra of the C6 region. The relationship between the CI value and the degree of oxidation shows that it is possible to evaluate the degree of oxidation from the NMR spectra irrespective of the crystallinity of cellulose. Furthermore, the C4-based CI value was linearly correlated with the C6-based trans-gauche (tg) ratio, which is approximated by a function, CI = 0.9 tg ratio

Modulation of anti-cancer drug sensitivity through the regulation of mitochondrial activity by adenylate kinase 4

Background: Adenylate kinase is a key enzyme in the high-energy phosphoryl transfer reaction in living cells. An isoform of this enzyme, adenylate kinase 4 (AK4), is localized in the mitochondrial matrix and is believed to be involved in stress, drug resistance, malignant transformation in cancer, and ATP regulation. However, the molecular basis for the AK4 functions remained to be determined. Methods: HeLa cells were transiently transfected with an AK4 small interfering RNA (siRNA), an AK4 short hairpin RNA (shRNA) plasmid, a control shRNA plasmid, an AK4 expression vector, and a control expression vector to examine the effect of the AK4 expression on cell proliferation, sensitivity to anti-cancer drug, metabolome, gene expression, and mitochondrial activity. Results: AK4 knockdown cells treated with short hairpin RNA increased ATP production and showed greater sensitivity to hypoxia and anti-cancer drug, cis-diamminedichloro-platinum (II) (CDDP). Subcutaneous grafting AK4 knockdown cells into nude mice revealed that the grafted cells exhibited both slower proliferation and reduced the tumor sizes in response to CDDP. AK4 knockdown cell showed a increased oxygen consumption rate with FCCP treatment, while AK4 overexpression lowered it. Metabolome analysis showed the increased levels of the tricarboxylic acid cycle intermediates, fumarate and malate in AK4 knockdown cells, while AK4 overexpression lowered them. Electron microscopy detected the increased mitochondrial numbers in AK4 knockdown cells. Microarray analysis detected the increased gene expression of two key enzymes in TCA cycle, succinate dehydrogenase A (SDHA) and oxoglutarate dehydrogenease L (OGDHL), which are components of SDH complex and OGDH complex, supporting the metabolomic results. Conclusions: We found that AK4 was involved in hypoxia tolerance, resistance to anti-tumor drug, and the regulation of mitochondrial activity. These findings provide a new potential target for efficient anticancer therapies by controlling AK4 expression

Nanocellulose Xerogels With High Porosities and Large Specific Surface Areas

Xerogels are defined as porous structures that are obtained by evaporative drying of wet gels. One challenge is producing xerogels with high porosity and large specific surface areas, which are structurally comparable to supercritical-dried aerogels. Herein, we report on cellulose xerogels with a truly aerogel-like porous structure. These xerogels have a monolithic form with porosities and specific surface areas in the ranges of 71–76% and 340–411 m2/g, respectively. Our strategy is based on combining three concepts: (1) the use of a very fine type of cellulose nanofibers (CNFs) with a width of ~3 nm as the skeletal component of the xerogel; (2) increasing the stiffness of wet CNF gels by reinforcing the inter-CNF interactions to sustain their dry shrinkage; and (3) solvent-exchange of wet gels with low-polarity solvents, such as hexane and pentane, to reduce the capillary force on drying. The synergistic effects of combining these approaches lead to improvements in the porous structure in the CNF xerogels

セツジョ カラ インプラント オ イジゲン トシタ エピテーゼ マデ イッカン チリョウ オ オコナッタ ジョウガクドウ アクセイ センイセイ ソシキ キュウシュ ノ 1レイ

A case of malignant fibrous histiocytoma (MFH) arising primarily in the left maxilla is reported. The patient, a 50-year-old man, presented with diffuse swelling of the upper left side of the gingiva. Radiographic findings revealed wide destruction of the left maxilla. Initial biopsy revealed a fibrosarcoma. The patient received continuous arterial infusion of 5-FU and external irradiation with 60Co-40Gy preoperatively. After a combination of chemotherapy and radiotherapy, he received total resection of the left maxilla with orbital exenteration. Histopathologically, the tumor was diagnosed as a storiform-pleomorphic type of MFH. After operation, general chemotherapy with CDDP and external irradiation with 60Co-30Gy were performed. Two years after removal of the tumor, three fixtures were placed into the bony orbital rim to fit an orbital prothesis. There is no clinical evidence of recurrence as of 9.5 years after extirpation of the tumor and the implants are functioning well

Multi-Wavelength Photometric and Polarimetric Observations of the Outburst of 3C 454.3 in Dec. 2009

In December 2009, the bright blazar, 3C 454.3 exhibited a strong outburst in the optical, X-ray and gamma-ray regions. We performed photometric and polarimetric monitoring of this outburst in the optical and near-infrared bands with TRISPEC and HOWPol attached to the Kanata telescope. We also observed this outburst in the infrared band with AKARI, and the radio band with the 32-m radio telescope of Yamaguchi University. The object was in an active state from JD 2455055 to 2455159. It was 1.3 mag brighter than its quiescent state before JD 2455055 in the optical band. After the end of the active state in JD 2455159, a prominent outburst was observed in all wavelengths. The outburst continued for two months. Our optical and nearinfrared polarimetric observations revealed that the position angle of the polarization (PA) apparently rotated clockwise by 240 degrees within 11 d in the active state (JD 2455063-2455074), and after this rotation, PA remained almost constant during our monitoring. In the outburst state, PA smoothly rotated counterclockwise by 350 degrees within 35 d (JD 2455157-2455192). Thus, we detected two distinct rotation events of polarization vector in opposite directions. We discuss these two events compared with the past rotation events observed in 2005, 2007 and 2008.Comment: 9 pages, 6 figures, accepted for publication in PAS