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228 results on '"Kokubun T"'

1. A Plant-Derived Antioxidant Supplement Prevents the Loss of Retinal Ganglion Cells in the Retinas of NMDA-Injured Mice

Author

Maekawa S, Sato K, Kokubun T, Himori N, Yabana T, Ohno-Oishi M, Shi G, Omodaka K, and Nakazawa T

Subjects
plant-derived antioxidant compounds, oxidative stress, retinal ganglion cells, glaucoma, Ophthalmology, RE1-994
Abstract

Shigeto Maekawa,1 Kota Sato,1,2 Taiki Kokubun,1 Noriko Himori,1,3 Takeshi Yabana,1 Michiko Ohno-Oishi,1 Ge Shi,1 Kazuko Omodaka,1,4 Toru Nakazawa1,2,4– 6 1Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan; 2Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan; 3Department of Aging Vision Healthcare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Miyagi, Japan; 4Department of Ophthalmic Imaging and Information Analytics, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan; 5Collaborative Program for Ophthalmic Drug Discovery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan; 6Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Miyagi, JapanCorrespondence: Toru Nakazawa, Department of Ophthalmology, Tohoku University Graduate School of Medicine, 1-1 Seiryo, Aoba, Sendai, Miyagi, 980-8574, Japan, Tel +81-22-717-7294, Fax +81-22-717-7298, Email ntoru@oph.med.tohoku.ac.jpPurpose: To investigate the effect of plant-derived antioxidant compounds, identified with primary culture screening, on retinal ganglion cell (RGC) survival in mice under excitotoxic conditions. Additionally, to determine the effect of these compounds on the involvement of calpain inactivation.Materials and Methods: Plant-derived antioxidant compounds including hesperidin, crocetin, and Tamarindus indica were administrated orally to C57BL/6J mice. The levels of lipid oxidation and calpain activation were assessed with a TBARS assay and western blotting. RGC survival was evaluated with a TUNEL assay and RBPMS immunostaining after intravitreal injection of NMDA.Results: Plant-derived antioxidant compounds significantly ameliorated the increase in the level of MDA in the retinas after NMDA injury. Cleaved α-fodrin fragments were detected in the NMDA-injured retinas, and these fragments were significantly lower in mice that received the plant-derived antioxidant compounds. The plant-derived antioxidants also ameliorated increases in TUNEL-positive cells and RGC death after NMDA injection.Conclusion: These results indicate that oral administration of plant-derived antioxidant compounds such as hesperidin, crocetin, and Tamarindus indica suppressed RGC death. This oral supplementation decreased lipid oxidation and excessive calpain activation in NMDA-injured retinas. Thus, our newly developed antioxidant supplement has a potential role in neuroprotective treatment for retinal diseases, such as glaucoma.Keywords: plant-derived antioxidant compounds, oxidative stress, retinal ganglion cells, glaucoma

Published
2022

13. Skill-level based examination of forearm muscle activation associated with efficient wrist and finger movements during typing

Author

Akira Kobayashi, Kanemura N, Kokubun T, Ito T, Y. Matsumoto, Yoshida M, and Funakoshi H

Subjects
medicine.medical_specialty, medicine.diagnostic_test, business.industry, Index finger, Electromyography, Kinematics, Wrist, Motion capture, body regions, medicine.anatomical_structure, Physical medicine and rehabilitation, Forearm, medicine, Finger joint, Typing, business
Abstract

Background Musculoskeletal disorders caused by computer use are associated with socio-economic problems. Reducing the biomechanical loading caused by hand movements could reduce the occurrence of such disorders. However, most participants recruited for past experimental studies had a certain level of typing skill, and differences in the biomechanical loading of those with different typing skills have not been examined. This study aimed to quantify the relationship between the movements of the wrist and finger joints and the loading on the forearm muscles and to clarify the differences between typists of different skill levels. Methods A 3D motion capture system measured wrist and index finger joint movements, and surface electromyography measured muscle activities for the right hand during a typing task. We compared wrist and finger joint movements and forearm muscle loading during typing, keystroke time, and key release time between skilled and unskilled typists. Findings Skilled typists move their wrists and fingers faster with less muscle activity during typing, the active tension of their finger flexor muscles during keystrokes are high, and they have higher mechanical stresses on the finger flexor tendons during keystrokes. Unskilled typists develop strategies to prevent excessive stiffness in their wrist joints when making keystrokes. They are expected to have a higher cumulative loading on the extensor muscles of the wrist during key release. Interpretation Biomechanical loading in typing skill is different, which may make it possible to predict disability. This could provide information on the changes in physical parameters and environments to prevent disability.

Published
2021

33. Quantifying the metabolic cost to an Antarctic liverwort of responding to an abrupt increase in UVB radiation exposure

Author

Snell, Katherine R.S., Kokubun, T., Griffiths, H., Convey, Peter, Hodgson, Dominic, Newsham, Kevin K., Snell, Katherine R.S., Kokubun, T., Griffiths, H., Convey, Peter, Hodgson, Dominic, and Newsham, Kevin K.

Abstract

We quantified the metabolic cost to the Antarctic leafy liverwort Cephaloziella varians of responding to an abrupt increase in ultraviolet B (UVB) radiation exposure in the natural environment at Rothera Point on the western Antarctic Peninsula (67 degrees 34'S, 68 degrees 07'W). The liverwort was protected from exposure to UVB radiation for 44 days with screens containing Mylar polyester, after which time its thalli, which are normally black in colour, had become green owing to reduced concentrations of an anthocyanidin, identified here as riccionidin A, in thallus tips. Thalli were then exposed to an abrupt increase in UVB radiation by removing the screens. The thalli became visibly darker within 48 h of the screens being removed, resynthesizing riccionidin A to the same concentration as that present in thalli outside screens during this period. Chlorophyll fluorescence measurements indicated that nonphotochemical quenching was higher in the thalli formerly under the screens than in those not previously covered with screens, but that F-v/F-m and photochemical quenching were the same in the two groups of thalli. We used data from aqueous phase oxygen electrode measurements to calculate an estimate for carbon fixation by C. varians during the 48 h after the screens were removed. Assuming a photosynthetic quotient for Antarctic bryophytes of 1, these analyses indicated that the minimum weight of carbon used to synthesize riccionidin A was equivalent to 1.85% of the carbon fixed by thalli during the 48 h after the abrupt increase in UVB radiation exposure.

Published
2009

34. Taxonomy of Calicium victorianum (F. Wilson) Tibell (Caliciaceae, Lecanorales), a lichenized ascomycete new to Europe

Author

Aguirre-Hudson, B., Kokubun, T., Spooner, B., Tibell, Leif, Aguirre-Hudson, B., Kokubun, T., Spooner, B., and Tibell, Leif

Abstract

The morphological features and chemical compounds found in the first European collection of Calicium victorianum are compared with type material from Australia of C. piperatum F. Wilson. The phylogenetic relationships of the species are discussed by comparing its nuclear rDNA ITS 1-5.8S-ITS2 with that of other species of Calicium.

Published
2007
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