224 results on '"Kentaro Kawai"'
Search Results
2. Relationship between binocular vision and Govetto’s stage in monocular idiopathic epiretinal membrane
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Kanae Tsuda, Manabu Miyata, Kentaro Kawai, Shinya Nakao, Akinari Yamamoto, Kenji Suda, Eri Nakano, Miho Tagawa, Yuki Muraoka, Ryo Sakata, and Akitaka Tsujikawa
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Binocular vision ,Epiretinal membrane ,Govetto’s stage ,Foveal avascular zone ,Medicine ,Science - Abstract
Abstract Govetto’s staging system (stages 1–4) for epiretinal membrane (ERM) based on optical coherence tomography images is a useful predictor of monocular visual function; however, an association between Govetto’s stage and binocular vision has not been reported. This study aimed to investigate the factors associated with Govetto’s stage among the monocular and binocular parameters. This retrospective study included consecutive patients with treatment-naïve eyes with unilateral ERM without pseudo-hole. We investigated Govetto’s stage, degrees of aniseikonia and metamorphopsia, foveal avascular zone area, central retinal and choroidal thickness, vertical ocular deviation, stereopsis, and binocular single vision (BSV). We compared the parameters between the BSV-present and BSV-absent groups and investigated correlations between Govetto’s stage and the monocular and binocular parameters. Twenty-eight eyes of 28 patients were examined (age, 66.6 ± 10.2 years). In multivariate correlation analyses, Govetto’s stage correlated with BSV (P = 0.04, β = − 0.36) and central retinal thickness (P
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- 2024
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3. Rhodium-catalyzed homo-coupling reaction of aryl Grignard reagents and its application for the synthesis of an integrin inhibitor
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Kazuyuki Sato, Satoki Teranishi, Atsushi Sakaue, Yukiko Karuo, Atsushi Tarui, Kentaro Kawai, Hiroyuki Takeda, Tatsuo Kinashi, and Masaaki Omote
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biphenyltetracarboxylic acid ,homo-coupling ,integrin inhibitor ,rhodium catalyst ,ullmann-type reaction ,Science ,Organic chemistry ,QD241-441 - Abstract
A novel Rh-catalyzed one-pot homo-coupling reaction of aryl Grignard reagents was achieved. The reaction with bromobenzenes having an electron-donating group or a halogen substituent gave the corresponding homo-coupling products in good yields, although the reaction using heterocyclic or aliphatic bromides scarcely proceeded. A Rh(III)–bis(aryl) complex, which might be formed from RhCl(PPh3)3 and the aryl Grignard reagents, plays an important role in giving the homo-coupling products in this reaction. Furthermore, we applied the reaction to the synthesis of a novel inhibitor for integrins which is critical for several diseases.
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- 2024
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4. Decarboxylative Aldol Reaction of α,α-Difluoro-β-keto Esters: Easy Access to Difluoroenolate
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Atsushi Tarui, Hiroshi Shimomura, Yohei Yasuno, Yukiko Karuo, Kazuyuki Sato, Kentaro Kawai, and Masaaki Omote
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Chemistry ,QD1-999 - Published
- 2024
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5. Quantification of dilated deep capillaries in diabetic retinopathy on optical coherence tomography angiography
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Noriko Terada, Tomoaki Murakami, Kenji Ishihara, Keiichi Nishikawa, Kentaro Kawai, and Akitaka Tsujikawa
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Medicine ,Science - Abstract
Abstract Morphological changes in capillaries are one of major clinical signs in diabetic retinopathy (DR). In this study, we quantified the dilated deep capillaries on optical coherence tomography angiography (OCTA) images. Central 3 × 3 mm en face images were obtained using a swept source OCTA device in 105 eyes of 99 patients with DR. Capillaries with a greater diameter in the deep layers were defined as the dilated deep capillaries, using stepwise image processing. The relative areas of automatically selected capillaries with a great diameter were calculated as the index of the dilated deep capillaries. Most eyes with DR had string-like or dot-like dilated deep capillaries in the OCTA images, which appeared to be dilated capillary segments or microaneurysms histologically. They were distributed more densely in the parafovea than in the central sector, while there were no differences between individual quadrants. The index of the dilated deep capillaries was higher in eyes with DR than in nondiabetic eyes. The index in the central subfield was modestly associated with visual acuity, diabetic macular edema, and proliferative diabetic retinopathy. The quantitative dilated deep capillaries are designated as a biomarker of vision-threatening DR.
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- 2023
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6. Quatrefoil light traps for free-swimming stages of cymothoid parasitic isopods and seasonal variation in their species compositions in the Seto Inland Sea, Japan
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Hiroki Fujita, Kentaro Kawai, Diego Deville, and Tetsuya Umino
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16S rRNA ,COI ,DNA barcoding ,Fish parasite ,Life cycle ,Manca ,Zoology ,QL1-991 - Abstract
Cymothoid parasitic isopods infest a wide range of fish of different taxa living in marine, brackish, and freshwater environments. Most research on the reproductive season of Cymothoidae has been done by collecting or monitoring host fish afflicted with cymothoid parasites. However, collecting ecological data on cymothoid species that infest non-commercial or endangered fishes is complex and challenging. We used a quatrefoil light trap to investigate the seasonal change in species composition of cymothoid free-swimming stages in the Seto Inland Sea, Japan. We also collected preliminary data for efficient light-trap sampling and showed its effectiveness in cymothoid-related research. From October 2020 to December 2021, 613 cymothoid free-swimming stages were sampled monthly. All obtained individuals were identified as Mothocya parvostis (596), Ceratothoa verrucosa (12), and Ceratothoa carinata (5) by DNA barcoding using cytochrome c oxidase subunit I and 16S rRNA gene sequences. Based on the number of M. parvostis mancae collected each month, M. parvostis was anticipated to reproduce from June to December, with two reproduction peaks each year, and C. verrucosa and C. carinata were expected to reproduce in June, July, and September, and September and October, respectively. In addition, free-swimming juveniles were captured, presumably after they had left their optional intermediate hosts. Furthermore, the most effective time to harvest cymothoids with light traps may be during high tide on the night of the new moon. This study serves as a methodological framework for future research on cymothoids using light traps.
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- 2023
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7. Genetic divergences and hybridization within the Sebastes inermis complex
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Diego Deville, Kentaro Kawai, Hiroki Fujita, and Tetsuya Umino
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Hybridization ,Sebastes ,Divergent selection ,Clustering analysis ,Rhodopsin gene ,Microsatellite loci ,Medicine ,Biology (General) ,QH301-705.5 - Abstract
The Sebastes inermis complex includes three sympatric species (Sebastes cheni, viz Sebastes inermis, and Sebastes ventricosus) with clear ecomorphological differences, albeit incomplete reproductive isolation. The presence of putative morphological hybrids (PMH) with plausibly higher fitness than the parent species indicates the need to confirm whether hybridization occurs within the complex. In this sense, we assessed the dynamics of genetic divergence and hybridization within the species complex using a panel of 10 microsatellite loci, and sequences of the mitochondrial control region (D-loop) and the intron-free rhodopsin (RH1) gene. The analyses revealed the presence of three distinct genetic clusters, large genetic distances using D-loop sequences, and distinctive mutations within the RH1 gene. These results are consistent with the descriptions of the three species. Two microsatellite loci had signatures of divergent selection, indicating that they are linked to genomic regions that are crucial for speciation. Furthermore, nonsynonymous mutations within the RH1 gene detected in S. cheni and “Kumano” (a PMH) suggest dissimilar adaptations related to visual perception in dim-light environments. The presence of individuals with admixed ancestry between two species confirmed hybridization. The presence of nonsynonymous mutations within the RH1 gene and the admixed ancestry of the “Kumano” morphotype highlight the potential role of hybridization in generating novelties within the species complex. We discuss possible outcomes of hybridization within the species complex, considering hybrid fitness and assortative mating. Overall, our findings indicate that the genetic divergence of each species is maintained in the presence of hybridization, as expected in a scenario of speciation-with-gene-flow.
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- 2023
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8. Pigmentary lesions in eyes with rhegmatogenous retinal detachment with flap tears: a retrospective observational study
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Midori Ideyama, Yuki Muraoka, Kentaro Kawai, Masaharu Ishikura, Shin Kadomoto, Naomi Nishigori, Takanori Kameda, Kenji Ishihara, Manabu Miyata, Masahiro Miyake, Tomoaki Murakami, Sotaro Ooto, and Akitaka Tsujikawa
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Medicine ,Science - Abstract
Abstract We included 97 patients with unilateral rhegmatogenous retinal detachment (RRD) with posterior vitreous detachment who underwent vitrectomy, and examined pigmentary lesion (PL) characteristics around the sites of original tears using pre- and postoperative ultra-widefield scanning light ophthalmoscopy, green light fundus autofluorescence (FAF) imaging, and intraoperative digital video. If PL did not involve RRD, we used OCT to preoperatively assess any pathologic changes to the lesion. A total of 116 retinal tears (mean count, 1.2 ± 0.5; range, 1–4 per eye) were observed in the detached retina. Overall, 102 (88%), 63 (54%), 14 (12%), and 25 (22%) tears were accompanied by lattice degeneration (LD) or PL, both LD and PL, only LD, and only PL, respectively. In green FAF images, LD showed normal to mild-hyper fluorescence, whereas all PL showed hypofluorescence. On OCT, PL were located at the RPE level, while choroid abnormalities were unclear. In the retinal areas of 22 eyes, which were not affected by RRD, we observed PL without retinal tears; some were accompanied by vitreous traction and tractional retinal detachment. Pre-, intra-, and post-operative assessments of original flap tears suggested that PL might be a risk factor for RRD, developing alongside or separately from LD.
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- 2022
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9. Clinically Significant Nonperfusion Areas on Widefield OCT Angiography in Diabetic Retinopathy
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Kentaro Kawai, MD, Tomoaki Murakami, MD, PhD, Yuki Mori, MD, Kenji Ishihara, MD, PhD, Yoko Dodo, MD, PhD, Noriko Terada, MD, Keiichi Nishikawa, MD, Kazuya Morino, MD, and Akitaka Tsujikawa, MD, PhD
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Diabetic retinopathy ,Nonperfusion areas ,Neovascularization ,Semiautomatic quantification ,Widefield OCT angiography ,Ophthalmology ,RE1-994 - Abstract
Purpose: To investigate the distribution of clinically significant nonperfusion areas (NPAs) on widefield OCT angiography (OCTA) images in patients with diabetes. Design: Prospective, cross-sectional, observational study. Participants: One hundred and forty-four eyes of 114 patients with diabetes. Methods: Nominal 20 × 23 mm OCTA images were obtained using a swept-source OCTA device (Xephilio OCT-S1), followed by the creation of en face images 20-mm (1614 pixels) in diameter centering on the fovea. The nonperfusion squares (NPSs) were defined as the 10 × 10 pixel squares without retinal vessels, and the ratio of eyes with the NPSs to all eyes in each square was referred to as the NPS ratio. The areas with probabilistic differences (APD) for proliferative diabetic retinopathy (PDR) and nonproliferative diabetic retinopathy (NPDR) (APD[PDR] and APD[NPDR]) were defined as sets of squares with higher NPS ratios in eyes with PDR and NPDR, respectively. The P ratio (NPSs within APD[PDR] but not APD[NPDR]/all NPSs) was also calculated. Main Outcome Measures: The probabilistic distribution of the NPSs and the association with diabetic retinopathy (DR) severity. Results: The NPSs developed randomly in eyes with mild and moderate NPDR and were more prevalent in the extramacular areas and the temporal quadrant in eyes with severe NPDR and PDR. The APD(PDR) was distributed mainly in the extramacular areas, sparing the areas around the vascular arcades and radially peripapillary capillaries. The APD(PDR) contained retinal neovascularization more frequently than the non-APD(PDR) (P = 0.023). The P ratio was higher in eyes with PDR than in those with NPDR (P < 0.001). The multivariate analysis designated the P ratio (odds ratio, 8.293 × 107; 95% confidence interval, 6.529 × 102–1.053 × 1013; P = 0.002) and the total NPSs (odds ratio, 1.002; 95% confidence interval, 1.001–1.003; P < 0.001) as independent risk factors of PDR. Most eyes with NPDR and 4-2-1 rule findings of DR severity had higher P ratios but not necessarily greater NPS numbers. Conclusions: The APD(PDR) is uniquely distributed on widefield OCTA images, and the NPA location patterns are associated with DR severity, independent of the entire area of NPAs. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references.
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- 2023
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10. The complete mitochondrial genome of Acanthopagrus pacificus (Perciformes, Sparidae) from Iriomotejima Island, Okinawa, Japan
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Kentaro Kawai, Hiroki Fujita, and Tetsuya Umino
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mitochondrial dna ,next generation sequencing ,pacific seabream ,phylogeny ,sparid ,Genetics ,QH426-470 - Abstract
The Pacific seabream, Acanthopagrus pacificus, is a commercially valuable resource for fisheries around the West Pacific Ocean countries. Although the phylogenetic position of the A. pacificus within the genus Acanthopagrus changes by the differences in the target gene regions or fish sampling locations, the genetic information of the species is quite limited. In this study, the complete mitochondrial genome of A. pacificus from Iriomotejima Island, Okinawa, Japan was determined. The sequence is 16,640 bp in length and consists of 13 protein-coding genes, 2 rRNA genes (12S rRNA and 16S rRNA), 22 tRNA genes, and one control region. A reconstructed phylogenetic tree showed that A. pacificus has the furthest relationship to other Acanthopagrus species in the genus.
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- 2022
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11. Pathological Neurovascular Unit Mapping onto Multimodal Imaging in Diabetic Macular Edema
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Tomoaki Murakami, Kenji Ishihara, Noriko Terada, Keiichi Nishikawa, Kentaro Kawai, and Akitaka Tsujikawa
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center-involving diabetic macular edema ,clinically significant macular edema ,diabetic macular edema ,diabetic retinopathy ,disorganization of retinal inner layers ,fluorescein angiography ,Medicine (General) ,R5-920 - Abstract
Diabetic retinopathy is a form of diabetic microangiopathy, and vascular hyperpermeability in the macula leads to retinal thickening and concomitant reduction of visual acuity in diabetic macular edema (DME). In this review, we discuss multimodal fundus imaging, comparing the pathogenesis and interventions. Clinicians diagnose DME using two major criteria, clinically significant macular edema by fundus examination and center-involving diabetic macular edema using optical coherence tomography (OCT), to determine the appropriate treatment. In addition to fundus photography, fluorescein angiography (FA) is a classical modality to evaluate morphological and functional changes in retinal capillaries, e.g., microaneurysms, capillary nonperfusion, and fluorescein leakage. Recently, optical coherence tomography angiography (OCTA) has allowed us to evaluate the three-dimensional structure of the retinal vasculature and newly demonstrated that lamellar capillary nonperfusion in the deep layer is associated with retinal edema. The clinical application of OCT has accelerated our understanding of various neuronal damages in DME. Retinal thickness measured by OCT enables us to quantitatively assess therapeutic effects. Sectional OCT images depict the deformation of neural tissues, e.g., cystoid macular edema, serous retinal detachment, and sponge-like retinal swelling. The disorganization of retinal inner layers (DRIL) and foveal photoreceptor damage, biomarkers of neurodegeneration, are associated with visual impairment. Fundus autofluorescence derives from the retinal pigment epithelium (RPE) and its qualitative and quantitative changes suggest that the RPE damage contributes to the neuronal changes in DME. These clinical findings on multimodal imaging help to elucidate the pathology in the neurovascular units and lead to the next generation of clinical and translational research in DME.
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- 2023
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12. Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane
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Yukiko Karuo, Ayaka Kametani, Atsushi Tarui, Kazuyuki Sato, Kentaro Kawai, and Masaaki Omote
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aryl 1,1-difluoroethyl ether ,1,1-difluoroethene ,fluorine compound ,halothane ,phenol ,Science ,Organic chemistry ,QD241-441 - Abstract
An efficient and convenient method for the synthesis of structurally unique and highly functionalized aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers has been developed. This approach exhibits a broad reaction scope, a simple operation and without the need of any expensive transition-metal catalyst, highly toxic or corrosive reagents. Notably, we demonstrate the potential utility of halothane for the synthesis of aryl gem-difluoroalkyl ethers containing the bromochloromethyl group.
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- 2021
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13. Unilateral transient high myopization after pediatric strabismus surgery: Observation by anterior segment optical coherence tomography
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Akihito Yoshimura, Manabu Miyata, Yuki Muraoka, Kentaro Kawai, and Akitaka Tsujikawa
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Anterior segment optical coherence tomography ,Strabismus surgery ,Myopization ,Ciliary detachment ,Ophthalmology ,RE1-994 - Abstract
Purpose: To describe an unusual case of unilateral transient high myopization after pediatric strabismus surgery. Observations: A 6-year-old girl with intermittent exotropia had undergone strabismus surgery and experienced a transient decrease in best-corrected visual acuity (BCVA, from 20/20 to 20/33) with high myopization (from +0.25 D to −9.00 D). Slit-lamp microscopy showed anterior chamber inflammation and a narrow angle only in the affected eye. Anterior segment optical coherence tomography (AS-OCT) revealed ciliary body detachment, a narrow angle, a shallow anterior chamber, and an anteroposterior elongation of the crystalline lens in the affected eye. Her symptoms of blurry vision and high myopization improved 8 weeks postoperatively. AS-OCT revealed the resolution of the ciliary body detachment, an open angle, and a deep anterior chamber, with normalization of the anteroposterior length of the crystalline lens. Her BCVA recovered to 20/20 with spherical equivalence of 0 D. Conclusions and Importance: We reported on an extremely rare case of unilateral transient high myopization following strabismus surgery, which was resolved without additional surgery. This myopization was probably caused due to ciliary body inflammation.
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- 2022
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14. Synthesis of new fluorescent molecules having an aggregation-induced emission property derived from 4-fluoroisoxazoles
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Kazuyuki Sato, Akira Kawasaki, Yukiko Karuo, Atsushi Tarui, Kentaro Kawai, and Masaaki Omote
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aggregation-induced emission ,boron ketoiminates ,fluorescent probe ,α-fluorinated boron ketoiminates ,4-fluoroisoxazoles ,Science ,Organic chemistry ,QD241-441 - Abstract
Fluorescent molecules based on a fluorinated isoxazole scaffold were synthesized and investigated for their photochemical properties. The introduction of a fluorine substituent into 3,5-diarylisoxazoles led to an increase of fluorescence intensity and exhibited a redshift in the emission intensity. α-Fluorinated boron ketoiminates (F-BKIs) were also synthesized via a ring-opening reaction of 4-fluoroisoxazoles and exhibited highly fluorescent luminescence and aggregation-induced emission (AIE), showing promise as a new fluorophore.
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- 2020
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15. Structural change of retinoic-acid receptor-related orphan receptor induced by binding of inverse-agonist: Molecular dynamics and ab initio molecular orbital simulations
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Shusuke Suzuki, Toshiya Nakamura, Ryosuke Saito, Yuta Terauchi, Kentaro Kawai, Midori Takimoto-Kamimura, and Noriyuki Kurita
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Molecular dynamics simulation ,Fragment molecular orbital ,Protein ligand interaction ,Agonist ,Inverse agonist ,Nuclear receptor ,Biotechnology ,TP248.13-248.65 - Abstract
To elucidate structural changes in the retinoic acid receptor-related orphan receptor gamma (RORγt) induced by the binding of an agonist or an inverse agonist, we conducted molecular dynamics (MD) simulations in explicit water. In addition, ab initio fragment molecular orbital calculations were carried out for certain characteristic structures obtained from the MD simulations to reveal important interactions between the amino acid residues of RORγt, and to distinguish the different effects in the binding of an agonist and an inverse agonist on the structure of RORγt. The results elucidate that the hydrogen bond between His479 of helix11 (H11) and Tyr502 of helix12 (H12) is important to keep the H12 conformation in the agonist-bound RORγt. In contrast, in the inverse-agonist-bound RORγt, the side chain of His479 rotates, significantly weakening the interaction between His479 and Tyr502, leading to a conformational change in H12. Therefore, the present molecular simulations clearly indicate that the conformational change in the side chain of His479 in the inverse-agonist-bound RORγt is the main reason for the H12 destabilization induced by the binding of the inverse agonist. Such a conformational change does not occur on the binding of the agonist in RORγt, owing to the strong hydrogen bond between His479 and Tyr502.
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- 2020
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16. Oyster farms are the main spawning grounds of the black sea bream Acanthopagrus schlegelii in Hiroshima Bay, Japan
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Kentaro Kawai, Hiroki Fujita, Gustavo Sanchez, and Tetsuya Umino
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Shellfish aquaculture ,Fish spawning ,Sparid ,Anthropogenic impact ,Fish eggs ,Medicine ,Biology (General) ,QH301-705.5 - Abstract
Understanding the anthropogenic impact of oyster farms is essential for the management and conservation of marine fishes. In Japan, Hiroshima Bay is the region with the most intense oyster farming and thus suitable to study the impact of these farms. Here, we surveyed spherical planktonic eggs of the black sea bream Acanthopagrus schlegelii, one of the most abundant fish in the Bay. Our survey was performed at fourteen stations which included places with oyster farms and historical spawning grounds. We found the highest egg densities in four stations, one with historical spawning aggregations and three with major oyster farms. Besides, surveys at the innermost part of Hiroshima Bay, where two major rivers discharge, showed a low density of eggs indicating that black sea bream avoids spawning in low salinity areas. Our study suggests that oyster farms benefit spawners of black sea bream by providing more food sources than historical spawning grounds for efficient spawning. Yet, whether oyster farms represent a full advantage for the species remains unclear, particularly because they are known to host jellyfishes that prey on eggs and limit water flow that can influence the survival of fish eggs.
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- 2021
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17. Ultrasonic-assisted anodic oxidation of 4H-SiC (0001) surface
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Xiaozhe Yang, Xu Yang, Kentaro Kawai, Kenta Arima, and Kazuya Yamamura
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Industrial electrochemistry ,TP250-261 ,Chemistry ,QD1-999 - Abstract
An ultrasonic-assisted electrochemical mechanical polishing (UAECMP) technique that combines ultrasonic vibration and electrochemical mechanical polishing (ECMP) is proposed. The effect of ultrasonic vibration on the anodic oxidation rate of a 4H-SiC (0001) surface was studied, and it was confirmed that ultrasonic vibration significantly enhanced the anodic oxidation of SiC. Compared with conventional anodic oxidation, the oxidation rate increased by about 34% with ultrasonic assistance (UA) in the initial oxidation stage, and by about 11% during subsequent anodic oxidation. In addition, the oxidation can be promoted continuously with increasing oxidation time owing to the porous structure of the oxide layer. UAECMP is very promising as an efficient finishing technique for SiC surfaces. Keywords: Silicon carbide, Ultrasonic-assisted electrochemical mechanical polishing, Ultrasonic-assisted anodic oxidation, Ultrasonic vibration
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- 2019
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18. The role of the isolation of the marginal seas during the Pleistocene in the genetic structure of black sea bream Acanthopagrus schlegelii (Bleeker, 1854) in the coastal waters of Japan
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Yutaro Yamashita, Gustavo Sanchez, Kentaro Kawai, Satoshi Tomano, Hiroki Fujita, and Tetsuya Umino
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Black sea bream ,Mitochondrial control region ,Genetic structure ,Pleistocene ,Refugia ,Northwestern Pacific Ocean ,Medicine ,Biology (General) ,QH301-705.5 - Abstract
The black sea bream Acanthopagrus schlegelii (Bleeker, 1854) is a commercially important species in Japanese waters. Assessing its population structure is essential to ensure its sustainability. In the Northwestern Pacific, historical glacial and interglacial periods during the Pleistocene have shaped the population structure of many coastal marine fishes. However, whether these events affected the population of black sea bream remains unknown. To test this hypothesis and to assess the population structure of black sea bream, we used 1,046 sequences of the mitochondrial control region from individuals collected throughout almost the entire Japanese coastal waters and combined them with 118 sequences from populations distributed in other marginal seas of the Northwestern Pacific Ocean. As in other coastal marine fish with similar distribution, we also found evidence that the glacial refugia on the marginal seas prompted the formation of three lineages in black sea bream. These lineages present signatures of population growth that coincided with the interglacial periods of the Pleistocene. While the origin of Lineages B and C remains unclear, the higher relative frequency of Lineage A in the southernmost location suggests its origin in the South China Sea. The non-significant pairwise ΦST and AMOVA of Japanese populations and the presence of these three lineages mixed in Japanese waters; strongly suggest that these lineages are homogenized in both the Sea of Japan and the Pacific Ocean. Our results indicate that the black sea bream should be managed as a single stock in Japan until the strength of connectivity in contemporary populations is further addressed using non-coding nuclear markers.
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- 2021
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19. Cyanobacterial cell lineage analysis of the spatiotemporal hetR expression profile during heterocyst pattern formation in Anabaena sp. PCC 7120.
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Hironori Asai, Shunsuke Iwamori, Kentaro Kawai, Shigeki Ehira, Jun-ichi Ishihara, Kazuyuki Aihara, Shuichi Shoji, and Hideo Iwasaki
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Medicine ,Science - Abstract
Diazotrophic heterocyst formation in the filamentous cyanobacterium, Anabaena sp. PCC 7120, is one of the simplest pattern formations known to occur in cell differentiation. Most previous studies on heterocyst patterning were based on statistical analysis using cells collected or observed at different times from a liquid culture, which would mask stochastic fluctuations affecting the process of pattern formation dynamics in a single bacterial filament. In order to analyze the spatiotemporal dynamics of heterocyst formation at the single filament level, here we developed a culture system to monitor simultaneously bacterial development, gene expression, and phycobilisome fluorescence. We also developed micro-liquid chamber arrays to analyze multiple Anabaena filaments at the same time. Cell lineage analyses demonstrated that the initial distributions of hetR::gfp and phycobilisome fluorescence signals at nitrogen step-down were not correlated with the resulting distribution of developed heterocysts. Time-lapse observations also revealed a dynamic hetR expression profile at the single-filament level, including transient upregulation accompanying cell division, which did not always lead to heterocyst development. In addition, some cells differentiated into heterocysts without cell division after nitrogen step-down, suggesting that cell division in the mother cells is not an essential requirement for heterocyst differentiation.
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- 2009
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20. Redescription and molecular characterization of Mothocya parvostis Bruce, 1986 (Crustacea: Isopoda: Cymothoidae) parasitic on Japanese halfbeak, Hyporhamphus sajori (Temminck & Schlegel, 1846) (Hemiramphidae) with Mothocya sajori Bruce, 1986 placed into synonymy
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HIROKI FUJITA, PANAKKOOL THAMBAN ANEESH, KENTARO KAWAI, SHIN-ICHI KITAMURA, MICHITAKA SHIMOMURA, TETSUYA UMINO, and SUSUMU OHTSUKA
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Animal Science and Zoology ,Ecology, Evolution, Behavior and Systematics - Abstract
Two species of Mothocya have previously been recorded from Hyporhamphus sajori: M. parvostis Bruce, 1986 and M. sajori Bruce, 1986. Mothocya parvostis is re-described based on the ovigerous female type and additional materials collected from the host from in and around the type locality. Morphological re-examination of fresh specimens and the type materials together with genetic data show that the M. sajori and M. parvostis are the same species, differing primarily in size, therefore we have placed Mothocya sajori Bruce, 1986 into a junior synonym of Mothocya parvostis Bruce, 1986. Mothocya parvostis is characterized by the following combinations of characters: 1) body slightly to moderately twisted to one side; 2) pereonite 7 posterior margin moderately to deeply recessed; 3) uropodal rami extending to pleotelson posterior margin; and 4) uropod rami bluntly rounded, exopod 1.5 times as long as peduncle. The differences of four morphological features for M. parvostis and M. sajori was quantified. Furthermore, a total of 635 isopods infesting H. sajori were collected from all over Japan to conduct quantitative morphological and molecular sequence analyses (mitochondrial cytochrome c oxidase subunit I and 16S rRNA). Although the four quantitative features did not overlap between the two species in type specimens, all quantitative morphological values of newly collected specimens in this study did not display a bimodal distribution. In addition, our molecular analyses found only a single clade for our newly collected specimens in neighbor-joining tree.
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- 2023
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21. Sn-Sb-Ag系高温鉛フリーはんだの疲労特性に及ぼす添加元素の影響
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Kohei Mitsui, Mizuki Yamamoto, Kentaro Kawai, Tatsuya Kobayashi, Ikuo Shohji, and Hirohiko Watanabe
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Electrical and Electronic Engineering - Published
- 2023
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22. Formation of Isolable Dearomatized [4 + 2] Cycloadducts from Benzenes, Naphthalenes, and N-Heterocycles Using 1,2-Dihydro-1,2,4,5-tetrazine-3,6-diones as Arenophiles under Visible Light Irradiation
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Kazuki Ikeda, Riku Kojima, Kentaro Kawai, Takayasu Murakami, Takashi Kikuchi, Masahiro Kojima, Tatsuhiko Yoshino, and Shigeki Matsunaga
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Published
- 2023
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23. わかるDNAシークエンサ
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Kentaro KAWAI
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Mechanical Engineering - Published
- 2023
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24. Formation of gold nanoparticle dimers on silicon by sacrificial DNA origami technique.
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Naoki Yamashita, Zhipeng Ma, Seongsu Park, Yoshikazu Hirai, Toshiyuki Tsuchiya, Osamu Tabata, and Kentaro Kawai
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- 2017
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25. Establishment of an efficient transformation method of garden stock (Matthiola incana) using a callus formation chemical inducer
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Yoshiki Tanahara, Kaho Yamanaka, Kentaro Kawai, Yukiko Ando, and Takashi Nakatsuka
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Plant Science ,Agronomy and Crop Science ,Biotechnology - Published
- 2022
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26. Spawning time of black sea bream Acanthopagrus schlegelii , related to underwater photoperiodism in oyster farms
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Kentaro Kawai, Hiroki Fujita, Diego Deville, and Tetsuya Umino
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Reproduction ,Animals ,Aquaculture ,Aquatic Science ,Ostreidae ,Sea Bream ,Ecology, Evolution, Behavior and Systematics ,Perciformes - Abstract
The embryonic development times, spawning timing and hatching rates of the black sea bream Acanthopagrus schlegelii were examined to investigate the potential effect of seawater temperature, tides and photoperiod on the reproductive rhythm of this species in Hiroshima Bay, Japan. Low temperatures decreased hatching rates and extended the hatching time, and the minimum temperature threshold for hatching was 15°C. Back-calculated spawning times indicated that the peak of spawning occurred just before sunset and the reduction in diurnal light intensity around the oyster rafts acted as a trigger for spawning. In contrast, no correlation was found between spawning rhythms and tidal cycle. The results highlight the important role of oyster farms in the reproductive cycle and population dynamics of A. schlegelii in Hiroshima Bay, the main spawning ground for this species in Japan. The study findings provide insights for the sustainable management of this important sparid species.
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- 2022
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27. Age-related differences in glenohumeral internal rotation deficit, humeral retrotorsion angle, and posterior shoulder tightness in baseball players
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Kota Tanaka, Hiroki Funasaki, Yusuke Murayama, Akiko Nagai, Kentaro Kawai, Mitsuru Saito, Makoto Suzukawa, Makiko Aoyama, Hiromu Tanaka, and Haruhito Aoki
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Male ,Shoulder ,Cross-Sectional Studies ,Adolescent ,Shoulder Joint ,Humans ,Orthopedics and Sports Medicine ,Surgery ,General Medicine ,Humerus ,Range of Motion, Articular ,Baseball - Abstract
Glenohumeral internal rotation deficit is generally recognized as a risk factor for throwing disability in baseball players. However, the pathology, timing of onset, role in the onset of humeral retrotorsion angle (HTA) and soft tissue extensibility (STE), and the relationship with age remain unclear. Therefore, the purpose of this cross-sectional study was to investigate age-related glenohumeral internal rotation deficit, HTA, and STE in Japanese baseball players and determine whether these factors correlate with throwing disability.Participants were 172 male baseball players divided into a symptomatic group (n = 68) and an asymptomatic group (n = 104). The mean age at examination was 15.4 ± 3.2 (range, 8-22) years. Measurement items were range of motion of bilateral internal and external rotation at 90° abduction (2ndIR and 2ndER, respectively), bilateral HTA, and posterior shoulder muscle elasticity. Correlations of age, symptom, and dominance with these measurements were investigated, and significant bilateral differences in HTA and STE by age and symptom were analyzed.HTA and 2ndER of the dominant side were significantly greater than those of the nondominant side in those over the age of 13 years in both the asymptomatic and symptomatic groups. In contrast, 2ndIR of the dominant side was significantly smaller than that of the nondominant side in those over the age of 13 years in both the asymptomatic and symptomatic groups. The difference in HTA between the dominant and nondominant sides increased and then plateaued at 12° after the age of 16 years. STE was observed only in the symptomatic group, and the value of STE was significantly greater in players aged16 years compared with that in players aged12 years (P = .001). Muscle elasticity did not differ significantly between sides and showed no correlation with STE.The difference in HTA between the dominant and nondominant sides increased with age until 16 years old regardless of symptoms. STE in the dominant side was observed only in symptomatic baseball players after the age of 13 years and increased with age, plateauing around the age of 16 years. Posterior shoulder muscle elasticity was not indicated as a cause of STE.
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- 2022
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28. Modulation of Optical Properties by ZnSe Shell Thickness Control in InP/ZnSe/ZnS Quantum Dots Front Cover: (ChemNanoMat 5/2023)
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Akihito Okamoto, Haruki Bai, Shintaro Toda, Maowei Huang, Hirotake Kajii, Kentaro Kawai, and Hirohiko Murakami
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Biomaterials ,Renewable Energy, Sustainability and the Environment ,Materials Chemistry ,Energy Engineering and Power Technology - Published
- 2023
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29. Reactions Using Freons and Halothane as Halofluoroalkyl/Halofluoroalkenyl Building Blocks
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Yukiko Karuo, Atushi Tarui, Kazuyuki Sato, Kentaro Kawai, and Masaaki Omote
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General Chemical Engineering ,Materials Chemistry ,General Chemistry ,Biochemistry - Published
- 2023
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30. Controlling Thickness of ZnSe Intermediate Shell Narrows FWHM of Green‐Emitting Spectra of InP/ZnSe/ZnS Multi‐Shell Quantum Dots
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Akihito Okamoto, Haruki Bai, Shintaro Toda, Maowei Huang, Hirotake Kajii, Kentaro Kawai, and Hirohiko Murakami
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Biomaterials ,Renewable Energy, Sustainability and the Environment ,Materials Chemistry ,Energy Engineering and Power Technology - Published
- 2023
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31. Macular atrophy at 5 years after photodynamic therapy for polypoidal choroidal vasculopathy
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Kentaro Kawai, Manabu Miyata, Sotaro Ooto, Hiroshi Tamura, Naoko Ueda-Arakawa, Ayako Takahashi, Akihito Uji, Yuki Muraoka, Masahiro Miyake, Kenji Yamashiro, and Akitaka Tsujikawa
- Subjects
Ophthalmology - Abstract
To investigate predictors for macular atrophy (MA) involving the fovea after photodynamic therapy (PDT) followed by pro re nata (PRN) treatment for polypoidal choroidal vasculopathy (PCV).This prospective observational study analysed treatment-naïve eyes with symptomatic PCV without MA at baseline which were followed up for 5 years. All eyes were initially treated with PDT, followed by a PRN regimen of anti-vascular endothelial growth factor (VEGF) therapy and/or PDT. We assigned eyes with and eyes without development of MA involving the fovea 5 years after the initial treatment into MA and non-MA groups, respectively. Baseline parameters and the number of treatments were compared between the two groups.Seventy-two eyes of 69 consecutive patients were included, and 29 eyes of 29 patients were analysed. Twelve (41%) and 17 (59%) eyes were assigned into the MA and non-MA groups, respectively. There were significant differences in subfoveal choroidal thickness (226.2 ± 47.8 μm vs. 278.8 ± 68.1 μm, P = 0.03) and number of anti-VEGF injections (13.7 ± 9.6 vs. 5.4 ± 5.6, P = 0.007) between the MA and non-MA groups, but not in the number of PDT sessions (P = 0.71). Best-corrected visual acuity at 5 years in the MA group was lower than in the non-MA group (P = 0.048).Our long-term observation suggests that a thin subfoveal choroid at baseline and many followed anti-VEGF injections in a PRN regimen increase the risk for development of MA involving the fovea 5 years after PDT.
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- 2022
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32. Efficient and slurryless ultrasonic vibration assisted electrochemical mechanical polishing for 4H–SiC wafers
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Xu Yang, Kenta Arima, Haiyang Gu, Kentaro Kawai, Kazuya Yamamura, and Xiaozhe Yang
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Materials science ,Process Chemistry and Technology ,Oxide ,Polishing ,Electrolyte ,Electrochemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Grinding ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Ceramics and Composites ,Surface roughness ,Wafer ,Composite material ,Layer (electronics) - Abstract
This paper proposes a slurryless, highly efficient polishing method called ultrasonic vibration assisted electrochemical mechanical polishing (UAECMP) to realize 4H–SiC wafers with subnanometer surface roughness. UAECMP involves using ultrasonic vibration to simultaneously assist anodic oxidation of the SiC surface and mechanical removal of the generated oxide layer. The performance of UAECMP was evaluated by experiments and theoretical analyses. For a 4H–SiC (0001) surface, UAECMP achieved a material removal rate (MRR) of 14.54 μm/h, which was 4.5 times greater than that of ordinary electrochemical mechanical polishing (ECMP) and 290 times greater than that of mechanical polishing. Ultrasonic vibration increased the anodic oxidation rate by introducing local transient strain to the SiC surface and increasing the temperatures of the polishing area and electrolyte. The effect increased with the amplitude of the ultrasonic vibration. However, increasing the ultrasonic vibration amplitude also increased the surface roughness due to the large fluctuations of polishing marks caused by the grinding stone and SiC surface impact and the increasing residual oxide. Therefore, we propose a high-efficiency and -quality polishing process for SiC wafers that combines UAECMP and ECMP. The proposed polishing process may help simplify the existing manufacturing process for SiC wafers.
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- 2022
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33. 1,2-Disubstituted 1,2-Dihydro-1,2,4,5-tetrazine-3,6-dione as a Dynamic Covalent Bonding Unit at Room Temperature
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Kentaro Kawai, Kazuki Ikeda, Akane Sato, Akira Kabasawa, Masahiro Kojima, Kenta Kokado, Akira Kakugo, Kazuki Sada, Tatsuhiko Yoshino, and Shigeki Matsunaga
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Colloid and Surface Chemistry ,General Chemistry ,Biochemistry ,Catalysis - Abstract
Dynamic covalent bonds are useful tools in a wide range of applications. Although various reversible chemical reactions have been studied for this purpose, the requirement for harsh conditions, such as high temperature and low or high pH, to activate generally stable covalent bonds limits their potential applications involving biomolecules or household utilization. Here, we report the design, synthesis, characterization, and dynamic covalent bonding properties of 1,2-disubstituted 1,2-dihydro-1,2,4,5-tetrazine-3,6-dione (TETRAD). Hetero-Diels-Alder reactions of TETRAD with furan derivatives and their retro-reactions proceeded rapidly at room temperature under neutral conditions, enabling a chemically induced sol-gel transition system.
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- 2022
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34. Effectiveness of Rotator Cuff Exercises for Throwing Injuries of the Shoulder: Comparison between Closed/Open Kinetic Chains
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Kentaro KAWAI and Hiroki FUNASAKI
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Physical Therapy, Sports Therapy and Rehabilitation - Published
- 2022
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35. Synthesis of 2,2-difluoro-2-arylethylamines as fluorinated analogs of octopamine and noradrenaline
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Atsushi Tarui, Erika Kamata, Koji Ebisu, Yui Kawai, Ryota Araki, Takeshi Yabe, Yukiko Karuo, Kazuyuki Sato, Kentaro Kawai, and Masaaki Omote
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Organic Chemistry - Abstract
Abstrtact A series of 2,2-difluoro-2-arylethylamines was synthesized as fluorinated analogs of octopamine and noradrenaline with the expectation of bioisosteric OH/F exchanges. The syntheses of these compounds were performed by a Suzuki–Miyaura cross-coupling reaction of 4-(bromodifluoroacetyl)morpholine with aryl boronic acids to produce the intermediate 2,2-difluoro-2-arylacetamides, followed by transformation of difluoroacetamide to difluoroethylamine.
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- 2022
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36. Novel highly-efficient and dress-free polishing technique with plasma-assisted surface modification and dressing
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Kenta Arima, Atsunori Nozoe, Kentaro Kawai, Rongyan Sun, Kazuya Yamamura, and Junji Nagahashi
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0209 industrial biotechnology ,Materials science ,Metallurgy ,Abrasive ,General Engineering ,Polishing ,02 engineering and technology ,Plasma ,021001 nanoscience & nanotechnology ,Grinding ,020901 industrial engineering & automation ,Slurry ,Abrasive grinding ,Surface modification ,Wafer ,0210 nano-technology - Abstract
Slurry is widely used in polishing difficult-to-machine materials. However, it is accompanied with some issues, such as the agglomeration of abrasives and high disposal cost. Although using fixed abrasive grains instead of slurry can solve these issues, the problems of wear and of loading fixed abrasive grinding stones, which result in decrease of material removal rate (MRR), also need to be solved. Many researches have been conducted on the self-sharpening of fixed abrasive grinding stones. However, the self-sharpening of grinding stones is not efficient with ultra-low polishing pressure, which is not large enough to break bonds so as to expose new abrasives. In this study, a novel dress-free dry polishing process was proposed, where it combines plasma-assisted polishing and plasma-assisted dressing using Ar-based CF4 plasma and a vitrified-bonded grinding stone. Polishing experiments were conducted on sintered AlN wafer. Also, as the main component of vitrified bond materials, silica was etched using CF4 plasma, which is equivalent to the continuous dressing of grinding stone surfaces. Since new abrasives could be constantly exposed, a high MRR was maintained. Thus, a dress-free high integrity polishing process was realized. Moreover, the CF4 plasma irradiation increased the MRR twice, as CF4 plasma can not only dress a grinding stone in real time but can also modify AlN to AlF3, which can easily be removed.
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- 2021
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37. Novel SiC wafer manufacturing process employing three-step slurryless electrochemical mechanical polishing
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Xu Yang, Kenta Arima, Kentaro Kawai, Kazuya Yamamura, and Xiaozhe Yang
- Subjects
Materials science ,Waviness ,Strategy and Management ,Polishing ,Management Science and Operations Research ,Industrial and Manufacturing Engineering ,Grinding ,chemistry.chemical_compound ,chemistry ,Chemical-mechanical planarization ,Silicon carbide ,Surface roughness ,Wafer ,Composite material ,Layer (electronics) - Abstract
In this work, a three-step silicon carbide (SiC) wafer manufacturing process using slurryless electrochemical mechanical polishing (ECMP) is proposed. In the first step, ECMP using fixed hard abrasives is applied to an as-sliced SiC wafer to rapidly remove the subsurface damage (SSD) and waviness induced during slicing. Then, the SiC wafer is polished using the second-step ECMP by employing a ceria grinding stone to remove the residual SSD and decrease the surface roughness. Finally, a finishing ECMP step employing a low potential is used to further decrease the surface roughness. Before applying this proposed three-step process to an as-sliced SiC wafer, a suitable grinding stone was selected for the first-step ECMP by evaluating the uniformity of the induced SSD layer and the obtained surface roughness. By applying the first step, i.e., ECMP using fixed-diamond abrasives, the root-mean-square (Sq) surface roughness decreased from 163.33 to 25.45 nm within 20 min with a material removal rate (MRR) of 62 μm/h. During the 30-min second step, the Sq and the maximum height (Sz) surface roughness values further decreased to 0.82 and 6.96 nm, respectively, with an MRR of 11 μm/h. Finally, the 60-min finishing step allowed the Sq and Sz surface roughness values to further decrease to 0.11 and 1.46 nm, respectively; furthermore, a surface with a step-terrace structure was obtained, which is comparable to the surface obtained by conventional chemical mechanical polishing. Overall, the proposed three-step slurryless ECMP method allowed for the rapid transformation of an unprocessed SiC wafer to an atomically smooth surface and is thus expected to reduce the cost and manpower required during SiC wafer manufacturing.
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- 2021
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38. Importance of the Azole Moiety of Cimetidine Derivatives for the Inhibition of Human Multidrug and Toxin Extrusion Transporter 1 (hMATE1)
- Author
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Masaaki Omote, Takeshi Nabe, Naoki Kobayashi, Masato Otsuka, Atsushi Tarui, Kazuyuki Kitatani, Masaya Matsuda, Kentaro Kawai, Susumu Shinya, Kazuyuki Sato, and Yukiko Karuo
- Subjects
Azoles ,Models, Molecular ,Organic Cation Transport Proteins ,Pharmacology ,Crystallography, X-Ray ,Nephrotoxicity ,Structure-Activity Relationship ,chemistry.chemical_compound ,Drug Discovery ,medicine ,Humans ,Moiety ,Structure–activity relationship ,Cimetidine ,chemistry.chemical_classification ,Dose-Response Relationship, Drug ,Molecular Structure ,Antagonist ,Transporter ,General Chemistry ,General Medicine ,chemistry ,Azole ,Histamine ,medicine.drug - Abstract
Herein, we describe the design and synthesis of cimetidine analogs, as well as their inhibitory activity toward the human multidrug and toxin extrusion transporter 1 (hMATE1), which is related to nephrotoxicity of drugs. Cimetidine is the histamine H2-receptor antagonist, but also inhibits hMATE1, which is known to cause renal impairment. We designed and synthesized cimetidine analogs to evaluate hMATE1 inhibitory activity to reveal whether the analogs could reduce the inhibition of hMATE1. The results showed that all analogs with an unsubstituted guanidino group exhibited hMATE1 inhibitory activity. On the other hand, there was a clear difference in the hMATE1 inhibitory activity for the other compounds. That is, compounds with a methylimidazole ring exhibited hMATE1 inhibition, while compounds with a phenyl ring did not. The results suggest that the ability to form hydrogen bonds at the azole moiety is strongly involved in the hMATE1 inhibition.
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- 2021
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39. Simple synthesis of multi-halogenated alkenes from 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane)
- Author
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Yukiko Karuo, Atsushi Tarui, Kazuyuki Sato, Kentaro Kawai, and Masaaki Omote
- Subjects
Organic Chemistry - Abstract
A series of aryl fluoroalkenyl ethers that contain chlorine and bromine as well as fluorine atoms were prepared in moderate to good yields via the reactions of phenols and 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane) in the presence of KOH. This simple reaction enabled the construction of highly halogenated compounds with the potential for further functionalization. The reaction involved a highly reactive difluoroethylene intermediate, which was produced by the reaction between halothane and KOH.
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- 2022
40. Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone
- Author
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Motoyuki Isoda, Kazuyuki Sato, Kenta Kameda, Kana Wakabayashi, Ryota Sato, Hideki Minami, Yukiko Karuo, Atsushi Tarui, Kentaro Kawai, and Masaaki Omote
- Subjects
Organic Chemistry - Abstract
Rhodium-catalyzed intramolecular reductive aldol-type cyclization was described to give β-hydroxylactones with high diastereoselectivities. This cyclization gave syn- or anti-form β-hydroxylactones selectively by changing the solvent. Furthermore, the synthesis of a chiral necic acid lactone was also described which is a part of structural component of pyrrolizidine alkaloid monocrotaline that is used for the preparation of pulmonary hypertension pathological model in rats.
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- 2022
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41. Selective Etching of Semiconductor Surfaces by Catalytic Activity of Nanocarbon
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Kentaro Kawai, Ryo Mikurino, Ayumi Ogasawara, Kenta Arima, and Kazuya Yamamura
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Semiconductor ,Materials science ,Chemical engineering ,business.industry ,Etching (microfabrication) ,General Medicine ,business ,Catalysis - Published
- 2021
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42. Identification and Synthesis of DDI-6, a Quinolinol Analog Capable of Activating Both Caenorhabditis elegans and Mouse Spermatozoa
- Author
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Ryo Tsunokawa, Yukiko Karuo, Riona Shiraki, Kazuyuki Sato, Kentaro Kawai, Ayaka Yoshida, Atsushi Tarui, Hitoshi Nishimura, Mayuko Nakahara-Yamada, and Masaaki Omote
- Subjects
endocrine system ,biology ,urogenital system ,Chemistry ,Spermiogenesis ,Activator (genetics) ,Acrosome reaction ,General Chemistry ,General Medicine ,biology.organism_classification ,Sperm ,In vitro ,Cell biology ,Human fertilization ,Drug Discovery ,Extracellular ,reproductive and urinary physiology ,Caenorhabditis elegans - Abstract
Sperm activation is an essential process by which the male gametes become capable of fertilization. Because the process in Caenorhabditis elegans is readily reproducible in vitro, this organism serves as an excellent model to investigate it. C. elegans sperm activation in vivo occurs during spermiogenesis. Membranous organelles (MOs) contained within spermatids fuse with the plasma membrane, resulting in extracellular release of their contents and relocation of some proteins indispensable for fertilization from the MO membrane onto the sperm surface. Intriguingly, these cytological alternations are exhibited similarly in mouse spermatozoa during the acrosome reaction, which also represents a form of sperm activation, prompting us to hypothesize that C. elegans and mice share a common mechanism for sperm activation. To explore this, we first screened a chemical library to identify compounds that activate C. elegans spermatozoa. Because a quinolinol analog named DDI-6 seemed to be a candidate sperm activator, we synthesized it to use for further analyses. This involved direct dechlorination and hydrogenolysis of commercially available 5-chloro-8-quinolinol, both of which are key steps to yield 1,2,3,4-tetrahydro-8-quinolinol, and we subsequently introduced the sulfonamide group to the compound. When C. elegans spermatids were stimulated with solvent alone or the newly synthesized DDI-6, approx. 3% and approx. 28% of spermatids became MO-fused spermatozoa, respectively. Moreover, DDI-6 triggered the acrosome reaction in approx. 20% of mouse spermatozoa, while approx. 12% became acrosome-reacted after mock stimulation. Thus, DDI-6 serves as a moderately effective activator for both C. elegans and mouse spermatozoa.
- Published
- 2021
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43. Fluorophenylalkyl-substituted cyanoguanidine derivatives as bacteria-selective MATE transporter inhibitors for the treatment of antibiotic-resistant infections
- Author
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Susumu Shinya, Kentaro Kawai, Naoki Kobayashi, Yukiko Karuo, Atsushi Tarui, Kazuyuki Sato, Masato Otsuka, and Masaaki Omote
- Subjects
Bacteria ,Organic Chemistry ,Clinical Biochemistry ,Pharmaceutical Science ,Membrane Transport Proteins ,Biochemistry ,Anti-Bacterial Agents ,Bacterial Proteins ,Anti-Infective Agents ,Drug Discovery ,Molecular Medicine ,Humans ,Molecular Biology ,Norfloxacin - Abstract
Drug efflux pump inhibitors for the multidrug resistance protein HmrM, a member of the multidrug and toxin extrusion (MATE) family of transporters, were investigated to increase the drug susceptibility of multidrug-resistant bacteria and restore the antimicrobial effect of fluoroquinolones, such as norfloxacin. The lead inhibitor, prepared from the known hMATE1 inhibitor cimetidine, reduced the norfloxacin resistance of HmrM-expressing strains by 92% at non-cytotoxic concentrations in human cells, and multidrug resistance protein MdtK-expressing strains by 86%. These results indicated that the inhibitor is a lead candidate for the development of drugs with a novel mechanism of action against infections caused by multidrug-resistant bacteria that act synergistically with antimicrobial drugs.
- Published
- 2022
44. Clinically Significant Nonperfusion Areas on Widefield OCT Angiography in Diabetic Retinopathy
- Author
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Kentaro Kawai, Tomoaki Murakami, Yuki Mori, Kenji Ishihara, Yoko Dodo, Noriko Terada, Keiichi Nishikawa, Kazuya Morino, and Akitaka Tsujikawa
- Subjects
Widefield OCT angiography ,Diabetic retinopathy ,Semiautomatic quantification ,General Medicine ,Nonperfusion areas ,Neovascularization - Abstract
[Purpose] To investigate the distribution of clinically significant nonperfusion areas (NPAs) on widefield OCT angiography (OCTA) images in patients with diabetes. [Design] Prospective, cross-sectional, observational study. [Participants] One hundred and forty-four eyes of 114 patients with diabetes. [Methods] Nominal 20 × 23 mm OCTA images were obtained using a swept-source OCTA device (Xephilio OCT-S1), followed by the creation of en face images 20-mm (1614 pixels) in diameter centering on the fovea. The nonperfusion squares (NPSs) were defined as the 10 × 10 pixel squares without retinal vessels, and the ratio of eyes with the NPSs to all eyes in each square was referred to as the NPS ratio. The areas with probabilistic differences (APD) for proliferative diabetic retinopathy (PDR) and nonproliferative diabetic retinopathy (NPDR) (APD[PDR] and APD[NPDR]) were defined as sets of squares with higher NPS ratios in eyes with PDR and NPDR, respectively. The P ratio (NPSs within APD[PDR] but not APD[NPDR]/all NPSs) was also calculated. [Main Outcome Measures] The probabilistic distribution of the NPSs and the association with diabetic retinopathy (DR) severity. [Results] The NPSs developed randomly in eyes with mild and moderate NPDR and were more prevalent in the extramacular areas and the temporal quadrant in eyes with severe NPDR and PDR. The APD(PDR) was distributed mainly in the extramacular areas, sparing the areas around the vascular arcades and radially peripapillary capillaries. The APD(PDR) contained retinal neovascularization more frequently than the non-APD(PDR) (P = 0.023). The P ratio was higher in eyes with PDR than in those with NPDR (P < 0.001). The multivariate analysis designated the P ratio (odds ratio, 8.293 × 107; 95% confidence interval, 6.529 × 102–1.053 × 1013; P = 0.002) and the total NPSs (odds ratio, 1.002; 95% confidence interval, 1.001–1.003; P < 0.001) as independent risk factors of PDR. Most eyes with NPDR and 4-2-1 rule findings of DR severity had higher P ratios but not necessarily greater NPS numbers. [Conclusions] The APD(PDR) is uniquely distributed on widefield OCTA images, and the NPA location patterns are associated with DR severity, independent of the entire area of NPAs. [Financial Disclosure(s)] Proprietary or commercial disclosure may be found after the references.
- Published
- 2022
45. Ferulic acid alleviates abnormal behaviors in isolation-reared mice via 5-HT1A receptor partial agonist activity
- Author
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Chihiro Hojo, Hayato Tachioka, Masaaki Omote, Akira Yasubuchi, Marina Ikegaya, Ayami Kita, Takeshi Yabe, Kentaro Kawai, and Ryota Araki
- Subjects
Pharmacology ,Agonist ,medicine.drug_class ,Chemistry ,Receptor antagonist ,Partial agonist ,030227 psychiatry ,03 medical and health sciences ,0302 clinical medicine ,Mechanism of action ,medicine ,5-HT1A receptor ,Serotonin ,medicine.symptom ,Receptor ,030217 neurology & neurosurgery ,5-HT receptor - Abstract
Preclinical and clinical reports suggest that ferulic acid (FA), a plant-derived phenylpropanoid, is effective against mental health problems such as agitation, anxiety, and irritability in humans, without causing adverse side effects. However, the mechanism of action is unknown. The aim of the study is to investigate the mechanism underlying the ameliorative effects of FA on mental health problems such as agitation, anxiety, and irritability, using in vivo behavioral analysis, in vitro pharmacological analysis, and in silico binding analysis. The effects of FA (10 mg/kg, 50 mg/kg, and 250 mg/kg) on hyperactivity and aggressive behaviors of isolation-reared mice were examined. The effects of FA (50 mg/kg and 250 mg/kg) on extracellular levels of monoamines such as serotonin (5-HT), dopamine, and noradrenaline were analyzed by in vivo microdialysis. The effects of FA (10−13–10−6 M) on 5-HT1A and 5-HT2A receptors were analyzed using a luciferase reporter gene assay. Binding of FA to the mouse 5-HT1A receptor was evaluated by in silico analysis. The behavioral analysis showed that administration of FA (50 mg/kg) 1 h before experiments significantly alleviated hyperactivity and aggressive behaviors in isolation-reared mice. These alleviative effects were abolished by pretreatment with the 5-HT1A receptor antagonist WAY-100635 (1 mg/kg). In vivo microdialysis analysis showed that FA (50 mg/kg) did not change extracellular monoamine levels in the prefrontal cortex of mice. The luciferase reporter gene assay indicated that FA activated 5-HT1A receptors, but not 5-HT2A receptors, in a dose-dependent manner. The maximal response of 5-HT1A receptors to FA was weaker than that to 8-hydroxy-2-dipropylaminotetralin (8-OH-DPAT), a 5-HT1A receptor full agonist. In silico binding analysis showed that FA binds to the orthosteric site of 5-HT1A receptors. Taken together, these results suggest that FA ameliorates agitation-, anxiety-, and irritability-like behaviors such as hyperactivity and aggressive behaviors in isolation-reared mice via 5-HT1A receptor partial agonist activity. These findings support the efficacy of FA on mental health problems that have been suggested in preclinical and clinical practice.
- Published
- 2021
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46. Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane
- Author
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Ayaka Kametani, Kentaro Kawai, Atsushi Tarui, Masaaki Omote, Yukiko Karuo, and Kazuyuki Sato
- Subjects
chemistry.chemical_classification ,aryl 1,1-difluoroethyl ether ,Base (chemistry) ,Aryl ,Organic Chemistry ,Combinatorial chemistry ,Full Research Paper ,Catalysis ,halothane ,lcsh:QD241-441 ,chemistry.chemical_compound ,Chemistry ,chemistry ,lcsh:Organic chemistry ,Reagent ,fluorine compound ,medicine ,Phenol ,1,1-difluoroethene ,phenol ,lcsh:Q ,Phenols ,Halothane ,lcsh:Science ,medicine.drug - Abstract
An efficient and convenient method for the synthesis of structurally unique and highly functionalized aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers has been developed. This approach exhibits a broad reaction scope, a simple operation and without the need of any expensive transition-metal catalyst, highly toxic or corrosive reagents. Notably, we demonstrate the potential utility of halothane for the synthesis of aryl gem-difluoroalkyl ethers containing the bromochloromethyl group.
- Published
- 2021
47. Separation of Neighboring Terraces on a Flattened Si(111) Surface by Selective Etching along Step Edges Using Total Wet Chemical Processing
- Author
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Zhida Ma, Seiya Masumoto, Kentaro Kawai, Kazuya Yamamura, and Kenta Arima
- Subjects
Electrochemistry ,General Materials Science ,Surfaces and Interfaces ,Condensed Matter Physics ,Spectroscopy - Abstract
We propose a bottom-up technique using total wet chemical treatments to separate neighboring terraces on Si(111). First, Ag cations were reduced at the step edges of a vicinal Si(111) surface composed of biatomic steps and flat terraces, resulting in self-assembled Ag rows consisting of nanodots and nanowires. By immersing this sample into a mixed solution of HF and H
- Published
- 2022
48. Patterns of mitochondrial and microsatellite DNA markers describe historical and contemporary dynamics of the Humboldt squid Dosidicus gigas in the Eastern Pacific Ocean
- Author
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Ricardo Fujita, Toshie Wakabayashi, Kentaro Kawai, Mitsuo Sakai, Carmen Yamashiro, Tetsuya Umino, and Gustavo Sanchez
- Subjects
0106 biological sciences ,Mitochondrial DNA ,education.field_of_study ,biology ,010604 marine biology & hydrobiology ,Humboldt squid ,Population ,Aquatic Science ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Genetic marker ,Evolutionary biology ,Genetic structure ,Biological dispersal ,Microsatellite ,education ,Southern Hemisphere - Abstract
Dosidicus gigas is an economically important species distributed in the Eastern Pacific Ocean. Unraveling the genetic population structure of this species is crucial to ensure its fishery sustainability and management. Mitochondrial DNA sequences and nuclear neutral loci are useful to understand how historical and contemporary factors drive the genetic population structure of species. However, most studies investigating genetic structuring of D. gigas from its northern and southern populations rely on patterns identified using mitochondrial genes. The use of both types of DNA markers is especially relevant for marine species with high dispersal capabilities such as D. gigas. Here, we describe the genetic structure of D. gigas using partial sequences of the mitochondrial gene NADH dehydrogenase subunit 2 and nuclear microsatellite loci in populations of the northern hemisphere from the Costa Rica Thermal Dome and off Ecuador; and, of the southern hemisphere from the South Equatorial Current and off Peru. Statistical parsimony network and Bayesian analyses from mitochondrial sequences revealed three historical maternal lineages in both hemispheres, with high levels of genetic differentiation and signatures of population expansion during the late Pleistocene. Use of Discriminant Analysis of Principal Component (DAPC) with microsatellite loci of mature and immature individuals showed the presence of at least two contemporary genetic stocks homogeneously co-distributed in both northern and southern hemispheres, which can be explained by the biological characteristics of D. gigas and the variable oceanographic conditions of the Eastern Pacific Ocean. Overall, our findings indicate that cooperation between countries with intensive fishing will benefit the sustainability of D. gigas.
- Published
- 2020
- Full Text
- View/download PDF
49. Estimating the spawning season of black sea bream Acanthopagrus schlegelii in Hiroshima Bay, Japan, from temporal variation in egg density
- Author
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Kentaro Kawai, Tetsuya Umino, Shuichi Furusawa, Hiroki Fujita, and Gustavo Sanchez
- Subjects
0106 biological sciences ,010604 marine biology & hydrobiology ,Effects of global warming on oceans ,Fishing ,Pelagic zone ,04 agricultural and veterinary sciences ,Aquatic Science ,Biology ,01 natural sciences ,DNA barcoding ,Fishery ,Gonadosomatic Index ,040102 fisheries ,0401 agriculture, forestry, and fisheries ,Acanthopagrus schlegeli ,Seawater ,Bay - Abstract
We aimed to determine the spawning period of black sea bream Acanthopagrus schlegelii in Hiroshima Bay, Japan, based on the distribution of its eggs, to assist in the resource management of this species. We developed a monoclonal antibody assay for the identification of black sea bream eggs, and appraised its specificity using immunohistochemical staining and DNA barcoding. To estimate the black sea bream spawning season in 2015 and 2016 in the major fishing ground of Hiroshima Bay, we collected 4061 eggs, attributed to pelagic black sea bream using our assay, and calculated the gonadosomatic index of 715 black sea bream adults to confirm the correspondence between egg presence and spawning season. We estimated that the spawning season of this species extended from mid-April until early July in both 2015 and 2016, and that it peaked in early May, about 20 days earlier than the peak reported for this species in the early 1980s. This temporal shift may be related to increasing seawater temperatures in Hiroshima Bay associated with climate change and ocean warming.
- Published
- 2020
- Full Text
- View/download PDF
50. Synthesis of new fluorescent molecules having an aggregation-induced emission property derived from 4-fluoroisoxazoles
- Author
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Yukiko Karuo, Masaaki Omote, Akira Kawasaki, Atsushi Tarui, Kazuyuki Sato, and Kentaro Kawai
- Subjects
4-fluoroisoxazoles ,Fluorophore ,aggregation-induced emission ,α-fluorinated boron ketoiminates ,Organic Chemistry ,Substituent ,chemistry.chemical_element ,Photochemistry ,Fluorescence ,Full Research Paper ,lcsh:QD241-441 ,chemistry.chemical_compound ,Chemistry ,chemistry ,lcsh:Organic chemistry ,fluorescent probe ,Fluorine ,Molecule ,lcsh:Q ,Isoxazole ,Boron ,Luminescence ,lcsh:Science ,boron ketoiminates - Abstract
Fluorescent molecules based on a fluorinated isoxazole scaffold were synthesized and investigated for their photochemical properties. The introduction of a fluorine substituent into 3,5-diarylisoxazoles led to an increase of fluorescence intensity and exhibited a redshift in the emission intensity. α-Fluorinated boron ketoiminates (F-BKIs) were also synthesized via a ring-opening reaction of 4-fluoroisoxazoles and exhibited highly fluorescent luminescence and aggregation-induced emission (AIE), showing promise as a new fluorophore.
- Published
- 2020
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