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Author Keiji Yamamoto

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Prediction model for hepatocellular carcinoma occurrence in patients with hepatitis C in the era of direct-acting anti-virals.

Yuki Tahata, Ryotaro Sakamori, Ryoko Yamada, Takahiro Kodama, Hayato Hikita, Hideki Hagiwara, Yasuharu Imai, Naoki Hiramatsu, Shinji Tamura, Keiji Yamamoto, Masahide Oshita, Kazuyoshi Ohkawa, Taizo Hijioka, Hiroyuki Fukui, Toshifumi Ito, Yoshinori Doi, Yukinori Yamada, Takayuki Yakushijin, Yuichi Yoshida, Tomohide Tatsumi, Tetsuo Takehara, ,

<h4>Background</h4>Several factors associated with hepatocellular carcinoma (HCC) occurrence after sustained virological response (SVR) in patients with hepatitis C have been reported. However, few validation studies have been performed in the era of direct-acting anti-virals (DAAs).<h4>Aims</h4>To develop a prediction model for HCC occurrence after DAA-mediated SVR and validate its usefulness.<h4>Methods</h4>We analysed ... Read more >>

Aliment Pharmacol Ther (Alimentary pharmacology & therapeutics)
[2021, :]

Cited: 0 times

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A Visual Analytics Framework for Reviewing Multivariate Time-Series Data with Dimensionality Reduction.

Takanori Fujiwara, Shilpika, Naohisa Sakamoto, Jorji Nonaka, Keiji Yamamoto, Kwan-Liu Ma,

Data-driven problem solving in many real-world applications involves analysis of time-dependent multivariate data, for which dimensionality reduction (DR) methods are often used to uncover the intrinsic structure and features of the data. However, DR is usually applied to a subset of data that is either single-time-point multivariate or univariate time-series, ... Read more >>

IEEE Trans Vis Comput Graph (IEEE transactions on visualization and computer graphics)
[2021, 27(2):1601-1611]

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Small-Bowel Lesions in Patients Taking Direct Oral Anticoagulants Detected Using Capsule Endoscopy.

Minoru Yamaoka, Hiroyuki Imaeda, Naoki Hosoe, Kazuaki Yoneno, Ryu Kanno, Takashi Mitsufuji, Takahiro Sasaki, Yuji Akiyama, Hideki Ohgo, Yuichi Morohoshi, Takanori Kanai, Toshimasa Yamamoto, Toshihide Mimura, Haruhiko Ogata, Nobuo Araki, Keiji Yamamoto, Hidetomo Nakamoto,

<h4>Methods</h4>This study was a prospective, open-label, nonblinded, multicenter, and observational study. From September 2013 to March 2017, patients taking DOACs were enrolled. Patients underwent VCE. The type and location of small-bowel lesions were registered. Also, (1) the proportion of lesions detected between types of DOAC was evaluated and (2) the ... Read more >>

Gastroenterol Res Pract (Gastroenterology research and practice)
[2020, 2020:7125642]

Cited: 0 times

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Molecular-level elucidation of saccharin-assisted rapid dissolution and high supersaturation level of drug from Eudragit® E solid dispersion.

Keisuke Ueda, Harunobu Kanaya, Kenjirou Higashi, Keiji Yamamoto, Kunikazu Moribe,

In this work, the effect of saccharin (SAC) addition on the dissolution and supersaturation level of phenytoin (PHT)/Eudragit® E (EUD-E) solid dispersion (SD) at neutral pH was examined. The PHT/EUD-E SD showed a much slower dissolution of PHT compared to the PHT/EUD-E/SAC SD. EUD-E formed a gel layer after the ... Read more >>

Int J Pharm (International journal of pharmaceutics)
[2018, 538(1-2):57-64]

Cited: 0 times

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Recapitulation of Clinical Individual Susceptibility to Drug-Induced QT Prolongation in Healthy Subjects Using iPSC-Derived Cardiomyocytes.

Tadahiro Shinozawa, Koki Nakamura, Masanobu Shoji, Maya Morita, Maya Kimura, Hatsue Furukawa, Hiroki Ueda, Masanari Shiramoto, Kyoko Matsuguma, Yoshikazu Kaji, Ippei Ikushima, Makoto Yono, Shyh-Yuh Liou, Hirofumi Nagai, Atsushi Nakanishi, Keiji Yamamoto, Seigo Izumo,

To predict drug-induced serious adverse events (SAE) in clinical trials, a model using a panel of cells derived from human induced pluripotent stem cells (hiPSCs) of individuals with different susceptibilities could facilitate major advancements in translational research in terms of safety and pharmaco-economics. However, it is unclear whether hiPSC-derived cells ... Read more >>

Stem Cell Reports (Stem cell reports)
[2017, 8(2):226-234]

Cited: 17 times

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Synergetic Role of Hypromellose and Methacrylic Acid Copolymer in the Dissolution Improvement of Amorphous Solid Dispersions.

Naoko Ohyagi, Keisuke Ueda, Kenjirou Higashi, Keiji Yamamoto, Kohsaku Kawakami, Kunikazu Moribe,

Synergetic role of polymer blending on dissolution of amorphous solid dispersion was investigated. Dissolution rates of hypromellose (HPMC) and methacrylic acid copolymer (EUD) from the HPMC/EUD spray-dried sample (SPD) were improved compared to those of each single polymer SPD. Differential scanning calorimetry measurements revealed that the structural change in HPMC ... Read more >>

J Pharm Sci (Journal of pharmaceutical sciences)
[2017, 106(4):1042-1050]

Cited: 3 times

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Molecular-Level Understanding of the Encapsulation and Dissolution of Poorly Water-Soluble Ibuprofen by Functionalized Organic Nanotubes Using Solid-State NMR Spectroscopy.

Nan Liu, Kenjirou Higashi, Junko Kikuchi, Shigeru Ando, Naohiro Kameta, Wuxiao Ding, Mitsutoshi Masuda, Toshimi Shimizu, Keisuke Ueda, Keiji Yamamoto, Kunikazu Moribe,

A comprehensive study of the encapsulation and dissolution of the poorly water-soluble drug ibuprofen (IBU) using two types of organic nanotubes (ONT-1 and ONT-2) was conducted. ONT-1 and ONT-2 had similar inner and outer diameters, but these surfaces were functionalized with different groups. IBU was encapsulated by each ONT via ... Read more >>

J Phys Chem B (The journal of physical chemistry. B)
[2016, 120(19):4496-4507]

Cited: 1 time

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Design of one-dimensional power spectrum using two-dimensional fast Fourier transform for discrimination of paper-based kraft tapes.

Sara Sasaoka, Koichi Saito, Kenjirou Higashi, Waree Limwikrant, Kunikazu Moribe, Shinichi Suzuki, Keiji Yamamoto,

A novel type of spectrum, the one-dimensional power spectrum (1D-PS), was designed for the discrimination of adhesive packing tapes, i.e., kraft tapes. The 1D-PS offered complementary information to that provided by the improved two-dimensional PS (2D-PS), which was calculated using our previously established image processes combined with a two-dimensional fast ... Read more >>

Forensic Sci Int (Forensic science international)
[2015, 257:329-336]

Cited: 1 time

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The effect of drug and EUDRAGIT® S 100 miscibility in solid dispersions on the drug and polymer dissolution rate.

Kenjirou Higashi, Hiroki Hayashi, Keiji Yamamoto, Kunikazu Moribe,

Amorphous solid dispersions of phenytoin (diphenylhydantoin: DPH) and glibenclamide (GBM) with Eudragit(®) S 100 (S100) were prepared by a spray-drying. At low drug loading ratios, DPH dissolved simultaneously with S100. However, at high drug loading ratios the DPH dissolution rates were significantly reduced in comparison with those of S100 because ... Read more >>

Int J Pharm (International journal of pharmaceutics)
[2015, 494(1):9-16]

Cited: 10 times

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Mechanistic insight into the dramatic improvement of probucol dissolution in neutral solutions by solid dispersion in Eudragit E PO with saccharin.

Kenjirou Higashi, Atsunori Seo, Kiichi Egami, Naoya Otsuka, Waree Limwikrant, Keiji Yamamoto, Kunikazu Moribe,

<h4>Objectives</h4>Solid dispersion using Eudragit E PO (EPO) improves the dissolution of poorly water-soluble drugs in acidic solutions; however, the dissolution extremely decreases in neutral solutions. In this report, ternary solid dispersions containing probucol (PBC), EPO, and saccharin (SAC) were prepared to enable high drug dissolution at neutral pH.<h4>Methods</h4>Cryogenic-grinding was used ... Read more >>

J Pharm Pharmacol (The Journal of pharmacy and pharmacology)
[2016, 68(5):655-664]

Cited: 1 time

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Equilibrium state at supersaturated drug concentration achieved by hydroxypropyl methylcellulose acetate succinate: molecular characterization using (1)H NMR technique.

Keisuke Ueda, Kenjirou Higashi, Keiji Yamamoto, Kunikazu Moribe,

The maintenance mechanism of the supersaturated state of poorly water-soluble drugs, glibenclamide (GLB) and chlorthalidone (CLT), in hydroxypropyl methylcellulose acetate succinate (HPMC-AS) solution was investigated at a molecular level. HPMC-AS suppressed drug crystallization from supersaturated drug solution and maintained high supersaturated level of drugs with small amount of HPMC-AS for ... Read more >>

Mol Pharm (Molecular pharmaceutics)
[2015, 12(4):1096-1104]

Cited: 3 times

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An Insight into Different Stabilization Mechanisms of Phenytoin Derivatives Supersaturation by HPMC and PVP.

Naoya Otsuka, Keisuke Ueda, Naoko Ohyagi, Kozue Shimizu, Kazuaki Katakawa, Takuya Kumamoto, Kenjirou Higashi, Keiji Yamamoto, Kunikazu Moribe,

In this study, we examined the stabilization mechanism of drug supersaturation by hypromellose (HPMC) and polyvinylpirrolidone (PVP). The poorly water-soluble drugs, phenytoin (diphenylhydantoin, DPH), and its synthesized derivatives monomethylphenytoin (MDPH) and dimethylphenytoin (DMDPH) were used. DPH supersaturation was efficiently maintained by both HPMC and PVP. HPMC maintained the supersaturation of ... Read more >>

J Pharm Sci (Journal of pharmaceutical sciences)
[2015, 104(8):2574-2582]

Cited: 6 times

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In situ molecular elucidation of drug supersaturation achieved by nano-sizing and amorphization of poorly water-soluble drug.

Keisuke Ueda, Kenjirou Higashi, Keiji Yamamoto, Kunikazu Moribe,

Quantitative evaluation of drug supersaturation and nanoparticle formation was conducted using in situ evaluation techniques, including nuclear magnetic resonance (NMR) spectroscopy. We prepared a ternary complex of carbamazepine (CBZ) with hydroxypropyl methylcellulose (HPMC) and sodium dodecyl sulfate (SDS) to improve the drug concentration. Different preparation methods, including grinding and spray ... Read more >>

Eur J Pharm Sci (European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences)
[2015, 77:79-89]

Cited: 7 times

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Direct evaluation of molecular States of piroxicam/poloxamer nanosuspension by suspended-state NMR and Raman spectroscopies.

Yuki Hasegawa, Kenjirou Higashi, Keiji Yamamoto, Kunikazu Moribe,

A nanosuspension of piroxicam (PXC) and poloxamer 407 (poloxamer) prepared by the wet milling method was directly evaluated at the molecular level from the viewpoint of both solution and solid phases. (13)C solution-state NMR measurements revealed a reduction in the concentration of dissolved poloxamer in the nanosuspension. Furthermore, the fraction ... Read more >>

Mol Pharm (Molecular pharmaceutics)
[2015, 12(5):1564-1572]

Cited: 4 times

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Pyogenic granuloma of the ileum diagnosed by double-balloon enteroscopy.

Azusa Kikuchi, Tomohisa Sujino, Minoru Yamaoka, Kazuaki Yoneno, Hideki Ohgo, Makoto Takagi, Shingo Morioka, Eiji Hirooka, Keiji Yamamoto, Nozomi Shinozuka, Taku Honma, Hidekazu Kayano, Hidetomo Nakamoto, Hiroyuki Imaeda,

A pyogenic granuloma (PG) is a capillary hemangioma that usually occurs on the skin or in the oral cavity; it is rarely observed in the gastrointestinal tract. We herein describe a case of a 86-year-old woman who presented with anemia. Esophagogastroduodenoscopy and colonoscopy did not reveal any significant bleeding focus, ... Read more >>

Intern Med (Internal medicine (Tokyo, Japan))
[2014, 53(18):2057-2059]

Cited: 4 times

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Inhibition mechanism of hydroxypropyl methylcellulose acetate succinate on drug crystallization in gastrointestinal fluid and drug permeability from a supersaturated solution.

Keisuke Ueda, Kenjirou Higashi, Makoto Kataoka, Shinji Yamashita, Keiji Yamamoto, Kunikazu Moribe,

The effects of drug-crystallization inhibitor in bile acid/lipid micelles solution on drug permeation was evaluated during the drug crystallization process. Hydroxypropyl methylcellulose acetate succinate (HPMC-AS) was used as a drug-crystallization inhibitor, which efficiently suppressed dexamethasone (DEX) crystallization in a gastrointestinal fluid model containing sodium taurocholate (NaTC) and egg-phosphatidylcholine (egg-PC). Changes ... Read more >>

Eur J Pharm Sci (European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences)
[2014, 62:293-300]

Cited: 7 times

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Encapsulation of poorly water-soluble drugs into organic nanotubes for improving drug dissolution.

Kunikazu Moribe, Takashi Makishima, Kenjirou Higashi, Nan Liu, Waree Limwikrant, Wuxiao Ding, Mitsutoshi Masuda, Toshimi Shimizu, Keiji Yamamoto,

Hydrocortisone (HC), a poorly water-soluble drug, was encapsulated within organic nanotubes (ONTs), which were formed via the self-assembly of N-{12-[(2-α,β-d-glucopyranosyl) carbamoyl]dodecanyl}-glycylglycylglycine acid. The stability of the ONTs was evaluated in ten organic solvents, of differing polarities, by field emission transmission electron microscopy. The ONTs maintained their stable tubular structure in ... Read more >>

Int J Pharm (International journal of pharmaceutics)
[2014, 469(1):190-196]

Cited: 3 times

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Insights into atomic-level interaction between mefenamic acid and eudragit EPO in a supersaturated solution by high-resolution magic-angle spinning NMR spectroscopy.

Kenjirou Higashi, Kazutoshi Yamamoto, Manoj Kumar Pandey, Kamal H Mroue, Kunikazu Moribe, Keiji Yamamoto, Ayyalusamy Ramamoorthy,

The intermolecular interaction between mefenamic acid (MFA), a poorly water-soluble nonsteroidal anti-inflammatory drug, and Eudragit EPO (EPO), a water-soluble polymer, is investigated in their supersaturated solution using high-resolution magic-angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy. The stable supersaturated solution with a high MFA concentration of 3.0 mg/mL is prepared ... Read more >>

Mol Pharm (Molecular pharmaceutics)
[2014, 11(1):351-357]

Cited: 10 times

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The effect of HPMCAS functional groups on drug crystallization from the supersaturated state and dissolution improvement.

Keisuke Ueda, Kenjirou Higashi, Keiji Yamamoto, Kunikazu Moribe,

The inhibitory effect on drug crystallization in aqueous solution was evaluated using various forms of hydroxypropyl methylcellulose acetate succinate (HPMCAS). HPMCAS suppressed crystallization of carbamazepine (CBZ), nifedipine (NIF), mefenamic acid, and dexamethasone. The inhibition of drug crystallization mainly derived from molecular level hydrophobic interactions between the drug and HPMCAS. HPMCAS ... Read more >>

Int J Pharm (International journal of pharmaceutics)
[2014, 464(1-2):205-213]

Cited: 20 times

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Four new polymorphic forms of suplatast tosilate.

Keiko Nagai, Takanori Ushio, Hidenori Miura, Takashi Nakamura, Kunikazu Moribe, Keiji Yamamoto,

We found four new polymorphic forms (γ-, ε-, ζ-, and η-forms) of suplatast tosilate (ST) by recrystallization and seeding with ST-analogous compounds; three polymorphic forms (α-, β-, and δ-forms) of ST have been previously reported. The physicochemical properties of these new forms were investigated using infrared (IR) spectroscopy, solid-state nuclear ... Read more >>

Int J Pharm (International journal of pharmaceutics)
[2014, 460(1-2):83-91]

Cited: 2 times

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Inhibitory effect of hydroxypropyl methylcellulose acetate succinate on drug recrystallization from a supersaturated solution assessed using nuclear magnetic resonance measurements.

Keisuke Ueda, Kenjirou Higashi, Keiji Yamamoto, Kunikazu Moribe,

We examined the inhibitory effect of hydroxypropyl methylcellulose acetate succinate (HPMC-AS) on drug recrystallization from a supersaturated solution using carbamazepine (CBZ) and phenytoin (PHT) as model drugs. HPMC-AS HF grade (HF) inhibited the recrystallization of CBZ more strongly than that by HPMC-AS LF grade (LF). 1D-1H NMR measurements showed that ... Read more >>

Mol Pharm (Molecular pharmaceutics)
[2013, 10(10):3801-3811]

Cited: 25 times

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Risk factor profiles, drug usage, and prevalence of aspirin-associated gastroduodenal injuries among high-risk cardiovascular Japanese patients: the results from the MAGIC study.

Naomi Uemura, Kentaro Sugano, Hideyuki Hiraishi, Kazuyuki Shimada, Shinya Goto, Shinichiro Uchiyama, Yasushi Okada, Hideki Origasa, Yasuo Ikeda, ,

<h4>Background</h4>Low-dose aspirin is widely used for the prevention of cardiovascular events. The prevalence of gastroduodenal injuries and the risk factor profile including gastroprotective drug therapy needs to be clarified in Japanese patients taking daily aspirin for cardioprotection.<h4>Methods</h4>This Management of Aspirin-induced Gastro-Intestinal Complications (MAGIC) study was conducted with a prospective nationwide, ... Read more >>

J Gastroenterol (Journal of gastroenterology)
[2014, 49(5):814-824]

Cited: 25 times

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Characterization of cromolyn sodium hydrates and its formulation by (23) Na-multiquantum and magic-angle spinning nuclear magnetic resonance spectroscopy.

Makoto Umino, Kenjirou Higashi, Hyuma Masu, Waree Limwikrant, Keiji Yamamoto, Kunikazu Moribe,

We characterized cromolyn sodium (CS) hydrates and evaluated their molecular states in low-dose formulations using Na-multiquantum magic-angle spinning (MQMAS) nuclear magnetic resonance (NMR) analysis. Two CS hydrates, low-water-content hydrated form and high-water-content hydrated form containing 2-3 and 5-6 hydrates, respectively, were prepared by humidification. Single-crystal X-ray diffraction and powder X-ray ... Read more >>

J Pharm Sci (Journal of pharmaceutical sciences)
[2013, 102(8):2738-2747]

Cited: 0 times

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Novel image analysis method using ultrasound elastography for noninvasive evaluation of hepatic fibrosis in patients with chronic hepatitis C.

Kenji Fujimoto, Michio Kato, Masatoshi Kudo, Norihisa Yada, Tsuyoshi Shiina, Kazuomi Ueshima, Yukinori Yamada, Tetsushi Ishida, Masayoshi Azuma, Masaru Yamasaki, Keiji Yamamoto, Norio Hayashi, Tetsuo Takehara,

It has been established that the long-term infection of chronic hepatitis C leads to the increased risk of hepatic fibrosis and hepatocellular carcinoma. Currently, histological diagnosis by invasive and painful liver biopsy is the gold standard for evaluating the hepatic fibrosis stage. Because of a side effect or patient inability ... Read more >>

Oncology (Oncology)
[2013, 84 Suppl 1:3-12]

Cited: 28 times

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Ghrelin counteracts salt-induced hypertension via promoting diuresis and renal nitric oxide production in Dahl rats.

Hirotaka Aoki, Masanori Nakata, Katsuya Dezaki, Ming Lu, Darambazar Gantulga, Keiji Yamamoto, Kazuyuki Shimada, Kazuomi Kario, Toshihiko Yada,

Ghrelin is the endogenous ligand for the growth hormone-secretagogue receptor expressed in various tissues including the heart, blood vessels and kidney. This study sought to determine the effects of long-term treatment with ghrelin (10 nmol/kg, twice a day, intraperitoneally) on the hypertension induced by high salt (8.0% NaCl) diet in ... Read more >>

Endocr J (Endocrine journal)
[2013, 60(5):571-581]

Cited: 11 times

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