Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Ken-ichi Yamada Last modified date:2020.07.01

Professor / Division of Molecular Bioinformatics / Department of Chemo-Pharmaceutical Sciences / Faculty of Pharmaceutical Sciences

1. Tomonori Tadokoro,1 Masataka Ikeda,1 Tomomi Ide,2 Hiroko Deguchi,1 Soichiro Ikeda,1 Kosuke Okabe,1 Akihito Ishikita,1 Shouji Matsushima,3 Tomoko Koumura,4 Ken-ichi Yamada,5 Hirotaka Imai,4 and Hiroyuki Tsutsui1, Mitochondria-dependent ferroptosis plays a pivotal role in doxorubicin cardiotoxicity. , JCI Insight. , 10.1172/jci.insight.132747, 249, 2020.05, Doxorubicin (DOX), a chemotherapeutic agent, induces a cardiotoxicity referred to as doxorubicin-induced cardiomyopathy (DIC). This cardiotoxicity often limits chemotherapy for malignancies and is associated with poor prognosis. However, the molecular mechanism underlying this cardiotoxicity is yet to be fully elucidated. Here, we show that DOX downregulated glutathione peroxidase 4 (GPx4) and induced excessive lipid peroxidation through DOX-Fe2+ complex in mitochondria, leading to mitochondria-dependent ferroptosis; we also show that mitochondria-dependent ferroptosis is a major cause of DOX cardiotoxicity. In DIC mice, the left ventricular ejection fraction was significantly impaired, and fibrosis and TUNEL+ cells were induced at day 14. Additionally, GPx4, an endogenous regulator of ferroptosis, was downregulated, accompanied by the accumulation of lipid peroxides, especially in mitochondria. These cardiac impairments were ameliorated in GPx4 Tg mice and exacerbated in GPx4 heterodeletion mice. In cultured cardiomyocytes, GPx4 overexpression or iron chelation targeting Fe2+ in mitochondria prevented DOX-induced ferroptosis, demonstrating that DOX triggered ferroptosis in mitochondria. Furthermore, concomitant inhibition of ferroptosis and apoptosis with ferrostatin-1 and zVAD-FMK fully prevented DOX-induced cardiomyocyte death. Our findings suggest that mitochondria-dependent ferroptosis plays a key role in progression of DIC and that ferroptosis is the major form of regulated cell death in DOX cardiotoxicity..
2. Miku Takahashi, Takujiro Homma, Ken ichi Yamada, Satoshi Miyata, Osamu Nakajima, Junichi Fujii, Genetic ablation of aldehyde reductase (Akr1a) augments exercise endurance in mice via activation of the PGC-1α-involved pathway, Life Sciences, 10.1016/j.lfs.2020.117501, 249, 2020.05, Aims: Aldehyde reductase (AKR1A) is involved in the synthesis of ascorbic acid (AsA) as well as the detoxification of aldehydes. AKR1A−/− (KO) mice produce about 10% of the normal amounts of AsA compared to AKR1A+/+ (WT) mice. We investigated physiologic roles of AKR1A in running using the KO mice. Main methods: The KO mice were subjected to a treadmill test under either restricted AsA production or a sufficiency by supplementation and compared the results with those of WT mice. Contents of glucose, aspartate aminotransferase, AsA and free fatty acids in blood were measured. Glycogen contents were measured in the liver and skeletal muscle, and hepatic proteins were examined by immunoblot analyses. Key findings: Running performance was higher in the KO mice than the WT mice irrespective of the AsA status. After the exercise period, blood glucose levels were decreased in the WT mice but were preserved in the KO mice. Liver glycogen levels were also consistently preserved in the KO mice after exercise. Free fatty acid levels tended to be originally high in blood plasma compared to those of the WT mice and were increased to similar extent in them. A key regulator of energy metabolism, PGC-1α, and the products of downstream target genes that encode for glyceraldehyde-3-phosphate dehydrogenase and glucose-6-phosphatase, were constitutively at high levels in the KO mice. Significance: The genetic ablation of AKR1A activates the PGC-1α pathway and spare glucose, which would consequently confer exercise endurance..
3. Kota Saito, Yuta Matsuoka, Ken-ichi Yamada, Reaction targets of antioxidants in azo-initiator or lipid hydroperoxide induced lipid peroxidation, Free Radic Res., , 2020.04, Lipid peroxidation (LPO) is reported to be involved in the pathogenesis of several oxidative diseases, and several therapeutic approaches using antioxidants have been proposed. LPO is thought to progress via a complicated series of multistep reactions suggesting that the activity of each antioxidant may be different, and depends on the reacting molecules. Hence, in this study, we evaluated the inhibitory mechanisms of several antioxidants toward arachidonic acid (AA) peroxidation induced by the azo initiator 2,2’-azobis(2-amidinopropane) dihydrochloride (AAPH) or a lipid hydroperoxide, hydroperoxyoctadecadienoic acid (HpODE)/hemin. Edaravone, ferrostatin-1, TEMPO and trolox effectively inhibited the production of malondialdehyde (MDA) and several oxidised AAs generated in the AAPH-induced LPO because of their scavenging ability toward lipid peroxyl radicals. In contrast, ebselen and ferrostatin-1 showed strong antioxidative activity in the HpODE/hemin-induced peroxidation. Under this condition, ebselen and ferrostatin-1 were thought to reduce HpODE and its derived alkoxyl radicals to the corresponding lipid alcohols. In conclusion, we found that each antioxidant had different antioxidative activities that prevented the progression of LPO. We expect that these findings will contribute to the design of novel therapeutic strategies using an appropriate antioxidant targeted to each step of the development of oxidative stress diseases..
4. Yuta Matsuoka, Yoshihiro Izumi, Masatomo Takahashi Takeshi Bamba Ken-ichi Yamada, Method for Structural Determination of Lipid-Derived Radicals, 10.1021/acs.analchem.0c00053, 2020.04, Diversified oxidized-lipid molecules are responsible for inflammation and cell death, including ferroptosis. Lipid radicals are the source of these oxidized lipids, which are the initial key molecules in the lipid peroxidation chain reaction. However, owing to their extremely high reactivity and short half-life, an established detection technique is not available. Here, we propose a high-performance liquid chromatography fluorometry and high-resolution tandem mass spectrometry system combined with a fluorescent probe as a structural analysis method for lipid-derived radicals. We detected 132 lipid-derived radicals, including 111 new species, from five polyunsaturated fatty acids. In addition, a database was constructed for which the initial fatty acid could be determined using the radical structure. Further, 12 endogenous lipid-derived radicals were identified in carcinogen-induced liver cancer mouse models. Therefore, this method and its corresponding database will provide novel insights into mechanisms underlying the lipid peroxidation, including the associated inflammation and ferroptosis..
5. Ryoma Shiraishi, Tomoyo Kaneko, Kazuteru Usui, Tatsuya Naganuma, Naoko Iizuka, Kosuke Morishita, Shigeki Kobayashi, Yasufumi Fuchi, Yuta Matsuoka, Go Hirai, Ken-Ichi Yamada, Satoru Karasawa, Effects of Substituents on the Properties of Metal-Free MRI Contrast Agents, ACS Omega, 10.1021/acsomega.9b03003, 4, 24, 20715-20723, 2019.12, Materials possessing electron spin can shorten the T1 relaxation times in magnetic resonance imaging (MRI). For example, gadolinium (Gd) complexes with seven f-orbital electrons are widely used as contrast agents in clinical applications. However, Gd has severe potential side effects, and thus metal-free alternatives are needed. Toward this end, we synthesized seven NO radicals consisting of a dioxa-azaspiro[4.5]decane framework having various substituents, DAD-X (X = methyl, ethyl, n-propyl, c-propyl, vinyl, phenyl, and 2-pyridyl), that functioned as metal-free MRI contrast agents. The relationship between (i) water-proton relaxivity and log※P and (ii) reactivity for ascorbic acid and the spin density of the NO oxygen atom were established, which provided a basis for the rational design of practical metal-free contrast agents..
6. @Noppawan Phumala Morales, @Pacharaporn Chunephisal, @Jindaporn Janprasit, #Yuma Ishida, @Rataya Leuchapudiporn、@Ken-Ichi Yamada, Kinetics and localization of hemin-induced lipoprotein oxidation, Free Radical Research, 10.1080/10715762.2019.1660323 , 2019.08.
7. Ishii N, Homma T, Lee J, Mitsuhashi H, Yamada KI, Kimura N, Yamamoto Y, Fujii J. , Ascorbic acid and CoQ10 ameliorate the reproductive ability of SOD1-deficient female mice., Biol Reprod. , 10.1093/biolre/ioz149. , 149, 1-14, 2019.08, Superoxide dismutase 1 (SOD1) suppresses oxidative stress within cells by decreasing the levels of superoxide anions. A dysfunction of the ovary and/or an aberrant production of sex hormones are suspected causes for infertility in SOD1-knockout (KO) mice. We report on attempts to rescue the infertility in female KO mice by providing two antioxidants, ascorbic acid (AsA) and/or coenzyme Q10 (CoQ10), as supplements in the drinking water of the KO mice after weaning and on an investigation of their reproductive ability. On the first parturition, 80% of the untreated KO mice produced smaller litter sizes compared to wild-type mice (average 2.8 vs 7.3 pups/mouse), and supplementing with these antioxidants failed to improve these litter sizes. However, in the second parturition of the KO mice, the parturition rate was increased from 18% to 44-75% as the result of the administration of antioxidants. While plasma levels of progesterone at 7.5 days of pregnancy were essentially the same between the WT and KO mice and were not changed by supplementation of these antioxidants, sizes of corpus luteum cells, which were smaller in the KO mouse ovaries after the first parturition, were significantly ameliorated in the KO mouse with the administration of the antioxidants. Moreover, the impaired vasculogenesis in uterus/placenta was also improved by AsA supplementation. We thus conclude that AsA and/or CoQ10 are involved in maintaining ovarian and uterus/placenta homeostasis against insults that are augmented during pregnancy and that their use might have positive effects in terms of improving female fertility..
8. Mizuki Nakamura, Toshihide Yamasaki, Megumi Ueno, Sayaka Shibata, Yoshikazu Ozawa, Tadashi Kamada, Ikuo Nakanishi, Ken-Ichi Yamada, Ichio Aoki, Ken ichiro Matsumoto, Radiation-induced redox alteration in the mouse brain, Free Radical Biology and Medicine, 10.1016/j.freeradbiomed.2019.08.020, 143, 412-421, 2019.11, Time courses of the redox status in the brains of mice after X-ray or carbon-ion beam irradiation were observed by magnetic resonance redox imaging (MRRI). The relationship between radiation-induced oxidative stress on the cerebral nervous system and the redox status in the brain was discussed. The mice were irradiated by 8-Gy X-ray or carbon-ion beam (C-beam) on their head under anesthesia. C-beam irradiation was performed at HIMAC (Heavy-Ion Medical Accelerator in Chiba, NIRS/QST, Chiba, Japan). MRRI measurements using a blood-brain-barrier-permeable nitroxyl contrast agent, MCP or TEMPOL, were performed using 7-T scanner at several different times, i.e., 5–10 h, 1, 2, 4, and 8 day(s) after irradiation. Decay rates of the nitroxyl-enhanced T1-weighted MR signals in the brains were estimated from MRRI data sets, and variation in the decay rates after irradiation was assessed. The variation in decay rates of MCP and TEMPOL after X-ray or C-beam irradiation was similar, but different variation patterns were observed between X-ray and C-beam. The apparent decay rate of both MCP and TEMPOL decreased due to the temporal reduction of blood flow in the brain several hours after X-ray and/or C-beam irradiation. After decreasing, the apparent decay rates of nitroxyl radicals in the brain gradually increased during the following days after X-ray irradiation or rapidly increased 1 day after C-beam irradiation. The sequential increase in nitroxyl decay rates may have been due to the oxidative atmosphere in the tissue due to ROS generation. X-ray and C-beam irradiation resulted in different redox responses, which may have been due to time-varying oxidative stress/injury, in the mouse brain. The C-beam irradiation effects were more acute and larger than those of X-ray irradiation..
9. Kurihara,K, Homma T, Kobayashi S, Shichiri M, Fujiwara H, Fujii S, Yamada KI, Nakane M, Kawamae K, Fujii J., Ascorbic acid insufficiency impairs spatial memory formation in juvenile AKR1A-knockout mice., J Clin Biochem Nutr, 10.3164/jcbn.19-41, 65, 2, 1-8, 2019.08.
10. Ihara H, Kakihana Y, Yamakage A, Kai K, Shibata T, Nishida M, Yamada KI, Uchida K., 2-Oxo-histidine-containing dipeptides are functional oxidation products., J Biol Chem., 10.1074/jbc.RA118.006111. , 25, 294(4), 1279-1289, 2019.01, midazole-containing dipeptides (IDPs), such as carnosine and anserine, are found exclusively in various animal tissues, especially in the skeletal muscles and nerves. IDPs have antioxidant activity because of their metal-chelating and free radical-scavenging properties. However, the underlying mechanisms that would fully explain IDP antioxidant effects remain obscure. Here, using HPLC-electrospray ionization-tandem MS analyses, we comprehensively investigated carnosine and its related small peptides in the soluble fractions of mouse tissue homogenates and ubiquitously detected 2-oxo-histidine-containing dipeptides (2-oxo-IDPs) in all examined tissues. We noted enhanced production of the 2-oxo-IDPs in the brain of a mouse model of sepsis-associated encephalopathy. Moreover, in SH-SY5Y human neuroblastoma cells stably expressing carnosine synthase, H2O2 exposure resulted in the intracellular production of 2-oxo-carnosine, which was associated with significant inhibition of the H2O2 cytotoxicity. Notably, 2-oxo-carnosine showed a better antioxidant activity than endogenous antioxidants such as GSH and ascorbate. Mechanistic studies indicated that carnosine monooxygenation is mediated through the formation of a histidyl-imidazole radical, followed by the addition of molecular oxygen. Our findings reveal that 2-oxo-IDPs are metal-catalyzed oxidation products present in vivo and provide a revised paradigm for understanding the antioxidant effects of the IDPs..
11. Emoto MC, Sato-Akaba H, Matsuoka Y, Yamada KI, Fujii HG., Non-invasive mapping of glutathione levels in mouse brains by in vivo electron paramagnetic resonance (EPR) imaging: Applied to a kindling mouse model., Neuroscience Letters, 10.1016/j.neulet.2018.10.001. , 690, 6-10, 2018.10, [URL], Glutathione (GSH) is an important antioxidant that can protect cells under oxidative stress. Thus, a non-invasive method to measure and map the distribution of GSH in live animals is needed. To image the distribution of GSH levels in specific brain regions, a new method using electron paramagnetic resonance (EPR) imaging with a nitroxide imaging probe was developed. Pixel-based mapping of brain GSH levels was successfully obtained by using the linear relationship between reduction rates for nitroxides in brains, measured by an in vivo EPR imager, and brain GSH levels, measured by an in vitro biochemical assay. The newly developed method was applied to a kindling mouse model induced with pentylenetetrazole (PTZ) to visualize changes in GSH levels in specific brain regions after seizure. The obtained map of brain GSH levels clearly indicated decreased GSH levels around the hippocampal region compared to control mice..
12. Takeru Araki, Yasufumi Fuchi, Shuhei Murayama, Ryoma Shiraishi, Tokimi Oyama, Mariko Aso, Ichio Aoki, Shigeki Kobayashi, Ken-Ichi Yamada, Satoru Karasawa, Fluorescence tumor-imaging using a thermo-responsive molecule with an emissive aminoquinoline derivative, Nanomaterials, 10.3390/nano8100782, 8, 10, 2018.10, We synthesized (2,4-trifluoromethyl-7-N-bis(2,5,8,11-tetraoxatridecane-13-yl)-aminoquinoline) TFMAQ-diEg4, an emissive aminoquinoline derivative that incorporated two tetraethyleneglycol chains into an amino group. TFMAQ-diEg4 showed fluorescence and thermo-responsive properties accompanied by a lower critical solution temperature (LCST), due to the introduction of the oligoethylene glycol chain. This thermo-responsive LCST behavior occurred at the border of a cloud point. Below and above the cloud point, self-assemblies of 6-7-nm nanoparticles and ~2000-nm microparticles were observed, in vitro. In addition, TFMAQ-diEg4 showed a high solubility, over 20 mM for aqueous solution, in vivo, which not only prevented thrombosis but also allowed various examinations, such as single intravenous administration and intravenous drips. Intravenous administration of TFMAQ-diEg4, to tumor-bearing, mice led to the accumulation of the molecule in the tumor tissue, as observed by fluorescence imaging. A subset of mice was treated with local heat around their tumor tissue and an intravenous drip of TFMAQ-diEg4, which led to a high intensity of TFMAQ-diEg4 emission within the tumor tissue. Therefore, we revealed that TFMAQ-diEg4 was useful as a fluorescence probe with thermo-responsive properties..
13. Takujiro Homma, Takaya Shirato, Ryusuke Akihara, Sho Kobayashi, Jaeyong Lee, Ken-Ichi Yamada, Satoshi Miyata, Motoko Takahashi, Junichi Fujii, Mice deficient in aldo-keto reductase 1a (Akr1a) are resistant to thioacetamide-induced liver injury, Toxicology Letters, 10.1016/j.toxlet.2018.05.015, 294, 37-43, 2018.09, Aldehyde reductase (Akr1a) has been reported to be involved in detoxification of reactive aldehydes as well as in the synthesis of bioactive compounds such as ascorbic acid (AsA). Because Akr1a is expressed at high levels in the liver and is involved in xenobiotic metabolism, our objective was to investigate the hepato-protective role of Akr1a in a thioacetamide (TAA)-induced hepatotoxicity model using Akr1a-deficient (Akr1a−/−) mice. Wild-type (WT) and Akr1a−/− mice were injected intraperitoneally with TAA and the extent of liver injury in the acute phase was assessed. Intriguingly, the extent of TAA-induced liver damage was less in the Akr1a−/− mice than in the WT mice. Biomarkers for the ER stress-induced apoptosis pathway were markedly decreased in the livers of Akr1a−/− mice, whereas AsA levels in plasma did not change significantly in any of the mice. In the liver, TAA is converted to reactive metabolites such as TAA S-oxide and then to TAA S, S-dioxide via the action of CYP2E1. In Akr1a−/− mice, CYP2E1 activity was relatively lower than WT mice at the basal level, leading to reactive TAA metabolites being produced at lower levels after the TAA treatment. The levels of liver proteins that were modified with these metabolites were also lower in the Akr1a−/− mice than the WT mice after the TAA treatment. Furthermore, after a lethal dose of a TAA challenge, the WT mice all died within 36 h, whereas almost all of the Akr1a−/− mice survived. These collective results suggest that Akr1a−/− mice are resistant to TAA-induced liver injury, and it follows that the absence of Akr1a might modulate TAA bioactivation..
14. Atsushi Fujita, hiroo yamaguchi, Ryo Yamasaki, Yiwen Cui, Yuta Matsuoka, Ken-Ichi Yamada, Jun-Ichi Kira, Connexin 30 deficiency attenuates A2 astrocyte responses and induces severe neurodegeneration in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride Parkinson's disease animal model, Journal of Neuroinflammation, 10.1186/s12974-018-1251-0, 15, 1, 2018.08, Background: The first pathology observed in Parkinson's disease (PD) is 'dying back' of striatal dopaminergic (DA) terminals. Connexin (Cx)30, an astrocytic gap junction protein, is upregulated in the striatum in PD, but its roles in neurodegeneration remain elusive. We investigated Cx30 function in an acute PD model by administering 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to wild-type (WT) and Cx30 knockout (KO) mice. Methods: On days 1 and 7 after MPTP administration, we evaluated changes in astrocytic Cx30, Cx43, glial fibrillary acidic protein, and ionised calcium-binding adapter molecule 1 expression by immunostaining and biochemical analysis. Loss of DA neurons was evaluated by tyrosine hydroxylase immunostaining. Gene expression was analysed using A1, A2, pan-reactive astrocyte microarray gene sets, and M1, M2, and M1/M2 mixed microglial microarray gene sets. Real-time PCR and in situ hybridisation were performed to evaluate glial cell-derived neurotrophic factor (Gdnf) and S100a10 expression. Striatal GDNF protein levels were determined by enzyme-linked immunosorbent assay. Results: MPTP treatment induced upregulation of Cx30 and Cx43 levels in the striatum of WT and KO mice. DA neuron loss was accelerated in Cx30 KO compared with WT mice after MPTP administration, despite no change in the striatal concentration of methyl-4-phenylpyridinium+. Astrogliosis in the striatum of Cx30 KO mice was attenuated by MPTP, whereas microglial activation was unaffected. Microarrays of the striatum showed reduced expression of pan-reactive and A2 astrocyte genes after MPTP treatment in Cx30 KO compared with WT mice, while M1, M2, and M1/M2 mixed microglial gene expression did not change. MPTP reduced the number of striatal astrocytes co-expressing Gdnf mRNA and S100β protein or S100a10 mRNA and S100β protein and also reduced the level of GDNF in the striatum of Cx30 KO compared with WT mice. Conclusions: These findings indicate that Cx30 plays critical roles in astrocyte neuroprotection in an MPTP PD model..
15. Toshikazu Nakamura, Tadaaki Ikoma, Ken-Ichi Yamada, Recent Developments in Electron Spin Science and Technology in Japan, Applied Magnetic Resonance, 10.1007/s00723-018-1035-9, 49, 8, 755-756, 2018.08.
16. Yasukawa K, Shigemi R, Kanbe T, Mutsumoto Y, Oda F, Ichikawa K, Yamada KI, Tun X, Utsumi H., In Vivo Imaging of the Intra- and Extracellular Redox Status in Rat Stomach with Indomethacin-Induced Gastric Ulcers Using Overhauser-Enhanced Magnetic Resonance Imaging., 10.1089/ars.2017.7336., 2018.05, Repeated use of nonsteroidal anti-inflammatory drugs can induce changes in the redox status, including production of reactive oxygen species (ROS), but the specific details of these changes remain unknown. Overhauser-enhanced magnetic resonance imaging (OMRI) has been used in vivo to monitor the redox status in several diseases and map tissue oxygen concentrations. We monitored the intra- and extracellular redox status in the stomach of rats with indomethacin-induced gastric ulcers using OMRI and investigated the relationship with gastric mucosal damage..
17. Kumiko Yamamoto, Hironobu Yasui, Tomoki Bo, Tohru Yamamori, Wakako Hiraoka, Toshihide Yamasaki, Ken-Ichi Yamada, Osamu Inanami, Genotoxic Responses of Mitochondrial Oxygen Consumption Rate and Mitochondrial Semiquinone Radicals in Tumor Cells, Applied Magnetic Resonance, 10.1007/s00723-018-1007-0, 1-15, 2018.04, Our recent report demonstrated that genotoxic stimuli enhance mitochondrial energy metabolism in various tumor cell lines. However, the mitochondrial response against genotoxic stimuli has not been fully elucidated. In this study, to investigate mitochondrial functions in X-irradiated cells, the oxygen consumption rate (OCR) in human cervical adenocarcinoma HeLa cells was examined by electron spin resonance (ESR) spectroscopy with lithium 5,9,14,18,23,27,32,36-octa-n-butoxy-2,3-naphthalocyanine. ESR oximetry demonstrated that basal respiration, ATP-linked respiration, proton leak, maximal respiration, and reserve capacity increased in HeLa cells 24 h after X-irradiation. However, a flow cytometric analysis using MitoTracker Green showed that mitochondrial mass also increased following X-irradiation. When the OCR was standardized to the mitochondria membrane mass, the radiation-induced increases in the respiratory parameters disappeared. This finding indicated that the radiation-induced increase in cellular OCR was explained by an increase in mitochondrial mass but not by the activation of mitochondrial respiratory-related enzymes. In addition, mitochondrial semiquinone radicals at g = 2.004 were detected by low-temperature (110 K) ESR spectroscopy. The ESR signal intensity of semiquinone radicals was enhanced by X-irradiation, suggesting an increase in the electron flow in the electron transport chain. These data will be important to understand the mechanism of radio-sensitization by mitochondria-targeting reagents in tumor cells..
18. Nao Kato, Suguru Sato, Ken-Ichi Yamada, Kazuhiro Ichikawa, Imaging Doxorubicin Free Radical in Mice with Overhauser Enhanced MRI and its Tumor Suppression Effect in Mice, Applied Magnetic Resonance, 10.1007/s00723-018-1004-3, 1-11, 2018.04, In the treatment with anticancer drugs, it is important to deliver an anticancer agent to target site of the tumor at an appropriate concentration. However, it is difficult to directly measure the distribution amount of the agent and effect of anticancer drug is evaluated using its tumor suppression effect. In this study, we report an approach to visualizing an anticancer agent distribution in tumor-bearing mouse model using Overhauser enhanced magnetic resonance imaging (OMRI). The agent, doxorubicin, is one of anthracycline anticancer drugs and can form a free radical at its quinone sites and could be visualized using OMRI. After direct injection into a tumor, doxorubicin free radical was successfully imaged in tumor-bearing mouse, demonstrating practical usefulness of OMRI in the study of pharmacodynamics of free radical compounds. Imaging of antitumor agent would be potentially useful as a guidance tool for image-guided-therapy of cancer local chemotherapy..
19. Saki Shinto, Yuta Matsuoka, Mayumi Yamato, Ken-Ichi Yamada, Antioxidant nitroxides protect hepatic cells from oxidative stress-induced cell death, Journal of Clinical Biochemistry and Nutrition, 10.3164/jcbn.17-60, 62, 2, 132-138, 2018.03, Oxidative stress causes cell death and induces many kinds of disease, including liver disease. Nitroxides are known to react catalytically with free radicals. In this study, the cell protective activities of nitroxides were compared with those of other antioxidants. Nitroxides showed much greater inhibition of hydrogen peroxide-induced cell death than other antioxidants in a hepatic cell line and in primary hepatocytes. The intracellular oxidative stress level at 24 h after hydrogen peroxide stimulation was significantly decreased by nitroxides, but not by other antioxidants. To clarify the mechanism of cell protection by nitroxides, we investigated whether nitroxides inhibited DNA damage and mitogen-activated protein kinase pathway activation. We found that nitroxides reduced caspase3 activation and may have ultimately inhibited cell death. In conclusion, nitroxides are very useful for attenuating cell damage due to oxidative stress. Nitroxides are thus a potential therapeutic agent for oxidative stress-related diseases..
20. Xin Tun, Keiji Yasukawa, Ken-Ichi Yamada, Nitric oxide is involved in activation of Toll-like receptor 4 signaling through tyrosine nitration of Src homology protein tyrosine phosphatase 2 in murine dextran sulfate-induced colitis, Biological and Pharmaceutical Bulletin, 10.1248/bpb.b18-00558, 41, 12, 1843-1852, 2018.01, Ulcerative colitis is characterized by colonic mucosal bleeding and ulceration, often with repeated active and remission stages. One factor in ulcerative colitis development is increased susceptibility to commensal bacteria and lipopolysaccharide (LPS). LPS activates macrophages to release nitric oxide (NO) through Toll-like receptor 4 (TLR4) signaling. However, whether NO is beneficial or detrimental to colitis remains controversial. In this study, we investigated whether NO enhances the development of colitis in mice treated with dextran sulfate sodium (DSS) and inflammation in cells treated with low-dose LPS. An NO donor, NOC18, induced colitis and increased CD14 protein and nitrotyrosine levels in colonic macrophages from mice treated with DSS for 7d (molecular weight: 5000). In the mouse peritoneal macrophage cell line RAW264.7 stimulated with 3ng/mL LPS, NO activated the CD14-TLR4-nuclear factor kappa B (NF-κB) axis. Low-dose LPS stimulation did not change the levels of signal transducer and activator of transcription (STAT) 3 phosphorylation, CD14, inducible NO synthase, interleukin (IL)-6, or NF-κB. In addition, low-dose LPS increased phosphorylation of src homology protein tyrosine phosphatase 2 (SHP2), a negative regulator of STAT3 phosphorylation. However, NO decreased SHP2 phosphorylation and significantly activated the downstream signaling molecules. NO increased SHP2 nitration in LPS-stimulated RAW264.7 cells and DSS-treated mice. These results indicate that SHP2 nitration in macrophages might be involved in activation of the CD14-TLR4-NF-κB axis through STAT3 signaling in mice with DSS-induced colitis..
21. Ishida Y, Okamoto Y, Matsuoka Yuta, Tada A, Janprasit J, Yamato Mayumi, Morales NP, Ken-ichi Yamada, Detection and inhibition of lipid-derived radicals in low-density lipoprotein, 10.1016/j.freeradbiomed.2017.10.388, 2017.10, Oxidized low density lipoprotein (Ox-LDL) is implicated in a variety of oxidative diseases. To clarify the mechanisms involved and facilitate the investigation of therapeutics, we previously developed a detection method for lipid-derived radicals using the fluorescent probe 2,2,6-trimethyl-6-pentyl-4-(4-nitrobenzo[1,2,5]oxadiazol-7-ylamino)piperidine-1-oxyl (NBD-Pen). In this study, NBD-Pen was used to detect lipid-derived radicals in Ox-LDL from in vitro and in vivo samples using an iron overloaded mouse model. By following the timeline of lipid radical generation using this method, the iron overloaded mice could be successfully treated with the antioxidant trolox, resulting in successful lowering of the plasma lipid peroxidation, aspartate transaminase and alanine transaminase levels. Furthermore, using a combination therapy of the chelating agent deferoxamine and trolox, liver injury and oxidative stress markers were also reduced in iron overloaded mice. The NBD-Pen method is highly sensitive as well as selective and is suitable for targeting minimally modified LDL compared with other existing methods..
22. Enoki M, Shinto S, Matsuoka Yuta, Otsuka A, Kaidzu S, Tanito M, Shibata T, Ohira A, Yamato Mayumi, Ken-ichi Yamada, Lipid radicals cause light-induced retinal degeneration, 10.1039/c7cc03387g., 53, 10922-10925, 2017.09, Age-related macular degeneration (AMD) is the leading cause of blindness worldwide. Although the cause of AMD remains unknown, lipid peroxidation (LPO) end-products are critical molecules for its development. Herein, we report the imaging of lipid radicals, which are key factors in the LPO reaction, and therapeutic information using animal models.
23. Nakamura M, Shibata S, Yamasaki T, Ueno M, Nakanishi I, Matsumoto K, Kamada T, Ken-ichi Yamada, Feasibility of magnetic resonance redox imaging at low magnetic field: Comparison at 1 T and 7 T, American journal of Translational Research, 9, 8, 802-806, 2017.09, The effect of different static magnetic field strength, 1 or 7 T, on a quality of nitroxyl radical based magnetic resonance redox imaging (MRRI) was demonstrated. The nitroxyl radical based T1-weighted signal enhancement ratio was higher at a 1 T imager compare to a 7 T imager when scanning was carried out using a similar gradient echo sequence. The gradient echo scanning at 7 T was sensitive to movement and/or flux of the sample solution, which would be resulted in distortion of baseline T1 weighted signal. No such wobbling signal was observed when the experiment was done at the 1 T. In vivo nitroxyl decay curve was similar at 1 and 7 T. Nitroxyl radical based redox imaging could be enough performed on clinically popular 1 T.
24. Emoto MC, Matsuoka Yuta, Ken-ichi Yamada, Sato-Akaba H, Fujii HG, Non-invasive imaging of the levels and effects of glutathione on the redox status of mouse brain using electron paramagnetic resonance imaging, 10, 485, 4, 802-806, 2017.02, [URL], Glutathione (GSH) is the most abundant non-protein thiol that buffers reactive oxygen species in the brain. GSH does not reduce nitroxides directly, but in the presence of ascorbates, addition of GSH increases ascorbate-induced reduction of nitroxides. In this study, we used electron paramagnetic resonance (EPR) imaging and the nitroxide imaging probe, 3-methoxycarbonyl-2,2,5,5-tetramethyl-piperidine-1-oxyl (MCP), to non-invasively obtain spatially resolved redox data from mouse brains depleted of GSH with diethyl maleate compared to control. Based on the pharmacokinetics of the reduction reaction of MCP in the mouse heads, the pixel-based rate constant of its reduction reaction was calculated as an index of the redox status in vivo and mapped as a "redox map". The obtained redox maps from control and GSH-depleted mouse brains showed a clear change in the brain redox status, which was due to the decreased levels of GSH in brains as measured by a biochemical assay. We observed a linear relationship between the reduction rate constant of MCP and the level of GSH for both control and GSH-depleted mouse brains. Using this relationship, the GSH level in the brain can be estimated from the redox map obtained with EPR imaging..
25. Hironobu Yasui, Kumiko Yamamoto, Motofumi Suzuki, Yuri Sakai, Tomoki Bo, Masaki Nagane, Eri Nishimura, Tohru Yamamori, 山﨑 俊栄, Ken-ichi Yamada, Osamu Inanami, Lipophilic triphenylphosphonium derivatives enhance radiation-induced cell killing via inhibition of mitochondrial energy metabolism in tumor cells, 10, 1016, 390, 160-167, 2017.01, [URL], It has recently been reported that radiation enhances mitochondrial energy metabolism in various tumor cell lines. To examine how this radiation-induced alteration in mitochondrial function influences tumor cell viability, various lipophilic triphenylphosphonium (TPP+) cation derivatives and related compounds such as 4-hydroxy-2,2,6,6-tetramethyl-1-oxy-piperidin (Tempol) with TPP+ (named “Mito-”) were designed to inhibit the mitochondrial electron transport chain. Mito-(CH2)10-Tempol (M10T) and its derivatives, Mito-(CH2)5-Tempol (M5T), Mito-(CH2)10-Tempol-Methyl (M10T-Me), Mito-C10H21 (M10), and C10H21-Tempol (10T), were prepared. In HeLa human cervical adenocarcinoma cells and A549 human lung carcinoma cells, the fractional uptake of the compound into mitochondria was highest among the TTP+ analogs conjugated with Tempol (M10T, M5T, and 10T). M10T, M10T-Me, and M10 exhibited strong cytotoxicity and enhanced X-irradiation-induced reproductive cell death, while 10T and M5T did not. Furthermore, M10T, M10T-Me, and M10 decreased basal mitochondrial membrane potential and intracellular ATP. M10T treatment inhibited X-ray-induced increases in ATP production. These results indicate that the TPP cation and a long hydrocarbon linker are essential for radiosensitization of tumor cells. The reduction in intracellular ATP by lipophilic TPP+ is partly responsible for the observed radiosensitization..
26. Homma T, Akihara R, Okano S, Shichiri M, Yoshida Y, Ken-ichi Yamada, Miyata S, Nakajima O, Fujii J, Heightened aggressive behavior in mice deficient in aldo-keto reductase 1a (Akr1a), 10, 22, 319, 219-224, 2016.11, Aldehyde reductase (Akr1a) is involved in the synthesis of ascorbic acid (AsA) which may play a role in social behavior. In the current study, we performed analyses on Akr1a-deficient (Akr1a-/-) mice that synthesize about 10% as much AsA as wild-type mice from the viewpoint of intermale aggression. The use of the resident-intruder test revealed that the Akr1a-/- mice exhibited more aggressive phenotypes than wild-type control mice. Unexpectedly, however, the oral administration of additional AsA failed to reduce the aggressive behavior of Akr1a-/- mice, suggesting that the heightened aggression was independent of AsA biosynthesis. The findings also show that the plasma levels of corticosterone, but not serotonin and testosterone, were increased in the absence of Akr1a in mice, suggesting that the mice were highly stressed. These results suggest that Akr1a might be involved in the metabolism of steroids and other carbonyl-containing compounds and, hence, the absence of Akr1a results in heightened aggression via a malfunction in a metabolic pathway..
27. Akihara R, Homma T, Lee J, Ken-ichi Yamada, Miyata S, Fujii J, Ablation of aldehyde reductase aggravates carbon tetrachloride-induced acute hepatic injury involving oxidative stress and endoplasmic reticulum stress, 10.1016/j.bbrc.2016.08.022, 478, 2, 765-771, 2016.08, Aldehyde reductase (Akr1a) has been reported to be involved in the biosynthesis of ascorbic acid (AsA) in the mouse liver. Because Akr1a is expressed at high levels in the liver, we aimed to investigate the role of Akr1a in liver homeostasis by employing a carbon tetrachloride (CCl4)-induced hepatotoxicity model. Akr1a-deficient (Akr1a(-/-)) and wild-type (WT) mice were injected intraperitoneally with CCl4 and the extent of hepatic injury in the acute phase was assessed. Liver damage was heavier in the Akr1a(-/-) mice than in the WT mice. Furthermore, severe hepatic steatosis was observed in the livers of Akr1a(-/-) mice compared to WT mice and was restored to the levels in WT mice by AsA supplementation. Since the presence or absence of AsA had no effect on the decrease in CYP2E1 activity after the CCl4 treatment, it appears that AsA plays a role in the process after the bioactivation of CCl4. Biomarkers for oxidative stress and ER stress were markedly increased in the livers of Akr1a(-/-) mice and were effectively suppressed by AsA supplementation. Based on these collective results, we conclude that Akr1a exerts a protective effect against CCl4-induced hepatic steatosis by replenishing AsA via its antioxidative properties.
28. Ken Ichiro Matsumoto, Toshihide Yamasaki, Mizuki Nakamura, Junji Ishikawa, Megumi Ueno, Ikuo Nakanishi, Aiko Sekita, Yoshikazu Ozawa, Tadashi Kamada, Ichio Aoki, Ken-Ichi Yamada, Brain contrasting ability of blood-brain-barrier–permeable nitroxyl contrast agents for magnetic resonance redox imaging, Magnetic Resonance in Medicine, 10.1002/mrm.25918, 76, 3, 935-945, 2016.09, Purpose: The detailed in vivo T1-weighted contrasting abilities of nitroxyl contrast agents, which have been used as redox responsive contrast agents in several magnetic resonance-based imaging modalities, in mouse brain were investigated. Methods: Distribution and pharmacokinetics of five types of five-membered-ring nitroxyl radical compound were compared using T1-weighted MRI. Results: The blood–brain barrier (BBB) -impermeable 3-carboxy-2,2,5,5-tetramethylpyrrolidine-N-oxyl (CxP) could not be distributed in the brain. The slightly lipophilic 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (CmP) showed slight distribution only in the ventricle, but not in the medulla and cortex. The amphiphilic 3-methoxy-carbonyl-2,2,5,5-tetramethyl-pyrrolidine-N-oxyl (MCP) had good initial uniform distribution in the brain and showed typical 2-phase signal decay profiles. A brain-seeking nitroxyl probe, acetoxymethyl-2,2,5,5-tetramethyl-pyrrolidine-N-oxyl-3-carboxylate (CxP-AM), showed an accumulating phase, and then its accumulation was maintained in the medulla and ventricle regions, but not in the cortex. The lipophilic 4-(N-methyl piperidine)−2,2,5,5-tetramethylpyrroline-N-oxyl (23c) was well distributed in the cortex and medulla, but slightly in the ventricle, and showed relatively rapid linear signal decay. Conclusion: Nitroxyl contrast agents equipped with a suitable lipophilic substitution group could be BBB-permeable functional contrast agents. MR redox imaging, which can estimate not only the redox characteristics but also the detailed distribution of the contrast agents, is a good candidate for a theranostic tool. Magn Reson Med 76:935–945, 2016..
29. Matsuoka Y, Ohkubo K, Yamazaki T, Yamato M, Ohtabu H, Shirouzu T, Fukuzumi S, Ken-ichi Yamada, A profluorescent nitroxide probe for ascorbic acid detection and its application to quantitative analysis of diabetic rat plasma, 10, 58, 1, 16-22, 2016.06.
30. Ken-ichi Yamada, Mito F, Matsuoka Yuta, Ide S, Shikimachi K, Fujiki A, Kusakabe D, Ishida Y, Enoki M, Tada A, Ariyoshi M, 山﨑 俊栄, Yamato Mayumi, Fluorescence probes to detect lipid-derived radicals, 10.1038/nchembio.2105, 12, 608-613, 2016.06, Lipids and their metabolites are easily oxidized in chain reactions initiated by lipid radicals, forming lipid peroxidation products including the electrophiles 4-hydroxynonenal and malondialdehyde. These markers can bind cellular macromolecules, causing inflammation, apoptosis and other damage. Methods to detect and neutralize the initiating radicals would provide insights into disease mechanisms and new therapeutic approaches. We describe the first high sensitivity, specific fluorescence probe for lipid radicals, 4-(4-nitrobenzo[1,2,5]oxadiazol-7-ylamino)-6-pentyl-2,2,6-trimethylpiperidine-1-oxyl, (NBD-Pen). NBD-Pen directly detected lipid radicals in living cells by turn-on fluorescence. In a rat model of hepatic carcinoma induced by diethylnitrosamine (DEN), NBD-Pen detected lipid radical generation within 1 h of DEN administration. The lipid radical scavenging moiety of NBD-Pen decreased inflammation, apoptosis and oxidative stress markers at 24 h, and liver tumor development at 12 w after DEN. Thus, we have developed a novel fluorescence probe that provides imaging information about lipid radical generation and potential therapeutic benefits in vivo..
31. Kurahashi T, Lee J, Nabeshima A, Homma T, Kang ES, Saito Y, Yamada S, Nakayama T, Ken-ichi Yamada, Miyata S, Fujii J, Ascorbic acid prevents acetaminophen-induced hepatotoxicity in mice by ameliorating glutathione recovery and autophagy, 10, 604, 36-46, 2016.06.
32. Kimura S, Toyoshi Inoguchi, Yamasaki T, Yamato Mayumi, Ide M, Sonoda N, Ken-ichi Yamada, Takayanagi R, A novel DPP-4 inhibitor teneligliptin scavenges hydroxyl radicals: In vitro study evaluated by electron spin resonance spectroscopy and in vivo study using DPP-4 deficient rats, 65, 3, 138-145, 2016.03.
33. Han SK, Yamasaki T, Ken-ichi Yamada, Photodecomposition of tetrabromobisphenol A in aqueous humic acid suspension by irradiation with light of various wavelengths, 10, 147, 124-130, 2016.03.
34. Yamato M, Kawano K, Yamanaka Y, Saiga M, Ken-ichi Yamada, TEMPOL increases NAD+ and improves redox imbalance in obese mice., 10, 8, 316-322, 2016.02.
35. Matsuoka Y, Yamato Mayumi, Ken-ichi Yamada, Fluorescence probe for the convenient and sensitive detection of ascorbic acid, 58, 1, 16-22, 2015.12.
36. Emoto MC, Yamato M, Akaba-Sato H, Fujii HG, Ken-ichi Yamada, Brain redox imaging in the pentylenetetrazole (PTZ)-induced kindling model of epilepsy by using in vivo electron paramagnetic resonance and a nitroxide imaging probe, 608, 40-44, 2015.11.
37. Matsumoto T, Yamasaki T, Nakamura M, Ueno M, Nakanishi I, Shibata S, Sekita A, Saga T, Kamada T, Ken-ichi Yamada, Aoki I, Brain Contrasting Ability of Blood-Brain-Barrier- Permeable Nitroxyl Contrast Agents for Magnetic Resonance RedOx Imaging, 2015.09.
38. Emoto MC, Yamato Mayumi, Akaba-Sato H, Ken-ichi Yamada, Matsuoka Y, Fujii HG, Brain Imaging in Methamphetamine-Treated Mice using a Nitroxide Contrast Agent for EPR Imaging of the Redox Status and a Gadolinium Contrast Agent for MRI Observation of Blood-Brain Barrier Function, 49, 8, 1038-1047, 2015.07.
39. Ikeda M, Ide Tomomi, Fujino T, Arai S, Saku K, Kakino T, Tyynismaa H, Yamasaki T, Ken-ichi Yamada, Dongchon Kang, Suomalainen A, Kenji Sunagawa, Overexpression of TFAM or Twinkle Increases mtDNA Copy Number and Facilitates Cardioprotection Associated with Limited Mitochondrial Oxidative Stress, 10, 3, e0119687, 2015.03.
40. Nishida H, Kurahashi T, Saito Y, Otsuki N, Kwon M, Ohtake H, Yamakawa M, Ken-ichi Yamada, Miyata S, Tomita Y, Fujii J, Kidney fibrosis is independent of the amount of ascorbic acid in mice with unilateral ureteral obstruction, 48, 9, 1115-1124, 2014.09.
41. Tun X, keiji yasukawa, Ken-ichi Yamada, Involvement of nitric oxide with activation of Toll-like receptor 4 signaling in mice with dextran sodium sulfate-induced colitis, 74, 108-117, 2014.09.
42. Kurahashi T, Kwon M, Homma T, Saito Y, Lee J, Takahashi M, Ken-ichi Yamada, Miyata S, Fujii J, Reductive detoxification of acrolein as a potential role for aldehyde reductase (AKR1A) in mammals, 452, 1, 136-141, 2014.09.
43. Tracey B Kajer, Kathryn E Fairfull-Smith, Toshihide Yamasaki, Ken-ichi Yamada, Shanlin Fu, Steven E Bottle, Clare L Hawkins, Michael J Davies, Inhibition of myeloperoxidase- and neutrophil-mediated oxidant production by tetraethyl and tetramethyl nitroxides, FREE RADICAL BIOLOGY AND MEDICINE, 10.1016/j.freeradbiomed.2014.02.011, 70, 96-105, 2014.05.
44. Niidome T,, Chijiiwa N,, Yamasaki T, Ken-ichi Yamada, Mori T, Naganuma T, hideo utsumi, Kazuhiro Ichikawa, Yoshiki Katayama, Change in Overhauser Effect-Enhaced MRI Signal in Response to uPA Highly Expressing in Tumor, 43, 999-1001, 2014.04.
45. Junitsu Ito, Noriyuki Otsuki, Xuhong Zhang, Tasuku Konno, Toshihiro Kurahashi, Motoko Takahashi, Mayumi Yamato, Yuuta Matsuoka, Ken-ichi Yamada, Satoshi Miyata, Junichi Fujii, Ascorbic acid reverses the prolonged anesthetic action of pentobarbital in Akr1a-knockout mice, LIFE SCIENCES, 10.1016/j.lfs.2013.12.004, 95, 1, 1-8, 2014.01.
46. Akane Hayashi, matsunaga naoya, Hiroyuki Okazaki, Keisuke Kakimoto, Yoshinori Kimura, Hiroki Azuma, Eriko Ikeda, Takeshi Shiba, Mayumi Yamato, Ken-ichi yamada, Koyanagi Satoru, shigehiro ohdo, A Disruption Mechanism of the Molecular Clock in a MPTP Mouse Model of Parkinson's Disease. , Neuromol Med. , 15, 2, 238-251, 2013.06.
47. Emoto Miho C, Ken-ichi Yamada, Mayumi Yamato, Fujii Hirotada G, Novel ascorbic acid-resistive nitroxide in a lipid emulsion: An efficient brain imaging contrast agent for MRI of small rodents, NEUROSCIENCE LETTERS, 10.1016/j.neulet.2013.04.044, 546, 11-15, 2013.06.
48. Toshihide Yamasaki, Yuta Matsuoka, Fumiya Mito, Mayumi Yamato, Ken-ichi yamada, Redox Potential of Nitroxides is an Index to Evaluate Superoxide Dismutase Mimic Activity. , Asian J Org Chem , 2, 5, 388-391, 2013.05.
49. Benial AM, Dhas MK, Kazuhiro Ichikawa, Ken-ichi yamada, Fuminori Hyodo, Jawahar A, Hideo Utsumi, Permeability Studies of Redox-Sensitive Nitroxyl Spin Probes Through Lipid Membranes Using an L-Band ESR Spectrometer., Appl Magn Reson., 44, 4, 439-447, 2013.04.
50. keiji yasukawa, Hiroto Tokuda, Ton Xin, Hideo Utsumi, Ken-ichi yamada, The detrimental effect of nitric oxide on tissue is associated with inflammatory events in the vascular endothelium and neutrophils in mice with dextran sodium sulfate-induced colitis., Free Radic Res. , 46, 12, 1427-1436, 2012.12.
51. Yuta Matsuoka, Mayumi Yamato, Toshihide Yamasaki, Fumiya Mito, Ken-ichi yamada, Rapid and convenient detection of ascorbic acid using a fluorescent nitroxide switch. , Free Radic Biol Med. , 53, 11, 2112-2118, 2012.12.
52. KOSEM NUTTAVUT, Tatsuya Naganuma, Kazuhiro Ichikawa, Phumala Morales N, keiji yasukawa, Fuminori Hyodo, Ken-ichi yamada, Hideo Utsumi, Whole-body kinetic image of a redox probe in mice using Overhauser-enhanced MRI., Free Radic Biol Med., 53, 2, 328-336, 2012.07.
53. Yamato M, Shiba T, Ide T, Seri N, Kudo W, Ando M, Yamada K, Kinugawa S, Tsutsui H., High fat diet-induced obesity and insulin resistance were ameliorated via enhanced fecal bile acid excretion in tumor necrosis factor-alpha receptor knockout mice., Mol Cell Biochem., 359(1-2):161-7., 2012.01.
54. Deguchi H, Yasukawa K, Yamasaki T, Mito F, Kinoshita Y, Naganuma T, Sato S, Yamato M, Ichikawa K, Sakai K, Utsumi H, Yamada K., Nitroxides prevent exacerbation of indomethacin-induced gastric damage in adjuvant arthritis rats., Free Radic Biol Med. , 51(9):1799-805., 2011.11.
55. Yamato M, Shiba T, Naganuma T, Ichikawa K, Utsumi H, Yamada K., Overhauser-enhanced magnetic resonance imaging characterization of mitochondria functional changes in the 6-hydroxydopamine rat model., Neurochem Int. , 59(6):804-11., 2011.11.
56. Emoto M, Mito F, Yamasaki T, Yamada K, Sato-Akaba H, Hirata H, Fujii H., A novel ascorbic acid-resistive nitroxide in fat emulsion is an efficient brain imaging probe for in vivo EPR imaging of mouse., Free Radic Res., 45(11-12):1325-32., 2011.11.
57. Fumiya Mito, Toshihide Yamasaki, Chisato Shirahama, Taketoshi Oishi, Yuko Ito, Mayumi Yamato, Ken-ichi yamada, Oxygen concentration dependence of lipid peroxidation and lipid-derived radical generation: application of profluorescent nitroxide switch., Free Radic Res, 45(9):1103-10. , 2011.09.
58. Shiba T, Yamato M, Kudo W, Watanabe T, Utsumi H, Yamada KI., In vivo imaging of mitochondrial function in methamphetamine-treated rats., Neuroimage., 57(3):866-872., 2011.08.
59. Yamato M, Shiba T, Ide T, Honda Y, Yamada KI, Tsutsui H., Nifedipine treatment reduces brain damage after transient focal ischemia, possibly through its antioxidative effects., Hypertens Res., 34(7):840-5., 2011.07.
60. Mito F, Yamasaki T, Ito Y, Yamato M, Mino H, Sadasue H, Shirahama C, Sakai K, Utsumi H, Yamada K., Monitoring the aggregation processes of amyloid-β using a spin-labeled, fluorescent nitroxyl radical. , Chem Commun (Camb), 47(17):5070-2., 2011.05.
61. Yamasaki T, Ito Y, Mito F, Kitagawa K, Matsuoka Y, Yamato M, Yamada K., Structural concept of nitroxide as a lipid peroxidation inhibitor., J Org Chem, 76(10):4144-8., 2011.05.
62. Yamasaki T, Mito F, Ito Y, Pandian S, Kinoshita Y, Nakano K, Murugesan R, Sakai K, Utsumi H, Yamada K., Structure-reactivity relationship of piperidine nitroxide: electrochemical, ESR and computational studies., J Org Chem, 76(2):435-40., 2011.01.
63. Kinoshita Y, Yamada K, Yamasaki T, Mito F, Yamato M, Kosem N, Deguchi H, Shirahama C, Ito Y, Kitagawa K, Okukado N, Sakai K, Utsumi H., In vivo evaluation of novel nitroxyl radicals with reduction stability. , Free Radic Biol Med, 49(11): 1703-9., 2010.12.
64. Sakai K, Yamada K, Yamasaki T, Kinoshita Y, Mito F, Utsumi H., Effective 2,6-substitution of piperidine nitroxyl radical by carbonyl compound., Tetrahedron, 66, 2311-2315, 2010.05.
65. Benial AM, Utsumi H, Ichikawa K, Murugesan R, Yamada K, Kinoshita Y, Naganuma T, Kato M., Dynamic nuclear polarization studies of redox-sensitive nitroxyl spin probes in liposomal solution., J Magn Reson, 204(1):131-8., 2010.05.
66. Yamato M, Kudo W, Shiba T, Yamada KI, Watanabe T, Utsumi H., Determination of reactive oxygen species associated with the degeneration of dopaminergic neurons during dopamine metabolism., Free Radic Res, 44, 249-257, 2010.03.
67. Yamato M, Shiba T, Yamada K, Watanabe T, Utsumi H. , Noninvasive assessment of the brain redox status after transient middle cerebral artery occlusion using Overhauser-enhanced magnetic resonance imaging. , J Cereb Blood Flow Metab, 29, 10, 1655-1664, 2009.10.
68. Yamato M, Shiba T, Yamada K, Watanabe T, Utsumi H., Separable detection of lipophilic- and hydrophilic- phase free radicals from the ESR spectrum of nitroxyl radical in transient MCAO mice., Free Radic Res, 43, 844-851, 2009.06.
69. Kinoshita Y, Yamada KI, Yamasaki T, Sadasue H, Sakai K, Utsumi H., Development of novel nitroxyl radicals for controlling reactivity with ascorbic acid., Free Radic Res, In Press, 2009.04.
70. Yamada K, Kinoshita Y, Yamasaki T, Sadasue H, Mito F, Nagai M, Matsumoto S, Aso M, Suemune H, Sakai K, Utsumi H., Synthesis of nitroxyl radicals for Overhauser-enhanced magnetic resonance imaging., Arch Pharm (Weinheim), 341(9):548-53., 2008.09.
71. Shiba T, Yamato M, Kudou W, Ichikawa K, Yamada K, Watanabe T, Utsumi H., Analysis of nitroxyl spin probes in mouse brain by X-band ESR with microdialysis technique., J Pharm Sci, 97(9):4101-7, 2008.09.
72. Kudo W, Yamato M, Yamada K, Kinoshita Y, Shiba T, Watanabe T, Utsumi H., Formation of TEMPOL-hydroxylamine during reaction between TEMPOL and hydroxyl radical: HPLC/ECD study., Free Radic Res, 42(5):505-12., 2008.05.
73. Matsumoto S, Yamada K, Hirata H, Yasukawa K, Hyodo F, Ichikawa K, Utsumi H., Advantageous application of a surface coil to EPR irradiation in overhauser-enhanced MRI., Magn Reson Med, 57, 4, 806-811, 2007.04.
74. Yamato M, Matsumoto S, Ura K, Yamada K, Naganuma T, Inoguchi T, Watanabe T, Utsumi H. , Are free radical reactions increased in the diabetic eye?, Antioxid Redox Signal, 9, 3, 367-373, 2007.03.
75. Benial AM, Ichikawa K, Murugesan R, Yamada K, Utsumi H., Dynamic nuclear polarization properties of nitroxyl radicals used in Overhauser-enhanced MRI for simultaneous molecular imaging., J Magn Reson, 182, 2, 273-282, 2006.10.
76. Hyodo F, Yasukawa K, Yamada K, Utsumi H., Spatially resolved time-course studies of free radical reactions with an EPRI/MRI fusion technique., Magn Reson Med, 56, 4, 938-943, 2006.10.
77. Yamada K, Nakamura T, Utsumi H., Enhanced intraarticular free radical reactions in adjuvant arthritis rats., Free Radic Res, 40, 5, 455-460, 2006.05.
78. Yamada K, Yamamiya I, Utsumi H., In vivo detection of free radicals induced by diethylnitrosamine in rat liver tissue., Free Radic Biol Med, 40, 11, 2040-2046, 2006.06.
79. Utsumi H, Yamada K, Ichikawa K, Sakai K, Kinoshita Y, Matsumoto S, Nagai M., Simultaneous molecular imaging of redox reactions monitored by Overhauser-enhanced MRI with 14N- and 15N-labeled nitroxyl radicals., Proc Natl Acad Sci U S A, 103, 5, 1463-1468, 2006.01.
80. Utsumi H, Yasukawa K, Soeda T, Yamada K, Shigemi R, Yao T, Tsuneyoshi M., Noninvasive mapping of reactive oxygen species by in vivo electron spin resonance spectroscopy in indomethacin-induced gastric ulcers in rats., J Pharmacol Exp Ther, 317, 1, 228-235, 2006.04.
81. Utsumi H, Ken-ichi Yamada, In vivo electron spin resonance-computed tomography/nitroxyl probe technique for non-invasive analysis of oxidative injuries., 416, 1, 1-8, 2003.08, [URL], Free radicals are widely recognized as harmful chemical species in oxidative tissue injury. However, there have been no satisfying methods to visualize free radicals in vivo non-invasively with information of their localization and amount. In vivo electron spin resonance (ESR) spectroscopy was recently developed to measure free radicals generated in rodents. Several kinds of stable nitroxyl radicals were used as spin probes to detect free radicals. ESR signal intensities reflecting the accumulation of nitroxyl probes in each organ decreases time-dependently and reduction decay rates are increased in the presence of free radicals. Such increase in signal decay rates is suppressed by prior administration of antioxidants or antioxidant enzymes. Thus, in vivo ESR techniques are useful in estimating not only in vivo free radical reactions but also the effects of antioxidants, and furthermore, in combination with other tomographic techniques, permits non-invasive localization of free radicals. Application of this technique to animal models will be described.
PMID: 12859975.
82. Mito F, Kitagawa K, Yamasaki T, Shirahama C, Oishi T, Ito Y, Yamato M, Yamada K., Oxygen concentration dependence of lipid peroxidation and lipid-derived radical generation: application of profluorescent nitroxide switch., Free Radic Res, In press.
83. Shiba T, Yamato M, Kudo W, Watanabe T, Utsumi H, Yamada KI., In vivo imaging of mitochondrial function in methamphetamine-treated rats., Neuroimage, In press.
84. Yamato M, Shiba T, Ide T, Honda Y, Yamada KI, Tsutsui H., Nifedipine treatment reduces brain damage after transient focal ischemia, possibly through its antioxidative effects., Hypertens Res, In press.
85. Mayumi Yamato, Ayumi Ishimatsu, Yuki Yamanaka, Takara Mine, Ken-ichi Yamada, Tempol intake improves inflammatory status in aged mice, J Clin Biochem Nutr, In Press.