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Articles by K Hirata
Total Records ( 4 ) for K Hirata
  Y Yamazaki , I Usui , Y Kanatani , Y Matsuya , K Tsuneyama , S Fujisaka , A Bukhari , H Suzuki , S Senda , S Imanishi , K Hirata , M Ishiki , R Hayashi , M Urakaze , H Nemoto , M Kobayashi and K. Tobe

Nonalcoholic fatty liver disease (NAFLD) is an abnormal liver metabolism often observed with insulin resistance and metabolic syndrome. Calorie restriction is a useful treatment for NAFLD and reportedly prolongs the life spans of several species in which sirtuin plays an important role. In this study, we examined whether the activation of SIRT1, a mammalian ortholog of sirtuin, may ameliorate the development of NAFLD. Monosodium glutamate (MSG) mice, which exhibited obesity and insulin resistance, were treated with SRT1720, a specific SIRT1 activator from the age of 6–16 wk. Sixteen-week-old MSG mice exhibited increased liver triglyceride content and elevated levels of aminotransferase. SRT1720 treatment significantly reduced these levels without affecting body weight or food intake. These results suggested that the administration of SRT1720 ameliorated the development of NAFLD in MSG mice. The expressions of lipogenic genes, such as sterol regulatory element-binding protein-1c, acetyl-CoA carboxylase, and fatty acid synthase, and the serum lipid profiles, including free fatty acids, were elevated in MSG mice and were reduced by SRT1720 treatment. SRT1720 treatment also reduced the expressions of lipogenic genes in cultured HepG2 cells. Furthermore, SRT1720 treatment decreased the expressions of marker genes for oxidative stress and inflammatory cytokines in the liver of MSG mice. Taken together, SRT1720 treatment may reduce liver lipid accumulation, at least in part, by directly reducing the expressions of lipogenic genes. The reduction of oxidative stress and inflammation may also be involved in the amelioration of NAFLD.

  N Kokubun , M Nishibayashi , A Uncini , M Odaka , K Hirata and N. Yuki

Guillain–Barré syndrome is divided into two major subtypes, acute inflammatory demyelinating polyneuropathy and acute motor axonal neuropathy. The characteristic electrophysiological features of acute motor axonal neuropathy are reduced amplitude or absence of distal compound muscle action potentials indicating axonal degeneration. In contrast, autopsy study results show early nodal changes in acute motor axonal neuropathy that may produce motor nerve conduction block. Because the presence of conduction block in acute motor axonal neuropathy has yet to be fully recognized, we reviewed how often conduction block occurred and how frequently it either reversed or was followed by axonal degeneration. Based on Ho’s criteria, acute motor axonal neuropathy was electrodiagnosed in 18 patients, and repeated motor nerve conduction studies were carried out on their median and ulnar nerves. Forearm segments of these nerves and the across-elbow segments of the ulnar nerve were examined to evaluate conduction block based on the consensus criteria of the American Association of Electrodiagnostic Medicine. Twelve (67%) of the 18 patients with acute motor axonal neuropathy had definite (n = 7) or probable (n = 5) conduction blocks. Definite conduction block was detected for one patient (6%) in the forearm segments of both nerves and probable conduction block was detected for five patients (28%). Definite conduction block was present across the elbow segment of the ulnar nerve in seven patients (39%) and probable conduction block in two patients (11%). Conduction block was reversible in seven of 12 patients and was followed by axonal degeneration in six. All conduction blocks had disappeared or begun to resolve within three weeks with no electrophysiological evidence of remyelination. One patient showed both reversible conduction block and conduction block followed by axonal degeneration. Clinical features and anti-ganglioside antibody profiles were similar in the patients with (n = 12) and without (n = 6) conduction block as well as in those with (n = 7) and without (n = 5) reversible conduction block, indicating that both conditions form a continuum; a pathophysiological spectrum ranging from reversible conduction failure to axonal degeneration, possibly mediated by antibody attack on gangliosides at the axolemma of the nodes of Ranvier, indicating that reversible conduction block and conduction block followed by axonal degeneration and axonal degeneration without conduction block constitute continuous electrophysiological conditions in acute motor axonal neuropathy.

  A Tanaka , T Imanishi , H Kitabata , T Kubo , S Takarada , T Tanimoto , A Kuroi , H Tsujioka , H Ikejima , K Komukai , H Kataiwa , K Okouchi , M Kashiwaghi , K Ishibashi , H Matsumoto , K Takemoto , N Nakamura , K Hirata , M Mizukoshi and T. Akasaka

Although some recent guidelines recommend an early invasive strategy for non-ST-segment elevation acute coronary syndrome (NSTEACS), several studies have failed to identify any benefit for very early intervention for NSTEACS. The no-reflow phenomenon may inhibit the expected benefit from very early recanalization for NSTEACS subjects. The aim of this study was to investigate whether optical coherence tomography (OCT) could predict no-reflow in patients with NSTEACS.

Methods and results

This study comprised 83 consecutive patients with NSTEACS who underwent OCT and successful emergent primary stenting. On the basis of post-stent TIMI flow, patients were divided into two groups: no-reflow group (n = 14) and reflow group (n = 69). Thin-cap fibroatheroma (TCFA) was defined as a plaque presenting lipid content for >90°, and with thinnest part of the fibrous cap measuring <70 µm. Thin-cap fibroatheroma were more frequently observed in the no-reflow group than in the reflow group (50% vs. 16%, P = 0.005). The frequency of the no-reflow phenomenon increases according to the size of the lipid arc in the culprit plaque. Final TIMI blush grade also deteriorated according to the increase in the lipid arc. A multivariable logistic regression model revealed that lipid arc alone was an independent predictor of no-reflow (odds ratio 1.018; CI 1.004–1.033; P = 0.01).


Optical coherence tomography can predict no-reflow after percutaneous coronary intervention (PCI) in NSTEACS. The lipid contents of a culprit plaque may play a key role in damage to the microcirculation after PCI for NSTEACS. From our results, it is found that OCT is useful tool for stratifying risk for PCI for NSTEACS.

  W Xia , K Hirata , K Yanagisawa , Y Ishida , H Kasai , K Yanagiuchi , D Shindo and A. Tonomura

The magnetic interaction between the pole tip of a single-pole head and a pseudo soft underlayer in perpendicular magnetic recording was observed by electron holography. The magnetic flux density inside the soft underlayer was quantitatively evaluated. The distribution of magnetic flux density was calculated using the finite element method, and the influences of the modulation of the reference wave and stray fields were investigated by comparison with experimental results. The flux density observed was found to be underestimated due to the modulation of the phase shift in reference wave. The magnetic flux measured experimentally was larger than that inside the specimen because of the relatively large stray fields above and below the specimen in the direction of the electron beam.

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