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Articles by K Watanabe
Total Records ( 7 ) for K Watanabe
  R Muramatsu , S Nakahara , J Ichikawa , K Watanabe , N Matsuki and R. Koyama
 

Proper axonal targeting is fundamental to the establishment of functional neural circuits. The hippocampal mossy fibres normally project towards the CA3 region. In the hippocampi of patients with temporal lobe epilepsy and related animal models, however, mossy fibres project towards the molecular layer and produce the hyperexcitable recurrent networks. The cellular and molecular mechanisms underlying this aberrant axonal targeting, known as mossy fibre sprouting, remain unclear. Netrin-1 attracts or repels axons depending on the composition of its attraction-mediating receptor, deleted in colorectal cancer, and its repulsion-mediating receptor, uncoordinated-5, on the growth cone; but the roles of netrin-1-dependent guidance in pathological conditions are largely unknown. In this study, we examined the role of netrin-1 and its receptors in mossy fibre guidance and report that enhanced neuronal activity changes netrin-1-mediated cell targeting by the axons under hyperexcitable conditions. Netrin-1 antibody or Dcc ribonucleic acid interference attenuated mossy fibre growth towards CA3 in slice overlay assays. The axons were repelled from CA3 and ultimately innervated the molecular layer when hyperactivity was pharmacologically introduced. We first hypothesized that a reduction in netrin-1 expression in CA3 underlies the phenomenon, but found that its expression was increased. We then examined two possible activity-dependent changes in netrin-1 receptor expression: a reduction in the deleted in colorectal cancer receptor and induction of uncoordinated-5 receptor. Hyperactivity did not affect the surface expression of the deleted in colorectal cancer receptor on the growth cone, but it increased that of uncoordinated-5A, which was suppressed by blocking cyclic adenosine monophosphate signalling. In addition, Dcc knockdown did not affect hyperactivity-induced mossy fibre sprouting in the slice cultures, whereas Unc5a knockdown rescued the mistargeting. Thus, netrin-1 appears to attract mossy fibres via the deleted in colorectal cancer receptor, while it repels them via cyclic adenosine monophosphate-induced uncoordinated-5A under hyperexcitable conditions, resulting in mossy fibre sprouting.

  T Oyama , Y Yasui , S Sugie , M Koketsu , K Watanabe and T. Tanaka
 

The flavone 4',5,7-trihydroxy-3',5'-dimethoxyflavone (tricin) present in rice, oats, barley, and wheat exhibits antigrowth activity in several human cancer cell lines and anti-inflammatory potential. However, the chemopreventive activity has not yet been elucidated in preclinical animal models of colorectal cancer. This study was designed to determine whether dietary tricin exerts inflammation-associated colon carcinogenesis induced by azoxymethane and dextran sulfate sodium in mice. Male Crj: CD-1 mice were initiated with a single i.p. injection of azoxymethane (10 mg/kg body weight) and followed by a 1-week exposure to dextran sulfate sodium (1.5%, w/v) in drinking water to induce colonic neoplasms. They were then given the experimental diet containing 50 or 250 ppm tricin. The experiment was terminated at week 18 to determine the chemopreventive efficacy of tricin. In addition, the effects of dietary tricin on the expression of several inflammatory cytokines, including tumor necrosis factor (TNF)-, were assayed. The development of colonic adenomas and adenocarcinomas was significantly reduced by feeding with 50 and 250 ppm tricin, respectively. Dietary tricin also significantly reduced the proliferation of adenocarcinoma cells as well as the numbers of mitoses/anaphase bridging in adenocarcinoma cells. The dietary administration with tricin significantly inhibited the expression of TNF- in the nonlesional cypts. Our findings that dietary tricin inhibits inflammation-related mouse colon carcinogenesis by suppressing the expression of TNF- in the nonlesional cyrpts and the proliferation of adenocarcinomas suggest a potential use of tricin for clinical trials of colorectal cancer chemoprevention.

  J. e Obata , T Nakamura , Y Kitta , Y Kodama , K Sano , K. I Kawabata , Y Saitoh , D Fujioka , T Kobayashi , T Yano , Y Watanabe , K Watanabe and K. Kugiyama
 

Background— Sirolimus-eluting stent (SES) implantation aggravated endothelial vasomotor dysfunction in infarct-related coronary arteries.

Methods and Results— This study examined the effect of SES implantation on the duration of reperfusion-induced endothelial vasomotor dysfunction in infarct-related coronary arteries and on postinfarct left ventricular dysfunction in acute myocardial infarction (AMI). Patients with a first AMI due to occlusion of the left anterior descending coronary artery and successful reperfusion using SES (n=15) or bare metal stents (BMS; n=18) were examined. The vasomotor response of the left anterior descending coronary artery to acetylcholine and left ventriculography were examined 2 weeks and 6 months after AMI. At 6 months after AMI, the impairment of epicardial coronary artery dilation and coronary blood flow increase in response to acetylcholine was recovered from 2 weeks after AMI in BMS-treated patients, whereas the responses of SES-treated patients improved but remained impaired compared with BMS-treated patients (% increase in blood flow, 77±12% in SES versus 116±15% in BMS at 10 µg/min of acetylcholine, P<0.01). Left ventricular regional wall dysfunction in the left anterior descending coronary artery territory improved from 2 weeks to 6 months after AMI in BMS-treated patients but not in SES-treated patients (% improvement of average SD/chord, 6% in SES versus 19% in BMS, P<0.05), although left ventricular global ejection fraction was similar between the groups at any time points.

Conclusions— SES implantation may delay recovery of reperfusion-induced endothelial vasomotor dysfunction in infarct-related coronary arteries and left ventricular regional dysfunction for at least 6 months after AMI.

  K Sawada , H Takahashi , K Abe , T Ichii , K Watanabe and Y. Takao
 

Sawada, K., Takahashi, H., Abe, K., Ichii, T., Watanabe, K., and Takao, Y. 2009. Target-strength, length, and tilt-angle measurements of Pacific saury (Cololabis saira) and Japanese anchovy (Engraulis japonicus) using an acoustic-optical system. – ICES Journal of Marine Science, 66: 1212–1218.

Pacific saury and Japanese anchovy generally congregate in dense groups or schools. An acoustic-optical system (the Japanese Quantitative Echosounder and Stereo-video Camera System or J-QUEST) has been developed to measure accurately the target strength (TS) of fish in a dense school. J-QUEST comprises a quantitative, 70 kHz, split-beam echosounder and a stereo-video camera. It was deployed from a research vessel to collect concomitant measures of TS and stereo images of in situ Pacific saury and Japanese anchovy. The stereo-video camera provides estimates of the fish lengths (L) and tilt-angles corrected for J-QUEST motion. In this way, empirical models of TS vs. log(L) were derived for Pacific saury and Japanese anchovy and compared with theory.

  T Fujii , H Kunikane , H Okamoto , K Watanabe , H Kunitoh , K Mori , A Yokoyama , H Fukuda , T Tamura and N. Saijo
  Objective

It is important to find optimal regimens of cisplatin (CDDP)-based third-generation chemotherapy and radiotherapy for patients with unresectable Stage III non-small cell lung cancer (NSCLC).

Methods

This Phase II study was designed to determine the toxicity and efficacy of two courses of chemotherapy (CDDP 80 mg/m2 on day 1 and irinotecan 60 mg/m2 on days 1 and 8) followed by accelerated hyperfractionated thoracic radiotherapy (60 Gy/40 fractions in 4 weeks) combined with daily carboplatin (CBDCA) administration. CBDCA was administered at a target area under the plasma level–time curve of 0.4 x (24 h creatinine clearance + 25), according to Calvert's formula.

Results

Twenty-six patients were enrolled in the study. The patients' median age was 63 years (range 40–74 years) and included 22 males and 4 females. Seven patients were Stage IIIA and 19 were Stage IIIB. Twenty had a performance status (PS) of 1 versus six with a PS of 0. There was one treatment-related death due to sepsis and pneumonia associated with Grade 4 neutropenia and diarrhea during chemotherapy. Grade 3 or 4 neutropenia and diarrhea were observed in 14 and 5 patients, respectively. Toxicity of the radiotherapy was mild. There were 0 complete response and 13 partial responses, giving a response rate of 50.0%. Median survival time and 2-year survival were 16.4 months and 21.5%, respectively. This study was designed with Simon's two-stage design, and the response rate did not meet the criteria to proceed to the second stage and the study was terminated early.

Conclusions

This regimen might be inactive for patients with unresectable Stage III NSCLC.

  T Hara , K Tanaka , K Maehata , K Mitsuda , N. Y Yamasaki , M Ohsaki , K Watanabe , X Yu , T Ito and Y. Yamanaka
 

A new energy dispersive X-ray spectrometer (EDS) with a mi- crocalorimeter detector equipped with a transmission electron microscope (TEM) has been developed for high- accuracy compositional analysis in the nanoscale. A superconducting transition-edge-sensor-type microcalorimeter is applied as the detector. A cryogen-free cooling system, which consists of a mechanical and a dilution refrigerator, is selected to achieve long-term temperature stability. In order to mount these detector and refrigerators on a TEM, the cooling system is specially designed such that these two refrigerators are separated. Also, the detector position and arrangement are carefully designed to avoid adverse affects between the superconductor detector and the TEM lens system. Using the developed EDS system, at present, an energy resolution of 21.92 eV full-width-at-half maximum has been achieved at the Cr K line. This value is about seven times better than that of the current typical commercial Si(Li) detector, which is usually around 140 eV. The developed microcalorimeter EDS system can measure a wide energy range, 1–20 keV, at one time with this high energy resolution that can resolve peaks from most of the elements. Although several further developments will be needed to enable practical use, highly accurate compositional analysis with high energy resolution will be realized by this microcalorimeter EDS system.

  K Watanabe , T Nagaoka , J. M Lee , C Bianco , M Gonzales , N. P Castro , M. C Rangel , K Sakamoto , Y Sun , R Callahan and D. S. Salomon
 

Cripto-1 associates with Notch1 in the endoplasmic reticulum and Golgi to enhance Notch1 localization to lipid rafts and its maturation.

 
 
 
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