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Articles by H. Watanabe
Total Records ( 3 ) for H. Watanabe
  M Asai , K Takeuchi , M Saotome , T Urushida , H Katoh , H Satoh , H Hayashi and H. Watanabe

Hypoxia, ischaemia, and exogenous chemicals can induce extracellular and intracellular acidosis, but it is not clear which of these types of acidosis affects endothelial cell function. The synthesis and release of endothelium-derived relaxing factors (EDRFs) are linked to an increase in cytosolic Ca2+ concentration, and we therefore examined the effects of extracellular and intracellular acidosis on Ca2+ responses and EDRF production in cultured porcine aortic endothelial cells.

Methods and results

Cytosolic pH (pHi) and Ca2+ were measured using fluorescent dyes, BCECM/AM (pH-indicator) and fura-2/AM (Ca2+-indicator), respectively. EDRFs, nitric oxide (NO) and prostaglandin I2 (PGI2) were assessed using DAF-FM/DA (NO-indicator dye) fluorometry and 6-keto PGF1 enzyme immunoassay, respectively. HEPES buffers titrated to pH 6.4, 6.9, and 7.4 were used to alter extracellular pH (pHo), and propionate (20 mmol/L) was applied to cause intracellular acidosis. Extracellular acidosis strongly suppressed bradykinin (BK, 10 nmol/L)- and thapsigargin (TG, 1 µmol/L)-induced Ca2+ responses by 30 and 23% at pHo 6.9, and by 80 and 97% at pHo 6.4, respectively. During the examinations, there were no significant differences in pHi among the three groups at pHo 7.4, 6.9, and 6.4. Extracellular acidosis also inhibited BK-stimulated PGI2 production by 55% at pHo 6.9 and by 77% at pHo 6.4, and NO production by 38% at pHo 6.9 and by 91% at pHo 6.4. The suppressive effects of extracellular acidosis on Ca2+ responses and NO production were reversible. Propionate changed pHi from 7.3 to 6.9, without altering pHo (7.4). Intracellular acidosis had no effect on BK- and TG-induced Ca2+ responses or NO production.


These results indicate that extracellular, but not intracellular, acidosis causes endothelial dysfunction by inhibiting store-operated Ca2+ entry, so helping to clarify the vascular pathophysiology of conditions such as ischaemia, hypoxia, acidosis, and ischaemia-reperfusion.

  H. Watanabe , Y. Adachi and M. Saigusa
  Improving early seedling growth is crucial for direct-seeding rice cultivation. In this study, field and laboratory experiments were conducted to determine the effects of Plant Growth Regulators (PGRs) such as gibberellic acid (GA3) and ethephon (ET) on the early growth of direct-seeded rice. Seeds were treated with the PGRs and pre-germinated at 30°C in the dark. For the field experiment, two Flooding Depth (FD) regimes were established during the growth period: 0 cm (drained condition) and 2 cm (flooded condition). Treatment of seeds with ET or GA3 alone promoted the growth of seedling organs compared to that of the control at both the FDs in some cases. However, combined application of ET and GA3 (ET+GA3) synergistically improved the growth of different seedling organs at both the FDs in most cases with slight exception: the coleoptile and mesocotyl plus coleoptile (mesocotyl+coleoptile) length were not different across the PGR treatments under drained condition. Further, the growth of the second node tiller was stimulated by the application of ET alone under drained conditions. The laboratory experiment revealed that ET+GA3 increased the growth rate of mesocotyl+coleoptile and that of the first leaf. These results suggest that the combined application of ET and GA3 might be useful for improving the growth performance of rice seedlings in the direct seeding method.
  Kai Man Kam , Cindy K. Y. Luey , Michele B. Parsons , Kara L. F. Cooper , G. B. Nair , M. Alam , M. Atiqul Islam , Danny T. L. Cheung , Y. W. Chu , T. Ramamurthy , G. P. Pazhani , S. K. Bhattacharya , H. Watanabe , J. Terajima , E. Arakawa , O.-A. Ratchtrachenchai , S. Huttayananont , Efrain M. Ribot , Peter Gerner-Smidt and Bala Swaminathan
  The pandemic spread of Vibrio parahaemolyticus is an international public health issue. Because of the outbreak potential of the organism, it is critical to establish an internationally recognized molecular subtyping protocol for V. parahaemolyticus that is both rapid and robust as a means to monitor its further spread and to guide control measures in combination with epidemiologic data. Here we describe the results of a multicenter, multicountry validation of a new PulseNet International standardized V. parahaemolyticus pulsed-field gel electrophoresis (PFGE) protocol. The results are from a composite analysis of 36 well-characterized V. parahaemolyticus isolates from six participating laboratories, and the isolates represent predominant serotypes and various genotypes isolated from different geographic regions and time periods. The discriminatory power is very high, as 34 out of 36 sporadic V. parahaemolyticus strains tested fell into 34 distinguishable PFGE groups when the data obtained with two restriction enzymes (SfiI and NotI) were combined. PFGE was further able to cluster members of known pandemic serogroups. The study also identified quality measures which may affect the performance of the protocol. Nonadherence to the recommended procedure may lead to high background in the PFGE gel patterns, partial digestion, and poor fragment resolution. When these quality measures were implemented, the PulseNet V. parahaemolyticus protocol was found to be both robust and reproducible among the collaborating laboratories.
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