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Articles by S Kimura
Total Records ( 4 ) for S Kimura
  S Kimura , T Kakuta , T Yonetsu , A Suzuki , Y Iesaka , H Fujiwara and M. Isobe
 

Background— Atherosclerotic plaque that shows echo signal attenuation (EA) without associated bright echoes is sometimes observed by intravascular ultrasound but its clinical significance remains unclear. We investigated the impact of EA on coronary perfusion and evaluated the pathological features of plaque with EA.

Methods and Results— We studied 687 native coronary lesions in 687 consecutive patients (336 with acute coronary syndrome and 351 with stable angina pectoris) who underwent intravascular ultrasound before percutaneous coronary intervention. By subgroup analysis, 60 lesions (30 lesions with EA) treated with directional coronary atherectomy underwent pathological examination. The Thrombolysis in Myocardial Infarction (TIMI) flow grade and myocardial blush grade after percutaneous coronary intervention were compared between lesions with and without EA in 627 lesions except directional coronary atherectomy subgroup. EA was observed in 245 lesions (35.7%), and coronary flow after percutaneous coronary intervention was worse for lesions with EA than without (final TIMI grade of 0 to 2: 15.4% versus 2.4%, P<0.001; final myocardial blush grade of 0 to 2: 45.6% versus 21.4%, P<0.001). Multivariate analysis revealed a significant association between no reflow (TIMI grade 0 to 2) and EA (odds ratio, 5.59; 95% CI, 2.64 to 11.85; P<0.001), a baseline TIMI grade of 0 to 2 (odds ratio, 5.91; 95% CI, 2.79 to 12.5; P<0.001), and a large reference area (odds ratio, 3.08; 95% CI, 1.40 to 6.76; P=0.005) after controlling for other associated factors. Pathological examination revealed a significantly higher frequency of lipid-rich plaque with microcalcification in lesions with EA.

Conclusions— Atherosclerotic plaque with EA showed a significant association with no reflow after percutaneous coronary intervention, suggesting the existence of fragile components susceptible to distal embolization.

  S Sawatsubashi , T Murata , J Lim , R Fujiki , S Ito , E Suzuki , M Tanabe , Y Zhao , S Kimura , S Fujiyama , T Ueda , D Umetsu , T Ito , K. i Takeyama and S. Kato
 

Chromatin reorganization is essential for transcriptional control by sequence-specific transcription factors. However, the molecular link between transcriptional control and chromatin reconfiguration remains unclear. By colocalization of the nuclear ecdysone receptor (EcR) on the ecdysone-induced puff in the salivary gland, Drosophila DEK (dDEK) was genetically identified as a coactivator of EcR in both insect cells and intact flies. Biochemical purification and characterization of the complexes containing fly and human DEKs revealed that DEKs serve as histone chaperones via phosphorylation by forming complexes with casein kinase 2. Consistent with the preferential association of the DEK complex with histones enriched in active epigenetic marks, dDEK facilitated H3.3 assembly during puff formation. In some human myeloid leukemia patients, DEK was fused to CAN by chromosomal translocation. This mutation significantly reduced formation of the DEK complex, which is required for histone chaperone activity. Thus, the present study suggests that at least one histone chaperone can be categorized as a type of transcriptional coactivator for nuclear receptors.

  M Yamaguchi , S Takemori , M Kimura , Y Tanishima , T Nakayoshi , S Kimura , T Ohno , N Yagi , J. F. Y Hoh and Y. Umazume
 

To characterize the structure of jaw muscle fibres expressing masticatory (superfast) myosin, X-ray diffraction patterns of glycerinated fibres of dog masseter were compared with those of dog tibialis anterior in the relaxed state. Meridional reflections of masseter fibres were laterally broad, indicating that myosin filaments are staggered along the filament axis. Compared with tibialis anterior fibres, the peak of the first myosin layer line of masseter fibres was lower in intensity and shifted towards the meridian, while lattice spacings were larger at a similar sarcomere length. These suggest that the myosin heads of masticatory fibres are mobile, and tend to protrude from the filament shaft towards actin filaments. Lowering temperature or treating with N-phenylmaleimide shifted the peak of the first myosin layer line of tibialis anterior fibres towards the meridian and the resulting profile resembled that of masseter fibres. This suggests that the protruding mobile heads in the non-treated masticatory fibres are in the ATP-bound state. The increased population of weakly binding cross-bridges may contribute towards the high specific force of masticatory fibres during contraction. Electron micrographs confirmed the staggered alignment of thick filaments along the filament axis within sarcomeres of masticatory fibres, a feature that may confer efficient force development over a wide range of the sarcomere lengths.

  S Oka , S Kimura , T Toshida , R Ota , A Yamashita and T. Sugiura
 

Lysophosphatidylinositol (LPI) is an endogenous ligand for GPR55, a putative novel type of cannabinoid receptor. In this study, we first examined the effects of LPI on p38 mitogen-activated protein kinase in HEK293 cells expressing GPR55. LPI induced the rapid phosphorylation of p38 mitogen-activated protein kinase in GPR55-expressing cells. No apparent effect was observed in the vector-transfected cells. The exposure of GPR55-expressing cells to LPI also triggered the phosphorylation of activating transcription factor 2 downstream of the p38 mitogen-activated protein kinase. Treatment of the cells with Y-27632 [a Rho-associated kinase (ROCK) inhibitor] blocked the LPI-induced phosphorylation of p38 mitogen-activated protein kinase and activating transcription factor 2, suggesting that the Rho-ROCK pathway is involved in these cellular responses. Notably, GPR55 was found to be abundantly expressed in lymphoid organs such as the spleen and thymus. We obtained evidence that rapid phosphorylation of p38 mitogen-activated protein kinase and activating transcription factor 2 also takes place in IM-9 lymphoblastoid cells, which naturally express GPR55, after stimulation with LPI. These results suggest that GPR55 and its endogenous ligand LPI play essential roles in the homoeostatic responses to stress signals in several mammalian tissues and cells including certain types of immune cells.

 
 
 
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