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Articles by T Onishi
Total Records ( 3 ) for T Onishi
  T Onishi , H Kawai , K Tatsumi , T Kataoka , D Sugiyama , H Tanaka , Y Okita and K. i. Hirata
 

Background— The best predictor for postoperative left ventricular (LV) systolic dysfunction in patients with chronic aortic regurgitation is still a matter of debate. The aim of this study was to assess the clinical significance of preoperative systolic radial strain rate (Ssr) derived from tissue Doppler echocardiography as a predictor of postoperative LV systolic dysfunction in patients with chronic aortic regurgitation.

Methods and Results— In 52 patients (mean age, 58 years; 13 women) with isolated chronic aortic regurgitation, we performed standard and tissue Doppler echocardiography before and after operation, obtained echocardiographic parameters such as LV dimensions and LV ejection fraction, and measured Ssr in 4 walls of the LV. Linear regression analysis determined correlations between preoperative parameters and postoperative LV ejection fraction. Receiver-operating characteristic curve analysis assessed the optimal cutoff values of parameters that predicted postoperative LV systolic dysfunction (ejection fraction <50%). The operation caused significant decreases in LV dimensions and volumes and significant increases in Ssr (1.94±0.64 to 2.39±0.83 per second; P<0.001) and ejection fraction (53.0±8.7 to 59.0±8.8%; P<0.001). Multiple regression analysis demonstrated that averaged Ssr was the only independent predictor of postoperative LV systolic dysfunction among the covariates examined (P<0.001). Using receiver-operating characteristic curve analysis, averaged Ssr yielded the greatest area under the curve among preoperative parameters (0.80) and was indicated to be a good predictor of postoperative LV dysfunction, with 90.9% sensitivity and 73.2% specificity (cutoff value, 1.82 per second).

Conclusions— Measurement of preoperative averaged Ssr is useful in predicting postoperative LV systolic dysfunction and optimizing surgical timing in patients with isolated chronic aortic regurgitation.

  K Tatsumi , H Kawai , D Sugiyama , K Norisada , T Kataoka , T Onishi , H Tanaka and K. i. Hirata
  Background—

Left ventricular (LV) remodeling can increase tethering force to mitral valve and functional mitral regurgitation (FMR). Because the relationship between FMR and regional myocardial function has not been quantitatively evaluated, we conducted a quantitative investigation of this association.

Methods and Results—

The effective regurgitant orifice (ERO) of FMR in 51 patients with depressed LV ejection fraction (32±9%) secondary to ischemic or nonischemic cardiomyopathy was compared with mitral deformation (valve and annulus), global LV remodeling (volume indices, function, and sphericity), and regional myocardial contractile function, as assessed by longitudinal peak systolic strain rate (Ssr) in LV anterior, anteroseptal, inferoseptal, inferior, inferolateral, and anterolateral segments at rest. Low-dose dobutamine (10 µg/kg per minute)-induced changes in ERO were compared with changes in the variables. Multivariable analysis identified the predictors of ERO at rest as mitral valvular tenting (β=0.062; P<0.001), Ssr in the inferior segment (inferior Ssr) (β=–0.178; P<0.001), and LV sphericity (β=0.414; P=0.001) and the predictors of valvular tenting at rest as inferior Ssr (β=–1.680; P<0.001), LV end-systolic volume index (β=0.022; P=0.001), and LV sphericity (β=3.886; P=0.012). Furthermore, dobutamine-induced reduction in ERO was predicted by reduction in valvular tenting (β=0.087; P<0.001) and increase in inferior Ssr (β=–0.082; P<0.001), and dobutamine-induced reduction in valvular tenting was predicted by increase in inferior Ssr (β=–0.860; P<0.001).

Conclusions—

Inferior regional myocardial dysfunction was quantitatively associated with mitral valvular tenting and FMR. Moreover, improvement with dobutamine of inferior myocardial contractile function attenuated valvular tenting and FMR. Inferior myocardial contractile function can affect the configuration of the mitral apparatus and predict FMR severity.

  K Hara , T Yokoo , R Kajita , T Onishi , S Yahata , K. M Peterson , K. U Torii and T. Kakimoto
 

Regulation of the number of cells is critical for development of multicellular organisms. During plant epidermal development, a protodermal cell first makes a fate decision of whether or not to be the meristemoid mother cell (MMC), which undergoes asymmetric cell division forming a meristemoid and its sister cell. The MMC-derived lineage produces all stomatal guard cells and a large proportion of non-guard cells. We demonstrate that a small secretory peptide, EPIDERMAL PATTERING FACTOR 2 (EPF2), is produced by the MMC and its early descendants, and negatively regulates the density of guard and non-guard epidermal cells. Our results suggest that EPF2 inhibits cells from adopting the MMC fate in a non-cell-autonomous manner, thus limiting the number of MMCs. This feedback loop is critical for regulation of epidermal cell density. The amino acid sequence of EPF2 resembles that of EPF1, which is known to control stomatal positioning. Over-expression of EPF1 also inhibits stomatal development, but EPF1 can act only on a later developmental process than EPF2. Overexpression and promoter swapping experiments suggested that the protein functions of EPF1 and EPF2, rather than the expression patterns of the genes, are responsible for the specific functions. Although targets of EPF1 and EPF2 are different, both EPF1 and EPF2 require common putative receptor components TOO MANY MOUTHS (TMM), ERECTA (ER), ERECTA LIKE 1 (ERL1) and ERL2 in order to function.

 
 
 
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