Yutaka Otsuji
University of Occupational and Environmental Health Japan
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Yutaka Otsuji.
Journal of the American College of Cardiology | 2002
Yutaka Otsuji; Toshiro Kumanohoso; Shiro Yoshifuku; Keiko Matsukida; Chihaya Koriyama; Akira Kisanuki; Shinichi Minagoe; Robert A. Levine; Chuwa Tei
OBJECTIVES We sought to test whether isolated mitral annular (MA) dilation can cause important functional mitral regurgitation (MR). BACKGROUND Mitral annular dilation has been considered a primary cause of functional MR. Patients with functional MR, however, usually have both MA dilation and left ventricular (LV) dilation and dysfunction. Lone atrial fibrillation (AF) can potentially cause isolated MA dilation, offering a unique opportunity to relate MA dilation to leaflet function. METHODS Mid-systolic MA area, MR fraction, LV volumes and papillary muscle (PM) leaflet tethering length were compared by echocardiography among 18 control subjects, 25 patients with lone AF and 24 patients with idiopathic or ischemic cardiomyopathy (ICM). RESULTS Patients with lone AF had a normal LV size and function but MA dilation (isolated MA dialtion) significant and comparable to that of patients with ICM (MA AREA: 8.0 +/- 1.2 vs. 11.6 +/- 2.3 vs. 12.5 +/- 2.9 cm(2) [control vs. lone AF vs. ICM]; p < 0.001 for both lone AF and ICM). However, patients with lone AF had only modest MR, compared with that of patients with ICM (MR fraction: -3 +/- 8% vs. 3 +/- 9% vs. 36 +/- 25%; p < 0.001 for patients with ICM). Multivariate analysis identified PM tethering length, not MA dilation, as an independent primary contributor to MR. CONCLUSIONS Isolated annular dilation does not usually cause moderate or severe MR. Important functional MR also depends on LV dilation and dysfunction, leading to an altered force balance on the leaflets, which impairs coaptation.
Circulation | 2006
Eiji Kuwahara; Yutaka Otsuji; Yoshifumi Iguro; Tetsuya Ueno; Fang Zhu; Naoko Mizukami; Kayoko Kubota; Kenichi Nakashiki; Toshinori Yuasa; Bo Yu; Takeshi Uemura; Kunitsugu Takasaki; Masaaki Miyata; Shuichi Hamasaki; Akira Kisanuki; Robert A. Levine; Ryuzo Sakata; Chuwa Tei
Background— Surgical annuloplasty can potentially hoist the posterior annulus anteriorly, exaggerate posterior leaflet (PML) tethering, and lead to recurrent ischemic/functional mitral regurgitation (MR). Characteristics of leaflet configurations in late postoperative MR were investigated. Methods and Results— In 30 patients with surgical annuloplasty for ischemic MR and 20 controls, the anterior leaflet (AML) and PML tethering angles relative to the line connecting annuli, posterior and apical displacement of the coaptation and the MR grade were measured by echocardiography before, early after, and late after surgery. Early after surgery, grade of MR and AML tethering generally decreased (P<0.01), whereas PML tethering significantly worsened (P<0.01). Nine of the 30 patients showed recurrent/persistent MR late after surgery. Compared with patients without late MR, those with the MR showed similar reduction in the annular area, significant re-increase in posterior displacement of the coaptation, and progressive worsening in PML tethering (P<0.05) late after surgery in comparison to the early phase. Both preoperative MR and late postoperative MR were significantly correlated with all tethering variables in univariate analysis. Although apical displacement of the coaptation was the primary determinant of preoperative MR (r2=0.60, P<0.0001), increased PML tethering was the primary determinant of late MR (r2=0.75, P<0.0001). Conclusions— Whereas both leaflets tethering is related to preoperative ischemic MR, both leaflets tethering but with predominant contribution from augmented and progressive PML tethering is related to recurrent/persistent ischemic/functional MR late after surgical annuloplasty.
Journal of the American College of Cardiology | 2001
Masakazu Imamura; Sadatoshi Biro; Takashi Kihara; Shiro Yoshifuku; Kunitsugu Takasaki; Yutaka Otsuji; Shinichi Minagoe; Yoshifumi Toyama; Chuwa Tei
OBJECTIVES We sought to determine whether sauna therapy, a thermal vasodilation therapy, improves endothelial function in patients with coronary risk factors such as hypercholesterolemia, hypertension, diabetes mellitus and smoking. BACKGROUND Exposure to heat is widely used as a traditional therapy in many different cultures. We have recently found that repeated sauna therapy improves endothelial and cardiac function in patients with chronic heart failure. METHODS Twenty-five men with at least one coronary risk factor (risk group: 38 +/- 7 years) and 10 healthy men without coronary risk factors (control group: 35 +/- 8 years) were enrolled. Patients in the risk group were treated with a 60 degrees C far infrared-ray dry sauna bath for 15 min and then kept in a bed covered with blankets for 30 min once a day for two weeks. To assess endothelial function, brachial artery diameter was measured at rest, during reactive hyperemia (flow-mediated endothelium-dependent dilation [%FMD]), again at rest and after sublingual nitroglycerin administration (endothelium-independent vasodilation [%NTG]) using high-resolution ultrasound. RESULTS The %FMD was significantly impaired in the risk group compared with the control group (4.0 +/- 1.7% vs. 8.2 +/- 2.7%, p < 0.0001), while %NTG was similar (18.7 +/- 4.2% vs. 20.4 +/- 5.1%). Two weeks of sauna therapy significantly improved %FMD in the risk group (4.0 +/- 1.7% to 5.8 +/- 1.3%, p < 0.001). In contrast, %NTG did not change after two weeks of sauna therapy (18.7 +/- 4.2% to 18.1 +/- 4.1%). CONCLUSIONS Repeated sauna treatment improves impaired vascular endothelial function in the setting of coronary risk factors, suggesting a therapeutic role for sauna treatment in patients with risk factors for atherosclerosis.
European Journal of Echocardiography | 2009
Hiromi Nakai; Masaaki Takeuchi; Tomoko Nishikage; Roberto M. Lang; Yutaka Otsuji
AIMS Early detection of diabetic heart disease is important for the timely interventions resulting in the prevention for the future development of heart failure. Subclinical left ventricular (LV) systolic dysfunction may be identified by a reduction in longitudinal function, which can be assessed using 2D speckle tracking echocardiography (STE). METHODS AND RESULTS To determine longitudinal, radial, and circumferential function, three LV short-axis and three LV apical views were acquired in 60 asymptomatic diabetic patients with normal LV ejection fraction (EF) and 25 age-matched healthy volunteers. Using 2D strain software, end-systolic longitudinal strain (LS), radial strain (RS), and circumferential strain (CS) were measured in 18 LV segments. No significant differences in LVEF were noted between two groups. Diabetic patients had more advanced diastolic dysfunction and increased LV mass compared with normal subjects. Basal, middle, and apical LSs were significantly lower in diabetic patients compared with control subjects, with 43% (26/60) of the diabetic patients showing abnormal global LS values (cut-off value: -17.2, mean - 2SD in control subjects). Basal RS and apical CS were also significantly lower in diabetic patients. Multivariate linear regression analysis showed that diabetic duration was the only independent confounder for the reduction of LS (t = 2.22, P = 0.0313). CONCLUSION In addition to diastolic dysfunction, subclinical LV longitudinal dysfunction is preferentially and frequently observed in asymptomatic diabetes patients with normal LVEF. The decrease in LS correlated with duration of diabetes. 2DSTE has the potential for detecting subclinical LV systolic dysfunction and might provide useful information of the risk stratification in an asymptomatic diabetic population.
Circulation | 2005
Fang Zhu; Yutaka Otsuji; Goichi Yotsumoto; Toshinori Yuasa; Takayuki Ueno; Bo Yu; Chihaya Koriyama; Shuichi Hamasaki; Sadatoshi Biro; Akira Kisanuki; Shinichi Minagoe; Robert A. Levine; Ryuzo Sakata; Chuwa Tei
Background—We hypothesized that surgical annuloplasty for ischemic mitral regurgitation (MR) that displaces the posterior annulus anteriorly can potentially augment posterior leaflet (PML) tethering, leading to persistent MR. Relationships between leaflet configurations and persistent ischemic MR after the annuloplasty were investigated. Methods and Results—In 31 patients with surgical annuloplasty for ischemic MR and 20 controls, posterior and apical displacement of the leaflet coaptation, the anterior leaflet (AML) and PML tethering angles relative to the line connecting annuli, coaptation length (CL), and the MR grade were quantified before and early after surgery in echocardiographic left ventricular long-axis views. Six of the 31 patients showed persistent MR despite annuloplasty. Compared with patients without persistent MR, those with MR showed no improvement in the left ventricular ejection fraction and systolic volume, similar reduction in the annular area, significant increase in posterior displacement of the coaptation (P<0.01), no improvement in AML tethering, greater worsening in PML tethering (P<0.01), and no increase in the CL. All tethering variables were significantly correlated with both preoperative and postoperative MR in univariate analysis, and reduced CL was the primary independent determinant of both preoperative and postoperative MR. Although increased AML tethering was the primary determinant of the preoperative CL (r2=0.46, P<0.0001), increased PML tethering was the primary determinant afterward (r2=0.60, P<0.0001). Conclusion—Although tethering of both leaflets is the major determinant of ischemic MR before surgical annuloplasty, both leaflets tethering but with predominant and augmented PML tethering is related to persistent ischemic MR after the annnuloplasty.
Oncogene | 2007
Tomonori Igarashi; Hiroaki Izumi; Takeshi Uchiumi; Kazuto Nishio; Tokuzo Arao; Mizuho Tanabe; Hidetaka Uramoto; Kenji Sugio; Kosei Yasumoto; Yasuyuki Sasaguri; Ke-Yong Wang; Yutaka Otsuji; Kimitoshi Kohno
The mechanisms underlying cellular drug resistance have been extensively studied, but little is known about its regulation. We have previously reported that activating transcription factor 4 (ATF4) is upregulated in cisplatin-resistant cells and plays a role in cisplatin resistance. Here, we find out a novel relationship between the circadian transcription factor Clock and drug resistance. Clock drives the periodical expression of many genes that regulate hormone release, cell division, sleep-awake cycle and tumor growth. We demonstrate that ATF4 is a direct target of Clock, and that Clock is overexpressed in cisplatin-resistant cells. Furthermore, Clock expression significantly correlates with cisplatin sensitivity, and that the downregulation of either Clock or ATF4 confers sensitivity of A549 cells to cisplatin and etoposide. Notably, ATF4-overexpressing cells show multidrug resistance and marked elevation of intracellular glutathione. The microarray study reveals that genes for glutathione metabolism are generally downregulated by the knockdown of ATF4 expression. These results suggest that the Clock and ATF4 transcription system might play an important role in multidrug resistance through glutathione-dependent redox system, and also indicate that physiological potentials of Clock-controlled redox system might be important to better understand the oxidative stress-associated disorders including cancer and systemic chronotherapy.
Journal of The American Society of Echocardiography | 2009
Kyoko Okamatsu; Masaaki Takeuchi; Hiromi Nakai; Tomoko Nishikage; Ivan S. Salgo; Stephane Husson; Yutaka Otsuji; Roberto M. Lang
BACKGROUND Aging affects left atrial (LA) function, which can be assessed by two-dimensional (2D) speckle tracking echocardiography (STE). The aim of this study was to determine (1) the feasibility and accuracy of measuring LA volume with 2DSTE and (2) the effects of aging on LA function. METHODS 2DSTE of the LA was acquired from the apical 4-chamber view (frame rate: 63 +/- 11 /sec, iE33) using prototype speckle tracking software (QLAB, Philips Medical Systems, Andover, MA) in 140 healthy volunteers (3-79 years, 74 men). LA wall was tracked on a frame-by-frame basis, and LA volume waveforms were generated. Maximum LA volume (LAVmax) and minimal LA volume (LAVmin), and the LA volume before atrial contraction (LAVpre-a) were measured. Passive emptying percent of total emptying (LA conduit function) and active emptying percent of total emptying (booster function) were calculated as ([LAVmax-LAVpre-a]/[LAVmax-LAVmin]) x 100 and ([LAVa-LAVmin]/[LAVmax-LAVmin]) x 100. RESULTS Adequate LA volume waveforms were obtained in all subjects. A good correlation was obtained between speckle tracking-derived LA volume measurements and manually traced LA volume measurements of the identical 2D image (LAVmax: r = 0.93, P <.001, LAVmin: r = 0.88, P <.001, LAVpre-a: r = 0.92, P <.001). Passive and active emptying indices had a significant age dependency (r = 0.80, P <.001). Overall, passive emptying accounted for 67% of the total LA emptying ranging from 83% in the youngest to 42% in the oldest decade. CONCLUSION Aging significantly affects LA conduit and booster function. 2DSTE can effectively and easily measure LA volume and has a potential for the noninvasive assessment of LA function.
Journal of Cardiology | 2008
Yutaka Otsuji; Robert A. Levine; Masaaki Takeuchi; Ryuzo Sakata; Chuwa Tei
The basic mechanism of ischemic mitral regurgitation (MR) is believed augmented leaflet tethering due to the outward displacement of the papillary muscles by left ventricular (LV) remodeling or dilatation. Annular dilatation and LV dysfunction may not be the central mechanism, but contribute to the development of MR in the presence of augmented tethering. Papillary muscle dysfunction was initially expected to cause leaflet prolapse and MR. However, multiple studies have confirmed that papillary muscle dysfunction per se does not usually cause ischemic MR and recent studies further suggest that papillary muscle dysfunction may occasionally attenuate tethering and MR. Although surgical annuloplasty is usually effective to treat ischemic MR, occasional patients with persistent or recurrent ischemic MR after surgical ring annuloplasty even with advanced downsizing suggest the need for approaches to address tethering. Finally, leaflet tethering in patients with ischemic MR can be heterogeneous, indicating the need for individualized approaches to correct ischemic MR in affected patients.
European Journal of Heart Failure | 2011
Nobuhiko Haruki; Masaaki Takeuchi; Kyoko Kaku; Hidetoshi Yoshitani; Hiroshi Kuwaki; Masahito Tamura; Haruhiko Abe; Masahiro Okazaki; Akizumi Tsutsumi; Yutaka Otsuji
The aim of this study was to determine differences in the acute and chronic impact of adaptive servo‐ventilation (ASV) on left chamber geometry and function in patients with chronic heart failure (CHF).
British Journal of Pharmacology | 2008
Hiroko Takemasa; Toshihisa Nagatomo; Haruhiko Abe; Kazunobu Kawakami; T Igarashi; Takuo Tsurugi; Narutoshi Kabashima; Masahito Tamura; Masahiro Okazaki; Brian P. Delisle; Craig T. January; Yutaka Otsuji
Many drugs associated with acquired long QT syndrome (LQTS) directly block human ether‐a‐go‐go‐related gene (hERG) K+ channels. Recently, disrupted trafficking of the hERG channel protein was proposed as a new mechanism underlying LQTS, but whether this defect coexists with the hERG current block remains unclear. This study investigated how ketoconazole, a direct hERG current inhibitor, affects the trafficking of hERG channel protein.
Collaboration
Dive into the Yutaka Otsuji's collaboration.
University of Occupational and Environmental Health Japan
View shared research outputsUniversity of Occupational and Environmental Health Japan
View shared research outputs