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Search Results: 1 - 10 of 838 matches for " Shigeru Miyagawa "
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From bench to bedside, work in cell-based myocardial regeneration therapy  [PDF]
Shigeru Miyagawa, Yoshiki Sawa
Journal of Biomedical Science and Engineering (JBiSE) , 2014, DOI: 10.4236/jbise.2014.72012

In clinical cellular cardiomyoplasty, bone marrow cells and myoblasts are introduced mainly to ischemic cardiomyopathy tissue via several cell delivery systems, such as needle injection or catheter. These clinical studies have demonstrated the safety and feasibility of this technique, but its effectiveness for treating heart failure, especially in the long term, is still under discussion. Neither of these cell types can differentiate into cardiomyocytes; rather, they improve the failing heart mainly by the paracrine effects of some cytokines, such as Hepatocyte growth factor (HGF) and Vascular endothelial growth factor (VEGF). Thus, many researchers have a great interest in stem cells, which exist in bone marrow, circulating blood, atrium, and adipose tissue, and can differentiate into cardiomyocytes. Although several stem cells with the potential to differentiate into various cell types have been reported, few can differentiate into cardiomyocytes. Moreover, beating cells that can demonstrate synchronized contraction with native cardiomyocytes are critical for the complete repair of severe heart failure. Therefore, stem cells with a high differentiation capacity should be explored for the goal of completely repairing severely damaged myocardium. In this review, we summarize the clinical protocols and basic experiments for cellular cardiomyoplasty using bone marrow cells, myoblasts, and other stem cells.

Activated Protein C Has a Protective Effect against Myocardial I/R Injury by Improvement of Endothelial Function and Activation of AKT1
Yoshito Maehata, Shigeru Miyagawa, Yoshiki Sawa
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038738
Abstract: Objectives Activated protein C (APC) has a protective efficacy against ischemia-reperfusion (I/R) injury in several organs. The objective of this study was to investigate effect of APC in myocardium with possible mechanism. Methods We used regional and global myocardial I/R injury models of rats. They consisted of I/R injuries (1) by ligation of left coronary artery, or (2) using Langendorff apparatus. Langendorff was used to focus the mechanism of APC excluding coagulation cascade in a working heart. Each experiment had an APC group (n = 10) and a control group with normal saline (n = 10). Injections of these solutions into rats were performed 30 minutes before the planned-I/R injury. Cardiac performance after the procedure was evaluated by echocardiography or indices with Langendorff apparatus. Coronary flow (CF) was measured in the global I/R injury model. Western blotting was performed to detect the change of AKT1 signal in myocardium after global I/R injury. Results LV function improved significantly in the APC group: %EF at 2 weeks after procedure, 70.8%±4.5% vs. 56.5%±0.7%; APC vs. control; p<0.01. Percent LV development pressure (LVDP) also improved in the APC group significantly, 88.8%±45.3% vs. 28.1%±15.4%; APC vs. control; p<0.01. In APC group, %CF improved significantly, 88.5%±15.8% vs. 65.0%±13.4%; APC vs. control; p<0.01. It was enhanced significantly when acetylcholine was administered; % CF: 103.5%±9.9% vs. 87.0%±12.1%; APC vs. control; p<0.05. Western blotting revealed that APC significantly induced activation of phosphorylated AKT1 in myocardium (p<0.05). Conclusions APC has a novel effect to protect myocardium and cardiac performance against I/R injury through improvement of endothelial function and activation of AKT1.
Three Dimensional Gait Analysis Using Wearable Acceleration and Gyro Sensors Based on Quaternion Calculations
Shigeru Tadano,Ryo Takeda,Hiroaki Miyagawa
Sensors , 2013, DOI: 10.3390/s130709321
Abstract: This paper proposes a method for three dimensional gait analysis using wearable sensors and quaternion calculations. Seven sensor units consisting of a tri-axial acceleration and gyro sensors, were fixed to the lower limbs. The acceleration and angular velocity data of each sensor unit were measured during level walking. The initial orientations of the sensor units were estimated using acceleration data during upright standing position and the angular displacements were estimated afterwards using angular velocity data during gait. Here, an algorithm based on quaternion calculation was implemented for orientation estimation of the sensor units. The orientations of the sensor units were converted to the orientations of the body segments by a rotation matrix obtained from a calibration trial. Body segment orientations were then used for constructing a three dimensional wire frame animation of the volunteers during the gait. Gait analysis was conducted on five volunteers, and results were compared with those from a camera-based motion analysis system. Comparisons were made for the joint trajectory in the horizontal and sagittal plane. The average RMSE and correlation coefficient (CC) were 10.14 deg and 0.98, 7.88 deg and 0.97, 9.75 deg and 0.78 for the hip, knee and ankle flexion angles, respectively.
Distribution of Deviation Distance to Alternative Fuel Stations  [PDF]
Masashi Miyagawa
American Journal of Operations Research (AJOR) , 2013, DOI: 10.4236/ajor.2013.33033
Abstract: This paper derives the distribution of the deviation distance to visit an alternative fuel station. Distance is measured as the Euclidean distance on a continuous plane. The distribution explicitly considers the vehicle range and whether the round trip between origin and destination can be made. Three cases are examined: fuel is available at both origin and destination, fuel is available at either origin or destination, and fuel is available at neither origin nor destination. The analytical expressions for the distribution demonstrate how the vehicle range, the shortest distance, and the refueling availability at origin and destination affect the deviation distance. The distribution will thus be useful to estimate the number of vehicles refueled at a station.

Sustained-Release Delivery of Prostacyclin Analogue Enhances Bone Marrow-Cell Recruitment and Yields Functional Benefits for Acute Myocardial Infarction in Mice
Yukiko Imanishi, Shigeru Miyagawa, Satsuki Fukushima, Kazuhiko Ishimaru, Nagako Sougawa, Atsuhiro Saito, Yoshiki Sakai, Yoshiki Sawa
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069302
Abstract: Background A prostacyclin analogue, ONO-1301, is reported to upregulate beneficial proteins, including stromal cell derived factor-1 (SDF-1). We hypothesized that the sustained-release delivery of ONO-1301 would enhance SDF-1 expression in the acute myocardial infarction (MI) heart and induce bone marrow cells (BMCs) to home to the myocardium, leading to improved cardiac function in mice. Methods and Results ONO-1301 significantly upregulated SDF-1 secretion by fibroblasts. BMC migration was greater to ONO-1301-stimulated than unstimulated conditioned medium. This increase was diminished by treating the BMCs with a CXCR4-neutralizing antibody or CXCR4 antagonist (AMD3100). Atelocollagen sheets containing a sustained-release form of ONO-1301 (n = 33) or ONO-1301-free vehicle (n = 48) were implanted on the left ventricular (LV) anterior wall immediately after permanent left-anterior descending artery occlusion in C57BL6/N mice (male, 8-weeks-old). The SDF-1 expression in the infarct border zone was significantly elevated for 1 month in the ONO-1301-treated group. BMC accumulation in the infarcted hearts, detected by in vivo imaging after intravenous injection of labeled BMCs, was enhanced in the ONO-1301-treated hearts. This increase was inhibited by AMD3100. The accumulated BMCs differentiated into capillary structures. The survival rates and cardiac function were significantly improved in the ONO-1301-treated group (fractional area change 23±1%; n = 22) compared to the vehicle group (19±1%; n = 20; P = 0.004). LV anterior wall thinning, expansion of infarction, and fibrosis were lower in the ONO-1301-treated group. Conclusions Sustained-release delivery of ONO-1301 promoted BMC recruitment to the acute MI heart via SDF-1/CXCR4 signaling and restored cardiac performance, suggesting a novel mechanism for ONO-1301-mediated acute-MI heart repair.
Recent Clinical and Experimental Advances in Atrial Fibrillation
Shigeru Miyagawa,Taichi Sakaguchi,Hiroyuki Nishi,Yasushi Yoshikawa,Satsuki Fukushima,Shunsuke Saito,Yoshiki Sawa
ISRN Cardiology , 2011, DOI: 10.5402/2011/958189
Abstract: Atrial fibrillation (AF) is the most common arrhythmia in clinical settings (Fuster et al., 2001), and it is often associated with congestive heart diseases (Issac et al., 2007). Many studies in both laboratory and clinical settings have sought to analyze the mechanisms of AF, develop treatments based on these mechanisms, and examine atrial remodeling in chronic AF. The aim of this paper is to analyze recent findings regarding the atrial remodeling that occurs in AF. In particular, we will describe the electrical and structural changes that involve atrial myocytes and the extracellular matrix. We will also describe the general classification and basic pathophysiology of AF and its surgical treatments. 1. Classification of AF The joint American College of Cardiology/American Heart Association/European Society of Cardiology proposed a classification system for AF to simplify its heterogeneous clinical aspects and clarify its clinical states [1]. Patients are initially classified as having a “first detected episode of AF,” when AF is confirmed by clinicians. If a patient has two or more episodes, the AF is classified as recurrent. Recurrent AF is designated as paroxysmal or persistent. Paroxysmal AF is an episode that generally continues for 7 or fewer days and terminates on its own. Persistent AF usually continues for more than 7 days without self-terminating and requires clinicians to terminate it using pharmacological treatment or electrical cardioversion to restore the sinus rhythm. Permanent AF is a situation in which the sinus rhythm cannot be sustained after cardioversion, and further medical efforts are required to restore it. 2. Pathophysiology of AF 2.1. The Basic Mechanisms of AF Many researchers agree that inflammation [2], neurohormonal disorders [3], cardiovascular diseases such as valvular diseases [4], diabetes, hypertension, congestive heart failure, myocardial infarction [5], and genetic factors [6] are “modulating factors” that can induce AF. Classically, AF mechanisms are described by the concept of atrial ectopic foci [7], which fire spontaneously in the atrium, a single reentry circuit, or multiple reentry circuits [8, 9]. The surgical maze procedure is designed to block the multiple reentry circuits and create an isolated electrical lesion in the atrium [10]. Haissaguerre et al. reported that triggers located in the pulmonary veins initiate most cases of paroxysmal AF [7], while in some cases the trigger, such as a venous remnant in the left atrium (LA) and superior vena cavae, occurs outside the pulmonary vein. This finding supports
Impact of microRNA Expression in Human Atrial Tissue in Patients with Atrial Fibrillation Undergoing Cardiac Surgery
Hiroyuki Nishi, Taichi Sakaguchi, Shigeru Miyagawa, Yasushi Yoshikawa, Satsuki Fukushima, Shunsuke Saito, Takayoshi Ueno, Toru Kuratani, Yoshiki Sawa
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073397
Abstract: Background Although microRNA (miRNA) regulates initiation and/or progression of atrial fibrillation (AF) in canine AF models, the underlying mechanism in humans remains unclear. We speculated that certain miRNAs in atrial tissue are related to AF, and evaluated the relationship of miRNA expression in human atrial tissue in cardiac surgery patients. Methods Right atrial tissues from 29 patients undergoing cardiovascular surgery were divided into 3 groups [A: chronic AF or unsuccessful maze, n=6; B: successful maze, n=10; C: sinus rhythm (SR) n=13]. miRNA expression was determined using high density microarrays and with Reverse transcriptase-polymerase chain reaction (RT-PCR). Fibrosis was examined using Masson trichrome staining. Results miRNA microarray analysis showed elevated miRNA-21, miRNA-23b, miRNA-199b, and miRNA-208b in AF as compared to SR groups. RT-PCR showed elevated miRNA-21 (1.9-fold) and miRNA-208b (4.2-fold) in AF as compared to the SR groups. miRNA-21 expression increased from Group C to A (A: 2.1-fold, B: 1.8-fold, C: 1.0-fold). Fibrosis increased from C to A (A: 43.0±12.9%, B: 21.3±6.1%, C: 11.9±3.1%). Percent fibrosis and miRNA-21 expression were correlated (r=0.508, p<0.05). The plasma levels of miRNA-21 in AF patients was significantly decreased as compared to the healthy volunteers (p<0.05). Conclusion The expression of miRNA-21 in human atrial tissue was found to be related to atrial fibrosis and might affect AF occurrence, indicating its usefulness as a biomarker for cardiac surgery management.
Seismic Damage Estimation of an Actual Reinforced Concrete Structure Using Subset MCMC  [PDF]
Shigeru Kushiyama
Open Journal of Civil Engineering (OJCE) , 2013, DOI: 10.4236/ojce.2013.33016

To estimate seismic damage of structures under strong motions is very important to know true safety of structures. However, we have to deal with very small failure probability issue to investigate quantitatively. If we use standard MCS (Monte Calro Simulation) to discuss failure probability, e.g., 1 × 10-6 order, since we have to execute nonlinear dynamic response analyses of approximate 107 times, it is not realistic. Recently, a subset simulation, which reduces the computation time by replacing small failure probability into the product of conditional failure probabilities, was proposed. In this study, the subset simulation is applied to estimate failure probability of an actual reinforced concrete building with 11 stories, and discuss the safety of the structure by checking with design criteria.

Spin-Magnetic Moment of Dirac Electron, and Role of Zitterbewegung  [PDF]
Shigeru Sasabe
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.57064

The spin-magnetic moment of the electron is revisited. In the form of the relativistic quantum mechanics, we calculate the magnetic moment of Dirac electron with no orbital angular-momentum. It is inferred that obtained magnetic moment may be the spin-magnetic moment, because it is never due to orbital motion. A transition current flowing from a positive energy state to a negative energy state in Dirac Sea is found. Application to the band structure of semiconductor is suggested.

Analytic properties of generalized Mordell-Tornheim type of multiple zeta-functions and L-functions
Takashi Miyagawa
Mathematics , 2015,
Abstract: Analytic properties of three types of multiple zeta functions, that is, the Euler-Zagier type, the Mordell-Tornheim type and the Apostol-Vu type have been studied by a lot of authors. In particular, in the study of multiple zeta functions of the Apostol-Vu type, a generalized multiple zeta function, including both the Euler-Zagier type and the Apostol-Vu type, was introduced.In this paper, similarly we consider generalized multiple zeta-functions and $ L $-functions, which include both the Euler-Zagier type and the Mordell-Tornheim type as special cases.We prove the meromorphic continuation to the multi-dimensional complex space, and give the results on possible singularities.
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