Browsing by Author "Ogawa, Masahiro"

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    Constitutive overexpression of periostin delays wound healing in mouse skin
    (Wiley, 2018) Nunomura, Satoshi; Nanri, Yasuhiro; Ogawa, Masahiro; Arima, Kazuhiko; Mitamura, Yasutaka; Yoshihara, Tomohito; Hasuwa, Hidetoshi; Conway, Simon J.; Izuhara, Kenji; Pediatrics, School of Medicine
    Periostin is a matricellular protein involved in development, maintenance and regulation of tissues and organs via by binding to cell surface integrin receptors. Pathologically, periostin plays an important role in the process of wound healing: as a deficiency of the Postn gene delays wound closure and periostin is consistently upregulated in response to injury and skin diseases. However, the functional role of elevated periostin in the process of wound healing has not been tested. In this study, we generated Postn-transgenic mice under the control of the CAG promoter/enhancer to investigate the effects of constitutive overexpression of full length periostin during its pathophysiological roles. Transgenic mice showed significant overexpression of periostin in skin, lung, and heart, but no morphological changes were observed. However, when these transgenic mice were injured, periostin overexpression delayed the closure of excisional wounds. Expression of IL-1β and TNFα, pro-inflammatory cytokines important for wound healing, was significantly decreased in the transgenic mice, prior to delayed healing. Infiltration of neutrophils and macrophages, the main sources of IL-1β and TNFα, was also downregulated in the transgenic wound sites. From these data, we conclude that enforced expression of periostin delays wound closure due to reduced infiltration of neutrophils and macrophages followed by downregulation of IL-1β and TNFα expression. This suggests that regulated spatiotemporal expression of periostin is important for efficient wound healing and that constitutive periostin overexpression interrupts the normal process of wound closure.
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    Effects of Stellate Ganglion Cryoablation on Subcutaneous Nerve Activity and Atrial Tachyarrhythmias in a Canine Model of Pacing-Induced Heart Failure
    (Elsevier, 2018-05) Shelton, Richard S.; Ogawa, Masahiro; Lin, Hongbo; Shen, Changyu; Wong, Johnson; Lin, Shien-Fong; Chen, Peng-Sheng; Everett, Thomas H.; Medicine, School of Medicine
    OBJECTIVES: This study aimed to test the hypothesis that subcutaneous nerve activity (SCNA) can adequately estimate the cardiac sympathetic tone and the effects of cryoablation of the stellate ganglion in dogs with pacing-induced heart failure (HF). BACKGROUND: Recording of SCNA is a new method to estimate sympathetic tone in dogs. HF is known to increase sympathetic tone and atrial arrhythmias. METHODS: Twelve dogs with pacing-induced HF were studied using implanted radiotransmitters to record the stellate ganglia nerve activity (SGNA), vagal nerve activity, and SCNA. Of these, 6 dogs (ablation group) underwent bilateral stellate ganglia cryoablation before the rapid ventricular pacing; the remaining 6 dogs (control group) had rapid ventricular pacing only. In both groups, SCNA was compared with SGNA and the occurrence of arrhythmias. RESULTS: SCNA invariably increased before the 360 identified atrial tachyarrhythmia episodes in the 6 control dogs before and after HF induction. SCNA and SGNA correlated in all dogs with an average correlation coefficient of 0.64 (95% confidence interval: 0.58 to 0.70). Cryoablation of bilateral stellate ganglia significantly reduced SCNA from 0.34 ± 0.033 μV to 0.25 ± 0.028 μV (p = 0.03) and eliminated all atrial tachyarrhythmias. CONCLUSIONS: SCNA can be used to estimate cardiac sympathetic tone in dogs with pacing-induced HF. Cryoablation of the stellate ganglia reduced SCNA and arrhythmia vulnerability.
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    Oscillatory behavior of P wave duration and PR interval in experimental congestive heart failure: a preliminary study
    (IOP Publishing, 2018-03) Piccirillo, Gianfranco; Magrì, Damiano; D'Alessandro, Gaetana; Fiorucci, Claudia; Moscucci, Federica; Iorio, Claudia Di; Mastropietri, Fabiola; Parrotta, Ilaria; Ogawa, Masahiro; Lin, Shien-Fong; Chen, Peng-Sheng; Medicine, School of Medicine
    Objective: The relationship between the autonomic nervous system (ANS) modulation of the sinus node and heart rate variability has been extensively investigated. The current study sought to evaluate, in an animal experimental model of pacing-induced tachycardia congestive heart failure (CHF), a possible ANS influence on the P wave duration and PR interval oscillations. Approach: Short-term (5 min) time and frequency domain analysis has been obtained in six dogs for the following electrocardiographic intervals: P wave duration (P), from the onset to peak of P wave (P p), from the onset of P wave to the q onset (PR) and from the end of P wave to the onset of q wave (P e R). Direct vagal nerve activity (VNA), stellate ganglion nerve activity (SGNA) and electrocardiogram (ECG) intervals have been evaluated contextually by implantation of three bipolar recording leads. Main results: At the baseline, multiple regression analysis pointed out that VNA was strongly positively associated with the standard deviation of PP and P e R intervals (r 2:0.997, p < 0.05). The same variable was also positively associated with high-frequency (HF) of P expressed in normalized units, of P p, and of P e R (b: 0.001) (r 2: 0.993; p < 0.05). During CHF, most of the time and frequency domain variability significantly decreased from 20% to 50% in comparison to the baseline values (p < 0.05) and SGNA correlated inversely with the low frequency (LF) obtained from P e R (p < 0.05) and PR (p < 0.05) (r 2:0.899, p < 0.05). LF components, expressed in absolute and normalized power, obtained from all studied intervals, were reduced significantly during CHF. Any difference between the RR and PP spectral components was observed. Significance: The data showed a significant relationship between ANS and atrial ECG variables, independent of the cycle duration. In particular, the oscillations were vagal mediated at the baseline, while sympathetic mediated during CHF. Whereas P wave variability might have a clinical utility in CHF management, it needs to be addressed in specific studies.