Low‐intensity pulsed ultrasound ameliorates angiotensin II-induced cardiac fibrosis by alleviating inflammation via a caveolin-1-dependent pathway

Objective:Cardiac hypertrophy and fibrosis are major pathological manifestations observed in left ventricular remodeling induced by angiotensin II(AngII).Low-intensity pulsed ultrasound(LIPUS)has been reported to ameliorate cardiac dysfunction and myocardial fibrosis in myocardial infarction(MI)through mechano-transduction and its downstream pathways.In this study,we aimed to investigate whether LIPUS could exert a protective effect by ameliorating AngII-induced cardiac hypertrophy and fibrosis and if so,to further elucidate the underlying molecular mechanisms.Methods:We used AngII to mimic animal and cell culture models of cardiac hypertrophy and fibrosis.LIPUS irradiation was applied in vivo for 20 min every 2 d from one week before mini-pump implantation to four weeks after mini-pump implantation,and in vitro for 20 min on each of two occasions 6 h apart.Cardiac hypertrophy and fibrosis levels were then evaluated by echocardiographic,histopathological,and molecular biological methods.Results:Our results showed that LIPUS could ameliorate left ventricular remodeling in vivo and cardiac fibrosis in vitro by reducing AngII-induced release of inflammatory cytokines,but the protective effects on cardiac hypertrophy were limited in vitro.Given that LIPUS increased the expression of caveolin-1 in response to mechanical stimulation,we inhibited caveolin-1 activity with pyrazolopyrimidine 2(pp2)in vivo and in vitro.LIPUS-induced downregulation of inflammation was reversed and the anti-fibrotic effects of LIPUS were absent.Conclusions:These results indicated that LIPUS could ameliorate AngII-induced cardiac fibrosis by alleviating inflammation via a caveolin-1-dependent pathway,providing new insights for the development of novel therapeutic apparatus in clinical practice.

Image Segmentation via Fischer-Burmeister Total Variation and Thresholding

Image segmentation is a significant problem in image processing.In this paper,we propose a new two-stage scheme for segmentation based on the Fischer-Burmeister total variation(FBTV).The first stage of our method is to calculate a smooth solution from the FBTV Mumford-Shah model.Furthermore,we design a new difference of convex algorithm(DCA)with the semi-proximal alternating direction method of multipliers(sPADMM)iteration.In the second stage,we make use of the smooth solution and the K-means method to obtain the segmentation result.To simulate images more accurately,a useful operator is introduced,which enables the proposed model to segment not only the noisy or blurry images but the images with missing pixels well.Experiments demonstrate the proposed method produces more preferable results comparing with some state-of-the-art methods,especially on the images with missing pixels.