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Cellular mechanism of cardiac alternans: an unresolved chicken or egg problem
Yun-liang Zang, Ling Xia
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 201-211.
https://doi.org/10.1631/jzus.B1300177
T-wave alternans, a specific form of cardiac alternans, has been associated with the increased susceptibility to cardiac arrhythmias and sudden cardiac death (SCD). Plenty of evidence has related cardiac alternans at the tissue level to the instability of voltage kinetics or Ca2+ handling dynamics at the cellular level. However, to date, none of the existing experiments could identify the exact cellular mechanism of cardiac alternans due to the bi-directional coupling between voltage kinetics and Ca2+ handling dynamics. Either of these systems could be the origin of alternans and the other follows as a secondary change, therefore making the cellular mechanism of alternans a difficult chicken or egg problem. In this context, theoretical analysis combined with experimental techniques provides a possibility to explore this problem. In this review, we will summarize the experimental and theoretical advances in understanding the cellular mechanism of alternans. We focus on the roles of action potential duration (APD) restitution and Ca2+ handling dynamics in the genesis of alternans and show how the theoretical analysis combined with experimental techniques has provided us a new insight into the cellular mechanism of alternans. We also discuss the possible reasons of increased propensity for alternans in heart failure (HF) and the new possible therapeutic targets. Finally, according to the level of electrophysiological recording techniques and theoretical strategies, we list some critical experimental or theoretical challenges which may help to determine the origin of alternans and to find more effective therapeutic targets in the future.
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Deregulation of microRNA expression in thyroid tumors
Zi-ming Yuan, Zhi-li Yang, Qi Zheng
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 212-224.
https://doi.org/10.1631/jzus.B1300192
MicroRNAs (miRNAs or miRs) are endogenous non-coding RNAs that negatively regulate gene expression by binding to the 3\' non-coding regions of target mRNAs, resulting in their cleavage or blocking their translation. miRNAs may have an impact on cell differentiation, proliferation, and survival, and their deregulation can be inclined to diseases and cancers, including thyroid tumors. The purpose of this review is to summarize the existing findings of deregulated miRNAs in different types of thyroid tumors and to exhibit their potential target genes, especially to demonstrate those involved in tumor invasion and metastasis. In addition, new findings of circulating miRNA expression profiles, single nucleotide polymorphism (SNP) in thyroid tumors, and the correlation of somatic mutations with deregulated miRNA expression in thyroid tumors were all included in this review.
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Fibroblast proliferation alters cardiac excitation conduction and contraction: a computational study
He-qing Zhan, Ling Xia, Guo-fa Shou, Yun-liang Zang, Feng Liu, Stuart Crozier
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 225-242.
https://doi.org/10.1631/jzus.B1300156
In this study, the effects of cardiac fibroblast proliferation on cardiac electric excitation conduction and mechanical contraction were investigated using a proposed integrated myocardial-fibroblastic electromechanical model. At the cellular level, models of the human ventricular myocyte and fibroblast were modified to incorporate a model of cardiac mechanical contraction and cooperativity mechanisms. Cellular electromechanical coupling was realized with a calcium buffer. At the tissue level, electrical excitation conduction was coupled to an elastic mechanics model in which the finite difference method (FDM) was used to solve electrical excitation equations, and the finite element method (FEM) was used to solve mechanics equations. The electromechanical properties of the proposed integrated model were investigated in one or two dimensions under normal and ischemic pathological conditions. Fibroblast proliferation slowed wave propagation, induced a conduction block, decreased strains in the fibroblast proliferous tissue, and increased dispersions in depolarization, repolarization, and action potential duration (APD). It also distorted the wave-front, leading to the initiation and maintenance of re-entry, and resulted in a sustained contraction in the proliferous areas. This study demonstrated the important role that fibroblast proliferation plays in modulating cardiac electromechanical behaviour and which should be considered in planning future heart-modeling studies.
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Estrogen receptor α gene PvuII polymorphism and coronary artery disease: a meta-analysis of 21 studies
Jie Ding, Hui Xu, Xiang Yin, Fu-rong Zhang, Xiao-ping Pan, Yi-an Gu, Jun-zhu Chen, Xiao-gang Guo
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 243-255.
https://doi.org/10.1631/jzus.B1300220
The association between the estrogen receptor α gene (ESR1) PvuII polymorphism (c.454-397T>C) and coronary artery disease (CAD) is controversial. Thus, we conducted a meta-analysis to evaluate the relationship. Data were collected from 21 studies encompassing 9926 CAD patients and 16710 controls. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the relationship between PvuII polymorphism and CAD. The polymorphism in control populations in all studies followed Hardy-Weinberg equilibrium. We found a significant association between ESR1 PvuII polymorphism and CAD risk in all subjects. When the data were stratified by region, a significant association between ESR1 PvuII polymorphism and CAD risk was observed in Asian populations but not in Western populations. The current study suggests that ESR1 PvuII polymorphism has an important role in CAD susceptibility.
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Association of matrix metalloproteinase-9 C1562T polymorphism and coronary artery disease: a meta-analysis
Xiao Wang, Lei-zhi Shi
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 256-263.
https://doi.org/10.1631/jzus.B1300088
Objective: Many investigations have studied the associations between matrix metalloproteinase-9 (MMP-9) C1562T polymorphisms and coronary artery disease (CAD). However, the conclusions of these studies were inconsistent. Therefore, this study was aimed at clarifying the association between MMP-9 C1562T polymorphisms and CAD in a large-scale meta-analysis. Methods: The PubMed and Embase databases were retrieved to collect all publications on the association between MMP-9 C1562T polymorphisms and CAD. Then the odd ratios (ORs) and 95% confidence intervals (95% CIs) for C1562T TT+TC versus CC genotype between CAD and the control groups were evaluated. Subgroup analysis was also performed according to different races. The meta-analysis was performed by Stata 10.0. Results: Sixteen case-control studies were included in our meta-analysis, involving 11032 CAD patients and 4628 non-CAD controls. Compared with C allele carriers, East Asian T allele carriers TT+TC had a significantly higher risk of CAD (OR=1.43; 95% CI: 1.03–1.99; P=0.031); however, there were no significant associations in Western populations (OR=1.06; 95% CI: 0.96–1.18; P=0.240) or West Asians (OR=1.13; 95% CI: 0.75–1.70; P=0.565). When further analyzing the association between C1562T polymorphisms and myocardial infarction (MI, the most serious type of CAD), the risk of TT+TC genotype versus CC genotype for MI was significantly higher for the overall (OR=1.21; 95% CI: 1.04–1.40; P=0.012) and for East Asians (OR=1.58; 95% CI: 1.26–1.97; P=0.000) but not in Western populations (OR=1.12; 95% CI: 0.99–1.26; P=0.078). Conclusions: Our meta-analysis suggested an obvious ethnic difference in the association between MMP-9 C1562T polymorphisms and CAD. MMP-9 C1562T polymorphism was significantly related to CAD in East Asians. However, no significant associations were observed in either West Asians or Western populations.
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Family-based association study of ZNF533, DOCK4 and IMMP2L gene polymorphisms linked to autism in a northeastern Chinese Han population
Shuang Liang, Xue-lai Wang, Ming-yang Zou, Han Wang, Xue Zhou, Cai-hong Sun, Wei Xia, Li-jie Wu, Takashi X. Fujisawa, Akemi Tomoda
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 264-271.
https://doi.org/10.1631/jzus.B1300133
Objective: A study in a Caucasian population has identified two single-nucleotide polymorphisms (SNPs) in ZNF533, one in DOCK4, and two in IMMP2L, which were all significantly associated with autism. They are located in AUTS1 and AUTS5, which have been identified as autism susceptibility loci in several genome-wide screens. The present study aimed to investigate whether ZNF533, DOCK4, and IMMP2L genes are also associated with autism in a northeastern Chinese Han population. Methods: We performed a similar association study using families with three individuals (one autistic child and two unaffected parents). A family-based transmission disequilibrium test (TDT) was used to analyze the results. Results: There were significant associations between autism and the two SNPs of ZNF533 gene (rs11885327: χ2=4.5200, P=0.0335; rs1964081: χ2=4.2610, P=0.0390) and the SNP of DOCK4 gene (rs2217262: χ2=5.3430, P=0.0208). Conclusions: Our data suggest that ZNF533 and DOCK4 genes are linked to a predisposition to autism in the northeastern Chinese Han population.
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Buyang Huanwu decoction increases angiopoietin-1 expression and promotes angiogenesis and functional outcome after focal cerebral ischemia
Jian Shen, Yu Zhu, Hai Yu, Zuo-xu Fan, Feng Xiao, Pan Wu, Qi-hui Zhang, Xiao-xing Xiong, Jian-wei Pan, Ren-ya Zhan
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 272-280.
https://doi.org/10.1631/jzus.B1300166
Buyang Huanwu decoction (BYHWD), a traditional Chinese herbal prescription, has been widely used clinically to treat stroke in China for hundreds of years; however, the mechanisms of this drug for stroke treatment are still unclear. This study aims to observe the cerebral angiogenesis effects of BYHWD on chronic brain injury after focal cerebral ischemia in rats and to explore its possible mechanisms. The ischemia was induced by occlusion of the right middle cerebral artery for 90 min. BYHWD (12.5 and 25.0 g/(kg∙d), equivalent to the dry weight of the raw materials) was orally administered twice a day beginning 2 h after surgery. BYHWD significantly attenuated the neurological dysfunction, infarct volume, and brain atrophy after ischemia. There was a significant increase in the microvessel density, as assessed by immunofluorescence CD31, and a significant increase in angiopoietin-1 (Ang-1) in the penumbra areas of the rats was shown by immunohistochemical staining and Western blotting. The results indicate that the neurorestorative effects of BYHWD are associated with angiogenesis and the enhancement of the expressions of Ang-1 on chronic brain injury after focal cerebral ischemia.
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Is there a role of TNFR1 in acute lung injury cases associated with extracorporeal circulation?
Yu Zhao, Chong-wei Zhang, Wen-jing Zhou, Jiao Chen, Nan-fu Luo, Li-na Gong, Lei Du, Jing Zhou
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 281-288.
https://doi.org/10.1631/jzus.B1300147
The signaling pathway for tumor necrosis factor-α (TNF-α) and its receptors is up-regulated during extracorporeal circulation (ECC), and recruits blood neutrophil into the lung tissue, which results in acute lung injury (ALI). In this study, we evaluated the role of tumor necrosis factor receptor 1 (TNFR1) in ECC-induced ALI by blocking TNF-α binding to TNFR1 with CAY10500. Anesthetized Sprague-Dawley (SD) rats were pretreated intravenously with phosphate buffered saline (PBS) or vehicle (0.3 ml ethanol IV) or CAY10500, and then underwent ECC for 2 h. The oxygenation index (OI) and pulmonary inflammation were assessed after ECC. OI was significantly decreased, while TNF-α and neutrophil in bronchoalveolar lavage fluid (BALF) and plasma TNF-α increased after ECC. Pretreatment of CAY10500 decreased plasma TNF-α level, but did not decrease TNF-α levels and neutrophil counts in BALF or improve OI. Lung histopathology showed significant alveolar congestion, infiltration of the leukocytes in the airspace, and increased thickness of the alveolar wall in all ECC-treated groups. CAY10500 pretreatment slightly reduced leukocyte infiltration in lungs, but did not change the wet/dry ratio in the lung tissue. Blocking TNF-α binding to TNFR1 by CAY10500 intravenously slightly mitigates pulmonary inflammation, but cannot improve the pulmonary function, indicating the limited role of TNFR1 pathway in circulating inflammatory cell in ECC-induced ALI.
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Effect of vitamin B12 on cleft palate induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin and dexamethasone in mice
Shu-fan Zhao, Mao-zhou Chai, Min Wu, Yong-hong He, Tian Meng, Bing Shi
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 289-294.
https://doi.org/10.1631/jzus.B1300083
The purpose of this study was to investigate the effect of vitamin B12 on palatal development by co-administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and dexamethasone (DEX). We examined the morphological and histological features of the palatal shelf and expression levels of key signaling molecules (transforming growth factor-β3 (TGF-β3) and TGF-β type I receptor (activin receptor-like kinase 5, ALK5)) during palatogenesis among a control group (Group A), TCDD+DEX exposed group (Group B), and TCDD+DEX+vitamin B12 exposed group (Group C). While we failed to find that vitamin B12 decreased the incidence of cleft palate induced by TCDD+DEX treatment, the expression levels of key signaling molecules (TGF-β3 and ALK5) during palatogenesis were significantly modulated. In TCDD+DEX exposed and TCDD+DEX+vitamin B12 exposed groups, palatal shelves could not contact in the midline due to their small sizes. Our results suggest that vitamin B12 may inhibit the expression of some cleft palate inducers such as TGF-β3 and ALK5 in DEX+TCDD exposed mice, which may be beneficial against palatogenesis to some degree, even though we were unable to observe a protective role of vitamin B12 in morphological and histological alterations of palatal shelves induced by DEX and TCDD.
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Anti-adipogenic effects of extracts of Ficus deltoidea var. deltoidea and var. angustifolia on 3T3-L1 adipocytes
Shiau Mei Woon, Yew Wei Seng, Anna Pick Kiong Ling, Soi Moi Chye, Rhun Yian Koh
Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology), 2014, 15(3): 295-302.
https://doi.org/10.1631/jzus.B1300123
Objective: This study examined the anti-adipogenic effects of extracts of Ficus deltoidea var. deltoidia and var. angustifolia, a natural slimming aid, on 3T3-L1 adipocytes. Methods: Methanol and water extracts of leaves of the F. deltoidea varieties were analyzed to determine their total flavonoid content (TFC) and total phenolic content (TPC), respectively. The study was initiated by determining the maximum non-toxic dose (MNTD) of the methanol and water extracts for 3T3-L1 preadipocytes. Possible anti-adipogenic effects were then examined by treating 2-d post confluent 3T3-L1 preadipocytes with either methanol extract or water extract at MNTD and half MNTD (½MNTD), after which the preadipocytces were induced to form mature adipocytes. Visualisation and quantification of lipid content in mature adipocytes were carried out through oil red O staining and measurement of optical density (OD) at 520 nm, respectively. Results: The TFCs of the methanol extracts were 1.36 and 1.97 g quercetin equivalents (QE)/100 g dry weight (DW), while the TPCs of the water extracts were 5.61 and 2.73 g gallic acid equivalents (GAE)/100 g DW for var. deltoidea and var. angustilofia, respectively. The MNTDs determined for methanol and water extracts were (300.0±28.3) and (225.0±21.2) µg/ml, respectively, for var. deltoidea, while much lower MNTDs [(60.0±2.0) µg/ml for methanol extracts and (8.0±1.0) µg/ml for water extracts] were recorded for var. angustifolia. Studies revealed that the methanol extracts of both varieties and the water extracts of var. angustifolia at either MNTD or ½MNTD significantly inhibited the maturation of preadipocytes. Conclusions: The inhibition of the formation of mature adipocytes indicated that leaf extracts of F. deltoidea could have potential anti-obesity effects.
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10 articles
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