Chinese Ophthalmic Research最新文献_第5页

Expression of monocyte chemoattractant protein-1 in experimental choroidal neovascularization 实验性脉络膜新生血管中单核细胞趋化蛋白-1的表达

Chinese Ophthalmic Research Pub Date : 2010-08-10 DOI: 10.3969/J.ISSN.1003-0808.2010.08.006

高小燕, 何守志, 张新秀

{"title":"Expression of monocyte chemoattractant protein-1 in experimental choroidal neovascularization","authors":"高小燕, 何守志, 张新秀","doi":"10.3969/J.ISSN.1003-0808.2010.08.006","DOIUrl":"https://doi.org/10.3969/J.ISSN.1003-0808.2010.08.006","url":null,"abstract":"目的观察单核细胞趋化蛋白-1(MCP-1)在氪激光诱导的BN大鼠脉络膜新生血管(CNV)中的表达.方法用氪激光对48只健康雄性BN大鼠的一侧眼进行视网膜光凝以建立CNV动物模型,光凝后连续8周每周对模型鼠行荧光素眼底血管造影(FFA)检查,每周检查后各摘除6只模型眼制备眼球壁切片.依据苏木精-伊红染色测量CNV面积,应用免疫组织化学法测定MCP-1、Ⅷ因子相关抗原(FⅧ-Rag)蛋白在CNV中的表达.结果视网膜光凝后1～8周,CNV面积、荧光素渗漏、FⅧ-Rag和MCP-1在CNV中的表达量随着时间的延长逐渐增加,差异均有统计学意义(F=194.43,P＜0.01;F=178.84,P＜0.01;F=965.15,P＜0.01;F=1400.71,P＜0.01).CNV面积与荧光素渗漏量(r=0.886,P＜0.05)、CNV面积与FⅧ-Rag表达量(r=0.975,P＜0.05)、CNV面积与MCP-1表达量(r=0.956,P＜0.05)、MCP-1表达量与FⅧ-Rag表达量(r=0.961,P＜0.05)、MCP-1表达量与荧光素渗漏量(r=0.914,P＜0.05)均呈正相关.结论 MCP-1的表达随CNV面积及荧光素渗漏量的增加而增强,可能在CNV形成和发展过程中起重要作用。","PeriodicalId":186994,"journal":{"name":"Chinese Ophthalmic Research","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129339301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Ultrastructure of trabecular tissue in primary angle close glaucoma of Mongolia 蒙古原发性闭角型青光眼小梁组织超微结构的观察

Chinese Ophthalmic Research Pub Date : 2010-07-10 DOI: 10.3969/J.ISSN.1003-0808.2010.07.020

崔巍, 孙晓雷, 李红霞

{"title":"Ultrastructure of trabecular tissue in primary angle close glaucoma of Mongolia","authors":"崔巍, 孙晓雷, 李红霞","doi":"10.3969/J.ISSN.1003-0808.2010.07.020","DOIUrl":"https://doi.org/10.3969/J.ISSN.1003-0808.2010.07.020","url":null,"abstract":"目的探讨蒙古族青光眼高发病率的原因,为寻找蒙古族原发性闭角型青光眼(PACG)的发病机制提供理论依据.方法蒙古族PACG患者30例,汉族PACG患者30例,均取常规小梁切除术眼的小梁组织.PACG诊断按照中华医学会眼科学会青光眼学组制定的标准.应用电子显微镜观察小梁组织的超微结构,其中包括小梁薄板胶原纤维轴、小梁内皮细胞、小梁薄板皮质区及小梁网眼.正常对照组为蒙古族正常人眼、汉族正常人眼各20例.结果蒙古族正常人眼小梁薄板胶原纤维走行相对紊乱,但无断裂现象;胶原纤维轴与基底膜结构界线不清并有渗透现象;蒙古族PACG小梁网中胶原纤维走行相对小梁薄板长轴的方向发生改变,可见断裂;小梁薄板内皮细胞核溶解,细胞器减少;小梁薄板皮质区薄厚不均,与断裂的胶原纤维有明显的分界线,并有玻璃样变性;小梁网眼有不同程度的堵塞和变窄.从正常人眼来看,蒙古族与汉族相比小梁组织超微结构异常的病例增加,二者比较差异有统计学意义,包括胶原纤维轴结构异常(χ2=4.360,P=0.025),小梁内皮细胞数异常(χ2=6.570,P=0.013),小梁薄板皮质区(χ2=7.140,P=0.035)和小梁网眼异常(χ2=5.430,P=0.020).蒙古族PACG和汉族PACG在小梁网超微结构的比较中异常病例增加,二者比较差异有统计学意义,包括胶原纤维轴结构异常(χ2=4.250,P=0.026),小梁内皮细胞数异常(χ2=7.180,P=0.037),小梁薄板皮质区(χ2=6.540,P=0.013) 以及小梁网眼异常(χ2=5.270,P=0.019).结论蒙古族PACG发病率高的机制不仅是由于存在浅前房、窄房角等高危因素,而且可能与其小梁网的超微结构异常有关。","PeriodicalId":186994,"journal":{"name":"Chinese Ophthalmic Research","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121904903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Inhibitory effect of tenomodulin protein on proliferation of vascular endothelial cells 腱调节蛋白对血管内皮细胞增殖的抑制作用

Chinese Ophthalmic Research Pub Date : 2010-07-10 DOI: 10.3969/J.ISSN.1003-0808.2010.07.012

王蔚, 大岛佑介, 田野保雄

{"title":"Inhibitory effect of tenomodulin protein on proliferation of vascular endothelial cells","authors":"王蔚, 大岛佑介, 田野保雄","doi":"10.3969/J.ISSN.1003-0808.2010.07.012","DOIUrl":"https://doi.org/10.3969/J.ISSN.1003-0808.2010.07.012","url":null,"abstract":"目的研究tenomodulin (TeM)蛋白对血管内皮生长因子(VEGF)诱导的人视网膜血管内皮细胞(RECs)和人脐静脉内皮细胞(UVECs)增生及其对体外血管样结构形成的作用.方法将传代至3～6代的人RECs和人UVECs生长至融合时用含质量分数0.5%胎牛血清(FBS) 的培养基孵箱中培养6h,加入不同质量浓度的VEGF或VEGF+TeM混合物,继续培养12h,ELISA法检测TeM对VEGF诱导的血管内皮细胞增生的影响.将含10%FBS、1%FBS DMEM培养基的人RECs和人UVECs悬液分别接种于预先放置基质胶的24孔培养板表面,含1%FBS培养基的细胞培养板内分别加入VEGF(100μg/L)或VEGF+TeM混合物37℃继续培养6h,共焦显微镜下观察,图像处理分析软件量化分析TeM蛋白对毛细血管样结构形成的作用.结果随着VEGF质量浓度的增加,血管内皮细胞DNA合成增加,其吸光度(A)值呈明显上升曲线,而添加TeM组的A值比VEGF组降低,差异有统计学意义(P＜0.01).含10%FBS和1%FBS培养基的血管内皮细胞在基质胶表面形成毛细血管样结构,并连接成网状;在基质胶表面同时添加VEGF的血管内皮细胞,其毛细血管样结构明显增多,长度明显变长.添加TeM组的血管内皮细胞和其毛细血管样结构破坏,每个视野内血管内皮细胞毛细血管样结构显著破坏,管形细胞总长度明显变短.结论 TeM蛋白对血管内皮细胞的增生及体外血管样结构的形成有明显抑制作用。","PeriodicalId":186994,"journal":{"name":"Chinese Ophthalmic Research","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121422905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Research progression in inducing factors of evaporative dry eye 蒸发性干眼症诱发因素的研究进展

Chinese Ophthalmic Research Pub Date : 2010-07-10 DOI: 10.3969/J.ISSN.1003-0808.2010.07.031

林惠玉

引用次数: 0

Effects of LPS-induced inflammation on expression of COX-2 mRNA and PGE2 secretion in orbital fibroblasts of TAO lps诱导炎症对TAO眼眶成纤维细胞COX-2 mRNA表达及PGE2分泌的影响

Chinese Ophthalmic Research Pub Date : 2010-07-10 DOI: 10.3969/J.ISSN.1003-0808.2010.07.006

易文殊, 许雪亮

{"title":"Effects of LPS-induced inflammation on expression of COX-2 mRNA and PGE2 secretion in orbital fibroblasts of TAO","authors":"易文殊, 许雪亮","doi":"10.3969/J.ISSN.1003-0808.2010.07.006","DOIUrl":"https://doi.org/10.3969/J.ISSN.1003-0808.2010.07.006","url":null,"abstract":"目的观察脂多糖(LPS)对甲状腺相关眼病(TAO)眼眶成纤维细胞环氧合酶-2(COX-2)表达及前列腺素E2(PGE2)分泌的影响.方法眼眶组织分别取自3例3眼因眼球萎缩行义眼台植入(正常对照组)和4例4眼因TAO行开眶减压术(TAO组)的患者.细胞原代培养采用组织块法.将体外培养的2组眼眶成纤维细胞,分别采用0、10、100、1000μg/L的LPS作用24h,或1000 μg/L LPS分别作用0、4、8、12、24h.半定量逆转录聚合酶链反应法(RT-PCR)检测各组COX-2mRNA的表达,ELISA法检测上清液中PGE2的表达.结果组织块培养法第3天即有成纤维样细胞自组织块边缘游出,细胞呈长梭形和多角形.10、100、1000μg/L LPS作用后,与未用LPS刺激时相比,正常对照组和TAO组眼眶成纤维细胞COX-2mRNA的表达均增强,PGE2的分泌增加.与正常对照组相比,1000μg/L LPS作用时间相同时,TAO组COX-2mRNA表达及PGE2的分泌增加更为明显(P＜0.05).结论 COX-2通路可能参与了活动期TAO的炎症过程;在疾病的活动期,采用抑制COX-2的治疗,可减轻局部炎症反应,可能对活动期TAO的治疗有效。","PeriodicalId":186994,"journal":{"name":"Chinese Ophthalmic Research","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132320712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Current research on epithelial mesenchymal transition related signal pathway in eye diseases 眼病上皮间充质转化相关信号通路的研究现状

Chinese Ophthalmic Research Pub Date : 2010-07-10 DOI: 10.3969/J.ISSN.1003-0808.2010.07.030

马健利

引用次数: 0

Corneal tissue responses under confocal microscopy after VisuMax femtosecond laser assisted LASIK VisuMax飞秒激光辅助LASIK术后共聚焦显微镜下角膜组织反应

Chinese Ophthalmic Research Pub Date : 2010-07-10 DOI: 10.3969/J.ISSN.1003-0808.2010.07.024

许烨, 周行涛, 牛凌凌, 徐建江, 褚仁远

{"title":"Corneal tissue responses under confocal microscopy after VisuMax femtosecond laser assisted LASIK","authors":"许烨, 周行涛, 牛凌凌, 徐建江, 褚仁远","doi":"10.3969/J.ISSN.1003-0808.2010.07.024","DOIUrl":"https://doi.org/10.3969/J.ISSN.1003-0808.2010.07.024","url":null,"abstract":"目的观察VisuMax飞秒激光制瓣的准分子激光角膜原位磨镶术(LASIK)术后角膜反应的动态变化.方法等效球镜为-6.75～-12.50D的近视患者6例12眼行VisuMax飞秒激光制瓣的LASIK.飞秒激光参数设置为脉冲频率200kHz,脉冲能量100～150nJ,瓣直径7.9～8.3mm,预计瓣厚度80～100μm.分别于术后1周、1个月、3个月用裂隙灯检查角膜中央区域的形态,并用共焦显微镜观察中央区域的角膜反应.结果术后1周、1个月、3个月裂隙灯检查所有手术眼未见haze或瓣皱褶,共焦显微镜下观察所有眼未见明显角膜上皮细胞的形态改变.术后1周,4例6眼观察到近切削界面的基质细胞轻度激活,表现为细胞核反光增强,细胞轮廓可见,切削面反光轻度增强,其余眼未观察到明显的基质细胞激活.角膜基质细胞激活在术后1个月减轻,至术后3个月基本消失.术后所有手术眼均可在切削面持续观察到高反光沉积物,1眼(预期角膜瓣厚度80μm)在共焦显微镜下可见角膜微皱褶.结论 VisuMax飞秒激光LASIK术后存在角膜细胞水平反应的变化,其角膜基质细胞激活程度较轻可能与脉冲能量较低有关。","PeriodicalId":186994,"journal":{"name":"Chinese Ophthalmic Research","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123516305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effect of rAAV2-NTF2 on vascular endothelial growth factor expression in human retinal capillary endothelial cells rAAV2-NTF2对人视网膜毛细血管内皮细胞血管内皮生长因子表达的影响

Chinese Ophthalmic Research Pub Date : 2010-07-10 DOI: 10.3969/J.ISSN.1003-0808.2010.07.001

史煜, 陈春生, 曹亮, 陈凌燕, 谢琳, 唐仕波

{"title":"Effect of rAAV2-NTF2 on vascular endothelial growth factor expression in human retinal capillary endothelial cells","authors":"史煜, 陈春生, 曹亮, 陈凌燕, 谢琳, 唐仕波","doi":"10.3969/J.ISSN.1003-0808.2010.07.001","DOIUrl":"https://doi.org/10.3969/J.ISSN.1003-0808.2010.07.001","url":null,"abstract":"目的观察核运输因子2(NTF2)在体外培养的人视网膜微血管内皮细胞(RCECs)中的表达,并探讨其高表达对RCECs中血管内皮生长因子(VEGF)表达的影响.方法取中山眼科中心眼库的人眼球,分离视网膜组织用以培养人RCECs,并用Ⅷ因子抗体免疫组织化学法鉴定.免疫组织化学法观察细胞中NTF2的表达.通过重组腺相关病毒(rAAV2)将外源性NTF2导入培养的RCECs内,rAAV2-NTF2和rAAV2-EGFP转染RCECs,未转染组为对照组.激光共焦显微镜下观察增强型绿色荧光蛋白(EGFP)阳性细胞,逆转录聚合酶链反应(RT-PCR)法检测各组NTF2、VEGF mRNA的表达变化,并进行定量分析.结果培养的RCECs呈典型铺路石样排列,荧光显微镜下可见Ⅷ因子阳性表达为绿色荧光,95%以上的活体细胞可摄取DiI标记的Ac-LDL,并在荧光显微镜下呈现红色荧光.RCECs可表达NTF2,主要位于细胞质内,富集于核周.rAAV2-EGFP转染后,激光共焦显微镜观察可见大量EGFP阳性细胞,实验组NTF2在mRNA水平表达明显强于GFP组和对照组(t=15.06,t=7.02,P＜0.01),VEGF表达明显下降(t=7.40,t=14.08,P＜0.01).结论 rAAV2-NTF2转染视网膜内皮细胞后,NTF2可稳定高表达,VEGF表达下降,NTF2可能通过调节VEGF的表达参与新生血管的发生。","PeriodicalId":186994,"journal":{"name":"Chinese Ophthalmic Research","volume":"412 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134289012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Expression of transforming growth factor β2 in human retinal pigment epithelium cells regulated by carbacholby 碳甾醇调节人视网膜色素上皮细胞转化生长因子β2的表达

Chinese Ophthalmic Research Pub Date : 2010-07-10 DOI: 10.3969/J.ISSN.1003-0808.2010.07.022

谭佳, 邓志宏, 刘双珍

{"title":"Expression of transforming growth factor β2 in human retinal pigment epithelium cells regulated by carbacholby","authors":"谭佳, 邓志宏, 刘双珍","doi":"10.3969/J.ISSN.1003-0808.2010.07.022","DOIUrl":"https://doi.org/10.3969/J.ISSN.1003-0808.2010.07.022","url":null,"abstract":"目的研究卡巴胆碱对人视网膜色素上皮(RPE)细胞株D407表达转化生长因子β2(TGF-β2)的调控,进而阐明胆碱能药物在近视眼巩膜重塑中的作用.方法常规培养D407细胞,药物干预前换用无血清培养基培养24h.将传代细胞分为实验组和空白组,实验组分别加入1×10-8、1×10-7、1×10-61×10-5、1×10-4mol/L卡巴胆碱,空白组不加药物.于处理后2、4、8、16、24、48h分别采用逆转录聚合酶链反应(RT-PCR)Western blot法检测细胞中TGF-β2mRNA及TGF-β2蛋白的表达,分析时效与量效关系.结果空白组细胞TGF-β2mRNA、蛋白质表达水平恒定.实验组D407细胞中TGF-β2mRNA的表达随卡巴胆碱作用时间的延长而逐渐升高,差异有统计学意义(F=4 455.148,P＜0.01)；且随卡巴胆碱浓度的升高逐渐增加,各组的总体比较差异有统计学意义(F=1102.240,P＜0.01).卡巴胆碱浓度与干预时间对TGF-β2mRNA表达的影响存在交互作用(F=2 49.609,P＜0.01).实验组D407细胞中TGF-β2蛋白的表达随时间延长而逐渐升高,各时间点的总体比较差异有统计学意义(F=2 619.21,P＜0.01),不同浓度卡巴胆碱组TGF-β2蛋白的表达总体比较差异有统计学意义(F=2 918.62,P＜0.01),卡巴胆碱浓度与干预时相TGF-β2 蛋白表达的影响存在交互作用(F=186.02,P＜0.01).结论 RPE细胞可表达TGF-β2,卡巴胆碱可以浓度和时间依赖的方式调控RPE细胞中TGF-β2的表达。","PeriodicalId":186994,"journal":{"name":"Chinese Ophthalmic Research","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122700200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Establishment of animal model for retinoblastoma in nude mice by subretinal injection of HXO-Rb44 cells 视网膜下注射HXO-Rb44细胞建立裸鼠视网膜母细胞瘤动物模型

Chinese Ophthalmic Research Pub Date : 2010-07-10 DOI: 10.3969/J.ISSN.1003-0808.2010.07.003

王丽萍, 周希瑗, 彭周贵, 郑敏明, 邱明忠, 雷博

{"title":"Establishment of animal model for retinoblastoma in nude mice by subretinal injection of HXO-Rb44 cells","authors":"王丽萍, 周希瑗, 彭周贵, 郑敏明, 邱明忠, 雷博","doi":"10.3969/J.ISSN.1003-0808.2010.07.003","DOIUrl":"https://doi.org/10.3969/J.ISSN.1003-0808.2010.07.003","url":null,"abstract":"目的建立一种生物学行为更接近临床的视网膜母细胞瘤(Rb)动物模型.方法 Rb细胞取HXO-Rb44细胞系,培养于含质量分数10%胎牛血清的改良型RPMI-1640培养基内,细胞悬液密度调至(5.0～6.0)×106/mL备用.30只裸鼠,分为视网膜下组和玻璃体腔组,每组各15只鼠30只眼.2组注射HXO-Rb44细胞悬液后每天裂隙灯下观察裸鼠眼内Rb肿物生长情况,并于注射后21、28、35、42d,根据组织病理学检查统计成瘤情况,比较2组成瘤率.行Rb特异性标志神经元特异性烯醇酶(NSE)及酸性钙结合蛋白(S100)和胶质纤维酸性蛋白(GFAP)免疫组织化学检测.结果视网膜下组和玻璃体腔组在注射后均观察到肿瘤在裸鼠眼内生长并逐渐增大.注射后21、28、35、42d,视网膜下组成瘤率高于玻璃体腔组,差异均有统计学意义(P＜0.05).免疫组织化学染色提示,Rb细胞质NSE表达较强,S100表达较弱,GFAP表达最弱.结论在同等条件下建立Rb动物模型,视网膜下注射的成瘤率高于玻璃体腔内注射者,且视网膜下注射建立的是原位肿瘤模型,生物学行为更接近临床。","PeriodicalId":186994,"journal":{"name":"Chinese Ophthalmic Research","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116807246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0