成人急性淋巴细胞白血病的MIC分型与临床预后分析

目的：分析成人急性淋巴细胞白血病（ＡＬＬ）的ＭＩＣ分型与临床与预后的关系。方法：４０例ＡＬＬ患者按常规骨髓涂片及细胞化学染色进行形态学分析，并用单克隆抗体间接免疫荧光法检测细胞免疫表型，用Ｒ显带技术分析１３例的细胞遗传学。结果：ＦＡＢ分型ＡＬＬ－Ｌ１型３例，Ｌ２型３５例，Ｌ３型２例。细胞免疫表型符合Ｔ细胞系ＡＬＬ１３例（伴髓系表达２例），Ｂ超细胞系ＡＬＬ２１例（伴髓系表达４例），Ｔ／Ｂ细胞系共同表     

维甲酸和三氧化砷对急性早幼粒细胞性白血病细胞组织因子表 …

目的 探讨全反式维甲酸（ＡＴＲＡ）和三氧化二砷（Ａｓ２Ｏ３）在体内外对急性早幼粒细胞性白血病（ＡＰＬ）细胞组织因子（ＴＦ）表达的意义。方法 利用复钙时间测定、ＥＬＩＳＡ和ＲＴ－ＰＣＲ等方法,分别检测了ＡＴＲＡ和Ａｓ２Ｏ３治疗前后ＡＰＬ患者（２３例）骨髓单个核细胞的促凝活性、ＴＦ抗原及其ｍＲＮＡ的转录水平,同时还检测了使用ＡＴＲＡ和Ａｓ２Ｏ３处理ＡＰＬ细胞株ＮＢ４－Ｒ１细胞以及转染ＰＭＬ－ＲＡＲａ融     

重组乙型肝炎表面抗原插入突变体的真核表达及其抗原性的分析

目的研究与乙型肝炎病毒感染的临床进程相关的两种乙型肝炎表面抗原（ＨＢｓＡｇ）插入变异体的免疫学性状,以阐明在ＨＢｓＡｇ阴性的慢性乙型肝炎病毒感染中所起的作用。方法利用体外ＰＣＲ诱变方法,构建重组ＨＢｓＡｇ的插入突变体;借助ＥＢ病毒载体ｐＣＥＰ４和逆转录病毒载体ＰＸＴ１将重组插入变异Ｓ基因转染哺乳动物细胞;利用ＥＬＩＳＡ及Ｗｅｓｔｅｒｎｂｌｏｔ方法,探讨变异抗原与抗ＨＢｓ的结合力。结果（１）构建了ＨＢｓＡｇ的插入突变体（分别在ＨＢｓＡｇ的第１２２位与１２３位氨基酸间插入Ａｒｇ,Ａｌａ和第１２３位与１２４位氨基酸间插入Ａｒｇ,Ｇｌｙ,Ａｌａ）的真核表达载体;（２）将其转染哺乳动物细胞,最终建立了能表达野生型和变异型ＨＢｓＡｇ的ＨｅｐＧ２细胞系;（３）这些细胞系能在体外稳定地连续传代培养;（４）野生型ＨＢｓＡｇ可与抗ＨＢｓ结合,变异型ＨＢｓＡｇ不能与抗ＨＢｓ结合。结论研究表明这两种插入变异体影响了ＨＢｓＡｇ的空间结构,从而使其失去与乙型肝炎病毒表面抗体的结合力,因而可能逃避机体的免疫清除而持续存在于体内形成慢性感染。     

B细胞系特异性单克隆抗体ZCH－4－2E8的制备鉴定及其初步应用

本文报告一种识别Ｂ细胞系白血病相关抗原的鼠单克隆抗体ＺＣＨ－４２Ｅ８（ＩｇＧ１），免疫印迹试验示其所识别的抗原分子量为２４５ｋｄ。经多种细胞系、正常外周血细胞成分、骨髓单个核细胞、胚胎肝、脾、胸腺和１３８例急、慢性白血病细胞的鉴定结果表明，２Ｅ８为Ｂ细胞系特异性单抗，其反应谱与ＣＤ１９类似，但其尚能识别早至１８周龄的胚胎脾（Ｂ）细胞，阳性率为３１．９％（ＣＤ１９为０％）。作者认为：２Ｅ８是一种能用于分化早期Ｂ细胞系急性淋巴细胞白血病（ＡＬＬ）的诊断和急性未分化型白血病（ＡＵＬ）鉴别诊断的Ｂ细胞系特异性单抗。     

三氧化二砷对急性早幼粒细胞性白血病细胞组织因子表达的影响

目的探讨三氧化二砷（Ａｓ２Ｏ３）对急性早幼粒细胞性白血病（ＡＰＬ）细胞组织因子（ＴＦ）表达的影响。方法利用复钙时间检测使用１μＭＡｓ２Ｏ３处理ＡＰＬ细胞株ＮＢ４细胞以及使用Ａｓ２Ｏ３治疗中不同时间的ＡＰＬ病人的骨髓细胞的促凝活性（ＰＣＡ）,并用ＥＬＩＳＡ方法检测其ＴＦ抗原、利用半定量ＲＴＰＣＲ检测ＴＦｍＲＮＡ的转录水平。结果Ａｓ２Ｏ３可以以时间依赖的方式下调ＡＰＬ细胞的促凝活性、ＴＦ抗原水平以及ＴＦｍＲＮＡ的转录;此外,通过对ＰＣＲ产物进行测序,发现ＡＰＬ细胞中还存在ＴＦ第五个外显子缺失的转录本,其生物学意义尚不明了。结论Ａｓ２Ｏ３可下调ＡＰＬ细胞ＴＦ的表达;而且在使用Ａｓ２Ｏ３诱导ＡＰＬ细胞凋亡的同时,Ａｓ２Ｏ３有可能通过下调ＡＰＬ细胞ＴＦ的表达而预防ＤＩＣ的发生     

三氧化二砷诱导K562细胞凋亡的初步研究

目的：探讨三氧化二砷（Ａｓ２Ｏ３） 治疗慢性粒细胞性白血病（ＣＭＬ） 的机制。方法：以ＣＭＬ细胞系Ｋ５６２ 为模型,通过细胞增殖、活力检测、形态学观察、肿瘤集落形成的琼脂糖凝胶电泳等检验。结果：经≥２．５μｍｏｌ／ＬＡｓ２Ｏ３ 处理的Ｋ５６２ 细胞可出现增殖受抑和凋亡的形态学改变及ＤＮＡ片段化。结论：Ａｓ２Ｏ３ 能有效地诱导Ｋ５６２ 细胞凋亡。     

三氧化二砷对K562细胞细胞周期的影响及其机制的研究

最近，有关三氧化二砷（Ａｓ２Ｏ３）有效治疗急性早幼粒细胞白血病，且无严重毒副作用及骨髓抑制的报道［１，２］，再度引起人们对Ａｓ２Ｏ３治疗白血病甚至其他恶性肿瘤的浓厚兴趣。为阐明Ａｓ２Ｏ３治疗慢性髓细胞白血病的机制，并为其临床应用提供理论依据，我们以Ｋ...     

大剂量阿糖胞苷治疗急性白血病8例临床分析

急性白血病（ＡＬ）诱导化疗症状完全缓解后,应继续清除体内的微小残留病变（ＭＲＤ）。ＭＲＤ是白血病复发及影响预后的根本原因［１］。在延长阿糖胞各（ＡＲＡ－Ｃ）用药时间及加大剂量后可清除ＭＲＤ,达到巩固强化治疗的目的,我院于１９９５年１月～１９９８年６月共收治ＡＬ。患者８例,取得满意的效果。报告如下。１资料与方法１．１一般资料８例中。男１例,女７例,年龄２０～５３岁,中位年龄３６．３岁,体表面积１．２～１．８ｍ２。平均体表面积１．５５ｍ３。其中急性髓细胞性白血病（ＡＮＩＬ）３例,急性淋巴细胞性白血病…     

急性白血病Bcl-2反义寡核苷酸基因治疗的实验研究

目的选用２０ｎｔＢｃｌ－２反义硫代磷酸寡核苷酸（Ａｓ－Ｐｓ－ＯＤＮ，ＡＳＰＯ），并以其正义寡核苷酸（ＳＰＯ）为对照做如下问题探讨：（１）普通剂量（５～２０μｍｏｌ）ＡＳＰＯ对ＨＬ６０细胞、正常及缺铁性贫血患者骨髓细胞及急性白血病病人骨髓细胞或外周白血病细胞（幼稚细胞≥８５％）的作用；（２）大剂量（１６０μｍｏｌ）正义或反义寡核苷酸对ＨＬ６０细胞作用的特点，并通过ＡＳＰＯ引起ＨＬ６０细胞Ｂｃｌ－２蛋白表达变化和ＳＰＯ对ＨＬ６０细胞毒性的变化，寻找可能的最佳效应剂量和最小毒性剂量；（３）ＡＳＰＯ联合化疗药物对ＨＬ６０细胞和原代急性白血病细胞的作用。方法台盼蓝拒染试验和克隆培养测定细胞的生长能力；免疫细胞化学染色和流式细胞仪检测Ｐ２６Ｂｃｌ－２蛋白表达，ＲＴ－ＰＣＲ法检测Ｂｃｌ－２ｍＲＮＡ（Ｂｃｌ－２／β－ａｃｔｉｎ）相对水平；光、电镜下观察凋亡细胞形态，吖啶橙染色及流式细胞仪检测细胞凋亡率，ＤＮＡ提取及电泳观察凋亡细胞ＤＮＡ降解片段的形成；ＭＴＴ法检测ＰＳ－ＯＤＮ及化疗药物的细胞毒作用。结果（１）普通剂量的ＡＳＰＯ即能降低ＨＬ６０细胞及白血病细胞Ｂｃｌ－２ｍＲＮＡ的表达，并抑制ＨＬ６０细胞及１８／２０例白血病细     

凋亡相关蛋白BCL—2与白血病化疗药物敏感性的研究

研究急性白血病细胞ＢＣＬ－２表达及其与体外化疗药物敏感性的关系。方法：采用Ｗｅｓｔｅｒｎｂｌｏｔｉｎｇ技术和四甲基偶氮唑盐比色法，分别检测ＨＬ－６０、Ｕ９３７细胞株和６例急性细胞白血病细胞ＢＣＬ－２表达水平及体外对柔红霉素的敏感性。结论细胞系和白血病原代细胞的ＢＣＬ－２高表达伴低药敏与ＡＭＬ疗效有关     

Arsenic trioxide induces multiple myeloma cell apoptosis viadisruption of mitochondrial transmembrane potentials and activation of caspase-3

Objective　To investigate the response of multiple myeloma (MM) cells to arsenic trioxide (As2O3 ) and their possible mechanisms. Methods　Two MM-derived cell lines RPMI8226 and U266 cells were used as in vitro models. Cell apoptosis was assessed by morphology, flow cytometry, and DNA gel electrophoresis. Mitochondrial transmembrane potentials (△Ψm) were evaluated by measuring cellular Rhodamine 123 staining intensity. Protein expression was analyzed using Western blot. Results　Zero point one to 0.5μmol/L As2O3 inhibited cell proliferation and 2.0?μmol/L As2O3 induced cell apoptosis, while 1.0μmol/L As2O3 inhibited proliferation with a weak degree of apoptosis induction in RPMI8226 and U266 cell lines. As2O3-induced apoptosis was accompanied by mitochondrial transmembrane potentials (△Ψm) collapse and caspase-3 activation in the presence of intact membrane. Glutathione depleter buthionine sulfoximine enhanced, while disulfide bond-reducing agent dithiothreitol partially antagonized As2O3 -induced △Ψm collapse and apoptosis in MM cells. All-trans retinoic acid (ATRA) could also induce apoptosis in RPMI8226 cells, but it did not show any cooperative effects with As2O3. Conclusion　As2O3 exerts apoptosis-inducing and growth-inhibiting effects on MM cells, and mitochondrium is a pivotal and common target of As2O3 for apoptosis induction.     

Apoptosis susceptibility of tumor cells to arsenic trioxide and the inherent cellular level of reactive oxygen species

Objective To explore the association of in herent cellular reactive oxygen species (ROS) levels with susceptibility of the tumor cells to apoptosis induction by arsenic trioxide (As(2)O(3)).Methods Low concentration (2μmol/L) of As(2)O(3) was administered to two cultured leukemic cell lines, NB4 and U937, and two esophageal carcinoma cell lines, EC1 .71 (also named EC/CUHK1) and EC1867, to confirm the difference in apoptosis su sceptibility of NB4 versus U937 and of EC1.71 versus EC1867. Dihydro genrhodamine 123 (DHR123), used as a ROS capture agent, was incubated with cell s in the absence of As(2)O(3). Fluorescence intensity of rhodamine 123, the pro duct of cellular oxidation of DHR123, was detected by flow cytometry and ROS was measured. Results Low concentration of As(2)O(3) induced apoptosis was more likely to occur in NB 4 and EC1.71 cells than in U937 and EC1867 cells, or NB4 was more sensitive tha n U937, and EC1.71 more sensitive than EC1867 to As(2)O(3). The inherent cellu lar ROS level is higher in NB4 than in U937, and also higher in EC1.71 than in EC1867 . Conclusions The difference in cellular ROS level is positively associated with cellular susc eptibility to apoptotis induction by As(2)O(3). The inherent ROS level might be important in defining apoptotic susceptibility to As(2)O(3).     

EFFECTS OF ARSENIC TRIOXIDE ADMINISTRATION STYLES ON LEUKOCYTOSIS

ARSENIC trioxide ( As2O3) is effective in thetreatment of acute promyelocytic leukemia(APL) and many other kinds of malignant he-matopathies and solid carcinomas·1-5However, leukocytosisis commonly noticed with As2O3use, which severelythreatens the survi…     

一氧化氮对肝癌细胞线粒体膜通透性和胞浆中细胞色素C含量的影响

目的探讨一氧化氮(NO)对肝癌细胞线粒体膜通透性和胞浆中细胞色素C(cytC)含量的影响.方法用NO供体硝普钠(SNP)诱导SMMC-7721和HepG2肝癌细胞株凋亡,流式细胞术检测SMMC-7721和HepG2细胞凋亡率,MTT法观察肝癌细胞生长增殖情况,流式细胞术检测细胞线粒体跨膜电位变化,Western blot检测胞浆中cyt C含量的变化,同时应用线粒体膜通透性转变孔开放抑制剂CsA和γ-谷氨酰半胱氨酸合成酶抑制剂BSO预处理细胞,并观察以上各指标的变化.结果 SNP能诱导人肝癌细胞SMMC-7721和HepG2凋亡,并可导致两株细胞线粒体跨膜电位下降,胞浆中cyt C含量增加,与SNP的作用时间成正比.CsA能够抑制SNP所致的肝癌细胞线粒体跨膜电位的下降及胞浆中cyt C含量的增加;而BSO则可促进线粒体跨膜电位下降,cyt C从线粒体释放到胞浆.结论 NO可能通过下调线粒体跨膜电位、开放线粒体膜通透性转变孔并释放线粒体cyt C,来诱导SMMC-7721和HepG2细胞凋亡.     

氧化砷通过线粒体跨膜电位下降与激活Caspase-3诱导多发性骨髓瘤细胞凋亡

目的　探讨氧化砷 (As2 O3)是否诱导多发性骨髓瘤细胞凋亡与其可能机制。方法　以两株多发性骨髓瘤细胞系RPMI82 2 6和U2 66为体外模型。以细胞形态学观察、流式细胞仪检测亚G1期细胞含量以及DNA凝胶电泳判定细胞凋亡。通过检测胞内Rhodamine12 3染色强度来判定线粒体跨膜电位。通过Western印迹分析蛋白表达。结果　 0 1- 0 5μmol LAs2 O3抑制RPMI82 2 6与U2 66细胞系生长 ,2 0 μmol LAs2 O3 诱导两株细胞凋亡 ,而 1 0μmol LAs2 O3抑制细胞生长同时也诱导部分细胞凋亡。As2 O3诱导的细胞凋亡伴随线粒体跨膜电位下降与细胞凋亡 ,而二巯基苏糖醇 (二巯基还原剂 )则部分抑制以上效应。虽然全反式维甲酸 (ATRA)诱导RPMI82 2 6细胞凋亡 ,但是它与As2 O3无协同效应。结论　不同深度As2 O3可抑制多发性骨髓瘤细胞生长与诱导细胞凋亡。线粒体是As2 O3 诱导细胞凋亡的重要且共同的“靶子”。     

As2O3对组织因子、纤溶酶原激活物抑制剂-1和-2表达的影响

目的探讨三氧化二砷(As2O3)在诱导NB4、HL-60和THP-1 白血病细胞凋亡过程中对细胞内组织因子(TF)、纤溶酶原激活物抑制剂(PAI)-1和-2 表达的影响.方法使用不同浓度的As2O3处理NB4、HL-60和THP-1 细胞,以生长曲线观察As2O3对细胞体外增殖的影响,并以琼脂糖电泳及流式细胞术观察细胞凋亡情况;用酶联免疫吸附测定(ELISA)方法检测经As2O3处理后细胞内TF、PA I-1 和-2抗原含量的变化.结果① 1 μmol/L和8 μmol/L的As2O3分别作用NB4和HL-60细胞24 h后,细胞均出现典型的凋亡;而THP-1细胞在8 μmol/L As2O 3作用24 h后未出现细胞凋亡.② 1 μmol/L As2O3下调NB4细胞内TF抗原含量,与对照组相比差异显著(P<0.01),且TF抗原水平的降低呈As2O3剂量依赖性;而2 μmol/L As2O3诱导NB4细胞凋亡过程中,细胞内PAI-1抗原含量增加(P<0.0 5).③ 8 μmol/L As2O3诱导HL-60细胞凋亡过程中,细胞内TF抗原含量增加(P <0.01),但细胞内PAI-2抗原含量降低(P<0.05).④ THP-1细胞在8 μmol/L As 2 O 3处理24 h后,细胞内TF和PAI-2抗原含量均增加(P<0.05和P<0.01). 结论 As2O3对NB4、HL-60和THP-1细胞内的TF、PAI-1和PAI-2的表达有不同的影响.     

Evaluation of sperm mitochondrial function using rh123 /PI dual fluorescent staining in asthenospermia and oligoasthenozoospermia

Objective: The recent advent of flow cytometry (FCM), coupled with fluorescent dyes, has been success-fully applied to assess mitochondrial function. The aim of this study was to investigate the feasibility and clinical significance of detecting sperm mitochondrial function and to evaluate sperm mitochondrial function by using Rhodamine 123/propidium (Rh123/PI) dual fluorescent staining and FCM in asthenospermia and oligoastheno-zoospermia. Methods: Twenty-five fertile men (with normal sperm parameters) and 230 infertile patients were examined. Fifty-five patients of the above 230 patients were selected for idiopathic infertility samples and were divided into two groups: asthenospermia (n = 30) and oligoasthenozoospermia (n = 25). Rh123/PI dual fluorescent staining and FCM were carried out to examine sperm mitochondrial function. Results: Significant differences were found between the normal and abnormal semen samples (P < 0.05) when Rh123+/PI-, Rh123-/PI+ and Rh123-/PI- sperm were examined by FCM, but there was no significant difference between the asthenospermia (P = 0.469) and oligoasthenozoospermia group (P = 0.950) when Rh123+/PI- and Rh123-/PI+ sperm were then examined; how-ever, a significant difference was found between the 2 groups (P = 0.003) when Rh123-/PI- sperm were examined. There was no correlation between Rh123-/PI- sperm and semen parameters in the normal group, but there was a significant negative correlation between the sperm concentration and Rh123-/PI- sperm in asthenospermia and oligoasthenozoospermia patients (r = -0.509, -0.660; P = 0.018, 0.038). Conclusion: Rh123/PI dual fluorescent staining and FCM can provide reliable information to assess the quality of sperm and reveal differences in mito-chondrial membrane potential in asthenospermia and oligoasthenozoospermia.     

Arsenic trioxide-induced apoptosis of human malignant lymphoma cell lines and its mechanisms.

OBJECTIVE: To investigate the responses of human Burkitt lymphoma cells to arsenic trioxide (As2O3) and the possible mechanisms. METHODS: Epstein-Barr virus (EBV)-positive human B-lymphoma Raji cell line and EBV-negative human B-lymphoma BJAB cell line were used as in vitro models to assess the cell apoptosis by morphology and DNA agarose gel electrophoresis. Protein expression was analyzed using Western blotting. RESULTS: After 24-hour treatment with the 2, 5 and 10 micromol/L As2O3, the concentrations of As2O3 achievable in vivo, cell apoptosis was induced in human Burkitt lymphoma BJAB cells at the rates of 47.6%+/-4.8% (Mean+/-SD, n=3), 66.4%+/-5.1%, 87.0%+/-7.3% and at 35.5%+/-3.8%, 51.5%+/-6.2%, 62.2%+/-7.9% respectively in Raji cells, corresponding to the concentration of As2O3. EBV-infected Raji cell line was less sensitive to As2O3 than EBV-negative BJAB cell line (P<0.05). As2O3-induced apoptosis was accompanied by down-regulation of Bcl-xL protein expression and activation of apoptosis protein caspase-3, as identified by Western blotting. CONCLUSION: As2O3 exerts apoptosis-inducing effects on human Burkitt lymphoma cells through down-regulation of Bcl-xL protein expression and activation of apoptosis protein caspase-3, and may serve as a candidate therapeutic agent against malignant lymphoma for both systemic and local therapies.     

丹参酮与三氧化二砷协同诱导急性早幼粒细胞白血病细胞株凋亡的体外研究

目的 为评估丹参酮ⅡA（Tanshinone ⅡA,Tan ⅡA）与三氧化二砷（As2O3）联合应用抑制NB4细胞增殖、诱导其凋亡的效应,观察二药的相互作用和相互影响,期望对两药的临床应用提供理论依据。方法 以不同浓度的As2O3、TanⅡA单独及联合应用作用于急性早幼粒细胞白血病细胞（NB4）作为实验组,通过观察细胞形态学改变,MTT法测定细胞存活率,并采用流式细胞术（FCM）检测细胞周期分布,分析不同浓度的As2O3、TanⅡA单独及联合应用对NB4细胞的增殖、凋亡的影响。结果 TanⅡA、As2O3均能抑制NB4细胞生长,以1.0 μmol/L As2O3作用更显著,二者联合应用后的增殖抑制作用表现为协同效应;经TanⅡA组处理后的NB4细胞,其形态改变更多显示一定程度的成熟粒细胞的特征,As2O3组则更多表现为细胞凋亡的形态学改变,并经电镜检查证实,两药联合应用可加强NB4细胞的凋亡形态改变;处理后的NB4细胞G0/G1期比例增高,S期细胞比例降低,细胞增殖指数（PI）下降,两药联合应用后具有协同效应。结论 1. TanⅡA、As2O3对NB4细胞均有增殖抑制作用,二者的增殖抑制作用具有协同效应,并与剂量相关;2. TanⅡA与As2O3联合作用于NB4细胞具有诱导凋亡作用,两药的诱导凋亡作用具有协同效应;3. 小剂量的As2O3联合TanⅡA即可对NB4细胞产生促进凋亡的效应,故临床可以选择小剂量的As2O3,以减轻砷剂的毒副作用。     

Potentiation of arsenic trioxide-induced apoptosis by retinoic acid in retinoic acid sensitive and resistant HL-60 myeloid leukemia cells

Objective To study the effect of arsenic trioxide (As(2)O(3)) on non-APL acute myeloid leukemia (AML) cells and the interreactive effect between retinoic acid (RA) and As(2)O(3).Methods RA-sensitive (S) and RA-resistant (R) HL-60 non-APL AML cells were used as an in vitro model. Cell number and trypan blue were used to observe cell growth and survival. Apoptosis was determined by morphological changes, using a DNA laddering assay, terminal deoxynucleotidyl transferase (TdT) fragment end labeling assay and a flow cytometry assay. Results As(2)O(3) induced apoptosis in both HL-60S and HL-60R cells, As(2)O(3)-induced apoptosis was both time- and concentration-dependent in a therapeutically-achievable As(2)O(3) range (0.25-4.0 μmol/L). Both all-trans retinoic acid (ATRA) and 9-cis retinoic acid (9cRA) potentiated As(2)O(3)-induced apoptosis, as measured by quantitative TdT fragment end labeling and flow cytometry assays in both HL-60S and HL-60R cells (P&lt;0 .05, for all RA+As(2)O(3) combinations vs As(2)O(3) alone in both sublines). Conclusions As(2)O(3) may inhibit the growth of non-APL AML cells by promoting programmed cell death. RA can potentiate As(2)O(3)-induced apoptosis even in RA-resistant HL-60 cells in which the classical ATRA response pathway is repressed owing to a homozygous inactivating mutation in the retinoic acid receptor α. As[2]O[3] can have clinical activity in non-APL cases of AML and the enhanced activity might result from the combined As(2)O(3)-RA therapy.