乙型肝炎疫苗-卡介苗联合疫苗在动物中的免疫应答

目的评价乙型肝炎疫苗-卡介苗联合疫苗的免疫应答。方法用联合疫苗及其单价疫苗分别免疫豚鼠和BALB/c小鼠,检测两种疫苗的免疫应答。结果联合疫苗与卡介苗豚鼠皮肤PPD反应直径数值相近(P>0·05),联合疫苗与乙肝疫苗免疫小鼠血清乙肝抗体滴度差异无显著意义(P>0·05);联合疫苗免疫小鼠淋巴细胞转化刺激指数、IL-2含量均高于单价疫苗,差异有显著意义(P<0·001)。结论乙型肝炎疫苗-卡介苗联合疫苗能有效地诱导实验动物的体液免疫和细胞免疫。     

两种方法制备甲乙肝联合疫苗的效果比较

目的　观察两种不同方法制备甲乙肝联合疫苗的效果。方法　将甲肝抗原和乙肝抗原分别加Al(OH) 3吸附后混合 ,制备甲乙肝联合疫苗 (方法 1)或将甲肝抗原与乙肝抗原等量混合后 ,加Al(OH) 3吸附 ,制备甲乙肝联合疫苗 (方法 2 ) ,并进行吸附效果、理化性质及效力检测。结果　两种方法制备的联合疫苗理化性质稳定 ,免疫效果良好 ;方法 2制备的联合疫苗其小鼠效力优于方法 1(方法 1甲肝ED50 为 4 2 .0 9EU ml,方法 2为 8.2 0EU ml,P =0 .0 10 )。结论　两种方法制备的联合疫苗均达到了单价疫苗的免疫效果 ,方法 2优于方法 1     

乙型脑炎病毒抗原定量检测试剂的研制

目的制备酶联免疫乙型脑炎病毒抗原定量检测试剂,用于乙型脑炎灭活疫苗中抗原定量检测。方法分别用2株杂交瘤细胞分泌的抗乙型脑炎病毒单克隆抗体作为包被和标记物,配以辅助试剂,建立酶联免疫检测系统,用经标化的乙型脑炎疫苗参考品绘制定量标准曲线,对试剂各项技术指标进行验证。结果试剂对乙型脑炎病毒抗原的最佳定量范围是0·131~0·666ELISA单位(EU/ml),标准曲线相关系数r=0·996,平均变异系数CV小于10%。与NIH法测定结果相比较,相关有非常显著意义(P<0·01)。对2批乙型脑炎疫苗9次测定,变异系数分别为2·7%和4·4%。结论试剂的精密性和准确度高,特异性和稳定性可靠,可用于乙型脑炎疫苗中的抗原定量检测。     

乙型脑炎活疫苗与灭活疫苗诱导小鼠体液和细胞免疫应答的比较

应用检测特异性CTL活性的方法检测乙脑活疫苗的细胞免疫应答 ,并以灭活疫苗作对照。结果显示活疫苗免疫小鼠后诱导的CTL均值为 79 2 % ,较灭活疫苗 2 9%高 5 0 2 % ,表明活疫苗具有较强的特异性CTL活性。用同批活疫苗免疫小鼠后其中和抗体效价为 1:5 ,而同批的灭活疫苗为 1:2 0 ,活疫苗的免疫效力 (ID5 0 ) 3 6× 10 6(ml)显著高于灭活疫苗的 4 0× 10 - 4 ～ 4 2× 10 4(ml)。表明乙脑活疫苗诱导的免疫应答中细胞免疫在保护效力中占有重要地位。     

cGAMP与幽门螺杆菌蛋白抗原肌肉注射诱导BALB/c小鼠免疫应答初步分析

目的初步分析肌肉注射免疫环鸟-腺二核苷酸(cyclic guanosine monophosphate-adenosine monophosphate,cGAMP)与幽门螺杆菌(Helicobacter pylori,H. pylori)蛋白抗原在BLAB/c小鼠中诱导的免疫应答。方法将BALB/c小鼠随机分成4组,cGAMP组、抗原组(H. pylori蛋白抗原)、cGAMP+抗原组及对照组(未免疫),肌肉注射免疫小鼠。间接ELISA法测定免疫后小鼠血清中抗原特异性IgG抗体、胃组织及粪便上清液中IgA抗体;CCK-8法检测小鼠脾淋巴细胞体外增殖水平;酶联免疫斑点法(ELISpot)分析脾淋巴细胞分泌抗原特异性细胞因子水平。结果经肌肉注射免疫,cGAMP+抗原组可诱导小鼠产生显著高于对照组的血清IgG抗体应答(P 0. 01);可诱导胃肠道黏膜产生显著高于单独抗原组的特异性IgA抗体应答(P 0. 05);体外孵育H. pylori蛋白抗原和脾淋巴细胞,促进了淋巴细胞的增殖,cGAMP+抗原组显著高于单独抗原组(P 0. 01);与单独抗原组及对照组比较,cGAMP+抗原组免疫小鼠诱导的脾淋巴细胞中抗原特异性IFNγ分泌细胞数量最多(P 0. 01)。结论 cGAMP通过肌肉注射途径可诱导BLAB/c小鼠对H. pylori蛋白抗原的体液免疫应答及脾脏中抗原特异性淋巴细胞免疫反应,其具有作为肌肉途径免疫H. pylori蛋白疫苗佐剂的潜质。     

抗人膀胱癌抗独特型抗体诱导特异性迟发过敏反应的研究

目的研究对抗人膀胱癌抗独特型抗体(BC2)诱导的特异性迟发过敏反应(DTH)。方法经过BC2免疫的小鼠,用膀胱癌细胞系进行脚掌注射攻击后,测定脚掌水肿厚度判定DTH反应强度,并进行病理学检查。结果BC2诱导的DTH平均水肿厚度为0·95mm,与膀胱癌组织抗原组比较差异无显著意义(P>0·05);免疫鼠对胃癌细胞攻击呈阴性反应;BC2诱导的病变内可见大量炎性细胞,呈弥漫性浸润。结论BC2具有抗原模拟作用,可诱导特异性的DTH反应,可能成为膀胱癌防治的新途径。     

增强ESAT6-CFP10融合蛋白诱导小鼠细胞免疫应答佐剂的筛选

目的筛选能增强特异性抗原早期分泌抗原靶6蛋白(Early secretory antigenic target 6,ESAT6)-培养滤出液蛋白-10(Culture filtrate protein 10,CFP-10)融合蛋白(E1C0)诱导小鼠细胞免疫应答的佐剂,建立基于细胞免疫应答的小鼠模型,以评价基于体外干扰素γ释放分析(IFNγrelease assay,IGRA)结核诊断方法中特异性刺激抗原E1C0的活性。方法建立小鼠IFNγ双抗体夹心SABC-ELISA检测系统,并验证系统的线性、灵敏度、重复性和特异性。将BALB/c小鼠随机分为7组:E1C0+单磷酸类脂A(Monophosphoryl lipid A,MPL)+双十八烷基二甲基溴化铵(Dimethyl dioctadecylammonium bromide,DDA)组、E1C0+DDA组、E1C0+MPL组、E1C0+弗氏不完全佐剂(IFA)组、E1C0组、生理盐水组和MPL+DDA联合组,每组6只,经小鼠后肢内侧皮下免疫3次,间隔2周,免疫剂量为:E1C0 100μg/只,MPL 25μg/只,DDA 250μg/只,IFA 100μl/只。末次免疫4周后处死小鼠,无菌取脾,分离脾淋巴细胞,加入E1C0进行培养,MTT法检测特异性淋巴细胞增殖反应,ELISA法检测培养上清中IFNγ水平。采用筛选出的最佳佐剂与抗原组合免疫3批BALB/c小鼠,进行IFNγ诱生测定。结果检测系统的线性范围为:40～2 560 pg/ml(R>0.98);灵敏度为40 pg/ml;变异系数(CV)<15%,检测大鼠、豚鼠和兔血清IFNγ均为阴性;E1C0+MPL+DDA组、E1C0+IFA组和E1C0+DDA组小鼠特异性淋巴细胞增殖刺激指数均明显高于生理盐水组(P<0.01);E1C0+MPL+DDA组小鼠的脾淋巴细胞经E1C0体外刺激后,产生的IFNγ水平明显高于其他组(P<0.001);重复试验结果显示,E1C0+MPL+DDA组3批小鼠免疫后,脾淋巴细胞诱生的IFNγ水平差异无统计学意义(P>0.05)。结论 E1C0与MPL和DDA联合免疫所诱导的小鼠Th1型细胞免疫应答最强,成功建立了用于评价刺激抗原E1C0活性的小鼠模型。     

三种常见乙型肝炎患者的血清蛋白谱特点

目的分析3种常见乙型肝炎病人的血清蛋白谱特征。方法采用酶联免疫吸附实验检测乙肝标志物,双缩脲法检测总蛋白,溴甲酚绿法(BCG)检测白蛋白,琼脂糖凝胶电泳法分析血清蛋白组分。结果乙型肝炎病毒表面抗原阳性携带者与正常人血清蛋白各组分之间差异无显著意义(P>0·05);乙型肝炎患者与正常人血清蛋白各组分之间差异均有显著意义(P<0·01)。乙型肝炎患者HBsAg(+)、HBeAg(+)、HBcAb(+)组与乙型肝炎患者HBsAg(+)、HBeAb(+)、HBcAb(+)组血清蛋白各组分相比较,Alb呈显著降低(P<0·05);α1、α2、β差异无显著意义(P>0·05),γ球蛋白呈显著升高(P<0·05)。结论血清蛋白电泳、总蛋白、白蛋白联合检测可全面了解乙型肝炎患者血清蛋白谱的变化特征,对乙型肝炎的临床诊断和疗效观察有重要的参考价值。     

小鼠多能干细胞对小鼠肝脏电离辐射损伤的作用

目的探讨小鼠多能干细胞(mouse pluripotent stem cells,miPS)对小鼠肝脏电离辐射损伤的作用。方法采用医用电子直线加速器进行单次全身性照射(电子辐射线源为6 MeV,照射总剂量为8 Gy,照射剂量率为1. 0 Gy/min)。辐射组于辐射后12和24 h,经小鼠尾静脉注射生理盐水(200μL/只);治疗组于照射后12和24 h,经尾静脉注射mi PS细胞悬浮液[3×106个/(200μL·只)];对照组小鼠不进行辐射,仅注射生理盐水(200μL/只)。末次注射后1、3、7、14 d,记录小鼠体重、计算肝脏指数,并检测小鼠肝脏中超氧化物歧化酶(superoxide dismutase,SOD)及丙二醛(malondialdehyde,MDA)水平;末次注射后14 d,观察小鼠状态,并采用组织病理学方法观察肝脏病理形态学变化。结果与对照组比较,辐射组小鼠精神状态和食欲状况均不佳,体重显著降低(P <0. 05),肝脏指数差异无统计学意义(P> 0. 05),肝脏中SOD活性显著降低(P <0. 01),MDA水平显著升高(P <0. 05);与辐射组比较,治疗组小鼠体重明显升高(P <0. 05),肝脏指数差异无统计学意义(P> 0. 05),肝脏中SOD活性显著升高(P <0. 05),MDA水平显著降低(P <0. 01)。对照组小鼠肝脏组织无明显病变;辐射组小鼠肝细胞发生明显肿胀及肝细胞索紊乱等明显病理变化;治疗组小鼠肝细胞索排列整齐,肝细胞轻度肿胀,病理变化得到改善。结论 miPS可通过其增殖分化减少小鼠体内氧化应激产生的细胞凋亡,对电离辐射造成的小鼠肝脏损害有明显的修复作用。     

转人HLA-A2基因小鼠对adr亚型重组乙型肝炎疫苗(汉逊酵母)的免疫应答

目的对汉逊酵母表达的adr亚型重组乙型肝炎(简称乙肝)疫苗(adr疫苗)进行免疫学特性与功能学研究。方法采用adr疫苗与酿酒酵母表达的重组乙肝疫苗(adw疫苗)免疫转人HLA-A2基因小鼠,免疫剂量2μg/0.2 ml,于初免3周后进行第2次免疫。于第2次免疫1周后,采血,分离血清,经ELISA法检测小鼠血清中抗-HBs抗体水平。同时取小鼠脾脏,制备脾细胞悬液,采用HLA-A2/WLSLLVPFV五聚体荧光标记流式细胞术分析细胞中特异性抗乙肝病毒表位的CTL比例。结果 adr疫苗与adw疫苗均可诱导转基因小鼠产生抗乙肝表面抗原抗体,且抗体水平差异无统计学意义(P>0.05),2种疫苗对转基因小鼠的体液免疫应答的增强作用相似;adr疫苗诱导的乙肝表面抗原特异性CTL应答作用较adw疫苗更明显(P<0.05)。结论 adr重组乙肝疫苗(汉逊酵母)诱导转基因小鼠的体液免疫应答作用与现有adw疫苗相似,但其诱导机体产生细胞免疫应答的能力更显著,可能具有更加良好的预防HBV感染作用和前景。     

Passive Immune-Protection of Litopenaeus vannamei against Vibrio harveyi and Vibrio parahaemolyticus Infections with Anti-Vibrio Egg Yolk (IgY)-Encapsulated Feed

Vibrio spp. are major causes of mortality in white shrimp (Litopenaeus vannamei) which is lacking adaptive immunity. Passive immunization with a specific egg yolk antibody (IgY) is a potential method for the protection of shrimp against vibriosis. In this study, immune effects of the specific egg yolk powders (IgY) against both V. harveyi and V. parahaemolyticus on white shrimp were evaluated. The egg yolk powders against V. harveyi and V. parahaemolyticus for passive immunization of white shrimp were prepared, while a tube agglutination assay and an indirect enzyme-linked immunosorbent assay (ELISA) were used for detection of IgY titer. Anti-Vibrio egg yolk was encapsulated by β-cyclodextrin, which could keep the activity of the antibody in the gastrointestinal tract of shrimp. The results showed that the anti-Vibrio egg powders had an inhibiting effect on V. harveyi and V. parahaemolyticus in vitro. Lower mortality of infected zoeae, mysis, and postlarva was observed in groups fed with anti-Vibrio egg powders, compared with those fed with normal egg powders. The bacterial load in postlarva fed with specific egg powders in seeding ponds was significantly lower than those fed with normal egg powders in seeding ponds. These results show that passive immunization by oral administration with specific egg yolk powders (IgY) may provide a valuable protection of vibrio infections in white shrimp.     

蛋白对HCV/HBV DNA疫苗的免疫增强作用

目的探讨蛋白对HCV/HBV DNA疫苗的免疫增强作用。方法将构建的HCV/HBV真核表达载体pcDNA-PCXS和蛋白分别免疫BALB/c小鼠,用ELISA的方法检测抗-HBs和抗-HCV Ab;3H-TdR掺入法检测免疫小鼠T淋巴细胞增殖;51Cr释放法检测免疫小鼠特异性CTLs杀伤作用。结果DNA-蛋白组抗-HBs和抗-HCV抗体均较DNA组出现早,且抗体水平明显高,DNA-蛋白组的CTL应答水平也明显高于DNA组。结论蛋白能提高DNA疫苗的特异性体液和细胞免疫功能,为DNA疫苗的实际应用提供了一种新的策略。     

Human Adipose-Derived Mesenchymal Stem Cells Are Resistant to HBV Infection during Differentiation into Hepatocytes in Vitro

The therapeutic methods for chronic hepatitis B are limited. The shortage of organ donors and hepatitis B virus (HBV) reinfection obstruct the clinical application of orthotopic liver transplantation (OLT). In the present study, adipose-derived mesenchymal stem cells (AD-MSCs) and bone marrow-derived mesenchymal stem cells (BM-MSCs) were isolated from chronic hepatitis B patients and characterized for morphology, growth potency, surface phenotype and the differentiation potential. The results showed that both MSCs had adipogenic, osteogenic and neuron differentiation potential, and nearly all MSCs expressed CD105, CD44 and CD29. Compared with AD-MSCs, BM-MSCs of chronic hepatitis B patients proliferated defectively. In addition, the ability of AD-MSCs to differentiate into hepatocyte was evaluated and the susceptibility to HBV infection were assessed. AD-MSCs could differentiate into functional hepatocyte-like cells. These cells express the hepatic-specific markers and have glycogen production and albumin secretion function. AD-MSCs and hepatic differentiation AD-MSCs were not susceptible to infection by HBV in vitro. Compared with BM-MSCs, AD-MSCs may be alternative stem cells for chronic hepatitis B patients.     

ATP5B Is an Essential Factor for Hepatitis B Virus Entry

Elucidation of the factors responsible for hepatitis B virus (HBV) is extremely important in order to understand the viral life cycle and pathogenesis, and thereby explore potential anti-HBV drugs. The recent determination that sodium taurocholate co-transporting peptide (NTCP) is an essential molecule for the HBV entry into cells led to the development of an HBV infection system in vitro using a human hepatocellular carcinoma (HCC) cell line expressing NTCP; however, the precise mechanism of HBV entry is still largely unknown, and thus it may be necessary to elucidate all the molecules involved. Here, we identified ATP5B as another essential factor for HBV entry. ATP5B was expressed on the cell surface of the HCC cell lines and bound with myristoylated but not with non-myristoylated preS1 2-47, which supported the notion that ATP5B is involved in the HBV entry process. Knockdown of ATP5B in NTCP-expressing HepG2 cells, which allowed HBV infection, reduced HBV infectivity with less cccDNA formation. Taken together, these results strongly suggested that ATP5B is an essential factor for HBV entry into the cells.     

Low cholesterol egg powder. Nutritive and quality characteristics of the product

The purpose of this study is to obtain a low cholesterol egg powder for the preparation of different foods for persons whose egg consumption is restricted. Egg white and yolk mixtures prepared in different proportions were dehydrated; the following dried mixtures were obtained: A (1:1), B (2:1) and C (3:1) of egg white:yolk respectively. These mixtures were evaluated using the following parameters: proximal analysis, microbiological assay and protein quality evaluation. Physical characteristics of the powder and the sensorial tests of foods prepared with these mixtures were carried out. The fat and the cholesterol content in the mixture C were decreased by 40% and 20% respectively. The microbiological tests showed that the three mixtures were safe for human consumption. The PER of sample A (whole egg) was 3.65 and for the mixture C 3:1 egg white:yolk was 3.05. The PER of the 50:50 protein mixtures eggs white and yolk: with corn lime treated flour (HMN) were higher than that of the casein standard. The sensorial tests of the foods prepared with all the mixtures were acceptable.     

Reactivation of Hepatitis B Virus in Hematopoietic Stem Cell Transplant Recipients in Japan: Efficacy of Nucleos(t)ide Analogues for Prevention and Treatment

We retrospectively reviewed 413 recipients with hematologic malignancies who underwent hematopoietic stem cell transplantation (HSCT) between June 1986 and March 2013. Recipients with antibody to hepatitis B core antigen (anti-HBc) and/or to hepatitis B surface antigen (anti-HBs) were regarded as experiencing previous hepatitis B virus (HBV) infection. Clinical data of these recipients were reviewed from medical records. We defined ≥1 log IU/mL increase in serum HBV DNA from nadir as HBV reactivation in hepatitis B surface antigen (HBsAg)-positive recipients, and also defined ≥1 log IU/mL increase or re-appearance of HBV DNA and/or HBsAg as HBV reactivation in HBsAg-negative recipients. In 5 HBsAg-positive recipients, 2 recipients initially not administered with nucleos(t)ide analogues (NUCs) experienced HBV reactivation, but finally all 5 were successfully controlled with NUCs. HBV reactivation was observed in 11 (2.7%) of 408 HBsAg-negative recipients; 8 of these were treated with NUCs, and fortunately none developed acute liver failure. In 5 (6.0%) of 83 anti-HBc and/or anti-HBs-positive recipients, HBV reactivation occurred. None of 157 (0%) recipients without HBsAg, anti-HBs or anti-HBc experienced HBV reactivation. In HSCT recipients, HBV reactivation is a common event in HBsAg-positive recipients, or in HBsAg-negative recipients with anti-HBc and/or anti-HBs. Further attention should be paid to HSCT recipients with previous exposure to HBV.     

Intravenous injection of tridihomo-γ-linolenoyl-glycerol into mice and its effects on delayed-type hypersensitivity

Highly purified tridihomo-γ-linolenoyl-glycerol (DGLA-TG) was emulsified with egg yolk lecithin as a 10% (wt/vol) DGLA-TG emulsion. We injected 0.05 or 0.5 mL of the emulsion into mice through the tail vein and investigated its effects on the fatty acid composition of spleen cells and on delayed-type hypersensitivity (DTH) response. At 1 h after the injection, dihomo-γ-linolenic acid (DGLA) concentrations were increased significantly in the total phospholipid fraction of spleen cells from 1.21±0.13 mol% to 2.09 ±0.74 mol% (P<0.02) and 7.95±1.25 mol% (P<0.001) in the 0.05-mL and 0.05-mL groups respectively. Mice, which had already been immunized with sheep red blood cells (SRBC), were challenged by the injection of SRBC into the right-hind footpad. Intravenous injection into mice with 0.5 mL of the emulsion immediately before the challenge almost completely suppressed DTH response measured by the swelling of the right-hind footpads 24 h thereafter. This inhibitory effect on the DTH response was significant with as little as 0.05 mL of the emulsion, whereas a soybean oil emulsion was not effective at all. In conclusion, intravenous injection of a DGLA emulsion increased DGLA concentrations in immune cells within 1 h and suppressed the DTH reaction.     

Hepatitis B Virus Infection,MicroRNAs and Liver Disease

Hepatitis B virus (HBV) attacks the liver and can cause both acute as well as chronic liver diseases which might lead to liver cirrhosis and hepatocellular carcinoma. Regardless of the availability of a vaccine and numerous treatment options, HBV is a major cause of morbidity and mortality across the world. Recently, microRNAs (miRNAs) have emerged as important modulators of gene function. Studies on the role of miRNA in the regulation of hepatitis B virus gene expression have been the focus of modern antiviral research. miRNAs can regulate viral replication and pathogenesis in a number of different ways, which includefacilitation, direct or indirect inhibition, activation of immune response, epigenetic modulation, etc. Nevertheless, these mechanisms can appropriately be used with a diagnosticand/or therapeutic approach. The present review is an attempt to classify specific miRNAs that are reported to be associated with various aspects of hepatitis B biology, in order to precisely present the participation of individual miRNAs in multiple aspects relating to HBV.     

Lysophosphatidic Acid Produced by Hen Egg White Lysophospholipase D Induces Vascular Development on Extraembryonic Membranes

Lysophosphatidic acid (lysoPtdOH), a lysophospholipid mediator, exerts diverse physiological effects, including angiogenesis, through its specific G‐protein‐coupled receptors. Previously, we showed that unfertilized hen egg white contains polyunsaturated fatty acid‐rich lysoPtdOH and lysophospholipase D (lysoPLD). Here, we examined whether lysoPtdOH was produced by lysoPLD in the presence and absence of a hen fertilized ovum and what the physiological role of lysoPtdOH in hen egg white is. Mass spectrometry showed that fertilized hen egg white contained about 8 μM lysoPtdOH before incubation with an ovum, mainly comprised of 18:1‐ (12.6 %), 18:2‐ (37.8 %) and 20:4‐molecular species (41.5 %). In an early gestation period, the lysoPtdOH was increased up to 9.6 μM, concomitant with a decrease in the level of polyunsaturated lysophosphatidylcholine (lysoPtdCho). Moreover, lysoPtdOH‐degrading activities were found in egg white and the vitelline membrane, showing that these enzymes control lysoPtdOH levels in egg white. In an egg yolk angiogenesis assay, two lysoPtdOH receptor antagonists, Ki16425 and N‐palmitoyl serine phosphoric acid (NASP), inhibited blood vessel formation induced by exogenously added 18:1‐lysoPtdOH and its precursor lysoPtdCho on the hen yolk sac. Ki16425 and NASP also inhibited blood vessel formation in the chorioallantoic membrane (CAM). Furthermore, the relatively higher levels of LPA₁, LPA₂, LPA₄ and LPA₆ mRNA were present in the yolk sac and CAM. These results suggest that lysoPtdOH produced from lysoPtdCho by the action of lysoPLD in hen egg white is involved in the formation of blood vessel networks through several lysoPtdOH receptors on various extraembryonic membranes, including the yolk sac membrane and CAM.     

Novel method to administer radiolabeled lipid to juvenile oysters

Particles prepared from egg yolk were shown to encapsulate protein and to be in a size range that would be filtered by the oyster. A radiotracer study involving the addition of radiolabeled phosphatidylcholine to egg yolk demonstrated that the egg yolk particles were taken up and metabolized by juvenile oysters (Crassostrea gigas). Catabolism of the radiolabeled lipid and subsequent resynthesis into non-lipid components occurred to a slight extent. The main factor responsible for the distribution of radioactivity amongst the lipids in the stomach tissue was believed to be transacylation.