Aflatoxin P-1: a new aflatoxin metabolite in monkeys

A new phenolic derivative of aflatoxin B(1), appearing mainly in conjugated form, was identified as the principal urinary metabolite of aflatoxin B(1) in rhesus monkeys. Its identification in human urine might facilitate estimation of aflatoxin exposure in human populations.     

乙腈溶液中黄曲霉毒素B1的电子束辐射降解行为的研究

为了研究复杂食品体系中黄曲霉毒素B1的降解行为,以黄曲霉毒素B1为研究对象,以乙腈为简单溶剂系统模型,利用高效液相色谱法,对辐照前后黄曲霉毒素B1进行定量,研究不同辐照剂量、不同毒素初始浓度等因素对黄曲霉毒素B1电子束辐射降解效果的影响。结果表明:电子束辐射能够有效地去除乙腈溶液中的黄曲霉毒素B1。在实验范围内,随着辐照剂量、初始浓度的增加,黄曲霉毒素B1的降解率增加。     

Aflatoxin B1: binding to DNA in vitro and alteration of RNA metabolism in vivo

Aflatoxin B(1) binds to both native and denatured DNA, as shown by spectroscopy and equilibrium dialysis. It also strongly inhibits incorporation of cytidine into rat liver nuclear RNA and lowers the RNA content of the nucleus. The extremle toxicity and carcinogenicity of aflatoxin B(1) may be direct results of the affinity of this agent for DNA.     

黄曲霉毒素的脱毒研究进展

黄曲霉毒素是由真菌代谢产生的天然毒素,主要分为B族黄曲霉毒素、G族黄曲霉毒素及M族黄曲霉毒素。黄曲霉毒素对人类和动物具有较高的毒性、致畸性、诱变性和致癌性,其中黄曲霉毒素B_1的毒性最高,且黄曲霉毒素B_1和黄曲霉毒素M_1被国际癌症研究机构列为一级致癌物。因此,黄曲霉毒素的脱毒越来越受到国内外的广泛关注。主要对国内外黄曲霉毒素的物理脱毒方法、化学脱毒方法及生物脱毒方法进行综述,重点对生物脱毒方法的种类、脱毒机理和降解产物的毒性进行了评述,并提出研究展望。     

黄曲霉毒素B1单克隆抗体的制备与鉴定

[目的]为黄曲霉毒素类生物毒素研究提供试验参考。[方法]黄曲霉毒素B1与人血清白蛋白耦联后免疫BALB/c小鼠,取小鼠脾细胞与小鼠骨髓瘤细胞进行细胞融合,通过阳性株的筛选和克隆等步骤,制备了3株稳定分泌抗黄曲霉毒素B1的单克隆抗体,用酶联免疫吸附试验测定抗体的效价和特异性。[结果]成功地筛选出能够分泌抗黄曲霉毒素B1的单克隆抗体杂交瘤细胞株,制备出对黄曲霉毒素B1具有高亲合力、高特异性的单克隆抗体。[结论]为鲜奶及奶粉的快速筛检提供了技术支持。     

花生中黄曲霉毒素检测方法的研究

[目的]建立了利用荧光光度法串联高效液相色谱法同时检测花生中4种黄曲霉毒素(B1、B2、G1和G2)的方法。[方法]样品经提取净化、荧光计初步筛选后,再利用高效液相色谱法进行确证分析。[结果]黄曲霉毒素B1、B2、G1、G2能达到完全的基线分离,检出限分别为0.3、1.0、0.3和1.0μg/kg,范围内线性关系良好,γ>0.999,回收率可达70%~96%,相对标准偏差低于9.4%。[结论]该方法快速、准确、灵敏且经济,能够满足花生中黄曲霉毒素B1、B2、G1、G2检验的需要。     

噬菌体展示纳米抗体模拟黄曲霉毒素抗原的活性表征

【目的】笔者实验室前期免疫并构建噬菌体展示纳米抗体库,应用此抗体库筛选、制备可以用作黄曲霉毒素无毒替代抗原的纳米抗体。本研究旨在探明已筛选出的噬菌体展示纳米抗体Phage 2-5用作黄曲霉毒素替代抗原的活性,为后续纳米抗体的合成以及黄曲霉毒素绿色免疫分析方法的建立奠定基础。【方法】前期,笔者实验室对羊驼免疫黄曲霉毒素抗原（AFB1-BSA）,经过5次免疫后,取血,提取RNA,反转录为cDNA,并采用PCR技术对抗体可变区VHH区域进行扩增,与载体pComb3X偶联,构建噬菌体展示纳米抗体库;经过吸附-洗脱的淘选过程筛选出能够与黄曲霉毒素竞争结合抗黄曲霉毒素单克隆抗体1C11的噬菌体展示纳米抗体Phage 2-5。本研究通过将抗黄曲霉毒素单克隆抗体1C11固定在酶标板上,以噬菌体展示纳米抗体Phage2-5作为竞争抗原,与反应体系中的游离黄曲霉毒素竞争结合抗体,构建酶联免疫分析（ELISA）体系,检测游离黄曲霉毒素含量,并分别对该方法的灵敏度、交叉反应率、缓冲液和样品基质对反应体系的影响进行测定。【结果】采用棋盘法确定了抗体最佳包被浓度为1.25 mg·mL-1,噬菌体最佳使用浓度为5´1011 pfu/mL。在最优条件下建立基于噬菌体展示纳米抗体Phage2-5的ELISA法,对黄曲霉毒素B1的IC50值为0.054 ng·mL-1,对黄曲霉毒素B2、G1、G2、M1的交叉反应率分别为38.6%、70.1%、14.5%、14.6%;反应最高耐受甲醇浓度为20%;当pH值为7.0时,反应灵敏度最高,升高或降低pH对反应灵敏度均有影响;盐离子浓度对反应灵敏度影响不大,反应体系在5´PBS的环境下仍能保持较高活性,但纯水溶液不利于反应的进行;因此,该反应的最佳反应缓冲液是pH值为7.0的0.01 mol·L-1 磷酸盐缓冲液（PBS）,花生、大米、玉米基质对反应体系无显著影响。【结论】噬菌体展示纳米抗体Phage2-5具备良好的模拟黄曲霉毒素抗原的生物活性,用作替代抗原建立的免疫分析方法灵敏度高、甲醇耐受能力强,并且样品基质效应不明显,具有进一步研制黄曲霉毒素模拟抗原的前景。     

The Metabolic Responses of Aspergillus flavus to N-Acetylcysteine, Ascorbate, and H2O2

Aflatoxin, the secondary metabolite of Aspergillus flavus and A. parasiticus, is the most toxic product in nature. In this study, N-acetylcysteine （NAC）, ascorbate, and H2O2 were used to ascertain their effects on fungal metabolic response of A. flavus. The results demonstrated that NAC did not affect fungal growth, but inhibited the aflatoxin Bt production, with the concomitant sporulation reduction. NAC increased the ratio of reduced glutathione （GSH） and oxidized glutathione （GSSG）, but decreased the activity of glutathione reductase （GR）. Ascorbate had similar effect on fungal growth, sporulation, and GR activity, but GSH/GSSG and total glutathione （tGSH, including GSH and GSSG） were significantly increased. H2O2 at high concentration （5 mM） inhibited fungal growth, but the aflatoxin production was increased. At the same time, it reduced GR activity and enhanced tGSH. Though reductive agents had different effects on GSH metabolism, reductive conditions inhibited aflatoxin production and sporulation without any effect on fungal growth. The results in this report confirmed that the relationship between oxidative stress and aflatoxin production is theoretically important in controlling aflatoxin contamination.     

柱前衍生高效液相色谱法测定植物油中黄曲霉毒素B1

[目的]建立柱前衍生高效液相色谱法测定植物油中黄曲霉毒素B1含量的方法。[方法]样品甲醇水溶液（45＋55）、三氯甲烷提取浓缩之后,用苯乙腈（2＋98）溶解,三氟乙酸衍生,反相C18柱分离,荧光检测器检测,所用激发及发射波长依次为365、440nm。[结果]试验表明,黄曲霉毒素B。线性关系良好,对添加黄曲霉毒素B1的样品进行加标回收试验,回收率在89．5％,重复性试验相对标准偏差（n=6）为2．34％。[结论]该法操作简单、线性范围广、效果良好,可用于测定植物油中黄曲霉毒素B1的含量。     

黄曲霉毒素对大白鼠体液免疫作用的研究

研究了玉米中的黄曲霉毒素（Ａｆ，含Ｂ１，１０００μｇ／Ｋｇ）对大白鼠体液免疫的作用．把５２只成年雄性大白鼠分成实验组（Ｅ组）３５只和对照组（Ｃ组）１７只．在第８周、２０周和４０周分３批扑杀，第１，２次扑杀Ｅ１，Ｅ２组各１０只，Ｃ１，Ｃ２组各５只；第３次扑杀Ｅ３组１３只，Ｃ３组７只．其中Ｅ２—６出现小灶性肝细胞型肝癌，另外２只Ｅ３—１０和Ｅ３—１５分别在第２５周和第４０周自然死亡，均在肝中间叶发生纤维型间皮瘤．Ｅ１组动物血中ｒ球蛋白含量显著增高（Ｐ＜０．００１）；Ｅ１组总补体活性（ＣＨ５０）没有变化，而Ｅ２组则明显下降（Ｐ＜０．１）；Ｅ３组与Ｃ３组球蛋白无明显差别，但Ｅ３组产生特异性１９Ｓ抗体的能力明显下降（Ｐ＜０．０５）．结果表明，Ａｆ对大白鼠体液免疫有严重损伤作用．     

Growth in vitro of cells from hyperplastic nodules of liver induced by 2-fluorenylacetamide or aflatoxin B1

Cell suspensions obtained from hyperplastic nodules induced in rat liver by either of the two hepatic carcinogens, 2-fluorenylacetamide or aflatoxin B(1), show growth when cultured in vitro. No growth of cells from liver adjacent to the hyperplastic nodules or from liver of control rats has been obtained so far under comparable conditions. Hepatocarcinoma cells induced by 2-fluorenylacetamide grow readily in vitro but behave differently. These findings suggest that some nonmalignant cells capable of growth in vitro arise during liver carcinogenesis prior to the appearance of unequivocal cancer. Cultures of such cells may offer new avenues for the study of liver carcinogenesis.     

雏鸭黄曲霉毒素中毒与曲霉菌病并发病例的病理学诊断

对湖北省襄樊某鸭场病死雏鸭进行了流行病学调查、病理解剖、病理组织学观察、饲料黄曲霉毒素B1检测等一系列诊断。结果表明:死亡雏鸭肝脏肿大,肝质硬化,表面有白色网格状花纹;肺脏表面及切面有灰白色病灶;肝细胞发生水泡变性和脂肪变性及坏死,胆管上皮细胞呈条索状增生;肺脏内有肉芽肿形成,肺气管内可见霉菌菌丝;饲料中黄曲霉毒素B1含量为8.3μg/kg。据以上结果,确诊为雏鸭黄曲霉毒素中毒和曲霉菌病并发。     

贵州省辣椒制品中黄曲霉毒素B1的污染调查

为了解贵州省辣椒制品中黄曲霉毒素B1的污染情况,采用ELISA方法对2009—2010年贵州省9个地区市场销售的669份辣椒制品中黄曲霉毒素B1含量进行检测分析。结果表明,贵州省辣椒制品中总体存在黄曲霉毒素B1的轻度污染,尤其是干辣椒制品中黄曲霉毒素B1的污染情况较重。     

北京地区被检饲料及饲料原料黄曲霉毒素污染情况的调查

【目的】了解目前北京市养殖场所用饲料原料和配合饲料受黄曲霉毒素的污染情况、检出频率和特点,为饲料生产和养殖企业提供数据参考。【方法】抽样采集北京市21个养殖场187份饲料样,采用免疫亲和柱-光化学衍生-高效液相色谱法测定黄曲霉毒素（B1、B2、G1和G2）的含量。【结果】玉米、麸皮、豆粕、DDGS、猪配合饲料和家禽配合饲料中黄曲霉毒素B1的检出率分别为50.0%、46.2%、33.3%、94.1%、67.1%和94.3%,平均含量分别为5.98、0.25、1.00、9.83、2.89和1.06 µg•kg-1,超标率分别为6.2%、0.0%、0.0%、5.9%、6.6%和0.0%。【结论】各类饲料不同程度地受到黄曲霉毒素污染,其中AFB1污染程度较严重;部分配合饲料、玉米和DDGS的AFB1平均含量较高,超标率也较高。     

Binding Capacity for Aflatoxin B1 by Different Adsorbents

In this article, in vitro adsorption of aflatoxin B1 （AFB1） onto different adsorbents was characterized and the result was verified by comparing the growth performance and serum protein levels of broilers exposed to aflatoxin-contamination feed. Main components of adsorbents selected were yeast cell extracts （Product A）, HSCAS （Product B）, and a mixture of yeast product and HSCAS （Product C）, respectively. A total of 240 broilers were assigned to eight treatments, and the effects of three types of adsorbents on growth performance and serum protein levels were evaluated. Results indicated that Product B had the highest in vitro affinity for AFB1, followed by Product C and Product A. Product B bound 97.69% of the AFB1 in solution in 10 min, and it remained over 96.03% in 60 min at pH 8.0. The B-AFB1 complex was much stronger than the other two complexes in vitro condition （P 〈 0.05）. Feed intake （FI） and average daily gain （ADG） decreased （P 〈 0.05） and feed gain ratio increased （P 〈0.05） in the treatment fed aflatoxin-contaminated feed versus treatment on the basal feed. Serum total protein （TP）, albumin （ALB）, and globulin （GLOB） levels were significantly decreased （P〈0.05）. Product B （0.15%） increased growth performance and improved serum protein levels, Product A and Product C were not as effective as Product B. Three adsorbents tested here had sufficient potential to AFBt in some extents and Product B could bind AFB1 more effectively than Product A and Product C. These results indicated that Product B could alleviate some of the AFBt toxic effect in broilers.     

3种吸附剂对黄曲霉毒素B1吸附能力的研究

 【目的】体外试验评价3种吸附剂（吸附剂A：主成分为酵母细胞壁提取物;吸附剂B：主成分为水合铝硅酸盐;吸附剂C为复合物,主成分是酵母细胞壁及水合铝硅酸盐）对黄曲霉毒素B1（AFB1）的吸附效果,并通过吸附剂对摄入AFB1肉仔鸡生长性能及血清蛋白水平的影响验证体外试验结果。【方法】（1）pH为2.0、6.0、8.0的磷酸盐缓冲溶液（PBS溶液）、人工胃液和人工肠液环境下吸附剂对AFB1的吸附能力;（2）吸附剂对AFB1的结合速率;（3）吸附剂结合AFB1形成的复合体的稳定性;（4）240只1日龄雄性AA肉仔鸡,随机分为8个处理,比较吸附剂对摄入AFB1肉仔鸡生长性能及血清蛋白水平的影响。【结果】（1）5种酸碱条件下吸附剂结合AFB1的能力大小顺序为B＞C＞A;（2）吸附剂B在10 min内对AFB1吸附率达到97.69 %,且60 min内一直处在96.03 %以上,而吸附剂A、C在60 min内对AFB1的吸附能力不稳定;（3）与吸附剂A、C相比较,体外条件下吸附剂B与AFB1形成的复合体解吸附率最低;（4）与基础组比较,AFB1组肉仔鸡采食量、体重增加显著下降,料重比显著增加（P＜0.05）,血清总蛋白（TP）、白蛋白（ALB）、球蛋白（GLOB）水平均显著下降（P＜0.05）。3种吸附剂均能提高肉仔鸡生长性能,吸附剂B能显著改善摄入AFB1污染日粮（98.98 μg?kg-1）的肉仔鸡血清蛋白水平的降低,添加吸附剂A或C效果不显著。【结论】3种吸附剂对AFB1均有一定的吸附作用,吸附剂B的作用效果优于吸附剂A和吸附剂C。结果提示,将吸附剂B应用于被AFB1污染的家禽饲料中,与其它霉菌毒素管理措施相结合,能降低AFB1对肉仔鸡的危害。     

黄曲霉毒素B1诱导MEK/ERK/ROS介导的巨噬细胞自噬反应

为研究黄曲霉毒素B1(AFB1)能否诱导细胞自噬,并初步探讨其可能的作用机制。利用免疫荧光、酶标仪检测、免疫印迹等技术检测经AFB1处理过的细胞的自噬水平、相关蛋白的表达量以及活性氧(Reactive oxygen species,ROS)的产生情况。结果表明:AFB1能够引起RAW264.7细胞和Hela细胞的自噬反应,并且该自噬为完全自噬。AFB1诱导的小鼠单核巨噬细胞RAW264.7自噬是依赖细胞外信号调节激酶(Extracellular signal-regulated kinase,ERK)途径发生的,并受ROS的调节。此外,发现AFB1诱导ROS产生呈浓度依赖性,而ROS抑制剂同时抑制了ROS和自噬发生,但自噬抑制剂并没有有效地抑制ROS的产生,表明ROS处于AFB1诱导自噬的上游,对自噬起到调节作用。这表明AFB1诱导的自噬现象在细胞中普遍存在,而自噬作为机体的免疫机制,在抵抗AFB1毒力侵染的过程中发挥重要作用。     

Neuroleptic-induced decrease in plasma homovanillic acid and antipsychotic activity in schizophrenic patients

Plasma-free homovanillic acid, a major metabolite of dopamine, was measured in chronically ill schizophrenic patients both before and during treatment with the antipsychotic phenothiazine, fluphenazine. Neuroleptic treatment was associated with a significant time-dependent decrease in plasma homovanillic acid from pretreatment values, which were significantly elevated when compared with those of age- and sex-matched healthy control subjects. Further, both the absolute concentrations as well as the neuroleptic-induced reductions in plasma homovanillic acid determined over 5 weeks of neuroleptic treatment were statistically significantly correlated with ratings of psychosis and improvement in psychosis, respectively. These findings suggest that the delayed effects of neuroleptic agents on presynaptic dopamine activity may more closely parallel their therapeutic actions than do their immediate effects in blocking postsynaptic dopamine receptors and that a decrease in dopamine "turnover" may be responsible for their antipsychotic effects.     

不同贮藏方式对花生仁品质的影响

以赣花7号花生为试验材料,采用低温贮藏、干燥贮藏、气调贮藏和通风贮藏对花生仁进行处理,检测贮藏期间花生仁的酸价、过氧化值、粗蛋白含量、油亚比、氨基酸含量和黄曲霉毒素B1含量的变化规律.结果表明:随着贮藏时间的延长,花生仁的酸价、过氧化值和粗蛋白含量都呈上升趋势;油亚比在贮藏后期升高;氨基酸总量在贮藏后期降低;黄曲霉毒素...     

Salt-induced conversion of B-DNA to Z-DNA inhibited by aflatoxin B1

The carcinogen aflatoxin B1 was reacted with a polymer of alternating deoxyguanine and deoxycytosine residues to determine the effect that adduct formation has on the conversion of this polymer from the right-handed B-DNA form found at low salt concentrations to the left-handed Z-DNA form found at high salt concentrations. Reaction with aflatoxin strongly inhibited the salt-induced conversion of this polymer from B-DNA to Z-DNA. This inhibition could be detected even at relatively low binding levels.