应用ELISA直接竞争法测定乳粉中黄曲霉毒素M_1

建立了测定黄曲霉毒素M_1的ELISA直接竞争法,其方法灵敏度为0.08ng/g。用该法测定了我国市售的乳粉97份,样品阳性率为84.5%,超标率(>0.5ng/g)为39.2%;阳性样品含量范围为0.08～4.16ng/g,调查结果证明我国南方生产的乳粉污染黄曲霉毒素M_1较严重。     

亚硝酸钠与AFB1相互作用对遗传物质影响的实验研究

以正常人外周血淋巴细胞的ＳＣＥ率作为细胞遗传学指标，研究了Ｎａ＿２ＳｅＯ＿３与ＡＦＢ＿１相互作用对细胞遗传物质的影响。结果表明，一定浓度的Ｎａ＿２ＳｅＯ＿３（１０￣（－５）ｍｏｌ）对ＡＦＢ＿１所诱发的ＳＣＥ有明显的抑制作用，但当浓度达到１０￣（－２）ｍｏｌ时，细胞增殖受到抑制，到１０￣（－１）ｍｏｌ时细胞出现毒性现象。提示Ｎａ＿２ＳｅＯ＿３具有抑变和细胞毒性双相作用。所以在Ｎａ＿２ＳｅＯ＿３与ＡＦＢ＿１相互作用的ＳＣＥ实验中应避免Ｎａ＿２ＳｅＯ＿３的浓度过高而损伤培养的细胞。     

Selective aflatoxin B1-induced sister chromatid exchanges and cytotoxicity in differentiating B and T lymphocytes in vivo

The purpose of this study was to assess the genotoxic and cytotoxic effects of the fungal metabolite aflatoxin B1 (AfB1) on the developing immune system of the chick embryo, a model in vivo system. Of particular interest was the assessment of AfB1 -mediated selective toxicity toward developing B lymphocytes as compared to T lymphocytes. In vivo bromodeoxyuridine (BrdU) labelling of DNA was used to detect the induction of sister chromatid exchanges (SCE) in lymphocytes and to assess the progression of these cells through successive cell cycles. Cytotoxicity was also assessed by studying the entrance and maintenance of cells in mitosis (mitotic index). Graded doses of AfB1 (1.09–17.4 μ/g embryo) were applied to chick embryos of 18 days of incubation (Dl). Embryos also received two doses of BrdU at 3 mg/200 μ (3 hr apart) to provide continuous labelling of B and T lymphocyte replicating DNA. B and T lymphocytes were harvested 20 hr post-AfB1/BrdU exposure from the bursa and thymus, respectively, and were processed for cytogenetic analyses. AfB1 induced dose-related increases in SCE in B lymphocytes; this induction was 6- to 8-fold that of controls at the higher doses tested, AfB1 -mediated induction of SCE in T cells was just 2-fold that of controls at the highest dose tested. AfB1 reduced the progression of B cells and to a lesser extent T ceels through successive rounds of replication. Furthermore, AfB1 dramatically reduced the mitotic index of B cells but not of T cells. These data indicate both selective genotoxicity and cytotoxicity of AfB1 toward B cells in the late stage embryo. © 1993 Wiley-Liss, Inc.     

Production and characterization of monoclonal antibodies cross‐reactive with major aflatoxins

Monoclonal antibodies cross‐reactive with four major aflatoxins (AFs) were produced by fusion of P3/NS‐1/1‐AG4–1 murine myeloma cells with spleen cells isolated from a BALB/c mouse that had been immunized with aflatoxin B3‐hemisuccinate conjugated to bovine serum albumin. Six stable clones were obtained. Isotyping by enzyme‐linked immunosorbent assay (ELISA) revealed that the antibodies produced by all but two of the clones were of the IgG₁ type. Of the remaining clones, one produced IgG₂₁, and the other IgA. Competitive radioimmunoassay using tritiated AFB₁ as the marker ligand revealed that two clones produced antibody that cross‐reacted well with both AFB₁ and AFG₁; one clone produced an antibody that had good specificity toward AFB₁. The relative cross‐reactivities (RCR) of antibody produced by clone 575B8F12 for AFB₁, AFB₂, AFG₁, and AFG₂ were 100, 5, 153, and 6, respectively. The RCR of antibody produced by clone 575G4H7 for the above AFs were 100, 40, 153, and 40, respectively. The RCR of antibody produced by clone 585D4D6 for the above AFs were 100, 40, 152, and 23, respectively. Antibodies produced by the other three clones were inadequate for immunoassay because their affinities for the AFs were 100 times less than the three clones described above.     

Effects of intermittent exposure to aflatoxin B1 on DNA and RNA adduct formation in rat liver: dose-response and temporal patterns.

We studied the effects of intermittent exposure to aflatoxin B1 (AFB1) on hepatic DNA and RNA adduct formation. Fisher-344 male rats were fed 0.01, 0.04, 0.4, or 1.6 ppm of AFB1 intermittently for 8, 12, 16, and 20 weeks, alternating with 4 weeks of dosing and 4 weeks of rest. Other groups of rats were fed 1.6 ppm of AFB1 continuously for 4, 8, 12, and 16 weeks. Control rats received AFB1-free NIH-31 meal diet. AFB1-DNA and -RNA adducts were measured by HPLC with fluorescence detection. The data are presented as total DNA or RNA adducts. The DNA and RNA adduct levels increased or decreased depending on the cycles of dosing and rest. Rats removed from treatment 1 month after 1 or 2 dosing cycles (8 and 16 weeks of intermittent exposure) showed approximately a twofold decrease in DNA adduct levels and a two- to elevenfold decrease in RNA adduct levels compared with rats euthanized immediately after the last dosing cycle (12 and 20 weeks of intermittent exposure). Our data indicate that DNA and RNA adducts increased linearly, from 0.01 ppm to 1.6 ppm of AFB1 after 12 and 20 weeks of intermittent treatment. A linear dose response was also apparent for DNA but not for RNA adducts after 8 and 16 weeks of treatment. As biomarkers of exposure, AFB1-RNA adducts were three to nine times more sensitive than AFB1-DNA adducts but showed greater variability. These results suggest that binding of AFB1 to hepatic DNA is a linear function of the dose, regardless of the way this is administered. The dose-response relationship for RNA adducts depends on the length of the no-dosing cycles and on the turnover rate of RNA.     

金蒲抑瘤片在实验诱发大鼠肝癌过程中的作用

目的探讨金蒲抑瘤片对黄曲霉毒素B1(aflatoxin B1,AFB1)致肝癌作用的影响。方法实验动物随机分为高剂量、低剂量和对照组。用AFB1处理各组动物,高、低剂量组大鼠在接受AFB1期间分别喂含量为9.3和2.3g/kg的金蒲抑瘤片混合饲料,对照组喂基础饲料。8周后处死动物,观察各组动物肝组织内γ-谷氨酰转肽酶阳性肝细胞增生(γ-glu-tamyltranspeptidase-positive hyperplastic livercell,γ-GT)灶的数量和大小。结果高、低剂量金蒲抑瘤片均能减少AFB1诱发的γ-GT灶的数量和大小高、低剂量组的数量分别为0.90和3.72个/cm2,均低于对照组6.10个/cm2,抑制率分别为85%和39%,高剂量组与对照组相比差异有统计学意义,t=2.597,P=0.028。高、低剂量组的大小分别为0.24和1.94mm2/个,均低于对照组2.36mm2/个,抑制率分别为90%和17%,但差异无统计学意义,P>0.05。结论金蒲抑瘤片有减少AFB1诱发大鼠肝γ-GT灶的数量和大小的作用,而高剂量金蒲抑瘤片的减少趋势更强。     

Influences of V5-epitope tag on the metabolic activation of AFB1 by human cytochrome P450 2A13

INTRODUCTION A flatoxin B1 (AFB1) , which is produced by Aspergillus flavus and Aspergillus parasitus, is a potent carcinogen in human and animals. Al- though AFB1 is best known as a liver carcinogen, it also induces lung tumors in animals and epidemio- logical studies show a positive association between human lung cancer occurrence and inhalation expo- sure to AFB1-containminated grain dust. As most of environmental carcinogens, metabolic activation cat- alyzed by cytochrome P450 (C…     

Occurrence and analysis of aflatoxin M1 in milk produced by Indian dairy species

A total of 600 samples of milk from different species [buffalo (150), cow (150), goat (150), and sheep (150)] were analyzed for aflatoxin M1 (AFM₁) contamination using high-performance liquid chromatography and enzyme-linked immunosorbent assay (ELISA) methods. AFM₁ contamination was found in buffalo (38.6%), cow (45.3%), goat (33.3%), and sheep (36.6%) milk. The mean value of AFM₁ was 0.026?µg?L^?1 in buffalo, 0.018?µg?L^?1 in cow, 0.014?µg?L^?1 in goat, and 0.017?µg?L^?1 in sheep milk. In all types of milks, the level of AFM₁ concentration was higher in milk obtained from urban and semi-urban areas, whereas it was found minimal in milk from rural areas. The results of the analysis of AFM₁ level by the ELISA analysis (ng?L^?1) was observed in 46.5% of all samples. The amount of AFM₁ in 16% buffalo, 44% cow, 10% goat, and 12% sheep milk samples was above the maximum tolerance limit accepted by the European Union.     

HBV转基因小鼠暴露ATB-1后肝脏ATB-1-DNA加成物水平的测定

目的探讨ＨＢＶ与ＡＴＢ１协同致肝癌的机理．方法用ＲＩＡ法测定ＨＢＶ转基因小鼠与正常小鼠暴露ＡＴＢ１后０，０５，１，２，４，８，２４ｈ７个不同时相肝脏ＡＴＢ１ＤＮＡ加成物的含量变化．结果暴露ＡＴＢ１后，ＨＢＶ转基因小鼠肝脏ＡＴＢ１ＤＮＡ加成物含量在各时相均高于正常小鼠，尤以１ｈ高峰时相值（５５９２ｐｍｏｌ／ｍｇ±４１５ｐｍｏｌ／ｍｇ比４１３６ｐｍｏｌ／ｍｇ±２８２ｐｍｏｌ／ｍｇＤＮＡ，Ｐ＜００１）及２４ｈ时相值（２４８７±２０３比９８９±８５，Ｐ＜００１）最显著．２４ｈ后，转基因小鼠肝脏ＡＴＢ１ＤＮＡ加成物仍维持高水平，但正常小鼠已基本恢复至暴露前水平．结论ＨＢＶ转基因小鼠暴露ＡＴＢ１后肝脏ＡＴＢ１ＤＮＡ加成物含量增加可能为ＨＢＶ与ＡＴＢ１协同致肝癌的直接原因．     

A survey of Aflatoxin M1 in some commercial milk samples and infant formula milk samples in Goa,India

A survey of aflatoxin M1 (AFM1) contamination in packaged milk and infant formula milk samples in the Goan market, India, was conducted using high performance liquid chromatography, association of analytical communities approved commercial kit and a sensitive chemiluminescent sandwich enzyme-linked immunosorbent assay (ELISA). A total of 72 samples of infant formula milk food (18) and packaged milk samples (54) was analysed. One hundred per cent of the analysed samples exceeded the European Communities recommended limits (50 ng/L) and 75% of the samples exceeded Codex Alimentarius, Food Safety and Standards Authority of India (FSSAI) and US Food and Drug Administration recommended limits (500 ng/L). The range of contamination of AFM1 was found lower in infant milk formula (501–713 ng/L) than liquid milk (511–809 ng/L). The methods were also compared for their performance, and ELISA was found to be most suitable for analysis of low-level AFM1 contamination in milk.