Further Survey of Aflatoxin M1 in Milk Powders by ELISA

A survey of AFM₁ residues in 58 commercial milk powder samples was carried out using an enzyme‐linked immunosorbent assay (ELISA) based on a monoclonal antibody against aflatoxin M₁ (AFM₁). The samples were collected from the USA (10), China (28), Italy (14), New Zealand (3) and Poland (3). The ELISA was performed without the need for clean‐up procedures. The data revealed that 4 (US), 21 (Chinese) and 1 (Polish) samples were positive for AFM₁, with an average of 95.5, 102.8 and 85.0 pg g^‐1 of the AFM₁respectively.     

Treatment with aflatoxin B1 for immortalization of human fibroblasts from Li-Fraumeni patients

Immortalization of normal human fibroblasts is a very rare event. Multiple genes such as p53 and cellular senescence genes are possibly involved in immortalization of human fibroblasts, suggesting that multiple treatments with carcinogens are required for the immortalization. We describe here the procedure for immortalization of human fibroblasts (MDAH 087) from Li-Fraumeni cancer syndrome with a germ-line p53 mutation. The cells were subjected to multiple treatments with aflatoxin B₁ (AFB₁) in the presence of exogenous metabolic activation with rat liver post-mitochondrial supernatant (PMS), and 3 of 9 MDAH 087 cell cultures treated 1–3 times with 0.1–1 µg/ml AFB₁ became immortal, defined as continuous growth for over 300 population doublings after the first treatment. However, cultures of human fibroblasts from a normal embryo treated under the same conditions failed to escape senescence. The results indicate that the model of human fibroblasts with a mutated p53 allele exposed to AFB₁ is potentially useful for studying mechanisms of chemically induced immortalization.     

泰兴地区肝癌高发因素研究

探讨了泰兴地区人群肝癌的高发因素。采用ELISA法分别检测人群体内HBV感染水平和AFT—SHA含量及生活饮用水水体内MC含量。结果发现该地区人群HBsAg携带率为29．5％,HBV感染阳性率68.1％,肝癌高发乡镇人群HBsAg携带率和HBV感染阳性率分别高达45．8％和94．7％;人群体内AFT—HSA检出率达100％,平均含量为16．39pg／ng;高发乡镇人群体内AFT—HSA平均含量31．99pgM;生活饮用水水体内MC阳性检出率13．2％,河水、沟塘水和浅井水内MC的平均含量分别为36ng／L,29ng／L和25ng／L．结论：人群中的HBV高感染;黄曲霉素强暴露;生活饮用水水体内MC的普遍污染是泰兴地区肝癌高发的三个重要因素．     

一种新的去除食油中黄曲霉毒素的去毒剂

本文报道一种新的去除食油中AFBl的去毒剂——AFR的除毒效力。一公斤被AFB_1污染的食油加入2克AFR,搅拌5分钟,自然静置约24小时,其上清部分符合国家食油卫生标准,去毒率可达95—100％,急性毒性,大鼠蓄积毒性、微核及Ames试验结果显示:AFR属于一种无毒的去毒剂,具有使用方便、高效及低耗油等特点。现已通过省级卫生、粮油部门鉴定,并已获“卫生合格证”,批准生产,推广于某些省区,其效果良好。     

Survivin在AFB1高暴露地区肝细胞癌中的表达及其临床意义

目的:探讨Survivin在黄曲霉毒素B1(AFB1)高暴露地区肝细胞癌(HCC)发生发展中的作用.方法:用逆转录聚合酶链反应检测来自广西南部黄曲霉毒素B1高暴露地区患者手术切除肝癌及其癌旁组织中Survivin mRNA的表达情况.结果:Survivin mRNA在55例HCC及其癌旁组织中的检出率分别为85.5%(47/55)及40.0%(22/55),两者差异有显著性(P＜0.01).Survivin mRNA在HCC组织中的表达率与临床分期(P＜0.05)和肿瘤直径(P＜0.05)相关.结论:Survivin在HCC发生发展过程中起重要作用,HCC组织中的Survivin mRNA可作为AFB1高暴露地区HCC预后不良的参考指标.     

黄曲霉毒素M1的危害、污染现状及检测方法进展

本文针对黄曲霉毒素M1 的理化特性、危害、产生及防治进行了总结 ,详细介绍了黄曲霉毒素M1 的四类检测方法 ,并进行了比较 ,同时展望了检测方法的发展方向     

高效液相色谱法同时测定食品中四种黄曲霉毒素的方法探讨

目的：建立一种快速、灵敏、简便的高效液相色谱（HPLC）同时测定食品中黄曲霉毒素（AFT）B1、B2、G1和G2的方法。方法：样品经振荡提取，多功能净化柱净化，三氟乙酸衍生后，选用ZORBAX XDB-C18分离柱，用乙腈-水（23＋77）作流动相，于20℃以下等度洗脱，经荧光检测器测定后，以保留时间定性，用峰面积或峰高定量。结果：20分钟内可完成AFr4种组分的分离。检出限分别是，B1为0．042ng，B2、G1和G2为0．08ng。回收率为83．4％～103．1％，r〉0．9995。结论：经振荡提取、多功能净化柱净化后，用荧光检测器同时测定食品中黄曲霉毒素（AFT）B1、B2、G1和G2的高效液相色谱方法快速、灵敏、简便。     

Immunohistochemical study of proliferating cell nuclear antigen (PCNA) in duckling liver fed with aflatoxin B1 and esterified glucomannan

The effect of esterified glucomannan on aflatoxin B₁ toxicity in ducklings was studied by immunohistochemical staining of proliferating cell nuclear antigen (PCNA) in hepatic cells on formalin-fixed paraffin-embedded liver samples. Cherry Valley ducklings were divided into five groups, 20 birds in each. One of the groups was fed with conventional feed, and the other groups were fed with diet containing 100 ppb aflatoxin B₁, that containing 0.05% esterified glucomannan, or that containing 100 ppb aflatoxin B₁ supplemented with 0.05 or 0.1% esterified glucomannan, from five days of age for one month, and subsequently all the groups were fed with conventional feed for 20 days. Four birds of each group were sacrificed on the 30th, 35th, 40th, 45th and 50th day of feeding, and PCNA on the liver tissue sections was quantitatively analyzed by immunohistochemical staining. The percentage of PCNA-positive hepatocytes was significantly higher in the group given diet containing aflatoxin B₁ than in the other groups, which were not significantly different from each other. The results demonstrate that supplementation of feed with esterified glucomannan is effective in reduction of aflatoxin B₁-induced hepatic injury in ducklings.     

Epidemiology of Aflatoxin Exposure and Human Liver Cancer

Aflatoxins, especially aflatoxin B₁, are potent hepatocarcinogens that induce liver tumors in many species of animals, including rodents, nonhuman primates, and fish. Human primary liver cancer, mainly hepatocellular carcinoma, is one of the most common diseases in Asia, Africa, and in populations of Asian‐ and Hispanic‐Americans. Over the past 40 years there have been extensive efforts to investigate the association between aflatoxin exposure and human liver cancer. These studies have been hindered in earlier years by the lack of adequate biomarkers and dosimetry data on aflatoxin intake, excretion, and metabolism in people, as well as by the general poor quality of world‐wide cancer morbidity and mortality statistics. Many studies carried out in the past decade have incorporated the molecular analysis of the cancer gene targets and aflatoxin‐specific biomarkers, which have spurred efforts to assess aflatoxin exposure and human liver cancer risks. These molecular epidemiological studies eventually led to the reclassification of naturally occurring aflatoxins to a Group I human carcinogen by the International Agency for Research on Cancer in 1993, and the evaluation was reaffirmed in 2002. Current research in the field mainly focuses on studying interactions between aflatoxins and viral infections (hepatitis B/C viruses) and preventions of both aflatoxin exposure and viral infections.     

Ability of Lactobacillus rhamnosus GAF01 to remove AFM1 in vitro and to counteract AFM1 immunotoxicity in vivo

Aflatoxin M₁ (AFM₁) has been detected in many parts of the world both in raw milk and many dairy products, causing great economic losses and human disease. Unfortunately, there are few studies dealing with AFM₁ immunotoxicity/interactions with lactic acid bacteria for potential application as a natural preventive agent. The aim of this study was to isolate (from dairy products) food-grade probiotic bacteria able to degrade/bind AFM₁ in vitro and evaluate whether the same organism(s) could impart a protective role against AFM₁-induced immunotoxicity in exposed Balb/c mice. Bacteria (Lactobacillus plantarum MON03 and L. rhamnosus GAF01) were isolated from Tunisian artisanal butter and then tested for abilities to eliminate AFM₁ from phosphate-buffered saline (PBS) and reconstituted milk (containing 0.05, 0.10, and 0.20 µg AFM₁/ml) after 0, 6, and 24?h at 37°C. Results showed that the selected bacteria could ‘remove’ AFM₁ both in PBS and skimmed milk. The binding abilities of AFM₁ by L. plantarum MON03 and L. rhamnosus GAF01 strains (at 10⁸ CFU/ml) in PBS and reconstituted milk ranged, respectively, from 16.1–78.6% and 15.3–95.1%; overall, L. rhamnosus showed a better potential for removal than L. plantarum. ‘Removal’ appeared to be by simple binding; the bacteria/AFM₁ complex was stable and only a very small proportion of mycotoxin was released back into the solution. L. rhamnosus GAF01 had the highest binding capacity and was selected for use in the in vivo study. Those results indicated that use of the organism prevented AFM₁-induced effects on total white and red blood cells, and lymphocyte subtypes, after 15 days of host treatment. These studies clearly indicated that L. rhamnosus GAF01 was able to bind AFM₁ in vitro and—by mechanisms that might also be related to a binding effect—counteract AFM₁-induced immunotoxicity. Moreover, by itself, this bacterium was not toxic and could potentially be used as an additive in dairy products and in biotechnology for mycotoxin detoxification.