Occurrence of aflatoxin M1 in raw milk collected from traditional dairies in Morocco

A survey of the presence of aflatoxin M1 (AFM1) was carried out on eight traditional dairies belonging to four sectors of Fez city situated in the northern center of Morocco. Raw milk samples were collected between October 2009 and September 2010, and analyzed by LC-fluorescence detection after immunoaffinity purification. AFM1 was detected in 13 out of 48 samples (27%) at concentrations ranged between 10 and 100 ng/l. Within these positive samples, four (∼8% of the total) were above the European legislation limit of 50 ng/l. This study revealed a variation of contamination from one sector to another with a higher incidence in milk samples collected in autumn compared to those collected in other seasons suggesting a link between feeding practices, such as the use of silage and AFM1 contamination. This is the first report on AFM1 contamination in raw milk directly collected from Moroccan traditional dairies. The levels of contamination found justify more detailed and continuous monitoring to assess the public health implication and reduce consumers’ exposure to AFM1.     

Impact of aflatoxin B1 on hypothalamic neuropeptides regulating feeding behavior

The presence of mycotoxins in food is a major problem of public health as they produce immunosuppressive, hepatotoxic and neurotoxic effects. Mycotoxins also induce mutagenic and carcinogenic effects after long exposure. Among mycotoxins that contaminate food are aflatoxins (AF) such as AFB1, which is the most powerful natural carcinogen. The AF poisoning results in symptoms of depression, anorexia, diarrhea, jaundice or anemia that can lead to death, but very few studies have explored the impact of AF on neuroendocrine regulations. To better understand the neurotoxic effects of AF related to anorexia, we explored in rat the impact of AFB1 on the major hypothalamic neuropeptides regulating feeding behavior, either orexigenic (NPY, Orexin, AgRP, MCH) or anorexigenic (α-MSH, CART, TRH). We also studied the effect of AFB1 on a novel neuropeptide, the secretogranin II (SgII)-derived peptide EM66, which has recently been linked to the control of food intake. For this, adult male rats were orally treated twice a week for 5 weeks with a low dose (150 μg/kg) or a high dose (300 μg/kg) of AFB1 dissolved in corn oil. Repeated exposure to AFB1 resulted in reduced body weight gain, which was highly significant for the high dose of AF. Immunocytochemical and quantitative PCR experiments revealed a dose-related decrease in the expression of all the hypothalamic neuropeptides studied in response to AFB1. Such orexigenic and anorexigenic alterations may underlie appetite disorders as they are correlated to a dose-dependent decrease in body weight gain of treated rats as compared to controls. We also found a decrease in the number of EM66-containing neurons in the arcuate nucleus of AFB1-treated animals, which was associated with a lower expression of its precursor SgII. These findings show for the first time that repeated consumption of AFB1 disrupts the hypothalamic regulation of neuropeptides involved in feeding behavior, which may contribute to the lower body weight gain associated to AF exposure.     

肝细胞癌组织中Ras相关结构域家族1A基因甲基化与环境因素的关系

目的 探讨肝细胞癌(UCC)组织中Ras相关结构域家族1A( RASSF1A)基因甲基化与环境因素的关系.方法 采用甲基化特异性聚合酶链反应检测80例HCC组织中RASSF1A基因甲基化状态,免疫组织化学法检测HCC组织中黄曲霉素B1( AFB1 )-DNA加合物和多环芳烃(PAHs) -DNA加合物的水平,并结合临床资料进行统计分析.结果 RASSF1A基因甲基化率在肝癌组织中(60/80)显著高于癌旁组织(33/80,P＜0.01).HCC组织中RASSF1A基因甲基化率在AFB1-DNA加合物阳性组(43/51)高于AFB1-DNA加合物阴性组(17/29,P＜0.05);在PAHs-DNA加合物阳性组(39/45)高于PAH-DNA加合物阴性组(21/35,P＜ 0.05).结论 HCC组织中RASSF1A基因甲基化与环境致癌因素AFBI -DNA加合物、PAHs-DNA加合物水平密切相关.     

Hepatocellular carcinoma in developing countries: Prevention, diagnosis and treatment

Hepatocellular carcinoma(HCC)occurs commonly and with increasing frequency in developing countries,where it also carries an especially grave prognosis.The major risk factor for HCC in these regions is chronic hepatitis B virus(HBV)infection,although dietary exposure to aflatoxin B1 also plays an important etio-logical role.Prevention of HCC in developing regions is unlikely in the foreseeable future.Although an effec-tive vaccine against HBV is available,the percentage of babies born in developing countries that receive the full course of immunization remains low.Moreover,the usually long interval between infection with HBV and the development of HCC means that 30 to 50 years will elapse before the full effect of the vaccine will be realized.Practical measures to prevent aflatoxin B1 ex-posure are not in place.Serumα-fetoprotein levels are a useful pointer to the diagnosis of HCC in low-income countries,but definitive diagnosis is hampered both by the lack of the sophisticated imaging equipment now available in developed countries and by obstacles to obtaining histological proof.In the majority of patients in low-income regions,the tumor is inoperable by the time the patient presents.Hepatic resection is seldom possible in sub-Saharan Africa,although the tumor is successfully resected in a larger number of patients in China.Liver transplantation for HCC is rarely performed in either region.Sophisticated new radiotherapy tech-niques are not available in developing countries.The beneficial effects of the multikinase inhibitor,sorafenib,are encouraging,although financial considerations may restrict its use in low-income countries.     

Associations of serum aflatoxin B1-lysine adduct level with socio-demographic factors and aflatoxins intake from nuts and related nut products in Malaysia

Aflatoxins are one of the major risk factors in the multi-factorial etiology of human hepatocellular carcinoma. Therefore, the information on aflatoxins exposure is very important in the intervention planning in order to reduce the dietary intake of aflatoxins, especially among the children. This study investigated the relationship between aflatoxin B(1) (AFB(1)) lysine adduct levers in serum and socio-demographic factors and dietary intake of aflatoxins from nuts and nut products in Penang, Malaysia. A cross-sectional field study was conducted in five districts of Penang. A survey on socio-demographic characteristics was administered to 364 healthy adults from the three main ethnic groups (Malay, Chinese and Indian). A total of 170 blood samples were successfully collected and tested for the level of AFB(1)-lysine adduct. 97% of the samples contained AFB(1)-lysine adduct above the detection limit of 0.4 pg/mg albumin and ranged from 0.20 to 23.16 pg/mg albumin (mean±standard deviation=7.67±4.54 pg/mg albumin; median=7.12 pg/mg albumin). There was no significant association between AFB(1)-lysine adduct levels with gender, district, education level, household number and occupation when these socio-demographic characteristics were examined according to high or low levels of AFB(1)-lysine. However, participants in the age group of 31-50 years were 3.08 times more likely to have high AFB(1) levels compared to those aged between 18 and 30 years (P=0.026). Significant difference (P=0.000) was found among different ethnic groups. Chinese and Indian participants were 3.05 and 2.35 times more likely to have high AFB(1) levels than Malay. The result of AFB(1)-lysine adduct suggested that Penang adult population is likely to be exposed to AFB(1) but at a level of less than that needed to cause direct acute illness or death.     

HPLC柱后衍生同时测定黄曲霉毒素B1、B2、G1、G2的探讨

目的:建立黄曲霉毒素B1、B2、G1、G2的高效液相色谱柱后衍生检测方法。方法:样品通过高效液相色谱柱分离后,进入柱后衍生装置与碘溶液发生反应,最后进入荧光检测器进行检测。结果:该方法的检出限AFB1、AFG2为0.03μg/kg、AFB2为0.01μg/kg、AFG1为0.05μg/kg。结论:方法灵敏度高,准确度好,操作简单,实用性强,可用于黄曲霉毒素的检测。     

UPLC同时测定食品中黄曲霉毒素B1、B2、G1、G2

目的:建立免疫亲和柱超高效液相色谱法测定食品中黄曲霉毒素B1,B2,G1和G2含量的方法。方法:试样经过甲醇-水提取、稀释后经过免疫亲和柱层析净化,应用超高液相色谱法检测。结果:试验结果表明:空白样品分别按照0.2μg/kg、0.8μg/kg、2.0μg/kg添加黄曲霉毒素混合标准,回收率为75.0%～90.4%,精密度<5%,黄曲霉毒素B1,B2,G1和G2的检测灵敏度分别为0.2μg/kg,0.2μg/kg,0.4μg/kg,0.2μg/kg。结论:免疫亲和柱净化超高效液相色谱法测定食品中黄曲霉毒素B1,B2,G1,G2含量,是一种简单、快速和准确的方法。     

氨熏蒸降解稻谷中黄曲霉毒素B_1的安全性毒理学试验

在薄层层析法确定氨熏蒸可降解稻谷中所含黄曲霉毒素B_1的基础上,按我国现行的《食品安全性毒理学评价程序》、对经氨熏蒸、毒素降解后的稻谷(或加工成的大米)的卫生品质进行了评价。按规定我们完成了评价程序的第一阶段(急性毒性与七日喂养)、第二阶段(致畸、致突变的三个试验)及第三阶段(亚慢性毒性)试验。全部结果证实,氨熏蒸可有效地降解稻谷中黄曲霉毒素B_1,并且未发现其降解物对实验动物有毒性。认为此去毒法可在有关部门推广应用。     

Studies on the Production and Radioactive Labeling "2-C14"of Aflatoxin B1 by the Chlamydospore Growth Phase of Aspergillus parasiticus

Summary: A significant yield of aflatoxin B₁ was produced by the chlamydospore growth phase of Aspergillus parasiticus grown on a synthetic liquid medium. Morphology and structure of the fungus growth is fully described. The two stage addition of 2-C¹⁴-acetate to the medium proved to improve dramatically the efficiency of labeling the toxic metabolite.
Zusammenfassung: Eine signifikante Ausbeute an Aflatoxin B₁ konnte aus der Chlamydosporen-Wuchsphase von Aspergillus parasiticus auf einem synthetischen flüssigen Medium gewonnen werden. Die Morphologie des Pilzwachstums wird ausführlich beschrieben. Die Zugabe von Natriumacetat-2-C¹⁴ zu dem Medium in zwei Stufen ergab eine dramatische Steigerung der Ausbeute an markierten Toxin.     

Selection Pressure and Altered Hepatocellular Islands after a Single Injection of Aflatoxin B1

Development of glutathione S-transferase placental form (GST-P)-positive focal populations was investigated subsequent to single injections of the hepatocarcinogens aflatoxin B1 (AfB1), dimethylnitrosamine (DMN) and diethylnitrosamine (DEN). While DEN proved far more potent at inducing putative initiated hepatocytes, the AfB1 treatment was associated with a very rapid (3 weeks) development of lesions approaching nodular proportions. Autoradiographic investigation revealed selective incorporation of label into GST-P-positive hepatocytes and oval cells at the day 7 time point following AfB1 treatment. Administration of butylated hydroxyanisole (BHA) subsequent to carcinogen injection was associated with a decrease in the final yield of lesions and increased tritiated thymidine incorporation in perivenular zone 3 background hepatocytes. The results suggest that 'selection pressure', resulting in rapid growth and development of putative preneoplastic lesions, is inherent in a single injection of the mycotoxin and indicate that variations of the present short-term model may be useful for elucidating the mechanisms underlying AfB1-induced hepatocarcinogenesis.