肉鸡养殖场中环丙沙星和头孢噻肟双重耐药沙门菌耐药机制的研究

目的阐明养殖场肉鸡及其环境中环丙沙星和头孢噻肟耐药沙门菌的分布和耐药机制特点。方法对河南省4个不同地区肉鸡养殖场及环境中分离的沙门菌进行环丙沙星和头孢噻肟双重耐药菌株的筛选和鉴定,并对分离株进行药敏试验、喹诺酮类和超广谱β内酰胺酶耐药机制研究。结果从52株养殖场肉鸡肛拭子及环境中筛选出5株耐环丙沙星和头孢噻肟的沙门菌,均为印第安纳沙门菌,有AMP-CAZ-CHL-CIP-CTX-GEN(n=1)和AMP-CAZ-CHL-CIP-CTX-GEN-SXT-TET(n=4)两种耐药谱。喹诺酮耐药机制研究显示,5株菌的拓扑异构酶编码基因gyr A和par C均有点突变出现,均携带了质粒介导的喹诺酮耐药基因,包括oqx AB、aac(6')-Ib-cr基因,而qnr A、qnr B、qnr S、qnr C、qnr D和qep A基因则未检出。超广谱β-内酰胺酶耐药机制显示,5株菌均为blaCTX-M-65型。结论耐环丙沙星和头孢噻肟的菌株存在于肉鸡养殖环节及其环境中,并具有复杂的喹诺酮耐药机制和可传播的超广谱β内酰胺酶耐药机制。为阐明农场-餐桌-感染者传递链条中耐药关联性,为社区感染防控、临床抗生素用药提供科学依据,我国应该加强肉鸡等养殖业沙门菌多重耐药菌株的监测。     

GII.3型诺如病毒重组衣壳蛋白的表达和纯化鉴定

目的通过杆状病毒表达系统,获取高纯度GⅡ.3型诺如病毒重组衣壳蛋白,为制备抗GⅡ.3型诺如病毒单克隆和多克隆抗体提供免疫原。方法将GⅡ.3型诺如病毒衣壳蛋白基因片段修饰后插入p HTA表达载体中,经测序鉴定,将鉴定正确的重组质粒转化到MAX Efficiency~DH10Bac~(TM)感受态细胞中,获取表达杆粒并转染SF9细胞,表达GⅡ.3型诺如病毒重组衣壳蛋白。重组蛋白用Ni-NTA His蛋白亲和柱纯化,十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)和蛋白免疫印迹(Western blot)方法鉴定。结果 SDS-PAGE和Western blot结果表达了分子量约为60 k Da的重组蛋白,动物试验表明重组蛋白具有较好的免疫原性,为制备抗GⅡ.3型诺如病毒单克隆抗体和多克隆抗体、建立相应的免疫学检测方法奠定了基础。结论构建了GⅡ.3型诺如病毒衣壳蛋白表达载体,并获得GⅡ.3型诺如病毒重组衣壳蛋白。     

Preparation and application of immunoaffinity column coupled with dcELISA detection for aflatoxins in eight grain foods

This paper described a reliable and simple analytical method for the determination of aflatoxins (AFB₁, AFB₂, AFG₁, AFG₂) in cereals, peanuts, vegetable oils and fermented foods like beer, soybean sauce and soybean paste based on immunoaffinity column (IAC) cleanup coupled with direct competitive enzyme-linked immunosorbent assay (dcELISA) detection and confirmed by ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Under the optimized conditions, the home-made IAC capacity was 293, 60, 220 and 45 ng/mL gel for AFB₁, AFB₂, AFG₁ and AFG₂, respectively. Eight grain foods were pretreated with IAC, and then the extracts were detected by the dcELISA. The results showed that the recoveries of IAC-dcELISA ranged from 71.5% to 119.8% (relative standard deviations ≤ 16.67%) that were higher than dcELISA without IAC cleanup procedure by at least 30% on average, indicating that the matrix interference of different samples could be alleviated via the pretreatment of IAC, especially for fermented foods. The developed method was also confirmed by UHPLC-MS/MS with electrospray interface in positive mode using multiple reaction monitoring. In conclusion, this assay could be used as an effective analytical method for the determination of aflatoxins in complex grain foods.     

Risk factors associated with the presence of aflatoxin M1 in raw bulk milk from Argentina

The objectives of this study were to assess aflatoxin M₁ (AFM1) contamination in bulk tank milk, and to further identify the risk factors associated with the presence of AFM1 in raw milk in Argentina. The presence of AFM1 was investigated in 160 bulk tank milk samples collected from farms located in the most important milk production region in Argentina during one year (four seasons). Samples were analysed using immunoaffinity column (IAC) cleanup and UHPLC-MS/MS method for determining AFM1 at low levels of concentrations (LOQ = 0.003 μg L⁻¹). A survey about the potential factors associated with the presence of AFM1 in milk was performed directly in the field through a questionnaire applied to the farmers. Chi-square and logistic regression were performed with presence of AFM1 in milk as dependent variable, and potential risk factors as independent variables. Incidence of AFM1 in raw milk was 38.8% and, in all samples, AFM1 levels were lower than the Southern Common Market (MERCOSUR) Regulation (maximum level accepted = 0.5 μg L⁻¹). Commercial feed consumption (OR = 4.630, P = 0.001), soybean expeller consumption (>0.95 kgDM/cow) (OR = 3.542, P = 0.019), and cotton seed consumption (>1.5 kgDM/cow) (OR = 2.949, P = 0.089) were associated with the incidence of AFM1 in raw milk. Despite the incidence and the level of AFM1 in milk produced and commercialized in Argentina is not a serious problem for public health. The farm breeding intensification and the supplementation with commercial feed, soybean expeller, and cotton seed seems to be the risk factors that impacts on the AFM1 milk contamination. Therefore, Argentina should improve its monitoring program on mycotoxins in animal feed and milk and improve the management practices in farms.     

食品化学物风险评估中一些重要参数的选择和使用

食品安全风险评估是我国制定、修订食品安全标准、实施食品安全监督管理的科学依据,评估结果的准确性和可靠性将直接影响食品安全监管决策的科学性。评估方法、统计学参数、模型构建和健康指导值是影响评估结果的几个重要因素,而对这些因素的选择和使用往往存在模糊认识和误区。本文主要针对食品中化学物的风险评估,对上述几个参数的选择和使用进行探讨。     

我国膳食无机砷致癌症及心血管疾病的疾病模型构建

目的 构建我国膳食无机砷致癌症及心血管疾病的疾病模型。方法 首先确立膳食无机砷导致的不同健康危害终点。根据我国人群相关疾病的流行病学数据,分别采用风险评估法和反事实分析法计算膳食无机砷暴露致癌症及心血管疾病的归因发病率、死亡率,结合疾病的伤残权重及病程等特点,构建膳食无机砷暴露致癌症及心血管疾病的疾病模型。结果 人群终身持续经膳食暴露于1.41 μg/（kg?d）无机砷时,引起皮肤癌、膀胱癌和肺癌的发病率分别为0.135%、0.010%以及0.034%,死亡率分别为0.015%、0.004%以及0.138%。人群终身持续经膳食暴露于1 μg/（kg?d）无机砷时,引起的心血管疾病发病率及死亡率分别为0.082%、0.025%。结论 疾病模型可用于计算食品污染物导致的疾病负担,对食品污染物的健康危害进行量化。     

Dissipation behavior of bifenthrin residues in tea and its brew

Dissipation behavior of bifenthrin, a widely used non-systemic acaricide/insecticide, applied under field condition on tea crop in wet (mid-June–October) and dry season (November–mid-June) was studied in green shoots, made tea and its brew. A simple, rapid analytical procedure for the quantification of bifenthrin in these matrices was developed using gas chromatography with electron capture detector. Degradation rate in both wet and dry seasons followed first order kinetics with half lives in green leave in the range 0.52–0.77 and 1.20–1.32 days and in made tea were 0.55–0.60 and 1.03–1.06 days for wet and dry seasons respectively. Processing of green shoots caused considerable loss (⩾42%) of residue and its only partial transfer (1.5–14%) in brew was observed. Based on the observation reported, a waiting period of at least three days before plucking the tea shoots after pesticide application at recommended dose (40 g a.i./ha) may be suggested and considered quite safe from point of health hazards due to toxic effect of residues in brew.     

“双碳”目标下中国居民食物消费结构升级及碳排放分析研究

目的 分析2014—2020年间中国居民食物消费结构及碳排放量,为倡导居民可持续消费模式,实现“双碳”目标提供科学支持。方法 以食物消费为对象,并进一步延伸至食物碳排放。综合运用食物碳排放系数和生命周期法,从直接和间接两个方面对我国居民食物消费引起的碳排放量进行全面的测算,探究食物碳排放演变趋势。结果 中国居民食物结构随动物性食物消费量逐年递增,温室气体排放量也有较大幅度增长。分别假设2030、2040、2050年逐渐调整其食物消费结构至膳食指南场景,温室气体排放总量分别在2030、2040、2049年达到峰值,温室气体排放量较现状水平均有一定幅度增加。结论 中国食物消费结构调整带来的碳减排压力较大,并结合上述结果结论,给出合理的政策启示。