Screen‐printed biosensor for allergens

Allergen levels in indoor environments, leading to many diseases, eg asthma, rhinitis and conjunctivitis, affect a large and increasing fraction of the population. A quite effective and inexpensive method of a rough but very rapid overall assessment of total allergen level in the environment has been developed. The method involved estimation of protein in allergen extracts by screen‐printed electrodes using two different techniques. The biosensor comprised a rhodinised carbon working electrode, a silver/silver chloride reference electrode and a carbon counter electrode. In the first method the enzyme protease reacted with allergen protein to release amino acid, which produced hydrogen peroxide in the presence of amino acid oxidase. This was detected amperometrically. The second method used potassium bromide as electrolyte and the electrode was subjected to dual potential. Bromine, released due to electrolysis at higher potential, was consumed by the allergen protein at lower potential. In the first method, a unique technique was used to microencapsulate the enzyme protease and immobilise it on the surface of the electrode by in‐situ polymerisation to avoid contact with the amino acid oxidase. A total of seven allergens were tested and the results gave a good correlation with the standard protein measurement method. Environmental specimens from indoors, schools and workplaces can be evaluated for the aeroallergens produced by dust mites, animal hairs, cockroach debris, pollens, etc as a means of determining the exposure risk. Copyright © 2005 Society of Chemical Industry     

牛乳过敏原及加工技术对其致敏性的影响

对婴幼儿来说,牛乳营养丰富,是母乳最好的替代品,但牛乳中的蛋白质可能会引起过敏。牛乳中的主要过敏原是酪蛋白、β-乳球蛋白和α-乳白蛋白。本文从牛乳过敏原的结构和抗原表位、热处理、发酵和酶处理等不同的加工技术对牛乳蛋白致敏性的影响和过敏原标记检测方法三个方面进行了综述,为开发低致敏牛乳制品提供借鉴。      

大米蛋白的BN大鼠致敏动物模型建立

以大米蛋白为过敏原,腹腔注射致敏雌性棕色挪威大鼠(BN大鼠),建立大米蛋白过敏BN大鼠动物模型。观察BN大鼠全身主动过敏反应及体重、体温、免疫脏器指数变化,检测其血清特异性Ig G、总Ig E和特异性Ig E水平,并测定血浆组胺释放水平及各组大鼠的血象变化。结果显示,实验第42 d大米蛋白激发实验后,实验组大鼠全部呈过敏反应阳性,且体温降低,脾脏指数显著增大(p<0.01),体内白细胞和嗜酸粒细胞数目升高(p<0.05);实验组血清特异性Ig G显著升高(p<0.01),总Ig E以及血浆组胺释放量均高于对照组(p<0.05),实验第14 d和42 d血清特异性Ig E高于对照组,第28 d无明显变化(p<0.05)。本实验结果证明BN大鼠是评价大米蛋白致敏性较为理想的动物模型。      

Food allergy,a summary of eight cases in the UK criminal and civil courts: effective last resort for vulnerable consumers?

Food allergy has a forensic context. The authors describe eight cases in the UK courts involving fatalities, personal injury or criminal non‐compliance with food law from mainly ‘grey’ literature sources. The potentially severe consequences for people with food allergy of contraventions of labelling law have led to enforcement action up to criminal prosecution for what might otherwise be regarded as ‘trivial’ non‐compliance. The authors suggest there should be central collation of such cases. Non‐compliances should be followed up in a more rapid and robust manner. Evidence of fraud in the catering supply chain supports recent calls for zero tolerance of food fraud. Businesses must guard against gaps in allergen management, for which there are readily available sources of training and guidance, but also against fraudulent substitution in the supply chain, about which training and guidance should be developed. New allergen labelling legislation and case law appear to place responsibility on food businesses even for the forensically problematic area of allergen cross‐contamination. The courts can be an effective last resort for vulnerable consumers; however, there is evidence of knowledge and skill gaps in both the investigation and prosecution of potentially serious incidents of food allergen mismanagement and mislabelling. Thorough investigation of food allergy deaths is required with a tenacious and skilled approach, including early realisation that samples of the food and/or stomach contents from a post mortem examination should be retained and analysed. The supply chain must be rigorously examined to find out where adulteration or contamination with the fatal allergen occurred. © 2014 Society of Chemical Industry     

虾类原肌球蛋白提取和活性的保持

蛋白质分离纯化的主要目的是研究其结构和理化性质,因此在分离纯化过程中应尽量保持原有的结构和性质。本文主要综述了甲壳类动物的主要过敏原-原肌球蛋白(Tropomyosin,TM)的结构,以及影响其结构稳定性的因素。同时讨论了分离纯化的方法及条件对原肌球蛋白结构和过敏原活性的影响,为提取高纯度且保留原有结构和活性的原肌球蛋白提供参考。     

酶联免疫吸附法(ELISA)检测婴幼儿配方食品中谷蛋白

介绍了利用ELISA法的醇溶谷蛋白试剂盒测定婴幼儿配方食品中的谷蛋白含量。样品经处理后,用提取液提取样品中谷蛋白,提取液经离心,稀释后,用酶联免疫吸附法直接测定。检测的线性范围是5～80μg/kg,相关系数是0.9988,回收率在115.6%～120.6%之间,证明可以用酶联免疫法测定婴幼儿配方食品中的谷蛋白含量。     

表面等离子体共振生物芯片无标记实时检测虾血蓝蛋白

利用自行研制的便携式表面等离子体共振生物芯片检测系统,在生物芯片表面分别固定虾血蓝蛋白、虾血蓝蛋白的单克隆抗体、虾血蓝蛋白的单克隆抗体腹水作为生物探针,利用免疫反应的特异性,研究虾血蓝蛋白与其单克隆抗体的相互作用,分析动力学反应过程,建立标准曲线。用同一个生物芯片检测了8个抗体样品、7个未纯化的抗体腹水,为现场检测大量食品中过敏原、检测临床血清中过敏原特异性抗体进行基础研究。表面等离子体共振生物芯片检测过敏原,仪器便携、操作简便、无需标记、无污染、成本低,可进行现场大量样品的实时连续检测和快速筛选,适用于超市、集市、工厂等需要实时快速检测和质量监控的场所,也可以应用于临床上患者血清样品的过敏原抗体检测。     

酶解对乳清蛋白抗原性影响的研究

研究了酶解对乳清蛋白抗原性的影响。选择了7种常见蛋白酶在同一水解模式下水解乳清蛋白，用竞争ELISA法测定水解物的残留抗原性，从而间接测定其过敏性变化。结果表明，酶解能有效降低乳蛋白抗原性，但水解物仍能与特异抗体反应，保留一部分抗原性。不同酶对乳清蛋白过敏原的影响不同，酶的特异性对乳清蛋白水解物的抗原性有较大的影响，碱性蛋白酶降低乳蛋白抗原性的效果最佳，对抗β-乳球蛋白（β-LG）和抗α-乳白蛋白（α-LA）抗体的抗原性分别降低了50．02％和99．72％。     

牛乳中主要过敏原组分的分离纯化及鉴定

目的:分离纯化并鉴定牛乳中引起过敏反应的主要致敏组分。方法:采用聚丙烯酰胺凝胶电泳(SDS- PAGE)分析了脱脂乳和乳清的蛋白组分,用饱和硫酸铵分段盐析-DEAE离子交换柱层析纯化过敏原蛋白,脱脂乳和乳清蛋白皮下注射Balb/c小鼠获得高效价特异性IgE抗血清用于免疫印迹分析。结果:免疫印迹分析显示β-乳球蛋白(β-Lg)是引起牛乳过敏的主要过敏原,建立了牛乳过敏小鼠模型。结论:明确了牛乳过敏的主要过敏组分,对牛乳过敏症的诊断治疗以及无过敏原牛乳的制备提供了实验依据。     

Sandwich enzyme-linked immunosorbent assay (ELISA) for detection of cashew nut in foods

The presence of undeclared cashew can pose a health risk to cashew-allergic consumers. The food industry has the responsibility to declare the presence of cashews on packaged foods even when trace residues are or might be present. The objective of this study was to develop a rapid, sensitive, and specific enzyme-linked immunosorbent assay (ELISA) for the detection of cashew residues. Raw and roasted cashews were defatted and used separately to immunize sheep, goats, and rabbits. The cashew ELISA was developed using sheep and rabbit polyclonal anti-roasted cashew sera as capture and detector reagents, respectively, with visualization through an alkaline phosphatase-mediated substrate reaction. The cashew ELISA was shown to have a limit of quantification of 1 ppm (1 μg cashew/g). The ELISA was highly specific except that substantial cross-reactivity was noted with pistachio and a lesser degree of cross-reactivity was noted with hazelnut. The performance of the ELISA was assessed by manufacturing cookies, ice cream, and milk chocolate with added known amounts (0 to 1000 ppm) of cashew. The mean percent recoveries for ice cream, cookies, and milk chocolate were 118%± 2.9%, 84.3%± 4.0%, and 104%± 3.0%, respectively. In a limited retail survey, 4/5 retail samples with cashew declared on ingredient labels tested positive for cashew compared to 5/36 samples of foods with precautionary labels indicating the possible presence of one or more tree nuts and 0/18 samples without cashew declared on the label in any manner. The cashew ELISA can be used to detect undeclared cashew residue in foods and as a potential tool for the food industry to assess the effectiveness of allergen control strategies and to guarantee compliance with food labeling regulatory requirements.