高效液相色谱法测定玉米粉中黄曲霉毒素B_1含量的不确定度评定

目的评定高效液相色谱(HPLC)法测定玉米粉中黄曲霉毒素B1含量测量的不确定度。方法依据《化学分析中的不确定度的评估指南》(CNAS-GL06),对HPLC法测定玉米粉中黄曲霉毒素B1含量进行不确定度分析。结果玉米粉中黄曲霉毒素B1含量测定扩展不确定为10.05%,样品含量为(2.59±0.26)μg/kg,影响含量测定的最主要影响因素为标准曲线的拟合及方法的提取回收率。结论本研究建立了简便易行的玉米粉中黄曲霉毒素B1含量检测结果的不确定度评定方法。     

Non-targeted method to detect honey adulteration: Combination of electrochemical and spectrophotometric responses with principal component analysis

Detecting adulteration in honey is not an easy task and most of the traditional methods are usually unaffordable. Thus, we describe the use of cyclic voltammetry using Cu/CuO electrode and UV–vis spectrophotometry along with chemometric tools to detect adulteration of honey with corn syrup. Both honey and corn syrup samples presented an anodic peak at +1.1 V, but the current is variable and depends on the sample composition in relation to the honey and syrup content. A cathodic peak at +0.42 V arises at higher scan rates, which is more pronounced for syrup samples and can be used to discriminate between pure and adulterated samples. This response can be combined with UV/vis absorbance peaks at 285 and 216 nm to identify adulteration. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) allowed differentiating between honey and corn syrup samples and simulated mixtures of them, in which the first two principal components together explain 100.0 % of the data variability, specifically 98.47 % by PC1 and 1.53 % by PC2. The method requires a minimum amount of sample and generates a low amount of waste. Furthermore, it is possible to use portable and cheap equipment, making it more accessible to the beekeeper sector.     

Acute and 28-day repeated dose toxicology studies in mice with aryloxyalkanoate dioxygenase (AAD-1) protein expressed in 2,4-D tolerant DAS-40278-9 maize

DAS-40278-9 maize (corn) plants have been genetically modified by the insertion of the aad-1 gene (aryloxyalkanoate dioxygenase), which confers tolerance to 2,4-dichlorophenoxyacetic acid (2,4-D) and aryloxyphenoxypropionate (AOPP) acetyl coenzyme A carboxylase (ACCase) inhibitors ("fop" herbicides) to enable the effective use of these herbicides on maize. The aad-1 gene, derived from Sphingobium herbicidovorans, encodes the aryloxyalkanoate dioxygenase (AAD-1) enzyme. As part of the safety assessment of the AAD-1 protein expressed in maize, acute and repeated dose mammalian toxicology studies were conducted. AAD-1 protein (heterologously produced) was orally administered to mice at a dose of 2000mg/kg, and no acute lethality or adverse effects were observed. Similarly, no adverse effects were observed in mice in a 28-day repeated-dose dietary toxicity study that incorporated the AAD-1 protein into diets at concentrations up to 1000-fold greater than the highest estimate of human exposure to maize. These results support the conclusion that the AAD-1 protein, as expressed in biotechnology derived DAS-40278-9 maize, represents a negligible risk to human health.     

玉米苞叶对AS家兔平滑肌细胞增殖及凋亡的影响

目的：采用流式细胞术对血管平滑肌细胞增殖周期及凋亡率进行定量检测，从分子水平探讨玉米苞叶防治动脉粥样硬化的作用机制，为临床应用提供理论依据。方法：选择大耳家兔，利用高脂饲料复制家兔动脉粥样硬化模型，随机分为动脉粥样硬化模型组，玉米苞叶煎剂组和正常对照组，成模后给予玉米苞叶煎剂治疗，8周后处死家兔，观察主动脉内膜的病理形态学改变，采用流式细胞术检测平滑肌细胞的凋亡以及增殖周期中各时相变化，结果：模型组血管平滑肌细胞的凋亡率和增殖指数明显高于对照组（P＜0．05），主动脉壁肉眼观察出现典型的硬化斑块，动脉管腔明显狭窄。应用玉米苞叶治疗后平滑肌细胞的凋亡率和增殖指数明显低于模型组（P＜0．05）；主动脉斑块面积较模型组明显减小，动脉管腔狭窄减轻，结论：玉米苞叶对AS家兔平滑肌细胞的增殖与凋亡有明显的调节作用；同时显著减轻AS斑块面积，减轻动脉管腔的狭窄程度，对于防止AS的进一步发展具有重要作用。     

Mycological survey and ochratoxin A natural contamination of swine feedstuffs in Rio de Janeiro State, Brazil

Mycotoxin contamination of animal feeds represents a hazard to human and animal health due to potential transmission to meat and milk. Barley by-products are alternative feeding supplies for animal production. The aims of this assay were to study the mycobiota of feedstuffs and finished swine feed, to determine the ability of Aspergillus and Penicillium isolates to produce ochratoxin A (OTA) and to evaluate OTA occurrence in these substrates. Corn, brewers' grains and finished swine feed samples were collected from different factories. Fungal counts were higher than 2.8 × 10⁴ CFU g⁻¹. Fusarium, Aspergillus and Penicillium genera were isolated at high levels. A 23.7% of the isolates produced 9-116 μg kg⁻¹ of OTA in vitro. Corn samples (44%) were contaminated with 42-224 μg kg⁻¹ of OTA. Finished feed (31%) and brewers' grains samples (13%) were contaminated with 36-120 μg kg⁻¹ and 28-139 μg kg⁻¹ of OTA, respectively. This is the first scientific report on contamination by OTA-producer molds and OTA in swine feedstuffs from Brazil. The presence of OTA in raw materials and finished feed requires periodic monitoring to prevent mycotoxicoses in animal production, reduce economic losses and minimize hazards to human health.     

Effect of the particle size of corn bran on the plasma cholesterol concentration, fecal output and cecal fermentation in rats

We studied the effect of the particle size of corn brain (CB) on the plasma cholesterol concentration, fecal output, and cecal fermentation. Rats were fed a fiber-free diet (FF) or FF containing CB (50 g/kg diet) of six different particle sizes (500, 350, 250, 177, 149, 105 μm in diameter) for 21 days. The fecal wet weight and wet weight of cecal content were significantly higher in the rats fed CB than in those fed FF. Liver total lipids, fecal moisture, fecal bile acids excretion and moisture of cecal content were significantly lower in the rats fed CB than in those fed FF. As the particle size decreased, the plasma cholesterol concentration, fecal wet weight, and fecal bulking effect decreased, while the liver cholesterol concentration, cecal wall weight, wet weight of cecal content, and total organic acids, acetic acid and n-butyric acid in the cecal content increased.     

白术-玉米轮作对白术植株生长及产量影响研究△

目的:研究适宜与白术轮作的作物种类及轮作方法.方法:在前作白术的地上种植春玉米,在春玉米收获后对土壤进行翻耕并灌水、盖薄膜,保持密闭3个月后再种植白术.结果:白术-玉米轮作种植白术效果好,尤其是以春玉米收获后灌水盖薄膜处理,能降低白术植株死苗率,增加白术植株高度和冠幅,增加单株根茎鲜重,提高亩产量.结论:在生产上白术与玉米轮作,可以缩短轮作年限,轮作间隔时间由3～5年减少至1年.     

玉米苞叶煎剂对高脂大鼠血清NO ET水平及内皮凋亡的作用

目的:观察玉米苞叶煎剂对食饵性高血脂大鼠主动脉内皮细胞凋亡的干预作用及血清NO、ET水平的影响。方法:选用雄性SD大鼠,随机分为正常对照、病理模型、阳性对照及玉米苞叶煎剂组。复制食饵性AS早期模型,同时给予玉米苞叶煎剂预防性给药,以吉非罗齐为阳性药对照。实验9周,检测血清脂质,NO和ET,流式细胞术定量检测主动脉内皮细胞凋亡率及增殖指数。结果:玉米苞叶煎剂组TC、TG、VLDL较模型组显著降低(P<0.05);内皮细胞凋亡率较模型组明显下降(P<0.05),增殖指数轻度上升(P>0.05);血清ET下降(P>0.05),NO上升(P>0.05)。结论:玉米苞叶煎剂可调节高脂大鼠血清NO和ET水平,降低内皮凋亡率,促进内皮修复。     

玉米肽糙米胚芽片对酒精性肝损伤保护作用的实验研究

目的研究玉米肽糙米胚芽片对酒精性肝损伤的保护作用。方法采用无水乙醇诱导大鼠酒精性肝损伤模型,实验设低、中、高3个剂量组,其玉米肽糙米胚芽片剂量分别为400、1 200、2 400 mg/（kg.bw）,另设蒸馏水阴性对照组和乙醇模型对照组,每组10只SD大鼠。分别给大鼠连续经口灌胃45 d后进行肝匀浆中丙二醛（MDA）、还原型谷胱甘肽（GSH）、甘油三酯（TG）测定及肝脏组织病理学检查,观察玉米肽糙米胚芽片对酒精性肝损伤的保护作用。结果与模型对照组相比,玉米肽糙米胚芽片中、高剂量组能升高大鼠肝匀浆GSH含量（均P〈0.05）,高剂量组能降低大鼠肝匀浆TG含量（P〈0.05）和减轻肝细胞脂肪变性（P〈0.05）。结论玉米肽糙米胚芽片对酒精性肝损伤具有保护作用。     

Advantageous Features of Plant-based Systems for the Development of HIV Vaccines

Plants have recently become an attractive option for the production of recombinant proteins. Plant-based systems can be used to produce many classes of foreign proteins including candidate vaccine antigens. The selected antigen can be purified from plant material prior to delivery by the preferred route, or alternatively delivered orally in edible plant material that has been processed to give a homogeneous and stable product. Several plant species have been used to express a wide range of vaccine candidates with tobacco, potato and corn being particularly favored. Corn seed is especially well suited to various food processing technologies that generate dry homogeneous material suitable for extended storage and refrigeration-free transport and distribution. Many antigens have been expressed in corn and assessed for efficacy in trials with generally positive results. Candidate HIV vaccines are particularly good targets for plant-based oral delivery since there is a great need for an easily distributed affordable vaccine that could be administered without injection and induce strong mucosal immune responses. As a first step in evaluating plant expression technology with a relevant antigen that might easily be tested in an animal system, we expressed the SIV major surface glycoprotein gp130 (analogous to HIV gp120) in corn seed. Expression levels were achieved that are compatible with conducting oral delivery trials in animals.