脱氧雪腐镰刀菌烯醇致动物厌食和呕吐机制的探讨

脱氧雪腐镰刀菌烯醇(DON)是一种由镰刀菌产生的霉菌毒素,其广泛存在于食品和饲料中,严重威胁着人类的健康和食品安全。DON又称呕吐毒素,它可对动物的肠道、大脑以及神经系统产生毒害作用,致使动物产生厌食和呕吐反应。本文综述了DON诱导厌食和呕吐反应的机制,并阐述了肠道微生物和DON诱导厌食和呕吐反应的潜在联系,以期为更深层次研究DON诱导厌食和呕吐反应的机制提供新思路。     

饲料原料中呕吐毒素靶向降解的研究进展

呕吐毒素(Vomitoxin),也称脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON),是由镰刀菌产生的代谢产物,对食用受污染食品的人类和食用受污染的饲料的动物构成严重的健康风险。通常会引起腹泻、呕吐和人类和动物的胃肠道炎症。随着我国自然灾害的频繁爆发,呕吐毒素的污染也随之增加,所以控制呕吐毒素的污染已刻不容缓。本文表述了DON的化学性质、危害作用及生物脱毒方面的研究进展,为降解粮食和饲料中DON含量提供科学依据。     

脱氧雪腐镰刀菌烯醇的免疫毒性研究进展

脱氧雪腐镰刀菌烯醇（deoxynivalenol,DON）是一种单端孢霉烯族毒素,主要由禾谷镰刀菌、尖孢镰刀菌、串珠镰刀菌、拟枝孢镰刀菌、粉红镰刀菌、雪腐镰刀菌等镰刀菌产生,由于它可以引起猪的呕吐,故又名呕吐毒素（vomitoxin,VT）。DON纯品1970年首先从日本香川县感染赤霉病的大麦中分离到并命名。这种毒素广泛存在于霉变的小麦、大麦、燕麦、玉米等谷类作物、发霉的饲料以及被污染的肉、奶等动物性食品中,人畜摄入了被DON污染的食物后,会导致厌食、呕吐、腹泻、发烧、站立不稳和反应迟钝等中毒症状,严重时损害造血系统造成死亡（Plattneretal,2003;敖志刚和陈代文,2008）。     

呕吐毒素对动物肠道结构与功能影响研究进展

脱氧雪腐镰刀菌烯醇(DON)对食物和饲料的污染已成为全球化的问题,人们也逐渐开始重视饲料污染物DON对动物机体造成的影响。随着科学的不断发展,DON神秘的面纱已被逐渐揭开。近年来的研究证实了随饲料经消化道进入动物机体的DON,在通过改变肠道组织形态学,影响肠道功能的同时,也可通过改变肠道营养物质运输载体、紧密链接蛋白、mRNA转录以及某些炎性物质等的表达,影响肠道营养吸收作用、屏障功能、免疫功能以及渗透作用等,最终导致动物机体产生营养不良、腹泻、呕吐和肠道炎症等不良反应。研究还表明,不同情况下DON对不同的动物肠道可以产生不同的影响。     

饲料中呕吐毒素对不同阶段商品猪及种猪的影响

我国不仅是畜牧业生产和消费大国,同时饲料产量也居世界首位,作为饲料中最常添加的谷物原料,其质量安全对饲料生产和养殖业有着重要影响。小麦、玉米等谷物在其生长、收获及加工等阶段未及时按规定处理会产生大量的霉菌毒素,其中呕吐毒素最为常见。呕吐毒素(DON)主要由镰刀菌属(如禾谷镰刀菌、尖孢镰刀菌等)产生,会造成不同阶段商品猪及种猪呕吐、肌肉出血、生长性能和繁殖力的下降等。本文综述了饲料中DON的污染现状及其对养猪生产的危害,进而提出了综合防治措施,为畜牧业生产者更好地防治DON污染、提高养殖收益提供系统科学参考。     

DON、ZEA对免疫的影响及互作效应研究进展

玉米赤霉烯酮(ZEA)和呕吐毒素(DON)是镰刀菌的有毒次生代谢产物,过量能抑制动物机体的免疫功能,造成动物生长速度减缓、繁殖性能降低、抗病能力下降,疫苗免疫效果不理想或免疫失败,造成严重的经济损失。同时这两种毒素间可能产生协同作用增加对免疫功能的抑制作用。本文综述了近几年国内外学者对ZEA和DON造成动物免疫系统抑制及其互作效应的研究进展。     

ZEA、DON及其联合染毒对CTLL-2细胞因子分泌的影响

为研究镰刀菌毒素玉米赤霉烯酮（ZEA）、脱氧雪腐镰刀菌烯醇（DON）及其联合作用对动物免疫功能的影响,试验以CTLL-2细胞（细胞毒性T淋巴细胞株）为材料,用不同浓度的ZEA （0、5、10、20 μg/mL）、DON （0、0.5、1、2 μg/mL）及联合（空白组、5 μg/mL ZEA、0.5 μg/mL DON、5 μg/mL ZEA＋0.5 μg/mL DON）处理CTLL-2细胞48 h,采用ELISA法检测了细胞内及培养上清液中颗粒酶B （GZMB）、穿孔素（PFP）、干扰素γ（IFN-γ）和肿瘤坏死因子α（TNF-α）等细胞因子的含量。结果显示,ZEA、DON能够降低CTLL-2细胞胞内及培养上清液中PFP、GZMB、IFN-γ的浓度,增加TNF-α浓度,染毒组与对照组相比均有显著或极显著差异（P＜0.05;P＜0.01）,且均呈剂量效应关系;ZEA、DON联合染毒表现为加性效应。结果表明,ZEA、DON及其联合作用可通过影响免疫细胞因子的分泌,降低免疫细胞杀伤活力,间接影响机体体液免疫和细胞免疫的负调节,从而导致动物机体免疫机能下降。     

饲料中呕吐毒素的危害和生物脱毒方法研究进展

呕吐毒素又称脱氧雪腐镰刀菌烯醇(deoxynivalenol,DON)是谷物中最为常见的一种真菌毒素,其降低畜禽的生产性能,并且对动物免疫系统、 细胞信号传导和基因的表达均有不同程度的影响.随着我国灾害气候的频频发生,呕吐毒素的污染程度呈现加剧趋势,因此呕吐毒素污染的控制迫在眉睫.传统控制脱氧雪腐镰刀菌烯醇的方法主要有物理法和化学法,但上述两种方法都具有局限性.本文阐述了脱氧雪腐镰刀菌烯醇的化学性质、 毒性作用以及生物脱毒方面的研究进展,为研究生物学方法控制粮食与饲料中呕吐毒素含量提供参考.     

呕吐毒素生物降解机制研究进展

呕吐毒素（DON）是全球农业领域最为关注的食源性真菌毒素之一,主要由镰刀菌产生。谷物类农产品一旦被污染,很难通过普通工艺将其消除。生物降解法消除农产品及其加工制品中的呕吐毒素是近年来的备受学者关注。一批新颖的降解菌、降解酶和降解机制被先后发现,为DON生物降解和防治技术的开发提供了新的切入点。文章根据DON不同的生物降解机制,梳理了近十年的相关研究进展,以便更好地了解呕吐毒素生物降解研究现状、存在的问题以及发展趋势。     

乳酸菌去除脱氧雪腐镰刀菌烯醇的研究进展

脱氧雪腐镰刀菌烯醇(deoxynivalenol, DON)是由镰刀菌属产生的真菌毒素,具有肠道和免疫毒性,在谷物和饲料中污染严重,威胁人类和动物的健康。利用微生物法去除真菌毒素特异性强,效率高且对环境安全,被广泛应用。乳酸菌作为一种益生菌,具有去除DON的能力,同时不会影响产品的品质,成为近年来去除DON的研究热点。本文主要阐述了具有去除DON能力的乳酸菌种类及乳酸菌去除DON的机制,并通过对比其他细菌降解DON的机制和降解酶,推测乳酸菌中可能存在生物降解作用,并对乳酸菌去除DON的应用前景进行了展望。     

Management of anorexia in the cat.

One of the most frequent motivations for seeking veterinary attention for a cat is when the owner recognises a loss of normal appetite in his pet. The medical term for a lack of appetite for food is 'anorexia', and it may be partial or complete. While anorexia is a common manifestation of disease, the mechanisms underlying decreased food intake are complex and not completely understood. The regulation of appetite involves interaction of external stimuli with signals from the gastrointestinal tract and central nervous system. Aberrations in any of the internal control systems for hunger and satiety, or changes in external factors such as diet or feeding environment, can result in partial or total anorexia. The challenge for the practitioner is not only to diagnose and treat the underlying condition, but to recognise at what point inadequate food intake has or will impinge on the patient's nutritional status to the extent that it might deleteriously affect clinical outcome. It is also important to bear in mind the significance that the patient's appetite and food intake has for the cat owner in his overall perception of his pet's condition and quality of life.     

Recent advances in the understanding of Fusarium trichothecene mycotoxicoses.

Recent concepts in the etiology of Fusarium trichothecene mycotoxicoses have been reviewed. The effect of orally administered trichothecenes on tissue metabolism has been traced from the gastrointestinal tract to the liver and subsequently to blood. It is proposed that the hyperaminoacidemia resulting from trichothecene toxicoses contributes to the behavioral changes observed, including loss of appetite and vomiting. Studies with several species and several trichothecenes have shown that elevated brain tryptophan arising from trichothecene-induced aminoacidemia can subsequently alter regional brain serotonin concentrations. This may produce behaviors such as loss of appetite and muscle incoordination characteristic of the firing of serotonergic neurons. Support is also presented for the concept that other Fusarium metabolites such as fusaric acid may act synergistically with trichothecenes to produce these effects.     

Immune and endocrine regulation of food intake in sick animals

To understand why sick animals do not eat, investigators have studied how the immune system interacts with the central nervous system (CNS), where motivation to eat is ultimately controlled. The focus has been on the cytokines secreted by activated mononuclear myeloid cells, which include interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). Either central or peripheral injection of recombinant IL-1β, IL-6, and TNF-α reduce food-motivated behavior and food intake in rodents. Moreover, these cytokines and their receptors are present in the endocrine system and brain, and antagonism of this system (i.e., the cytokine network) has been shown to block or abrogate anorexia induced by inflammatory stimuli. Recent studies indicate that the same cytokines act on adipocytes and induce secretion of leptin, a protein whose activity has been neuroanatomically mapped to brain areas involved in regulating food intake and energy expenditure. Therefore, many findings converge to suggest that the reduction of food intake in sick animals is mediated by inflammatory cytokines, which convey a message from the immune system to the endocrine system and CNS. The nature of this interaction is the focus of this short review.     

Endoscopic Aspiration of Intestinal Contents in Dogs and Cats: 394 Cases

Medical records from 394 dogs and cats that had endoscopic aspiration of intestinal contents for identification of Giardia sp. trophozoites were retrospectively reviewed. The most common indications for endoscopy were chronic vomiting (152), chronic diarrhea (108), chronic vomiting and diarrhea (58), and acute vomiting (33). Metronidazole had been previously administered to 111 animals (28.2%), and to 58.6% of those with chronic diarrhea. Six aspirate samples (1.5%) were positive for Giardia sp. In 3 of these cases a single fecal flotation identified Giardia cysts before endoscopy. The authors conclude that intestinal aspiration in animals from a primarily referral population undergoing upper gastrointestinal endoscopy rarely identifies Giardia and should not be routinely performed. However, animals in which zinc sulfate flotation was not performed or those that did not previously receive metronidazole might benefit from intestinal aspiration.     

浅析反刍动物胃肠道微生物通过肠道－脑轴对宿主的影响

反刍动物胃肠道中存在着众多微生物,如细菌、真菌、原虫和古细菌等。胃肠道微生物对于动物的能量代谢发挥着重要作用,同时对于动物的中枢神经正常功能的发挥也扮演着重要角色。肠道微生物可以与肠道细胞直接接触,不仅产生激活内源性中枢神经系统信号传导机制的代谢物,还可以独立地产生或促成许多神经活性分子的产生。微生物代谢产物和神经活性分子通过神经信号通路、胃肠道内分泌信号通路、免疫系统等关键途径共同形成一个复杂的反射网络,即胃肠道微生物与代谢产物通过传入神经元将信号传导至中枢神经系统。胃肠道微生物与宿主之间通过主要的信号通路相互作用,影响机体胃肠道屏障、营养代谢、免疫应答等生理机能和摄食行为。作者主要从反刍动物胃肠道微生物的种类、微生物通过肠道-脑轴的"自下而上"的传导途径、微生物及其代谢产物通过肠道-脑轴对宿主疾病和行为起到的作用、胃肠道微生物-肠道-脑轴可能的影响因素进行浅析,并对反刍动物胃肠道微生物-肠道-脑轴的研究进行了展望。     

A syndrome resembling feline dysautonomia (Key-Gaskell syndrome) in a dog.

Dysautonomia, or autonomic nervous system dysfunction, was diagnosed in a 1-year-old dog. Clinical signs of disease included diarrhea, vomiting, prolapse of nictitating membranes, and urinary incontinence. Bilateral keratoconjunctivitis sicca, xerostomia, and decreased anal sphincter tone were also observed. On the basis of response to atropine, results of intradermal histamine testing and gastric motility studies, and ocular response to parasympathomimetics and sympathomimetics (direct and indirect acting), autonomic nervous system function was determined to be abnormal. Treatment with metoclopramide hydrochloride and bethanechol chloride resulted in improved attitude, appetite, Schirmer tear test response, and decrease in frequency of vomiting within 24 hours. Bladder function and anal tone improved within 3 weeks.     

Prevalence and clinical signs of avipoxvirus infection in falcons from the Middle East

The prevalence, cutaneous manifestations and concurrent clinical signs of avipoxvirus infection in 3706 falcons in two Middle Eastern countries are reported. Diagnosis was based on evidence of typical 'dry' skin lesions on featherless parts of the body and microscopic detection of Bollinger bodies in epithelial cells. Avipoxvirus was isolated from one representative case. Overall prevalence of cutaneous changes due to avipoxvirus infection did not differ significantly between Kuwait (2.7%) and Dubai (2.3%), although pox lesions were more prevalent on the feet of birds from Kuwait (67.4% vs. 50%) and more common on the eyelids of birds from Dubai (45.6% vs. 30.4%). Foot lesions were always present in birds with multiple infection sites. Some birds from Dubai had severe infection associated with weight loss, anorexia, lethargy, vomiting, central nervous system involvement and ultimately death.     

Cytotoxicity and metabolic stress induced by deoxynivalenol in the porcine intestinal IPEC-J2 cell line

The digestive tract is a target for the Fusarium toxin deoxynivalenol (DON), a major cereal grain contaminant of animal and public health concern. Toxic effects of DON range from diarrhoea, vomiting and gastrointestinal inflammation to necrosis of several tissues. Following ingestion of contaminated food or feed, intestinal epithelial cells are exposed to a high concentration of ingested DON, potentially affecting intestinal functions. Pigs are considered to be the species most sensitive to DON toxicity. However, only few studies directly evaluated DON effects on porcine intestinal epithelial cells. Therefore, we used the porcine intestinal cell line (IPEC-J2) to assess short-term effects of DON on functional characteristics of the intestinal epithelial cells. The cytotoxic effect of DON on IPEC-J2 cells was evaluated by measuring the count of living cells and the activity of lactate dehydrogenase (LDH) released in the culture media at a DON concentration range from 0, 0.5, 2.5 and 10 μm. We demonstrated that DON at concentrations of 2.5 and 10 μm decreased significantly (p < 0.001) the cell count in a dose-dependent manner. At a concentration of 10 μm, DON caused cell damage, including rounding of cells, autolysis and cell loss from the monolayer. The mycotoxin, DON, increased LDH release into the culture medium compared with the control value. The alterations of LDH showed a good agreement with the decrease in cell count. Deoxynivalenol decreased the l-lactate concentration in the fluid supernatant of IPEC-J2 cells at 2.5 μm (p < 0.05) with a maximal effect at 10 μm of DON. To determine whether the altered lactate production may be linked to alterations of energy balance, we measured cellular ATP levels in IPEC-J2 cells. A significant decrease in ATP levels was seen at 48 h in a dose-dependent manner. It could be demonstrated that DON has a distinct cytotoxic effect on IPEC-J2 cells.     

Feeding trials with vomitoxin (deoxynivalenol)-contaminated wheat: effects on swine, poultry, and dairy cattle

Nutritional and toxicologic feeding trials with 3 species of farm animals demonstrated that decreased feed consumption and reduced weight gains in pigs are the main effects of ingestion of a diet with low vomitoxin (deoxynivalenol; DON) content, eg, 2 mg of DON/kg of feed, ie, 2 ppm. The feeding trials indicated that swine can ingest up to 2 mg of DON/kg of feed without serious adverse effects. Poultry can tolerate at least 5 mg of DON/kg feed. In fact, at concentrations up to 5 mg of DON/kg feed, some beneficial effects on poultry were observed. In dairy cattle, feed consumption decreased slightly when a wheat-oats diet containing 6 mg of DON/kg was fed at the rate of 1% of body weight/day, with hay offered ad libitum. In surveys of Canadian grains carried out during the past 3 years, the DON content (maximum of 8.5 mg/kg) in eastern Canadian wheats probably was not high enough to account for reports of feed refusal, vomiting, and reproductive problems in livestock operations. This conclusion is based partly on the fact that even at the highest concentrations of DON found in wheat, formulated diets comprise, at maximum, about 70% to 80% wheat. Consequently, the actual DON content of diets fed to farm animals would be much lower.