氟中毒和碘缺乏病并发地区分布及流行病学概况

氟中毒和碘缺乏病均是世界范围内广泛存在的一类地球化学性疾病。由于两者分布范围极其广泛,在一些地区出现了氟中毒和碘缺乏病交叉流行的现象。在氟中毒和碘缺乏病并发地区,儿童智力水平显著下降,甲状腺肿发生率明显升高。氟碘关系复杂,其对脑组织和甲状腺功能的影响是广泛的,作用机理扑朔迷离。文章综述了氟中毒和碘缺乏病并发地区的分布、形成原因及儿童智力水平和甲状腺肿的流行病学调查等,为进一步研究氟碘对中枢神经系统和甲状腺损伤作用机制提供流行病学资料。     

氟中毒及其相关研究技术

从氟对骨相组织牙齿和骨骼,非骨相组织肝脏、肾脏、脑、胃肠道、中枢神经系统、内分泌系统及生殖系统不同程度的损伤作用入手,较深入的探讨了氟的毒性作用机制。并归纳总结了诊断氟中毒病的各种物理方法和生化指标,以及相关的分子生物学技术。最后,根据各种技术手段的特点,论述其在氟中毒病中的具体应用,为更进一步的研究提供理论基础与技术支持。     

家蚕耐氟与敏感品种乙酰胆碱酯酶的比较研究

用浸叶法添氟以检测氟对家蚕乙酰胆碱酯酶的影响。实验结果显示,添氟后蚕体乙酰胆碱酯酶活性降低,耐氟品种添氟组与对照组差距小于敏感品种;耐氟品种添氟后酶原蛋白含量高于对照组,敏感品种酶原蛋白含量始终低于对照组。研究结果表明,耐氟品种通过乙酰胆碱酯酶基因表达量的增加弥补了氟对乙酰胆碱酯酶活性的影响,使乙酰胆碱酯酶活性总体持平,从而使家蚕产生耐氟性。     

高氟低碘对中枢神经系统的影响

氟中毒和碘缺乏病均是世界范围内广泛存在的一类地球化学性疾病。由于两者分布范围极其广泛,在一些地区出现了氟中毒和碘缺乏病交叉流行的现象。作者综述了高氟低碘地区儿童智力水平和甲状腺肿的流行病学调查,高氟低碘对脑组织、甲状腺及其激素影响的研究进展,并分析了氟、碘相互作用的可能作用机制,为进一步研究氟、碘对机体的影响及其作用机制提供了思路。     

配合饲料中氟含量现状和降低氟含量的措施

氟是动物必需的微量元素,但过量的氟对动物有严重危害,影响动物的健康与生产性能。在生产实践中,控制饲料中氟含量对饲料品质有重要意义。本实验对广东珠江三角洲部分地区的配合饲料中氟含量进行了调查检测,同时提出了防止配合饲料中氟含量超标的几点建议。     

氟与动物健康

氟是一种非金属元素,在自然界中广泛存在,同时氟也是动物的必需微量元素。适量的氟对动物的牙齿、骨骼、钙磷代谢,促进酶的活性都有着积极的作用。但是过量的氟又会造成氟中毒,对动物产生一系列不良影响。本文综述了氟的性质、分布,对机体的影响以及简要介绍氟中毒的防治措施。     

氟对畜禽毒性的作用机理

1928年,Jacob和Reynold指出畜禽摄入过量氟会引起中毒,首次提出了氟对畜禽的毒性作用。随后Kick和Roholm又研究了氟过量对畜禽骨骼的影响,从而使畜禽氟中毒越来越引起人们的重视。本文就氟对畜禽的毒性作用、中毒症状、原因及耐受量作一概述。1 氟对畜寓的毒性机理探讨     

鸡氟中毒引起贫血的发病机制

氟是动物体必需的微量元素,但摄入过量易导致中毒。氟中毒是一种多器官受损害性疾病,可引起机体广泛性的病理损害,造成多种机能和形态的异常改变,国内外就畜禽氟中毒引起的骨相和非骨相损伤已进行过大量的研究。近年来由于一些含高氟的劣质饲料原料进入市场,导致畜禽氟中毒的现象越来越多。贫血是氟病的一个征候,但对其产生的机理至今仍未阐明。为了探讨过量氟导致动物贫血产生的可能机理,现就高氟对鸡红细胞的影响进行综合阐述。1高氟对鸡红细胞数的影响李兴霞等首次报道了鸡氟中毒时红细胞的数量和血红蛋白含量会减少,且呈明显的剂量一效…     

微量元素氟的生理作用及其对畜禽健康的影响

氟是畜禽正常生长必需的微量元素之一，适量的氟对畜禽的牙齿、骨骼、钙磷代谢、生长发育和繁殖均有着积极作用。综述了氟的来源、需要、吸收、分布及代谢以及生理功能和过量氟对机体健康的影响，并简要介绍了氟中毒的防治措施。     

氟对畜禽毒性的研究

氟对畜禽毒性的研究浙江省饲料监察所屈健１９２８年，Ｊａｃｏｂ和Ｒｅｙｎｅｌｄ指出畜禽摄入过量氟会引起中毒，首次提出了氟对畜禽的毒性作用。随后Ｋｉｃｋ和Ｒｏｈｏｌｍ又研究了氟过量对畜禽骨骼的影响，从而使畜禽氟中毒越来越引起人们的重视。本文将就氟对畜禽的...     

外源性硫化氢的毒性机制及在动物体内代谢的研究进展

外源性硫化氢是畜禽养殖过程中由含硫有机物发酵而产生的一种恶臭气体,其具有神经毒性,能刺激眼和呼吸器官,使氧化型细胞色素酶失去活性,并有直接抑制呼吸中枢等作用,引起急性和慢性中毒,高浓度可导致迅速窒息死亡,严重影响畜禽生产、动物福利和人类健康。然而,硫化氢中毒的预防和治疗至今仍缺乏有效的方法,因此,深入研究外源性硫化氢在动物体内的吸收代谢规律,阐明其作用机制,对缓解硫化氢在畜禽生产中的危害具有重要意义。本文从外源性硫化氢的性质及毒性机制、外源性硫化氢对动物机体的危害、外源性硫化氢进入动物体内的途径和分布状况及新陈代谢规律4个方面进行综述,以期为外源性硫化氢对畜禽健康影响机制研究提供参考,为动物健康养殖提供理论依据。     

脱氧雪腐镰刀菌烯醇导致厌食和呕吐的机制研究进展

由镰刀菌产生的脱氧雪腐镰刀菌烯醇(DON)广泛存在于谷物及其加工产品中,对动物和人类健康有着潜在的危害。DON具有多方面的毒性作用,而厌食和呕吐是机体摄入DON后出现的最典型症状,厌食和呕吐的产生主要归因于DON对中枢神经系统和胃肠道食欲因子的影响。DON可直接作用于中枢神经系统的呕吐中枢产生呕吐反射,同时激活下丘脑神经元分泌食欲调节因子影响采食;DON可诱导肠内分泌细胞分泌肽YY、胆囊收缩素等食欲调节因子从而引发厌食;DON对中枢神经系统和胃肠道分泌的影响又可通过肠-脑轴产生关联;此外,细胞因子及肠道微生物也部分参与了反应的介导。本文综述了DON诱发机体出现厌食和呕吐的可能机制,以期为找到相应解决措施提供理论指导。     

紫锥菊根末的安全药理学研究

对健康昆明小鼠连续一周灌服不同浓度的紫锥菊根末生药液,观察其对健康昆明小鼠中枢神经系统、呼吸系统和心率的影响,以考察紫锥菊根末的潜在不良反应.结果表明,紫锥菊根末对健康昆明小鼠的中枢神经系统、呼吸系统和心率均无明显影响.     

Oestrogens in the mammalian brain: from conception to adulthood--a review

Environmental and plant oestrogens have been identified as compounds that when ingested, disrupt the physiological pathways of endogenous oestrogen actions and thus, act as agonists or antagonists of oestrogen. Although the risks of exposure to exogenous oestrogens (ExEs) are subject to scientific debate, the question of how ExE exposure affects the central nervous system remains to be answered. We attempt to summarise the mechanisms of oestrogenic effects in the central nervous tissue with the purpose to highlight the avenues potentially used by ExEs. The genomic and rapid, non-genomic cellular pathways activated by oestrogen are listed and discussed together with the best known interneuronal mechanisms of oestrogenic effects. Because the effects of oestrogen on the brain seem to be age dependent, we also found it necessary to put the age-dependent oestrogenic effects in parallel to their intra- and intercellular mechanisms of action. Finally, considering the practical risks of human ExE exposure, we briefly discuss the human significance of this matter. We believe this short review of the topic became necessary because recent data suggest new fields and pathways for endogenous oestrogen actions and have generated the concern that the hidden exposure of humans and domestic animal species to ExEs may also exert its beneficial and/or adverse effects through these avenues.     

An in vitro system to study trans-neuronal spread of pseudorabies virus infection

The neuronal spread of infection of alpha herpesviruses is controlled by unknown mechanisms. In the natural host, primary infection always leads to invasion of the peripheral nervous system, but rarely results in extensive invasion of the central nervous system. After reactivation of latent infection in the peripheral nervous system, virions are produced and shed from epithelial surfaces, but rarely invade the central nervous system. We have been studying two aspects of the general problem. First, using GFP and mRFP fusion proteins, we have used video confocal microscopy to assess mechanisms that influence spread of pseudorabies (PRV) virion components within axons. Second, and the subject of this report, is the development of a new in vitro cell culture system that enables the study of trans-neuronal spread of infection from neurons to non-neuronal cells similar to what happens after reactivation and spread to epithelial surfaces. We have developed a tissue culture system involving tri-chamber Teflon rings that enables facile analysis of trans-neuronal spread. The system duplicates all the known in vivo correlates of trans-neuronal spread and provides the opportunity to do both quantitative and qualitative assessment of spread of PRV infection from infected neurons to non-neuronal cells.     

The Diagnosis and Surgical Correction of Congenital Portosystemic Vascular Anomalies in Two Calves and Two Foals

Two calves and two foals presented with episodic clinical signs of diffuse central nervous system disease. Portosystemic anomalies were tentatively diagnosed based on the history, clinical signs, and increased serum concentrations of blood ammonia and total serum bile acids with normal concentrations of liver derived enzymes. One calf died before intraoperative contrast portography, whereas the other calf and both foals had marked clinical improvement after intensive medical therapy. Surgical correction was attempted in these three animals and was successful in one foal. A right paracostal celiotomy was superior to a ventral median approach for exposure to the portal vascular system and shunt access.     

MAGNETIC RESONANCE IMAGING CHARACTERISTICS IN FOUR DOGS WITH CENTRAL NERVOUS SYSTEM NEOSPOROSIS

Neosporosis is a polysystemic disease that can affect dogs of any age and can cause inflammation of the central nervous system. Antemortem diagnosis can be challenging, as clinical and conventional laboratory test findings are often nonspecific. A previous report described cerebellar lesions in brain MRI studies of seven dogs and proposed that these may be characteristic for central nervous system Neosporosis. The purpose of this retrospective study was to describe MRI characteristics in another group of dogs with confirmed central nervous system neosporosis and compare them with the previous report. The hospital's database was searched for dogs with confirmed central nervous system neosporosis and four observers recorded findings from each dog's MRI studies. A total of four dogs met inclusion criteria. Neurologic examination was indicative of a forebrain and cerebellar lesion in dog 2 and multifocal central nervous system disease in dogs 1, 3, and 4. Magnetic resonance imaging showed mild bilateral and symmetrical cerebellar atrophy in three of four dogs (dogs 2, 3, 4), intramedullary spinal cord changes in two dogs (dogs 3, 4) and a mesencephalic and metencephalic lesion in one dog (dog 2). Multifocal brain lesions were recognized in two dogs (dogs 1, 4) and were present in the thalamus, lentiform nucleus, centrum semiovale, internal capsule, brainstem and cortical gray matter of the frontal, parietal or temporal lobe. Findings indicated that central nervous system neosporosis may be characterized by multifocal MRI lesions as well as cerebellar involvement in dogs.     

试验性氟中毒鸡睾丸组织的病理学研究

30只180日龄京北939公鸡被随机平均分为两组，每鸡单笼饲养，饲喂相同全价配合饲料。对照组饮自来水，试验组于自来水中添加3000mg／L氟化钠。70d后测定体质量、睾丸鲜质量，并对鸡睾丸组织进行光学和超微病理学观察。结果表明，高氟可显著抑制鸡的生长和及睾丸发育，染氟鸡活体质量、睾丸质量、睾丸质量／活体质量均显著低于对照组，高氟可严重损伤鸡睾丸曲细精管、生精细胞及间质细胞。     

Pemoline and tetramisole 'positives' in English racehorses following levamisole administration

Pemoline is a central nervous system stimulant that has been used to treat attention-deficit hyperactivity disorder and narcolepsy in humans; its identification in horses could be considered evidence of attempts to influence performance. Two recent pemoline 'positives' in English racehorses led us to review the chemical relationships between tetramisole, levamisole, aminorex and pemoline. Pemoline is a simple oxidation product of aminorex, which has been shown in the United States and elsewhere to be an equine metabolite of levamisole. Based on the clear structural relationships between aminorex and pemoline, we conclude that levamisole can metabolise to pemoline in horses and that pemoline identifications in horses post levamisole administration are likely to be associated with levamisole administration. Levamisole should not be administered to horses about to compete because of its ability to metabolise to two central nervous system stimulants, aminorex and pemoline.     

Congenital defects of the bovine central nervous system

Congenital brain defects in cattle are usually obvious at birth, but detection may depend on the nature and extent of the defect. The cause may be genetic or environmental, or the cause may be unknown. Many central nervous system defects are inherited as a simple autosomal recessive trait and may have a significant economic impact on purebred and commercial cattle operations. A common structural defect of genetic nature is internal hydrocephalus. A functional defect of simple autosomal recessive inheritance is bovine progressive degenerative myeloencephalopathy. The most significant teratogenic agents causing central nervous system defects are prenatal viral infections such as bovine virus diarrhea and bluetongue viruses. Many other defects of the central nervous system are reviewed.