Purdey M
Elworthy, Taunton, Somerset, UK.
Med Hypotheses. 2001 Jul;57(1):29-45. doi: 10.1054/mehy.2001.1305.
Ecosystems supporting clusters of sporadic transmissible spongiform encephalopathy (TSE) are characterized by common properties of high-manganese/low-copper, zinc, selenium mineral status, and high-altitude/snow-covered/pre-cambrian mountain terrain where above-average intensities of ultra violet/ozone oxidants are prevalent. Cell culture trials have confirmed the hypothesis that manganese (Mn) substitutes at Prion Protein's (PrP's) vacated copper (Cu) domain, whereupon PrP loses its Cu-mediated antioxidant function, transforming into a protease-resistant misfolded isoform that aggregates into fibril 'tombstone' structures - the key hallmark distinguishing TSE central nervous system (CNS) pathology. The cellular localisation of PrP suggests PrP serves a 'front line' contributory role in neutralizing radicals generated by incoming environmental oxidants, whilst an intensive expression of PrP messenger ribonucleic acid (mRNA) in the retina, melanocytes, epidermis, etc., suggests PrP performs a key antioxidant role as a 'photooxidative shock absorber'; binding of porphyrin IX, Congo red and other photosensitisers to PrPc suggests PrPc serves as an integral associate of the porphyrin/melanin chromophore electron transfer chain; thereby serving as a quencher of singlet O2/superoxide generated by photoenergised chromophores/xeno photosensitisers. It is proposed that sporadic TSE pathogenesis is initiated in the retina of environmentally/genetically predisposed individuals via a two-stage chronic toxic process - Mn substitution at PrP's Cu domain forming a stable Mn2+-PrP complex, followed by an ultra violet in situ photo-oxidization of the Mn2+ component; whereby the latent 'Jekyll and Hyde' capacity of the Mn2+-PrP conjugate is activated into the fully fledged, 'infectious' lethal auto-oxidizing, Mn3+-PrP 'prion' agent. Thus, PrPc's Cu-mediated antioxidant function is replaced by a Mn3+-mediated autooxidant dysfunction. Could the UK's increased loading of a cocktail of environmental oxidants that penetrated the CNS of the UK bovine (ultra violet microwaves/ozone/systemic cu-chelating insecticides) account for a more virulent Mn4+ mediated acceleration of the TSE degenerative process in Mn-contaminated/genetically predisposed individuals, manifesting as the widespread emergence of new-variant bovine spongiform encephalopathy (BSE)/variant Creutzfeldt-Jacob disease (VCJD)/FSE in younger mammals?
支持散发性传染性海绵状脑病(TSE)集群的生态系统具有高锰/低铜、锌、硒矿物质状态以及高海拔/积雪覆盖/前寒武纪山地地形等共同特征,在这些地区,紫外线/臭氧氧化剂的强度高于平均水平。细胞培养试验证实了以下假设:锰(Mn)在朊病毒蛋白(PrP)空出的铜(Cu)结构域处进行替代,随后PrP失去其铜介导的抗氧化功能,转变为抗蛋白酶的错误折叠异构体,聚集成纤维状“墓碑”结构——这是区分TSE中枢神经系统(CNS)病理学的关键标志。PrP的细胞定位表明PrP在中和进入的环境氧化剂产生的自由基方面发挥“一线”促进作用,而PrP信使核糖核酸(mRNA)在视网膜、黑素细胞、表皮等中的强烈表达表明PrP作为“光氧化减震器”发挥关键的抗氧化作用;卟啉IX、刚果红和其他光敏剂与PrPc的结合表明PrPc是卟啉/黑色素发色团电子转移链的一个组成部分;从而作为光激发发色团/异种光敏剂产生的单线态氧/超氧化物的猝灭剂。有人提出,散发性TSE发病机制是通过一个两阶段的慢性毒性过程在环境/遗传易感个体的视网膜中启动的——Mn在PrP的Cu结构域处替代形成稳定的Mn2+-PrP复合物,随后Mn2+成分发生紫外线原位光氧化;由此,Mn2+-PrP共轭物潜在的“杰基尔与海德”能力被激活为完全成熟的、“传染性”的致死性自氧化Mn3+-PrP“朊病毒”因子。因此,PrPc的铜介导的抗氧化功能被Mn3+介导的自氧化功能障碍所取代。英国环境氧化剂混合物负荷增加,这些氧化剂穿透了英国牛的中枢神经系统(紫外线微波/臭氧/全身性铜螯合杀虫剂),这是否可以解释在受锰污染/遗传易感个体中,更具毒性的Mn4+介导的TSE退化过程加速,表现为年轻哺乳动物中广泛出现新变异型牛海绵状脑病(BSE)/变异型克雅氏病(vCJD)/猫海绵状脑病(FSE)?