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Devi S, Chaturvedi M, Fatima S, Priya S. Environmental factors modulating protein conformations and their role in protein aggregation diseases. Toxicology 2022; 465:153049. [PMID: 34818560 DOI: 10.1016/j.tox.2021.153049] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 11/12/2021] [Accepted: 11/20/2021] [Indexed: 12/13/2022]
Abstract
The adverse physiological conditions have been long known to impact protein synthesis, folding and functionality. Major physiological factors such as the effect of pH, temperature, salt and pressure are extensively studied for their impact on protein structure and homeostasis. However, in the current scenario, the environmental risk factors (pollutants) have gained impetus in research because of their increasing concentrations in the environment and strong epidemiologic link with protein aggregation disorders. Here, we review the physiological and environmental risk factors for their impact on protein conformational changes, misfolding, aggregation, and associated pathological conditions, especially environmental risk factors associated pathologies.
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Affiliation(s)
- Shweta Devi
- Systems Toxicology and Health Risk Assessment Group, Vishvigyan Bhawan, 31, Mahatma Gandhi Marg, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Minal Chaturvedi
- Systems Toxicology and Health Risk Assessment Group, Vishvigyan Bhawan, 31, Mahatma Gandhi Marg, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Siraj Fatima
- Systems Toxicology and Health Risk Assessment Group, Vishvigyan Bhawan, 31, Mahatma Gandhi Marg, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Smriti Priya
- Systems Toxicology and Health Risk Assessment Group, Vishvigyan Bhawan, 31, Mahatma Gandhi Marg, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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Ricci A, Allende A, Bolton D, Chemaly M, Davies R, Fernández Escámez PS, Gironés R, Herman L, Koutsoumanis K, Lindqvist R, Nørrung B, Robertson L, Sanaa M, Simmons M, Skandamis P, Snary E, Speybroeck N, Kuile BT, Threlfall J, Wahlström H, Adkin A, De Koeijer A, Ducrot C, Griffin J, Ortiz Pelaez A, Latronico F, Ru G. Bovine spongiform encephalopathy (BSE) cases born after the total feed ban. EFSA J 2017; 15:e04885. [PMID: 32625550 PMCID: PMC7010122 DOI: 10.2903/j.efsa.2017.4885] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Sixty bovine spongiform encephalopathy (BSE) cases of Classical or unknown type (BARB‐60 cases) were born after the date of entry into force of the EU total feed ban on 1 January 2001. The European Commission has requested EFSA to provide a scientific opinion on the most likely origin(s) of these BARB‐60 cases; whether feeding with material contaminated with the BSE agent can be excluded as the origin of any of these cases and, if so, whether there is enough scientific evidence to conclude that such cases had a spontaneous origin. The source of infection cannot be ascertained at the individual level for any BSE case, including these BARB‐60 cases, so uncertainty remains high about the origin of disease in each of these animals, but when compared with other biologically plausible sources of infection (maternal, environmental, genetic, iatrogenic), feed‐borne exposure is the most likely. This exposure was apparently excluded for only one of these BARB‐60 cases. However, there is considerable uncertainty associated with the data collected through the field investigation of these cases, due to a time span of several years between the potential exposure of the animal and the confirmation of disease, recall difficulty, and the general paucity of documented objective evidence available in the farms at the time of the investigation. Thus, feeding with material contaminated with the BSE agent cannot be excluded as the origin of any of the BARB‐60 cases, nor is it possible to definitively attribute feed as the cause of any of the BARB‐60 cases. A case of disease is classified as spontaneous by a process of elimination, excluding all other definable possibilities; with regard to the BARB‐60 cases, it is not possible to conclude that any of them had a spontaneous origin.
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Imrie CE, Korre A, Munoz-Melendez G. Spatial correlation between the prevalence of transmissible spongiform diseases and British soil geochemistry. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2009; 31:133-145. [PMID: 18427934 DOI: 10.1007/s10653-008-9172-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Accepted: 04/02/2008] [Indexed: 05/26/2023]
Abstract
Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurological conditions affecting a number of mammals, including sheep and goats (scrapie), cows (BSE), and humans (Creutzfeldt-Jakob disease). The diseases are widely believed to be caused by the misfolding of the normal prion protein to a pathological isoform, which is thought to act as an infectious agent. Outbreaks of the disease are commonly attributed to contaminated feed and genetic susceptibility. However, the implication of copper and manganese in the pathology of the disease, and its apparent geographical clustering, have prompted suggestions of a link with trace elements in the environment. Nevertheless, studies of soils at regional scales have failed to provide evidence of an environmental risk factor. This study uses geostatistical techniques to investigate the correlations between the distribution of TSE prevalence and soil geochemical variables across the UK according to different spatial scales. A similar spatial pattern in scrapie and BSE occurrence is identified, which may be linked with increasing pH and total organic carbon, and decreasing iodine concentration. However, the pattern also resembles that of the density of dairy farming. Nevertheless, despite the low spatial resolution of the TSE data available for this study, the fact that significant correlations are detected indicates there is a possibility of a link between soil geochemistry, scrapie, and BSE. It is suggested that further investigations of the prevalence of TSE and environmental exposure to trace metals should take into account the factors affecting their bioavailability.
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Affiliation(s)
- C E Imrie
- Department of Earth Science and Engineering, Imperial College London, London, UK.
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Zhao D, Wang J, Zhang Z, Zhang J. Photocatalytic degradation of omethoate using NaY zeolite-supported TiO2. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/s11705-009-0053-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Hortells P, Monleón E, Acín C, Vargas A, Ryffel B, Cesbron JY, Badiola JJ, Monzón M. Effect of the dimethoate administration on a Scrapie murine model. Zoonoses Public Health 2008; 55:368-75. [PMID: 18667030 DOI: 10.1111/j.1863-2378.2008.01139.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Some authors have associated organophosphate compounds with susceptibility to transmissible spongiform encephalopathy (TSE) and even with the origin of this group of diseases. Nevertheless, the actual role played by these compounds still remains unclear. The aim of this study was to assess the effect of oral exposure to dimethoate (DMT) on the development of Scrapie using a genetically modified murine model. A total of 70 C57BL/6 mice over-expressing the PrP gene (Tg20) were included in the present study. A portion of the mice were intraperitoneally inoculated, while the rest were maintained as non-infected controls. Animals from the treated group were exposed to dimethoate dissolved in drinking water from the beginning of the experiment. Variables of incubation period, spongiosis, PrPsc deposits, glial over-expression, neuronal loss, and amyloid plaques were assessed in all animals. According to the results, a treatment consisting of a daily 15 mg/kg dose of DMT for 5 weeks did not show any effect on any of the variables assessed. Although more exhaustive studies for assessing different doses and organic compounds are required, this finding constitutes an empirical study that rules out the possibility that this compound may have a predisposing effect on TSEs.
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Affiliation(s)
- P Hortells
- Research Centre for Prion Diseases, Faculty of Veterinary, University of Zaragoza, Zaragoza, Spain
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Seidel B, Thomzig A, Buschmann A, Groschup MH, Peters R, Beekes M, Terytze K. Scrapie Agent (Strain 263K) can transmit disease via the oral route after persistence in soil over years. PLoS One 2007; 2:e435. [PMID: 17502917 PMCID: PMC1855989 DOI: 10.1371/journal.pone.0000435] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 04/18/2007] [Indexed: 11/19/2022] Open
Abstract
The persistence of infectious biomolecules in soil constitutes a substantial challenge. This holds particularly true with respect to prions, the causative agents of transmissible spongiform encephalopathies (TSEs) such as scrapie, bovine spongiform encephalopathy (BSE), or chronic wasting disease (CWD). Various studies have indicated that prions are able to persist in soil for years without losing their pathogenic activity. Dissemination of prions into the environment can occur from several sources, e.g., infectious placenta or amniotic fluid of sheep. Furthermore, environmental contamination by saliva, excrements or non-sterilized agricultural organic fertilizer is conceivable. Natural transmission of scrapie in the field seems to occur via the alimentary tract in the majority of cases, and scrapie-free sheep flocks can become infected on pastures where outbreaks of scrapie had been observed before. These findings point to a sustained contagion in the environment, and notably the soil. By using outdoor lysimeters, we simulated a contamination of standard soil with hamster-adapted 263K scrapie prions, and analyzed the presence and biological activity of the soil-associated PrPSc and infectivity by Western blotting and hamster bioassay, respectively. Our results showed that 263K scrapie agent can persist in soil at least over 29 months. Strikingly, not only the contaminated soil itself retained high levels of infectivity, as evidenced by oral administration to Syrian hamsters, but also feeding of aqueous soil extracts was able to induce disease in the reporter animals. We could also demonstrate that PrPSc in soil, extracted after 21 months, provides a catalytically active seed in the protein misfolding cyclic amplification (PMCA) reaction. PMCA opens therefore a perspective for considerably improving the detectability of prions in soil samples from the field.
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Affiliation(s)
- Bjoern Seidel
- Fraunhofer Institute for Molecular Biology und Applied Ecology (IME), Schmallenberg, Germany.
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Poerschmann J, Trommler U, Biedermann W, Truyen U, Lücker E. Sequential pressurized liquid extraction to determine brain-originating fatty acids in meat products as markers in bovine spongiform encephalopathy risk assessment studies. J Chromatogr A 2006; 1127:26-33. [PMID: 16782118 DOI: 10.1016/j.chroma.2006.05.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Revised: 05/08/2006] [Accepted: 05/11/2006] [Indexed: 11/26/2022]
Abstract
A new approach using sequential pressurized liquid extraction described recently [J. Poerschmann, R. Carlson, J. Chromatogr. A, 1127 (2006) 18-25] was applied to determine lipid markers originating from central nervous system (CNS) tissue of cows in heat-processed sausages. These studies are very important in quality control as well as risk assessment studies in the face of the bovine spongiform encephalopathy (BSE) crisis. Diagnostic CNS lipid markers, which should not be present in meat products without CNS addition, were recognized on complete transesterification as polar 2-hydroxy-fatty acids (2OH-24:0, 2OH-24:1, 2OH-22:0, 2OH-18:0, shorthand designation) as well as odd-numbered non-branched fatty acids beyond C(22). An array of other fatty acids including lignoceric acid (24:0), nervonic acid (24:1), arachidonic acid (20:4), and polyunsaturated nC(22)-surrogates are strongly related to CNS lipids, but occur as traces in meat products without CNS addition as well, thus reducing their value as diagnostic markers. Samples including meat products without CNS addition, meat with 3% CNS addition, as well as pure CNS homogenates, were subjected to sequential PLE (pressurized liquid extraction) consisting of two steps: n-hexane/acetone 9:1 (v/v) extraction at 50 degrees C to remove neutral lipids, followed by chloroform/methanol 1:4 (v/v) extraction at 110 degrees C to isolate polar CNS lipids (two 10 min PLE cycles each). To enhance the fractionation efficiency, cyanopropyl modified silica as well as chemically not modified silica sorbent was used at the outlet of the PLE cartridge to retard polar lipids in the first extraction step. This method proved superior to widely distributed exhaustive lipid extraction followed by solid-phase extraction (SPE) using silica regarding lipid recoveries and clear-cut boundaries between lipid classes. Methodological studies showed that the alcoholysis using trimethylchlorosilane/methanol (1:9, v/v) is an excellent method for the complete transesterification of lipids and quantitative formation of methyl esters.
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Affiliation(s)
- J Poerschmann
- UFZ-Center for Environmental Research, Leipzig-Halle, Permoserstrasse 15, 04318 Leipzig, Germany.
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Purdey M. Metal microcrystal pollutants: the heat resistant, transmissible nucleating agents that initiate the pathogenesis of TSEs? Med Hypotheses 2005; 65:448-77. [PMID: 15908137 DOI: 10.1016/j.mehy.2005.03.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Accepted: 03/09/2005] [Indexed: 01/09/2023]
Abstract
This paper exposes the flaws in the conventional consensus on the origins of transmissible spongiform encephalopathies (TSEs) which decrees that the protein-only misfolded 'prion' represents the primary aetiological transmissible agent, and then reviews/presents the emerging data which indicates that environmental exposure to metal microcrystal pollutants (sourced from munitions, etc.) represents the heat resistant, transmissible nucleating agents which seed the metal-prion protein (PrP)-ferritin fibril crystals that cause TSE. Fresh analytical data is presented on the levels of metals in ecosystems which support populations affected by clusters of variant Creutzfeldt-Jacob disease (vCJD), sporadic/familial CJD, and the scrapie types of TSE that have emerged in the UK, Sicily, Sardinia, Calabria and Japan. This data further substantiates the abnormal geochemical template (e.g., elevated strontium (Sr), barium (Ba) and silver (Ag)) which was observed as a common hallmark of the TSE cluster ecosystems across North America, thereby supporting the hypothesis that these microcrystals serve as the piezoelectrion nucleators which seed the growth/multireplication of the aberrant metal-PrP-ferritin fibril features which characterise the neuropathology of the TSE diseased brain. A secondary pathogenic mechanism entails the inactivation of the sulphated proteoglycans which normally regulate the mineralisation process. This can be induced by a rogue metal mediated chelation of free sulphur, or by contamination with organo-sulphur pollutants that substitute at natural sulphur bonds, or via a mutation to the S-proteoglycan cell line; thereby enabling the aberrant overgrowth of rogue fibril crystal formations that possess a piezoelectric capacity which compromises the ability of the contaminated individual to process incoming acoustic/tactile pressure waves in the normal way. The crystals transduce incoming sonic energy into electrical energy, which, in turn, generates magnetic fields on the crystal surfaces that initiate chain reactions of free radical mediated spongiform neurodegeneration. Metal microcrystal nucleating agents provide a group of plausible aetiological candidates that explain the unique properties of the TSE causal agent - such as heat resistance, transmissibility, etc. - which the protein-only prion model fails to fulfill. This paper also discusses the possible nutritional measures that could best be adopted by populations living in high risk TSE ecosystems; as a means of preventing the successful implantation of these rogue microcrystals and their consequent hypermineralisation of the soft tissues within the CNS.
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Affiliation(s)
- Mark Purdey
- High Barn Farm, Elworthy, Taunton, Somerset TA4 3PX, UK.
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Chun M, Chngchun S, Yanghao G, Jianfeng C, Fen Y. Study on characteristics of biocometabolic removal of omethoate by the Aspergillus spp. WATER RESEARCH 2004; 38:1139-1146. [PMID: 14975646 DOI: 10.1016/j.watres.2003.11.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2002] [Revised: 11/04/2003] [Accepted: 11/13/2003] [Indexed: 05/24/2023]
Abstract
A strain Aspergillus spp. F1 which could effectively metabolized omethoate was screened out in this study. F1 tended to form granula with diameter 4-5mm after 5 days culture in shaker. The pH range from 4.5 to 6.5 was the suitable pH range for growth and metabolism of Aspergillus spp. F1. The maximum omethoate removal rate was about 3.0mg/(hL), and the removal fraction of omethoate reached 90% after 8 days culture when initial concentrations of omethoate were not more than 2000mg/L in medium. There was no obvious relativity between cell growth and cometabolism of omethoate. Starch was the best carbon source for omethoate removal and the result after 3 days reached 56.6% removal. F1 could use omethoate to metabolize as single nitrogen or phosphate source. The residual fragments in medium after treatment with the Aspergillus spp. F1 were determined by gas chromatography-mass spectrometry. The analysis results showed that only fragment o,o,s,-trimethyl phosphorothioate (TEP) containing phosphorus was available and the fragment containing nitrogen was consumed by F1 thoroughly in culture process. But no accumulations of TEP were observed in the omethoate bioremediation process. F1 could effectively remove omethoate in complex nutritional environment safely.
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Affiliation(s)
- Meng Chun
- Department of Food Science and Biotechnology, Fuzhou University, Fuzhou, Fujian, China
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Purdey M. Does an infrasonic acoustic shock wave resonance of the manganese 3+ loaded/copper depleted prion protein initiate the pathogenesis of TSE? Med Hypotheses 2003; 60:797-820. [PMID: 12699706 DOI: 10.1016/s0306-9877(03)00007-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Intensive exposures to natural and artificial sources of infrasonic acoustic shock (tectonic disturbances, supersonic aeroplanes, etc.) have been observed in ecosystems supporting mammalian populations that are blighted by clusters of traditional and new variant strains of transmissible spongiform encephalopathy (TSE). But TSEs will only emerge in those 'infrasound-rich' environments which are simultaneously influenced by eco-factors that induce a high manganese (Mn)/low copper (Cu)-zinc (Zn) ratio in brains of local mammalian populations. Since cellular prion protein (PrPc) is a cupro-protein expressed throughout the circadian mediated pathways of the body, it is proposed that PrP's Cu component performs a role in the conduction and distribution of endogenous electromagnetic energy; energy that has been transduced from incoming ultraviolet, acoustic, geomagnetic radiations. TSE pathogenesis is initiated once Mn substitutes at the vacant Cu domain on PrPc and forms a nonpathogenic, protease resistant, 'sleeping' prion. A second stage of pathogenesis comes into play once a low frequency wave of infrasonic shock metamorphoses the piezoelectric atomic structure of the Mn 3+ component of the prion, thereby 'priming' the sleeping prion into its fully fledged, pathogenic TSE isoform - where the paramagnetic status of the Mn 3+ atom is transformed into a stable ferrimagnetic lattice work, due to the strong electron-phonon coupling resulting from the dynamic 'Jahn-Teller' type distortions of the oxygen octahedra specific to the trivalent Mn species. The so called 'infectivity' of the prion is a misnomer and should be correctly defined as the contagious field inducing capacity of the ferrimagnetic Mn 3+ component of the prion; which remains pathogenic at all temperatures below the 'curie point'. A progressive domino-like 'metal to ligand to metal' ferrimagnetic corruption of the conduits of electromagnetic superexchange is initiated. The TSE diseased brain can be likened to a solar charged battery on continuous charge; where the Mn contaminated/Cu depleted circadian-auditory pathways absorb and pile up, rather than conduct the vital life force energies of incoming ultra violet, acoustic and geomagnetic radiation. Instead of harnessing these energies for the body's own bio-rhythmic requirements, an infrasonic shock induced metamorphosis of the Mn atom intervenes; initiating an explosive pathogenesis that perverts the healthy pathways of darkness and light; Cu prions are replaced by hyperpolarized Mn 3+ prions that seed self perpetuating 'cluster bombs' of free radical mediated neurodegeneration. TSE ensues.
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Bounias M, Purdey M. Transmissible spongiform encephalopathies: a family of etiologically complex diseases--a review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2002; 297:1-19. [PMID: 12389776 DOI: 10.1016/s0048-9697(02)00140-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The upsurge of 'mad cow disease' with its human implications has raised the problem of the etiological mechanisms and the similarities or differences underlying the family of transmissible spongiform encephalopathies. Structural properties of prions are reviewed in connection with their natural distribution and functions, factors of transmissibility and mechanisms of pathogenicity. Polymorphism is examined in relation to disease phenotype variants. The role of oxidative factors is emphasized, while raising complexity about the role of copper ions. Further investigation directions are suggested.
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Brown DR. BSE did not cause variant CJD: an alternative cause related to post-industrial environmental contamination. Med Hypotheses 2001; 57:555-60. [PMID: 11735310 DOI: 10.1054/mehy.2001.1388] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The new prion diseases that have emerged in the last 15 years are bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (variant CJD). Although initially confined to the UK, these diseases have recently emerged in other European countries. The accepted cause of the human disease is that BSE spread from cattle to humans by the consumption of infected beef. However, the evidence that supports this is very thin. This article describes this evidence and lists a series of hypotheses concerning the cause of both BSE and variant CJD. The final hypothesis is based on recent evidence linking prion diseases to environmental factors including manganese. High environmental availability of manganese is associated with the prevalence of those prion diseases not linked to BSE. Therefore it is quite possible that BSE and variant CJD have emerged as a result of manganese-rich industrial pollution that has only occurred in the last century.
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Affiliation(s)
- D R Brown
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
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Kourie JI. Mechanisms of prion-induced modifications in membrane transport properties: implications for signal transduction and neurotoxicity. Chem Biol Interact 2001; 138:1-26. [PMID: 11640912 DOI: 10.1016/s0009-2797(01)00228-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Prion-related encephalopathies are associated with the conversion of a normal cellular isoform of prion protein (PrP(c)) to an abnormal pathologic scrapie isoform (PrP(Sc)). The conversion of this single polypeptide chain involves a reduction in the alpha-helices and an increase in beta-sheet content. This change in the content ratio of alpha-helices to beta-sheets may explain the diversity in the proposed mechanisms of action. Many of the pathogenic properties of PrP(Sc), such as neurotoxicity, proteinase-resistant properties and induction of hypertrophy and proliferation of astrocytes, have been attributed to the peptide fragment corresponding to residues 106-126 of prion (PrP[106-126]). In particular, the amyloidogenic and hydrophobic core AGAAAAGA has been implicated in modulation of neurotoxicity and the secondary structure of PrP[106-126]. Because of some similarities between the properties of PrP[106-126] and PrP(Sc), the former is used as a useful tool to characterize the pharmacological and biophysical properties of PrP(Sc) in general and of that domain in particular, by various laboratories. However, it is important to note that by no means can PrP[106-126] be considered a complete equivalent to PrP(Sc) in function. Several hypotheses have been proposed to explain prion-induced neurodegenerative diseases. These non-exclusive hypotheses include: (i) changes in the membrane microviscosity; (ii) changes in the intracellular Ca(2+) homeostasis; (iii) superoxide dismutase and Cu(2+) homeostasis; and (iv) changes in the immune system. The prion-induced modification in Ca(2+) homeostasis is the result of: (1) prion interaction with intrinsic ion transport proteins, e.g. L-type Ca(2+) channels in the surface membrane, and IP(3)-modulated Ca(2+) channels in the internal membranes, and/or (2) formation of cation channels. These two mechanisms of action lead to changes in Ca(2+) homeostasis that further augment the abnormal electrical activity and the distortion of signal transduction causing cell death. It is concluded that the hypothesis of the interaction of PrP[106-126] with membranes and formation of redox-sensitive and pH-modulated heterogeneous ion channels is consistent with: (a) PrP-induced changes in membrane fluidity and viscosity; (b) PrP-induced changes in Ca(2+) homeostasis (and does not exclude changes in endogenous Ca(2+) transport pathways and Cu(2+) homeostasis); (c) PrP role as an antioxidant; and (d) the PrP structural properties, i.e. beta sheets, protein aggregation, hydrophobicity, functional significance of specific amino acids (e.g. methionine, histidine) and regulation with low pH.
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Affiliation(s)
- J I Kourie
- Membrane Transport Group, Department of Chemistry, The Faculties, The Australian National University, ACT, 0200, Canberra, Australia.
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Abstract
▪ Abstract The study of epidemics provides a unique point of entry for examining the relationships among cultural assumptions, institutional forms, and states of mind. The Black Death is said to have contributed to the emergence of nation states, the rise of mercantile economies, and the religious movements that led to the Reformation. It may also have brought about new ways of understanding God, the meaning of death, and the role of authority in religious and social life. Cholera induced a public health approach that stressed quarantine, and venereal diseases led to contact tracing. Western medicine, however, failed to cure the epidemics that resulted from imperial expansion into the Americas, Asia, Africa, and Europe. The focus of this essay is on the impact of two contemporary epidemics considered to be caused by prions, a newly recognized infectious agent: kuru in Papua New Guinea and bovine spongiform encephalopathy (associated with variant Creutzfeldt-Jakob disease) in Europe. A close look at epidemics constitutes a sampling device for illuminating relationships among illness, social forms, and social thought. Theories of disease causation provide ways of thinking about the world and sets of directions for acting in it.
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Affiliation(s)
- Shirley Lindenbaum
- Department of Anthropology, Graduate Center, City University of New York, New York 10036
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Purdey M. Does an ultra violet photooxidation of the manganese-loaded/copper-depleted prion protein in the retina initiate the pathogenesis of TSE? Med Hypotheses 2001; 57:29-45. [PMID: 11421622 DOI: 10.1054/mehy.2001.1305] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
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?
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16
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Hinton MH. Infections and intoxications associated with animal feed and forage which may present a hazard to human health. Vet J 2000; 159:124-38. [PMID: 10712800 DOI: 10.1053/tvjl.1999.0412] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Animal feed or forage may be the source of a limited number of infections for farm animals that could lead to human illness. Likely organisms include Salmonella enterica, Toxoplasma gondii, Trichinella spiralis and possibly the agent of bovine spongiform encephalopathy. The risk to human health from other infectious agents which may contaminate either feed or forage appear to be either negligible, e.g. Bacillus anthracis and Mycobacterium bovis, or non-existent, e.g. Clostridium botulinum toxin and Listeria monocytogenes. Mycotoxins present in animal feed can result in foods of animal origin also containing them. This risk is well recognized but has yet to be quantified accurately and in some instances the risk may be of theoretical rather than practical importance. Pesticides, agricultural and industrial chemicals, heavy metals and radionuclides may pollute animal feed and forages. The methods available for controlling pollution from these sources are well understood from a technical point of view although the effective implementation of controls can be difficult.
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Affiliation(s)
- M H Hinton
- Department of Clinical Veterinary Science, University of Bristol, Langford, North Somerset, BS40 5DT, UK
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Purdey M. Ecosystems supporting clusters of sporadic TSEs demonstrate excesses of the radical-generating divalent cation manganese and deficiencies of antioxidant co factors Cu, Se, Fe, Zn. Does a foreign cation substitution at prion protein's Cu domain initiate TSE? Med Hypotheses 2000; 54:278-306. [PMID: 10790765 DOI: 10.1054/mehy.1999.0836] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Analyses of food chains supporting isolated clusters of sporadic TSEs (CWD in N Colorado, scrapie in Iceland, CJD in Slovakia) demonstrate a consistent 2 1/2+ fold greater concentration of the pro-oxidant divalent cation, manganese (Mn), in relation to normal levels recorded in adjoining TSE-free localities. Deficiencies of the antioxidant co factors Cu/Se/Zn/Fe and Mg, P and Na were also consistently recorded in TSE foodchains. Similarities between the clinical/pathological profile of TSEs and Mn delayed psycho-neurotoxicity in miners are cited, and a novel theory generated which suggests that sporadic TSE results from early life dependence of TSE susceptible genotypes on ecosystems characterised by this specific pattern of mineral imbalance. Low Cu/Fe induces an excessive absorption of Mn in ruminants and an increased oxidation of Mn2+ into its pro oxidant species, Mn3+, which accumulates in mitochondria of CNS astrocytes in Mn SOD deficient genotypes. Deficiencies of scavenger co factors Cu/Zn/Se/Fe in the CNS permits Mn3+ initiated chain reactions of auto-oxidant mediated neuronal degeneration to proliferate, which, in turn, up-regulates the expression of the Cu-metalloprotein, prion protein (PrP). Once the rate of PrP turnover and its demand for Cu exceeds the already depleted supply of Cu within the CNS, PrP can no longer bind sufficient Cu to maintain its conformation. Mn3+ substitutes at the vacated Cu domain on PrP, thus priming up a latent capacity for lethal auto-oxidative activity to be carried along with PrP like a 'trojan horse'; where Mn 3+ serves as the integral 'infectious' transmissible component of the misfolded PrP-cation complex. The Mn overactivation of concanavalin A binding to glycoprotein and Mn-initiated autoxidation results in a diverse pathological profile involving receptor capping, aggregation/modification of CNS membrane/cytoskeletal proteins. TSE ensues. The BSE/nv CJD strain entails a 'synthetic' induction of the same CNS mineral disturbance, where 'in utero' exposure to Cu-chelating insecticides/Mn supplements accelerates the onset of a more virulent 'strain' of adolescent TSE.
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Affiliation(s)
- M Purdey
- High Barn Farm, Elworthy, Taunton, UK
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Abstract
Misfolded prion protein (PrP) is generally accepted as causing transmissible spongiform encephalopathies (TSEs) by aligning alongside normal host prion protein and inducing it to change to the misfolded configuration. This paper disputes this theory, and proposes that, rather than causing TSEs, misfolded PrP is the result of an autoimmune response to the host PrP, a component both of nerve cells and of lymphocytes. Autoimmunity is initiated by detachment of the phosphotidylinositol glycolipid anchor as a result of exposure to organophosphate pesticides. Once PrP is detached, antibodies are mobilized against it. In some individuals, point mutations, like the codon 129 met-val substitution, have evolved as a self-defence mechanism, causing a change in PrP to the misfolded, protease-resistant form seen in TSEs. Increased PrP production, both in response to nerve damage, and as a component of lymphocytes stimulated to proliferate in response to PrP, produces a positive feedback mechanism, resulting in symptoms of brain destruction.
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