Does an ultra violet photooxidation of the manganese-loaded/copper-depleted prion protein in the retina initiate the pathogenesis of TSE?

Electronic properties of a PrPC-Cu(ii) complex as a marker of 5-fold Cu(ii) coordination

Human prion protein is a subject of extensive study, related in particular to the molecular basis of neurodegenerative disease development and prevention. This protein has two main domains: the membrane C-terminal, structured domain as well as the unstructured N-terminal domain. While PrPC (23-231) has up to eight Cu(ii) binding sites in the N-terminal domain, it includes a characteristic, conservative octarepeat region PHGGGWGQ, which was studied by means of X-ray absorption near edge spectroscopy. The measurements were conducted at the SuperXAS beamline (SLS, PSI, Villigen). For the initial 1 : 1 protein-to-Cu(ii) ratio, the two main Cu(ii) binding modes were identified using linear combination fitting and ab initio FEFF calculations for X-ray spectra. Their electronic structures indicated that Cu(ii) coordinated by strong π-donors could effectively suppress the pre-edge structure due to the filling of empty Cu(ii) d-states. The suppression was correlated with the charge transfer effect and filling of the virtual electronic Cu(ii) states. What is more, we showed that the 1s → 4p + LMCT (Ligand-to-Metal-Charge-Transfer) multielectron transition relation with the main edge transition could be used as a marker for preliminary comparison of an unknown organic compound to a reference. The presented results permitted a possible explanation of the mechanism of choosing the preferred Cu(ii) modes in PrPC-Cu(ii) coordination processes and of the complex stability from the electronic point of view.

Bovine spongiform encephalopathy (BSE) cases born after the total feed ban

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.

Activating transcription factor 3 (ATF3) expression in the neural retina and optic nerve of zebrafish during optic nerve regeneration

Fish, unlike mammals, can regenerate axons in the optic nerve following optic nerve injury. We hypothesized that using microarray analysis to compare gene expression in fish which had experienced optic nerve lesion to fish which had undergone a similar operation but without optic nerve injury would reveal genes specifically involved in responding to optic nerve injury (including repair), reducing detection of genes involved in the general stress and inflammatory responses. We discovered 120 genes were significantly (minimally two-fold with a P-value < or = 0.05) differentially expressed (up or down) at one or more time point. Among these was ATF3, a member of the cAMP-response element binding protein family. Work by others has indicated that elevated cAMP could be important in axon regeneration. We investigated ATF3 expression further by qRT-PCR, in situ hybridization and immunohistochemistry and found ATF3 expression is significantly upregulated in the ganglion cell layer of the retina, the nerve fiber layer and the optic nerve of the injured eye. The upregulation in retina is detectable by qRT-PCR by 24 h after injury, at which time ATF-3 mRNA levels are 8-fold higher than in retinas from sham-operated fish. We conclude ATF3 may be an important mediator of optic nerve regeneration-promoting gene expression in fish, a role which merits further investigation.

Manganese enhances prion protein survival in model soils and increases prion infectivity to cells

Prion diseases are considered to be transmissible. The existence of sporadic forms of prion diseases such as scrapie implies an environmental source for the infectious agent. This would suggest that under certain conditions the prion protein, the accepted agent of transmission, can survive in the environment. We have developed a novel technique to extract the prion protein from soil matrices. Previous studies have suggested that environmental manganese is a possible risk factor for prion diseases. We have shown that exposure to manganese is a soil matrix causes a dramatic increase in prion protein survival (∼10 fold) over a two year period. We have also shown that manganese increases infectivity of mouse passaged scrapie to culture cells by 2 logs. These results clearly verify that manganese is a risk factor for both the survival of the infectious agent in the environment and its transmissibility.

The expanding universe of prion diseases

Prions cause fatal and transmissible neurodegenerative disease. These etiological infectious agents are formed in greater part from a misfolded cell-surface protein called PrP(C). Several mammalian species are affected by the diseases, and in the case of "mad cow disease" (BSE) the agent has a tropism for humans, with negative consequences for agribusiness and public health. Unfortunately, the known universe of prion diseases is expanding. At least four novel prion diseases--including human diseases variant Creutzfeldt-Jakob disease (vCJD) and sporadic fatal insomnia (sFI), bovine amyloidotic spongiform encephalopathy (BASE), and Nor98 of sheep--have been identified in the last ten years, and chronic wasting disease (CWD) of North American deer (Odocoileus Specis) and Rocky Mountain elk (Cervus elaphus nelsoni) is undergoing a dramatic spread across North America. While amplification (BSE) and dissemination (CWD, commercial sourcing of cervids from the wild and movement of farmed elk) can be attributed to human activity, the origins of emergent prion diseases cannot always be laid at the door of humankind. Instead, the continued appearance of new outbreaks in the form of "sporadic" disease may be an inevitable outcome in a situation where the replicating pathogen is host-encoded.

Free radical generation of protease-resistant prion after substitution of manganese for copper in bovine brain homogenate

The exchange between copper and seven transition metals is studied in a bovine brain obex homogenate according to the redox status of the medium. In reductive conditions, almost all the studied metals can substitute for copper when it is in the reduced form Cu+. This substitution is reversible, since copper uptake as Cu++ is restored in an oxidizing medium but only Co++, Ni++ and Mn++, in this decreasing order, can substitute perfectly for copper in bovine brain homogenate. To study free radical effects on bovine brain proteins, at first a copper substitution was processed in order to inhibit superoxide dismutase-like protective properties against free radicals in copper metalloproteins. Manganese was selected since a brain copper decrease correlated with a manganese increase is well-known in transmissible spongiform encephalopathies. Results for bovine brain homogenate, initially negative in the Western blot Prionics test, indicate that the substitution of manganese for copper in a reducing medium and exposure to UVA-induced free radicals produce proteinase K resistant prion. These findings suggest that an impairment in brain metal homeostasis leading to oxidative abnormalities may be involved in transmissible spongiform encephalopathies.

[Prion protein and copper: a mysterious relationship]

Prion diseases form a group of fatal neurodegenerative disorders including Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy in animals. All of which are characterized by the accumulation of abnormally folded isoform of the cellular prion protein (PrP(C)), denoted PrP(Sc), which is the major component of infectious prion diseases. The function of PrP(C) remains elusive. Its amino-terminal region contains a repeated five octapeptide domain that binds copper. The protein is believed to display a superoxide dismutase like activity, and hence a possible protective function against oxidative stress. In this review, relationship between PrP, copper and oxidative stress was analysed. Thus, metal ions and oxidative stress would play an essential role in the pathogenesis of prion diseases and represent important targets for future therapeutic targets or a novel diagnostic marker.

Trypanosoma cruzi trans-sialidase as a new therapeutic tool in the treatment of chronic inflammatory diseases: possible action against mycoplasma and chlamydia

The present paper proposes a new therapy using Trypanosoma cruzi trans-sialidase to treat diseases with unclear pathogenesis that present in common chronic inflammation and fibrosis. This hypothesis is based on recent findings that co-infection with mycoplasma and chlamydia is present in many of these diseases and that this enzyme was capable to eliminate or decrease the co-infection from the host. We identified that mycoplasmas and chlamydias are present in atherosclerosis, aortic valve stenosis, dilated cardiomyopathy, chronic chagasic myocarditis and cancer. We hypothetized that mycoplasmal infection may induce immunodepression in the host, favoring proliferation of pre-existent chlamydial infection and that elimination of mycoplasma would lead to improvement of the immune system resistance and the control of chlamydial proliferation. Mycoplasma has a particular parasitic relationship with host cells, involving strong adherence of their membranes, making it extremely difficult to eradicate mycoplasmal infection from the host. A new therapeutic approach is suggested using one or more agents that prevent or inhibit the adherence of mycoplasma to host cell membranes by removing sialic acid residues and preventing oxidation of the cells. The use of a neuraminidase enzyme, particularly the T. cruzi trans-sialidase enzyme, associated with treatment using anti-oxidating agents is proposed. Preliminary experimental animal and laboratory tests showed good results. The proposal that trans-sialidase from T. cruzi is efficient in combating co-infection of mycoplasma and chlamydia is based, at least in part, on the observation that chagasic patients suffering from T. cruzi infection present less mycoplasma and chlamydia infection in their tissues. Also, a lower incidence of the diseases above described to be related to mycoplasma infection is observed in chagasic patients. It is also hypothesized that co-infection with mycoplasma and chlamydia may induce oxidation of the host cells. Anti-oxidants such as those present in plant extracts may also be used in the treatment. Other diseases such as chronic hepatitis, glomerulonephritis, Multiple Sclerosis, Alzheimer's Syndrome and idiopathic encephalitis are other examples of chronic diseases where mycoplasma and chlamydia might be present, as they have the characteristics of unknown etiology, persistent chronic inflammation and fibrosis.

Priorities for mixtures health effects research

In order to better inform scientific decision making in the occupational environment, we need a better understanding of the toxicology of mixed exposures. In particular, we need an understanding of the dose-response relationship from the level of individual or population exposure down to the molecular level (and then back up again from the molecular level to the specific health-related response of the organism as a whole). Mixtures toxicology is proving to be different from single-chemical toxicology in several fundamental but barely recognized ways: Knowledge gained in mixtures research should be able to improve current risk assessment and mitigation or intervention methods. In NIOSH's National Occupational Research Agenda (NORA) three priority areas have been identified:

Does an infrasonic acoustic shock wave resonance of the manganese 3+ loaded/copper depleted prion protein initiate the pathogenesis of TSE?

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.

Copper binding to the octarepeats of the prion protein. Affinity, specificity, folding, and cooperativity: insights from circular dichroism

The prion protein (PrP) is a Cu(2+) binding cell surface glycoprotein. There is increasing evidence that PrP functions as a copper transporter. In addition, strains of prion disease have been linked with copper binding. We present here CD spectroscopic studies of Cu(2+) binding to various fragments of the octarepeat region of the prion protein. We show that glycine and l-histidine will successfully compete for all Cu(2+) ions bound to the PrP octapeptide region, suggesting Cu(2+) coordinates with a lower affinity for PrP than the fm dissociation constant reported previously. We show that each of the octarepeats do not form an isolated Cu(2+) binding motif but fold up cooperatively within multiple repeats. In addition to the coordinating histidine side chain residues, we show that the glycine residues and the proline within each octarepeat are also necessary to maintain the coordination geometry. The highly conserved octarepeat region in mammals is a hexarepeat in birds that also binds copper but with different coordination geometry. Finally, in contrast to other reports, we show that Mn(2+) does not bind to the octarepeat region of PrP.

Transmissible spongiform encephalopathies: a family of etiologically complex diseases--a review

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.

Prion diseases: copper deficiency states associated with impaired nitrogen monoxide or carbon monoxide transduction and translocation

Literature concerning prion diseases and Cu metabolism was examined to determine merits of various suggestions concerning the relationship between these diseases and altered Cu metabolism. There are a number of recent suggestions that the normal non-pathogenic form of the prion protein (PrP(C)) contains Cu while the abnormal pathogenic form of this protein, PrP(SC), lacks Cu. Results of experiments showing oxidant sensitivity in the presence of ionically bonded Cu and millimolar concentrations of hydrogen peroxide were found to lack relevance. Demonstrating superoxide disproportionation and a correlation with cellular Cu2Zn2SOD activity is relevant and consistent with a role for PrP(C) in Cu endocytosis. There are also a number of recent suggestions that PrP(C) has a role in nerve transmission. Serum from mice that lack cellular PrP(C) was found to have an elevated Cu content consistent with a response to overcome an inflammatory disease. Attempts to induce a 'transmissible' form of prion disease requiring intracerebral injections of somewhat purified brain homogenates were found lacking in support for an etiology occurring as the result of oral ingestion of supposedly 'infected' tissues. It is suggested that PrP(C) is a normal Cu-dependent cuproglycoprotein of unknown function that may have a role in facilitating normal nitrogen monoxide- or carbon monoxide-mediated biochemistry.