Browsing by Subject "Prion diseases"

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    Current concepts in human prion protein (Prp) misfolding, Prnp gene polymorphisms and their contribution to Creutzfeldt-Jakob Disease (CJD)
    (Murcia : F. Hernández, 2007) Michalczyk, K.; Ziman, M.
    Transmissible spongiform encephalopathies are a group of neural degenerative diseases that may be infectious, sporadic, or hereditary and are associated with an abnormally folded prion protein. Unfortunately at the current time it is not at all clear what the normal structure of the prion protein actually is or how it is toxic to cells. Extensive research on prion diseases has led to a dramatic increase in understanding of the pathogenesis of prion disorders, which will hopefully lead to the development of effective treatments. The inability to detect the disease in blood using current technology has made screening difficult. While fortunately there has been a decline in the number of clinical cases of transmissible variant CJD, evidence indicates that very long incubation periods can occur in humans so there may be a long slow, gradual epidemic. In particular, clinical cases in genotypes other than those homozygous for methionine at codon 129 of PRNP have not yet occurred, but such cases might be expected to have longer incubation periods and show differences in pathology to those seen to date. proportion of infected animals develop sub-clinical disease. Moreover, results from a large prevalence study in humans show that several cases test positive but do not develop clinical disease. It is possible therefore that further cases of secondary transmission could occur by iatrogenic spread, which could result in vCJD persisting in the UK at low levels for many years, highlighting the importance of continued vigilance.
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    Human and animal spongiform encephalopathies are the result of chronic autoimmune attack in the CNS: A novel medical theory supported by overwhelming experimental evidence
    (Murcia : F. Hernández, 2005) Ting Zhu, Bao
    Spongiform encephalopathies, also called "prion diseases", are fatal degenerative diseases of the central nervous system which can occur in animals (such as the "mad cow disease" in cattle) and also in humans. This paper presents a novel medical theory concerning the pathogenic mechanisms for various human and animal spongiform encephalopathies. It is hypothesized that various forms of prion diseases are essentially autoimmune diseases, resulting from chronic autoimmune attack of the central nervous system. A key step in the pathogenic process leading towards the development of spongiform encephalopathies involves the production of specific autoimmune antibodies against the disease-causing prion protein (PrPsc) and possibly other immunogenic macromolecules present in the brain. As precisely explained in this paper, the autoimmune antibodies produced against PrPsc are responsible for the conversion of the normal cellular prion protein (PrPc) to PrPsc, for the accumulation of PrPsc in the brain and other peripheral tissues, and also for the initiation of an antibody-mediated chronic autoimmune attack of the central nervous system neurons, which would contribute to the development of characteristic pathological changes and clinical symptoms associated with spongiform encephalopathies. The validity and correctness of the proposed theory is supported by an overwhelming body of experimental observations that are scattered in the biomedical literature. In addition, the theory also offers practical new strategies for early diagnosis, treatment, and prevention of various human and animal prion diseases.
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    Molecular clues to pathogenesis in prion diseases
    (Murcia : F. Hernández, 1997) Laurent, M.; Johannin, G.
    The infectious agent of the transmissible spongiform encephalopathies (TSE) resembles a virus in that it propagates in vivo and has distinct strains. However, compelling evidence strongly suggests that a posttranslational structural alteration in a glycoprotein P ~ PC(t he normal, cellular isoform of the so-called prion protein) is responsible for pathogenesis of these diseases. According to this hypothesis - now close to being generally accepted -, iatrogen, sporadic and familia1 forms of TSE would have the same molecular mechanism: the conversion of PrPC into a proteaseresistant isoform prPSc kinetically behaves as an autocatalytic process which, combined with the high turnover rate of the normal isoform, may endow the system with bistability properties and subsequent threshold behavior between normal and pathogenic steady-states. Normal prion protein seems to be necessary for long-term survival of Purkinje neurons, regulation of circadian rhythms and, more controversially, for normal synaptic function. At least part of the pathology might be due to the unavailability of normal isoform rather than to the accumulation of PrPSc. NMR structure of the normal mouse prion protein reveals a short, unexpected B-sheet which might be a nucleation site for the conformational transition between P ~ PCa nd P~PSCP.r ion diseases may challenge the edged distinction that we use to make between informational (DNA) and functional (proteins) macromolecules. Pathogenic mechanism of prions might also be involved in other proteins to achieve and pass on their conformation. Hence, structural inheritance at the molecular leve1 might be the missing link for the understanding of the structural inheritance processes featured at the cellular level. Moreover, evolutionary paradigm postulating a primitive RNA world is weakened by the mechanism of prion diseases.