Prion disease is a neurodegenerative malady, which is believed to be transmitted via a prion protein in its abnormal conformation (PrP
Sc
). Previous studies have failed to demonstrate that prion ...disease could be induced in wild-type animals using recombinant prion protein (rPrP) produced in
Escherichia coli
. Here, we report that prion infectivity was generated in Syrian hamsters after inoculating full-length rPrP that had been converted into the cross-β-sheet amyloid form and subjected to annealing. Serial transmission gave rise to a disease phenotype with highly unique clinical and neuropathological features. Among them were the deposition of large PrP
Sc
plaques in subpial and subependymal areas in brain and spinal cord, very minor lesioning of the hippocampus and cerebellum, and a very slow progression of disease after onset of clinical signs despite the accumulation of large amounts of PrP
Sc
in the brain. The length of the clinical duration is more typical of human and large animal prion diseases, than those of rodents. Our studies establish that transmissible prion disease can be induced in wild-type animals by inoculation of rPrP and introduce a valuable new model of prion diseases.
The article gives a survey of the problematics, historic and cultural practice of maintaining and developing the ethnic languages of Russia through translation; it retrospectively describes the ...history of polycultural co-existence (including the unified method of presentation for childrens folk lore in S. Marshaks version) and outlines the ways of dealing with todays urgent problems of preserving ethnic language. The article describes the models of reconstructing the lost texts and the strategies of translating the texts of small ethnic groups, as well as the models of maintaining the quality of translation from Russias ethnic languages into Russian. We especially stress the importance of the Russian language in its role of the cultural mediator. The article pays due attention to the need to develop specific practiceoriented theories of translation which would embrace the global experience in translatology and take into account the specificity of ethno-centric mentality and the ways to keep it in translation. The article is an introduction to the following materials in the volume.
The transmissible agent of prion disease consists of a prion protein in its abnormal, β-sheet rich state (PrP(Sc)), which is capable of replicating itself according to the template-assisted ...mechanism. This mechanism postulates that the folding pattern of a newly recruited polypeptide chain accurately reproduces that of a PrP(Sc) template. Here we report that authentic PrP(Sc) and transmissible prion disease can be generated de novo in wild type animals by recombinant PrP (rPrP) amyloid fibrils, which are structurally different from PrP(Sc) and lack any detectable PrP(Sc) particles. When induced by rPrP fibrils, a long silent stage that involved two serial passages preceded development of the clinical disease. Once emerged, the prion disease was characterized by unique clinical, neuropathological, and biochemical features. The long silent stage to the disease was accompanied by significant transformation in neuropathological properties and biochemical features of the proteinase K-resistant PrP material (PrPres) before authentic PrP(Sc) evolved. The current work illustrates that transmissible prion diseases can be induced by PrP structures different from that of authentic PrP(Sc) and suggests that a new mechanism different from the classical templating exists. This new mechanism designated as "deformed templating" postulates that a change in the PrP folding pattern from the one present in rPrP fibrils to an alternative specific for PrP(Sc) can occur. The current work provides important new insight into the mechanisms underlying genesis of the transmissible protein states and has numerous implications for understanding the etiology of neurodegenerative diseases.
Protein misfolding cyclic amplification (PMCA) provides faithful replication of mammalian prions in vitro and has numerous applications in prion research. However, the low efficiency of conversion of ...PrP(C) into PrP(Sc) in PMCA limits the applicability of PMCA for many uses including structural studies of infectious prions. It also implies that only a small sub-fraction of PrP(C) may be available for conversion. Here we show that the yield, rate, and robustness of prion conversion and the sensitivity of prion detection are significantly improved by a simple modification of the PMCA format. Conducting PMCA reactions in the presence of Teflon beads (PMCAb) increased the conversion of PrP(C) into PrP(Sc) from ∼10% to up to 100%. In PMCAb, a single 24-hour round consistently amplified PrP(Sc) by 600-700-fold. Furthermore, the sensitivity of prion detection in one round (24 hours) increased by 2-3 orders of magnitude. Using serial PMCAb, a 10¹²-fold dilution of scrapie brain material could be amplified to the level detectible by Western blotting in 3 rounds (72 hours). The improvements in amplification efficiency were observed for the commonly used hamster 263K strain and for the synthetic strain SSLOW that otherwise amplifies poorly in PMCA. The increase in the amplification efficiency did not come at the expense of prion replication specificity. The current study demonstrates that poor conversion efficiencies observed previously have not been due to the scarcity of a sub-fraction of PrP(C) susceptible to conversion nor due to limited concentrations of essential cellular cofactors required for conversion. The new PMCAb format offers immediate practical benefits and opens new avenues for developing fast ultrasensitive assays and for producing abundant quantities of PrP(Sc)in vitro.
Bioassay by end-point dilution has been used for decades for routine determination of prion infectivity titre. Here we show that the new protein misfolding cyclic amplification with beads (PMCAb) ...technique can be used to estimate titres of the infection-specific forms of the prion protein with a higher level of precision and in 3-6 days as opposed to 2 years, when compared with the bioassay. For two hamster strains, 263 K and SSLOW, the median reactive doses determined by PCMAb (PMCAb(50)) were found to be 10(12.8) and 10(12.2) per gram of brain tissue, which are 160- and 4,000-fold higher than the corresponding median infectious dose (ID(50)) values measured by bioassay. The 10(2)- to 10(3)-fold differences between ID(50) and PMCAb(50) values could be due to a large excess of PMCAb-reactive prion protein seeds with little or no infectivity. Alternatively, the differences between ID(50) and PMCAb(50) could be due to higher rate of clearance of infection-specific prion protein seeds in animals versus PMCAb reactions. A well-calibrated PMCAb reaction can be an efficient and cost-effective method for the estimation of infection-specific prion protein titre.
Today the criteria for evaluating translations of literary texts combine vast practical experience, insights of the translation theory and the demands set by the contemporary society for the ...translation of literature. The article describes the stages of developing literary translation criteria and offers the integrative multicomponent model which comprises aesthetic information, text unity, dominant style features and their frequency, diachronic distance, translator’s individual style, literary norm of the receiving language and specificity of the social expectations. The above-listed components are considered crucial in the analysis of the present-day and past translations, as well as in the study of two-step translation method via the mediating language.
The route of transmission of most naturally acquired transmissible spongiform encephalopathy (TSE) infections remains speculative. To investigate urine as a potential source of TSE exposure, we used ...a sensitive method for detection and quantitation of TSE infectivity. Pooled urine collected from 22 hamsters showing clinical signs of 263K scrapie contained 3.8 +/- 0.9 infectious doses/mL of infectivity. Titration of homogenates of kidneys and urinary bladders from the same animals gave concentrations 20,000-fold greater. Histologic and immunohistochemical examination of these same tissues showed no indications of inflammatory or other pathologic changes except for occasional deposits of disease-associated prion protein in kidneys. Although the source of TSE infectivity in urine remains unresolved, these results establish that TSE infectivity is excreted in urine and may thereby play a role in the horizontal transmission of natural TSEs. The results also indicate potential risk for TSE transmission from human urine-derived hormones and other medicines.
Spiroplasma spp. have been proposed to be the etiological agents of the transmissible spongiform encephalopathies (TSEs). In a blind study, a panel of 20 DNA samples was prepared from the brains of ...uninfected hamsters or hamsters infected with the 263K strain of scrapie. The brains of the infected hamsters contained >/=10¹⁰ infectious doses/g. The coded panel was searched for bacterial 16S rRNA gene sequences, using primers selective for spiroplasma sequences, primers selective for mollicutes in general, and universal bacterial primers. After 35 PCR cycles, no samples were positive for spiroplasma or any other bacterial DNA, while control Spiroplasma mirum genomic DNA, spiked at 1% of the concentration required to account for the scrapie infectivity present, was readily detected. After 70 PCR cycles, nearly all samples yielded amplified products which were homologous to various bacterial 16S rRNA gene sequences, including those of frequent environmental contaminants. These sequences were seen in uninfected as well as infected samples. Because the concentration of scrapie infectivity was at a known high level, it is very unlikely that a bacterial infection at the same concentration could have escaped detection. We conclude that the infectious agent responsible for TSE disease cannot be a spiroplasma or any other eubacterial species.
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