Prion encephalopathy

The conformational plasticity supported by mobile regions within native proteins, partially denatured protein states such as molten globules, and natively unfolded proteins underlies many of the conformational (protein misfolding) diseases (Carrell and Lomas, 1997 Dobson et al., 2001). Many of these diseases involve amyloid fibril formation, as in amyloidosis from mutant human lysozymes, neurodegenerative diseases such as Parkinson s and Alzheimer s due to the hbrillogenic propensities of a -synuclein and tau, and the prion encephalopathies such as scrapie, BSE, and new variant Creutzfeldt-Jacob disease (CJD) where amyloid fibril formation is triggered by exposure to the amyloid form of the prion protein. In addition, aggregation of serine protease inhibitors such as a j-antitrypsin is responsible for diseases such as emphysema and cirrhosis. 

The transmissible spongiform encephalopathies, or prion diseases, are fatal neurodegenerative diseases characterized by spongiform changes, astrocytic gliomas, and neuronal loss resulting from the deposition of insoluble protein aggregates in neural cells. They include Creutzfeldt-Jakob disease in humans, scrapie in... 

Prions—protein particles that lack nucleic acid— cause fatal transmissible spongiform encephalopathies such as Creutzfeldt-Jakob disease, scrapie, and bovine spongiform encephalopathy. Prion diseases involve an altered secondary-tertiary strucmre of a namrally occurring protein, PrPc. When PrPc interacts with its pathologic isoform PrPSc, its conformation is transformed from a predominantly a-helical strucmre to the P-sheet strucmre characteristic of PrPSc. 

The most resistant of all infectious agents to chemical inactivation are the prions, which cause transmissible degenerative encephalopathies. 

Prion diseases resulting in encephalopathy can be transmitted between individuals within species (more rarely between species) [26-28], A conformational variant of the normal cellular protein PrPs (PrPc) (protease-sensitive or cellular) is believed to catalyze [29] or nucleate [30-33] conversion to the pathological form, PrPR (protease-resistant). This highly unusual nongenetic mode of transmission of an infectious agent has been strongly debated [29]. The observation of multiple examples of nucleated catalysis of aberrant polymerization of protein subunits has... 

In addition, the regulatory authorities are concerned about contamination with viruses and prions, such as the causative agent of bovine spongiform encephalopathy (BSE), which could be present in mammalian cell cultures. It is necessary to... 

Suggested Alternatives for Differential Diagnosis Bartonellosis, brucellosis, other causes of encephalitis, coxsackieviruses, cryptococcosis, cysticercosis, cytomegalovirus, histoplasmosis, legionellosis, leptospirosis, listeria, lyme disease, malaria, rabies, tuberculosis, mumps, stroke, metabolic encephalopathy, Reye syndrome, Bartonella infection, Naegleria infection, Ebstein-Barr virus, prion disease, toxic ingestions, and AIDS. 

The prion diseases are a closely related group of neuro-degenerative conditions which affect both humans and animals. They have previously been described as the subacute spongiform encephalopathies, slow virus diseases and transmissible dementias, and include scrapie in sheep, bovine spongiform encephalopathy (BSE) in cattle, and the human prion diseases, Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker disease (GSS), fatal familial insomnia (FFI) and kuru. Prion diseases are... 

Other animal prion diseases. Outbreaks of transmissible mink encephalopathy and chronic wasting disease in captive populations of mink, mule deer and elk in certain regions of the U.S.A. have also been attributed to prion-infected foodstuffs, although the origin of prion infection is unclear [8], Epidemiological studies suggest lateral transmission as the most plausible explanation for the spread of chronic wasting disease in captive populations... 

Fig. 3. Classification of human prion diseases. Sporadic the transformation from PrPc (circle) to PrPSc (square) occurs without apparent cause. Familial a point mutation ( ) is thought to facilitate the transformation. Infectious the transformation arises via PrPSc which acts as a template. The kinetic equations are defined by Eigen (1996). The infectious form includes kuru, iatrogenic CJD (iCJD), variant CJD (vCJD first reported in 1996), bovine spongiform encephalopathy (BSE first reported in 1985), and scrapie. In the nucleation-dependent model, monomeric PrPc and PrPSc are in chemical equilibrium.

Prusiner, S. B. (1991). Molecular biology of prions causing infectious and genetic encephalopathies of humans as well as scrapie of sheep and BSE of cattle. Dev. Biol. Stand. 75, 55-74. 

The normal cellular form of prion protein (PrPc) can exist as a Cu-metalloprotein in vivo (492). This PrPc is a precursor of the pathogenic protease-resistant form PrPsc, which is thought to cause scrapie, bovine spongiform encephalopathy (BSE), and Creutzfeldt—Jakob disease. Two octa-repeats of PHGGGWGQ have been proposed as Cu(II) binding sites centered on histidine (493). They lack secondary and tertiary structure in the absence of Cu(II). Neurons may therefore have special mechanisms to regulate the distribution of copper. 

Pathological conditions are also linked to posttranslational modifications such as oxidized histidine residues found in P-amyloid protein of Alzheimer s patients, or conformational variants in the case of prion-induced encephalopathies. The development of sensitive MS tools and proteomics techniques is playing an active role in the precise description of these mechanisms.97,98... 

Bovine spongiform encephalopathy (BSE or mad cow disease) is a progressive neurological degenerative disease in cattle. It is caused by a mutated protein called a prion. BSE was first reported in the United Kingdom in 1986. Creutzfeldt-Jakob disease (CJD) is a rare disease that occurs in humans. Evidence to date indicates it is possible for humans to acquire CJD after consuming BSE-contaminated cattle products. 

With the background of the mad cow crisis in Europe, questions relating to the prion diseases have attracted intensive interest. It is now widely accepted that prion diseases, such as Creutzfeldt-Jakob disease (CJd) in humans and bovine spongiform encephalopathy (BSE) are caused by a conformational change of the prion protein (PrP) from a normally folded cellular form, PrP ", to an alternate, aggregation-prone, pathogenic scrapie form,... 

Phenotypically, different neurodegenerative disorders, including AD, Parkinson disease, and prion diseases (transmissible spongiform encephalopathies), are... 

Mad cow disease—Bovine spongiform encephalopathy, or BSE, the form of transmissible spongiform encephalopathy (TSE) found in cattle. It is thought to be spread by consumption of brain tissue and caused by proteins called prions. 

Transmissible spongiform encephalopathies (TSEs)—Brain diseases transmitted from one animal to another. Under a microscope, the brain tissue of animals and people with TSEs resembles a sponge. TSEs include variant Creutzfeldt-Jacob disease (vCJD) in humans, scrapie in sheep and goats, and bovine spongiform encephalopathy (BSE) in cows (mad cow disease). These diseases are spread by consumption of brain tissue and are thought to be caused by prions, a kind of protein. 

Because they are derived from cattle, there is a concern that gelatins might be vehicles for the transmission of the prion agent responsible for bovine spongiform encephalopathy (BSE) in cattle and variant Creutzfeldt-Jakob disease (vGD) in humans. There is at present no evidence that these products have contributed to the transmission of BSE or vCJD. However, the incubation period may be up to several years, and due prudence is warranted when such products are used. 

The prion protein (PrP) is an infectious protein that converts noninfectious PrP into the infectious form, which precipitates. PrP is implicated as the causative agent of the transmis sible spongiform encephalopathies, including Creutzfeld-Jakob disease. 

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