Objective The objective of the study is to report 2 new genotypic forms of protease-sensitive prionopathy (PSPr), a novel prion disease described in 2008, in 11 subjects all homozygous for valine at codon 129 of the prion protein (PrP) gene (129VV). The 2 new PSPr forms affect individuals who are either homozygous for methionine (129MM) or heterozygous for methionine/valine (129MV). Methods Fifteen affected subjects with 129MM, 129MV, and 129VV underwent comparative evaluation at the National Prion Disease Pathology Surveillance Center for clinical, histopathologic, immunohistochemical, genotypical, and PrP characteristics. Results Disease duration (between 22 and 45 months) was significantly different in the 129VV and 129MV subjects. Most other phenotypic features along with the PrP electrophoretic profile were similar but distinguishable in the 3 129 genotypes. A major difference laid in the sensitivity to protease digestion of the disease-associated PrP, which was high in 129VV but much lower, or altogether lacking, in 129MV and 129MM. This difference prompted the substitution of the original designation with “variably protease-sensitive prionopathy” (VPSPr). None of the subjects had mutations in the PrP gene coding region. Interpretation Because all 3 129 genotypes are involved, and are associated with distinguishable phenotypes, VPSPr becomes the second sporadic prion protein disease with this feature after Creutzfeldt-Jakob disease, originally reported in 1920. However, the characteristics of the abnormal prion protein suggest that VPSPr is different from typical prion diseases, and perhaps more akin to subtypes of Gerstmann-Sträussler-Scheinker disease.

Objective: To report a novel prion disease characterized by distinct histopathological and immunostaining features, and associated with an abnormal isoform of the prion protein (PrP) that, contrary to the common prion diseases, is predominantly sensitive to protease digestion. Methods: Eleven subjects were investigated at the National Prion Disease Pathology Surveillance Center for clinical, histopathological, immunohistochemical, genotypical, and PrP characteristics. Results: Patients presented with behavioral and psychiatric manifestations on average at 62 years, whereas mean disease duration was 20 months. The type of spongiform degeneration, the PrP immunostaining pattern, and the presence of microplaques distinguished these cases from those with known prion diseases. Typical protease-resistant PrP was undetectable in the cerebral neocortex with standard diagnostic procedures. After enrichment, abnormal PrP was detected at concentrations 16 times lower than common prion diseases; it included nearly 4 times less protease-resistant PrP, which formed a distinct electrophoretic profile. The subjects examined comprised about 3% of sporadic cases evaluated by the National Prion Disease Pathology Surveillance Center. Although several subjects had family histories of dementia, no mutations were found in the PrP gene open reading frame. Interpretation: The distinct histopathological, PrP immunohistochemical, and physicochemical features, together with the homogeneous genotype, indicate that this is a previously unidentified type of disease involving the PrP, which we designated "protease-sensitive prionopathy" (or PSPr). Protease-sensitive prionopathy is not rare among prion diseases, and it may be even more prevalent than our data indicate because protease-sensitive prionopathy cases are likely also to be classified within the group of non-Alzheimer's dementias.

The ever-increasing demands for clean and sustainable energy sources combined with rapid advances in bio-integrated portable or implantable electronic devices have stimulated intensive research activities in enzymatic (bio)fuel cells (EFCs). The use of renewable biocatalysts, the utilization of abundant green, safe, and high energy density fuels, together with the capability of working at modest and biocompatible conditions, make EFCs promising as next generation alternative power sources. However, the main challenges (low energy density, relatively low power density, poor operational stability and limited voltage output) hinder future applications of EFCs. This review aims at exploring the underlying mechanism of EFCs and providing possible practical strategies, methodologies and insights to tackle of these issues. Firstly, this review summarizes approaches in achieving high energy densities in EFCs, particularly, employing enzyme cascades for the deep/complete oxidation of fuels. Secondly, strategies for increasing power densities in EFCs, including increasing enzyme activities, facilitating electron transfers, employing nanomaterials, and designing more efficient enzyme-electrode interfaces, are described. The potential of EFCs/(super)capacitor combination is discussed. Thirdly, the review evaluates a range of strategies for improving the stability of EFCs, including the use of different enzyme immobilization approaches, tuning enzyme properties, designing protective matrixes, and using microbial surface displaying enzymes. Fourthly, approaches for the improvement of the cell voltage of EFCs are highlighted. Finally, future developments and a prospective on EFCs are envisioned.

Aggregated prion protein (PrPSc ), which is detergent-insoluble and partially proteinase K (PK)-resistant, constitutes the major component of infectious prions that cause a group of transmissible spongiform encephalopathies in animals and humans. PrP Sc derives from a detergent-soluble and PK-sensitive cellular prion protein (PrP C ) through an ␣-helix to ␤-sheet transition. This transition confers on the PrP Sc molecule unique physicochemical and biological properties, including insolubility in nondenaturing detergents, an enhanced tendency to form aggregates, resistance to PK digestion, and infectivity, which together are regarded as the basis for distinguishing PrP Sc from PrP C . Here we demonstrate, using sedimentation and size exclusion chromatography, that small amounts of detergent-insoluble PrP aggregates are present in uninfected human brains. Moreover, PK-resistant PrP core fragments are detectable following PK treatment. This is the first study that provides experimental evidence supporting the hypothesis that there might be silent prions lying dormant in normal human brains.

The prion protein (PrP) is best known for its association with prion diseases. However, a controversial new role for PrP in Alzheimer disease (AD) has recently emerged. In vitro studies and mouse models of AD suggest that PrP may be involved in AD pathogenesis through a highly specific interaction with amyloid-␤ (A␤42) oligomers. Immobilized recombinant human PrP (huPrP) also exhibited high affinity and specificity for A␤42 oligomers. Here we report the novel finding that aggregated forms of huPrP and A␤42 are co-purified from AD brain extracts. Moreover, an anti-PrP antibody and an agent that specifically binds to insoluble PrP (iPrP) co-precipitate insoluble A␤ from human AD brain. Finally, using peptide membrane arrays of 99 13-mer peptides that span the entire sequence of mature huPrP, two distinct types of A␤ binding sites on huPrP are identified in vitro. One specifically binds to A␤42 and the other binds to both A␤42 and A␤40. Notably, A␤42-specific binding sites are localized predominantly in the octapeptide repeat region, whereas sites that bind both A␤40 and A␤42 are mainly in the extreme N-terminal or C-terminal domains of PrP. Our study suggests that iPrP is the major PrP species that interacts with insoluble A␤42 in vivo. Although this work indicated the interaction of A␤42 with huPrP in the AD brain, the pathophysiological relevance of the iPrP/A␤42 interaction remains to be established. Alzheimer disease (AD)2 is the leading cause of dementia in the elderly and the most common neurodegenerative disorder. The underlying pathology in AD seems to be associated with the accumulation of soluble and insoluble aggregated species of the amyloid-␤ (A␤) peptide in the brain (1). However, the mechanisms underlying A␤ deposition and neurotoxicity remain poorly understood. The cellular prion protein (PrP C ) is a glycoprotein highly expressed in the brain, and best known for its association with prion diseases. These are unique neurodegenerative disorders with an infectious, sporadic or genetic etiology, and which are characterized by deposition of misfolded, pathological PrP (PrP Sc ) in the brain (2). Interestingly, a recent interpretation of early and newer observations suggests that PrP C may play a role in the pathogenesis of AD (3). Epidemiological studies suggest that the Met/Val polymorphism at residue 129 in PrP modulates the number of A␤ deposits (4). Also, pathological evidence indicates that PrP deposits often accompany A␤ plaques in AD (5-7). Moreover, transgenic mice expressing mutant amyloid precursor protein (APP) and overexpressing hamster PrP C present an exacerbated A␤ plaque burden (8). The circumstantial evidence of an association between PrP and A␤ was greatly strengthened by the recent finding that PrP was the protein that most strongly supported the binding of cells to soluble A␤42 oligomers in a screen of 225,000 murine clones (9). The authors also showed that although A␤42 oligomers suppressed long-term potentiation (LTP) in CA1 hippocampal neurons in mouse brain slices, LTP inhibitio...

A lactate/O enzymatic biofuel cell (EBFC) was prepared as a potential power source for wearable microelectronic devices. Mechanically stable and flexible nanoporous gold (NPG) electrodes were prepared using an electrochemical dealloying method consisting of a pre-anodization process and a subsequent electrochemical cleaning step. Bioanodes were prepared by the electrodeposition of an Os polymer and Pediococcus sp. lactate oxidase onto the NPG electrode. The electrocatalytic response to lactate could be tuned by adjusting the deposition time. Bilirubin oxidase from Myrothecium verrucaria was covalently attached to a diazonium-modified NPG surface. A flexible EBFC was prepared by placing the electrodes between two commercially available contact lenses to avoid direct contact with the eye. When tested in air-equilibrated artificial tear solutions (3 mM lactate), a maximum power density of 1.7 ± 0.1 μW cm and an open-circuit voltage of 380 ± 28 mV were obtained, values slightly lower than those obtained in phosphate buffer solution (2.4 ± 0.2 μW cm and 455 ± 21 mV, respectively). The decrease was mainly attributed to interference from ascorbate. After 5.5 h of operation, the EBFC retained 20% of the initial power output.

The infectious pathogen responsible for prion diseases is the misfolded, aggregated form of the prion protein, PrPSc. In contrast to recent progress in studies of laboratory rodent-adapted prions, current understanding of the molecular basis of human prion diseases and, especially, their vast phenotypic diversity is very limited. Here, we have purified proteinase resistant PrPSc aggregates from two major phenotypes of sporadic Creutzfeldt-Jakob disease (sCJD), determined their conformational stability and replication tempo in vitro, as well as characterized structural organization using recently emerged approaches based on hydrogen/deuterium (H/D) exchange coupled with mass spectrometry. Our data clearly demonstrate that these phenotypically distant prions differ in a major way with regard to their structural organization, both at the level of the polypeptide backbone (as indicated by backbone amide H/D exchange data) as well as the quaternary packing arrangements (as indicated by H/D exchange kinetics for histidine side chains). Furthermore, these data indicate that, in contrast to previous observations on yeast and some murine prion strains, the replication rate of sCJD prions is primarily determined not by conformational stability but by specific structural features that control the growth rate of prion protein aggregates.

Dealloyed nanoporous gold (NPG) is a relatively new class of materials with potential applications in a wide range of fields, especially in electrochemistry. This review describes recent progress in the use of NPG electrodes for applications in bioelectrochemistry. 20