Michele Di Bari - Academia.edu (original) (raw)

Papers by Michele Di Bari

PrPSc migration pattern in bank voles. (a) PrPSc extracted from bank voles (Bv109M, 1st passage) ... more PrPSc migration pattern in bank voles. (a) PrPSc extracted from bank voles (Bv109M, 1st passage) inoculated with case #1 (p-CJDMM1 in Bv109M) and case a (np-CJDMM1 in Bv109M) were run in a 7 cm long gel. Membrane was probed with the primary antibody 9A2. Molecular weights are expressed in kDa. (b) Comparison of PrPSc glycoform ratio in bank voles inoculated with case #1 (n = 10) and case a (n = 5). D: diglycosylated, M: monoglycosylated, U: unglycosylated PrPSc. For p-CJDMM1, D = 54.8 ± 8.8; M = 39.1 ± 15.3; U = 6.1 ± 3.0. For np-CJDMM1, D = 54.2 ± 5.2; M = 38.9 ± 3.0; U = 6.9 ± 2.4. Values (mean ± standard deviation) are expressed as a percentage of total PrPSc amount. (TIFF 546 kb)

PrPSc glycoform ratio in p-CJDMM1 and np-CJDMM1. Values represent the percentage (meanâ Âąâ stand... more PrPSc glycoform ratio in p-CJDMM1 and np-CJDMM1. Values represent the percentage (meanâ Âąâ standard deviation) of glycoforms referred to the total PrPSc amount. D: diglycosylated, M: monoglycosylated, U: unglycosylated PrPSc. (DOCX 13 kb)

Relative amounts of PrPSc fragments in samples from p-CJDMM1 and np-CJDMM1. Values represent the ... more Relative amounts of PrPSc fragments in samples from p-CJDMM1 and np-CJDMM1. Values represent the percentage (mean ± standard deviation) of fragments referred to the total PrPSc amount. Differences were not statistically significant (Student's t test). (DOCX 13 kb)

Electrophoretic mobility of PrPSc after PK-digestion and deglycosylation in p-CJDMM1/MM1â +â 2C a... more Electrophoretic mobility of PrPSc after PK-digestion and deglycosylation in p-CJDMM1/MM1â +â 2C and np-CJDMM1 samples. PrPSc bands were resolved in 7Â cm long gels and probed with the primary antibody SAF60. Relative molecular masses are expressed in kDa. (TIFF 368 kb)

Semi-quantitative evaluation of gray matter spongiform change and astrocytosis. Each lesion was s... more Semi-quantitative evaluation of gray matter spongiform change and astrocytosis. Each lesion was scored semi-quantitatively using a 0â 3 scale (0, absence of significant spongiosis or astrocytosis, + mild, ++ moderate, and +++ severe spongiosis or astrocytosis; SS, status spongiosus, F, focal). F-CTX, frontal cortex; T-CTX; temporal cortex; O-CTX, occipital cortex, HIPP-CA1, hippocampus-cornu ammonis 1; STR, striatum; THAL, thalamus; CRBL, cerebellum. *Atrophic molecular layer. In the cerebellum, lesions were evaluated in the molecular layer. (DOCX 15 kb)

Western blot analysis of np-CJDMM1 and p-CJDMM1 (case #1) subcortical white matter. FC: frontal c... more Western blot analysis of np-CJDMM1 and p-CJDMM1 (case #1) subcortical white matter. FC: frontal cortex; PC: parietal cortex. (a) Electrophoretic mobility of PK-digested PrPSc (i.e. PrP27–30) after separation in a 7 cm long gel. Blot was probed with the primary antibody 3F4. (b) CTF13 analysis after PrP deglycosylation with PNGase F. Blot was probed with the primary antibody SAF60. Relative molecular masses are expressed in kDa. Percentages (mean ± standard deviation) of CTF13 are referred to the total PrPSc amount: np-CJDMM1 = 12.8 ± 5.0, p-CJDMM1 = 14.1 ± 2.9. (TIFF 824 kb)

Statistics and demography, the legacy of Corrado Gini, 2015

We report on a hybrid approach to analyze a dataset derived from an experimental study on prion d... more We report on a hybrid approach to analyze a dataset derived from an experimental study on prion diseases conducted at the Istituto Superiore di Sanita`. The data comes from inoculating different strains (inocula) of the disease to bank voles. The aim of the research is to understand at what extent some phenotypic outcomes such as survival times and profiles of brain lesions are able to detect the underlying heterogeneous multi-level origin of the data. We use first an ensemble of hierarchical clustering through the Gower index, a general coefficient that includes similarity for different metrics in the dataset (quantitative and ordinal data). We have verified the ability of the proposed approach to match some preliminary knowledge on the underlying group structure with some possible hint at detecting a slightly finer struc ture. We then consider alternative classifiers with the aim of validating alternative clustering structures and predict whether a new observation belongs to a gro...

Journal of General Virology, 2008

Archives of Neurology, 2007

of Further characterisation of transmissible spongiform encephalopathy phenotypes after inoculati... more of Further characterisation of transmissible spongiform encephalopathy phenotypes after inoculation of cattle with two temporally separated sources of sheep scrapie from Great Britain

Additional file 1: Summary of original experiment. This document gives an overview of the inocula... more Additional file 1: Summary of original experiment. This document gives an overview of the inoculations carried out in cattle and wild-type mice with references to the animal numbers in the original, published study [2].

Although proteinacious in nature, prions exist as strains with specific self-perpetuating biologi... more Although proteinacious in nature, prions exist as strains with specific self-perpetuating biological properties. Prion strains are thought to be associated with different conformers of PrP Sc, a disease-associated isoform of the host-encoded cellular protein (PrP C). Molecular strain typing approaches have been developed which rely on the characterization of proteaseresistant PrP Sc. However, PrP Sc is composed not only of protease-resistant but also of protease-sensitive isoforms. The aim of this work was to develop a protocol for the molecular characterization of both, protease-resistant and protease-sensitive PrP Sc aggregates. We first set up experimental conditions which allowed the most advantageous separation of PrP C and PrP Sc by means of differential centrifugation. The conformational solubility and stability assay (CSSA) was then developed by measuring PrP Sc solubility as a function of increased exposure to GdnHCl. Brain homogenates from voles infected with human and she...

Proceedings of the National Academy of Sciences

Chronic wasting disease (CWD) is a relentless epidemic disorder caused by infectious prions that ... more Chronic wasting disease (CWD) is a relentless epidemic disorder caused by infectious prions that threatens the survival of cervid populations and raises increasing public health concerns in North America. In Europe, CWD was detected for the first time in wild Norwegian reindeer (Rangifer tarandus) and moose (Alces alces) in 2016. In this study, we aimed at comparing the strain properties of CWD prions derived from different cervid species in Norway and North America. Using a classical strain typing approach involving transmission and adaptation to bank voles (Myodes glareolus), we found that prions causing CWD in Norway induced incubation times, neuropathology, regional deposition of misfolded prion protein aggregates in the brain, and size of their protease-resistant core, different from those that characterize North American CWD. These findings show that CWD prion strains affecting Norwegian cervids are distinct from those found in North America, implying that the highly contagiou...

Magnetic Resonance Insights

Background and Purpose Transmissible spongiform encephalopathy (TSE) diseases are fatal, progress... more Background and Purpose Transmissible spongiform encephalopathy (TSE) diseases are fatal, progressive neurodegenerative disorders affecting both humans and animals. Clinical signs typically appear after years and even decades of silent disease progression. This study was aimed at investigating whether altered brain MRI patterns may precede clinical signs in a TSE rodent model. Methods In vivo T2-weighted (T2W) MRI examinations (4.7 T) were performed on Golden Syrian hamsters (GSH) intracerebrally, orally, or intraperitoneally (i.p.) infected with the 263K scrapie strain. Histopathological analyses were performed on i.p. infected GSH at the end of one-day or longitudinal MRI sessions. Results T2W-MRI hyperintensity was detected in the thalamic nuclei of GSH with clinical signs, irrespective of the infection route. Hyperintensity in the thalamus was also observed in pre-clinical animals, between 106 and 121 days post-infection (dpi), while normal T2W intensity was detected in four anim...

Acta Neuropathologica Communications

Amyloid plaques formed by abnormal prion protein (PrP Sc) aggregates occur with low frequency in ... more Amyloid plaques formed by abnormal prion protein (PrP Sc) aggregates occur with low frequency in Creutzfeldt-Jakob disease, but represent a pathological hallmark of three relatively rare disease histotypes, namely variant CJD, sporadic CJDMV2K (methionine/valine at PRNP codon 129, PrP Sc type 2 and kuru-type amyloid plaques) and iatrogenic CJDMMiK (MM at codon 129, PrP Sc of intermediate type and kuru plaques). According to recent studies, however, PrP-amyloid plaques involving the subcortical and deep nuclei white matter may also rarely occur in CJDMM1 (MM at codon 129 and PrP Sc type 1), the most common CJD histotype. To further characterize the phenotype of atypical CJDMM1 with white matter plaques (p-CJDMM1) and unravel the basis of amyloid plaque formation in such cases, we compared clinical and histopathological features and PrP Sc physicochemical properties between 5 p-CJDMM1 and 8 typical CJDMM1 brains lacking plaques. Furthermore, transmission properties after bioassay in two genetic lines of bank voles were also explored in the two groups. All 5 p-CJDMM1 cases had a disease duration longer than one year. Three cases were classified as sporadic CJDMM1, one as sporadic CJDMM1 + 2C and one as genetic CJDE200K-MM1. Molecular mass, protease sensitivity and thermosolubilization of PrP Sc aggregates did not differ between p-CJDMM1 and classical CJDMM1 cases. Likewise, transmission properties such as incubation time, lesion profile and PrP Sc properties in bank voles also matched in the two groups. The present data further define the clinical-pathologic phenotype of p-CJDMM1, definitely establish it as a distinctive CJD histotype and demonstrate that PrP-plaque formation in this histotype is not a strain-specific feature. Since cases lacking amyloid plaques may also manifest a prolonged (i.e. > than one year) disease course, unidentified, host-specific factors likely play a significant role, in addition to disease duration, in generating white matter PrP-amyloid plaques in p-CJDMM1.

Acta neuropathologica, 2017

Prion diseases are caused by a misfolding of the cellular prion protein (PrP) to a pathogenic iso... more Prion diseases are caused by a misfolding of the cellular prion protein (PrP) to a pathogenic isoform named PrP(Sc). Prions exist as strains, which are characterized by specific pathological and biochemical properties likely encoded in the three-dimensional structure of PrP(Sc). However, whether cofactors determine these different PrP(Sc) conformations and how this relates to their specific biological properties is largely unknown. To understand how different cofactors modulate prion strain generation and selection, Protein Misfolding Cyclic Amplification was used to create a diversity of infectious recombinant prion strains by propagation in the presence of brain homogenate. Brain homogenate is known to contain these mentioned cofactors, whose identity is only partially known, and which facilitate conversion of PrP(C) to PrP(Sc). We thus obtained a mix of distinguishable infectious prion strains. Subsequently, we replaced brain homogenate, by different polyanionic cofactors that we...

Journal of virology, Jun 1, 2017

In 2007, we reported a patient with an atypical form of Creutzfeldt-Jakob disease (CJD) heterozyg... more In 2007, we reported a patient with an atypical form of Creutzfeldt-Jakob disease (CJD) heterozygous for methionine-valine (MV) at codon 129 who showed a novel pathological prion protein (PrP(TSE)) conformation with an atypical glycoform (AG) profile and intraneuronal PrP deposition. In the present study, we further characterize the conformational properties of this pathological prion protein (PrP(TSE) MV(AG)), showing that PrP(TSE) MV(AG) is composed of multiple conformers with biochemical properties distinct from those of PrP(TSE) type 1 and type 2 of MV sporadic CJD (sCJD). Experimental transmission of CJD-MV(AG) to bank voles and gene-targeted transgenic mice carrying the human prion protein gene (TgHu mice) showed unique transmission rates, survival times, neuropathological changes, PrP(TSE) deposition patterns, and PrP(TSE) glycotypes that are distinct from those of sCJD-MV1 and sCJD-MV2. These biochemical and experimental data suggest the presence of a novel prion strain in C...

Scientific Reports, 2017

Fatal Familial Insomnia (FFI) is a genetic prion disease caused by a point mutation in the prion ... more Fatal Familial Insomnia (FFI) is a genetic prion disease caused by a point mutation in the prion protein gene (PRNP) characterized by prominent thalamic atrophy, diffuse astrogliosis and moderate deposition of PrP Sc in the brain. Here, for the first time, we demonstrate that the olfactory mucosa (OM) of patients with FFI contains trace amount of PrP Sc detectable by PMCA and RT-QuIC. Quantitative PMCA analysis estimated a PrP Sc concentration of about 1 × 10 −14 g/ml. In contrast, PrP Sc was not detected in OM samples from healthy controls and patients affected by other neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease and frontotemporal dementia. These results indicate that the detection limit of these assays is in the order of a single PrP Sc oligomer/ molecule with a specificity of 100%.

Prion, 2016

Prion diseases, or transmissible spongiform encephalopathies, have revealed the bewildering pheno... more Prion diseases, or transmissible spongiform encephalopathies, have revealed the bewildering phenomenon of transmissibility in neurodegenerative diseases. Hence, the experimental transmissibility of prion-like neurodegenerative diseases via template directed misfolding has become the focus of intense research. Gerstmann-Str€ aussler-Scheinker disease (GSS) is an inherited prion disease associated with mutations in the prion protein gene. However, with the exception of a few GSS cases with P102L mutation characterized by co-accumulation of protease-resistant PrP core (PrP res) of »21 kDa, attempts to transmit to rodents GSS associated to atypical misfolded prion protein with »8 kDa PrP res have been unsuccessful. As a result, these GSS subtypes have often been considered as non-transmissible proteinopathies rather than true prion diseases. In a recent study we inoculated bank voles with GSS cases associated with P102L, A117V and F198S mutations and found that they transmitted efficiently and produced distinct pathological phenotypes, irrespective of the presence of 21 kDa PrP res in the inoculum. This study demonstrates that GSS is a genuine prion disease characterized by both transmissibility and strain variation. We discuss the implications of these findings for the