New Antibody-Free Mass Spectrometry-Based Quantification Reveals That C9ORF72 Long Protein Isoform Is Reduced in the Frontal Cortex of Hexanucleotide-Repeat Expansion Carriers

Frontotemporal dementia (FTD) is a fatal neurodegenerative disease characterized by behavioral and language disorders. The main genetic cause of FTD is an intronic hexanucleotide repeat expansion (G4C2)n in the C9ORF72 gene. A loss of function of the C9ORF72 protein associated with the allele-specific reduction of C9ORF72 expression is postulated to contribute to the disease pathogenesis. To better understand the contribution of the loss of function to the disease mechanism, we need to determine precisely the level of reduction in C9ORF72 long and short isoforms in brain tissue from patients with C9ORF72 mutations. In this study, we developed a sensitive and robust mass spectrometry (MS) method for quantifying C9ORF72 isoform levels in human brain tissue without requiring antibody or affinity reagent. An optimized workflow based on surfactant-aided protein extraction and pellet digestion was established for optimal recovery of the two isoforms in brain samples. Signature peptides, common or specific to the isoforms, were targeted in brain extracts by multiplex MS through the parallel reaction monitoring mode on a Quadrupole–Orbitrap high resolution mass spectrometer. The assay was successfully validated and subsequently applied to frontal cortex brain samples from a cohort of FTD patients with C9ORF72 mutations and neurologically normal controls without mutations. We showed that the C9ORF72 short isoform in the frontal cortices is below detection threshold in all tested individuals and the C9ORF72 long isoform is significantly decreased in C9ORF72 mutation carriers

Control of the Illegal Administration of Natural Steroid Hormones in the Plasma of Bulls and Heifers

In the context of the control of the illegal administration of natural steroid hormones in cattle husbandry, an attempt was made to establish the decision levels for sex steroid hormones in the plasma of adult cattle, taking into account the effect of the treatment. Bulls and heifers were treated with two injections, at a two week interval, of an estradiol-testosterone cocktail. Steroid hormone and biochemical precursor concentrations were measured in plasma samples by using specific radioimmunoassays, before and after the treatment. When the treatment significantly (p < 0.05) modified a hormone concentration, a decision level was established for that hormone concentration. At each decision level, a score was assigned that represented the percentage of treated animals detected when the decision limit was applied. For heifers, 17 beta-estradiol and testosterone concentrations in plasma, which increased after the treatment, are the best criteria to use to detect treated animals, with decision limits of 20 pg ml-1 and 125 pg ml-1, respectively. In the instance of bulls, both testosterone and steroid biochemical precursor concentrations decreased in the plasma after the treatment. We proposed decision limits of 1500 pg ml-1 and 28 pg ml-1 for testosterone and androstenedione concentrations, respectively, the bulls displaying concentrations below these limits being positive. We observed that the repetition of the injection increased the score of the decision limit. The scores for testosterone are 70%, 14d after the first injection and 100% 14 d after the second injection, and for androstenedione, these scores are 60 and 100%, respectively

Mise au point d'une antenne IRM 11.7T pour l'imagerie directe de coupes histologiques

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Lipidomique - Neuroinflammation - Alzheimer : Lipidomique Localisée de Cerveaux de Patients atteints de la Maladie d'Alzheimer en Imagerie par Spectrométrie de Masse

"poster" de soumission pour une évaluation par l'AERESEvaluation du 4 mai 2009 par l'AERES, équipe LAPREVOT

Mise au point d'une antenne IRM 11.7T pour l'imagerie directe de coupes histologiques

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FE65 in Alzheimer's disease: neuronal distribution and association with neurofibrillary tangles.

International audienceFE65, a protein expressed in the nervous system, has the ability to bind the C-terminal domain of the amyloid precursor protein. This suggests a role for FE65 in the pathogenesis of Alzheimer's disease (AD). The present study was conducted to find out if the distribution of FE65 immunoreactivity was affected during the course of AD, and to determine the degree of co-localization of FE65 with other proteins known to be involved in AD. Single immunoperoxidase-labeling experiments, conducted on six sporadic AD patients and six nondemented age-matched controls, showed that the proportion of volume occupied by FE65 immunoreactivity was not modified in the isocortex of AD patients. However, in hippocampal area CA4, increased FE65 immunoreactivity seemed to be associated with the severity of the disease. Double-immunofluorescent labeling did not show any clear co-localization of FE65 with the amyloid precursor protein. FE65 immunoreactivity was also absent from focal and diffuse deposits of the beta-amyloid peptide. Unexpectedly double labeling experiments showed a co-localization of FE65 and tau proteins in intracellular tangles. Ultrastructural observations confirmed that FE65 was associated with paired helical filaments

Heterogeneity of Alzheimer’s disease: Insight from a novel mouse model of amyloid and tau lesions based on the inoculation of human brain preparations

International audienceBackground: A major challenge in clinical research is to better understand the heterogeneity of AD. Indeed, AD is heterogeneous regarding its origin, neuropathology and clinical expressions. While classical sporadic forms of AD (clAD) evolve over approximately 10 years, the "rapidly progressive form of AD" (rAD) is a non-genetic aggressive form associated with a rapid clinical decline that evolves over approximately 2 years (Schmidt et al., Arch Neurol. 2011). Several studies have shown that the experimental inoculation of brain samples with Aβ- and/or tau pathology into transgenic (tg) mouse models overexpressing mutant human APP or tau promotes either Aβ or tau aggregation in the brain of the recipient animal (Gary et al., Acta Neuropathol Com. 2019). The phenotype of the inoculated brains is moreover reproduced in the recipient host (Watts et al., PNAS. 2014). The aim of this work was to study the impact of the inoculations of rAD versus clAD-human brain preparations in tg mice mouse models of β-amyloidosis to explore the mechanisms associated to AD heterogeneity