domenica 26 luglio 2015
Follow-up nerve conduction studies in CIDP after treatment with IGIV-C: Comparison of patients with and without subsequent relapse
: Electrodiagnostic studies (EDX) are not performed routinely before treatment suspension in CIDP, and no data exist regarding their value in predicting clinical relapse. : Serial EDX (baseline and after IGIV-C therapy) were analyzed from subjects in the ICE clinical trial who responded to IGIV-C treatment and were subsequently re-randomized to placebo in an extension phase. Comparisons were made between subjects who relapsed and those who did not. : A total of 55% (6/11) of the Relapse group had an increase in total number of demyelinating findings (DF) versus 8% (1/13) in the No Relapse group ( = 0.023). In the Relapse group, 100% had ≥1 new DF and 73% (8/11) had ≥4 new DF versus 60% (8/13) and 8% (1/13), respectively, in the No Relapse group. : An increased total number of DF or the occurrence of ≥4 new DF may indicate a higher risk of clinical relapse after treatment cessation in IGIV-C-responsive patients.
Muscle & Nerve 2015
Muscle & Nerve 2015
Parkinson's disease (PD) is an increasingly prevalent and progressively disabling neurodegenerative disease. The impact of PD on patients and their families as well as its burden on health care systems could be substantially reduced by disease-modifying therapies that slow the rate of neurodegeneration or stop the disease process. Multiple agents have been studied in clinical trials designed to assess disease modification in PD, but all have failed. Over the last 3 years, clinical trials investigating the potential of adeno-associated virus serotype 2 (AAV)-neuturin, coenzyme Q10, creatine, pramipexole, and pioglitazone reported negative findings or futility. Despite these disappointments, progress has been made by expanding our understanding of molecular pathways involved in PD to reveal new targets, and by developing novel animal models of PD for preclinical studies. Currently, at least eight ongoing clinical trials are testing the promise of isradipine, caffeine, nicotine, glutathione, AAV2-glial cell-line derived neurotrophic factor (GDNF), as well as active and passive immunization against α-synuclein (α-Syn). In this review, we summarize the clinical trials of disease-modifying therapies for PD that were published since 2013 as well as clinical trials currently in progress. We also discuss promising approaches and ongoing challenges in this area of PD research.
Movement Disorders 2015
Accumulation of toxic protein aggregates—amyloid-β (Aβ) plaques and hyperphosphorylated tau tangles—is the pathological hallmark of Alzheimer disease (AD). Aβ accumulation has been hypothesized to result from an imbalance between Aβ production and clearance; indeed, Aβ clearance seems to be impaired in both early and late forms of AD. To develop efficient strategies to slow down or halt AD, it is critical to understand how Aβ is cleared from the brain. Extracellular Aβ deposits can be removed from the brain by various clearance systems, most importantly, transport across the blood–brain barrier. Findings from the past few years suggest that astroglial-mediated interstitial fluid (ISF) bulk flow, known as the glymphatic system, might contribute to a larger portion of extracellular Aβ (eAβ) clearance than previously thought. The meningeal lymphatic vessels, discovered in 2015, might provide another clearance route. Because these clearance systems act together to drive eAβ from the brain, any alteration to their function could contribute to AD. An understanding of Aβ clearance might provide strategies to reduce excess Aβ deposits and delay, or even prevent, disease onset. In this Review, we describe the clearance systems of the brain as they relate to proteins implicated in AD pathology, with the main focus on Aβ.
Neurons, like other eukaryotic cells, utilize 2 major pathways for turning over dysfunctional proteins or organelles. One of them is the ubiquitin-proteasome system, which degrades short-lived proteins in the cytoplasm and nucleus and involves the covalent binding of ubiquitin molecules to the targeted protein, followed by its degradation by the proteasome. The second is the autophagy-lysosome pathway, which digests long-lived proteins, protein aggregates, stress RNA granules, and abnormal cytoplasmic organelles, including mitochondria. Autophagy (derived from the Greek words for self and eating) includes 3 major types: microautophagy, chaperone-mediated autophagy (CMA), and macroautophagy; all these pathways eventually lead to cargo degradation by the lysosome. Autophagy is a highly regulated process that involves sequential activation of protein complexes encoded by autophagic genes (ATG). Macroautophagy, the best-characterized form of autophagy, involves the formation of a particular organelle called autophagosome. There are 2 main types of macroautophagy. Basal macroautophagy is a quality control mechanism that prevents metabolic and oxidative stress by degrading aggregated or aggregate-prone proteins or damaged organelles, such as mitochondria. Starvation-induced autophagy occurs in response to nutrient deprivation and recycles macromolecules to provide substrates for energy metabolism. The mammalian (mechanistic) target of rapamycin complex 1 (mTORC1) constitutively inhibits starvation-induced and to a lesser extent basal autophagy. There is interaction between the ubiquitin and the autophagy systems, as ubiquitination serves as a signal for cargo-selective autophagy. There is also crosstalk between autophagy and apoptosis; in most cases, autophagy precedes and increases threshold for apoptosis in response to cellular stress. The fusion of the autophagosome with the lysosome is a critical final step of autophagy. Impairment of the autophagy-lysosomal system leads to accumulation of abnormal protein aggregates and dysfunctional mitochondria promoting oxidative stress and apoptosis. These are shared mechanisms of cell death in neurodegenerative disorders and lysosomal storage diseases. There are recent comprehensive reviews on these subjects and only salient concepts are emphasized here.
sabato 25 luglio 2015
Prevention of sporadic Alzheimer's disease: lessons learned from clinical trials and future directions
Interventions that have even quite modest effects at the individual level could drastically reduce the future burden of dementia associated with Alzheimer's disease at the population level. In the past three decades, both pharmacological and lifestyle interventions have been studied for the prevention of cognitive decline or dementia in randomised controlled trials of individuals mostly aged older than 50–55 years with or without risk factors for Alzheimer's disease. Several trials testing the effects of physical activity, cognitive training, or antihypertensive interventions showed some evidence of efficacy on a primary cognitive endpoint. However, most of these trials had short follow-up periods, and further evidence is needed to confirm effectiveness and establish the optimum design or dose of interventions and ideal target populations. Important innovations in ongoing trials include the development of multidomain interventions, and the use of biomarker or genetic inclusion criteria. Challenges include the use of adaptive trial designs, the development of standardised, sensitive outcome measures, and the need for interventions that can be implemented in resource-poor settings.
Lancet Neurology 2015
Lancet Neurology 2015
sabato 18 luglio 2015
Baseline and longitudinal grey matter changes in newly diagnosed Parkinson’s disease: ICICLE-PD study
Mild cognitive impairment in Parkinson’s disease is associated with progression to dementia (Parkinson’s disease dementia) in a majority of patients. Determining structural imaging biomarkers associated with prodromal Parkinson’s disease dementia may allow for the earlier identification of those at risk, and allow for targeted disease modifying therapies. One hundred and five non-demented subjects with newly diagnosed idiopathic Parkinson’s disease and 37 healthy matched controls had serial 3 T structural magnetic resonance imaging scans with clinical and neuropsychological assessments at baseline, which were repeated after 18 months. The Movement Disorder Society Task Force criteria were used to classify the Parkinson’s disease subjects into Parkinson’s disease with mild cognitive impairment (39) and Parkinson’s disease with no cognitive impairment (66). Freesurfer image processing software was used to measure cortical thickness and subcortical volumes at baseline and follow-up. We compared regional percentage change of cortical thinning and subcortical atrophy over 18 months. At baseline, cases with Parkinson’s disease with mild cognitive impairment demonstrated widespread cortical thinning relative to controls and atrophy of the nucleus accumbens compared to both controls and subjects with Parkinson’s disease with no cognitive impairment. Regional cortical thickness at baseline was correlated with global cognition in the combined Parkinson’s disease cohort. Over 18 months, patients with Parkinson’s disease with mild cognitive impairment demonstrated more severe cortical thinning in frontal and temporo-parietal cortices, including hippocampal atrophy, relative to those with Parkinson’s disease and no cognitive impairment and healthy controls, whereas subjects with Parkinson’s disease and no cognitive impairment showed more severe frontal cortical thinning compared to healthy controls. At baseline, Parkinson’s disease with no cognitive impairment converters showed bilateral temporal cortex thinning relative to the Parkinson’s disease with no cognitive impairment stable subjects. Although loss of both cortical and subcortical volume occurs in non-demented Parkinson’s disease, our longitudinal analyses revealed that Parkinson’s disease with mild cognitive impairment shows more extensive atrophy and greater percentage of cortical thinning compared to Parkinson’s disease with no cognitive impairment. In particular, an extension of cortical thinning in the temporo-parietal regions in addition to frontal atrophy could be a biomarker in therapeutic studies of mild cognitive impairment in Parkinson’s disease for progression towards dementia.
Elevated mutant dynorphin A causes Purkinje cell loss and motor dysfunction in spinocerebellar ataxia type 23
Spinocerebellar ataxia type 23 is caused by mutations in , which encodes the opioid neuropeptide precursor protein, prodynorphin. Prodynorphin is processed into the opioid peptides, α-neoendorphin, and dynorphins A and B, that normally exhibit opioid-receptor mediated actions in pain signalling and addiction. Dynorphin A is likely a mutational hotspot for spinocerebellar ataxia type 23 mutations, and data suggested that dynorphin A mutations lead to persistently elevated mutant peptide levels that are cytotoxic and may thus play a crucial role in the pathogenesis of spinocerebellar ataxia type 23. To further test this and study spinocerebellar ataxia type 23 in more detail, we generated a mouse carrying the spinocerebellar ataxia type 23 mutation R212W in . Analysis of peptide levels using a radioimmunoassay shows that these mice display markedly elevated levels of mutant dynorphin A, which are associated with climber fibre retraction and Purkinje cell loss, visualized with immunohistochemical stainings. The mice reproduced many of the clinical features of spinocerebellar ataxia type 23, with gait deficits starting at 3 months of age revealed by footprint pattern analysis, and progressive loss of motor coordination and balance at the age of 12 months demonstrated by declining performances on the accelerating Rotarod. The pathologically elevated mutant dynorphin A levels in the cerebellum coincided with transcriptionally dysregulated ionotropic and metabotropic glutamate receptors and glutamate transporters, and altered neuronal excitability. In conclusion, the mouse is the first animal model of spinocerebellar ataxia type 23 and our work indicates that the elevated mutant dynorphin A peptide levels are likely responsible for the initiation and progression of the disease, affecting glutamatergic signalling, neuronal excitability, and motor performance. Our novel mouse model defines a critical role for opioid neuropeptides in spinocerebellar ataxia, and suggests that restoring the elevated mutant neuropeptide levels can be explored as a therapeutic intervention
Pelizaeus-Merzbacher disease is an X-linked hypomyelinating leukodystrophy caused by mutations or rearrangements in . It presents in infancy with nystagmus, jerky head movements, hypotonia and developmental delay evolving into spastic tetraplegia with optic atrophy and variable movement disorders. A clinically similar phenotype caused by recessive mutations in is known as Pelizaeus-Merzbacher-like disease. Both genes encode proteins associated with myelin. We describe three siblings of a consanguineous family manifesting the typical infantile-onset Pelizaeus-Merzbacher disease-like phenotype slowly evolving into a form of complicated hereditary spastic paraplegia with mental retardation, dysarthria, optic atrophy and peripheral neuropathy in adulthood. Magnetic resonance imaging and spectroscopy were consistent with a demyelinating leukodystrophy. Using genetic linkage and exome sequencing, we identified a homozygous missense c.399C>G; p.S133R mutation in This gene, previously associated with hereditary spastic paraplegia, encodes myelin-associated glycoprotein, which is involved in myelin maintenance and glia-axon interaction. This mutation is predicted to destabilize the protein and affect its tertiary structure. Examination of the sural nerve biopsy sample obtained in childhood in the oldest sibling revealed complete absence of myelin-associated glycoprotein accompanied by ill-formed onion-bulb structures and a relatively thin myelin sheath of the affected axons. Immunofluorescence, cell surface labelling, biochemical analysis and mass spectrometry-based proteomics studies in a variety of cell types demonstrated a devastating effect of the mutation on post-translational processing, steady state expression and subcellular localization of myelin-associated glycoprotein. In contrast to the wild-type protein, the p.S133R mutant was retained in the endoplasmic reticulum and was subjected to endoplasmic reticulum-associated protein degradation by the proteasome. Our findings identify involvement of myelin-associated glycoprotein in this family with a disorder affecting the central and peripheral nervous system, and suggest that loss of the protein function is responsible for the unique clinical phenotype.
Permeability of the blood–brain barrier predicts conversion from optic neuritis to multiple sclerosis
Optic neuritis is an acute inflammatory condition that is highly associated with multiple sclerosis. Currently, the best predictor of future development of multiple sclerosis is the number of T lesions visualized by magnetic resonance imaging. Previous research has found abnormalities in the permeability of the blood–brain barrier in normal-appearing white matter of patients with multiple sclerosis and here, for the first time, we present a study on the capability of blood–brain barrier permeability in predicting conversion from optic neuritis to multiple sclerosis and a direct comparison with cerebrospinal fluid markers of inflammation, cellular trafficking and blood–brain barrier breakdown. To this end, we applied dynamic contrast-enhanced magnetic resonance imaging at 3 T to measure blood–brain barrier permeability in 39 patients with monosymptomatic optic neuritis, all referred for imaging as part of the diagnostic work-up at time of diagnosis. Eighteen healthy controls were included for comparison. Patients had magnetic resonance imaging and lumbar puncture performed within 4 weeks of onset of optic neuritis. Information on multiple sclerosis conversion was acquired from hospital records 2 years after optic neuritis onset. Logistic regression analysis showed that baseline permeability in normal-appearing white matter significantly improved prediction of multiple sclerosis conversion (according to the 2010 revised McDonald diagnostic criteria) within 2 years compared to T lesion count alone. There was no correlation between permeability and T lesion count. An increase in permeability in normal-appearing white matter of 0.1 ml/100 g/min increased the risk of multiple sclerosis 8.5 times whereas having more than nine T lesions increased the risk 52.6 times. Receiver operating characteristic curve analysis of permeability in normal-appearing white matter gave a cut-off of 0.13 ml/100 g/min, which predicted conversion to multiple sclerosis with a sensitivity of 88% and specificity of 72%. We found a significant correlation between permeability and the leucocyte count in cerebrospinal fluid as well as levels of CXCL10 and MMP9 in the cerebrospinal fluid. These findings suggest that blood–brain barrier permeability, as measured by magnetic resonance imaging, may provide novel pathological information as a marker of neuroinflammation related to multiple sclerosis, to some extent reflecting cellular permeability of the blood–brain barrier, whereas T lesion count may more reflect the length of the subclinical pre-relapse phase.