NCS-1 Inhibits insulin stimulated GLUT4 translocation in 3T3L1 adipocytes through a phosphatidylinositol 4-kinase dependent pathway

Expression of NCS-1 (neuronal calcium sensor-1, also termed frequenin) in 3T3L1 adipocytes strongly inhibited insulin-stimulated translocation of GLUT4 and insulin-responsive aminopeptidase. The effect of NCS-1 was specific for GLUT4 and the insulin-responsive aminopeptidase translocation as there was no effect on the trafficking of the cation-independent mannose 6-phosphate receptor or the GLUT1 glucose transporter isoform. Moreover, NCS-1 showed partial colocalization with GLUT4-EGFP in the perinuclear region. The inhibitory action of NCS-1 was independent of calcium sequestration since neither treatment with ionomycin nor endothelin-1, both of which elevated the intracellular calcium concentration, restored insulin-stimulated GLUT4 translocation. Furthermore, NCS-1 did not alter the insulin-stimulated protein kinase B (PKB/Akt) phosphorylation or the recruitment of Cbl to the plasma membrane. In contrast, expression of the NCS-1 effector phosphatidylinositol 4-kinase (PI 4-kinase) inhibited insulin-stimulated GLUT4 translocation, whereas co-transfection with an inactive PI 4-kinase mutant prevented the NCS-1-induced inhibition. These data demonstrate that PI 4-kinase functions to negatively regulate GLUT4 translocation through its interaction with NCS-1

Quantification of SNAP-25 with mass spectrometry and Simoa: a method comparison in Alzheimer's disease

BACKGROUND: Synaptic dysfunction and degeneration are central to Alzheimer's disease (AD) and have been found to correlate strongly with cognitive decline. Thus, studying cerebrospinal fluid (CSF) biomarkers reflecting synaptic degeneration, such as the presynaptic protein synaptosomal-associated protein 25 (SNAP-25), is of importance to better understand the AD pathophysiology. METHODS: We compared a newly developed Single molecule array (Simoa) immunoassay for SNAP-25 with an in-house immunoprecipitation mass spectrometry (IP-MS) method in a well-characterized clinical cohort (n = 70) consisting of cognitively unimpaired (CU) and cognitively impaired (CI) individuals with and without Aβ pathology (Aβ+ and Aβ-). RESULTS: A strong correlation (Spearman's rank correlation coefficient (rs) > 0.88; p < 0.0001) was found between the Simoa and IP-MS methods, and no statistically significant difference was found for their clinical performance to identify AD pathophysiology in the form of Aβ pathology. Increased CSF SNAP-25 levels in CI Aβ+ compared with CU Aβ- (Simoa, p ≤ 0.01; IP-MS, p ≤ 0.05) and CI Aβ- (Simoa, p ≤ 0.01; IP-MS, p ≤ 0.05) were observed. In independent blood samples (n = 32), the Simoa SNAP-25 assay was found to lack analytical sensitivity for quantification of SNAP-25 in plasma. CONCLUSIONS: These results indicate that the Simoa SNAP-25 method can be used interchangeably with the IP-MS method for the quantification of SNAP-25 in CSF. Additionally, these results confirm that CSF SNAP-25 is increased in relation to amyloid pathology in the AD continuum

Cytogenetic complexity in chronic lymphocytic leukemia: definitions, associations and clinical impact

Recent evidence suggests that complex karyotype (CK) defined by the presence of 653 chromosomal aberrations (structural and/or numerical) identified by chromosome banding analysis (CBA) may be relevant for treatment decision-making in chronic lymphocytic leukemia (CLL). However, many challenges towards routine clinical application of CBA remain. In a retrospective study of 5290 patients with available CBA data, we explored both clinicobiological associations and the clinical impact of CK in CLL. We found that patients with 655 abnormalities, defined as high-CK, exhibit uniformly dismal clinical outcome, independently of clinical stage, TP53 aberrations (deletion of chromosome 17p and or TP53 mutations, TP53abs) and the expression of somatically hypermutated (M-CLL) or unmutated (U-CLL) immunoglobulin heavy variable genes (IGHV). Thus, they contrasted CK cases with 3 or 4 aberrations (low-CK and intermediate-CK, respectively) who followed aggressive disease courses only in the presence of TP53abs. At the other end of the spectrum, patients with CK and +12,+19 displayed an exceptionally indolent profile. Building upon CK, TP53abs and IGHV gene somatic hypermutation status, we propose a novel hierarchical model where patients with high-CK exhibit the worst prognosis, while M-CLL lacking CK or TP53abs as well as CK with +12,+19 show the longest overall survival. In conclusion, CK should not be axiomatically considered unfavorable in CLL, representing a heterogeneous group with variable clinical behavior. High-CK with 655 chromosomal aberrations emerges as prognostically adverse, independently of other biomarkers. Prospective clinical validation is warranted before finally incorporating high-CK in risk stratification of CLL

Neurofilaments in pre-symptomatic ALS and the impact of genotype.

Objective. To evaluate serum and cerebrospinal fluid (CSF) levels of phosphorylated neurofilament heavy (pNfH), and to compare these to levels of neurofilament light (NfL), as biomarkers of pre-symptomatic ALS. Design. The study population includes 34 controls, 79 individuals at-risk for ALS, 22 ALS patients, and 14 phenoconverters. At-risk individuals are enrolled through Pre-Symptomatic Familial ALS (Pre-fALS), a longitudinal natural history and biomarker study of individuals who are carriers of any ALS-associated gene mutation, but who demonstrate no clinical evidence of disease at the time of enrollment. pNfH and NfL in serum and CSF were quantified using established enzyme-linked immunosorbent assays. Results. There is a longitudinal increase in serum pNfH in advance of the emergence of clinically manifest ALS. A similar pattern is observed for NfL, but with the absolute levels also frequently exceeding a normative threshold. Although CSF data are more sparse, similar patterns are observed for both neurofilaments, with absolute levels exceeding a normative threshold prior to phenoconversion. In serum, these changes are observed in the 6-12 months prior to disease among SOD1 A4V mutation carriers, and as far back as 2 and 3.5 years, respectively, in individuals with a FUS c.521del6 mutation and a C9ORF72 hexanucleotide repeat expansion. Conclusions. Serum and CSF pNfH increase prior to phenoconversion. In CSF, the temporal course of these changes is similar to NfL. In serum, however, pNfH is less sensitive to pre-symptomatic disease than NfL. The duration of pre-symptomatic disease, as defined by changes in neurofilaments, may vary depending on underlying genotype

Biological variation estimates of Alzheimer's disease plasma biomarkers in healthy individuals

INTRODUCTIONBlood biomarkers have proven useful in Alzheimer's disease (AD) research. However, little is known about their biological variation (BV), which improves the interpretation of individual-level data.METHODSWe measured plasma amyloid beta (Aβ42, Aβ40), phosphorylated tau (p-tau181, p-tau217, p-tau231), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL) in plasma samples collected weekly over 10 weeks from 20 participants aged 40 to 60 years from the European Biological Variation Study. We estimated within- (CVI) and between-subject (CVG) BV, analytical variation, and reference change values (RCV).RESULTSBiomarkers presented considerable variability in CVI and CVG. Aβ42/Aβ40 had the lowest CVI (≈ 3%) and p-tau181 the highest (≈ 16%), while others ranged from 6% to 10%. Most RCVs ranged from 20% to 30% (decrease) and 25% to 40% (increase).DISCUSSIONBV estimates for AD plasma biomarkers can potentially refine their clinical and research interpretation. RCVs might be useful for detecting significant changes between serial measurements when monitoring early disease progression or interventions.Highlights·Plasma amyloid beta (Aβ42/Aβ40) presents the lowest between- and within-subject biological variation, but also changes the least in Alzheimer's disease (AD) patients versus controls.·Plasma phosphorylated tau variants significantly vary in their within-subject biological variation, but their substantial fold-changes in AD likely limits the impact of their variability.·Plasma neurofilament light chain and glial fibrillary acidic protein demonstrate high between-subject variation, the impact of which will depend on clinical context.·Reference change values can potentially be useful in monitoring early disease progression and the safety/efficacy of interventions on an individual level.·Serial sampling revealed that unexpectedly high values in heathy individuals can be observed, which urges caution when interpreting AD plasma biomarkers based on a single test result.<br/

Increased levels of serum MAP-2 at 6-months correlate with improved outcome in survivors of severe traumatic brain injury

Objective: To evaluate microtubule-associated proteins (MAP-2), a dendritic marker of both acute damage and chronic neuronal regeneration after injury, in serum of survivors after severe TBI and examine the association with long-term outcome. Methods: Serum concentrations of MAP-2 were evaluated in 16 patients with severe TBI (Glasgow Coma Scale score [GCS] ≤ 8) 6 months post-injury and in 16 controls. Physical and cognitive outcomes were assessed, using the Glasgow Outcome Scale Extended (GOSE) and Levels of Cognitive Functioning Scale (LCFS), respectively. Results: Severe TBI patients had significantly higher serum MAP-2 concentrations than normal controls with no history of TBI (p = 0.008) at 6 months post-injury. MAP-2 levels correlated with the GOSE (r = 0.58, p = 0.02) and LCFS (r = 0.65, p = 0.007) at month 6. Significantly lower serum levels of MAP-2 were observed in patients in a vegetative state (VS) compared to non-VS patients (p < 0.05). A trend tracking the level of consciousness was observed. Conclusions: Severe TBI results in a chronic release of MAP-2 into the peripheral circulation in patients with higher levels of consciousness, suggesting that remodelling of synaptic junctions and neuroplasticity processes occur several months after injury. The data indicate MAP-2 as a potential marker for emergence to higher levels of cognitive function

The Oxygen Evolution Reaction Drives Passivity Breakdown for Ni–Cr–Mo Alloys

Corrosion is the main factor limiting the lifetime of metallic materials, and a fundamental understanding of the governing mechanism and surface processes is difficult to achieve since the thin oxide films at the metal-liquid interface governing passivity are notoriously challenging to study. In this work, a combination of synchrotron-based techniques and electrochemical methods is used to investigate the passive film breakdown of a Ni-Cr-Mo alloy, which is used in many industrial applications. This alloy is found to be active toward oxygen evolution reaction (OER), and the OER onset coincides with the loss of passivity and severe metal dissolution. The OER mechanism involves the oxidation of Mo4+ sites in the oxide film to Mo6+ that can be dissolved, which results in passivity breakdown. This is fundamentally different from typical transpassive breakdown of Cr-containing alloys where Cr6+ is postulated to be dissolved at high anodic potentials, which is not observed here. At high current densities, OER also leads to acidification of the solution near the surface, further triggering metal dissolution. The OER plays an important role in the mechanism of passivity breakdown of Ni-Cr-Mo alloys due to their catalytic activity, and this effect needs to be considered when studying the corrosion of catalytically active alloys

A Multi-Center Study of Neurofilament Assay Reliability and Inter-Laboratory Variability

Objectives: Significantly elevated levels of neurofilament light chain (NfL) and phosphorylated neurofilament heavy chain (pNfH) have been described in the blood and cerebrospinal fluid (CSF) of amyotrophic lateral sclerosis (ALS) patients. The aim of this study was to evaluate the analytical performance of different neurofilament assays in a round robin with 10 centers across Europe/U.S. Methods: Serum, plasma and CSF samples from a group of five ALS and five neurological control patients were distributed across 10 international specialist neurochemical laboratories for analysis by a range of commercial and in-house neurofilament assays. The performance of all assays was evaluated for their ability to differentiate between the groups. The inter-assay coefficient of variation was calculated where appropriate from sample measurements performed across multiple laboratories using the same assay. Results: All assays could differentiate ALS patients from controls in CSF. Inter-assay coefficient of variation of analytical platforms performed across multiple laboratories varied between 6.5% and 41.9%. Conclusions: This study is encouraging for the growing momentum toward integration of neurofilament measurement into the specialized ALS clinic. It demonstrates the importance of 'round robin' studies necessary to ensure the analytical quality required for translation to the routine clinical setting. A standardized neurofilament probe is needed which can be used as international benchmark for analytical performance in ALS.status: Published onlin

A multi-center study of neurofilament assay reliability and inter-laboratory variability

© 2020 World Federation of Neurology on behalf of the Research Group on Motor Neuron Diseases. Objectives: Significantly elevated levels of neurofilament light chain (NfL) and phosphorylated neurofilament heavy chain (pNfH) have been described in the blood and cerebrospinal fluid (CSF) of amyotrophic lateral sclerosis (ALS) patients. The aim of this study was to evaluate the analytical performance of different neurofilament assays in a round robin with 10 centers across Europe/U.S. Methods: Serum, plasma and CSF samples from a group of five ALS and five neurological control patients were distributed across 10 international specialist neurochemical laboratories for analysis by a range of commercial and in-house neurofilament assays. The performance of all assays was evaluated for their ability to differentiate between the groups. The inter-assay coefficient of variation was calculated where appropriate from sample measurements performed across multiple laboratories using the same assay. Results: All assays could differentiate ALS patients from controls in CSF. Inter-assay coefficient of variation of analytical platforms performed across multiple laboratories varied between 6.5% and 41.9%. Conclusions: This study is encouraging for the growing momentum toward integration of neurofilament measurement into the specialized ALS clinic. It demonstrates the importance of ‘round robin’ studies necessary to ensure the analytical quality required for translation to the routine clinical setting. A standardized neurofilament probe is needed which can be used as international benchmark for analytical performance in ALS