Unraveling the Early Events of Amyloid-β Protein (Aβ) Aggregation: Techniques for the Determination of Aβ Aggregate Size

The aggregation of proteins into insoluble amyloid fibrils coincides with the onset of numerous diseases. An array of techniques is available to study the different stages of the amyloid aggregation process. Recently, emphasis has been placed upon the analysis of oligomeric amyloid species, which have been hypothesized to play a key role in disease progression. This paper reviews techniques utilized to study aggregation of the amyloid-β protein (Aβ) associated with Alzheimer’s disease. In particular, the review focuses on techniques that provide information about the size or quantity of oligomeric Aβ species formed during the early stages of aggregation, including native-PAGE, SDS-PAGE, Western blotting, capillary electrophoresis, mass spectrometry, fluorescence correlation spectroscopy, light scattering, size exclusion chromatography, centrifugation, enzyme-linked immunosorbent assay, and dot blotting

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Rev Neurol (Paris)

BACKGROUND AND PURPOSE: Recent studies demonstrated the benefit of mechanical thrombectomy (MT) plus intravenous tissue-type plasminogen activator (IV-tPA) (MT-IV-tPA) in acute ischemic stroke. This study aimed to estimate the cost-utility of MT-IV-tPA compared with IV-tPA alone from the perspective of the French National Health Insurance. METHODS: We developed a decision tree for the first 3 months after stroke onset and a Markov model until 10 years post-stroke. The health states of the Markov model were according to the modified Rankin Scale (mRS): independent (mRS=0-2), dependent (mRS=3-5), dead (mRS=6). Recurrent stroke was the fourth health stage of our model. We conducted systematic literature reviews and meta-analyses to estimate the cost and utility of each health state, and the transition probabilities between health states. A microcosting study was conducted to estimate the cost of MT. We estimated the incremental cost-effectiveness ratio of MT-IV-tPA and conducted a probabilistic analysis in order to estimate the probability that MT-IV-tPA is cost-effective compared to IV-tPA, the expected value of perfect information (EVPI), and the expected value of partial perfect information (EVPPI), given the uncertainty surrounding the value of our model's parameters. RESULTS: The total mean (standard deviation (SD) cost of MT was euro6708.9 (2357.0). The incremental cost-effectiveness ratio (ICER) of the strategy using IV-tPA combined to MT costs was euro14,715 per QALY gained as compared to a strategy using IV-tPA alone. The probabilistic analysis showed that the probability of MT-IV-TPA being cost-effective was 85.4% at threshold willingness-to-pay of euro30,000 per QALY gained, reaching 98% at euro50,000 per QALY gained. CONCLUSION: Although there is no universally accepted willingness-to-pay threshold in France, our analysis suggest that MT combined to IV-tPA can be considered a cost-effective treatment compared with IV-tPA alone

Comparative cost-effectiveness analysis of sacral anterior root stimulation for rehabilitation of bladder dysfunction in spinal cord injured patients.

International audienceBACKGROUND: Urinary disorders account for 10% of deaths in patients with complete spinal cord injury. Sacral anterior root stimulation (SARS) may be a valuable therapeutic option to restore complete and voluntary micturition (CVM), but questions on its cost-effectiveness remain. OBJECTIVE: To evaluate the cost-effectiveness of SARS to restore CVM in patients with complete spinal cord injury. METHODS: We conducted a nonrandomized, multicenter, parallel-group cohort study comparing SARS vs. current medical treatments with catheterization or reflex micturition. CVM was assessed at 12 months (end of follow-up) by urodynamic examination. Medical and nonmedical costs were measured in the perspective of the French national health insurance. Linear regression models were used to estimate the incremental net benefit ((Equation is included in full-text article.); λ = willingness-to-pay) adjusted for potential confounders, and P (INB >0) (i.e., probability of SARS being cost-effective vs medical treatment) for different values of λ. RESULTS: Twenty-five patients were included in each group in 2005 to 2009. At inclusion, mean age was 41 years; 45 (90%) patients were male, and 29 (59%) patients were paraplegic. At 12 months, 15 (60%) patients with SARS had a CVM vs. 3 (12%) patients with medical treatment (P 0) was 74% at λ = 100,000 €. This probability was 94% in a sensitivity analysis excluding 6 patients presenting a CVM at inclusion. CONCLUSION: The effectiveness and cost of SARS are much higher than for medical treatment. Our results inform decision makers of the opportunity to reimburse SARS in this vulnerable population

Evaluating Amyloid Beta (Aβ) 1-40 Degradation by Capillary Electrophoresis

Here, we describe a capillary electrophoresis method for evaluating proteolysis of the amyloid beta peptide (Aβ) 1–40. This method is suitable for kinetic studies, demands little specialized equipment, and consumes only small quantities of a commercially available substrate whose physiological accumulation is thought to underlie the development of Alzheimer’s disease

Development of a magnetic immunosorbent for on-chip preconcentration of amyloid β isoforms: Representatives of Alzheimer’s disease biomarkers

Determination of amyloid β (Aβ) isoforms and in particular the proportion of the Aβ 1-42 isoform in cerebrospinal fluid (CSF) of patients suspected of Alzheimer’s disease might help in early diagnosis and treatment of that illness. Due to the low concentration of Aβ peptides in biological fluids, a preconcentration step prior to the detection step is often necessary. This study utilized on-chip immunoprecipitation, known as micro-immunoprecipitation (μIP). The technique uses an immunosorbent (IS) consisting of magnetic beads coated with specific anti-Aβ antibodies organized into an affinity microcolumn by a magnetic field. Our goal was to thoroughly describe the critical steps in developing the IS, such as selecting the proper beads and anti-Aβ antibodies, as well as optimizing the immobilization technique and μIP protocol. The latter includes selecting optimal elution conditions. Furthermore, we demonstrate the efficiency of anti-Aβ IS for μIP and specific capture of 5 Aβ peptides under optimized conditions using various subsequent analytical methods, including matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), capillary electrophoresis, microchip electrophoresis, and immunoblotting. Synthetic Aβ peptides samples prepared in buffer and spiked in human CSF were analyzed. Finally, on-chip immunoprecipitation of Aβ peptides in human CSF sample was performed