Long-Term Storage Effects on Stability of Aβ1–40, Aβ1–42, and Total Tau Proteins in Human Plasma Samples Measured with Immunomagnetic Reduction Assays

Background: The stability of Alzheimer’s disease (AD) biomarkers in plasma, measured by immunomagnetic reduction (IMR) after long-term storage at –80°C, has not been established before. Method: Ninety-nine human plasma samples from 53 normal controls (NCs), 5 patients with amnestic mild cognitive impairment (aMCI), and 41 AD patients were collected. Each plasma sample was aliquoted and stored as single-use aliquots at –80°C. The baseline measurements for Aβ1–40, Aβ1–42, and total Tau protein (T-Tau) concentrations for each sample were done within 3 months of blood draw by IMR. They are referred to as baseline concentrations. A separate aliquot from each sample was assayed with IMR to assess the stability of the measured analytes during storage at –80°C between 1.1 and 5.4 years. This is referred to as a repeated result. Results: IMR shows that plasma levels of Aβ1–40 and Aβ1–42 exhibit stability over 5-year storage at –80°C and that plasma levels of T-Tau are less stable (approximately 1.5 years). Conclusion: Although the measured concentrations of T-Tau in human plasma may alter during storage, the diagnostic utility of the results are only slightly affected when the product of Aβ1–42 and T-Tau concentrations are used. The results show that the overall agreement between baseline and repeated measurements in the ability of discriminating NCs from aMCI/AD patients is higher than 80%

The Relation Between Brain Amyloid Deposition, Cortical Atrophy, and Plasma Biomarkers in Amnesic Mild Cognitive Impairment and Alzheimer’s Disease

Background: Neuritic plaques and neurofibrillary tangles are the pathological hallmarks of Alzheimer’s disease (AD), while the role of brain amyloid deposition in the clinical manifestation or brain atrophy remains unresolved. We aimed to explore the relation between brain amyloid deposition, cortical thickness, and plasma biomarkers.Methods: We used 11C-Pittsburgh compound B-positron emission tomography to assay brain amyloid deposition, magnetic resonance imaging to estimate cortical thickness, and an immunomagnetic reduction assay to measure plasma biomarkers. We recruited 39 controls, 25 subjects with amnesic mild cognitive impairment (aMCI), and 16 subjects with AD. PiB positivity (PiB+) was defined by the upper limit of the 95% confidence interval of the mean cortical SUVR from six predefined regions (1.0511 in this study).Results: All plasma biomarkers showed significant between-group differences. The plasma Aβ40 level was positively correlated with the mean cortical thickness of both the PiB+ and PiB- subjects. The plasma Aβ40 level of the subjects who were PiB+ was negatively correlated with brain amyloid deposition. In addition, the plasma tau level was negatively correlated with cortical thickness in both the PiB+ and PiB- subjects. Moreover, cortical thickness was negatively correlated with brain amyloid deposition in the PiB+ subjects. In addition, the cut-off point of plasma tau for differentiating between controls and AD was higher in the PiB- group than in the PiB+ group (37.5 versus 25.6 pg/ml, respectively). Lastly, ApoE4 increased the PiB+ rate in the aMCI and control groups.Conclusion: The contributions of brain amyloid deposition to cortical atrophy are spatially distinct. Plasma Aβ40 might be a protective indicator of less brain amyloid deposition and cortical atrophy. It takes more tau pathology to reach the same level of cognitive decline in subjects without brain amyloid deposition, and ApoE4 plays an early role in amyloid pathogenesis

Ex Vivo Magnetofection with Magnetic Nanoparticles: A Novel Platform for Nonviral Tissue Engineering

Several methods have been described to introduce DNA expression vectors into mammalian cells both in vitro and in vivo. Each system has benefits and limitations, and to date there is still no ideal method for gene transfer. In this study, we introduced a novel method of gene transfer by using Fe3O4 nanoparticles. The magnetic nanoparticles composed of Fe3O4, and the transfected genes used are Lac Z and enhanced green fluorescence protein gene (EGFG). Four different groups of preparations included in this study were homemade liposome-enveloped EGFP-DNA/Fe3O4, homemade liposome EGFP-DNA gene without magnetic Fe3O4 nanoparticles, lipofectamine 2000-enveloped EGFP-DNA, and EGFP-DNA gene only. Mice osteoblast and He99 lung cancer cell line were used as host cells for gene transfection. The time-dependent EGFP gene expression was monitored and analyzed. The results showed that the diameter of the complex was less than 100 nm. There was no cytotoxicity observed at any of the magnetic Fe3O4 nanoparticle concentrations tested. In the presence of magnetic field, the liposome-enveloped EGFP- DNA/Fe3O4 complex exhibited a much higher efficiency for transfecting EGFP-DNA into osteoblast cells under external magnetic fields. The gene can be transfected into cells with an aid of magnetic vectors and magnetic force. Under a gradient magnetic field, the efficiency of magnetofection is enhanced as compared to that without magnetic field

Dual immobilization and magnetic manipulation of magnetic nanoparticles

By suitably bio-functionalizing the surfaces, magnetic nanoparticles are able to bind specific biomolecules, and may serve as vectors for delivering bio-entities to target tissues. In this work, the synthesis of bio-functionalized magnetic nanoparticles with two kinds of bio-probes is developed. Here, the stem cell is selected as a to-be- delivered bio- entity and infarcted myocardium is the target issue. Thus, cluster designation-34 (CD-34) on stem cell and creatine kinase-MB (CK-MB) (or troponin I) on infarcted myocardium are the specific biomolecules to be bound with bio-functionalized magnetic nanoparticles. In addition to demonstrating the co-coating of two kinds of bio-probes on a magnetic nanoparticle, the feasibility of manipulation on bio-functionalized magnetic nanoparticles by external magnetic fields is investigated

Dual Immobilization and Magnetic Manipulation of Magnetic Nanoparticles

By suitably bio-functionalizing the surfaces, magnetic nanoparticles are able to bind specific biomolecules, and may serve as vectors for delivering bio-entities to target tissues. In this work, the synthesis of bio-functionalized magnetic nanoparticles with two kinds of bio-probes is developed. Here, the stem cell is selected as a to-be- delivered bio- entity and infarcted myocardium is the target issue. Thus, cluster designation-34 (CD-34) on stem cell and creatine kinase-MB (CK-MB) (or troponin I) on infarcted myocardium are the specific biomolecules to be bound with bio-functionalized magnetic nanoparticles. In addition to demonstrating the co-coating of two kinds of bio-probes on a magnetic nanoparticle, the feasibility of manipulation on bio-functionalized magnetic nanoparticles by external magnetic fields is investigated

Development of an ultra-high sensitive immunoassay with plasma biomarker for differentiating Parkinson disease dementia from Parkinson disease using antibody functionalized magnetic nanoparticles

Background: It is difficult to discriminate healthy subjects and patients with Parkinson disease (PD) or Parkinson disease dementia (PDD) by assaying plasma alpha-synuclein because the concentrations of circulating alpha-synuclein in the blood are almost the same as the low-detection limit using current immunoassays, such as enzyme-linked immunosorbent assay. In this work, an ultra-sensitive immunoassay utilizing immunomagnetic reduction (IMR) is developed. The reagent for IMR consists of magnetic nanoparticles functionalized with antibodies against alpha-synuclein and dispersed in pH-7.2 phosphate-buffered saline. A high-T-c superconducting-quantum-interference-device (SQUID) alternative-current magnetosusceptometer is used to measure the IMR signal of the reagent due to the association between magnetic nanoparticles and alpha-synuclein molecules. Results: According to the experimental alpha-synuclein concentration dependent IMR signal, the low-detection limit is 0.3 fg/ml and the dynamic range is 310 pg/ml. The preliminary results show the plasma alpha-synuclein for PD patients distributes from 6 to 30 fg/ml. For PDD patients, the concentration of plasma alpha-synuclein varies from 0.1 to 100 pg/ml. Whereas the concentration of plasma alpha-synuclein for healthy subjects is significantly lower than that of PD patients. Conclusions: The ultra-sensitive IMR by utilizing antibody-functionalized magnetic nanoparticles and high-T-c SQUID magnetometer is promising as a method to assay plasma alpha-synuclein, which is a potential biomarker for discriminating patients with PD or PDD

Applying the Fuzzy BWM to Determine the Cryptocurrency Trading System under Uncertain Decision Process

The crypto and digital assets ecosystems have attracted investment, regulators, and speculators to their environment. As the blockchain-based framework can reduce transaction costs, generate distributed trust, and enable decentralized platforms, it has become a potential new base for decentralized business models. Previous studies have highlighted the advantages and drawbacks of each platform, such as interest rates, cost concerns, transparency issues, hacking issues, and hazards. Consequently, it is challenging for investors to evaluate the cryptocurrency trading system which determines the optimum exchanges and crucial aspects. Therefore, in order to rank the optimal digital token trading system, this paper develops an evaluation architecture to determine the various token trading systems. The developed architecture integrates fuzzy theory and the best-worst method (BWM) into the decision-making process to assess decision behaviors regarding preference for digital token trading systems in investors in Taiwan. First, this work establishes the views and parameters by modifying the Delphi method based on a literature review and survey. Second, the fuzzy-BWM is applied to obtain the fuzzy weights of the views and parameters. Then, defuzzification and BWM are used to rank the optimal alternatives of the digital token trading systems for investors. The results indicate that the optimal digital token trading system is the decentralized platform, and the critical parameters are gas fees, interest rates, and the mechanism of savings under fuzzy uncertain scenarios. This means that when considering the uncertain and ambiguous characteristics of the expert decision process in digital token trading systems, the evaluation is decentralized and the gas fees are the most important parameter in the digital token investment platform. Academically, the fuzzy BWM-based decision-making architecture can provide corporations and investors with valuable guidance to rank the optimal digital token trading systems based on fuzzy uncertain scenarios. Commercially, the proposed architecture could provide corporations and investors with a useful model to measure the optimal digital token trading system