Performance of the QPLEX™ Alz plus assay, a novel multiplex kit for screening cerebral amyloid deposition
Background: Alzheimer’s disease (AD) is an irreversible neurodegenerative disease characterized by the hallmark finding of cerebral amyloid deposition. Many researchers have tried to predict the existence of cerebral amyloid deposition by using easily accessible blood plasma samples, but the effectiveness of such strategies remains controversial.
Methods: We developed a new multiplex kit, the QPLEX™ Alz plus assay kit, which uses proteomics-based blood biomarkers to prescreen for cerebral amyloid deposition. A total of 300 participants who underwent Pittsburgh compound B (PiB)-positron emission tomography (PET) which allows imaging of cerebral amyloid deposition were included in this study. We compared the levels of QPLEX™ biomarkers between patients who were classified as PiB-negative or PiB-positive, regardless of their cognitive function. Logistic regression analysis followed by receiver operating characteristic (ROC) curve analysis was performed. The kit accuracy was tested using a randomized sample selection method.
Results: The results obtained using our assay kit reached 89.1% area under curve (AUC) with 80.0% sensitivity and 83.0% specificity. Further validation of the QPLEX™ Alz plus assay kit using a randomized sample selection method showed an average accuracy of 81.5%.
Conclusions: Our QPLEX™ Alz plus assay kit provides preliminary evidence that it can be used as blood marker to predict cerebral amyloid deposition but independent validation is needed.
Description: Premade ready to use kits will always come in handy. Get your experiment done right form the first try by using a validated kit with perfectly balanced reagents proportions and compatibility and by following a clear protocol.
Description: The OxiSelect ROS Assay Kit is a cell-based assay for measuring hydroxyl, peroxyl, and other reactive oxygen species activity within a cell. The assay employs the cell-permeable fluorogenic probe DCFH-DA, which diffuses into cells and is deacetylcated by cellular esterases into the non-fluorescent DCFH (Figure 1). In the presence of ROS, DCFH is rapidly oxidized to highly fluorescent DCF. Fluorescence is read on a standard fluorometric plate reader.
Description: The OxiSelect ROS Assay Kit is a cell-based assay for measuring hydroxyl, peroxyl, and other reactive oxygen species activity within a cell. The assay employs the cell-permeable fluorogenic probe DCFH-DA, which diffuses into cells and is deacetylcated by cellular esterases into the non-fluorescent DCFH (Figure 1). In the presence of ROS, DCFH is rapidly oxidized to highly fluorescent DCF. Fluorescence is read on a standard fluorometric plate reader.
Description: The OxiSelect Cellular Antioxidant Assay Kit is a cell-based assay for measuring the activity of an exogenous antioxidant compound within adherent cells. Cells are first cultured in a 96-well black fluorescence cell culture plate until confluent. Then the cells are pre-incubated with a cell-permeable DCFH-DA fluorescence probe dye and the bioflavonoid Quercetin, or the antioxidant sample being tested. After a brief incubation, the cells are washed, and the reaction started by adding the Free Radical Initiator. The Free Radical Initiator creates free radicals that convert the probe to highly fluorescent DCF. The Quercetin inhibits the formation of free radicals, and thus DCF formation, in a concentration dependent manner.
Description: The OxiSelect ROS Assay Kit is a cell-based assay for measuring hydroxyl, peroxyl, and other reactive oxygen species activity within a cell. The assay employs the cell-permeable fluorogenic probe DCFH-DA, which diffuses into cells and is deacetylcated by cellular esterases into the non-fluorescent DCFH (Figure 1). In the presence of ROS, DCFH is rapidly oxidized to highly fluorescent DCF. Fluorescence is read on a standard fluorometric plate reader.
OxiSelect In Vitro ROS/RNS Assay Kit (Green Fluorescence)
Description: The OxiSelect In Vitro ROS/RNS Assay provides a sensitive method to detect total reactive oxygen species (ROS) plus reactive nitrogen species (RNS) in a wide variety of sample types. This assay employs a proprietary fluorogenic probe, DCFH-DiOxyQ; the probe is primed with a dequenching reagent to the highly reactive DCFH form. In the presence of ROS and RNS, the DCFH is rapidly oxidized to the highly fluorescent DCF.
OxiSelect In Vitro ROS/RNS Assay Kit (Green Fluorescence)
Description: The OxiSelect In Vitro ROS/RNS Assay provides a sensitive method to detect total reactive oxygen species (ROS) plus reactive nitrogen species (RNS) in a wide variety of sample types. This assay employs a proprietary fluorogenic probe, DCFH-DiOxyQ; the probe is primed with a dequenching reagent to the highly reactive DCFH form. In the presence of ROS and RNS, the DCFH is rapidly oxidized to the highly fluorescent DCF.
EZClick? Palmitoylated Protein Assay Kit (FACS/Microscopy), Green Fluorescence
Description: The OxiSelect In Vitro ROS/RNS Assay provides a sensitive method to detect total reactive oxygen species (ROS) plus reactive nitrogen species (RNS) in a wide variety of sample types. This assay employs a proprietary fluorogenic probe, DCFH-DiOxyQ; the probe is primed with a dequenching reagent to the highly reactive DCFH form. In the presence of ROS and RNS, the DCFH is rapidly oxidized to the highly fluorescent DCF.
EZClick? O-GalNAc Modified Glycoprotein Assay Kit (FACS/Microscopy, Green Fluorescence)
Description: A polyclonal antibody against DAP. Recognizes DAP from Human, Mouse, Rat. This antibody is Unconjugated. Tested in the following application: ELISA, IHC;ELISA:1:2000-1:5000, IHC:1:50-1:200
Description: A polyclonal antibody against DAP. Recognizes DAP from Human. This antibody is Unconjugated. Tested in the following application: ELISA, IHC; Recommended dilution: IHC:1:50-1:200
Description: A polyclonal antibody against DAP. Recognizes DAP from Human, Mouse, Rat. This antibody is Unconjugated. Tested in the following application: ELISA
Description: A polyclonal antibody against DAP. Recognizes DAP from Human, Mouse. This antibody is Unconjugated. Tested in the following application: IHC, ELISA;IHC:1/100-1/300.ELISA:1/40000
Description: A polyclonal antibody against DAP. Recognizes DAP from Human, Mouse, Rat. This antibody is Unconjugated. Tested in the following application: ELISA, IHC;ELISA:1:1000-1:2000, IHC:1:25-1:100
Description: DAP Antibody: The Death-associated protein (DAP) is a basic proline-rich 15kDa protein that as a positive mediator of programmed cell death that is induced by interferon-gamma (1). DAP is also a direct substrate of mammalian target of rapamycin (mTOR), a serine/threonine kinase that regulates cell growth and cell cycle, and a negative regulator of autophagy. Under rich nutrient conditions, mTOR phosphorylates DAP at Ser3 and Ser51; under starvation conditions, these residues are dephosphorylated and DAP is converted into an active suppressor of autophagy (2).
Description: DAP Antibody: The Death-associated protein (DAP) is a basic proline-rich 15kDa protein that as a positive mediator of programmed cell death that is induced by interferon-gamma (1). DAP is also a direct substrate of mammalian target of rapamycin (mTOR), a serine/threonine kinase that regulates cell growth and cell cycle, and a negative regulator of autophagy. Under rich nutrient conditions, mTOR phosphorylates DAP at Ser3 and Ser51; under starvation conditions, these residues are dephosphorylated and DAP is converted into an active suppressor of autophagy (2).
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Analysis of Cerebrospinal Fluid Extracellular Vesicles by Proximity Extension Assay: A Comparative Study of Four Isolation Kits
There is a lack of reliable biomarkers for disorders of the central nervous system (CNS), and diagnostics still heavily rely on symptoms that are both subjective and difficult to quantify. The cerebrospinal fluid (CSF) is a promising source of biomarkers due to its close connection to the CNS.
Extracellular vesicles are actively secreted by cells, and proteomic analysis of CSF extracellular vesicles (EVs) and their molecular composition likely reflects changes in the CNS to a higher extent compared with total CSF, especially in the case of neuroinflammation, which could increase blood-brain barrier permeability and cause an influx of plasma proteins into the CSF. We used proximity extension assay for proteomic analysis due to its high sensitivity.
We believe that this methodology could be useful for de novo biomarker discovery for several CNS diseases. We compared four commercially available kits for EV isolation: MagCapture and ExoIntact (based on magnetic beads), EVSecond L70 (size-exclusion chromatography), and exoEasy (membrane affinity).
The isolated EVs were characterized by nanoparticle tracking analysis, ELISA (CD63, CD81 and albumin), and proximity extension assay (PEA) using two different panels, each consisting of 92 markers. The exoEasy samples did not pass the built-in quality controls and were excluded from downstream analysis.
The number of detectable proteins in the ExoIntact samples was considerably higher (~150% for the cardiovascular III panel and ~320% for the cell regulation panel) compared with other groups. ExoIntact also showed the highest intersample correlation with an average Pearson’s correlation coefficient of 0.991 compared with 0.985 and 0.927 for MagCapture and EVSecond, respectively.
The median coefficient of variation was 5%, 8%, and 22% for ExoIntact, MagCapture, and EVSecond, respectively. Comparing total CSF and ExoIntact samples revealed 70 differentially expressed proteins in the cardiovascular III panel and 17 in the cell regulation panel. To our knowledge, this is the first time that CSF EVs were analyzed by PEA. In conclusion, analysis of CSF EVs by PEA is feasible, and different isolation kits give distinct results, with ExoIntact showing the highest number of identified proteins with the lowest variability.
A simple and rapid algal assaykit to assess toxicity of heavy metal-contaminated water
This study presents a novel algal-based toxicity test suitable for simple and rapid assessment of heavy metal (Hg2+, Cr6+, Cd2+, Pb2+, or As3+)-contaminated water. A closed-system kit-type algal assay was developed using Chlorella vulgaris. Toxicity was assessed by oxygen evolution in the gaseous phase of the assay kits, which was measured via a needle-type oxygen sensor. Initial cell density, light intensity, and exposure time that enabled favorable test performance for the algal assay kits were 103 cells/mL, 250 μmol m-2s-1, and 18 h, respectively.
Results from the heavy metal toxicity tests demonstrate that Hg2+, Cr6+, Cd2+, and Pb2+ are more toxic in inhibiting algal photosynthetic activity than As3+. The 18 h half-maximum effective concentrations (EC50) for Hg2+, Cr6+, Cd2+, Pb2+, and As3+ were determined to be 31.3 ± 0.5, 179.6 ± 7.5, 301.3 ± 6.1, 476.1 ± 10.5, and 2184.1 ± 31.1 μg/L, respectively. A strong correlation between oxygen concentrations in the headspace of the assay kits and chlorophyll a production indicates that oxygen evolution in the gaseous phase is able to represent algal photosynthetic activity and serve as the end-point in algal toxicity tests. High test sensitivity and reproducibility as well as an easy test protocol and rapid processing time make the algal assay kit a suitable tool for simple and rapid toxicity testing of heavy metal-contaminated water.
Sperm chromatin structure assay versus sperm chromatin dispersion kits: Technical repeatability and choice of assisted reproductive technology procedure
Objective: The sperm DNA fragmentation index (DFI) guides the clinician’s choice of an appropriate assisted reproductive technology (ART) procedure. The DFI can be determined using commercially available methodologies, including sperm chromatin dispersion (SCD) kits and sperm chromatin structure assay (SCSA). Currently, when DFI is evaluated using SCD kits, the result is analyzed in reference to the SCSA-derived threshold for the choice of an ART procedure. In this study, we compared DFI values obtained using SCSA with those obtained using SCD and determined whether the difference affects the choice of ART procedure.
Methods: We compared SCSA to two SCD kits, CANfrag (n=36) and Halosperm (n=31), to assess the DFI values obtained, the correlations between tests, the technical repeatability, and the impact of DFI on the choice of ART.
Results: We obtained higher median DFI values using SCD kits than when using SCSA, and this difference was significant for the CANfrag kit (p<0.001). The SCD kits had significantly higher coefficients of variation than SCSA (p<0.0001). In vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) would be chosen for a significantly higher proportion of patients if a decision were made based on DFI derived from SCD rather than DFI determined using SCSA (p=0.003).
Conclusion: Our results indicate that SCD kit-specific thresholds should be established in order to avoid the unnecessary use of IVF/ICSI based on sperm DNA damage for the management of infertility. Appropriate measures should be taken to mitigate the increased variability inherent to the methods used in these tests.
