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Chemical Structure of Lipid A: Recent Advances in Structural Analysis of Biologically Active Molecules
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
Ulrich Zähringer, Buko Lindner, Ernst T. Rietschel
Stereochemistry of β-Hydroxylated Fatty Acids Recently, a new 1H-NMR method has been introduced to determine the absolute configuration of (R)-3-hydroxylated (3-OH) fatty acids (114). This is achieved by investigation of the carboxymethyl protons of the fatty acid methyl ester (COOCH3) in a 1H-NMR spectrum recorded in CDCl3 usually resonating around 3.7 ppm. This signal shifts in a dose-dependent manner to a lower field in the presence of Tris-[3-(heptafluoroprolyl-hy droxymethy lene)-(+)-camphorato] europium(III) as complexing reagent (114). Depending on the shift induced by this reagent and with the help of synthetic reference compounds, the absolute stereo-chemistry of the hydroxylated fatty acid can be determined. The disadvantages of this procedure as compared to a previous method employing (R)-phenylethylamine and GLC analysis (115) are that the methyl ester has to be isolated and purified to homogeneity prior to NMR investigations and that several measurements have to be done for each hydroxy fatty acid being investigated. This is not required in case of the GLC procedure, where 2-hydroxylated fatty acids can be analyzed in the same run. Nevertheless, NMR has been used in order to determine the stereochemistry of 3-hydroxylated fatty acids of Porphyromonas gingivalis (114) and Comamonas testeroni (116), which was shown to be (R) in both cases.
Digital Receptors
Published in Christopher M. Hayre, William A. S. Cox, General Radiography, 2020
The addition of europium changes the structure of the crystal. Consequently, the electrons actually become trapped within the halide portion of the phosphor layer due to defects in the lattice that are present in the crystal as a result of the addition of europium (Fujifilm Imaging Plate Manual, n.d.; Leblans et al., 2011). Subsequently, these defects become traps for the electrons that are leaving the conduction band. The process of electron release (ionization) and capture (energy traps) happens numerous times and is proportional to the X-ray exposure received. This contributes to the formation of the latent image.
Imaging Cell Trafficking with MR Imaging
Published in Martin G. Pomper, Juri G. Gelovani, Benjamin Tsui, Kathleen Gabrielson, Richard Wahl, S. Sam Gambhir, Jeff Bulte, Raymond Gibson, William C. Eckelman, Molecular Imaging in Oncology, 2008
Assaf A. Gilad, Piotr Walczak, Jeff W. M. Bulte, Michael T. McMahon
One example of cell labeling with PARACEST contrast agents was reported by Aime and colleagues. In this study, the same cell line (rat hepatoma) was labeled by incubation for six hours with two different PARACEST contrast materials. One cell population was labeled with Eu-DOTAmGly, while the second population was labeled with Tb-DOTAmGly. Terbium (Tb) and europium (Eu) are both lanthanides. When the cells were imaged in vitro, each cell population was highlighted only after applying a pulse at its specific frequency (42), thus allowing “MR double labeling.”
Establishment of Cell-Based Assay System for Evaluating Cytotoxic Activity Modulated by the Blockade of PD-1 and PD-L1 Interactions with a Therapeutic Antibody
Published in Immunological Investigations, 2023
Haruka Hirosaki, Yosuke Maeda, Masahiro Takeyoshi
Cytotoxic activity was measured using the europium release assay (Zons et al. 1997). The target cells (2 × 106 cells of K562 or PD-L1/K562) were labeled with europium in 200 μL of labeling buffer containing 0.5 mM europium acetate, 2.5 mM diethylenetriaminepentaacetic acid (DTPA), and 25 mM HEPES for 10 min at room temperature. After the addition of 60 μL of 10 mM CaCl2 solution and additional incubation for 10 min, the cells were washed four times in 1 mL of RPMI1640 assay medium supplemented with 10% heat-inactivated FBS. The europium-labeled target cells were seeded into a 96-well U-bottom plate at a density of 5 × 103 cells/100 μL/well, and effector cells (KHYG-1 or TK-PD1) were added to the plate at a density of 1 × 105 cells/100 μL/well in the assay medium. As controls for the spontaneous or maximal release of europium to calculate the cytotoxic activity, 100 μL/well of assay medium or 0.2% Triton X-100 was added to the seeded target cells without effector cells. After 3 h of co-cultivation at 37°C in 5% CO2 humidified air, 20 μL/well of supernatant was transferred to each well of a 96-well flat-bottom plate and 100 μL/well of the enhancement solution (PerkinElmer, Inc., Waltham, MA, USA) was added to each well. After mixing for 5 min, time-resolved fluorescence (TRF) was measured using the Nivo Alpha S microplate reader (PerkinElmer, Inc., Waltham, MA, USA).
Molecular docking study on europium nanoparticles and mussel adhesive protein for effective detection of latent fingerprints
Published in Biomarkers, 2023
T. R. Poorani, C. Ramya, Ramya Manohar
The Europium element whose atomic symbol is Eu and atomic number is 63, is present in Block F, Group 3, Period 6 of the periodic table. Its atomic radius is around 151.964. Each europium shell is filled with the number of electrons of about 2, 8, 18, 25, 8, 2 with an electronic configuration of [Xe]4f76s2. This europium metal belongs to the lanthanide or rare earth series which has an atomic radius of about 180 pm and its Van der Waals radius was about 233 pm. This metal looks like a silvery white and found as a free element in natural environment. Europium nanoparticles (EuNp) also known as nanopowder or nanodots looks like a black spherical particle with higher surface area and are around 10 − 45 nm with the specific surface area (SSA) of about 30 − 50 m2/g. These nanoparticles were also available with the average particle size of 75 − 100 nm. Once these europium nanoparticles were surface functionalised, these can be easily adsorbed onto the surface interface by chemically interacting polymers. The chemical structure of the europium nanoparticles synthesised and its interaction with Mussel adhesive protein amino acid is represented in the Figure 1.
An overview of multiplexed analyses of CAR T-cell therapies: insights and potential
Published in Expert Review of Proteomics, 2021
Brittany Paige DePriest, Noah Vieira, Alan Bidgoli, Sophie Paczesny
Immunoassays have widespread use in both hospitals and the laboratory, measuring concentrations of molecules based on antigen-antibody reactions. However, most conventional immunoassays are performed in established laboratories using bulky conventional equipment and well-trained staff, limiting widespread access. POC immunoassays are urgently needed to provide more time and cost-effective testing along with expanded access to healthcare facilities. At this time, CAR-T therapy biomarker POC testing is limited to the recently developed IL-6 specific lateral flow assays, also known as immunochromatographic assays [47]. Huang et al. used europium nanoparticles (Eu-np) as a label with the basis of a conventional sandwich immunoassay. Results were available in 15 minutes. The strips yielded adequate sensitivity at 0.37 pg/mL IL-6 and demonstrated significantly high (p < 0.01) correlation when compared to the traditional Siemens IL-6 ELISA kit [47]. Similar results using lateral flow assay for POC testing (Milenia QuickLine IL-6) were found by Schefold et al. and correlation with standard ELISA testing was also found to be significant (p < 0.001) [48]. Proxim Diagnostics has also created POC IL-6 testing but instead uses a handheld device with an indwelling ELISA cartridge [49].