ScopeMaillard reaction products (MRPs) are believed to interact with the receptor for advanced glycation endproducts (RAGE) and lead to a pro‐inflammatory cellular response. The structural basis for this interaction is scarcely understood. This study investigates the effect of individual lysine modifications in free form or bound to casein on human colon cancer cells.Methods and resultsSelectively glycated casein containing either protein‐bound N‐ε‐carboxymethyllysine (CML), N‐ε‐fructosyllysine (FL), or pyrraline is prepared and up to 94%, 97%, and 61% of lysine modification could be attributed to CML, FL, or pyrraline, respectively. HCT 116 cells are treated with free CML, pyrraline, FL, or modified casein for 24 h. Native casein is used as control. Intracellular MRP content is analyzed by UPLC‐MS/MS. Microscopic analysis of the transcription factors shows no activation of NFκB by free or protein‐bound FL or CML, whereas casein containing protein‐bound pyrraline activates Nrf2. RAGE expression is not influenced by free or casein‐bound MRPs. Activation of Nrf2 by pyrraline‐modified casein is confirmed by analyzing Nrf2 target proteins NAD(P)H dehydrogenase (quinone 1) (NQO1) and heme oxygenase‐1 (HO‐1).ConclusionStudies on the biological effects of glycated proteins require an individual consideration of defined structures. General statements on the effect of “AGEs” in biological systems are scientifically unsound.
S. Mü ller W. Uhl (corresponding author) Institute of Urban Water Management (ISI), Chair of Water Supply Engineering,The treatment of raw water by hybrid coagulation-ultrafiltration was investigated. Coagulationultrafiltration removed high molecular weight organics, preferentially humics. Adsorption of the trace compound cis-1,2-dichloroethene, present in raw water, on granular activated carbon was improved considerably as compounds competing for adsorption space had been removed.This was shown in isotherms and breakthrough curves. Aeration during filtration did not affect membrane performance as expressed in permeability. However, aeration in the submerged membrane container resulted in a release of organic matter from the flocs, which resulted in higher concentrations of dissolved organic carbon in the filtrate. ABBREVIATIONS BV bed volumes (m 3 m 23 ) c concentration (mg l 21 or mol l 21 ) c 0 initial concentration (mg l 21 ) c eq liquid-phase concentration at adsorption equilibrium (mg l 21 ) CDOC chromatographic detectable organic carbon (ppb) DCE cis-1,2-dichloroethene (mg l 21 ) DOC dissolved organic carbon (mg l 21 or ppb) FNU formazine nephelometric unit GAC granular activated carbon HPC heterotrophic plate count (ml 21 ) HOC hydrophobic organic carbon (ppb) K F Freundlich parameter (mg g 21 ) LC-OCD liquid chromatography-organic carbon detection l det detection limit m mass of adsorbent (mg) MWCO molecular weight cut-off (Dalton) n number of measurements n F Freundlich exponent NOM natural organic matter OC organic carbon (ppb) P membrane permeability (l m 22 h 21 kPa 21 ) P 0 initial permeability (l m 22 h 21 kPa 21 ) q solid-phase concentration at adsorption equilibrium (mg g 21 ) TMP transmembrane pressure (hPa or kPa) TOC total organic carbon (ppb) UF ultrafiltration UVA 254 ultra violet absorbance at 254 nm (m 21 )
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