In this study we have investigated the presence on endothelial cells of potential glycoprotein receptors, other than P-selectin, which are involved in the adhesion of monocytes at the early stages of activation. We report that the majority of cells binding to thrombin-activated endothelial cells from a peripheral blood mononuclear cell (PBMC) preparation are monocytes. The adhesion of PBMC to thrombin-activated, but not resting, endothelial cells was inhibited (66%) by a monoclonal antibody (mAb) directed against alpha v beta 3. Elutriated monocytes or a monocytic cell line (U937) were also inhibited by this antibody, its F(ab)'2 fragments and three other anti-(alpha v beta 3) mAbs. alpha v beta 3 isolated from endothelial-cell lysates significantly inhibited the adhesion of monocytes and U937 cells to endothelial cells. A peptide motif (RGDF) known to interact with alpha v beta 3 inhibited U937 cell adhesion to activated endothelial cells by 53%. Finally, an anti-(P-selectin) mAb (LYP20) or a platelet-activating factor (PAF)-receptor antagonist (WEB 2086) inhibited monocyte adhesion to activated endothelial cells. This study shows for the first time that alpha v beta 3 is implicated, in addition to P-selectin and PAF, in the adhesion of monocytes to activated endothelial cells.
The development of a scalable telescoped continuous flow procedure for the acetylation and nitration of 4-fluoro-2-methoxyaniline is described. A subsequent batch deprotection then affords 4-fluoro-2-methoxy-5-nitroaniline, a key building block in the synthesis of osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) that is used for the treatment of nonsmall-cell lung carcinomas carrying EGFR-TKI sensitizing and EGFR T790M resistance mutations. The hazards associated with nitration of organic compounds, such as thermal runaway and explosivity of intermediates, make it difficult to scale up nitrations to industrial quantities, particularly within large-scale batch reactors. In this study, we investigated an acetic acid/aqueous nitric acid mixture as a predominantly kinetically controlled nitration regime and a water-free mixture of acetic acid, fuming nitric acid, and fuming sulfuric acid (oleum) as a mass-transfer-limited nitration regime. A modular microreactor platform with in-line temperature measurement was utilized for the nitration. Furthermore, we identified that it was necessary to protect the amine functionality through acetylation to avoid side reactions. The process parameters and equipment configuration were optimized at laboratory scale for the acetylation and nitration to improve the product yield and purity. The two steps could be successfully telescoped, and the laboratory-scale flow process was operated for 80 min to afford the target molecule in 82% isolated yield over two steps, corresponding to a throughput of 25 mmol/h. The developed flow process was then transferred to an industrial partner for commercial implementation and scaled up by the use of higher flow rates and sizing-up of the microreactor platform to pilot scale to afford the product in 83% isolated yield, corresponding to a throughput of 2 mol/h (0.46 kg/h).
A novel approach to prepare the core structure of Aspidosperma and Strychnos alkaloids is described. The strategy is based on a cyclization cascade involving the formation of quaternary carbon center followed by trapping of the radical intermediate by an aryl azide to build the 5-membered ring of the pyrrolocarbazole system. This reaction is run with triethylborane without the need for any hydrogen atom donor such as a tin hydride or tris(trimethylsilyl)silane, and it furnishes the tetracyclic framework as a single diastereomer. The influence of different N-protecting groups on the starting iodoacetamide has been examined.
Platelets were metabolically labelled with 32P and the phosphoproteins examined by two-dimensional non-reduced/reduced gel electrophoresis and isoelectric-focusing/gel electrophoresis. Comparison with similar separations of surface-labelled platelets showed that the only major glycoprotein which is phosphorylated is the beta-subunit of glycoprotein Ib, indicating that this subunit contains a cytoplasmic segment. The identification was confirmed using immunoblotting with an antibody to the beta-subunit. Phosphoserine was the principal phosphorylation site, with some phosphothreonine, but phosphotyrosine was absent. No quantitative or qualitative differences could be detected in the phosphorylation of glycoprotein Ib beta from resting or activated platelets. These results exclude changes in phosphorylation of the major platelet membrane glycoproteins as a method of signal transmission by these receptors.
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