Browsing by Author "Sammour, Yasser"

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    DEK, a nuclear protein, is chemotactic for hematopoietic stem/progenitor cells acting through CXCR2 and Gαi signaling
    (Wiley, 2022) Capitano, Maegan L.; Sammour, Yasser; Ropa, James; Legendre, Maureen; Mor-Vaknin, Nirit; Markovitz, David M.; Microbiology and Immunology, School of Medicine
    Few cytokines/growth modulating proteins are known to be chemoattractants for hematopoietic stem (HSC) and progenitor cells (HPC); stromal cell-derived factor 1α (SDF1α/CXCL12) being the most potent known such protein. DEK, a nuclear DNA-binding chromatin protein with hematopoietic cytokine-like activity, is a chemotactic factor attracting mature immune cells. Transwell migration assays were performed to test whether DEK serves as a chemotactic agent for HSC/HPC. DEK induced dose- and time-dependent directed migration of lineage negative (Lin–) Sca-1+ c-Kit+ (LSK) bone marrow (BM) cells, HSCs and HPCs. Checkerboard assays demonstrated that DEK's activity was chemotactic (directed), not chemokinetic (random migration), in nature. DEK and SDF1α compete for HSC/HPC chemotaxis. Blocking CXCR2 with neutralizing antibodies or inhibiting Gαi protein signaling with Pertussis toxin pretreatment inhibited migration of LSK cells toward DEK. Thus, DEK is a novel and rare chemotactic agent for HSC/HPC acting in a direct or indirect CXCR2 and Gαi protein-coupled signaling-dependent manner.
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    Dual Coronary-Pulmonary Artery Fistula in a Patient with Severe Bicuspid Aortic Valve Stenosis
    (Houston Methodist DeBakey Heart & Vascular Center, 2023-04-10) Bou Chaaya, Rody G.; Sammour, Yasser; Thakkar, Samarthkumar; Jaradat, Ziad; Gill, William J.; Batal, Omar; Medicine, School of Medicine
    A 62-year-old male presented to the emergency department with acute viral bronchitis and worsening of his chronic dyspnea on exertion. Incidentally, a murmur was detected on physical examination. Extensive work-up, including coronary computed tomography angiography, revealed a rare combination and potential association between severe bicuspid aortic valve stenosis and coronary-pulmonary artery fistulas.