Blood
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Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) and T-cell/histiocyte-rich B-cell lymphoma (T/HRBCL) are distinct tumors and are treated differently. They are linked by a morphologic and probably a biologic continuum, which renders the differential diagnosis difficult. To develop criteria to distinguish the entities along the morphologic continuum, we correlated the lymph node architecture and immunophenotype of both tumor cells and reactive components of 235 neoplasms in the spectrum of NLPHL and T/HRBCL with clinical data. ⋯ Tumor cells either were loosely scattered or formed clusters, thus resembling areas of either T/HRBCL or inflammatory diffuse large BCL (DLBCL) within the nodules. Patients with these NLPHLs with T-cell/histiocyte-rich nodules presented at a high stage and with B symptoms, as in T/HRBCL, but had an excellent survival, as in NLPHL. This morphologic pattern suggests a biologic continuum between NLPHL and T/HRBCL.
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Iron regulatory proteins (IRP1 and IRP2) are RNA-binding proteins that affect the translation and stabilization of specific mRNAs by binding to stem-loop structures known as iron responsive elements (IREs). IREs are found in the 5'-untranslated region (UTR) of ferritin (Ft) and mitochondrial aconitase (m-Aco) mRNAs, and in the 3'-UTR of transferrin receptor (TfR) and divalent metal transporter-1 (DMT1) mRNAs. Our previous studies show that besides iron, IRPs are regulated by hypoxia. ⋯ During the late phase of hypoxia, IRP2 RNA-binding activity increases, becoming the dominant regulator responsible for decreasing Ft synthesis. During reoxygenation (ReO2), Ft protein increases concomitant with a decrease in IRP2 RNA-binding activity. The data suggest that the differential regulation of IRPs during hypoxia may be important for cellular adaptation to low oxygen tension.
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Protease-activated receptors (PARs) are stimulated by proteolytic cleavage of their extracellular domain, unmasking a new N-terminus acting as tethered ligand. Whereas the role of PARs in platelets is well known, their presence and function in human monocytes and other antigen-presenting cells has not been characterized. Here it is demonstrated that human peripheral monocytes and monocyte-derived macrophages and dendritic cells differentially express PARs. ⋯ Stimulation of PAR1, PAR2, and PAR3 with thrombin, trypsin, or established receptor-activating peptides (PAR-APs) triggered cytosolic Ca2+ responses, indicating functionally active PARs. Further, stimulation of monocytes or macrophages with thrombin or PAR1-AP, but not with PAR2-or PAR4-AP, triggers expression of monocyte chemoattractant protein-1 (MCP-1) both at the mRNA and the protein level. These data demonstrate that differentiation of human monocytes is associated with differential expression of functionally active PARs that mediate distinct regulatory functions in inflammation and atherogenesis.