Publications by authors named "Nabil El-Zein"

Article Synopsis
  • The study focuses on the spread of the Omicron variant of COVID-19, emphasizing the need for quick and effective detection methods.
  • Researchers designed a low-cost and fast RT-qPCR technique using SYBR Green to identify specific mutations in the Omicron variant, rather than relying on expensive genomic sequencing.
  • Testing of 120 clinical samples confirmed the presence of these mutations and validated the new detection method, which could help contain the spread of the variant in areas where it is prevalent.
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Hyperglycemia exerts various harmful effects on the vasculature. Studies have shown an association between the levels of the adipokines leptin and adiponectin (APN) and vascular complications in diabetes mellitus. The aim of our study was to investigate the molecular mechanisms mediated by APN and leptin that are involved in hyperglycemia-induced vascular remodeling, especially at the level of oxidative stress and actin cytoskeleton dynamics.

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Objective And Design: This study is aimed at uncovering the signaling pathways activated by vasoactive intestinal peptide in human macrophages MATERIALS: Human peripheral blood mononuclear cell-derived macrophages were used for the in vitro investigation of the VIP-activated signaling pathways.

Methods And Treatment: Time-course and dose-response experiments and siRNA were used in human macrophages co-challenged with various concentrations of VIP and different MAPK pharmacologic inhibitors to investigate signaling pathways activated by VIP. Flow analysis was performed to assess the levels of CD11b, CD35 and CD66.

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Recently the first genome sequences for 11 SARS-CoV-2 isolates from Lebanon became available. Here, we report the detection of variants within the genome of these strains. Pairwise alignment analysis using blastx was performed between these sequences and the UniProtKB data for the SARS-CoV-2 coronavirus to identify amino acid variations.

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Aerobic glycolysis, known as the "Warburg effect", is one of several hallmarks of cancer cells. The conversion of phosphoenolpyruvate (PEP) to pyruvate can be down regulated by the re-expression of the embryonic isoform 2 of pyruvate kinase (PKM2). This mechanism allows the accumulation of glycolytic intermediates for the biosynthesis of macromolecules, such as proteins, lipids and nucleic acids.

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Damage to podocytes is a key event in glomerulopathies. While energy dense food can contribute to kidney damage, the role of the orixegenic hormone "ghrelin" in podocyte biology is still unknown. In the present study, we investigated the effect of ghrelin on podocyte survival as well as the signalling pathways mediating ghrelin effect in immortalized cultured rat podocytes.

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Regulatory T cells (Tregs) are central for maintaining immune balance and their dysfunction drives the expansion of critical immunologic disorders. During the past decade, microRNAs (miRNAs) have emerged as potent regulators of gene expression among which immune-related genes and their immunomodulatory properties have been associated with different immune-based diseases. The miRNA signature of human peripheral blood (PB) CD8 CD25 CD127 Tregs has not been described yet.

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PACAP has opposing roles ranging from activation to inhibition of tumor growth and PACAP agonists/antagonists could be used in tumor therapy. In this study, the effect of PACAP stimulation on signaling pathways was investigated in MCF-7 human adenocarcinoma breast cancer cells. Results showed that MCF-7 cells express VPAC1 and VPAC2, but not PAC1, receptors.

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Objective And Design: The objective of this study is to uncover the signal transduction pathways of N-formyl methionyl-leucyl-phenylalanine (fMLP) in monocyte.

Materials Or Subjects: Freshly isolated human peripheral blood monocytes (PBMC) were used for in vitro assessment of signal transduction pathways activated by fMLP.

Treatment: Time-course and dose-response experiments were used to evaluate the effect of fMLP along with the specific inhibitors/stimulators on the activation of downstream signaling kinases.

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Thyroxine (T) enters the brain either directly across the blood-brain barrier (BBB) or indirectly the choroid plexus (CP), which forms the blood-cerebrospinal fluid barrier (B-CSF-B). In this study, using isolated perfused CP of the sheep by single-circulation paired tracer and steady-state techniques, T4 transport mechanisms from blood into lateral ventricle CP has been characterized as the first step in the transfer across the B-CSF-B. After removal of sheep brain, the CPs were perfused with I-T and C-mannitol.

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Interferon gamma (IFN-ɣ) is a pleiotropic cytokine which plays dual contrasting roles in cancer. Although IFN-ɣ has been clinically used to treat various malignancies, it was recently shown to have protumorigenic activities. Reactive oxygen species (ROS) are overproduced in cancer cells, mainly due to NADPH oxidase activity, which results into several changes in signaling pathways.

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EGFR and VEGFR pathways play major roles in solid tumor growth and progression, however, little is known about these pathways in haematological tumors. This study investigated the crosstalk between EGFR and VEGFR2 signaling in two hematological in vitro models: THP1, a human monocytic leukemia, and Raji, a Burkitt's lymphoma, cell lines. Results showed that both cell lines express EGFR and VEGFR2 and responded to EGF stimulation by activating EGFR, triggering VEGF production and phosphorylating ERK, AKT, and p38 very early, with a peak of expression at 10-20min.

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Introduction: Adiponectin (APN), an adipocytokine, exerts protective effects on cardiac remodeling, while angiotensin II (Ang II) induces hypertension and vascular remodeling. The potential protective role of APN on the vasculature during hypertension has not been fully elucidated yet. Here, we evaluate the molecular mechanisms of the protective role of APN in the physiological response of the vascular wall to Ang II.

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Cancer cells secrete VEGF, which plays a key role in their growth, invasion, extravasation and metastasis. Direct cancer cell-endothelial cell interaction, mediated by gap junctions, is of critical importance in the extravasation process. In this study, we evaluated avastin (Av), an anti-VEGF antibody; and oleamide (OL), a gap junction inhibitor, using MDA-MB-231 human breast cancer cells in vitro and a xenograft murine model in vivo.

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Objectives. Hollow space between implant and abutment may act as reservoir for commensal and/or pathogenic bacteria representing a potential source of tissue inflammation. Microbial colonization of the interfacial gap may ultimately lead to infection and bone resorption.

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IFN-γ is a cytokine with important roles in the innate and adaptive immune responses. This cytokine is secreted by activated T cells, NK cells and macrophages. Studies on the regulation of human IFN-γ expression had been previously focused on the promoter region.

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Regulatory T cells (Tregs) are characterized by a high expression of IL-2 receptor α chain (CD25) and of forkhead box P3 (FOXP3), the latter being essential for their development and function. Another major player in the regulatory function is the cytotoxic T-lymphocyte associated molecule-4 (CTLA-4) that inhibits cytotoxic responses. However, the regulation of CTLA-4 expression remains less well explored.

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The G-protein coupled receptor (GPCR) fMLP receptor (FPR) and the two receptors tyrosine kinase (RTK), the nerve growth factor (NGF) receptor TrkA and the epidermal growth factor (EGF) receptor (EGFR) are involved in reactive oxygen species (ROS), matrix metalloproteinase-9 (MMP-9) production and CD11b membrane integrin upregulation. We show that in monocytes the three receptors crosstalk each other to modulate these pro-inflammatory mediators. Tyrphostin AG1478, the EGFR inhibitor, inhibits fMLP and NGF-associated ROS production, fMLP-associated CD11b upregulation and NGF-induced TrkA phosphorylation; K252a, the NGF receptor inhibitor, inhibits fMLP or EGF-associated ROS production, CD11b expression and EGF-induced EGFR phosphorylation; cyclosporine H, the FPR inhibitor inhibits EGF or NGF-associated ROS production, EGF-associated CD11b upregulation and prevents EGFR and TrkA phosphorylation by their respective ligand EGF and NGF.

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Regulatory T cells (Tregs) play a key role in immune system homeostasis and tolerance to antigens, thereby preventing autoimmunity, and may be partly responsible for the lack of an appropriate immune response against tumor cells. Although not sufficient, a high expression of forkhead box P3 (FOXP3) is necessary for their suppressive function. Recent reports have shown that histones deacetylase inhibitors increased FOXP3 expression in T cells.

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Mature dendritic cells (DCs) represent, by far, the most potent antigen-presenting cells. The development of clinical grade techniques to produce them in large numbers has rendered possible their use in clinical trials. It is therefore crucial to assess the DCs characteristics according to the methodology used to generate them, to improve the comparison and standardization of these trials.

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Treg are the main mediators of dominant tolerance. Their mechanisms of action and applications are subjects of considerable debate currently. However, a human microRNA (miR) Treg signature has not been described yet.

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The CD4+ T-cell malignancy induced by human T-cell leukemia virus type 1 (HTLV-I) infection and termed; Adult T-cell Leukemia lymphoma (ATLL), is caused by defects in the mechanisms underlying cell proliferation and cell death. In the CD4+ T-cells, calcium ions are central for both phenomena. ATLL is associated with a marked hypercalcemia in many patients.

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The neuropeptide vasoactive intestinal peptide (VIP) regulates the exocytosis of secretory granules in a wide variety of cells of neuronal and non-neuronal origin. In human monocytes, we show that the proinflammatory effects of VIP are associated with stimulation of exocytosis of secretory vesicles as well as tertiary (gelatinase) granules with, respectively, up-regulation of the membrane expression of the beta2 integrin CD11b, the complement receptor 1 (CD35), and the matrix metalloproteinase-9 (MMP-9). Using the low-affinity formyl peptide receptor-like 1 (FPRL1) antagonist Trp-Arg-Trp-Trp-Trp-Trp (WRW4) and the exchange protein directly activated by cAMP (EPAC)-specific compound 8CPT-2Me-cAMP and measuring the expression of Rap1 GTPase-activating protein as an indicator of EPAC activation, we found that the proinflammatory effect of VIP is mediated via the specific G protein-coupled receptor VIP/pituitary adenylate cyclase-activating protein (VPAC1) receptor as well as via FPRL1: VIP/VPAC1 interaction is associated with a cAMP increase and activation of a cAMP/p38 MAPK pathway, which regulates MMP-9, CD35, and CD11b exocytosis, and a cAMP/EPAC/PI-3K/ERK pathway, which regulates CD11b expression; VIP/FPRL1 interaction results in cAMP-independent PI-3K/ERK activation with downstream integrin up-regulation.

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In human neutrophils, the neuropeptide pituitary adenylate cyclase activating polypeptide (PACAP) acting via the G protein-coupled receptors vasoactive intestinal peptide/PACAP receptor 1 (VPAC-1) and formyl peptide receptor-like 1 (FPRL1) modulates Ca2+ and pro-inflammatory activities. We evaluated in human monocytes the importance of the Ca2+ signal and the participation of FPRL1 in PACAP-associated signaling pathways and pro-inflammatory activities. PACAP-evoked Ca2+ transient involved both Ca2+ influx and intracytoplasmic Ca2+ mobilisation.

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