Myeloperoxidase-Oxidized LDL Activates Human Aortic Endothelial Cells through the LOX-1 Scavenger Receptor.

Cardiovascular disease as a result of atherosclerosis is a leading cause of death worldwide. Atherosclerosis is primarily caused by the dysfunction of vascular endothelial cells and the subendothelial accumulation of oxidized forms of low-density lipoprotein (LDL). Early observations have linked oxidized LDL effects in atherogenesis to the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) scavenger receptor. It was shown that LOX-1 is upregulated by many inflammatory mediators and proatherogenic stimuli including cytokines, reactive oxygen species (ROS), hemodynamic blood flow, high blood sugar levels and, most importantly, modified forms of LDL. Oxidized LDL signaling pathways in atherosclerosis were first explored using LDL that is oxidized by copper (Cuox-LDL). In our study, we used a more physiologically relevant model of LDL oxidation and showed, for the first time, that myeloperoxidase oxidized LDL (Mox-LDL) may affect human aortic endothelial cell (HAEC) function through the LOX-1 scavenger receptor. We report that Mox-LDL increases the expression of its own LOX-1 receptor in HAECs, enhancing inflammation and simultaneously decreasing tubulogenesis in the cells. We hypothesize that Mox-LDL drives endothelial dysfunction (ED) through LOX-1 which provides an initial hint to the pathways that are initiated by Mox-LDL during ED and the progression of atherosclerosis.

Toxins and Antibiotic Resistance in Staphylococcus aureus Isolated from a Major Hospital in Lebanon.

Molecular characterization of Staphylococcus aureus is of both clinical and infection control importance. Virulence determinants using PCR and multiple drug resistance profiles were studied in 130 S. aureus isolates. PCR-RFLP analysis of the 16S-23S DNA spacer region was done to investigate the level of 16S-23S ITS (internal transcribed spacer) polymorphism. Methicillin-resistant S. aureus (MRSA), which represented 72% of the studied isolates, showed multiple drug resistance with 18% being resistant to 10-18 of the drugs used compared to a maximum resistance to 9 antibiotics with the methicillin sensitive S. aureus (MSSA) isolates. Exfoliative toxin A (ETA) was more prevalent than B (ETB) with virulent determinants being additionally detected in multiple drug-resistant isolates. 16S-23S ITS PCR-RFLP combined with sequencing of the primary product was successful in generating molecular fingerprints of S. aureus and could be used for preliminary typing. This is the first study to demonstrate the incidence of virulent genes, ACME, and genetic diversity of S. aureus isolates in Lebanon. The data presented here epitomize a starting point defining the major genetic populations of both MRSA and MSSA in Lebanon and provide a basis for clinical epidemiological studies.