Publications by authors named "Gan Luan"

Optimizing the deployment of roadside units (RSUs) holds great potential for enhancing the delay performance of vehicular ad hoc networks. However, there has been limited focus on devising RSU deployment strategies tailored specifically for highway intersections. In this study, we introduce a novel probabilistic model to characterize events occurring around highway intersections.

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Cancer is the second leading cause of human death across the world. Tripartite motif (TRIM) family, with E3 ubiquitin ligase activities in majority of its members, is reported to be involved in multiple cellular processes and signaling pathways. TRIM proteins have critical effects in the regulation of biological behaviors of cancer cells.

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When bacterial cells are exposed to increasing concentrations of quinolone-class antibacterials, survival drops, reaches a minimum, and then recovers, sometimes to 100%. Despite decades of study, events underlying this paradoxical high-concentration survival remain obscure. Since reactive oxygen species (ROS) have been implicated in antimicrobial lethality, conditions generating paradoxical survival were examined for diminished ROS accumulation.

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The quinolones are potent antibacterials that act by forming complexes with DNA and either gyrase or topoisomerase IV. These ternary complexes, called cleaved complexes because the DNA moiety is broken, block replication, transcription, and bacterial growth. Cleaved complexes readily form in vitro when gyrase, plasmid DNA, and quinolone are combined and incubated; complexes are detected by the linearization of plasmid DNA, generally assayed by gel electrophoresis.

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Nutrient starvation usually halts cell growth rather than causing death. Thymine starvation is exceptional, because it kills cells rapidly. This phenomenon, called thymineless death (TLD), underlies the action of several antibacterial, antimalarial, anticancer, and immunomodulatory agents.

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Fluoroquinolones form drug-topoisomerase-DNA complexes that rapidly block transcription and replication. Crystallographic and biochemical studies show that quinolone binding involves a water/metal-ion bridge between the quinolone C3-C4 keto-acid and amino acids in helix-4 of the target proteins, GyrA (gyrase) and ParC (topoisomerase IV). A recent cross-linking study revealed a second drug-binding mode in which the other end of the quinolone, the C7 ring system, interacts with GyrA.

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Unlabelled: Ribosomal elongation factor 4 (EF4) is highly conserved among bacteria, mitochondria, and chloroplasts. However, the EF4-encoding gene, lepA, is nonessential and its deficiency shows no growth or fitness defect. In purified systems, EF4 back-translocates stalled, posttranslational ribosomes for efficient protein synthesis; consequently, EF4 has a protective role during moderate stress.

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Widespread fluoroquinolone resistance has drawn attention to quinazolinediones (diones), fluoroquinolone-like topoisomerase poisons that are unaffected by common quinolone-resistance mutations. To better understand differences between quinolones and diones, we examined their impact on the formation of cleaved complexes (drug-topoisomerase-DNA complexes in which the DNA moiety is broken) with gyrase, one of two bacterial targets of the drugs. Formation of cleaved complexes, measured by linearization of a circular DNA substrate, required lower concentrations of quinolone than dione.

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DNA gyrase and topoisomerase IV control bacterial DNA topology by breaking DNA, passing duplex DNA through the break, and then resealing the break. This process is subject to reversible corruption by fluoroquinolones, antibacterials that form drug-enzyme-DNA complexes in which the DNA is broken. The complexes, called cleaved complexes because of the presence of DNA breaks, have been crystallized and found to have the fluoroquinolone C-7 ring system facing the GyrB/ParE subunits.

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Granulysin is a cytolytic, proinflammatory protein produced by human cytolytic T-lymphocytes and natural killer cells. Granulysin has two stable isoforms with molecular weight of 9 and 15 kDa; the 9-kDa form is a result of proteolytic maturation of the 15-kDa precursor. Recombinant 9-kDa granulysin exhibits cytolytic activity against a variety of microbes, such as bacteria, parasites, fungi, yeast and a variety of tumor cell lines.

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