Learn More
  • Qiang Ma
  • Annual review of pharmacology and toxicology
  • 2013
Organismal life encounters reactive oxidants from internal metabolism and environmental toxicant exposure. Reactive oxygen and nitrogen species cause oxidative stress and are traditionally viewed as being harmful. On the other hand, controlled production of oxidants in normal cells serves useful purposes to regulate signaling pathways. Reactive oxidants are(More)
Activation of the aryl hydrocarbon receptor (AhR) by 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD), a potent agonist of AhR, induces a marked reduction in steady state AhR. To analyze the mechanism of regulation of ligand-activated AhR, we examined the biochemical pathway and function of the down-regulation of the receptor by TCDD. Pulse-chase experiments(More)
The utilization of molecular oxygen as the terminal electron acceptor for energy production has in many ways shaped the evolution of complex life, physiology, and certain disease processes. The generation of reactive oxygen species (ROS), either as by-products of O(2) metabolism or by specialized enzymes, has the potential to damage cellular components and(More)
TCDD (2,3,7,8-tetrachlorodibenzo- p -dixoin) induces phase II drug-metabolizing enzyme NQO1 [NAD(P)H:quinone oxidoreductase; EC 1.6.99.2; DT-diaphorase] in a wide range of mammalian tissues and cells. Here, we analysed the molecular pathway mediating NQO1 induction by TCDD in mouse hepatoma cells. Inhibition of protein synthesis with CHX (cycloheximide)(More)
CYP1A1 and 1A2 play critical roles in the metabolic activation of carcinogenic polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic amines/amides (HAAs), respectively, to electrophilic reactive intermediates, leading to toxicity and cancer. CYP1As are highly inducible by PAHs and halogenated aromatic hydrocarbons via aryl hydrocarbon(More)
Carbon nanotubes (CNTs) are novel materials with unique electronic and mechanical properties. The extremely small size, fiberlike shape, large surface area, and unique surface chemistry render their distinctive chemical and physical characteristics and raise potential hazards to humans. Several reports have shown that pulmonary exposure to CNTs caused(More)
The CYP1A1 gene encodes microsomal cytochrome P4501A1 that catalyzes the metabolism of many xenobiotics, including the oxygenation of polycyclic aromatic hydrocarbons (PAH). Induction of CYP1A1 enhances the metabolism of PAHs, and therefore, represents an adaptive response to chemical exposure in mammalian cells. Mechanistic studies reveal an AhR/DRE(More)
Induction of drug-metabolizing enzymes through the antioxidant response element (ARE)-dependent transcription was initially implicated in chemoprevention against cancer by antioxidants. Recent progress in understanding the biology and mechanism of induction revealed a critical role of induction in cellular defense against electrophilic and oxidative stress.(More)
With the development of positioning technologies and the boosting deployment of inexpensive location-aware sensors, large volumes of trajectory data have emerged. However, efficient and scalable query processing over trajectory data remains a big challenge. We explore a new approach to this target in this paper, presenting a new framework for query(More)
The ubiquitous toxic metalloid arsenic elicits pleiotropic adverse and adaptive responses in mammalian species. The biological targets of arsenic are largely unknown at present. We analyzed the signaling pathway for induction of detoxification gene NAD(P)H-quinone oxidoreductase (Nqo1) by arsenic. Genetic and biochemical evidence revealed that induction(More)