Chemical and Cellular Formation of Reactive Oxygen Species from Secondary Organic Aerosols in Epithelial Lining Fluid.

INTRODUCTION: Oxidative stress mediated by reactive oxygen species (ROS) is a key process for adverse aerosol health effects. Secondary organic aerosols (SOA) account for a major fraction of particulate matter with aerodynamic diameter ≤2.5 µm (PM2.5). PM2.5 inhalation and deposition into the respiratory tract causes the formation of ROS by chemical reactions and phagocytosis of macrophages in the epithelial lining fluid (ELF), but their relative contributions are not well quantified and their link to oxidative stress remains uncertain. The specific aims of this project were (1) elucidating the chemical mechanism and quantifying the formation kinetics of ROS in the ELF by SOA; (2) quantifying the relative importance of ROS formation by chemical reactions and macrophages in the ELF. METHODS: SOA particles were generated using reaction chambers from oxidation of various precursors including isoprene, terpenes, and aromatic compounds with or without nitrogen oxides (NOx). We collected size-segregated PM at two highway sites in Anaheim, CA, and Long Beach, CA, and at an urban site in Irvine, CA, during two wildfire events. The collected particles were extracted into water or surrogate ELF that contained lung antioxidants. ROS generation was quantified using electron paramagnetic resonance (EPR) spectroscopy with a spin-trapping technique. PM oxidative potential (OP) was also quantified using the dithiothreitol assay. In addition, kinetic modeling was applied for analysis and interpretation of experimental data. Finally, we quantified cellular superoxide release by RAW264.7 macrophage cells upon exposure to quinones and isoprene SOA using a chemiluminescence assay as calibrated with an EPR spin-probing technique. We also applied cellular imaging techniques to study the cellular mechanism of superoxide release and oxidative damage on cell membranes. RESULTS: Superoxide radicals (·O2-) were formed from aqueous reactions of biogenic SOA generated by hydroxy radical (·OH) photooxidation of isoprene, ß-pinene, α-terpineol, and d-limonene. The temporal evolution of ·OH and ·O2- formation was elucidated by kinetic modeling with a cascade of aqueous reactions, including the decomposition of organic hydroperoxides (ROOH), ·OH oxidation of primary or secondary alcohols, and unimolecular decomposition of α-hydroxyperoxyl radicals. Relative yields of various types of ROS reflected the relative abundance of ROOH and alcohols contained in SOA, which generated under high NOx conditions, exhibited lower ROS yields. ROS formation by SOA was also affected by pH. Isoprene SOA had higher ·OH and organic radical yields at neutral than at acidic pH. At low pH ·O2- was the dominant species generated by all types of SOA. At neutral pH, α-terpineol SOA exhibited a substantial yield of carbon-centered organic radicals (R·), while no radical formation was observed by aromatic SOA.Organic radicals in the ELF were formed by mixtures of Fe2+ and SOA generated from photooxidation of isoprene, α-terpineol, and toluene. The molar yields of organic radicals by SOA were 5-10 times higher in ELF than in water. Fe2+ enhanced organic radical yields by a factor of 20-80. Ascorbate mediated redox cycling of iron ions and sustained organic peroxide decomposition, as supported by kinetic modeling reproducing time- and concentration-dependence of organic radical formation, as well as by additional experiments observing the formation of Fe2+ and ascorbate radicals in mixtures of ascorbate and Fe3+. ·OH and superoxide were found to be efficiently scavenged by antioxidants.Wildfire PM mainly generated ·OH and R· with minor contributions from superoxide and oxygen-centered organic radicals (RO·). PM OP was high in wildfire PM, exhibiting very weak correlation with radical forms of ROS. These results were in stark contrast with PM collected at highway and urban sites, which generated much higher amounts of radicals dominated by ·OH radicals that correlated well with OP. By combining field measurements of size-segregated chemical composition, a human respiratory tract model, and kinetic modeling, we quantified production rates and concentrations of different types of ROS in different regions of the ELF by considering particle-size-dependent respiratory deposition. While hydrogen peroxide (H2O2) and ·O2- production were governed by Fe and Cu ions, ·OH radicals were mainly generated by organic compounds and Fenton-like reactions of metal ions. We obtained mixed results for correlations between PM OP and ROS formation, providing rationale and limitations of the use of oxidative potential as an indicator for PM toxicity in epidemiological and toxicological studies.Quinones and isoprene SOA activated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in macrophages, releasing massive amounts of superoxide via respiratory burst and overwhelming the superoxide formation by aqueous chemical reactions in the ELF. The threshold dose for macrophage activation was much smaller for quinones compared with isoprene SOA. The released ROS caused lipid peroxidation to increase cell membrane fluidity, inducing oxidative damage and stress. Further increases of doses led to the activation of antioxidant response elements, reducing the net cellular superoxide production. At very high doses and long exposure times, chemical production became comparably important or dominant if the escalation of oxidative stress led to cell death. CONCLUSIONS: The mechanistic understandings and quantitative information on ROS generation by SOA particles provided a basis for further elucidation of adverse aerosol health effects and oxidative stress by PM2.5. For a comprehensive assessment of PM toxicity and health effects via oxidative stress, it is important to consider both chemical reactions and cellular processes for the formation of ROS in the ELF. Chemical composition of PM strongly influences ROS formation; further investigations are required to study ROS formation from various PM sources. Such research will provide critical information to environmental agencies and policymakers for the development of air quality policy and regulation.

Isolation of infectious salmon anemia virus (ISAV) from Atlantic salmon in New Brunswick, Canada.

Infectious salmon anemia virus (ISAV) was isolated at a marine grow-out site in New Brunswick, Canada, from Atlantic salmon Salmo salar which experienced mortalities due to hemorrhagic kidney syndrome (HKS). Of 20 fish sampled in this study, 14 showed histologically various degrees of interstitial hemorrhaging, tubular epithelial degeneration and necrosis, and tubular casts in the posterior kidney, typical of HKS. Posterior kidney and spleen homogenates produced a cytopathic effect on chinook salmon embryo (CHSE-214) cells 10 to 14 d after inoculation. Pleomorphic virus particles in the size range 80 to 120 nm were seen by electron microscopy. The virus was confirmed as ISAV using reverse transcriptase-polymerase chain reaction (RT-PCR). This is a systematic diagnostic study of the isolation of ISAV on the North American continent and the first description of the growth of ISAV on the CHSE-214 cell line.

Trephine bone biopsy system: a refined needle for radiologists.

A new type of bone biopsy unit that uses standard engineering and machinery principles of self cleaning and clearance allows for greater ease and more accurate performance of biopsy. Its use consistently yields excellent biopsy material. Included is a semi-rigid K wire, which may be used with a drill, for ease of insertion and a stylet in a cannula, which allows for multiple biopsies without reinsertion. The needle is compared with standard saw tips (trephines) and sharpened cannulas.

The cervicothoracic junction on chest radiograph.

Fractures of the first rib may be detected by indirect signs, including apical extrapleural fluid collection, pneumothorax, and supraclavicular soft tissue mass. Thoracic outlet syndrome represents a complex series of abnormalities that may be clarified utilizing digital subtraction angiography. Major distortions of alignment can produce bony adaptive changes at the cervicothoracic junction simulating intra-spinal canal tumors.

Low-dose direct fibrinolysis in peripheral vascular disease.

One hundred thirty patients underwent low-dose, catheter-directed fibrinolytic therapy for arterial and graft occlusions present for various periods of time. In 65 consecutive patients the therapeutic parameters were identical, and a careful hematologic evaluation was performed. In the subsequent 65 patients, varying doses of fibrinolytic agents were employed. Fibrinolytic therapy was found to be beneficial in a diverse group of clinical situations and in patients whose occlusions had occurred at varying lengths of time. Early study demonstrated that effective fibrinolysis can be achieved at approximately one-twentieth of the systemic level and that systemic effects could be avoided in all patients during 24-hour infusions and in many patients infused up to 96 hours. Bleeding complications occurred only in patients in whom concomitant heparinization was employed, and this was thought to be the causative factor. Therapeutic success and avoiding complications are strongly dependent on close monitoring of patients and joint decision making by the vascular surgeon and radiologist.

A new method for treating carcinomatous biliary obstruction with intracatheter radium.

We describe a new method for relieving biliary obstruction due to malignant solid tumors. The method consists of placement of radium needles in a Ring biliary drainage catheter for three days. After removing the radium needles, the catheter is left in place to allow for repair of irradiated tissues, then it is removed. The object is to leave the patient with a patent biliary tree without a biliary drainage prosthesis. The clinical course of six patients treated by this method is described, and the autopsy findings in three cases are outlined. Three patients died with a serum total bilirubin ranging from 1--4.5 mg/100 ml, two to three months after removing the drainage catheter. Two patients died before the bile drainage catheter could be removed. One patient is alive with a bile drainage catheter in place. Possible modifications in technique and catheters are being considered.

Giant gastric villous adenoma.

Although gastric villous adenomas are relatively rare lesions, rapid or early diagnosis and proper treatment depends upon a thorough knowledge of the characteristic radiographic, clinical and pathologic features.