Survival of cells with bleomycin-induced chromosomal lesions in the cultured lymphocytes of lung cancer patients

OBJECTIVE: To investigate whether persistent T lymphocyte activation is a feature of steroid-resistant (SR) asthma and to study the inhibitory effects of dexamethasone and other immuno-inhibiting agents on PHA-induced proliferation of peripheral blood T lymphocytes from SR and steroid-sensitive (SS) asthmatics. MATERIAL AND METHODS: 15 SR and 15 SS asthmatics were studied. Serum levels of soluble interleukin-2 receptor (sIL-2R) were measured before and after prednisone therapy by an enzyme-linked immunosorbent assay. PHA-driven proliferative assay was performed to evaluate inhibition of T lymphocyte proliferation. RESULTS: Serum levels of sIL-2R were elevated in both patients with SR and SS asthma as compared with normal controls (P < 0.001). After a 7-day course of prednisone (20 mg/day), serum levels of sIL-2R decreased significantly in SS asthmatics (P < 0.001) but not in SR asthmatics (P > 0.1). Proliferation of T lymphocytes from the sensitive but not the resistant asthmatics was significantly (P < 0.002) inhibited by dexamethasone (10 mol/L), reflecting a shift of the dose-response curve. In contrast, oxymatrine and thymus-derived immunosuppressors inhibited proliferation of T lymphocytes to a similar degree between SR and SS asthmatics. CONCLUSIONS: The results suggest that persistent T lymphocyte activation due to a relative insensitivity of the cells to glucocorticoids is a feature of SR asthma. Immuno-inhibiting agents other than glucocorticoids may be of therapeutic benefit in patients with SR asthma.     

Excitation with a focused, pulsed optical beam in scattering media: diffraction effects

To gain a better understanding of the spatiotemporal problems that are encountered in two-photon excitation fluorescence imaging through highly scattering media, we investigate how diffraction affects the three-dimensional intensity distribution of a focused, pulsed optical beam propagating inside a scattering medium. In practice, the full potential of the two-photon excitation fluorescence imaging is unrealized at long scattering depths, owing to the unwanted temporal and spatial broadening of the femtosecond excitation light pulse that reduces the energy density at the geometric focus while it increases the excitation energy density in the out-of-focus regions. To analyze the excitation intensity distribution, we modify the Monte Carlo-based photon-transport model to a semi-quantum-mechanical representation that combines the wave properties of light with the particle behavior of the propagating photons. In our model the propagating photon is represented by a plane wave with its propagation direction in the scattering medium determined by the Monte Carlo technique. The intensity distribution in the focal region is given by the square of the linear superposition of the various plane waves that arrive at different incident angles and optical path lengths. In the absence of scattering, the propagation model yields the intensity distribution that is predicted by the Huygens-Fresnel principle. We quantify the decrease of the energy density delivered at the geometric focus as a function of the optical depth to the mean-free-path ratio that yields the average number of scattering events that a photon encounters as it propagates toward the focus. Both isotropic and anisotropic scattering media are considered. Three values for the numerical aperture (NA) of the focusing lens are considered: NA = 0.25, 0.5, 0.75.     

Design and operation of pilot plant for CO2 capture from IGCC flue gases by combined cryogenic and hydrate method

This project is a trial conducted under contract with CO₂CRC, Australia of a new CO₂ capture technology that can be applied to integrated gasification combined cycle power plants and other industrial gasification facilities. The technology is based on combination of two low temperature processes, namely cryogenic condensation and the formation of hydrates, to remove CO₂ from the gas stream. The first stage of this technology is condensation at −55 °C where CO₂ concentration is expected to be reduced by up to 75 mol%. Remaining CO₂ is captured in the form of solid hydrate at about 1 °C reducing CO₂ concentration down to 7 mol% using hydrate promoters. This integrated cryogenic condensation and CO₂ hydrate capture technology hold promise for greater reduction of CO₂ emissions at lower cost and energy demand. Overall, the process produced gas with a hydrogen content better than 90 mol%. The concentrated CO₂ stream was produced with 95-97 mol% purity in liquid form at high pressure and is available for re-use or sequestration. The enhancement of carbon dioxide hydrate formation and separation in the presence of new hydrate promoter is also discussed. A laboratory scale flow system for the continuous production of condensed CO₂ and carbon dioxide hydrates is also described and operational details are identified.     

Photooxidation processes for an azo dye in aqueous media: modeling of degradation kinetic and ecological parameters evaluation

Three photooxidation processes, UV/H(2)O(2), UV/S(2)O(8)(2-) and UV/O(3) were applied to the treatment of model wastewater containing non-biodegradable organic pollutant, azo dye Acid Orange 7 (AO7). Dye degradation was monitored using UV/VIS and total organic carbon (TOC) analysis, determining decolorization, the degradation/formation of naphthalene and benzene structured AO7 by-products, and the mineralization of model wastewater. The water quality during the treatment was evaluated on the bases of ecological parameters: chemical (COD) and biochemical (BOD(5)) oxygen demand and toxicity on Vibrio fischeri determining the EC(50) value. The main goals of the study were to develop an appropriate mathematic model (MM) predicting the behavior of the systems under investigation, and to evaluate the toxicity and biodegradability of the model wastewater during treatments. MM developed showed a high accuracy in predicting the degradation of AO7 when considering the following observed parameters: decolorization, formation/degradation of by-products and mineralization. Good agreement of the data predicted and the empirically obtained was confirmed by calculated standard deviations. The biodegradability of model wastewater was significantly improved by three processes after mineralizing a half of the initially present organic content. The toxicity AO7 model wastewater was decreased as well. The differences in monitored ecological parameters during the treatment indicated the formation of different by-products of dye degradation regarding the oxidant type applied.     

Synthesis and characterization of indium monoselenide (InSe) nanowires

Indium monoselenide (InSe) nanowires were grown by the thermal evaporation method in argon atmosphere without the presence of any catalysts using InSe polycrystalline powder as the source material. No nanostructure growth was observed at deposition temperatures below 580 °C. The nanostructures were discernable at temperatures above 620 °C. Pure InSe nanowires were obtained at the deposition temperature of 660 °C for 50 min. The diameters of the nanowires were from 50 to 240 nm and their lengths were up to several micrometers. X-ray diffraction spectrum reveals that the synthesized products were single-crystalline of the β-phase hexagonal structure of InSe with lattice constants a = 4.006 Å and c = 16.642 Å. The strong peak due to the reflection from the (004) crystal plane reveals that most nanowires grow with a strong preferred orientation.     

Continuous analysis of dissolved gaseous mercury in freshwater lakes

The concentration of dissolved gaseous mercury (DGM) in freshwaters changes more quickly than the 40-min processing time of current analytical methods. A new method for continuous field analysis of DGM was developed using a Tekran 2537A to achieve a DGM analysis time of 5 min. Samples were concurrently analyzed for temperature, oxygen, conductivity, pH, and oxidation-reduction potential using a Hydrolab. The detection limit for DGM ranged between 5 and 20 fmolL(-1) with 99% removal efficiency. Control experiments showed that there was no interference due to methyl mercury, which is present in similar concentrations to DGM. Controlled experiments comparing continuous DGM analysis with discrete DGM analysis showed that the results are not significantly affected by typical variations in water temperature (4-30 degrees C), oxidation-reduction potential (135-355 mV), dissolved organic carbon (4.5-10.5 mgL(-1)), or pH (3.5-7.8). The continuous analysis was within 4.5% of the discrete analysis when compared across 12 samples analyzed in triplicate. The field performance of this method was tested over two 48-h periods in two lakes in Kejimkujik Park, Nova Scotia where over 1000 data points were collected.     

Dynamic component chemiluminescent sensor for assessing circulating polymorphonuclear leukocyte activity of peritoneal dialysis patients

Recurrent bacterial peritonitis is a major complication in peritoneal dialysis (PD) patients, which is associated with polymorphonuclear leukocyte (PMN) functional changes and can be assessed by a chemiluminescent (CL) reaction. We applied a new approach of a dynamic component chemiluminescence sensor for the assessment of functional states of PMNs in a luminol-amplified whole-blood system. This method is based on the evaluation of CL kinetic patterns of stimulated PMNs, while the parallel measurements of intracellular and extracellular production of reactive oxygen species (ROS) from the same sample can be conducted. Blood was drawn from diabetic and nondiabetic patients during follow-up, and during peritonitis. Healthy medical personnel served as the control group. Chemiluminescence curves were recorded and presented as a sum of three biological components. CL kinetic parameters were calculated, and functional states of PMNs were assessed. Data mining algorithms were used to build decision tree models that can distinguish between different clinical groups. The induced classification models were used afterward for differentiating and classifying new blind cases and demonstrated good correlation with medical diagnosis (84.6% predictive accuracy). In conclusion, this novel method shows a high predictive diagnostic value and may assist in detection of PD-associated clinical states.     

Bioaccessibility of metal cations in soil is linearly related to its water exchange rate constant

Site-specific risk assessments often incorporate the concepts of bioaccessibility (i.e., contaminant fraction released into gastrointestinal fluids) or bioavailability (i.e., contaminant fraction absorbed into systemic circulation) into the calculation of ingestion exposure. We evaluated total and bioaccessible metal concentrations for 19 soil samples under simulated stomach and duodenal conditions using an in vitro gastrointestinal model. We demonstrated that the median bioaccessibility of 23 metals ranged between <1 and 41% under simulated stomach conditions and < 1 and 63% under simulated duodenal conditions. Notably, these large differences in metal bioaccessibility were independent of equilibrium solubility and stability constants. Instead, the relationship (stomach phase R = 0.927; duodenum phase R = 0.891) between bioaccessibility and water exchange rates of metal cations (k(H?O)) indicated that desorption kinetics may influence if not control metal bioaccessibility.     

Fertilization stimulates anaerobic fuel degradation of antarctic soils by denitrifying microorganisms

Human activities in the Antarctic have resulted in hydrocarbon contamination of these fragile polar soils. Bioremediation is one of the options for remediation of these sites. However, little is known about anaerobic hydrocarbon degradation in polar soils and the influence of bioremediation practices on these processes. Using a field trial at Old Casey Station, Antarctica, we assessed the influence of fertilization on the anaerobic degradation of a 20-year old fuel spill. Fertilization increased hydrocarbon degradation in both anaerobic and aerobic soils when compared to controls, but was of most benefit for anaerobic soils where evaporation was negligible. This increased biodegradation in the anaerobic soils corresponded with a shift in the denitrifier community composition and an increased abundance of denitrifiers and benzoyl-CoA reductase. A microcosm study using toluene and hexadecane confirmed the degradative capacity within these soils under anaerobic conditions. It was observed that fertilized anaerobic soil degraded more of this hydrocarbon spike when incubated anaerobically than when incubated aerobically. We conclude that denitrifiers are actively involved in hydrocarbon degradation in Antarctic soils and that fertilization is an effective means of stimulating their activity. Further, when communities stimulated to degrade hydrocarbons under anaerobic conditions are exposed to oxygen, hydrocarbon degradation is suppressed. The commonly accepted belief that remediation of polar soils requires aeration needs to be reevaluated in light of this new data.