Peat fires and air quality: volatile organic compounds and particulates.

There are numerous localized peat deposits on the Swan Coastal Plain, an urban and rural bioregion otherwise dominated by wetland ecosystems in southwestern Australia. Hydrological change is significant in the bioregion: urban development encroaches on wetlands, groundwater extraction provides the city population with most of its water, and rainfall declines will not recharge aquifers in the future. The wetland processes which contribute to the formation of these peat deposits have therefore changed and are becoming vulnerable to fire events with residents increasingly exposed to peat smoke. There is an imperative to characterise this peat smoke to determine if exposures are harmful or toxic, and opportunities to do so in this setting arise due to the absence of bushfire smoke which has confounded other international studies. We have measured volatile organic compounds (VOCs) and particulate concentrations from an opportunistic assessment of two peat fires. SUMMA canister grab samples and a portable GCMS were used to determine the VOCs with high 1h benzene concentrations of 16 and 30 ppm v/v. PM10 and PM2.5 particulate data were collected using an Osiris continuous analyser with 24h concentrations recorded at varying time periods (within a 5 months timeframe) ranging from 1h maximums of between 23-37 microgm(-3) for PM10 and 50.5-106 microgm(-3) for PM2.5. While the 24h averages were generally below national air quality standards, elevated 1h concentrations were observed on numerous occasions and on most days. Given the proximity of residential development to many peat deposits, a drying climate and the increased risk of arson in peri-urban environments, the health impacts of exposure to peat smoke need to be determined and if necessary measures developed to prevent exposure (which would include maintaining wetland sediment integrity so as to reduce its vulnerability to fire).

Human exposure to metals in groundwater affected by acid sulfate soil disturbance.

The disturbance and oxidation of sulfidic soils can cause an increase in acidity resulting in the mobilization of high concentrations of metals in groundwater or connected surface water. This is an increasing problem in urban areas of Australia and internationally. We hypothesized that the risks of exposure to contaminated water would be increased by this phenomenon. We undertook a preliminary investigation of human exposure to metals recruiting 27 residents in an acid sulfate soil-affected area, 21 residents using a bore (groundwater) for home-grown produce irrigation, and 6 residents who did not. Participants completed a questionnaire and provided a sample of urine (first morning void), toenails (from all 10 toes), hair, and borewater. Only hair metal concentrations were higher in those using bore water and ranged from below detection (

Preconcentration of radium isotopes from natural waters using MnO2 Resin.

We have characterized "MnO2 Resin," a new resin developed by the PG Research Foundation, for radium adsorption over wide ranges of pH, reaction times and salt concentrations. We show that the sorption of 133Ba (used as a proxy for Ra) is highly dependent on pH with the most useful range from pH 4 to 8. The surface layers of the Mn oxides apparently become more positively charged under acidic conditions (below pH 4), which prevents diffusion of positively charged alkaline earth species (e.g. Ba2+, Ra2+) into the sorption sites. Adsorption at higher pH is thought to be inhibited because of carbonate complexation. We found that the sorption characteristics for radium onto MnO2 Resin are especially favorable for low-salinity waters but the sorption is still very satisfactory for highly salted solutions (KD=2.8x10(4) in both cases) but with slower kinetics. For analytical purposes, both column and pump experiments showed high recoveries with no measurable discrimination between Ra and Ba regardless of flow rates in fresh water. Seawater tests showed that recoveries of Ra and Ba are lower than fresh water at elevated flow rates with Ra adsorption higher than Ba at flow rates above 10 ml/min.

Personnel protection during aerosol ventilation studies using radioactive technetium (Tc99m)

Two commercially available nebulizing devices used for ventilation studies were evaluated. The nebulizers use radioactive Technetium-99m (Tc99m), a potential source of room air contamination. Ambient air concentrations of Tc99m were monitored, as were the exposures of department personnel not performing ventilation studies. Room surfaces and air vents were examined to determine the extent of contamination in the examination room. Personnel were evaluated for contamination on clothing, hair, and airways when hospital lab coats and latex gloves were the only protective apparel used. Though the maximum permissible concentration of 4 x 10(-5) microCi/c3 was not exceeded, preliminary results indicated levels as high as 11,000 disintegrations/min in the nasal passages of personnel. These findings clearly demonstrate the need for more effective personal protective devices. Personnel contamination resulted primarily from the patient, due to an inability to maintain a proper oral seal on the nebulizer mouthpiece. Conventional hospital surgical masks were ineffective in reducing internal deposition to tolerable levels. By comparison, levels were reduced by 19% (p > 0.10) through use of methods such as simple body substance isolation techniques and high-efficiency disposable respirators. Levels approaching 50 disintegrations/min or less were obtainable (p < 0.001), and overall levels of Tc99m were reduced by 78%.

Efficacy of DMP 840: a novel bis-naphthalimide cytotoxic agent with human solid tumor xenograft selectivity.

DMP 840, a novel bis-naphthalimide, was evaluated for antitumor efficacy in several tumor models in mice. As measured by a tumor growth inhibition assay, i.v. administration of DMP 840 to athymic nude mice at doses at or below the maximum tolerated dose resulted in curative activity against four human solid tumor xenografts, MX-1 mammary carcinoma, CX-1 and DLD-2 colon adenocarcinomas, and LX-1 lung carcinoma, producing full or incomplete regressions and/or percent tumor growth inhibition of > or = 96%. The efficacy of DMP 840 in the models was dose dependent. The activity of DMP 840 against the human tumors surpassed that demonstrated by several clinically used and investigational anticancer agents. In long-term growth delay studies, DMP 840 induced full regressions in 20 of 20 mice bearing MX-1 tumors, and tumors in one-half of these mice remained regressed for over 5 months. In addition, DMP 840 was curative against exponentially growing DLD-2 tumors staged at 500 mg and MX-1 tumors staged at 1000 mg. The bis-naphthalimide was equally efficacious when administered i.v. or i.p. but was slightly less active after oral dosing. Against both the MX-1 mammary carcinoma and the DLD-2 colon adenocarcinoma, some measure of schedule dependence was observed; the optimum schedule was daily for 9 days. Against L1210 and P388 murine leukemias, DMP 840 demonstrated little or no activity and was inactive against B16 murine melanoma. Overall, these results suggest that DMP 840 may be a human solid tumor selective cytotoxic agent.

A bifurcated endobronchial tube in the management of laryngotracheo-oesophageal cleft repair.

We describe the management of laryngotracheo-oesophageal cleft Type III using a bifurcated endobronchial tube. When the cleft was opened for repair, we were able to obtain effective control of the airway, which is the main problem in this rare congenital anomaly. Commercial tubes are not available, so we made the tube on the day of surgery, immediately before operation.

Expression of protein F, the fibronectin-binding protein of Streptococcus pyogenes JRS4, in heterologous streptococcal and enterococcal strains promotes their adherence to respiratory epithelial cells.

In a previous study we reported the identification of protein F, a fibronectin-binding protein that was essential to the ability of Streptococcus pyogenes JRS4 to adhere to respiratory epithelial cells (E. Hanski and M. Caparon, Proc. Natl. Acad. Sci. USA, 89:6172-6176, 1992). To further evaluate the role of protein F in the adherence of the group A streptococci, we screened other group A streptococcal strains, including six recent clinical isolates, and one strain of Enterococcus faecalis for their capacity to bind fibronectin and for the presence of the gene encoding protein F (prtF). Seven of eight group A streptococcal strains analyzed, including all recent clinical isolates, both bound fibronectin at high affinity and contained DNA sequences that hybridized with a prtF-specific probe. One group A streptococcal isolate and the strain of E. faecalis examined neither contained a prtF-related gene nor bound fibronectin. These two strains also could not efficiently adhere to respiratory epithelial cells. However, upon the introduction of the cloned prtF gene, both of these strains gained the capacity to bind fibronectin and to adhere to respiratory epithelial cells. These results suggest that protein F is an important adhesin, which may have a general role in the virulence of the group A streptococci.

Activation of soluble guanylate cyclase by NO-hemoproteins involves NO-heme exchange. Comparison of heme-containing and heme-deficient enzyme forms.

The mechanism of activation of soluble guanylate cyclase purified from bovine lung by high molecular weight, nitrosyl-hemoprotein complexes is reported. Heme-containing, heme-deficient, and heme-reconstituted forms of guanylate cyclase were studied. Nitric oxide (NO) and nitroso compounds activated heme-containing and heme-reconstituted enzymes (over 50-fold), with an accompanying shift in the Soret absorption peak from 431 to 398 nm, but failed to activate or alter the spectral characteristics of heme-deficient enzyme. In contrast, preformed NO-hemoprotein complexes as well as low molecular weight NO-heme activated all forms of guanylate cyclase. Heme-deficient guanylate cyclase was first reacted with excess amounts of NO-hemoglobin, NO-myoglobin, or NO-catalase and then rapidly separated from the NO-hemoprotein by column chromatography. Spectrophotometric analysis indicated that the NO-heme moiety was transferred from each of the NO-hemoproteins to heme-deficient guanylate cyclase. Approximately 1 mol of NO-heme was bound per mol of holoenzyme and the specific activity of this enzyme form was over 50-fold greater than that of unreacted, heme-deficient enzyme. NO-heme was tightly bound to guanylate cyclase as no transfer of enzyme-bound NO-heme to apohemoglobin was evident. Enzyme activated by NO-hemoproteins closely resembled, kinetically, that activated by NO or NO-heme. In contrast, reactions between heme-deficient guanylate cyclase and hemoproteins did not result in heme transfer, whereas heme alone rapidly reconstituted the enzyme. These observations indicate that soluble guanylate cyclase can be readily reconstituted with, and thereby activated by, NO-heme through an exchange reaction with NO-hemoproteins.

The effects of amrinone on human platelet aggregation: evidence that amrinone does not act through a cyclic nucleotide mechanism in platelet rich plasma.

The purpose of the present study was to investigate in human platelet rich plasma the effects of amrinone, a cardiotonic agent, on platelet aggregation induced by ADP, arachidonic acid (AA), collagen, prostaglandin H2 (PGH2), and U46619, a substance reported to mimic the actions of thromboxane A2. Amrinone inhibited aggregatory responses to all substances studied in a dose-related fashion and this is the first report demonstrating the inhibitory actions of amrinone on platelet aggregation induced by PGH2. Although amrinone inhibited aggregatory responses to ADP, collagen, PGH2, and U46619 at similar doses, markedly lower doses of amrinone were necessary to inhibit aggregatory responses to AA. Furthermore, amrinone did not alter cAMP and cGMP levels in human platelet rich plasma. The present data demonstrate that amrinone inhibits human platelet aggregation induced by a variety of substances and independent of changes in cAMP and cGMP levels. Furthermore, the present data suggest that amrinone selectively inhibits aggregatory responses to arachidonic acid prior to the formation of thromboxane A2.

Influence of verapamil and diltiazem on aggregatory responses in cat and rabbit platelet rich plasma.

The effects of verapamil and diltiazem, calcium channel blockers, on aggregatory responses to ADP, arachidonic acid (AA), U46619, a thromboxane A2 mimic, and prostaglandin H2 (PGH2) were investigated in cat and rabbit platelet rich plasma. Results of the present study demonstrate that verapamil and diltiazem inhibit cat or rabbit platelet aggregation induced by ADP, AA, U46619, and PGH2. Furthermore, the present experiments provide the first reported data showing the inhibitory actions of calcium channel blockers on aggregatory responses to PGH2, the pivotal endoperoxide intermediate of arachidonic acid metabolism. Since verapamil and diltiazem at similar concentrations inhibited aggregatory responses to a similar degree in platelet rich plasma from cat or rabbit, the present data indicate that the influence of verapamil and diltiazem on platelet aggregation may be independent of species studied as well as nonspecific in nature.

Modes in misaligned unstable resonators.

A previously developed technique for the calculation of modes of perfectly aligned unstable resonators in the limit of large Fresnel number is here extended to include effects of misalignment. It is shown how asymptotic techniques may be employed to simplify the calculation of near- and far-field patterns produced by such modes. The basic conclusion is that rectangular aperture unstable resonators are quite insensitive to misalignment, in the sense that the lowest-loss mode continues to be essentially diffraction limited as long as the feedback mirror remains well within the output beam.