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Biomedical subjects

H K Dillon

Publications and source records attributed to H K Dillon.

8 recordsLinked to original sources
PubMed2001

Development and characterization of a molecular viability assay for Pneumocystis carinii f sp hominis.

Pneumocystis carinii pneumonia (PCP) remains the most common opportunistic infection among human immunodeficiency virus-infected persons. Despite this, little is known concerning the transmission dynamics of this infection. In the absence of a reliable method to isolate and culture P. carinii from environmental samples, it has not been possible to assess the importance of person-to-person transmission in the epidemiology of PCP. A molecular viability assay was developed for the human form of P. carinii (P. carinii f sp hominis) that is applicable to both clinical specimens and environmental samples. This assay will enable the evaluation of the spread and persistence of viable human P. carinii in the environment.

AIDS-Related Opportunistic Infections↗
PubMed2001

Magnetic bead capture eliminates PCR inhibitors in samples collected from the airborne environment, permitting detection of Pneumocystis carinii DNA.

PCR detection methods are useful in studies of organisms not amenable to culture. Inhibitors in environmental samples can interfere with such assays. We describe a magnetic bead DNA capture protocol that removes inhibitors from outdoor air samples, maintaining the sensitivity of a 16S Pneumocystis carinii mitochondrial rRNA gene-based PCR.

Air Microbiology↗
PubMed1999

Review of methods applicable to the assessment of mold exposure to children.

This article presents discussion of the assessment of the exposure of children to fungi, substances derived from fungi, and the environmental conditions that may lead to exposure. The principles driving investigations of fungal contamination and subsequent exposure are presented as well as guidelines for conducting these investigations. A comprehensive description of available research sampling and analysis techniques is also presented.

Air Pollution, Indoor↗
PubMed1998

An environmental chamber for investigating the evaporation of volatile chemicals.

An inexpensive test chamber has been constructed that provides an environment appropriate for testing the effects of temperature and chemical interactions on gaseous emissions from test solutions. Temperature, relative humidity, and ventilation rate can be controlled and a well-mixed atmosphere can be maintained. The system is relatively simple and relies on heated tap water or ice to adjust the temperature. Temperatures ranging from 9 to 21 degrees C have been maintained. At an average temperature of 15.1 degrees C, temperatures at any location within the chamber vary by no more than 0.5 degree C, and the temperature of the test solution within the chamber varies by no more than 0.1 degree C. The temperatures within the chamber are stable enough to generate precise steady-state concentrations. The wind velocities within the chamber are reproducible from run to run. Consequently, the effect of velocity on the rate of evaporation of a test chemical is expected to be uniform from run to run. Steady-state concentrations can be attained in less than 1 hour at an air exchange rate of about 5 per hour.

Air Pollutants↗
PubMed1997

Development and evaluation of an inhalable bioaerosol manifold sampler.

This paper describes the development and evaluation of an inhalable bioaerosol manifold sampler for the collection of replicate samples over sequential sampling periods. Wind tunnel experiments at wind velocities < or = 0.6 m/sec (< or = approximately 120 ft/min) and at a sampling velocity of 0.6 m/sec yielded sampling efficiencies within 10% of the American Conference of Governmental Industrial Hygienists' inhalable curve up to particle diameters of about 18 microns and efficiencies within 18% for diameters up to 26 microns. At wind velocities > or = 0.6 m/sec, a sampling velocity of 0.8 m/sec yielded efficiencies that were within 15% of the inhalable curve up to diameters of about 22 microns and within 20% for diameters up to 25 microns. Microscopic counts of 15.6-micron and 25.6-micron monodisperse polystyrene beads aerosolized in the wind tunnel and collected with the manifold sampler yielded precise concentrations (pooled CV = 9.0 and 5.3%, respectively) averaging 115% and 92%, respectively, of measurements with the APS Model 3310 aerodynamic particle sizer. Field tests in a cotton dust environment demonstrated the ability to generate a time/concentration profile of fungal spores similar to that indicated for cotton dust levels determined with horizontal elutriators. Cotton dust was sampled efficiently while cotton fibers were excluded. Field tests on a dairy farm indicated no statistically significant bias (p = 0.72) between spore concentrations determined with the manifold sampler and concentrations determined through a central test port.

Aerosols↗
PubMed1986

Sampling and analytical methods for the determination of monochloroacetic acid in air.

A personal sampling and analytical method has been developed for the determination of monochloroacetic acid (MCA) vapor in air. The sampling procedure is the collection of MCA with a solid sorbent sampling tube packed with silica gel. The MCA is leached from the exposed sorbent into distilled, deionized water and quantitated by ion chromatographic analysis. The method has been validated in the concentration range of 0.35 to 29 mg/m3 in 3-L air samples. The capacity of the silica gel is in the range of 3 to 4 mg of MCA per 100 mg of sorbent, which allows for up to 8 hr of sampling at concentrations greater than 40 mg/m3. There are no significant interferences from glycolic acid, acetic acid, dichloroacetic acid, trichloroacetic acid, fluoride and chloride compounds, or water vapor. The effects on the analytical data due to variations in the temperature and humidity of the test atmosphere, sample storage time and chromatographic parameters have been found to be minimal.

Acetates↗
PubMed1978

Solid sorbent sampler for white phosphorus in air.

A solid sorbent sampling tube packed with Tenax-GC is used with a personal sampling pump to collect samples of white (yellow) phosphorus vapor from air. The phosphorus is leached from the exposed sorbent into xylene and quantitated by gas chromatographic analysis. The capacity of the sorbents is in the range 10 to 20 microgramP4per100 mg of sorbent, which allows for up to 4 hrs of sampling at the OSHA Standard, 0.1 mg/m3. No interferences from red phosphorus, phosphine, water vapor, or other common gases are significant. The effects on the method of variations in temperature, pressure, humidity, sample storage and shipping conditions, and chromatographic parameters were determined.

Adsorption↗