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Biomedical subjects

D R Douglas

Publications and source records attributed to D R Douglas.

9 recordsLinked to original sources
PubMed2005

Detection of airborne Stachybotrys chartarum macrocyclic trichothecene mycotoxins on particulates smaller than conidia.

Highly respirable particles (diameter, <1 microm) constitute the majority of particulate matter found in indoor air. It is hypothesized that these particles serve as carriers for toxic compounds, specifically the compounds produced by molds in water-damaged buildings. The presence of airborne Stachybotrys chartarum trichothecene mycotoxins on particles smaller than conidia (e.g., fungal fragments) was therefore investigated. Cellulose ceiling tiles with confluent Stachybotrys growth were placed in gas-drying containers through which filtered air was passed. Exiting particulates were collected by using a series of polycarbonate membrane filters with decreasing pore sizes. Scanning electron microscopy was employed to determine the presence of conidia on the filters. A competitive enzyme-linked immunosorbent assay (ELISA) specific for macrocyclic trichothecenes was used to analyze filter extracts. Cross-reactivity to various mycotoxins was examined to confirm the specificity. Statistically significant (P < 0.05) ELISA binding was observed primarily for macrocyclic trichothecenes at concentrations of 50 and 5 ng/ml and 500 pg/ml (58.4 to 83.5% inhibition). Of the remaining toxins tested, only verrucarol and diacetylverrucarol (nonmacrocyclic trichothecenes) demonstrated significant binding (18.2 and 51.7% inhibition, respectively) and then only at high concentrations. The results showed that extracts from conidium-free filters demonstrated statistically significant (P < 0.05) antibody binding that increased with sampling time (38.4 to 71.9% inhibition, representing a range of 0.5 to 4.0 ng/ml). High-performance liquid chromatography analysis suggested the presence of satratoxin H in conidium-free filter extracts. These data show that S. chartarum trichothecene mycotoxins can become airborne in association with intact conidia or smaller particles. These findings may have important implications for indoor air quality assessment.

Air Microbiology↗
PubMed1996

A pharmacokinetic comparison of acetaminophen products (Tylenol Extended Relief vs regular Tylenol)

OBJECTIVE: To compare the pharmacokinetics of Tylenol Extended Relief (ER APAP) with those of immediate-release acetaminophen (IR APAP) at supratherapeutic doses. METHODS: A prospective, double-blind, randomized, crossover comparison trial involving 14 adult volunteers. Each subject ingested 75 mg/kg of either ER APAP or IR APAP and 1 week later received the other APAP preparation. On both occasions plasma APAP concentration ([APAP]) was determined 0.5, 1, 2, 3, 4, 6, 8, 12, and 16 hours after ingestion. The times to maximum [APAP] (Tmax); the maximum [APAP] values (Cmax); the elimination half-lives 4-16 hours postingestion (t1/2), and the areas under the [APAP] vs time curve (AUC) for ER APAP and IR APAP were compared using the paired t-test. RESULTS: All the subjects completed both study phases. The mean APAP dose ingested was 5.6 g (range 4.2-7.8 g). Both the AUC and the Cmax were less after ER APAP than after IR APAP; otherwise, there was no evident difference in any measure. Graphically, ER APAP yielded a flatter, plateau-shaped curve initially, but after 4 hours the curve was nearly identical to that for IR APAP. Results are summarized in the table: [table: see text] CONCLUSION: In this model involving a single supratherapeutic dose, ER APAP evidenced no pharmacokinetic features that would suggest the need for an alternate poisoning screening strategy. When compared with IR APAP, ER APAP had a lower AUC, all peak [APAP] occurred in < 4 hours, and terminal eliminations were identical. The data suggest that, in most cases, the diagnostic approach to an overdose of ER APAP need not deviate from that used for an IR APAP overdose.

Acetaminophen↗
PubMed1975

Occurrence of spontaneous hemorrhagic necrosis of the central nervous system in fetal hamsters.

Lesions of hamster fetal neuraxial tissues, characterized by multifocal and coalescent zones of hemorrhage, edema, and necrosis in the cerebral mantle, brainstem, and spinal cord, were observed in experiments designed to test the teratogenicity of potato preparations. Retrospective and prospective data indicated, however, that the potato preparations were not responsible but that the disease occurred spontaneously in the colony and was associated with direct breeding contact of virgin females with certain males. Observations suggest that an infectious agent may be responsible, but no agent was recovered. Immunofluorescence assay of inoculated cultures indicated that reovirus was not present in affected fetal tissues.

Animals↗
PubMedDate not supplied

Efficacy of chlorine dioxide as a gas and in solution in the inactivation of two trichothecene mycotoxins.

The efficacy of chlorine dioxide (ClO2) in detoxifying two potential bioterrorism agents, the trichothecene mycotoxins verrucarin A and roridin A, was evaluated. In the first experiment, verrucarin A (1, 5, or 10 microg) and roridin A (5 or 10 microg) were each inoculated onto square-inch sections of glass, paper, and cloth and exposed to 1000 ppm of ClO2 for either 24 or 72 h at room temperature. In the second experiment, verrucarin A and roridin A (1 or 2 ppm in water) were treated with 200, 500, or 1000 ppm ClO2 for up to 116 h at room temperature in light and dark conditions (N = 9 per treatment for test and control). A yeast assay using Kluyveromyces marxianuswas used to quantify the toxicity of verrucarin A and roridin A. Additionally, high-performance liquid chromatography was performed on selected samples. Results for the first experiment showed that ClO2 treatment had no detectable effect on either toxin. For the second experiment, both toxins were completely inactivated at all tested concentrations in as little as 2 h after treatment with 1000 ppm ClO2. For verrucarin A, an effect was seen at the 500 ppm level, but this effect was not as strong as that observed at the 1000 ppm level. Roridin A toxicity was decreased after treatment with 200 and 500 ppm ClO2, but this was not significant until the 24-h exposure time was reached. These data show that ClO2 (in solution) can be effective for detoxification of roridin A or verrucarin A at selected concentrations and exposure times.

Bioterrorism↗