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Biomedical subjects

W G Palmer

Publications and source records attributed to W G Palmer.

18 recordsLinked to original sources
PubMed1997

Bioavailability of TNT residues in composts of TNT-contaminated soil.

Composting is being explored as a means to remediate 2,4,6-trinitrotoluene (TNT) contaminated soils. This process appears to modify TNT and to bind it to organic matter. The health hazards associated with dusts generated from such materials cannot be predicted without knowing if the association between TNT residues and compost particulate is stable in biological systems. To address this question, single doses of [14C]-TNT, soil spiked with [14C]-TNT, or compost generated with [14C]-TNT-spiked soils were administered to rats by intratracheal instillation. The appearance of 14C in urine and tissues was taken as an indication of the bioavailability of TNT residues from compost particles. In rats instilled with neat [14C]-TNT, about 35% of the 14C dose appeared in urine within 3 d. The 14C excreted in urine by these rats decreased rapidly thereafter, and was undetectable by 4 wk after treatment. Similar results were obtained with soil-treated rats. In contrast, after treatment with [14C]-TNT-labeled compost, only 2.3% of the total 14C dose appeared in urine during the first 3 d. Low levels of 14C continued to be excreted in urine from compost-treated rats for more than 6 mo, and the total amount of 14C in urine was comparable to that in TNT-treated animals. Determination of the radiolabel in tissues showed that 14C accumulated in the kidneys of rats treated with labeled compost but not in rats treated with [14C]-TNT or [14C]-TNT-spiked soil. These results indicate that the association between TNT and particulate matter in compost is not stable when introduced into the lungs. Accumulation of 14C in kidneys suggests the presence of a unique TNT residue in compost-treated rats. The rate of excretion and tissue disposition of 14C in rats treated with TNT-spiked soil indicate that TNT in soil is freely available in the lungs.

Animals↗
PubMed1994

Mutagenicity of particulate emissions from the M16 rifle: variation with particle size.

Emissions generated by firing the M16 rifle with the propellant WC844 in a combustion chamber designed to simulate conditions of actual use were tested for mutagenic activity in the Salmonella/Ames assay. Dimethyl sulfoxide extracts of emissions collected from either the breech or muzzle end of the rifle were mutagenic in three strains of Salmonella (TA1537, TA1538, and TA98) both in the presence and absence of metabolic activation systems (S9). The extracts were negative in strains TA100 and TA102. Aerosols generated by firing the M16 rifle were fractionated according to aerodynamic diameter. Submicrometer particles were far more mutagenic than particles with aerodynamic diameters between 1 and 15 microns. The mutagens associated with the smaller particles were more active in the presence of S9, while extracts of larger particles were as active, or more active, in the absence of S9. Heavier particles, which settled rapidly out of the airstream, were not mutagenic.

Firearms↗
PubMed1985

Analysis of emissions collected from four types of iron casting molds.

The levels of polycyclic aromatic hydrocarbons (PAH) and related compounds, phenols and particulates were determined in emissions collected from iron casting molds composed of four different types of chemical binders: furan, urethane, green sand with sea coal and phenol-formaldehyde resins in shell molds. The shell sample, with 50% particulates, contained the most water-soluble material; green sand, 25% particulates; furan, 10% particulates; and urethane, less than 2% particulate material. The portion of the particulate fraction soluble in cyclohexane varies from 16 to 36% between mold types; emissions from urethane and furan molds contained the lowest quantities of cyclohexane-soluble components and of PAH and related compounds. Phenol, which was found in all four foundry samples, was present in the highest concentration in emissions from urethane molds. Shell mold emissions contained the highest levels of 2- and 4-nitrophenol.

Air Pollutants, Occupational↗
PubMed1984

Metabolism of 7,12-dimethylbenz(a)anthracene by alveolar macrophages containing ingested ferric oxide, aluminum oxide or carbon particles.

Rat alveolar macrophages with ingested aluminum oxide (Al2O3), ferric oxide (Fe2O3) or carbon particles were incubated for 24 hours with 3H-7, 12-dimethylbenz(a)anthracene (DMBA). Essentially the same amounts and types of metabolites were produced by and released from macrophages with ingested Fe2O3 and Al2O3 particles. Smaller quantities of DMBA and its metabolites could be extracted with ethyl acetate from the culture media and cell lysates of macrophages with ingested carbon particles than from those with Fe2O3 and Al2O3 particles. Also, more of the intracellular radioactivity was associated with insoluble material in macrophages with ingested carbon than in those with the other two types of particles. The results suggest that the inability of Al2O3 to act as a co-carcinogenic carrier for polycyclic aromatic hydrocarbons (PAH) is not related to its effect on PAH metabolism. However, adsorption of PAH and their nonpolar metabolites to carbon may alter the exposure pattern of pulmonary tissues to PAH and their metabolites.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

An innovative approach to sampling complex industrial emissions for use in animal toxicity tests: application to iron casting operations.

Sampling of complex mixtures of airborne contaminants for chronic animal toxicity tests often involves numerous sampling devices, requires extensive sampling time, and yields forms of collected materials unsuitable for administration to animals. A method is described which used a high volume, wet venturi scrubber for collection of respirable fractions of emissions from iron foundry casting operations. The construction and operation of the sampler are presented along with collection efficiency data and its application to the preparation of large quantities of samples to be administered to animals by intratracheal instillation.

Air Pollutants↗
PubMed1981

Lung cancer in ferrous foundry workers: a review.

Epidemiologic studies indicate that an increased incidence of lung cancer may be associated with specific work areas in ferrous foundries. With the exception of crane operators, who were found to have an elevated lung cancer rate in one foundry, the excess lung cancer incidence is generally confined to molders, casters, and cleaning room operators whose lung cancer risk is two- to threefold higher than that of standard populations. These studies reflect conditions that existed in the foundries several decades ago. The lung cancer risk today may differ as a result of the introduction of new foundry practices and the use of new molding materials. Benzo(a)pyrene and certain other polycyclic aromatic hydrocarbons have been found in many locations in the foundries. It is not known if tumor promoters, co-carcinogens, or other classes of chemical carcinogens are present. The contribution of tobacco smoke to the lung cancer risk of ferrous foundry workers is also unknown. Current studies are examining the composition and long-term health effects of emissions from molds composed of modern synthetic chemical molding materials as well as those from the more traditional green sand molds.

Animals↗
PubMed1981

Reproducibility of serum haptoglobin profiles in mice with transplanted tumors.

To determine whether the elevation of serum haptoglobin (Hp) elicited by many tumors is associated with properties of the tumor, Hp levels were determined during successive passages of two transplantable fibrosarcomas and two leukemia lines in syngeneic mice. Characteristic and unique profiles were elicited by each of the four tumors and were reproducible in each of three successive transplant generations. The Hp profiles elicited by EL4 leukemia cells were similar in allogeneic and syngeneic mice, except that the Hp maxima were greater in the allogeneic mice. Preimmunization with EL4 cells or pretreatment with immune serum or spleen cells obliterated the Hp response normally elicited by EL4 cells in allogeneic mice. These results suggest that the Hp response elicited by a tumor is associated with transmissible characteristics of the tumor.

Animals↗
PubMed1978

Serum haptoglobin levels in mice with 7, 12-dimethylbenz[a]anthracene-induced tumors.

Serum haptoglobin (Hp) levels were determined periodically in mice treated with the carcinogen 7, 12-dimethylbenz[a]anthracene (DMBA). The magnitude and duration of the Hp response to tumors induced by DMBA were dependent on the tumor type; lymphocytic lymphomas elicted a minimal response, whereas mice bearing mammary carcinomas and stomach squamous cell carcinomas had high Hp levels which remained elevated throughout most of the period of tumor development. In the majority of mice with mammary carcinomas, the initial rise in serum Hp coincided fairly closely with the first appearance of palpable masses. Some variation in the magnitude of the Hp response was observed between individual mice bearing chemically-induced tumors of similar histological types.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

Metabolism of 7,12-dimethylbmethylbenz(a)anthracene by macrophages and uptake of macrophage-derived metabolites by respiratory tissues in vitro.

Cultured mouse macrophages and tracheal and lung tissue each produced the same ethyl acetate-soluble derivatives of 7,12-dimethylbenz(a)anthracene (DMBA). The derivatives produced in the different cultures were indistinguishable by thin-layer chromatography and by high-pressure liquid chromatography but differed in their relative proportions. The greatest difference was seen between lungs and macrophages. The predominant metabolite produced by lungs was 8,9-dihydro-8,9-dihydroxy-7,12-dimethylbenz(a)anthracene, while macrophages produced equal quantities of both 8,9-dihydro-8,9-dihydroxy-7,12-dimethylbenz(a)anthracene and a second uncharacterized derivative, Metabolite B, at low DMBA doses (less than 0.05 microgram/ml medium) and primarily Metabolite B at higher DMBA doses (greater than 0.05 microgram/ml medium). Macrophages released the majority of the ethyl acetate-soluble metabolites that they produced into the surrounding medium. With the exception of 8,9-dihydro-8,9-dihydroxy-7,12dimethylbenz(a)anthracene, these derivatives were accumulated within tracheal and lung tissue when these organs were cocultivated with macrophages in the presence of DMBA.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1976

Association between macrophage activity and serum haptoglobin levels.

Serum haptoglobin is elevated by treatment of mice with thioglycollate, B.C.G. or silica. Haptoglobin concentrations were followed for a two week period following treatment and were found to correlate with the known effect of the stimulants upon macrophage activity. The numbers and characteristics of peritoneal exudate cells present following intraperitoneal thioglycollate inoculation suggest a relationship between phagocytic activity and serum haptoglobin levels and support the idea that serum haptoglobin levels may be controlled by mediators released during the process of phagocytosis.

Adjuvants, Immunologic↗
PubMed1969

Aging of alpha-crystallins during development of the lens.

Fetal alpha-crystallin from the bovine lens can be resolved into three major subunit fractions by ion exchange chromatography. A fourth subunit gradually arises during the development of the lens. Incorporation studies indicate that this subunit is not formed by de novo synthesis but by the chemical conversion of one subunit into another. Possible mechanisms for this conversion are discussed.

Aging↗