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Biomedical subjects

C E Mitchell

Publications and source records attributed to C E Mitchell.

44 records · Page 3Linked to original sources
PubMed1979

Distribution, retention, and elimination of pyrene in rats after inhalation.

Pyrene was measured in tissues of Fischer 344 rats are various times after inhalation of pyrene aerosols (500 microgram/l; mass median diameter, 0.3-0., micrometer) for 1 h. Significant quantities of pyrene were found in nasal turbinates, trachea, lungs, kidney, and liver immediately after exposure. Clearance from the respiratory tract was rapid; concentrations in the trachea and lungs 48 h after exposure were 20 and 5% of the concentrations present 1/2 h after exposure. Pyrene also cleared from liver and kidney at a relatively rapid rate; concentrations in these tissues 48 h after exposure were approximately 10% of those 1/2 h after exposure. Concentrations in the gastrointestinal tract 24 h after exposure were 4 times those found 1/2 h after exposure. Pyrene cleared from the gastrointestinal tract approximately 4 d after exposure. Thus, inhaled pyrene is rapidly cleared from the respiratory tract by mucocilliary action from the trachea and bronchi and by translocation from the respiratory tract to the liver and kidney; it is eliminated primarily through the gastrointestinal tract.

Administration, Topical↗
PubMedDate not supplied

Effects on rat lung immunity by acute lung exposure to benzo(a)pyrene.

This study describes the effect of intratracheal instillation of benzo(a)pyrene (BaP) on immunological responses in the lung-associated lymph nodes, cervical lymph nodes, and spleen after deposition of 10(8) sheep red blood cells (SRBC) in the lung or peritoneal cavity of rats. An increased number of anti-SRBC antibody-forming cells was observed in the lung-associated lymph nodes when rats were immunized simultaneously with BaP installation. A suppression in the number of anti-SRBC antibody-forming cells occurred when SRBC were given intratracheally 4 or 7 days after BaP. The effects of the BaP appeared to be on the function of the cells in the lung-associated lymph nodes rather than due to changes in the exposed lung. BaP-induced changes in antigen handling or in regulatory populations of immune cells in the lung-associated lymph nodes may be responsible for the immune alterations observed.

Animals↗
PubMedDate not supplied

Generation and characterization of condensation aerosols of benzo[alpha]pyrene.

Condensation aerosols of benzo[a]pyrene (BAP) with particle sizes ranging from 0.1 to 2 micrometers (aerodynamic diameter) were produced and studied. These aerosols were generated in a glove box by direct vaporization of BaP and homogeneous condensation of the vapor. The aerosol concentration ranged from 50 to 700 micrograms/l with aerosol production rates up to 15 mg BaP per minute. The effects of vaporization temperature and flow rate of diluting air on the particle size distribution and aerosol output were studied. The BaP aerosol was produced with relatively constant mass concentration and particle size distribution for more than 5 h. The aerosol was physicochemically and thermally stable. Data on the in vitro dissolution of BaP particles in aqueous solvents and in different dissolution systems suggested that the organic BaP particle does not dissolve in simple aqueous solvents. Proteins, surfactants, or ethyl alcohol enhanced the rate of dissolution of BaP. The rate of dissolution of BaP particles was inversely proportional to particle size.

Aerosols↗
PubMedDate not supplied

Distribution and elimination of inhaled phenanthridone in Fischer-344 rats.

Aza-arenes are widely distributed in the environment. Certain members of this chemical class are biologically active and therefore could pose health hazards to humans if inhaled or ingested. Since inhalation is the most likely route for significant exposure for aza-arenes that are air pollutants, knowledge of the absorption, distribution, and excretion after inhalation is necessary to understand mechanisms of toxicity and predict health hazards associated with exposure to aza-arenes. In this study, rats were exposed nose-only to an aerosol of [14C]phenanthridone, a mutagenic aza-arene found in coal tar. Tissues, urine, feces, and expired air were collected at specified times and assayed for radioactivity. Radioactivity was rapidly absorbed from the respiratory tract and distributed to all tissues examined. It was rapidly eliminated from tissues (greater than 80% in 12 h), being concentrated only in the large intestine at later timepoints. Excretion of radioactivity in both feces and urine was complete within 4 d. Virtually none of the dose was eliminated as [14C]CO2. [14C] Phenanthridone was also administered orally to assess its absorption from the gastrointestinal tract. Absorption was nearly complete (83 +/- 6%), indicating that phenanthridone ingested as a result of mucociliary clearance and swallowing, grooming, or coprophagy could also contribute to tissue exposure. These results are similar to those obtained from inhalation studies of other polycyclic aromatic hydrocarbons, indicating that as a class, inhaled polycyclic aromatic hydrocarbons may be rapidly absorbed from the respiratory tract, widely distributed throughout the body, and readily eliminated in both urine and feces.

Air Pollutants↗