William M. Hadley

Nasal cavity enzymes involved in xenobiotic metabolism : effects on the toxicity of inhalants

A decade ago, the ability of nasal tissues to metabolize inhalants was only dimly suspected. Since then, the metabolic capacities of nasal cavity tissues has been extensively investigated in mammals, including man. Aldehyde dehydrogenases, cytochrome P-450-dependent monooxygenases, rhodanese, glutathione transferases, epoxide hydrolases, flavin-containing monooxygenases, and carboxyl esterases have all been reported to occur in substantial amounts in the nasal cavity. The contributions of these enzyme activities to the induction of toxic effects from inhalants such as benzo-a-pyrene, acetaminophen, formaldehyde, cocaine, dimethylnitrosamine, ferrocene, and 3-trifluoromethylpyridine have been the subject of dozens of reports. In addition, the influence of these enzyme activities on olfaction and their contribution to vapor uptake is beginning to receive attention from the research community. Research in the next decade promises to provide answers to the many still unanswered questions posed by the presence of the substantial xenobiotic metabolizing capacity of the nasal cavity.

Cytochrome P-450 dependent monooxygenase activity in rat nasal epithelial membranes

Cytochrome P-450 was found in nasal epithelial membranes (NEM) of the rat. The quantity was 12% that of liver on a per mg of microsomal protein basis and 1.6 times that of lung on the same basis. Metabolism of p-nitroanisole was faster by microsomes from NEM than by microsomes from liver or lungs while the metabolism rate of aniline by microsomes from NEM was between that of microsomes from liver and lung.

Persistent suppression of humoral immunity produced by 7,12-dimethylbenz(a)anthracene (DMBA) in B6C3F1 mice: Correlation with changes in spleen cell surface markers detected by flow cytometry☆

The purpose of these studies was to examine the effects of DMBA on subpopulations of splenocytes obtained from B6C3F1 mice, using cell surface markers defined by monoclonal antibodies and multiparameter flow cytometry. Changes were correlated with alterations in humoral immune function assessed in vitro. Mice were treated for 10 days during a 2 week period by subcutaneous (s.c.) injections of DMBA in corn oil at doses of 0.5, 5 and 10 micrograms/g/day (5-100 micrograms/g total dose). Four mice from each exposure group and an additional corn oil control group of mice were studied at 4 and 8 weeks following the last injection with DMBA. These studies demonstrated a dose-dependent decrease in the total number and percentage of spleen cells expressing B-cell markers (mu heavy chain, kappa light chain and 14.8 antigen) as well as T-cell markers (Thy 1.2, Lyt-1 and Lyt-2). The percentage of splenocytes expressing Mac-1 was increased by DMBA. Helper T-cells appeared to be a very sensitive population of spleen cells to DMBA exposure, as suggested by a decrease in the number and percentage of Lyt-1 positive cells recovered from the spleen 4 weeks after exposure to DMBA. DMBA produced a dose-dependent suppression of the in vitro primary humoral immune responses to SRBC, TNP-Ficoll and TNP-LPS. The fact that a functional suppression of humoral immunity was accompanied by a decrease in the number of mature B-cells and T-cells in the spleen suggests that cell surface markers may be useful indicators of immunotoxicity in animals receiving DMBA in sub-chronic studies.

Analysis of heavy metal immunotoxicity by multiparameter flow cytometry : correlation of flow cytometry and immune function data in B6CF1 mice

Bone marrow and spleen cells obtained from female B6C3F1 mice given a single i.p. exposure to cadmium acetate (0.9 mg/kg), lead acetate (12 mg/kg), or sodium acetate (12 mg/kg), were studied using flow cytometry, immunologic, and hematologic assays. Significant changes were detected in subpopulations of bone marrow cells using multiparameter flow cytometry within 1 day following treatment with cadmium or lead. Bone marrow cells obtained from B6C3F1 mice 5 days after treatment with cadmium or lead were found to have a decreased number of cells expressing Mac-1, 55-7.2, 14.8, and Lyt-1 antigens, suggesting a shift to immature cell types. An increase in the number of progenitor cells (CFU-C) obtained from the bone marrow of mice treated with heavy metals was also noted 5 days after exposure to cadmium or lead. A time-dependent suppression of the in vitro primary humoral immune response of spleen cells to SRBCs, TNP-Ficoll and TNP-LPS was produced by cadmium or lead treatment. Suppression of the mitogenic response of spleen cells to Con A, PHA, and LPS was also found to be time-dependent. Spleen cell surface marker expression (Mac-1, Lyt-1, Lyt-2 and 14.8) was altered in response to cadmium or lead treatments, but these changes did not appear to correlate with the humoral immunity or mitogen-induced proliferation data. These studies demonstrate that changes in cell surface markers on discrete subpopulations of lymphoid cells present in the spleens of heavy metal exposed mice may not correlate with alterations in the functional activity of these cells. However, changes in murine bone marrow surface markers in response to cadmium or lead treatment predicts a shift to immature cell types, which appeared to correlate with the increase in CFU-C activity.

Five-month oral (diet) toxicity/infectivity study of Bacillus thuringiensis insecticides in sheep

Bacillus thuringiensis insecticides (Bt) [Dipel (test substance D or Thuricide-HP (test substance T)] were administered in the diet for 5 months to castrated mixed rambouillet/merino sheep (24-34 kg at the beginning of the study) at a dose of 500 mg/kg/day (approximately 10(12) spores per day). No treatment-related effect was seen on weight gain or clinical chemistry parameters nor were significant gross clinical changes observed. Several blood and tissue samples taken just prior to the time the animals were killed or at necropsy were found to be positive for Bt when cultured. Detailed gross and microscopic pathologic examination of the sheep revealed several incidental lesions. However, the only lesion that may have been associated with the treatment was lymphocytic hyperplasia in Peyers patches seen in the cecum of three sheep and it was not considered to be clinically significant.

Flow cytometry coulter volume analysis of lead- and cadmium-induced cellular alterations in bone marrow obtained from young adult and aged balb/c mice☆

Flow cytometry Coulter volume analysis was used to examine the effects of an acute exposure to cadmium or lead on subpopulations of Balb/c bone marrow cells. A significant shift in the volume of Balb/c bone marrow cells was detected in response to a single i.p. injection of cadmium acetate (Cd) or lead acetate (Pb) compared to sodium acetate (Na)-treated mice. An increase in the relative number or size of myeloid/monocytic cells was noted in the bone marrow of cadmium or lead-treated mice. This effect was more pronounced in aged Balb/c mice than in young adults. These studies suggest the flow cytometry Coulter volume analysis may be a useful and sensitive technique for the assessment of cellular changes that occur in the bone marrow in response to xenobiotic exposure.

Determination of Selenium in Tissues, Serum, and Blood of Wild Rodents by Graphite Furnace Atomic Absorption Spectrophotometry

Selenium (Se) levels were determined in liver, kidney, blood, and serum of wild rodents using graphite furnace atomic absorption spectrophotometry. A simple wet digestion technique was used to prepare samples for analysis. Nickel nitrate was used to suppress volatilization of Se during the char stage. Compared to existing techniques this greatly reduces the effort and time required for sample preparation and allows use of the graphite furnace atomic absorption technique for Se determination.

Decrease in acetaminophen toxicity in mice treated with metyrapone

Abstract Metyrapone, an inhibitor of cytochrome P-450, was administered to mice to determine the effects on acetaminophen toxicity. Metyrapone increased the acetaminophen LD-50 by 30%. Hepatic glutathione depletion was significantly less in the metyrapone-treated mice while the time to maximum depletion was delayed. Histological studies showed a significant decrease in the hepatic necrosis in mice receiving metyrapone after acetaminophen compared to mice receiving acetaminophen alone.

Comparative distribution of misonidazole and its amine metabolite in female swiss webster mice

The distribution of misonidazole and its terminal reduction product 1-(2-amino-1-imidazolyl)-3-methoxy-2-propanol (miso-amine) were compared in female Swiss Webster mice to determine if either misonidazole or miso-amine is distributed to peripheral nerves. Female Swiss Webster mice received a 100 mg/kg (5 microCi/mumole) i.p. dose of either 3H-misonidazole or 3H-miso-amine and the distribution of radioactivity was determined in various tissues including sciatic nerves and other myelinated nerves. Urine from misonidazole treated animals contained both miso-amine and misonidazole (8.4 and 20.4%, respectively, of the total radioactivity in the urine). Misonidazole produced higher initial tissue concentrations of radioactivity than did miso-amine. The relative tissue concentrations of radioactivity produced by misonidazole or miso-amine were similar, although not identical, 48 hours after administration of the drugs. Both sciatic and other myelinated nerves were found to retain radioactivity following the administration of either misonidazole or miso-amine.

Kepone: A Case Study of an Environmental Legacy

Drs. Kidd and Hadley are professors of biology and pharmacy (toxicology), respectively, at the University of New Mexico, Albuquerque 87131. Dr. Kidd (left) holds a B.S. (biology) from Northern Arizona University, M.S. degrees from Northwestern University (biology) and University of New Hampshire (chemistry teaching), and a Ph.D. (phycology-limnology) from Michigan State University. He has taught at the secondary, community college, and university levels since 1954. Dr. Kidd has served as an invited lecturer at NSF-AAAS Chautauqua-type short courses for college teachers across the country on environment-related topics. Dr. Hadley holder of B.S. (pharmacy), M.S. (pharmacology), and Ph.D. (pharmicology/,toxicoo rdeeti gre e from Purde U niversity , bgann hisi profesionloy carenierasaphrcisty and has taughtshine (c%7miDr. H deyin) hasnevd as ahD (hconsltatog-inogy sevral Mcaseirgardng Sthratset oUnvrsi t.envrnet hand isgh atrglr nslatwt the Poisaycmunt ole,and Contvrol Drugleel Inoraioncente4.r. Hed hals served s on teUinverityeo Newtrra