PubMed Health⌕ Search

Biomedical subjects

D A Creasia

Publications and source records attributed to D A Creasia.

At least 19 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↗
PubMed1997

Comparative binding and toxicity of saxitoxin and saxitoxinol in mice and in cultured cells.

The binding characteristics of saxitoxin (STX), a known voltage-gated sodium channel blocker, and its analog saxitoxinol (STXOL), were studied in neuroblastoma, peritoneal macrophage, hepatocytes and PC-12 cell lines. 3H-STXOL bound to the cell-surface sites which appear to be the same as those occupied by 3H-STX and which can, therefore, be identified as STX receptors. The relative agreement of respective Kd obtained by saturation, competition, association and dissociation kinetics for STX and STXOL suggest the absence of any artifact in binding measurements. Unlike STX, STXOL was non-toxic to mice by intratracheal instillation. The major advantage of using 3H-STXOL is that the tritium label is not exchangeable. Data from this study suggest that 3H-STXOL can be used to identify STX receptors at 37 degrees C.

Animals↗
PubMed1994

Oxidation of saxitoxin: detection and biological activity of its reaction products.

We characterized the oxidation products of saxitoxin by high-performance liquid chromatography and thin-layer chromatography. We observed several changes in the saxitoxin and neosaxitoxin chromatographic profile, as well as changes in the biological activities of the saxitoxin oxidized product. Toxins were heated in the presence of oxidizing agent, and at least five oxidation products were detected. Spectrophotometric measurements with Folin-Ciocalteau reagent confirmed the formation of these oxidation products. The excitation maximum of each of the oxidized components was determined by spectrophotofluorometry scans, and differed from the parent compound. The oxidized saxitoxin inhibited 3H-saxitoxin binding to neuroblastoma-glioma hybrid cells (NG108-15) to a lesser extent than saxitoxin, and had no toxic effect in mice. Formation of oxidation products suggests the possible, non-enzymatic transformation of saxitoxin and neosaxitoxin.

Animals↗
PubMed1993

Protection of mice from inhaled ricin by vaccination with ricin or by passive treatment with heterologous antibody.

Mice were vaccinated subcutaneously with 25 micrograms kg-1 of ricin in the presence of Freund's complete adjuvant or Ribi adjuvant, followed by a boost 14 days later with 50 micrograms kg-1 ricin in Freund's incomplete adjuvant or Ribi adjuvant, respectively. Three subsequent boosts at 28-day intervals with 25 micrograms kg-1 ricin yielded high anti-ricin antibody titres as determined by ELISA. Vaccinated animals were exposed to an aerosolized LD99 dose of ricin. With the exception of one death not attributable to ricin intoxication, all vaccinated mice survived the lethal aerosol exposure. In addition, a passive protection regimen was evaluated in mice pretreated with 100 micrograms purified goat anti-ricin IgG administered intravenously, and then challenged with ricin intravenously. All were resistant to 125 micrograms kg-1 of ricin, a dose greater than 25 times the intravenous lethal dose. Mice injected intravenously with 5 mg of the same IgG were protected from a lethal aerosol challenge. These results indicated that it is possible to protect animals from inhaled ricin by vaccination or passive administration of specific antibodies.

Aerosols↗
PubMed1991

Protection against microcystin-LR-induced hepatotoxicity by Silymarin: biochemistry, histopathology, and lethality.

Microcystin-LR, a cyclic heptapeptide synthesized by the blue-green algae, Microcystis aeruginosa, is a potent hepatotoxin. Pathological examination of livers from mice and rats that received microcystin-LR revealed severe, peracute, diffuse, centrilobular hepatocellular necrosis, and hemorrhage. These changes were correlated with increased serum activities of sorbitol dehydrogenase, alanine aminotransferase, and lactate dehydrogenase. Pretreatment of either rats or mice with a single dose of silymarin, a flavonolignane isolated from the wild artichoke (Silybum marianum L. Gaertn), completely abolished the lethal effects, pathological changes, and significantly decreased the levels of serum enzymes induced by microcystin-LR intoxication.

Animals↗
PubMed1990

Acute inhalation toxicity of T-2 mycotoxin in the rat and guinea pig.

In this study, concentration-response parameters were determined for rats and guinea pigs systematically exposed to an aerosol of T-2 toxin. The LC50 for a 10-min exposure to T-2 toxin aerosol was 0.02 mg T-2/liter air for rats and 0.21 mg T-2/liter air for guinea pigs. Data from total T-2 deposition in rats and guinea pigs exposed to their respective LC50 aerosol concentration gave an LD50 of 0.05 mg T-2/kg body weight for the rat and 0.4 mg T-2/kg body weight for the guinea pig. These data show that inhaled T-2 toxin is approximately 20 times more toxic to the rat (0.05 mg T-2/kg body wt inhaled vs 1.0 mg T-2/kg body wt ip) and at least twice as toxic to the guinea pig (0.4 mg T-2/kg body wt inhaled vs 1-2 mg T-2/kg body wt ip) than ip administered T-2 toxin. Histopathologic examination of major organs in both the rat and guinea pig after respiratory exposure to T-2 toxin indicated that lesions were similar to those described after systemic administration of the toxin. Gross and microscopic alterations of respiratory tract tissue after T-2 aerosol exposure were minimal and could not account for the increase in toxicity.

Administration, Inhalation↗
PubMed1990

The inhibition by methionine and choline of liver carcinoma formation in male C3H mice dosed with diethylnitrosamine and fed phenobarbital.

The ability of the dietary methyl donors methionine and choline to inhibit the carcinogenic and tumor-promoting effects of phenobarbital (PB) in the livers of male weanling C3H mice was examined. The mice were fed a commercial rodent diet with or without 0.05% PB. Thirty animals from each set received the diet with either: (1) no dietary supplementation, (2) an additional 1.0% choline chloride, (3) 1.5% DL-methionine or (4) both 1.5% DL-methionine and 1.0% choline chloride. Additional groups of 30 animals with the same eight dietary and PB-treatment regimens described above were given a single initiating dose of 150 mg diethylnitrosamine (DENA)/kg body wt dissolved in saline, or the saline solution only, 1 week prior to the start of PB feeding. The 16 treatment groups were fed their respective diets for 12 months. Statistical trend analysis showed that increasing levels of supplemental methyl donors gave highly significant protection in PB-treated mice (P less than 0.01). The incidence of liver carcinomas in the four dietary groups not receiving PB or DENA varied from 0 to 7%. The PB-treated animals not receiving an initiating dose of DENA developed hepatocellular carcinomas (HCCs) at incidences of 79% in group 1 animals, 74% in group 2 animals, 60% in group 3 animals, and 31% in group 2 animals respectively. Thus, incidence of HCCs in group 4 was significantly lower than in groups 1, 2 or 3 (P less than 0.01). However, the total incidence of liver tumors (adenomas plus carcinomas) was about the same in all DENA or PB-treated groups. Thus, dietary supplementation with methyl donors increased the proportion of animals bearing liver adenomas as their most advanced hepatic lesion in PB-treated mice. In DENA-treated mice fed PB, dietary supplementation with methionine and choline protected against the formation of liver carcinomas (P less than 0.02); however, methionine and choline had no significant effect on liver tumor formation in mice fed the PB-free diets. Methionine and choline supplementation gave significant protection against HCC metastases in the lungs of the tumor-bearing mice in groups initiated with DENA followed by PB promotion. These results support the hypothesis that PB exerts it tumorigenic activity in mice at least in part through a physiological insufficiency of labile methyl groups.

Animals↗
PubMed1990

Inhibition of microcystin-induced release of cyclooxygenase products from rat hepatocytes by anti-inflammatory steroids.

We showed previously that exposure to microcystin causes eicosanoid release. That study was extended further to test the effect of glucocorticoids on microcystin-induced release of [14C]arachidonic acid and its metabolites from rat hepatocytes previously treated with [14C]arachidonic acid. Release of total radioactivity was 4-fold greater from hepatocytes after 2-hr incubation with 1 microM microcystin than after incubation with control medium. Fluocinolone pretreatment decreased the microcystin-induced synthesis and release of prostacyclin by 24 +/- 2.6% (P less than 0.05) and thromboxane B2 by 39 +/- 3% (P less than 0.025). Treatment of hepatocyte cultures with either microcystin (1 microM) or steroids had no effect on cell viability or total cell protein. Total radioactivity released into the incubation medium was not affected by glucocorticoid alone. Under these conditions, the quantities of both prostaglandin F2 alpha and prostaglandin E2 released were not significantly different when control and microcystin-treated cultures were compared. The half-maximal inhibition (IC50) values obtained from the dose-response data for the inhibition of arachidonic acid release by steroids were comparable with normal cortisol levels in humans. Dose-response curves gave the following rank order of inhibitory potency: fluocinolone greater than dexamethasone greater than hydrocortisone. These results suggest that glucocorticoid therapy might be beneficial in microcystin toxicosis.

Animals↗
PubMed1989

Effect of toxins on arachidonic acid metabolism in rat cultured pulmonary alveolar macrophages.

The action of a trichothecene (T-2), microcystin-LR and saxitoxin on arachidonic acid metabolism in cultured rat alveolar macrophages was studied. Pulmonary macrophages exposed to T-2 trichothecene were stimulated to synthesize and release large amount of thromboxane B2 (TxB2) and 6-Keto F1 alpha. Microcystin-LR induced significant release of prostaglandins F2 alpha (140%), PGE2 (175%) and TxB2 (169%) compared to controls. Saxitoxin induced TxB2 release by 37%. Arachidonic acid release was stimulated by all three toxins. The release of arachidonic acid and its metabolites in alveolar macrophages exposed to T-2 toxin was partially blocked by fluocinolone (1 microM). These results suggest that macrophages synthesize and release inflammatory mediators in response to toxin exposure, and fluocinolone may protect against T-2 toxicosis.

Animals↗
PubMed1989

Effects of testosterone on the prevention of T-2 toxin-induced adrenocortical necrosis in mice.

To evaluate the effect of exogenous testosterone on the development of T-2 toxin-induced necrosis of adrenal glands, mice were allotted to 3 treatment groups. Each treatment group contained castrated male, and castrated and sexually intact female mice. Each mouse in group 1 was given 0.16 mg testosterone propionate at 48-hour intervals for a total of 12 injections, group-2 mice were given similar injections of only the vehicle, and group-3 mice were given no treatment. Twenty-four hours after the last injection, the mice in all 3 groups were exposed for 10 minutes to an aerosol of T-2 toxin. All mice alive at 24 hours after exposure were euthanatized and the adrenal glands and thymuses were examined histologically. Necrosis of the adrenal cortex was not found in any of the mice given preexposure treatment with exogenous testosterone, whereas all mice given vehicle only or no treatment had T-2 toxin-induced necrosis of the inner portion of the adrenal cortex. Lymphocytolysis in the cortex of the thymus confirmed that each mouse of all 3 treatment groups had experienced systemic mycotoxicosis. The uniform severity of the lesion in all mice suggests that the thymus was not protected by exogenous testosterone administration or by the castration status of the mice. We propose that T-2 toxin-induced adrenal necrosis in mice is prevented by the presence of testosterone.

Adrenal Cortex↗
PubMed1988

Mycotoxicosis caused by aerosolized T-2 toxin administered to female mice.

Thymus, spleen, adrenal glands, and small intestine of female mice exposed to aerosolized T-2 mycotoxin were examined at postexposure hours (PEH) 0.25, 1, 2, 4, 6, 9, 12, and 24. Lymphocyte necrosis was observed at PEH 1 in the thymus, spleen, and lamina propria and Peyer patches of the small intestine. Necrosis of small intestinal crypt epithelial cells was observed at PEH 2, and necrosis of parenchymal cells and increased number of neutrophils were seen in sinusoids of the adrenal cortex at PEH 4. These results indicated that the earliest microscopic evidence of T-2 mycotoxicosis after aerosol exposure was necrosis of lymphocytes in the thymus, spleen, and lamina propria and Peyer patches of the small intestine.

Adrenal Glands↗
PubMed1987

Acute inhalation toxicity of T-2 mycotoxin in mice.

Experiments were conducted to study the acute inhalation toxicity of T-2 mycotoxin in both young adult and mature mice. For a 10-min aerosol exposure, the 24-hr LC50 of T-2 mycotoxin in young adult mice was 0.08 +/- 0.04 mg T-2/liter air and that for mature mice was 0.325 +/- 0.1 mg T-2/liter air. Deaths among mice exposed to the higher aerosol concentrations used in this study (i.e., 1.5 to 2.4 mg T-2/liter air) occurred in less than 5 hr. General clinical symptoms in these animals immediately postexposure were tremors, lethargy, stilted gait, and, in some animals, prostration. In experiments separate from the concentration-response studies, total deposition of T-2 aerosol and selective retention of T-2 in the respiratory tract and nasal turbinates were determined analytically from 3H-labeled T-2. When total deposition of T-2 was quantitated, there was excellent agreement between that amount of T-2 deposited and that amount of T-2 predicted from calculations based on aerosol size and animal minute volume. Based on the aerosol deposition data, the LD50 values of T-2 mycotoxins was 0.24 mg/kg for young adult mice and 0.94 mg/kg for mature mice. For mice, inhalation of T-2 mycotoxin is at least 10 times more toxic than systemic administration (LD50 approximately 4.5 mg/kg) and at least 20 times more toxic than dermal administration (LD50 greater than 10 mg/kg).

Aerosols↗
PubMed1986

Adrenal cortical necrosis caused by T-2 mycotoxicosis in female, but not male, mice.

Experimentally, adrenal cortical parenchymal cell necrosis was induced by T-2 mycotoxin in female, but not male, mice. The lesion occurred in the adrenal glands in 11 of 11 female and 0 of 10 male mice given a nose-only aerosol exposure to T-2 mycotoxin. The necrosis, restricted to the zona fasciculata, began at the X zone interface and extended peripherally to involve 15% to 70% of the zone. Both light and transmission electron microscopies were used to determine whether the cellular and subcellular damage involved parenchymal cells of the zona fasciculata. Extensive necrosis of cortical thymocytes and necrosis of lymphoid cells in follicles of the spleen, lymph nodes, and intestine-associated lymphoid tissue were observed in both sexes. This is the first report to describe adrenal gland necrosis associated with exposure to T-2 mycotoxin.

Administration, Intranasal↗
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↗
PubMed1984

A sequential study of methapyrilene hydrochloride-induced liver carcinogenesis in male F344 rats.

Methapyrilene hydrochloride [2-[2-(dimethylamino)-ethyl)-2-thenylamino)pyridine monohydrochloride (CAS: 135-23-9)]-induced hepatocarcinogenesis was studied in male F344/NCr rats by sequential histologic, histochemical, and biologic methods. Methapyrilene hydrochloride was administered in the feed to rats at a concentration of 1,000 ppm for periods up to 89 weeks. Groups of rats were killed after 5, 10, 15, 29, 40, or 73 weeks of ingesting the carcinogen. Another group was allowed to live out their life-span. Hepatocellular eosinophilic foci and adenomas were seen after 10 and 15 weeks, respectively. Basophilic foci and adenomas were found after 29 and 40 weeks, respectively. Hepatocellular carcinomas developed in 5 of 10 rats at week 40, in 3 of 5 rats at week 73, and in 19 of 19 rats that lived out their life-span. Carcinomas arose within adenomas or as small in situ carcinomas. The histologic types included trabecular, adenocarcinoma, mixed, and solid poorly differentiated hepatocellular carcinomas. Eleven of the mixed and solid poorly differentiated carcinomas metastasized to the lung. Solid poorly differentiated hepatocellular carcinomas grew upon transplantation to the mammary fat pad of weanling F344 rats. Cholangiocarcinomas were found in 7 of 19 rats only in the life-span group. Mucous cholangiofibrosis was seen in all rats after 15 weeks. With the use of Regaud's mitochondrial stain, an increased cellular density of mitochondria was seen in some hepatocytes of peripheral and central lobular areas and in some hepatocellular carcinoma cells, but not in cells in many of the adenomas and foci. Cellular alpha-fetoprotein was found by immunoperoxidase staining in portions of hepatocellular carcinomas, but not in foci, adenomas, and nonneoplastic areas. The majority of hepatocytes in foci, adenomas, and hepatocellular carcinomas contained gamma-glutamyl transpeptidase. The findings suggest that multiple pathways may be followed in the development of methapyrilene-induced liver cancer that are similar to those found in rats exposed to many other hepatic carcinogens.

Aminopyridines↗
PubMed1983

In vivo and in vitro NO2 exposures enhance phagocytic and tumoricidal activities of rat alveolar macrophages.

Rat alveolar macrophages (AM) were exposed in vivo or in vitro to nitrogen dioxide (NO2) and subsequently tested for phagocytic and tumoricidal activities. AM obtained by lavage from Fischer 344/N rats exposed for 4 h to 40 ppm NO2 were significantly more phagocytic to opsonized sheep red blood cells (SRBC), exhibited an increased cytotoxic response toward syngeneic mammary adenocarcinoma cells, and were more sensitive to activation by agents such as lipopolysaccharide, muramyl dipeptide, and macrophage-activating factor, as compared with the response of AM obtained from unexposed control rats. Repeated 4 h/d NO2 exposures over 7-d or 14-d periods usually resulted in AM activity similar to control levels, with some instances of increased phagocytic activity of the AM but not to the extent of that observed for a single 4 h exposure. There were no significant decreases in the cytotoxic or phagocytic activities of the AM during any of the exposure periods. For the in vitro exposures, AM were lavaged from normal rats and then exposed for various periods to 10, 20, or 40 ppm NO2. A dose-related and time-dependent enhanced cytotoxic response of AM was observed. Maximum AM-mediated cytotoxicity occurred after an in vitro exposure to 10 ppm NO2 for 2 h. The cytotoxic response was directed toward syngeneic mammary adenocarcinoma cells but not against syngeneic embryoblast cells, indicating that the AM retained the ability to distinguish between normal and abnormal cells. No inhibitory effects of NO2 on AM-mediated cytotoxicity were observed. These experiments suggest that the host AM-mediated immune defense of the lung may be modulated by host exposure to inhaled chemicals.

Animals↗