Medical Toxicology Commons^™

Comparative Metabolism Of Aflatoxin B1 In Two Quail Genera Coturnix Japonica And Callipepla Californica, Sean Moody

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Avian species are highly susceptible to the hepatotoxic mycotoxin aflatoxin B₁ (AFB₁). Domesticated turkeys are exquisitely sensitive, due to a combination of highly-efficient hepatic cytochrome P450 (CYP)-mediated bioactivation, and to dysfunctional alpha-class glutathione S-transferases (GSTAs) which typically detoxify the bioactivated electrophilic metabolite exo-AFB₁-8,9-epoxide (AFBO). Wild turkeys are relatively resistant to AFB₁ in large part due to expression of functional GSTAs. Quail, a related Galliforme, are slightly less sensitive in vivo to AFB₁, but whether this is related to the hepatic metabolic profiles of these two critical enzymes has not been rigorously evaluated. …

Dna-Protein Cross-Linking By Pyrrolizidine Alkaloids, Gail L. Drew

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Pyrrolizidine alkaloids (PAs) are natural plant compounds found in hundreds of plant species worldwide and are reported to have cytotoxic, carcinogenic, antimitotic, and genotoxic activity. PAs are metabolized by the cytochrome P450 (CYP) system to the pyrrole or the N-oxide form. The pyrroles are bifunctional electrophilic alkylators that bind cellular nucleophiles such as DNA and proteins and sirupt normal cell processes, including DNA replication and gene transcription and can cause megalocytosis. The pyrroles dehydrosenecionine (DHSN) and dehydromonocrotaline (DHMO) are among the most potent PA cross-linkers and inducers of megalocytosis. DHSN and DHMO-induced cross-links in cultured normal (MDBK) and neoplastic (MCF7) …

Aflatoxin B1 Metabolism In Mammalian Pulmonary Tissue, J. Michael Eichelberger

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Aflatoxin B₁ (AFB₁) is a potent dietary hepatocarcinogen and may be a lung carcinogen when inhaled. To study the relative ability of lung and liver to metabolize AFB₁, a susceptible (Swiss-Webster rat) and resistant species (Syrian golden hamster) were pretreated with inducing agents in order to identify specific AFB₁ metabolizing enzymes in each tissue.

Analysis of AFB₁-exo-epoxide (AFBO) formation, O-dealkynation assays, and protein immunoblots demonstrated that cytochrome P450 (CYP) 1A proteins were overexpressed in both the lung and liver of hamsters pretreated with 3-methylchyolanthrene (3-MC). Only CYP1A1 was expressed in the lung …

The Role Of Homeostatic Imbalance In The Reported Immunomodulation Of T-2 Toxin, Michael Jay Taylor

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

T-2 toxin (T-2), produced by the genus Fusarium, is a cytotoxic trichothecene mycotoxin, a feed contaminant, and has been shown to be immunomodulatory. It is suspected that T-2-associated immunomodulation is mediated partly through the hypothalamic-pituitary-adrenal axis. The presence of endotoxin, a bacterial product capable of activating the hypothalamic-pituitary-adrenal axis as well as the levels of several hormones, also associated with activation of the hypothalamic-pituitary-adrenal axis, were determined in both vehicle- and toxin-treated animals. Endotoxemia was evident twenty-four hours after a single oral exposure to T-2. Blood levels of adrenocorticotropic hormone and corticosterone, parameters of the stress response, also increased …

Dietary Factors And Induction Of Hepatic Microsomal Hydroxylative Enzymes By Organochlorine Pesticides, D. Jesse Wagstaff

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Induction of hepatic microsomal hydroxylative enzymes is an important aspect of detoxication of fat-soluble toxicants. The magnitude of induction depends on numerous factors, such as the nature and dose of toxicant as well as dietary factors. Research was conducted on (1) endrin tolerance in rats, (2) preliminary comparisons of inductive effects of various organochlorine pesticides in rats to select compounds for further study in guinea pigs, (3) general effects of various dietary factors on induction, and (4) effects of ascorbic acid deficiency on induction of hepatic microsomal hydroxylative enzymes by organochlorine pesticides in guinea pigs. Measurements were made of body …