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Feb 20, 2024

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NST 11 Spring 2024 Assignment 1 Introduction & Concept of Toxicology 1. Which of the following describes hormesis? a. A response that is beneficial at low doses and toxic at high doses (slide 1, pg. 28) b. A response that is toxic at low doses and beneficial at high doses c. A response that has no effect at low doses d. None of the above 2. The toxic effects of substance X were predicted using computer software. The analyses revealed a structural analogy between substance X and caffeine. This type of study is: a. In-silico (slide 1, pg. 14) b. In-vitro c. In-vivo d. None of the above 3. Which of the following correctly describes toxicity testing? a. Toxicity testing results could determine the approval of a product for use b. Toxicity testing could determine the allowable concentration of a chemical in the environment c. Toxicity testing requires in vivo testing to determine the potential health effects of a chemical. d. In vitro, in vivo, and in silico testing can be expensive and may take over 5 years to complete e. All of the above are true (slide 1, pg. 13-14) 5-8: True or False?  4. In the toxicity testing of substance X, a dose of 10 mg/kg is the lowest dose that can cause 100% lethality in a mice population. Therefore, the LD50 of substance X is 5mg/kg a. True/ False (Highlight one) 5. You want the difference between the effective dose-response curve and the toxic dose curve to be large. a. True/False (Highlight one) 6. Hormesis response is likely observed in some nutrients including vitamins and minerals. a. True/False (Highlight one)
NST 11 Spring 2024 7. The metabolism of a toxic substance always decreases its toxicity. a. True/ False (Highlight one) 8. Let’s look closer at dose-response relationships: % Response Lethal Dose 0 0.5 mg/kg 15% 1.3mg/kg 80% 12 mg/kg 100% 100 mg/kg a. What is the approximate LD 50 of chemical X? 10 mg/kg b. What is the NOAEL and LOAEL based on lethal dose ? NOAEL = 0.5 mg/kg LOAEL = 0.8 mg/kg
NST 11 Spring 2024 c. What is the equation for the margin of safety (certain safety factor)? Using this, what is the approximate margin of safety for compound X? Certain Safety Factor = LD1/ED99 1/0.1 = 10 Fundamental Concepts of Toxicokinetics 9. Which of the following is not a biological factor that determines toxicity? a. Excretion b. Absorption c. Translocation d. Storage e. Drug action 10. What class of enzymes are responsible for phase I metabolic reactions? a. Serine hydrolases b. Cytochrome P450 enzymes c. ATPases d. Lipid kinases e. Deacetylases 11. AhR is a protein that induces CYP1A1 expression. Knocking out AhR gene in mice will: a. Promote tumor growth (actually opposite I think… reduces toxicity of B(a)P because B(a)P becomes more toxic with Phase 1 metabolism) b. Decrease DNA adducts c. Increase the amount of reactive metabolite from Phase I metabolism d. Increase Phase II metabolism e. None of the above 12. Which statement(s) is true regarding hepatic/portal circulation? a. It circulates bile acids from the liver into the small intestine and transports bile acids back to the liver. b. It removes excessive interstitial fluid. c. It restricts the passage of pathogens into the cerebrospinal fluid. d. It passes the substances from the gut to the liver
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