Methods in Toxicology Flashcards
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Read the first 5 Methods in Toxicology flashcards as text
What is the purpose of the LD50 test in toxicology?
Answer: To identify the lethal dose for 50% of a test population
The LD50 (Lethal Dose 50%) test is a standard measure in toxicology used to determine the dose of a substance that is lethal for 50% of a test population. It provides a quantitative estimate of the acute toxicity of a chemical, indicating its short-term poisoning potential. This value helps in classifying substances and setting safety guidelines.
Which of the following in vitro methods is commonly used to assess cytotoxicity of chemicals?
Answer: MTT assay
The MTT assay is a widely used in vitro method for assessing cell viability and cytotoxicity of chemicals. It measures the metabolic activity of cells, as viable cells convert the yellow MTT tetrazolium dye into a purple formazan product. The intensity of the purple color is directly proportional to the number of living cells, providing a quantitative measure of a chemical's toxic effect on cells.
What is the main advantage of using in vitro methods over in vivo methods in toxicology testing?
Answer: Faster and more controlled environment
A main advantage of using in vitro methods in toxicology testing is that they are generally faster and conducted in a more controlled environment. These methods allow for high-throughput screening of chemicals, reduced costs, and precise manipulation of experimental conditions, making them efficient for initial hazard identification and mechanistic studies compared to complex in vivo models.
What does the Ames test evaluate?
Answer: Mutagenic potential
The Ames test is a bacterial assay specifically designed to evaluate the mutagenic potential of chemical compounds. It assesses whether a substance can cause mutations in the DNA of specific strains of Salmonella typhimurium bacteria. A positive result indicates that the chemical may be a mutagen and potentially a carcinogen.
Which method is used to detect DNA strand breaks in individual cells?
Answer: Comet assay
The Comet assay, also known as single-cell gel electrophoresis, is a sensitive technique used to detect and quantify DNA strand breaks in individual cells. Damaged DNA fragments migrate further in an electric field, creating a characteristic 'comet tail' shape. This assay is valuable for assessing genotoxicity and DNA repair mechanisms.