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LAT Certification
Chapter 11
Question | Answer |
---|---|
Toxicology is | The science of poisons and the harmful or noxious effects these substances have on living organisms |
What are the five principal types of studies conducted in a toxicology lab? | Acute, subacute, subchronic, chronic and reproductive |
Describe acute toxicity studies | Exposure to a toxicant for a short period, usually less than 24 hours. |
What is LD50? | The median lethal dose of a substance, or the amount required to kill 50% of a test population |
Why are multi-dose toxicity studies performed? | To investigate the effects of repeated administration of a substance |
What is the timeframe for a subacute study? | Often 28 days (1 month) in duration |
What is the timeframe for a subchronic study? | Typically 13 weeks (3 months), approximating 10% of the life span of a rodent |
What is the timeframe for a chronic study? | May run 26 weeks (6 months), 38 weeks (9 months) or 52 weeks (1 year)-designed to see the effects of repeated administration over a larger portion of an animal's lifespan |
Global regulatory testing guidelines require multi-dose studies in which two species? | One rodent and one non-rodent, typically dog or nonhuman primate |
What are satellite animals used for? | They are administered the substance solely for the blood samples needed to determine the toxicokinetics of the subtance |
Why are reproductive and developmental toxicity studies performed? | To investigate the effect of a substance on various stages of the reproductive cycle, on gestation and on the fetus |
Protocols designed to study reproductive and developmental toxicity studies are generally divided into 3 types, which are? | Segment I-reproductive toxicity in male and female animals Segment II-fetal toxicity Segment III-toxicity in newborn pups |
What is a pyrogen? | A substance that produces a fever |
What test serves as an alternative to the use of rabbits in pyrogen testing? | Limulus amebocyte lysate (LAL) test-uses blood from a horseshoe crab mixed with the test substance-which will clump together in the presence of a bacterial toxin |
The nude mutation causes? | Hairlessness and the lack of a thymus gland. Without a thymus, mice lack T cells |
SCID stands for? | Severe combined immunodeficiency disorder; causes a deficit in both T cells and B cells |
Immunodeficiencies can be introduced into animal models by? | Surgery, exposure to chemicals, irradiation, induced tolerance |
Describe the three types of radiation exposure that are used to induce immunodeficiencies? | Single exposure-total body radiation in a single exposure Low-dose semicontinous-exposures are intermittent Partial-body-accomplished using lead shields to protect certain parts of the body |
What are antibodies? | Proteins that are produced by lymphocytes in response to exposure to specific foreign substances (antigens) |
What species are commonly used for antibody production? | Rabbits, sheep, and goats |
What are adjuvants? | Substances that are mixed with an antigen to directly stimulate immune cells to produce antibodies and prolong the absorption of the antigen from the injection site. |
What are some common adjuvants? | Freund's complete adjuvant (FCA), Freund's incomplete adjuvant (FIA), Titer-Max, Titer-Max Gold, MPL, Alhydrogel, and other aluminum salt adjuvants. |
What are possible side effects when using FCA? | Granulomas and ulcerations at injection sites. |
What are monoclonal antibodies? | Antibodies that recognize only one specific portion of the antigen. |
What is the procedure for producing monoclonal antibodies? | Immunizing mice (sometimes rats) with an antigen, collecting the plasma cells that produce the antibody of interest, then culturing a single clone so that a large amount of the antibody can be produced. |
What is the goal of monoclonal antibody production? | To expand and maintain the cell clone and collect its antibodies. |
What is a hybridoma? | A cancer cell fused with a plasma cell, which has properties of both parent cells: good growth rats from the cancer cell plus production of the desired antibody |
What are the two types of animal models for cancer research? | Induced disease and spontaneous disease |
Induced cancer models usually involve? | Injection of cancer cells or a topical application of some cancer-causing chemical directly on the skin or mucous membranes. |
Which lab animal is most frequently used for behavioral research? Why? | The rat. Because of its convenient size, ready availability, low cost and the vast amount of literature available on its biology. |
Why are mice used as models in neurobiology and neurobehavioral research? | The ability to manipulate their genome. |
What is positive reinforcement? | An animal repeating a behavior to acquire a reward |
What is negative reinforcement? | An animal learning to avoid an aversive stimulus |
What is pair-feeding, with respect to dietary studies? | method of ensuring that the control group and the experimental group receive the same amount of feed. The amount of food provided to the control animals each day is determined by how much test diet was consumed by the study group on the previous day. |
What do metabolism cages allow measurement of? | Food and water intake and feces and urine output. |
What are shared features of all metabolism cages? | Feed is placed in a recessed container as to not waste it, water bottle is recessed to catch any leakage, bottom of cage is wire mesh, double inverted funnel is used to separate feces from urine is separate receptacles |
What does a stereotaxic apparatus do? | Stabilize the head and precisely measure dimensions to allow for correct placement of the implants, needles, or electrodes during a surgical procedure |
What are some types of imaging procedures? | Ultrasound, MRI, PET, SPECT, CT, radiopharmaceuticals, fluorescent and bioluminescence systems |
What do bioimaging studies involve? | Restraint, administration of substances by IV catheters or other means, anesthetic regimens of varying length and recovery |