Lecture 7 Flashcards
Study of the adverse effects of chemicals on living organisms:
Toxicology
Toxicology is an intersection between ________ and _________
biology and chemistry
Interaction of toxicant with biological system depends on (2):
- Chemical/physical characteristics of toxicant
- Biological characteristics of organism
__________ makes the poison
Dose
On a dose-response curve the dose is located on the _ axis and the response on the _ axis
x
y
What are the 3 assumptions for dose response curves:
1) Response is due to the chemical
2) Magnitude of response is due to the dose
3) Quantifiable method to assess response
What are some different ways that a dose can be administered:
- injections (needle)
- diet (food, water)
- waterborne exposure (gills, skin)
- airborne (lungs, skin)
What are some units for the dose that we can see on the x axis:
- amount of toxicant (mg)
- amount of toxicant per weight (mg/kg) or volume (mg/L)
- amount of toxicant per weight per time (mg/kg bw /d)
- may also be time (seconds - years)
Biological responses are ______________ some are very sensitive and some very resistent
variable
Illustrate a response frequency curve and tell me where most responses are located
most respond at middle of curve
What does LC50 mean?
at what concentration do we see 50% of the fish die
EC =
LC =
IC =
- effective concentration
- lethal concentration
- inhibitory concentration
MED =
Minimally effective dose / at what concentration you actually see a response (=threshold dose)
Name the 4 curves on the D-R Continuum of effects
- enzyme induction
- tissue lesions
- behavioral changes
- lethal effects
A biological response to a chemical that gives a measure of exposure and toxic effect:
Biomarker
Name 4 biomarkers that can be used to study PAHs
1) DNA adducts
2) COMET assay
3) Phase 1 or Phase 2 biomarkers
4) CYP1a/EROD
Explain DNA adducts:
a DNA adduct is a chemical that covalently binds to DNA, modify the DNA, change its structure, which affects cell structure and causes some tissue-level effects.
To detect DNA adducts in the lab you can use:
radioactivity
Explain comet assay:
With the comet assay (SCGE assay) the goal is to see if the chemical is affecting the structure of the nucleus, we calculate the comet tail length based on the different concentrations of chemical, one positive control (UV) and one control
_____________________ are induced by toxicants, and their induction can be used as a biomarker
Biotransformation enzymes
Explain EROD assay:
Chemical reagents that we can put in our samples and if the sample has this enzyme (CYP1A) the color will change
