C&D 9th Chapter 13 table list different toxic responses of the liver (e.g., cancer) and associated toxicants (e.g., aflatoxin, arsenic). One chemical was listed as an example for inflammation, steatosis, hepatocyte death, liver regeneration, and fibrosis and cirrhosis. Which was that hepatotoxicant? 

A. Acetaminophen

B. Bacterial endotoxins

C. Ethanol 

D. Vinyl chloride


Answer: C. A main way to reason this one out is to think about how different the dosing is for these chemicals. Acetaminophen overdoses cause liver death and are a leading cause of needing liver transplants in some countries (e.g., U.S.A.). Bacterial endotoxins cause an immune response throughout the body. Vinyl chloride is an occupational exposure risk primarily in terms of liver damage and it is an irritating chemical to work with and around.


Ethanol in contrast is consumed regularly and recreationally and in the cases of overconsumption leading to severe intoxication, with ethanol acting as a sedative-hypnotic it is the brain losing function that leads to lethality. It is the wide range of exposures up to potentially daily and decades long cycles of injury and repair which allow for ethanol to be associated such a wide range of responses and lesions.


A peanut butter sandwich contains two potential sources of a mycotoxin that can cause liver cancer as it gets bioactivated into an intercalating and adduct-forming ultimate carcinogen. To protect human health allowable limits are set for this toxin in a variety of nuts and grains.  What is this toxin called? 

A. Aflatoxin B1

B. Brevetoxin 

C. Cholera toxin

D. Digitoxin


Answer: A. Notes: B can be eliminated as it is produced by algae (e.g., karenia brevis (red tide) and not fungi. C. can be eliminated as it is produced by bacteria particularly pathogenic strains of Vibrio cholerae. D. can be eliminated as it is produced by plants (e.g., Digitalis purpurea (foxglove).



Hepatotoxicants can be divided into intrinsic and idiosyncratic. With intrinsic hepatotoxicants like carbon tetrachloride, they are characterized by having characteristic to the chemical lesions and dose (often high) related responses tied to a direct effect of the chemical or metabolite.  Intrinsic hepatotoxicant injury happens reproducibly in both exposed individuals and in animal models. With idiosyncratic hepatotoxicants they are characterized by variable pathology, dosing, and the intersection of a variety of factors to cause toxicity. This means their toxicity is often limited to susceptible individuals and this toxicity may be missed during routine preclinical testing. Which of the following is an example of an idiosyncratic hepatotoxicant?

A. Acetaminophen (aka paracetamol)

B. Alcohol (i.e., ethanol)

C. Alpha amanitin (e.g., from Amanita phalloides)

D. Anesthetic halothane. Note: The “halo” hints at how it was the first halogenated anesthetic 


Answer: D. Notes: Acetaminophen toxicity comes from regular metabolism and is primarily driven by dose with overdosing overwhelming the detoxification pathways as they run out of conjugating cofactors. Ethanol toxicity tends to be more chronic and related to long cycles of injury and repair due it being consumed in alcoholic beverages. C. is something that evolved in mushrooms to discourage animals from eating the fruiting bodies and as such is a rather broadly active hepatotoxicant.


A patient comes in and has yellow sclera and a yellowish tinge to their nails and skin. What organ has most likely been damaged and what is building up in their body as a result of that injury to cause these color changes?

A. Gall bladder and globin

B. Kidney and urea

C. Liver and bilirubin

D. Pancreas and lipase


Answer C. Notes: A can be eliminated as follows. Gall bladder injury can also cause the build up of bilirubin. However, bilirubin comes from the heme part of hemoglobin. The globin part does not cause the yellow coloration associated with jaundice. B. Can be eliminated as kidney damage is not associated with that kind of skin color change. Redness associated with itchy and rashy skin and paleness associated with nausea are more commonly found with kidney damage. Also, urea is colorless. The yellow color found in urine is a result of hemoglobin getting broken down into urochrome. D. Can be eliminated as the pancreas is involved in the recycling of bile salts but this happens in the intestines. Thus instead of building up in the blood and body they are eliminated and this increased in the intestines is associated with diarrhea. Also, lipase is an enzyme which has lipids as its substrate and is not directly involved in bilirubin.


There can be significant differences between species with respect to both the liver metabolites produced from the same chemical and the associated toxicity even at similar doses. While humanized animal models are available for some studies, there are other methods to study human specific metabolite production. To create both metabolites and to have signs of toxicity to assess what would be the better in vitro model?

A. Expressed isoforms (e.g., CYP3A4)

B. Hepatocytes

C. Human liver nuclear pellets

D. Microsomes


Answer: B. Notes: Hepatocytes are liver cells and as such have both the capacity for metabolism and can be used in cytotoxicity assays involving the release of cellular markers of toxicity (e.g., LDH) or the uptake (e.g., neutral red) or metabolism (e.g., MTT, XTT) of viability indicating compounds.


A can be eliminated as follows. Expressed isoforms, while they might be grown in cells (particularly insect cell derived baculosomes) are extracted from them before testing. So, they won't be able to respond to something like a dye uptake or metabolism-based viability assay. C and D can be prepared as subcellular fractions from liver tissue, which includes but is not limited to hepatocytes.


C is actually the name of a custom product I had made in order to get my Ph.D. research done and graduate.


C and D can actually be made at the same time as C is the first pellet made when making D, with S9 being the second.


Often that first pellet is called a "junk" pellet and thrown away. But particularly in the multinucleate hepatocytes there's loads of DNA in them and since most of that DNA spends most of its time at least partly protected by histones it is possible to get really good and often thready DNA from that process in spite of the ultrasonication and shredding involved in tissue preparation.


Buying that otherwise biohazardous waste cut our genotyping costs by ~70% and meant I could do the genotyping while Xenotech was doing the phenotyping. In the end, I got to pick only the samples whose donors had the genotypes I needed to do my study.


https://repository.lib.ncsu.edu/items/4543382b-a40b-493e-a13f-f579d103c453