Chapter 16: Food Toxicology Flashcards
How does coffee keep us attentive?
Adenosine binds to receptor which makes us feel sleepy. caffeine binds to the same receptor and blocks adenosine from binding thus making us feel awake and not tired.
Anything can be added to food if it falls into what class?
Generally Recognized As Safe - GRAS
Describe the nerve impulse transmission
Step 1:
Na+/K+ pumps move Na+ ions out and K+ ions in to the axon cell.
Step 2:
When the neuron ‘fires’ it lets the Na+ ions back in through Na+ channels
A ‘wave’ of depolarization flows down the nerve axon.
The Na+ channels quickly close and K+ channels open to allow the neutron to go back to its resting state.
What is paralytic shellfish poisoning? what organism produces it? what toxin is produced? what are the symptoms? what is the mechanism?
- Dinoflagellates Alexandrium and some cyanobacteria produce saxitoxin(s)
– Na+ channel inhibitors (keeps them closed) leads to flaccid paralysis
– Heat stable (don’t degrade much from cooking)
- Symptoms: tingling, burning, numbness, drowsiness, incoherent speech, respiratory paralysis
What is neurotoxic shellfish poisoning? what organism produces it? what toxin is produced? What is the mechanism?
- From the dinoflagellate Karenia brevis
- Makes a number of brevotoxins
- Also Na+ channel blockers, but not as severe in toxicity
What is diarrheic shellfish poisoning? what organism produces it? what toxin is produced?
Algae (Dinophysis and Prorocentrum spp.) make okadaic acids. Symptoms: mild diarrhea, nausea, vomiting, abdominal pain, chills, headache, fever.
What is amnesic shellfish poisoning? what organism produces it? what toxin is produced?
The diatom Pseudo-nitzschia spp. makes domoic acid.
Symptoms:
– Gastrointestinal: vomiting, diarrhea, vomiting, apoptosis, necrosis
– Neurological: confusion, memory loss, disorientation, seizure coma
Binds to excitatory amino acid receptors in neurons, causing Ca2+ influx and necrosis/apoptosis in nerve cells
The blue-green algae Microcystis spp. make a class of 80 different toxins called what? what is the maximum acceptable limits in drink water? how does it work?
microcystins that are liver toxins
maximum acceptable limit- 1.5 μg/L
inhibits the activity of protein phosphatases that remove phosphate groups from proteins that are necessary for their regulation. in the liver this can cause deregulation of glucose metabolism
What is scombroid poisoning? how can you get this poison? what are the initial and late symptoms? what is the antidote?
named for the family of scomberidae (tunas and mackerels)
can involve any fish containing high levels of free histidine. spoilage bacteria break down free histidine into histamine.
Onset: immediate to 30 minutes
Initial symptoms: tingling or burning sensation in the mouth, rash on the upper body, drop in blood pressure, headache, itching of the skin
Later symptoms: nausea, vomiting, and diarrhea
Duration: 3 hours to several days
Antidote: Antihistamines!
What is pufferfish poisoning? how does the toxin works?
Pufferfish accumulate tetrodotoxin in (mostly) their liver and gonads. Tetrodotoxin is a potent Na+ channel blocker.
What is Nitrite and why is it used in curing meat and fish products?
Nitrite (NO₂−) is a chemical compound used in curing meat and fish products due to its antimicrobial activity, ability to react with myoglobin and hemoglobin to form red nitrosyl compounds, and contribution to sensory attributes of the meat.
How does Nitrite contribute to the formation of carcinogenic compounds in meat?
Nitrite reacts with 2º, 3º amines to form stable mutagenic nitrosamines, which can cause DNA adducts and result in mutations and cancer. High temperature (i.e. cooking) and acidic conditions (i.e. digestion) increase the rate of nitrosamine formation.
In which food products can Sodium Nitrite be found?
Sodium Nitrite is commonly found in cured meats, sausages, beef jerky, bacon, hot dogs, and other processed meat products.
What is the significance of the WHO upgrading cured meats to Group 1 carcinogens in November 2015?
The WHO’s classification of cured meats as Group 1 carcinogens means that there is sufficient evidence to suggest that consuming these products can cause cancer in humans. It is important for individuals to balance the risks associated with consuming these products with their enjoyment of life.
The high temperature breakdown of carbohydrates and proteins when grilling and smoking meats forms what?
The high temperature breakdown of carbohydrates and proteins when grilling and smoking meats forms PAHs and heterocyclic aromatic amines PAAs. these can form DNA adducts
What toxin is produced by fungi?
mycotoxins
What are the four major aflatoxins?
B1, B2, G1, and G2
What are aflatoxins?
These are modified furanocoumarins that are made via fungal polyketide biosynthesis
What is ergotism?
Produced from eating grains infected by the fungus: Claviceps purpurea
Grows in wet and overwintered grains: rye, barley, wheat
The fungus makes sclerotia or “ergots” by consuming a whole seed and replacing it with fungal hyphae.
What is ergometrine?
- potent vasoconstriction drug
- 5HT1a agonist (hallucinogenic)
- Used to facilitate the delivery of the placenta and stop bleeding in childbirth
- WHO ‘essential drug’
What is ergotamine?
a potent vasoconstriction drug
Used medically to treat migraine headaches
What are ergotism symptoms and outcomes?
- Gangrene- Not enough blood flow to the extremities
↳vasoconstriction will constrict blood flow - necrosis in extremities - Convulsions- From disruption in serotonin levels
- Hallucinations- From disrupting certain neuro receptors (5HT1a agonist)
- Spontaneous abortions-Not enough blood flow to the developing child
What are exotoxins?
Soluble toxins that are made and secreted by bacteria but can also released by lysis of the bacterial cell.
problems with enzymatic function
partially degraded by cooking
can be made by living bacteria in contaminated food and persist even after bacteria is dead
What are endotoxins?
Cell-associated substances that are structural lipopolysaccharide components of the outer membrane of Gram-negative bacteria.
- They’re released from dead bacteria (e.g. after antibiotic treatment).
- Causes a hyperactive immune response “toxic shock syndrome”: fever, blood clots, hypotension, shock, death.
What is botulism?
Caused by the exotoxin botulinum (Botulinum Neurotoxin A – BnNT A) produced by the bacteria Clostridium botulinum
What are the three types of botulism poisoning?
- Food borne botulism (canned food)
* Botulism spores infect food in anaerobic conditions
* Toxin is produced and released into food when bacteria die
* Toxin concentration can be reduced through cooking - Infant botulism
* Infants ingest C. botulinumspores
* Spores germinate in gut and bacterial colony is established.
* bacteria colony releases toxins
* this is a reason why you dont feed babies certain food until they’re older - Wound botulism
* Mostly associated with IV drug use
What do all three types of botulism result in?
symmetric descending flaccid paralysis of motor and autonomic nerves
what are the symptoms and treatment of botulism poisoning?
Symptoms include:
Blurred vision, drooping eyelids, Dry mouth, Difficulty swallowing, muscle weakness, Death due to respiratory failure
Treatment: Inject anti-toxin antibodies and stick the patient on a ventilator
What are the medical uses of botulinum toxin?
migraine headache, back pain, multiple sclerosis spams, excessive sweating
