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Toxicology > Food Toxicology > Flashcards

Food Toxicology Flashcards

1
Q

Food toxicology is complicated

A
  • not produced in a defined area, hard to have strict quality controls
  • food is grown, harvested or caught
  • food contains nutrients and non-nutrient substances
  • different types of natural toxins that we can react to
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2
Q

non-nutrients

A

-are found in both natural and heavily processed foods

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3
Q

Food, Drug, Cosmetics Act

A
  • presumes that food is safe if it is free of certain contaminants
  • stuff can be added to food if it falls into Generally Recognized As Safe
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4
Q

Generally Recognized as Safe

A

food colour additives

  • with FD&C prefix
  • natural in origin
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5
Q

Nerve impulse transmission step 1

A
  • Na+/K+ pumps move Na+ ions out of the nerve cell and K+ ions in
  • charges of other molecules inside the axon block the positive charge of the K+ ions
  • a resting state occurs with a greater positive charge on the outside of the cell largely due to the Na+ ions
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6
Q

Nerve impulse transmission step 2

A
  • neuron fires it lets the Na+ ion back in through Na+ channels
  • a wave of depolarization that flows down the nerve axon
  • Na+ channels quickly close and K+ channels open to allow the neuron to go back to its resting state
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7
Q

Toxins from aquatic organisms

A
  • produced by aquatic diatoms and dinoflagellates

- humans normally get poisoned by eating shellfish that have eaten these micro-organisms and absorb the toxin

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8
Q

Paralytic Shellfish poisoning

A
  • most common, severe, fatal
  • dinoflagellates and cyanobacteria produced saxitoxins
  • Symptoms: tingling, burning, numbness, drowsiness, incoherent speech, respiratory paralysis
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9
Q

saxitoxins

A
  • Na+ channel inhibitors leads to flaccid paralysis

- heat stable (don’t degrade from cooking)

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10
Q

Neurotoxic Shellfish poisoning

A
  • dinoflagellate
  • produce brevotoxins
  • Na+ channel blockers
  • fish die off from this toxin
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11
Q

Diarrheic shellfish poisoning

A
  • algae make okadaic acids

- symptoms: mild diarrhea, nausea, vomiting, abdominal pain, chills, headache, fever

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12
Q

Amnesic shellfish poisoning

A
  • diatom makes domoic acid
  • Symptoms: vomiting, diarrhea, confusion, memory loss, disorientation, seizure coma
  • binds to excitatory amino acid receptors in neurons
  • Ca++ influx and necrosis and apoptosis in nerve cells
  • PEI outbreak, west coast shellfish closure
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13
Q

west coast shellfish closure

A
  • domoic acid
  • large-scale ocean temperature anomaly
  • big patch of warm water causing issues with weather and water quality
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14
Q

Blue-green algae

A
  • toxin-producing cyanobacteria
  • high inflows of nutrients from agriculture
  • blue-green algae can fix their own N
  • When N is limited, can not out compete green algae and leads to harmful algal blooms
  • microcystins-liver toxins
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15
Q

mycrocystins

A
  • inhibit activity of protein phosphates that remove phosphate groups from proteins that are necessary for their regulation
  • in liver cause dysregulation of glucose metabolism
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16
Q

scombroid poisoning

A
  • tuna/mackerels
  • fish containing high levels of free histidine
  • spoilage bacteria back down free histidine into histamine
  • Symptoms: immediate onset, tingling, rash, drop in bp, headache, itching of the skin, nausea, vomiting, diarrhea
  • Antidote: antihistamines
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17
Q

Muscle contraction and relaxation

A
  • membrane depolarization-Ca++ released from the sarcoplasmic reticulum
  • muscle contraction
  • muscle relaxation
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18
Q

muscle relaxation

A
  • Ca++ back into sr
  • parvalbumin binds free Ca
  • facilitates movement back into the sr
  • parvalbumin correlated with muscle relaxation rate
  • more parvalbumin=faster relaxation time
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19
Q

Allergies to fish

A
  • parvalbumin levels in fish can be high in the fast twitch muscles that make up the bulk of the filet
  • allergies are reaction parvalbumin
  • parvalbumin differs between species
20
Q

pufferfish poisoning

A
  • accumulate tetrodotoxin in pufferfish liver and gonads
  • Na+ channel blocker
  • class 1=extremely toxic
  • also accumulate high saxitoxin concentrations
21
Q

real zombies

A
  • haitian cultures-Bokurs used tetrodotoxin pufferfish to poison victims
  • paralyzed, appear dead, comatose
  • buried
  • Bokur digs up the victim, gives them hallucinogen and makes them a slave
22
Q

nitrate as additive creates carcinogenic compounds

A

nitrate-curing meats and fish products

  • antimicrobial activity and reacts with myoglobin and hemoglobin to form red nitrosylcompounds
  • nitrate reacts with amines to form stable nitrosamines
  • high temperature and acidic conditions increase rate of nitrosamine formation
  • nitrosamines can alkylate DNA and cause mutations and cancer
  • groups 1 carcinogens
23
Q

BBQ/cooking meat

A
  • high temperature breakdown of carbohydrates and proteins forms polycyclic aromatic hydrocarbons and heterocyclic aromatic amines
  • form DNA adducts
  • group 2 carcinogen, stomach and colorectal cancers
24
Q

mycotoxins

A
  • toxins produced by fungi
  • single species may make several toxins
  • many species could make the same toxin
  • only certain strains will make toxins
  • high infection rates on drought-stressed and insect-eaten plants
  • high fungal growth rates when food stored at high humidity
  • grow on plants, improperly stored food
  • passed from animals to humans
25
Q

aflatoxin toxins

A
  • B1, B2, G1, G2
  • modified furanocoumarins made via fungal polyketide biosynthesis
  • highly/extremely toxic classes
  • acute symptoms: abdominal pain, pulmonary edema, fatty infiltration and necrosis of the liver
  • additive or synergistic with other liver carcinogens
26
Q

aflatoxin B1

A
  • metabolically activated in the liver
  • cytochrome P450 covert into an epoxide
  • binds to DNA at the guanine base, incorrect repairs of adducts can leads to cancer
27
Q

Bt corn

A
  • reduced levels of aflatoxin contamination
  • expresses a protein normally made by soil bacteria
  • toxic to some insects
  • developed to increase yields by reducing insect damage
  • decrease in insect damage leads to less fungal infestation, resulting in reduced aflatoxin levels
28
Q

ergotism

A
  • eating grains infected by fungus
  • wet and overwintered grains
  • sclerotia consumes a whole seed and replacing it with fungal hyphae
  • caused by ergot alkaloids
29
Q

ergometrine

A
  • potent vasoconstriction drug
  • hallucinogenic
  • facilitate the delivery of the placenta and stop bleeding in childbirth
  • WHO essential drug
30
Q

ergotamine

A
  • potent vasoconstriction drug

- medically treats migraine headaches

31
Q

egotism symptoms and outcomes

A
  • gangrene-not enough blood flow to the extremities
  • convulsions-disruption in serotonin levels
  • hallucinations-disrupting certain neuro receptors
  • spontaneous abortions-not enough blood flow to the developing child
32
Q

exotoxins

A
  • soluble toxins made and secreted by bacteria released by lysis of the bacteria
  • proteins with enzymatic function
  • partially degraded by cooking
  • sufficient numbers avoid being digested in the gut and make it into the bloodstream
  • can be made by living bacteria in contaminated food and press even after the bacteria is dead
33
Q

endotoxins

A
  • cell-associated substances that are structural lipopolysaccharide components of the outer membrane of gram-negative bacteria
  • released from growing bacterial cells, released from dead bacteria
  • hyperactive immune response-toxic shock syndrome
34
Q

botulism

A
  • exotoxin botulism produced by bacteria
  • gram positive
  • obligate anaerobic bacillus
  • form spores
  • resistant to heat, light, drying, radiation
  • conditions for germination-anaerobic conditions, warmth, mild alkalinity
35
Q

botulism discovery

A
  • sausage poisoning

- neuoparalytic toxin produced by anaerobic bacterium

36
Q

BoNT mode of action

A
  • binds to receptors on the outside of the neuron, up-take toxin via endocytosis
  • translocation domain punches a hole through the endocytic vesicle so the protein escapes into the cytoplasm
  • catalytic domain finds its target (protein involved in secretion) and cleaves it, destroying it
37
Q

Catalytic domain cleaves SNARE

A
  • vesicles containing neurotransmitters must first be docked by SNARE proteins
  • botulinum toxin catalytic chain specifically cleaves these SNARE proteins, no neurotransmitters are released
  • stops neurotransmission between neuronal muscle junctions causing flaccid paralysis
38
Q

food borne botulism

A
  • spores infect food
  • toxin is produced and released into food when bacteria die
  • cand be reduced through cooking
39
Q

infant botulism

A
  • spores germinate in gut and bacterial colony is established
  • bacteria colony release toxins
40
Q

wound botulism

A

-associated with IV drug use

41
Q

botulism poisoning

A
  • result in symmetric descending flaccid paralysis of motor and autonomic nerves
  • symptoms: blurred vision, drooping eyelids, dry mouth, respiratory failure
  • treatment: anti-toxin antibodies and stick the patient on a ventilator
42
Q

medical botulism

A
  • used to treat conditions when muscles contract when they should not
  • botox blocks the nerve transmission that causes the muscle cells to contract
43
Q

exotoxin in e coli

A
  • non-pathogenic
  • bacteria are really good at swapping DNA bits amongst species
  • picked up genes that make them pathogenic
  • acquired the genes to make shiga toxin
  • cow guts-infect hamburger meat
44
Q

shiva toxin structure and function

A

subunit a
-toxic catalytic bit, cleaves the 28S ribosomal RNA destroying ribosomes and halting all protein translation
subunit b
-interacts with a specific lipid cell membranes
-tricks cells into taking it in by endocytosis

45
Q

shiva toxin

A
  • primarily occurs in intestinal epithelial cells

- acute hemorrhagic diarrhea and fever

46
Q

hemolytic-ureic syndrom

A
  • direct destruction of kidney cells from toxin
  • direct nerve damage
  • indirect destruction of red blood cells
  • elderly and children

Toxicology (14 decks)

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