class 11

Question 1

What is a natural toxin?

Answer 1

A natural toxin is a harmful chemical produced by living organisms, such as plants, molds, algae, microorganisms, and animals.

Question 2

What are mycotoxins and where can they be found?

Answer 2

Mycotoxins are toxic compounds produced by molds. They can be found in food products like grains, nuts, spices, and also in non-food materials under conditions like warmth, dampness, and humidity.

Question 3

How does aflatoxin exposure occur in humans?

Answer 3

Aflatoxin exposure occurs mainly through consuming contaminated foods or ingredients. Livestock consuming contaminated feed can also lead to human exposure through animal products.

Question 4

What is the primary health concern associated with aflatoxins?

Answer 4

Aflatoxins are carcinogens that can lead to liver damage or liver cancer upon consumption.

Question 5

How do phytotoxins, like tropane alkaloids, affect the nervous system?

Answer 5

Tropane alkaloids can have significant effects on the central and peripheral nervous systems by acting on acetylcholine receptors, leading to symptoms like hallucinations and potentially death.

Question 6

What is botulism, and how is it caused?

Answer 6

Botulism is a rare but serious illness caused by botulinum toxins, which interfere with nerve function leading to paralysis. It can be caused by consuming contaminated food, wound infection, or infant exposure.

Question 7

How do aflatoxins enter and affect the brain?

Answer 7

Aflatoxins can damage cells of the blood-brain barrier (BBB) or form DNA adducts, leading to neurotoxicity and potential brain cancer risk.

Question 8

How can aflatoxins impact astrocyte and microglia function in the brain?

Answer 8

Aflatoxins can induce neurotoxicity by causing mitochondrial-dependent apoptosis in astrocytes and triggering pro-inflammatory responses in microglia.

Question 9

What role do aflatoxins play in neurodevelopment?

Answer 9

Exposure to aflatoxins during critical developmental periods can affect the proliferation and development of neurons and influence behaviors such as motor coordination and spatial orientation.

Question 10

How are tropane alkaloids used in medical practice today?

Answer 10

Tropane alkaloids like atropine and scopolamine are used to treat conditions like bradycardia and to prevent motion sickness, respectively, due to their anticholinergic properties.

Question 11

What are the symptoms of amnestic shellfish poisoning?

Answer 11

Symptoms include memory loss, seizures, and potentially death, caused by consumption of seafood contaminated with domoic acid, an algal neurotoxin.

Question 12

How does domoic acid cause neurotoxic effects?

Answer 12

Domoic acid acts similarly to glutamate, overstimulating neurons to the point of injury or death, leading to neurological symptoms.

Question 13

What is the significance of DNA adducts formed by aflatoxins?

Answer 13

DNA adducts indicate direct DNA damage, which can lead to mutations, impaired cell function, and increased cancer risk, including in the brain.

Question 14

How might aflatoxins disrupt hypothalamic signaling related to feeding behavior?

Answer 14

Aflatoxins can alter the expression of appetite-regulating genes in the hypothalamus, potentially affecting feeding behavior and energy metabolism.

Question 15

What effects do aflatoxins have on acetylcholine, particularly its breakdown by acetylcholinesterase (AChE)?

Answer 15

Aflatoxins can slow down the activity of AChE, reducing the efficiency of acetylcholine breakdown, which may impair neural communication and cognitive functions.

Question 16

How do aflatoxins influence neurodevelopment and behavior in prenatal exposure?

Answer 16

Prenatal exposure to aflatoxins can affect the development of new neurons and lead to changes in neurobehavioral functions such as motor coordination and learning.

Question 17

What is the impact of adult exposure to aflatoxins on cognitive and emotional health?

Answer 17

In adults, aflatoxin exposure can lead to cognitive deficits, behavioral despair, working and spatial memory issues, and oxidative stress in the brain.

Question 18

How do tropane alkaloids work as anticholinergic agents?

Answer 18

Tropane alkaloids inhibit the action of acetylcholine at muscarinic receptors, preventing acetylcholine from exerting its effects on muscle movement, heart rate, and bodily secretions.

Question 19

How has scopolamine been historically used outside of medical practice?

Answer 19

Historically, scopolamine has been used as a “truth serum” by law enforcement and intelligence agencies to lower inhibitions and defenses, theoretically making individuals more likely to divulge information.

Question 20

How do tropane alkaloids like atropine and scopolamine differ in their medical applications?

Answer 20

Atropine is used to treat bradycardia and as an ophthalmic agent to dilate pupils, while scopolamine is used to prevent motion sickness and nausea, showcasing their diverse impacts on the nervous system.

Question 21

different types of natural toxins:

Answer 21

Toxin-producing plants (phytotoxins)
Ex: tropane alkaloids
Toxin-producing algae (phycotoxins)
Ex: domoic acid
Toxin-producing moulds (mycotoxins)
Ex: alflatoxin
Toxin-producing microorganisms
(enterotoxins)
Ex: botulinum toxin
Toxin-producing animals (venoms)
Ex: haditoxin

Question 22

Botulism =

Answer 22

Botulism is a really serious illness caused by a super strong poison that comes from a germ called Clostridium botulinum. When this poison gets into your body, it can make your muscles weak and hard to move, and it can even make it tough to breathe.

Question 23

how can people get Botulism

Answer 23

People can get this sickness in a few different ways:

Eating bad food: Sometimes food that wasn’t cooked or canned the right way has this poison in it.
Babies eating dirt or honey: Babies can get sick if they eat something that has the germ’s spores, like dirt or honey.
Getting a cut infected with the germ: If the germ gets into a wound, it can make the poison.
Breathing in the poison: This is super rare, but it can happen, like in a scary movie scenario.
If someone has botulism, they might feel really weak, have a hard time seeing, and find it hard to talk or swallow. Doctors treat it with a special medicine that fights the poison and help with breathing or eating if needed.

Question 24

Domoic acid (DA)

Answer 24

is another algal
neurotoxin that accumulates in marine
fish & shellfish

Question 25

enterotoxins vs phycotoxins

Answer 25

In summary, enterotoxins come from bacteria and primarily cause gastrointestinal issues by attacking the intestines. Phycotoxins come from algae and can cause a variety of symptoms, including neurological, liver, and skin problems, depending on the type of toxin and how a person is exposed to it.

Question 26

Amnestic Shellfish Poisoning

Answer 26

symptoms that include memory loss,
seizures, & death

Question 27

mycotoxin

Answer 27

Mycotoxins are toxic substances produced by fungi, like molds. Imagine if some of your food got left out too long and started to grow moldy patches. Those molds can produce mycotoxins, and if you eat the food, those mycotoxins can make you sick.

Sources in Food:
Aflatoxins: Found in grains (corn), nuts, & spice
(produced by Aspergillus fungus)
Considered carcinogens & can lead to liver damage
or liver cancer (when consumed)
Ochratoxin A: Commonly discovered in cereals, coffee
beans, & dried fruits
Main target = kidney
Patulin: Mostly found in rotten apples & apple products
Main target = immune system causing
immunotoxicty

Question 28

mycotoxin sources in the household:

Answer 28

Trichothecene mycotoxins:
Produced by Stachybotrys
chartarum (Black Mold)
can cause serious respiratory
issues & flu-like symptoms when
inhaled in contaminated
buildings

Aflatoxins - produced by
Aspergillus & found in in damp
indoor environments
Can cause respiratory infections
& lung infection (when inhaled)

Question 29

Trichothecene mycotoxins:

Answer 29

Produced by Stachybotrys
chartarum (Black Mold)
can cause serious respiratory
issues & flu-like symptoms when
inhaled in contaminated
buildings

Question 30

Aflatoxins -

Answer 30

Aflatoxins are a type of mycotoxin, which means they are poisons produced by certain molds, specifically ones called Aspergillus fungi. These molds like to grow on crops in warm and humid conditions, especially on things like corn, peanuts, cottonseed, and tree nuts.

Question 31

The 4 main aflatoxins are:

Answer 31

AFB1, AFG1, AFB2 & AFG2

Question 32

The B1 form is the predominant & most toxic
form of aflatoxin true or false

Answer 32

true

Question 33

Residues =

Answer 33

trace amounts of a chemical found on
foods
Can ultimately lead to exposure

Question 34

type of natural toxins:

Answer 34

Phytotoxins from plants, such as tropane alkaloids.
Phycotoxins from algae.
Mycotoxins from molds, like aflatoxin.
Enterotoxins from microorganisms.
Venoms from animals.

Question 35

Adducts” refer to complexes formed when
AFB1 chemically binds to DNA within the
cells. This can lead to several harmful
outcomes:

Answer 35

(1) DNA damage: Adduct formation is a
direct indication of DNA damage

(2) Cell Function and Viability

(3) Cancer Risk:

Question 36

how are aflatoxins aborbsed:

Answer 36

passive transport

Question 37

Metabolism of AFB1 occurs primarily in the.. and Converted via cascade of biochemical pathways by the hepatic
microsomal enzymes called …

Answer 37

liver and CYP450

Question 38

AFB1 has been detected in about
….% of autopsied brain specimens

Answer 38

80

Question 39

Indicates AFB1 can enter into brain
but the methods of entry can be
either via .. or …

Answer 39

a BBB transport
mechanism OR (ii) via causing
damage to BBB BCECs

Question 40

DNA adducts

Answer 40

a form of molecular damage that occurs when a foreign chemical substance covalently bonds with DNA. This means that the chemical forms a stable connection directly with the DNA molecule. Here’s a more straightforward explanation:

Think of your DNA as a long, spiral staircase inside almost every cell of your body. This DNA holds the instructions that tell your body how to grow and function.

Now, imagine if a piece of gum were stuck on some of the steps of that staircase. This gum represents a DNA adduct, which is basically when a harmful chemical from outside sticks to your DNA.

Just like gum on a staircase might block your step, DNA adducts can block the machinery that reads DNA to make new cells. This can mess up how cells grow and work.

Question 41

protein creatine
kinase (CK)

Answer 41

is a type of enzyme, which is a protein that helps speed up certain chemical reactions in the body. The main job of creatine kinase is to help manage energy in your muscles and other active parts of the body.

Here’s how it works:

Energy Storage: Your body needs a quick way to store and use energy during activities like running or lifting weights. CK helps by changing a molecule called creatine into another molecule called phosphocreatine, which stores energy.

Question 42

Pyroptosis

Answer 42

This is a form of programmed cell death
distinct from apoptosis
Characterized by the cell swelling &
bursting
This releases inflammatory substances
into the surrounding area.
It’s called “fiery cell death” b/c it
tends to provoke a strong
inflammatory response

Question 42

why is pyroptosis known as “fiery cell death”

Answer 42

It’s called “fiery cell death” b/c it
tends to provoke a strong
inflammatory response

Question 43

Microgliotoxicity vs Astrogliotoxicity

Answer 43

Microgliotoxicity = harmful effects on microglia

Astrogliotoxicity = damaging effects on astrocytes

Question 44

To measure AChE function we can look at …..

Answer 44

(i) how
fast AChE could break down its target (Vmax, a
maximum speed of reaction) & (ii) how effectively
AChE could bind to its target (Km, an indication of
binding affinity; lower means better)

Question 45

AFB1 reduces Vmax & increases ….

Answer 45

Km

Question 46

The Swimming direction test

Answer 46

Purpose: To assess motor coordination & spatial
orientation of animal
Provide insights into the animal’s ability to
control its movements & orient itself in space
How It’s Done: Typical setup (i) place in water, (ii)
observe its ability to swim in a directed manner
towards a safe platform
Might measure how straight animal swims
towards goal or how quickly it corrects its
direction if it starts swimming away
Poor performance in swimming direction might
indicate issues with (i) motor control, (ii) muscle
strength, (iii) balance, or (iv) spatial awareness

Question 47

Plant toxins are
synthesized through:

Answer 47

complex
biochemical pathways

Question 48

Tropane alkaloids =

Answer 48

class of naturally
occurring chemical compounds found in
several plant species.

Have significant effects on CNS & PNS due to
their action on ACh receptors
Most well-known tropane alkaloids are
atropine, scopolamine, & hyoscyamine

Can cause anticholinergic syndrome, leading
to symptoms like dilated pupils, increased
heart rate, hallucinations, & potentially
death due to their effects on the nervous
system

Question 49

Anticholinerigic Versus Cholinergic Activity

Answer 49

Cholinergic is like pushing the gas pedal, making things go by enhancing acetylcholine’s effects.
Anticholinergic is like hitting the brake, slowing things down by blocking acetylcholine’s effects.

Question 50

The hypothesis behind “truth-telling”:

Answer 50

Reduced
inhibition & critical thinking skills might lead to
unguarded speaking

Question 51

Atropine

Answer 51

Used in emergency medicine to treat:
Bradycardia (abnormally slow heart
rate), etc.
Also used in ophthalmology to dilate
the pupils for eye examinations

Question 52

Scopolamine

Answer 52

Used to prevent motion sickness &
nausea

Question 53

Cholinergic hypothesis” of AD

Answer 53

Acetylcholine helps send messages between brain cells, especially those involved in memory and learning.
Alzheimer’s Effect: In people with Alzheimer’s, the amount of acetylcholine in the brain is reduced. This happens because the specific brain cells that make and use acetylcholine start to die off as the disease progresses.
Knowing that acetylcholine levels were lower in Alzheimer’s patients, doctors began using medicines called cholinesterase inhibitors. These drugs slow down the breakdown of acetylcholine, which helps increase its levels temporarily in the brain.
Impact: These drugs can help manage symptoms of memory loss and mental confusion for some time, but they don’t stop the disease from getting worse because they only address one part of the problem.

In summary, the Cholinergic Hypothesis helped us understand that Alzheimer’s involves a decrease in a key brain chemical important for memory, leading to some of the first treatments for the disease. However, Alzheimer’s is a complex disease, and no single explanation covers all aspects of it. This hypothesis is a piece of the puzzle that has led to broader research and treatment approaches.