Cyanide Toxicity and Thiamin Deficiency Quiz

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Questions and Answers

What effect does methemoglobin have on the body's oxygen transport?

It cannot bind oxygen, impairing transport. (correct)

It increases the affinity of hemoglobin for oxygen.

It enhances oxygen transport to tissues.

It allows hemoglobin to carry more oxygen.

Which condition is primarily associated with demyelination of peripheral nerves due to chronic cyanide exposure?

Cyanide Antidote Syndrome

Tropical Amblyopia

Peripheral Neuropathy Disorder

Tropical Ataxia Neuropathy (correct)

What is a common treatment intervention included in cyanide antidote kits?

Calcium gluconate

Potassium chloride

Sodium nitrite (correct)

Sodium bicarbonate

Which of the following is NOT a consequence of chronic cyanide toxicity?

Increased oxygen transport Signup and view all the answers

What is a significant association with the conditions Tropical Amblyopia and Tropical Ataxia Neuropathy?

Low vitamin B12 status Signup and view all the answers

What is the recommended action to minimize the impact of tannins on thiamin absorption after a meal?

Consume foods high in ascorbic acid Signup and view all the answers

Which condition is primarily caused by thiamin deficiency?

Beriberi Signup and view all the answers

What enzyme function does thiamine pyrophosphate (TPP) support?

Conversion of pyruvate to acetyl CoA Signup and view all the answers

What is a common result of chronic alcohol consumption in relation to thiamin?

Increased risk of thiamin deficiency Signup and view all the answers

Which of the following is NOT recommended to counteract thiaminase activity?

Consuming dairy products Signup and view all the answers

What is the primary function of glucosinolates in plants?

Providing a bitter taste and potential protective benefits Signup and view all the answers

What happens to glucosinolate content when cruciferous vegetables are cooked?

It decreases generally Signup and view all the answers

Which substance is produced as a breakdown product of glucosinolates?

Isothiocyanates Signup and view all the answers

Which cruciferous vegetable is noted for having the highest glucosinolate content?

Brussel sprouts Signup and view all the answers

What effect do glucosinolates have at high doses in the body?

They can be pro-carcinogenic Signup and view all the answers

What role does the enzyme myrosinase play in the metabolism of glucosinolates?

Hydrolyzes glucosinolates to produce breakdown products Signup and view all the answers

What is a potential health consequence of consuming glucosinolates?

Reduction in thyroid function Signup and view all the answers

How can microbial myrosinase affect the body after consuming cruciferous vegetables?

It releases isothiocyanates in the gastrointestinal tract Signup and view all the answers

What is the most abundant glycoalkaloid in potatoes?

Solanine Signup and view all the answers

Which factor can increase the content of glycoalkaloids in potatoes?

Breeding for disease resistance Signup and view all the answers

Which glycoalkaloid is toxic and commonly found in under-ripe tomatoes?

Tomatine Signup and view all the answers

Where in the potato are glycoalkaloids most abundant?

In the skin Signup and view all the answers

What type of enzymes are involved in the biosynthesis of tomatidine from cholesterol?

GAME enzymes Signup and view all the answers

How does cooking affect the glycoalkaloids in potatoes?

It does not affect them, except during deep frying. Signup and view all the answers

Which glycoalkaloids are predominantly found in eggplants?

α-Solasonine and α-Solamargine Signup and view all the answers

What is the role of glycoalkaloids in nightshade plants?

Playing a protective role against pests Signup and view all the answers

Which enzyme is responsible for the conversion of glucosinolates to isothiocyanates?

Myrosinase Signup and view all the answers

What happens to 3-indolylmethyl-isothiocyanate in the blood?

It spontaneously degrades to form indole-3-carbinol. Signup and view all the answers

Which compound is formed when two molecules of indole-3-carbinol (I3C) dimerize?

Diindolylmethane (DIM) Signup and view all the answers

What is the most common pathway for the metabolism of isothiocyanates?

Glutathione conjugation Signup and view all the answers

Which isothiocyanate is associated with glucoraphanin?

Sulforaphane Signup and view all the answers

Which statement is true regarding the bioactivity of isothiocyanates like I3C, PEITC, and sulforaphane?

They have been shown to decrease cancer incidence. Signup and view all the answers

What type of reaction occurs when isothiocyanates are metabolized to produce mercapturic acid conjugates?

Conjugation Signup and view all the answers

Which enzyme has a role in the γ-glutamyl transpeptidase pathway of isothiocyanate metabolism?

Dipeptidase Signup and view all the answers

What is the role of isothiocyanates (ITCs) in relation to phase I and phase II metabolic enzymes?

They regulate the expression of these enzymes. Signup and view all the answers

What can happen when high doses of goitrogenic substances are consumed?

They can lead to enlargement of the thyroid gland. Signup and view all the answers

What is a characteristic of the competitive inhibition caused by phytochemicals?

They bind to enzymes but render them catalytically inactive. Signup and view all the answers

How do isothiocyanates act in relation to polycyclic aromatic hydrocarbons (PAH)?

They block the induction of CYP enzymes by PAH. Signup and view all the answers

Why is it important to consider dose when evaluating the effects of phytochemicals?

The dose makes the poison, impacting both beneficial and toxic effects. Signup and view all the answers

What is the effect of phytochemicals on CYP1A1 and CYP1A2?

They mildly induce the expression of both enzymes. Signup and view all the answers

What are the possible outcomes of glucosinolate breakdown products?

They can lead to the formation of potentially toxic intermediates. Signup and view all the answers

What type of substances can competitive inhibition of iodide uptake by goitrogenic substances lead to?

Goiter and thyroid gland enlargement. Signup and view all the answers

Study Notes

Natural Toxins in Plant Products

Phytoalexins (plant pesticides) are chemical defenses against attacking organisms and unfavorable environmental conditions.
Phytoalexins deter herbivores and prevent plant infection.
Phytochemicals often contain a sugar molecule, called a glycoside.
If the sugar is glucose, it's a glucoside.
Glycosides contain any sugar(s), while aglycones lack sugar.
Myrosinase/Thioglucosidase enzymes catalyze the breakdown reactions.
Heat (e.g., cooking) can interrupt endogenous plant enzyme activity but also enhance these chemical reactions.
Some bacteria possess myrosinase activity (e.g., Citrobacter species).
Phytochemicals in the Cruciferae/Brassicaceae family, such as Brussels sprouts and cabbage, are high in glucosinolates.
Cooking generally lowers glucosinolate content.
Glucosinolate breakdown products include thiocyanates, cyanogens, and isothiocyanates (ITCs).
Thiocyanates inhibit iodide uptake, leading to goiter and/or thyroid cancer.
Cyanogens (nitriles) are very toxic.
Isothiocyanates (ITCs) are anti-carcinogenic at low doses.
Some glucosinolates, like progoitrin in rapeseed and canola, form goitrin, which is strongly goitrogenic and not aided by iodine supplementation.
Erucic acid, a fatty acid in rapeseed and canola, can cause myocardial lipidosis when consumed in large amounts.
Cyanogenic glycosides/glucosides release hydrogen cyanide (HCN), a toxin.
Cyanide metabolism can be converted to thiocyanate or by binding to hydroxycobalamin (vitamin B12).
Cyanide poisoning leads to immediate, life-threatening effects, and can result from single exposure with increased severity at higher doses/exposure.
Cyanide binds to cytochrome oxidase a3, blocking ATP formation, building up H+ and lowering pH.
Cyanide poisoning leads to adverse symptoms like dyspnea, tachycardia, metabolic acidosis, coma, and potentially death in 20 minutes to 3 hours.
Cyanide antidote kits usually contain sodium nitrite along with high doses of hydrocobalamin.
Note that methemoglobin, created by the nitrite, carries no oxygen, so there's increased risk from using sodium nitrite.
Bamboo shoots contain cyanogenic glycosides (taxiphyllin) which can create HCN through pickling.
Apricot seeds contain amygdalin, a cyanogenic glucoside, which in high doses result in cyanide toxicity in people.
Glycoalkaloids are natural toxins in some plants of the nightshade family (Solanaceae).
Solanine can be found in high concentrations in the green parts of potato plants.
Solanine generally doesn't cause any difficulties for humans in potato tubers, unless it is improperly stored.
Some plants produce phytochemicals that have beneficial uses at lower doses but are harmful in high doses.
Thiaminases destroy thiamin (vitamin B1) and are found in bacteria, fungi, and certain plants and fish.
Some plants/products contain anti-nutrients that interfere with the absorption and utilization of nutrients from the food.
Soybean protease inhibitors can inhibit protein digestion in animals.

Phytic Acid/Phytate

Phytic acid is a major storage form of phosphorus in plants.
It binds to minerals and can inhibit their absorption.
It can cause a problem with mineral deficiencies and other malabsorption issues.
Soaking, milling, and fermentation can break down the phytate and reduce its effects on mineral absorption.

Oxalates

Oxalate is an anti-nutrient that binds to minerals like calcium, iron, and magnesium.
It can cause kidney stones and other negative health effects.
A diet with a high intake of oxalate-rich foods should be reduced, as indicated by a health professional.

Other Anti-Nutrients

Avidin (raw eggs) prevents biotin absorption, leading to deficiencies.
Amylase inhibitors affect starch digestion.
Lipase inhibitors affect fat digestion, which can be harmful to animals.
Saponins have diverse molecular structures but have a general anti-absorptive property on other nutrients.

Soybean Protease Inhibitors

Protein inhibitors in soybeans affect the absorption of proteins, and they are acid stable.
Heat processing usually breaks down these inhibitors.

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Description

Test your knowledge on the effects of cyanide toxicity, methemoglobin's role in oxygen transport, and the implications of thiamin deficiency. This quiz explores various conditions and interventions associated with these topics, challenging your understanding of biochemical pathways and nutritional impacts.