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CMBM exam 3 > Nutrients, Oxidation and Antioxidants > Flashcards

Nutrients, Oxidation and Antioxidants Flashcards

1
Q

Is vitamin E water or lipid soluble?

A

Lipid soluble

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2
Q

Is vitamin C water or lipid soluble?

A

Water soluble

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3
Q

What is oxidative stress?

A

O2 will steal an electron from a reduced metal, flavin etc and become superoxide) O2-

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4
Q

Superoxide and its products are known as;

A

Reactive Oxygen Species or ROS

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5
Q

The gas hormone nitric oxide (NO) is known as a;

A

Reactive Nitrogen Species (RNS)

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6
Q

How are ROS and RNS formed?

A

By accident in the electron transport chain

On purpose by immune cells

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7
Q

What can have its structure modified by oxidative or nitrosative stress?

A

Proteins, lipids, carbohydrates, individual nucleotide bases

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8
Q

Is it good or bad that a hydroxyl group can react with anything around it?

A

Bad

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9
Q

What can aldehydes do that are considered bad?

A

Create cross links between proteins

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10
Q

How is iron important?

A

Key role in many enzymes (cytochromes)

Catalysis and electron transfer, oxygen transport

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11
Q

How is iron toxic?

A

It is insoluble in presence of oxygen
Catalyzes the Haber-Weiss-Fenton Reactions
Produces a free radical hydroxyl

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12
Q

How does iron help defend against the toxins it makes?

A

With Superoxide dismutase to aid in conversion of superoxide to more stable form

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13
Q

Where and how is iron stored?

A

In ferritin and hemosiderin mostly in the liver

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14
Q

What molecule moves iron from various organs and cells into tissues and bones?

A

Transferrin

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15
Q

How much iron should a person have in a day to maintain stores?

A

At least 8 mg

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16
Q

How is the transferrin receptor complex internalized?

A

By receptor medicated endocytosis

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17
Q

How is iron release?

A

By acidification

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18
Q

How is non-heme iron uptake inhibited?

A

By phytate and polyphenols in common food (plant sources) like;
- black tea
- cocoa
- chamomile
Polyphenols numerous rings chelate the iron increasing its elimination

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19
Q

How is iron uptake stimulated?

A

Vitamin C
Organic acids
Heme

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20
Q

What is a hereditary excess in iron called?

A

Hemochromatosis

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21
Q

What is a dietary overload of iron called and how can someone get it?

A

Hemosiderosis

Alcohol (red wines) and over using supplements (children)

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22
Q

What drugs does iron decrease the absorption of?

A

Thyroxine, tetracyclin, ciprofaloxacin
occurs because numerous rings on the molecules act as chelators and this more effectively eliminates the drug and iron along with it

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23
Q

What is anemia?

A

Abnormally low blood hemoglobin

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24
Q

What enzymes can protect you from reactive oxygen species?

A

Superoxidase dismutases
Catalases
Peroxidases

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25
Q

What chemicals can protect you from ROS?

A

Bilirubin, glutathione, catalase, vitamin E, B-carotene and ascorbate (vit C)

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26
Q

What is glutathione?

A

A small tripeptide reversibly oxidized/reduced and can be regenerated by NADPH and glutathione reductase

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27
Q

Superoxide Dismutase

A

catalyzes superoxide to hydrogen peroxide

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28
Q

What is the danger in an ischemic/reperfusion injury?

A

the initial return of oxygen creates a burst of ROS species

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29
Q

Reactive Nitrogen species -RNS

A

NO

Peroxynitrite is ONOO- which is O2- + NO

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30
Q

Although H2O2 is not a free radical but …

A

it can generate free radicals by encountering a transition metal

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31
Q

Lipid degradation generates

A

Peroxyl radicals

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32
Q

HOCl

A

produced by neutrophils during respiratory burst

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33
Q

Peroxynitrite

A

RNOS
strong oxidizing agent that is not a free radical
can generate NO2 which is a radical

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34
Q

what AA is important because it can be reversibly oxidized and reduced?

A

Methionine

this requires a reduced thiol such as glutathione

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35
Q

why are aldehydes so detrimental?

A

they crosslink proteins preventing them from functioning and making the breakdown and elimination difficult

36
Q

What is Vit E’s role in lipid oxidation ?

A

it prevents propagation of damage by acting as a sponge

37
Q

Influx of intracellular calcium causes?

A

cellular death through activation of numerous intracellular pathways

38
Q

what complicates the monitoring of oxidative damage in the vascular system?

A

oxidative damage not necessarily reflected by biomarkers and cannot be used as therapeutic targets
damage build ups in the subendothelial space

39
Q

Haber Weiss Fenton reaction

A

(1) Fe+2 + O2 -> Fe+3 + O2-
(2) 2 O2- + 2H+ –> H2O2 + O2
(3) Fe+2 + H2O2 –> OH* + OH- + Fe+3

40
Q

What transition metal in non reactive in biosystems?

A

Zinc

41
Q

In regards to reduction potential, the more negative it is ….

A

the more likely it will GIVE UP electrons

42
Q

What aids Iron absorption?

A

Vit C by acting as an electron donor converting Fe+3 to Fe+2 which is more soluble

43
Q

In general, what effects metal solubility?

A

very insoluble at pH 7

but most are very soluble in acid

44
Q

Freidreich ataxia

A

hereditary ataxia

defective frataxin - Fe cant be exported from Mitochondria and iron builds up in the nervous system

45
Q

What metal is required for Iron absorption?

A

Cu

46
Q

What can Fe deficiency lead to ?

A

lead poisoning because DMT/Divalent metal transporter expression is increased and it nonspecifically uptakes other metals as well

47
Q

What molecules act as buffers to maintain electrical potentials in cells?

A

NAD(P), glutathione and Ascorbate
all these uptake electrons at different ranges to cover a wide range of redox potentials to maintain the electrical balance in cells
similar to how pH is maintained in the blood

48
Q

How was it determined that Vitamin E was a requirement in the human body?

A

Patients with fat malabsoprtion syndromes were shown to have low levels of vitamin E

49
Q

What sequesters Fe and Cu ions which prevents ROS?

A

Ceroplasmin (Cu), albumin (metals) and transferrin

50
Q

What is Vitamin E actually?

A

A collection of molecules which function like alpha-tocopherol (alpha, beta, gamma, delta)

51
Q

What is the main function of vit E?

A

Antioxidant
Stops propagation of free-radical damage in membranes
May prevent fatty acid damage in membranes

52
Q

Tocopheryl esters (a form of vit E) are broken up by;

A

Pancreatic esterases (which also break up fatty acids)

53
Q

What is essential for vit E absorption?

A

Bile acids
Deficiency occurs in fat malabsorption
which makes sense since Vit E is fat soluble

54
Q

True or False

Like other fat soluble vitamins, E accumulates in toxic levels.

A

False

55
Q

What uptakes vit E?

A

Chylomicrons

56
Q

How is vit E oxidized and excreted?

A

Omega-oxidation by cytochrome P450

Removed in urine or bile

57
Q

What large organ is also important for vit E excretion?

A

Skin - sebaceous glands

58
Q

If there is a deficiency in vit E what are some diagnosis that can develop?

A

Retintis pigmentosa, neurological symptoms

59
Q

There is only one type of organism that can make vit E, what is it?

A

Plants

Best sources are veggie oils

60
Q

If you are deficient in alpha-tocopherol symptoms of ____ are mimicked.

A

Freidreich’s ataxia

61
Q

What can regenerate reduced vit E?

A

Vitamin C

62
Q

What is vit C’s main function?

A

Collegen biosynthesis
converts Proline to hydroxyproline
converts Lysine to hydroxylysine for crosslinking

63
Q

L-ascorbic acid is derived from ____.

A

D-glucuronate

structure similar to glucose, can be uptaken by GLUT4

64
Q

How many electrons can vit C donate? What does it use to regenerate?

A

2

NAD(P)H or glutathione

65
Q

What is a deficiency in vit C called?

A

Scurvy

66
Q

What are some symptoms of scurvy?

A

Connective tissue weakness, vascular damage, hemorrhagia, bleeding gums, poor wound and bone healing

67
Q

What happens if there is excess vit C?

A

Hypoglycemia (blocks glucose uptake), kidney stones, indigestion, dissolves tooth enamel
No direct evidence that megadose helps colds or flu

68
Q

What organ needs the most vit C?

A

pituitary gland

maybe cause its highly sensitive oxidative damage?

69
Q

Do vitamins C and E aid in primary prevention of total cancer incidence or mortality?

A

No

70
Q

In women with cardiovascular event who have high risk CVD, does ascorbic acid, vit E or beta carotene protect against it?

A

No

71
Q

Do vit C and E help prevent prostate cancer?

A

No

72
Q

Does vitamin C decrease the risk of diabetes?

A

Yes

73
Q

Does multivitamin supplementation prevent cancer or CVD?

A

Perhaps, very limited evidence

74
Q

what chemicals absorb electrons?

A

bilirubin, glutathione, ascorbate (vit c)

75
Q

Glutathione is a small tripeptide composed of …

A

glutamate, cysteine and glycine

76
Q

what contributes to Glutathione’s reversibly oxidation/reduction ability?

A

it is a sulfhydryl, the sulfur atoms can easily lose electrons or be partially ionized
it can also be nitrosylated

77
Q

What state is the glutathione pool maintained in ?

A

Reduced state (SH)

S-S) is the oxidized state (from 4 to 2 electrons

78
Q

What are the defenses in the blood/plasma against reactive oxygen species?

A

Vitamin C
Bilirubin
uric acid

79
Q

why can’t an anemic (low heme) pt be given IV heme?

A

Free Heme in the body is actually toxic

Its is normally bound to Haptoglobin or Hemopexin in the blood. The molecules clean up heme from lysed RBCs

80
Q

LDLs contain a significant amount of ?

A

Vitamin E which helps to protect them oxidation

81
Q

what improves bioavailability of Vit E?

A

the fat content of food

2 times more available when taken with milk vs. OJ

82
Q

Can vitamin E be stored?

A

yes in Adipose tissue

83
Q

What else is Vit C involved in?

A

synthesis of adrenal hormones
drug metabolism
folate metabolism
stimulates iron uptake

84
Q

what patients should consider taking nutrient supplements?

A

older adults
pregnant women
pt who are food insecure
alcohol dependent
strict vegetarians and vegans (for these ppl when genetics may affect nutrition)
those on drug regimens that alter metabolism/excretion

85
Q

A common measure of oxidative stress in plasma?

A

Malondialdehyde

CMBM exam 3 (24 decks)

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