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Biochemistry Exam #2 > Clinical Application > Flashcards

Clinical Application Flashcards

1
Q

What are the two disorders of fructose metabolism? Which is more severe?

A
  1. Fructokinase deficiency (essential fructosuria)

2. Aldose B deficiency (fructose poisoning) - more severe

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2
Q

What is the effect of fructokinase deficiency?

A

Fructose accumulation in the urine (fructose not broken down into fructose 1P)

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3
Q

What are the consequences of Aldose B deficiency?

A
  • Fructose 1P accumulates in the liver - Fructose 1P is osmotically active and leads to liver damage/failure when water is pulled into the liver
  • Decreased cellular Pi levels because it is not released since Fructose 1P is not broken down - this causes hypoglycemia because there is a decrease in liver glycogenolysis (no Pi to release Glucose 6P) AND decrease in ATP synthesis/gluconeogenesis (no Pi to make ATP)
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4
Q

What is the recommended therapy for Aldose B deficiency?

A

Avoid dietary fructose and sucrose intake

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5
Q

What is a disorder of galactose metabolism? Is this disorder considered benign or more severe?

A

Galactose 1P Uridyltransferase deficiency (classical galactosemia) is VERY severe

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6
Q

What are the consequences of Galactose 1P Uridyltransferase deficiency?

A
  • Galactose 1P accumulates in the liver - Galactose 1P is osmotically active and leads to liver damage/failure when water is pulled into the liver
  • Galactose accumulates in the blood (galactosemia) and urine (galactosuria)
  • Galactose in the cells (any type) is converted to galactitol
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7
Q

What are two consequences of galactitol production?

A
  • Cataracts due to galactitol accumulation (galactitol leads to increased cellular osmolarity in the lens)
  • Kidney and nerve tissue damage
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8
Q

What is the alternative name for Galactose 1P Uridyltransferase deficiency?

A

Classical galactosemia

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9
Q

What is the alternative name for Fructokinase deficiency?

A

Essential fructosuria

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10
Q

What is the alternative name for Aldose B deficiency?

A

Fructose poisoning

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11
Q

What are Statin drugs? Do they work reversibly or irreversibly? What are they chemically similar to?

A

Stain drugs inhibit HMG CoA Reductase (inhibit second step of De Novo cholesterol synthesis)

  • Work as reversible competitive inhibitors
  • Chemically similar to HMG CoA
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12
Q

Explain the mechanism of Statin drugs (4 parts).

A
  • Inhibited HMG CoA Reductase activity
  • Increased LDL receptor synthesis (as a result of HMG CoA Reductase inhibition)
  • Increased LDL endocytosis
  • Decreased serum LDL-cholesterol
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13
Q

What are bile acid sequestrants? What is an alternative name, and give an example of a bile acid sequestrant.

A

Bile acid sequestrants (aka resins) work as a charged resin which forms ionic bonds with bile acids - bile acids cannot then be recycled and must be excreted in the feces

Example of Resin: Cholestyramine

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14
Q

Explain the mechanism of bile acid sequestrant drugs (5 parts).

A
  • Decreased cytosolic cholesterol (cholesterol in the cell is used in De Novo cholesterol synthesis to produce bile acids)
  • Increased LDL receptor synthesis (as a result of HMG CoA Reductase inhibition)
  • Increased LDL endocytosis
  • Activated HMG CoA Reductase activity
  • Decreased serum LDL-cholesterol
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15
Q

What are cholesterol absorption inhibitors and what do they result in? Give an example of a cholesterol absorption inhibitor.

A

Bind to a protein that is important to cholesterol absorption (located in the GI tract epithelium and hepatocytes)

Example of cholesterol absorption inhibitor: Ezetimbe

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16
Q

Explain the mechanism of cholesterol absorption inhibitor drugs (5 parts).

A
  • Decreased cytosolic cholesterol (cholesterol not absorbed)
  • Increased LDL receptor synthesis (as a result of HMG CoA Reductase inhibition)
  • Increased LDL endocytosis
  • Activated HMG CoA Reductase activity
  • Decreased serum LDL-cholesterol
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17
Q

Provide two examples of combination drug therapy.

A
  • Statins/Cholestyramine

- Statins/Ezetimbe

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18
Q

What is there a deficiency of in Familial Hypercholesterolemia? What is the mechanism of this disorder?

A

Familial Hypercholesterolemia is a deficiency of the LDL receptor

  • Decreased LDL receptors means decreased LDL endocytosis resulting in increased serum LDL
  • Cytosolic cholesterol is also decreased resulting in increased HMG CoA Reductase activity and De Novo cholesterol synthesis
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19
Q

What is the alternative name for Familial Hypercholesterolemia?

A

Type IIa Hyperlipidemia

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20
Q

What are three clinical presentations of Familial Hypercholesterolemia?

A
  • Xanthoma on extremities
  • Corneal arcus (grey/white ring around cornea)
  • Atherosclerosis (higher risk for cardiovascular disease)
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21
Q

What does the lipid profile for Familial Hypercholesterolemia look like?

A
  • High LDL cholesterol

- Normal TAGs

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22
Q

What is the recommended therapy for Familial Hypercholesterolemia?

A

Reduction in dietary cholesterol and saturated fats; Combination drug therapy

23
Q

Why does cholelithiasis occur?

A

Gallstones form as a result of abnormal bile composition (high free cholesterol and low bile acids)

24
Q

What are the five risk factors for cholelithiasis?

A
  • Fat
  • Forty
  • Female
  • Fertile (high estrogen levels)
  • Fibrates (drugs that inhibit cholesterol 7-alpha-hydroxylase, which converts C to bile acids)
25
Q

What is the solvent and solute in saturated solution? Why is this significant?

A

Cholesterol is the solute and bile acids are the solvent
- Cholesterol is water insoluble and requires a solvent in supersaturated solutions in order to prevent crystal formation

26
Q

What are the two treatment options for cholelithiasis and which is more common?

A
  • Cholecystectomy (more common)

- Administration of exogenous ursodeoxycholic acid (medication) that supplements the body’s supply of bile acids

27
Q

What is there a deficiency of in Familial Chylomicronemia?

What is the consequence of Familial Chylomicronemia?

A

Familial Chylomicronemia is a deficiency of LPL or Apo C-II

TAGs in the CM are not hydrolyzed and remain in the CM (CMs are TAG-rich)

28
Q

What does the lipid profile for Familial Chylomicronemia look like?

A

Elevated fasting CM (high TAGs)

Top creamy layer with centrifugation

29
Q

What are two clinical presentations of Familial Chylomicronemia?

A
  • Xanthomata

- Pancreatitis (can be caused by high triglycerides)

30
Q

Does Familial Chylomicronemia increase risk for heart disease?

A

NO

31
Q

What are the two recommended treatments of Familial Chylomicronemia?

A
  • Consume short- and medium-chain containing TAGs

- Fat-soluble vitamin supplementation

32
Q

What is an alternative name for Familial Chylomicronemia?

A

Type I Hyperlipidemia

33
Q

What is the cause of Abetalipoproteinemia?

What is the consequence of Abetalipoproteinemia?

A

Loss of function in MTP gene (deficient MTP)

TAGs are not transferred to nascent CMs or VLDLs (cannot be assembled)

34
Q

What does the lipid profile for Abetalipoproteinemia look like?

A

CM, VLDL, and LDL are almost absent in plasma which leads to hypolipidemia

35
Q

What are four clinical presentations of Abetalipoproteinemia?

A
  • Failure to thrive
  • Dietary fat accumulation in enterocytes
  • Steatorrhea
  • Neurological defects due to malabsorption of fat-soluble vitamins
36
Q

What are the two recommended treatments of Abetalipoproteinemia?

A
  • Low-fat, calorie-rich diet

- Fat-soluble vitamin supplementation

37
Q

What is an alternative name for Abetalipoproteinemia?

A

CM Retention disease

38
Q

What is the cause of Familial Combined Hyperlipidemia Type IIb? What are the secondary causes?

What is the consequence of Familial Combined Hyperlipidemia Type IIb?

A

Over production of Apo B-100
Secondary: obesity, metabolic syndrome, DM, HTN

Excessive production of VLDLs

39
Q

What does the lipid profile for Familial Combined Hyperlipidemia Type IIb look like?

A
  • Elevated VLDLs (high TAGs)
  • Elevated LDLs (high CEs)
  • Decreased HDL
40
Q

What is the increased risk associated with Familial Combined Hyperlipidemia Type IIb?

A

Higher risk for premature heart disease

41
Q

What are the two recommended treatments of Familial Combined Hyperlipidemia Type IIb?

A
  • Combined drug therapy (Niacin to reduce high TAGs and Statins or Resins to reduce high CEs)
  • Secondarily, diet and lifestyle changes
42
Q

What is the cause of Familial Disbetalipoproteinemia Type III? What are the secondary causes?

What is the consequence of Familial Disbetalipoproteinemia Type III?

A

Variation of Apo E protein (Apo E2 variant binds poorly to Apo E receptor)
Secondary: high fat diet, DM, obesity, alcohol, hypothyroidism, estrogen deficiency

There is decreased clearing of IDLs and CM remnants

43
Q

What does the lipid profile for Familial Disbetalipoproteinemia Type III look like?

A
  • Elevated IDLs

- Elevated CM remnants

44
Q

What are four clinical presentations of Familial Disbetalipoproteinemia Type III?

A
  • Tuboeruptive xanthomata
  • Palmar striated xanthomata
  • High risk for premature heart disease
  • High risk for peripheral vascular disease
45
Q

What are the two recommended treatments of Familial Disbetalipoproteinemia Type III?

A
  • Combined drug therapy (Niacin to reduce high TAGs and Statins or Resins to reduce high CEs)
  • Secondarily, diet and lifestyle changes
46
Q

In individuals with increased CETP activity, does their lipid profile demonstrate elevated LDLs or HDLs? Is their risk for atherosclerosis increased or decreased?

A

LDLs because when CE is sent to the VLDLs from HDL, the HDL becomes unstable - risk for atherosclerosis is increased

Lower CETP activity is preferred

47
Q

What is there a deficiency of in Tangier disease?

What are the three consequences of Tangier disease?

A

Tangier disease is a deficiency in ABCA1 protein

  • Deficient transport of cholesterol out of peripheral cells causing cholesterol accumulation in the tissues
  • Prevents HDL from maturing (no ABCA1 protein so cholesterol is not moved into HDL from peripheral tissues)
  • Impaired transfer of Apo C-II and Apo E
48
Q

What does the lipid profile for Tangier disease look like?

A
  • Low HDL

- Low LDL

49
Q

What are four clinical presentations of Tangier disease?

A
  • Enlarged, orange tonsils
  • Premature MI
  • Cornea clouding
  • Hepatosplenomegaly
  • Intermittent peripheral neuropathy due to CM accumulation
50
Q

Is there a treatment for Tangier disease?

A

NO

51
Q

What is an alternative name for Tangier disease?

A

alpha-lipoprotein deficiency

52
Q

What are two drugs used to treat hyperTAG and to increase HDL?

A

Niacin and Fibrates

53
Q

How does Niacin lower serum TAGs and increase serum HDL?

A
  • Lower serum TAGs: niacin inhibits HSL and lipolysis therefore decreasing VLDL and LDL production
  • Increase serum HDL: niacin decreases the breakdown of Apo A-I, extending HDL half-life
54
Q

How do Fibrates lower serum TAGs and increase serum HDL?

A
  • Lower serum TAGs: fibrates activate LPL (more TAGs broken down and increase in VLDL clearance; also decreased secretion of nascent VLDLs)
  • Increase serum HDL: fibrates increase Apo A-I gene expression, producing more Apo A-I and ultimately HDLs

Biochemistry Exam #2 (5 decks)

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