Hyperlipidaemias Flashcards

1
Q

What is atherosclerosis?

A

build up of plaque in arteries = thickening or hardening of arteries

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2
Q

What are the stages of atherosclerosis?

A
  1. LDLs travel through endothelial barrier lumen
  2. LDL oxidised
  3. macrophages attracted to oxidied LDL, also enter artery wall
  4. macrophage phagocytose oxidised LDL = foam cell
  5. foam cells expand
    - undergo death, release lipid content = recruitment of inflammatory cytokines
    - growth factors released = smooth muscle proliferation = ⬆ collagen synthesis = hardening of plaque
  6. plaque-> narrowing of artery
  7. plaque can rupture -> thrombosis = risk of clots
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3
Q

what is foam cell filled with?

A

lipids

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4
Q

whats plaque in wall (atherosclerosis) made of? 5

A
dead foam cells
foam cells
immune cells
collagen
smooth muscle cells
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5
Q

What is the structure of lipoproteins?

A

lipid core of trigl + cholesterol esters

coat containing apoproteins - mediate binding of lipoproteins with tissues in body using receptors on those tissues

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6
Q

what about a lipoprotein affects which tissue and receptor it will bind to?

A

coat containing apoproteins- type affects..

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7
Q

name some lipproteins

A

chylomicrons
VLDL
LDL
HDL

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8
Q

transport pathways of lipoproteins?

A

exogenous

endogenous

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9
Q

Which lipid pathway involves lipids in the diet?

A

exogenous

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10
Q

What are lipids (TGs and cholesterol esters) emulsified by in the GIT?

A

bile acids

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11
Q

lipids are emsulsified in the GIT.. what are absorbed into?

A

chylomicrons

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12
Q

Explain how a foam cell is formed?

A
  • LDL travels through endothelial barrier -> lining of artery
  • LDL oxidised
  • macrophages attracted and enter lining
  • macrophages phagocytose oxidised LDL forming a foam cell
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13
Q

What do foam cells do after they are formed?

A
  • continue to expand
  • undergo death
  • release lipid content and recruit inflammatory cytokines
  • release growth factors
  • smooth muscle proliferates
  • increased collagen synthesis
  • plaque hardens
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14
Q

What is the consequence of plaque rupturing?

A

thrombosis

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15
Q

Describe the exogenous lipid pathway

A

involves lipid in the diet
emulsified by bile acids in the GIT
lipids absorbed into chylomicons
triglycerides hydrolysed by lipoportein lipase, produces free fatty acids = absorbed and stored in fat and muscle tissues
chylomicron remnants - taken up by hepatocytes = store of cholesterol

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16
Q

Describe the endogenous lipid pathway

A

liver
makes C and TG from exogenous pathway
lipids excreted into VLDL
TGS hydrolysed by same enzyme, fatty acids produced and stored in tissues
LDLS now contain mainly cholesterol esters
extrahepatic
cholesterol from cell turnover absorbed into HDL
cholesterol esters transferred to LDL and VLDL
increased HDL promotes LDL removal

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17
Q

What are TGs hydrolysed by to produce free fatty acids?

A

lipoprotein lipase

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18
Q

Where are free fatty acids absorbed and stored?

A

fat and muscle tissues

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19
Q

What are chylomicrons an excess of?

A

TG

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20
Q

what are chylomicron REMNANTS an excess of and how do they appear in liver?

A

CE (cholesterol)

yellow!

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21
Q

What are chylomicrons taken up in order to contribute to the store in the liver?

A

hepatocytes

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22
Q

Endogenous pathway:

2 sites

A

liver

extrahepatic (reverse cholesterol transport)

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23
Q

liver makes cholesterol (C) and TG + C from what pathway?

A

exogenous

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24
Q

What is Acetyl co enzyme A converted to in the liver?

what enz is involved?

A

ACoA —- > MVA (Mevalonate)

HMG CoA reductase

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25
Q

After mevalonate is formed what gets secreted into VLDLs?

A

lipids (both TG and cholesterol esters CE)

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26
Q

In the endogenous pathway VLDLs travel through muscle and fat tissue and bind to receptors on the wall of muscle and fat tissue. What are they hydrolysed to?

A

free fatty acids

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27
Q

What do LDLs mostly contain at the end of the endogenous pathway in the liver?

A

cholesterol esters

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28
Q

The extra hepatic pathway is called the reverse cholesteral transport. What is absorbed into HDL from cell turnover?

A

cholesterol

and from developing plaques

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29
Q

HDLs contain cholesterol esters in the extra hepatic pathway but do not travel. What happens to them instead?

A

transferred to VLDLs and LDLs via CETP, change in apoprotein = more likely to be taken up by hepatocytes due to ⬆ levels of HDLs

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30
Q

Give 3 uses of LDLs in the body?

A

membranes, steroids and bile acids

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31
Q

What is dyslipidaemia? and how fixed?

A

high LDL (i.e. cholesterol) - drugs given

low HDL - exercise, less alcohol

32
Q

Drugs used for prevention even if lipids are normal should only be used if what are present?

A

other risk factors

33
Q

What is hyperlipidaemia usually an increase of?

A

lipoproteins

34
Q

What are the types of hyperlipidaemia?

A

primary (genetic)
risk of atherosclerosis

secondary
metabolic disorders
diabetes, hyperthyroidism, renal disease, alcoholism

35
Q

Primary hyperlipidaemia is genetic, how many phenotypes are there?

A

6, differ in lipoprotein class affected

36
Q

How can increased LDLs increase the risk of atherosclerosis and thrombosis?

A

LDL contains apoprotein similar to plasminogen, competes for receptors so less plasmin therefore thombus can form (inc thrombosis)

37
Q

List 3 things that can cause secondary hyperlipidaemia?

A

diabetes, hyperthyroidism and alcoholism

38
Q

HMC CoA reductase inhibitors/ statins such as atorvastatin, simvastatin and pravastatin can be used to….

A

reduce high cholesterol levels

39
Q

describe statins

A

prodrugs

potent competitive inhibitors of HMG CoA reductase

40
Q

What statins work to decrease the synthesis of?

A

cholesterol

41
Q

Why is the synthesis of cholesterol in the hepatocytes not reduced as much as we would like?

A
  • statins competitively inhibit HMG CoA reductase
  • ⬇ cholesterol
  • ⬆ transcription for genes that encodes HMG CoA enzyme and LDL receptor
  • ⬆ cholesterol synthesis and LDL receptor expression on hepatocytes
42
Q

What do the increased LDL receptors on hepatocytes bind to in the blood which has been shown to be clinical benefit of statins?

A

circulating LDL particles in blood

= reduces LDL blood cholesterol levels

43
Q

Why are statins contraindicated in pregnancy?

A

lipids are necessary for proper fetal development

..decreased synthesis of cholesterol affects fetal development

44
Q

What statin would be used for

  • high intensity
  • low intensity
A
  • atorvastatin

- pravastatin

45
Q

side effects of statins?

A

myositis
hepatitis
rhabomyolysis

46
Q

another word for hmg reductase inhibitor?

A

statin

47
Q

How does PCSK9 increase circulating LDLs?

A

binds to LDL-R and promotes its degredation

48
Q

What does a PCSK9 inhibitor do? work?

A

Increase the number of LDL receptors available increase uptake into hepatocytes to decrease plasma LDL

49
Q

example of PCSK9 inhibitor?

A

evolocumab (monoclonal antibody)

50
Q

What type of drug would be used for increased TGs? give examples

A

Fibrates

bezafibrate, gemfibrozil

51
Q

How do fibrates work?

A

decrease TGs

activate nuclear receptors = ⬆transcription
activation of lipoprotein lipase = ⬇VLDL production = less TGs (VLDL) = more liver uptake of LDL via more receptors for apoproteins = more HDL

52
Q

What types of lipids can increase with fibrates?

A

HDLs

53
Q

one adverse effect of fibrates ?

A

myositis esp w xs alcohol; care with statins

54
Q

fibrates uses?

A

increased TGs esp type IIb

- statin 1st choice!

55
Q

Why are resins lost along with bile acids and cholesterol?

A

too big

56
Q

What can be reabsorbed/used via enterohepatic circulation?

A

bile acids

57
Q

bile acids essential for ?

A

cholesterol absorption and reabsorbed via enterohepatic recirculation

58
Q

How do bile acid-binding resins work?

A

lose cholesterol and bile acids = more synthesis of bile acids = less liver cholesterol as stores used up = more LDL receptors..

or:
Lower LDL by interrupting enterohepatic circulation of bile acids which stimulates conversation of cholesterol into bile acids

59
Q

which type of lipid increases with bile acid binding resins?

A

TGs

60
Q

List some cons of bile acid binding resins?

A

resins unpleasant, GI side effects and cause vitamin deficiency

not first line… combine w statin

61
Q

How does ezetimibe work?

A

inhibits intestinal absorption of cholesterol by blocking receptor uptake (transport protein NPC1L1)

62
Q

Can ezetimibe be used with statins?

A

not first line on its own but yes

63
Q

Ezetimibe has a higher potency than resins (dose 10mg) but has no effect on the absorption of what?

A

fat soluble vitamins

64
Q

Describe use of ezetimibe.

A

inhibits intestinal absorption of cholesterol
blocks receptor uptake
no evidence of decreased atherosclerosis
more specific action in gut

65
Q

How do nicotinic acids work?

A

decreased synthesis of TGs = less VLDLs = less LDL = more HDL

66
Q

Why can nicotinic acid cause pruritis?

A

releases prostaglandins

67
Q

Name two other common side effects of nicotinic acid?

A

common intense flush and jaundice

68
Q

Why might fish oil be good for patients after MI?

A

alpha tricglycerides improve survival

69
Q

Whats the mechanism of fish oil?

A

decreases clotting by inhibiting platelet aggregation and prolonging of clot formation

70
Q

Why is fish oil not suitable for type 2 hyperlipidaemia?

A

cholesterol levels increase

71
Q

What effect might fish oil have on platelets and clotting?

A

inhibit aggregation and reduce clotting

72
Q

What is the first line drug class for primary prevention hyperlipidaemia ( and for all diabetics over 40)?

A

statins

73
Q

What are two other drugs/ drug classes that statins can be combined with?

A

PCSK9 inhibitors and ezetimibe

74
Q

For the secondary prevention of hyperlipidaemia, statins are first line. What may be added to the regimen and used in combination with statins?

A

fibrate or bile acid resin or nicotinic acid

care w fibrate+ statin

75
Q

secondary prevention drug to be used on its own, w/out statin?

A

nicotinic acid

76
Q

What is the first line drug class used in the treatment of hyperlipidaemia?

A

statins

77
Q

drugs for hyperlipidaemia MoA?

A

inc chol- statin + ezetimibe/ PCSK9 inhibitor
or
in TG- statin? + fibrate (myositis!)