triglycerides

Question 1

sources of TG

Answer 1

dietary TG (processed in intestinal cells)
de novo TG (in liver hepatocytes)
de novo TG (in adipocytes)

Question 2

lipases involved in breakdown of TGs in adipocyte

Answer 2

hormone sensitive lipase (HSL)
lipoprotein lipase
monoacylglycerol lipase

Question 3

promote lipolysis in adipocytes by acting on hormone sensitive lipase (HSL)

Answer 3

glucagon (secreted in response to hunger)

epinephrine (secreted in response to exercise)

Question 4

inhibit lipolysis in adipocytes by acting on hormone sensitive lipase (HSL)

Answer 4

insulin (secreted in response to high carb meal)

Question 5

perilipins are..? Fx? how many types?

Answer 5

family of proteins coating lipid droplets in adipocytes and muscle cells

• regulate lipolysis by controlling physical acces to HSL
• humans have 5 members in the family

Question 6

perilipin 1

Answer 6

• overexpression inhibits lipolysis
• knockout PROMOTES lipolysis
• regulated by PKA (phosphorylation allows assoication with HSL and promotes lipolysis)
• target of obesity treatment

Question 7

what is olestra?

Answer 7

• synthetic fat made of sucrose backbone with 6-8 FA
• NOT absorbed in small intestine
• no calories
• excreted out in stool

Question 8

issue with olestra

Answer 8

absorbs vitamins A, D, E, K

• high amounts causes deficiency in these vitamins
• abdominal cramps, bloating, diarrhea

Question 9

serve as transport vehicle for cholesterol, TGs, fat soluble vitamins

Answer 9

lipoproteins

Question 10

structure of lipoproteins

Answer 10

outer shell: monolayer of phospholipids, free cholesterol and apolipoprotiens (ALP)
inner core: packed with hydrophobic TGs, cholesterol esters

Question 11

converts free cholesterol into extremely hydrophobic cholesterol esters stored in lipid droplets

Answer 11

Acyl CoA Acyl Transferase (ACAT)

Question 12

different types of lipoproteins

Answer 12

chylomicrons
VLDL
LDL "bad cholesterol"
IDL
HDL "good choelsterol"

Question 13

chylomicron properties

Answer 13

largest
least dense
high TG content
exogenous
formed from dietary fats

Question 14

HDL properties

Answer 14

smallest
most dense
high protein and phospholipid content
“good cholesterol” particle

Question 15

ALPs on chylomicron

Answer 15

ApoB-48
ApoE
ApoC-II

Question 16

ALPs on VLDL

Answer 16

ApoB-100
ApoC-II
ApoE

Question 17

ALPs on IDL

Answer 17

ApoB-100

ApoE

Question 18

ALPs on LDL

Answer 18

ApoB-100

Question 19

ALP acting as co-factor to activate capillary lipase

Answer 19

ApoC-II

only present on VLDL, HDL and chylomicrons

Question 20

LDL has a high content of

Answer 20

cholesterol esters

Question 21

ALPs on HDL

Answer 21

ApoA-1
ApoE
ApoC-II

Question 22

swelling of lymph nodes found in

Answer 22

infections

cancer (non-Hodgkin lymphoma)

Question 23

Apoplipoprotein funcitons

Answer 23

• structural (stabilize lipoproteins)
• transport (redistribution of lipids between tissues)
• cofactors for enzymes (e.g. activation of LPL by Apo-CII)

Question 24

cause and effects of Type I hlp: familial hyperchylomicronemia

Answer 24

C: deficiency in apoC-II (cofactor for LPL) or defective lipoprotein lipase
E: chylomicrons ^ and triacylglycerol ^

Question 25

cause and effects of Type IIa hlp: familial hypercholesterolemia

Answer 25

LDL receptor completely defective
E: cholesterol ^
TG: normal
LDL: ^

Question 26

cause and effects of Type IIb hlp: familial hypercholesterolemia

Answer 26

LDL receptor partially defective
E: cholesterol ^
TG: ^
LDL: ^
VLDL: ^

Question 27

Type I hlp: familial hyperchylomicronemia

issue, ages, blood sample, inheritence, clinical symptoms, treatment

Answer 27

• inability to hydrolyze TAGs in chylomicrons and VLDL
  primary LPL def. - infancy
  ApoC-II def. - post adolescence
  plasma TAG levels > 1000 mg/dL
  creamy appearance of blood sample; overnight at 4 C separates into creamy and clear layer
• both autosomal recessive
  s/s - abdominal pain, acute pancreatitis, cutaneous eruptive xanthomas (fat accumulating on skin)
  treatment: low fat diet

Question 28

Type II hlp: familial hypercholesterolemia (FH)

issue, inheritance, cholesterol levels for hetero/homo and their outcomes and treatments, physical symptoms

Answer 28

• increased cholesterol in blood and subsequent atherosclerosis
• impaired ability to recognize ApoB 100 on LDL
• autosomal dominant inheritance
• normal cholesterol 130-200 mg/DL [heterozygous; 300-500 mg/dL, homozygous >800 mg/dL]
• untreated homozygous die of coronary artery disease (CAD) before teenage years; heterozygous develop CAD by 40
  physical symptoms: xanthomas, arcus senilis or corneal deposits in eye, angina pectoris
  heterozygous respond to diet, statins and bile acid binding resins
  homozygous need LDL apheresis and liver transplantation

Question 29

beneficial effects of HDL, whats its job? levels increased by which activities and drugs? HDL levels low in??

Answer 29

• antioxidant and antiinflammatory properties
• reverses cholesterol transport from peripheral tissues to liver
• HDL levels increased by weight loss, exercise, smoking cessation and moderate consumption of alcohol
• antihyperchoelsteremic drugs, fibrates, niacin, antidiabetic thiazolidine drugs, estrogens, omega-3 fatty acids, increase HDL-C
• HDL levels low in smoking, progestins, androgens, beta blockers and high intake of PUFA (omega-6)

Question 30

statins mechanism of action

Answer 30

mimic the structure of HMG CoA and Mevalonate (substrate and product of HMG CoA reductase)

• rate limiting enzyme in cholesterol biosynthesis
• potent competitive inhibitors ==> cholesterol levels fall
• enhances transcription of LDL receptor ==> more uptake into hepatocytes, lowers plasma levels

Question 31

use of statins also effects

Answer 31

production of heme a, dolichol, ubiquinone, prenylated proteins;
bisphosphonates (to treat osteoporosis) also working upstream of these