Muscle 8

Question 1

How much muscle mass is lost from 20-80?

Answer 1

50%

Question 2

How does muscle change with age?

Answer 2

Increase in fat mass and non muscle fat free mass

Question 3

What happens to protein balance with age?

Answer 3

Protein breakdown exceeds synthesis-negative protein balance

Question 4

What is sarcopenia and where is it noticeable?

Answer 4

• Loss of skeletal muscle mass, strength and power with aging and inactivity
• Most notable in weight bearing lower limb and trunk muscle groups

Question 5

What fibre type does sarcopenia affect?

Answer 5

Type II myofibre atrophy, myofibre type grouping and fibre necrosis

Question 6

What happens to the food response with age?

Answer 6

Reduced anabolic food response - blunted increase in protein synthesis with food intake

Question 7

What happens to basal blood glucose levels in ICU patients?

Answer 7

Increased - hyperglycaemic - impairs other cellular processes

Question 8

How much muscle mass lost in 10 days in ICU and what impact does multi-organ failure have?

Answer 8

20%

Muscle mass exacerbated and more rapid

Question 9

When did patients in ICU have reduced muscle quality and what did this consist of?

Answer 9

Day 7

Infiltration of non-muscle cell types and macrophages - inflammation and muscle breakdown

Question 10

What % of functional capacity do ICU patients recover?

Answer 10

70%

Question 11

What did exercise do for ICU patients?

Answer 11

Stand after 11 days instead of 15

Question 12

What does LPS (lipopolysaccharide) cause?

Answer 12

Translocation of NFB to nucleus - pro inflammatory cytokines released

Question 13

What does LPS do to protein synthesis?

Answer 13

No change in protein breakdown markers but 40-50% reduction in protein synthesis

Question 14

What is the initial effect of LPS?

Answer 14

Stops animals eating

Question 15

What effect does LPS have on glucose levels and body mass?

Answer 15

• LPS reduced circulating blood glucose - stimulates glucose uptake to tissues
• LPS admin leads to reduced body mass - within 24 hours reduced muscle mass by 25%

Question 16

What does a tumour cause?

Answer 16

• Secretes inflammatory factors - apoptosis
• Alters protein, fat, CHO and aa metabolism across the body
• Increased protein breakdown and aa oxidation
• Decreased protein synthesis and amino acid transport

Question 17

What happens with amino acids if there is increased protein breakdown?

Answer 17

Increased release (alanine and glutamine)

Question 18

Why is glutamine important for tumours?

Answer 18

Glutamine released from skeletal muscle is rapidly taken up by the tumour - can be converted to serine and shunted into carbon metabolism to increase growth of cells

Question 19

How do tumour cells get energy?

Answer 19

Increase glucose output from liver

Question 20

What happens to IGF-1 and myostatin levels in cancer?

Answer 20

Reduced IGF-1: decreased protein synthesis

Myostain: increases and supresses protein synthesis

Question 21

What does FOXO do?

Answer 21

Increased transcription of MAFBX and MURF1 (E3 ligases) - regulate protein breakdown

Question 22

What reduction in muscle mass does cancer cachexia lead to?

Answer 22

15-25%

Question 23

What does Atrogin1/MAFBX do?

Answer 23

Tags proteins for breakdown, and directly regulates protein synthesis by reducing capacity of protein synthetic machinery

Question 24

What is eLF3-f important for?

Answer 24

Binds to mTOR to start translation and protein synthesis

Question 25

How does turmeric affect inflammation?

Answer 25

Reduces TNF, IL-6, IL-1, IL-8 and increases Akt

Question 26

What happened to tumour bearing mice when given turmeric?

Answer 26

40% reduction in protein breakdown

Reduced loss in body weight

Question 27

How does glycine affect tumour bearing mice?

Answer 27

Glycine reduced loss of extra muscle mass. Supplementing with glycine reduced tumour growth by 30%. Inflammatory cytokine expression reduced