Research Lec 2 - Ben Perry

Question 1

Career

Answer 1

• Undergraduate degree in Exercise and sport science 2008
• honours in exercise physiology 2009
• doctor of philosophy (PhD), muscle and exercise physiology 2014

Question 2

PhD: applied exercise and muscle physiology

Answer 2

• Investigated how knee injury, osteoarthritis, and physical inactivity affected exercise performance, skeletal muscle function and biochemical signalling
• no effect on 3 weeks on crutches or osteoarthritis on Na+, K+ ATPase content in muscle, but a decrease in young patients with ACL rupture

Question 3

Muscle physiology and biochemistry

Answer 3

• investigated the biomolecular signalling in muscle atrophy using cell culture and obese animal models

Question 4

Skeletal muscle hypertrophy

Answer 4

• skeletal muscle enlarges primarily though hypertrophy of muscle fibres
• myofibre cross sectional area is one of the most important determinants of force production

Question 5

Skeletal muscle atrophy

Answer 5

• a reduction in skeletal muscle cross sectional area is termed” muscle atrophy”
• skeletal muscle atrophy decreases muscle function

Question 6

Skeletal muscle atrophy

Answer 6

Cycle:

• if severe enough, muslce atrophy compromises ability to do everyday tasks
• this further induces physical inactivity and enhances muscle atrophy

Question 7

Biomolecular cause of skeletal muscle atrophy

Answer 7

• caused by an imbalance in muslce contractile protein synthesis and degradation rates

Question 8

Duchenne muscular dystrophy

Answer 8

• one of the severe forms of muscular dystrophy
• allelic x-chromosome linked muscle disorder in men
• due to mutation in dystrophin glycoprotein complex
• causes cytoskeletal and sarcolemmal instability and recurring muscle damage
• muscle does not adequately repair

Question 9

Cancer Cachexia

Answer 9

• almost half of cancer patients exhibit cachexia
• substantial and dangerous loss of muslce and fat mass
• cachexia substantially increases morality in cancer patients ~20%

Question 10

Limb disuse/inactivity

Answer 10

• muscle disuse is a prominent contributor to muscle atrophy
• by itself in a healthy young adult, poses little clinical risk
• can enhance muscle atrophy and further enhance mortality in such conditions
• limb disuse is particularly dangerous in elderly as they have less capacity to regain the muscle mass back

Question 11

Sarcopenis

Answer 11

• muscle loss with ageing
• slowed by exercise, but will still occur
• in elderly patients muscle mass loss can be severe enough to reduce or prevent physical activity
• along with decreased strength, sarcopenia is linked to increased morality, especially with other atrophy-inducing conditions.

Question 12

Type II diabetes mellitus

Answer 12

• Patients w/ T2DM exhibit only subtle muscle atrophy during middle age, but this muscle atrophy is exacerbated with sarcopenia or diabetic neuropathy

Question 13

ER stress and muscle atrophy

Answer 13

• During ER stress, the unfolded protein response (UPR) reduces the production of unfolded or misfolded proteins, and upregulates protein degradation
• Chronic and/or severe ER stress can decrease protein synthesis and upregulate proteolytic pathways, > contributing muscle atrophy

Question 14

Summary of research findings

Answer 14

• Palmitate induces ER stress, induces muscle atrophy, increases protein degradation and decreases protein synthesis in cultured skeletal muscle
• DHA can reverse the effects of paltimate listed above
• TLR4 not responsible for the effects of paltimate on ER stress in skeletal muscle