Basic Science Oite 2015

Front 1

Increased levels of perosixome, proliferator activated receptor gamma 2 (PPARy2) results in increased:

Back 1

adipose formation. PPARy2 is a stimulator of adipogenesis.

Front 2

What transcription factor stimulates bone formation?

Back 2

Runt-related transcription factor (colonization factor antigen 1).

Front 3

What transcription factor stimulates chondrogenesis?

Back 3

Sox 9 stimulates chondrogenesis.

Front 4

What transcription factor stimulates myogenesis?

Back 4

Myocyte enhancer factor-2.

Front 5

What transcription factor stimulates tendon/ligament development?

Back 5

Scleraxis stimulates tendon and ligament development.

Front 6

What is the mechanism of anticoagulation of heparin?

Back 6

Heparin activates antithrombin III. Heparin binds AT III and causes a conformational change resulting in activation through increased flexibility of AT III reactive site loop. ATIII then deactivates thombin, factor Xa and other proteases that stimulate clotting.

Front 7

Warfarin works by blocking the ____________ complex and therefore creates vitamin _____ deficiency. Vitamin _____ then cannot add a carboxyl group to glutamic acid residues on factors II, VII, IX, and X and proteins _____ & _____.

Back 7

VKOOR complex

Vitamin K deficiency

Vitamin K can't carboxyate

Proteins C and S.

Front 8

Protein C and S promote clotting or bleeding?

Back 8

They promote anticoagulation.

Front 9

What is the mechanism of action of ASA?

Back 9

Inhibits thromboxanes and prostaglandins through it's irreversible binding of COX enzyme (acetyl group covalently binds to serine residue on COX).

Thomboxane is responsible for clotting via platelet aggregation and prostaglandins are responsible for transmission of pain signal and inflammation.

Front 10

What is the reversal agent for heparin?

Back 10

Protamine sulfate

Front 11

What anticoagulant specifically targets factor Xa through ATIII?

Back 11

Fondaparinux. Decreased incidence of DVT in hip fracture and TKA when compared to enoxaparin, however, fonda has the highest bleeding risk.

Front 12

Rovaroxaban is a direct factor ________ inhibitor

Back 12

Direct Factor Xa inhibtor (fonda still acts through ATIII). No reversal agent.

Front 13

Describe the mechanis of action of tranexamic acid as an antifibrinolytic (promotes stabilization of clot formation).

Back 13

Normally, tPA binds plasminogen and converts it to plasmin and plasmin stimulates fibrinoylsis. TXA competitively inhibits plasminogen activation by binding the lysine binding site on plasminogen that would normally be bound by tPA. Therefore, plasminogen is not activated to plasmin, so there is no plasmin to promote fibrinolysis so blood clots are stabilized.

Front 14

What is the most likely cause of pseudotumor in a well-positioned total hip arthroplasty?

Back 14

There has to be metal-on-metal contact somewhere in the construct. It is much for common for this to be due to fretting and corrosion reaction from the taper. Could also be from catastrophic polyethylen failure with metal-on-metal contact, but this would be much more rare.

Front 15

Which gait pattern is most likely associated with knee osteoarthritis progression?

Back 15

Gait pattern is increased adductor moment. This is described as rapid tibial adduction = increased medial compartment loading.

Front 16

Describe an ACL protective gait.

Back 16

Ambulating with the knee flexed to reduce shift in the knee.

Front 17

What is a major controlling molecule for tendon collagen fiber size?

Back 17

Decorin is influential in collagen fiber size for tendon formation and repair after injury.

Front 18

What role does elastin play in tendon anatomy/function?

Back 18

Elastin is associated with tendon crimp.

Front 19

What molecule is important in INITIAL tendon development but not fibrillar control?

Back 19

Biglycan is important in initial tendon development.

Front 20

Fibrillin is associated with ____________ deposition.

Back 20

Elastin deposition.

Front 21

Which molecule has a role in cell adhesion, growth, cell migration and development?

Back 21

Fibronectin.

Front 22

What is the major cause of age-related increase in articular cartilage brittleness?

Back 22

The gradual passive covalent bonding of sugars to collagen over time results in advanced glycation end products along with brittleness and yellowish appearance of cartilage in older people.

Front 23

The primary muscle energy source for a marathon runner is:

Back 23

Glycogen and fatty acids. Slow twitch muscles can use fatty acids and glycogen for an energy source.

Front 24

Describe the products used in anaerobic muscle metabolism

Back 24

ATP + creatine phosphate, ATP + creatine phosphate + glycogen and glycogen alone.

Front 25

Which molecule is most responsible for hydration of the intervertebral disk?

Back 25

Aggrecan. Aggrecan has an avidity for water 50:1 due to the large amount of glycosaminoglycans within their carboxyl and sulfate groups. Collagen has hydrophilic regions, but lower avidity.

Front 26

What is the mechanism of action for denosumab in treatment of osteoporosis?

Back 26

Inhibits RANKL.

Front 27

What is the function of sclerostin in adult bone homeostastis?

Back 27

Sclerostin decreases bone formation by inhibiting osteoblastogenesis. They are currently developing an antibody to sclerostin for potential use in osteoporosis.

Front 28

Ater initial arthroplasty surgery, infection that occurs within _____________ days is considered a surgical-site infection?

Back 28

365 days!. Surgical site infections are defined as those that occur within 30days of initial surgery, however, for surgery involving implants (hardware, arthroplasty) the surgical site infection period is extended to 1 year!

Front 29

What is the inheritance pattern for Duschennes; muscular dystrophy?

Back 29

X linked recessive- mutation of DMD gene on Xp21.

This is due to the absence of the dystrophin protein which anchors muscle cell cytoskeleton to the surround extracellular matrix. In its absence, there is muscle cell membrane disruption and muscle wasting.

1/3 of cases are due to sporadic mutation.

Front 30

Which factor is most commonly used to stimulate cartilage regeneration in vitro?

Back 30

Transforming growth factor beta (TGF-beta) is used to stimulate chondrogenesis in stem cells and chondrocytes.

Front 31

Which immune cell type is involved in metal allergy associated with orthopedic implants?

Back 31

T lymphocytes. T lymphocytes cause a hypersensitivity reaction and T cells secrete cytokines due to the ionic degradation products from metal implants. This can result in dermatitis, urticaria, vasculitis. Usually associated with cobalt, nickel, chromium.

Front 32

Which ion and ion channel is responsible for a nerve action potential?

Back 32

Sodium ion through voltage-gated sodium channels. As sodium ions enter the cell, the membrane potential changes from negative to positive and the action potential propagates along the axon.

Front 33

In the disease process pictured in this 50 year old man, with elevates alk phos, which cell type is abnormal?

Back 33

This is Pagets disease of bone. Osteoclasts are altered, leading to increased bone resorption and a compensatory increase in bone deposition by osteoblasts. = increased bone remodeling rate and fragile bones. They also have elevated urine hydroxyproline. There is a combined lytic and sclerotic phase resulting in histology of disorganized bone "osteoblasts gone wild," non-lamellar, marbled bone.

Front 34

Where does the muscle involved in lateral epicondylitis insert?

Back 34

Primary muscle involved is the extensor carpi radialis brevis which inserts on the base of the third metacarpal and is involved in wrist extension.

Front 35

Where does the extensor carpi radialis longus insert?

Back 35

Inserts on the base of the 2nd metacarpal.

Front 36

Where does the extensor carpi ulnaris insert?

Back 36

ECU inserts on the based of the 5th metacarpal.

Front 37

Where does the brachioradialis insert?

Back 37

Inserts on the radial styloid

Front 38

What tendon inserts on the fourth metacarpal?

Back 38

None!

Front 39

What symptoms would you expect in a patient with this MRI?

Back 39

This shows a L5-S1 paracentral lumbar disc herniation. Will result in plantar numbness, weak gastroc and decreased achilles tendon reflex.

Front 40

What happens to size and cellularity of the nucleus pulposis proportional to the intervertebral disk after birth.

Back 40

There is decrease in size and cellularity. The nucleus pulposus is derived from the notocord during embryogenesis and retains some notochord cells after birth. However, throughout life, the notochord cells become fewer in number and chondrocyte-like cells can be found in the nucleus.

Front 41

All ligaments and tendons are made up primarily of ______________

Back 41

Type I collagen. Elastin and proteoglycans are also found in tendons and ligaments, but they are not the predominant fiber type.

Front 42

Articular cartilage is made up of ___________

Back 42

Type II collagen.

Front 43

According to the WHO, how is osteopenia defined based on DXA?

Back 43

T-score between 1 - 2.5 standard deviations below the norm. T score is in comparison to the mean bone density for a healthy 30 year old adult of the same gender.

Front 44

Hemophilia A and B are transmitted by which inheritance pattern?

Back 44

X-linked recessive.

Front 45

42 year old woman with slow growing mass in her right knee. What is the translocation?

Back 45

This is synovial sarcoma. Translocation is X:18. Characterized on MR by low signal on T1 and high signal on T2. Histology shows spindle cells with pleomorphism (not uniform appearance from cell to cell).

Front 46

Reading DNA by RNA polymerase and converting this to mRNA is known as:

Back 46

Transcription.

Front 47

The conversion of mRNA to protein by ribosomes is known as

Back 47

Translation.

Front 48

True or False

Achondroplasia is caused by mutation of FGFR3 which leads to a gain in function of FGFR3 (turned on).

Back 48

True! This is a "gain of function" mutation. This causes uncontrolled activation of FGFR-3 which causes impaired growth in proliferative zone of the physis. Achondroplasia has an autosomal dominant inheritance pattern, however, 80% of mutations are sporadic.

Front 49

What factors promote inflammation-related osteolysis around orthopaedic implants?

Back 49

IL-6

IL-1

TNF- alpha

RANKL

PGE2

Front 50

What factors block or neutralize the osteolytic cascade?

Back 50

IL-1 receptor antagonist

Osteoprotegrin

IFN gamma

IL-4

IL-10

Front 51

Materials that demonstrate stress-strain behaviors that are time dependent are:

Back 51

viscoelastic

Front 52

A materail that can undergo large strains during plastic deformation before failure have high _________

Back 52

ductility

Front 53

Materails that have very little plastic deformation before fracture and fail in tension at low strain are termed:

Back 53

brittle

Front 54

A material that has the same mechanical properties in all DIRECTIONS is :

Back 54

isotropic

Front 55

A material that exhibits varying mechanical properties with different loading directions is termed:

Back 55

anisotropic. Think aniso = can change shape.

Front 56

What is the name of the genetic phenomenon by which a child experiences earlier onset and more severe form of a disease inherited from their parent?

Back 56

Anticipation. This is because during meiosis, specific trinucleotide repeats are expanded in number, resulting in earlier expression of a mutation.

Front 57

Loss of telomere length is associated with:

Back 57

aging

Front 58

Lyonization is defined as:

Back 58

the inactivation of 1 of 2 copies of the X chromosome in females.

Front 59

An inactivating mutation in the receptor for 1,25(OH)2 vitamin D3 is the cause of what bone metabolic disorder?

Back 59

Type II vitamin D dependent rickets.

Front 60

Decreased reabsorption of phosphate in the kidneys defines

Back 60

Familial hypophosphatemic rickets. This is also known as vitamin D resistant rickets.

X linked dominant

Front 61

Decreased conversion of 25 vitD to 1,25 Vitamin D3 by the kidneys and secondary hyperparathyroidism due to elevated phosphate from poor kidney excretion is part of what disease process?

Back 61

Renal osteodystrophy.

Front 62

What lab values are characteristic of hypophosphatasia?

Back 62

Low alk phos and high urine phosphoethanolamine.

Front 63

When providing a patient with a second opinion, do you have to disclose the error of a prior physician if you believe there was an error in the treatment?

Back 63

Yes. You are ethically bound to disclose all relevant facts, including the possibility of surgeon error. However, you are not legally bound.

Front 64

In the setting of spousal abuse, is the physician required to report this abuse to the authorities?

Back 64

No. Child abuse, the physician must report, however, in the setting of spousal abuse, the physician does not have to report, but must encourage the patient to pursue self protection.

Front 65

What affect on nerve transmission does a thicker myelin sheath have?

Back 65

Increased myelin sheath thickness = increased propagation speed. Depolarization and refractory periods are not affected by thickness of myelin sheath.