MS UWorld 2

Question 0

young man with low back pain and morning stiffness with inflammation and early fusion of sacroiliac joint. Dx, associated with

Answer 0

Ankylosing spolndylitis - associated with HLA B27, which is a specific HLA class I serotype

Question 1

Anterior mediastinal mass in myasthenia gravis

Answer 1

Majority of MG patients have thymoma or thymic hyperplasia.

Both the thymus and the inferior parathyroids are from the 3rd pharyngeal pouch

Question 2

Ecthyma gangrenosum

Answer 2

Cutaneous necrotic disease with strong association with pseudomonas bacteremia and septicemia. Bacteria invades perivascularly and release exotoxins that cause vascular destruction and insufficiency to patches of skin.

Question 3

Function of PCL

Answer 3

Prevents anterior motion of femur relative to tibia (or posterior motion of tibia relative to femur) when the knee is flexed.

Question 4

Insect (bee) sting hypersensitivity

Answer 4

Type I

Question 5

Black color of urine upon standing for a while, no other symptoms noted

Answer 5

Alkaptonuria - benign disorder of tyrosine metabolism. Autosomal recessive deficiency of homogentisate oxidase blocks phenylalanine and tyrosine conversion to fumarate. Homogentisic acid accumulates in urine and can oxidize to black color. (it can also cause blue/black pigmentation and arthralgias)

Question 6

14 y/o boy with conductive hearing loss, multiple fractures after minor trauma. Mutation in type I collagen.

Answer 6

Osteogenesis imperfecta

Question 7

Thiazide diuretic side effects

Answer 7

Hypokalemic metabolic acidosis, hyperGLUC: glucose, lipid, uric acid, calcium

Question 8

Antibodies in rheumatoid arthritis

Answer 8

Rheumatoid factor: IgM against Fc portion of self IgG

Question 9

Cystathionine beta synthase deficiency is enzyme defect present in:

Answer 9

classic homocystinuria

Question 10

Pleiotropy

Answer 10

occurrence of multiple phenotypic manifestations often in different organ systems as a result of a single genetic defect

Question 11

Baby with recurrent skin infections without pus formation, delayed separation of umbilical cord

Answer 11

Leukocyte adhesion deficiency, deficiency in CD18 integrin.

Question 12

____ are multinucleate cells responsible for bone resorption

Answer 12

Osteoclasts

Question 13

What are the 2 most important factors for osteoclast differentiation, and where do they come from?

Answer 13

RANK-L and M-CSF both come from osteoblasts

Question 14

Type I (slow twitch) and Type II (fast twitch) fibers - which ones have lots of myoglobin and glycogen?

Answer 14

Type I are aerobic: lots of myoglobin. Postural muslces

Type II are anaerobic, lots of glycogenolysis

Question 15

Long term serum uric acid lowering therapy

Answer 15

Note: really only used for chronic recurrent cases.

Prebenecid/sulfinpyrazone inhibit resorption of uric acid in PCT

Allopurinol and febuxostat are xanthine oxidase inhibitors. Decreases uric acid production in purine metabolism.

Allopurinol is the best choice for tophaceous gout

Question 16

Sensory receptors that inhibit contraction when a muscle exhibits too much force

Answer 16

Golgi tendon organ. Negative feedback system that regulates and maintains muscle tension. Sensitive to increases in muscle tension but insensitive to passive stretch.

Question 17

Muscle spindles

Answer 17

Arranged in parallel with fibers, sensitive to changes in muscle length. Mediate stretch (DTR) reflexes

Question 18

Upregulation in RANK receptor leads to

Answer 18

increased osteoclast bone resorption

Question 19

Major toxin of C. perfringes

Answer 19

Lecithinase, aka phospholipase C or alpha toxin: catalyzes splitting of phospholipid molecules, leading to membrane destruction, cell death, necrosis, hemolysis

Question 20

Damage to radial nerve

Answer 20

Wrist drop, decreased grip strength, loss of sensation over posterior arm/dorsal hand

Comes from midshaft fracture of humerus or compression of axilla (Saturday night palsy)

Question 21

3 major organisms for necrotizing fasciitis

Answer 21

Strep pyogenes, Staph aureus, Clostridium perfringes

Question 22

Resting potential of cell depends on conductance of:

Answer 22

high potassium and some sodium conductance

Question 23

Where does the majority of collagen synthesis take place?

Answer 23

RER

Question 24

Elderly woman, tea and toast diet, bleeding gums

Answer 24

Scurvy, vitamin C deficiency impairs collagen hydroxylation

Question 25

TNF-alpha inhibitors - side effects

Answer 25

Etanercept, infliximab, adalimumab - predispose to infection, including reactivation of latent TB

Question 26

Presentation of Lambert-Eaton syndrome

Answer 26

Proximal muscle weakness, autonomic symptoms like dry mouth, eye stuff, impotence. Often as a paraneoplastic syndrome from small cell lung cancer

Question 27

Most commonly injured nerve in the leg, effects

Answer 27

Common peroneal nerve. Very superficial when it goes around the neck of the fibula. Injury causes loss of sensation over dorsum of foot, and weakness of dorsiflexion and eversion

Question 28

Succinylcholine

Answer 28

depolarizing NMJ blocker administered for rapid sequence induction and intubation. Rapid onset. Paralytic action can be reversed by anticholinesterases (stigmines).

Question 29

What is most responsible for peak bone mass?

Answer 29

Genetic factors

Question 30

What test should you do before starting etanecept therapy?

Answer 30

PPD - TNF-alpha inhibitors might cause TB reactivation

Question 31

Sustained involuntary muscle contractions which force certain parts of the body into abnormal, painful movements

Answer 31

Dystonia

Question 32

Sudden, brief, sometimes shock-like muscle contraction

Answer 32

Myoclonus

Question 33

Treatment for a pt with hypertension, CHF, and osteoporosis

Answer 33

hctz

Question 34

Fibromyalgia

Answer 34

Chronic disorder, widespread musculoskeletal pain associated with stiffness, paresthesias, poor sleep, fatigue. Often worse with exercise. Multiple symmetrically distributed tender spots over muscles, joints, tendons (spine of scapula, lateral epicondyle, medial fat pad of knee). Women more than men.

Tx: exercise, antidepressants, anticonvulsants

Question 35

Child with moderate growth retardation and prominent brown stains on teeth - what did his mom use in pregnancy?

Answer 35

Tetracycline

Question 36

Musculocutaneous nerve, injury

Answer 36

C5-7. Innervates major upper arm flexors, and sensory innervation to skin of lateral forearm.

Injury causes loss of forearm flexion, loss of sensation over lateral forearm

Question 37

Gluteus medius gate:

Answer 37

hips dip downwards when ipsilateral foot is lifted off ground.

Question 38

Safe place for intramuscular injections in gluteal region

Answer 38

Superiolateral region. Superiomedial risk hitting sciatic nerve and gluteal nerves

Question 39

How are osteocytes connected?

Answer 39

Via gap junctions

Question 40

Contracture

Answer 40

Deformity in wound and surrounding tissue. Comes from excessive matrix metalloproteinase activity and myofibroblast accumulation in wound margins during wound healing

Question 41

Erythema infectiosum

Answer 41

Aka fifth disease, caused by parvovirus B19. Bright red rash on cheeks, lacelike rash on trunk and extremities

Question 42

Subdural hematoma and bilateral retinal hemorrhages in infant is suggestive of

Answer 42

Shaken baby syndrome, child abuse