MS UWorld 1 Flashcards
Embryonic conditions associated with maternal diabetes
Caudal regression syndrome, congenital heart defects, neural tube defects
Infant born with flaccid lower extremities, absent ankle reflexes bilaterally. X-ray: poorly developed lumbar spine and sacrum. What is this and what maternal condition may be related?
Caudal regression syndrome: agenesis of sacrum and sometimes lumbar spine. Flaccid paralysis of legs, dorsiflexed contractures of feet, urinary incontinence. May cause anal atresia to sirenomelia (mermaid syndrome). Related to poorly controlled maternal diabetes
Mutations in Fas receptor/ligand can cause
Autoimmune diseases. Mutations can prevent apoptosis of autoreactive T-cells, leading to autoimmune disease.
Colchicine
Binds and stabilizes tubulin to inhibit microtubular polymerization, which disrupts membrane-dependent functions (chemotaxis, phagocytosis, degranulation). Aso reduces formation of Leukotriene B4
Used for acute gout and prophylaxis.
Side effects are nausea, diarrhea, abdominal pain
Treatment for acute gouty arthritis
NSAIDS
Glucocorticoids
Colchicine
Treatment for Lyme disease
doxycycline or penicillin-type antibiotics (ceftriaxone)
45 y/o woman with fatigue, swelling, pain, morning stiffness in multiple joints for > 6 months. Diagnosis, treatment for rapid relief, and long term.
Rheumatoid arthritis. Treat acutely with NSAIDS, corticosteroids (glucocorticoids, ie prednisone). Steroids work better, but only used short term because of side effects
Long term treatment with methotrexate, but it takes weeks to kick in
General rule: if calcium is ___, phosphorus is ___
high/low and low/high. Opposite!
What is PRPP synthetase involved in? What might an activating mutation cause?
Purine synthesis, defect can cause hyperuricemia, which can cause gout
Negatively birefringent crystals
yellow under parallel light, blue under perpenducular. Monosodium urate –> gout
What cells are primarily responsible for intense inflammatory response in gout? What drug tempers this particular effect?
Neutrophils, which phagocytose the monosodium urate crystals –> neutrophil chemotaxis and release of inflammatory cytokines
Note: this is blocked by colchicine
IP3 second messenger system
GDP –> GTP, Phospholipase C, DAG and IP3, DAG –> protein kinase C, IP3 –> Ca –> PKC, PKC phosphorylates things for effects
Type I collagen synthesis
Signal sequence directs growing polypeptide chain to ER, where signal sequence is cleaved and hydroxylation (vitamin C dependent) of lysines and prolines occurs. Selective lysines are glycosylated, pro-a chains are arranged into procollagen triple helix, which is secreted out in ECM. Terminal di-sulfide propeptides cleaved, and collagen fibrils spontaneously assemble. Finally, covalently cross-linked by lysyl oxidase.
Ehlers-Danlos syndrome
Mutations causing faulty collagen synthesis. Hypermobile joints, hyperextensible skin, tendency to bleed.
Goodpasture syndrome and myasthenia gravis are type ___ hypersensitivity disorders
Type II HSR - IgM an/or IgG antibodies bind to cell surface antigens and/or ECM components
Muscle weakness worst in hips and shoulders, difficulty rising from chairs and combing hair. MHC I overexpression on sarcolemma, CD8+ lymphocyte infiltration. Dx and lab findings
Polymyositis
elevated CK, ANA+, anti-Jo-1, anti-SRP, Anti-Mi2
Older patient with bone pain and increased alk phos, mosaic pattern of lamellar bone with haphazard prominent cement lines. Dx and cell type involved
Paget disease (osteitis deformans). Initial lytic stage is osteoclasts, followed by mixed clast and blast stage, then just blasts.
Classic triad of reactive arthritis. Symmetric? Upper/lower extremities? What does it follow? What HLA?
Conjunctivitis, urethritis, arthritis. Most common asymmetric inflammatory arthritis of lower extremities in young men. Post GI or non-gonococcal urethritis, HLA B27
Conjunctivitis, urethritis, arthritis, sacroiliitis in a young man
Reactive arthritis
Which ligament is damaged by forceful anterior motion of tibia with respect to femur? Posterior motion?
ACL, PCL
Pt with MG is given a cholinesterase inhibitor but is getting side effects. What effects, and what can treat them?
GI, abdominal cramping, nausea, sweating, diarrhea. Can be controlled with cholinergic antagonist (scopolamine)
Function of t-tubules
to transmit depolarization from sarcolemma to SR in a rapid and uniform manner. Necessary for coordination for muscle contraction
Young black woman with dyspnea, cough, x-ray with bilateral hilar adenopathy and multiple parenchymal infiltrates. Non-caseating granulomas, high calcium. dx, what causes high calcium?
Sarcoidosis
High Ca from extra-renal 1,25-dihydroxy VD. Activated T-lymphocytes secrete interferon gamma which increases 1-alpha hydroxylase activity in macrophages.
How is MRSA resistant to penicillins?
alteration in penicillin binding protein
Methotrexate: use, mechanism, toxicity
Use: first line for rheumatoid arthritis
Mechanism: inhibits dihydrofolate reductase to block folinic acid synthesis
Toxicity: painful mouth ulcers, hepatotoxicity, myelosuppression, opportunistic infxn, B-cell lymphoma, pulmonary fibrosis
Hot tub folliculitis
superficial pseudomonas infection of hair follicles, minor outbreaks from water in pools or spas.
Pseudomonas is gram- oxidase+, non lactose fermenting, motile rods that produce pigment
What does Staph protein A do?
Binds Fc portion of IgG, preventing complement activation
Shoulder ulcer with central black eschar surrounded by edema, large gram positive rods. Suspect?
Bacillus anthracis, cutaneous anthrax. Most likely through occupational exposure to animals or animal products
Fracture of midshaft of humerus: risk of damage to what nerve and what artery?
Radial nerve, deep brachial artery
Skeletal muscle contraction: ATP causes
myosin head detachment from actin filament
Gas gangrene caused by
Clostridium perfringes, gram + rod, found in soil. Phospholipase toxin attacks cell membranes and causes cell death. Gas is from metabolizing carbohydrates.
This organism can also cause late-onset food poisoning and transient watery diarrhea.
Neuromuscular lesions, ragged red skeletal muscle fibers, lactic acidosis
Mitochondrial encephalomyopathy
Heteroplasmy
condition of having different organellar genomes (ie mutant and wild type) in the same cell. seen in mitochondrial diseases
Trendelenburg sign
Observe pt standing facing away from examiner wile lifting each foot off ground. Positive if hip dips toward unaffected side when pt stands on affected leg. Can co-occur with gluteus medius limp.
Indicates weakness of gluteus medius and minimus, superior gluteal nerve (these muscles pull pelvis down, abduct thigh)
Injury to inferior gluteal nerve
innervates gluteus maximus muscle. injury causes difficulty rising from seated position and climbing stairs
Bacterioid species
gram negative anaerobes that make beta lactamase. Tx with pip-taz
Floppy baby with jaundice, enlarged tongue, hypotonia, umbilical hernia
Congenital hypothyroid
CREST syndrome: name the things and the antibody
Anti centromere antibody
Calcinosis, Raynaud’s, esophageal dysmotility, sclerodactyly, telangiectasias
Pt with short stature, normal trunk and head size but very short limbs. Defect, prognosis
Achondroplasia: constitutive activation of fibroblast growth factor receptor 3 inhibits chondrocyte proliferation. Failure of longitudinal bone growth due to this impaired cartilage proliferation
Normal fertility and life span
Parvovirus presentation in adults
arthritis involving PIP, MCP, knee, and ankle joints. Symmetric, usually resolves spontaneously. Mimics RA
Etanercept
TNF-a inhibitor, added to methotrexate for RA when needed. Fusion protein that links TNF-a receptor to Fc portion of IgG –> decoy receptor.
Biological agent suffixes
- mab
- cept
- nib
- mab is monoclonal ab
- cept is a receptor molecule
- nib is a kinase inhibitor
First line tx for gouty arthritis
NSAIDs
Lab values in osteoporosis (PTH, calcium)
Normal
Valsalva maneuver
increases vagal tone. most important muscle is rectus abdominis
Tx for paraxysmal supraventricular tachycardia
Vagal stimulation, such as carotid massage or valsalva
What are the changes in bone structure in rickets?
increase in unmineralized osteoid around trebeculae, and widened osteoid seams
What muscle is on the anterior and lateral surface of the vertebral body/transverse process? The posterior?
Ant: psoas muscle. Post: erector spinae.
What part of bone is affected by hematogenous osteomyelitis in kids? Adults
Kids: Metaphysis of long bones, due to slower blood flow and capillary fenestrae, happens mostly in young boys
Adults: vertebral body, also location of Pott disease
Young man with low back pain and morning stiffness suggests
ankylosing spondylitis
