September 8 Bone Patho Flashcards
What do nerve conduction studies test?
Motor, sensory, mixed nerves
What does electromyography test?
Skeletal muscle fibers
What do we study in electromyography?
MUAPs–motor unit action potential of all depolarizing fibers
What is spasticity?
Velocity depenent increase in tonic stretch of a muscle
Hyperexcitability of the stretch reflex
One component of the upper motor neuron syndrome
How do we treat spasticity?
Botulinum neurotoxin
Targets SNAP 25 docking protein for vesicle to attach to; no AcH released
What are the only two things that differentiate osteoblasts from fibroblasts?
Runx2
Osteoclacin
What makes hydroxyapatite hard?
Osteocalcin
What induces and inhibits osteoblasts?
Inhibited by leptin
Induced by PTH/BMP
How do osteoclasts work?
- PTH activates
MCSF induces macrophages
RANKL induces differentation
OPG binds to RANK L receptor - Osteoclasts make acid from CO2
- Low pH dissolves calcium and potassium; activates cathepsin K (lysomal enzyme)
Paget’s disease
> 40 years old
High rate of remodeling due to mutant osteoclasts (too many nuclei); too much primary bone
How does bone lengthening work?
- estrogen/testosterone releases GH which makes IGF1
- IGF1 induces zone of proliferation [in growth plate] into hypertrophy (fractures)
- Zone of calcification=collagen X and hydroxyapatite laid down (basophillic)
- Zone of ossification=collagen I laid down (eosinophilic)
What are osteoclasts induced and inhibited by?
Inhibited by calcitonin, OPG
Induced by PTH, RANKL
Osteoporosis
Too much osteoclast activity, makes BMD go down
T score=# deviations below normal BMD
Osteopetrosis
Dense, heavy bone because osteoclasts lack ruffled border
How do we treat osteoporosis?
Anabolic pro osteoblast=PTH 1-34 (spikes promote osteoblast)
Anti resorptive (anti osteoclasts)=SERM like raloxifene (estrogen R mods); bisphosphonates; RANKL antibodies (Denosumab)
Working on=OPGs, anti alpha5beta3, RunxX2
