- most abundant noncollagenous protein in bone - secreted by OSTEOBLASTS - promotes mineralization and bone formation - inhibited by PTH and stimulated by VitD

OITE - Basic Science Flashcards by M Almasri

Calcitonin’s role in bone metabolism?

-Inhibits osteoclastic bone resorption, by binding CTR (receptor)
-decreases osteoclast resorption at the ruffled border
“calcitOnin Opposes bOne resOrption”

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Which Ig subtype does rheumatoid factor target?

Rheumatoid factor (IgM) attaches to IgG forming imm complex
IgM is only one that is a pentamer
IG is only Ab which can cross placenta giving passive immunity to fetus

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Psoriatic arthritis, what is it?

Seronegative spondyloarthropathy in 5-20% with psoriasis
Distal phalax acrolysis
Dactylitis “sausage digits”
Pencil in cup xray of phalanges

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Herniated disks are associated with spontaneous increase in production of:

OPG (osteoprotegerin)
IL-1 beta
RANKL
PTH

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COX action?

-catalyze formation of PG and thromboxane from arachidonic acid

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COX-1 action?

-generates PG responsible for maintenance/protection of GIT

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COX-2 action?

-generates PG responsible for inflammation and pain

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Function of hemeobox gene product?

regulates somatization of the axial skeleton

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What is the function of Cathepsin K, produced by osteoclasts?

released by osteoclasts at the ruffled border to function to RESORB bone
Cathepsin K inhibits (role for osteoporosis?)

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GILT enzymes?

Reduce di-sulfide bonds

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3 features of bone grafting to know?

Compression strength
Resorption rates
Drainage (calcium sulfate)

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Which bone graft substitute have the fastest resorption characteristics?

Calcium sulfate

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Is COX-2 expressed under normal condiitons?

No, only found during general states of inflammation

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What zone do physeal fx typically occur?

Zone of provisional calcification in HYPERTROPHIC zone

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Peak bone mass in men and woman is most dependent on which sex steroid?

Estrogen - prevents bone loss by inhibiting bone resorption

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Osteocalcin?

most abundant noncollagenous protein in bone
secreted by OSTEOBLASTS
promotes mineralization and bone formation
inhibited by PTH and stimulated by VitD

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Organic components of bone?

Collagen
Proteoglycans
Matrix protein (osteocalcin, osteonectin, osteopontin)

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What is renal osteodystrophy?

Pathologic bone condition in pts with underlying kidney disease
increased PTH secretion

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Renal osteodystrophy, what is the key pathophysiological step leading to osteomalacia?

-Uremia related phosphate retention
-inadequate phosphorus secretion
-insoluble calcium phosphate removes calcium from circulation
hypocalcemia occurs

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What is hypopohsphatasia and what lab values does it lead to?

AR disorder due to inborn error in production of alk phosphatase
Low serum alkaline phosphatase levels
ALP is a marker of bone formation

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What is Rickets?

Defect in mineralization of osteoid matrix caused by inadequate calcium and phosphate

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Which serum marker is most closely associated with colorectal carcinoma?

CEA - colorectal
CA 19-9 pancreatic
CA 125 ovarian
CA 15-3 breast AFP - hepatocellular carcnioma

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Muscle injury, what is the first listed cells to appear following acute injury?

-Neutrophils

Then macrophages

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SOX-9 is a key transcription factor in the differentiation of what cell lineage?

Cartilage differentiation from chondrocytes

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Vitamin B12 deficiency causes what?

-peripheral sensory neuropathy Signs -Decreased DTR, babinski, fatigue/depression

How do you increase strength and stability of an exfix construct?

2 cortices better than 1 separating the pins is better pins closer to fx shorter pins better bigger pins better

Adductor myodesis benefit in AKA?

- improves outcomes by creating dynamic balance force facilitating ambulation - provides soft tissue cushion beneath osseous amputation and - enhances prosthetic fitting

Myoelectric prosthesis candidate? its features?

- best candidate is transradial amputation - good cosmesis - heavier, but good for overhead activities, sedentary - less sensory feedback

Galvanic corrosion?

wear in dissimilar metals in proximity with difference between their electric potentials, results in a flow of current between them

4 types of corrosion?

- crevice corrosion - fretting corrosion - pitting corrosion - galvanic corrosion

Chromium, molybdenum and cobalt are basic components of which implant material?

Cobalt alloy

Which metal is closest to bone in Youngs modulus?

Titantium

Stainless steel?

- Iron with chromium in it | - resistant to corrosion

Lead toxicity affects growth by inhibiting what?

PTHrP (parathyroid hormone related peptide) | and TGH-beta1

3 P for Plumbism?

``` Painful belly (colic constipation) Polka-dotted RBC Peripheral palsies: RADIAL NERVE ```

3 b''s for Plumbism?

Blue (burton's) gum lines Basophilic Blue stippling Bright BONY BANDS metaphysis (in growing bones)

Which medication replaces normal coagulation factors with Decarboxylated factors?

- Warfarin prevents Vit K gamma carboxylation | - II, VII, XI, X, Protein C and S

Etiology of FES (fat embolism syndrome) in TKA ?

intramedullary instrumentation

CXR of FES

like ARDS, "Snow Storm Lung"

What are the Biphasic Clinical stages of FES?

- Immediate, fat emboli i 90% of long bone fx, block vessels | - Delayed 24-72 hrs (Facids stimulate complement to ARDS)

What part of the articular cartilage has the highest concentration of proteoglycans and lowest conc of Water?

Deep layer

What type of collagen starts at Tidemark in cartilage?

Cartilage Type 10

What kind of collagen is found predominantly in cartilage?

``` Type 2 (90-95%) Type X is only in calcified cartilage zone ```

What is the result of a Type 1 collagen defect?

bONE collagen | -Type 1 defect leads to OI

Ehlers-Danlos syndrome defect?

Type 1 and Type 3 collagen defect

Gout "YUPAN"

Yellow Urate Parallel ( to compensator) Negative birefringence Needle Shaped

What about CPPD?

Positive birerefringence | Blue crystals

Which genetic polymorphisms are associated with osteoporosis?

Calcitonin Estrogen receptor-1 Vit D receptor Type 1 collagen alpha-1 chain

MED spinal involvement?

Pseudoachondroplasia, spine involvement? Genetic mutation?

Yes | COMP

Daily calcium and Vit D recommendation for women?

age >50 --1200 mg calcium, 800-1000 IU Vitamin D | age

Longterm bisphosphates associated with what kind of fx?

- Atypical Subtroch femoral stress fx | - Jaw osteonecrosis

What is the primary mode of bisphosphonate excretion?

-Renal excretion | is contra-indicated in pts with severe renal disease

What mode of inheritance are structural protein deficits in ortho?

``` Autosomal dominant (collagen, fibrillin, FGF) ```

If it is enzymatic defect, what is the typical mode of inheritance?

``` autosomal recessive (cerebrosidase, carbonic anhydrASE, etc). ```

What is genetic anticipation?

=disease develops earlier in life in each successive generation

What is genetic imprinting?

A single working copy of a gene is inherited | nonworking or silenced gene is usually methylated

What species of bacteria is known to produce MecA?

- MRSA is most common carrier - MecA forms penicillin binding protein 2A - alters efficacy of beta-lactam antibiotics

Clinical trials pyramid?

Level 1 - RCT Level 2 - Prospective cohort Level 3 - Retrospective cohort, or Case control study Level 4 - Case series Level 5 - Case report

HOw is radiation exposure increased?

- Larger body part is imaged - Extremity is positioned closed to X-ray source - Large C-arm > mini C arm

What factors can one use to decrease radiation exposure?

- Minimizing exposure time -protective shielding - Maximizing distance - Colliminator - Inverted position relative to patient

What term in stats defines accepting the null hypothesis, when it is in fact not true?

Type 1 error - null hypothesis is REJECTED even though it is correct Type II error - nuLL hypothesis is aCCepted, even though it is in fact not correct

What are type 2 errors due to ?

Inappropriate study power | AKA false negative rate

Study power formula?

Power = 1 - beta (type2 error) - is an estimate of probability of finding an association in a research study when on actually exists - 80% is appropriate power

What injury independently predicts poor outcome in polytrauma pts?

Foot injury | -SF 36, WOMAC, and other validated outcome measure tools

Joint reaction force increases or decreases, as the acetabular component is moved medial in THA?

Joint rxn force decreaes, due to decreasing abductor tension

in a single-sided leg stance, what is the body and leg weight relative to total body weight?

5/6th of total body weight

What cell expresses RANKL?

- Expressed on osteoblasts | - RANK receptor is on osteoclast precursor cell (causing bone resorption)