Patho: Bone/Rheumatology Flashcards Preview

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Flashcards in Patho: Bone/Rheumatology Deck (116):
1

Osteocalcin

Protein that is as a marker for cell turnover and osteoblast activity

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Osteopontin

Protein that acts as a marker for cell turnover

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Osteoprogenitor cells

Pluripotent mesenchymal stem cells that can differentiate to active osteoblasts or surface/inactive osteoblasts that release cytokines and hormones

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Runx2

Produces transcription factors supporting the maturation of osteoprogenitor cells to active osteoblasts... mutations can result in cleidocranial dysplasia

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LRP5/6

LDL receptor related proteins 5 & 6, receptors on osteoblasts that bind Wnt to allow production of beta catenin

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Wnt

Binds to LRP5/6 receptors on osteoblasts to stimulate production of beta catenin, which anchors osteoblasts to the lamellar bone

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Beta catenin

Produced by active osteoblasts after stimulation by Wnt binding to the LRP5/6 receptors, anchors osteoblasts to the lamellar bone to allow for remodeling to occur

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BMP

Bone morphogenic protein, stimulates bone remodeling, can be used in spinal fusions to encourage bone growth

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Infuse

Recombinant BMP approved for use in spinal fusions to encourage bone growth, also causes overgrowth of bone and is a/w 38% increase in benign tumors

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Osteoid

Bone matrix not yet mineralized, takes about 12 days for mineralization to be complete

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RANK ligand

Protein expressed by osteoblasts that bind to osteoclast precursors to activate NF-kappabeta to increase osteoclastogenesis

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RANK

TNF-related receptor expressed by osteoclast precursors, increases osteoclastogenesis when bound by RANK ligand

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OPG

Osteoprotegrin, protein produced by osteoblasts that blocks RANK-RANK ligand interaction to inhibit osteoclastogenesis

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Howship lacunae

Small depressions in bone where osteoclasts are found

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Osteoclastogenesis

Differentiation of osteoclast precursors to osteoclasts

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NF-kappabeta

Nuclear factor kappabeta, increases osteoclastogenesis when activated by RANK/RANK ligand interaction

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M-CSF

Macrophage colony stimulating factor, released by osteoblasts, binds to receptors on osteoclasts to induce differentiation and stimulate bone resorption

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Modeling

Bone resorption and formation occur on separate surfaces

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Remodeling

Replacement of old bone with new bone mass

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T-score

Bone mineral density standards based on 30 year old females

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Z-score

Bone mineral density standards that are age and gender matched

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Osteopenia

Bone mineral density between 1-2.5 standard deviations below the mean for young adult women (T-score -1 to -2.5)

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Osteoporosis

Bone mineral density more than 2.5 standard deviations below the mean for young adult women (T-score <-2.5)

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Cholecalciferol

Vit D3, synthesized in skin after UV light exposure, ingested with diet, longer half life than Vit D2

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Ergocalciferol

Vit D2, ingested with diet

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Raloxifene

Estrogen receptor modulator, decreases osteoclast activity by increasing production of osteoprotegrin

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Bisphosphonates

Osteoclast inhibitor, affects the proton pumps, most common treatment for osteoporosis

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Forteo

Recombinant PTH, stimulates osteoblasts to actively build bone, an injectable treatment for osteoporosis

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Denosumab

Antibody to RANK ligand, acts like OPG to prevent cell differentiation of osteoclasts

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Osteitis deformans

Paget's disease

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SQSTM1

Gene that codes for protein p62, mutations lead to enhanced RANK signaling and increased osteoclast activity

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p62

Protein that acts as a scaffolding protein in the RANK signaling pathway

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Osteoporosis circumscripta

Refers to a focal lytic lesion in the frontal and/or parietal bones, characteristic of Paget's disease

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Infraction

An incomplete fracture without displacement, can be found in Paget's disease

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Platybasia

Flattening of the base of the skull that can be a complication of Paget's disease, impinges foramen magnum, compresses medulla and spinal cord

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Pagetic steal

Refers to lightheadedness due to shunting of blood from brain to bone, a complication of Paget's disease

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1-alpha-hydroxylase

Enzyme involved in the activation of vitamin D

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CASR

Calcium sensing receptor gene, mutations lead to familial hyperparathyroidism

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Dissecting osteitis

First step of bone resorption in hyperparathyroidism, osteon hollowed out by osteoclasts

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Osteitis fibrosa

Second step of bone resorption in hyperparathyroidism, trabecular bone resorbed and marrow replaced with fibrosis

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Osteitis fibrosa cystica

Third step of bone resorption in hyperparathyroidism, "brown tumor" is filled with fluid containing RBCs, fibrosis with bleeding occurs

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Dysotoses

Congenital malformations of the bones

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Polydactyly

Formation of extra bones

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Syndactyly

Fusion of two adjacent digits

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HOXD13

Homeobox gene, mutations can cause an extra digit between 3rd and 4th fingers and syndactyly

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FGFR3

Inhibits cartilage growth when activated by FGF3, mutations lead to constitutive activation causing achondroplasia

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Achondroplasia

Caused by an autosomal dominant mutation in FGFR3, major cause of non-lethal dwarfism

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Thanatophoria

Caused by a mutation in FGFR3 that leads to new and abnormal function of the gene product, most common form of lethal dwarfism

49

Acid hydrolases

Enzymes that normally degrade dermatan sulfate, heparan sulfate, and keratan sulfate... can cause mucopolysaccharidosis when decreased

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Glycosaminoglycans

Accumulate in connective tissue, neurons, and hepatocytes when a patient with mucopolysaccharidosis has decreased acid hydrolases to degrade them

51

Elaprase

An enzyme given as treatment for mucopolysaccharidosis that can degrade some of the sulfates to halt the disease progression

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Carbonic anhydrase

An enzyme necessary for osteoclasts to generate protons to resorb bone... can cause the autosomal dominant form of osteopetrosis when deficient

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7-dehydrocholesterol

Synthesized in the skin when exposed to sunlight and is then converted to Vit D3 (cholecalciferol)

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25-hydroxyvitamin D

Formed when the liver conjugates cholecalciferol

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1,25-hydroxyvitamin D

Formed when the kidneys conjugate 25-hydroxyvitamin D

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Osteosclerosis

Increased bone density

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Pseudoarthrosis

A false joint that can form at the site of a fracture

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Cloaca

The hole formed in the bone during the formation of a draining sinus in a patient with osteomyelitis, can extend to the surface of the skin

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Sequestrum

Dead bone fragment embedded in pus in a patient with osteomyelitis

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Involucrum

New bone that forms a sheath around a necrotic sequestrum in a patient with osteomyelitis

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POTTS disease

TB of the bone

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SABRE shins

An anterior-bowing tibia due to tertiary syphilis

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Synovial joints

Freely moveable

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Synarthrosis

Joint with little or no movement

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Syndesmosis

Fibrous synarthrosis where the bones are connected by fibrous tissue without cartilage (ex: cranial sutures)

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Symphyses

Cartilaginous synarthrosis where the bones are joined by fibrocartilaginous tissue and firm ligaments (ex: vertebral bodies)

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Synchondrosis

Cartilaginous synarthrosis where bones are connected by articular cartilage without synovium (ex: 1st rib & sternum)

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Subintima

Outer layer of synovium cells

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Intima

Inner layer of synovium cells

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Type A synoviocytes

Macrophage-like with lysosomal enzymes

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Type B synoviocytes

Fibroblast-like, synthesize hyaluronic acid and proteins... expansion of these cells is a hallmark of RA

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Tidemark

Line that separates the radial from the calcified zone of hyaline cartilage... this is where cartilage cells regenerate and then migrate upward

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Osteophytes

Bony projections at the margins of articular surfaces covered with fibrocartilage and hyaline cartilage, formed during the progression of OA

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MMP

Matrix metalloproteinase, enzymes that break down interstitial collagen (types I, II, and III)

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ADAMTS-4

Enzyme that degrades aggrecan, which is a proteoglycan, contributing to the breakdown of cartilage in OA

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COL2A1

Gene for type II collagen that can be defective in people with primary OA

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Eburnation

Conversion of bone into hard ivory-like mass

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Joint mice

Pieces of cartilage and subchondral bone that become dislodged into the joint

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Heberden nodes

Osteophytes at distal interphalangeal joints

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HLA-DR4/1/10/14

Proteins that predispose people for RA

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Arginine

Present in great amounts in the DR epitope in people with seropositive RA, associated with a poor prognosis

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Lysine

Present in great amounts in the DR epitope in people with seronegative RA, associated with a good prognosis

83

PTPN22

Tyrosine phosphatase, activates inflammatory cells, a genetic factor associated with RA

84

CCP

Citrulline modified peptides, recognized by Abs that form against filaggrin (main epitope in CCP) in patients wtih RA

85

Filaggrin

Main epitope recognized by anti-CCP Abs in patients with RA... these Abs cross-react with keratin and perinuclear factor

86

RANA

RA-associated nuclear antigen, related to the nuclear antigen encoded by EBV... Abs form against RANA in patients with RA

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Pannus

Collection of various destructive cells accumulating on the joint surface in a patient with RA

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Ankylosis

Fibrous fusion of a joint

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Enthesitis

Inflammation of a point of attachment of skeletal muscle to bone, B27 positive, form of JIA

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Marie-Strumpell disease

Ankylosing spondylitis

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Reiter syndrome

Reactive arthritis, associated with IBD... triad of seronegative polyarthritis, uveitis/conjunctivitis, & nonspecific urethritis or cervicitis

92

HLA-B27

Class I MHC associated with the spondyloarthropathies

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Monosodium urate

Crystals that deposit in joints of a patient with gout

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Tophi

Large aggregates of monosodium urate crystals that deposit in joints of a patient with gout

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Urate transporter 1

Gene responsible for renal filtration and excretion of uric acid... mutations can cause hyperuricemia and decreased uric acid excretion

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HGPRT

Hypoxanthine transferase, a gene involved in the salvage pathway of purine synthesis... mutated in a genetic form of gout, causes increased uric acid production

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Allopurinol

Medication that inhibits the action of xanthine oxidase to decrease the production of uric acid

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Probenecid

Medication that increases uric acid excretion

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Apo-E

Coats the monosodium urate crystals to inhibit responding cells from initiating an immune reaction in a patient with gout

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Lesch-Nyhan syndrome

Complete HGPRT deficiency resulting in an overproduction of uric acid with increased urinary excretion

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Trophus

Extracellular soft tissue deposits of urate crystals surrounded by foreign body giant cells (macrophages)

102

Rat bite

X-ray finding describing punched out juxta-articular lytic lesions found in patients with gout

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Podagra

Painful reddened big toe, common finding in someone experiencing acute gouty arthritis

104

Nidus

The uric acid center that first starts the formation of a kidney stone

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Calcium pyrophosphate

Crystals that deposit in joints or in surrounding soft tissue in patients with pseudo-gout

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Ochronosis

Blue/black discoloration of certain tissues due to the accumulation of homogentisic acid, which can lead to secondary pseudo-gout

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MDM2

Gene that regulates p53, amplified in some patients with osteoblastoma

108

TP53

Gene that produces p53, deleted in some patients with osteoblastoma

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Li-Fraumeni

Syndrome with germline p53 mutation, greatly elevates the incidence of osteosarcoma

110

INK4a

Gene that codes for p16 (cell cycle regulator) and p14 (aids p53 function), mutations can increase likelihood of developing osteosarcoma

111

Codman triangle

Triangular shadow on X-ray between bony cortex and raised ends of periosteum

112

EXT1/2

Genes that can be a hereditary cause of osteochondroma when mutated... may gain function or be inactivated by mutations

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Ollier disease

The presence of multiple enchondromas

114

Maffucci syndrome

The presence of hemangiomas in a patient with a chondroma... these patients are at risk of developing other types of malignancies

115

CDKN2A

Tumor suppressor gene on chromosome 9 that can lead to the development of a central chondrosarcoma when mutated

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PTHrP & Bcl-2

Genes that can lead to the development of a secondary peripheral chondrosarcoma when upregulated