Week 3 UWORLD Qs Flashcards
Describe the difference between CRC associated with Lynch syndrome vs FAP?
Lynch - inherited defect DNA mismatch repair genes (MSH, MLH, PMS)
Be on the lookout for relatives for GYN + CR cancers (adenocarcinoma CRC)
FAP - APC gene mutation so likely to develop tumors by adenoma-carcinoma sequence, will present with MANY polyps
APC mutation is also most common mutation in sporadic colon cancers
What kind of tumor are you thinking + what are the risk factors:
Weight loss, anorexia - 3 mos
Jaundice, dark urine, pale stools
Enlarged GB, non-tender
You were thinking porcelain GB but NO - is pancreatic cancer @ head causing back up of bile into the GB distending it
It’s not a horrible idea b/c porcelain are not painful, but no h/o recurrent GB infections here like you’d need (chronic cholecystits)
RF pancreatic cancer:
1. Age - old people
2. Smoking!!!!
3. Chronic pancreatitis (think 20 yrs) associated with h/o alcoholism
4. Diabetes
5. Genetics: MEN1 (ant pit, paraT, pancreas)
Name the 2 main causes of acute pancreatitis and other clues that would tip you off to this dx
- Gall stones - see stones on scans, jaundice
- Alcohol - 2 AST > ALT, macrocytic RBC (even if not anemic)
Possible EFFECTS of acute pancreatitis - HypoCa if Ca deposits on necrotic tissue that was self digested
- HyperG if islets got destroyed
- HyperNa due to acute pancreatitis induced hypovol
What is the difference between biliary atresia and Gilbert syndrome?
Biliary atresia = normal bile duct at birth that gets obliterated, baby w/ jaundice, dark urine, pale stool
*Hepatomegaly that would show liver fibrosis and intrahepatic duct profile if biopsied, urgent treat to prevent progression to cirrhosis
Gilbert syndrome = less UDP glucuronosyltransferase than normal to conjugated BR but generally no symptoms - see small increase BR in blood w/ stress
Don’t confuse with Crippler Najjar which has NO UDP enzyme so babies present with jaundice too - but this is fatal b/c will deposit in brain (ketonicturus)
2 enzymes reflect biliary injury
Alk phos
GGT = gamma glytamyl transpeptidase
What 3 measures determine cirrhosis prognosis
Albumin
BR (but not all phos or GGT)
PT
3 major complications of UC
- Toxic megacolon - XR is best for colonic dilation (NO barium enema or colonoscopy b/c higher risk to perf thin wall of dilated bowel)
- Fulminant colitis
- Perforation
Do contrast CT for obstructions
Do US for kidney stones and free fluid aka blood w/ trauma (FAST exam)
If a patient presents with pain w/ swallowing but no dysphagia, what esophageal path are you thinking?
ULCER
Vs dysphagia think stricture (+obstruction) or Barrett’s metaplasia w/ chronic GERD (weight loss b/c cancer)
What are the 2 watershed areas of the colon/
Splenic flexure - between SMA + IMA supplied by marginal artery
Recto-sigmoid jxn - between sigmoid artery (SMA) and superior rectal artery (int iliac)
Describe histo for the esophagus with:
Changes due GERD
Adenocarcinoma (Barrett’s)
SCC
GERD - longer papillae, basal cell hypertrophy, intraepi eosinophils
Barretts - look for GOBLET cells (intestinal metaplasia)
SCC - keratin pearls + no intercell bridges
Who gets Cdiff?
People on ANTIBIOTICS - esp those in hospital b/c more likely to exposed
This is because normal GI flora prevents infection
Why you don’t see any IC canes in sketch
Which disease has the IgA vs tissue transglutaminase, endomysial, and deamidated gladden peptide? Where do you see it specifically, what are other symptoms?
Celiac - HLA DQ 2, 8
Screen w/ IgA test or d-xylose test - are things gets absorbed in the prox SI
Confirm with duodenum (some jejunum) biopsy
Dermatitis herpetiformis - IgA vs tips of dermal papillae, looks ulcerative on skin
Name the symptoms and possible causes of vit A def
Need vit A for vision + cell differentiation
Symptoms: night blind, dry skin (SE of using retinoid face creams)
Causes
1. Pancreatic insuff - A is fat sol it
2. Intestinal mal absorb
3. Biliary disorder = PRIMARY BILIARY CIRRHOSIS
AI destroy intra-hepatic bile ducts (+ANA)
- Vit A def b/c no bile to emulsify fat for absorption
- PRURITIS b/c build up BR
- Xanthomas
- High alk phos (bile problem) + cholesterol in blood
What is the presentation and patho of familial hypercholesterolemia
AD mutate LDL R
Most effects b/c liver can’t use this R well to remove LDL + IDL
See atherosclerosis at v/ young age
You know RAS as a TF. Explain how RAS exists in cells, gets activated, and works
RAS = protein Exists in cytoplasm Inactive: RAS + GDP Active: RAS + GTP Something binds cell TK -> activates RAS -> activates MAPK mitogen activated protein kinase = what goes into nucleus to change gene transcription
What is Wilson’s disease
Can’t excrete Cu into bile (excretion)/blood (transport)
AR (chr 13) mutate Cu transporting ATPase -> accumulates in TISSUES and damges via free rad prod
Lover
Brain - neuro + psych disease
Eyes - Kayser Fleisher rings
Renal - Fanconi syndrome (increase U Cu)
Describe the presentation and treatment of arsenic poisoning
Mechanism: X cell resp (X pyruvate deH)
Sources: insecticide, well water, pressure treated wood
Acute symp: garlic breath, QT prolong, watery diarrhea, vomit
Chronic symp: hypo/hyperpigment, stocking/glove neuropathy
+ DIMERCAPROL - pee out metals
Or DMSA
Describe what you use each anti-dote for CaNa2 EDTA Deferoxamine Hydroxycobalamin Methylene blue
- Acute lead poisoning - urine excretion - constipation, anemia, irritability, confusion
- Fe OD due to multiple transfusions - urine excretion
- Cyanide poisoning - cherry red skin - urine excretion
- Anti-freeze (methemoglobinemia) - use as artificial e- transporter to reduce methemoglobin in NADPH pathway - gray/blue skin, SOB, chocolate colored blood
Describe Dubin Johnson syndrome
You can conj BR - but you can’t get it out of hepatocytes
Asymptomatic - decreased excretion BR glucuronides
+ Stress see increase direct = conj BR
BLACK LIVER incidental finding
What does the D-xylose test tell you?
SI absorptive fxn index of pancreatic fun
Since this molecule should be absorbed directly
Explain mechanism of HMG CoA reductase
X cholesterol synthesis = decrease levels cholesterol @ liver
Upreg LDL R -> take more LDL/IDL out of circulation to get the cholesterol you need to do things in the liver
Explain mechanism of cholestyramine
= bile acid binder aka don’t let them be reabsorbed so now have to use more cholesterol to make new ones
Therefore you much increase hepatic cholesterol synthesis
Describe symptoms, people at risk, and effects of riboflavin def
= Vit B2 = FAD
Alcoholics, malnourished
Needed for ETC (complex 2 in ETC = succinate dehydrogenase [also TCA enzyme])
Cheilosis = inflam lips, scaling at corners mouth
Corneal vasculaization
Describe presentation of peau d’orange
Red, itchy breast
Can see axilla lymphadenopathy
Cancerous cell obstruct lymphatics
Describe the process of making and the significance of Barr bodies
“Condensed body of heaving methylated DNA”
Embryo: X inactivation = lyonization
Each cell suppress either mom or dad X - mosaic pattern of which one is suppressed means X recessive carriers don’t have symptoms
Barr body = heterochromatin @ periphery of nucleus
1. Hyper meth DNA
2. DE acetylated histones
Aka low (not no) transcriptional activity
Describe mechanism + use of proteasome Is
Bortezomib
Proteosome = protein breakdown/recycle
Mechanism = boronic acid dipeptide @ proteasome catalytic site => cause cell apoptosis
Use for multiple myeloma b/c plasma cells v sensitive due to constant protein production (Ig)
Recognize MM: low back pain (bone pain), hyperCa, anemia, high creatinine (kidney disease)
How does HIV become resistant to the normal HAART regimen?
Mutations to POL
Change proteases - protease I resistance
Change RT - N and nonNRT Is
Vs env mutations allow escape neutralizing Abs
Vs high intrinsic mutation rate - cell mediate immune responses don’t work vs HIV
Describe when you use fibrinolytics for MI and the CIs to doing so
Fibrin specific fibrinolytics only cleave recently formed clot w/o systemic activation (tPA, reteplase) Vs non-fibrin specific streptokinase Use WITHIN 6 HRS STEMI CI 1. Hemm stroke 2. Ischemic stroke within 1 yr 2. BP > 180/110 Dissecting aneurysm + active internal bleeding
Name the LNs these structures drain to
- Bladder dome
- Lateral lobe prostate
- Orifice anal canal
- Upper pole testes
- Upper 1/3 rectum
- Superior bladder -> external iliac (vs inferior portion pladder -> internal iliac)
- Prostate -> internal iliac (mainly) also ext iliac and sacral
- Anal canal BELOW dentate line -> inf rectal nodes -> superficial inguinal nodes
*Sup inguinal LNs drain all CUTANEOUS lymph from the belly button down including scrotum
Exception: testes, glans penis (deep inguinal), skin of post CALF - Testes -> para aortic LNs
- Above dentate line -> inf mesenteric LNs
Why do we keep increasing ionizing radiation doses with each treatment?
B/c initial dose = plateau
Higher dose + more treatments -> more dsDNA breaks + ROS -> cancer cell survival drops dramatically
As does normal actively replication cells
Vs UV radiation = mades prymidine dimers
Describe RNA interference
Changes mRNA TRANSLATION
+non-coding RNA (siRNA or miRNA) to cause post-transcription gene silencing
miRNA -> nucleus to make ds precursor -> out to cytoplasm -> cleave into RNA helix via dicer -> individual strands separated + incorporated into RNA induced silencing complex
Uses miRNA to bind complementary seq on target mRNA
What is HgF’s relationship to 2,3 BPG?
Binds BPG with lower affinity that normal B globin
Good in a fetus b/c binds O2 more tightly than mom’s Hg so can take the O2 @ placental transfer
Hg S - reduced O2 affinity
Hg H (alpha thal -> Beta tetramers) - higher O2 affinity
Hg C - no change
Hg A1c - reduced 2,3 BPG affinity but due to methylation (not replacing AA in the binding site like Hg F)
Where is heme made in cells
Mitochondria + cytoplasm
@ Bone marrow + liver via RBC precursors
How do Gardos channel blockers help sickle cell patients
Sickle cell treatment
- Hydroxyurea increase HgF
- Gardos channel blockers X K + H2O efflux -> prevent dehydration so less change sickle (polymerize Hb S)
Mechanism and rescue treatment for MTX
MTX - DHF reductase - no THF for purine synthesis in rapidly dividing cells
Rescue w/ leucovorin (foilinic acid) = reduced folic acid that does NOT require DHF-R
Often adding together to rescue cells normally hit by MTX toxicity
Remember, leucovorin potentiates 5-FU (X thymidylate synthase) - making more portent treatment for CRC
What accumulates in cells due to MTX use
X DHF reductase so precursors build up in cells: folic acid + DHF polyglutamate (aka recycled)
MTX is brought into cells and polyglutamated to keep it in cells - same with folate and recycled DHF
Think about this in the context of using MTX for ectopic preg
Name + describe mechanism of integrase Is for HIV
Raltegravir
X HIV dsDNA from integrating into host chromosomes
Vs protease Is = ritonavir, saquinavir = X cleavage of polyprotein precursor into fxnal proteins
Vs fusion Is = enfuvirtide = bind gp41
Vs RT Is = efavirenz, tenofavir, lamivudine
Vs CCR5 antag = maraviroc
Describe 5 steps of T cell maturation
Double neg (no CD4/8) = pro-T cells arrive @ thymus
TCR rearragement
1. Rearrange b chain = both CD4 + CD8 expressed = double positive T cells (immature T cells)
2. Rearrange a chain
3. Positive selection @ cortex - do you work vs antigen
4. Negative selection @ medulla - do you recognize self
5. Lose either 4 or 8
Mechanism etoposide
Major uses: testicular cancer + small cell lung cancer
X topo 2 -> can’t seal the ds DNA breaks it induces -> breaks accum -> cell death
Topo 2 induces dsDNA breaks to relieve both positive and negative supercoiling
Same idea = podophyllin - use for genital warts
Vs topo 1 - ss nicks to relieve negative supercoil (drugs here are irinotecan and topotecan)
What is released during placental abruption that cause cause maternal DIC
Tissue factor = thromboplastin
- Hypertension may have cause the abruption
Also DIC w acute fatty liver of pregnancy but presents w/ N/V, ab pain, elevated liver enzymes
Can also get DIC from amniotic fluid emoblism but this is seen with hypotension and cardiogenic shock
Difference between unfract and LMW heparin
Unfract - can bind antithrombin 3 + F10a or AT3 + thrombin
LMW - binds only AT3 + 10a
Yeah sure cancer can met to the adrenals, but how would this present
Asymptomatic or w/ adrenal INSUFF
What is the fusion product in non small cell lung cancer vs CML
NSSLC = EML4-ALK fusion, active TK -> malignancy, treat with TK I = crizotinib
CML t 9,22 = philadephila = Bcr-Abl fusion = TK activity causes profile granulocyte precursors, treat with TK I = imatinib
Describe changes to carboxyHgb, PaO2, and methemoglobin w/ CO poisoning
Normal PaO2 = O2 dissolved in blood doesn’t change unless vent/prof changes
Increase carboxyHgb = CO bd Hgb = INCREASES makes sense b/c Co binds Hgb with greater affinity than O2
No change methemoglobin - does not cause precipitation (when Fe2+ -> Fe3+, changes w/ drug exposure, enzyme def, hemoglobinopathies)
Which is a DNA vs RNA virus: Hep B vs C
B = RNA - incorporates into host genome so risk HCC stays high even after infectivity ceases/liver damage tapers off as you develop anti-viral Abs C = DNA - no RT, won't integrate into host genome
Explain why a person with B thal trait may have skewed diabetic control via HbA1c
B thal trait - B globin underproduced -> decreased Hgb A (2a,2b) and increase HgA2 (2a,2d)
HbA1c is talking and HgA NOT A2
Therefore less A to begin with will skew your readings if you are a diabetic
Pt has megaloblastic anemia - describe what happens if you start B12 or folate supplement
Start folate -> still have symptoms or develop new ones (neuro) then it was actually b/c B12 def
Treating B12 def /w folate will worsen demyelination by depleting [unmethylated cobalamin] for MM CoA processing
Describe PCR
Goal = amplify small DNA fragments
You need to know DNA segments flanking your target region to make the primers to start PCR
The target region doesn’t need to be known b/c may be mutated - that’s one of the reasons your doing PCR
+thermo stable DNA pol to repl DNA template from supplied pool of DNA bases
1. Denature via heat
2. Anneal - primers combine w/ ss or target region
3. Elongation - DNA pol forms new daughter DNA strands 5 -> 3 prime starting from 3’ end
Effects of adding TMP/SMX to ganciclovir
Gan SE = neutropenia, anemia, TCP, etc
For CMV infections in advanced HIV
TMP/SMX xs formation THF acid for purine/pyrmidine synthesis SE = bone marrow suppression
Together even higher risk bone marrow suppression (neutropenia)
Another one you’d want to watch in this scenario = zidovudine
What is heteroplasmy
= coexistence of distinct versions of mitochondrial genomes in 1 cell
Each cell has many mitochondria - each mitochondria has own DNA (you know that)
Varies the expression of mitochondrial diseases
Vs mosaicism = 2+ cells ones w/ unique nuclear genome in the same person
Describe inherited mitochondrial encephalopathy
Mito disease therefore
- Lactic acidosis - mito should do ox phos but here don’t have enough fxning mito
- Ragged skeletal muscle fibers - makes sense, mito dense tissues are muscle + neuro
What is one of the main differences in COX 1 and 2 besides their function?
COX 1 = constitutively expressed
COX 2 = induced by inflammatory states to release PGs
Mutation and presentation of alkaptonuria
Mutation in tyrosine breakdown to products for the TCA cycle
X homogentisic acid dioxygenase - build up homogentisate at:
1. Joints - darkening of articular cartilage
2. Deposits in eye: blue black spots in eye
3. Urine goes black on standing
Motor and sensory innervation of Tibial nerve Femoral n Superficial fibular nerve Deep fibular nerve
T: plantarflex, invert ankle, toe flex, sense plantar foot
*Prox injury to this nerve presents as dorsiflex + eversion w/ sensory loss, distal injury @ tarsal tunnel may be just sensory loss
F: hip flex, knee extend, sensory to medial thigh + ant knee + medial calf
SF: eversion, lateral calf + lat dorsal foot
DF: dorsiflex, extend toes, sensory to area between big toe and 2nd toe
Common tibial - think wrapping around fibular head
Describe presentation of parvoB19 in kids vs adults
Kids = 5th disease = erythema infectiosum = bright red rash in circle on cheeks Adults = acute arthritis in multiple joints that resolves on own
Depolarizing vs non-depol NMJ block
Non-depol = vecuronium = compete for post synpatic ACh R, train of four shows fading as less ACh is released with each impulse
Depol = SCh
Phase 1: TOF shows equal in all 4 twitches b/c presynaptic ACh R stim helps mobilize presynaptic ACh vesicle release
Phase 2: Persistant SCh exposure causes ACh R to become desensitized//inactivated (aka basically same as non deploy block)
Match up: ACL/PCL insertions on medial/lateral femoral epicondyle
ACL onto lat
PCL onto med
2 factors required for osteoclast differentiation vs osteoblast
M-CSF macrophage colony stim factor
RANK L = receptor for activated nuclear factor kappa B ligand
vs
Fibroblast growth factor
Mutation and presentation of McCune Albright Syndrome
Gs receptor mutation in alpha subunit -> always on adenylate cyclase
- Cafe au last spots - melanin production
- Endocrine problems: hyperT, early puberty
- Fibrous dysplasia - IL 6 production + osteoclast activation = many lesions throughout bone