UWorld 2 Flashcards
1
Q
What types of medications might increase osteoporosis risk? How might each of them cause this?
A
- anticonvulsants that induce cytochrome P450 (phenobarbital, phenytoin, carbamazepine)
- increase Vit D catabolism
- aromatase inhibitors and medroxyprogesterone
- decrease estrogen
- GnRH agonists
- decrease testosterone and estrogen
- PPIs
- decrease calcium absorption
- glucocorticoids
- decrease bone formation
2
Q
What is the spleen derived from?
What is unique about the origin of its blood spupply?
A
mesoderm of the dorsal mesentery
blood supply is derived from a foregut derivative (splenic artery off the celiac trunk). venous return from the spleen goes through splenic vein to portal system
3
Q
What is the liver derived from?
How does the liver receive blood?
A
endoderm derived structure of the foregut
receives arterial blood from the proper hepatic artery (via the celiac trunk) and receives venous blood from the gut via the portal vein
4
Q
Where are the kidneys derived from and what are their arterial and venous connections?
A
mesoderm derived
retroperitoneal and supplied by renal arteries from the abdominal aorta and drained by renal veins to the IVC
5
Q
The first two thirds of the transverse colon is derived from the… and supplied by…
Whereas the last one third of the transverse colon arises from the… and is supplied by …
How do the vessels anastomose?
A
midgut
superior mesenteric artery
hindgut
branches of teh inferior mesenteric artery
marginal artery
6
Q
What is an endoderm-derived structure of the foregut that receives blood primarily from the superior and inferior pancreaticoduodenal arteries?
A
pancreas
7
Q
Falsely conclude there is NO difference
A
Type II (beta) error
8
Q
falsely conclude there is a difference
A
Type I (alpha) error
9
Q
selection bias that can be created by selecting hospitalized patients as the control group
A
Berkson’s bias
10
Q
Within a study, what will increase as sample size increases? What does this mean?
A
power
the larger the sample, the greater the ability of a study to detect a difference when one truly exists
11
Q
What is the enzyme responsible for the production of the activated ribose necessary for de novo synthesis of purine and pyrimidine nucleotides?
What disease may have a mutation in this enzyme?
A
phosphoribosyl pyrophosphate synthetase (PRPP)
gout
12
Q
What is responsible for the intense inflammatory response seen in patients with gout?
A
neutrophils
phagocytosis of urate crystals by neutrophils causes the release of various cytokines and inflammatory mediators that lead to further neutrophil activation and chemotaxis, resulting in a positive feedback loop that amplifies the inflammatory response
13
Q
What is first line tx for gouty arthritis?
MOA?
What if the pt has contraindications to NSAIDs?
MOA?
A
NSAIDs
inhibit prostanoid biosynthesis (PGs, prostacyclin, thromboxanes) exerting a broad anti-inflammatory effect that includes inhibition of neutrophils
colchicine
impairs neutrophil migration and phagocytosis by interfering with microtubule formation and decreasing tyrosine phosphorylation in response to monosodium urate crystals
14
Q
How do fibrates work to lower triglyceride levels?
What about fish oils?
A
activate peroxisome proliferator-activated receptor alpha, which leads to decreased hepatic VLDL production and increased lipoprotein lipase activity
with high concentrations of omega-3 fatty acids, they decrease production of VLDL and apolipoprotein B
15
Q
What hydrolyzes triglycerides in chylomicrons and VLDL to release free fatty acids?
A
lipoprotein lipase (LPL)
16
Q
Most cases of secondary bacterial pneumonia s/p influenza infection are caused by…
A
S. pneumo, S. aureus, and H. influenzae
17
Q
reduced cardiac output in HF pts triggers compensatory activation of what systems?
What does this result in?
A
sympathetic nervous system and renin-angiotensin-aldosterone pathway
- resulting in vasoconstriction (increased afterload)
- fluid retention (increased preload)
- deleterious cardiac remodeling
perpetuate a downward spiral of cardiac deterioration, leading to symptomatic decompensated HF
18
Q
biopsy shows endomysial inflammation without prominent vascular involvement in a scattered or patchy distribution
What autoantibodies might you see?
A
polymyositis
anti-histidyl-tRNA synthetase (anti-Jo-1) antibodies
19
Q
What caution must you take with hydatid cysts?
A
Echinococcus granulosus is MCC, and spilling of cyst contents can cause anaphylactic shock
20
Q
What is the MC inherited cause of intellectual disability?
What is the defect?
What does chromosomal analysis show?
A
Fragile X syndrome
unstable expansion of trinucleotide repeats (CGG) in the fragile X mental retardation 1 (FMR1) gene, located on the long arm of chromsome X
small gap near tip of the long arm of the X chromosome
21
Q
What does the diphtheria vaccine do to prevent disease?
A
generates neutralizing IgG abs against the binding component of diphtheria toxin
22
Q
How do alcohol-based disinfectants kill enveloped viruses?
A
dissolving lipid bilayer membranes
23
Q
virus causing pink eye?
kids with this virus (rarely) can acquire what other pathology?
A
adenovirus (dsDNA, naked, linear)
hemorrhagic cystitis
24
Q
ssx: febrile neutropenia w/ ecthyma gangrenosum (EG)
pathogen?
How does EG come about?
A
Pseudomonas aeuruginosa
perivascular invasion and release of tissue-destroying exotoxins leading to edematous skin patches that necrose
25
pt injured in costal waters or is eating raw oysters
pathogen?
what would worsen the infection? what happens?
vibrio vulnificus
* liver disease or iron overload
* free Fe is exponential growth catalyst
* rapidly progressive necrotizing fascitis with hemorrhagic bullous lesions
26
abx v Pseudomonas
* ticarcillin
* piperacillin
* cefepime
* ceftazadime
* ciprofloxacin
* levofloxacin
* imipenem
* meropenem
27
lace like rash on stomach, back, and extremities of child; flushed face, congestion, HA, fever prior
dx?
pathogen?
replicates in what cell type?
erythema infectiosum (fifth disease/slapped cheek)
Parvovirus B19
erythroid precursor cells
28
MC atypical pna, pt doesn't appear that bad..
pathogen?
tx and MOA?
mycoplasma pneumoniae, or chlamydia pneumoniae
MP lacks cell wall and CP has other cell wall make up
rx macrolide or tetracycline, MOA: bacterial protein synthesis inhibitor
29
painless indurated granulomatous lesion to white/gray rubbery and can ulcerate and be about anywhere
what?
in what disease?
how else can this disease manifest?
gummas
tertiary syphilis
* CV involvement with ascending aortic aneurysms, valve insufficiency
* murmur high pitch S2 tambour
30
describe Zika virus and genus?
transmission?
it crosses the placenta to destroy?
ssRNA, Flavivirus
aedes misquito or genital secretions
fetal neuroprogenitor cells
31
B. henselae can cause cat scratch fever and what else?
cat scratch fever can present with ...
* bacillary angiomatosis
* immunocompromised
* red-purple papular skin lesions
* CSF: tender regional LAD, especially axillary
32
varicella and herpes encephalitis can present histologically as...
Cowdry's Type A inclusion bodies
33
What 2 drugs may be recommended to tx a pregnant woman with gestational hypertension?
labetalol or hydralazine
also okay: nifedipine and methyldopa
34
MC site of aneurysm causing oculomotor nerve palsy?
What ssx would be present and why?
posterior communicating artery
* lateral strabismus
* ptosis
* pupillary dilation
CN III innervates all eye muscles except lateral rectus (CN VI) and superior oblique (CN IV)
35
bacterium being able to take up exogenous DNA fragments and express encoded proteins is called...
transformation
36
What gene is responsible for acquired resistance to RTI, protease inhibitors and integrase strand transfer inhibitors?
What gene enables escape from host-neutralizing antibodies?
HIV pol gene
env gene
37
rx tx for RSV in 6 mo old?
ribavirin
prodrug, nucleoside inhibitor
38
to ward off encapsulated bacteria, you should..
vaccinate using conjugated polysaccharides
39
What is coinfection of a host cell by 2 viral strains creating progeny virions that contain nucleocapsid proteins from one strain and unchanged parental genome of the other strain?
no genetic exchange, so next generation...
phenotypic mixing
reverts to original, unmixed phenotypes
40
drug concentration equation
[drug]mg/L = (dose(mg))/ volume of distribution
41
What kind of leprosy will the lepromin skin test be + in?
pt with tuberculoid leprosy because of strong CD4+ Th1 cell-mediated response
lepromatous leprosy will be negative because of weak Th1 response
42
Tuberculoid leprosy pts develop a strong response through what kind of immune path?
Lepromatous leprosy affected tissues will show...
* Th1 cell mediated immune response
* increase IL-2, IFNy, IL-12
* accumulation of acid fast bacilli within macrophages and Th2 cytokine profile (IL-4, IL-5, IL-10)
43
Post-exposure prophylaxis for rabies includes what?
How is the vaccine created?
rabies immune globulin and vaccine (killed)
inactivated by Beta-propiolactone
44
What is the scientific name for a pinworm?
What is the first line tx?
What about tx in pregnant pts?
Enterobius vermicularis
Albendazole
pyrantel pamoate
45
hepatocellular carcinoma is usually preceded by...
How then, can HCC be prevented?
HBV
vaccination
46
Daptomycin can tx MRSA... MOA?
AE?
CI?
depolarization of cell membrane and inhibition of DNA, RNA, and protein synthesis
increase CPK levels and increase incidence in myopathy
cannot be used in pulmonary infection
47
What pathogen has M protein?
What does M protein do?
Abs can form against M protein and lead to...?
S. pyogenes
prevents phagocytosis, inhibits Complement binding, and mediates bacterial adherence
cross-react with epitopes on myosin, leading to rheumatic carditis
48
organisms with airborne transmission (4)
mycobacterium tb
rubeola virus (measles)
varicella zoster virus
variola virus (small pox)
49
P. aeruginosa virulence factors that may contribute to ecythema gangrenosum are...
* exotoxin A - protein synthesis inhibition
* elastase - blood vessel destruction
* phospholipase C - degrades cellular membranes
* pyocyanin - generates ROS
50
MOA of aminoglycoside streptomycin?
inhibit protein synthesis by inactivating 30S ribosomal subunit
51
MOA of Rifampin?
inhibit bacterial DNA-dependent RNA polymerase, preventing transcription from DNA to mRNA
52
MCC of meningitis in the elderly?
neonate?
infant?
child?
adolescents and young adults?
* S. penumo
* GBS/agalactiae and E. coli
* Hib if no vax, S. penumo or N. meningitidis
* N. meningitidis if no vax
53
What is mixing of genome segments in segmented viruses that infect the same host cell?
How do they interact?
What virus is known for this?
reassortment
2 segmented viruses exchange whole genome segments
highly mutagenic influenza virus
54
squamous cell cancer of bladder in East Africa and middle East; painless hematuria and pulmonary HTN
pathogen?
other features?
tx?
Schistosoma haematobium
* blood fluke/trematode
* urinary and genital involvement
* increase exposure in field/manual labor
* calcification of bladder and ureters
tx is radical cystectomy if no metastases
55
Lab results of RMSF would include...
underlying pathophysiology?
rx tx?
hyponatremia due to increased ADH secretion d/t hypovolemia and thrombocytopenia
invasion of vascular endothelial cells by bacteria (increase vascular permeability, hypovolemia, hypotension)
doxycycline
56
2 pathogens that inactivate eEF-2 and their toxins that cause it?
what does eEF-2 do?
* C. diphtheria/ diphtheria toxin
* P. aeruginosa/exotoxin A
inhibit eukaryotic cell protein synthesis
57
resolved Hep B infection or immunized for Hep B
* no Ag
* + Anti-HBsAg
* + Anti-HBcAg
* + Anti-HbeAg
or
* + Anti-HBsAg
58
How can enterococci become resistant to Vancomycin (VRE)?
organsims substitute D-lactate in place of D-alanine during peptidoglycan cell wall synthesis
Vanc usually binds D-alanyl-D-alanine in cell wall
59
Babesiosis
pathogen/vector?
ssx?
dx?
* babesia microti
* ixodes tick
* NE US
* flu-like ssx, anemia, thrombocytopenia, increased LFTs
* dx: thin blood smear (WrightGiemsa) intraerythrocytic pleomorphic ring forms, occasionally maltese cross
60
What are classic findings in Zika infected newborn?
* microcephaly with large facial features
* arthrogryposis (contractures)
* cortical thinning/loss of brain mass
* fetal demise possible
61
What pathogen normally is in the colonic and urogenital flora that can grow in hypertonic saline and bile? describe
GU instrumentation or catheterization could therefore potentially cause...
enterococcus
* g+ cocci
* gamma hemolytic
* catalase neg
* PYR+ (pyrrolidonyl arylamidase +)
enterococcal endocarditis
62
toxin MOA for
botulinum?
tetani?
shiga?
cholerae?
inhibits ACh release
inhibits glycine and GABA release
interferes with 60S ribosomal subunit
activates cellular adenylate cyclase, increasing cAMP (increase chloride and water secreation
63
most of the cutaneous lymph from the umbilicus down, including the anus below the dentate line, drains to what lymph nodes?
What are the two exceptions?
superficial inguinal lymph nodes
glans penis and posterior calf, draining to the deep inguinal nodes
64
lymph from the upper third of the rectum drains to the... while lymph from the testes drains to...
inferior mesenteric lymph nodes
abdominal para-aortic (retroperitoneal) lymph nodes
65
Lymph from the superior portion of the bladder drains to... while the inferior portion of the bladder and the prostate both drain lymph to...
external iliac nodes
internal iliac nodes
66
exaggerated drop (\>10mmHg) in systolic BP during inspiration
How is this quantified?
Who will I see this in?
pulsus paradoxus
the difference between the systolic pressure at which Korotkoff sounds first become audible during expiration and the pressure at which they are heard throughout all phases of respiration quantifies pulsus paradoxus
pt with cardiac tamponade, severe asthma, COPD, and constrictive pericarditis
67
What are the 5 major causes of hypoxemia?
* alveolar hypoventilation
* low partial pressure of inspired oxygen
* ventilation-perfusion mismatch
* diffusion impairment
* and right to left shunting
68
What can differentiate alveolar hypoventilation from other causes of hypoxemia?
A-a gradient is normal and low partial pressure of inspired oxygen
69
What kind of drugs are myasthenia gravis patients extremely sensitive to?
nondepolarizing neuromuscular blocking agents (competitive antagonists of AChRs
due to depletion of receptors, patients with MG are extremely sensitive to these agents and very small doses can induce paralysis and impair airway production
70
What is the MC trigger for DIC in pregnancy?
release of tissue factor (thromboplastin) from an injured placenta (eg placental abruption) into the maternal circulation
71
two genetic loci are said to be in....... when their respective alleles are inherited together in the same gamete (haplotype) more or less often than expected by chance alone given their corresponding allele frequencies.
This is often the result of.... of genes on the same chromosome
linkage disequilibrium
physical proximity
72
How do you estimate the expected probability of 2 alleles from separate loci appearing together?
multiply their occurence rates
fr x fr
73
what describes the presence of different mitochondrial genomes (eg mutated and wild type) within a single cell?
heteroplasmy
74
what is the occurence of multiple phenotypic manifestations, often in different organ systems, which result from a mutation in a single gene?
pleiotropy
75
In SLE, anti-Smith abs are commonly seen. What does the Smith protein normally do?
normally complexes with small nuclear RNA (snRNA) in the cytoplasm, forming small nuclear ribonucleicproteins (snRNPs)
76
What are the two stages of mRNA synthesis?
What are the parts of the second stage?
1. DNA template is transcibed into a complementary strand of pre-mRNA
2. pre-mRNA is processed into mature mRNA
1. RNA capping (addition of a methylated guanine nucleotid to 5' end)
2. RNA polyadenylation (addition of several adenine nucleotides to the 3' end (poly-A tail)
3. RNA splicing (Removal of introns (noncoding regions) by spliceosomes, which consist of snRNPs and other proteins)
77
What hormones are most prevalent during transition to menopause?
FSH levels increase due to resistant ovarian follicles and lack of feedback from inhibin
absence of menstrual cycles is associated with hypoestrogenic symptoms
estradiol and progesterone levels gradually decrease during the menopausal transition due to decreasing ovarian function (not a reliable indicator of menopause)
78
How does PCP (phencyclidine) work?
hallucinogen that works primarily as an N-methyl-D-aspartate (NMDA) glutamate receptor antagonist
NMDA receptor hypofunction increases the risk of psychosis partially by causing dopamine dysregulation
can also inhibit the reuptake of NE, DA, and serotonin and affect neuronal sigma receptors
79
What are the two branches off of the external iliac artery?
inferior epigastric artery (proximal to inguinal ligament)
deep circumflex iliac artery (branches more laterally but also supplies blood to the lower abd wall)
80
What is the fastest conducting tissue in the heart? the slowest?
fastest: purkinje system
atrial muscle
ventricular muscle
slowest: AV node
81
autonomic instability, altered mental status, and neuromuscular hypertrophy
dx?
what is this often caused by?
serotonin syndrome
due to combined effects of several serotonergic medications, overdose, and/or a drug-drug interaction
82
What antibiotic might play a role in precipitating serotonin syndrome?
what does it tx normally?
why?
Linezolid - gram + bacteria, especially VRE and MRSA
it has MAOI activity and therefore can precipitate serotonin syndrome with soncomitant use of an SSRI
83
conclusion that there is no difference between the groups studied when a difference truly exists; random error, not systematic error (ie bias)
beta error
84
First gen antihistamines that very much cause sedation
what are they used to tx?
* diphenhydramine
* promethazine
* hydroxyzine
* chlorpheniramine
prevent/tx allergic reactions, motion sickness and as antiemetics
85
ranitidine ...
H2 receptor antagonist that inhibits gastric acid secretion
slight affinity for CYP450
86
Tetralogy of Fallot results from what?
anterior and cephalad deviation of the infundibular septum during embryologic development, resulting in a malaligned ventricular septal defect with an overriding aorta
87
what happens in anomalous pulmonary venous return?
blood from both pulmonary and systemic venous systems flow into the right atrium, leading to right atrial and ventricular dilation
88
L to R shunt is occurring, over time, pulmonary vascular resistance increases leading to bidirectional flow, eventually a R to L shunt is present
dx?
Eisenmenger syndrome
89
formula for half life
=(0.7x Vd)/CL
90
Where is the optimal site for a femoral nerve block?
What will it anesthetize?
inguinal crease at the lateral border of the femoral artery
skin and muscles of the anterior thigh, femur, and knee along with saphenous nerves (terminal extension of femoral nerve) to decrease sensation in the medial leg below the knee
91
contralateral homonymous hemianopia with macular sparing would mean an occlusion of what artery?
posterior cerebral artery - lesion in occipital cortex
92
In a HGPRT deficiency, what enzyme will be increased in order to supply a sufficient amount of purine nucleotides?
how does this do that?
PRPP aminotransferase
de novo purine synthesis
93
aspartate carbamoyltransferase
dihydroorotase
thymidylate synthase
these enzymes do what?
involved in pyrimidine synthesis
94
How does lymph flow from the lower extremities?
* superficial lymphatic system is divided into medial and lateral tracks
* medial track runs along saphenous vein up to the superficial inguinal lymph nodes, bypassing the popliteal nodes
* the lateral track communicates with the popliteal and inguinal nodes, causing lymphadenopathy in both the popliteal and inguinal areas
95
If there is a reduction in the number of postsynaptic cation channels that can open in response to acetylcholine, how does it prevent muscle fiber depolarization?
reduction of the amplitude of motor end plate potential
96
What is the tx of myasthenia gravis?
What AE are possible?
How can you ameliorate these AEs?
* cholinesterase inhibitor, immunosuppressants, and possible thymectomy
* muscarinic overstimulation
* antimuscarinic agents
* glycopyrrolate
* hyoscyamine
* propantheline
97
What is pilocarpine?
nonselective muscarinic receptor agonist
98
What can be given to improve anemia symptoms and avoid the need for blood transfusions in CKD and dialysis patients?
What are risks that come with this use?
Erythropoiesis-stimulating agents (ESAs)
risk increased for HTN and thromboembolic events
99
How do osmotic diuretics work?
What are common side effects?
what is a more severe toxicity?
* rapidly increase plasma or tubular fluid osmolality, causing water to move from the interstitial space into the vascular space or tubular lumen
* HA, nausea, vomiting
* aggressive overtx can lead to excessive volume depletion and eventual hypernatremia in certain patients
* pulmonary edema
100
Bumetanide MOA
loop diuretic that works by inhibiting NaK2Cl symporters in the ascending limb of the loop of Henle to block Na and Cl transport and increase Na, Cl, and fluid excretion
101
Triamterene MOA
Potassium sparing diuretic blocks Na channels in the distal tubule and collecting duct
102
What characteristics of a drug might lend itself to being trapped in the plasma compartment resulting in a low Vd (3-5L)?
* high molecular weight
* high plasma protein binding
* high charge
* hydrophilicity
103
What is the major underlying cause of disease severity when infected with N. meningitidis?
How might a pt present?
lipooligosaccharide - virulence factor in outer membrane
rapid-onset sepsis and circulatory collapse in otherwise healthy young individuals - myalgias, high fever, headache, and altered level of consciousness and quickly progressing to hypotension, organ failure, and death
often have a petechial/ecchymotic rash due to underlying DIC
104
How does LOS and LPS work as a virulence factor?
they are endotoxins that cause toxicity when released into the plasma via shedding of the outer membrane (blebbing) or bacterial lysis
endotoxins bind to Toll-like receptor 4 on monocytic and dendritic cells and trigger release of inflammatory cytokines
105
What anticholinergic drugs can reach both central and peripheral nervous systems?
Which ones are only able to reverse cholinergic effects in the periphery?
tertiary amines (physostigmine, galantamine, donepezil, rivastigmine) - lipophilic, nonpolar, can cross BBB
quarternary amines (neostigmine, edrophonium, pyridostigmine) - hydrophilic and not readily crossing BBB
106
ANP and BNP are released from the atria and ventricles and do what?
in response to myocardial wall stretch due to intravascular volume expansion
promote increased glomerular filtration rate, natriuresis, and diuresis
107
Characteristics of a complete molar pregnancy?
* empty ovum fertilized by 2 sperm (or one sperm that duplicates chromosomes); 46 chromosomes
* no fetal tissue
* all villi are hydropic (villous edema)
* diffuse circumferential proliferation around hydropic villi (trophoblastic proliferation)
* 2-3% risk for choriocarcinoma
108
Characteristics of partial molar pregnancy?
* normal ovum fertilized by 2 sperm (or one sperm that duplicates chromosomes); 69 chromosomes
* fetal tissue present
* some villi hydropic, some normal
* focal proliferation present around hydropic villi
* minimal risk for choriocarcinoma
109
no upper vagina (short vagina), and varible uterine development; 46 XX females with normal ovaries and secondary sex characteristics
dx?
What else should you consider screening for?
Mullerian aplasia (Mayer-Rokitansky-Kuster-Hauser Syndrome)
consider looking for a renal abnormalities
110
olfactory sensory defect in male, very rarely female, decreased GnRH in hypothalamus
Kallman syndrome
111
Triglycerides stored in adipose are broken down during DKA and glycerol is sent back to the liver to be converted into glycerol-3-phosphate by what enzyme?
Then what happens?
glycerol kinase
glycerol-3-phosphate is converted to glycerol-3-phosphate dehydrogenase to dihydroxyacetone phosphate (DHAP) which can be used to produce glucose through gluconeogenesis
112
biotin dependent enzyme in liver and adipose; catalyzes first committed step in fatty acid synthesis (conversion of acetyl CoA to malonyl CoA)
acetyl CoA carboxylase
113
fatty acids must be activated by what enzyme prior to being able to undergo beta-oxidation in mitochondria?
acyl CoA synthetase
114
While being at high altitudes, are you more likely to be acidodic or alkalotic?
Why?
* PiO2 is decreased leading to hypoxemia
* reducing PaO2
* triggers chemoreceptors in carotid bodies to stimulate ventilation and causing increased exhalation of CO2
* respiratory alkalosis
* over several days, kidneys compensate by increasing bicarb excretion to normalize pH
115
Pts with panic disorder often develop...
agoraphobia
116
cognitive testing of attention and concentration includes what tasks?
reciting months of the year backward
counting down from 100 in intervals
spelling world backwards
117
lymphatic channels proximal to the anal dentate line drain into...
areas distal to the anal dentate line drain primarily into the...
the inferior mesenteric and internal iliac lymph nodes
inguinal nodes
118
DiGeorge syndrome has failed development of what embryological structures?
What will this cause?
third (inferior parathyroid and thymus) and fourth (superior parathyroid) pharyngeal/branchial pouches
hypocalcemia and T cell deficiency
119
If the second branchial cleft is not obliterated in utero as it normally is, what will its persistance cause?
branchial cleft cyst between the angle of the mandible and sternocleidomastoid muscle
120
de novo partial deletion of the short arm of chromosome 5
cri du chat
121
2 yo boy with urine that turns black overnight
deficiency?
dx?
why are there black and blue colors?
tyrosine to fumarate deficiency (homogentisic acid dioxygenase)
alkaptonuria - disorder of tyrosine metabolism
homogentisic acid accumulates in the body and is excreted in the urine. retained HA selectively binds to collagen in CT, tendons, and cartilage --\> ochronosis and ochronotic arthropathy
122
What aa is increased in maple syrup urine disease?
What happens because of the impaired metabolism?
leucine, isoleucine, and valine
cerebral edema, seizures, and sweet smell of urine
123
substitution of valine for glutamic acid
sickle cell
124
Ehlers danlos can be caused by what type of deficiency?
procollagen peptidase deficiency, resulting in impaired cleavage of terminal propeptides in the extracelluar space
125
What is the reason for the incresed incidence of cholelithiasis in women who are pregnant or using oral contraceptives?
estrogen induced cholesterol hypersecretion and progesterone induced gallbladder hypomotility
126
the probability of rejecting a null hypothesis when it is truly false
power (1-beta)
127
thyrotropin receptor antibodies
Graves disease
128
what pathway helps breakdown intracellular proteins (both foreign and native) and helps recycle them into amino acid building blocks?
UPP - ubiquitin proteasome pathway
129
What does ubiquitin do?
How does this happen?
functions as a tag that is attached to proteins to mark them for destruction
ubiquitin ligases, enzymes that recognize specific protein substrates and catalyze ubiquitin attachment
130
How would you know when the fetal lung is considered to be mature?
* checking phospholipid content of amniotic fluid
* lecithin to sphingomyelin ratio in amniotic fluid is \>=2, fetal lung is considered mature
131
in cases of suspected erythroblastosis fetalis, amniocentesis is checking for what
assess fetal hemolysis by measuring amniotic fluid bilirubin levels
132
How would you detect Congenital Adrenal Hyperplasia?
* antenatal detection via amniocentesis
* measure 17-hydroxyprogesterone levels
* gene linkage analysis involving the HLA region of chromosome 6
* detection of abnormal genes via molecular probes
133
What is the MCC of hair loss in males and females?
What kind of inheritance pattern does it have?
androgenetic alopecia
polygenic inheritance with variable expressivity
134
What are some common medical conditions with polygenic inheritance?
* androgenetic alopecia
* epilepsy
* glaucoma
* hypertension
* ischemic heart disease
* schizophrenia
* type II DM
135
How does hormone sensitive lipase get activated in order to keep blood glucose close to normal range while prolonged fasting is occurring?
* found in adipose tissue
* catalyzes the mobilization of triglycerides into FFA and glycerol
* activated in response to stress hormones
* catecholamines, glucagon, ACTH
* inhibited by insulin release
* Stress hormones stimulate Gs coupled receptors on adipocytes
* increasing cAMP production
* activating PKA
* phosphorylates and activates HSL, stimulating lipolysis
136
Why would the coronary sinus ever be dilated?
what does the coronary sinus drain?
where does it open to?
* it communicates freely with the right atrium and gets dilated related to any factor that causes increased right atrial pressure
* MCC is pulmonary HTN
most of the venous drainage from the myocardium, deoxygenated blood to the R atrium
opens to R atrium between IVC and tricuspid valve
137
What is the CFTR protein?
what does a defect here cause?
transmembrane ATP-gated chloride channel
thick, plugging mucous and elevated sodium and chloride levels in sweat (cystic fibrosis)
138
small ovoid bodies within a macrophage - fungal dx?
how does it replicate?
what if you are immunocompromised?
what are common manifestations?
* histoplasma capsulatum
* replicates within the phagosome of macrophages
* at risk for dissemination through the reticuloendothelial system
* hepatosplenomegaly, lymphadenopathy, pancytopenia, ulcerated lesions on the tongue
139
Where is glycosyltransferase used? (bacteria wise)
component of peptidoglycan synthesis (main component of bacterial wall in g+ and g- organisms)
it adds glycan molecules to growing peptidoglycan chain
140
How will functional residual capacity change in a COPD pt?
increase
due to air-trapping
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Cimetidine MOA?
tx GERD via blocking parietal cell H2 receptors
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PPIs (omeprazole, lansoprazole) MOA?
block the final common pathway of fastric acid secretion from parietal cells, stimulated by acetylcholine, histamine, and gastrin (H/K-ATPase pump)
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isoproterenol MOA?
beta 1 and beta 2 adrenergic agonist that causes increased myocardial contractility (positive inotropic activity of B1) and decreased systemic vascular resistance (vasodilation by relaxation of vascular smooth muscle by B2)
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how does acetylcholine affect the heart?
binds to M2 and M3 in vasculature and causes decreased heart rate and conduction velocity and vasodilation
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how does adenosine work on the heart?
acts on A1 receptors on cardiac cells and activates K channels, increasing conductance; leads to transient conduction delay through the AV node; can also cause peripheral vasodilation, attenuates the adrenergic-mediated increase in contractility
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how does clonidine work?
stimulates a2 adrenoreceptors in the brainstem, resulting in reduced sympathetic outflow from the CNS, leading to a decrease in peripheral vascular resistance, HR, and BP
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esmolol MOA?
selective B1 blocker with negative inotropic and chronotropic effects causing a decrease in cardiac contractility
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pt has elevated CK, what are we thinking?
myopathic process with myocyte damage and release of muscle enzymes into circulation
* hypothyroid
* muscular dystrophies
* inflammatory muscle diseases
* medications like HMG-CoA reductase inhibitors
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What are symptoms of TCA OD?
Why would sodium bicarb be used as treatment?
* AMS, seizures, prolonged QRS duration, ventricular arrhythmias, and anticholinergic findings
* txs associated cardiac toxicity and works by increasing serum pH and extracellular Na (alleviating fast sodium channel blockade)
150
What is used in case-control studies in order to control confounding?
matching
matching variables should always be the potential confounders of the study (eg age, race)
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disorder caused by mutations in the SMN1 gene, resulting in impaired assembly of snRNPs in lower motor neurons
how does this present?
spinal muscular atrophy
infants often have flaccid paralysis due to degeneration of anterior horn cells in the spinal cord
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Baclofen MOA
what else can be used to control the same symptoms?
agonist at GABA-B receptor - monotherapy for tx of spasticity secondary to both brain and spinal cord disease, including MS
tizanidine (alpha2 agonist)
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Why would you have brown pigment gallstones?
composed of calcium salts of unconjugated bilirubin and arise secondary to bacterial or helminthic infection of the biliary tract
beta-glucuronidase released by injured hepatocytes and bacteria hydrolyzes bilirubin glucuronides to unconjugated bilirubin
154
Why would pigmented gall stones appear in the absence of infection?
when excess bilirubin is excreted, such as with hemolytic anemia
155
How is a PDA murmur characterized and where on the chest would you auscultate it?
continuous murmur heard best in the left infraclavicular region with maximal intensity at S2
156
What in the kidney will sense if the kidney is not getting enough blood flow?
juxtaglomerular apparatus - consists of macula densa, extraglomerular mesangial cells (Lacis cells), and JG cells
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tall, narrow cells located in the distal tubule that monitor salt content and tubular flow rate
macula densa cells
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where are JG cells located and where do they get information from?
How would you describe JG cells?
wall of the afferent arteriole, info from macula densa
modified smooth muscle cells with renin-containing zymogen granules
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significant renal hypoperfusion leads to a compensatory...
if it is chronic hypoperfusion, what will happen?
increase in renin secretion by JG cells
JG cells will undergo hyperplasia as a result of chronic stimulation
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incomplete obliteration of the omphalomesenteric duct that connects the midgut lumen and yolk sac cavity early in fetal life
meckel diverticulum
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microscopically and functionally normal cells/tissues found in an abnormal location due to embryonic maldevelopment
ectopy
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LE paresthesias, macrocytic RBCs, and gastric body and fundus atrophy
dx?
mechanism?
where are affected cells located?
pernicious anemia
autoimmune destruction of parietal cells (oxyntic cells found predominantly in the upper glandular layer of teh gastric body and fundus)
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chronic pernicious anemia will cause what anatomical change?
progressive parietal cell destruction leads to atrophic gastritis, characterized by CD4 predominant inflammatory infiltrate, oxyntic gland atrophy and intestinal metaplasia
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Why do pts with pernicious anemia develop neurologic dysfunction?
deficiency of B12, demyelination of the dorsal and lateral spinal tracts, resulting in paresthesias and ataxia
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autosomal recessive disorder characterized by defects in nucleotide exision repair often caused by a deficiency in UV-specific endonuclease
dx?
ssx?
xeroderma pigmentosum
affected children usually have severe photosensitivity, hyperpigmentation in sun exposed areas, and a greatly increased risk for skin cancer
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pulomonary hypoplasia along with facial and lower limb deformities
dx?
how does this occur?
what is the classic finding?
* Potter sequence
* renal anomaly that leads to decreased urine output by the fetus - leading to oligohydraminos or anhydraminos
* lack of amniotic fluid causes compression of the fetus leading to characteristic facies and limb abnormalities, and pulmonary hypoplasia
* classic finding is bilateral renal agenesis
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What is the rate limiting enzyme of the PPP?
What happens if there is a deficiency of this?
G6PD (glucose-6-phosphate dehydrogenase)
X linked recessive disorder resulting in episodic bout of hemolysis when RBCs experience increased oxidative stress
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What does G6PD do?
catalyzes conversion of glucose-6-phosphate to 6-phosphogluconolactone, which is then converted to 6-phosphogluconate
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What is the purpose of the PPP?
generate NADPH and ribose-5-phosphate, a precursor for nucleotide synthesis
RBCs utilize reduced NADPH to maintain a steady supply of glutathione, a molecule capable of neutralizing free radicals and therefore protecting teh cells against oxidative damage
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What microscopically happens to the RBCs exoposed to oxidative damage or stress?
causes hemoglobin to denature, forming insoluble Heinz bodies that are removed in the spleen - creating characteristic bite cells (G6PD deficiency)
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What will aldosterone excess cause physiologically?
What causes type IV renal tubular acidosis?
hypertension, hypokalemia, metabolic acidosis and depressed renin
hypoaldosteronism
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What is Conn Syndrome and how is ti treated?
primary hyperaldosteronism (can be adenoma)
aldosterone antagonist, such as spironolactone or eplerenone
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How would you prevent neonatal GBS sepsis, pneumonia, and meningitis?
intrapartum penicillin or ampicillin
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immediate onset of euphoria, lethargy, ataxia, and/or LOC followed by rapid recovery within 45 min is indicative of...
what can be seen in chronic users?
inhalants
perioral or perinasal dermatitis (ie glue sniffers rash)
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Hyperaldosteronism is characterized by increased Na+ reabsorption from the collecting tubule. How does this cause the other physiologic changes seen in hyperaldosteronism?
* creates a negative charge in the lumen, pulling K+ and H+ from tubular cells and leading to increased excretion of these
* results in hypokalemia
* increased H+ excretion by alpha-intercalated cells promotes bicarb production and increased acivity of the basolateral HCO3-/Cl- exchanger
* results in metbolic alkalosis
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Why isnt hypernatremia associated with hyperaldosteronism?
aldosterone escape
* increased intravascular volume causes increased renal blood flow (with resulting pressure natriuresis) and augmented release of atrial natriuretic peptide
* limits net sodium rentention and prevents teh development of overt volume overload and significant hypernatremia
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Why would you want to adjust a ventilator to a lower PaCO2 level?
decrease ICP
CO2 is a potent vasodilator of cerebral vasculature; tachypnea causes hypocapnia and cerebral vasoconstriction, thereby decreasing cerebral blood volume and ICP
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what type of hernia passes through the deep inguinal ring, are covered by internal spermatic fascia, and are located lateral to the inferior epigastric bloos vessels?
indirect inguinal hernia
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What occurs if there is failure of obliteration of the processus vaginalis?
leads to a persistent connection between the scrotum and the peritoneal cavity through the inguinal canal
if the opening is small and allows for fluid leakage only, a communicating hydrocele develops
if the opening is large it can allow for the passage of abdominal organs, an indirect inguinal hernia
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non-specific inflammation of the testes that is classicly associated with mumps
in young adults and adolescents, what is it commonly caused by?
older pts?
orchitis
Chlamydia trachomatis and neisseria gonorrhea
e. coli
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Where are direct inguinal hernias located?
do not pass through the inguinal canal and are located medial to the inferior epigastric blood vessels
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Myocyte depolarization causes activation of ........ calcium channels on the plasma membrane.
In cardiac and smooth muscle this leads to....
The released calcium then binds to... in cardiac muscle or .... in smooth muscle, allowing actin and myosin to interact and cause muscle contraction.
L-type
influx of extracellular calcium that activates sarcoplasmic RyR channels, inducing the release of additional calcium from the SR.
troponin, calmodulin
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How does activation of L-type channels in skeletal muscle differ from those in smooth muscle or cardiac muscle?
these directly interact with RyR calcium channels to release calcium from the SR.
mechanical coupling between the receptors allows SR calcium release to occcur without significant influx of calcium across the plasma membrane
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MOA of Verapamil
how does it only work on the heart?
nondihydropyridine CCB that acts by blocking L-type calcium channels, preventing the initial calcium influx into cardiac myocytes and vascular smooth muscle cells
bc skeletal muscle is not dependent on extracellular calcium influs, CCBs do not affect skeletal muscle contractility
185
What are the etiologic agents most commonly causing COPD exacerbations - bacteria and viral?
* Haemophilus influenzae (#1)
* S. pneumoniae, Moraxella catarrhalis
* rhinovirus
upper respiratory pathogens
186
How does a Zenker diverticulum form?
abnormal spasm or diminished relaxation of the cricopharyngeal muscles during swallowing (cricopharyngeal motor dysfunction)
187
How and where does isotype switching of immunoglobulins occur?
in germinal centers of lymph nodes and requires interaction of the CD40 receptor on B-cells with the CD40 ligand (CD154) expressed by activated T cells
188
early infancy presentation with cardiomegaly, macroglossia, and profound muscular hypotonia
dx?
deficiency/accumulation?
Pompe disease - glycogen storage disease type II
acid maltase (alpha-glucosidase) deficiency
abnormal glycogen accumulation within lysosomal vesicles is seen on muscle biopsy
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Cytogenic studies of Patau syndrome usually demonstrate...
what is the chromosome count?
meiotic nondysjunction - failure of chromosomal separation during meiosis, causing inheritance of a chromsome pair from 1 parent rather than a single chromatid
(47, XX, +13)
190
What results from the inability to convert phenylalanine into tyrosine, a reaction normally catalyzed by phenylalanine hydroxylase?
what cofactor is required?
phenylketonuria (PKU)
tetrahydrobiopterin (BH4)
191
homozygous infants with PKU are normal at birth but gradually...
what is also usually seen in appearance?
develop severe intellectual disability and seizures if left untreated.
hypopigmentation of the skin, hair, eyes, and catecholaminergic brain nuclei is also frequently seen
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