Missed Questions Uworld - Week 2 Flashcards
What would signify a twisted, serpentine pattern/parallel chains of growth of a mycobacterial organisms?
Consistent with the presence of cord factor
Cord factor = mycoside = composed of 2 mycolic acid molecules bound to the disaccharide trehalose; correlates with virulence [responsible for inactivating neutrophils, damaging mitochondria and inducing release of TNF; inhibits macrophage activation]
In a mycobacteria, NO cord factor = NO disease
What is the difference between T-test and analysis of variance test (ANOVA)?
T-test is used to cmpare teh difference between the means of 2 groups; when more than 2 groups are to be compared, ANOVA is used
When does the epithelium of the airway change?
When you stop having goblet cells?
By the TERMINAL BRONCHIOLES, the airway epithelium changes from pseudostratified cilated columnar to cilated simple columnar
CIlia is present through the respiratory bronchioles but not present in the alvolear ducts or in the alveoli.
Mucin producing cells/goblet cells end in the smallest bronchi, just before the bronchioles begin
What happens to the following in repsones to high altititude:
PO2, PCO2, pH
DEC PiO2 –> hypoxemia –> reduction in arterial oxygen tension –> triggers chemoR in the carotid bodies to stimualte ventilation –> HYPERVENT –> decrease in arterial CO2 –> respiratory alkalosis, pH rises acutely!, renal compensates by increasein the loss of bicar (24-48 hour delay)
2+ days –> complete or partial compensated respiratory alkalosis
Hypoxemia and the associated ventilatory response persists for hte duration of the ascent, but magnitude reduces with acclimatization
LONG TERM:
INC in 2,3 DPG, Hb, pulmonary diffusing capacity, vascular endothelial growth factor induced angiogenesis, INC cellular mito, hemoconcentration
What are examples of delayed-type hypersensitivity reactions
How do the work?
CONTACT dermatitis, granulomatous inflammation, tuberculin skin test, candida extrac skin test
Type IV
delayed meaning they take about 1-2 days after antigen exposure [think of waiting 48-72 hours for TBtest]
Antigen is taken up by dendritic cells and presented to CD4+ T cells on MHC II molecules [usually TH1] release interferon-gamma –> stimulate and recruit macrophages leading to a moncytic infiltration of the area where the antigen is indtorudced
also “walling off” of infection
Tx for oral thrush?
Candida fungi
Tx: Nystatin
swish and swallow
polyeye antifungal w/mxn similar to amphotericin B/ergosterol molecules in teh funal cell membrane - causing pores adn leakage of funacl cell contents
Nocardia
gram positive rod - beaded/branched
partiall acid-fast, aerobic
affects immunocompromised
could seen as pulmonary infection (similar to TB), brain aabsecess, and skin
TX: sulfonamides, and drainage of abscesses
APC and
+ IL 12 and interferon gamma –>
+ IL4
+IL12/interferon gamma –> TH1 –> inteferon gamma, IL2- lymphotoxin B
CELL MEDIATED [intracellular, mycobacterial infections]
activation of macrophages and CD8+ T cells
mediation of delayed type hypersen reactions
HUMORAL:
+IL4 –> TH2, b cell, plasma cells –> antibodies
initation of antibody response, regulation of immunoglobulin class switching
[extracellular viruses or bacteria]
what bacteria are spore forming and found in soil?
Bacillus anthracis and membrers of hte genus clostridium
Verenicline
Use?
Reduction of nicotine craving
reduction of pleasureable effects of cigarettes and other tabacco products
Partial stimulaiton of nicotinic acetylcholine R-
competes with nicotine (full agonist)
reduces nicotine withdrawal
prevents nicotine from binding and inducing rewarding response
what is the deficiency seen in hyper IgM syndrome?
genetic deficiency in the enzymes responsible for isotype switching (such a d DNA recombinase) or in the CD40 T lymphocyte ligand that is essential in inducing B cell to switch classes
elevated/NL IgM
unable to synthesize all other immunoglobulin heavy chain constant regions
clinical effects = recurrent sinus and airway infections (due to IgA deficiency)
Tx: IvIg
Decrease breath sounds could be an indicaiton of what? (5)
DEC breath sounds: pleural effusion, atelectasis/bronchial obstruciton, pneumothorax, or tension pneumothorax
What is the characteristic breathing pattern seen in pt with advanced CHF?
Cheyne-stokes breathing
cyclic breathing pattern in which apnea is followed by gradully increasing then decreasing tidal volumes until the next apneic period
chronic hyperventilation with hypocapnia – induces apnea during sleep when the pp of CO2 falls below a certain level (apneic threshold)
[this type of breathing pattern is also seen in other neurologic disease states - stroke, brain tumors, traumatic brain injury - poor prognostic sign]
When is kussmaul breathing seen?
Kussmaul breahting is deep and labored breathing pattern often associated with severe metabolic acidosis, particularly diabetic ketoacidosis
What are common features seen in the sputum of asthmatics?
Curchmann spirals (shed epithelium formed whorled mucus plug)
Charcot-Leyden crystals (eosinophilic, hexagonal, double pointed, neddle-like crystals formed from breakdown of eosinophils in sputum)
What are the different types of infections caused by candida in HIV pt with..
CD <500
and CD<100
@ CD <500: oral thursh
@ CD <100: esophagitis
What is the classic presentation of Legionella?
High fever with relative bradycardia, headache confusion, pneum with watery diarrhea
Lab findings: hyponatremia, sputum gran stain showing many neutrophils but few to no organisms (often affecting smokers)
dx: urine antigen test
* acquring diagnositc sputum sample is difficult and unreliable, often sowing few or no bacteria since unique LPS chains on the outer membrane inhibit gram staining*
tx: respiratory fluoroguinolones or newere macrolides
What is thought to cause sarcoidosis?
Dysregulation of cell-mediated immune response to an unidentified antigen that results in the formation of non-caseating granulomas
Cell-mediated is driven by Th1 type CD4+ T helper cells, secrete IL2 and interferon gamma
IL2- stimulates teh autcrine proliferation of TH1
Interferon gamma activates macrophages, promoting granuloma formation
Lung granuloma in sarcoid are result of intra-alveolar and interstitial accumulations of CD4+ T cells due to oligoclonal expansion and increased levels of IL2 and IFN-gamma
Chronic granulomatous disease:
Pathogensis
clinical manifestations…what infections are highly seen?
Diagnosis:
Pathogen: inactivating mutation affecting NADPH oxidase [nl fxn: ROS formation, needed for microbicidal activity, activate granule proteases]
Clinical manifestations: recurrent infections with CATALASE POSITIVE bacteria and fungi
lungs, skin, lym, and liver most commonly involved, diffuse granuloma formation
Dx: measurement of neutrophil superoxide production
DHR flow cytometry (preferred)
NBT testing
What are some catalase positive infections?
Staph Aureus
Burkholderia cepacia
Serratia marcesens
Nocardia
Aspergillus
Why is pancreatitis a major risk factor for ARDS?
Pancreatitis results in the release of a large amount of inflammatory cytokines and pancreatic enzymes into the circulation, leads to infiltration of neutrophils into the pulmonary interstium and alveolar spaces
diffuse injury to the alveolar epithelium and pulmonary micorvascular endothelium results in a leaky alveolar capillary membrane and signficiant pulmonary edema
ARDS is typically characterized by progressive hypoxemia refractory to oxygen therapy and diffuse interstitial edema in the absence of cardiogenic causes
first 1-6 days, alveoli become lined with waxy hyline memrbanes
What are the classic presentation of dermatomyositis?
What are 2 clinical signs associated with dermatomyositis?
Autoimmune
proximal muscle weakness and skin involvement including a violaceous discoloration of the upper eye lids (heliotrope rash) and raised violaceous scaling eruptions of the knuckes (Gottron’s sign)
CPK levels are typically elevated
Clinical pres of pertussis
What are the stages (3)
aka whopping cough aka 100 years cough!
Three phases
- catarrhal stage - URI type of infection
- Paroxysmal stage - severe coughing spells, with the classic whoop or post-tussive emesis (puke!)
- convalescent stage - cough improves
cxr could be unrevealing
no vaccination or adult with no recent booster
What mediates the cough reflex?
The internal laryngeal nerve (branch of superior laryngeal nerve CN X) mediates the afferent limb of the cough reflex above the vocal cords
this nerve contains only sensory info (in contrast to the external laryngeal and recurrent laryngeal) carries sensation from the mucosa superior to the vocal cords
**foreign bodies can become lodged in the piriform recess and may cause damage to the nerve, impairing the cough reflex
What nerves are involved in the gag reflex?
Afferent limb of the gag reflex is mediated predominately by glosopharyngeal nerve CN IX, while the efferent limb is carried by the vagus CN X
What fungus could produce allergic sensistivity to patients with asthma or CF?
What could be a consequence of recurrent sensitivites/reactions?
Aspergillus fumigatus -
asthmatics or pts with CF could develop an allergic hypersensitivty reaction to the fungus –> allergic bronchopulmonary aspergillosis ABPA, which occurs in 5-10% of corticosteroid-depedent asthmatics
Pts have high levesl of serum IgE, eosinophilia
and IgE + IgG serum antibodies to Aspergillus
intense airway inflammation and mucus plugging with exacerbations and remissions
repeated exacerbations may produce transient pulmonary infiltrates and proximal bronchiectasis
Two immunodeficiences could present with absent thymic shadow on CXR and recurrent infections?
What are the two and how can you distinguish between them?
Severe combiend immunodeficiency (SCID) and Thymic aplasia/DiGeorge sydrome
SCID - a T cell deficiencey –> B cell deficiency too
you get recurrent infections of all - viral, bacterial, fungal, protozoa
Failure to thrive
DIARREHA, THRUSH (yeast!)
DiGeorge* - *tetany due to LOW CALCIUM (absent thymus and parathroid) LOW PTH, LOW T cells
Reccurent infections - viral and fungal mostly
T cell deficiency
CONOTRUNCAL ABNORMALITIES (tetralogy of fallot, truncus arteriosus), craniofacial abnormalities
Sharp pain worse with inspiration could be due to what?
where cause this pain be refered to?
What nerves are involved?
phrenic nerve C3-C5, delivers motor innervation to the diphragm and carries pain fibers from the diphgramatic and mediastinal pleura
irritaiton of the PARIETAL pleura in either area will cause a sharp pain worsened by inspiration that will be referred to the C3-C5 distribution at the base of the neck and over the shoulder
[visceral pleura has no pain fibers]
What effect does a panic attack have on the arterial partial pressures?
Panic attack –> hyperventilation –> decreased arterial CO2
hyperventilation DOES NOT decrease the pO2 or the arterial oxygen content
Will produce respiratory alkalosis, increase pH and decreased pCO2
*Hypocapnia –> cerebral VASOCONSTRICTION!*
–> decreased cerebral blood flow = dizziness, weakness, blurred vision symptoms
What congential abnormality is highly associated with CF pt?
What are the symptoms?
What is a differential diagnosis?
Meconium ileus
meconium obstruction at level of ileum, inspissated with negative squirt sign
distended abdomen, refuse to eat, palpable interstinial loops, dark green emesis, air fluid levels and small bowel dilation in plain film
enema doesn’t relieve obstruction
Hirschsprung disease (lack of neuronal innervation - more associated with down’s syndrome, obstruction occuring at rectosgmoid post dilated colon/megacolon; normal meconium consistency and + squirt sign
What clinical triad is suggestive of a fat embolism syndrome?
ACUTE ONSET of neurologica abnormalities, hypoxemia, petechial rash in a pt with a severe long bone and or pelvic bone fractures
most commonly in the first 24-72 hours but can occur up to 2 weeks later
fat from bone marrow –> vascular sinusoids -> pulmonary microvessels
occlusion of microvessles impairs pulmonary gas exchagne and induces hypoxemia
free FA cause local toxic injury to the endotheium with the potential to cause ARDS
others escape via precapillary AV shunts that open due to increase pulmonary artery pressure –> CN, dermal capilaries, and sometimes thrombocytopenia due to platelet adhesion
Sudden upward jerking of the arm could cause injury to what nerves?
What clinical presentation could this have?
injury to the lower trunk of the brachial plexus - carries nerve fibers from C8 to T1, that contribute to the median and ulnar nerves
–> innervate all the intrinsic muslcs of the hand
Injury to the lower trunk of the brachial pelxus –> paralysis of all the intrinsic hand muscles = Klumpke’s palsy
relative sparing of the extrinsic flexors and extensors of the hand contributes to the total claw hand deformity
[lumbricals normally flex MCP joints and extend DIP and PIP]
What type of test could be used to rule out asthma?
why is this useful?
Methacholine challenge test
a cholinergic muscarinic agonist
assesses bronchial hyperactivity, a central pathophysiological feature of asthma. BHR can be quantified as teh concentration of an inhaled aerosolized bronchoconstrictive substance req to produce a 20% decline in FEVi
because this test has high sensitivity, used to exclude a diagnosis
SNout = sensistivty rules OUT
SPIN = specificit rules IN
What is a cross-over study?
Subejcts are randomly allocated to a sequence of 2 or more treatments given conesecutively - simplest model is a AB/BA type of study in which subjects allocated to teh AB study receive treatmetn A followed by treatment B, and viseversa in the BA arm
Crossover trials allow the patietns to serve as their own controls
DRAWBACK - teh effects of one treatment may “carry over” and alter the response to subsequent treatments/confounding effects; to limit this disadvantage, a washout (no treatment) period is often added between consecutive treatments. The washout period is designed to be long enough to allow the effects of prior treamtents to wear off
Clinical features of Turners syndrome
XO:
Short stature, broad chest
cystic hydromas (congenital lymphatic malformation) –> web neck
lymhadema in hands and feet
ovarian dysgenesis (abnl growth during embryonic growth and develeopment and premature ovarian failure/amenorrhea/premature menopause), streak gonads –> dec estrogen –> inc LH/FSH (due to lack of negative feedback)
Inc risk to develop dysgerminomas
BICUSPID aortic valves
PREductal coartation (intracardiac anomaly during development, leads to decrease blood flow through the left side of the heart –> hypoplastic development of the aorta)
Horseshoe kidneys
NL ovarian development during fetal life BUT lack of parental X during development, causes loss of ovarian follices by age 2 – 45X.
What is renal blood flow?
RBF = volume of blood that flows through the kidney per unit time
RBF - dependent on the pressure difference between teh renal artery and renal vein, as well as the resistance in the renal vasculature
tightly regulated, to keep RBF constant over a wide range of systemic blood pressures
RBF = [renal artery pressure - renal vein pressure] / renal vasulature pressure
RBF = PAH clearance / (1-hematocrit =plasma)
PAH clearance = (urine [PAH]Xurine flow rate) / plasma [PAH]
Tx for gonorrhea?
Third generation cephalosporin (ceftriaxone) + macrolide (azithromycin or doxyclicine - possible chlamydia co-infection)
Where does heme metabolism occur and what is the pathway?
Heme metabolism starts in in macrophages
via heme oxygenease –> biliverdin (giving a green color if in a bruise) –> + biliverdin reductase to bilirubin
Unconjugated bilirubin binds to albumin in the blood and is further removed by the liver, where it is conjugated by UDP-glucuronosyl-transferase/bilirubin glycuronyl transferase/UGT to conjugated bilirubi by glucoruonic acid and further moved in bile
What vitamin a overdoes could lead to intracranial hypertension, skin changes and hepatosplenomegal?
Vitamin A
Three stages: acute, chronic and teratogenic!
Acute - can occur after a single ingestion of a single high dose of vitam in A –> n/v, vomiting, vertigo and blurred vision
Chronic - alopecia, dry skin, hyperlipidemia, hepattoxici, hepatospleno, visual difficulties; papilledema when present, is suggestive of cerebral edema in the setting of benign intracranial hypertension(psedutumor cerebri)
Teratogenic effects — excessive vitamin A ingestion, include mcirocephaly, cardiac anomalies, fetal death (esp first trimeseter)
CN III exits where in the brain stem?
What arteries could affect this nereve? where would a deficit be localized to?
What eye is affected?
CN III / oculomotor carries general somatic efferent fiber and general visceral efferent paraysmpathteric fiber, exits the midbrain and courses between the posterior cerebral and superior cerebellar arteries
aneuryms arising from either artery can lead to a non-pupil sparing third nerve palsy, which presents with unilateral H/A, eye pain, diplopia, dilated nonreactive pupil and ptosis with teh IPSILATERAL eye in teh down and out psoition
The medication polyethylene glycool is used for what and is similar to what dz?
Constipation
similar to lactase deficiency
osmotic laxatives = non absorable/poorly absorable substances that attract water into the itnestinal lume, thus distending the intestinal wall and increasing peristalsis
rapid laxative effect
[magnesium hydroxide and other magnesium containing compounds such as magnesium citrate are other osmotic laxatives]
difference between osmotic and secretory diarrhea?
Osmotic is uusally due to an offending agent, and usually goes away when the agent is removed (ie - lactose); it is watery, and loose
Secretory, does not stop with feeding/does not stop with fasting, watery and loose and high in electroylte content (ie high in chloride and potassium!) high volume
what are example of dzs are associated with the following deficiencies?
T-cell dysfunction?
Deficient intraceullar killing?
Inability to form the MAC?
T-cell dysfunction? DiGeorges; thymic hypoplasia, recurrent viral and fungal infections
Deficient intraceullar killing? chronic granulomatous disease (increased infection with catalase POSITIVE, staph etc- inability of phagocytes to syntheseize NADPH oxidase, an enzyme essential to the lysosomal oxidative burst)
Inability to form the MAC? recurrent infections by Neisseria species
Coronary artery blood flow -
when does it occur?
what regulates it?
occurs during dyastole
During the zone of autoregulation, increases in coronary blood flow are primarily mediates by the relative myocardia hypoxia that occurs during times of increased work
increased myocardia oxygen requirements during exercise can only be achieved hrough corresponding increases in coronary blood flow since extraction of oxygen is already at a max
Nitric oxide and adenosine are the most important factors involved in coronary blood flow autoregulation
What is the most significant risk factor for UTI in a catherized patient?
the DURATION
preventative measures include: avoiding unncecessary catheterization, using sterile technique when inserting the cather and removing the catehrer promtply when no longer needed
Inferior MIs are associated with what type of HR change?
what medication is give and what is a some side effects?
Bradycardia, since usually inferior MIs are due to blockage of RCA, and thus the artery respoinsible for the SA and AV node perfusion
Atropine blocks vagal influence on the nodes, effective in increasing HR in patients
Atropine side effects are due to the muscarinic receptor blockade in other organs
in the eyes- mydriasis, results in narrowing of the anterior chamber angle and diminished outflow of aqueous humoer - precipiates angle-closure glaucoma in pt with shallow anteiror chambers or higher tha normal intraocular pressure; presents iwth unilateral severe eye pain and visual distubrances
what could prevent herpes reactivation?
recurrence of genital herpes can be reduces through daily treatment with oral valacyclovi, acyclovir or famciclovir.
C. tetani,
what is its mxn of pathogen?
what can protect us from it?
Tetanospasmin, is a protein extoxin produced by C. tetani that can travel by a RETROGRADE axonal transport into the CNS – heavy chain binds ganglioside receptors on neuronal membranes and the light chain inhibits release of glycine and GABA from inhibitory interneurons
–> absence of interneurons inhibitor NT = sustain muscle contration/tetanus
Prominent sx: masseter muscle spasms/lockjaw, opisthotonos, dyphagi and facial muscl spasm/risus sardonicus
tantanus is preventd by tetanus toxoid/formaldehyde-inactivates tetaus toxin vaccination– elicits HUMORAL immunity specific for TETANUS TOXIN and for prophylaxis after an injury if the wound is grossly contamintated = antitoxoin antibodies / active immunity
What could cause QT prolongation in a young individual, otherwise healthy?
Usually congenital
Jervell, lange-Nelsen Syndrome (cardio + sensorineural deafness)
Romano-ward syndrome (cardiac only)
QT inverval begins at QRS and ends at end of T wave, prolongcation reflects prolonged action potentional, determined in part by potassium currents though channel porteins, contributing to the delayed rectifier current Ik of the cardiac action potential
may predispose to torsades de pointes / ventricular tachyarrhythmia
What requirements must be bet for an RNA molecule purified from a virus to be infectious?
= on its own, must act as a mRNA capable of using the host’s intraceullar machinery for translation
= single-stranded POSITIVE sense virus
RNA SS negative strands require an RNA-depedent RNA polymerase
dsRNA - requires a specific viral RNA polymerase, present intact virion to gain entry into the host cell
what area of the eye is associated with the left temporal hemiretina?
how is this visual field processed? (what is the pathway?)
The left temporal hemiretina receives visual info from teh nasal visual field
Visual info then remains ipsilateral to that eye…transmitted via the left optic nerve to the lateral aspeic of the opti chiams, then joins the visual signals from the right nsal hemiretina, and travesl via the left optic tract to the left geniculate body in the thalamus, then travels via the ipsilateral optic radiations to the ipseilateral primary visual cortex for visual processing
What are symptoms associated with hydrocephalus?
What are potential complications?
macocepahly, poor feeding, muscle hypertonicity, hyperrefelxia (due to upper motor neuro injury cauesd by stretching of the periventricular pyramidal tracts!)
TX: surgical placement of a shunt to bypass teh obstruction most often iva teh ventriculoperitoneal route
Presentation of tertiary syphillis
cardiovascular involvement with gummas
gummas = necrotizing granulomas occuring on the skin, mucosa, subcutaneous tissue and bones or within other organs
[chancre is seen in primary syphillis; condylomata lata occuring during secondary syphillis]
neurosyphilis can occur at ANY STAGE (VDRL positive of CSF)
drug of choice for beta blocker overdose?
Beta blocker overdose –> diffuse non-selective blocakde of peripheral beta adrenergic receptors, causing depression of myocardial contractility, bradycardia and varying degress of AV block = low cardiac output stage
Glucagon, drug of choice for beta blocker overdose
acts of G protein coupled receptors, increasing intraceullar cAMP and thus increasing the release of intraceullar calcium druing muscle contraction
increasing heart rate and cardiac contractility
What type of injury does CCl4 produce?
CCL4 is oxidized by the P450 oxidase system in the liver
–> formation of the free radical CCl3 which reacts with structural lipids of cell membreanes –> lipid degradation and hydrogen peroxide formation = lipid peroxidation –> form new radicals,
cell injry due to CCl4 develops rapidly and leads to swelling of the ER, destruction of mitochondria and increased permeability of cell membranes = culminate in hepatocyte necrosis
Theophylline:
indication
overdose sx
overdose indication
Used to treat asthma and other lung dz
acute intoxication - n/v, abdominal pain, diarrhea, cardiac arrhythmias, seizures
Seizures are the major cause of morbidity and mortality in theophylline intox
tachyarrhythmias are the other major concern but usually donot cause QT prolongation
What type of reaction is associated with membraneous nephropathy?
Idiopathic membranous nephropathy is associated with circulating IgG4 antibodies to the phospholipase A2 receptor which might play a role in the development of the disease
What AA is only essential during times of growth?
Arginine
Time period of positive nitrogen balance
[recall arginine is also essential for NO production]
What are period of positive nitrogen balance?
= amt of nitrogen incorporated exceed the amount excreted and its associated with:
Growth
Pregnancy
recovery phase of injury or surgery
recovery from condition associated with negative nitrogen balance
what conditions are associated with negative nitrogen balance?
Neg nitrogen balance = nitrogen loss exceeds incorporation
Protein malnutrition (Kwashiorkor)
Dietary deficiency of even 1 essential amino acid
starvation
uncontrolled diabetes (increase protien breakdown needed for gluconeogenesis)
infection (break down of tissue and etc)
