UWorld Flashcards
Acid fast stain protocol
- First treated with aniline dye (eg carbolfuschin)
- Dye penetrates bacterial cell wall and binds mycolic acids
- Slide treated with HCl and alcohol
- Acid alcohol dissolves the outer cell membranes of nontuberculous bacteria but the presence of mycolic acids prevents decolorization of mycobacteria
Causes of polyhydramnios via impaired fetal swallowing
- Fetal gastrointestinal obstruction (esophageal, duodenal, or intestinal atresia)
- Anencephaly
Causes of polyhydramnios via increased fetal urination
- High fetal cardiac output (alloimmunization, parvovirus infection, fetomaternal hemorrhage)
Other causes of mild polyhydramnios
- Maternal diabetes
- Multiple gestations
Describe the immunologic response to Schistosoma
- TH2 mediated granulomatous response directed against the eggs that is composed of infiltrating TH@ cells, eosinophils, and M2 macrophages
- Leads to the development of marked fibrosis and ulceration and scarring of the bowel or bladder/ureters (depending on the species)
- Eggs that settle into the presinusoidal radicals of the portal vein can cause periportal “pipestem” fibrosis (pathognomonic for hepatic schistosomiasis)
Define positive likelihood ratio
A ratio representing the likelihood of having the disease given a positive result
Define negative likelihood ratio
A ratio representing the likelihood of having the disease given a negative result
Clinical features of panic disorder
Recurrent and unexpected panic attacks with >4 of the following
- Chest pain, palpitations, shortness of breath
- Trembling, sweating, nausea
- Dizziness, paraesthesias
- Derealization, depersonalization
- Fear of losing control, dying
Worry about additional attacks, avoidance behavior
Treatment of panic disorder
- IMMEDIATE: benzodiazepines
- LONG TERM: SSRI/SNRI and/or cognitive behavioral therapy
Most common cause of pneumonia in an HIV+ patient with normal CD4+ counts (400-1400 cells/uL)
Most common cause is S pneumoniae
Differentiation into TH1 requires
- IFN-gamma
- IL-12
TH1 cells secrete
- IFN-gamma
- IL-2
- Lymphotoxin beta
This induces the activation of macrophages and CD8+ T cells and mediates the delayed type of hypersensitivity
Differentiation into TH2 requires
IL-4
TH2 cells secrete
- IL-4
- IL-5
- IL-10
- IL-13
This initiates antibody response and regulates immunoglobulin class switching
Administration of what is indicated in patients with IL-12 receptor deficiency
IFN-gamma
Name the 3 dopaminergic systems
- Mesolimbic-mesocortical (functions to regulate behavior and is associated with schizophrenia)
- Nigrostriatal (function to coordinate voluntary movements and is associated with parkinsonism)
- Tuberoinfundibular (functions to control prolactin secretion and is associated with prolactinemia)
Describe the toxin released by Clostridium tetani
- Tetanospasm is a neuro-exotoxin
- Blocks the release of GLYCINE and GABA from the spinal inhibitory interneurons that regulate the lower motor neurons
- These disinhibited motor neurons cause increased activation of muscles, leading to spasms and hyperreflexia
What is increased in menopause
- FSH and LH
- FSH is the more reliable and earlier indicator
Osteoporosis involves which type of bone
- Trabecular/spongy (as opposed to cortical)
- Most prominent changes occur in dorsolumbar vertebral bodies, as vertebrae are predominately trabecular
- Neck of the femur is the second most common location of fractures
Describe a koilocyte
- Immature squamous cell with dense, irregularly staining cytoplasm and perinuclear clearing (resulting in a halo)
- Also has an enlarged pyknotic nucleus where the chromatin has condensed as a part of the apoptosis process, giving it a “raisinoid” appearance
Define pica
Compulsive consumption of a nonfood and/or non-staple food source for >1 month
Fever and sore throat in a patient with hyperthyroidism (Graves’ disease) treated with medical therapy should raise concern for
- Thionamide-induced agranulocytosis
- Therefore order a WBC count with differential to confirm diagnosis
- Can be caused by both methimazole and propylthiouracil
- Usually within first few months of therapy
- Patients typically have fever, sore throat, oral ulcerations or other signs of infection
Optimal site for femoral nerve block
- Inguinal crease (lateral border of the femoral a.)
- Injecting at this site anesthetizes the skin and muscles of the anterior thigh, femur and knee
- The block also anesthetizes the saphenous nerve (terminal extension of the femoral n.) to decrease sensation in the medial leg below the knee
Describe polyol pathway impairment
- Occurs in tissues that do not depend on insulin for glucose transport (lens, peripheral nerves, blood vessels and kidneys)
- Hyperglycemia results in increased intracellular glucose concentrations in these tissues
- Glucose undergoes conversion to SORBITOL by ALDOSE REDUCTASE
- Sorbitol is then converted to FRUCTOSE
- Sorbitol and fructose increase the osmotic pressure in tissues and stimulate the influx of water leading to osmotic cellular injury
- Leads to opacification of lens (cataracts) and peripheral neuropathy (osmotic injury of schwann cells)
Centers that regulate micturition reflex
- SACRAL MICTURITION CENTER - located S2-S4 level and responsible for bladder contraction; parasympathetic fibers travel from ventral white matter within pelvic nerve and stimulate cholinergic receptors in the bladder wall
- PONTINE MICTURITION CENTER - located in the pontine reticular formation; coordinates relaxation of external urethral sphincter with bladder contraction during voiding
- CEREBRAL CORTEX - inhibits sacral micturition center
Describe urinary incontinence in the context of NPH
- Expanded ventriculi place traction on cortical efferent and afferent fibers (corona radiata)
- This traction disrupts the periventricular pathways that transmit impulses from the cortex to the sacral micturition center
- Lack on inhibition from the cerebral cortex leads to frequent and uncontrolled micturition or urge incontinence
- The bladder fills with urine and empties reflexively when full
- The patient has no sensation of bladder fullness and no control over bladder function
- Voluntary relaxation of the urethral sphincter remains intact
Describe capitation
An arrangement in which a payor pays a fixed, predetermined fee to provide all the services required by the patient. Payors may negotiate a capitated contract with an insurance company that then pays the providers or a large medical group may negotiate directly with the payor
Describe discounted fee-for-service
A payment arrangement in which an insurer pays a provider for each individual service provided at a pre-arranged, discounted rate. Employers would not generally negotiate a fee-for-service contract directly with a provider.
Describe global payment
An arrangement in which an insurer pays a provider a single payment to cover all the expenses associated with an incident of care. This is most commonly done for elective surgeries, in which the global payment covers the surgery as well as any pre and post-operative visits needed.
Describe patient-centered medical home
A specific model of primary care in which patients have access to a personal physician who coordinates care and sees the patient through all aspects of care including preventive serves and acute and chronic disease management. Payment for these services may be capitated or fee-for-service.
Describe point-of-service plans
Require patients to have a primary care provider and obtain referrals for specialty consultations. They differ from health maintenance organizations (HMO) in that they allow patients to see providers outside of the the network, albeit at higher out-of-pocket costs (copays and deductibles)
Medications used for pregnancy termination
- Misoprostol (prostaglandin E1 agonist)
- Mifepristone (progesterone antagonist, glucocorticoid antagonist)
- Methotrexate (folic acid antagonist)
Morphologies of different transplant rejections
HYPERACUTE
- Gross and mottling with cyanosis
- Arterial fibrinoid necrosis and capillary thrombotic occlusion
ACUTE
- Humoral: CD4d deposition, neutrophilic infiltrate, necrotizing vasculitis
- Cellular: lymphocytic interstitial infiltrate and endotheliitis
CHRONIC
- Vascular wall thickening and luminal narrowing
- Interstitial fibrosis and parenchyma atrophy
Mechanism of thionamide drugs
- Methimazole and propylthiouracil
- Used to treat hyperthyroidism
- Inhibit thyroid peroxidase - the enzyme responsible for both iodine organification and coupling of iodotyrosines
- PTU also decreases peripheral conversion of T4 to the active hormone T3
Describe Mayer-Rokitansky-Kuster-Hauser syndrome/ vaginal agenesis
- 46 XX
- Mullerian aplasia
- Variable uterine development and no upper vagina (short vagina)
- Uterus is hypoplastic or absent - the patient cannot menstruate (eg primary amenorrhea)
- Have normal ovaries which secrete estrogen normally and enable regular development of secondary sexual characteristics (breasts, pubic hair, etc)
- 50% will have coexisting urologic anomaly (ie unilateral renal agenesis)
Difference between Mayer-Rokitansky-Kuster-Hauser syndrome/ vaginal agenesis and Androgen insensitivity syndrome
- 46 XY vs 46 XX
- Patients with AIS have minimal axillary or pubic hair due to androgen resistance
- Patients with AIS also have cryptorchid testes and no uterus or ovaries
Describe translocation down syndrome
- Less common
- Can be inherited from an unaffected parent with a balanced translocation
- Robertsonian translocations occur between 2 acrocentric, nonhomologous chromosomes
- Resultant translocated chromosomes are the fusion of 2 long arms
- Affected parent is asymptomatic because they have a normal (albeit rearranged) genetic complement
Describe stress related urinary incontinence
- Loss of urethral support and intraabdominal pressure exceeds urethral sphincter pressure
- Leaking with coughing, sneezing, laughing and lifting
Describe urge related urinary incontinence
- Detrusor overactivity
- Sudden, overwhelming or frequent need to empty bladder
Describe overflow related urinary incontinence
- Impaired detrusor contractility, bladder outlet obstruction
- Constant involuntary dribbling of urine and incomplete emptying
When is pulmonary vascular resistance lowest
- Functional residual capacity
- Increased lung volumes increase PVR due to the longitudinal stretching of alveolar capillaries by expanding alveoli
- Decreased long volumes also increase PVR due to decreased radial traction from adjacent tissues on the large extra-alveolar vessels
Acute salicylate intoxication
- Salicylate intoxication causes 2 different acid-base abnormalities SIMULTANEOUSLY
RESPIRATORY ALKALOSIS:
- 1st disturbance to occur, as salicylates directly stimulate the medullary respiratory center
- Resulting increase in ventilation leads to increased loss of CO2 in the expired air
- Usually only see primary respiratory alkalosis by itself in under 3 hours from ingestion time
ANION GAP METABOLIC ACIDOSIS:
- Begins to develop shortly afterward, as high concentrations of salicylates increase lipolysis, uncouple OXPHOS and inhibit the TCA cycle
- Results in accumulation of organic acids in the blood (eg ketoacids, lactate and pyruvate)
Fracture of the neck of the fibula yields
Injury of common peroneal nerve due to its superficial location as it courses laterally around the neck of the fibula
- Causes LOSS OF DORSAL FOOT SENSATION (not loss of sensation over sole of foot) as well as IMPAIRED DORSIFLEXION and EVERSION RESULTING IN FOOT DROP
Pulsatile release of GnRH from hypothalamus stimulates
Secretion of LH from anterior pituitary and in the case of males leads to increased testosterone production
Constant GnRH activity causes
Down-regulation of GnRH receptors on pituitary gonadotrophin cells, which suppresses LH secretion
Such is the mechanism of long acting GnRH agonists (eg leuprolide)
Mechanism of action of flutamide
- Nonsteroid agent
- Competitive testosterone receptor inhibitor
- Prevention of androgen-receptor binding blocks the stimulatory effect of androgens on primary tumor and metastases and leads to reduction in their size (improving symptoms such as bone pain and urinary obstruction)
Phosphorylase kinase regulation in liver vs muscle
- Glycogen stored in liver is used to maintain blood glucose levels during the fasting state, whereas glycogen in the muscles is used to provide energy for muscle contraction
- PK-liver activated primarily through binding of epinephrine and glucagon to Gs receptors which increase cAMP and cause phosphorylation of PK to make it active
- Skeletal muscle lacks glucagon receptors but PK-muscle can still be phosphorylated in response to epinephrine
- However, INCREASED Ca2+ is a MORE POWERFUL STIMULATOR OF PK-MUSCLE
- Release of SR Ca2+ following neuromuscular ACh stimulation allows for synchronization of skeletal muscle contraction and glycogen breakdown
Assessment of decision making capacity
- Communicates a choice
- Understands information provided
- Appreciates consequences
- Rationale given for decision
Primary carnitine deficiency
- Deficiency of Acyl CoA synthase
- Muscle weakness
- Cardiomyopathy
- Hypoketotic hypoglycemia (after a significant/long fast)
- Elevated muscle triglycerides
Medium chain acyl CoA dehydrogenase (MCAD) deficiency
- Deficiency of Acyl CoA dehydrogenase located in the mitochondrion
- Hypoglycemia
- Hypoketotic hypoglycemia (after a significant/long fast)
- Most commonly deficient enzyme in beta oxidation disorders
Sun exposure catalyzes the conversion of 7-dehydrocholesterol to what in the skin
Cholecalciferol (vitamin D3)
Fractures to the orbital floor can result in
- Generally result from direct frontal trauma to the orbit
- Infraorbital nerve runs along the orbital floor in a groove in the maxilla before exiting the skull just inferior to the orbit
- Damage can result in paresthesia of the upper cheek, upper lip and upper gingiva
- The inferior rectus muscle can also become entrapped, limiting superior gaze
Describe noise induced hearing loss
- Results from trauma to the stereociliated hair cells of the organ of Corti
- The acoustic reflex normally dampens the effects of loud noise by causing the stapedius and tensor tympani muscles to contract, which lessens the responsiveness of the ossicles to sound
- However, prolonged noise exposure can cause distortion or fracture the sterocilia due to shearing forces against the tectorial membrane
- HIGH FREQUENCY hearing is lost FIRST, REGARDLESS of the frequency of the sounding causing the damage
Describes the steps of transduction of mechanical sound waves into nerve impulses occurs in the organ of Corti
- Sound reaches the middle ear by vibrating the tympanic membrane
- The vibration is transferred to the oval window by the ossicles
- Vibration of the oval window causes vibration of the basilar membrane, which in turn causes bending of the hair cilia against the tectorial membrane
- Hair cell bending causes oscillating hyperpolarization and depolarization of the auditory nerve, thereby creating nerve impulses from sound
Mechanism of action of thiazolidinediones
- Exert their glucose lowering effect by improving insulin sensitivity
- Bind to PPAR-gamma causing it form a heterodimer complex with the retinoid X receptor
- This complex then binds to the transcriptional regulatory sequences of various genes responsible for glucose and lipid metabolism, altering their expression
- One of the most important genes regulated by PPAR-gamma is one that codes for ADIPONECTIN (cytokine secreted by fat tissue that enhances insulin sensitivity and fatty acid oxidation)
- Adiponetin levels are low in obese patients and those with T2DM
- Treatment with thiazolidinediones increases adiponectin levels, improving insulin sensitivity
Describe melanocytic nevi
JUNCTIONAL NEVI
- Characterized by aggregates of nevus cells along the dermoepidermal junction
- Typically appear as flat black-to-brown pigmented macules with darker coloration in the center than the periphery and preserved skin markings
COMPOUND NEVI
- Form as aggregates of nevus cells that EXTEND INTO DERMIS
- Raised papules with uniform brown to tan pigmentation
- Has both dermal and epidermal involvement
INTRADERMAL NEVI
- Considered to be older lesions in which the epidermal nests of nevus cells have been lost
- Remaining dermal nevus cells lose tyrosinase acitivity and produce little to no pigment
- Skin to tan colored, dome-shaped and sometimes pedunculated
Most common cause of coronary sinus dilation
- Elevated right sided heart pressure secondary to pulmonary hypertension because it communicates freely with the right atrium
- Also occurs in patients with anomalous venous drainage into the CS, including persistent left SVC and total anomalous pulmonary venous return
Inherited hyperlipoproteinemias
- Familial chylomicronemia syndrome
- Familial hypercholesterolemia
- Familial dysbetalipoproteinemia
- Familial hypertriglyceridemia
Familial chylomicronemia syndrome
- Inherited hyperlipoproteinemia
- Protein defect: lipoprotein lipase and Apo-CII
- Elevated chylomicrons
- MANIFESTATIONS: ACUTE PANCREATITIS, lipemia retinalis, eruptive skin xanthomas, hepatosplenomegaly
Familial hypercholesterolemia
- Inherited hyperlipoproteinemia
- Protein defect: LDL receptor and ApoB-100
- Elevated LDL
- MANIFESTATIONS: PREMATURE CORONARY ARTERY DISEASE, corneal arcus, tendon xanthomas, xanthelasmas
Familial dysbetalipoproteinemia
- Inherited hyperlipoproteinemia
- Protein defect: ApoE
- Elevated chylomicrons and VLDL remnants
- MANIFESTATIONS: PREMATURE CORONARY ARTERY DISEASE AND PERIPHERAL VASCULAR DISEASE, tuboeruptive and palmar xanthomas
Familial hypertriglyceridemia
- Inherited hyperlipoproteinemia
- Protein defect: ApoA-V
- Elevated VLDL
- MANIFESTATIONS: increased pancreatitis risk, associated with obesity and insulin resistance
Hepatitis that appears finely granular, homogenous with dull eosinophilic inclusions that fill the cytoplasm (ground glass hepatocytes)
Hepatitis B
Hepatitis that shows lymphoid aggregates within the portal tracts and focal areas of macrovesicular steatosis
Hepatitis C
Homogenous eosinophilic inclusions that fill the cytoplasm are much more specific for hepatitis B
Aortic arch derivatives
FIRST: part of maxillary artery
SECOND: hyoid artery and stapedial artery
THIRD: common carotid artery and proximal internal carotid artery
FOURTH: aortic arch (left) and proximal subclavian artery (right)
SIXTH: proximal pulmonary arteries and ductus arteriosus (left)
Thiamine (B1) participates in glucose metabolism and is a cofactor for the following:
- PYRUVATE DEHYDROGENASE, which converts pyruvate (glycolysis end product) into acetyl CoA (enters the TCA cycle)
- ALPHA-KETOGLUTARATE DEHYDROGENASE, an enzyme in the TCA cycle
- Branched chain ALPHA-KETOACID DEHYDROGENASE, which is essential for catabolism of branched chain amino acids (leucine, isoleucine, valine)
- TRANSKETOLASE, an enzyme in the pentose phosphate pathway that helps convert ribulose 5-phosphate (derived from glucose) to glycolysis intermediates (eg glyceraldehyde 3-phosphate)
Most significant risk factor for UTI via catheterization
Duration of catheterization
Responsible for clinical variability of mitochondrial diseases
Heteroplasmy
Mitochondrial syndromes
- LEBER HEREDITARY OPTIC NEUROPATHY leads to bilateral vision loss
- MYOCLONIC EPILEPSY WITH RAGGED-RED FIBERS: myoclonic seizures and myopathy associated with exercise; skeletal muscle biopsy shows irregularly shaped muscle fibers (ragged red fibers)
- MITOCHONDRIAL ENCEPHALOMYOPATHY with lactic acidosis and stroke-like episodes (MELAS)
Concentration increases as fluid runs along proximal tubule
- PAH
- Creatinine
- Inulin
- Urea
Concentration decreases as fluid runs along proximal tubule
- Bicarbonate
- Glucose
- Amino acids
Penetrating injury above the clavicle and between the midclavicular and lateral sternal lines injures
Lung pleura
- Lung apices extend above the level of the clavicle and first rib through the superior thoracic aperture
- Penetrating injury in this area may lead to pneumothorax, tension pneuthorax, or hemothorax
Homeobox genes
- Highly conserved DNA sequence that is usually 180 nucleotides
- Typically code for TRANSCRIPTION FACTORS
- Mutations of these genes interrupt developmental processes often resulting in severe abnormalities such as skeletal malformations and improperly positioned limbs and appendages
- Play an important role in the segmental organization of the embryo along the cranio-caudal axis
Type A adverse drug reaction
Predictable reaction due to known pharmacologic properties of the drug
- Gastritis associated with NSAID use
- Nephrotoxicity due to aminoglycosides
Type B adverse drug reaction
EXAGGERATED SENSITIVITY: predictable reaction occurring at lower than expected exposure (eg tinnitus after single aspirin dose)
IDIOSYNCRATIC: unpredictable reaction in certain patients (eg nonimmune hemolytic anemia with primaquine in G6PD deficiency)
IMMUNOLOGIC (DRUG ALLERGY): unpredictable, specific immunologic reaction (eg rapid utricaria or anaphylaxis, drug induced hemolysis, serum sickness, contact dermatitis)
Endoneural inflammation is associated with
Guillan-Barre syndrome
Endomysial inflammation is associated with
Polymyositis
Treatment of delirium
- Low dose antipsychotics (eg haloperidol)
- May manifest as acute changes in cognition and behavior
- Benzodiazepines can worsen confusional states, particularly in the elderly - only use for treatment of delirium due to alcohol or benzodiazepine withdrawal
Desmopressin used to treat
- Mild hemophilia A and vWF disease (increases circulating factor VIII and endothelial secretion of vWF to stop bleeding)
- Central diabetes insipidus and nocturnal enuresis (binds to V2 receptors in renal tubular cells, leading to increased aquaporin channels, increased water reabsorption and decreased urine output)
Failure to acidify lysosomes of antigen presenting cells would lead to deficient expression of
MHC Class II bound to foreign antigen and subsequent lack of interaction between APCs and T cells
Cholecystectomy patients absorb dietary lipids from
Jejunum
Low HDL concentration is associated with increased cardiovascular risk, however the use of medications to raise HDLs…
Does NOT improve cardiovascular outcomes!
Statins are the most effective lipid-lowering drugs for primary and secondary prevention of cardiovascular events, regardless of baseline lipid levels
Diagnosis of lactose intolerance
Hydrogen breath test
Diagnosis of Celiac disease
- Increased tissue transglutaminase IgA
- Increased endomysial antibodies
- Duodenal biopsy showing increased intraepithelial lymphocytes and flattened villi
Treatment of mild hypoglycemia
- Manifests as anxiety, tremor, and sweating
- Self-treatment with oral intake of 15-30g of fast acting carbohydrates
Treatment of severe hypoglycemia
- Manifests as confusion, loss of consciousness and seizures
- Treat with intramuscular glucagon or IV dextrose
Treatment of treatment-resistant schizophrenia
Clozapine
Cause of dynamic left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy
Due to abnormal systolic anterior motion of the anterior leaflet of the mitral valve toward a hypertrophied interventricular septum
Clinical findings of Wilson’s disease
- Hepatic (acute liver failure, chronic hepatitis, cirrhosis)
- Neurologic (parkinsonism, gait disturbance, dysarthria)
- Psychiatric (depression, personality changes)
- Kayser-Fleischer rings (can be observed with a slit lamp!)
Traumatic aortic rupture
- Most often caused by the rapid deceleration that occurs in motor vehicle collisions
- Most common site is the AORTIC ISTHMUS, which is tethered by the ligamentum arteriosum and is relatively fixed and immobile compared to the adjacent descending aorta
Helicase
Unwinds double helix
Topoisomerase II
- DNA gyrase
- Removal of supercoils
Single-stranded DNA-binding protein
Stabilization of unwound template strands
Primase
- RNA polymerase
- Synthesis of RNA primer
DNA Polymerase III
5’ to 3’ DNA synthesis and 3’ to 5’ exonuclease (“proofreading”) activity
DNA Polymerase I
5’ to 3’ DNA synthesis and 3’ to 5’ exonuclease (“proofreading”) activity
Also removes RNA primer (5’ to 3’ exonuclease activity) and replaces it with DNA
DNA ligase
Joining of Okazaki fragments on lagging strand
Most highly oxygenated blood of fetal circulation
Umbilical vein, which empties directly into the inferior vena cava via the ductus venosus
What makes up the pelvic floor
Levator ani muscles (ilococcygenous, pubococcygeus, puborectalis) hold the bladder and the urethra in the appropriate anatomic position. Injury to these muscles results in urethral hypermobility and/or pelvic organ prolapse (eg cystocele)
Action of human placental lactogen (hPL)
Decreases maternal fatty acid stores and increases maternal serum glucose in order to provide adequate glucose in the growing fetus. The actions of hPL results in physiologic insulin resistance in the latter half of pregnancy. Gestational diabetes occurs when maternal insulin secretion is inadequate.
Describe hemorrhoids
Results from distention of one of several arteriovenous plexuses (anal cushions), which are composed of vascular tissue, smooth muscle and connective tissue. The venous component of internal hemorrhoids drain into the middle and superior rectal veins, which communicate with the internal iliac and inferior mesenteric veins, respectively.
Describe normal morphological changes in the aging heart
- Decrease in left ventricular chamber apex-to-base dimension
- Development of a sigmoid shaped ventricular septum
- Myocardial atrophy with increased collagen deposition
- Accumulation of cytoplasmic lipofuscin pigment within cardiomyocytes
Vascular endothelium secretes what to inhibit platelet aggregation
Prostacyclin (PGI2) is produced from prostaglandin H2 by prostacyclin synthase in vascular endothelial cells. When secreted, it vasodilates, inhibits platelet aggregation and increases vascular permeability. The functions of prostacyclin oppose those of thromboxane A2. These substances work in concert to ensure vascular homeostasis.
What change is responsible for maintaining CO in the setting of aortic regurgitation
Regurgitant blood flow from the aorta into the left ventricle in chronic aortic regurgitation leads to an increase in left-ventricular EDV and wall stress, with resultant eccentric hypertrophy. The gradual increase in left ventricular chamber size increases total stroke volume and helps maintain CO. Not increase in HR.
Common sources of arsenic
Insecticides and contaminated water
Causes of pure red cell aplasia
Rare form of marrow failure characterized by severe hypoplasia of marrow erythroid elements in the setting of normal granulopoiesis and thrombopoiesis. Pure red cell aplasia is associated with THYMOMA, LYPHOCYTIC LEUKEMIAS and PARVOVIRUS B19 INFECTION.
Adhesion of cells to the extracellular matrix involves
Integrin-mediated binding to fibronectin, collagen and laminin. Differential expression of integrin subtypes affects adhesion properties of individual cells and has been found to correlate with malignant behavior in a number of tumors.
What is bosentan
A competitive antagonist of endothelin used for treatment of idiopathic pulmonary arterial hypertension
Describe systemic mastocytosis
- Clonal mast cell proliferation that occurs in the bone marrow, skin and other organs
- Mast cell proliferation often is associated with mutations in the KIT receptor tyrosine kinase
- These cells are characterized by prominent expression of mast cell tryptase
- Excessive histamine release from degranulation of mast cells mediates many of the symptoms of the disease such as syncope, flushing, hypotension, pruritis, and utricaria
- Histamine also induces gastric acid secretion, which can lead to gastric ulceration
- Excess acid also inactivates pancreatic and intestinal enzymes, causing diarrhea
- Other gastrointestinal symptoms include nasusea, vomiting, and abdominal cramps
Predominant lymphocyte found in sarcoid granulomas
CD4+ T cells. Intraalveolar and interstitial accumulation of CD4+ T cells in sarcoidosis often results in high CD4+/CD8+ T cell ratios in bronchoalveolar lavage fluid.
What amino acid becomes essential in PKU
Tyrosine, as PKU results from an inability to convert phenyalanine to tyrosine by the phenyalanine hydroxylase system. Classical clinical features of untreated PKU include intellectual disability, seizures, light pigmentation, and a “musty” body odor.
Most important risk factors for aortic dissection and aortic aneurysm
Hypertension is the single most important risk factor for the development of intimal tears leading to aortic dissection
High cholesterol is a risk for atherosclerosis, which predisposes more to aortic aneurysm formtaion
Young, asymptomatic patient with a soft systolic ejection murmur at the right 2nd intercostal space most likely has
Bicuspid aortic valve
What determines the ventricular contraction rate in atrial fibrillation
Atrioventricular node refractory period
AF is initated by aberrant electrical impulses that arise within regions of heightened atrial excitability (most often the pulmonary veins). Once triggered, AF lead to electrical remodeling of the atria with the development of shortened refractory periods and increased conductivitiy. This facilitates the creation and persistence of multiple ectopic foci and re-entrant impulses within the atria, increasing the risk and chronicity of subsequent episodes.
Ventricular response in AF is dependent on the transmission of the abnormal atrial impulses through the AV node. Each time the AV node is excited, it enters a refractory period during which additional impulses cannot be transmitted to the ventricles, consequently, the majority of atrial impulses never reach the ventricles. The average ventricular rate in AF ranges between 90-170 bpm. Because atrial excitation is chaotic, the ventricular rate is irregular with no set intervals between contractions.
What type of channel is defective in cystic fibrosis
A transmembrane ATP-gated chloride channel
Signs of a patella fracture
- Most commonly due to impact to the anterior aspect of the knee
- Acute swollen knee
- Focal patella tenderness
- Inability to extend the knee against gravity
- Palpable gap in the extensor mechanism
Acute intermittent porphyria
- Acute attacks are due to the accumulation of aminolevulinate and porphobilinogen resulting from an inherited PBG deaminase deficiency combined with ALA synthase induction
- Typically due to certain medications, alcohol use, or a low calorie diet
- Managed with glucose or hemin (inhibits ALA synthase activity)
- Presents with neurologic symptoms (eg tingling, difficulty concentrating) and recurrent episodes of nonspecific abdominal pain
Direct injury to what will causes central diabetes inspidus
Damage to the hypothalamic nuclei will cause permanent central diabetes insipidus whereas injury to the posterior pituitary or infundibulum can cause TRANSIET DI because axonal regneration and hypertrophy will allow adequate ADH to be released into circulation
Describe Hirschsprung disease pathogenesis
Hirschsprung disease is a result of abnormal migration of neural crest cells during embryogenesis. These cells are the precursors of ganglion cells of intestinal wall plexi. Since neural crest cells migrate caudally, the rectum is ALWAYS affected in Hirschsprung disease.
Penicillin resistance mechanisms
- Beta lactamase, ESBL
- Mutated PBP
- Mutated porin protein
Vancomycin resistance mechanisms
- Mutated peptidoglycan cell wall
- Impaired influx/ increased efflux
Quinolones resistance mechanisms
- Mutated DNA gyrase
- Impaired influx/ increased efflux
Aminoglycosides resistance mechanisms
- Aminoglycoside-modifying enzymes
- Mutated ribosomal subunit protein
- Mutated porin protein
Tetracycline resistance mechanisms
- Impaired influx/ increased efflux
- Inactivated enzyme
Rifamycin resistance mechanisms
- Mutated RNA polymerase
Major cause of morbidity and mortality from theophylline intoxication
Seizures. Tachyarrhythmias are another major concerns. Treat with activated charcoal to reduce GI absorption. BEta blockers are the drugs of choice for tachyarrhythmias. Seizures are difficult to treat, but benzodiazepines and barbiturates are the most effective agents.
Exposure to high temperature or exercise in cystic fibrosis patients can lead to
Hyponatremia due to excessive sodium loss through sweat, therefore salt supplementation is recommended.
Standard heart failure therapy
- Beta blocker, ACE inhibitor, mineralocorticoid receptor antagonist (spironolactone)
- Mineralocoritcoid receptor antagonists block the deleterious effects of aldosterone on the heart, causing regression of myocardial fibrosis and improvement in ventricular remodeling; also reduce morbidity and improve survival in patients with congestive heart failure and decreased ejection fraction; should not be used in patients with hyperkalemia or renal failure
Stress related mucosal disease
- Caused by local ischemia in the setting of severe physiologic stress (eg shock, extensive burns, sepsis, severe trauma)
- Ulcers arising in the setting of severe trauma/burns are called Curling’s ulcers
- Ulcers arising from intracranial injury are caused by direct VAGAL stimuation and are called Cushing’s ulcers
Difference between CMV and HSV1 associated HIV esophagitis
HSV1 presents with small vesicles and punched out ulcers and on microscopy presents with eosinophilic intranuclear inclusions (Cowdry type A) in multinuclear squamous cells at ulcer margins.
CMV presents with LINEAR ulcerations and on microscopy has intranuclear and cytoplasmic inclusions.
Essential tremor
- Most commonly diagnosed movement disorder
- Often AD inheritance
- Worsens while maintaining a particular posture (eg when holding an object)
- Commonly reported to improve with alcohol consumption
- First line of treatment is nonspecific beta adrenergic antagonist (propanolol)
Bloom syndrome
- AR
- Short stature
- Generalized chromosomal instability caused by deficient DNA repair enzymes
- Increased susceptibility to neoplasms
Cause of hypospadias
- Incomplete fusion of the urethral (urogenital) folds
- Results in an abnormal opening of the urethra proximal to the glans penis along the ventral shaft of the penis
Infusion of glucose in a patient with thiamine deficiency
Precipitates encephalopathy (Wernicke). This is because thiamine is a cofactor of the enzymes responsible for glucose metabolism and will therefore exacerbate the pre-existing thiamine deficiency.
Where are the most and least concentrated fluid of the nephron located
- Most concentrated: collecting ducts
- Least concentrated: thick ascending limb of the loop and distal convulted tubule
Rubber like properties of elastin are due to what
Extensive cross linking between elastin monomers, which is facilitated by lysyl oxidase.
Tolerance to what side effects of opioid do not develop
Constipation of constipation and miosis. Tolerance is developed to analgesic effects as well as most other side effects. To prevent bowel complications, it is recommended that patients be treated prophylatically with adequate fluid intake and daily laxatives.
Opsoclonus-myoclonus syndrome
- Non-rhythmic conjugate eye movements associated with myoclonus
- Associated with neuroblastoma, most common extracranial childhood cancer
COPD can cause hypoxia sufficient enough to stimulate production of what by cortical cells of the kidney
Erythropoietin by cortical cells of the kidney
Mutation of huntingtin protein causes transcriptional repression of a number of other genes, what is its mechanism of doing so
Histone deacetylation. Prevents transcription of certain genes that code for neurotrophic factors, contributing to neuronal cell death.
Peau d’orange
- Erythematous, itchy breast rash with skin texture changes analogous to an orange peel
- This is the key dermatologic presention of INFLAMMATORY BREAST CANCER and is caused by cancerous cells obstructing lymphatic drainage due to spread of the dermal lymphatic spaces
Chronic rejection of lung transplantation affects what structure
Immune reaction mainly affects the small airways, causing BRONCHIOLITIS OBLITERANS syndrome. Symptoms include dyspnea and wheezing.
Histological appearance of dermatitis herpetiformis
Characterized by microabcesses containing fibrin and neutrophils at the dermal papillae tips. The overlying basal cells become vacuolated, and coalescing blisters for at the tips of the involved papillae.
Organ susceptibility to infarction after occlusion of a feeding artery from greatest to least
CNS > myocardium > kidney > spleen > liver
Dual supply is typically sufficient to sustain liver parenchyma, notable exception is when a transplanted liver undergoes hepatic artery thrombosis.
Hepatic encephalopathy
- Caused by increased levels of ammonia and other neurotoxins in the circulation that lead to increased inhibitory neurotransmission and impaired excitatory neurotransmitter release
- Frequently precipitated by a stressor that alters the ammonia balance (eg gastrointestinal bleeding, increased dietary protein)
Direct arteriorlar vasodilators
Lower blood pressure BUT trigger reflex sympathetic activation and stimulate the renin-angiotensin-aldosterone axis. This results in tachycardia and edema. To counteract such compensatory effects these agents are often given in combination with sympatholytics and diuretics.
What makes P vivax and P ovale different from P falciparum
They also establish a latent hepatic infection (exo-erythrocytic cycle) in the form of hynozoites, responsible for relapses. Primaquine is used to eliminate in this intrahepatic stage.
Treatment of anovulation
Menotropin (human menopausal gonadotropin) is a treatment option that acts like FSH surge (just prior to LH surge) and triggers the formation of a dominant ovarian follicle. Ovulation is then induced by administration of human chorionic gonadotropin, which mimics the LH surge.
Enteropeptidase deficiency
The jejunal brush border enzyme enteropeptidase activates trypsin from its inactive precursor, trypsinogen. Trypsin degrades complex polypeptides to dipeptides, tripeptides, and amino acids while activating other pancreatic enzymes. Enteropeptidase deficiency impairs both protein and fat absorption, leading to diarrhea, failure to thrive and hypoproteinemia.
Placental aromatase deficiency
Aromatase converts androgens into estrogens in the ovaries, testes, placenta, and other peripheral tissues. Placental aromatase deficiency causes accumulation of androgens during pregnancy, resulting in ambiguous external genitalia in female infants and maternal virilization.
Differentiate Niemann-Pick disease and Tay-Sachs disease
Hepatosplenomegaly is absent in Tay-Sachs disease
Dihydropyridines vs nondihydropyridines
Dihydropyridines (eg nifedipine, amlodipine) primarily affect peripheral arteries and cause vasodilation. Nondihydropyridines (eg verapamil, diltiazem) affect the myocardium and can cause bradycardia and slowed AV conduction.
How do inhalation anesthetics affect various organ systems
CARDIOVASCULAR EFFECTS: include myocardial depression that leads to a decrease in CO and increase in atrial and ventricular pressures. Hypotension associated with fluorinated anesthetics is a result of decrease in CO.
RESPIRATORY: all inhalation anesthetics, except NO, are respiratory depressants. They decrease tidal volume and minute ventilation and cause hypercapnia. Another undesirable effect is the suppression of mucociliary clearance, which may predispose to postoperative atelectasis. Halothane and sevoflurane have bronchodilation properties and are preferred in patients with asthma.
BRAIN: fluorinated anesthetics decrease vascular resistance and lead to an increase in cerebral blood flow. It is an undesirable effet as it results in increased intracranial pressure.
KIDNEY: inhaled anesthetic decrease glomerular filtration rate, increase renal vascular resistance and decrease renal plasma flow
LIVER: fluorinated anesthetics decrease hepatic blood flow
Testicular torsion
Due to twisting of the testis around the spermatic cord (containing the gonadal artery) which can eventually lead to ischemia. The gonadal artery arises from the abdominal aorta.
Classical conditioning
Involves a neutral stimulus being repeatedly paired with a non-neutral stimulus that elicits a reflexive, unconditioned response. Over time, the formerly neutral stimulus is able to evoke a conditioned response by itself in absence of the non-neutral stimulus.
Tabes dorsalis
Occurs due to degeneration of the dorsal columns and dorsal roots of the spinal cord. Loss of propioception and vibration senses, ataxia and Argyll Robertsons pupils may be seen.
Describe acanthosis nigricans as it relates to type II diabetes
The early course of TIIDM is characterized by increased insulin production and decreased sensitivity of target organs to the effects of insulin, although insulin levels may later decline as the disease progresses. Acanthosis nigricans is a sign of insulin resistance. Insulin resistance in adipose cells hinders the antilipolytic effects of insulin, leading to lipolysis and release of free fatty acids. In turn, chronically elevated free fatty acid levels contribute to insulin resistance by impairing insulin-dependent uptake in liver and muscle and increasing hepatic gluconeogenesis. Other factors that contribute to insulin resistance include obesity and a sedentary lifestyle.
Intestinal atresia distal to the duodenum
Occurs due to vascular accidents in utero. “Apple-peel” atresia occurs when the superior mesenteric artery is obstructed. The result is a blind-ending proximal jejunum; a length of absent bowel and mesentery; and, finally, a terminal ileum spiraled around an ileocolic vessel.
Right sided varicocele
Suggests renal vein thrombosis, a well-known complication of nephrotic syndrome. Nephrotic syndrome is a hypercoaguable state. Loss of anticoagulant factors, especially antithrombin III, is responsible for the thrombotic and thromboembolic complications of nephrotic syndrome.
Insulin receptor
- Tetrameric structure consisting of 2 alpha and 2 beta subunits
- Alpha subunits are extracellular and provide the binding site for insulin
- Beta subunits are intracellular and contain tyrosine kinase domains that are activated when insulin attaches to the alpha subunits
- A series of downstream signaling is then triggered, staring with the autophosphorylation of IR, phosphorylation of IR substrates 1 and 2 and ultimately translocation of GLUT-4 to the cell membrane
How does TNF-alpha induce insulin resistance
- TNF-alpha is a proinflammatory cytokine that induces insulin resistance through activation of serine kinases, which then phosphorylate serine residues on the beta subunits of IR and IRS-1
- This inhibits tyrosine phosphorylation of IRS-1 by IR and subsequently hinders downstream signaling, resulting in resistance to the normal actions of insulin
- Phosphorylation of threonine residues has similar effects
- Catecholamines, glucocorticoids and glucagon can also induce insulin resistance by this same mechanism
Congenital long QT syndrome
- Most often caused by genetic mutations in a K+ channel protein that contributes to the outward-rectifying potassium current
- A decrease in the outward K+ current leads to prolongation of the action potential duration and QT interval
- This prolongation predisposes to the development of life-threatening ventricular arrhythmias (eg torsades de pointes) that can cause palpitations, syncope, seizures, or sudden cardiac death
When do VSDs become audible
Around ages 4-10 days when pulmonary vascular resistance declines, enabling left to right shunting
Progressively weakening diaphragmatic contractions during maximal voluntary ventilation with intact phrenic nerve stimulation indicate
Neuromuscular junction pathology (eg myasthenia gravis) and/or abnormally rapid diaphragmatic muscle fatigue (eg restrictive lung or chest wall disease)
Clinical findings of tabes dorsalis
- Sensory ataxia
- Lancinating pains
- Neurogenic urinary incontinence
- Associated with Argyll Robertson pupils (manifest with a light-near dissociation and are caused by damaged to the midbrain tectum)
Acute neuronal injury (red neuron)
- Transient severe insult that leads to cell death
- Shrinkage of the cell body
- Pyknosis of the nucleus
- Loss of the Nissl substance
- Eosinophilic cytoplasm
- Characteristic changes become 12-24 hours after the injurious event
Axonal reaction
- Loss of axon
- Enlargement of the cell body
- Eccentric nucleus
- Enlargement of the nucleolus
- Dispersion of the Nissl substance
Neuronal atrophy
- Progressive degenerative disease
- Loss of neurons and functional groups of neurons
- Reactive gliosis
Increase in pulmonary capillary wedge pressure is associated with
Mitral stenosis. Pulmonary capillary wedge pressure reflect left atrial and left ventricular end-diastolic pressure. Mitral stenosis leads to an increase in the LA pressure that is reflected as elevated PCWP during pulmonary artery cauterization. Left ventricular filling may be normal, resulting in an increased pressure gradient between the LA and LV during diastole.
Blood supply of different parts of the ureter
- Proximal ureter receives its blood supply from the renal artery whereas the distal ureter is supplied by the superior vesical artery
- Circulation to the middle portions of the ureter is variable and anastomotic
Kidney lies deep to which rib
The kidney lies immediately deep to the tip of the 12th rib
How do cleft lip and palate occur
- Cleft lip results when the maxillary prominence fails to fuse with the intermaxillary segment during the 5th-6th week of embryonic development
- Cleft palate occurs when the palatine shelves fail to fuse with one another or with the primary palate
- Cleft lip and palate can occur together or in isolation
Describe normal lip and palate formation
- Occurs during the 5th-6th week of embryonic development through a series of fusions
- The 1st pharyngeal arch splits into the upper maxillary prominence and the lower mandibular prominence
- Fusion of the 2 medial nasal prominences forms the midline intermaxillary segment. The intermaxillary segment will become the philtrum of the upper lip, the 4 medial maxillary teeth and the primary palate.
- The left and right maxillary prominences then fuse with the midline intermaxillary segment to form the upper lip and the primary palate. If one of the maxillary prominences fails to fuse with the intermaxillary segment, a unilateral cleft lip results. If both maxillary prominences fail to fuse with the intermaxillary segment, bilateral cleft lip results.
Describe micrognathia
- Characterized by hypoplasia of the mandibular prominence
- In the Pierre-Robin sequence, the severe micrognathia results in posterior displacement of the tongue (glossoptosis) and prevents fusion of the secondary palate (cleft palate)
Most important cytokine in mediating sepsis
TNF-alpha
Somatostatin decreases the production of which gastrointestinal hormones
- VIP
- Gastrin
- Glucagon
- Cholecystokinin
Clinical features of cystic fibrosis vs primary ciliary dyskinesia
PRIMARY CILIARY DYSKINESIA:
- Chronic sinopulmonary infections
- Bronchiectasis
- Situs inversus (50% of cases)
- Infertility due to immotile spermatozoa
CYSTIC FIBROSIS:
- Chronic sinopulmonary infections
- Bronchiectasis
- Pancreatic insufficiency
- Infertility due to ABSENT vas deferens bilaterally (azoospermia)
Diagnosis of cystic fibrosis vs primary ciliary dyskinesia
PRIMARY CILIARY DYSKINESIA:
- Low nasal nitric oxide levels
- Bronchoscopy and electron microscopic visualization of ciliary abnormalities
- Genetic testing
CYSTIC FIBROSIS:
- Elevated sweat chloride levels
- Abnormal nasal transepithelial potential difference
- Genetic testing
How is primary tuberculosis infection controlled
Throught he action of CD4+ TH1 lymphocytes and macrophages. These cells work together to contain M. tuberculosis within a caseous granuloma, which offers the macrophages inside an opportunity to kill the remaining organisms if the necrotic area is small enough.
What is a common presentation of choriocarcinoma
Dyspnea/hemoptysis due to pulmonary metastasis from hematogenous spread
Most likely cause of a repetitive, widened pulse pressure together with an unusually large LV stroke volume and heart murmur
Aortic regurgitation. Wide pulse pressure is responsible for many of the symptoms and signs of AR, such as head bobbing.
McCune-Albright syndrome
Characterized by the triad of fibrous dysplasia (scar like tissue forms in the place of normal bone) of the bone, endocrine abnormalities and cafe-au-lait spots. Results from an activating mutation in the G protein/CAMP/adenylate cyclase signaling pathway.
Legg-Calve-Perthes disease
Disease of young children that results in isolated idiopathic osteonecrosis of the hip.
Which coagulation factor has the shortest half-life
Factor VII
Failure of prothrombin time to correct with vitamin K supplementatin indicates
Liver disease, reflecting factor VII deficiency (has the shortest half-life of the coagulation factors)
What is coagulation factor IV
Calcium. It is required for coagulation factors to bind to phospholipid.
How does mannitol cause pulmonary edema
- Mannitol is an osmotic diuretic that works by increasing plasma or tubular fluid osmolality
- Increased plasma and fluid osmolality causes extraction of water from the interstitial space into the vascular space or tubular lumen, with subsequent diuresis
- In the brain, water redistribution from the tissues into the plasma helps reduce edema and intracranial pressure in the setting of cerebral edema
- One of the more severe toxicities of agressive osmotic diuretics is pulmonary edema
What is the rate limiting step in acyclovir activation
Phosphorylation of acyclovir to acyclovir monophosphate via virally-encoded thymidine kinase
Why does acyclovir work for HSV and VZV infections but not CMV or EBV
EBV and CMV do not produce the same thymidine kinase as HSV and VZV. As a result they are not able to be easily converted acyclovir to its pharmacologically active form.
How does tertiary syphilis begin
Tertiary syphilis begins with vasa vasorum endarteritis and obliteration, resulting in inflammation, ischemia, and weakening of the adventitia. Aneurysmal dilation of the thoracic aorta results and can extend to involve the aortic valve ring.
Who does medicaid cover
Medicaid is a federal socialized medical insurance program that covers individuals age 65 and older who have a work history and younger individuals with disabilites
Wallerian degeneration
- Refers to the process that occurs when an axon is damaged, resulting in axonal degeneration and breakdown of the myelin sheath distal to the site of injury
- Degeneration of the axon usually begins withing a few days after lesion onset
Wallerian degneration in the PNS
- Schwann cells sense the axonal degeneration and begin to degrade their myelin and secrete cytokines and chemokines that recruit macrophages
- This allows of effective clearance of myelin debris which, along with trophic factor secretion by Schwann cells, stimulates formation of a growth cone from the stump of the proximal axon and facilitates nerve regeneration
Wallerian degeneration in the CNS
- Phagocytic macrophages/microglia are recruited more slowly because of the blood-brain barrier
- Myelin-producing oligodendrocytes also become inactive or undergo apoptosis and do not assist with phagocytosis
- This slows removal of the myelin debris, which can persist for year in the degenerating tracts and suppress axonal growth via myelin-associated inhibitory factors
- Astrocytes also release inhibitory molecules and proliferate in the weeks to months following injury, forming a glial scar that acts as a barrier to axon regeneration
Vaginal dryness, low bone density, and hypogonadism are very common manifestations of
Prolactin induced low levels of estrogen
Germ tube test
- Diagnostic of Candida albicans
- Allows it to be distinguished from other members of the Candida family (such as C tropicalis and C glabrata
How does excess copper cause injury
Excess copper causes injury by binding to sulfhydryl groups of cellular proteins. D-penicillamine contains a free sulhydryl group and functions as a copper chelator.
Visualization of post-streptococcal glomerulonephritis
Deposits can be visualized as electron-dense subepithelial “humps” on electron microscopy and as granular depositions within the mesangium and glomerular capillary walls on IgG and C3 immunofluorescence
Where does positive selection of T cells occur
Thymic cortex
Where does negative selection of T cells occur
Thymic medulla
Pulmonary abscesses
- Local suppurative collections within lung parenchyma that result in necrosis of the surrounding lung tissue
- If the abscess cavity communicates with an air passage, the semiliquid exudate within will partially drain, creating an air-containing cavity that can be identified on chest radiograph
- Tissue damage and resultant abscess formation is primarily caused by lysosomal enzyme release from neutrophils and macrophages
Relationship between GFR and serum creatinine
- When the GFR is normal, relatively large decreases in GFR result in only small increases in serum creatinine
- When GFR is significantly decreased, small decrements in GFR produce relatively large changes in serum creatinine
- Rule of thumb: every time GFR halves, serum creatinine doubles
Clinical features of TCA overdose
CNS:
- Mental status changes (eg drowsiness, delirium, coma)
- Seizures, respiratory depression
CARDIOVASCULAR:
- Sinus tachycardia, hypotension
- Prolonged PR/QRS/QT intervals
- Arrhythmias (eg ventricular tachycardia, fibrillation)
ANTICHOLINERGIC:
- Dry mouth, blurred vision, dilated pupils
- Urinary retention, flushing, hyperthermia
How to treat cardiac abnormalities associated with TCA overdose
- TCAs result in blockage of fast sodium channels and has deleterious effects on the cardiac conduction system, causing QRS and QT prolongation and cardiac dysrhythmias
- Widened QRS interval or ventricular arrhythmias are an indication for SODIUM BICARBONATE therapy
- Sodium bicarbonate increases serum pH, which favors the non-ionized (neutral) form of the drug, making it less accessible to bind to sodium channels
- Also increases extracellular sodium concentration, which helps overcome the competitive, rapid sodium channel blockage induced by TCAs
Nonbacterial thrombotic endocarditis
- Form of noninfectious endocarditis characterized by deposition of sterile platelet thrombi on cardiac valves
- Commonly associated with advanced malignancy and can also occur with chronic inflammatory disorders (eg antiphospholipid syndrome, SLE) and sepsis
Presentation of acute hepatitis B
Serum-sickness like syndrome with joint pain, lymphadenopathy, and pruritic utricarial rash. Other features may include right upper quadrant pain, hepatomegaly, and elevated hepatic transaminase levels.
Presentation of stimulant intoxication
Stimulation intoxication can present with paranoid ideation and must be differentiated with primary psychiatric disorders. Physical signs of stimulant intoxication include tachycardia, hypertension, hyperthermia, diaphoresis, and mydriasis
Vibrio cholerae and Enterotoxigenic E coli
- Do not invade the mucosa or cause enterocyte death
- Toxins secreted by these organisms modify electrolyte handling by enterocytes but do not cause cell death
- Therefore, no erythrocytes or leukocytes are typically noted on stool microscopy
Functional hypothalamic amenorrhea
- Underlying pathophysiology of FHA is incompletely understood but appears to involved reduced circulating leptin levels as a result of diminished adipose tissue stores
- The decrease in leptin levels inhibits pulsatile GnRH release from the hypothalamus, causing decreased pituitary LH and FSH secretion, low circulating estrogen levels, and amenorrhea
Where is H pylori found in relation to ulcers
- Endoscopic biopsy can show organisms in the actual ulcers up to 30% of the time
- Appears to colonize mainly the antrum of the stomach in the prepyloric area (where there are few acid-secretory parietal cells)
- Colonization of the gastric antrum by H pylori is associated with increased gastric acid secretion and the duodenal bulb is the area most exposed to this increase in acid prodution
How to prevent gynecomastia in a patient being treated for prostate cancer with GnRH agonists
- Conditions that cause an increased estrogen to androgen ratio may lead to gynecomastia, which is characterized histopathologically by ductal epithelial hyperplasia surrounded by dense stromal fibrosis
- Acinar development is driven primarily by progesterone and is not usually seen
- The selective estrogen receptor modulator TAMOXIFEN inhibits the effects of estrogen on breast tissue and is effective for prevention and treatment of gynecomastia in patients on androgen deprivation therapy (ADT)
Neonatal complications of diabetes during pregnancy
- Premature delivery
- Fetal macrosomia (big baby)
- Congenital malformations (neural tube defects, cardiovascular abnormalities, caudal regression syndrome)
- Respiratory distress
- Transient hypoglycemia
- Polycythemia and hyperviscosity
Caudal regression syndrome
- Congenital abnormal development of fetal lower spine (sacral area)
- Associated with gestational diabetes
Role of vitamin E
- Primarily serves to protect fatty acids from oxidation
- Predisposes cell membranes to oxidative injury
- The cells that are most susceptible include neurons with long axons (due to large membrane surface areas) and erythrocytes (due to high oxygen exposure)
- Most common clinical manifestations of vitamin E deficiency are NEUROMUSCULAR DISEASE (eg skeletal myopathy, spinocerebellar ataxia, polyneuropathy) and HEMOLYTIC ANEMIA
What causes the formation of a tracheoesophageal fistula with esophageal atresia
- Tracheoesophageal fistula with esophageal atresia results from failure of the primitive foregut to appropriately divide into separate trachea and esophageal structures
- Infants present shortly after birth with excessive secretions and choking/cyanosis during feeds
- Diagnosis can be confirmed by x-ray after the inability to pass a nasogastric tube into the stomach
Common site of metastasis for clear cell carcinoma (a type of renal cell carcinoma)
- Lungs
- Composed of large, rounded or polygonal cells with clear cytoplasm
- Rarely presents with triad of hematuria, flank pain, and palpable mass
- Non-specific symptoms and paraneoplastic syndromes are more common
- Often detected incidentally at an advanced stage
Where is the greatest amount of airway resistance found
- Regional airway resistance within the first 10 generations of bronchi contributes to most of the total airway resistance of the lower respiratory tract
- Resistance is maximal in the 2nd to 5th generation airways, including segmental bronchi
How does chronic alcoholic pancreatitis cause epigastric calcifications
- Thought that alcohol-related chronic pancreatitis develops in part due to alcohol-induced secretion of protein-rich fluid
- These proteinaceous secretions can precipitate within the pancreatic ducts, forming ductal plugs that may calcify and be detectable on abdominal imaging
- Ductal obstruction by such concretions may cause exocrine insufficiency due to atrophy of the pancreatic acinar cells and pancreatic fibrosis
- Pancreatic insufficiency leads to malabsorption with consequent diarrhea/steatorrhea
- Weight loss and bulky, frothy stools are typical clinical findings
What is the cause of direct hernias
Caused by weakness of the transversalis fascia in Hesselbalch’s triangle and is most common in older men
Very long chain fatty acid oxidation
- Very long chain and some branched chain fatty acids cannot undergo mitochondrial beta oxidation
- These fatty acids are metabolized by a special form of beta oxidation (very long chain fatty acids) or by alpha oxidation (branched chain fatty acids such as phytanic acid) within peroxisomes
- When peroxisomes are absent or nonfunctional, these fatty acids accumulate within the tissues
- ZELLWEGER SYNDROME: peroxisomal disease; infants are unable to properly form myelin in the CNS; hypotonia, seizures, mental retardation, early death
- REFSUM DISEASE: defect in peroxisomal alpha oxidation and leads to neurologic disturbances in response to accumulation of phytanic acid within the body; treat with strict avoidance of chlorophyll in diet
Patients who have undergone a total gastrectomy require lifelong
- Vitamin B12 supplementation due to inability to produce IF
- Pepsin and HCl are helpful, but are not required, for protein digestion and patients can still digest protein after gastrectomy due to presence of pancreatic and intestinal proteases
What is used to treat serotonin syndrome
- Cyproheptadine: an antihistamine with anti-serotonergic properties (nonspecific 5-HT1 and 2 receptor antagonistic properties)
- Supportive care, hydration and temperature maintenance
Clinical presentation of rheumatoid arthritis
- Pain, swelling and morning stiffness in multiple joints
- Small joins (PIP, MCP, MTP); spares DIP joints
- Sytemic symptoms (fever, weight loss, anemia)
- Cervical spine involvement: subluxatin, cord compression
