5/19 UWORLD TEST 1

Question 1

Osteosarcoma

Answer 1

Bone tumor most often associated with Paget’s disease
Arising in femur, tibia, humerus, other bones
Destruction of normal trabecular bone pattern, mixed radiodense and radiolucent areas, periosteal new bone formation, lifting of the cortex, Codman’s triangle
Adjacent soft tissue usually demonstrates ossification in a “sunburst” pattern

Question 2

Acetylcholine like muscarinic agonists

Answer 2

Cause smooth muscle contraction
Potentiated by physostigmine
Inhibited by atropine

Question 3

Germline mosaicism

Answer 3

Presence of multiple, genetically different gamete cell lines
Should be considered when a genetic mutation is identified in the offspring but not in the parents

Note* somatic mutations cannot be passed on to offspring!!

Question 4

Interleukin-2

Answer 4

Is exclusively produced by T lymphocytes and functions to stimulate the growth and differentiation of T cells, B cells, NK cells, and macrophages

Question 5

Molluscum contagiosum

Answer 5

Characterized by umbilicated, flesh colored papules on the skin and mucous membranes
It is caused by a poxvirus, which appears in pathologic specimens as eosinophilic cytoplasmic inclusions (molluscum bodies)

Question 6

Anterior and posterior dislocations at the knee joint

Answer 6

Injury to the popliteal artery is the primary concern
This vessel is rigidly fixed proximal and distal to the knee joint by the adductor magnus and soleus muscles, respectively

Question 7

Sublimation

Answer 7

A mature defense mechanism in which a person channels unacceptable thoughts or impulses into socially acceptable behavior

Question 8

Heminephrectomy

Answer 8

Results in compensatory hyperfiltration and hypertrophy of the nephrons in the remaining kidney.
Post-nephrectomy, the total GFR increases from 50% to approximately 80% of its original value within several weeks

Question 9

Acute intermittent porphyria

Answer 9

Deficiency of porphobilinogen deaminase
Intermittent episodes of abdominal pain with neurological manifestations following exposure to an offending medication
Urine from patient during attacks will classically darken when exposed to sunlight
Skin photosensitivity is characteristically absent

Question 10

Metabolic derangements associated with DKA

Answer 10

Metabolic acidosis, ketonemia, hyperglycemia, hyperkalemia, hyponatremia
Hyperammonemia can also be observed due to muscle degradation

Question 11

Complete androgen insensitivity syndrome

Answer 11

Rare, x-linked disorder
“Testicular feminization”
46, XY karyotype with a female phenotype
Mutated testosterone receptors throughout the body that are resistant to androgens
Serum testosterone are in normal range for males, LH is high, FSH is normal
Peripherally converted to estradiol, results in breast development
Vagina ends abruptly in a blind pouch (Mullerian structures are absent) with external female genetalia

Question 12

Intraventricular hemorrhage

Answer 12

AKA germinal matrix hemorrhage (in utero)

Due to germinal matrix fragility

Question 13

Amiodarone-induced interstitial pneumonitis

Answer 13

Slowly progressive dyspnea, fever, cough, patchy interstitial infiltration on radiograph > inflammation and fibrosis in the pulmonary interstitium
Usually reversible with a reduction in dose or discontinuation of the drug

Question 14

Misoprostol

Answer 14

PGE1 analog
Binds to plasma membrane prsotaglandin receptors
In the upper GI tract, misoprostol stimulates gastric epithelial cell mucus production and appears to decrease parietal cell acid secretion

Question 15

Head and neck cancers

Answer 15

Vast majority are squamous cell carcinomas
Strongly associated with the use of tobacco and alcohol
Tend to develop in the oral cavity- ventral tongue, floor of mouth, lower lip, soft palate, gingiva = MC sites of origin
Often infiltrates adjacent tissue, may eventually metastasize locally to cervical lymph nodes or distally to mediastinal lymph nodes, lungs, liver, bones

Question 16

Albright hereditary osteodystrophy

Answer 16

Pseudohypoparathyroidism

Short stature, and short metacarpal and metatarsal bones

Question 17

Allelic heterogeneity

Answer 17

Different mutations at the same genetic locus cause similar phenotypes
Ex. three different mutations can cause B-thalassemia

Note:
Genetic heterogeneity=mutations of different genes cause similar phenotypes
Phenotypic heterogeneity= mutations in the same gene result in markedly different phenotypes

Question 18

Hemochromatosis

Answer 18

AR disease
Excessive GI absorption of iron
Common manifestations: liver disease with hepatomegaly, diabetes mellitus secondary to pancreatic islet destruction, arthropathy, pituitary hormone deficiencies, hyperpigmentation, cardiomyopathy
Manifests > 40 years

Question 19

Cirrhosis

Answer 19

Causes portal HTN due to distortion of the hepatic vascular bed; the increased pressures in the portal venous system can cause splenic vein hypertension and splenomegaly

Question 20

Achondroplasia

Answer 20

Gain of function point mutation of the fibroblast growth factor receptor 3 (FGFR3) gene
Presents with proximal limb (humeral/femoral) shortening, midface hypoplasia, frontal bossing, macrocephaly, shortened digits with a space between the 3rd and 4th digits

Question 21

Proteins destined for the RER possess

Answer 21

Hydrophobic, N-terminal peptide signal sequences that identify the as such
Removal of these sequences would cause inappropriate protein accumulation in the cytosol

Question 22

Maple syrup urine disease

Answer 22

Defect in the branched chain alpha-keto acid dehydrogenase complex, which is responsible for the catabolism of the branched chain alpha-amino acids leucine, valine, and isoleucine
This enzyme complex requires thiamine (B1) as a coenzyme

Question 23

Alpha-thalassemia

Answer 23

Classic peripheral smear of hypochromic, microcytic cells
Offspring are at risk for absent alpha globin production- the most severe form of alpha thalassemia, which leads to hemoglobin Barts accumulation and death in utero from hydrops fetalis (anasarca, ascites, effusions)

Question 24

Androgen-binding protein (ABP)

Answer 24

Synthesized in the Sertoli cells of the seminiferous epithelium and secreted into the seminiferous tubule lumen
ABP maintains the high local concentration of testosterone necessary for normal sperm production and maturation

Question 25

Hyperhidrosis

Answer 25

Excessive sweating due to sympathetic hyperacitvity
Sympathetic postganglionic cholinergic neurons innervate eccrine and apocrine sweat glands
Rx: systemic anticholinergic meds (oxybutynin), local anticholinergic injectable meds (botulinum toxin), surgical sympathectomy (for axilla = ablation of thoracic sympathetic trunk)

Question 26

Red safranin O stain

Answer 26

Stain cartilage, mast cell granules, and mucin red

Question 27

Cartilage on histology

Answer 27

Presence of cells surrounded by a glassy matrix of ground substance and collagen
Predominant collagen found in hyaline cartilage is type II collagen

Question 28

Idiopathic pulmonary arterial hypertension (IPAH)

Answer 28

Increased pulmonary artery pressure and right ventricular failure
Starts with injury to the pulmonary endothelium secondary to an idiopathic mechanism or a known medical condition (cardiac defects, collagen vascular disease, PE)

Question 29

Ischemic colitis

Answer 29

Common cause of lower GI hemorrhage in eldely
Crampy abd pain, tenderness to palpation, bloody stool
Weak lower extremity pulses indicate extensive atherosclerosis
Histology: mucosal hemorrhage, ecchymoses, patchy necrosis, eventually leading to thickening of bowel, edema. Transmural infarction can result bowel perforation

Question 30

Ras

Answer 30

GTP binding, signal-transducing oncoprotein

Question 31

Treatment for carcinoid tumor

Answer 31

Octreotide

Somatostatin analog that functions by inhibiting the release of bioactive peptides by the carcinoid tumor

Question 32

Protein synthesis during apoptosis

Answer 32

Internal ribosome entry is an alternative method used by apoptotic cells whereby a distinct nucleotide sequence allows translation to begin in the middle of mRNA

Question 33

Thiazolidinediones (pioglitazone, rosiglitazone)

Answer 33

Peroxisome proliferator-activated receptor Y (PPAR-y) agonists that increase transcription of insulin-responsive genes.
Thiazolidinediones exert their glucose lowering effects by decreasing insulin resistance

Question 34

Crohn disease

Answer 34

Chronic, idiopathic, inflammatory condition
Most frequently involves the TERMINAL ILEUM
Abdominal pain, diarrhea, low-grade fever, aphthous ulcers, of the mouth and perianal disease (fissures, abscesses)

Question 35

Cimetidine effects on Warfarin

Answer 35

Slows the metabolism of warfarin, resulting in a gradual increase of the prothrombin time over a period of several days

Question 36

Hepatic encephalopathy Rx

Answer 36

Lactulose acidifies the contents of the GI tract, converting NH3 into NH4+

Question 37

Osteomalacia

Answer 37

Decreased mineralization of newly deposited osteoid
Presents with bone pain, muscle weakness, increased fracture risk
Most often caused by Vit D deficiency and the resulting hypophosphatemia

Question 38

Atherosclerotic plaques

Answer 38

Eccentric intimal thickening with a fibrous cap, smooth muscle proliferation, local inflammatory infiltrate, and a lipid filled core
Exertional leg pain, dermal atrophy, arterial ulcers

Question 39

Li-Fraumeni syndrome

Answer 39

AD, early onset malignancies (breast cancer, bone and soft tissue sarcomas, adrenocortical carcinoma, brain tumors)
Single germline mutation in p53 tumor suppressor gene (present in every cell in patient’s body)
A second hit leads to unchecked proliferation of mutated cells and carcinogenesis

Question 40

Coccidioides immitis

Answer 40

Dimorphic soil fungus endemic to San Joaquin Valley, southwest United States, Mexico, and South America.
It most commonly causes asymptomatic infection or mild pneumonia
Rarely it may cause formation of a thin walled cavity in the lung leading to hemoptysis in addition to fever and cough
Rash and symmetric arthralgias

Question 41

Intellectualization

Answer 41

Use of excessive thinking to avoid painful emotions or fears; particularly common in patients recently diagnosed with serious medical illnesses

Question 42

Atrial septal defect

Answer 42

Widely split and fixed S2

Question 43

Less common symptoms of anemia

Answer 43

Glossal pain, dry mouth, atrophy of the tongue papillae, alopecia, pagophagia

Question 44

Reactive arthritis

Answer 44

Acute oligoarthritis of the appendicular skeleton, often with conjunctivitis and urethritis
Caused by deposition of immune complexes, usually from genitourinary or GI infection
CANT SEE, CANT PEE, CANT CLIMB A TREE

Question 45

Prader-Willi Syndrome

Answer 45

Neonatal hypotonia, extremem hyperphagia, progressive obesity, hypogonadism, small hands and feet
Microdeletions involving the paternal chromosome 15q11-13 or maternal uniparental disomy

Question 46

PCOS

Answer 46

Elevated ovarian androgen levels (testosterone) stimulate development of small ovarian follicles and prevent the formation of a single dominant follicle
Leads of ovulatory dysfunction and the characteristic polycystic pathology of polycystic ovary syndrome

Question 47

Pernicious anemia

Answer 47

Autoimmune destruction of gastric mucosa
Production of gastric acid is diminished, leading to compensatory increase in gastrin release
Secretion of gastric intrinsic factor is also lost, leading to Vitamin B12 deficiency

Question 48

Varicoceles

Answer 48

Dilations of the spermatic vein pampiniform plexus that enlarge with standing and regress with lying down
Patients may be asymptomatic or experience aching pain relieved with recumbency, testicular atrophy, or reduced fertility
Does not transilluminate light

Question 49

Leuprolide

Answer 49

Continuous administration of GnRH analog inhibits secretion of FSH and LH
In patients with prostate cancer, this decreases testosterone production and can slow progression of the disease

Question 50

DiGeorge Syndrome

Answer 50

Facial abnormalities, thymic and parathyroid aplasia, cardiac and great vessel defects. Maldevelopment of the truncus arteriosus is common in utero, resulting in persistent truncus arteriosis, tetralogy of Fallot, or interrupted aortic arch

Question 51

Gaucher disease

Answer 51

Most common lysosomal storage disease
B-glucocerebrosidase deficiency, and glucocerebroside accumulation
Hepatosplenomegaly, pancytopenia, skeletal destruction, which can lead to severe bone pain and avascular necrosis

Question 52

Transformation

Answer 52

Process by which bacteria take up naked DNA from their environment and incorporate it into their genomes

(DNase degrades naked DNA in the culture media, preventing transformation)

Question 53

Homeobox (HOX) genes

Answer 53

Encode transcription factors that guide the pattern of embryo development along the rostro-caudal, limb and genital axes
Mutations in HOXA13 can cause hand-foot-genital syndrome, a rare dominantly inherited syndrome marked by distal limb defects including hypoplastic first digits and genitourinary malformations