Block 33

Question 1

Structures arising from neural crest cells

Answer 1

Motel PASS
Melanocytes
Odontoblasts
Tracheal cartilage
Entrochromaffin cells 
Laryngeal cartilage
Parafollicular thyroid cells
Adrenal medulla 
Schwann cells
Spiral membrane

Question 2

Lumacaftor and ivacaftor

Answer 2

• CFTR modulating medications that can potentially help patients with CF by restoring CFTR proteins to the membrane and also by enhancing protein function at the membrane, respectively.
• the combination of these 2 medications in patients with homozygous F508 mutation has been shown to improve predicted forced expiratory volume and decrease rates of pulmonary exacerbations.

Question 3

Thalasemia

Answer 3

• hereditary hemolytic anemia resulting from defective synthesis of globin chains
• it pts with thalassemia the synthesis of either alpha or beta are defective.
• if only one gene is defective the patient will have beta thalassemia trait (beta thalassemia minor) and lack significant anemia.
• a defect in both beta globin gene results in severe hemolytic anemia known as beta thalasemia major.
• in this disease alpha chain are produced normally but they cant form stable tetramers due to the lack of beta globin chains.
• this failure to form stable hemoglobin leads to precipitation of alpha globin chains and premature lysis of RBC.

Question 4

Hormone sensitive lipase

Answer 4

• Enzyme found in adipose tissue that catalyzes the mobilization of stored triglycerides into free fatty acids and glycerol.
• HSL is inhibited by insulin, and activated by stress hormone such as glucagon.
• the stress hormone stimulate Gs protein coupled receptors on adipocytes, leading to increased cAMP production and activation of protein kinase A —> lipolysis.
• FFA and glycerol released into circulation can be taken up by the liver where the glycerol is used primarily as a carbon source for gluconeogenesis.

Question 5

Obstructive sleep apnea —> secondary polycythemia

Answer 5

-peritubular cells in the renal cortex sense hypoxia and respond by releasing erythropoietin into the bloodstream.

Question 6

Renininoma

Answer 6

Renin secreting tumor, rare , small solitary, benign juxtaglomelular cell neoplasm. They should be strongely considered in patients with marked hyperreninemia and hypertension who doesnt have renovascular disease.

Question 7

PPAR-y role in treating D.M II

Answer 7

• it binds to RXR—> PPAR-¥/RXR complex —>
• it increases FA uptake, increase adipnectin production , decrease TNF-å and decrease leptin production.
• Its role is useful in decreasing insulin resistance without increasing insulin levels.

Question 8

Uncontrolled severe asthma treatment

Answer 8

• severe asthma is defined as having symptoms throughout the day, nighttame symptoms daily, symptoms with limited activity, frequent exacerbation requiring steroids and evidence of decreased lung function on pulmonary function test.
• many asthmatics have allergies as a-trigger due to high IgE response
• anti IgE antibodies given as a subcutaneous injection (omalizumab) have been shown to be effective in moderate to severe asthma.
• this is given usually if the pts doesnt respond well to steroids and beta agonists

Question 9

Appendectomy - surgical landmarks

Answer 9

Teniae coli can be used as a surgical landmark to the appendix.

Question 10

Base excision repair

Answer 10

Its responsible for repairing various non-bulky DNA base alteration, including depurination, alkylation, oxidation, and deamination.

• excessive consumption of dietary nitrites (eg sodium nitrite), can lead to cytosine, adenine, and guanine deamination to form uracil, hypoxanthine and xanthine.
• if these abnormal bases arent removed and replaced with the correct base, DNA mutation may occur.
• BASE excision repair begins with recognition of abnormal bases by “glycosylases”, these cleave the altred DNA bases from the parent DNA molecule, leaving an empty site called AP site.
• and endonuclease then cleaves the 5’ end of the AP site, before a “layase” (phosphodiesterase) enzyme complete extraction of the AP site from the DNA molecule by removing the remaining sugar phosphate group.
• DNA polyemerase then fills the gap with the correct sugar phosphate base and final nick is sealed by “ligase”

Question 11

Prepatellar brusitis

Answer 11

“Housmaid knee”

• acute pain and localized tendreness associated with repetitive anterior knee trauma from kneeling is typical.
• its located between patella and the overlying skin. Other occupations associated with prepatellar and infrapatellar bursitis include carpet laters, mechanics and plumbers.

Question 12

Q fever

Answer 12

• human infection usually occurs through inhalation of bacteria from air contaminated by animal waste
• it has acute and chronic stages
• acute Q fever manifest as febrile illness, fever lasting >10 days, fatigue and myalgia.
• severe debilitating headaches which are often retrorbital and associated with photophobia are a frequent symptom.
• pneumonia is one of the primary signs of acute Q fever and the most common X-ray abnormality is lobar consolidation.
• leukocytes count is often normal. Other classic lab findings are increased liver enzymes and thrombocytopenia.
• chronic Q fever which is fatal if not treated and manifests as infective endocarditis in pts with valvular disease.

Question 13

SSSS

Answer 13

• its most common in infants and young children, usually not fatal unless skin lesions become secondarily infected.
• exfoliative toxins show exquisite pathalogic specificity in blistering only the superficial epidermis. They act as proteases and cleaves desmoglein in desmosomes.
• bullous impetigo is more localized form of SSSS with the bulla formation being another effect

Question 14

Theophylline intoxication

Answer 14

• its metabolized predominantly by hepatic cytochrome oxidases.
• inhibition of these enzymes by concurrent illness or other drugs (eg, cimitidne, ciprofloxacin, macrolides, verapamil, ketoconazole…) can raise serum concentration and cause theophylline toxicity.
• theophylline is a phosphodiesterase inhibitor that is sometimes used as alternate therapy for asthma.
• toxicity present as excessive CNS stimulation, GI distubances, and cardiovascular abnormalities.

Question 15

Spondyloarthritis is associated with

Answer 15

• pts with these disease have higher incidence of HLA B27 allele compared to the general population, although most patients with HLA B27 wont develop its
• they are said to have “class I HLA proteins” which are presented by all cells, on the contorary class II are only exposed by APCs and present predominantly foreign antigen to CD4 helper T cells.

Question 16

The most rapid relief from RA

Answer 16

-corticosteroids (prednisone), or NSAIDs untill DMARDS gets into effect.

Question 17

The most common congeintal breast anomalies in women and men are

Answer 17

Accessory nipple.

• they are due to failure of involution of the mammary ridge. They are usually asymptomatic however they may swell or become tender similar to normal breast tissue before or during menses.
• its identical to the normal nipple and can present with hyperpigmentation, epidermal thickening, pilosebaceous structure of montogmery areolar tubercules, smooth musle bundles and possible mammary glands and multiple ducts.

Question 18

LTC4, LTD4 and LTE4 antagonists are useful in

Answer 18

• they are useful in atopic asthma. Atopic asthma usually manifests in childhood. Of numerous inflammatory mediators postulated to play a role in the pathogenesis of allergic asthma, only leukotrines and actylcholine produce bronchospasm that is relieved by pharmacologic antagonists.
• leukotrines are synthesized by mast cells, eosinophils, basophilas and other cell types that infiltrate the bronchial mucosa in asthmatics. In addition to causing bronchial constriction and hyperreactivity.
• examples are zafirleukast and monteleukast

Question 19

Hepatitis B outcome

Answer 19

• acute hepatitis with complete resolution
• chronic hepatitis with or without cirhosis
• fulminant hepatitis with massive liver necrosis.
• the most common outcome in HBV infected adults is acute hepatitis with mild or subclinical symptoms that eventually completely resolves.

Question 20

Lactation suppression during pregnancy

Answer 20

• although lactenogenesis may begin during the second trimester, lactation is suppressed due to the high progesterone levels inhibiting the anterior pituitary.
• progesterone also inhibits LH and FSH during pregnancy.
• the drop in P after delivery allows for lactation

Question 21

Dofetillide is

Answer 21

Class III antiarrhythmic drug

Question 22

How to prophylactically treat in contact persons with , N.meningitidis transmission

Answer 22

N.meningitids is transmitted by direct contact with contaminated respiratory secretion or aerosilized droplets —> ppl are at high risk of developing the disease.

• antibiotic prophylaxis can prevent these secondary cases of given promptly.
• rifampin can be given to prevent the disease,also ciprofloxacin although its not used in children due to concerns about connective tissue injury

Question 23

Cerberal amyloid angiopathy

Answer 23

Amyloid angiopathy is a consequence of ßamyloid deposition in the walls of small to medium seized cerberal arteries, resulting in vessel wall weakening and predisposition to rupture.

• the disease isnt associated with systemic amyloidosis rather the amyloidogenic proteins are usually the same as those seen in Alzheimer disease .
• amyloid angiopathy is the most common cause of spontaneous lobar henmorrhage, particulary in adults age >60. Hemorrhage tends to be recurrent is typically associated with homonymous hemianopsia due to ocipital lobe infarcts.
• parietal lobe hemorrhage can cause contolateral hemisensory loss.

Question 24

Temporal bone fracture can lead to

Answer 24

Epidural hematoma

Question 25

Nonocclusive ischemic colitis

Answer 25

- in low flow states as may be seen in severe hypotension in pateints with underlying arterial insufficiency (D.M , ATH ). - non occlusive ischemia may occur at the margins of the anastomsis distribution. - these watershed areas are primarily in the left colon splenic flexure and rectosigmoid junction.

Question 26

Liquefactive necrosis

Answer 26

Complete digestion of necrotic tissue with the formation of a cavity, this predilection for liquefactive necrosis is thought to be assoicated with large amounts of lipids and lysosomal enzymes in the nervous cells.

Question 27

Bronchiolitis obliterans

Answer 27

Chronic rejection affects the small bronchiole producing drop in FEV1 to FVC. - histopathology shows lymphocytic inflammation and destruction of the epithelium of the small airways. Subsequently fibrinopurulent exudate and granulation tissue are found in the lumen of the bronchioli —> fibrosis and scarring.

Question 28

Myeloma cast nephropathy

Answer 28

Due to excess excretion of free light chain (bence jones proteins). - these proteins are filtered by the glomerulus in small amounts and reabsorbed in the tubules, when levels exceed reabsorptive capacity, light chain precipitate with tamm horsfall protein and form cast that cause tubular obstruction and epithelial injury leading to impaired renal function. - light microscopy shows numerous glossy cast that stain intensely esoinophilic are seen.

Question 29

A1 antitrypsin deficiency leads to

Answer 29

Panacinar emphysema

Question 30

Glioblastoma gross examination

Answer 30

Necrosis and hemorrhae with poorly defined areas. | -highly malignant with very poor prognosis and patients usually dies within less than a year from diagnosis.

Question 31

Vetebral osteolmylitis

Answer 31

- localized bony back pain, low grade fever and recent staphylococcal bacteremia all suggests vetebral osteomyelitis. - initial evaluation include blood cultures and MRI of the spine which is the most sensetive imaging method for diagnosis osteomyelitis.

Question 32

Malignant hyperthermia syndrome

Answer 32

Hypersensetivity of skeletal muscle to inhalation anesthetics (especially halothane) and muscle relaxant succinylcholine. - susceptibility to malginant hyperthermia is inheritied as an AD trait. - in majority of cases is due to defect to ryanodine receptors of sarcoplasmic reticulum. - abnorma ryanodine receptros release large anmount of Ca+ after exposure to anesthetic, excess of free Ca in the cytoplasm of muscle fibers stimulates its ATP dependent reuptake by SR. - excessive consumption of ATP generate heat, loss of ATP along with high tempreture leads to muscle damage. - clinically malignant hyperthermia presents with fever, and muscle rigidity after surgery under general anesthesia. - tachycardia, hypertension, hyeprkalemia, and myoglobinemia are characterestic - treatment is by dantrolene

Question 33

CAAT box is an area of

Answer 33

Initiation of transcription, as well as TATA box

Question 34

Glactokinase deficiency

Answer 34

-galactokinase deficiency causes galactose buildeup and this excess is converted to galctitol, an osmotic agent that causes cataracts. Unlike galactose 1 phosphate deficiency its a milder disease that usually results only in cataracts and positive test for reducing substances in urine.

Question 35

Temporomandibular disorder is

Answer 35

Charactrized by a constellation of symptoms that may include unilateral facial pain that worsens with jaw movement, headache and ear discomfort. -symptoms can originate from temporomandibular joint derangment, pathalogic contraction of the muscles of mastication and/or hypersensetivity of the nerves that supply the jaw.

Question 36

Integrins and fibronectin role in melanoma

Answer 36

The integrins are a family of transmembrane proteins receptors that interact with the extracellular matrix by binding to specific proteins, including collagen, fibronectin and laminin. - fibronectin are large glycoproteins produced by fibroblasts and some epithelial cells. - they bind integrins, matrix collagen and glycosaminoglycans serving as a mediator of cell adhesion and migration. - differential expression of integren subtypes affects adhesion proporties of individual cells and correlate with malignant behavior in number of tumors including melanoma.

Question 37

K+ regulation in nephron

Answer 37

- bowmans capsule 100% (freely filtred) - PCT 65% gets absorbed (35% remains) - the thick ascending limb of the loop of henle further reabsorbs about 25-30% of the filtred K+ load. - even in the presence of high K+, reabsorption of majority of PCT and ascending loop will be reabsorbed. - however the modulating part is in the collecting tubule.where 3 functions occurs 1. High extracellular K+ —> NA/K pump on principal cells 2. Aldosterone enahances activity of principal cells NA/K pumps 3. Alkalosis promotes K+ entery into cells in exchange for H+ which helps buffer the high extracellular PH

Question 38

Competitive inhibition

Answer 38

Occurs when an inhibitor binds to an enzyme and prevents it from binding to the substrate . Most competitive inhibitors bind to the active site and physically impede substrate binding to the active site.

Question 39

Vertical transmition of CMV leads to

Answer 39

It occurs in 1/3 of cases with the highest risk of transmission in 1st trimester. -it can lead to chorioretinitis , sensoneural seizures, jaundice hepatomegaly and splenomegaly , microcephaly also.

Question 40

Spinal stenosis

Answer 40

Abnormal narrowing of the spinal canal occuring most commonly in the lumbar region. - compression f the nerve roots results in a number of neurologic symptoms including lower extremity pain, numbness and parasethesia and weakness. - the onset of pain with walking is referred to as neurogenic claudication. - the symptoms of spinal stenosis are posture dependent(extension of lumbar spine narrows spinal canal and worsens symptoms while lumbar flexion such as walking uphill or leaning on stroller relieves the pain. - degenerative arthritis of the spine is the most common cause of spinal stenosis typically occuring in patients age >60. - hypertrophy of ligamentum flavum is the main factor that predispose to symptoms.

Question 41

Obturator nerve

Answer 41

Arise from lumbar plexus, and carries fibers from L2-L4 spinal segment. - it descends posteromedial to the ilipsaos muscle and course alone the lateral aspect of the lesser pelvis before descending through the obturator canal. - obturator nerve function is in adduction of the thigh - injury is most commonly caused by compression due to pelvic trauma, surgery or tumors. Patients typically presents with weakness on thigh adduction and sensory loss in the distal medial thigh.

Question 42

Jugular foramen syndrome

Answer 42

1. Loss of taste from post 1/3 of tongue 2. Loss of gag reflex 3. Dysphagia 4. Dysphonia hoarsness 5. Soft palate drop with deviation of uvula to normal side 6. SCM and trapezius paresis.

Question 43

Spinal muscle atrophy

Answer 43

The condition is caused by SMN1 gene mutation which encodes a protein involved in assembly of snRNPs in lower motor neurons. Defective snRNP results in imapred splicosome function and degeneration of anterior horn cell in the spinal cord. Nfant presents with delayed motor development and flaccid paralysis (hypotonia , decreased Deep tendon reflexes)

Question 44

Impetigo

Answer 44

- caused by s.pyogenes and staphylococcus aureus - clinically presents as painful non itchy pustules and honey crusted lesions - topical antibiotics (mupirocin ) is the treatment - complication : PSGN (not ARF - ARF is more common in strep throat)

Question 45

Supine hypotension syndrome

Answer 45

Its charactrized by hypotension, pallor, sweating nausea and dizzeness that occur when a pregnant women lies supine. This is due to the gravid uterus compressing on the IVC which reduces the venous return.

Question 46

Gumma

Answer 46

Appears in tertiary syphillis, develops many years after infection in untreated individuals, gumma are characterestic and often begins as painless, indurated granulomatous lesions that progress to white gray rubbery lesions that may ulcerate. They are most commonly cutaneous but also appear in the subcutaneous tissues, bones , liver and other organs. -tertiarry syphillis can also manifest as cardiovascular involvement with ascending aortic aneurysm and resultant aortic valve insufficiency.

Question 47

Xanthelasma biopsy

Answer 47

Lesion commonly found on the eyelid that contains lipid laden macrophages. (Foam cells, arrow ) histologically. - these papule are typically yellow due to the location of the foam cells in superficial dermis. - xanthelasma and other forms of xanthoma (tuberous, eruptive, tendinous) are classicaly associated with primary or secondary hyperlipidemia.

Question 48

Causes of menstrual bleeding

Answer 48

1,Fibroids : heavy menses, constipation, urinary frequency, pelvic pain and heaviness and enlarged uterus. 2. Adenomyosis: dysmenorrhea, pelvic pain, heavy menses, bulky globular and tender uterus. 3. Endometrial cancer/hyperplasia: history of obesity, null parity pr chronic an-ovulation, irregular intermenustraual or postmenopausal bleeding with non tender uterus

Question 49

Adhesions seen in endometriosis can lead to

Answer 49

They may interfere with ovulation and fallopian tube function resulting in infertility. - adhesions involving the uterosacral ligament can result in fixed, retroverted uterus. Infiltration of the posterior cul-de-sac can result in painful intercourse and tenderness with palpation of the posterior vaginal fornix. - shedding of ectopic tissue leads to dysmenorrhea

Question 50

Pseudocyst in pancreatitis is made out of

Answer 50

Fibrous and granulation tissues. -the most common location for pseudocyst is in the lesser peritoneal sac bordered by the stomach dudenum and transverse colon.