Block 17

Question 1

Acetylation of a drugs

Answer 1

Drugs like isoniazid, dapsone, hydralazine and procainamide, rely on acetylation.
Some people are fast acetylators and other are slow, this depends on genetic predisposition.
-slow acetylators of these drugs are at increased risk of toxic effect, while fast actylators requires larger dose to achieve theraputic effect

Question 2

Medical conditions with polygenic inheritence

Answer 2

1. androgentic alopecia
2. Epilepsy
3. Glaucoma
4. Hypertension
5. IHD
6. Schizophrenia
7. Type II D.M

Question 3

Eggshell calcification of hilar lymph nodes (calcified node, birefringent particles surrounded by dense collagen fibers) —>

Answer 3

Silica exposure

• can lead to fibrosis
• symptoms usually occur after 10-20 years of exposure
• dyspnea on excretion and productive cough.

Question 4

Asbestosis can presnt with

Answer 4

Dyspnea on excertion, interstitial pattern of involvement in lower zones.

• pleural plaques can be seen
• histology shows ferruginous bodies, fusiform rods with translucent asbestos center and iron containing coating

Question 5

L.monocytogenes meningits

Answer 5

• resistant to third generation cephalosporins

- susceptible to ampicillin

Question 6

Primary biliary cholangitis

Answer 6

• autoimmune liver disease characterized by small and mid sized intrahepatic bile ducts with resulting cholestasis.
• most common in middle aged women and associated with other autoimmune disease.
• clinical= fatigue, itching, hepatomegaly , ALP increased , anti mitochondrial antibody.
• biopsy shows= lymphocytic inflammation with destruction of intrahepatic bile ducts, and necrosis and micronodular regeneration of periportal tissues.

Question 7

GVHD

Answer 7

Occurs in immuncompromised patients following transplant of allogeneic bone marrow or other lymphocyte rich tissues. Donor T-cells migrate into host tissue, where they recognize MHC as foreign.
- liver involvement is often seen with increased ALP, and lymphocytic infiltration and destruction of small intrahepatic bile ducts (similar to PBC)

Question 8

Hypothalamus pituitary thyroid axis is regulated by

Answer 8

Negative feedback by T3 on TRH and TSH.

Question 9

Circulating thyroid hormones exist in which forms

Answer 9

1. T4 - major secretory product
2. T3 -the most active form of thyroid hormone, majority arises from peripheric conversion from T4
3. Reverse T3 (rT3)- is an inactive form that is generated almost entirely from T4

Question 10

Selective estrogen receptor modulators

Answer 10

Drugs : tomaxifen and raloxifene
Mechanism: competitive inhibitor of E2 binding, has mixed agonist/antagonist action.
Indication: -prevention of breast cancer in high risk patients
- tomaxifen: adjuvent treatment of breast cancer
-raloxifene: postmenopausal osteoporosis.

AE: -hot flushes, venous thrombosis.
Tomaxifen AE also shows endometrial hyperplasia and carcinoma.

Question 11

What is the most common cause of valvular aortic stenosis in developed nations

Answer 11

Calcific degeneration- progressive aortic leaflet thickening and calcification leading to restricted mobility.

Question 12

Infective endocarditis can lead usually to

Answer 12

AR

Question 13

Dyenein and kinesin role in virus transportation

Answer 13

• Dynein dependent “retrograde” transport of the virus.
• kinesin dependent “anterograde” transport of virus.
• this is usually seen in reactivation of HSV-1 infections during times of stress or illness.

Question 14

Pancoast tumors

Answer 14

-non small cell lung cancer arises near the superior sulcus.
- clinically determined by extent of local spread.
- compression and invasion of brachial plexus can cause ipsilateral shoulder pain, upper limb parasthesis, areflexic arm weakness.
-involvement of cervical symphatetic ganglia may lead to horners syndrome (ptosis, miosis and anhidrosis).
-

Question 15

Lymphatic drainage of the rectum

Answer 15

1. Lymphatics proximal to the anal line drain into the inferior mesenteric and internal illiac lymph-nodes
2. The upper rectum and superior part of the middle rectum follows the superior rectal nodes along the superior rectal artery into the inferior mesenteric lymph nodes
3. the middle to lower third can drain upward towards inferior mesenteric or follow middle rectal artery to the internal illiac lymph nodes.
4. Areas distal to the anal dentate line drain primarily into the inguinal nodes, although some also can reach upper nodes.

Question 16

Infant botulism

Answer 16

• associated with honey intake
• constipation usally precedes the characterstic signs of neuromuscular paralysis by a few days or weeks
• lathergy, weakness, and reduced feeding.
• in severe cases loss of head control and baby becomes floppy

Question 17

What is the most common cause of death in meconium ileus disease

Answer 17

Pneumonia- usually in CF patients

Question 18

MCC of death in CF

Answer 18

Pneumonia
Cor pulmonale
Bronchoectasis.

Question 19

Squirt sign

Answer 19

Forceful expulsion of stools after rectal examiation in infants
Present in hirschprung disease

Question 20

ß-hemolytic gram positive bacteria, DD

Answer 20

• s.pyogenes: PYR positive, bacteriacin sensetive,
• S.agalactiea- PYR negative, bacteriacin resistnat, hippurate test, CAMP factor positive (L.monocytogenes also CAMP positive)

Question 21

Necrotizing fasciitis features

Answer 21

Microbiology: S.pyogenes, S.aureus. C.perferingen, polymicrobial
Pathogenesis: bacteria spread rapidly through subcutaneous tissues and deep fascia, undermining the skin, usually involves extremities and perineal region.
clinical:history of minor trauma, erythema of overlying skin, swelling and edema, pain out of proportion to examination findings, systemic symptoms.
Treatment: requires surgical debridemant and broad spectrum antibiotics

Question 22

Acute hepatitis B

Answer 22

• systemic, skin and joint symptoms.
• hepatomegaly
• elevated transaminases.
• incubation period is 30-180 days
• sexually, parenterally and vertical transmission.
• pts may develop serum sickness like syndrome with joint pain, lymphadenopathy and pruritic urticarial vasculitis rash.
• most patients have non-ecteric hepatitis

Question 23

Acute hepatitis C

Answer 23

Typically assmymptomatic, dermatologic manifestations are seen in chronic infections.
-sexual transmission is very rare, usually parenteral transmission.

Question 24

Headaches, along with flat,pigmented,spots on the trunk. Also multiple subcentimter, soft ,fleshy cutaneous tumors on the trunk and neck.

Answer 24

NF-1

• AD, caused by mutation in NF1 tumor supressor gene. Patient develops hyper pigmented macules (over the turnk) soon after birth and are at increased risk for developing CNS neoplasms (eg. Optic gliomas, pilocytic astrocytoma) which can cause elevation of ICP and headache.
• cutaneous neurofibromas usually composed of schwann cell( which derived from neural crest cells).

Question 25

Kehr sign

Answer 25

Shoulder pain represents referred pain due to peritoneal irritation.

Question 26

Aminoglycoside resistnace

Answer 26

Develops through bacterial production of aminoglycosides modifying enzymes that transfers different chemical groups to aminoglycosides antibiotic molecule outside of the bacterium, thereby decreasing the ability of antibiotic to bind to ribosomes and exert is antimicrobial effects. (Mediated by plasmid or transposons)

Question 27

Vancomycin reistance in enterococci

Answer 27

VanA ligase replaces D-alanyl D-alanine to D-alanyl D-lactate, thereby preventing vancomycin binding.

Question 28

Tetracycline resistance

Answer 28

Can occur through a decrease in intracellular concentration of the drug and via synthesis fo a protein that allows ribosome to perform translation even in the presence of antibiotics

Question 29

Zellweger syndrome

Answer 29

Defective peroxisomal biogenesis. It typically presents in early infancy with carniofacial abnormalities (widened sutures, large anterior fontanelle), hepatomegaly, and profound neurologic defects (hypotonia, seizures, developmental delay). Death usually occuurs within months.

Question 30

X-linked adrenoleukodystrophy

Answer 30

-defective transport of VLCFA into prexisisomes. Patients present in childhood or adulthood with neurologic deterioration and adrenal insufficiency as VLCFA accumulate in CNS and adrenal gland

Question 31

The 50% infectios dose (ID50) corresponds to

Answer 31

Minimum number of organism required to cause a disease in 50% of affected individuals.

Question 32

CD55 absence indicates

Answer 32

Paroxysmal nocturnal hemoglobinuria

Question 33

Paroxysmal nocturnal hemoglobinuria would show which renal changes

Answer 33

-hemosiderosis, due to increased destruction of RBC—> iron overload —> iron deposition in the kidney —> PCT dysfunction with interstitial scarring and cortical infarcts.

Question 34

Cast nephropathy usually seen in

Answer 34

-multiple myeloma,

Question 35

Cholestasis clinical

Answer 35

Fatigue ,pruritus, hepatomegaly and elevated ALP. Cholestatasis arises secondary to hepatocellular dysfunction, or intrahepatic or extrahepatic dysfunction. -both obstructive and non obstructive cholestasis are charactrized by deposition of bile pigment within the hepatic parenchyma, often with green brown plugs in the dilated bile canaliculi. - the reduction in bile flow causes intestinal malabsorption of fats and fat soulble vitamins. (ADEK)

Question 36

In atherosclerosis of coronary artery, which is responsible for making the fibrous cap (synthesis)

Answer 36

Smooth muscle cells

Question 37

Sturge weber syndrome

Answer 37

Rare congenital neucutaneous disorder charactrized by the presence of cutaneous facial angiomas as well as leptomeningeal angioma. The condition is associated with mental retardation, seizures, hemiplegia, and skull radiopacities. (Tram track calcification)

Question 38

Oseler weber rendu syndrome

Answer 38

- AD,congenital telengectasia to the skin, and mucus membrane. - rupture of telengectasia may lead epistaxis, gi bleeding and hematuria.

Question 39

AV shunts after injury

Answer 39

Reult from the formation of AV fistulas. An AV fistula is an abnormal communication between an artery and vein that bypasses the arterioles, the major source of resistance in the vascular system. - thus AV sunts allow blood under arterial pressure to directly enter the venous system —>increases cardiac preload —>increasing the rate and volume of blood flow back to the heart.—> TPR decreased —>decrease in afterload

Question 40

Pulsatile mass with a thrill on palpation and presence of constant bruit over the site.

Answer 40

AV shunt

Question 41

Treatment of narcolepsy

Answer 41

Modafinil, non-amphetamine simulant is the first line, well tolerated and drug abuse is rare.

Question 42

Causes of gynecomastia

Answer 42

1. Increased E2 = -testicular cancer, obesity, cirhosis, thyrotoxicosis or androgen use 2. Androgen deficiency= hyperprolactinemia, renal failure, and primary or seconday male hypogonadism. 3. Medication effect= A. Decreased androgen production (GnRH agonist, ketoconazole) B. Decreased peripheral conversion to DHT(finasteride) C. Inhibition of androgen receptor ( spironolactone, bicaultamide)

Question 43

Gynecomastia prevention in males can be done using

Answer 43

Tomaxifen

Question 44

Uncontorlled diabetes can cause CN III ?

Answer 44

-it can cause diabetic CN III mononueropathy which classicaly present as acute onset diplopia - ptosis may occur -its caused by ischemic nerve damage which predominantly involves the core of the CNIII with relative sparing of the peripheral part. The somatic component of CN III that innervates the extra ocular muscles is located centrally,but autonomic component responsible for pupillary constriction and accomodation is located in the peripheral aspect of the nerve, therefore pupillary size and reactivity is normal.

Question 45

Loop of henle water permability

Answer 45

The descending loop is permeable to water while the ascending thick and thin are impermeable to water. (In the ascending limb the osmolarity decreases due to passive absorption of NaCl in the skin region as well as active transport of electrolytes out of the lumen by Na/k/2Cl- cotransporter in the thick portion.