Block 21

Question 1

EBV attachment to B cells

Answer 1

-gp350 of EBV attaches to CD21 of B-cells.

Question 2

Common peroneal injury leads to

Answer 2

Injury can lead to loss of :
Foot eversion,
dorsoflexin and
toe extension

Question 3

Sickle cell disease manifestation

3

Answer 3

1. Hemolysis : intra and extravascular hemolysis —> increased bilirubin and and LDH and decreased hepatoglobin.
2. Vasocclusive symptoms: patients may experience pain from hypoxic tissue injury and infarction due to obstruction of small vessels by sickled cells. Dactylitis (hand-foot syndrome) —> infarction of bones of extremities can occur.
3. Infections: predisposition of infection with encapsulated organisms (s.pneumoniae..) because of repeated splenic infarcts.

Question 4

B12 deficiency —> what substances are changed in blood

Answer 4

1. Elevated levels of methylmalonic acid( the reason of subacute combined degeneration of dorsal coulmn)
2. Increased homocysteine.

Question 5

VHL gene is present on

Answer 5

Chromosome 3p. (Cerbellar hemangioblastoma, clear cell renal carcinoma, phochromocytoma and RCC

Question 6

NADPH is needed in

Answer 6

1. Fatty acid synthesis
2. Pentose phosphate pathway
3. Phagocytic cells (respiratory burst)
4. Cholesterol and steroid synthesis.

Question 7

a agonist effect on the eye

Answer 7

• the pupillary dilator muscle of the eye possesses å1 receptors and the stimulation of these å receptors result in contraction of the pupillary dilator muscle —> mydriasis. (Phenylephrine is used to dilate the pupil before opthalmioscopic examination)

Question 8

Heart posterior surface is made mostly by

Answer 8

Left atrium

Question 9

What structures in the pelvis are recruited in doing the valsalva manuever

Answer 9

Rectus muscles. They play the largest role in the development of the resultant intraabdominal and intrathoracic pressure during this maneuver.

Question 10

Candida is normally present in

Answer 10

1. Normal flora of the skin
2. Mouth
3. Vagina
4. Intestine

Question 11

Indole positive bacteria

Answer 11

• E.coli
• it differentiates it from enterobacter cloacae that have same features(gram negative lactose fermenting. Can cause uti) but is indole negative.

Question 12

Proteus features

Answer 12

Gram negative , non lactose feremnting.

Question 13

Diagnostic features of D.M

Answer 13

1. Fasting glycemia >126
2. Random glucose >200 mg/dl
3. Elevated Hb A1C >6.5%

Question 14

S.bovis is found in

Answer 14

Patients with subacute endocarditis and colonic cancer

Question 15

HF leading to dyspnea (mechanism)

Answer 15

Presence of fluid in the pulmonary interstitium causes distortion of the affected tissue, increasing resistance to movement (decrease compliance).
-as a result negative pressure generated during normal respiratory effort isnt suffecient to adequately distend the lungs resulting in poor gas exchange and shortness of breath.

Question 16

IgA protease importance in bacteria

Which organisms have it

Answer 16

• present on Niesseria species, H.infleunzae, and S.pneumoniae
• It cleaves IgA at its hinge region (yielding Fab, and compromised Fc fragments), thus decreasing its effectiveness.
• this facilitates bacterial adherence to mucosa.

Question 17

Dissemenated gonnorrheal infection

Answer 17

Triad of
1. Arthritis
2. Dermatitis
3. Tenosynovitis 
In sexually active women.

Question 18

Common triggers of asthma

Answer 18

1. Allergen inhalation (animal dandar, dust mites, pollens ..)
2. Respiratory irritants( cigarrete smoke, air pollutants, perfumes)
3. Infection (viral upper respiratory infection, rhinosinusitis)
4. Pharmacologic (aspirin, NSAID, Beta blockers)
5. Others such as excercise, cold , dry air, GERD. Emotions.

Question 19

Thermophillic actimomycetes species is associated with

Answer 19

Hypersensetivity pneumonitis in farmers (farmers lung)

Question 20

Differntial diagnosis of back pain

Answer 20

1. Degenerative : osteoarthritis : relieved with rest
2. Radiculopathy (disc) : radiates to leg, sensory and motor findings
3. Spinal stenosis: pain with standing, relieved by spinal flexion
4. Spondyloarthropathy : young, HLA-B27, relieved with exercise, morning stiffness
5. Spinal metastasis : constant pain, worse at night, not responsive to position change
6. Vertebral osteomyleitis: focal tenderness, fevers and night sweats, recent infection, iv drug abuse or immune comprmise,

Question 21

Neural crest migration to the abdomen

Answer 21

• neural crest start migrating to the intestinal wall very early during embryonic development. They give rise to ganglion cells of meissner and aurbach plexi of bowel wall.
• these neural crest usually present in the wall of proximal colon by the 8th week and at the rectum by the 12 week
• interruption of migration causes hirschprung disease.

Question 22

Alzehaimer drugs

Answer 22

Memantune : NMDA receptor antagonist

Galantamine, rivastigimine, tacrine,Donepezil, cholinestrease inhibitor.

Question 23

Amphotericin B side effects

Answer 23

• renal toxicity is the most notorius side effect of amphotericin B
• it causes renal vasoconstriction and reduction in glomerular filtration rate. It may also act as direct toxin on renal epithelial cells, leading to Acute tubular necrosis and renal tubular acidosis, and electrolytes disturbances.
• severe hypokalemia and hypomagnesemia can occur.

Question 24

Daptomycin side effect

Answer 24

Can lead to rhabdomylysis leading to elevated creatine phophokinase.

Question 25

Hypovolemic changes in FF,GFR,and RPF

Answer 25

• approximately 1/5 of the plasma that passes through the glomerular capillaries is filtred into bowmans space (normally)
• the decline in BP sensesd by baroreceptors —> arterial vasoconstriction —> renal vasoconstriction further lowers RPF (which already decreased due to systemic vasoconstriction) —> decreased glomerular perfusion —> decrease GFR —> RENIN-AGII —> constriction of efferent arterioles -> due to this change the decreases in GFR is less pronounced than the decrease in RPF.

Question 26

Hereditary orotic aciduria

Answer 26

-due to defect in uridine 5-monopsophate synthase
-physical and mental retardation
-megaloblastosis
-elevated urinary orotic acid levels.
Treatment: uridine supplementation can bypass this enzymatic defect and improve symptoms as uridine is converted to UMP via nucleoside kinase

Question 27

TCA side effects

Answer 27

1. Inhibition of presynaptic neurotransmitter reuptake (NE and serotinin) —> tremor, insomnia
2. Blockade of cardiac fast sodium channels —> conduction defects, arrythmias, and hypotension.
3. Antagonism of central and peripheral muscarinic actylcholine receptors—> confusion, dry moth, constipation, flushing ,urinary retention.
4. Antagonism of peripheral alpha-1 adrenergic receptors. —> orthostatic hypotension, falls
5. Antagonism of H1 receptors —> sedation.

Question 28

Argatroban mechanism of action and usage

Answer 28

Its used for heparin induced thrombocytopenia and it binds to thrombin active site

Question 29

17å hydroxylase deficiency

Answer 29

• it impairs the synthesis of androgens, estrogens and cortisol but doesnt alter aldosterone synthsis. In fact it have high quantitiy of mineralocorticoids.
• males with 17å hydroxylase are phemotypically female at birth but lack internal female genitalia due to absence of virilizing androgen in utero, hower female are normal internal and external genetalia.
• at puberty impaired synthesis of sex hormones prevents the development of secondary sexual characterestics in both sexes and prevents menarche in females. Excessive production of mineralcorticoids leads to hypokalemia, hypertension, low renin

Question 30

Flank pain radiating to the groin with a balootable flank mass that develops within a week of pelvic surgery suggests

Answer 30

Ureteric obstruction —> hydronephrosis

Question 31

Acute interstitial nephritis

Answer 31

Classically medication induced

- fever,rash and AKI

Question 32

Metabolic bone disease due to CKD

Answer 32

• CKD decrease GFR —> decreased phosphate filtration —> elevated phosphate —

Question 33

Length constant

Answer 33

Known as space constant, is a measure of how far along an axon an electrical impulse can propogate.

• more specifically the length constant is the distance at which the originating potential decreases to 37% of its original amplitude.
• one of the purposes of mylin is to reduce charge dissipation by increasing membrane resistance, thus increasing the length constant
• demyelination will decreases the length constant and result in impaired stimulus transmission.

Question 34

MS Vs polycythemia in hot shower pruritus

Answer 34

• MS have optic neuritis

- polycythemia doesnt involve the eye

Question 35

High synovial fluid leukocytes count >100,000 and absent crystals om microscopic examination strongly suggests>

Answer 35

Bacterial joint infection (septic arthritis ), antibiotics to prevent joint destruction osteomyelitis and sepsis.

Question 36

Sarcoidosis cells predomination

Answer 36

Increased CD4+/CD8+ ratio.

Question 37

lofgren syndrome

Answer 37

Acute form of sarcoidosis charactrized by

1. Erythema nodosum
2. Bilateral hilar lymphadenopathy
3. Polyarthlagia

Question 38

Myxo,atous changes in the media of large arteries are found in

Answer 38

Cystic medial degeneration

• medial degeneration is charactrized by the fragmentation of elastic tissues and seperation of the elastic and fibromuscular components of the tunica media by small,cleft like spaces that become filled with amorphous extracellular matrix.
• marfan syndrome is a common cause of cystic medial degeneration in younger patients, mutation in fibrillin-1 can lead to aortic aneurysm and dissection.