Block 29

Question 1

Guidelines for preventing cardiovascular events after MI

Answer 1

• the best treatment for prevention of cardiovascular events are HMG-Coa reductase inhibitors (statins) as those and always used as first line (even if HDL is low and LDL is normal).
• fibrates are inferior to statins in reducing cardiovascular evens and are primarily used to prevent pancreatitis in pts with very high TAG levels.
• niacin used usually in patients failed to benefit from both above
• ezetemibe usually used in patients having high LDL despite statin use.

Question 2

Which enzyme uses needs FAD in krebs cycle

Answer 2

Succinate dehydroginease (from succinate to fumurate)

Question 3

Riboflavin deficiency

Answer 3

• stomatitis
• chelitis
• glossitis
• seborrheic dermatitis
• eye changes
• anemia

Question 4

Good pasture syndrome

Answer 4

• nephritic syndrome
• renal biopsy shows linear deposits of immunoglobulins along the glomelular basment membrane which composed from IgG and C3
• type of RPGN in which cresentic GN occurs.
• pulmonary hemorrhage may be present as collagen type IV also present in the alveoli.

Question 5

Selective IgA deficiency

Answer 5

Usually assymptomatic, recurrent sinopulmonary or GI infection

• autoimmune disease (celiac disease may be present)
• anaphylaxis during transfusion (due to presence of IgA - foreign to body)
• diagnosed with low or absent IgA with normal IgG , IgM

Question 6

Fetal circulation

Answer 6

Oxygenated blood from placenta is delivered to the fetus via the umbilical vein, thus the umbilical vein have the highest O2 content on fetal circulation (ligamentum teres).
-then to the liver —> ductus venosus —> IVC —> right heart —> foramen ovale—> left heart.

Question 7

Enzymes that uses NAD

Answer 7

1. Isocitrate dehydrogenease
2. A ketoglutarate dehydorgease
3. Malate dehydorgeanse
4. Pyruvate dehydrognease

Question 8

G6PD deficiency

Answer 8

X-linked disorder mostly affects males.

• in erythrocytes G6PD is essential for maintaining adequate NADPH concentration (necessary to prevent oxidative stress)
• this syndrome is augmented under the infleuence of certain drugs (bactrim, dapsone, antimalarias, sulfinamides-trimethoprim ..) or other oxidant such as fava beans.

Question 9

Nucleosomes structural subunits

Answer 9

• within the nucleus are composed of DNA wrapped around a core of histone proteins.
• there are five major histones H1, H2A,H2B,H3 and H4. Each histone core is made up of 8 histone proteins (2 of each H2a,b, H3 and H4) .
• H1 is located outside the histone core, it binds to the linker segment of DNA that lie between nucleosome and facilitate packaging of nucleosomes into more compact structures.

Question 10

Effect of lung volume on alveolar and extraalveolar vessels

Answer 10

1. Increased lung volume causes alveolar expansion and lengthwise streching of the interstitial alveolar blood vessels. This increases their length and recudes its diamter resulting in increased alveolar vessel resistance
2. Decreased lung volume during expiration causes the extralveolar arteries and vein to become narrowed due to decreasd radial traction from adjacent tissues and compression by the positive intrathoracic pressure. This leads to increase in extraalveolar vessel resistance.
   - PVR is calculated as a sum of alveolar and extralveolar resistance ats these vessels lie in series with each other.
   - the highest PVR is present in inspiration and lowest in expiration.

Question 11

GLUT 2

Answer 11

Glucose enters the beta cells via GLUT 2 and undergoes oxidative metabolism through glycolysis and citric acid cycle generating ATP.

• ATP binds to the regulatory subunit of ATP-sensetive K+ channel.
• K+ channels normally opened at rest and maintain membrane polarization allowing outward movement of potasium from the beta cells, but when ATP binds to it channels close.
• high ATP/ADP ration leads to decreased K+ efflux and membrane depolarization. This result in the openeing of Ca+ channels —> insulin release.

Question 12

Cutaneous innervation of the ear

Answer 12

The majority of external ear recieves cutaneous innervation from the great auricular nerve(C2-C3), lesser occipital(C2-C3) nerve and auricotemporal nerve(CN V3)
Most of the external auditory canal including the external portion of tympanic nerve is innervated by the mandibular nerve .
-however the posterior part of the external auditory cana as well as the concavity and posterior eminentia of the concha is innervated by small auricular branch of vagus nerve ( if otoscope speculum is inserted patient may develop vasovagal syncope)

Question 13

SVC like syndrome with only one side affected means obstruction is present in

Answer 13

Brachiocephalic veins

Question 14

ARDS

Answer 14

• diffuse injury to the pulmonary microvascular endothelium and alveolar epithelium resulting in increased pulmonary capillary permability with leaky alvelocapillary membrane
• this result on noncardiogenic pulmonary edema with normal capillary wedge pressure. (Usually elevated PCWP is more suggestive of cardiogenic pulmonary edema).
• acute pancreatitis is highly associated with this syndrome.
• cytokines such as TNF-å, IL-1, IL-6 and IL-8 begins to circulate in response to the infection causing activation of pulmonary epithelium.-> provokes inflammatory response -> capillary damage and leakage of protein and fluid into alveolar space.
• most cases of ARDS occurs after 24 hours of inciting risk factor.

Question 15

Vibrio cholera

Answer 15

Oxidase positive , gram negative comma shaped organism able to grow in water and high alkaline selective media.

• cases can be isolated or with small outbreaks.
• fluid replacement is the mainstay of managment
• it leads to watery diarrhea
• pathogens typically causes dirrhea by producing cholera toxin (V. Cholera doesnt invade intestinal epethelium ).
• cholera toxin activated adenylate cycase 00> increased cAMP
• enhanced chloride efflux and decreased sodium reabsorption, and massive watery diarrhea.
• toxin also induces mucin ejection by goblet cells.
• rice water stool.
• no leukocytes or erythrocytes are present in stools.

Question 16

Stool findings in acute diarrhea

Answer 16

1. Watery: non-inflammatory, usually enterotoxin, stool findings shows no fecal leukocytes or erythrocytes
2. Dysentery or inflammatory: inflammatory (invasion or cytotoxin), fecal PMN with or without erythrocytes
3. Enteric fever : penetration and possible dissemenation, focal mononuclear lekocytes are seen (caused by salmonella typhi- leukocytes with monocytes predominance)

Question 17

What happens if a patient with B12 deficiency gets treated with folate

Answer 17

It can worsen demylination present and augment neurologic dysfunction.
-this is due to the fact that it causes abnormal myelin synthesis by depleting the concentration of unmethylated cobalamin available for methylmalonyl-CoA processing.

Question 18

Obstructive sleep apnea

Answer 18

Pathophysiology : relaxation of pharyngeal muscle leads to closure of airways.
Loud snoring with periods of apnea
Symptoms: 
-daytime somnolence
-non restorative sleep with frequent awakenings
-morning headache
- affective and cognitive symptoms
Sequlelae: 
-systemic HTA
- PHT and right heart failure

Question 19

Drugs which decrease craving for alcohol

Answer 19

-mu opoid receptor blockers
(Naltrexone)
-it blocks the rewarding and reinforcing effects of alcohol and has been shown to reduce craving for it.
-long acting depot form with monthly injection is useful for patients at risk for nonadherence with the drug.

Question 20

Disulfiram

Answer 20

Inhibits aldehyde dehydrogenease —> actylaldehyde accumulates leading to unpleasent side effects, its used only in abstinent patient with strong motivation to maintain abstinence.

Question 21

Side effects of a blockers

Answer 21

1. Orthostatic hypotension
2. Vertigo
3. First dose effect( first doses leads to hypotension, this is prevented with starting with a low dose going up)

Question 22

Walleria degeneration

Answer 22

Refers to the process that occurs when an axon is damaged, resulting in axonal degeneration and breakdown of mylin sheath distal to the site of injury, degeneration of the axon usually begins within few days after lesion onset.(persistance myelin debris)

• in the PNS this doesnt occur as schwan cells sense axonal degeneration and begins to degrade their myelin and recruit macrophages —> end result is nerve regeneration
• in CNS microglia are recruited more slowly because of BBB. This slows removal of myelin debris which can persist for years in degenerating tracts and supress axonal growth via myelin associated inhibitory factors.

Question 23

CF patients symptoms can be improved by giving >

Answer 23

Pancreatic lipase supplementation.

Question 24

Renin angiotensin aldosterone system drugs

Answer 24

1. Beta blockers: result in all (renin, AGI, AGII, and aldosterone ) to be decreased.
2. Direct renin inhibitors : result in all low except renin
3. ACEI: result in low AG II and aldosterone with high AG I and renin.
4. ARBS : result in all to be high except aldosterone.
5. Aldosterone inhibitors : all high

Question 25

PAroxysmal atrial fibrillation treatment

Answer 25

- rate control uses AV nodal blocking drugs (beta blockers, Ca+ blockers) - rhythm control , antiarrythmic drugs such as sotalol, flecinanide and amiodarone)

Question 26

Cause of hepatic encephalopathy in chronic liver failure

Answer 26

- hepatocytes disfunction and shunting f blood through portosystemic collateral impairs the livers detoxification ability. This leads to accumulation of ammonia and other neurotoxins in circulation. - this result in increased inhibitory neurotransmision (GABA) and impaired excitatory neurotransmistter release. - ammonia is normally produced by GI tract as a result of enterocytic catabolism of gltamine and colonic bacterial catabolism of dietary protein. - GI bleeding causes increased nitrogen delivery to the gut in. The form of hemoglobin, which is then converted into ammonia and absorbed into the blood stream. If liver failure is present this can lead to hepatic encephalopathy.

Question 27

Lactulose mechanism

Answer 27

Bacterial action on lactulose results in acidification of colonic contents, which then converts absorbable ammonia into nonabsorbable ammonium ions, trapping it in the stool and therby increasing fecal nitrogen excertion.

Question 28

PID

Answer 28

Symptoms : lower abdominal pain and abnormal bleeding Physical examination: cervical motion tendreness, fever, and mucupurulent discharge Treatment : third generation ceftriaxone plus azithromycin or doxycycline Complication: 1. Tubo-ovatian cyst 2. Infertility 3. Ectopic pregnancy 4. Perihepatitis.

Question 29

Partial mole

Answer 29

- present with vaginal bleeding, no fetal cardiac activity - triploid karyotype - evacuated uterine content contains fetal tissue, and other parts. - some edematous villi with focal trophoblastic proliferation and some normal appearing villi.

Question 30

Lumbar puncture site

Answer 30

Is performed with the patient in recumbent position. The optimal site for insertion is L3/L4 or L4/L5. The L4 vertebral body lies on line drawn between the highest points of iliac crests

Question 31

Homocysteine metabolism(normal vs disorders)

Answer 31

1. Can be metabolized to methionine ( via methyl-THF via methionine synthase).(treated with increasing methionine in diet) 2. Cystathionine (via cystathioine ß synthase ) —> cysteine (via cysthinoase )( treated with decreased methionine, increased cysteine , B12 and B9) 3. Decreased affinity to cysthaionine synthase (due to vitamin B6 deficiency) (treated with B6, and cysteine)

Question 32

Exteded spectrum beta lactamase producing E.coli

Answer 32

ESBL enzymes can inactivate penicillin and cephalosporins and monobactams. Gene coding for these enzymes are present in plasmid and therefore can be transferred to other organisms or specied through conjunction. - carbapenems are the treatment of choice in ESBL.

Question 33

Penicillin binding proteins with reduced antibiotic affinity is found in

Answer 33

MRSA