Block 32

Question 1

Anticholenrgic toxicity

Answer 1

Clincal : -fever
-flushing
-dry skin and mucus membrane
- non reactive mydriasis
- delerium
Urinary retention 
-decreased bowel sounds
-tachycardia
Causes: 
1. Antihistamines
2. TCA
3. 1st generation antipsychotic (chlorprozamine)
4. 2nd generation antipsychotic (clozepine) 
5. Anti parkinson drugs (benzotropine, trihexyphendyl)
6. Belladonna alkaloids (atropine)

Question 2

Epinephrine effect on vessels

Answer 2

• On low doses the ß2 mediated vasodilation predominates whereas at high doses å1 induced vasoconstriction is more pronounced.
• if ß2 is blocked, (by propronalol for example), the å1 effect will be minimal, however if an epinephrine is infused the å1 effect will predominates leading to increase in BP with decrease in HR due to proponalol effect on ß1.

Question 3

Hemodynamic effect of epinephrine

Answer 3

1. HR and contractiliy : increases them (ß1 effect)
2. Systolic BP: increase (using ß1 +å1)
3. Diastolic BP: decrease at low dose(ß2>å1)
   Increase at high doses (å1>ß2)

Question 4

Trendelenberg gait is seen in injury to which nerve

Answer 4

-superior gluteal nerve

Question 5

In response of ADH where is the lowest osmolarity present

Answer 5

(Lowest osmolarity = diluted urine)
-distal convulated tubule is imperable for water —> it leads to absorption of solutes thus diluting the urine (lowest osmolarity)

Question 6

Bacillus anthrax toxin mechanism

Answer 6

Anthrax exotoxin composed of pretective antigen, edema factor and lethal factor.
-protective agent translocase the EF,and LF into the cell.once inside the cell EF acts as calmodulin dependent adenylate cyclase that increase cAMP concentration. It causes accumulation of fluid within and between cells and also results in suppression of neutrophil and Macrophages function.

Question 7

Micturition regulation

Answer 7

1. Sacral micturition center (located in S2-S4) (bladder contraction)
2. Pontine micturition center - located on pontine reticular formation
3. Cerberal cortex - inhibit sacral micturition center.

Question 8

Acute retinal hemorrhage

Answer 8

• most commonly caused by sever poorly controlled hypertension.
• hypertensive retinal hemorrhae typically causes painless, unilateral visual disturbances, ranging from mild obscuration without loss of visual acuity to permanent blindness.
• severe HTA in retinal precapillary arterioles causes endothelial disruption, leakage of plasma into the arteriolar wall, and fibrinous necrosis.
• necrotic vessels can then bleed into the nerve fiber layers, causing dot and flame shaped hemorrhages.

Question 9

CD 31 expressing tumor associated with arsenic exposure or polyvinyl chloride

Answer 9

Liver angiosarcoma

Question 10

Rapid urease test used to diagnose

Answer 10

H.pylori
-h.pylori produces large amounts of extracellular urease enzyme hence the use of urea solution for this test.
-urease converts urea to carbon dioxide and ammonia, causing PH increase and change in the color to pink (alkaline).
Alkaline color for more than 5 minutes indicates positive diagnosis.

Question 11

ETEC

Answer 11

• travelers diarrhea, gram negative cholera like toxin

- watery diarrhea with abdominal cramping, nausea and vomiting and possibly low fever.

Question 12

How to reduce the risk of transmission of microorganisms between patients

Answer 12

• hand hygiene by health care workers is the single most important measure.
• it includes hand-washing with soap and water or using alcohol based hand sanitizers that dont require water.
• proper hand-washing technique involves washing all surfaces of the hands and fingers with soap and water for at least 15 seconds, drying with a disposable towel, and using the towel to turn off the faucet.

Question 13

Shigella binding site in intestine

Answer 13

• Sihgella cant bind all intestinal cells, shigella exhibits specificity for the microfold cells at the vase of mucosal villi within a peyer patch region of the ileal mucosa.
• shigella penetrates the mucous membrane by passing through M cells via endocytosis. It subsequently lyses the endosome, multiple, and spreads laterally into other epithelial cells.
• this result in denuing and ulceration f the mucosa and subsequent leakage of blodd, inflammatory elements, and mucus into the intestinal lumen.

Question 14

Blunt trauma to the eye

Answer 14

• causes rapid increase in pressure that typically doesn’t rupture the globe but it transmitted posteropry into the orbit.
• the weakest plates of bone in the orbit, the medial and inferior walls , are common site of fracture
• fracture is typically evident on radiographic imaging and fluid or herniation of the orbital content can often visualized in the adjacent normally air filled sinuses.

Question 15

Infundibulopelvic ligament

Ovarian torsion

Answer 15

• its also called suspensory ligament of the ovary, it also houses the ovarian nerve plexus . Rotation of the ovary around the IP ligament leads in ovarian torsion.
• the main risk factor for torsion is the presence of large ovarian mass, the weight of the mass causes ovary to twist and occlude the ovarian vessel and nerve.
• a patient with ovarian torsion will typically present with sudden onset unilateral pelvic pain and nausea and sometimes vomiting and fever.

Question 16

Cavernous hemangioma

Answer 16

• the most common benign liver cancer typically present in adults 30-50 years of age.
• these benign tumors are thought to be congenital malformation that enlarge by ectasia, not hyperplasia or hypertrophy.
• multiple, well circumscribed, less than 5 cm in width
• these tumors consist of cavernous blood filled vascular spaces of variable size lined by a single layer of epithelium.

Question 17

Hepatic adenoma can regress in case of

Answer 17

-stopping oral contraceptive.

Question 18

Polyomyositis

Answer 18

-symmetric proximal muscle weakness
-increasing difficulty climbing stares, getting up from chair and carrying heavy objects
- elevated CK, aldolase
-autoantibodies (ANA, Anti jo1, anti histidyl tRNA synthetase)
- endomysial mononuclear infiltrates and patchy necrosis
Associated complication:
- interstitial lung disease and myocarditis.

Question 19

Acute interstitial nephritis(AIN)

Answer 19

• fever, rash, and AKI occuring within a few weeks of starting ß lactam is highly suggestive of acute interstital nephritis.
• other medication usually (NSAID, sulfonamides, rifampin and diuretics).
• AIN is thought to be mediated by IgE mediated hypersensetivity or cell mediated reaction (IV H.S).
• it leads to interstitial edema, leukocytes infiltration.
• inflammatory cells commonly infiltrates the tubular epithelium and granuloma formation may be observed.

Question 20

Disease calculation for a child to born with recessive disorder

Answer 20

P(affected child) = 1/4 X P (carrier mother ) X P (carrier father)
This is done in case the question doesnt state if the father and mother are true carriers.

Question 21

Pathogenesis of cholesterol gallstones

Answer 21

• in the liver free cholesterol is converted into cholic acid and chenodeoxycholic acids through a series of chemical reaction begining with cholesterol 7a hydroxylase.
• as water insoluble cholesterol is secreted in bile , it is rendered soluble in small amonts by detergent action of hydrophobic and hydrophilic bile salt, and phosphatidycholine (phospholipid). When these can be made soluble it precipitates into crystals that eventually merge and form gallstones

Question 22

Decreased levels of phosphatidylchline leads to

Answer 22

Gall stones formation

It can be given to a patient with gallstones to help dissolve gallstones.

Question 23

Tolerance to opioids

Answer 23

Tolerance to opioid usually expected to occur however tolerance to constipation and miosis doesn’t readily occur and constipation is the most common and persistent side effect of opioid.

• opioid stimulate mu receptors in GI tract causing decrease in secretion and gastric motility.
• pts treated with opioid should recieve prophylactic bowel regimen (high fibers diet, laxative and increased fluid)

Question 24

Sorolimus

Rituximab

Answer 24

1. Sorolimus mechanism of action: proliferation signal inhibitor by targeting mTOR signaling pathway, it binds to immunophilin FK-506 binding protein, forming complex that inhibits mTOR —> interruption of IL-2 signal transduction.
2. Rituximab: antibody against CD20 antigen, it depletes B cells through multiple pathways including complement mediated lysis, antibody- dependent cytotoxicity, and induction of lymphocytes apoptosis

Question 25

Mucormycosis

Answer 25

- most cases are rhinocerberal. - infection acquired through nasal passage to the sinuses/orbits and then sometimes the brain, leading to confusion neurological deficit and death. - black necrotic eschar in nasal cavity is characteristic - its diagnosed using mucosal biopsy to check for nonseptate hyphae with right angle branching.

Question 26

Types of xanthomas

Answer 26

Usually are 5 1. Eruptive xanthoma- appear with increased plasma triglycerides and lipid 2. Tuberous and tendenious xantoma - achilles tenon and extensor tendonds of the fingers. 3. Plane xanthomas - linear lesion associated with PBC 4. Xanthelasma - soft eyelid or periorbital plaque with no associated lipid abnormalities in 50% of cases.

Question 27

Penetrating injury at the left sternal border in the fourth intercostal space will injure ?

Answer 27

-right ventricle due to the fact that it composes the majority of the anterior surface of the heart

Question 28

Nasal injury

Answer 28

Nasal mucosa is highly vascular and easily irritated by trauma (eg nose picking), mucosal dryness and rhinitis. - epistaxis is very common in children and may be classified anterior or posterior. - anterior nosebleed is more common and vast majority occurs within the watershed area in the nasal septum known as hesselbach plexus. - managment to stop bleeding is usually by direct compression of the nasal alae. - cautery (silver nitrates ) may be necessary in persistant bleeding.

Question 29

Proliferative phase vs secretory phase

Answer 29

1. proliferative phase is characterized by increased levels of E2 -> nonbranching, nonbudding uniform glands evenly distributed, - in midproliferative the glands are tubular ,narrow and lined with pseudostratified elongated mitotically active epithelial cells. - the stratum functionale contains compact nonedematous stroma. 2. Secretory phase is characterized by —> increase PR —>follow ovulation —> development of secretory endometrium with large glands —> coiled and cell aquire large cytoplasmic vacules - glyocgen rich mucus is released into glandular lumens.

Question 30

Autosomal recessive polycystic kidney disease

Answer 30

``` Caused by mutation in PKHD1 gene, codes for fibrocystin (liver and kidney) Clinical findings: - renal insuffeciency -nephromegaly -hypertension( after few months ) -respiratory distress at delivery -oligohydroamnios — potter sequence ```

Question 31

Antigenic variation

Answer 31

This is especially seen in reinfection, as the body develops humoral immunity against one strain, the reinfectant strain will have another proporties due to recombination of pilus proteins —> produce new antigenic types of pilli

Question 32

Malignancy presence along with nephrotic syndrome suggests

Answer 32

- membrenous glomerulopathy - biopsy shows uniform, thickening of glomelular capillary wall on light microscopy without an increase in cellularity. IF reveals granular deposits and EM shows thickining by irregular dense deposits between basment membrane and epethilal cells that resembles spikes. - its caused by : 1. Systemic disease (D.M, SLE. solid tumors). 2. Certain drugs such as gold, penicillamine and NSAID 3. Infections - hepatitis B, hepatitis C, malaria, and syphillis

Question 33

Familial dysbetalipoproteinemia

Answer 33

- its charactrized by xanthomas and premature CHD. - AR disorder that is clinically more sever in pts with other condition affecting lpoprotein metabolism (e.g D.M) - the primary defect in this disorder are in ApoE3 and ApoE4 apolipoproteins found on the TAG rich lipoproteins (chylomicrons and VLDLs) that are responsible for binding hepatic apolipoprotein receptors. - without ApoE3 and ApoE4, the liver cant efficiently remove chylomicrons and VLDL remenants from circulation, causing their accumulation in the blood —> increased TAG and cholesterol.

Question 34

Familial chylomicronemia syndrome

Answer 34

LPL defeciency as well as ApoC2 Leads to elevated chylomicrons, and TAG. -may lead to acute pancreatitis and lipemia retinalis.

Question 35

Anicteric viral hepatitis

Answer 35

In children age <6 , HAV infection is most often (.80%) silent or subclinical (anicteric ). Less frequently it can present as acute self limited illness . - clinical disease is typically more severe in adults (some of them develop an aversion to smoking for unclear reasons) - hepatitis A rarely lead to liver failure

Question 36

Acyclovir nephrotoxicity

Answer 36

- phenomenon that occur in 5-10% of patients - when acyclovir concentration in collecting ducts exceeds its solubility crystalization, crystalluria and renal tubular damage may result. - in most cases, this toxic complication is transient and can be prevented with adequate hydration and dose adjusment.

Question 37

Allupurinol in leukemia and lymphoma

Answer 37

-it can be used to prevent tumor lysis associated urate crystal nephropathy

Question 38

Low molecular weight heparin mechanism of action

Answer 38

- administration of heparin increases the effect of the naturally occuring anticoagulant antithrombin III, it binds to AT III via pentasaccharide in the heparin chain, this result in a conformational change of AT III which subsequently inhibits factor Xa and neutralized thrombin, promoting anticoagulation. - AT III activated by LMWH acts predominantely at factor Xa (not thrombin ...... not thrombin ... not thrombin ) (thrombin is by unfractionated heparin)

Question 39

Cardiac output equations

Answer 39

CO=SV X HR | CO= rate of O2 consumption / arteriovenous O2 content differences

Question 40

Beta blockade on heart failure

Answer 40

- decrease myocardial work and O2 consumption —> slowing ventricular rate and reducing contractility. - lowers peripheral resistance by decreasing circulating levels of vasoconstricting hormones. - These effects are cardioprotective and help reduce cardiomyocyte death and limit deleterious cardiac remodeling.

Question 41

What is used to prevent PE

Answer 41

Low dose heparin

Question 42

Why does hemorrhagic infarct occur from PE

Answer 42

Because the lung have dual blood supply drom both pulmonary and bronchial arteries, bronchial blood usually hemorrhages into the ischemia area causing ,red hemorrhagic infarct. Occlusion of the peripheral branch of pulmonary artery produces a wedge shaped peripheral infarct adjacent to the pleura.

Question 43

Rectal biopsy in hirschprung disease should be taken from

Answer 43

The area with narrow lumen (not the megacolon part) from the submucosa as they contain the meissner and myenteric plexi

Question 44

Lesion to temporal love (vision problems)

Answer 44

-lesions in temporal lobe can disrupt meyers loop and produce controlateral superior quadrantnopia, temporal lobe lesions can also produce other neurologic manifestation including aphasia, memory deficits, seizures and hallucinations

Question 45

In gluconeogenesis phosphophenolpyruvate requires what in order to be converted from oxaloacetate

Answer 45

GTP that is obtained from the conversion of succinyl-coa to succinate.

Question 46

Pyruvate metabolism under hypoxic conditions

Answer 46

Under hypoxic condition, Intracellular accumulation of NADH inhibits pyruvate dehydrogenease. As a result increased amounts of pyruvate is shifted toward lactate dehydrogenease. Which regenerates NAD+ from NADH.

Question 47

Pyruvate enzymes

Answer 47

1. Pyruvate kinase : PEP —> pyruvate 2. Pyruvate carboxylase : pyruvate —> oxaloacetate 3. Pyruvate dehydrogenase -> pyruvate -> actyl-coa

Question 48

Endotoxin creates its effect by binding

Answer 48

TNF-å, IL-1 and IL-6.