Thurs July 24

Question 1

explain the FULL process of t cell maturation in the thymus

Answer 1

• t-lymphocytes are produced in the bone marrow and arrive in the thymus in the first trimester
• the pro-T cells arrive at the thymus with neither the CD4 or CD8 antigens (double negative)
• next, rearrangement of the TCR occurs and this stimulates the synthesis of both CD8 and CD4 (double positive)
• positive selection then occurs in the thymic cortex
• negative selection then occurs in the thymic medulla
• finally, the loss of either CD4 or CD8 results in a mature lymphocyte

Question 2

where does positive selection of t lymphocytes occur?

Answer 2

thymic cortex

Question 3

where does negative selection of t lymphocytes occur?

Answer 3

thymic medulla

Question 4

which antibodies are specific for CREST syndromes?

Answer 4

anti-centromere antibodies

Question 5

which antibodies are specific for diffuse scleroderma?

Answer 5

anti-DNA-topoisomerase (Anti-Scl-70) antibodies

Question 6

what are the two fates of homocysteine?

Answer 6

1. it can undergo conversion to cystathionine and then to cysteine
2. it can undergo remythlation to methionine

Question 7

which enzyme is responsible for the conversion of homocysteine to cystathionine?

Answer 7

cystathione synthase

Question 8

which cofactor is required by cystathione synthase?

Answer 8

B6

Question 9

which enzyme is responsible for the conversion of homocysteine to methionine?

Answer 9

methionine synthase

Question 10

which cofactor is required by methionine synthase?

Answer 10

B12

Question 11

does a patient with siADH usually present with features of volume overload (heart failure, edema)?

Answer 11

No - usually the body compensates for the increase in volume and the presentation is subclinical - euvolemic hyponatremia

Question 12

is rotavirus capable of genetic shift?

Answer 12

yes - it is a segmented virus and the strains can undergo reassortment

Question 13

what is defective in ehlers danlos syndrome?

Answer 13

There is a deficiency in procollagen peptidase

Question 14

what is the function of procollagen peptidase?

Answer 14

-it cleaves the propeptides of procollagen in the extracellular space

Question 15

In Ehlers Danlos, there is a deficiency of procollagen peptidases. What is the result on collagen production?

Answer 15

The impaired propetide removal results in the formation of soluble collagen that does not properly cross link

Question 16

what does mucor and rhizopus look like on microscopy?

Answer 16

Right angled branching, non-septate

Question 17

how many a GI bleed lead to hepatic encephalopathy in someone with liver fibrosis?

Answer 17

GI bleed such as esophageal varices can lead to increased blood in the GI tract. The hemoglobin is converted to ammonia and reabsorbed into the blood stream. In someone with liver fibrosis, this cannot be properly detoxified- > encephalopathy

Question 18

is sexual transmission of hep C common?

Answer 18

NO its rare - usually from IV drugs

Question 19

how does acute hep C present?

Answer 19

Usually asymptomatic

Question 20

how does acute hep B present?

Answer 20

serum-sickness like syndrome - joint pain, lymphadenopathy, and an urticarial vasculitic rash

Question 21

auer rods suggest which type of blood cancer?

Answer 21

AML

Question 22

will many blast forms be seen in chronic leukemia?

Answer 22

No - blasts are characteristic of acute leukemia - mature cells are seen in chronic

Question 23

what causes whipple disease?

Answer 23

Tropheryma whippelii

Question 24

how to treat whipple disease?

Answer 24

antibiotics

Question 25

describe normal changes to the heart that occur with aging?

Answer 25

• decreased left ventricular chamber size (particularly length, leading to a signmoid shaped ventricular septum)
• increased interstitial connective tissue with increased amyloid deposition
• brownish cytoplasmic granules

Question 26

what drugs are associated with a blue discoloration of vision?

Answer 26

PDE-5 inhibitors

Question 27

why may PDE-5 inhibitors cause blue discoloration of vision?

Answer 27

they may inhibit PDE 6 in the retina which is involved in colour vision

Question 28

effects of leukotriene C4?

Answer 28

triggers intense vasoconstriction, increased vascular permeability and bronchospasm

Question 29

what is tardive dyskinesia?

Answer 29

involuntary movements, seen after chronic use of antipsychotics — lip smacking, facial grimacing, etc.

Question 30

what is akathisia?

Answer 30

restlessness and inability to sit still

Question 31

what is an acute dystonic reaction?

Answer 31

sudden-onset, sustained muscle contractions

Question 32

saline microscopy AKA

Answer 32

wet mount

Question 33

cervical cytology AKA

Answer 33

pap smear

Question 34

Focal impaired awareness seizures that are preceeded by a distinct aura (returning aura) such as a smell, taste etc. are characteristic of..

Answer 34

mesial temporal lobe epilepsy

Question 35

what commonly leads to mesial temporal lobe epilepsy?

Answer 35

Underlying hippocampal sclerosis, which can be due to febrile seizures

Question 36

what lobe is the hippocampus part of?

Answer 36

temporal lobe

Question 37

is methadone a full or partial mu agonist?

Answer 37

FULLLLLLLLLLLLL

Question 38

Why could the administration of buprenorphine precipitate opioid withdrawal in someone with opioid dependance?

Answer 38

It’s a part agonist - it binds tightly to the receptor and can block binding of other agonists but it has low intrinsic acitvity and thus could induce withdrawal in someone usually on full-agonists

Question 39

what substance binds to neurokinin 1 receptors to induce vomiting?

Answer 39

substance P

Question 40

which type of t cell is abnormal in EBV?

Answer 40

CD8 cytotoxic t cells

Question 41

can the epithelial cells of tubules in acute tubular necrosis regenerate?

Answer 41

yes - will occur gradually, during the recovary phase of acute tubular necrosis

Question 42

which type of cell is responsible for the formation of fibrous cap on an atheroma?

Answer 42

vascular smooth muscle cells - they secrete matrix proteins, elastins, etc

Question 43

what is the most common benign liver tumour?

Answer 43

cavernous hemangioma

Question 44

which type of liver tumour may regress upon discontinuation of an OCP?

Answer 44

hepatic adenomas