Mon July 13 Flashcards
how are pyrimidine dimers removed?
nucleotide excision repair
what type of DNA repair is defective in xeroderma pigmentosum?
nucleotide excision repair
abiraterone MOA?
Inhibits 17-alpha-hydroxylase, thus decreasing DHEA production. -Useful in prostate cancer
which enzyme is defective in PKU?
phenylalanine hydroxylase or BH4 cofactor
Presentation of PKU?
Intellectual disability Growth retardation Seizures Fair complexion Eczema Musty body odour
Treatment of PKU?
Avoidance of phenylalaine
Increased tyrosine intake
Tetrahydrobiopterin supplementation
Which sweetener must patients with PKU avoid?
aspartame - contains phenylalanine
Which enzyme is defective in alkaptonuria?
homogentisate oxidase
Which pathway is disrupted in alkaptonuria?
Conversion of tyrosine to fumarate
presentation of alkaptonuria?
blue-black connective tissue, ear cartilage and sclera - urine turns black on prolonged exposure to air
-arthralgias
proopiomelanocortin is cleaved to produce which substances?
beta-endorphins, ACTH and MSH
what is aripiprazole?
An antipsychotic drug used in schizophrenia and bipolar I
which enzymes require the cofactor thiamine?
pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and transketolase
inheritance of VHL?
autosomal dominant
what is systemic mastocytosis?
Clonal mast cell proliferation in the bone marrow, skin and other organs
systemic mastocytosis is associated with which mutation?
mutations in the KIT receptor tyrosine kinase
pathophys of systemic mastocytosis?
Mast cells overproduce tryptase
- they have excessive histamine release leading to flushing, syncope, hypotension, urticaria, etc.
- the histamine induces gastric acid secretion leading to ulceration
- the excess acid also inhibits pancreatic and intestinal enzymes, leading to diarrhea
what type of virus is the west nile virus?
Arbovirus (+ RNA virus)
what receptor does glucagon act on?
g protein coupled receptors - Gs
what is the first line treatment for essential tremor?
Beta-blocker
the acidic environment of the stomach helps with the absorption of which substances?
Ca, Fe, Mg and B12
the acidic environment of the stomach activates which pancreatic enzymes?
amylase and protease
the acidic environment of the stomach INactivates which pancreatic enzymes?
lipase
Someone who has been prescribes a PPI will have increased absorption of what?
dietary fats - loss of H leads to decreased INactivation of pancreatic lipases - thus promoting lipase activity and fat absorption
giant multinucleated tumour cells are consistent with which grade of cancer?
High-grade
These are found in anaplastic tumours
retinal hemorrhages in a baby are highly suggestive of….
abusive head trauma (shaken baby syndrome)
pathophys of shaken baby syndrome (abusive head trauma)?
Vigorous shaking leads to tearing of the bridging veins and subdural hemmorhage and retinal hemorrhage. The baby may have accompanying posterior rib fractures from the perpetrators grasp.
under normal conditions, the extracellular space has a high concentration of which ions?
Na and Cl
how may macrophages in an atheroma lead to instability of the plaque?
The plaque is constantly being remodelled, and macrophages may secrete MMPs which breakdown extracellular matrix proteins leading to plaque instability and risk of rupture
In myocardial ishemia, how soon will loss of contraction of the affected tissue occur?
Less then 60 seconds due to rapid depletion of ATP
after how long does myocardial ischemia lead to irreversible damage?
30 minutes
Under hypoxic conditions what is ATP in the myocardium broken down into?
ATP - > ADP -> AMP ->adenosine, which can cross the cell membrane and act as a vasodilator
what structures run through the superior orbital fissure?
CN III, IV, Va, VI, opthalmic veins and sympathetic fibers
what structure goes through the foramen rotundum?
CN Vb
what structure goes through the foramen ovale?
CN Vc
formula for total peripheral resistance in a parallel circuit?
1/resistance = 1/R1 + 1/R2 + 1/R3 + 1/R4
Blood supply to the femoral head?
Branches from the median circumflex humeral artery
what type of vaccine is the post-prophylactic exposure vaccine for rabies?
inactivated
which measure is sensitive to changes in prevalance of disease?
positive predictive value
negative predictive value
does sensitivity change with changes in prevalence of disease?
no
where does the radial nerve enter the forearm?
anterior to the lateral epicondyle
which two nerves does the radial nerve split into?
superficial and deep branches. The superficial branch is sensory and the deep branch is motor
which muscle does the deep branch of the radial nerve travel through?
the supinator muscle - making it vulnerable to injury from repeated supination/pronation
under which condition is chronic hyperventilation normal?
Pregnancy - the progesterone stimulates a sensation of shortness of breath and stimulates hypothalamus to increase respiratry drive
