Thurs July 24 Flashcards
explain the FULL process of t cell maturation in the thymus
- 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
where does positive selection of t lymphocytes occur?
thymic cortex
where does negative selection of t lymphocytes occur?
thymic medulla
which antibodies are specific for CREST syndromes?
anti-centromere antibodies
which antibodies are specific for diffuse scleroderma?
anti-DNA-topoisomerase (Anti-Scl-70) antibodies
what are the two fates of homocysteine?
- it can undergo conversion to cystathionine and then to cysteine
- it can undergo remythlation to methionine
which enzyme is responsible for the conversion of homocysteine to cystathionine?
cystathione synthase
which cofactor is required by cystathione synthase?
B6
which enzyme is responsible for the conversion of homocysteine to methionine?
methionine synthase
which cofactor is required by methionine synthase?
B12
does a patient with siADH usually present with features of volume overload (heart failure, edema)?
No - usually the body compensates for the increase in volume and the presentation is subclinical - euvolemic hyponatremia
is rotavirus capable of genetic shift?
yes - it is a segmented virus and the strains can undergo reassortment
what is defective in ehlers danlos syndrome?
There is a deficiency in procollagen peptidase
what is the function of procollagen peptidase?
-it cleaves the propeptides of procollagen in the extracellular space
In Ehlers Danlos, there is a deficiency of procollagen peptidases. What is the result on collagen production?
The impaired propetide removal results in the formation of soluble collagen that does not properly cross link
what does mucor and rhizopus look like on microscopy?
Right angled branching, non-septate
how many a GI bleed lead to hepatic encephalopathy in someone with liver fibrosis?
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
is sexual transmission of hep C common?
NO its rare - usually from IV drugs
how does acute hep C present?
Usually asymptomatic
how does acute hep B present?
serum-sickness like syndrome - joint pain, lymphadenopathy, and an urticarial vasculitic rash
auer rods suggest which type of blood cancer?
AML
will many blast forms be seen in chronic leukemia?
No - blasts are characteristic of acute leukemia - mature cells are seen in chronic
what causes whipple disease?
Tropheryma whippelii
how to treat whipple disease?
antibiotics
describe normal changes to the heart that occur with aging?
- 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
what drugs are associated with a blue discoloration of vision?
PDE-5 inhibitors
why may PDE-5 inhibitors cause blue discoloration of vision?
they may inhibit PDE 6 in the retina which is involved in colour vision
effects of leukotriene C4?
triggers intense vasoconstriction, increased vascular permeability and bronchospasm
what is tardive dyskinesia?
involuntary movements, seen after chronic use of antipsychotics — lip smacking, facial grimacing, etc.
what is akathisia?
restlessness and inability to sit still
what is an acute dystonic reaction?
sudden-onset, sustained muscle contractions
saline microscopy AKA
wet mount
cervical cytology AKA
pap smear
Focal impaired awareness seizures that are preceeded by a distinct aura (returning aura) such as a smell, taste etc. are characteristic of..
mesial temporal lobe epilepsy
what commonly leads to mesial temporal lobe epilepsy?
Underlying hippocampal sclerosis, which can be due to febrile seizures
what lobe is the hippocampus part of?
temporal lobe
is methadone a full or partial mu agonist?
FULLLLLLLLLLLLL
Why could the administration of buprenorphine precipitate opioid withdrawal in someone with opioid dependance?
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
what substance binds to neurokinin 1 receptors to induce vomiting?
substance P
which type of t cell is abnormal in EBV?
CD8 cytotoxic t cells
can the epithelial cells of tubules in acute tubular necrosis regenerate?
yes - will occur gradually, during the recovary phase of acute tubular necrosis
which type of cell is responsible for the formation of fibrous cap on an atheroma?
vascular smooth muscle cells - they secrete matrix proteins, elastins, etc
what is the most common benign liver tumour?
cavernous hemangioma
which type of liver tumour may regress upon discontinuation of an OCP?
hepatic adenomas
