Random Flashcards
How can we differentiate Neimann Pick from Tay Sachs?
Both have cherry red spot
Neimann Pick has HSM (sphingomyelin builds up in lipid-laden foam cells that accumulate), Tay Sachs does not
Enzyme deficient in metachromatic leukodystrophy?
Arylsulfatase A deficiency
Findings in metachromatic leukodystrophY?
CNS accumulation of cerebroside sulfate –> Central and peripheral demyelination
Peripheral neuropathy and ataxia
Enzyme deficient in Krabbe’s disease?
galactocerebrosidase
How does Krabbe’s disease present?
Developmental delay and/or regression, hypotonia, optic atrophy, and seizures
What accumulates in Fabry disease?
Alpha-galactosidase A deficiency –> build up of ceramide trihexoside
What is the first step in heme synthesis?
Succinyl CoA and glycine — (ALA synthase) —> ALA
ALA = alpha amino levulinic acid
Which two enzymes in the heme synthesis pathway are inhibited by lead?
ALA dehydratase (ALA --> porphobilinogen, PBG) Ferrochelatase (portophyrin IX + Fe2+ --> heme)
What builds up with lead poisoning?
ALA
Zinc portophyrin IX (combines with zinc instead of lead)
Which enzyme is deficient in acute intermittent porphyria?
Porphobilinogen deaminase (PBG deaminase)
Characterized by acute attacks of abdominal pain, neuropsychiatric symptoms, and red or brown urine
What are the symptoms associated with porphyria cutanea tarda? What enzyme is most commonly affected?
Urophorphyrinogen decarboxylase
Leads to blisters where skin was exposed
Which porphyrin precursor products lead to photosensitivity?
Late ones- they must be a porphyrinogens or porphyrins
Which vitamins is a cofactor for ALA synthase?
Pyridoxal phosphate- B6
B6 deficiencies can lead to a microcytic hypochromic anemia
What are the effects of Pompe’s disease on the heart?
Cardiomegaly
What are the two galactokinase deficiencies and which one is worse?
Galactokinase deficiency–> less common, only leads to cataracts
GALT (galactose-1-phosphate uridyl transferase) deficiency –> vomiting, jaundice, hepatomegaly, lethargy
Most common cause of cystic fibrosis?
delta F508 –> misfolded protein
What is the copper reduction test?
Nonspecifically detects the presence of reducing sugars in the urine (fructose, glucose, or galactose)
What is the toxic build up in aldolase B deficiency and what is the consequence?
Toxic build up of fructokinase-1-phosphate, which builds up in the liver
What is the point of the 5’ –> 3’ exonuclease activity of bacterial DNA polymerase I?
Removed the RNA primer created by RNA primase and repair damaged DNA sequences
How does a B12 deficiency lead to impaired myelination?
Subacute combined degeneration
B12 is required for methylmalonyl CoA mutase. When it is impaired, methylmalonyl CoA cannot be converted to succinyl CoA, and its precursor, methylmalonic acid, builds up and impairs myelin synthesis
What reaction in the DNA synthesis pathway requires B12?
RBC synthesis depends on B12-dependent recycling of folate
Conversion of homocysteine to methionine with methionine synthase
This reaction creates THF, which is required for DNA synthesis
Connect PRPP synthetase deficiency to gout
Deficiency leads to increased production of purines and consequently increased purines precipitate as gout
Describe the use of colchicine in the acute management of gout?
Colchicine is useful in the acute management of gout when NSAIDS are contraindicated. It inhibits neutrophil chemotaxis and phagocytosis by inhibiting microtubule formation
Other than reducing oxidizing glutathione, what other biochemical process is NADPH required for?
Cholesterol and fatty acid synthesis
Describe the activation and inhibition of lipolysis of triglycerides in adipose tissue
Stress hormones stimulated Gs –> increased cAMP and activated PKA to activate hormone sensitive lipase which released free fatty acids.
HSL is inhibited by insulin
What is the embryologic purpose of the vitelline (omphalomesenteric) duct?
connects midgut lumen to the yolk sac
Structural derivatives of pharyngeal pouches 1-4?
1- Ear stuff
2- epithelium of palatine tonsil crypts
3- thymus, inferior parathyroid glands
4- Superior parathyroid glands,
Tx for homocystinuria?
B6 administration
Dietary methionine restriction and cysteine supplimentation
Chediak-Higashi syndrome?
Immunodeficiency, albinism, neurologic defects (like nystagmus)
ID comes from inhibition of phagolysosome fusion in neutrophils
AR inherited condition
Which embryologic layer gives rise to the anterior pituitary?
Surface ectoderm
What is the role of IL-3 (secreted by activated T cells?)
Stimulates growth and differentiation of stem cells from bone marrow
Mutation in primary myelofibrosis?
JAK2- a cytoplasmic tyrosine kinase –> constitutive JAK/STAT activation
All chronic myeloproliferative disorders have this mutation (polycythemia vera, essential thrombocytosis, primary myelofibrosis)
What are the serum and urine levels of calcium seen with calcium stones?
Normocalcemic plasma levels - regulated by Vit D, calcitonin and PTH
Hypercalciuria - idiopathic usually
Both thyroid parafollicular cells and chromaffin cells of adrenal medulla are derived from which embryological layer?
Neural crest
Structures arising from neural crest?
MOTEL PASS
Melanocytes Odontoblasts Tracheal cartilage Enterochromaffin cells Laryngeal cartilage Parafollicular cells of thyroid Adrenal medulla Schwann cells Spiral membrane
What is MELAS?
Mitochondrial encephalomyelopathy with lactic acidosis and stroke-like episodes
Describe psychologic “reaction formation”
Uncomfortable feelings are transformed into their opposite
How does ionizing radiation kill cells?
dsDNA breaks, free radical formation
How does non-ionizing radiation (UV light) cause DNA damage?
Formation of pyrimidine-pyrimidine (thymine) dimers
CD14 is a marker for which type of cell?
Macrophage
What CSF level is low in narcolepsy?
Hypocretin-1
Function of smooth ER?
Lipid synthesis, Carbohydrate metabolism, detox of harmful substances
SEx steroid synthesis
Succinate dehydrogenase requires which cofactor?
B2- riboflavin
succinate –> fumarate
How does the valsalva maneuver help with paroxysmal supraventricular tachycardia?
STimulates vagal tone –> decreases heart rate
Describe potassium levels during DKA
Overall, total body K+ is low (K+ is lost in the urine, hypovolemia –> increase in aldosterone and consequent loss of K+)
Despite low K+ levels overall, K+ is normal or increased in the blood b/c movement across concentration gradient, lack of insulin causes shift outside
Insulin normally promotes cellular uptake of insulin
What causes a type II (Beta) error?
Low power study
–> Falsely concludes there is no significant difference when there is
What is type I (alpha) error?
Falsely concludes there is a significant difference when there is not
What is Berkson’s bias?
Bias created when you choose hospitalized patients as the control group
What is open angle glaucoma?
Increased intraocular pressure due to increased aqueous humor production or decreased outflow
One advantage of the live polio vaccine is that it increases production of what Ig?
DUODENAL IgA
Secretory IgA is the major antibody associated with mucosal immunity
Which amino acid is elevated in astrocytes with hepatic encephalopathy?
Glutamine
Elevated ammonia –> increased production of glutamine to help it get excreted in the urea cycle.
Ankle sprains usually involve which ligament?
Anterior talofibular ligament
Mastocytosis can lead to what abnormality in the stomach?
Increased gastric secretion of HCl due to excess histamine stimulation of parietal cells
How does aminoglycoside resistance develop?
Bacterial production of aminoglycoside-modifying enzymes that transfer different chemical groups to the antibiotic molecule thereby decreasing its ability to bind the ribosome at 30S
Differentiate the build up of conjugated vs unconjugated bilirubin in Gilbert’s vs dubin johnson syndrome
Dubin Johnson- build up of conjugated bilirubin
Gilbert’s - build up of unconjugated
Delayed type (IV) hypersensitivity is characterized by what histologic changes of the skin?
spongiosis and accumulation of edema fluid in the intercellular spaces
Most common cause of fetal unilateral hydronephrosis?
UPJ obstruction- failure of canalization
Differentiate structures that arise from the metanephric blastema vs ureteric bud
Metanephric- glomeruli, bowmans space, nephron through the distal convoluted tuble
Ureteric bud: Collecting tubules –> ureters
What part of the tRNA binds to the ribosome?
The T-loop (left loop) that contains those weird amino acids
What does desmolase do?
Conversion of cholesterol to pregnenolone
What is the MOA of amatoxins from mushrooms?
Binding to DNA-dependent RNA polymerase II and therefore halting mRNA synthesis
MOA of ricin?
Inhibits protein synthesis by cleaving rRNA component of eukaryotic 60S subunit
How does fructose enter the glycolytic pathway in people with benign hereditary fructosuria?
Hexokinase converts fructose to fructose 6-phosphate, which can then enter glycolysis
What is the enzyme deficient when beta-oxidation is impaired?
Acyl-CoA dehydrogenase
Explain Hartnup disease
Deficiency in the ability to absorb neutral amino acids in the small intestine and proximal tubule of the kidney –> eventual niacin deficiency (from tryptophan)
–> pellegra like symptoms (with skin rashes) and cerebellar ataxia
List reaction sequences that require BH4
Phenylalanine –> tyrosine –> DOPA ….
Tryptophan –> serotonin …
G energy in protein, carbs, fats and ethanol?
Protein and carbs: 4g
Fats: 9g
Ethanol: 7g
Where in the cell does the hydroxylation of proline and lysine for collagen synthesis occur?
Inside the rough endoplasmic reticulum
Which reaction in the TCA generates GTP?
Succinyl-CoA to succinate (by succinyl-CoA synthase)
