Biostats review Flashcards
What are the essential amino acids?
Private (PVT) TIM HaLL
· P – Phenylalanine
· V – Valine
· T – Threonine
· T – Tryptophan
· I – Isoleucine
· M – Methionine
· H – Histidine
· L – Leucine
· L – Lysine
Rate limiting step of urea cycle
Carbamoyl phosphate synthetase 1
What is the transporter for ammonia
Alanine
Causes of hyperammonemia?
Liver disease (hepatic encephalopathy – because urea cycle occurs in hepatocyte)
Urea cycle enzyme deficiency (ornithine transcarbamylase is the most common deficiency)
Causes and basic premise behind phenylketonurie (PKU)
Tyrosine deficiency
Due to:
o Deficiency in phenylalanine hydroxylase, or
o Deficiency in tetrahydrobiopterin cofactor (BH4)
Presentation of PKU
o Intellectual disability
o Growth retardation
o Seizures
o Fair skin (inability to make melanin)
o Eczema
o Must body odor
Basic premise behind maple syrup urine disease
THINK: I Love Vermont maple syrup from branched maple trees
§ Branches - blocked degradation of branched amino acids
§ I - Isoleucine
§ Love - leucine
§ Vermont - Valine
Presentation of maple syrup urine disease
o CNS defects, intellectual disability, and death
Basic premise behind Alkaptonuria
Inability to degrade tyrosine due to defect of homogentisate oxidase
Presentation of Alkaptonuria
o Blueish-black connective tissue and sclera
o Black urine upon prolonged exposure to air
o Debilitating arthralgias
Causes of homocysteinuria
o Cystathionine synthase deficiency
o Decreased affinity of cystathionine synthase for B6
o Methionine synthase deficiency
Presentation of homocysteinuria
o Homocysteine in urine
o Marfanoid habitus
o Ocular changes (downward and inward lens subluxation – vs. Marfan which is upward)
o CV effects (thrombosis and atherosclerosis)
o Kyphosis
o Intellectual disability
Cause of cystinuria
Defect in proximal convoluted tubule of the kidney in the COLA transporter (Cysteine, Ornithine, Lysine, Arginine)
Defect prevents reabsorption of COLA amino acids
4 uses of NADPH
Synthesis of fatty acids and cholesterol
Generation of O2 free radicals (conversion of O2 to O2- via NADPH oxidase)
Protection of RBCs from free radicals (via reduction of glutathione)
Cytochrome P450 enzymes
What are the 4 major glycogen storage diseases?
THINK: Very Poor Carbohydrate Metabolism:
Von Gierke disease (Type I)
Pompe Disease (Type II)
Cori Disease (Type III)
McArdle Disease (Type V)
What is the deficient enzyme in Von Gierke Disease
glucose-6-phosphatase
(glucose-6-phosphate to glucose)
Findings in Von Gierke disease
Severe fasting hypoglycemia
The defect affects both glycogenolysis and gluconeogenesis
What is the deficient enzyme in Pompe disease?
Lysosomal a-1,4-glucosidase
(branched glycogen back to glucose)
Presentation of Pompe disease
Cardiomegaly, hypertrophic cardiomyopathy, exercise intolerance, shortened life expectancy
THINK: Pompe = fat = symptoms of obesity
What enzyme is deficient in Cori disease?
Debranching enzyme
THINK: Cori wants me to climb his “straight branch”
Presentation of Cori disease
Is a milder form of Von Gierke because it causes a defect in glycogenolysis but not in gluconeogenesis
What is the deficient enzyme in McArdle disease
Skeletal muscle glycogen phosphorylase
THINK: McArdle = Muscle
Findings of McArdle disease
You can make glycogen but can’t break it down
Increased glycogen in muscle -> increased osmotic pressure -> swelling and lysis of myocytes -> rhabdomyolysis -> myoglobin in serum -> myoglobin in urine (myoglobulinuria - red urine)
