Biochemistry - Nutrition and Metabolism 2 Flashcards
Hyperammonemia Treatment:
limit protein in the diet.
May be given to dec ammonia levels:
- Lactulose to acidify GI tract and trap NH4 + for excretion.
- Antibiotics (eg, rifaximin, neomycin) to kill ammoniagenic bacteria.
- Benzoate, phenylacetate, or phenylbutyrate react with glycine or glutamine, forming products that are excreted renally.
Hyperammonemia metabolic effects
NH3+ depletes glutamate in the CNS
inhibits the TCA cycle ( dec. a-ketoglutarate).
Arginine used to synthesize:
Creatine
Urea
Nitric oxide
(creat ur No)
Catecholamine synthesis/tyrosine catabolism
Phenylalanine - tyrosine - DOPA -Dopamine - Norepinephrine - Epinephrine
Catecholamine synthesis/tyrosine catabolism:
Phenylalanine and tyrosine both use…
hydroxylase and BH4
DOPA to Dopamine needs
dopa decarboxylase and B6
Dopamine to Norepinephrine needs…
dopamine beta-hydroxylase and vit C
Norepinephrine to Epinephrine needs…
Phenylethanolamine-N-methyltransferase and SAM
Induced by cortisol
Norepinephrine and Epinephrine metabolized to and by…
Vaniltymandelic acid
COMT
Dopamine metabolized to
Homovanillic acid
Homocystinuria Caused by:
- Cystathionine synthase deficiency
- dec. affinity of cystathionine synthase for pyridoxal phosphate
- Methionine synthase (homocysteine methyltransferase) deficiency
- Methylenetetrahydrofolate reductase (MTHFR) deficiency
Cystathionine synthase deficiency tx
dec. methionine, inc. cysteine, inc. B6, B12, and folate in diet)
dec. affinity of cystathionine synthase for pyridoxal phosphate tx
inc. substantially B6 and inc. cysteine in diet
Methionine synthase (homocysteine methyltransferase) deficiency tx
inc. methionine in diet
Methylenetetrahydrofolate reductase (MTHFR) deficiency tx
folate in diet
Homocystinuria presentation
All forms result in excess homocysteine.
H - HOMOCYstinuria: homocysteine in urine
O - Osteoporosis
M - Marfanoid habitus,
O - Ocular changes (downward and inward lens subluxation)
C - Cardiovascular effects (thrombosis and atherosclerosis - stroke and Ml)
Y - kYphosis
I - intellectual disability
F - fair complexion.
In homocystinuria, lens subluxated “down and in” (vs Marfan, “up and fans out”).
Propionic acidemia - Findings:
Findings:
vomiting (vomit pathway)
S - seizures H - hepatomegaly A - acidosis (anion gap metabolic) F - feeding (poor) T -hypoTonia
Von Gierke disease
(type I) sx
Severe fasting hypoglycemia
inc. Glycogen in liver and kidneys - hepatomegaly, renomegaly
Inc. blood lactate
inc. triglycerides
Inc. uric acid (Gout),
The liver does not regulate blood glucose.
Tay-Sachs disease findings
R - hyperReflexia A - hyperAcusis N - Neurodegeneration (Progressive) D - developmental delay O - onion skin lysosomes M - macula has a "cherry-red" spot
No hepatosplenomegaly (vs Niemann-Pick).
Tay-Sachs disease:
DEFICIENT ENZYME
ACCUMULATED SUBSTRATE
HeXosaminidase A
GM2 ganglioside
Fabry disease findings
XR!
Early: the triad of episodic peripheral neuropathy, angiokeratomas, hypohidrosis.
Late: progressive renal failure, cardiovascular disease.
Fabry disease
DEFICIENT ENZYME
ACCUMULATED SUBSTRATE
alfa -galactosidase A
Ceramide trihexoside (globotriaosylceramide)
Metachromatic
leukodystrophy
DEFICIENT ENZYME
ACCUMULATED SUBSTRATE
Arylsulfatase A
Cerebroside sulfate
Krabbe disease
DEFICIENT ENZYME
ACCUMULATED SUBSTRATE
Galacto-cerebrosidase (galactosyl-ceramidase)
Galactocerebroside, psychosine
Gaucher disease
DEFICIENT ENZYME
ACCUMULATED SUBSTRATE
Glucocerebrosidase (beta-glucosidase); treat with recombinant glucocerebrosidase.
Glucocerebroside
Niemann-Pick disease
DEFICIENT ENZYME
ACCUMULATED SUBSTRATE
Sphingomyelinase
Sphingomyelin
Hurler syndrome
DEFICIENT ENZYME
ACCUMULATED SUBSTRATE
a -L-iduronidase
Heparan sulfate,
dermatan sulfate
Hunter syndrome
DEFICIENT ENZYME
ACCUMULATED SUBSTRATE
Iduronate-2-sulfatase
Heparan sulfate,
dermatan sulfate
XR!
Metachromatic leukodystrophy - FINDINGS
Demyelination (central and peripheral)
Ataxia
Dementia.
Krabbe disease FINDINGS
N - Neuropathy (Peripheral)
O - oligodendrocytes destruction
D - developmental delay
O - optic atrophy
G - globoid cell
Gaucher disease FINDINGS
Most common: PHONe Booth with tissue paper
P - pancytopenia H - Hepatosplenomegaly O - osteoporosis N - necrosis (avascular, of the femur) e
Booth - bone crises
Gaucher cells (lipid-laden macrophages resembling crumpled tissue paper).
Niemann-Pick disease FINDINGS
Progressive neurodegeneration, hepatosplenomegaly, foam cells (lipid-laden macrophages) “cherry-red” spot on macula.
Hurler syndrome FINDINGS
C - corneal clouding H - hepatosplenomegaly AR- AiRway obstruction G - gargoylism e D - Developmental delay
Hunter syndrome FINDINGS
Mild Hurler + aggressive behavior, no corneal clouding.
“aggressive hunter needs to see the X”
Systemic 1° carnitine deficiency-
inherited defect in the transport of LCFAs into the mitochondria - toxic accumulation.
It causes:
weakness
hypotonia
hypoketotic hypoglycemia.
Medium-chain acyl-CoA dehydrogenase
deficiency- Pathophysiology
Dec. ability to break down fatty acids into acetyl-CoA - accumulation of fatty acylcarnitines in the blood.
Treat by avoiding fasting.
Familial dyslipidemias pathogenesis
1LP (or C II), 2 LD (or apoB 100), 3 with no E , 4 gets more (VLDL)
Familial dyslipidemias with even number are
AD
Familial dyslipidemias 1,4 cause
pancreatitis
Familial dyslipidemias 1,2,3 cause
xanthomas
Familial dyslipidemias 2 causes
corneal arcus + tendon xanthomas
Familial dyslipidemias 2,3
accelerated atherosclrosis
Familial dyslipidemias 4 is related to
insulin resistance
Familial dyslipidemia 1 has inc. blood level of
Chylomicrons, TG, cholesterol
Familial dyslipidemia 2 has inc. blood level of
Ila: LDL, cholesterol
lib: LDL, cholesterol,VLDL
Familial dyslipidemia 3 has inc. blood level of
Chylomicrons, VLDL
Familial dyslipidemia 4 has inc. blood level of
VLDL, TG
Hypertriglyceridemia (> 1000 mg/dL)
Abetalipoproteinemia
FREE SAM: F - Fatty acid restriction (TX) R - Retinitis pigmentosa E - E Vit E (TX-oral) E - Enterocytes are lipid Layden
S - Spinocerebellar degeneration (due to vit E def.)
A - Acantocytosis+ no Apo B48/100
M - MTP mutation (microsomal transfer protein) + Malabsorption.
weird reason for inc. synthesis of HDL
Alcohol
CARRIER MOLECULES for Acyl groups
CoA, lipoamide
Arsenic inhibits
lipoic acid.
Pyruvate
dehydrogenase
complex deficiency
PATHOPHYSIOLOGY
Causes a buildup of pyruvate that gets shunted to lactate (via LDH) and alanine (via ALT).
X-linked.
Pyruvate
dehydrogenase
complex deficiency
FINDINGS
Neurologic defects
Lactic acidosis
Inc. serum alanine starting in infancy.
Pyruvate
dehydrogenase
complex deficiency
TREATMENT
intake of ketogenic nutrients
Lactic acid dehydrogenase needs which cofactor?
B3
Antimycin A:?
Azide:?
Antimycin A: complex 3 inhibitor
Azide: complex 4 inhibitor
PEPCK needs?
GTP
Cahill cycle
Cori cycle
Cahill cycle - Glucose & Alanin
Cori cycle - Glucose & Lactate
orotic aciduria vs. ornithine transcarbamylase def.
orotic aciduria - has megaloblastic aneamia
ornithine transcarbamylase def. - has NH3
both have orotic acid in the urine (and blood)
Von Gierke disease tx:
frequent oral glucose/cornstarch; avoidance of fructose and galactose
Medium-chain acyl-CoA dehydrogenase
deficiency- findings
Causes: vomiting + CALLS + hypoketotic hypoglycemia. C - coma A - hyperAmmonemia L - lethargy L - liver dysfunction S - seizures
It can lead to sudden death in infants or children.