Biochem Flashcards
Function of Vit. A (retinol)?
- Antioxidant
- visual pigment component (retinal)
- squamous epithelial cell differentiation into specialized cells (i.e. pancreas, mucus-secreting)
- prevents squamous metaplasia
- Tx: measles, & AML-M3
S/E of Vit A deficiency?
- Night blindness
- Dry skin
What is is Vit A used for in treatment?
Wrinkles, acne
Measles
AML-M3 subtype
Excess Vitamin A can cause hat Sx?
- Arthralgias
- fatigue, headache, sore throat
- skin changes
- alopecia
- Teratogenic
Why is Vit A based drugs not given to women? Give example of drug and requirements before admin
- Teratogenic: cleft palate & cardiac abnormalities
- Retinol an act on embryogenesis. Part of Hox gene. If excess, Hox gene becomes dys-Fx
- before Isotretinoin (severe acne), requires neg pregnancy test and reliable contraception
What tissues are effected first by Thiamine deficiency? What Tx can worsen Sx?
Brain and CNS; heart (highly Aerobic)
Vitamin B1 needed for ATP production.
Glucose infusion worsens
What enzymes require Thiamine? In what form does it act?
- Thiamine is a cofactor for enzymes as TPP: Thiamine pyrophosphate. Used for decarboxylation:
1) Pyruvate Dehydrogenase (Glcolysis –> TCA)
2) α-ketoglutarate dehydrogenase (TCA)
3) Transketolase (HMP)
4) Branched chain amino acid dehydrogenase
Deficiency of what enzyme can cause buildup branch chain amino acids? What is the disease and Sx?
Describe in detail
Maple Syrup Urine Disease [AR]
Decrease in α-ketoacid dehydrogenase. Deficiency causes buildup of α-ketoacids: Ile, Leu, Val.
Sx: Severe CNS defets, mental retardation, death.
“I Love Vermont maple syrup from maple trees w/ branches
What are causes of Homocystinuria?
Defect [AR] in
- Cystathionine synthase,
- N5-methyl THF homocysteine methyltransferase (NPTHM)
- or decreased affinity of CS for Vit. B6 (cofactor)
- B12 def another cause, needed for NPTHM
Homocysteinuria affects whih enzyme pathway?
Homocysteine –(NPTHM)-> Methionine
Homocysteine–(CS & B6)–> Cystathionine –(B6)->Cysteine
Explain Sx of Homocystinuria
Homocysteine toxic to
-vascular endothelium: CAD, ↑PLTadhesion→Thromboembolis, stroke, MI
-MR
-Interferes w/ collaen formation: osteoporosis, lens dislocation (ectopia lentis).
Tall height, Arachnodactyly, elongated limbs, scoliosis, aka “Marfanoid habitus”.
DON’T CONFUSE W/ MARFAN SYNDROME!
How to Tx Homocystinuria?
- Decrease methionine in diet
- increase cysteine, folate, B12, & high dose Vit B6 in diet.
What causes Hartnup disease?
Mutation [AR] in neutral amino acid transporter in renal PT & small intestine epithelial cells.
Deficiency in neural AA, like Tryptophan
Sx of Hartnup disease
↓Tryptophan → Niacin deficiency.
- Pellegra (3 Ds)
- photosensitive dermatitis (face, neck, limbs),
- Neuro: personality disturbance, cerebellar ataxia, MR
Tx of Hartnup disease?
Nicotinic acid supplements
Lab findings of Hartnup
Renal aminoaciduria in urine
Lab findings of Homocystinuria
↑Methionine in serum
↑↑homocysteine in urine
What causes Cystinuria?
Tx?
Defect [AR] in renal PCT and intestinal absorption of Cysteine, Ornithine, Lysine, &Arginine
“Kidneys don’t drink COLA”
Tx: drink water, & alkalize urine
Sx and lab findings of Cystinuria
- cysteine kidney stones (CT radiograph shows)
- hematuria and cystine hexagonal crystals when urine cools
- Staghorn calculi
- Urine AA chromatography: COLA
What diseases seen w/ Thiamine deficiency?
-Wernicke Korsakoff: classic triad of confusion, ophthalmoplegia, & ataxia.
+ confabulation, personality change, memory loss (permanent)
-Dry Beri Beri (CNS): polyneuritis, symmetrical muscle wasting
-Wet Beri Beri (heart):dilated cardiomyopathy, edema
What CNS tissues affected by B1 deficiency?
Mamillary bodies
Medial Dorsal Nucleus of thalamus
What is function for Vit B2?
Vit Riboflavin
-cofactor Redox (i.e. FADH2). FAD & FMN derived from riboFlavin (B2 = 2 ATP)
Sx of Vitamin B2 deficiency
-Cheilosis (lip inflammation, scaling fissures at corners of mouth)
-Corneal vascularization
-Magenta colored tongue
“The 2 C’s of B2”
Function of Vit B3?
Derived from what?
Part of NAD+, NADP+. Used in redox rxns.
Derived from tryptophan (tryptophan converted to Niacin w/ Vit B6)
