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38 Cards in this Set

  • Front
  • Back
The C677TT polymorphism results in what?
A lowered activity of the enzyme MTHFR
What does MTHFR do?
Converts 5,10-methylene PteGlu --> 5 methyl PteGlu.
What are the two pathways of 5,10-methylene PteGlu ?
Can -->5 mthyl PteGlu (which then reacts & homo-->met)
-->H2PteGlu & dUMP->dTMP
If low folate & C677TT polymorphism then what?
Hypomethylation of DNA and decreased DNA syntheses:
- accum. of dUMP.
-misincorporation of uracil for thymine
- Increased DNA strand breakage
- Poor DNA repair
If high folate & C677TT polymrphism then what?
Still hypo methylation but now high conc. of 5,10-methylene PteGlu - increased DNA synthesis:
- higher DNA stability
- less misincorporation
-reduced risk of MSI tumors

-High met intake helps
Why does alcohol negate folate intake benefit?
Folate needed for alcohol metabolism (reduces folate pool) and alcohol can cleave folate
High homocysteine is believed to cause depression how?
Decreased neurotransmitter methylation
Oxidative damage
Why is neurotransmitter methylation inpaired?
Rxn converting SAH-->homo is reversible. High levels homo and the reverse reaction dominates. The methyl transferases have higher affinity for SAH than SAM; methylation decreases.
What are the causes of hyperhomocystenemia
B12/Folate deficiency
MTHFR or cbs impairment
What is excitotoxicity?
HCSA/HCA (oxidation products of homocysteine) can bind to NMDA receptor; opens cation channel, influx of Ca; cell death.
What is the disease associated with tocis doses of MeHg?
Minamata Disease
What are the symptoms of Minamata? MeHg poisoning in general?
Ataxia, sensory/vision impairment, tremors

MeHg causes permanent CNS damage
What foods contain high levels of MeHg?
How is MeHg absorbed? Once inside, where is it found?
90% absorption rate - very high!

It complexes with L-cysteine and taken into brain where it has neurotoxic effects.
How are seminal plasma concentrations of Vit C linked to male fertility?
Infertile men have been shown to have sig. lower seminal plasma Vit C concs then fertile men
It is believed that having a higher seminal concentration of Vit C results in higher quality sperm. Why?
Because of Vit C's ability to act as an antioxidant. It reacts with ROS (reactive oxygen species) that would otherwise affect sperm.

-OH can donate H =O
By reacting with the ROS, what is the benefit?
**IT reduces sperm DNA fragmentation***

Prevents chromatin cross-linking, DNA strand breakage, and oxidation of DNA bases
Also reduces abnormal spermatogensis
What is mastitis?
Inflammation of the mammary gland resulting from a bacterial infection.
A lack of what vitamins are believed to increase the incidence of mastitis?
Vit E and Se
What are neutrophils
They are the first-responders and produce peroxides to kill bacteria.
What is Vit E's role?
Vit E:
• Increases activity of WBC (neutrophils)
• Results in higher IL2 (higher Tcells)

• protects against too high of peroxide levels that could damage milk-secreting cells
What about Se?
Part of glutathione peroxidase that metabolises peroxides.
How does ethanol consumption increase one's risk of cancer?
The same enzymes used for the metabolism of ethanol are needed for the conversion of Retinol<-->retinal-->retinoic acid. RA needed in complex to regulate cell proliferation.
What are these enzymes?
1. Alhohol dehydrogenase (retinol dehydrogenase)
2. Aldehyde dehydrogenase (retinaldehyde dehydrogenase)
With high levels of ethanol, what happens?
Retinol accumulates. Less conversion to Retinal. Also, RA degradation increases.
Why is R.A. important for the regulation of cell proliferation?
RA is needed in RAR-RXR complex which is transcription factor for phosphorylase.

Compounds involved in cell proliferation (JNK, cJUN) are active when phosphorylated. Without phosphorylase, these compounds are not de-phosphorylated and continue to be active.

Plus -- ethanol stimulates cell proliferation. A double whammy.
Describe phytate and how it affects iron absorption
Phytate is a ringed structure with multiple phosphate groups. It chelates iron, espec. when there at 5+ groups.
How does erythorbic acid increase absorption of Iron?
It is better able to reduce iron, it stays in duodemun longer, and slows absorption
What does malting/soaking oat have to do with iron absorption?
Phytate is reduced; lower phytate = higher iron bioavailability; fermentation works too.
How is Vitamin D effective against breast cancer?

But what is downside?
Vit D:
induces apoptosis & causes tumor regression
high levels lead to hypercalcemia
What is a Vit D analog?
A structure similar to Vitamin D that is different in its side chain structure. Different analogs bind to different VDREs.
What is a VDRE?
Vit D Response Element
The two front runner - what are they and why do they work?
EB1089: inhibits growth factors
CB1093: induction of apotosis and increased DNA and cell membrane fragmentation

Key - both have less of an impact on Ca status than Vit D
Why would we treat pig's food with phytase?
#1: Increase the usable phosphorous in the food which is mostly linked to phytate - this also serves to reduce the load their "load"
2. Also, increase bioavailability of minerals
What is the impact of caffeine on Ca?
Caffeine impacts the metabolism of calcium. Acute: hypercalciuria due to decreased reabsoption
What are the main mechanisms that caffeine is believed to affect Ca?
1. Inhibition of adenosine & cAMP
Why is bone affected by caffeine?
1. effect secondary to increased urinary losses
2. caffeine may increase osteroblast apoptosis
What is the link between Vit E and vascular damage?
Vitamin E can prevent the oxidation of LDL by quenching free radicals. If LDL is oxidized, it can be taken up by macrophages, form foam cell; increased oxidative damage causes inflamation, endothelial disfuction. Deposits of plaque on arterial walls.