Teratogens Flashcards
what are the classes of teratogens
- medications
- social drugs
- environmental agents
- high temp/fever
- infectious diseases
- chronic diseases
- nutrient deficiency/excess
examples of teratogenic medications
- seizure meds
- accutane
- thalidomide
- lithium
- chemotherapy drugs
examples of social drugs
- alcohol
- cocaine
- cigarettes
examples of environmental agents
- organic solvents
- heavy metals
- pesticides
- PCBs
how is zinc status related to teratogenesis?
involved in the induction of metallothioneins, which are proteins that participate in a stress response in the liver.
they can bind to zinc –> secondary deficiency
is cannabis ok to have when preg?
there’s a lot of evidence that says no (negative impact on memory, hyperactivity, future risk of addiction, neurohormonal release in the mom)
what is the general advice as it pertains to drugs for pregnant ppl?
avoid them if possible whatsoever, but especially early on
what’s toxoplasmosis?
infectious disease caused by parasites in cat feces
what nutrients are of particular interest in excess?
- iodides (congenital goiter, mental/physical retardation)
- fluoride (spina bifida occulta)
- vit D (facial abnormalities, mental retardation)
- vit A (CNS abnormalities)
what nutrients are particular interest in deficiencies?
- protein (microcephaly)
- vit A (eye, microceph)
- vit D (fetal rickets)
- vit E (congenital abnormalities)
- vit K (coumadin syndrome)
- folate
- iodine (cretinism)
- K (kidney abn)
- copper (connective tissue defects, brain/bone abn)
- zinc (neural tube)
name some drugs that can induce nutrient deficiencies
- folate antagonists (methotrexate)
- vit K antagonists (coumadin)
- anticonvulsant-induced folate and Zn deficiencies
FAS characteristics
- craniofacial dimorphism
- growth retardation
- decreased fat stores
- retarded psychomotor and intellectual development
- decreased attention span
- decreased IQ
- hyperactivity
what is the safe amount of alcohol a preg person can have?
no safe amount
- 1 oz of pure alcohol –> 160 g decrease in birth weight
- high risk - 3 oz alcohol/day or 4 drinks/day
- increased risk w binge drinking
why does alcohol cause FAS?
alcohol passes freely through placenta where its clearance is very limited
- replaces other caloric sources
- affects folic acid and Zn metabolism
- acetaldehyde and free radical toxicity
- excessive apoptosis in sensitive cell populations
- placental toxicity
- fetal hypoxia
alcohol (increases/decreases) absorption of folate and zinc
decreases
anencephaly
no top part of skull
spina bifida
spine doesn’t completely close –> nerve exposure and damage
life long
etiology of neural tube defects?
- multifactorial inheritance
- single gene disorders
- chromosomal aneuploidy
- teratogens
- maternal diabetes
- severe overweight
- family history
- hot tub use/fever
- folate deficiency or inborn error of folate metab
how does folate protect against ntd?
methionine metabolism plays an important part in reproduction
the bioactive form of folate, 5-Me-TH4-folate, donates a methyl group to homocysteine to be converted into methionine
methionine is converted to SAM which enables the methylation of many integral components of the reproductive system (like DNA methylation)
what 3 vitamins are key in maintaining the proper methylation of homocysteine?
- b6
- b12
- folate
how does folate interact with the enzyme, 5-methylene tetrahydrofolate reductase?
this enzyme is key in generating the bioactive form of folate
a population with a low activity of this enzyme can correct it by having sufficient folate intake
how does homocysteine influence teratogenicity?
- accumulation of SAH leads to the hypomethylation of DNA
- oxidative stress (damaging and decreases functional activity of methionine synthase by limiting availability of b12)
you generally get more folate from consuming it from (a supplement/fortified foods/the diet)
supplement
