Environmental Influences Flashcards
Teratogens are:
- agents that can cause birth defects.
- usually something in the environment that the mother may be exposed to during her pregnancy.
Teratogenic susceptibility is greatest during:
- early organogenesis
- for EACH ORGAN there are critical windows of susceptibility
A baby is most likely to contract Congenital Rubella Syndrome (CRS) if he/she is exposed to Rubella in what trimester?
- highest risk: first trimester
- lowest risk: third trimester
What is the critical window in fetal development for Rubella to cause Congenital Rubella Syndrome (CRS)?
- 3-8 weeks
Signs of Congenital Rubella Syndrome (CRS):
- Mental Retardation
- Low Birth Weight
- Facial deformities
Congenital rubella syndrome [CRS] is the reason why what vaccine was developed?
- MMR
- contraindicated during pregnancy
Primary phenotypes of thalidomide toxicity during fetal development:
- Phocomelia (very short limbs)
- Syndactyly (webbing)
- Ear and eye defects
What is the critical window in fetal development for Thalidomide toxicity?
- 4-6 weeks
- upper limb development is 4-5 weeks
Mechanism of Thalidomide toxicity:
- Altered permeability of blood vessels
- Arrested development of critical blood vessels
Diseases Thalidomide is useful for:
- Multiple myeloma
- Leprosy
Diethylstilbestrol (DES) was originally marketed as:
- non-steroidal estrogen
- miscarriage prevention
Female offspring of diethylstilbestrol (DES)-treated mothers developed:
- clear-cell adenocarcinoma of the vagina shortly after the onset of the menarche
Critical period of maternal exposure to diethylstilbestrol (DES):
- First trimester during development of urogenital ridge
Endocrine Disruptors are:
- substances that interfere with normal hormone function.
- diethylstilbestrol (DES) is an endocrine disruptor.
In predatory birds, DDT caused:
- total reproductive failure
- anti-estrogenic effects on oviduct
- inhibited calcium deposition
What are the 5 routes of exposure to endocrine disruptors?
- food
- air
- dust
- soil
- water
Barker Hypothesis:
- stresses during development increase risks for certain diseases many years later
- adaptational responses reset “set points”
- i.e. malnutrition
“Critical periods” or “sensitive windows” are:
- points in development at which an insult (pharmaceutical, toxic or infectious) may have a specific, profound impact on certain targets that are vulnerable at that time.
The main exposure route of Methylmercury and PCBs is:
- consumption of fish
- mercury: predatory species such as tuna, shark, swordfish have highest mercury levels.
- PCBs: Great Lakes fish
Methylmercury interferes with:
- development of the nervous system both before and after birth.
- effects are mediated by impacts at the molecular level, including on microtubulin synthesis, neuronal migration, synapse formation
Elevated post-natal lead levels are associated with:
- reduced intelligence, poorer school performance, and higher delinquency
What is the most important exposure time period for lead?
- post-natal
Routes of lead exposure:
- paint chips
- leaded gasoline
- lead dust
- lead plumbing
A reference dose is:
- an amount of a substance that can be consumed on a daily basis without causing adverse effects.
Organophosphate pesticides can cause adverse effects on cognitive function and “intelligence” via:
- inhibiting acetylcholinesterase allowing acetylcholine to build up at neuronal junctions
Acetylcholinesterase inhibition by organophosphate pesticides disrupts:
- cell replication,differentiation, synaptogenesis, axonogenesis
What enzyme is involved in the metabolism of organophosphate pesticides?
PON1
Critical periods for methylmercury, PCBs, and Lead exposure:
- Methylmercury: prenatal
- PCBs: prenatal
- Lead: postnatal
Critical period for rubella/Congenital Rubella Syndrome (CRS):
first trimester (3-8 weeks)
Critical period for Thalidomide:
first trimester (4-6 weeks)
Critical period for Intrauterine Growth Retardation (IUGR):
second and third trimesters (16-38 weeks)
