teratology Flashcards

1
Q

teratology

A

-the study of the causes, mechanisms and manifestations of developmental deviations of structural or functional nature.

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2
Q

principle 1

A

susceptibility to teratogenesis depends on the genotype of the conceptus in a manner in which it interacts with adverse enviro factors.

-simple: enviro factors interact with fetus to form defect

gene- intrinsic
environment-extrinsic (even the mother if sick)

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3
Q

teratogens

A

-agents with interfere with normal development

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4
Q

principle II

A

-susceptible to teratogenesis varies with the developmental stage at the time of exposure to an adverse influence.

-stage of exposure at what stage of development matters

stages:
1 predifferentiation
2 early differentiation (most critical)
3 advanced organogenesis

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5
Q

manifestations of damage

A

-abortion (most common)
-early embryonic death
-sub lethal repair
-morph defects malformation (depends on # of cells that are destroyed)
-later pregnancy: growth retardation
-teratogens destroy cells

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6
Q

embryonic period

A

1st trimester: organ development, where you get fetal deaths and abortions, morph defects, malformations
2nd trimester: growth and maturation, less susceptibility, most susceptible
3rd trimester: less susceptibility, growth retardation, behavior effects (when nervous and immune system develops)

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7
Q

principle III

A

teratogenic agents act in a specific ways (mechanisms) on developing cells and tissues to initiate sequences of abnormal developmental events (pathogenesis)

-mechanism-> pathogenesis-> common pathway-> defect

some mechanisms: mutation, chromosomal abnormality, altered DNA

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8
Q

causes of abnormal embryogenesis

A

1 excessive cell death (underlying factor period) if they destroy enough cells can stop entire organ from forming cause absorption.
2 failure of cell interaction
3 mechanical disruption
4 reduced biosynthesis
5 impaired morph movement
6 altered differentiation schedules

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9
Q

sites of teratogenesis

A

1 fetus-direct
2 fetal-placental unit
3 mother- altered homeostasis
4 father-sperm

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10
Q

principle IV

A

the final manifestations of abnormal development are:
1 death
2 malformation
3 growth retardation
4 postnatal functional deficiency

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11
Q

principle V

A

The access of adverse influences (agents) to the developing tissues (fetus) depends upon the physical nature of the agent.

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12
Q

factors affecting fetal dose

A

1 maternal dose
2 maternal absorption rate
3 maternal metabolism
4 plasma half life
5 protein binding
6 placenta transfer
7 molecular weight (anything below 600 g is teratogenic)
8 charge (neutral toxins cross the placenta and are more teratogenic)

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13
Q

principle VI

A

-manifestations of abnormal development increase in frequency and degree with dose from the no effect level to the lethal zone.

-the teratogenic window is very small. maternal lethal zone and embryolethal zone are large.

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14
Q

manifestations of abnormal development are influenced by

A

dose
time
duration of exposure
species

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15
Q

genetic causes of abnormal development

A

-gene mutation
1 autosomal
2 sex linked: hemophilia
3 chromosomal abnormalities: chimerism

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16
Q

infectious causes of abnormal development

A

1 bluetounge virus: cattle sheep, embryonic death, resorption, arthrogyposis

2 BVD: absorption, early embryo death, placentitis, cerebellar hypoplasia

3 parvovirus: effects rapidly dividing cells in dogs and pigs.
1st trimester: reportion
2nd: abortion
3 few effects

4 feline panleukopenia virus:
death, ataxia, cerebellar hypoplasia, hydrocephalus.

17
Q

nutritional deficiencies causing fetal abnormalities

A

vitamin A: blind, micropthalmia, abortion, stillbirth, CNS, renal malformations

vitamin E/ Se: cardiomyopathy

minerals:
copper: enzootic ataxia
selenuium
magnese: cartilage
iodine: prolonged gestation, goiter, hairless

18
Q

veratrum calcification

A

-can cause cyclops, cleft palate, death, depends on time of exposure
-from alkaloids
-mechanism reduced cell mitosis/ migration reduced choncrocyte proliferation.

19
Q

lupines (crooked calf disease)

A

-arthrogryposis, cleft palate, spinal curvature, torticolis, scoliosis
-agent alkaloid, anagryrine

20
Q

tabacco (nicotiana)

A

pigs: cleft palate, arthrogyposis
-agent anabasine

21
Q

chemicals causing abnormalities vitamin A toxicity

A

-mechanim: interfers with neural crest cell migration
lesions: fatal resorption, cleft palate, micropthamia, spina bifida, heart, gi defects, most defects in the eyes
-toxicity occurs at therapeutic doses not high doses

22
Q

chemicals causing abnormalities albendazole

A

-mechanism: inhibits microtubule formation
-lesions: spina bifida, bone & kidney defects

23
Q

chemical organophosphate insecticides

A

-embryotoxic, fetotoxic
-mechanism: inhibit ach neutransmitter
-lesions: death of fetus or CNS, learning impairment, behavior change

24
Q

organochlorine insecticides (DDT, lidane)

A

-estrogenic mechanism leads to no implantation, resorption, reduced CL formation, reduced sperm

25
Q

griseofulvin

A

not species specific
-antifungal drug
-reduced microtubule and mitotic spindle function
lesions: absorption, bone, neural tube, cyclopia, anopthalmia

26
Q

cyanide (plant)

A

-mechanism: effects energy and oxygen utilization
-lesion: arthrogryposis, no limb movement in utero (involves limb movement or neuro= arthrogyposis)

27
Q

nitrates

A

-plant origin
-mech: methemoglobin formation and anoxia leads to abortion in fetus, dam is fine
-in drought stress crops, herd problem, cows can adapt if you build up to high nitrates over time

28
Q

mycotoxins causing abnormalities

A

-fungal metabolites

1 zeralenone: estrogenic
2 alfatoxin/ fimonsisns rapidly dividing cells
3 trichothecenes: DON, DAS, rapidly dividing cells,
4 dicoumerol: abortion, bleeding,
5 ergot: abortion, vasoconstriction, AGALAGTIA (no milk) impairs prolactin, and growth retardation in 3rd trimester.