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IBMS SR > Proteopathic diseases and amelogensis imperfecta II > Flashcards

Proteopathic diseases and amelogensis imperfecta II Flashcards

1
Q

what is amelogensis imperfecta

A

a group of developmental conditions that are genomic in origin which affects the structure and appearance of the enamel and nearly all of the enamel in every tooth

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2
Q

what is the prevalence of AI

A

1 in 700- 1 in 1400 depending on population

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3
Q

how can AI also be present

A

in cone rod dystrophy

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4
Q

in geneitcs how can AI be acquired

A

autosomal dominant
autosomal recessive
sex linked
and shows sporadic

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5
Q

phenotypes of AI

A

hyperplastic- pitting of enamel with an open bite
hypermineralised- rough soft enamel which is discoloured
hypermaturation- enamel normal thickness and very whiteish surface- can be mistaken as fluorosis

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6
Q

what is present in all cases of AI

A

in all cases teeth are sensitive, discoloured and prone to disintegration by post eruptive breakdown and idiopathic resorption

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7
Q

What are the key features of hyperplasia

A

pitting of enamel with open bite

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8
Q

what are the Key features of hyper-mineralisation

A

rough soft enamel which is discoloured

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9
Q

what are the Key features of hyper-maturation

A

normal thickness of enamel, whiteish enamel can be frequently mistaken for fluorosis
sensitive teeth

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10
Q

mutations in which genes are responsible for AI

A

amelogenin and enamelin

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11
Q

what is the wild type phenotype in mice

A

allele codes for phenotype most commonly

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12
Q

what has the Riken institute in Japan developed

A

a mass mutogenic library of mice

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13
Q

how have the Riken institute made this library

A

done this by feeding male mice ENUand this causes them to form point mutation and then interbreed with normal mice

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14
Q

what is ENU

A

ENU(N-ethyl-N-nitroso urea)- A HIGHLY POTENT MUTAGEN

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15
Q

how many dentitions do mice have

A

monophyodont dentition- only one permanent set of dentition

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16
Q

what is the mouse incisor characterised by on SEM

A

A herring-bow pattern with different levels of complexity

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17
Q

what allows the incisor to remain chiselled and sharp

A

the columnar and laminar structure of the HAP crystals which form rods with interods in between

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18
Q

what is the enamel characterised by

A

characterised by C axis hydroxyl ion where the Ca and Phosphate arrange

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19
Q

what is the enamel formation stages based on

A

tissue structure
histology of the adjacent enamel organ cells
enamel chemistry

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20
Q

what two stages are easily found

A

secretion stage

maturation stage

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21
Q

what are the characteristics of the secretion stage

A

characterised by:
secretion of matrix and the initial mineral phase and is complete when the full thickness of this complete tissue is deposited.

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22
Q

what are characteristics of the maturation stage

A

characterise by:
final matrix is removed and the final mineral content is acquired
complete when post eruption phase when it is not mediated by cells of the enamel organ

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23
Q

what stage is also included in the literature

A

transition phase( early maturation phase) between secretory and maturation

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24
Q

when does the transition phase occur

A

when the amelogenin is secreted

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25
how are the phases concerned
as discrete
26
what are the characteristics of the early maturation phase
the ameloblasts are long and columnar and around 7 microns in length the ER is also denser
27
what happens to the ameloblasts as the matrix is deposited in the maturation phase
the height of the ameloblasts decreases to around 3.5 microns in length the ER is less dense nucleus is also more in the centre of the cell
28
what is the mineral content in the secretion stage
around 30%
29
what is the mineral content in the early maturation stage
around 40%
30
what is the mineral content in the in the maturation stage
around 90%
31
what minerals increase in amount in the maturation stage
calcium and phosphate
32
what happens in the secretory stage
enamel proteins are secreted
33
what happens in the early maturation stage
enamel proteins stop being secreted
34
what happens in the maturation stage
proteins are removed and replaced by enamel
35
what is the enamel matrix mainly composed of
around 90% amelogenin
36
where is amelogenin found in chromosomes in humans
on the x chromosomes and Y
37
where is amelogenin found in chromosomes in rodents
on the x chromosome
38
if you have a heterozygous female rodent that reproduces what are the chances of getting AI
50% affected | 50% unaffacted
39
if you have affected male rodent that reproduces what are the chances of getting AI
100% affected
40
what does the enamel look like in 100% affected offspring from XY affected males
no enamel is formed just a thin layer of descript material on top of the dentine
41
what does the enamel look like in 50% affected offspring from XX affected female
enamel is formed but it is just abnormal
42
what is lyonisation
where one copy of the x chromosome is turned off- gives rise to banded enamel in HETEROZYGOUS females with X LINKED AI
43
What does the histology of the enamel look like in heterozygous amelogenin mutant females
we can see strong eosinophilic vesicles in the enamel of the ameloblasts more vascular in nature herring-bow structure of the tomes process is lost
44
what are the eosinophilic vesicles packed with
amelogenin and ameloblastin- the proteins co localised within the vesicles
45
where does the failure lie if mutant amelogenin is accumulating in the ameloblasts
in the secretory pathway
46
what accumulates in the ameloblasts
mutant amelogenin due to an error in the secretory pathway
47
what does amelogenin mutation cause
loss of normal ER and golgi structure and the ameloblasts become engorged and filled with amelogenin filled vesicles
48
what causes ER stress
mutant amelogenin buildup which leads to activation o the unfolded protein response
49
what does the upr end up causing
attempts to restore proteostasis but will tip towards apoptosis with increasing time and stress
50
what chemical is used also as a chaperone
phenylbuterate which can act as a chaperone and help to refold chemical misfoldings
51
what drug can be used to treat urea cycle disorders
phenylbuterate
52
what is phenylbuterate used to treat
urea cycle disorders
53
how can phenylbuterate help mince
the visual shoring showed a marked improvement on the incisors but not on the molars
54
what is the mechanism of AI recovery by phenylbuterate
the phenylbuterate chaperones the proteins and mitigates the stress leading to ameloblasts not dying and the monolayer is retained allowing for healthy enamel to form
55
how long does it take for the UPR to switch from survival mode to death mode
around 6 days- thats when cells undergo apoptosis
56
what do mice with the enamelin mutation( S55I) show
massive defects in the enamel | less mineral density along the incisor
57
what is shown in the heterozygous S55I mutation in mice in regards to mineral content
good mineral content around the incisal edge but poor at the beginning
58
what is shown in the heterozygous S55I mutation in mice in regards to mineral content
poor all along | and poor enamel all along
59
is there a statically difference in the fold change of ENAM HETERO AND ENAM HOMO in BIP
no statisical difference
60
is there a statically difference in the fold change of ENAM HETERO AND ENAM HOMO in CHOP
statistical difference
61
what does the mutation in ENAM S55I show
that it inhibits the ameloblasts secondary pathway and leading to ER stress and the UPR which leads to slight recovery and the deposition of normal enamel but the enamel secreted after was abnormal
62
what can fluoride trigger
an unfolded protein response which could trigger ameloblast function and or survival and lead to fluorotic enamel defects causing fluorosis it doesnt cause protein misfolding just activates in some way

IBMS SR (38 decks)

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