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ODDR Basic Science > Biochemistry of the Periodontal Ligament in Health and Disease 2 > Flashcards

Biochemistry of the Periodontal Ligament in Health and Disease 2 Flashcards

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1
Q

Which cells produce collagenase in HEALTH?

A

Fibroblasts

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2
Q

Which cells produce collagenase in DISEASE?

A

polymorphonucleocytes
macrophages
Some bacteria can also secrete collagenase

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3
Q

Name the enzyme that breaks down collagen

A

Collagenase

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4
Q

What type of enzyme is collagen?

A

It is a matrix metalloprotease (MMP)

It is an Endopeptidase

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5
Q

Describe the optimum conditions for collagenase to work at

A
  1. Neutral pH
  2. Need Calcium ions
    3, Need six ions
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6
Q

In what form do cells secrete collagenase in?

A

They secrete it in its inactive precursor form

This needs to be self activated after secretions

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7
Q

How is collagenase turned off after it has been activated?

A

By a small peptide called tissue inhibitor of metalloproteases (TIMP)

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8
Q

What is TIMP produced by?

A

By the cells that secrete collagenase

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9
Q

What does TIMP synthesis regulate?

A

Will regulate collagen degradation within a tissue

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10
Q

What link has been suggested between TIMP and periodontal disease?

A

there has been some suggestion that TIMP may be downregulated in certain patients tipping the balance towards periodontal breakdown.

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11
Q

What does collagenase do?

A

It cleaves collagen molecules within their length in to three quarter and one quarter length fragments

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12
Q

Which enzyme hooks collagenase to break down collagen?

A

gelatinases

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13
Q

What do gelatinases do?

A

They take over and degrade the collagen fragments completely.

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14
Q

How quickly does collagen turnover occur?

A

In less than an hour

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15
Q

Which has the quickest turnover:
Skin
PDL
Gingiva?

A

PDL

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16
Q

How much faster is collagen synthesis in PDL compared to subdermal gingiva?

A

2 times

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17
Q

How much faster is collagen synthesis in PDL compared to Skin

A

4 times faster

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18
Q

How much faster is collagen synthesis in PDL compared to Alveolar bone?

A

6 times fater

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19
Q

How much faster is collagen breakdown in PDL compared to the gingiva?

A

5 time faster

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20
Q

How much faster is collagen breakdown in PDL compared to skin?

A

15 times faster

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21
Q

How much faster is collagen breakdown in PDL compared to alveolar bone

A

6 times faster

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22
Q

What is the half life of collagen in the PDL, gingiva and skin

A

PDL: 40 mins
Gingiva: 80 mins
Skin: 360 mins

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23
Q

What model can we use to help us understand disease progrssion within the periodontal ligament ?

A

By using sheep

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24
Q

What do some sheep suffer from?

A

A condition called broken moth

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25
Q

What is broken mouth clinical similar to?

A

To rapidally progressing periodontitis in men

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26
Q

What happens ti sheep suffering from broken mouth?

A

Their quickly lose their lower teeth

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27
Q

What happen to the amount of collagen in sheep suffering from broken mouth?

A

there was an overall loss of collagen from the gingiva and periodontal ligament with disease

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28
Q

Loss of collagen from the gingiva and PDL results in what?

A

Accounts for the loss of attachment and increased pocket depth

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29
Q

What happens to the activity of gelatinase in sheep suffering from broken mouth?

A

There was an increased activity of the enzymes in the diseased tissue

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30
Q

What does increased activity of gelatinase lead to?

A

greater degradative activity of collagen if gelatinase activity increases

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31
Q

What 3 things did scientist look at in sheep with broken mouth disease?

A

Gelatinase enzyme activity
Collagen levels
GCF was tested

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32
Q

What were scientist looking fro when they tested the GCF of disease sheep?

A

looked for evidence of any collagen fragments that might be present in the sulcus

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33
Q

What was the underlying hypothesis scientists were working around when they were looking at sheep with broken mouth disease?

A

The underlying hypothesis was that if there is increased collagen degradation occurring during episodes of active periodontal disease, then some of those fragments might “wash out” in to the gingival crevice due to the increase fluid outflow that occurs with gingival inflammation.

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34
Q

What did southern blotting of the GCF in sheep with broken mouth disease show?

A

detected fragments of collagen in the crevicular fluid of diseased animals but not in healthy animals.

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35
Q

Has a strong correlation between PDL conditions in sheep with broken mouth disease and humans with periodontitis been found?

A

No a strong correlation has not been found

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36
Q

Where is the ground substance found?

A

It is present as the cement around the fibres in all connective tissues, including periodontal ligament

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37
Q

What does the ground substance comprise of?

A
  1. Non-collagenous proteins (NCPs)
  2. Hyaluronic Acid (GAG)
  3. Proteoglycans (PGs)
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38
Q

Give an example of a non collagenous protein?

A

fibronectin which is a glycoprotein

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39
Q

What does fibronectin do?

A

It acts as a linker for cells to their underlying matrix, providing an anchor.

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40
Q

What are proteoglycans made up of?

A

Proteoglycans are made up of a protein core to which is attached a chain(s) of glycosylaminoglycans (GAGs)

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41
Q

What are glycosylaminoglycans?

A

GAGs are carbohydrate heteropolymers, made up of repeating disaccharide sub-units. Each disaccharide sub-unit is comprised of a hexosamine sugar plus a uronic acid residue

42
Q

Are glycosylaminoglycans hydrophilic or hydrophobic?

A

They are highly HYDROPHILIC and attract and bind many water molecules as part of their extended structure

43
Q

What does each disaccharide sub unit in a glycosylaminoglycans comprise of?

A

uronic acid residue

a hexosamine residue (which is subject to modification )

44
Q

What 2 forms can chondroitin sulphate exist in?

A

chondroitin-6-sulphate

chondroitin-4-sulphate

45
Q

What is the difference between chondroitin-6-sulphate and chondroitin-4-sulphate?

A

In chondroitin-6-sulphate the sulphate ion is attached to the 6th carbon
In chondroitin-4-sulphate the sulphate ion is attached to the 4th carbon

46
Q

Which if the 2 forms of chondroitin sulphate is more abundant in hard tissue?

A

Chondroitin-6-sulphate

47
Q

Which if the 2 forms of chondroitin sulphate is more abundant in the PDL?

A

Chondroitin-4-sulphate

48
Q

Name the 2 GAGs we need to know

A

chondroitin sulphate

dermatan sulphate.

49
Q

What is the difference between chondroitin sulphate and dermatan sulphate?

A

the form of uronic acid in dermatan sulphate is an epimer called iduronic acid

50
Q

What are proteoglycans?

A

GAGs that are covalently attached to a protein core

51
Q

What are proteoglycans aggregates?

A

They are huge aggregated macromolecular structures that arise when proteoglycans have associated non covalently to hyaluronic acid via interactions with small linker proteins

52
Q

What does the number do GAG side chains bound to a single protein core depend on?

A

depends upon the specific proteoglycan

53
Q

What was the first really well reported proteoglycan structure called?

A

Aggrecan

54
Q

Where is aggrecan found?

A

In cartilage

55
Q

Describe what aggrecan is

A

It is a large, aggregating proteoglycan that looks like a bottle brush structure under the transmission electron microscope

56
Q

What is aggrecan responsible for?

A

for conferring the stiffness/compressive properties of the tissue due to its ability to bind large amounts of water.

57
Q

What type of proteoglycans do connective tissues contain?

A

both small (unaggregated) and large (usually aggregated) proteolycans.

58
Q

Name the 2 SMALL proteoglycans found most abundantly in the PDL

A

mainly two small leucine-rich proteoglycans

decorin and biglycan

59
Q

What is decorin?

A

is a small proteoglycan that is rich in dermatan sulphate GAGs

60
Q

Name the BIG proteoglycans found most abundantly in the PDL

A

Versican

61
Q

What is Versican?

A

A large proteolglycan that is rich in chondroitin sulphate.

62
Q

Describe the protein cores of small proteoglycans

A

They contain relatively large amounts of the amino acid leucine
They have a relatively low molecular weight

63
Q

What are small proteoglycans sometimes referred to as?

A

Small Leucine Rich Proteoglycans (SLRPs)

64
Q

Why are proteoglycans referred to as Small Leucine Rich Proteoglycans (SLRPs)

A

Because they have a relatively large amounts of the amino acid leucine

65
Q

Do small proteoglycans (SLRPs) aggregate?

A

They tend not to aggregate

66
Q

How many GAG side chains does decorin have?

A

1 called dermatan sulphate

67
Q

Where is biglycan more abundant?

A

In the alveolar bone

68
Q

How many GAG side chains does biglycan have ?

A

2

either both chondroitin sulphate or one hondroitin sulphate and the other dermatan sulphate.

69
Q

Describe versicans protein core

A

Many GAGchains are attached to it

It is bigger than decorin

70
Q

List the functions of proteoglycans and GAGs in connective tissues

A
  1. Collagen fibril orientation/diameter
  2. Control of Mineralisation
  3. Generation of the Eruptive Force
71
Q

What do proteoglycans have the ability to bind to?

A

Collagen

72
Q

How does decorin interact with collagen?

A

Decorin is able to interact closely with collagen fibrils and regulate their growth and hence their final fibril diameter within the tissue

73
Q

Where is Dermatan sulphate found?

A

Mainly in decorin

74
Q

What is Dermatan sulphate associated with in regards to collagen?

A

It is associated with large collagen fibrils (200 – 300 nm in diameter)

75
Q

What is chondroitin sulphate associated with in regards to collagen?

A

associated with small fibrils

76
Q

What did Parrys investigations show about collagen fibres?

A

he found that as the tissue aged and became fully functional, the average size of collagen fibrillar diameters increased from around 50 nm to over 300 nm.
This was associated with a ten fold decrease in the amount of glycosylaminoglycan within the same tissues.

77
Q

According to Parrys investigation what happens to the number of Dermatan sulphate as we age?

A

It increases with tissue age

Becomes the most abundant GAG (80% of all tissue GAG present)

78
Q

According to Parrys investigation what happens to the number of Chondroitin sulphate as we age?

A

Almost all chondroitin was lost in mature tissue, when collagen fibrils were large.

79
Q

What are proteoglycans responsible fro directing with regard to collagen fibrils?

A

Proteglycans are responsible for directing the orientation of collagen fibres throughout the tissue (important for tissue function)

80
Q

What process do proteoglycans control? (in regards to collagen fibril orientation)

A

fibrillogenesis

81
Q

How do proteoglycans control fibrillogenesis?

A

via their ability to bind to

collagen fibrils.

82
Q

What is a high GAG content associated with?

A

is associated with unimodal

distribution of small fibrils

83
Q

In what tissue age is Chondroitin sulphate mainly found?

A

In foetal tissue

84
Q

What can GAGs inhibition’s in skeletal tissue?

A

GAGS are able to inhibit the nucleation and deposition of the hydroxyapatite crystals that make up the mineral component of skeletal tissues.

85
Q

What determines the extent to which a GAG can interfere/prevent mineralisation?

A

Depends upon:
the type of GAG
its surrounding environment
what type of proteoglycan it is present in

86
Q

What can some GAGs induce that may affect mineralisation of skeletal tissue?

A

Some GAGs can induce mineralisation ions and preventing their precipitation and/or their ability to bind to collagen, preventing other proteins nucleating crystals by acting as mask.

87
Q

What may the ability of GAGs being able to inhibit and control mineralisation be related to ?

A

their high negative charge binding mineral

88
Q

How do GAGs control mineralisation?

A

GAGs can inhibit deposition of hydroxyapatite crystals in

soft connective tissues

89
Q

What does the removal of GAGs from the PDL lead to?

A

leads to deposition of

hydroxyapatite crystals in and around collagen fibrils

90
Q

Why are proteoglycans and GAGs need for tooth eruption?

A

GAGs may be responsible, at least in part, for generation

of the forces required for tooth eruption.

91
Q

What may the ability of proteoglycans and GAGs being able to produce a strong eruptive force be related to?

A

their highly charged structure and the fact that they are very hydrophilic

92
Q

How does being hydrophilic help proteoglycans and GAGs to produce a strong eruptive force?

A

They attract water molecules and are potentially capable of generating a significant hydrodynamic force.

93
Q

What is increased tooth eruption associated with?

A

increased GAG (and therefore increased proteoglycan),

94
Q

What happens to the amount of collagen when someone gets periodontal disease?

A

It decreases

95
Q

What happens to the total GAG content in the PDL of a sheep with periodontal disease?

A

It increases

96
Q

What happens to the total Dermatan sulphate content in the PDL of a sheep with periodontal disease?

A

It decreases

97
Q

What happens to the total Chondroitin sulphate content in the PDL of a sheep with periodontal disease?

A

It increases

98
Q

What happens to the total decorin content in the PDL of a sheep with periodontal disease?

A

It decreases

99
Q

What happens to the total Versican content in the PDL of a sheep with periodontal disease?

A

Increases

100
Q

GAGs that are covalently attached to a protein core are called what?

A

Proteoglycans

101
Q

Name the structure that forms when proteoglycans associate non covalently to hyaluronic acid via interactions with small linker proteins

A

proteoglycans aggregates

102
Q

Summarise how the biochemistry of the PDL changes with periodontal disease?

A
  1. Total sulphated GAG content increases
  2. Percentage of Dermatan sulphate decreases
  3. Decorin decreases
  4. Percentage of Chondroitin sulphate increases
  5. Versican increases
  6. Collagen content decreases
  7. Gelatinase activity increases

ODDR Basic Science (2 decks)

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