OB S- pellicle 2 Flashcards

1
Q

what is the enamel pellicle?

A

the layer of material acquired by a cleaned tooth

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2
Q

what is included in the enamel pellicle?

A
–  Mucins
–  Acidic Proline-rich proteins 
–  Statherin
–  Amylase
–  Lysozyme
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3
Q

what are mucin functions?

A
  • forming buffer between 2 surfaces
  • allowing movement of materials across and providing protection
  • tissue coating (aggregate microbes for removal and concentrates anti-microbial molecules at mucosal interface)
  • lubrication
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4
Q

Describe the bacterial interactions of MG1 .

A

– Attracts some species S. sanguinis, S. mitis & Actinomyces spp.
– Associated with soluble phase, and rapid flushing out of material

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5
Q

Describe the bacterial interactions of MG2.

A

– Attracts many bacterial species;
• S. sanguinis, S. gordonii, E. corrodens, S. aureus, P. aeruginosa
– Long protein core with short CHO chains that often end in sialic acid
• S. sanguinis, S. mitis (sialic acid adhesins)
– Neuraminidase cleaves sialic acid exposing galactose
– Galactose binding bacteria

(sides chains can be modified , can take carbohydrates which can be used as binding sites for certain bacteria (reveal sites)

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6
Q

Describe the proteolytic cleavage of MG2.

A

-peptides assessed in vitro kill bacteria (streptococci, P. gingivalis)
- potent anti fungal peptides characterised (kill azole & amphotericin B resistant Candida & Crytpotoccus sp.
, Crosses fungal membrane and accumulates within the cell, Effective in animal models of Candidiasis)

Cleavage that goes on can release antimicrobial properties

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7
Q

what does proteolytic cleavage cause a release of?

A

Release of peptides derived (in particular) from Acidic & Basic PRPs, Statherin & Histatins

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8
Q

Describe acidic (16kD) PRPs.

A
–  unique to saliva
–  affinity for hydroxyapatite
–  newly formed pellicle
–  important for Ca2+ & PO4- levels
–  degradation products (peptides) have antibacterial activity
-Conformational change 
- C-terminus exposed as receptor
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9
Q

Describe basic (6-9kD) PRPs.

A

– found in saliva & nasal/ bronchial secretions

– complex with tannin & tannic acid

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10
Q

Describe glycosylated (36kD) PRPs.

A

-newly formed pellicle
– bind to hydroxyapatite
– binds S. mutans efficiently

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11
Q

what do salivary proteins appear to be involved in?

A

Preventing or promoting bacterial adhesion to oral soft and hard tissues

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12
Q

What are PRPs strong promoters of?

A

bacterial adhesion:

  • Amino terminal :control calcium phosphate chemistry
  • Carboxy terminal :interaction with oral bacteria
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13
Q

Describe how interactions of oral bacteria with PRPs and other pellicle proteins is highly specific.

A

– Depends on proline-glutamine carboxy-terminal dipeptide
• e.g. P. gingivalis preference for HA coated with PRPs
– PRPs in solution do not inhibit adhesion of bacteria

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14
Q

What does statherin prevent?

A

both primary and secondary calcium phosphate disposition

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15
Q

what does Statherin aid?

A

Aids A. viscosus & F. nucleatum binding to HAp

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16
Q

What is the C-terminal of statherin involved in?

A

only upon binding to pellicle & conformational change

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17
Q

What are the functions of alpha- amylase?

A
•  α-amylase
–  α 1-4 glycosidic bonds
•  Digestivefunction
–  e.g. starch, amylose
•  Essential component of salivary pellicle
•  Bacterial Receptor
–  S. sanguinis, S. gordonii
•  Forms heterotypic mixed
micelle like structures
18
Q

what are glucans?

A

glucose polysaccharides with glucose molecules joined by 1,3-α- or 1,6-α- linkages

19
Q

Name water-soluble glucans with 1,6-α- links.

20
Q

Name water-insoluble glucans with 1,3-α- links and 1,6-α- links.

21
Q

Describe binding pellicle-attached glucosyltransferases .

A
  • Such immobilized enzymes are still active and continue to produce sticky polysaccharide
  • Bound GTFs also act as binding sites for bacterial adhesion
22
Q

what immunoglobulins are found in the pellicle?

A

IgA and IgG

23
Q

what immunoglobulin predominates?

A

IgA2 -shorter hinge resists proteases

24
Q

what does pellicle -attached immunoglobulins inhibit?

A

Inhibits growth of some species & contributes to adherence of other species

25
what underpins the idea of immunising against S.mutans?
presence of antiseptic paint
26
Describe cystatins.
• Inhibitors of cysteine proteases (e.g. bacterial & viral) • Include unique cystatins restricted to oral environment • Cystatin SA linked with pellicle formation & remineralisation • May function in control of periodontal disease • Protect other salivary proteins from degradation (protective role -reducing microbial population)
27
Describe histatins.
• Histidine rich cationic (+ve ) peptides – family of at least 12 (1,3&5major saliva forms) • Incorporated into acquired pellicle
28
What 2 properties does histatins have?
- antifungal properties | - antibacterial properties
29
Describe the antifungal properties of histatins.
– Histatin 5 anti-candidal | • binds receptor, target mitochondria, inhibit respiration & leads to production of reactive O2 species
30
Describe the antibacterial properties of histatins.
– bactericidal against S.mutans – Inhibits co-aggregation of P.gingivalis & S.mitis -Disrupt in vitro biofilms produced by a number of oral bacteria
31
Name other components of the pellicle.
• Lysozyme • Lactoferrin, – (globular protein with antimicrobial/antifungal properties) • albumin • Other bacterial enzymes & products
32
where is lysozyme present?
present in numerous organs and most body fluids
33
where is oral lysozyme derived from?
at least 4 sources: | -major and minor salivary glands, phagocytic cells and gingival crevicular fluid (GCF)
34
Describe the actions of lysozyme.
• Cleaves β-1,4 linkage between N- acetylmuramic acid (NAM) & N- acetylglucosamine (NAG) – Gram negative bacteria are generally more resistant due to outer LPS layer • Activates bacterial autolysins - ‘suicide packages’ (attacking cell wall and causing its degredation)
35
What is lactoferrin?
• Iron chelating glycoprotein – Single polypeptide, MW 80 kD – Member of transferrin family of iro-binding antibacterial proteins
36
what does lactoferrin have a high affinity for?
Fe+3
37
what is the principal action of lactoferrin?
blocks growth of iron dependent organisms with bacteriostatic effect
38
what does lactoferrin do?
– N-terminal peptide product of pepsin (contains no Fe binding sites). – Broad spectrum bactericidal, antiviral & antifungal – Binds to LPS & inhibits endotoxin activity
39
Describe antimicrobial activity of HOSCN/OSCN-
• Product of Salivary Peroxidase activity – Enzymes absorb onto Hydroxyapatite • Against a variety of microorganisms – e.g. S. mutans, lactobacilli, yeasts, even some viruses • Can oxidize sulfhydryl groups of enzymes • Block glucose uptake • Inhibit amino acid transport • Damage inner membrane, leading to leakage of cell • Disrupt electrochemical gradients • Inhibits hexokinase (essential for Glycolysis)
40
What are antimicrobial components of salvia?
``` • Lactoferrin • IgA • Mucins • Antimicrobial peptides • Enzymes – Lysozyme, glycosidases, peroxidase, esterase, transferase • Proteins – Glycoproteins – Statherins – Histidine-rich Proteins – Proline-rich Proteins ```
41
what binds carbohydrates and what does this allow?
Group of adhesins- called lectins , binding allows build up of bacteria, insoluble phae its good cause it collect bacteria for removal
42
Describe the stages of pellicle formation.
``` • Molecules attach immediately • 1-2 μMs thick before bacteria attach – 1 hour • Transition from pellicle to plaque – MG1, sIgA, lysozyme all bind to bacterial cell walls – Pioneer species – S. gordonii, S. sanguinis etc. • Rapid increase up to 2 hours • Slower growth until reaches 5-10 μMs ```