Ocular: Corneal Metabolism And Enzymatic Activity Flashcards
What causes accumulation of lactic acid in the cornea?
Avid contact lens wear increases anaerobic conditions which leads to an increase in lactic acid
Does HMP shunt pathway produce ATP?
NO!
Photokeratitis (ultraviolet keratitis):
Painful eye condition caused by exposure of UV (natural or artificial) to insufficiently protected eyes
Response of cornea to low level UV exposure:
Inhibited cell mitosis
Response of cornea to medium to high level UV exposure
Swollen nuclei and cell death
Response of cornea to extreme level UV exposure
Complete sloughing of epithelia cells
When there are higher levels of UV damage, ____ contributes to the damage
O2
DNA UV light damage can cause _______________ more commonly called ______________
Pyrimidine dimers, thymine dimers
DNA repair mechanism for UV damage
UV specific endonuclease
Mechanisms of action of UV specific endonuclease:
-cuts DNA on both sides and removes damaged region
-gap filled by repair DNA polymerase
-ligase completes bond in DNA backbone
Xeroderma pigmentosum:
Rare genetic disorder resulting from deficiency in exonuclease and reduced ability to repair DNA damage
Symptoms of xeroderma pigmentosum:
-skin damage and increased cancer risk
-eyelid scarring
-corneal ulcerations
How does B-lysine function to kill a pathogen?
As a detergent that pokes holes in the cell membrane to release the bacterial cytoplasm to the external environment
What is the mechanism of Defensins?
Bind to microbial cell membrane and embeds within the bacterial cell membrane to forms a pores that allows efflux of ions and nutrients
Do Defensins polypeptides act as detergents?
NO
How do Defensins protect the eye?
By preventing bacterial growth in the tear film and ducts
Defensins-mimetics as drugs:
Small molecule structures that mimic Defensins in structure and activity
Where is lysozyme abundant?
Tears, saliva, human milk, and mucus
Lysozyme is an ____-__________ __________ apart of which immune system?
Anti-microbial enzyme, innate
What is the function of the lysozyme?
Cleaves the beta 1,4 linkages between petidoglycans in gram positive bacteria cell walls
What does lactoferrin bind to?
To iron and other metal ions
What is the mechanism of lactoferrin preventing infection?
By taking up nutrients that are needed for the bacteria to grow
How is lactoferrin associated with breast cancer?
Reduced level of lactoferrin means there is an increases risk of viral infection and thus an increased cancer risk
Lactoferrin can be detected in _____ and low levels of lactoferrin here can lead to ____ ____disease?
Tears, dry eye disease
