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Disease and Defense III > UV Radiation and DNA repair > Flashcards

UV Radiation and DNA repair Flashcards

1
Q

__________ radiation is responsible for most of the effects of the sunlight on the body?

A

uv-b

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2
Q

___ radiation is the main cause of sunburn and tanning

A

uv-b

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3
Q

___ radiation is main cause of formation of VitD3

A

uv-b

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4
Q

UV-B penetration

A

not fa - most is absorbed in the superficial tissue layers of 0.1mm depth

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5
Q

UVR effects on skin (6)

A

damage to DNA/RNA/protein/lipid

pro-inflammatory effects

immunosuppressive effects

induction of innate defense

induction of apoptosis

vitD synthesis

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6
Q

Most skin cancers are caused by?

A

UVA and UVB UV rays

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7
Q

UVB biological consequences?

A

eye problems

sunburns

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8
Q

UVB penetration?

A

just epidermis

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9
Q

UVA biological consequences?

A

dartk patches
wrinkles
loose skin
premature aging

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10
Q

UVA penetration?

A

through dermis

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11
Q

Erythema action spectrum is highest at?

A

low wavelength UVB (290nm) - so most sunburn is UVB dependent

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12
Q

melanoma

A

UVA and UVB

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13
Q

DNA damage primarily

A

UVB

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14
Q

NMSC?

A

mainly UVB

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15
Q

Erythema?

A

mainly UVB

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16
Q

Immune suppression?

A

mainly UVA

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17
Q

UVB affected cells?

A

kertinocytes
melanocytes
langerhaans

18
Q

UVA affected cells

A

In addition to those in epidermis (kertinocyte, melanocyte, langerhaans)
also those in dermis
- fibroblast
- vessle and CT damage

19
Q

what is present in skin that is converted to vitD3

A

7-dehydrocholesterol

20
Q

DNA damage indueced by UVR?
Thymine dimer?

Pyrimidine-6-4-pyrimidone?

Hydroxyguanosine (free radicals)?

A

UVB

UVB

UVA

21
Q

mainly responsible for oxidative damage and base modifications?

A

UVA

22
Q

mainly responsible for strand breaks / mutation / cell cycle changes

A

UVB

23
Q

Outcome of DNA damage to skin (3)

A

repair
induction of apoptosis
gene mutation
–> carcinogenesis initiation, transformtion, progression

24
Q

basal and apoptosis

A

more resistant

25
Q

What contributes to the erythema and oedema you seen in sunburn?

A

leukocyte extravasation and migration to the inflammatory sunburn
cytokines are induced by UVR

26
Q

UVR induces inflammation by?

A

mediated by primary and secondary cytokines as well as lipids - erythema and sunburn cells potentiate other types of cutaneous inflammation (adhesion molcules, induction, cytoine and chemokine release)

27
Q

Important mediators released by UVR

Primary cytokines?

A

IL-1a / TNF-a

28
Q

Important mediators released by UVR

Secondary cytokines?

A

IL-6, IL-8, IL-10, GM-CSF

29
Q

How does DNA damage via UVR cause immune suppression

A

via preferentially stimulating TH2 –> cytokine IL10 TNFalpha –> suupress cell induction?

30
Q

UVR and langerhaans

A

reduces langerhaans cell population

31
Q

UVR and inhibitory cytokine

A

IL10 / TH2

32
Q

Is UVR immunosuppression inhibited by high melanin content?

A

No - so it will not be affected by black vs white

33
Q

What does UVR immunosuppression potentiate?

A

induction of NMSC

34
Q

Skin defenses against UVR? (4)

A

DNA repair
Apoptosis
Defenses against ROS
Melanin

35
Q

________________ is a family of diseases in which genetic defects lead to premature aging of the skin and fatal induction of UVR induced skin cancer

A

xeroderma pigmentosum

36
Q

What activates DNA repair enzymes following exposure to UVR

A

p53 activation by UVR

37
Q

Defenses against ROS in epidermis?

A

peroxidase and catalase
superoxide dysmutase
glutathione reductase
thioredoxin reductase

38
Q

albinism

defective?

A

tyrosinase

39
Q

tyrosinase

A

converts tyrosine to dopa which is beginning of melanin production cascade

40
Q

Who knows to make more melanin?

A

surrounding keratinocytes are principle detectors of UVR adn they signal melanocytes to increase melanin production as well as melanocyte proliferation

41
Q

SPF refers to?

A

UVB rating

Disease and Defense III (11 decks)

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