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FD9 > 17 - Cutaneous Photobiology > Flashcards

17 - Cutaneous Photobiology Flashcards

(68 cards)

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1
Q

Radiation can only cause a photobiologic response if

A

It is first absorbed by a molecule (chromophore) in the skin

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2
Q

UV-signature mutations

A

C to T and CC to TT mutations at dipyrimidine sites

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3
Q

Y/N: Photoaging is reversible.

A

No

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4
Q

Carries sufficient photon-energy to completely remove an electron from an atom or molecule

A

Ionizing electromagnetic radiation

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5
Q

Examples of ionizing electromagnetic radiation

A

X-rays

Gamma rays

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8
Q

Shortest wavelength of solar electromagnetic radiation reaching the earth’s surface

A

290 nm

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9
Q

Y/N: Longer wavelengths of UVR are highly damaging to animals and plants

A

No - shorter wavelengths

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10
Q

Energy (increases/decreased) with increasing wavelength

A

Decreases

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11
Q

ROYGBIV is arranged according to increasing

A

Wavelength

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12
Q

Spectrum of electromagnetic radiation from lowest to highest energy

A 
Radio waves
Infrared
Visible
Ultraviolet
X-rays
Gamma rays

Roman men Invented Very Unusual Xray Guns

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13
Q

(Shorter/longer) wavelengths of visible light are more filtered by a linger passage through the atmosphere

A

Shorter

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14
Q

Fraction of UVA relative to UVB (increases/decreases) with lower angles of solar radiation

A

Increases

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15
Q

Y/N: UVA and UVB are less abundant early or late in the day

A

Yes

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16
Q

States that light must be first absorbed by a chemical substance for a photochemical reaction to take place

A

Grotthuss-Draper law

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17
Q

One wavelength that is most likely to excite a chromophore

A

Absorption maximum

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18
Q

Well characterized chromophores in the skin (3)

A

DNA
Porphyrins
Melanin

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19
Q

Process in which energy from an excited chromophore is transferred to another molecule

A

Photosensitized reaction

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20
Q

States that the wavelength of fluorescence is always longer (=less energetic) than the exciting wavelength

A

Stokes law

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21
Q

Photon emission from return of triplet excited states to ground states

A

Phosphorescence

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22
Q

Major role of vitamin D

A

Increase the flow of calcium into the bloodstream

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23
Q

Safe upper limit for adult intake of vitamin D

A

10,000 IU/day

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24
Q

Chronic toxic dose of vitamin D

A

50,000 IU/day

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25
Q

When obtained from food or supplements, vitamin D is absorbed in the

A

Small intestine

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26
Q

Central role in photoaging

A

UVA

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27
Immediate erythema and pigment darkening
UVA
28
Major role in drug induced photosensitivity
UVA
29
Major role in carcinogenesis
UVB
30
Role in vitamin D production
UVB
31
25(OH)D-1alpha-hydroxylase activity is increased by (2)
Parathyroid hormone | Low phosphate
32
In tropical areas, adequate amounts if vitamin D3 can be made in the skin with
10 to 15 minutes of biweekly sun exposure to the face, arms and hands, or the back
33
Most of the immunosuppressive effects of UVR are caused by
UVB
34
Chromophore for the sunburning and tanning reaction
DNA
35
Plant-based chromophores related to psoralens
Furocoumarins
36
Chromophore is the perfume ingredient bergamot oil (5-methoxy psoralen)
Berloque dermatitis
37
Most common indication for phototherapy
Psoriasis
38
Chromophore that mediates the antipsoriasis therapeutic efficacy
DNA
39
Much less energetic and produces much less pyrimidine dimers (UVA/UVB)
UVA
40
Chromophore that mediates the therapeutic effect of PDT
Protoporphyrin IX
41
Can penetrate through window glass
UVA
42
Almost monochromatic emissions at 311-312 nm
Phillips TL01 fluorescent lamp
43
Protoporphyrin is most effectively excited by (blue/red light)
Blue light
44
Deeper penetration of PDT with (blue/red light)
Red light
45
PDT modality more effective for thicker skin lesions, for example, infiltrating skin cancers
Methyl aminolevulinic acid (MAL) with red light
46
Y/N: Photoabsorbing molecules are usually larger and aromatic and are therefore less likely to be internalized by cells
Yes Except chromophore of current PDT
47
Two main types of DNA photoproducts
Cyclobutane pyrimidine dimers | 6,4-pyrimidine-pyrimidone photoproducts
48
Absorption maximum of DNA
260 nm
49
SCC and AK genetic mutations
p53
50
BCC genetic mutations
Sonic hedgehog signaling pathways (ptch, shh, smo) | p53
51
Melanoma genetic mutations
CDKN2A PTEN TERT promoter p53
52
Mechanisms by which UVR induces formation of pyrimidine dimers (2)
Direct absorption of photons by DNA bases | Photoexcitation of melanin, particulary pheomelanin leading to formation of "dark cyclobutane pyridimine dimers"
53
Non-exposed cells in the vicinity of irradiated cells also demonstrate stress responses similar to exposed cells
Bystander effect
54
Most of the oxidative DNA damage after exposure to natural sunlight is caused by
UVA
55
Much higher abundance in natural sun (UVA/UVB)
UVA
56
Generating the majority of solar radiation-induced pyrimidine dimers (UVA/UVB)
UVB
57
Does not induce a robust cellular DNA damage response (UVA/UVB)
UVA
58
Melanomas that are not UVR-induced
Mucosal | Acral
59
Melanomas on chronically sun-damaged skin often arise from
Lentigo maligna
60
Non-chronically sun-damaged skin melanomas are most common on the _____ in wowen and on the _____ in men
Lower legs | Back
61
Damaged nucleotide is removed and | replaced with undamaged DNA
Nucleotide excision repair
62
Defects in nucleotide excision repair genes can cause
Xeroderma pigmentosum | Cockayne syndrome Trichothiodystrophy
63
Simpler type of DNA damage involving chemical changes in a single DNA base
Oxidative base modifications
64
DNA repair pathway for oxidative base modifications
Base excision repair
65
Guardian of the genome
Tumor suppressor p53
66
Group of cysteine proteases that are central regulators of apoptosis
Caspases
67
Only nonproliferative feature of photoaged skin that is not observed in intrinsically aged skin
Actinic elastosis
68
Accumulation of fibrillary basophilic material in the upper and middermis
Actinic elastosis
69
Progerin is found in high concentrations in cells from patients with
Hutchinson Gilford progeria
70
Advantage of MAL vs 5-ALA
Better uptake into cells because of is more lipophilic properties

FD9 (108 decks)

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