Flashcards in Photobiology and Photosensitive dermatoses Deck (31):
What is included in optical radiation?
UV, visible light and infrared
UV radiation exists at wavelengths above/below that of visible light
What are the ranges of wavelengths for UVA, UVB, and UVC light?
What UV radiation causes aging?
What is minimal erythema dose (MED)
the minimal amount of a particular wavelength of light capable of causing redness of the skin
The effect of absorption depends on the _______, the molecule that absorbs light energy in the skin
a chromphore can absorb what kind of light rays?
UVA, UVB or both
What effects does UV light have on DNA?
UVB suppresses DNA synthesis which mediates anti-inflammatory effects on the skin
What effects does UV light have on melanin?
stimulates the melanocyte
What effects does UV light have on protein?
collagen and elastic fiber degeneration---> results in photoaging
What are often treated by laser therapies?
dyschromia and pigmented skin lesions
lasers that target water are specifically used for what kind of pathology?
What is a Fitzpatrick skin type IV?
never burns always tans
What is a Fitzpatrick skin type V
moderately pigmented skin
What does Immediate tanning result from ?
UVA exposure from the oxidation of melanin
What does Delayed tanning result from?
UVA and UVB exposure--> increased # of melanocytes, increased melanin synthesis and increased association of melanosomes with keratinocytes
What are the pro-inflammatory properties of UV exposure?
sunburns, phototoxic and photoallergic reactions
What are the anti-inflammatory properties of UV exposure?
used to treat dieases like psoriasis and atopic dermatitis
Describe some common features of phototoxic reactions
Manifested by redness, swelling, and burning/stinging
sun-protected sites are spared
onset within 24 hours
NOT immune related so may occur upon first exposure
What is Phytodermatisis?
occurs following exposure to caustic plant material coupled with UV light
plants may contain furocoumarins which is a photosensitizer
What is the differences between phototoxic reactions and photoallergic?
Photoallergic has delayed onset because it is immune related
Photoallergic has redness and itching
Phototoxic has redness, swelling and burning/stinging
What is a common causative agent of photoallergic reactions
What is the clinical presentation of PMLE
itching, edema, pink, papules coalescing into plaques and vesicles of sun-exposed skin
What is the treatment of PMLE?
avoid sun, topical corticosteroids, and possible phototherapy
What are some common features of XP
caused by impaired DNA nucleotides excision repair
30% risk to develop neurologic abnormalities
What is the phototherapy recommendation for psoriasis?
narrow band UBV (311nm)
What is psoralen?
medication that increases the absorption of UV light and the subsequent anti-inflammatory properties (most often used with UVA)
what are examples of physical blockers of sunscreen?
zinc oxide and titanium dioxide
What are UVA blockers?
Titanium dioxide/Zinc oxide
What are UVB blockers?
Titanium dioxide/ zinc oxide