DD - Ultraviolet Damage and Repair Flashcards
The UV spectrum is divided into (3)
UV-C (100 - 280 nm)
UV-B (280 - 320 nm)
UV-A (320 - 400 nm)
The _____ radiation is responsible for most of
the effects of sunlight on the body.
UV-B
UVR damage to skin includes
1) damage to DNA, RNA, lipids and proteins
2) pro-inflammatory effects
3) Immunosuppressive effects
3) induction of innate defenses
4) induction of apoptosis
5) Vitamin D synthesis
The main types of DNA damage resulting from UVR are?
- Thymine dimer (cyclobutane pyrimidine dimer) (UVB)
- Pyrimidine-6-4 pyrimidone (UVB)
- Hydroxyguanosine (UVA and singlet oxygen)
Melanoma
Non-melanoma Skin Cancer
Basal Cell Carcinoma
Squamous Cell Carcinoma
These are all?
ancers caused by UVR
Skin Defenses Against UVR
- DNA Repair
- Apoptosis of Cells with DNA Damage
- Defenses Against Reactive Oxygen
- Melanin
DNA repair process:
Excision of mutated strand of DNA
UVR ABC nuclease
Repair replication: DNA Polymerase
Rejoining: DNA Ligase
4 key enzymes are expressed in skin that help to detoxify free radical damage….
- Peroxidases and catalases
- Superoxide dysmutase
- Glutathione reductase
- Thioredoxin reductase
Situated in the basal layer of the skin
Deposit melanin into keratinocytes
One per 5 - 10 basal keratinocytes
Melanocytes
The paradox of ultraviolet light therapy for skin diseases
- Treatment of extensive psoriasis, atopic dermatitis
- Cutaneous T cell lymphoma
- Mastocytosis
- Repigmentation of vitiligo
SPF Sun Protective Factor refers to
UVB rating
- Damage to DNA, RNA, lipids, proteins
- Pro-inflammatory effects
- Immunosuppressive effects
- Induction of innate defenses
- Induction of apoptosis
- Vitamin D synthesis
UVR Effects on the Skin
UVR induces the non-enzymatic synthesis of cholecalciferol (VitD3) and _______
ergocalciferol (VitD2)
Outcome of DNA Damage
- Repair of Damage
- Induction of Apoptosis
- Gene Mutation
Carcinogenesis initiation, transformation and progression
Erythema, sunburn cells, potentiation of other types of cutaneous inflammation are?
UVR Proinflammtory effects
UVR induces the non-enzymatic synthesis of __________ and ergocalciferol (VitD2
cholecalciferol (VitD3)
UVR decrease in _______ populations
Langerhans Cell
Xeroderma Pigmentosum is a family of diseases in which genetic defects in _____
lead to premature aging of the skin and fatal induction of UVR-induced skin cancers
DNA repair
UVR Immunosuppression
Not inhibited by high melanin content
Potentiates induction of NMSC
DNA Ligase
DNA Repair Enzymes
Rejoining
DNA Polymerase
DNA Repair Enzymes
replication
Photodermatoses
a skin disease that is caused by exposure to sunlight.
skin rashes following exposure to the sun. Polymorphous Light Eruption is the most common type of photodermatosis.
Photodermatoses
Connective Tissue Disease
Lupus Erythematosus Dermatomyositis Mixed Connective Tissue Disease (MCTD or Sharp’s Syndrome)
Photodermatoses
-Idiopathic probably immunologic Solar urticaria, PMLE, actinic prurigo -DNA repair Defects Xeroderma pigmentosum -Chemical photosensitivity Drug induced Porphyria -Photoaggrevated dermatoses Psoriasis Atopic Dermatitis
Humans and mice: Oculocutaneous Albinism (OCA)
- OCA I: Tyrosinase
- OCA II: Pink
- OCA III: Tyrp 1
- OCA IV: MATP
UVR ABC nuclease
Excision of mutated strand of DNA
DNA Repair Enzymes
- Apoptosis of Cells with DNA Damage
- DNA Repair
- Defenses Against Reactive Oxygen
- Melanin
Skin Defenses Against Ultraviolet Radiation
Not inhibited by high melanin content
Potentiates induction of NMSC
UVR Immunosuppression
UVR decrease in Langerhans Cell populations by
migration
- Repair of Damage
- Induction of Apoptosis
- Gene Mutation
Carcinogenesis initiation, transformation and progression
Outcome of DNA Damage
- Thymine dimer (cyclobutane pyrimidine dimer) : UVB
- Pyrimidine-6-4 pyrimidone: UVB
- Hydroxyguanosine (UVA and singlet oxygen)
DNA Damage Induced by UVR
- Damage to DNA, RNA, lipids, proteins
- Pro-inflammatory effects
- Immunosuppressive effects
- Induction of innate defenses
- Induction of apoptosis
- Vitamin D synthesis
UVR Effects on the Skin