TY  - CHAP
M1  - Book, Section
TI  - Chapter 90. Fundamentals of Cutaneous Photobiology and Photoimmunology
A1  - Kochevar, Irene E.
A1  - Taylor, Charles R.
A1  - Krutmann, Jean
A2  - Goldsmith, Lowell A.
A2  - Katz, Stephen I.
A2  - Gilchrest, Barbara A.
A2  - Paller, Amy S.
A2  - Leffell, David J.
A2  - Wolff, Klaus
PY  - 2012
T2  - Fitzpatrick's Dermatology in General Medicine, 8e
AB  - |PrintFundamentals  of  Cutaneous  Photobiology  and  Photoimmunology  at  a  GlanceWhen  radiation  enters  the  skin,  it  is  scattered  or  absorbed.  Only  light  absorbed  by  molecules  (chromophores)  in  the  skin  can  cause  a  photobiologic  response.Electromagnetic  radiation  can  be  conceptualized  either  as  a  wave  or  as  packets  of  energy  called  photons.An  action  spectrum  indicates  which  wavelengths  produce  a  photobiologic  response  most  effectively  and  is  plotted  as  the  reciprocal  of  the  minimum  effective  fluence  versus  wavelength.The  most  erythemogenic  wavelengths  present  in  sunlight  are  in  the  ultraviolet  B  (UVB)  range.  Ultraviolet  A  (UVA)  is  roughly  1000-fold  less  effective  than  UVB.Prostaglandins  and  nitric  oxide  appear  to  be  the  major  mediators  for  UVB  erythema.When  certain  drugs  and  dyes  absorb  UV/visible  light,  inflammation  ensues.  This  is  called  photosensitization.Photosensitivity  responses  are  usually  mediated  by  reactive  oxygen  species.Blocked  by  sunscreen  use,  cutaneous  vitamin  D  production  is  mediated  by  wavelengths  from  295–300  nm.  Optimal  vitamin  D  blood  levels  are  essential  for  good  bone  health  and  increasingly  associated  with  a  myriad  of  other  potential  health  benefits.Ultraviolet  radiation  is  immunosuppressive.  Local  and  systemic  immunosuppressions  are  recognized.Pyrimidine  dimers,  reactive  oxygen  species  and  urocanic  acid  initiate  UV-induced  immunosuppression.Interleukin-10  (IL-10),  tumor  necrosis  factor  (TNF)-α,  platelet-activating  factor,  platelet-activating  factor-like  lipids  and  other  molecules  mediate  photoimmunosuppression.The  major  cellular  players  in  UV  immunosuppression  are  Langerhans  cells,  keratinocytes,  macrophages,  and  T  cells.UV  radiation  impairs  T  helper  1-mediated  cellular  immune  response.  
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PB  - The McGraw-Hill Companies
CY  - New York, NY
Y2  - 2024/04/24
UR  - accessmedicine.mhmedical.com/content.aspx?aid=56050969
ER  -