The Experts below are selected from a list of 63915 Experts worldwide ranked by ideXlab platform
H Mcgrath - One of the best experts on this subject based on the ideXlab platform.
-
Fluorescent Light activates the immunomodulator cis-urocanic acid in vitro: implications for patients with systemic lupus erythematosus.
Annals of the Rheumatic Diseases, 1994Co-Authors: H Mcgrath, J.m. Bell, John W HaycockAbstract:OBJECTIVE--Erythemagenic (295-305 nm) ultraviolet-B (UVB) radiation is toxic to patients with systemic lupus erythematosus (SLE). Cool white Fluorescent lamp emissions produce a similar toxicity even though the UVB radiation emitted is primarily at the relatively non-erythemagenic wavelength of 313 nm. The purpose of this study was to determine if Fluorescent Light, presumably acting predominantly along the 313 nm wavelength, exhibits photochemical activity sufficient to account for toxicity. METHODS--The photochemical activity of Fluorescent Light was assessed by testing its capacity to activate urocanic acid, a plentiful and potent epidermal immunological mediator normally activated by polychromatic UVB radiation but activated maximally at 313 nm. Irradiation-induced isomerisation of trans-urocanic to cis-urocanic acid was quantitated by UV spectroscopy after separation of the isomers by high performance liquid chromatography. RESULTS--Fluorescent Light irradiation of solutions containing the photoreceptor trans-urocanic acid produced a cumulative conversion of trans-to-cis-urocanic acid. This photochemical activity was compared with that of erythemagenic sunlamps, high in polychromatic UVB emissions. When normalised for UVB irradiance, the accumulation of cis-urocanic acid produced by both Light sources was essentially equivalent. Conventional acrylic diffusers that absorb UVB emissions eliminated the Fluorescent Light-induced reaction. CONCLUSION--The results indicate that radiation from Fluorescent lamps possesses substantial photoimmunological capability, sufficient to activate a potent, potentially dangerous, disease-modifying, immunomodulatory pathway and that poorly erythemagenic, primarily monochromatic UVB photons are responsible.
-
Fluorescent Light photosensitivity in patients with systemic lupus erythematosus.
Arthritis and rheumatism, 1992Co-Authors: Michael Rihner, H McgrathAbstract:Objective. To determine the prevalence of Fluorescent Light toxicity in patients with systemic lupus erythematosus (SLE). Methods. SLE patients were polled about their symptomatic responses to sunLight and cool white Fluorescent Light. Photometry was used to determine the levels of ultraviolet (UV) emissions from Fluorescent lamps. Results. Thirteen of 30 photosensitive SLE patients described increases in disease activity following exposure to unshielded Fluorescent lamps. Photometry indicated that these lamps emit substantial levels of UV-B (280–320 nm) radiation, which is toxic to patients with SLE. Standard acrylic diffusers absorbed this radiation, and their use was associated with almost no patient-reported problems. Conclusion. Fluorescent lamps, emitting UV-B radiation, induce disease activity in photosensitive SLE patients. Standard acrylic diffusers absorb UV-B radiation and appear to be protective against induction of disease activity with the use of Fluorescent lamps.
Tsang Cheung - One of the best experts on this subject based on the ideXlab platform.
-
Fluorescent Light effects on FWT-60 radiochromic film
Physics in medicine and biology, 2005Co-Authors: Martin J Butson, Tsang CheungAbstract:FWT-60 radiochromic film has been tested for colouration effects from Fluorescent Light sources and shown to produce a marked colouration when exposed to office Fluorescent Light sources showing an approximate 1 OD unit per 0.5 J m−2 exposure to a broad ultraviolet (UV) UVA + UVB spectrum at the peak absorption wavelength. This produces a measurable and quantifiable response to UV exposure. By choosing an appropriate wavelength of readout or band pass, the level of sensitivity can be changed to match the application or exposure level measurement required. These levels of UV response are significantly higher in sensitivity than other radiochromic films such as Gafchromic MD-55 by an order of magnitude. This feature may be of use for measurement of integrated UV exposure from Fluorescent Lights when required and produces a quantifiable history of total exposure.
-
Evaluation of a Fluorescent Light densitometer for radiochromic film analysis
Radiation Measurements, 2002Co-Authors: Tsang Cheung, Martin J ButsonAbstract:Abstract Radiochromic film dosimetry used in high energy X-ray detection has been evaluated using a VIDAR VXR-12 digitiser for accuracy and results are compared to other densitometers. The VIDAR scanner uses a broad band Fluorescent Light source which however, produces a negligible ultraviolet reaction effect on the radiochromic film with an estimated equivalent dose of 0.25 cGy darkening per scan to MD-55-2 film. By varying the exposure setting on the scanner, more accurate information can be obtained using radiochromic film within a certain optical density range. Over the range of 0– 20 Gy , the scanner can accurately measure dose with a standard deviation of 1.8% calculated between the measured values and a polynomial fit to data. The VIDAR scanner is shown to be a suitable densitometer for radiochromic film.
Martin J Butson - One of the best experts on this subject based on the ideXlab platform.
-
Fluorescent Light effects on FWT-60 radiochromic film
Physics in medicine and biology, 2005Co-Authors: Martin J Butson, Tsang CheungAbstract:FWT-60 radiochromic film has been tested for colouration effects from Fluorescent Light sources and shown to produce a marked colouration when exposed to office Fluorescent Light sources showing an approximate 1 OD unit per 0.5 J m−2 exposure to a broad ultraviolet (UV) UVA + UVB spectrum at the peak absorption wavelength. This produces a measurable and quantifiable response to UV exposure. By choosing an appropriate wavelength of readout or band pass, the level of sensitivity can be changed to match the application or exposure level measurement required. These levels of UV response are significantly higher in sensitivity than other radiochromic films such as Gafchromic MD-55 by an order of magnitude. This feature may be of use for measurement of integrated UV exposure from Fluorescent Lights when required and produces a quantifiable history of total exposure.
-
Evaluation of a Fluorescent Light densitometer for radiochromic film analysis
Radiation Measurements, 2002Co-Authors: Tsang Cheung, Martin J ButsonAbstract:Abstract Radiochromic film dosimetry used in high energy X-ray detection has been evaluated using a VIDAR VXR-12 digitiser for accuracy and results are compared to other densitometers. The VIDAR scanner uses a broad band Fluorescent Light source which however, produces a negligible ultraviolet reaction effect on the radiochromic film with an estimated equivalent dose of 0.25 cGy darkening per scan to MD-55-2 film. By varying the exposure setting on the scanner, more accurate information can be obtained using radiochromic film within a certain optical density range. Over the range of 0– 20 Gy , the scanner can accurately measure dose with a standard deviation of 1.8% calculated between the measured values and a polynomial fit to data. The VIDAR scanner is shown to be a suitable densitometer for radiochromic film.
John W Haycock - One of the best experts on this subject based on the ideXlab platform.
-
Fluorescent Light activates the immunomodulator cis-urocanic acid in vitro: implications for patients with systemic lupus erythematosus.
Annals of the Rheumatic Diseases, 1994Co-Authors: H Mcgrath, J.m. Bell, John W HaycockAbstract:OBJECTIVE--Erythemagenic (295-305 nm) ultraviolet-B (UVB) radiation is toxic to patients with systemic lupus erythematosus (SLE). Cool white Fluorescent lamp emissions produce a similar toxicity even though the UVB radiation emitted is primarily at the relatively non-erythemagenic wavelength of 313 nm. The purpose of this study was to determine if Fluorescent Light, presumably acting predominantly along the 313 nm wavelength, exhibits photochemical activity sufficient to account for toxicity. METHODS--The photochemical activity of Fluorescent Light was assessed by testing its capacity to activate urocanic acid, a plentiful and potent epidermal immunological mediator normally activated by polychromatic UVB radiation but activated maximally at 313 nm. Irradiation-induced isomerisation of trans-urocanic to cis-urocanic acid was quantitated by UV spectroscopy after separation of the isomers by high performance liquid chromatography. RESULTS--Fluorescent Light irradiation of solutions containing the photoreceptor trans-urocanic acid produced a cumulative conversion of trans-to-cis-urocanic acid. This photochemical activity was compared with that of erythemagenic sunlamps, high in polychromatic UVB emissions. When normalised for UVB irradiance, the accumulation of cis-urocanic acid produced by both Light sources was essentially equivalent. Conventional acrylic diffusers that absorb UVB emissions eliminated the Fluorescent Light-induced reaction. CONCLUSION--The results indicate that radiation from Fluorescent lamps possesses substantial photoimmunological capability, sufficient to activate a potent, potentially dangerous, disease-modifying, immunomodulatory pathway and that poorly erythemagenic, primarily monochromatic UVB photons are responsible.
Michael Rihner - One of the best experts on this subject based on the ideXlab platform.
-
Fluorescent Light photosensitivity in patients with systemic lupus erythematosus.
Arthritis and rheumatism, 1992Co-Authors: Michael Rihner, H McgrathAbstract:Objective. To determine the prevalence of Fluorescent Light toxicity in patients with systemic lupus erythematosus (SLE). Methods. SLE patients were polled about their symptomatic responses to sunLight and cool white Fluorescent Light. Photometry was used to determine the levels of ultraviolet (UV) emissions from Fluorescent lamps. Results. Thirteen of 30 photosensitive SLE patients described increases in disease activity following exposure to unshielded Fluorescent lamps. Photometry indicated that these lamps emit substantial levels of UV-B (280–320 nm) radiation, which is toxic to patients with SLE. Standard acrylic diffusers absorbed this radiation, and their use was associated with almost no patient-reported problems. Conclusion. Fluorescent lamps, emitting UV-B radiation, induce disease activity in photosensitive SLE patients. Standard acrylic diffusers absorb UV-B radiation and appear to be protective against induction of disease activity with the use of Fluorescent lamps.