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Skobowiat C.,University of Memphis | Sayre R.M.,Rapid Precision Testing Laboratories | Sayre R.M.,University of Memphis | Dowdy J.C.,Rapid Precision Testing Laboratories | Slominski A.T.,University of Memphis
British Journal of Dermatology | Year: 2013

Background 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1), 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), and glucocorticoids (GC) and their receptor (GR) play a key role in tissue-specific regulation of GC action. Objectives To determine the expression of genes encoding 11β-HSD1 (HSD11B1), 11β-HSD2 (HSD11B2) and GR (GRa; also known as NC3R1) and their protein products, and levels of cortisol in human skin explants and/or cocultured keratinocytes/melanocytes after treatment with ultraviolet (UV) A, B or C wavebands. Methods Skin from foreskins and/or cocultured human keratinocytes/melanocytes were irradiated with UVA, UVB or UVC (skin) and incubated for 12 and 24 h. Methods of reverse transcription- polymerase chain reaction, Western blotting, enzyme-linked immunosorbent assay and immunohistochemistry (IHC) were used to determine expression and localization of corresponding genes or antigens. Results UVB enhanced the HSD11B1 gene and protein expression in a dose-dependent manner, while UVA had no effect. Similarly, UVC increased 11β-HSD1 protein product as measured by IHC. UVB and UVC enhanced cortisol production and decreased epidermal GR expression, while UVA had no detectable effects. Although both UVA and UVB stimulated HSD11B2 gene expression, only UVA increased 11β-HSD2 protein product levels with UVB and UVC having no effect. Conclusions We suggest that these differential, waveband-dependent effects of UV radiation on the expression of cutaneous HSD11B1, HSD11B2 and GRa genes and their corresponding protein products, and cortisol production are to protect and/or restore the epidermal barrier homeostasis against disruption caused by the elevated cortisol level induced by UVB and UVC. © 2012 British Association of Dermatologists.


Sayre R.M.,University of Tennessee Health Science Center | Sayre R.M.,Rapid Precision Testing Laboratories | Dowdy J.C.,Rapid Precision Testing Laboratories | Gottschalk R.W.,Galderma Laboratories L.P.
Journal of Cosmetic and Laser Therapy | Year: 2011

This report documents the optical characteristics of a number of photodynamic therapy (PDT) light sources of varied types, measured and indexed relative to estimated effectiveness for activation of the PDT chromaphore protoporphyrin IX (PpIX). PDT sources in use at several clinics, including intense pulsed light (IPL) sources, lasers, and continuous wave (CW) light sources, were spectroradiometrically measured and indexed relative to their overlap to an absorption spectrum of PpIX. The sources were highly disparate, varying in power from irradiance in the mW/cm 2 range for the CW sources up to ∼30 J/cm 2 per flash for the IPL sources. Our PpIX Index ranged by a factor of nearly 100 (0.0080.630) in estimated PpIX PDT effectiveness following the distinct spectral characteristics of the light sources surveyed. Application of this PpIX Index, tempered with an understanding of the biology of the lesion being treated and effective spectrum of the light source reaching the lesion requiring therapy, provides a rational algorithm to approximate equivalent light doses prior to clinical protocols to establish equivalent patient outcomes employing alternative PDT light sources. © 2011 Informa UK, Ltd.


Dowdy J.C.,Rapid Precision Testing Laboratories | Sayre R.M.,Rapid Precision Testing Laboratories | Sayre R.M.,University of Tennessee Health Science Center | Sayre R.M.,University of Memphis
Photochemistry and Photobiology | Year: 2013

We evaluated six UV nail lamps representative of major US manufacturers to evaluate radiant hazards as defined in ANSI/IESNA RP-27 Recommended Practice for Photobiological Safety. Lamps were evaluated at three positions, 1 cm above the inner surface approximating exposure to the hand and the 20 cm RP-27 non-general light source distance, oriented normal and 45° to the opening. Hazard to skin at intended use distance classified these devices into Risk Group 1 or 2 (Low to Moderate) with S(λ) weighted Actinic UV ranging 1.2-1.7 μW cm-Â and 29.8-276.25 min permissible daily exposure. At 20 cm on center and 45° UV risk to skin and eyes were all within Exempt classification. Actinic UV ranged 0.001-0.078 μW cm-Â and unweighted near UV (320-400 nm) ranged 0.001-0.483 mW cm-Â. Likewise the retinal photochemical blue light hazard and retinal thermal and cornea/lens IR were also Exempt. One device had aphakic eye hazard slightly rising into Risk Group 1 (Low). There were no other photobiological risks to normal individuals. Total exposure following programmed times and steps accumulate to only a small fraction of RP-27 permissible daily occupational exposure. These risks are further mitigated in realistic nonoccupational use scenarios as it is unlikely to be a daily occurrence. © 2013 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2013 The American Society of Photobiology.


Dowdy J.C.,Rapid Precision Testing Laboratories | Czako E.A.,Light Sources Inc. | Stepp M.E.,Wolff System Technology Corporation | Schlitt S.C.,Cosmedico Light Inc | And 8 more authors.
Health Physics | Year: 2011

The authors compared calculations of sunlamp maximum exposure times following current USFDA Guidance Policy on the Maximum Timer Interval and Exposure Schedule, with USFDA/CDRH proposals revising these to equivalent erythemal exposures of ISO/CIE Standard Erythema Dose (SED). In 2003, [USFDA/CDRH proposed replacing their unique CDRH/Lytle] erythema action spectrum with the ISO/CIE erythema action spectrum and revising the sunlamp maximum exposure timer to 600 J m ISO/CIE effective dose, presented as being biologically equivalent. Preliminary analysis failed to confirm said equivalence, indicating instead ∼38% increased exposure when applying these proposed revisions. To confirm and refine this finding, a collaboration of tanning bed and UV lamp manufacturers compiled 89 UV spectra representing a broad sampling of U.S. indoor tanning equipment. USFDA maximum recommended exposure time (Te) per current sunlamp guidance and CIE erythemal effectiveness per ISO/CIE standard were calculated. The CIE effective dose delivered per Te averaged 456 JCIE m (SD = 0.17) or ∼4.5 SED. The authors found that CDRH's proposed 600 JCIE m recommended maximum sunlamp exposure exceeds current Te erythemal dose by ∼33%. The current USFDA 0.75 MED initial exposure was ∼0.9 SED, consistent with 1.0 SED initial dose in existing international sunlamp standards. As no sunlamps analyzed exceeded 5 SED, a revised maximum exposure of 500 JCIE m (∼80% of CDRH's proposal) should be compatible with existing tanning equipment. A tanning acclimatization schedule is proposed beginning at 1 SED thrice-weekly, increasing uniformly stepwise over 4 wk to a 5 SED maximum exposure in conjunction with a tan maintenance schedule of twice-weekly 5 SED sessions, as biologically equivalent to current USFDA sunlamp policy. Copyright © 2011 Health Physics Society.


Sayre R.M.,University of Tennessee Health Science Center | Sayre R.M.,Rapid Precision Testing Laboratories | Dowdy J.C.,Rapid Precision Testing Laboratories | Shepherd J.G.,UV Foundation | Shepherd J.G.,KBD, INC.
Journal of Steroid Biochemistry and Molecular Biology | Year: 2010

While there is limited documentation that certain indoor tanning lamps effectively produce vitamin D, the diversity of such devices has not been extensively surveyed. This study compares the spectral effectiveness of a variety of tanning units, and solar spectra, for ultraviolet (UV) photosynthesis of pre-vitamin D3 (preD3) and UV induced erythema. Well-established techniques exist for the calculation of spectral effectiveness for photobiological responses that have defined action spectra. Using spectroradiometric data from sunlamp measurements, and standard solar reference spectra, we computed effective irradiances using the CIE action spectrum for the production of preD3 in human skin and the ISO/CIE human erythema reference action spectrum. We found, as with sunlight at different times or latitude, the preD3 and erythemal effectiveness of sunlamps varied as a function of the UV-B proportion of the spectrum. Ratios of sunlamp preD3 to erythemal effectiveness ranged from ∼0.5 to nearly 2.0, similar to ratios for sunlight. Optimal risk to benefit conditions for preD3 from solar UV exposure occurs under high solar altitude, low zenith angle, midday midsummer sunlight. Analogous optimal preD3 exposure conditions are provided by low to intermediate pressure sunlamps with greater UV-B spectral overlap with the preD3 action spectrum. Similar to low altitude or high latitude sunlight, high pressure tanning units, filtered for negligible UV-B emissions, have insignificant vitamin D benefit. We conclude that while vitamin D can be made by both UVB exposure from indoor tanning units and by exposure UVB from sunlight, the effect is also comparably variable. Unlike sunlight, indoor tanning offers privacy and environmental conditions for practical full body exposure, lowering the requisite exposure per skin surface area, and device timers limit the potential of overexposure. Guidance for optimal use of tanning sources for vitamin D benefit is needed. © 2010 Elsevier Ltd.


Dowdy J.C.,Rapid Precision Testing Laboratories | Sayre R.M.,Rapid Precision Testing Laboratories | Sayre R.M.,University of Tennessee Health Science Center | Holick M.F.,Vitamin D
Journal of Steroid Biochemistry and Molecular Biology | Year: 2010

Holick's rule says that sun exposure 1/4 of a minimal erythemal dose (MED) over 1/4 of a body is equivalent to 1000 International Units (IU) oral vitamin D3. Webb and Engelsen recently commented that the ultraviolet (UV) spectrum used to establish Holick's rule is unknown. They consequently used a spring midday Boston solar spectrum to estimate ample sunlight exposures for previtamin D3 (preD3) at various locations. Literature review found the source upon which this rule is based was a fluorescent sunlamp (FS lamp). The FS spectrum is known and its relative weighting against the action spectra for erythema and the preD3 is significantly different from the solar spectrum used to derive the standard vitamin D effective dose (SDD). The preD3 effectiveness of the solar spectrum per unit erythemal hazard is greater than the FS lamp by a factor of 1.32. Consequently, UV exposure estimates based on Boston reference sunlight, instead of the UV lamp employed in the originating experiments, over estimate UV exposure equivalent to ∼1000 IU orally by ∼1/3. This redefinition of SDD impacts risk/benefit assessments of optimal/feasible sun exposure for vitamin D maintenance and the application of Holick's rule to rational public health messages. © 2010 Elsevier Ltd.


Sayre R.M.,University of Memphis | Sayre R.M.,Rapid Precision Testing Laboratories | Dowdy J.C.,Rapid Precision Testing Laboratories
Photochemical and Photobiological Sciences | Year: 2010

The US Food and Drug Administration is in the process of formulating final rules for sunscreen labeling and testing. They have adopted a version of the solar simulator standard proposed by COLIPA, a European cosmetic products trade association. From our files we have selected spectral data on several solar simulators that comply with the proposed rules and have compared these sources both one to another and to several standard solar spectra of Air Mass 1.0, 1.5, and 2.0. In doing so we have used additional spectral analysis procedures including examining the goodness of fit between each solar simulator spectrum and an Air Mass 1.0 (0° zenith angle) solar spectrum. The index of goodness of fit ranges from ∼78% to just over 90% compared to solar spectra representing other Air Masses of 1.5 and 2.0, the goodness of fit is lower. Unfortunately, one may not assume that complying with a standard assures that other solar simulators also complying will produce identical results. In fact, by our analysis, none of the solar simulators we examined would be expected to produce the same SPF as sunlight. © The Royal Society of Chemistry and Owner Societies 2010.


Slominski A.T.,University of Memphis | Slominski A.T.,University of Alabama at Birmingham | Janjetovic Z.,University of Memphis | Kim T.-K.,University of Memphis | And 7 more authors.
Journal of Steroid Biochemistry and Molecular Biology | Year: 2015

CYP11A1 hydroxylates the side chain of vitamin D3 (D3) in a sequential fashion [D3 → 20S(OH)D3 → 20,23(OH)2D3 → 17,20,23(OH)3D3], in an alternative to the classical pathway of activation [D3 → 25(OH)D3 → 1,25(OH)2D3]. The products/intermediates of the pathway can be further modified by the action of CYP27B1. The CYP11A1-derived products are biologically active with functions determined by the lineage of the target cells. This pathway can operate in epidermal keratinocytes. To further define the role of these novel secosteroids we tested them for protective effects against UVB-induced damage in human epidermal keratinocytes, melanocytes and HaCaT keratinocytes, cultured in vitro. The secosteroids attenuated ROS, H2O2 and NO production by UVB-irradiated keratinocytes and melanocytes, with an efficacy similar to 1,25(OH)2D3, while 25(OH)D3 had lower efficacy. These attenuations were also seen to some extent for the 20(OH)D3 precursor, 20S-hydroxy-7-dehydrocholesterol. These effects were accompanied by upregulation of genes encoding enzymes responsible for defense against oxidative stress. Using immunofluorescent staining we observed that the secosteroids reduced the generation cyclobutane pyrimidine dimers in response to UVB and enhanced expression of p53 phosphorylated at Ser-15, but not at Ser-46. Additional evidence for protection against DNA damage in cells exposed to UVB and treated with secosteroids was provided by the Comet assay where DNA fragmentation was markedly reduced by 20(OH)D3 and 20,23(OH)2D3. In conclusion, novel secosteroids that can be produced by the action of CYP11A1 in epidermal keratinocytes have protective effects against UVB radiation. This article is part of a special issue entitled '17th Vitamin D Workshop'. © 2015 Elsevier Ltd.


PubMed | Rapid Precision Testing Laboratories
Type: Journal Article | Journal: Health physics | Year: 2011

The authors compared calculations of sunlamp maximum exposure times following current USFDA Guidance Policy on the Maximum Timer Interval and Exposure Schedule, with USFDA/CDRH proposals revising these to equivalent erythemal exposures of ISO/CIE Standard Erythema Dose (SED). In 2003, [USFDA/CDRH proposed replacing their unique CDRH/Lytle] erythema action spectrum with the ISO/CIE erythema action spectrum and revising the sunlamp maximum exposure timer to 600 J m(-2) ISO/CIE effective dose, presented as being biologically equivalent. Preliminary analysis failed to confirm said equivalence, indicating instead 38% increased exposure when applying these proposed revisions. To confirm and refine this finding, a collaboration of tanning bed and UV lamp manufacturers compiled 89 UV spectra representing a broad sampling of U.S. indoor tanning equipment. USFDA maximum recommended exposure time (Te) per current sunlamp guidance and CIE erythemal effectiveness per ISO/CIE standard were calculated. The CIE effective dose delivered per Te averaged 456 J(CIE) m(-2) (SD = 0.17) or 4.5 SED. The authors found that CDRHs proposed 600 J(CIE) m(-2) recommended maximum sunlamp exposure exceeds current Te erythemal dose by 33%. The current USFDA 0.75 MED initial exposure was 0.9 SED, consistent with 1.0 SED initial dose in existing international sunlamp standards. As no sunlamps analyzed exceeded 5 SED, a revised maximum exposure of 500 J(CIE) m(-2) (80% of CDRHs proposal) should be compatible with existing tanning equipment. A tanning acclimatization schedule is proposed beginning at 1 SED thrice-weekly, increasing uniformly stepwise over 4 wk to a 5 SED maximum exposure in conjunction with a tan maintenance schedule of twice-weekly 5 SED sessions, as biologically equivalent to current USFDA sunlamp policy.


PubMed | Rapid Precision Testing Laboratories
Type: Journal Article | Journal: The Journal of steroid biochemistry and molecular biology | Year: 2010

Holicks rule says that sun exposure 1/4 of a minimal erythemal dose (MED) over 1/4 of a body is equivalent to 1000 International Units (IU) oral vitamin D3. Webb and Engelsen recently commented that the ultraviolet (UV) spectrum used to establish Holicks rule is unknown. They consequently used a spring midday Boston solar spectrum to estimate ample sunlight exposures for previtamin D3 (preD3) at various locations. Literature review found the source upon which this rule is based was a fluorescent sunlamp (FS lamp). The FS spectrum is known and its relative weighting against the action spectra for erythema and the preD3 is significantly different from the solar spectrum used to derive the standard vitamin D effective dose (SDD). The preD3 effectiveness of the solar spectrum per unit erythemal hazard is greater than the FS lamp by a factor of 1.32. Consequently, UV exposure estimates based on Boston reference sunlight, instead of the UV lamp employed in the originating experiments, over estimate UV exposure equivalent to approximately 1000 IU orally by approximately 1/3. This redefinition of SDD impacts risk/benefit assessments of optimal/feasible sun exposure for vitamin D maintenance and the application of Holicks rule to rational public health messages.

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