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19. Heme oxygenase induction mediates the photoimmunoprotective activity of UVA radiation in the mouse

Author

Reeve, Vivienne E. and Tyrrell, Rex M.

Subjects
Ultraviolet radiation -- Physiological aspects, Immunosuppression -- Physiological aspects, T cells -- Physiological aspects, Oxidases -- Physiological aspects, Mice -- Physiological aspects, Science and technology
Abstract

In contrast to the immunosuppressive potential of UVB (280-320 nm) radiation in experimental animals and humans, UVA (320-400 nm) radiation at environmentally relevant doses appears to be immunologically inert. However, such exposure to UVA radiation has been observed unexpectedly to induce resistance to UVB-induced immunosuppression in mice, by a mechanism resulting in the inactivation of cis-urocanic acid (UCA), an epidermal immunosuppressive UV photoproduct. In this study in mice, we show that the immunoprotective activity of UVA radiation, against the effects of both UVB radiation and cis-UCA, can be attributed to the induction of cutaneous heme oxygenase (HO; EC 1.14.99.3). Cell-mediated immune function was assessed in vivo by the contact hypersensitivity response induced to oxazolone at an unirradiated skin site, and HO enzyme activity was measured in cutaneous microsomal preparations from treated mice. There was a progressive increase in HO enzyme activity for at least 3 days after UVA irradiation. However HO activity, both constitutive and UVA radiation-induced, was sensitive to the effects of injecting mice with the specific HO inhibitor, tin protoporphyrin (Sn [IV] protoporphyrin IX; SnPP). We observed, in addition, that in SnPP-injected mice, the immunoprotective effect of UVA radiation against either UVB radiation or cis-UCA was abrogated. Because SnPP injection did not affect normal contact hypersensitivity responsiveness but did inhibit the constitutive HO enzyme activity, it appeared that only the inducible HO was active in modulating immune function. This finding indicates that UVA-induced HO activity is a major player in the skin defenses against UVB immunosuppression.

Published
1999

20. A study of the kinetics of photo-enzymatic repair in ultraviolet sensitive strains of Escherichia coli

Author

Tyrrell, Rex M.

Subjects
579
Abstract

The introduction includes a review of the recent work on the repair of damage induced in the DNA of bacterial cells by U.V. particular emphasis has been placed on a consideration of the photoenzymatic repair system and on the way recent findings have been used to postulate mechanisms for the repair processes. The experimental work is in two parts. The first section is concerned with experiments undertaken with stationary phase cells of Escherichia coli K12.AB2480 and AB1886. The cells were used to study the kinetics of photoreactivation. Survival curves, with samples at a minimum of six U.V. doses were obtained at several periods of photoreactivation ranging from zero to maximum, and the results were analysed mathematically on the basis of two different repair models. Experiments at different temperatures and dose-rates indicated two distinct rates of photoreactivation. The second experimental section is concerned with an investigation of the different rate processes using the U.V. sensitive AB2480 grown in liquid culture. An initial fast rate could be eliminated by administering a single high intensity light flash at the start of continuous illumination. This experimental technique allowed the recognition of two separate rates during continuous illumination and the dose-rate and temperature dependence of these were characterised. The effect of growth stage on the U.V. sensitivity of AB2480 was also investigated. The results suggest that the number of active repair enzymes per cell changes during the growth cycle. Findings from these experiments have been discussed in relation to the current concepts regarding molecular repair phenomena.

Published
1971

24. Contributors

Author

Afaq, Farrukh, primary, Agostinis, Patrizia, additional, Armstrong, Bruce K., additional, Arpino, Glenn, additional, Basu-Modak, Sharmila, additional, Black, Homer S., additional, Brenneisen, Peter, additional, Brown, David A., additional, Burack, Herb, additional, Cantrell, Ann, additional, Cadet, Jean, additional, Chung, Jin Ho, additional, Cyr, W. Howard, additional, Davies, Michael J., additional, Decraene, David, additional, Diffey, Brian L., additional, Douki, Thierry, additional, Driscoll, Colin M.H., additional, Eisner, Mel, additional, Falchi, Mario, additional, Gallas, Jim, additional, Garmyn, Marjan, additional, Giacomoni, Paolo U., additional, Gibbs, Neil K., additional, Girotti, Albert W., additional, Golstein, Patricia, additional, Gruijl, Frank R. de, additional, Haes, Petra de, additional, Heenen, Michel, additional, Hellweg, Christine, additional, van Hoffen, Anneke, additional, Holick, Michael F., additional, Jacobson, Elaine L., additional, Jacobson, Myron K., additional, Kamath, Yash, additional, Katiyar, Santosh K., additional, van Kranen, Henk J., additional, Kricker, Anne, additional, Krins, Andreas, additional, Kuhr, Lale, additional, Leone, Anna-Sophia, additional, Malorni, Walter, additional, Mayer, Helmut, additional, McGarvey, David J., additional, Meewes, Christian, additional, Miller, Sharon A., additional, Monfrecola, Giuseppe, additional, Mukhtar, Hasan, additional, Mullenders, Leon H.F., additional, Norval, Mary, additional, Orentreich, David, additional, Prizio, Emilia, additional, Pupe, Annemie, additional, Ravanat, Jean-Luc, additional, Razi-Wolf, Ziba, additional, Rhodes, Lesley E., additional, Roberts, Joan E., additional, Roberts, Michael J., additional, Ruetsch, Sigrid B., additional, Scharffetter-Kochanek, Karin, additional, Schneider, Lars-Alexander, additional, Seidlitz, Harald K., additional, Sheehan, John M., additional, Sies, Helmut, additional, Stahl, Wilhelm, additional, Straface, Elisabetta, additional, Strickland, Faith M., additional, Tantcheva-Poór, Iliana, additional, Thiel, Stephan, additional, Trautinger, Franz, additional, Truscott, Roger J.W., additional, Truscott, T. George, additional, Tyrrell, Rex M., additional, Urbach, Frederick, additional, Weigmann, Hans-Dietrich, additional, Wlaschek, Meinhard, additional, Wondrak, Georg T., additional, Yarosh, Daniel B., additional, Young, Antony R., additional, and van Zeeland, Albert A., additional

Published
2001
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41. Encapsulation of Cadmium Selenide Nanocrystals in Biocompatible Nanotubes: DFT Calculations, X-ray Diffraction Investigations, and Confocal Fluorescence Imaging

Author

European Research Council, Centre for Sustainable Chemical Technologies (UK), University of Bath, Calatayud, David G., Ge, Haobo, Kuganathan, Navaratnarajah, Mirabello, Vincenzo, Jacobs, Robert M.J., Rees, Nicholas H., Stoppiello, Craig T., Khlobystov, Khlobystov, Tyrrell, Rex M., Da-Como, Enrico, Pascu, Sofia I., European Research Council, Centre for Sustainable Chemical Technologies (UK), University of Bath, Calatayud, David G., Ge, Haobo, Kuganathan, Navaratnarajah, Mirabello, Vincenzo, Jacobs, Robert M.J., Rees, Nicholas H., Stoppiello, Craig T., Khlobystov, Khlobystov, Tyrrell, Rex M., Da-Como, Enrico, and Pascu, Sofia I.

Abstract

[EN] The encapsulation of CdSe nanocrystals within single‐walled carbon nanotube (SWNT) cavities of varying dimensions at elevated temperatures under strictly air‐tight conditions is described for the first time. The structures of CdSe nanocrystals under confinement inside SWNTs was established in a comprehensive study, combining both experimental and DFT theoretical investigations. The calculated binding energies show that all considered polymorphs [(3:3), (4:4), and (4:2)] may be obtained experimentally. The most thermodynamically stable structure (3:3) is directly compared to the experimentally observed CdSe structures inside carbon nanotubes. The gas‐phase DFT‐calculated energy difference between “free” 3:3 and 4:2 structures (whereby 3:3 models a novel tubular structure in which both Cd and Se form three coordination, as observed experimentally for HgTe inside SWNT, and 4:2 is a motif derived from the hexagonal CuI bulk structure in which both Cd and Se form 4 or 2 coordination) is surprisingly small, only 0.06 eV per formula unit. X‐ray powder diffraction, Raman spectroscopy, high‐resolution transmission electron microscopy, and energy‐dispersive X‐ray analyses led to the full characterization of the SWNTs filled with the CdSe nanocrystals, shedding light on the composition, structure, and electronic interactions of the new nanohybrid materials on an atomic level. A new emerging hybrid nanomaterial, simultaneously filled and beta‐d‐glucan coated, was obtained by using pristine nanotubes and bulk CdSe powder as starting materials. This displayed fluorescence in water dispersions and unexpected biocompatibility was found to be mediated by beta‐d‐glucan (a biopolymer extracted from barley) with respect to that of the individual inorganic material components. For the first time, such supramolecular nanostructures are investigated by life‐science techniques applied to functional nanomaterial characterization, opening the door for future nano‐biotechnological applic

Published
2018

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