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Nm Radiation (nm + radiation)

Distribution by Scientific Domains
Medical Sciences50%

Selected Abstracts

Bacterial Inactivation by Solar Ultraviolet Radiation Compared with Sensitivity to 254 nm Radiation

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2009
Thomas P. Coohill
Our goal was to derive a quantitative factor that would allow us to predict the solar sensitivity of vegetative bacterial cells to natural solar radiation from the wealth of data collected for cells exposed to UVC (254 nm) radiation. We constructed a solar effectiveness spectrum for inactivation of vegetative bacterial cells by combining the available action spectra for vegetative cell killing in the solar range with the natural sunlight spectrum that reaches the ground. We then analyzed previous studies reporting the effects of solar radiation on vegetative bacterial cells and on bacterial spores. Although UVC-sensitive cells were also more sensitive to solar radiation, we found no absolute numerical correlation between the relative solar sensitivity of vegetative cells and their sensitivity to 254 nm radiation. The sensitivity of bacterial spores to solar exposure during both summer and winter correlated closely to their UVC sensitivity. The estimates presented here should make it possible to reasonably predict the time it would take for natural solar UV to kill bacterial spores or with a lesser degree of accuracy, vegetative bacterial cells after dispersion from an infected host or after an accidental or intentional release. [source]

Port wine stain treatment with a dual-wavelength Nd:Yag laser and cryogen spray cooling: A pilot study,

LASERS IN SURGERY AND MEDICINE, Issue 2 2004
an MD
Abstract Background and Objectives We report on a pilot study of port wine stain (PWS) treatment with a prototype Nd:YAG/KTP laser system, emitting simultaneously at 1,064 and 532 nm, and equipped with a cryogen spray cooling (CSC) device. Study Design/Patients and Methods On 10 patients (4,36 years old, mean: 16.2 years) with skin types II-III, therapeutic efficacy of the dual-wavelength laser (KTP+) was compared with a standard KTP laser (532 nm only) at the same pulse duration (25 millisecond), spot diameter (3 mm), and CSC parameters. The fluences were selected in order to obtain the same immediate response with both laser systems. Blanching of each test segment was assessed 8 weeks post treatment by an independent evaluator and by the subjects, and graded on a 1,4 scale. Results Significant blanching of PWS was noted 8 weeks after a single therapeutic session with the KTP+ laser (mean: 532 nm radiant exposure: 8.2 J/cm2), very similar to that observed with KTP at 12.4 J/cm2. The evaluator noticed a slight brownish coloration in areas treated with the KTP+ laser. Isolated beam-sized atrophic scars were present in two patients where KTP+ (9 and 10 J/cm2) and KTP (14 J/cm2) lasers were used. Conclusions The addition of 1,064 nm radiation allowed a significant reduction of 532 nm radiant exposure with no loss of efficacy in PWS treatment. Lasers Surg. Med. 34:164,167, 2004. © 2004 Wiley-Liss, Inc. [source]

Bacterial Inactivation by Solar Ultraviolet Radiation Compared with Sensitivity to 254 nm Radiation

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2009
Thomas P. Coohill
Our goal was to derive a quantitative factor that would allow us to predict the solar sensitivity of vegetative bacterial cells to natural solar radiation from the wealth of data collected for cells exposed to UVC (254 nm) radiation. We constructed a solar effectiveness spectrum for inactivation of vegetative bacterial cells by combining the available action spectra for vegetative cell killing in the solar range with the natural sunlight spectrum that reaches the ground. We then analyzed previous studies reporting the effects of solar radiation on vegetative bacterial cells and on bacterial spores. Although UVC-sensitive cells were also more sensitive to solar radiation, we found no absolute numerical correlation between the relative solar sensitivity of vegetative cells and their sensitivity to 254 nm radiation. The sensitivity of bacterial spores to solar exposure during both summer and winter correlated closely to their UVC sensitivity. The estimates presented here should make it possible to reasonably predict the time it would take for natural solar UV to kill bacterial spores or with a lesser degree of accuracy, vegetative bacterial cells after dispersion from an infected host or after an accidental or intentional release. [source]

Repair of cyclobutyl pyrimidine dimers in human skin: variability among normal humans in nucleotide excision and in photorepair

PHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 3 2002
Betsy M. Sutherland
Background/Aims: Photoreactivation (PR) of cyclobutyl pyrimidine dimers (CPD) in human skin remains controversial. Recently Whitmore et al. (1) reported negative results of experiments using two photorepair light (PRL) sources on UV-irradiated skin of volunteers. However, their PRL sources induced substantial levels of dimers in skin, suggesting that the additional dimers formed could have obscured PR. We met a similar problem of dimer induction by a PRL source. We designed and validated a PRL source of sufficient intensity to catalyse PR, but that did not induce CPD, and used it to measure photorepair in human skin. Methods and Results: Using a solar simulator filtered with three types of UV-filters, we found significant dimer formation in skin, quantified by number average length analysis using electrophoretic gels of isolated skin DNA. To prevent scattered UV from reaching the skin, we interposed shields between the filters and skin, and showed that the UV-filtered/shielded solar simulator system did not induce damage in isolated DNA or in human skin. We exposed skin of seven healthy human volunteers to 302 nm radiation, then to the improved PRL source (control skin areas were kept in the dark for measurement of excision repair). Conclusions: Using a high intensity PRL source that did not induce dimers in skin, we found that three of seven subjects carried out rapid photorepair of dimers; two carried out moderate or slow dimer photorepair, and three did not show detectable photorepair. Excision repair was similarly variable in these volunteers. Subjects with slower excision repair showed rapid photorepair, whereas those with rapid excision generally showed little or no photoreactivation. [source]