Using intense pulsed light for cosmetic purposes: our experience

The authors' experience using intense pulsed light for skin rejuvenation is summarized and analyzed with regard to its efficacy, safety, and complications. Rejuvenation using intense pulsed light was performed on 59 patients over a 6-month period (January of 2002 to July of 2002); these patients served as the study group. The areas treated were the face, neck, chest, hands, and legs. The parameters used during the procedure, patient satisfaction, and complications are described. Ninety-five percent of the patients included in the study had one or two sessions. Good to very good results were reported by 93.1 percent. Most patients had minor side effects and only three patients (5 percent) experienced complications (hyperpigmentation or scars). Intense pulsed light is an effective and safe method for skin rejuvenation. Its efficacy is mainly manifested by eliminating senile pigmentation and telangiectasias and a achieving a younger and fresher appearance of the skin. Although in the literature intense pulsed light skin rejuvenation is mainly reported for the face, the authors have obtained good results by using it for other areas of the body. The majority of the patients were satisfied. The authors conclude that intense pulsed light skin rejuvenation is a safe and effective method for facial and nonfacial rejuvenation.     

Seed propagation ofDioscoreophyllum cumminsii,source of an intense natural sweetener

Germination ofDioscoreophyllum cumminsii is inhibited by light. Under shade 80 to 85% germination was achieved after 10 weeks. Pre-treatment with 0.1% to 0.5% giberrilic acid solutions was found to reverse the light inhibition and to accelerate germination. These techniques may enable large-scale cultivation ofD. cumminsii from seeds and commercial exploitation of the berries.     

Factors affecting the inactivation of micro-organisms by intense light pulses

AIM: To determine the influence of several factors on the inactivation of micro-organisms by intense light pulses (ILP). METHODS AND RESULTS: Micro-organisms on agar media were flashed 50 times under different conditions and their inactivation measured. Micro-organisms differed in sensitivity to ILP but no pattern was observed among different groups. Several enumeration methods to quantify the effect of ILP were investigated and showed relevant differences, shading effect and photoreactivation accounted for them, the strike method yielded the most reliable results. Higher decontamination efficiencies were obtained for Petri dishes located close to the strobe and inside the illumination cone. Decontamination efficacy decreased significantly at contamination levels >6.85 log(10). After 13 successive treatments, no resistance to ILP could be demonstrated. Media warming up depended on the distance from the strobe and the number of flashes. CONCLUSIONS: For an industrial implementation: the position and orientation of strobes in an unit will determine the lethality, products should be flashed as soon as possible after contamination occurs, a cooling system should be used for heat-sensitive products and flashed products should be light protected. No resistant flora is expected to develop. SIGNIFICANCE AND IMPACT OF THE STUDY: Conclusions derived from this work will allow a better implementation of this decontamination technique at industrial level.     

Chemically modified firefly luciferase is an efficient source of near-infrared light

Bioluminescence and bioluminescence resonance energy transfer (BRET) are two naturally occurring light emission phenomena that have been adapted to a wide variety of important research applications including in vivo imaging and enzyme assays. The luciferase enzyme from the North American firefly, which produces yellow-green light, is a key component of many of these applications. Recognizing the heightened interest in the potential of near-infrared (nIR) light to improve these technologies, we have demonstrated that spectral emissions with maxima of 705 and 783 nm can be efficiently produced by a firefly luciferase variant covalently labeled with nIR fluorescent dyes. In one case, an outstanding BRET ratio of 34.0 was achieved emphasizing the importance of selective labeling with fluorescent dyes and the efficiency provided by the intramolecular BRET process. Additionally, we constructed a biotinylated fusion protein that similarly produced nIR light. This novel material was immobilized on solid supports containing streptavidin, demonstrating, in principle, that it may be used for receptor-based imaging. Also, the matrix-bound labeled fusion protein was used to measure factor Xa activity at physiological concentrations in blood. We believe this to be the first report of bright nIR light sources produced by chemical modification of a beetle luciferase.     

Responses of crayfish photoreceptor cells following intense light adaptation

Summary After intense orange adapting exposures that convert 80% of the rhodopsin in the eye to metarhodopsin, rhabdoms become covered with accessory pigment and appear to lose some microvillar order. Only after a delay of hours or even days is the metarhodopsin replaced by rhodopsin (Cronin and Goldsmith 1984). After 24 h of dark adaptation, when there has been little recovery of visual pigment, the photoreceptor cells have normal resting potentials and input resistances, and the reversal potential of the light response is 10–15 mV (inside positive), unchanged from controls. The log V vs log I curve is shifted about 0.6 log units to the right on the energy axis, quantitatively consistent with the decrease in the probability of quantum catch expected from the lowered concentration of rhodopsin in the rhabdoms. Furthermore, at 24 h the photoreceptors exhibit a broader spectral sensitivity than controls, which is also expected from accumulations of metarhodopsin in the rhabdoms. In three other respects, however, the transduction process appears to be light adapted: (i) The voltage responses are more phasic than those of control photoreceptors. (ii) The relatively larger effect (compared to controls) of low extracellular Ca⁺⁺ (1 mmol/1 EGTA) in potentiating the photoresponses suggests that the photoreceptors may have elevated levels of free cytoplasmic Ca⁺⁺. (iii) The saturating depolarization is only about 30% as large as the maximal receptor potentials of contralateral, dark controls, and by that measure the log V-log I curve is shifted downward by 0.54 log units. The gain (change in conductance per absorbed photon) therefore appears to have been diminished.     

Prospect for feedback guided surgery with ultra-short pulsed laser light

The controlled cutting of tissue with laser light is a natural technology to combine with automated stereotaxic surgery. A central challenge is to cut hard tissue, such as bone, without inducing damage to juxtaposed soft tissue, such as nerve and dura. We review past work that demonstrates the feasibility of such control through the use of ultrafast laser light to both cut and generate optical feedback signals via second harmonic generation and laser induced plasma spectra.     

Effect of light regimes on the utilisation of an exogenous carbon source by freshwater biofilm bacterial communities

This study reports the novel use of nucleic acid stable isotope probing (NA-SIP) to identify metabolically active ([¹³C]-acetate assimilating) bacteria in freshwater biofilms. Currently, a little is known of the factors affecting the structure and activity of these complex microbial biofilm communities, although it is likely that they are influenced by riparian vegetation through attenuation of light and alteration of allochthonous inputs of carbon. NA-SIP was used to investigate the effect of varying light regimes on [¹³C]-acetate assimilating bacteria within laboratory biofilm microcosms. Differences in clone libraries of 16S rRNA and rRNA genes from ¹³C-labelled and unlabelled nucleic acids indicated differential uptake of acetate and the rapid transfer of ¹³C to organisms at a higher trophic level. Biofilm communities incubated in the dark changed least over time and retained a significant fraction of phototrophic organisms. Incubation under elevated light caused the greatest change in bacterial community structure. Contrary to expectation, a complete loss of chlorophyll containing organisms occurred within this treatment, challenging current thinking that elevated light promotes communities dominated by photoautotrophs in nutrient enriched environments.     

Effect of light source on the microbiological desulfurization in a photobioreactor

Removal rates of a toxic pollutant-hydrogen sulfide were investigated using several light sources in photosynthetic desulfurization. An incandescent bulb has a broad spectrum starting from about 400?nm but emits most of its light energy beyond 800?nm as heat. LED₇₁₀ among those sources saved energy considerably comparing with the incandescent light, but the scattering and absorption was a problem in light transmission within the deep region of a bioreactor due to its own weak light intensity. Fluorescent light was inefficient in desulfurization in comparison with light sources illuminating with wide wavelength range, because of the weak transmittance at the peak wavelength of 460?nm. A combination of LED₇₁₀ and fluorescent lamp was estimated as an optimal light source in this study.     

Treatment of head and neck cancers with BRMs

It has been reported that immunologic function is deteriorated in head and neck cancer patients by primary therapies such as surgery, irradiation and chemotherapy or tumor itself. As previously described by us, immunologic dysfunction in such patients may be recovered by treatment with BRMs. In the present study, we investigated the effects of BRMs on survival of patients who had primarily been treated in our clinic. Fifty-one patients (23 patients; Stage I or Stage II, 28 patients; Stage III or Stage IV) were treated with BRMs (BRM group), and 49 patients (22 patients; Stage I or Stage II, 27 patients; Stage III or Stage IV) were employed as controls (Control group). The results obtained were as follows: (1) In patients of all Stages, the survival period was significantly (p<0.05) longer in BRM group than in Control group; (2) The survival periods of patients of Stage I or Stage II were not different between the groups; and (3) The survival period of BRM group was significantly (p<0.05) longer than that of Control group in patients of Stage III or Stage IV. There were observed more patients in BRM group who survived for a prolonged period. These results suggest that BRMs may be useful for recovering immunologic function in head and neck cancer patients particularly of Stage III or Stage IV who usually receive multimodality therapy.     

Studies on the inactivation of medically important Candida species on agar surfaces using pulsed light

Development of a pulsed-light (PL) approach to inanimate surface decontamination is timely, as the incidence of yeast-related infections in healthcare remains unacceptably high. Critical electrical and biological factors governing the efficacy of PL for the in vitro inactivation of medically important yeast were established in this study. Predetermined cell numbers of yeast were inoculated separately on agar plates and were flashed with ≤90 pulses of broad-spectrum light under varying operating conditions, and their inactivation was measured. Significant differences in inactivation among different yeasts occurred depending on the intensity of the applied lamp discharge energy and the amount of pulsing applied. Levels of yeast sensitivity also varied depending on the distance between the light source and the treatment surface used, and the population size, type and age of cultures treated. Yeast strains were shown to be significantly more resistant to PL irradiation compared with similarly treated bacterial control cultures. A clear relationship was observed between the concentration of eluted proteins from treated yeast and the severity of PL conditions, with scanning electron micrographs showing irreversible cellular damage. Therefore, the findings from this study will enable further development and optimization of PL as a method of decontaminating surfaces in healthcare setting.     

Optical coherence hyperspectral microscopy with a single supercontinuum light source

In the paper, we have developed an optical coherence hyperspectral microscopy with a single supercontinuum light source. The microscopy consists of optical coherence tomography (OCT) and hyperspectral imaging (HSI), which can visualize the structural and functional characteristics of biological tissues. The 500 to 700 nm band is selected for HSI and OCT imaging, where HSI enables imaging of oxygen saturation and hemoglobin (Hb) content, while OCT acquires structural characteristics to assess the morphology of biological tissues. The system performance of the optical coherence hyperspectral microscopy is verified by normal mice ears, and the practical applications of the microscopy is further performed in 4T1 and inflammation Balb/c mice ears in vivo. The experimental results demonstrate that the microscopy has potential to provide complementary information for clinical applications.     

Fast and effective: intense pulse light photodynamic inactivation of bacteria

The goal of this study was to investigate the photodynamic toxicity of TMPyP (5, 10, 15, 20-Tetrakis (1-methylpyridinium-4-yl)-porphyrin tetra p-toluenesulfonate) in combination with short pulses (ms) of an intense pulse light source within 10 s against Bacillus atrophaeus, Staphylococcus aureus, Methicillin-resistant S. aureus and Escherichia coli, major pathogens in food industry and in health care, respectively. Bacteria were incubated with a photoactive dye (TMPyP) that is subsequently irradiated with visible light flashes of 100 ms to induce oxidative damage immediately by generation of reactive oxygen species like singlet oxygen. A photodynamic killing efficacy of up to 6 log(10) (>99.9999%) was achieved within a total treatment time of 10 s using a concentration range of 1-100 μmol TMPyP and multiple light flashes of 100 ms (from 20 J cm(-2) up to 80 J cm(-2)). Both incubation of bacteria with TMPyP alone or application of light flashes only did not have any negative effect on bacteria survival. Here we could demonstrate for the first time that the combination of TMPyP as the respective photosensitizer and a light flash of 100 ms of an intense pulsed light source is enough to generate sufficient amounts of reactive oxygen species to kill these pathogens within a few seconds. Increasing antibiotic resistance requires fast and efficient new approaches to kill bacteria, therefore the photodynamic process seems to be a promising tool for disinfection of horizontal surfaces in industry and clinical purposes where savings in time is a critical point to achieve efficient inactivation of microorganisms.