Visible Blue Light Research Articles

A single center, open label investigator study of photodynamic therapy in the treatment of sebaceous gland hyperplasia with topical 20% 5-aminolevulinic acid with visible blue light or intense pulsed light

Recent investigatory clinical trials have shown the cosmetic benefits of 20% 5-aminolevulinic acid and a variety of laser/light sources. Sebaceous gland hyperplasia often presents to dermatologists as a difficult entity to control and treat. In this clinical trial, 10 patients received short-contact 20% 5-aminolevulinic acid to the full face followed by either blue light therapy or intense pulsed light. Each patient received 4 weekly blue light treatments or 3 monthly intense pulsed light source treatments, with one and three month follow-ups. The resutls from this trial will be presented, thus giving dermatologists a new therapy for sebaceous gland hyperplasia.

A multi-center investigatory study of the treatment of mild to moderate inflammatory acne vulgaris of the face with visible blue light in comparison to topical 1% clindamycin antibiotic solution

A multi-center investigatory study of the treatment of mild to moderate inflammatory acne vulgaris of the face with visible blue light in comparison to topical 1% clindamycin antibiotic solution

Chinese, German & Indian suppliers dumping optical brighteners in the US?

This chapter describes the chemistry and mechanism of optical brightening agents as well as their applications to various kinds of fibers. The optical brighteners counteract the yellowness of the fabric by increasing the reflection of blue light rays. They convert invisible short-wave ultraviolet rays of sunlight into visible blue light and have a degree of whiteness that is comparatively more intense. Over-bleaching may reduce the fibre strength. Even well bleached fabrics possess a slight yellowish appearance. This yellowish hue of the materials can be eliminated by whitening with optical brightenering agents (OBA) or fluorescent brightening agents (FBA). Sometimes blueing agents are also used. In blueing, the initial yellowish shade of the textiles is covered by the blue dye and bluish white results. However, the corresponding blue dye itself absorbs in visible light and thus, the total amount of reflected light is smaller than in the case of unblued material, so that the blued material is less bright—that is, it is dull, or greyish.

A way to obtain visible blue light emission in porous silicon

Strong blue emission around 435 nm from porous silicon (PS) embedded in Pb(Zrx,Ti1−x)O3 (PZT) is realized, which is stable and clearly visible to the naked eye even after exposure in an ambient atmosphere for a year. The sample is obtained by hydrothermal etching of (100)-oriented single crystal silicon wafers in an HF aqueous solution, followed by pulsed laser ablation deposition of a PZT thin layer on the surface of the PS. The electrons and holes excited from silicon nanocrystallites could be separated by the PZT-induced electrostatic field and migrate to the boundaries of PS/PZT along opposite directions, respectively. Therefore, the blue emission is interpreted in terms of the recombination of excited carriers from the silicon nanocrystallites in the interfacial region of PS/PZT.

ALA/PDT in the treatment of actinic keratosis: spot versus confluent therapy

BACKGROUND: Actinic keratosis (AK) represents commonly occurring, atypical keratinocytic proliferations confined to the epidermis. While it is the standard of care to destroy AK, few advances have been made to the traditional approaches of physical ablation (e.g. cryosurgery, curettage) and chemotherapeutics (e.g. topical 5‐fluorouracil). The recent advances in photodynamic therapy (PDT) with 20% aminolevulinic acid (ALA) offer a novel, safe, and effective approach to AK therapy.OBJECTIVE: To evaluate the safety and efficacy of 20% ALA solution and blue light for the treatment of multiple facial AK.PATIENTS/METHODS: A total of 32 patients were offered either partial treatment (i.e. individual target lesions treated) or confluent treatment (i.e. entire region treated). At 15–20 hours after ALA solution application, treated areas were exposed to visible blue light for 16 minutes and 40 seconds.RESULTS: ALA/PDT treatment resulted in a rapid resolution of multiple AK lesions with a limited period of associated photosensitivity. Side effects experienced by individual patients were found to be influenced by a number of factors: use of analgesic and topical anesthetic agents, body region treated, partial versus confluent treatment, and light exposure time.CONCLUSION: Twenty per cent ALA/PDT offers a safe, effective, and cost‐efficient means of managing multiple AK lesions per treatment session with a low recurrence rate. In addition to a favorable tolerability profile, most patients also achieved an improvement in skin texture.

ALA/PDT in the treatment of actinic keratosis: spot versus confluent therapy

BACKGROUND: Actinic keratosis (AK) represents commonly occurring, atypical keratinocytic proliferations confined to the epidermis. While it is the standard of care to destroy AK, few advances have been made to the traditional approaches of physical ablation (e.g. cryosurgery, curettage) and chemotherapeutics (e.g. topical 5‐fluorouracil). The recent advances in photodynamic therapy (PDT) with 20% aminolevulinic acid (ALA) offer a novel, safe, and effective approach to AK therapy.OBJECTIVE: To evaluate the safety and efficacy of 20% ALA solution and blue light for the treatment of multiple facial AK.PATIENTS/METHODS: A total of 32 patients were offered either partial treatment (i.e. individual target lesions treated) or confluent treatment (i.e. entire region treated). At 15–20 hours after ALA solution application, treated areas were exposed to visible blue light for 16 minutes and 40 seconds.RESULTS: ALA/PDT treatment resulted in a rapid resolution of multiple AK lesions with a limited period of associated photosensitivity. Side effects experienced by individual patients were found to be influenced by a number of factors: use of analgesic and topical anesthetic agents, body region treated, partial versus confluent treatment, and light exposure time.CONCLUSION: Twenty per cent ALA/PDT offers a safe, effective, and cost‐efficient means of managing multiple AK lesions per treatment session with a low recurrence rate. In addition to a favorable tolerability profile, most patients also achieved an improvement in skin texture.

The significance of oxidative mechanisms in diseases of the retina

The eye is at high risk to be damaged by oxidative mechanisms. One major reason is the exposure to light throughout life. Anterior segment structures are mostly exposed to UV light. Visible blue light is believed to be a significant damaging mechanism for the retina. The biochemical composition of the posterior segment structures (unsaturated fatty acids) is an important factor making the eye more susceptible than other organs. Damaging mechanisms such as xanthin oxidase mechanisms are responsible for damage occurring in ischaemic diseases. These mechanisms are well known from diseases of other organs. Ischaemic processes are no longer believed to be the primary damaging mechanisms in diabetic retinopathy. Here, advanced glycation end products (AGE's) and related products may induce oxidative reactions and the expression of growth factors. In age-related macular degeneration photodynamic processes occurring already in childhood are believed to be a major factor contributing to the pathogenesis of the disease process. In addition, the expression of growth factors and new vessel growth can be initiated via inflammatory reactions or oxidative metabolites. In this manuscript we give an overview on oxidative mechanisms involved in the pathogenesis of retinal diseases. Different therapeutical and preventive approaches such as the results of the ARED-Study and possible side effects are discussed.

A whole new way of looking at things: the use of Dark Reader technology to detect fluorophors.

The Dark Reader optical system (Clare Chemical Research, Denver, CO, USA) uses relatively low intensity broad-band visible blue light in combination with broad-band optical filters to detect fluorescence with a level of sensitivity that often surpasses that of UV transilluminators and can rival that of laser-based scanners. Applications of DR (Clare Chemical Research) devices include the detection of DNA and SYBR-stained protein samples following, and also during, electrophoresis. Unlike laser-based imaging systems, the fluorescence is directly visible to the user as well as being fully compatible with charge-coupled device (CCD) and Polaroid camera-based detection and imaging. Additionally, the DR optical system functions well in multicolor fluorophor environments. Because the Dark Reader does not emit any UV light, the extent of DNA damage incurred when visualizing DNA samples is drastically reduced compared to the damage produced by a UV device and this can have a significant benefit on downstream cloning protocols. Furthermore, dye photobleaching is minimal, extending the length of time that a fluorescent sample is visible. The inherent flexibility of the DR optical system allows many different configurations of the Dark Reader to be constructed such as transilluminators, hand lamps and integrated transilluminator-electrophoresis units.

On the nature and causes of luminescent lines and bands in coral skeletons

Holes pushed into the surface of laboratory grade CaCO3 powder reproduced visible and measurable luminescence similar to that seen and measured in coral skeletons. Heating such powder to 450 °C for 2 h did not destroy the luminescence although it did destroy luminescence in powdered coral skeleton. The effect in coral skeletal powder was probably due to carbonisation of contained organics because addition of small and increasing amounts of powdered charcoal to laboratory grade CaCO3 increasingly attenuated luminescence. Luminescent lines and bands in coral skeletons have previously been ascribed to incorporation of humic substances. However, coating laboratory grade powder with humic acid attenuates rather than enhances luminescence. Ultra-violet lamps used to display coral luminescent lines and bands emit significant amounts of violet and blue visible light. Reflection of these visible wavelengths from the surface of laboratory grade CaCO3 powder obscured luminescence of the powder. Multiple reflections within a hole in the powder resulted in absorption of the short wavelengths of visible light, including violet and blue light that would otherwise mask luminescence, and their re-emission at longer wavelengths. Luminescent bands in offshore corals were associated with the low-density regions of the annual density banding pattern. Luminescent lines in skeletons of inshore corals were in narrow regions of low-density skeleton, probably resulting from altered growth during periods of lowered salinity.

Holographic `development' of a hidden UV image recorded on a liquid crystalline polymer

Films of a chiral liquid crystalline side chain polymer with azobenzene chromophores are shown to be a novel medium for UV image recording. The principle includes a primary process of recording a UV image (e.g. of a mask) by unpolarized UV light excitation of a considerable amount of extraordinary long living cis-isomers of the azo-chromophores. After that the image is `hidden' because it is not seen under a polarising microscope equipped with a red filter. At the second stage, the image is developed by a linearly polarized beam of visible (blue or green) light that converts cis-isomers back into their trans-counterparts. The image appears in the form of the spatial modulation of the optical anisotropy which is measured at each stage in situ by an ellipsometry technique. The development of the hidden images has been done both with a uniform illumination and a holographic technique using a grating formed by interfering beams of visible Ar-laser light. Recorded images are erased by the second, this time uniform, UV irradiation of the film and the process may be repeated many times on the same spot.

A Blue Excitable Charge-Transfer Fluorescent Probe and Its Fluorogenic Derivative

Structural modification of the highly fluorescent donor-bridge-acceptor molecule “Fluoroprobe” (FP) is shown to extend the excitation window to longer wavelengths. The resulting “Fluorotrope” (FT) shows appreciable absorption in the 350-420-nm range, so that visible (blue) light can be used for excitation. Further functionalization with a maleimide group results in the novel fluorogenic reagent MaleimidoFluorotrope (MFT) which yields fluorescent adducts with amines, thiols and other reactive groups that add to the double bond of the maleimide. The fluorescence wavelength of these adducts is extremely sensitive to the polarity and mobility of the medium.

New Series of Blue-Light-Emitting Polymers Constituted of 3-Alkylthiophenes and 1,4-Di(1,3,4-oxadiazolyl)phenylene

A new series of conjugated polymers constituted of 3-alkylthiophenes and 1,4-di(1,3,4-oxadiazolyl)phenylene are synthesized through precursor polymers of polyhydrazides. The solubility of the precursor polymers and the corresponding target polymers is improved by increasing the length of side chains on thiophene rings, which results in a higher degree of the conversion from the precursors to the final polymers and thus results in longer effective conjugated length in the polymers bearing longer side chains. The thermal stability and electrochemical properties of the polymers are studied. The polymers emit blue light under the irradiation of UV light in their film states. The relative fluorescence yield in solutions increases with the increase in length of side chains on thiophene rings in the polymers and reaches up to 79% for the polymer bearing octyl side chains. The possibility of polymers being used as electroluminescent material in polymer light-emitting diodes (PLEDs) is demonstrated by the successful fabrication of a single-layer device of indium tin oxide (ITO)/polymer/Ca, which emits visible blue light above 8 V of forward bias.

Dielectric Properties during Free-Radical Bulk Polymerization: Visible Light-Induced Polymerization of Bisphenol-A Bis(2-hydroxyethyl ether) Dimethacrylate

The dielectric properties of the polymerized and unpolymerized bisphenol-A bis(2-hydroxyethyl ether) dimethacrylate have been studied, and the polymerization of this monomer using visible blue light (λ = 470 nm) and the system camphorquinone/(dimethylamino)ethyl methacrylate as a photochemical initiator has been followed in real time. Remarkable changes in the permittivity ε‘(ω,t,T) and the loss peak ε‘‘(ω,t,T) of the polymer have been observed and analyzed, as soon as the sample was illuminated, corresponding to a sudden fall of ε‘(ω,t,T) for all the frequencies of measurement, a shift to low frequencies, and a large decrease of the relaxation loss peak in the frequency domain. A thermal postcuring of the acrylic polymer has been performed, leading to small changes in the chemical properties but large changes in the dielectric absorption. The present work shows how dielectric relaxation spectroscopy may be used as a very sensitive technique to follow polymerization.

Lipofuscin Accumulation in Cultured Retinal Pigment Epithelial Cells Causes Enhanced Sensitivity to Blue Light Irradiation

Lipofuscin accumulates with age within secondary lysosomes of retinal pigment epithelial (RPE) cells of humans and many animals. The autofluorescent lipofuscin pigment has an excitation maximum within the range of visible blue light, while it is emitting in the yellow-orange area. This physico-chemical property of the pigment indicates that it may have a photo-oxidative capacity and, consequently, then should destabilize lysosomal membranes of blue-light exposed RPE. To test this hypothesis, being of relevance to the understanding of age-related macular degeneration, cultures of heavily lipofuscin-loaded RPE cells were blue-light–irradiated and compared with respect to lysosomal stability and cell viability to relevant controls. To rapidly convert primary cultures of RPE, obtained from neonatal rabbits, into aged, lipofuscin-loaded cells, they were allowed to phagocytize artificial lipofuscin that was prepared from outer segments of bovine rods and cones. Following blue-light irradiation, lysosomal membrane stability was measured by vital staining with the lysosomotropic weak base, and metachromatic fluorochrome, acridine orange (AO). Quantifying red (high AO concentration within intact lysosomes with preserved proton gradient over their membranes) and green fluorescence (low AO concentration in nuclei, damaged lysosomes with decreased or lost proton gradients, and in the cytosol) allowed an estimation of the lysosomal membrane stability after blue-light irradiation. Cellular viability was estimated with the delayed trypan blue dye exclusion test. Lipofuscin-loaded blue-light–exposed RPE cells showed a considerably enhanced loss of both lysosomal stability and viability when compared to control cells. It is concluded that the accumulation of lipofuscin within secondary lysosomes of RPE sensitizes these cells to blue light by inducing photo-oxidative alterations of their lysosomal membranes resulting in a presumed leakage of lysosomal contents to the cytosol with ensuing cellular degeneration of apoptotic type. The suggested mechanism may have bearings on the development of age-related macular degeneration. © 1997 Elsevier Science Inc.

Simultaneous luminescence pressure and temperature measurement system for hypersonic wind tunnels

Surface pressures and temperatures are determined from visible emission brightness and green-to-red color ratioing of induced luminescence from a ceramic surface with an organic dye coating. A ceramic-dye matrix of porous silica ceramic with an adsorbed dye is developed for high-temperature pressure sensitivity and stability (up to 150 C). Induced luminescence may be excited using a broad range of incident radiation from visible blue light (488-nm wavelength) to the near ultraviolet (365 nm). Ceramic research models and test samples are fabricated using net-form slip-casting and sintering techniques. Methods of preparation and effects of adsorption film thickness on measurement sensitivity are discussed. With the present 8-bit imaging system a 10% pressure measurement uncertainty from 50 to 760 torr is estimated, with an improvement to 5% from 3 to 1500 torr with a 12-bit imaging system.

Accumulation of lipofuscin within retinal pigment epithelial cells results in enhanced sensitivity to photo-oxidation.

Retinal pigment epithelial (RPE) cells are largely postmitotic. They continuously phagocytose the outer tips of the photoreceptor outer segments (POS). Over the life span of an individual, this activity results, although surprisingly slowly, in the intralysomal accumulation of lipofuscin, or age-pigment. Native lipofuscin shows orange-red autofluorescence when exposed to blue light. The loss of energy resulting from the conversion of excitatory blue light into emitted orange-red light may induce photo-oxidative reactions. We exposed neonatal rabbit RPE cells in culture to purified POS from cow eyes. The material were either native or peroxidized by irradiation with UV-light before being added to the RPE cultures. Lipofuscin accumulation was studied by transmission electron microscopy and measured by microfluorometric registration of its autofluorescence. Cells exposed to peroxidized POS accumulated much more lipofuscin than those exposed to native POS, indicating that peroxidized outer segments are not digestable by lysosomal enzymes. Furthermore, lipofuscin-loaded RPE cells were considerable more sensitive to visible blue light than unloaded control cells. The former ones showed lysosomal membrane destabilization with ensuing leakage of lytic enzymes and eventually cell death. We suggest that photo-oxidation of lysosomal membranes surrounding accumulated lipofuscin may be of importance for the development of age-related macular degeneration.

Use of Alternative Light Source Illumination in Bite Mark Photography

Recent investigation regarding the optical properties of human skin has lead to studies measuring autofluorescence, absorption, and reflectance of monochromatic light during exposure both in vitro and in vivo environments. The Stokes Shift deviation in absorbed and reflected light energy that occurs when skin is illuminated by 450 nanometer visible blue light can produce an augmentation in the appearance of pattern injuries when viewed through colored blocking filters. This paper demonstrates a comparison between photographic appearances of several bitemarks inflicted on living and deceased persons to determine the corroborability and usefulness of fluorescent versus full spectrum visibility of bitemark pattern injuries.

CERENKOV-TYPE OPTICAL SECOND-HARMONIC GENERATION IN ORGANIC-CRYSTALLINE CHANNEL WAVEGUIDES

Cerenkov-type optical second-harmonic generation (SHG) in organic-crystalline waveguides has been investgated. Various techniques for the fabrication of organic-crystalline waveguides are described. Planar and channel waveguides have been fabricated using an organic nonlinear optical crystal (−)2-(α-methylbenzylamino)-5-nitropyridine (MBANP). Visible blue light has been obtained in an MBANP rib waveguide using a laser-diode source. Theoretical analysis of Cerenkov-type SHG in planar waveguides is made, and a simple analytic expression for second-harmonic power is derived. Optimum conditions for attaining high conversion efficiency are discussed on the basis of the theoretical calculations.

An electron paramagnetic resonance and theoretical study of the radical cationic C8H8 +? system

EPR spectroscopy shows that the radical cation of cyclooctatetraene (1), as formed by γ-radiolysis in solid freon matrices at 77 K, is converted by visible (blue) light (400–600 nm) to the isomeric bicyclo[3.3.0]octa-2,6-diene-4,8-diyl isomer (2). On subsequently irradiating with red light (>570 nm), 2 is converted to a third isomer with couplings (a= 13.5 G) to two protons which are α- to the SOMO, as may be judged from the g and A anisotropy. Restricted HF AM1 calculations establish the structure 11 for this isomer and provide a rationale for the conversion of 2 to 11 in the clear correlation that is found between the two highest occupied orbitals of excited 2* and 11. Other local minima are located by extensive exploration of the C8H8+˙ potential energy surface, and possible conversions between selected examples of these are calculated to compare with published experimental results.

Optical properties of piloboloid and β-carotene-overproducing mutants of phycomyces blakesleeanus responsible for their negative phototropism

Sporangiophores (spphs) of the piloboloid mutant (genotype pil) of Phycomyces, the extension zone of which gradually ceases elongation but expands spherically shortly after sporangium formation (stage IVb), and of the β-carotene-overproducing mutant (genotype carS) grown on medium containing vitamin A show negative phototropism toward unilateral visible (blue) light, in contrast with the wild-type spph. We hypothesized that the phototropic orientation of spph, positive or negative, is determined by the ratio of the maximal light fluence rate of the proximal side ( I Pmax) to that of the distal side ( I Dmax) of spph. The reversal of phototropism in the pil and car mutants probably occurs because of the expansion of the extension zone (increase in length of intracellular light path) and the accumulation of excess β-carotene in the extension zone, respectively. These characteristics of the mutants reduce the transmission of incident light to the distal side of the spph cell, and cause a reverse in the I Pmax/ I Dmax ratio as a result of a decrease in I Dmax. The information obtained on the optical properties of the extension zones of these mutants supports our hypothesis.