V posledných 10 rokoch badať výrazný vzostup používania rôznych metód liečby akné, ktoré sú založené na báze svetla. Ako zdroje sa používajú najmä vysokotlakové výbojky, fluorescenčné trubice a diodové svetlo LED (Light Emitting Diodes). Najčastejšou cieľovou vlnovou dĺžkou je 415 ± 10 nm, pretože táto je veľmi účinne absorbovaná v protoporfyríne IX (PpIX) v Propionibacterium acnes (P. acnes). Svetlom navodeným rozpadom PPIX dochádza k tvorbe kyslíkových radikálov, ktoré usmrcujú P. acnes. V poslednej dobe sa do popredia dostávajú aj dôkazy protizápalového pôsobenia modrého svetla. Okrem tohto sa často využíva aj červené (630nm) svetlo. Využitie svetla v liečbe akné je vhodné kombinovať s inými metódami (napr. lokálne keratolytiká). Nevýhodou je, že po ukončení série ošetrení dochádza pomerne rýchlo k relapsu.
A great increased number of light-based therapies of acne have arisen in the past decade. High pressure gas tubes, fluorescent tubes and LEDs (Light Emitting Diodes) are the most common light sources. The l 415 ± 10 nm wave length is the mostly used one, because it is well absorbed in the protoporphyrin IX (PpIX) in Propionibacterium acnes (P. acnes). Light-based PpIX disintegration leads into production of oxygen radicals that destroy the P. acnes. Recently, an evidence of the anti-inflammatory properties of blue light is becoming more recognized. The red light (630 nm) is also used in acne treatment. Better results are achieved when the phototherapy is combined with other treatment modalities (e.i. topical keratolytics). Relapses occuring shortly after finishing treatment series are the main drawback of optical treatment methods.
- MeSH
- Acne Vulgaris therapy MeSH
- Administration, Topical MeSH
- Photochemotherapy methods instrumentation trends MeSH
- Photosensitizing Agents administration & dosage therapeutic use MeSH
- Phototherapy economics classification trends MeSH
- Skin Absorption drug effects radiation effects MeSH
- Aminolevulinic Acid administration & dosage therapeutic use MeSH
- Low-Level Light Therapy methods trends MeSH
- Humans MeSH
- Adolescent MeSH
- Ultraviolet Therapy methods instrumentation trends MeSH
- Treatment Outcome MeSH
- Check Tag
- Humans MeSH
- Adolescent MeSH
We recently developed a new light source that allows for the continuous monitoring of light-induced changes using common spectrophotometric devices adapted for microplate analyses. This source was designed primarily to induce photodynamic processes in cell models. Modern light components, such as LED chips, were used to improve the irradiance homogeneity. In addition, this source forms a small hermetic chamber and thus allows for the regulation of the surrounding atmosphere, which plays a significant role in these light-dependent reactions. The efficacy of the new light source was proven via kinetic measurements of reactive oxygen species generated during the photodynamic reaction of chloroaluminium phthalocyanine disulfonate (ClAlPcS2) in three cell lines: human melanoma cells (G361), human breast adenocarcinoma cells (MCF7), and human fibroblasts (BJ).
This study presents a mathematical model, which expresses the absorbance of a photosynthetic sample as a non-linear polynomial of selected reference absorbance. The non-linearity is explained by inhomogeneities of a product of pigment concentration and light path length in the sample. The quadratic term of the polynomial reflects the extent of inhomogeneities, and the cubic term is related to deviation of the product distribution from a symmetric one. The model was tested by measurements of suspension of unstacked tobacco thylakoid membranes of different chlorophyll concentrations in cuvettes of different thicknesses. The absorbance was calculated from the diffuse transmittance and reflectance of sample, illuminated by perpendicular collimated light. The evaluated quantity was a sensitivity defined as the relative difference between the sample absorbance and the reference absorbance to the reference absorbance. The non-linearity of sample absorbance was demonstrated by a characteristic deviation of the sensitivity spectrum from a constant value. The absorbance non-linearity decreased on an increase of the product of pigment concentration and cuvette thickness. The model suggests that the sieve and detour effects influence the absorbance in a similar way. The model may be of interest in modeling of leaf or canopy optics including light absorption and scattering.
- MeSH
- Chlorophyll metabolism MeSH
- Photosynthesis radiation effects MeSH
- Plant Leaves physiology radiation effects MeSH
- Pigmentation radiation effects MeSH
- Light MeSH
- Nicotiana physiology radiation effects MeSH
- Remote Sensing Technology MeSH
- Models, Theoretical * MeSH
- Thylakoids radiation effects MeSH
- Publication type
- Journal Article MeSH
Optical mapping is a fluorescence-based physiological method to image spreading of action potential in excitable tissues, such as the heart and central nervous system. Because of the requirements for high speed imaging in low light conditions, highly sensitive high-speed cameras together with an optical system with maximum photon efficiency are required. While the optimization of these two components is relatively straightforward, the choice of the perfect light source is less simple; depending on the other (usually fixed) components, various parameters may acquire different weight in decision-making process. Here we describe the rationale for building an optical mapping setup and consider the relative advantages and disadvantages of three different commonly available light sources: mercury vapor lamp (HBO), xenon lamp (XBO), and light emitting diode (LED). Using the same optical system (fluorescence macroscope) and high-speed camera (Ultima L), we have tested each of the sources for its ability to provide bright and even illumination of the field of view and measured its temporal fluctuations in intensity. Then we used each in the actual optical mapping experiment using isolated, perfused adult mouse heart or chick embryonic heart to determine the actual signal to noise ratio at various acquisition rates. While the LED sources have undergone significant improvements in the recent past, the other alternatives may still surpass them in some parameters, so they may not be the automatic number one choice for every application.
- MeSH
- Action Potentials MeSH
- Fluorescent Dyes chemistry MeSH
- Chick Embryo MeSH
- Mice MeSH
- Heart physiology MeSH
- Light MeSH
- Calcium analysis metabolism MeSH
- Voltage-Sensitive Dye Imaging methods standards MeSH
- Animals MeSH
- Check Tag
- Chick Embryo MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
HYPOTHESIS: Higher light intensity settings do not yield improved image quality in endoscopic ear surgery. BACKGROUND: Light intensity is a parameter with major impact on the quality of digital images. For ear surgery, light produces heat associated with a thermal risk to ear structures and the light source setting should be accordingly optimized. METHODS: Several series of still images were acquired during live middle ear surgery, using cadaveric and plastic temporal bone models and with three-dimensional printed models. Images obtained under varying light intensities were compared with the image acquired at maximum intensity of a light emitting diode light source. We analyzed digital image brightness and noise using quantitative methods. RESULTS: Our measurements revealed significantly decreased image brightness with light intensities set below 20% with an increase in noise at light intensities lower than 30%. CONCLUSION: The optimal light source setting corresponded to 30% intensity in our experimental set-up. Special attention should be given to those cases where faster image quality degradation is expected (dark or bloody scenes or larger cavities). The results were strongly dependent on the equipment used. The methods described in this study can serve as a general guide for determining the optimal light source setting in any specific set-up.
- MeSH
- Endoscopy MeSH
- Humans MeSH
- Otologic Surgical Procedures * MeSH
- Temporal Bone MeSH
- Ear, Middle surgery MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Two alkylated verdazyl radicals (AlkVZs) were investigated as active compounds for photoinitiated controlled MCF-7 cell death. Observed results unambiguously showed that AlkVZ could be a potential structural moiety for the design of a novel family of photodynamic therapy agents. The main advantage of the proposed substances is an oxygen-independent generation of active radicals, which play a pivotal role in the treatment of oxygen-deficient tumors.
L-serine is one of the proteinogenic amino acids and participates in several essential processes in all organisms. In plants, the light-dependent photorespiratory and the light-independent phosphoserine pathways contribute to serine biosynthesis. In cyanobacteria, the light-dependent photorespiratory pathway for serine synthesis is well characterized, but the phosphoserine pathway has not been identified. Here, we investigated three candidate genes for enzymes of the phosphoserine pathway in Synechocystis sp. PCC 6803. Only the gene for the D-3-phosphoglycerate dehydrogenase is correctly annotated in the genome database, whereas the 3-phosphoserine transaminase and 3-phosphoserine phosphatase (PSP) proteins are incorrectly annotated and were identified here. All enzymes were obtained as recombinant proteins and showed the activities necessary to catalyse the three-step phosphoserine pathway. The genes coding for the phosphoserine pathway were found in most cyanobacterial genomes listed in CyanoBase. The pathway seems to be essential for cyanobacteria, because it was impossible to mutate the gene coding for PSP in Synechocystis sp. PCC 6803 or in Synechococcus elongatus PCC 7942. A model approach indicates a 30-60% contribution of the phosphoserine pathway to the overall serine pool. Hence, this study verified that cyanobacteria, similar to plants, use the phosphoserine pathway in addition to photorespiration for serine biosynthesis.
- MeSH
- Enzyme Activation MeSH
- Phosphoglycerate Dehydrogenase genetics metabolism MeSH
- Phosphoserine metabolism MeSH
- Metabolic Networks and Pathways * MeSH
- Molecular Sequence Data MeSH
- Gene Expression Regulation, Enzymologic MeSH
- Amino Acid Sequence MeSH
- Sequence Alignment MeSH
- Serine metabolism MeSH
- Substrate Specificity MeSH
- Light * MeSH
- Synechocystis physiology MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
This paper describes a compact video-ophthalmoscope (VO) designed for capturing retinal video sequences of the optic nerve head (ONH) under flicker light stimulation. The device uses an OLED display and a fiber optic-coupled LED light source, enabling high-frame-rate video at low illumination intensity (12 μW/cm2). Retinal responses were recorded in 10 healthy subjects during flicker light exposure with a pupil irradiance of 2 μW/cm2. Following 20 s of stimulation, all subjects displayed changes in retinal reflectance and pulsation attenuation, linked to blood flow and volume variations. These findings suggest that increased blood volume leads to decreased retinal reflectance. Temporal analysis confirmed the ability to capture flicker-induced retinal reflectance changes, indicating its potential for spatial and temporal analysis. Overall, this device offers a portable approach for investigating dynamic retinal responses to light stimuli, which can aid the diagnosis of retinal diseases like diabetic retinopathy, glaucoma, or neurodegenerative diseases affecting retinal blood circulation.
- MeSH
- Video Recording * instrumentation MeSH
- Adult MeSH
- Humans MeSH
- Young Adult MeSH
- Ophthalmoscopes * MeSH
- Retina * radiation effects physiology MeSH
- Photic Stimulation * MeSH
- Light * MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
