Search results for "Photobleaching"
showing 10 items of 59 documents
Photobleaching measurements of pigmented and vascular skin lesions: results of a clinical trial
2011
The autofluorescence photobleaching intensity dynamics of in vivo skin and skin pathologies under continuous 532 nm laser irradiation have been studied. Overall the 141 human skin malformations were investigated by laser induced skin autofluorescence photobleaching analysis. Details of equipment are described along with some measurement results illustrating potentiality of the technology.
Imaging of LED-excited autofluorescence photobleaching rates for skin diagnostics
2019
The aim of this study is to develop a novel non-invasive approach for skin cancer (melanoma, basal cell and squamous cell carcinomas) diagnostics by mapping the AF intensity decrease (photo-bleaching) rates under continuous 405 nm LED excitation. For parametric mapping of skin AF intensity decrease rates a sequence of filtered AF imaging under 405 nm LED excitation for 20 seconds at a power density of ~7 mW/cm2 with a frame rate 0.5 fps was recorded and analyzed by cloud-based prototype device. Several clinical cases and potential future applications of the proposed autofluorescence photobleaching rate imaging technique are discussed.
Unraveling In vivo brain transport of protein‐coated fluorescent nanodiamonds
2019
The blood–brain barrier is the biggest hurdle to overcome for the treatment of neurological disorders. Here, protein‐coated nanodiamonds are delivered to the brain and taken up by neurovascular unit cells after intravenous injection. Thus, for the first time, nanodiamonds with their unique properties and a flexible protein coating for the attachment of therapeutics emerge as a potential platform for nanotheranostics of neurological disorders.Nanotheranostics, combining diagnostics and therapy, has the potential to revolutionize treatment of neurological disorders. But one of the major obstacles for treating central nervous system diseases is the blood–brain barrier (BBB) preventing systemic…
MOLECULAR BASIS OF DRUG PHOTOTOXICITY: PHOTOSENSITIZED CELL DAMAGE BY THE MAJOR PHOTOPRODUCT OF TIAPROFENIC ACID
1994
Tiaprofenic acid is a photosensitizing nonsteroidal anti-inflammatory drug, whose major photoproduct (decarboxytiaprofenic acid) is also a potent photosensitizer. Because of the lack of the carboxylate moiety, this photoproduct is more lipophilic and might bind more efficiently to cell membranes, thereby causing phototoxic damage. To verify the feasibility of this hypothesis, we have prepared the 3H-labeled analogs of tiaprofenic acid and its photoproduct and examined the binding, persistence and phototoxicity of the photoproduct using poorly metabolizing (fibroblasts) and actively metabolizing cells (hepatocytes). The photoproduct of tiaprofenic acid accumulates in both cell types as it is…
Structural and Functional Analysis of the Antiparallel Strands in the Lumenal Loop of the Major Light-harvesting Chlorophyll a/b Complex of Photosyst…
2007
The light-harvesting chlorophyll a/b-binding protein of photosystem II (LHCIIb) fulfills multiple functions, such as light harvesting and energy dissipation under different illuminations. The crystal structure of LHCIIb at the near atomic resolution reveals an antiparallel strands structure in the lumenal loop between the transmembrane helices B/C. To study the structural and functional significances of this structure, three amino acids (Val-119, His-120, and Ser-123) in this region have been exchanged to Phe, Leu, and Gly, respectively, and the influence of the mutagenesis on the structure and function of LHCIIb has been investigated. The results are as follows. 1) Circular dichroism spect…
Lasers for in-vivo skin diagnostics: some recent developments
2019
The recent advancements of three laser-based diagnostic technologies developed at the Riga group are briefly reviewed: (i) RGB imaging of cw-laser excited skin autofluorescence intensity and photobleaching rate distributions, (ii) ps-laser excited skin autofluorescence and diffuse reflectance kinetics analysis, (iii) snapshot RGB skin chromophore mapping under triple-laser illumination. These techniques have passed preliminary laboratory and clinical tests which have demonstrated a promising potential for further implementation in portable devices for routine clinical applications. Operation principles, set-up schemes and some clinical results obtained by the above-mentioned techniques are …
Dynamics and interactions of parvoviral NS1 protein in the nucleus
2007
Summary Nuclear positioning and dynamic interactions of viral proteins with nuclear substructures play essen- tial roles during infection with DNA viruses. Visual- ization of the intranuclear interactions and motility of the parvovirus replication protein (NS1) in living cells gives insight into specific parvovirus protein- cellular structure interactions. Confocal analysis of highly synchronized infected Norden Laboratory Feline Kidney cells showed accumulation of nuclear NS1 in discrete interchromosomal foci. NS1 fused with enhanced yellow fluorescence protein (NS1- EYFP) provided a marker in live cells for dynamics of NS1 traced by photobleaching techniques. Fluo- rescence Recovery after…
Diffusion of small molecules in edible films: Effect of water and interactions between diffusant and biopolymer
2008
Mass transfers of various molecules in multiphasic food products lead to quality modification and thus require the use of edible films or coatings in-between the foodstuff. Consequently, it is important to assess the barrier properties and efficiencies of edible films as well as to determine the diffusivities of the migrants. Translational diffusion of a reference molecule such as fluorescein, determined by the fluorescence recovery after photobleaching (FRAP) method, displays a threshold of a critical water content inducing an increase of the molecular mobility, and demonstrates that multiple populations of a single molecular specie can be involved in different diffusion kinetics. Further …
Protein diffusion in mammalian cell cytoplasm.
2011
We introduce a new method for mesoscopic modeling of protein diffusion in an entire cell. This method is based on the construction of a three-dimensional digital model cell from confocal microscopy data. The model cell is segmented into the cytoplasm, nucleus, plasma membrane, and nuclear envelope, in which environment protein motion is modeled by fully numerical mesoscopic methods. Finer cellular structures that cannot be resolved with the imaging technique, which significantly affect protein motion, are accounted for in this method by assigning an effective, position-dependent porosity to the cell. This porosity can also be determined by confocal microscopy using the equilibrium distribut…