Página 16 dos resultados de 2289 itens digitais encontrados em 0.009 segundos

In vitro studies of cutaneous retention of magnetic nanoemulsion loaded with zinc phthalocyanine for synergic use in skin cancer treatment

PRIMO, Fernando L.; RODRIGUES, Marcilene M. A.; SIMIONI, Andreza R.; BENTLEY, Maria V. L. B.; MORAIS, Paulo C.; TEDESCO, Antonio C.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
In this study was developed a new nano drug delivery system (NDDS) based on association of biodegradable surfactants with biocompatible magnetic fluid of maguemita citrate derivative. This formulation consists in a magnetic emulsion with nanostructured colloidal particles. Preliminary in vitro experiments showed that the formulation presents a great potential for synergic application in the topical release of photosensitizer drug (PS) and excellent target tissue properties in the photodynamic therapy (PDT) combined with hyperthermia (HPT) protocols. The physical chemistry characterization and in vitro assays were carried out by Zn(II) Phtalocyanine (ZnPc) photosensitizer incorporated into NDDS in the absence and the presence of magnetic fluid, showed good results and high biocompatibility. In vitro experiments were accomplished by tape-stripping protocols for quanti. cation of drug association with different skin tissue layers. This technique is a classical method for analyses of drug release in stratum corneum and epidermis+ dermis skin layers. The NDDS formulations were applied directly in pig skin (tissue model) fixed in the cell`s Franz device with receptor medium container with a PBS/EtOH 20% solution (10mM, pH 7.4) at 37 degrees C. After 12 h of topical administration stratum corneum was removed from fifty tapes and the ZnPc retained was evaluated by solvent extraction in dimetil-sulphoxide under ultrasonic bath. These results indicated that magnetic nanoemulsion (MNE) increase the drug release on the deeper skin layers when compared with classical formulation in the absence of magnetic particles. This could be related with the increase of biocompatibility of NDDS due to the great affinity for the polar extracelullar matrix in the skin and also for the increase in the drug partition inside of corneocites wall. (C) 2008 Elsevier B.V. All rights reserved.

Iontophoretic transport of zinc phthalocyanine tetrasulfonic acid as a tool to improve drug topical delivery

SOUZA, Joel G.; GELFUSO, Guilherme M.; SIMAO, Patricia S.; BORGES, Antonio C.; LOPEZ, Renata F. V.
Fonte: LIPPINCOTT WILLIAMS & WILKINS Publicador: LIPPINCOTT WILLIAMS & WILKINS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
Phthalocyanines have been used as systemic photosensitizers because of their high affinity towards tumour tissue, and the high rates of reactive oxygen species produced when they are irradiated during photodynamic therapy. However, the topical administration of these compounds is limited by their large size, poor hydrosolubility and ionic character. This study aimed to investigate the iontophoretic delivery of charged zinc phthalocyanine tetrasulfonic acid (ZnPcS(4)) from a hydrophilic gel to different skin layers by means of in-vitro and in-vivo studies. Six hours of passive administration was insufficient for ZnPcS(4) to cross the stratum corneum (SC) and to reach the epidermis and dermis. No positive effect was reached when anodal iontophoresis was performed, showing that the drug-electrode attraction effect was higher than the electro-osmosis contribution at a pH of 5.5. Cathodal iontophoresis, however, was able to transport significant amounts of the drug to the viable epidermis. In addition, the absence of NaCl in the formulation significantly increased (by five-fold) the amount of ZnPcS(4) that crossed the SC and accumulated in the epidermis and dermis. It was possible to visualize the drug accumulation in the follicle openings and in the epidermis...

Preparation, characterization and in vitro cytotoxicity of BSA-based nanospheres containing nanosized magnetic particles and/or photosensitizer

RODRIGUES, Marcilene M. A.; SIMIONI, Andreza R.; PRIMO, Fernando L.; SIQUEIRA-MOURA, Marigilson P.; MORAIS, Paulo C.; TEDESCO, Antonio C.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
This study reports on the preparation, characterization and in vitro toxicity test of a new nano-drug delivery system (NDDS) based on bovine serum albumin (BSA) nanospheres which incorporates surface-functionalized magnetic nanoparticles (MNP) and/or the silicon(IV) phthalocyanine (NzPc). The new NDDS was engineered for use in photodynamic therapy (PDT) combined with hyperthermia (HPT) to address cancer treatment. The BSA-based nanospheres, hosting NzPc, MNP or both (NzPc and MNP), present spherical shape with hydrodynamic average diameter values ranging from 170 to 450 nm and zeta potential of around -23 mV. No difference on the fluorescence spectrum of the encapsulated NzPc was found regardless of the presence of MNP. Time-dependent fluorescence measurements of the encapsulated NzPc revealed a bi-exponential decay for samples incorporating only NzPc and NzPc plus MNP, in the time window ranging from 1.70 to 5.20 ns. The in vitro assay, using human fibroblasts, revealed no cytotoxic effect in all samples investigated, demonstrating the potential of the tested system as a synergistic NDDS. (C) 2009 Elsevier B.V. All rights reserved.

Retrograde delivery of photosensitizer (TPPp-O-beta-GluOH)(3) selectively potentiates its photodynamic activity

AMESSOU, Mohamed; CARREZ, Daniele; PATIN, Delphine; SARR, Marianne; GRIERSON, David S.; CROISY, Alain; TEDESCO, Antonio C.; MAILLARD, Philippe; JOHANNES, Ludger
Fonte: AMER CHEMICAL SOC Publicador: AMER CHEMICAL SOC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
Photodynamic therapy involves administration of a photosensitizing drug and its subsequent activation by visible light of the appropriate wavelength. Several approaches to increasing the specificity of photosensitizers for cancerous tissues and, in particular, through their conjugation to ligands that are directed against tumor-associated antigens have been investigated. Here, we have studied the delivery of the photocytotoxic porphyrin compound TPP(p-O-beta-D-GluOH)(3) into tumor cells that overexpress the glycosphingolipid Gb3, using the Gb3-binding nontoxic B-subunit of Shiga toxin (STxB) as a vector. To allow for site-directed chemical coupling, an STxB variant carrying a free sulfhydryl moiety at its C-terminal end has been used. Binding affinity, cellular uptake, singlet oxygen quantum yield, and phototoxicity of the conjugate have been examined. Despite some effect of coupling on both the photophysical properties of TPP(p-O-beta-D-GluOH)(3) and the affinity of STxB for its receptor, the conjugate exhibited a higher photocytotoxic activity than the photosensitizer alone and was exquisitely selective for Gb3-expressing tumor cells. Furthermore, our data strongly suggest that STxB-mediated retrograde delivery of the photosensitizer to the biosynthetic/secretory pathway is critical for optimal cytotoxic activity. In conclusion...

Dextrin-microencapsulated porphyrin - Luminescent properties

LUZ, Priscilla Parva; NERI, Claudio Roberto; SERRA, Osvaldo Antonio
Fonte: BLACKWELL PUBLISHING Publicador: BLACKWELL PUBLISHING
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
Photophysical properties of porphyrins in aqueous solutions are strongly affected by aggregation. One possible solution to this problem is to encapsulate the porphyrin into polymeric spheres, to provide an environment where the photosensitizer can be administered in its monomeric form in such treatments as photodynamic therapy. Here we report the microencapsulation of the meso-tetrakis(4-sulphonatophenyl) porphyrin (TPPS4) photosensitizer by the ultrasonic spray-drying technique. The encapsulated TPPS4 was morphologically characterized by scanning electron microscopy, and its photophysical properties were studied and compared with those of a physical blend of dextrin and TPPS4. We Successfully encapsulated TPPS4 into dextrin microspheres, and the encapsulated photosensitizer displays higher luminescence intensity than that of the prepared physical blends.

Effect of Diode-Laser and AC Magnetic Field of Bovine Serum Albumin Nanospheres Loaded with Phthalocyanine and Magnetic Particles

SIMIONI, Andreza Ribeiro; RODRIGUES, Marcilene M. A.; PRIMO, Fernando L.; MORAIS, Paulo C.; TEDESCO, Antonio Claudio
Fonte: AMER SCIENTIFIC PUBLISHERS Publicador: AMER SCIENTIFIC PUBLISHERS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
This study reports on the development and characterization of bovine serum albumin (BSA) nanospheres containing Silicon(IV) phthalocyanine (NzPc) and/or maghemite nanoparticles (MNP), the latter introduced via ionic magnetic fluid (MF). The nanosized BSA-loaded samples were designed for synergic application while combining Photodynamic Therapy and Hyperthermia. Incorporation of MNP in the albumin-based template, allowing full control of the magnetic content, was accomplished by adding a highly-stable ionic magnetic fluid sample to the albumin suspension, following heat denaturing. The material`s evaluation was performed using Zeta potential measurements and scanning electron microscopy. The samples were characterized by steady-state techniques and time-resolved fluorescence. The in vitro assay, using human fibroblasts, revealed no cytotoxic effect in all samples investigated, demonstrating the potential of the tested system as a synergistic drug delivery system.; (FAPES)[09/51729-5]; (FAPES)[09/15363-6]; (FAPES)[07/01548-9]

Photodynamic therapy for acne vulgaris: A critical review from basics to clinical practice Part II. Understanding parameters for acne treatment with photodynamic therapy

SAKAMOTO, Fernanda H.; TOREZAN, Luis; ANDERSON, R. Rox
Fonte: MOSBY-ELSEVIER Publicador: MOSBY-ELSEVIER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
Photodynamic therapy requires a photosensitizer, oxygen, and activating light. For acne, pilosebaceous units are ""target"" structures. Porphyrins are synthesized in vivo from 5-aminolevulinic acid (ALA), particularly in pilosebaceous units. Different photosensitizers and drug delivery methods have been reported for acne treatment. There are a variety of porphyrin precursors with different pharmacokinetic properties. Among them, ALA and methyl-ester of ALA (MAT.) are available for possible off-label treatment of acne vulgaris. In addition, various light sources, light dosimetry, drug incubation time, and pre- and posttreatment care also change efficacy and side effects. None of these variables has been optimized for acne treatment, but a number of clinical trials provide helpful guidance. In this paper, we critically analyze clinical trials, case reports, and series of cases published through 2009. (J Am Acad Dermatol 2010;63:195-211.)

Influence of pH on the phototransformation process of PhotogemA (R)

MENEZES, P. F. C.; IMASATO, H.; BAGNATO, Vanderlei Salvador; SIBATA, Cl. H.; PERUSSI, J. R.
Fonte: MAIK NAUKA/INTERPERIODICA/SPRINGER Publicador: MAIK NAUKA/INTERPERIODICA/SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
PhotogemA (R) is a hematoporphyrin derivative that has been used as a photosensitizer in experimental and clinical Photodynamic Therapy (PDT) in Brazil. Photosensitizers are degraded under illumination. This process, usually called photobleaching, can be monitored by decreasing in fluorescence intensities and includes the following photoprocesses: photodegradation, phototransformation, and photorelocalization. Photobleaching of hematoporphyrin-type sensitizers during illumination in aqueous solution is related not only to photodegradation but is also followed by the formation of photoproducts with a new fluorescence band at around 640-650 nm and with increased light absorption in the red spectral region at 640 nm. In this study, the influence of pH on the phototransformation process was investigated. PhotogemA (R) solutions, 40 mu g/ml, were irradiated at 514 nm with intensity of 100 mW/cm(2) for 20 min with different pH environments. The controls were performed with the samples in the absence of light. The PhotogemA (R) photodegradation is dependent on the pH. The behavior of photodegradation and photoproducts formation (monitored at 640 nm) is distinct and depends on the photosensitizer concentration. The processes of degradation and photoproducts formation were monitored with Photogemin the concentration of 40 mu g/mL since that demonstrated the best visualization of both processes. While below pH 5 the photodegradation occurred...

Analysis of the combined effect of lasers of different wavelengths for PDT outcome using 600, 630, and 660 nm

ATIF, M.; FAKHAR-E-ALAM, M.; SABINO, L. G.; IKRAM, M.; ARAUJO, M. T. de; KURACHI, Cristina; BAGNATO, Vanderlei Salvador; ALSALHI, M. S.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
We investigated the effects of photodynamic therapy (PDT) outcome when combining three laser systems that produce light in three different wavelengths (600, 630, and 660 nm). Cooperative as well as independent effects can be observed. We compared the results of the combined wavelengths of light with the effect of single laser for the excitation of the photosensitizer. In the current experiment, the used photosensitizer was Photogem (R) (1.5 mg/kg). Combining two wavelengths for PDT, their cumulative dose and different penetrability may change the overall effect of the fluence of light, which can be effective for increasing the depth of necrosis. This evaluation was performed by comparing the depth and specific aspect of necrosis obtained by using single and dual wavelengths for irradiation of healthy liver of male Wistar rats. We used 15 animals and divided them in five groups of three animals. First, Photogem (R) was administered; follow by measurement of the fluorescence spectrum of the liver before PDT to confirm the level of accumulation of photosensitizer in the tissue. After that, an area of 1 cm(2) of the liver was illuminated using different laser combinations. Qualitative analysis of the necrosis was carried out through histological and morphological study. [GRAPHICS] (a) - microscopic images of rat liver cells...

Major determinants of photoinduced cell death: Subcellular localization versus photosensitization efficiency

OLIVEIRA, Carla S.; TURCHIELLO, Rozane; KOWALTOWSKI, Alicia J.; INDIG, Guilherme L.; BAPTISTA, Mauricio S.
Fonte: ELSEVIER SCIENCE INC Publicador: ELSEVIER SCIENCE INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
We present a study on whether and to what extent subcellular localization may compete favorably with photosensitization efficiency with respect to the overall efficiency of photoinduced cell death. We have compared the efficiency with which two cationic photosensitizers, namely methylene blue (MB) and crystal violet (CV), induce the photoinduced death of human cervical adenocarcinoma (HeLa) cells. Whereas MB is well known to generate singlet oxygen and related triplet excited species with high quantum yields in a variety of biological and chemical environments (i.e., acting as a typical type II photosensitizer), the highly mitochondria-specific CV produces triplet species and singlet oxygen with low yields, acting mostly via the classical type I mechanism (e.g., via free radicals). The findings described here indicate that the presumably more phototoxic type II photosensitizer (MB) does not lead to higher degrees of cell death compared to the type I (CV) photosensitizer. In fact, CV kills cells with the same efficiency as MB, generating at least 10 times fewer photoinduced reactive species. Therefore, subcellular localization is indeed more important than photochemical reactivity in terms of overall cell killing, with mitochondrial localization representing a highly desirable property for the development of more specific/efficient photosensitizers for photodynamic therapy applications. (C) 2011 Elsevier Inc. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP; CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); American Cancer Society; American Cancer Society[RSG-02-026-01-CDD]

Relationship between structure and photoactivity of porphyrins derived from protoporphyrin IX

UCHOA, Adjaci F.; OLIVEIRA, Carla S.; BAPTISTA, Mauricio S.
Fonte: WORLD SCI PUBL CO INC Publicador: WORLD SCI PUBL CO INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.69741%
Protoporphyrin (Pp IX) derivatives were prepared to study the relationship between photosensitizer structure and photoactivity, with an emphasis on understanding the role of membrane interactions in the efficiency of photosensitizers used in photodynamic therapy (PDT). The synthetic strategies described here aimed at changing protoporphyrin periferic groups, varying overall charge and oil/water partition, while maintaining their photochemical properties. Three synthetic routes were used: (1) modification of Pp IX at positions 3(1) and 8(1) by addition of alkyl amine groups of different lengths (compounds 2-5), (2) change of Pp IX at positions 13(3) and 17(3), generating alkyl amines (compounds 6 and 7), a phosphate amine (compound 8), and quarternary ammonium compounds (compounds 9 and 10), and (3) amine-alkylation of Hematoporphyrin IX (Hp IX) at positions 3(1), 8(1), 13(3) and 17(3) (compound 12). Strategy 1 leads to hydrophobic compounds with low photocytotoxicity. Strategy 2 leads to compounds 6-10 that have high levels of binding/incorporation in vesicles, mitochondria and cells, which are indicative of high bioavailability. Addition of the phosphate group (compound 8), generates an anionic compound that has low liposome and cell incorporation...

Concepts and Principles of Photodynamic Therapy as an Alternative Antifungal Discovery Platform

Dai, Tianhong; Fuchs, Beth B.; Coleman, Jeffrey J.; Prates, Renato A.; Astrakas, Christos; St. Denis, Tyler G.; Ribeiro, Martha S.; Mylonakis, Eleftherios; Hamblin, Michael R.; Tegos, George P.
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica
Publicado em 10/04/2012 EN
Relevância na Pesquisa
47.72437%
Opportunistic fungal pathogens may cause superficial or serious invasive infections, especially in immunocompromised and debilitated patients. Invasive mycoses represent an exponentially growing threat for human health due to a combination of slow diagnosis and the existence of relatively few classes of available and effective antifungal drugs. Therefore systemic fungal infections result in high attributable mortality. There is an urgent need to pursue and deploy novel and effective alternative antifungal countermeasures. Photodynamic therapy (PDT) was established as a successful modality for malignancies and age-related macular degeneration but photodynamic inactivation has only recently been intensively investigated as an alternative antimicrobial discovery and development platform. The concept of photodynamic inactivation requires microbial exposure to either exogenous or endogenous photosensitizer molecules, followed by visible light energy, typically wavelengths in the red/near infrared region that cause the excitation of the photosensitizers resulting in the production of singlet oxygen and other reactive oxygen species that react with intracellular components, and consequently produce cell inactivation and death. Antifungal PDT is an area of increasing interest...

Real-Time Monitoring of Photocytotoxicity in Nanoparticles-Based Photodynamic Therapy: A Model-Based Approach

Benachour, Hamanou; Bastogne, Thierry; Toussaint, Magali; Chemli, Yosra; Sève, Aymeric; Frochot, Céline; Lux, François; Tillement, Olivier; Vanderesse, Régis; Barberi-Heyob, Muriel
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 07/11/2012 EN
Relevância na Pesquisa
47.72437%
Nanoparticles are widely suggested as targeted drug-delivery systems. In photodynamic therapy (PDT), the use of multifunctional nanoparticles as photoactivatable drug carriers is a promising approach for improving treatment efficiency and selectivity. However, the conventional cytotoxicity assays are not well adapted to characterize nanoparticles cytotoxic effects and to discriminate early and late cell responses. In this work, we evaluated a real-time label-free cell analysis system as a tool to investigate in vitro cyto- and photocyto-toxicity of nanoparticles-based photosensitizers compared with classical metabolic assays. To do so, we introduced a dynamic approach based on real-time cell impedance monitoring and a mathematical model-based analysis to characterize the measured dynamic cell response. Analysis of real-time cell responses requires indeed new modeling approaches able to describe suited use of dynamic models. In a first step, a multivariate analysis of variance associated with a canonical analysis of the obtained normalized cell index (NCI) values allowed us to identify different relevant time periods following nanoparticles exposure. After light irradiation, we evidenced discriminant profiles of cell index (CI) kinetics in a concentration- and light dose-dependent manner. In a second step...

Effects of chlorin e6-mediated photodynamic therapy on human colon cancer SW480 cells

Li, Yuhua; Yu, Yalu; Kang, Ling; Lu, Ying
Fonte: e-Century Publishing Corporation Publicador: e-Century Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 15/12/2014 EN
Relevância na Pesquisa
47.72437%
Objective: This study is to investigate the antitumor effects and possible mechanisms of chlorin e6-mediated photodynamic therapy (Ce6-PDT) on human colon cancer SW480 cells. Methods: SW480 cells were treated with Ce6, followed by photodynamic irradiation. Subcellular localization of Ce6 in SW480 cells was observed with confocal laser scanning microscopy (LSCM). Reactive oxygen species (ROS) levels were monitored with fluorescence microscopy. Cell proliferation and apoptosis were detected by the MTT assay and flow cytometry, respectively. Scratch test and colony formation assay were employed to analyze the cell migration ability and colony formation ability. Results: LSCM showed that, in SW480 cells, Ce6 was evenly distributed within the ER and lysosomes, with nearly no distribution in the mitochondria and nuclei. When SW480 cells were subjected to Ce6-PDT, the ROS levels would be elevated, in a dose-dependent manner. Moreover, Ce6-PDT treatment could inhibit the cell proliferation and enhance the apoptotic process, in SW480 cells. However, Ce6 treatment alone without photodynamic irradiation could not induce any significant differences in the cell proliferation and apoptosis. In addition, the migration ability and colony formation ability of SW480 cells were decreased by Ce6-PDT treatment at appropriate dosages. Conclusion: Ce6-PDT treatment could enhance ROS production and apoptosis...

In vivo measurement of fluorescence emission in the human prostate during photodynamic therapy

Finlay, Jarod C.; Zhu, Timothy C.; Dimofte, Andreea; Stripp, Diana; Malkowicz, S. Bruce; Whittington, Richard; Miles, Jeremy; Glatstein, Eli; Hahn, Stephen M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 22/04/2005 EN
Relevância na Pesquisa
47.72437%
Among the challenges to the clinical implementation of photodynamic therapy (PDT) is the delivery of a uniform photodynamic dose to induce uniform damage to the target tissue. As the photodynamic dose depends on both the local sensitizer concentration and the local fluence rate of treatment light, knowledge of both of these factors is essential to the delivery of uniform dose. In this paper, we investigate the distribution and kinetics of the photosensitizer motexafin lutetium (MLu, Lutrin®) as revealed by its fluorescence emission. Our current prostate treatment protocol involves interstitial illumination of the organ via cylindrical diffusing fibers (CDF’s) inserted into the prostate though clear catheters. For planning and treatment purposes, the prostate is divided into 4 quadrants. We use one catheter in each quadrant to place an optical fiber-based fluorescence probe into the prostate. This fiber is terminated in a beveled tip, allowing it to deliver and collect light perpendicular to the fiber axis. Excitation light is provided by a 465 nm light emitting diode (LED) source coupled to a dichroic beamsplitter, which passes the collected fluorescence emission to a CCD spectrograph. Spectra are obtained before and after PDT treatment in each quadrant of the prostate and are analyzed via a linear fitting algorithm to separate the MLu fluorescence from the background fluorescence originating in the plastic catheter. A computer-controlled step motor allows the excitation/detection fiber to be moved along the catheter...

Effect of Factor XIII-A G185T Polymorphism on Visual Prognosis after Photodynamic Therapy for Neovascular Macular Degeneration

Parmeggiani, Francesco; Costagliola, Ciro; Semeraro, Francesco; Romano, Mario R; Rinaldi, Michele; Gallenga, Carla Enrica; Serino, Maria Luisa; Incorvaia, Carlo; D’Angelo, Sergio; De Nadai, Katia; Dell’Omo, Roberto; Russo, Andrea; Gemmati, Donato; Per
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 20/08/2015 EN
Relevância na Pesquisa
47.72437%
Macular degenerations represent leading causes of central blindness or low vision in developed countries. Most of these severe visual disabilities are due to age-related macular degeneration (AMD) and pathologic myopia (PM), both of which are frequently complicated by subfoveal choroidal neovascularization (CNV). Photodynamic therapy with verteporfin (PDT-V) is still employed for CNV treatment in selected cases or in combined regimen. In Caucasian patients, the common polymorphism G185T of factor XIII-A gene (FXIII-A-G185T; rs5985) has been described as predictor of poor angiographic CNV responsiveness to PDT-V. Nevertheless, the prognostic implications of this pharmacogenetic determinant on long-term visual outcome after a PDT-V regimen have not been evaluated. We retrospectively selected Caucasian patients presenting with treatment-naive CNV and receiving standardized PDT-V protocol for two years. The study population included patients affected by subfoveal CNV secondary to AMD or PM. We assessed the correlations between the polymorphic allele T of FXIII-A-G185T and: (1) total number of photodynamic treatments; and (2) change in visual acuity from baseline to the end of the follow-up period. Considering a total study population of 412 patients with neovascular AMD or PM...

Concepts and Principles of Photodynamic Therapy as an Alternative Antifungal Discovery Platform

Fuchs, Beth B.; Prates, Renato A.; Astrakas, Christos; St. Denis, Tyler G.; Ribeiro, Martha S.; Dai, Tianhong; Coleman, Jeffrey James; Mylonakis, Eleftherios; Hamblin, Michael; Tegos, George
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
47.72437%
Opportunistic fungal pathogens may cause superficial or serious invasive infections, especially in immunocompromised and debilitated patients. Invasive mycoses represent an exponentially growing threat for human health due to a combination of slow diagnosis and the existence of relatively few classes of available and effective antifungal drugs. Therefore systemic fungal infections result in high attributable mortality. There is an urgent need to pursue and deploy novel and effective alternative antifungal countermeasures. Photodynamic therapy (PDT) was established as a successful modality for malignancies and age-related macular degeneration but photodynamic inactivation has only recently been intensively investigated as an alternative antimicrobial discovery and development platform. The concept of photodynamic inactivation requires microbial exposure to either exogenous or endogenous photosensitizer molecules, followed by visible light energy, typically wavelengths in the red/near infrared region that cause the excitation of the photosensitizers resulting in the production of singlet oxygen and other reactive oxygen species that react with intracellular components, and consequently produce cell inactivation and death. Antifungal PDT is an area of increasing interest...

Reflectance and fluorescence spectroscopies in photodynamic therapy

Finlay, Jarod C. (1975 - ); Foster, Thomas H.
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xxv, 343 leaves
ENG
Relevância na Pesquisa
47.72437%
Thesis (Ph. D.)--University of Rochester. Dept. of Physics and Astronomy, 2004.; In vivo fluorescence spectroscopy during photodynamic therapy (PDT) has the potential to provide information on the distribution and degradation of sensitizers, the formation of fluorescent photoproducts and changes in tissue autofluorescence induced by photodynamic treatment. Reflectance spectroscopy allows quantification of light absorption and scattering in tissue. We present the results of several related studies of fluorescence and reflectance spectroscopy and their applications to photodynamic dosimetry. First, we develop and test an empirical method for the correction of the distortions imposed on fluorescence spectra by absorption and scattering in turbid media. We characterize the irradiance dependence of the in vivo photobleaching of three sensitizers, protoporphyrin IX (PpIX), Photofrin and mTHPC, in a rat skin model. The photobleaching and photoproduct formation of PpIX exhibit irradiance dependence consistent with singlet oxygen (1O2)-mediated bleaching. The bleaching of mTHPC occurs in two phases, only one of which is consistent with a 1O2-mediated mechanism. Photofrin’s bleaching is independent of irradiance, although its photoproduct formation is not. This can be explained by a mixed-mechanism bleaching model. Second...

Photodynamic therapy influence on anti-cancer immunity

Isaeva, O. G.; Osipov, V. A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.72437%
The system of partial differential equations describing tumor-immune dynamics with angiogenesis taken into account is presented. For spatially homogeneous case, the steady state analysis of the model is carried out. The effects of single photodynamic impact are numerically simulated. In the case of strong immune response we found that the photodynamic therapy (PDT) gives rise to the substantial shrinkage of tumor size which is accompanied by the increase of interleukin-2 concentration. On the contrary, the photodynamic stimulation of weak immune response is shown to be insufficient to reduce the tumor. These findings indicate the important role of anti-cancer immune response in the long-term tumor control after PDT.; Comment: 9 pages, 5 figures

Ultrastructural effects of two phthalocyanines in CHO-K1 and HeLa cells after laser irradiation

de CastroPazos,Marcelo; Pacheco-Soares,Cristina; Soares da Silva,Newton; DaMatta,Renato Augusto; Pacheco,Marcos Tadeu T.
Fonte: Biocell Publicador: Biocell
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2003 EN
Relevância na Pesquisa
47.72437%
The effects of Photodynamic Therapy using 2nd generation photosensitizers have been widely investigated aiming clinical application treatment of solid neoplasms. In this work, ultrastructure changes caused by the action of two 2nd generation photosensitizers and laser irradiation on CHO-K1 and HeLa (neoplastic) cells were analyzed by transmission electron microscopy. Aluminum phthalocyanine chloride, aluminum phthalocyanine tetrasulfonate chloride and radiation from a semiconductor laser at a fluency of 0.5 J/cm² (Power=26mW; l=670nm) were used. The results showed induction of apoptosis. Such alterations where observed in HeLa but not in CHO-K1 cells after Aluminum phthalocyanine tetrasulfonate chloride (AlPcS4) photodynamic treatment. The Aluminum phthalocyanine chloride (AlPc) photodynamic treatment induced necrosis on the neoplastic cell line, and cytoplasm and nuclear alterations on the normal cell line.