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Fluorescence Kinetics (fluorescence + kinetics)
Selected AbstractsFluorescence Kinetics of Protoporphyrin-IX Induced from 5-ALA Compounds in Rabbit Postballoon Injury Model for ALA-PhotoangioplastyPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2008Oh-Choon Kwon Protoporphyrin IX (PpIX) is one of the photodynamically active substances that are endogenously synthesized in the metabolic pathway for heme as a precursor. Aminolevulinic acid-esters are more lipophilic than conventional 5-aminolevulinic acid (ALA) and some of them are currently being approved as new drugs for photodynamic diagnosis (PDD) and photodynamic therapy (PDT). In order to investigate the pharmacokinetics of ALA and ALA-ethyl ester (ALA-ethyl) in the atheromatous plaque and normal aortic wall of rabbit postballoon injured artery, each 60 mg kg,1 of ALA or ALA-ethyl was injected intravenously followed by serial detection of PpIX fluorescence of harvested arteries at 0,48 h post-injection. Maximum PpIX build-up in the atheromatous plaque was seen at 2 h after injecting ALA. In contrast, it occurred at 9 h after injecting ALA-ethyl. In addition, the selective build-up of ALA in the atheromatous plaque compared to normal vessel wall was much higher (10 times) than that of ALA-ethyl. The time of maximum fluorescence intensity of PpIX was employed as drug-light-interval for subsequent PDT treatment of the atheromatous plaque with 50,150 J cm,1 of light dose. Significant reduction in plaque was observed without damage of the medial wall at both groups, but smooth muscle cell (SMC) was still present in the media region below the PDT-treated atheromatous plaque. In conclusion, ALA may be a more effective compound for endovascular PDT treatment of the atheromatous plaque compared with ALA-ethyl based on their pharmacokinetics, but further optimization of PDT methodology remains to remove completely residual SMC in the media for preventing potential restenosis. [source] Protoporphyrin IX Fluorescence Kinetics and Localization after Topical Application of ALA Pentyl Ester and ALA on Hairless Mouse Skin with UVB-Induced Early Skin CancerPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2000Johanna T. H. M. van den Akker ABSTRACT In order to improve the efficacy of 5-aminolevulinic acid-based (ALA) photodynamic therapy (PDT), different ALA derivatives are presently being investigated. ALA esters are more lipophilic and therefore may have better skin penetration properties than ALA, possibly resulting in enhanced protoporphyrin IX (PpIX) production. In previous studies it was shown that ALA pentyl ester (ALAPE) does considerably enhance the PpIX production in cells in vitro compared with ALA. We investigated the in vivo PpIX fluorescence kinetics after application of ALA and ALAPE to hairless mice with and without UVB-induced early skin cancer. ALA and ALAPE (20% wt/wt) were applied topically to the mouse skin and after 30 min, the solvent was wiped off and PpIX fluorescence was followed in time with in vivo fluorescence spectroscopy and imaging. At 6 and 12 h after the 30 min application, skin samples of visible lesions and adjacent altered skin (UVB-exposed mouse skin) and normal mouse skin were collected for fluorescence microscopy. From each sample, frozen sections were made and phase contrast images and fluorescence images were recorded. The in vivo fluorescence kinetics showed that ALAPE induced more PpIX in visible lesions and altered skin of the UVB-exposed mouse skin, but not in the normal mouse skin. In the microscopic fluorescence images, higher ALAPE-induced PpIX levels were measured in the stratum corneum, but not in the dysplastic layer of the epidermis. In deeper layers of the skin, PpIX levels were the same after ALA and ALAPE application. In conclusion, ALAPE does induce higher PpIX fluorescence levels in vivo in our early skin cancer model, but these higher PpIX levels are not located in the dysplastic layer of the epidermis. [source] Photodynamic Therapy of Cutaneous Lymphoma Using 5-Aminolevulinic Acid Topical ApplicationDERMATOLOGIC SURGERY, Issue 8 2000Arie Orenstein MD Background. Photodynamic therapy (PDT) with topical application of 5-aminolevulinic acid (ALA) is a new and effective modality for treatment of superficial basal and squamous cell carcinomas. Objective. We present the kinetics of ALA-induced protoporphyrin IX (PP) accumulation and the results of ALA PDT treatment on two patients with different stages (stage I and stage III) of mycosis fungoides (MF)-type cutaneous T-cell lymphoma (CTCL). Methods. ALA-Decoderm cream was applied to the lesions for 16 hours. Spectrofluorescence measurements of PP accumulation were carried out before, during, and 1 hour after photoirradiation (580,720 nm) using the VersaLight system. Results. Different patterns of PP fluorescence kinetics were observed in patients with early and advanced stages of the disease. During photoirradiation the intensity of fluorescence decreased depending on the lesion thickness. One hour after the photoirradiation procedure no PP fluorescence was observed in the stage I MF lesion, while in the thick stage III MF lesions, PP fluorescence reappeared; after an additional 10,15 minutes of irradiation PP fluorescence disappeared. Complete response with excellent cosmetic results was observed in the stage I lesion after a single irradiation with a light dose of 170 J/cm2; in five stage III lesions, complete response was achieved after fractionated irradiation with a total light dose of 380 J/cm2 (follow-up at 27 and 24 months, respectively). Conclusion. The results showed a high response of both stage I and stage III MF lesions to ALA PDT. This modality appears to be very effective and can be used successfully for MF treatment. [source] Quantitative Trait Loci Mapping for Chlorophyll Fluorescence and Associated Traits in Wheat (Triticum aestivum)JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2007De-Long Yang Abstract Parameters of chlorophyll fluorescence kinetics (PCFKs) under drought stress condition are generally used to characterize instincts for dehydration tolerance in wheat (Triticum aestivum L.). Therefore, it is important to map quantitative trait loci (QTLs) for PCFKs in wheat genetic improvement for drought tolerance. A doubled haploid (DH) population with 150 lines, derived from a cross between two common wheat varieties, Hanxuan 10 and Lumai 14, was used to analyze the correlation between PCFKs and chlorophyll content (ChlC) and to map QTLs at the grain-filling stage under conditions of both rainfed (drought stress, DS) and well-watered (WW), respectively. QTLs for these traits were detected by QTLMapper version 1.0 based on the composite interval mapping method of the mixed-linear model. The results showed a very significant positive correlation between Fv, Fm, Fv/Fm and Fv/Fo. The correlation coefficients were generally higher under WW than under DS. Also, there was a significant or a highly significant positive correlation between Fv, Fm, Fv/Fm, Fv/Fo and ChlC. The correlation coefficients were higher in the DS group than the WW group. A total of 14 additive QTLs (nine QTLs detected under DS and five QTLs under WW) and 25 pairs of epistatic QTLs (15 pairs detected under DS and 10 pairs under WW) for PCFKs were mapped on chromosomes 6A, 7A, 1B, 3B, 4D and 7D. The contributions of additive QTLs for PCFKs to phenotype variation were from 8.40% to 72.72%. Four additive QTLs (two QTLs detected under DS and WW apiece) controlling ChlC were mapped on chromosomes 1A, 5A and 7A. The contributions of these QTLs for ChlC to phenotype variation were from 7.27% to 11.68%. Several QTL clusters were detected on chromosomes 1B, 7A and 7D, but no shared chromosomal regions for them were identified under different water regimes, indicating that these QTLs performed different expression patterns under rainfed and well-watered conditions. (Handling editor: Yong-Biao Xue) [source] Protoporphyrin IX Fluorescence Kinetics and Localization after Topical Application of ALA Pentyl Ester and ALA on Hairless Mouse Skin with UVB-Induced Early Skin CancerPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2000Johanna T. H. M. van den Akker ABSTRACT In order to improve the efficacy of 5-aminolevulinic acid-based (ALA) photodynamic therapy (PDT), different ALA derivatives are presently being investigated. ALA esters are more lipophilic and therefore may have better skin penetration properties than ALA, possibly resulting in enhanced protoporphyrin IX (PpIX) production. In previous studies it was shown that ALA pentyl ester (ALAPE) does considerably enhance the PpIX production in cells in vitro compared with ALA. We investigated the in vivo PpIX fluorescence kinetics after application of ALA and ALAPE to hairless mice with and without UVB-induced early skin cancer. ALA and ALAPE (20% wt/wt) were applied topically to the mouse skin and after 30 min, the solvent was wiped off and PpIX fluorescence was followed in time with in vivo fluorescence spectroscopy and imaging. At 6 and 12 h after the 30 min application, skin samples of visible lesions and adjacent altered skin (UVB-exposed mouse skin) and normal mouse skin were collected for fluorescence microscopy. From each sample, frozen sections were made and phase contrast images and fluorescence images were recorded. The in vivo fluorescence kinetics showed that ALAPE induced more PpIX in visible lesions and altered skin of the UVB-exposed mouse skin, but not in the normal mouse skin. In the microscopic fluorescence images, higher ALAPE-induced PpIX levels were measured in the stratum corneum, but not in the dysplastic layer of the epidermis. In deeper layers of the skin, PpIX levels were the same after ALA and ALAPE application. In conclusion, ALAPE does induce higher PpIX fluorescence levels in vivo in our early skin cancer model, but these higher PpIX levels are not located in the dysplastic layer of the epidermis. [source] Drought stress effects on photosystem I content and photosystem II thermotolerance analyzed using Chl a fluorescence kinetics in barley varieties differing in their drought tolerancePHYSIOLOGIA PLANTARUM, Issue 2 2009Abdallah Oukarroum Drought stress has multiple effects on the photosynthetic system. Here, we show that a decrease of the relative contribution of the I-P phase, ,VIP = ,VI = (FM,FI)/(FM, Fo), to the fluorescence transient OJIP is observed in 10 drought-stressed barley and 9 chickpea varieties. The extent of the I-P loss in the barley varieties depended on their drought tolerance. The relative loss of the I-P phase seems to be related to a loss of photosystem (PS) I reaction centers as determined by 820-nm transmission measurements. In the second part of this study, the interaction of drought and heat stress in two barley varieties (the drought tolerant variety A¨t Baha and the drought sensitive variety Lannaceur) was studied using a new approach. Heat stress was induced by exposing the plant leaves to temperatures of 25,45°C and the inactivation of the O2 -evolving complex (OEC) was followed measuring chlorophyll a (Chl a) fluorescence using a protocol consisting of two 5-ms pulses spaced 2.3 ms apart. In active reaction centers, the dark interval is long enough to allow the OEC to recover from the first pulse; whereas in heat-inactivated reaction centers it is not. In the latter category of reaction centers, no further fluorescence rise is induced by the second pulse. Lannaceur, under well-watered conditions, was more heat tolerant than Aït Baha. However, this difference was lost following drought stress. Drought stress considerably increased the thermostability of PS II of both varieties. [source] Effects of elevated ozone on photosynthesis and stomatal conductance of two soybean varieties: a case study to assess impacts of one component of predicted global climate changePLANT BIOLOGY, Issue 2009E. Singh Abstract Global climatic change scenarios predict a significant increase in future tropospheric ozone (O3) concentrations. The present investigation was done to assess the effects of elevated O3 (70 and 100 ppb) on electron transport, carbon fixation, stomatal conductance and pigment concentrations in two tropical soybean (Glycine max L.) varieties, PK 472 and Bragg. Plants were exposed to O3 for 4 h·day,1 from 10:00 to 14:00 from germination to maturity. Photosynthesis of both varieties were adversely affected, but the reduction was higher in PK 472 than Bragg. A comparison of chlorophyll a fluorescence kinetics with carbon fixation suggested greater sensitivity of dark reactions than light reactions of photosynthesis to O3 stress. The O3 -induced uncoupling between photosynthesis and stomatal conductance in PK 472 suggests the reduction in photosynthesis may be attributed to a factor other than reduced stomatal conductance. An increase in internal CO2 concentration in both O3 -treated soybean varieties compared suggests that the reduction in photosynthesis was due to damage to the photosynthetic apparatus, leading to accumulation of internal CO2 and stomatal closure. The adverse impact of O3 stress increased at higher O3 concentrations in both soybean varieties leading to large reductions in photosynthesis. This study suggests that O3 -induced reductions in photosynthesis in tropical and temperate varieties are similar. [source] | ||||||||||