The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Tsunenori Arai - One of the best experts on this subject based on the ideXlab platform.
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A three-compartment non-linear model of myocardial cell conduction block during Photosensitization
Medical & Biological Engineering & Computing, 2021Co-Authors: Emiyu Ogawa, Eitaro Aiyoshi, Tsunenori AraiAbstract:This study constructed a new non-linear model of myocardial electrical conduction block during Photosensitization reaction to identify the vulnerable cell population and generate an index for recurrent risk following catheter ablation for tachyarrhythmia. A three-compartment model of conductive, vulnerable, and blocked cells was proposed. To determine the non-linearity of the rate parameter for the change from vulnerable cells to conductive cells, we compared a previously reported non-linear model and our newly proposed model with non-linear rate parameters in the modeling of myocardial cell electrical conduction block during Photosensitization reaction. The rate parameters were optimized via a bi-nested structure using measured synchronicity data during the Photosensitization reaction of myocardial cell wires. The newly proposed model had a better fit to the measured data than the conventional model. The sum of the error until the time where the measured value was higher than 0.6, was 0.22 in the conventional model and 0.07 in our new model. The non-linear rate parameter from the vulnerable cell to the conductive cell compartment may be the preferred structure of the electrical conduction block model induced by Photosensitization reaction. This simulation model provides an index to evaluate recurrent risk after tachyarrhythmia catheter ablation by Photosensitization reaction. Graphical abstract A three-compartment non-linear model of myocardial cell conduction block during Photosensitization
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Photosensitization reaction along depth of a culture well with high concentration of talaporfin sodium for extra cellular photodynamic therapy study
Proceedings of SPIE, 2014Co-Authors: Masahiro Yajima, Emiyu Ogawa, Mei Takahashi, Hiroshige Kawakami, Tsunenori AraiAbstract:We studied Photosensitization reaction progress in a cell culture well by oxygen partial pressure distribution measurement along the well depth direction with a high concentration of talaporfin sodium solution. The talaporfin sodium solution of 20 μg/ml in concentration with 2.8 mm thickness in the well was irradiated from the well bottom by 663 nm excitation laser with 0.29 W/cm2. A small Clark-type oxygen electrode was used to measure oxygen partial pressure during the Photosensitization reaction with approximately 200 μm resolution. Corrections against solution temperature change and direct light irradiation were applied to the electrode output. The oxygen partial pressures at various depths were decreased uniformly from the atmospheric oxygen partial pressure with the Photosensitization reaction progress up to the irradiation of 1.0 J/cm2 in radiant exposure. In the case of Photosensitization reaction over 1.0 J/cm2 in radiant exposure, the oxygen partial pressure distribution along the well depth was non-uniform. In the case of Photosensitization reaction with 40 J/cm2 in radiant exposure in the solution without cells, there was pressure gradient of 2.8×104 mmHg/m from 0.5 to 1.0 mm in depth from the solution surface. In this case, there was no pressure gradient near the bottom of the well. In contrast, with myocardial cells at the bottom, oxygen partial pressure gradient of 7.5×103 mmHg/m from 1.5 to 2.0 mm in the depth was appeared after irradiation with 40 J/cm2 in radiant exposure. Consequently, we found that oxygen partial pressure distribution along the depth in the well with high concentration of talaporfin sodium solution was dynamically changed with time of the Photosensitization reaction using the laser irradiation from the bottom. We think this dynamic pressure change in the well might be useful to understand the Photosensitization reaction progress in the well experiment system in vitro corresponding to the extracellular PDT.
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Immediate response of Ca2+ concentration in myocardial cells against oxidation stress by extracellular Photosensitization reaction using Talaporfin sodium for the arrhythmia treatment application
Optical Interactions with Tissue and Cells XXV; and Terahertz for Biomedical Applications, 2014Co-Authors: Emiyu Ogawa, Mei Takahashi, Arisa Ito, Tsunenori AraiAbstract:We studied the immediate response of myocardial cells by continuous observation using confocal microscope against oxidation stress by extracellular Photosensitization reaction using Talaporfin sodium for tachyarrhythmia treatment application. Immediate response in order from several seconds to several minutes is required for the arrhythmia treatment since operators should judge the therapeutic effect during the tachyarrhythmia ablation procedure. To understand the immediate response of myocardial cells, we measured the intracellular Ca 2+ concentration using fluo-4 AM during and after the extracellular Photosensitization reaction. Talaporfin sodium concentration was varied 10-30 μg/ml. A red diode laser of 663 nm in wavelength was irradiated under the microscope with the radiant exposure of 40 J/cm 2 and irradiance of 0.29 W/cm 2 . We observed the fluorescence image of fluo-4 AM each 400 ms during until 10 min after the Photosensitization reaction. The myocardial cell beatings were stopped about 2 s after the beginning of the laser irradiation. The blebs were formed with the Ca 2+ inflow. The intracellular Ca 2+ was re-decreased after the bleb formation and then the cell necrosis was induced. The cell lethality 10 min after the laser irradiation was less than bleb formation ratio. The time response of the cell necrosis was shortened with the photosensitizer concentration increasing and the minimum average value was 209 s in the case of the 30 μg/ml in photosensitizer concentration and 40 J/cm 2 in the radiant exposure. We think this extracellular Photosensitization reaction may be applicable to tachyarrhythmia treatment in terms of its immediate response.
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Study of Photosensitization reaction progress in a 96 well plate with photosensitizer rich condition using Talaporfin sodium
Proceedings of SPIE, 2013Co-Authors: Emiyu Ogawa, Mei Takahashi, Tsunenori AraiAbstract:To quantitatively investigate Photosensitization reaction in vitro against myocardial cells with photosensitizer rich condition in solution using Talaporfin sodium in the well of a 96 well plate, we studied Photosensitization reaction progress in this well. We have proposed non-thermal conduction block of myocardium tissue using the Photosensitization reaction with laser irradiation shortly after Talaporfin sodium injection. In above situation, the photosensitizer is located outside the myocardial cells in high concentration. To understand interaction of the Photosensitization reaction in which the photosensitizer distributes outside cells, the Photosensitization reaction progress in the well was studied. Talaporfin sodium (799.69 MW) solution and a 663 nm diode laser were used. The photosensitizer solution concentrations of 12.5-37.5 μM were employed. The photosensitizer fluorescence with 0.29 W/cm 2 in irradiance, which was optimized in previous cell death study, was measured during the laser irradiation until 40 J/cm 2 . The photosensitizer solution absorbance and dissolved oxygen pressure after the laser irradiation were also measured. We found that the Photosensitization reaction progress had 2 distinctive phases of different reaction rate: rapid Photosensitization reaction consuming dissolved oxygen and gentle Photosensitization reaction with oxygen diffusion from the solution-air boundary. The dissolved oxygen pressure and photosensitizer solution absorbance were 30% and 80% of the initial values after the laser irradiation, respectively. Therefore, oxygen was rate-controlling factor of the Photosensitization reaction in the well with the photosensitizer rich condition. In the oxygen diffusion phase, the oxygen pressure was maintained around 40 mmHg until the laser irradiation of 40 J/cm 2 and it is similar to that of myocardium tissue in vivo . We think that our 96 well plate in vitro system may simulate PDT in myocardial tissue with Photosensitization reaction parameters mentioned above.
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myocardial electrical conduction block induced by Photosensitization reaction in exposed porcine hearts in vivo
Lasers in Surgery and Medicine, 2011Co-Authors: Arisa Ito, Shunichiro Miyoshi, Takehiro Kimura, Seiji Takatsuki, Kotaro Fukumoto, Keiichi Fukuda, Tsunenori AraiAbstract:Background and Objective This study proposes Photosensitization reaction for non-thermal cardiac ablation in arrhythmia therapy. Acute and chronic phase experiments were conducted in exposed porcine hearts to demonstrate the Photosensitization reaction-induced myocardial electrical conduction block in vivo. Study Design/Materials and Methods The porcine left atrial appendage was exposed under an open-chest procedure. Then, a water-soluble chlorin photosensitizer, NPe6, was injected into the pigs intravenously at 5 or 10 mg/kg. About 15 or 30 minutes after the injection, a 663-nm continuous-wave diode laser was irradiated on the surface of the atrial appendage through a silica optical fiber. The laser energy was delivered to the tissue point by point at an energy density of 50–208 J/cm2. Results Acute and chronic tissue damages as a result of the Photosensitization reaction were determined by electrophysiology and histology, respectively. The change in the myocardial conduction time between two electrodes was measured immediately after the completion of the 35-mm irradiation line between the electrodes. The conduction delay of 35.5 milliseconds might be due to the change in the conduction pathway induced by transmural acute conduction block with the Photosensitization reaction. The tissue temperature increase in the irradiated area was approximately 12.8°C. Azan-staining revealed about 1-mm transmural fibrosis of the atrial appendage at 2 weeks after the irradiation (50 J/cm2). Conclusions The results suggest that the Photosensitization reaction might induce acute and chronic myocardial electrical conduction block. Cardiac ablation with the Photosensitization reaction might be a non-temperature-mediated methodology for arrhythmia therapy. Lasers Surg. Med. 43:984–990, 2011. © 2011 Wiley Periodicals, Inc.
Zivile Luksiene - One of the best experts on this subject based on the ideXlab platform.
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towards better microbial safety of fresh produce chlorophyllin based Photosensitization for microbial control of foodborne pathogens on cherry tomatoes
Journal of Photochemistry and Photobiology B-biology, 2018Co-Authors: Egle Paskeviciute, Bernadeta Zudyte, Zivile LuksieneAbstract:Abstract The aim of this study is to evaluate the antimicrobial efficiency of Chlorophyllin-based Photosensitization for microbial control of cherry tomatoes. Chlorophyllin-based Photosensitization (1.5 × 10−4 M, 3 J/cm2) significantly (2.4 log) reduced the population of naturally distributed surface attached various mesophilic bacteria (microbiota) on tomatoes. Moreover, the population of thermoresistant strains of food pathogens Bacillus cereus and Listeria monocytogenes inoculated on tomatoes was reduced by 1.5 log and 1.6 log respectively after this treatment. Conventional washing with water reduced the population of Listeria on tomato by 0.6 log and Bacillus by 0.8 log. In comparison, hypochlorite treatment reduced Listeria on tomatoes by 1.4 log and Bacillus by 1.6 log. The regrowth of mesophilic bacteria and thermoresistant Listeria on the surface of tomatoes after Photosensitization was delayed for 28 days and 14 days respectively. Moreover, Photosensitization did not induce harmful effects on main parameter of nutritional quality of tomatoes, i.e. antioxidant activity of tomatoes remained unchanged (27.5 mM Fe2+/kg). Eventually, this treatment did not induce visible thermal effects in fruit matrix and prolonged the shelf-life of tomatoes by 4 days. In our opinion, chlorophyllin-based Photosensitization has a huge potential as alternative to not-chemical food preservation technology, saving water and energy. In addition, fast development of light emitting diodes (LED's) and light sources based on LED technologies make this treatment low cost, environmentally friendly and easy to maintain.
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Attempts to use Photosensitization for preservation of strawberry cultivar ‘Darselect’: effects on shelf-life, nutritional and organoleptic properties” excluding Photosensitization for preservation of strawberry
Journal of Plant Diseases and Protection, 2016Co-Authors: Neringa Rasiukevičiūtė, Alma Valiuškaitė, Jonas Viskelis, Nobertas Uselis, Zivile LuksieneAbstract:The methods recently applied for decontamination of fruits and vegetables are not always efficient, human and ecologically friendly. In this context, Photosensitization might serve as really promising tool. Obtained data indicated that Botrytis spp. was susceptible to Photosensitization and its growth inhibited 14 % and reduced 18 % rotten strawberries. The following evaluation of shelf life of treated strawberries indicated some extension in comparison with control ones. The examination of nutritional quality of treated strawberries revealed that total antioxidant activity, amount of phenols and anthocyanins did not change in comparison with control. No effects on berry color were observed, just a slight reduction (10 %) of fruit firmness found in treated ones. In conclusion, Photosensitization has potential as bio-fungicide, since inactivates Botrytis spp. on the surface of strawberry without impact on their nutritional properties or visual quality.
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novel approach to the microbial decontamination of strawberries chlorophyllin based Photosensitization
Journal of Applied Microbiology, 2011Co-Authors: Zivile Luksiene, Egle PaskeviciuteAbstract:Aims: This study is focused on the possibility to control microbial contamination of strawberries by chlorophyllin (Na-Chl)-based Photosensitization. Moreover, Photosensitization-induced effects on key quality attributes of treated strawberries was evaluated. Methods and Results: Strawberries were inoculated with Listeria monocytogenes ATCL3C 7644, soaked in 1 mmol l−1 Na-Chl for 5 min and illuminated for 30 min with visible light (λ = 400 nm, energy density 12 mW cm−2). Results indicated that the decontamination of strawberries using Photosensitization was 98% compared to control sample. Naturally occurring yeasts/microfungi and mesophiles were inhibited by 86 and 97%, respectively. The shelf life of treated strawberries was extended by 2 days. The total antioxidant activity of treated strawberries increased by 19%. No impact on the amount of phenols, anthocyanins or surface colour was detected. Conclusions: Photosensitization may be an effective, nonthermal and environmentally friendly microbial decontamination technique which expands the shelf life of strawberries without any negative impact on antioxidant activity, and phenols, anthocyanins or colour formation. Significance and Impact of the Study: Experimental data support the idea that Na-Chl-based Photosensitization can be a useful tool for the future development of nonthermal food preservation technology.
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Photosensitization based inactivation of food pathogen listeria monocytogenes in vitro and on the surface of packaging material
Journal of Photochemistry and Photobiology B-biology, 2010Co-Authors: Irina Buchovec, Egle Paskeviciute, Zivile LuksieneAbstract:The study was focused on the susceptibility of Listeria monocytogenes ATCL3C 7644 cells and biofilms to non-thermal antimicrobial treatment - Photosensitization in vitro and after adhesion to the surface of packaging material. L. monocytogenes was incubated with 5-aminolevulinic acid (ALA) (7.5 mM) for 0-2h and illuminated with visible light. The LED-based light source used for the illumination emitted light lambda=400 nm with energy density 20 mW/cm(2). The illumination time varied 0-20 min, and a total light dose reached 0-24 J/cm(2). The obtained data indicate that L. monocytogenes produces endogenous porphyrins after incubation with 7.5mM ALA. Subsequent illumination of cells remarkably inactivates (4 log) them in vitro. Photosensitization diminished population of Listeria cells adhered onto the packaging material by 3.7 log and inactivated bacterial biofilms by 3.1 log. It was shown that antimicrobial efficiency of Photosensitization depended on the illumination time, incubation with ALA time as well as on the used ALA concentration. In conclusion, cells and biofilms of L. monocytogenes ATCL3C 7644 can be effectively inactivated by ALA-based Photosensitization in the solution as well as adhered onto the surface of packaging material. Obtained data support the idea, that Photosensitization as non-thermal and effective antimicrobial treatment has potential to develop into environmentally safe, surface decontamination technique.
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Inactivation of food pathogen Bacillus cereus by Photosensitization in vitro and on the surface of packaging material.
Journal of applied microbiology, 2009Co-Authors: Zivile Luksiene, Irina Buchovec, Egle PaskeviciuteAbstract:Aims: The study was focused on the possibility to inactivate food pathogen Bacillus cereus by 5-aminolevulinic acid (ALA) – based Photosensitization in vitro and after adhesion on the surface of packaging material. Methods and Results: Bacillus cereus was incubated with ALA (3–7·5 mmol l−1) for 5–60 min in different environment (PBS, packaging material and wheat grains) and afterwards illuminated with visible light. The light source used for illumination emitted light at λ = 400 nm with energy density at the position of the cells, 20 mW cm−2. The illumination time varied from 0 to 20 min, and subsequently a total energy dose was between 0 and 24 J cm−2. The obtained results indicate that B. cereus after the incubation with 3–7·5 mmol l−1 ALA produces suitable amounts of endogenous photosensitizers. Following illumination, micro-organism inactivated even by 6·3 log. The inactivation of B. cereus after adhesion on the surface of food packaging by Photosensitization reached 4 log. It is important to note that spores of B. cereus were susceptible to this treatment as well; 3·7-log inactivation in vitro and 2·7-log inactivation on the surface of packaging material were achieved at certain experimental conditions. Conclusions: Vegetative cells and spores of Gram-positive food pathogen B. cereus were effectively inactivated by ALA-based Photosensitization in vitro. Moreover, the significant inactivation of B. cereus adhered on the surface of packaging material was observed. It was shown that Photosensitization-based inactivation of B. cereus depended on the total light dose (illumination time) as well as on the amount of endogenous porphyrins (initial ALA concentration, time of incubation with ALA). Significance and Impact of the Study: Our previous data, as well as the one obtained in this study, support the idea that Photosensitization with its high selectivity, antimicrobial efficiency and nonthermal nature could serve in the future for the development of completely safe, nonthermal surface decontamination and food preservation techniques.
Arisa Ito - One of the best experts on this subject based on the ideXlab platform.
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Immediate response of Ca2+ concentration in myocardial cells against oxidation stress by extracellular Photosensitization reaction using Talaporfin sodium for the arrhythmia treatment application
Optical Interactions with Tissue and Cells XXV; and Terahertz for Biomedical Applications, 2014Co-Authors: Emiyu Ogawa, Mei Takahashi, Arisa Ito, Tsunenori AraiAbstract:We studied the immediate response of myocardial cells by continuous observation using confocal microscope against oxidation stress by extracellular Photosensitization reaction using Talaporfin sodium for tachyarrhythmia treatment application. Immediate response in order from several seconds to several minutes is required for the arrhythmia treatment since operators should judge the therapeutic effect during the tachyarrhythmia ablation procedure. To understand the immediate response of myocardial cells, we measured the intracellular Ca 2+ concentration using fluo-4 AM during and after the extracellular Photosensitization reaction. Talaporfin sodium concentration was varied 10-30 μg/ml. A red diode laser of 663 nm in wavelength was irradiated under the microscope with the radiant exposure of 40 J/cm 2 and irradiance of 0.29 W/cm 2 . We observed the fluorescence image of fluo-4 AM each 400 ms during until 10 min after the Photosensitization reaction. The myocardial cell beatings were stopped about 2 s after the beginning of the laser irradiation. The blebs were formed with the Ca 2+ inflow. The intracellular Ca 2+ was re-decreased after the bleb formation and then the cell necrosis was induced. The cell lethality 10 min after the laser irradiation was less than bleb formation ratio. The time response of the cell necrosis was shortened with the photosensitizer concentration increasing and the minimum average value was 209 s in the case of the 30 μg/ml in photosensitizer concentration and 40 J/cm 2 in the radiant exposure. We think this extracellular Photosensitization reaction may be applicable to tachyarrhythmia treatment in terms of its immediate response.
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myocardial electrical conduction block induced by Photosensitization reaction in exposed porcine hearts in vivo
Lasers in Surgery and Medicine, 2011Co-Authors: Arisa Ito, Shunichiro Miyoshi, Takehiro Kimura, Seiji Takatsuki, Kotaro Fukumoto, Keiichi Fukuda, Tsunenori AraiAbstract:Background and Objective This study proposes Photosensitization reaction for non-thermal cardiac ablation in arrhythmia therapy. Acute and chronic phase experiments were conducted in exposed porcine hearts to demonstrate the Photosensitization reaction-induced myocardial electrical conduction block in vivo. Study Design/Materials and Methods The porcine left atrial appendage was exposed under an open-chest procedure. Then, a water-soluble chlorin photosensitizer, NPe6, was injected into the pigs intravenously at 5 or 10 mg/kg. About 15 or 30 minutes after the injection, a 663-nm continuous-wave diode laser was irradiated on the surface of the atrial appendage through a silica optical fiber. The laser energy was delivered to the tissue point by point at an energy density of 50–208 J/cm2. Results Acute and chronic tissue damages as a result of the Photosensitization reaction were determined by electrophysiology and histology, respectively. The change in the myocardial conduction time between two electrodes was measured immediately after the completion of the 35-mm irradiation line between the electrodes. The conduction delay of 35.5 milliseconds might be due to the change in the conduction pathway induced by transmural acute conduction block with the Photosensitization reaction. The tissue temperature increase in the irradiated area was approximately 12.8°C. Azan-staining revealed about 1-mm transmural fibrosis of the atrial appendage at 2 weeks after the irradiation (50 J/cm2). Conclusions The results suggest that the Photosensitization reaction might induce acute and chronic myocardial electrical conduction block. Cardiac ablation with the Photosensitization reaction might be a non-temperature-mediated methodology for arrhythmia therapy. Lasers Surg. Med. 43:984–990, 2011. © 2011 Wiley Periodicals, Inc.
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Photosensitization Reaction-Induced Acute Electrophysiological Cell Response of Rat Myocardial Cells in Short Loading Periods of Talaporfin Sodium or Porfimer Sodium
Photochemistry and photobiology, 2010Co-Authors: Arisa Ito, Shunichiro Miyoshi, Satoshi Ogawa, Takehiro Kimura, Tsunenori AraiAbstract:Electrophysiological responses of rat myocardial cells to exogenous Photosensitization reactions for a short period of incubation with two photosensitizers, talaporfin sodium or porfimer sodium, were measured in a subsecond time scale. The loading period of the photosensitizer when the photosensitizer might not be taken up by the cells was selected as 15min, which was determined by the fluorescence microscopic observation. We measured the intracellular Ca(2+) concentration ([Ca(2+) ](in) ) by using a fluorescent Ca(2+) indicator, Fluo-4 AM, under a high-speed confocal laser microscope to evaluate the acute electrophysiological cell response to the Photosensitization reaction. The measured temporal change in Fluo-4 fluorescence intensity indicated that the response to the Photosensitization reaction might be divided into two phases in both photosensitizers. The first phase is acute response: disappearance of Ca(2+) oscillation when irradiation starts, which might be caused by ion channel dysfunction. The second phase is slow response: [Ca(2+) ](in) elevation indicating influx of Ca(2+) due to the concentration gradient. The continuous Ca(2+) influx followed by changes in cell morphology suggested micropore formation on the surface of the cell membrane, resulting in necrotic cell death.
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Dependence of light fluence on treated depth with Photosensitization reaction shortly after photosensitizer injection in rabbit myocardial tissue in vivo
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XIX, 2010Co-Authors: T. Suenari, Shunichiro Miyoshi, Arisa Ito, Hiroki Matsuo, Tsunenori AraiAbstract:We investigated experimentally dependence of light fluence on treated depth with Photosensitization reaction shortly after photosensitizer injection in rabbit myocardial tissue in vivo. In this particular Photosensitization reaction scheme, the photosensitizer accumulation characteristics for target region are not available. Meanwhile, the photosensitizer dose and hospitalization period under restricted light circumstance might be reduced. Since both photosensitizer and oxygen supply are governed by blood flow, this Photosensitization reaction is influenced significantly by blood flow variation in particular blood vessel occlusion. We employed the myocardial tissue to keep tissue blood flow during the Photosensitization reaction because vessel blood flow speed in myocardial tissue is fast to resist vascular occlusion. Surgically exposed rabbits myocardial tissues were irradiated with the light fluence ranging 25-100 J/cm2 by a 663 nm diode laser 30 min after the injection of 2 mg/kg water soluble chlorin photosensitizer, Talaporfin sodium. Two weeks after the irradiation, the rabbits were sacrificed and the histological specimens of the irradiated area were made to measure scar layer thickness. The scar layer tissue thickness of 0.2-3.0 mm was observed microscopically by the light fluence ranging 25-100 J/cm2. The scarring threshold in the deposit light fluence was estimated to 15-25 J/cm3 based on the above mentioned relation assuming constant and uniform myocardial effective attenuation coefficient of 0.72 mm-1. The estimated scarring threshold in the deposit light fluence was lower than the threshold of conventional PDT. Large variation of the estimated threshold value might be attributed to unconsidered PDT parameter such as flow rate inhomogeneity in the myocardial tissue. These results suggested that the Photosensitization reaction investigated in this study would be available to apply arrhythmia therapy such as atrial fibrillation.
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The Myocardial Electrical Blockade Induced by Photosensitization Reaction
IEEE Transactions on Biomedical Engineering, 2010Co-Authors: Arisa Ito, Shuntaro Hosokawa, Shunichiro Miyoshi, Kyoko Soejima, Satoshi Ogawa, Tsunenori AraiAbstract:The authors studied the application of Photosensitization-reaction-induced cytotoxicity to establish electrical blockade of myocardial tissue. This Photosensitization-reaction-induced cytotoxicity, i.e., photodynamic therapy (PDT) was performed with chlorine photosensitizer, talaporfin sodium, and a red (670 nm) diode laser. The cytotoxicity on rat cardiac myocytes and the electrical blockade by PDT using rat myocardial tissue were confirmed. The mechanism of PDT-induced electrical blockade was investigated. The Photosensitization-reaction-induced cytotoxicity in normal rat cardiac myocytes was obtained in cell lethality measurement. The ex vivo experiment with rat-isolated myocardial tissue demonstrated the immediate electrical blockade by PDT. Moreover, the possibility of permanent electrical blockade by PDT using rat atrioventricular blockade model was confirmed. To study the mechanism of the acute electrical blockade obtained in the ex vivo study, intracellular Ca2+ concentration changes in rat cardiac myocytes were measured by the intensity of the fluorescent Ca2+ indicator Fluo-4 AM. A rapid increase in fluorescence intensity during the Photosensitization reaction and a change in cell morphology after the Photosensitization reaction were observed. These results indicate that cell membrane damage, Ca2+ influx, and eventually cell death are caused by the Photosensitization reaction. The necrosis-like cell death induced by the Photosensitization reaction can explain a permanent electrical blockade of the myocardial tissue in vivo by PDT.
Egle Paskeviciute - One of the best experts on this subject based on the ideXlab platform.
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towards better microbial safety of fresh produce chlorophyllin based Photosensitization for microbial control of foodborne pathogens on cherry tomatoes
Journal of Photochemistry and Photobiology B-biology, 2018Co-Authors: Egle Paskeviciute, Bernadeta Zudyte, Zivile LuksieneAbstract:Abstract The aim of this study is to evaluate the antimicrobial efficiency of Chlorophyllin-based Photosensitization for microbial control of cherry tomatoes. Chlorophyllin-based Photosensitization (1.5 × 10−4 M, 3 J/cm2) significantly (2.4 log) reduced the population of naturally distributed surface attached various mesophilic bacteria (microbiota) on tomatoes. Moreover, the population of thermoresistant strains of food pathogens Bacillus cereus and Listeria monocytogenes inoculated on tomatoes was reduced by 1.5 log and 1.6 log respectively after this treatment. Conventional washing with water reduced the population of Listeria on tomato by 0.6 log and Bacillus by 0.8 log. In comparison, hypochlorite treatment reduced Listeria on tomatoes by 1.4 log and Bacillus by 1.6 log. The regrowth of mesophilic bacteria and thermoresistant Listeria on the surface of tomatoes after Photosensitization was delayed for 28 days and 14 days respectively. Moreover, Photosensitization did not induce harmful effects on main parameter of nutritional quality of tomatoes, i.e. antioxidant activity of tomatoes remained unchanged (27.5 mM Fe2+/kg). Eventually, this treatment did not induce visible thermal effects in fruit matrix and prolonged the shelf-life of tomatoes by 4 days. In our opinion, chlorophyllin-based Photosensitization has a huge potential as alternative to not-chemical food preservation technology, saving water and energy. In addition, fast development of light emitting diodes (LED's) and light sources based on LED technologies make this treatment low cost, environmentally friendly and easy to maintain.
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novel approach to the microbial decontamination of strawberries chlorophyllin based Photosensitization
Journal of Applied Microbiology, 2011Co-Authors: Zivile Luksiene, Egle PaskeviciuteAbstract:Aims: This study is focused on the possibility to control microbial contamination of strawberries by chlorophyllin (Na-Chl)-based Photosensitization. Moreover, Photosensitization-induced effects on key quality attributes of treated strawberries was evaluated. Methods and Results: Strawberries were inoculated with Listeria monocytogenes ATCL3C 7644, soaked in 1 mmol l−1 Na-Chl for 5 min and illuminated for 30 min with visible light (λ = 400 nm, energy density 12 mW cm−2). Results indicated that the decontamination of strawberries using Photosensitization was 98% compared to control sample. Naturally occurring yeasts/microfungi and mesophiles were inhibited by 86 and 97%, respectively. The shelf life of treated strawberries was extended by 2 days. The total antioxidant activity of treated strawberries increased by 19%. No impact on the amount of phenols, anthocyanins or surface colour was detected. Conclusions: Photosensitization may be an effective, nonthermal and environmentally friendly microbial decontamination technique which expands the shelf life of strawberries without any negative impact on antioxidant activity, and phenols, anthocyanins or colour formation. Significance and Impact of the Study: Experimental data support the idea that Na-Chl-based Photosensitization can be a useful tool for the future development of nonthermal food preservation technology.
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Photosensitization based inactivation of food pathogen listeria monocytogenes in vitro and on the surface of packaging material
Journal of Photochemistry and Photobiology B-biology, 2010Co-Authors: Irina Buchovec, Egle Paskeviciute, Zivile LuksieneAbstract:The study was focused on the susceptibility of Listeria monocytogenes ATCL3C 7644 cells and biofilms to non-thermal antimicrobial treatment - Photosensitization in vitro and after adhesion to the surface of packaging material. L. monocytogenes was incubated with 5-aminolevulinic acid (ALA) (7.5 mM) for 0-2h and illuminated with visible light. The LED-based light source used for the illumination emitted light lambda=400 nm with energy density 20 mW/cm(2). The illumination time varied 0-20 min, and a total light dose reached 0-24 J/cm(2). The obtained data indicate that L. monocytogenes produces endogenous porphyrins after incubation with 7.5mM ALA. Subsequent illumination of cells remarkably inactivates (4 log) them in vitro. Photosensitization diminished population of Listeria cells adhered onto the packaging material by 3.7 log and inactivated bacterial biofilms by 3.1 log. It was shown that antimicrobial efficiency of Photosensitization depended on the illumination time, incubation with ALA time as well as on the used ALA concentration. In conclusion, cells and biofilms of L. monocytogenes ATCL3C 7644 can be effectively inactivated by ALA-based Photosensitization in the solution as well as adhered onto the surface of packaging material. Obtained data support the idea, that Photosensitization as non-thermal and effective antimicrobial treatment has potential to develop into environmentally safe, surface decontamination technique.
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Inactivation of food pathogen Bacillus cereus by Photosensitization in vitro and on the surface of packaging material.
Journal of applied microbiology, 2009Co-Authors: Zivile Luksiene, Irina Buchovec, Egle PaskeviciuteAbstract:Aims: The study was focused on the possibility to inactivate food pathogen Bacillus cereus by 5-aminolevulinic acid (ALA) – based Photosensitization in vitro and after adhesion on the surface of packaging material. Methods and Results: Bacillus cereus was incubated with ALA (3–7·5 mmol l−1) for 5–60 min in different environment (PBS, packaging material and wheat grains) and afterwards illuminated with visible light. The light source used for illumination emitted light at λ = 400 nm with energy density at the position of the cells, 20 mW cm−2. The illumination time varied from 0 to 20 min, and subsequently a total energy dose was between 0 and 24 J cm−2. The obtained results indicate that B. cereus after the incubation with 3–7·5 mmol l−1 ALA produces suitable amounts of endogenous photosensitizers. Following illumination, micro-organism inactivated even by 6·3 log. The inactivation of B. cereus after adhesion on the surface of food packaging by Photosensitization reached 4 log. It is important to note that spores of B. cereus were susceptible to this treatment as well; 3·7-log inactivation in vitro and 2·7-log inactivation on the surface of packaging material were achieved at certain experimental conditions. Conclusions: Vegetative cells and spores of Gram-positive food pathogen B. cereus were effectively inactivated by ALA-based Photosensitization in vitro. Moreover, the significant inactivation of B. cereus adhered on the surface of packaging material was observed. It was shown that Photosensitization-based inactivation of B. cereus depended on the total light dose (illumination time) as well as on the amount of endogenous porphyrins (initial ALA concentration, time of incubation with ALA). Significance and Impact of the Study: Our previous data, as well as the one obtained in this study, support the idea that Photosensitization with its high selectivity, antimicrobial efficiency and nonthermal nature could serve in the future for the development of completely safe, nonthermal surface decontamination and food preservation techniques.
Irene E. Kochevar - One of the best experts on this subject based on the ideXlab platform.
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Influence of Rose Bengal Dimerization on Photosensitization.
Photochemistry and photobiology, 2021Co-Authors: Bryan Mendes, Stefan Kassumeh, Alan Aguirre‐soto, Qing Pei, Belinda Heyne, Irene E. KochevarAbstract:Protein crosslinking photosensitized by rose Bengal (RB2- ) has multiple medical applications and understanding the Photosensitization mechanism can improve treatment effectiveness. To this end, we investigated the photochemical efficiencies of monomeric RB2- (RBM2- ) and dimeric RB2- (RBD2- ) and the optimal pH for anaerobic RB2- Photosensitization in cornea. Absorption spectra and dynamic light scattering (DLS) measurements were used to estimate the fractions of RBM2- and RBD2- . RB2- self-photosensitized bleaching was used to evaluate the photoactivity of RBM2- and RBD2- . The pH dependence of anaerobic RB2- Photosensitization was evaluated in ex vivo rabbit corneas. The 549 nm/515 nm absorption ratio indicated that concentrations > 0.10 mM RB contained RBD2- . Results from DLS gave estimated mean diameters for RBM2- and RBD2- of 0.70±0.02 nm and 1.75±0.13 nm, respectively, and indicated that 1 mM RB2- contained equal fractions of RBM2- and RBD2- . Quantum yields for RB2- bleaching were not influenced by RBD2- in RB2- solutions although accounting for RB2- concentration effects on the reaction kinetics demonstrated that RBD2- is not a photosensitizer. Optimal anaerobic Photosensitization occurred at pH 8.5 for solutions containing 200 mM Arg. These results suggest potential approaches to optimizing RBM2- -photosensitized protein crosslinking in tissues.