Photodynamic therapy

Grossweiner, Leonard I.

doi:10.2351/1.4745372

Cited by 9 publications

(6 citation statements)

References 22 publications

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“…Tumor cells have higher numbers of LDL receptors on their surfaces, potentially associated with their higher requirement for cholesterol than normal cells to build membranes 47 . Several studies have achieved preferential photosensitizer release to tumor cells by associating the photosensitizers with low density lipoproteins and by increasing hydrophobicity by augmentation with liposome delivery systems 48–50 . However, other reports have shown that a degree of selectivity does not correlate with their hydrophobicity or their affinity for LDL, indicating that LDL receptor‐mediated pathway may not be the main route of internalization 15,51 …”

Section: Photosensitizer Localization In Neoplastic Tissuementioning

confidence: 99%

Photodynamic therapy: basic principles and potential uses for the veterinary ophthalmologist

Giuliano¹,

Ota²,

Tucker

2007

Veterinary Ophthalmology

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Photodynamic therapy (PDT) involves the use of photochemical reactions mediated through the interaction of photosensitizing agents, light and oxygen. PDT, while now commonly used in physician ophthalmology and oncology, is uncommonly used for the veterinary ophthalmic patient. It is an emerging new therapy in veterinary ophthalmology for the treatment of periocular tumors. This article reviews the basic principles of PDT to provide the veterinary ophthalmologic community with a succinct reference for this emerging treatment modality in our field.

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Section: Photosensitizer Localization In Neoplastic Tissuementioning

confidence: 99%

Photodynamic therapy: basic principles and potential uses for the veterinary ophthalmologist

Giuliano¹,

Ota²,

Tucker

2007

Veterinary Ophthalmology

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“…Apoptotic cells were recognized by their smaller size and nuclei fragmented into condensed chromatin bodies. The results were validated against a standard induction of apoptosis by heat treatment at 43°C for 40 min followed by incubation for 4 h at 37°C according to the method described by Li et al (1994). One hundred cells in four preparations (total of 400 cells) were counted by two individuals, independently.…”

Section: Determination Of Percentage Of Apoptotic Cellsmentioning

confidence: 99%

“…The leading, most widely investigated, photosensitizers in PDT are the haematoporphyrins (HPDPhotofrin II) (Kessel, 1984), which were recently approved for clinical use. However, their use may be limited because of prolonged cutaneous phototoxicity, aggregation tendency, slow metabolism in vivo (Gomer, 1991;Grossweiner, 1994;Jones et al, 1996), as well as limited efficacies in affecting penetrating solid tumours (Orenstein et al, 1996). To overcome these limitations, a number of photosensitizing molecules are being investigated as potential agents for use in PDT.…”

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confidence: 99%

A photodynamic pathway to apoptosis and necrosis induced by dimethyl tetrahydroxyhelianthrone and hypericin in leukaemic cells: possible relevance to photodynamic therapy

et al. 1999

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SummaryThe mechanism of cell death induction by dimethyl tetrahydroxyhelianthrone (DTHe), a new second-generation photodynamic sensitizer, is analysed in human leukaemic cell lines in comparison with the structurally related hypericin. DTHe has a broad range of light spectrum absorption that enables effective utilization of polychromatic light. Photosensitization of HL-60 cells with low doses of DTHe (0.65 µM DTHe and 7.2 J cm -2 light energy) induced rapid apoptosis of ≥90% of the cells. At doses ≥2 µM, dying cells assumed morphological necrosis with perinucleolar condensation of chromatin in HL-60 and K-562 cell lines. Although nuclear fragmentation that is characteristic to apoptosis was prevented, DNA digestion to oligonucleosomes proceeded unhindered. Such incomplete apoptosis was more prevalent with the related analogue hypericin throughout most doses of photosensitization. Despite hypericin being a stronger photosensitizer, DTHe exhibited advantageous phototoxic properties to tumour cells, initiating apoptosis at concentrations about threefold lower than hypericin. Photosensitization of the cells induced dissociation of the nuclear envelope, releasing lamins into the cytosol. DTHe also differed from hypericin in effects exerted on the nuclear lamina, causing release of an 86-kDa lamin protein into the cytosol that was unique to DTHe. Within the nucleus, nuclear envelope lamin B underwent covalent polymerization, which did not affect apoptotic nuclear fragmentation at low doses of DTHe. At higher doses, polymerization may have been extensive enough to prevent nuclear collapse. Hut-78, CD4 + cells were resistant to the photodynamically activated apoptotic pathway. Beyond the tolerated levels of photodynamic damage, these cells died exclusively via necrosis. Hut-78 cells overexpress Bcl-X L as well as a truncated Bcl-X L tr isoform that could contribute to the observed resistance to apoptosis.Keywords: photodynamic therapy; hypericin; dimethyl tetrahydroxyhelianthrone; Bcl-X; Bax; lamin; apoptosis 423British Journal of Cancer (1999) 79(3/4), 423-432 © 1999 Cancer Research Campaign Article no. bjoc.1998 Received Efforts to identify novel efficacious agents for photodynamic therapy led us to evaluate the photodynamically induced cytotoxicities of a newly designed photosensitizer 10,13-dimethyl 1,3,4,6-tetrahydroxyhelianthrone (DTHe) (Figure 1), in leukaemic cell lines. DTHe was chosen because of its dibenzperylenequinone chromophore (seven aromatic rings) that has absorption spectral properties virtually identical to hypocrellins, potent anti-tumoral photosensitizers isolated from the parasitic fungus Hypocrella bambuase which grows in China and Tibet (Diwu, 1990;Diwu, 1995; Miller, 1997). DTHe also shares structural similarities with HY and was anticipated to be a potent photosensitizer owing to its considerable light absorbance in the visible range of the spectrum. The phototoxicity profiles and mechanisms of cell death induction of DTHe were analysed in comparison with those of HY in HL-60, K-562 and Hut-...

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“…PDT has been receiving increasing attention as an important approach for cancer treatment [45,75]. Many compounds can be used as photosensitizers in PDT with low systemic toxicity and excellent biocompatibility [76,77].…”

Section: Photosynthesis-boosted Photodynamic Therapymentioning

confidence: 99%

“…A few cancer therapies, for example, radiotherapy (RT) and photodynamic therapy (PDT), also require oxygen to enhance efficacy [42][43][44]. PDT employs a light-activated photosensitizer to deliver energy to oxygen and then generates highly reactive singlet oxygen, which destroys tumor tissue by inducing cellular necrosis, apoptosis, acute inflammation, and attraction of leukocytes to the targeted tumors [45][46][47]. There are some oxygen-replenishing strategies for such therapies, including catalyzing endogenous H 2 O 2 with organic or inorganic catalysts [48][49][50], water splitting [51][52][53], oxygen transport [54,55], and respiratory inhibitors [56].…”

Section: Introductionmentioning

confidence: 99%

Photosynthetic biomaterials: applications of photosynthesis in algae as oxygenerator in biomedical therapies

et al. 2021

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For most organisms, molecular oxygen is indispensable for normal physiological metabolism; in humans, prolonged hypoxia in tissues can induce many diseases, exemplified by cardiovascular disease, chronic wounds, and tissue necrosis. Therefore, the oxygen in our environment is vital for life. As a main source of oxygen in the natural world that transforms light energy into chemical energy and oxygen, photosynthesis has been widely studied in scientific research and used in production of food, fuel, and medicine. In recent years, photosynthesis has become more closely involved in biomedicine and has been widely used in photodynamic therapy, tissue regeneration, transplantation, and in treatment of specific diseases. This review summarizes innovative applications of photosynthesis in biomedical research and highlights the theory and implications of clinical treatment for specific diseases.

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Photodynamic therapy

Cited by 9 publications

References 22 publications

Photodynamic therapy: basic principles and potential uses for the veterinary ophthalmologist

Photodynamic therapy: basic principles and potential uses for the veterinary ophthalmologist

A photodynamic pathway to apoptosis and necrosis induced by dimethyl tetrahydroxyhelianthrone and hypericin in leukaemic cells: possible relevance to photodynamic therapy

Photosynthetic biomaterials: applications of photosynthesis in algae as oxygenerator in biomedical therapies

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