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Showing papers in "Journal of Photochemistry and Photobiology B-biology in 1997"


Journal ArticleDOI
Martin Ochsner1
TL;DR: The purpose of this review article is to summarize the up-to-date knowledge on the mechanisms responsible for the induction of tumour necrotic reactions.
Abstract: Photodynamic therapy (PDT) is an innovative and attractive modality for the treatment of small and superficial tumours. PDT, as a multimodality treatment procedure, requires both a selective photosensitizer and a powerful light source which matches the absorption spectrum of the photosensitizer. Quadra Logic's Photofrin, a purified haematoporphyrin derivative, is so far the only sensitizer approved for phase III and IV clinical trials. The major drawbacks of this product are the lack of chemical homogeneity and stability, skin phototoxicity, unfavourable physicochemical properties and low selectivity with regard to uptake and retention by tumour vs. normal cells. Second-generation photosensitizers, including the phthalocyanines, show an increased photodynamic efficiency in the treatment of animal tumours and reduced phototoxic side effects. At the time of writing of this article, there were more than half a dozen new sensitizers in or about to start clinical trials. Most available data suggest a common mechanism of action. Following excitation of photosensitizers to long-lived excited singlet and/ or triplet states, the tumour is destroyed either by reactive singlet oxygen species (type II mechanism) and/or radical products (type I mechanism) generated in an energy transfer reaction. The major biological targets of the radicals produced and of singlet oxygen are well known today. Nucleic acids, enzymes and cellular membranes are rapidly attacked and cause the release of a wide variety of pathophysiologically highly reactive products, such as prostaglandins, thromboxanes and leukotrienes. Activation of the complement system and infiltration of immunologically active blood cells into the tumorous region enhance the damaging effect of these aggressive intermediates and ultimately initiate tumour necrosis. The purpose of this review article is to summarize the up-to-date knowledge on the mechanisms responsible for the induction of tumour necrotic reactions.

1,030 citations


Journal ArticleDOI
TL;DR: Mechanisms associated with the anti- and pro-oxidant behaviour of carotenoids are discussed includingCarotenoid interactions with other anti-Oxidants.
Abstract: Carotenoids are abundant in many fruits and vegetables and they play diverse roles in photobiology, photochemistry and medicine. This review concerns the reactivity of carotenoids with singlet oxygen and the interaction of carotenoids with a range of free radicals. Mechanisms associated with the anti- and pro-oxidant behaviour of carotenoids are discussed including carotenoid interactions with other anti-oxidants.

834 citations


Journal ArticleDOI
TL;DR: In this article, broad-band measurements have been made at Jungfraujoch, Switzerland (3576 m above sea-level) and Innsbruck, Austria (577 m a.s.l.), where daily totals of erythernal effective irradiance, UVA irradiance and total irradiance have been compared.
Abstract: Since 1981, broad-band measurements have been made at Jungfraujoch, Switzerland (3576 m above sea-level (a.s.l.)) and Innsbruck, Austria (577 m a.s.l.), where daily totals of erythemal effective irradiance, UVA irradiance and total irradiance have been compared. Under clear sky conditions, the observed increases in irradiance with altitude (altitude effect) of the daily totals of global irradiance are 8%±2% per 1000 m (total irradiance), 9%±2% per 1000 m (UVA irradiance) and 18%±2% per 1000 m (erythemal effective irradiance) during the summer. The altitude effect of the simultaneously measured erythernal effective irradiance between Innsbruck (577 m a.s.l.) and Hafelekar (2300 m a.s.l.), horizontally separated by 2.5 km, shows a slight dependence on the solar elevation: 15.1%±1.8% per 1000 m at 60° solar elevation and 18.6% ± 2.9% per 1000 m at 20° solar elevation. Simultaneously taken measurements of solar irradiance with high resolution spectrometers at Garmisch-Partenkirchen, Germany (730 m a.s.l.) and Wank (1730 m a.s.l.), horizontally separated by 5 km, show a clear wavelength dependence of the altitude effect of the global irradiance: 9% per 1000 m at 370 nm increasing to 11% per 1000 m at 320 nm and 24% per 1000 m at 300 nm. The altitude effect of direct irradiance is considerably higher than that of global irradiance at all measured wavelenths.

376 citations


Journal ArticleDOI
TL;DR: UV is absorbed by several target molecules relevant for cellular signaling, and it appears that numerous signal transduction pathways are stimulated.
Abstract: Irradiation of cell with short wavelength ultraviolet light (UVA, B and C) induces the transcription of many genes. The program overiaps with that induced by oxidants and alkylating agents and has both protective and other functions. Genes transcribed in response to UV irradiation include genes encoding transcription factors, growth factors, proteases and viral proteins. While the transcription of transcription factor encoding genes is initiated in minutes after UV irradiation (immediate response genes) and depends exclusively on performed proteins, the transcription of protease encoding genes occurs only many hours after UV irradiation. Transcription controlling the activity of immediate response genes are activated by protein kinases belonging to the group of proline directed protein kinases immediately after UV irradiation. Experimental evidence suggests that these kinases are activated in UV irradiated cells through pathways which are used by growth factors. In fact, the first cellular reaction detectable in UV irradiated cells is the phosphorylation of several growth factor receptors at tyrosine residues. This phosphorylation does not depend on UV induced DNA damage, but is due to an inhibition of the activity of tyrosine phosphatases. In contrast, for late cellular reactions to UV, an obligatory role of DNA damage in transcribed regions of the genome can be demonstrated. Thus, UV is absorbed by several target molecules relevant for cellular signaling, and it appears that numerous signal transduction pathways are stimulated. The combined action of these pathways establishes the genetic program that determines the fate of UV irradiated cells.

259 citations


Journal ArticleDOI
TL;DR: The singlet oxygen quantum yield of photodynamic agents was measured at 546nm, 630 nm and on the far-red absorption peak as mentioned in this paper, in a pH 7.4 phosphate buffer plus 1% Triton X-100 (PB/X100) for methylene blue in the phosphate buffer.
Abstract: The singlet oxygen quantum yield of photodynamic agents was measured at 546nm, 630 nm and on the far-red absorption peak. The technique employed is available in most laboratories, in which the photosensitization of lysozyme is used as an internal actinometer. Measurements in a pH 7.4 phosphate buffer plus 1% Triton X-100 (PB/X100) are scaled to 0.52 for methylene blue in the phosphate buffer. The average quantum yields are: hematoporphyrin IX (0.73), protoporphyrin IX (0.56), zinc protoporphyrin IX (0.91), mesotetra-(4-sulfonato-phenyl)porphine (0.61), PhotofrinR (0.89), benzoporphyrin derivative monoacid ring-A (0.84), chlorin e6 in PB (0.64), pheophorbide a (0.69), and aluminum phthalocyanine tetrasulfonate (0.38). Protection factors were measured for added azide ion, 1,4-diazabicyclo[2,2,2]-octane, and superoxide dismutase. Spectral evidence is presented for chlorin e6 interactions with PB/TX100 and for binding to lysozyme.

252 citations


Journal ArticleDOI
TL;DR: Factors that have been reported to influence photocarcinogenesis in laboratory animals, including the sensitivity of the test animals, the amount of the ultraviolet radiation delivered, the mode of its delivery, and interactions of other radiations or of chemicals in the process of carcinogenesis are reviewed.
Abstract: Photocarcinogenesis represents the sum of a complex of simultaneous and sequential biochemical events that ultimately lead to the occurrence of skin cancer These events, initiated by UV radiation of appropriate wavelength, include the formation of DNA photoproducts: DNA repair; mutation of proto-oncogenes and tumor suppressor genes; UV-production of radical species with subsequent effects on mutation and extra-nuclear function; and other epigenetic events that influence the course of carcinogenesis The epigenetic influences may include immunological responses, antioxidant defenses, and dietary factors This review represents an effort to provide current research results in the aforementioned areas and an attempt to meld these events into a comprehensive overview of photocarcinogenesis If effective prevention and intervention strategies for skin cancer are to developed, a more thorough understanding of the disease process is imperative

245 citations


Journal ArticleDOI
TL;DR: The skin possesses an elaborate antioxidant defence system to deal with UV-induced oxidative stress, but excessive exposure to UV can overwhelm the cutaneous antioxidant capacity, leading to oxidative damage and ultimately to skin cancer, immunosuppression and premature skin aging.
Abstract: The skin possesses an elaborate antioxidant defence system to deal with UV-induced oxidative stress. However, excessive exposure to UV can overwhelm the cutaneous antioxidant capacity, leading to oxidative damage and ultimately to skin cancer, immunosuppression and premature skin aging. Therefore, an interesting strategy for photoprotection is the support of the endogenous antioxidant system. This can be accomplished by induction or transdermal delivery of the various antioxidant enzymes, such as glutathione peroxidase, catalase, or superoxide dismutase. Supplementation of non-enzymatic antioxidants such as glutathione, alpha-tocopherol, ascorbate and beta-carotene was also found to be very effective in photoprotection. Although treatments with single components of the antioxidant system were successful against a wide variety of photodamage, the balance between the different antioxidants in the skin is very important. In some studies, it was found that too much of a single component could even have deleterious effects. The most promising results were obtained in studies combining several compounds, often resulting in synergism of the protective effects.

189 citations


Journal ArticleDOI
TL;DR: For the first time systematic measurements of the ''ultraweak'' photon emission of the human body (biophotons) have been performed by means of a photon detector device set up in darkness.
Abstract: For the first time systematic measurements of the \"ultraweak\" photon emission of the human body (biophotons) have been performed by means of a photon detector device set up in darkness. About 200 persons have been investigated. In a particular case one person has been examined daily over several months. It turned out that this biophoton emission reflects, (i) the left-right symmetry of the human body; (ii) biological rhythms such as 14 days, 1 month, 3 months and 9 months; (iii) disease in terms of broken symmetry between left and right side; and (iv) light channels in the body, which regulate energy and information transfer between different parts. The results show that besides a deeper understanding of health, disease and body field, this method provides a new powerful tool of non-invasive medical diagnosis in terms of basic regulatory functions of the body.

187 citations


Journal ArticleDOI
TL;DR: All the fluoroquinolone antibiotics studied have the capability of enhancing UVA-induced phototumorigenesis, but only lomefloxacin caused the development of cystic squamous cell carcinomas in the majority of treated animals.
Abstract: Fluoroquinolone antibacterials are known to be phototoxic, both in vivo and in vitro. The action spectrum for the phototoxicity of the quinolones lies mainly in the UVA region. During studies of systemic drug phototoxicity, Johnson et al. (Dundee) induced dose-dependent phototoxicity in Swiss albino mice, and severe phototoxic reactions were followed by the development of skin tumors. The present study was designed to compare the ability of several quinolones to produce photobiologic effects following chronic, subphototoxic UVA radiation. To compare the activities of different quinolones (lomefloxacin, fleroxacin, ciprofloxacin, ofloxacin and nalidixic acid), doses that result in similar plasma and skin levels of drug were administered by gavage to slightly pigmented Skh-1 hairless mice for up to 78 weeks. 8-Methoxypsoralen (8-MOP) was used as a positive control, and unirradiated, drug-treated and irradiated and unirradiated drug-free controls were also used. No signs of phototoxicity were seen, except for minimal-to-slight erythema and swelling of the skin in animals of the lomefloxacin-UVA group. Skin tumors (1 mm in diameter or larger) were observed in all the irradiated groups and the incidence was increased in all the groups treated with the test articles. The cumulative tumor prevalence was accelerated, the median latent periods were shortened and tumor onset was significantly enhanced by 8-MOP plus UVA, lomefloxacin plus UVA and fleroxacin plus UVA, as compared with vehicle plus UVA-exposed animals. The majority of skin tumors (with the exception of lomefloxacin and 8-MOP) were benign. The majority of squamous cell carcinomas in the lomefloxacin group were of a histologic type different from those previously reported in UVA-exposed animals. Thus, all the fluoroquinolone antibiotics studied have the capability of enhancing UVA-induced phototumorigenesis, but only lomefloxacin caused the development of cystic squamous cell carcinomas in the majority of treated animals.

182 citations


Journal ArticleDOI
TL;DR: Algae from the sublittoral zone had problems coping with the natural UV radiation in shallow water, whereas those from the intertidal zone were acclimatized to the unfavourable UV /PAR conditions.
Abstract: The photoinhibition in brown and red macroalgae from Spitsbergen (79°N, 12°E) was investigated to study the effects of UV under balanced UV /photosynthetically active radiation (PAR) conditions. Algae were collected from different depths and exposed to natural solar radiation. Various parts of the UV radiation spectrum were successively cut off by filters absorbing wavelengths of less than 295 nm, less than 320 nm and less than 400 nm. The samples were covered with these filters and exposed to daylight 10 cm below the water surface in outdoor tanks near the shore supplied with running seawater. PAR and UV radiation were continuously measured during the experiments. The degree of photoinhibition was observed during the course of the day by measuring the in vivo fluorescence of photosystem II ( F v F m ). In addition, the transmittance of the water body of the Kongsfjord (Spitsbergen, Norway) related to the UV and PAR wavelength ranges was determined. Even on a sunny day in August, only relatively low fluence rates of UVA (approximately 13 W m−2), UVB (approximately 0.14 W m−2) and PAR (approximately 1100 μmol m−2 s−1 ) were measured in the air at noon due to the low position of the sun at this high latitude. The UV transmittance of the water body in the fjord was also low. As a result, UV stress occurred only in seaweeds growing in the intertidal zone or in shallow water. The photoinhibition of photosynthesis was mainly induced by white light in shallow water. The inhibitory effects of UV radiation caused a delay in the recovery processes in the afternoon and evening, rather than an inhibitory effect on photosynthesis in the morning. Fucus distichus, growing in the upper intertidal zone, was most insensitive to UV radiation. Algae from the sublittoral zone had problems coping with the natural UV radiation in shallow water, whereas those from the intertidal zone were acclimatized to the unfavourable UV /PAR conditions. By cutting off sequentially the shorter wavelengths of the UV range, the investigated brown algae showed no significantly different effects. In contrast, the red alga Palmaria palmata showed a clear response to the different UV ranges, i.e. the UVB wavelength range was very effective in causing photoinhibition. In addition, the recovery phase was delayed in spite of the low fluence rates impinging on the alga during the course of the day.

180 citations


Journal ArticleDOI
TL;DR: In this article, photoactivation of ICG by irradiation with a diode laser was shown to induce effectively cell killing of HaCaT keratinocytes and this effect was inhibited by sodium azide.
Abstract: Indocyanine green (ICG; absorption peak in human plasma 805 nm) was investigated for ICG-mediated phototherapy in vitro. The cellular uptake of ICG (1 microM-50 microM) into HaCaT keratinocytes after an incubation period of 24 h increased up to an intracellular ICG concentration of 12.1 +/- 1.3 nmol per 10(6) cells. To examine dose dependent phototoxic effects in vitro, keratinocytes were incubated with 0 microM-50 microM ICG for 24 h and irradiated by a diode laser (805 nm) with different energy densities (0, 12, 24, 48 J cm-2). All applied ICG concentrations except for 5 microM yielded a cell killing effect in combination with irradiation depending significantly on ICG concentration and light dose. Cell viability for dark control and cells incubated with 50 microM ICG and irradiated with 48 J cm-2 was 0.82 +/- 0.15 and 0.07 +/- 0.02, respectively. Sodium azide (100 mM), a quencher of reactive oxygen species, inhibited significantly the cell killing using 50 microM ICG and 24 J cm-2. Taken together, photoactivation of ICG by irradiation with a diode laser was shown to induce effectively cell killing of HaCaT keratinocytes. Moreover, this effect was inhibited by sodium azide, thus irradiation of ICG might induce a photodynamic reaction.

Journal ArticleDOI
TL;DR: It is demonstrated that proline is involved in reducing the photodamage in the thylakoid membranes by scavenging and/or reducing the production of 1O2.
Abstract: Investigations were carried out to determine the involvement of proline in protecting thylakoid membranes against photodamage. The exposure of thylakoids isolated from the cotyledons of Brassica juncea to photoinhibitory light caused a linear increase in lipid peroxidation with time as measured by the assay of conjugated dienes and malondialdehyde (MDA). Proline produced a considerable reduction in the lipid peroxidation-linked formation of both conjugated dienes and MDA in the thylakoids during exposure to strong light. This reduction in lipid peroxidation reflects the probable involvement of proline in the reduction of the free radicals generated on strong light exposure. The thylakoids exposed to strong light intensity also generated singlet oxygen (1O2) and superoxide radical anion (O2−1). The level of these radicals increased with the time of exposure. The presence of proline significantly curtailed the production of 1O2 by the thylakoids during strong illumination. However, the presence of proline did not affect the O2− induction capacity of the thylakoid membranes during strong light exposure. Peroxidation of linolenic acid micelles occurred on exposure to UV radiation. The almost total suppression of UV-induced lipid peroxidation of linolenic acid micelles in the presence of sodium azide and L-histidine (singlet oxygen quenchers) suggested the involvement of 1O2 in UV-induced lipid peroxidation. The presence of proline during the exposure of linolenic acid micelles to UV radiation caused a considerable reduction in the formation of conjugated dienes as well as MDA. The proline-induced reduction in the peroxidation of these micelles further confirms the involvement of proline in reducing the level of 1O2. Our results therefore demonstrate that proline is involved in reducing the photodamage in the thylakoid membranes by scavenging and/or reducing the production of 1O2.

Journal ArticleDOI
TL;DR: In vitro chemical testing proved that successive methylation rendered the phenothiazinium chromophore both more resistant to reduction to its inactive leuco form, and also led to increased levels of singlet-oxygen production, thus providing a possible explanation for the increased toxicities of the methylated derivatives.
Abstract: The cytotoxic and photodynamic activities of the commercially-available biological stains methylene blue (MB), 1,9-dimethyl MB (Taylor's Blue) and a newly synthesised compound, 1-methyl MB, were measured against the murine mammary tumour cell line, EMT-6. Both 1-methyl MB and 1,9-dimethyl MB exhibited increased dark toxicity with concomitant higher phototoxicity compared to MB at a light dose of 7.2 J cm-2. While increasing the light dose as a function of the fluence rate increased the photocytotoxicity of MB, this had little effect on the methylated derivatives. In vitro chemical testing proved that successive methylation rendered the phenothiazinium chromophore both more resistant to reduction to its inactive leuco form, and also led to increased levels of singlet-oxygen production, thus providing a possible explanation for the increased toxicities of the methylated derivatives. Comparisons are made with the benzo[a]phenothiazinium photosensitizer, EtNBS.

Journal ArticleDOI
TL;DR: The TL01 lamp is less effective at reducing epidermal antigen presentation, inducing dendritic cell migration to lymph nodes draining irradiated sites and suppressing contact hypersensitivity at the doses tested, so the use of this lamp in phototherapy should be considered carefully after weighing up its diverse effects on the skin and immune system.
Abstract: The narrow-band UVB (TL01) lamp (311 nm emission) was developed for use in phototherapy, as an alternative to a broad-band UVB source and to photochemotherapy, both of which have significant side effects and carry a risk of carcinogenesis. This new lamp has proved to be particularly effective at clearing psoriasis. It is now acknowledged that the TL01 lamp is probably 2-3 times more carcinogenic per minimum erythema dose than broad-band UVB, but the cumulative dose required in therapy is considerably less than when using broad-band UVB sources. In terms of irradiation dose, the TL01 lamp is about 5-10-fold less potent than broad-band UVB for erythema induction, hyperplasia, oedema, sunburn cell formation and Langerhans cell depletion from skin. However, the broad-band UVB to TL01 potency ratio for cis-urocanic acid formation in the skin is approximately unity. In addition, the TL01 lamp, as used in phototherapy, has relatively more suppressive effects than broad-band UVB on systemic immune responses as judged by natural killer cell activity, lymphoproliferation and cytokine responses. However, the TL01 lamp is less effective at reducing epidermal antigen presentation, inducing dendritic cell migration to lymph nodes draining irradiated sites and suppressing contact hypersensitivity at the doses tested. Therefore the use of the TL01 lamp in phototherapy should be considered carefully after weighing up its diverse effects on the skin and immune system.

Journal ArticleDOI
TL;DR: The increase in NMSC incidence in the past two decades is not likely to be due to the decrease in ozone, given the long latency associated with UVR effects on skin, and projections suggest that this decline will continue into the next century.
Abstract: Current scientific evidence indicates that stratospheric ozone has declined worldwide over the past 20 years. The trend estimates are markedly dependent on the geographical location and are highly seasonal. Winter trends are much more negative than those for summer and autumn. Projections based on current assumptions of chlorine release suggest that this decline will continue into the next century. On the basis of the decrease in ozone over the mid-latitudes, an increase in biologically effective ultraviolet radiation (UVR) of 4%-9% is expected, depending on the season and geographical location. However, the UVR penetration to the Earth's surface is greatly affected by clouds, aerosols and tropospheric ozone, and current increases, if any, have not been as large as this. Direct evidence for the induction of non-melanoma skin cancer (NMSC) due to UVR has been derived from animal experiments in mice and rats. Numerous epidemiological data confirm that this relationship also holds for human skin. The increase in NMSC incidence in the past two decades is not likely to be due to the decrease in ozone, given the long latency (two to three decades) associated with UVR effects on skin. A knowledge of the action spectrum for NMSC development suggests that a 1% depletion in stratospheric ozone may be expected to increase NMSC, at equilibrium, by about 2.0% The evidence on the role of UVR exposure in the development of malignant melanoma (MM) is less certain. It has been estimated that a 1% reduction in ozone may cause an increase in MM of 0.6%.

Journal ArticleDOI
Elena Reddi1
TL;DR: Low-density lipoproteins and monoclonal antibodies, in particular, are regarded as the most promising delivery systems for anticancer drugs and some pharmacokinetic studies with LDL-associated photosensitizers have demonstrated a higher tumour uptake compared with the same photosensitized drugs delivered with other formulations.
Abstract: The use of photosensitizing drugs associated with different types of delivery vehicle has received strong interest within the field of the photodynamic therapy of tumours Lipid-based delivery vehicles, such as liposomes and oil emulsions, allow the administration of water-insoluble photosensitizers, widening the choice of photosensitizers potentially useful for treating tumours In some cases, these delivery vehicles increase the selectivity of tumour targeting by favouring photosensitizer uptake in tumour tissue However, a higher selectivity of tumour targeting could be obtained through the association of photosensitizers with delivery vehicles which can interact preferentially or specifically with tumour cells With this aim in mind, low-density lipoproteins (LDLs) and monoclonal antibodies, in particular, are regarded as the most promising delivery systems for anticancer drugs Some pharmacokinetic studies with LDL-associated photosensitizers have demonstrated a higher tumour uptake compared with the same photosensitizers delivered with other formulations Monoclonal antibody-coupled photosensitizers have been tested mainly in vitro, and have shown a high selectivity towards cells expressing specific antigens Only a limited number of reports are available on the biodistribution of immunoconjugated photosensitizers and on their selectivity in vivo, so that their importance for the selectivity of tumour targeting has not yet been defined

Journal ArticleDOI
TL;DR: Different strategies are explained which increase the affinity of the complexes for DNA and direct the complex photoreactivity to sites of special DNA topology or targeted sequences of bases.
Abstract: The design of Ru(II) and Os(II) complexes which are photoreactive with deoxyribonucleic acid (DNA) represents one of the main targets for the development of novel molecular tools for the study of DNA and, in the future, for the production of new, metal-based, anti-tumor drugs. In this review, we explain how it is possible to make a complex photoreactive with nucleobases and nucleic acids. According to the photophysical behaviour of the Ru(II) compounds, two types of photochemistry are expected: (1) photosubstitution of a ligand by a nucleobase and another monodentate ligand, which takes place from the triplet, metal-centred (3MC) state; this state is populated thermally from the lowest lying triplet metal to ligand charge transfer (3MLCT) state; (2) photoreaction from the 3MLCT state, corresponding to photoredox processes with DNA bases. The two photoreactivities are in competition. By modulating appropriately the redox properties of the 3MLCT state, an electron transfer process from the base to the excited complex takes place, and is directly correlated with DNA cleavage or the formation of an adduct of the complex to DNA. In this adduct, guanine is linked by N2 to the alpha-position of a non-chelating nitrogen of the polyazaaromatic ligand without destruction of the complex. Different strategies are explained which increase the affinity of the complexes for DNA and direct the complex photoreactivity to sites of special DNA topology or targeted sequences of bases. Moreover, the replacement of the Ru(II) ion by the Os(II) ion in the photoreactive complexes leads to an increased specificity of photoreaction. Indeed, only one type of photoreactivity (from the 3MLCT state) is present for the Os(II) complexes because the 3MC state is too high in energy to be populated at room temperature.

Journal ArticleDOI
TL;DR: The results of this experiments suggest that for a systemic application of 5-ALA side-effects in sensitive patients cannot be excluded, and PPIX levels in the plasma of blood samples could be detected via its fluorescence for all studied routes of application with the exception of the ointment.
Abstract: The fluorescence and photosensitivity of endogenously synthesized protoporphyrin IX (PPIX) is increasingly used for the diagnosis and treatment of malignant and certain non-malignant diseases. A selective accumulation of PPIX can be induced by application of 5-aminolevulinic acid (5-ALA), which is a precursor of PPIX in the cellular biosynthetic pathway of heme. The purpose of this study was to monitor the in vivo accumulation of PPIX in different locations of the skin after oral ingestion and to determine the pharmacokinetics of 5-ALA and PPIX in human blood plasma for various routes of application. At the same time we wanted to achieve an optimal treatment scheme but also study possible side-effects of 5-ALA administration. After oral application of 5-ALA in a concentration of 40 mg kg-1 body weight, the fluorescence intensities of PPIX in the skin showed maxima between 6.5 and 9.8 h depending on the location and decreased to values lower than 5% related to the maximum after a mean time of about 40 h. The measured absolute intensities of PPIX fluorescence varied strongly between different patients and different locations on one patient. In the plasma of blood samples, PPIX could be detected via its fluorescence for all studied routes of application with the exception of the ointment, where PPIX levels were below the detection limit of 1 microgram l-1. The highest mean concentration of 742 micrograms l-1 PPIX in the plasma was measured 6.7 h after oral application. For inhalation of 5-ALA, a mean maximum concentration of 12 micrograms l-1 could be detected 4.1 h after application, for intravesical instillation, the mean maximum concentration was found to be 1 microgram l-1 2.9 h after application. The kinetics of 5-ALA in the plasma peaked much earlier with a maximum concentration of 32 mg l-1 about 30 min. after oral administration. The 5-ALA levels did not exceed normal reference values after topical application. The results of our experiments suggest that for a systemic application of 5-ALA side-effects in sensitive patients cannot be excluded.

Journal ArticleDOI
TL;DR: Fluoroquinolones warrant further study, because they have potential photocarcinogenic properties, and an increase in the number of benign skin tumors when compared with animals exposed to UVA alone.
Abstract: Hairless mice were exposed orally to antibiotics of the fluoroquinolone group alone and in combination with irradiation with UVA over an extended period of time to determine the possible skin carcinogenicity in comparison with that with 8-methoxypsoralen, i.e. a known photochemical skin carcinogen. Animals exposed to UVA and fleroxacin, ciprofloxacin, nalidixic acid and ofloxacin exhibited an increase in the number of benign skin tumors when compared with animals exposed to UVA alone. Animals exposed to lomefloxacin and UVA exhibited a specific type of neoplastic progression. In addition to benign papillomas and solar keratoses, a number of cystic squamous cell carcinomas were observed. In the positive control group, which was given 8-methoxypsoralen and UVA, a number of papillomas and superficial squamous cell carcinomas were found. In animals exposed to UVA alone, only a few benign tumors were seen; in unexposed animals, no cutaneous neoplasms were observed. It is concluded that fluoroquinolones warrant further study, because they have potential photocarcinogenic properties.

Journal ArticleDOI
TL;DR: Comparison of the reconstructed in vivo spectrum with the measured spectra showed good agreement, outside of the blood absorption bands, suggesting that (i) the theoretical modeling, (ii) the skin optical parameters used, and (iii) the measured microscopic morphology and spectral data are consistent.
Abstract: The in vivo skin autofluorescence spectrum was reconstructed by Monte Carlo simulation using microscopic fluorophore distributions and intrinsic fluorescence spectra measured from excised skin tissue sections as well as employing published skin tissue optical parameters. The theoretical modeling took into account the light-tissue interactions of scattering, absorption, and regeneration of fluorescence photons. The modification of the intrinsic spectra by tissue optical properties to generate the in vivo spectrum observed at the tissue surface can be represented by a fluorescence detection efficiency function (η) which equals the integral of the product of the excitation light distribution inside the tissue and the fluorescence escape efficiency. Comparison of the reconstructed in vivo spectrum with the measured spectra showed good agreement, outside of the blood absorption bands, suggesting that (i) the theoretical modeling, (ii) the skin optical parameters used, and (iii) the measured microscopic morphology and spectral data are consistent. The divergence which exists over the strong blood absorption wavelength band (530–600 nm) suggests that the effect of blood contents on in vivo tissue optical properties deserves further investigations.

Journal ArticleDOI
TL;DR: Treatment with full-spectrum visible light at higher light doses may be the most effective and promising form of light exposure in ALA-PDT of solar keratoses.
Abstract: Photodynamic therapy with 5-aminolevulinic acid (ALA-PDT) is based on photosensitization by endogenous synthesis of protoporphyrin IX and its transient accumulation especially in malignant epithelially derived tissues. Recent studies have indicated that ALA-PDT is effective for the treatment of solar keratoses (SK), but there has been a lack of long-term clinical follow-up. The goal of the present study was to investigate the immediate and long-term effect of ALA-PDT on SK. Twenty-eight patients with a total of 251 SK were enrolled in the study. Standard treatment involved the topical application of 20% ALA, under occlusive and light-shielding dressing for 4 hours before exposure to UVA and/or different wave bands or wave band combinations of polychromatic visible light (full-spectrum visible light, and/or different wave bands of filtered visible light >515, >530, >570, or >610 nm) in one or two treatment sessions. The primary complete response rate of SK to ALA-PDT was 64% after one treatment, but 85% when the responses to a second treatment were included. Taken all treatments together, the complete response rate for lesions on face, scalp and neck was 93% for full-spectrum visible light, 96% for the combination of full-spectrum visible light and filtered light, 91% for different wave bands of filtered visible light, and 100% for the combination of long wave UVA and full-spectrum visible light, respectively. The complete response rate for lesions on forearms and hands was 51% for full-spectrum visible light and 33% for the combination of full-spectrum visible light and filtered light. The greater response rate for SK on the face, scalp, and neck was associated with a higher surface fluorescence and immediate response rate after ALA photosensitization at these sites ( X 2 : p = 0.0001). However, due to the treatment protocol the mean light dose applied to lesions on the face, scalp and neck (50 J cm −2 ) was substantially higher than that for lesions on forearms and hands (35 J cm −2 ). In the long term follow-up of SK on face scalp and neck, the projected disease-free rate at 36 months after therapy was 71% for lesions treated with full-spectrum visible light versus 23% for lesions treated with different wave bands of filtered light (Log rank - Mantel Cox; p = 0.0001). These results indicate that treatment with full-spectrum visible light at higher light doses may be the most effective and promising form of light exposure in ALA-PDT of SK.

Journal ArticleDOI
TL;DR: It was shown that the phototoxicity correlated well with thehypericin cellular uptake, and the reduction of the intracellular glutathione content did not enhance further the cytotoxic effects of photoactivated hypericin, as investigated with the A431, HeLa and MCF7 cells.
Abstract: The cytotoxic effects of the natural photosensitizing agent hypericin were evaluated. A dramatic difference in the sensitivity of several different human and mouse cell lines towards photoactivated hypericin (4J cm −2 ) was demonstrated using a neutral red assay (e.g. A431, IC 50 = 0.14 ± 0.02 μ M; HeLa,IC 50 = 0.32 ± 0.05 μ M; MCF7,IC 50 = 1.84 ± 0.22 μ M). Dark cytotoxicity was absent, even at high hypericin concentration (25 μM). The differential phototoxicity of hypericin did not correlate with the expression of the epidermal growth factor (EGF) receptor nor with the expression of the P170 glycoprotein in the cell. The reduction of the intracellular glutathione content did not enhance further the cytotoxic effects of photoactivated hypercin, as investigated with the A431, HeLA and MCF7 cells. Conversely, using confocal laser microscopy, it was shown that the phototoxicity correlated well with the hypericin cellular uptake.

Journal ArticleDOI
TL;DR: It is concluded that cationic lipophilic sensitizers, such as ZnPcA6, etc., specifically accumulate in the inner mitochondrial membranes and can be used for the selective photosensitization of mitochondria.
Abstract: In order to optimize the photosensitization of mitochondria, we prepared the new cationic zinc (II) phthalocyanines with lipophilic side-chains (2,9,16,23-tetrakis (trimethylammonio) zinc (II) phthalocyanine tetramethylsulphate (ZnPcA1) and 2,9,16,23-tetrakis(hexyldimethylammonio) zinc (II) phthalocyanine tetramethylsulphate (ZnPcA6)) and compared them with the known cationic lipophilic sensitizers 2,9,16,23-tetrakis[2-(trimethylammonio) ethoxy]zinc (II) phthalocyanine tetraiodide (ZnPcE1) and 2,9,16,23-tetrakis[2-(hexyldimethylammonio) ethoxy] zinc (II) phthalocyanine tetrabromide (ZnPcE6) and the anionic hydrophilic sulphonated sensitizer ZnPcS. The absorption and fluorescence spectra, fluorescence quantum yields, partition coefficients Po/w between octanol and water, dimerization of ZnPcA1 in water and photosensitized generation of singlet oxygen were examined. Moreover, the phototoxic and cytotoxic effects of the phthalocyanines on HeLa cells, their photodynamic action on the proliferation rate and the influence of irradiation on the respiratory activity were studied and compared with electron and fluorescence microscopic observations of the ultrastructure of incubated and irradiated HeLa cells. From our experiments, we conclude that cationic lipophilic sensitizers, such as ZnPcA6, etc., specifically accumulate in the inner mitochondrial membranes. Therefore they can be used for the selective photosensitization of mitochondria. On irradiation of the incubated HeLa cells, the cristae are affected and finally completely destroyed. The respiration stops and the energy metabolism breaks down. Our experiments indicate that the phototoxic efficacy of the sensitizers decreases in the following order: ZnPcA6 > ZnPcA1 > ZnPcE6 > ZnPcE1 > ZnPcS. The cationic lipophilic ZnPcA6 has the strongest phototoxic activity. It acts on incubation at very low sensitizer concentrations and short irradiation periods. The dark toxicity is completely negligible. The phototoxic activity follows the type II mechanism.

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TL;DR: The structure of mitochondria was studied after the irradiation of human lymphocytes with an He-Ne laser to show that the number of mitochondira was reduced to 9-12 in the irradiated cells compared with 40-45 in the control cells.
Abstract: The structure of mitochondria was studied after the irradiation of human lymphocytes with an He-Ne laser (wavelength, 632.8 nm; dose, 56 J m-2). Ultrathin sections of the lymphocytes were studied by electron microscopy 1 h after the irradiation. The irradiation resulted in a 20% increase (p = 0.95) in the number of mitochondrial profiles on the cell section without an increase in their total area. Three-dimensional reconstruction of mitochondria from ultrathin sections trough the whole lymphocyte showed that the number of mitochondria was reduced to 9-12 in the irradiated cells compared with 40-45 in the control cells. In the irradiated lymphocytes, 2-4 giant branching mitochondria were also observed among small discrete mitochondria.

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TL;DR: In vivo chemiluminescence appears to be a suitable method for following the kinetics of the oxidative stress processes and for testing the effect of topical application with antioxidant and photoprotective agents.
Abstract: Mouse skin was exposed to UVA radiation (320–400 nm). The in vivo chemiluminescence of the skin was measured after irradiation. Chemiluminescence showed a maximum 13-fold increase (control emission, 10 ± 1 cps cm−2) after 45–60 min of exposure to UVA, with no further increase with 60 min additional exposure. Spectral analysis of the emitted chemiluminescence showed that the principal species emitted in the 400–500 nm range. Topical application with α-tocopherol (10% v/w) and s-carotene (1 mM) greatly reduced the UVA-induced skin chemiluminescence. Thiobarbituric acid reactive substance (TBARS) levels were increased by 130% in skin homogenates after 2 h of exposure to UVA (control value, 77 ± 14 nmol malonaldehyde equivalents (g tissue)−1). The activities of antioxidant enzymes in skin homogenates were decreased after 2 h of irradiation: the superoxide dismutase (SOD) activity (control value, 181 ± 10 U SOD (g tissue)−1) was decreased by 40% and the catalase activity (control value, 1.34 ± 0.14 pmol (g tissue) 1) was decreased by 45%. In vivo chemiluminescence appears to be a suitable method for following the kinetics of the skin oxidative stress processes and for testing the effect of topical application with antioxidants and photoprotective agents.

Journal ArticleDOI
TL;DR: In this article, the photophysical parameters of a cationic prophyrin, i.e. fluorescence quantum yield and lifetime, triplet state formation and lifetime were determined directly in phosphate buffer solution in the native state and in complexes with calf thymus DNA, [poly(dA-dT)]2 and [poly (dG-dC)]2.
Abstract: The photophysical parameters (fluorescence quantum yield and lifetime, triplet state formation and lifetime) of a cationic prophyrin, i.e. 5,10,15,20-tetrakis(4-N-methylpyridyl) porphyrin (H2(TMpy-P4)), were determined directly in phosphate buffer solution in the native state and in complexes with calf thymus DNA, [poly(dA-dT)]2 and [poly(dG-dC)]2. In [poly(dG-dC)]2-porphyrin complexes (mostly intercalative), interaction induced an efficient fluorescence quenching and decrease in the triplet state quantum yield. No such effects were observed in [poly(dA-dT)]2-pophyrin complexes (mostly non-intercalative). The case of DNA was intermediate between the other two. On the basis of the redox properties of the various nucleic bases, it was shown that these observations can be interpreted in terms of fast reversible intermolecular electron transfer from the guanine moiety to the porphyrin in the excited state, when the porphyrin is intercalated with an appropriate geometry within the DNA duplex. These observations and interpretations support a type I (electron transfer) mechanism as the primary event leading to the photodynamic activity of cationic free base porphyrins used as photosensitizers in the process of photoinduced DNA strand breaks.

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TL;DR: The UV action spectra of two different biologically weighting UV photofilms (spore films) produced with Bacillus subtilis spores are determined at the Okasaki large spectrograph (OLS) within the level of wavelength range 254-400 nm, yielding a sensitivity curve similar to the action spectrum for erythemal induction in human skin.
Abstract: The UV action spectra of two different biologically weighing UV protofilms (spore films), produced with Bacillus subtilis spores (wild-type and DNA repair-deficient strains), were determined at the Okasaki large spectrograph (OLS) within the wavelength range 254–400 nm. The action spectrum of the mutant strain film was modified with a cut-off filter, yielding a sensitivity curve similar to the action spectrum for erythemal induction in human skin. The detector system was tested in a field study and in a study using lamps with different UV spectral compositions. The systems demonstrated its applicability over the spectral region from λ = 290 nm to the visible light. The system could be calibrated to give the minimal erythemal dose.

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TL;DR: The ability of ZnPC in liposomes to photoreact effectively by an electron transfer mechanism is demonstrated and type I processes may add to the effects of singlet oxygen in Zn PC-mediated PDT.
Abstract: Zinc(II) phthalocyanine (ZnPC) is a new photosensitizer currently undergoing phase I and II clinical trials at Lausanne's CHUV hospital for the photodynamic therapy (PDT) of early cancer in the upper aerodigestive tract. Activated oxygen species other than singlet oxygen produced during the photosensitization of ZnPC in liposomes have been examined by electron paramagnetic resonance (EPR) spin trapping and by the cytochrome c reduction method. Visible light irradiation of ZnPC associated with liposomes in the presence of the spin trap 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) gives an EPR spectrum characteristic of the DMPO-hydroperoxyl radical spin adduct (DMPO-.OOH). Superoxide anion attains a level of 1 microM min-1 20 min after the start of irradiation as determined by the superoxide dismutase (SOD)-inhibitable reduction of cytochrome c. The yield of O2.- is strongly enhanced by physiological electron donors. An EPR spectrum characteristic of the DMPO-hydroxyl radical spin adduct (DMPO-.OH) is also observed. The addition of dimethyl sulphoxide or ethanol produces additional hyperfine splittings due to the respective hydroxyalkyl radical products, indicating the presence of free .OH. DMPO-.OH is significantly inhibited by desferrioxamine or catalase. Conversely, this adduct is enhanced by hydrogen peroxide. These data demonstrate the ability of ZnPC in liposomes to photoreact effectively by an electron transfer mechanism. Such type I processes may add to the effects of singlet oxygen in ZnPC-mediated PDT.

Journal ArticleDOI
TL;DR: In this article, the absorption and fluorescence spectral data and triplet energy content, as well as quantum yields of fluorescence, of triplet state formation, and of sensitized generation of singlet molecular oxygen, O 2 ( 1 Δ g ), of 38 porphycene derivatives are reported.
Abstract: Absorption and fluorescence spectral data and triplet energy content, as well as quantum yields of fluorescence, of triplet state formation, and of sensitized generation of singlet molecular oxygen, O 2 ( 1 Δ g ) , of 38 porphycene derivatives are reported. Long-wavelength absorption and the efficiency of fluorescence and O 2 ( 1 Δ g ) sensitization qualify most of these porphycenes as potential photodynamic therapy agents (so-called second-generation sensitizers), unless steric or electronic effects by substitution perturb the parent aromatic 18 π system.