Photodynamic therapy in the treatment of basal cell carcinoma.

Photodynamic therapy (PDT) is a medical procedure based on the activation of the molecules of various exogenous or endogenous chemical substances called photosensitizers by a light source emitting radiation of an adequate wavelength, usually situated in the visible spectrum; photosensitizers are chemical compounds bearing the capacity to selectively concentrate in the neoplastic cells. The energy captured by the molecules of these substances pervaded in the tumor cells is subsequently discharged in the surrounding tissue, triggering certain photodynamic reactions that result in the destruction of the tumor. The procedure is applicable in numerous medical fields. Skin basal cell carcinoma (BCC), the most frequent type of cancer of the human species, is a cutaneous tumor that responds very well to this innovative treatment method. By reviewing numerous recent studies in the field, this article aims to present the role and the indications of photodynamic therapy in the management of basal cell carcinoma, as well as the most important results achieved so far by this therapy in the field of dermato-oncology.

Oxidative photodamage induced by photodynamic therapy with methoxyphenyl porphyrin derivatives in tumour-bearing rats.

The oxidative effects of photodynamic therapy with 5,10,15,20-tetrakis(4-methoxyphenyl) porphyrin (TMP) and Zn-5,10,15,20-tetrakis(4-methoxyphenyl) porphyrin (ZnTMP) were evaluated in Wistar rats subcutaneously inoculated with Walker 256 carcinoma. The animals were irradiated with red light (λ = 685 nm; D = 50 J/cm2; 15 min) 3 h after intra-peritoneal administration of 10 mg/kg body weight of porphyrins. The presence of free radicals in tumours after photodynamic therapy with TMP and ZnTMP revealed by chemiluminescence of luminol attained the highest level at 18 h after irradiation. Lipid peroxides measured as thiobarbituric-reactive substances and protein carbonyls, which are indices of oxidative effects produced on susceptible biomolecules, were significantly increased in tumour tissues of animals 24 h after photodynamic therapy. The levels of thiol groups and total antioxidant capacity in the tumours were decreased. The activities of antioxidant enzymes superoxide dismutase and glutathione peroxidase were also increased in tumour tissues after photodynamic therapy. Increased levels of plasma lipid peroxides as well as changes in the levels of erythrocyte antioxidant enzyme activities suggest possible systemic effects of photodynamic therapy with TMP and ZnTMP.

Possible in vivo mechanisms involved in photodynamic therapy using tetrapyrrolic macrocycles

Photodynamic therapy (PDT) mediated by oxidative stress causes direct tumor cell damage as well as microvascular injury. To improve this treatment new photosensitizers are being synthesized and tested. We evaluated the effects of PDT with 5,10,15,20-tetrakis(4-methoxyphenyl)-porphyrin (TMPP) and its zinc complex (ZnTMPP) on tumor levels of malondialdehyde (MDA), reduced glutathione (GSH) and cytokines, and on the activity of caspase-3 and metalloproteases (MMP-2 and -9) and attempted to correlate them with the histological alterations of tumors in 3-month-old male Wistar rats, 180 ± 20 g, bearing Walker 256 carcinosarcoma. Rats were randomly divided into five groups: group 1, ZnTMPP+irradiation (IR) 10 mg/kg body weight; group 2, TMPP+IR 10 mg/kg body weight; group 3, 5-aminolevulinic acid (5-ALA+IR) 250 mg/kg body weight; group 4, control, no treatment; group 5, only IR. The tumors were irradiated for 15 min with red light (100 J/cm², 10 kHz, 685 nm) 24 h after drug administration. Tumor tissue levels of MDA (1.1 ± 0.7 in ZnTMPP vs 0.1 ± 0.04 nmol/mg protein in control) and TNF-α (43.5 ± 31.2 in ZnTMPP vs 17.3 ± 1.2 pg/mg protein in control) were significantly higher in treated tumors than in controls. Higher caspase-3 activity (1.9 ± 0.9 in TMPP vs 1.1 ± 0.6 OD/mg protein in control) as well as the activation of MMP-2 (P < 0.05) were also observed in tumors. These parameters were correlated (Spearman correlation, P < 0.05) with the histological alterations. These results suggest that PDT activates the innate immune system and that the effects of PDT with TMPP and ZnTMPP are mediated by reactive oxygen species, which induce cell membrane damage and apoptosis.

Possible in vivo mechanisms involved in photodynamic therapy using tetrapyrrolic macrocycles.

Photodynamic therapy (PDT) mediated by oxidative stress causes direct tumor cell damage as well as microvascular injury. To improve this treatment new photosensitizers are being synthesized and tested. We evaluated the effects of PDT with 5,10,15,20-tetrakis(4-methoxyphenyl)-porphyrin (TMPP) and its zinc complex (ZnTMPP) on tumor levels of malondialdehyde (MDA), reduced glutathione (GSH) and cytokines, and on the activity of caspase-3 and metalloproteases (MMP-2 and -9) and attempted to correlate them with the histological alterations of tumors in 3-month-old male Wistar rats, 180 ± 20 g, bearing Walker 256 carcinosarcoma. Rats were randomly divided into five groups: group 1, ZnTMPP+irradiation (IR) 10 mg/kg body weight; group 2, TMPP+IR 10 mg/kg body weight; group 3, 5-aminolevulinic acid (5-ALA+IR) 250 mg/kg body weight; group 4, control, no treatment; group 5, only IR. The tumors were irradiated for 15 min with red light (100 J/cm², 10 kHz, 685 nm) 24 h after drug administration. Tumor tissue levels of MDA (1.1 ± 0.7 in ZnTMPP vs 0.1 ± 0.04 nmol/mg protein in control) and TNF-α (43.5 ± 31.2 in ZnTMPP vs 17.3 ± 1.2 pg/mg protein in control) were significantly higher in treated tumors than in controls. Higher caspase-3 activity (1.9 ± 0.9 in TMPP vs 1.1 ± 0.6 OD/mg protein in control) as well as the activation of MMP-2 (P < 0.05) were also observed in tumors. These parameters were correlated (Spearman correlation, P < 0.05) with the histological alterations. These results suggest that PDT activates the innate immune system and that the effects of PDT with TMPP and ZnTMPP are mediated by reactive oxygen species, which induce cell membrane damage and apoptosis.

The dynamics of reactive oxygen species in photodynamic therapy with tetra sulfophenyl-porphyrin.

Photodynamic therapy (PDT) is a promising therapy especially in skin cancer, using the systemic administration of a photosensitizer (PS), followed by the local irradiation of the tumor with visible light. The antitumor effects of PDT are determined especially by the generation of cytotoxic reactive oxygen species (ROS). The 5,10,15,20-tetra-sulfo-phenyl-porphyrin (TSPP) is a synthetic photosensitizer, which proved its efficiency in in vitro studies. Our study evaluates the effects of PDT with TSPP upon the tumor levels of ROS and upon the metalloproteinases 2 (MMP2) activities on Wistar male rats bearing 256 Walker carcinosarcoma in correlation with the accumulation of PS in the tumor and with the intratumor histological alterations. The evaluations were performed dynamically, at 3 hours, 6 hours, 24 hours and 14 days after the PDT with TSPP. Our results emphasize that 24 hours after the PDT with TSPP, the ROS generation increases, as revealed by protein carbonyls and malondialdehyde levels and the antioxidant capacity (hydrogen donors, thiol groups) decreases in the tumor tissue. These parameters were correlated with the appearance of the histological disorders. The MMP-2 activity increases exponentially in the 24 hours-14 days post PDT interval. PDT with TSPP offers, in vivo , consistent results regarding ROS generation, MMP2 activation and cytotoxic capacity.

Spectroscopic characteristics of metalloporphyrins used in photodynamic therapy.

The photodynamic therapy (PDT) became more and more widely used in the treatment of different malignant tumors. For present studies, porphyrins and haematoporphyrin derivatives, in the conditions of N2 laser radiation, were chosen because their strong absorption along a large spectral range; this makes possible the excitation of their fluorescence at 337.1 nm, which is the wavelength of the N2 pulsed laser radiation. The photophysical and photochemical properties depend on the central metal and the peripheral substituents. Trying to find an optimal sensitizer to be used with N2 laser in photodynamic therapy (PDT), a spectroscopic study of these dyes was performed. The obtained data show that the UV radiation emitted by a N2 pulsed laser may be used for PDT application; among other dyes having interesting characteristics, Zn-TSPP and Zn-TNP in DMSO at 0.5% concentration seem to be more relevant.

Photochemical and photodynamic properties of vitamin B2--riboflavin and liposomes.

Ocular neovascular disease represents an important cause of blindness today. In this paper, it was used a model to evaluate the vaso-occlusive potential of photodynamic therapy with B2 vitamin. Neovascularization induced în an occular cornea consists of an easily accessible monolayer-like neovascular net within a transparent matrix. This fact allows studying the efficiency of occlusion în an isolated neovascular structure. This study is a requirement for the transport evaluation and photodynamic efficiency of this drug. Both riboflavin and the DPBF are embedded în the phospholipid bilayer. The quantum yield of DPBF photooxidation and riboflavin singlet oxygen generation are higher by comparison with water (13-35 s în liposomes and 0.4 s în water), due to the higher lifetime of singlet oxygen în liposomes and due to the special transport mechanism of B2 inside of liposomes. The photochemical behavior of riboflavin (Vitamin B2) aqueous solution and în unilamellar liposomes of dipalmitoyl phosphatidylcholine (DPPC) during the sensitized photooxidation of 1,3-diphenylisobenzofuran (DPBF) are discussed în this paper. Some structural aspects of DPPC liposomes, have been studied, too. The first step în the sequence of vesicle shape transformations, the spherical to polygonal shape transition, occurs în a very narrow temperature range, i.e., during the gel-to-liquid crystalline phase transition. At different temperatures (30,37-42 degrees C) could be seen the sequence for the vesicle form: spherical-polygonal-ellipsoidal, attributable to the lipid domain coexistence on the macroscopic structure of liposomes. The incorporation of B2 Vitamin eliminates the ellipsoidal form of DPPC, even at high temperature, because B2 has a very small molecule able to be encapsulated into DPPC vesicle. Also, the incorporation of B2 increase the DPPC diameter, all these observations being obtained by optical confocal microscopy.

The British reaction to dementia praecox 1893-1913. Part 1.

Emil Kraepelin introduced the concept of dementia praecox in 1893. The eventual acceptance of the concept brought a degree of clarity and order previously unknown to psychiatric nosology. The pre-Kraepelin era had been dominated by concepts such as mania, melancholia and adolescent insanity. After Kraepelin these ideas were abandoned in favour of the two great concepts of dementia praecox and manic depressive insanity, both of which remain active within modern psychiatry in the form of schizophrenia and bipolar disorder. This two-part study focuses on the early British reaction to Kraepelin's concept, from 1893, when he first introduced it, to 1913 when it gained general recognition. It examines the struggle experienced by the proponents of dementia praecox before the concept's acceptance by most British psychiatrists in 1913. It argues that both clinical/professional and linguistic factors influenced the British response to dementia praecox. Part 1 of this study describes the backdrop to the development of Kraepelin's ideas and examines the response to the concept in the British psychiatric textbooks and journals of the period. Part 2 will explore reaction to the concept in the professional meetings of the period, and will also examine and evaluate the key issues arising from the debate.

The British reaction to dementia praecox 1893-1913. Part 2.

Part 1 of this study described the backdrop to the development of Kraepelin's ideas on dementia praecox and examined the response to the concept in the British psychiatric textbooks and journals of the period. Part 2 now explores the reaction to the concept in the professional meetings of the period, held by the British Medical Association (BMA) and the Medico-Psychological Association (MPA) during the years 1893 to 1913. In addition, it examines and evaluates the main issues and conclusions arising from the debate.

Photodynamic occlusion of ocular neo-vascularization with B2 vitamin.

Photodynamic therapy (PDT) of cancer has been known for over twenty years and is based on the dye-sensitized photooxidation of different biological targets in the tumoral tissue yielding to a photochemically induced cell's death via apoptotic pathways. Several parameters affect clinical trials in PDT and influence the therapeutic outcome. A potentially major application of PDT in a non-cancer field is its use in treatment of age-related macular degeneration. This condition, caused by proliferation of neovasculature in the retina, is the major cause of blindness in the over 50s. Using a photosensitiser which enters neovasculature very rapidly following administration and is subsequently quickly moved from the circulation. Ocular neovascular disease represents an important cause of blindness today. In this paper, was used an animal model (rabbit) to evaluate the vaso-occlusive potential of photodynamic therapy with B2 vitamin. Neovascularization induced in the rabbit cornea consists of an easily accessible monolayer-like neovascular net within a transparent matrix. This fact allows studying the efficiency of occlusion in an isolated neovascular structure.

The interactions of phthalocyanines with stimulated and resting human peripheral blood mononuclear cells.

The interactions of two metal-free phthalocyanines [(H2Pc) and Solar Pc (with four peripherical groups: SO2N(CH2CH2OH)2)] and of one metal substituted dye (CoPc) with resting and stimulated human peripheral blood mononuclear cells (PBMC) were compared. The absorption, fluorescence, photoacoustic and EPR spectra of both resting cells and cells stimulated by phytohaemagglutinin, incubated in dimethyl sulfoxide (DMSO) with very low or 95% water content and with or without dye addition, were measured. The fate of the light absorbed by the samples was investigated. It is known that singlet oxygen production is crucial for photodynamic action of dyes. Thermal deactivation and luminescence emission compete with this process, so investigation of these alternative paths of sensitizer deactivation provides information about photodynamic action. The incorporation of the investigated dyes into cells and the perturbation of the cell structure caused by the dyes, the incubation solvent and the activator were investigated by comparing the spectral properties of PBMC before and after stimulation and incubation. Incubation of the cells for 1 h in a solution of Solar Pc in 99.5% aqueous DMSO, resulted in an efficient dye incorporation which was highly selective. Solar Pc being introduced much more efficiently into stimulated cells than into resting cells.

Spectral analysis of the porphyrins incorporation into human blood.

The porphyrins seem to be the most effective photosensitizers in photodynamic therapy of cancer. Monomers and dimers of sulfonated and nonsulfonated porphyrins [5,10,15,20-tetra-phenyl-porphyrin, 5,10,15,20-tetra-naphtyl-porphyrin (TNP), 5,10,15,20-tetra-p-sulfonato-phenyl-porphyrin (TS4PP) and 5,10,15,20-tetra-p-sulfonato-naphtyl-porphyrin], are studied in this paper by means of different spectral methods (UV-vis, fluorescence and polarization fluorescence). The porphyrins as TNP seem to be the most effective photosensitizer especially in a DMSO:water binary mixture of solvent. Monomer-dimer and J-aggregation equilibria and the temperature dependence of TS4PP spectra are also studied in this paper. The incorporation of the forms of these porphyrins into blood cells is studied by means of the cytofluorimetric method. © 1999 Society of Photo-Optical Instrumentation Engineers.

The incorporation of various porphyrins into blood cells measured via flow cytometry, absorption and emission spectroscopy.

The incorporation of the five following porphyrins: meso-tetra(4-phenyl)porphyrin (TPP); meso-tetra(4-sulfonato-phenyl)porphyrin (TPPS4); meso-tetra(4-naphthyl)porphyrin (TNP); tri-sulfo-tetra-phenyl porphyrin (TPPS3) and tetra-sulfonato-naphthyl porphyrin (TNPS4) into human blood cells was investigated using flow cytometry, and absorption and emission spectroscopy. The percentage of stained cells, measured in a fluorescence cytometer, provided information on the efficiency of incorporation of fluorescent dye molecules into different types of cells. The yield of the incorporation of a dye was dependent on the type of dye and the solvent used for cell incubation. The degree of dye aggregation and ionization varied with the incubation medium, but dye molecules incorporated into cells seemed to be restricted to those in the monomeric state, exhibiting similar fluorescence yield. Of the three sulfonated porphyrins investigated only TPPS4 was efficiently incorporated into leukocytes. In the incubation solvent, this dye was in monomeric and neutral form. TPPS3 which was also in monomeric form, practically was not incorporated into cells. TPP and TNP dissolved in 5% aqueous dimethyl sulfoxide were present mostly in aggregated forms but they penetrated the cells with a high efficiency.