PubMed Health⌕ Search

Biomedical subjects

A Rück

Publications and source records attributed to A Rück.

At least 37 records · Page 2Linked to original sources
PubMed1996

Comparison of sensitivity towards photodynamic therapy of cutaneous resident and infiltrating cell types in vitro.

BACKGROUND AND OBJECTIVE: Photodynamic therapy (PDT) combines photosensitizers absorbing light in the visible spectral region and irradiation with light of corresponding wavelengths. We analysed the sensitivity of cell lines established from resident cutaneous cells and from transformed lymphocytes towards PDT. STUDY DESIGN/MATERIALS AND METHODS: PDT was performed employing either 630 or 662 nm light or polychromatic red light (600-700 nm) and photosensitizers Photosan-3, delta-aminolevulinic acid, or methylene blue. Proliferation measured by 3H-TdR uptake was determined in human immortalized keratinocytes (HaCaT) and mouse fibroblasts (NIH/3T3) in comparison to human transformed T-(HuT78) and B-lymphocytes (RA1). Additionally, uptake of the photosensitizers was estimated employing video-intensified fluorescence-microscopy (VIFM). RESULTS: Depending on the photosensitizer tested HaCaT and NIH/3T3 exhibited an ED50 up to 10-fold as high as the lymphocytic lines. Polychromatic red light was at least as effective at inducing photodynamic reactions as 630 or 662 nm light. VIFM revealed a positive correlation between sensitivity of a given cell type towards PDT and uptake of the photosensitizers. The differential uptake observed in vitro was confirmed in vivo: A photosensitizer applied topically on a lesion of a patient with mycosis fungoides was found to accumulate preferentially in the lymphocytic infiltrate. CONCLUSION: Selective topical polychromatic PDT seems to be a feasible goal for the treatment of cutaneous lymphomas.

Aminolevulinic Acid↗
PubMed1996

Aminolevulinic acid for photodynamic therapy of bladder carcinoma cells.

A new concept in photosensitizing tumor cells is photosensitizer synthesis in situ. Aminolevulinic acid (ALA) is a precursor of protoporphyrin IX (PP IX), a potent photosensitizer. The goal of our study was to examine dark toxicity, phototoxic potential, metabolism of ALA and morphological alterations in Waf bladder cancer cells. Dark toxicity of Waf cells was observed after incubation with ALA, beginning at a concentration of 15 mM. Photodynamic treatment with ALA at concentrations of 1, 5 and 10 mM showed a drug- and light-dose-dependent cell survival rate in comparison to a control group. Two incubation times of 3.5 and 5.5 h were compared for cell survival. After a longer incubation time of 5.5 h, cell survival was decreased in all experiments; this is consistent with our extraction data where higher fluorescence was found after 5.5 than after 3.5 h. The results show that ALA-induced photosensitization has a high potential for photodynamic therapy (PDT) of superficial bladder carcinoma.

Aminolevulinic Acid↗
PubMed1996

Dynamic fluorescence changes during photodynamic therapy in vivo and in vitro of hydrophilic A1(III) phthalocyanine tetrasulphonate and lipophilic Zn(II) phthalocyanine administered in liposomes.

The fluorescence emission of hydrophilic tetrasulphonated aluminium phthalocyanine (AlPcS4) and hydrophobic zinc phthalocyanine (ZnPc), bound to the membrane of liposomes, was investigated in vivo in an appropriate tumour model of the rat bladder and in RR 1022 epithelial cells of the rat. The sensitizers were administered systemically to the rats and photodynamic therapy (PDT) was performed 24 h later. During PDT treatment, the fluorescence was measured every 30 s. The fluorescence was excited with 633 nm light from an HeNe laser and the fluorescence spectra were detected with an optical multichannel analyser system. PDT was performed for both sensitizers using 672 nm light from an Ar+ dye laser. The fluorescence changes during PDT were significantly different for the two phthalocyanines. For AlPcS4, an initial fluorescence intensity increase, followed by subsequent photobleaching, was observed. In contrast, ZnPc fluorescence showed an exponential decrease and no increase at the start of treatment. Tumour necrosis 24 h after PDT was significant only for ZnPc. RR 1022 cells incubated for 24 h with AlPcS4 revealed a granular fluorescence pattern, whereas ZnPc was localized diffusely in the cytoplasm of the cells. In agreement with the in vivo measurements, subcellular relocalization and a fluorescence intensity increase were detected exclusively in the case of AlPcS4. Morphological changes at this time were significant only for ZnPc. The subcellular localization and fluorescence kinetics were obtained using a confocal laser scanning microscope.

Animals↗
PubMed1995

Photodynamic efficiency of liposome-administered tetramethyl hematoporphyrin in two human bladder cancer cell lines.

The main problems presented by superficial bladder carcinoma, its high recurrence rate and multifocal appearance, require treatment of the bladder as a whole. Photodynamic therapy (PDT) is one such experimental treatment for superficial bladder carcinoma, involving the administration of a photosensitizer that accumulates in the tumor tissue, and subsequent irradiation of the tumor with light. Since the photosensitizers used in PDT suffer from several drawbacks, new photosensitizers are being sought. Drug delivery systems are also being investigated for the administration of hydrophobic photosensitizers and enhancement of photodynamic efficiency and tumor selectivity. In this study we examined a new photosensitizer, tetramethyl hematoporphyrin (TMHP), in two human bladder cancer cell lines. In the first pair of the experiments, TMHP was bound to unilamellar liposomes. Cellular uptake, dark toxicity and photodynamic efficiency were then studied. Fluorescence microscopy showed TMHP localization in the cytoplasm in a perinuclear region, sparing the nucleus. Dark toxicity occurred after incubation of cells with TMHP above a concentration of 20 micrograms/ml. Irradiation was carried out using an argon-pumped dye laser emitting a wavelength of 630 nm at a fluence of 3.6 and 7.2 J/cm2. Before irradiation, cells were incubated with TMHP at concentrations of 2.5 and 5 micrograms/ml for 1 h. Cell survival rates after incubation with 5 micrograms/ml TMHP and irradiation at 7.2 J/cm2 were 15.7% of control cells for Rec and 4.5% for Waf cells. Uptake studies showed a higher intracellular TMHP concentration in Waf than in Rec cells. This correlates with the higher PDT efficiency seen in Waf cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Transitional Cell↗
PubMed1995

Intracellular fluorescence behaviour of meso-tetra(4-sulphonatophenyl)porphyrin during photodynamic treatment at various growth phases of cultured cells.

Meso-tetra(4-sulphonatophenyl)porphyrin (TPPS4) taken up by cells is mainly localized in lysosomes as previously shown by fluorescence microscopical and fluorescence spectroscopical investigations. In the present study the intracellular fluorescence behaviour and the intracellular amount of this dye at various growth periods of cells were examined. For cells irradiated in the growth phase a relocalization of TPPS4 from the lysosomes into the cytoplasm and finally into the nucleus was observed. In contrast, for cells irradiated in the stationary phase no redistribution could be detected and therefore no evidence for severe damage of the lysosomal membranes and subsequently for the release of lytical enzymes is given. In both cases lethal damage of the cells was achieved as examined using the trypan blue exclusion test. This indicates that damage of the lysosomes is less important in the photodynamic inactivation of cells sensitized by TPPS4.

Animals↗
PubMed1995

Time-resolved pH-dependent fluorescence of hydrophilic porphyrins in solution and in cultivated cells.

Fluorescence decay kinetics and time-gated (nanosecond) emission spectra of the hydrophilic photosensitizers meso-tetra(4-sulfonatophenyl)porphyrin (TPPS4) and uroporphyrin III (UP III) are reported. These substances are characterized by low aggregation, preferential accumulation within lysosomes and a pH-dependent composition of unprotonated and protonated species. A comparison of TPPS4 and UP III in buffer solutions and in confluently growing RR 1022 epithelial cells showed that the intracellular pH value of the environment of both photosensitizers was about 4.7. A slight decrease by 0.10-0.15 pH units occurred after light exposure which (in the case of TPPS4) was concomitant with a lethal damage of the cells. A photoproduct at 640 nm with a characteristic fluorescence lifetime of 4.3 +/- 0.8 ns was detected for UP III in buffer solutions at pH values above 5. The absence of this photoproduct in epithelial cells again indicated that UP III was located within lysosomes.

Animals↗
PubMed1995

Influence of activation and differentiation of cells on the effectiveness of photodynamic therapy.

Photodynamic therapy combines photosensitizers absorbing light in the red spectral region and irradiation with light of the corresponding wavelength. To analyse the influence of cell differentiation on susceptibility to photodynamic therapy, we compared the proliferation inhibition induced by photodynamic therapy on normal human keratinocytes, spontaneously transformed human keratinocyte cell line HaCat and on squamous cell carcinoma lines. Cells were irradiated with polychromatic methylene blue as well as the precursor of protoporphyrin, 5-aminolevulinic acid. When incubated with Photosan-3, normal human keratinocytes exhibited and ED50 about 10-fold lower than the other cell lines studied. When methylene blue and 5-aminolevulinic acid were used, photodynamic therapy had comparable effects on all cell types. Stimulation of normal human keratinocytes with either EGF-alpha or IFN-gamma resulted in an increase susceptibility to photodynamic therapy when 5-aminolevulinic acid was used. This effect was more pronounced in the case of EGF-alpha. Our experiments suggest that activation and differentiation are two important parameters determining susceptibility to photodynamic therapy.

Aminolevulinic Acid↗
PubMed1995

[Photodynamic therapy of small adenocarcinomas with methylene blue].

Photodynamic therapy (PDT) is a new method in the treatment of small/early malignancies. It is based on the interaction of a photosensitiser, light and cellular oxygen. A new therapeutic concept with locally applied 1% of methylene blue into the tumour and subsequent radiation (argon laser pumped dye laser, 665 nm, 100 mW/cm2, 100 J/cm2) was first tested in xeno-transplanted carcinomas and then clinically applied. The animal experiments showed a tumour volume reduction of 1:12, as compared to a control group, two weeks after the first PDT-application. After the second PDT-treatment 6 out of 10 tumours were destroyed. Four carcinomas showed inhibited growth after the treatment. The method was clinically applied in 3 patients with local tumour recurrence in the area of the anastomosis after oesophagus resection. 72 hours after PDT-treatment 4-5 mm tumour necrosis could be proven experimentally. PDT was repeated at the same site within 2 weeks. There were no experimental or clinical complications during or after PDT. The treated tumour areas showed no local tumour growth within 6 months after PDT-treatment.

Adenocarcinoma↗
PubMed1994

Photodynamic therapy of experimental colonic tumours with 5-aminolevulinic-acid-induced endogenous porphyrins.

5-Aminolevulinic acid (5-ALA) is a precursor in the biosynthesis of haem. External application of 5-ALA leads to the formation of protoporphyrin IX, the last intermediate product before haem, which is an effective sensitiser. The 5-ALA-induced endogenous photosensitisation of tumour cells has been exploited for photodynamic therapy (PDT). Experimental human G-3 colonic tumours were transplanted into nude mice, and ten mice were treated by PDT. Ten animals served as controls. We measured a fluorescence intensity of the tumour that was about eight times higher than in the surrounding tissue; a good correlation between the fluorescence intensity and the photodynamic effect was found. Tumour growth was inhibited significantly after PDT, two tumours being destroyed completely after the second PDT treatment. In addition, on-line fluorescence detection during PDT showed a change in the intensity and the fluorescence spectrum of protoporphyrin IX caused by photobleaching and the formation of photoproducts.

Adenocarcinoma↗
PubMed1994

In vitro and in vivo effects of photodynamic therapy in cutaneous T cell lymphoma.

Photodynamic therapy consists of the combination of photosensitizers absorbing light in the visible spectral region and irradiation with light of corresponding wavelengths. We analysed its effects in comparison to PUVA treatment on cell lines MyLA and HuT78, established from patients with cutaneous T cell lymphomas. Proliferation was reduced to 50% by exposure to 7.5 J/cm2 UV-A (= ED50). This effect was increased more than 10-fold in the presence of 10 micrograms/ml 8-methoxypsoralen. The ED50 for photodynamic therapy using 630 nm light emitted by a dye laser and 10 micrograms/ml Photosan-3 was found to be about 1 J/cm2. In vivo fluorescence recordings during topical photodynamic therapy of mycosis fungoides lesions showed photo-bleaching and thus documented the triggering of photochemical reactions. Our observations document the capability of photodynamic therapy to inhibit proliferation of transformed T cells similar to PUVA, pointing out its potential in the treatment of cutaneous T cell lymphomas.

Cell Line↗
PubMed1993

Photodynamic activity of liposome-delivered Cd-texaphyrin using tumor-bearing nude mice.

Photodynamic effects in bladder-tumor bearing nude mice induced by a krypton ion laser (752.5 nm) after i.v. application of liposome-delivered cadmium texaphyrin were investigated. Cd-texaphyrin possesses strong absorption transitions in the far red spectral region (around 760 nm) and a high quantum efficiency of singlet oxygen production. No therapeutic effects were obtained using irradiation 24 hours after administration of the sensitizer, whereas phototreatment 2 hours after application led to significant tumor reduction. This corresponds well with studies on fluorophore-labeled liposomes indicating highest tumor accumulation 1-2 hours after administration. However, the induced cytotoxic effects were lower than those of HpD.

Animals↗
PubMed1993

Solid-phase introduction and intracellular photoinduced reaction of a water-soluble meso-tetracarboxyporphine conjugated to an antisense oligodeoxyribonucleotide.

Oligonucleotide conjugated with water-soluble meso-tetra(4-carboxyphenyl) porphine (TPPC4) has been prepared by a supporting synthesis and novel solid-phase conjugation strategy. The conjugates could be used in dual fashion: i) on formation of iron complex, target DNA could be site-specifically cleaved on incubation with dithiothreitol; ii) on incubation of RR 1022 rat epithelial cell culture with non-metalized oligonucleotide TPPC4 conjugate, cytotoxic effect was detected after irradiation with laser light at 635 nm.

Animals↗
PubMed1993

In vivo photoproduct formation during PDT with ALA-induced endogenous porphyrins.

The administration of 5-aminolevulinic acid (ALA) in tumor-bearing nude mice leads to the formation of the fluorescent, photounstable photosensitizer protoporphyrin IX in tumor tissue. On-line fluorescence spectroscopy during photodynamic therapy (PDT) shows the in vivo formation of chlorintype photoproducts of protoporphyrin. The fluorescence of protoporphyrin as well as its photoproducts is bleached completely at the end of the PDT (100 J cm-2, 630 nm). These findings were also verified using ultrashort laser pulses and time-correlated single-photon counting. A photinduced shortening of the decay times and decrease in the integral fluorescence intensity were measured in vivo due to the photodestruction of the endogenous photosensitizer protoporphyrin IX in the tumor.

Aminolevulinic Acid↗
PubMed1993

Time-resolved in-vivo fluorescence of photosensitizing porphyrins.

Various components of photosensitizing porphyrins (e.g. monomers, aggregates, ionic species) have been recently localized in single cells by time-resolved fluorescence microscopy. Novel time-resolving techniques, based on picosecond laser diodes, a frequency-doubled Nd:YAG laser and time-gated microscopic equipment, were used for in-vivo measurements of the chick chorioallantoic membrane (CAM) exhibiting a pronounced vasculature. Changes of the fluorescence decay kinetics after light exposure were correlated with the formation of a photoproduct (Photosan, aminolaevulinic acid) or changes of the intracellular binding sites (tetraphenyl-porphyrins). Fluorescent components with different decay times were shown to be distributed differently within the tissue.

Allantois↗
PubMed1993

[Photodynamic therapy of skin tumors].

Photodynamic therapy (PDT) is still an experimental modality using red light in conjunction with a systemic or topical photosensitizer. The photosensitizers have a longer retention time in malignant tumors compared with the normal surrounding tissue. Irradiation with a red light at wavelength of 630 nm results in photochemical generation of cytotoxic singulet oxygen. The systemic sensitizer mostly used is hematoporphyrin derivative (HPD) and the light sources are argon-pumped dye lasers, gold vapour lasers and even more simple light sources based on conventional lamps. The most important side effect of systemic application of HPD is light hypersensitivity in the UVA range, which lasts up to several weeks. Multiple studies in recent years have proved that superficial basal cell carcinomas, squamous cell carcinomas, Bowen's disease and epidemic Kaposi's sarcoma respond to systemic PDT. Up to now, however studies with greater numbers of patients and a sufficient follow-up have been lacking. Topical application of sensitizers like amino-levulinic acid (ALA) and tetraphenylporphine sulfonate (TPPS) have been used for the treatment of superficial basal cell carcinomas and squamous cell carcinomas. Possible future applications of PDT are virus papillomas and psoriasis. Even if PDT is an experimental therapeutical modality at present, it may become more clinical relevant in the future.

Basal Cell Carcinoma↗
PubMed1992

Fluorescence formation during photodynamic therapy in the nucleus of cells incubated with cationic and anionic water-soluble photosensitizers.

The variations of fluorescence during light exposure of the cationic sensitizers methylene blue (MB) and meso-tetra(4N-methylpyridyl)porphyrin (T4MPyP) as well as the anionic meso-tetra(4-sulphonatophenyl)porphyrin (TPPS4) were measured at different intracellular sites using video-intensified microscopy in combination with microspectrofluorometry. Before light exposure the sensitizers were localized in distinct parts of the cytoplasm, especially in fluorescent organelles. During irradiation a drastic fluorescence formation and increase in the cytoplasm and nucleus, which was most pronounced in the nucleoli, could be observed for the cationic sensitizers as well as TPPS4. In the case of MB the increase in fluorescence was concomitant with a spectral shift in the emission spectra. For TPPS4 and T4MPyP the formation of a second species with a Soret band shifted towards longer wavelengths was observed and correlated with the fluorescence increase in the nucleoli. Cell deformations also took place.

Animals↗