PubMed Health⌕ Search

Biomedical subjects

C Abels

Publications and source records attributed to C Abels.

At least 37 records · Page 2Linked to original sources
PubMed1999

Epidermodysplasia verruciformis treated using topical 5-aminolaevulinic acid photodynamic therapy.

We describe a 65-year-old woman who had had wart-like lesions on the hands, lower arms and forehead for about 45 years. She had already had several basal cell carcinomas excised. Histological study, electron microscopy and in situ hybridization [human papilloma virus (HPV)-types 5/8/12/14/19-23/25/36] of skin biopsies confirmed a diagnosis of epidermodysplasia verruciformis (EV). Photodynamic therapy (PDT) was performed using a 20% 5-aminolaevulinic acid ointment applied for 6 h to the lesions and irradiating using an incoherent light source (lambda = 580-740 nm, 160 mW/cm2, 160 J/cm2). Following PDT, blistering and crusting of the lesions occurred, but these healed completely within 2-3 weeks without scarring, and the cosmetic result was excellent. Six months after PDT a skin biopsy was taken. In situ hybridization was positive for HPV type 8 in skin which was clinically and histologically normal. Twelve months after PDT a few lesions had recurred on the hands. Although permanent cure of EV cannot be achieved by any therapy at present and single lesions continue to appear in this patient, topical PDT might result in better control of HPV-induced lesions.

Administration, Topical↗
PubMed1999

Active and higher intracellular uptake of 5-aminolevulinic acid in tumors may be inhibited by glycine.

Topical 5-aminolevulinic acid is used for the fluorescence-based diagnosis and photodynamic treatment of superficial precancerous and cancerous lesions of the skin. Thus, we investigated the kinetics of 5-aminolevulinic acid-induced fluorescence and the mechanisms responsible for the selective formation of porphyrins in tumors in vivo. Using amelanotic melanomas (A-Mel-3) grown in dorsal skinfold chambers of Syrian golden hamsters fluorescence kinetics were measured up to 24 h after topical application of 5-aminolevulinic acid (1%, 3%, or 10%) for 1 h, 4 h, or 8 h by intravital microscopy (n = 54). Maximal fluorescence intensity in tumors after 1 h application (3% 5-aminolevulinic acid) occurred 150 min and after 4 h application (3% 5-aminolevulinic acid) directly thereafter. Increasing either concentration of 5-aminolevulinic acid or application time did not yield a higher fluorescence intensity. The selectivity of the fluorescence in tumors decreased with increasing application time. Fluorescence spectra indicated the formation of protoporphyrin IX (3% 5-aminolevulinic acid, 4 h; n = 3). The simultaneous application of 5-aminolevulinic acid (3%, 4 h) and glycine (20 microM or 200 microM; n = 10) reduced fluorescence in tumor and surrounding host tissue significantly. In contrast, neither decreasing iron concentration by desferrioxamine (1% and 3%; n = 10) nor inducing tetrapyrrole accumulation using 1, 10-phenanthroline (7.5 mM; n = 5) increased fluorescence in tumors. The saturation and faster increase of fluorescence in the tumor together with a reduction of fluorescence by the application of glycine suggests an active and higher intracellular uptake of 5-aminolevulinic acid in tumor as compared with the surrounding tissue. Shorter application (1 h) yields a better contrast between tumor and surrounding tissue for fluorescence diagnosis. The additional topical application of modifiers of the heme biosynthesis, desferrioxamine or 1,10-phenanthroline, however, is unlikely to enhance the efficacy of topical 5-aminolevulinic acid-photodynamic therapy at least in our model.

Aminolevulinic Acid↗
PubMed1998

Pharmacokinetics and selectivity of aminolevulinic acid-induced porphyrin synthesis in patients with cervical intra-epithelial neoplasia.

Photodynamic therapy (PDT), due to its tumor selectivity, represents an alternative approach to diagnose and treat cervical intra-epithelial neoplasia (CIN) without altering normal surrounding tissue. Our aim was to investigate the pharmacokinetics and the selectivity of 5-aminolevulinic acid (5-ALA)-induced porphyrin fluorescence after topical administration, to obtain basic clinical data for future diagnostic fluorescence imaging and PDT protocols for CIN. Twenty-eight non-pregnant women with a cytological diagnosis of low-grade or high-grade squamous intra-epithelial lesions were included. An aqueous solution containing 3% 5-ALA was topically applied 1 to 6 hrs prior to conization using a cervical cap. After excision, porphyrin-induced fluorescence was quantified in dysplastic (n = 14) and normal epithelium (n = 28) by means of quantitative fluorescence microscopy. High values of porphyrin fluorescence were found in squamous epithelium between 150 and 450 min, with a maximum at 300 min following administration of 5-ALA. Ratios of porphyrin fluorescence of dysplastic vs. surrounding normal epithelium were 1.3 and 1.21 for CIN 1 (n = 3) and CIN 2 (n = 3), respectively. In CIN 3 patients (n = 8), this ratio was 2.35; the best selectivity of 5-ALA-induced porphyrin fluorescence in CIN 3 lesions (ratio 3) was observed with a topical administration time of between 150 and 250 min. Our results demonstrate that patients with CIN 3 show higher 5-ALA-induced fluorescence compared with normal epithelium. The optimal administration time of topically applied 5-ALA was between 3 and 4 hr. Our data suggest that topical ALA-PDT and photodynamic diagnosis might be suitable for detecting CIN.

Adult↗
PubMed1998

Simulations on the selectivity of 5-aminolaevulinic acid-induced fluorescence in vivo.

The knowledge of the exact time course of a photosensitizer in tumour and surrounding host tissue is fundamental for effective photodynamic therapy (PDT) and fluorescence-based diagnosis. In this study the time course of porphyrin fluorescence following topical application of 5-aminolaevulinic acid (ALA) using different formulations, concentrations and incubation times has been measured in amelanotic melanomas (A-Mel-3) (n = 54) grown in transparent dorsal skinfold chambers of Syrian golden hamsters and in human basal cell carcinomas (BCCs) (n = 40) in vivo. To simulate the accumulation of ALA-induced protoporphyrin IX (Pp IX), a three-compartment model has been developed and rate constants have been determined. The kinetics of both the A-Mel-3 tumours and the BCCs show a significantly higher fluorescence intensity in tumour as compared to normal surrounding host tissue. Maximal fluorescence intensity in A-Mel-3 tumours as a percentage of the reference standard used occurs 150 min post incubation (p.i.) using a 1, 3 or 10% (vol.) ALA solution buffered to pH 7.4 and 1 h incubation time. After a 4 h incubation time maximal fluorescence intensity in tumour is measured shortly p.i. A concentration of 10% ALA does not increase the fluorescence intensity as compared to 3% ALA following 4 h incubation, but either 3 or 10% ALA yields a significantly higher fluorescence after 4 h incubation time as compared to 1 h. The fluorescence intensity following an 8 h incubation reaches its maximum directly p.i. for all concentrations and then decreases exponentially. The fluorescence intensity in the surrounding host tissue shows no statistically significant difference regarding concentration or incubation time. At least during the first hour p.i., the fluorescence intensity measured in the surrounding tissue is lower as compared to that in the tumour in all groups. 24 h after topical application hardly any fluorescence is detectable in tumour or surrounding host tissue in all experimental groups. Incubating human BCCs with a 20% ALA cream (water-in-oil emulsion) or a 20% ALA gel (containing 40% dimethyl sulfoxide) for approximately 2 h yields a similar fluorescence intensity directly after incubation for either cream or gel. However, while yielding a maximum 120 min p.i. with cream, the fluorescence intensity increases for a longer time (about 2-3 h p.i.) and up to higher values using the gel formulation. In surrounding normal skin, cream as well as gel formulation yields a similar fluorescence intensity directly after incubation. Afterwards the fluorescence intensity decreases slowly using the cream whereas a further increase of the fluorescence intensity is measured in the normal skin with a maximum 240 min p.i. using the gel formulation. The results of the proposed three-compartment model indicate that the observed selectivity of accumulated porphyrins following topical application of ALA is mainly governed by an increased ALA penetration of the stratum corneum of the skin, an accelerated ALA uptake into the cell and a higher porphyrin formation in tumour as compared to normal skin tissue, but not by a reduced ferrocheletase activity.

Aminolevulinic Acid↗
PubMed1998

Photostability and thermal stability of indocyanine green.

The photo-fading of the S0-S1 absorption band of the infrared dye indocyanine green sodium iodide (ICG-NaI) has been studied by cw laser excitation to the S1 band. Monomeric solutions in water, heavy water, aqueous sodium azide, human plasma, methanol and dimethyl sulfoxide (DMSO) as well as J-aggregated solutions in H2O and D2O have been investigated. A leucoform of indocyanine green seems to be formed by photodegradation. The degradation slows down with exposure time. The initial degradation yield, phi D,0, is determined. In monomeric and dimeric water, heavy water and sodium azide solutions the initial photostability is of the order of phi D.0 approximately 10(-3), in the organic solvents methanol and DMSO it is of the order of phi D.0 approximately 10(-5), and in human plasma it is phi D.0 approximately 2 x 10(-6). J-aggregates at high concentration are very stable. The thermal stability of the ICG-NaI solutions at room temperature in the dark is compared with their photostability. The thermal degradation time of monomeric and dimeric ICG-NaI in water, heavy water and sodium azide solutions is t(th) approximately 10 days, while no thermal degradation is observed for ICG-NaI J-aggregates and ICG-NaI in methanol, DMSO and human plasma.

Coloring Agents↗
PubMed1998

Indocyanine green and laser light for the treatment of AIDS-associated cutaneous Kaposi's sarcoma.

Indocyanine green (ICG) is clinically approved for the determination of liver function, cardiac output and plasma volume. In this pilot study, ICG was used as photosensitizer in combination with a diode laser to treat AIDS-associated Kaposi's sarcoma (KS) in three patients. Directly and up to 50 min after intravenous administration of ICG (2-4 mg kg(-1) body weight), KS (n=57), mainly plaque-type, were irradiated using a diode laser (lambda em=805 nm, 100 J cm[-2], 0.5-5 W cm[-2]) matching the absorption maximum. Complete remission of KS (n=16) was achieved when irradiated 1-30 min after injection of the second dose of ICG (2 x 2 mg kg(-1) b.w., 30 min apart) with 3-5 W cm(-2) and 100 J cm(-2). Biopsies (n=3) revealed necrosis of the tumour 24 h and complete remission 4 weeks after therapy. In general, systemic side-effects were not observed and cosmetic results were very good. However, hyperpigmentation occurred temporarily in lesions located on the lower extremities. These findings show that AIDS-associated KS can be effectively treated after photosensitization with ICG and subsequent irradiation with an appropriate diode laser. However, additional investigations need to elucidate the exact mechanism of action of ICG-mediated phototherapy and have to show the efficacy for the treatment of other highly vascularized solid tumours.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Impact of dextran on microvascular disturbances and tissue injury following ischemia/reperfusion in striated muscle.

The aim of this study was to evaluate the effect of dextran (Dx) 1 versus Dx 60 (molecular weights 1,000 and 60,000) on microvascular disturbances and tissue injury in striated muscle after ischemia/reperfusion (I/R). Experiments were performed using a 4 h pressure-induced ischemia model in the hamster dorsal skinfold chamber. Three groups (n=6) of animals received a continuous infusion (45 min, 3 microL/min) of either Dx 1 or Dx 60 (total dose 5 mg/kg) or saline solution beginning 15 min before reperfusion. Intravital fluorescence microscopy allowed for quantification of functional capillary density, leukocyte adherence, extravasation of fluorescein isothiocyanate-Dx, and nonviable (propidium-positive) cell count before ischemia and .5, 2, and 24 h after reperfusion. Experiments were terminated with tissue preservation for electron microscopy. Postischemic functional capillary density was significantly improved by Dx 60 (at 24 h, 88% vs. 51% in controls). In animals receiving postischemic Dx 1 or Dx 60, leukocyte adherence was significantly reduced (at .5 h, 44% and 58%, respectively) as compared with controls, whereas macromolecular extravasation was unchanged. Nonviable cell count was significantly decreased by both Dx fractions (at 24 h, Dx 1, 75%; Dx 60, 87%), indicating a reduction of tissue injury, which was also confirmed by electron microscopy. These results provide evidence that Dx 60 at 5 mg/kg attenuates I/R injury more effectively than Dx 1. Leukocytes play a major role in the development of I/R injury, but macromolecular extravasation does not always correlate with the leukocyte-endothelium interaction and the manifestation of I/R injury.

Animals↗
PubMed1997

[Photochemotherapy with indocyanine green in cutaneous metastases of rectal carcinoma].

HISTORY AND ADMISSION FINDINGS: Six weeks before admission of a 47-year-old man with known rectal carcinoma, small nodular metastases had occurred over the front of both his thighs. Examination showed many aggregatet cuti-color or livid nodes, diameter 0.5 cm. The patient's poor general condition excluded the usual palliative measures. TREATMENT AND COURSE: Photochemotherapy of the skin metastases with indocyanine green (ICG; absorption maximum 805 nm), a non-toxic dye approved for diagnostic purposes, was undertaken on a trial basis. The dye, being bound to plasma proteins, is retained in the intravacular space. Immediately after administration of the dye (2.5 mg/kg intravenously) the skin metastases were irradiated by diode laser (lambda = 805 nm, 100 J/cm2, 3 W/cm2, radiation diameter 2 cm). This necrosed the metastases and clinically as well as histologically resulted in their complete disappearance with scarring of the treated area. CONCLUSION: This case illustrates the effectiveness of photochemotherapy with ICG against solid skin tumours of increased microvascular density.

Humans↗
PubMed1997

Topical application of a first porphycene dye for photodynamic therapy--penetration studies in human perilesional skin and basal cell carcinoma.

Photodynamic therapy (PDT) in dermatology has been proven to be a successful noninvasive therapeutic modality for treating skin cancer. To facilitate its clinical introduction, the development of topical photosensitizers is necessary to avoid generalized, cutaneous photosensitivity. Therefore the penetration of synthetic chemically pure 9-acetoxy-2,7,12,17-tetrakis-(beta-methoxyethyl)-porphycene (ATMPn) into human skin was studied. Single specimens of freshly excised perilesional skin (n = 70) and basal cell carcinomas (n = 28) were evaluated after topical application of ethanolic ATMPn solutions (0.1% and 0.05%) for various times (2, 6, 16, 20 h). The penetration depth of ATMPn, recognized as red fluorescence in cryostat sections, was determined qualitatively by fluorescence imaging using a system of scoring related to the morphological structure of human skin (0 no fluorescence, 5 fluorescence deeper than basement membrane). Perilesional skin incubated for 2 or 6 h revealed fluorescence restricted to the upper parts of the epidermis, while after 16 or 20 h of incubation fluorescence was detected down to the basement membrane resulting in a significantly higher score (mean sum of scores : 2 h 2.6 +/- 0.4; 6 h 3.2 +/- 0.1; 16 h 3.8 +/- 0.1; 20 h 3.6 +/- 0.1). Quantitative evaluation by digital image analysis confirmed the qualitative results. Fluorescence was limited to the epidermis and the fluorescence intensity of the epidermis was higher after 16 h (4.9% of the fluorescence standard) than after 6 h (4.1%) incubation. Basal cell carcinomas showed fluorescence in the deep dermis as early as after 6 h incubation, but restricted to tumour cell nests. These results suggest that penetration of ATMPn into tumour tissue after topical application might be sufficient for topical PDT and that poor penetration into surrounding tissue might prevent scar formation following irradiation for PDT. The penetration characteristics of ATMPn now have to be proven in an in vivo setting.

Administration, Topical↗
PubMed1997

Indocyanine green: intracellular uptake and phototherapeutic effects in vitro.

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.

Antineoplastic Agents↗
PubMed1997

Photodynamic therapy with 5-aminolaevulinic acid-induced porphyrins of an amelanotic melanoma in vivo.

Of particular interest for photodynamic therapy (PDT) are the endogenously formed and photodynamically active porphyrins produced following topical or systemic application of 65-aminolaevulinic acid (ALA), a haem precursor. Having determined the pharmacokinetics and wavelength dependence of PDT with ALA-induced porphyrins, we analysed the porphyrin metabolites in tumour and surrounding skin. The therapeutic efficacy of PDT using ALA-induced porphyrins was investigated. Amelanotic melanomas (A-Mel-3) were implanted subcutaneously in the back of Syrian golden hamsters (body weight (b.w.), 70-80 g). After 5-7 days, tumours with a volume of approximately 150 mm3 were used for PDT (n = 36). ALA (500 mg kg-1 b.w., pH 6.5) was injected intravenously 45, 90, 150 and 300 min before light irradiation (635 nm, 100 mW cm-2, 100 J cm-2). Tumours with light irradiation only served as controls. The tumour volume was measured after PDT for 28 days. The total porphyrin content was determined in the tumours, the surrounding skin and erythrocytes prior to and 45, 90, 180, 240, 300 and 480 min and 24 h following intravenous injection of ALA (500 mg kg-1 b.w.; n = 32). Porphyrin metabolites were separated by high pressure liquid chromatography (HPLC). Tumour growth was significantly delayed when PDT with ALA was performed 45, 90 or 150 min following intravenous administration. At that time, protoporphyrin (1.8 +/- 0.4 nmol g-1), coproporphyrin (2.2 +/- 0.5 nmol g-1) and uroporphyrin (1.7 +/- 1.4 nmol g-1) were the main metabolites in the tumour tissue. Erythrocytes also contained significant amounts of porphyrins (11.8 +/- 1.3 nmol g-1). The tumour and surrounding skin exhibited a different pattern of porphyrin metabolites. Unexpectedly, a single treatment of PDT with ALA-induced porphyrin resulted in only one complete remission out of six amelanotic melanomas when the final therapeutic outcome was assessed after 28 days. The therapeutic efficacy of PDT with ALA-induced porphyrins can be positively correlated with the fluorescence kinetics previously determined. The analysis of the porphyrin metabolites in amelanotic melanoma by HPLC indicates that the porphyrin accumulation is not due to a decreased activity of ferrochelatase. Moreover, the photodynamic effects may not be mediated solely by porphyrins localized in the tumour parenchyma, but also by significant amounts of porphyrins in the microvasculature. PDT with this endogenous photosensitizer failed to induce complete emission of the treated tumours despite irradiation at the time of maximum porphyrin concentration using the optimum therapeutic wavelength. Thus PDT with ALA-induced porphyrins is less effective in our model relative to that observed for the exogenous photosensitizer Photofrin or synthetic porphycenes after a single treatment.

Aminolevulinic Acid↗
PubMed1997

Targeting of the tumor microcirculation by photodynamic therapy with a synthetic porphycene.

9-acetoxy-2,7,12,17-tetrakis-(beta-methoxyethyl)-porphycene (ATMPn) is a chemically pure substance with fast pharmacokinetics and superior photodynamic properties in vitro as compared to Photofrin. In this study the pharmacokinetics, photodynamic efficacy and tissue localization of ATMPn were investigated in vivo. Amelanotic melanomas (A-Mel-3) were implanted in dorsal skin fold chambers fitted to Syrian Golden hamsters. Fluorescence kinetics of ATMPn (1.4 mumol kg-1 b.w.i.v.; n = 8) were monitored by intravital microscopy. Quantitative measurements of fluorescence intensity were carried out by digital image analysis. For tumor growth studies 1.4 mumol kg-1 was injected 24 h (n = 3), 3 h (n = 3), 1 min (n = 6) and 2.8 mumol kg-1 1 min (n = 6) before PDT (Laser (630 nm) or lamp (600-750 nm), 100 mW cm-2, 100 J cm-2). Tumor volume was measured for 28 d. Solid tumors (n = 3) were excised 1 min after injection of ATMPn (2.8 mumol kg-1) and cryostat sections (20 mm) were analyzed by confocal laser scanning microscopy (CLSM) for tissue localization of the dye. Maximal fluorescence (mean +/- S.E.) arose in the tumor (94 +/- 7%) and surrounding host tissue (67 +/- 5%) 30 s post injection followed by a rapid decrease. Hardly any fluorescence was detectable 12 h after administration. Only PDT 1 min after injection of ATMPn was effective yielding 3/6 complete remissions (2.8 mmol kg-1, laser) and 6/6 complete remissions (2.8 mumol kg-1, lamp), respectively. One minute after injection the dye is primarily localized in the vascular wall of normal and tumor vessels as shown by CLSM. PDT at a time, when the dye is localized primarily in the tumor microcirculation, exhibits the best tumor killing effects showing that vascular targeting is effective in treating solid malignant tumors. ATMPn in liposomes makes administration and light irradiation in one session possible due to its fast pharmacokinetics. Thus, using ATMPn as a photosensitizer may provide more flexibility to perform PDT after surgical exploration and debulking as adjuvant therapy.

Animals↗
PubMed1997

Influence of a haematoporphyrin derivative on the protoporphyrin IX synthesis and photodynamic effect after 5-aminolaevulinic acid sensitization in human colon carcinoma cells.

Haematoporphyrin derivatives (HPDs) are potent sensitizers in photodynamic therapy (PDT), associated with prolonged skin photosensitivity. 5-Aminolaevulinic acid (5-ALA), a natural precusor of haem, is converted intracellularly into the photosensitive agent protoporphyrin IX (PPIX), causing direct cytotoxicity after laser light irradiation but limited skin photosensitivity over 1-2 days and higher tumour selectivity. Unfortunately, the use of 5-ALA in PDT has been shown to cause only superficial tissue necrosis. Therefore, a combination of HPD and 5-ALA could be of great clinical value in the treatment of tumours if a synergistic effect of both sensitizers on tumour cell necrosis with less skin photosensitivity could be demonstrated. Human colon adenocarcinoma cells (HT-29) were cultured with either HPD or 5-ALA alone, simultaneously for 24 h with 5-ALA and HPD or in succession with 5-ALA (18 h) followed by HPD (6 h at different concentrations. Intracellular PPIX concentrations were determined by high-performance thin-layer chromatography. Furthermore, PDT was performed with an incoherent light source (lambda = 580-740 nm) using a light dose of 30 J cm(-2) and an output power of 40 mW cm(-2). The intracellular PPIX concentration correlated well with 5-ALA drug dose and incubation time and was highest after single 5-ALA sensitization. In the presence of HPD, either simultaneously or sequentially, PPIX decreased significantly. The PDT effect after simultaneous incubation with both sensitizers for 24 h was not superior to incubation with HPD alone. If 5-ALA incubation (18 h) was followed by HPD (6 h) cytotoxicity after PDT was higher than with either single drug. 5-ALA (80 microg ml(-1)) led to a decrease in tumour cell viability by 40%. A similar effect could be observed when 5-ALA and HPD were sequentially combined allowing for a reduction of the 5-ALA dose from 80 microg ml(-1) in the absence of HPD to 60 microg ml(-1) and 5 microg ml(-1) together with 0.5 microg ml(-1) and 2 microg ml(-1) HPD respectively. We speculate that the enhanced PDT effect after the combined administration of 5-ALA and HPD to cultures of colon carcinoma cells should be even more impressive in the tumour in vivo, since HPD primarily targets the tumour microvasculature and secondarily tumour cells.

Aminolevulinic Acid↗
PubMed1997

Porphyrins preferentially accumulate in a melanoma following intravenous injection of 5-aminolevulinic acid.

Systemically, as opposed to topically, administered 5-aminolevulinic acid (ALA) is of increasing interest for photodynamic therapy (PDT) because of more selective and more homogeneous accumulation of porphyrins in neoplastic tissues. This study investigates the profile and the time course of porphyrin metabolites in various tissues following intravenous injection of ALA (0.5 g/kg body weight) into hamsters bearing an amelanotic melanoma (A-Mel-3). ALA injection led to maximum levels of ALA and porphyrins in erythrocytes after 45 min. In tissues, maximum porphyrin levels were detected after 45 min (tumor), 4 h (skin, kidney), and 24 h (liver). Sixfold higher porphyrin levels were observed in tumors as compared to surrounding normal skin at 45 min. Predominant porphyrin metabolites were protoporphyrin (tumor, skin, liver, kidney), coproporphyrin (tumor) and highly carboxylated porphyrins (tumor, skin, kidney). These data suggest optimum efficacy of light irradiation in systemic PDT with ALA within the first two hours after injection. Tumor-specific ALA metabolism yields protoporphyrin and coproporphyrin as the prevailing porphyrin metabolites.

Aminolevulinic Acid↗
PubMed1996

9-Acetoxy-2,7,12,17-tetrakis-(beta-methoxyethyl)-porphycene (ATMPn), a novel photosensitizer for photodynamic therapy: uptake kinetics and intracellular localization.

The optimal photosensitizer for topical or systemic photodynamic therapy (PDT) has not yet been found. A promising new second-generation sensitizer is 9-acetoxy-2,7,12,17-tetrakis-(beta-methoxyethyl)-porphycene (ATMPn) whose time- and temperature-dependent uptake and intracellular localization were investigated in two human-skin-derived cell lines (HaCaT keratinocytes and dermal fibroblasts). Flow cytometry analysis (0-800 s) revealed an immediate increase in fluorescence in the cells after start of incubation with 100 ng ml-1 ATMPn (in cell culture medium). At longer incubation periods (0-24 h) a constant increase in fluorescence up to 12 h, with a steady state up to 24 h, was observed. Keratinocyte showed a faster rate of ATMPn uptake than fibroblasts within the first 12 h. Temperature-dependent ATMPn uptake was measured at 4 and 37 degrees C. An increase in fluorescence was observed even at 4 degrees C, suggesting that cellular uptake of ATMPn is partially based on passive diffusion. Confocal laser scan miscroscopy showed spotty, granular fluorescence inside the cytoplasm after incubation with ATMPn, similar to the pattern of rhodamine 123 which stains mitochondria. These results demonstrated an unusually fast intracellular, probably intramitochondrial, uptake of ATMPn in vitro. Therefore the use of ATMPn in photodynamic therapy might allow a reduction of the time span between administration of drug and irradiation.

Cell Line↗
PubMed1995

Effects of photodynamic therapy on leucocyte-endothelium interaction: differences between normal and tumour tissue.

An inflammatory reaction is regularly noticed in irradiated tissues following photodynamic therapy (PDT). This observation is potentially associated with leucocyte-mediated tissue damage, which might further contribute to the tumoricidal effect of this therapy. The objective of our study was to investigate the effects of PDT on leucocyte-endothelium interaction in the microvasculature of tumours and normal tissue. Experiments were performed in the dorsal skinfold chamber preparation of Syrian golden hamsters bearing amelanotic melanoma A-Mel-3. The photosensitiser. Photofrin (5 mg kg-1 i.v.) was injected 24 h before laser irradiation (630 nm, 100 mW cm-2, 10 J cm-2 or 100 J cm-2). Post-capillary confluent venules (diameter 15-40 microns) of subcutaneous (s.c.) tissue or the amelanotic melanoma A-Mel-3 were observed by intravital microscopy before, 5, 30, 60 and 180 min after laser irradiation and recorded for off-line analysis. Before treatment, the number of adherent leucocytes in tumour vessels was only 22% of the number observed in vessels of s.c. tissue (P < 0.01). The maximum increase in adhering leucocytes was observed in post-capillary venules of s.c. tissue 1 h after PDT (P < 0.01). In contrast, enhanced leucocyte-endothelium interaction was missing in tumour vessels and in control groups. These results indicate that the tumour destruction observed after PDT is not mediated by leucocyte-endothelium interaction in the tumour. Induction of leucocyte adhesion in the PDT-treated normal tissue suggests a contribution to the peritumoral inflammatory response. Different maturational status or biochemical properties of tumour microvascular endothelium may explain the lack of leucocyte adherence upon PDT.

Animals↗
PubMed1995

Wavelength dependency of photodynamic effects after sensitization with 5-aminolevulinic acid in vitro and in vivo.

A promising new therapeutic modality for skin cancer, administration of the heme precursor 5-aminolevulinic acid followed by light irradiation, is known as photodynamic therapy. Photofrin, the only clinically approved sensitizer, has an absorption maximum at 630 nm, the wavelength used in most experimental and clinical trials with 5-aminolevulinic acid. We investigated photodynamic efficacy of irradiation with coherent light at wavelengths ranging from 622 to 649 nm in vitro and in vivo as well as the content and distribution of intracellular porphyrin after administration of 5-aminolevulinic acid. HaCaT immortalized human keratinocytes were sensitized with 30 micrograms/ml 5-aminolevulinic acid for 24 h in vitro. By cell viability determined with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, the best cell-killing effects were observed after irradiation at 635 nm. Using an amelanotic melanoma (A-Mel-3) grown subcutaneously in Syrian Golden hamsters, we confirmed these results in vivo: tumor growth was markedly delayed in animals treated with 100 mg/kg 5-aminolevulinic acid intravenously and irradiated with coherent light at 635 nm as compared to animals irradiated at 630 nm. This photodynamic effect is probably mediated by large amounts of the photosensitizing porphyrin, protoporphyrin IX, localized in cell membranes as visualized by confocal laser scan microscopy and as determined by high pressure liquid chromatography in vitro. The results suggest that irradiation at 635 nm with a coherent light source is more effective than irradiation at 630 nm for photodynamic therapy with 5-aminolevulinic acid.

Aminolevulinic Acid↗