Genome-wide surveillance of transcription errors in response to genotoxic stress.

Mutagenic compounds are a potent source of human disease. By inducing genetic instability, they can accelerate the evolution of human cancers or lead to the development of genetically inherited diseases. Here, we show that in addition to genetic mutations, mutagens are also a powerful source of transcription errors. These errors arise in dividing and nondividing cells alike, affect every class of transcripts inside cells, and, in certain cases, greatly exceed the number of mutations that arise in the genome. In addition, we reveal the kinetics of transcription errors in response to mutagen exposure and find that DNA repair is required to mitigate transcriptional mutagenesis after exposure. Together, these observations have far-reaching consequences for our understanding of mutagenesis in human aging and disease, and suggest that the impact of DNA damage on human physiology has been greatly underestimated.

Tracking pan-continental trends in environmental contamination using sentinel raptors-what types of samples should we use?

Biomonitoring using birds of prey as sentinel species has been mooted as a way to evaluate the success of European Union directives that are designed to protect people and the environment across Europe from industrial contaminants and pesticides. No such pan-European evaluation currently exists. Coordination of such large scale monitoring would require harmonisation across multiple countries of the types of samples collected and analysed-matrices vary in the ease with which they can be collected and the information they provide. We report the first ever pan-European assessment of which raptor samples are collected across Europe and review their suitability for biomonitoring. Currently, some 182 monitoring programmes across 33 European countries collect a variety of raptor samples, and we discuss the relative merits of each for monitoring current priority and emerging compounds. Of the matrices collected, blood and liver are used most extensively for quantifying trends in recent and longer-term contaminant exposure, respectively. These matrices are potentially the most effective for pan-European biomonitoring but are not so widely and frequently collected as others. We found that failed eggs and feathers are the most widely collected samples. Because of this ubiquity, they may provide the best opportunities for widescale biomonitoring, although neither is suitable for all compounds. We advocate piloting pan-European monitoring of selected priority compounds using these matrices and developing read-across approaches to accommodate any effects that trophic pathway and species differences in accumulation may have on our ability to track environmental trends in contaminants.

Fermentation performance of lactic acid bacteria in different lupin substrates-influence and degradation ability of antinutritives and secondary plant metabolites.

AIMS: The main objectives were to determine the influence of secondary plant metabolites and antinutritives in lupin seeds on the fermentation performance of lactic acid bacteria and to study their ability to degrade these substances. The suitability of lupin raw materials as fermentation substrates was examined. METHODS AND RESULTS: To evaluate the fermentation performance, microbial growth, metabolite formation and substrate uptake in three different lupin substrates was monitored. On the one hand, a lupin protein isolate, which contained only trace amounts of phytochemicals was used in the study. On the other hand, the flour of Lupinus angustifolius cv. Boregine and the flour of the alkaloid rich lupin Lupinus angustifolius cv. Azuro were inoculated with Bifidobacterium animalis subsp. lactis, Pediococcus pentosaceus, Lactobacillus plantarum and Lactococcus lactis subsp. lactis. The micro-organisms showed no significant differences in the fermentation performance on the different lupin flours. Similarly, the growth of most strains on lupin protein isolate was comparable to that on the lupin flours. The fermentation with Bifidobacterium animalis subsp. lactis led to a significant decrease in flatulence causing oligosaccharides. During fermentation with Lactobacillus plantarum the phytic acid content was partially degraded. CONCLUSIONS: Neither the secondary plant metabolites nor the antinutritives of lupin flour inhibited the growth or metabolic activity of the tested micro-organisms. Therefore, lupin flour is suitable for lactic fermentation. Some strains showed the ability to degrade oligosaccharides or phytic acid. SIGNIFICANCE AND IMPACT OF THE STUDY: This work contributes to the fundamental knowledge of the metabolism of lactic acid bacteria during fermentation of lupin substrates. Fermentation of lupin raw materials could be used to improve the nutritional value of the substrates due to the reduction of antinutritives.

Glyphosate, AMPA and glufosinate in soils and earthworms in a French arable landscape.

Although Glyphosate-based herbicides are often marketed as environmentally friendly and easily biodegradable, its bioavailability and risks to wildlife raise significant concerns. Among non-target organisms, earthworms which live in close contact with the soil can be directly exposed to pesticides and harmed. We investigated soil contamination and the exposure of earthworms to glyphosate, its metabolite AMPA, and glufosinate in an arable landscape in France, both in treated (i.e. temporary grasslands and cereal fields under conventional farming), and nontreated habitats (i.e. hedgerows, permanent grasslands and cereal fields under organic farming) (n = 120 sampling sites in total). Glyphosate, AMPA and glufosinate were detected in 88%, 58% and 35% of the soil samples, and in 74%, 38% and 12% of the earthworm samples, respectively. For both glyphosate and AMPA, concentrations in soils were at least 10 times lower than predicted environmental concentrations. However, the maximum glyphosate soil concentration measured (i.e., 0.598 mg kg-1) was only 2 to 3 times lower than the concentrations revealed to affect earthworms (survival and avoidance) in the literature. These compounds were found both in conventional and organic farming fields, thus supporting a recent study, and for the first time they were detected in hedgerows and grasslands. However, glyphosate and AMPA were more frequently detected in soils from cereal fields and hedgerows than in grasslands, and median concentrations measured in soils from cereal fields were significantly higher than in the two other habitats. Bioaccumulation of glyphosate and AMPA in earthworms was higher than expected according to the properties of the molecules. Our findings raised issues about the high occurrence of glyphosate and AMPA in soils from cropped and more natural areas in arable landscapes. They also highlight the potential for transfer of these molecules in terrestrial food webs as earthworms are prey for numerous animals.

Short incubation with methyl aminolevulinate for photodynamic therapy of actinic keratoses.

BACKGROUND: Photodynamic therapy (PDT) using methyl aminolevulinate (MAL) is an effective first-line treatment for actinic keratoses. A reduced incubation period may have practical advantages. OBJECTIVE: This study aims to evaluate the effect of incubation time (1 vs. 3 h), MAL concentration (160 mg/g vs. 80 mg/g) and lesion preparation in the setting of MAL-PDT for treatment of actinic keratosis (AK). DESIGN: Open, randomized, parallel-group multicentre study. SETTING: Outpatient dermatology clinics. SUBJECTS: One hundred and twelve patients with 384 previously untreated AK. Most lesions (87%) were located on the face and scalp and were thin (55%) or moderately thick (34%). METHODS: Lesions were debrided, and MAL cream (160 mg/g or 80 mg/g) was applied before illumination with red light (570-670 nm; light dose, 75 J/cm2). Patients were followed up at 2 and 3 months. Sixty patients (54%) were re-treated and assessed at 6 months. MAIN OUTCOME: Complete lesion response rates 3 and 12 months after last treatment. RESULTS: For lesions on the face/scalp, lesion complete response rates were 78% for thin AK and 74% for moderately thick AK lesions after 1 h vs. 96% and 87% after 3 h incubation with MAL 160 mg/g. Lesion recurrence rates at 12 months after two treatments were similar [19% (3 of 16) with 1 h vs. 17% (3 of 18) with 3 h 160 mg/kg MAL-PDT] and lower than for 80 mg/g MAL-PDT (44-45%). CONCLUSION: MAL-PDT using a 1-h incubation may be sufficient for successful treatment of selected AK lesions.

Protection circuits for ultrasound applications.

A simple input protection circuit for ultrasound pulse-echo applications is described. Its performance is analyzed with regard to other widely used arrangements. Besides the primary function of showing high impedance during the transducer excitation time and a low impedance path to the amplifier in reception, issues of harmonic distortion, insertion losses, bandwidth, power dissipation, transient response, and noise are addressed. It is shown that the proposed circuit has many advantages, operating without any control signals or bias voltages. It is small and can be considered a good general-purpose protection circuit alternative.

Activation of JNK and p38 but not ERK MAP kinases in human skin cells by 5-aminolevulinate-photodynamic therapy.

5-Aminolevulinate (ALA) photodynamic therapy (PDT) is being used clinically for the treatment of skin cancers. ALA is applied as a precursor of porphyrins serving as endogenous photosensitizers. Irradiation of HaCaT cells preincubated with 1 mM ALA for 24 h with red light of 570-750 nm at a dose of 4.5 J/cm2 leads to a 6-fold elevation of cellular c-Jun N-terminal kinase activity; phosphorylation of p38 mitogen-activated protein kinase (MAPK) is enhanced to a similar extent. In contrast, neither activation nor increased phosphorylation of the extracellular stimulus-regulated kinase MAPKs is detected. p38 is also phosphorylated by ALA-PDT in the human melanoma cell lines Bro and SkMel-23, applying doses that lead to 80-95% cell death after 24 h. Hence, the effects of ALA-PDT on MAPKs are similar to stresses like UV irradiation or exposure to hydrogen peroxide with respect to activation of JNK and p38 MAPKs. They are different, however, in that extracellular stimulus-regulated kinase activity is not raised by ALA-PDT. Of the 830 pmol porphyrins/mg protein that were present at 24 h in HaCaT cells, 99 pmol/mg were intracellular. When extracellular porphyrins had been removed by washing, p38 responses were retained. Thus, intracellular porphyrins synthesized from ALA are sufficient to elicit activation of p38 on photosensitization.

Patients with sciatica still experience pain and disability 5 years after surgery: A systematic review with meta-analysis of cohort studies.

BACKGROUND AND OBJECTIVE: The clinical course of patients with sciatica is believed to be favourable, but there is conflicting evidence on the postoperative course of this condition. We aimed to investigate the clinical course of sciatica following surgery. DATABASES AND DATA TREATMENT: An electronic search was conducted on MEDLINE, EMBASE and CINAHL from inception to April 2015. We screened for prospective cohort studies investigating pain or disability outcomes for patients with sciatica treated surgically. Fractional polynomial regression analysis was used to generate pooled means and 95% confidence intervals (CI) of pain and disability up to 5 years after surgery. Estimates of pain and disability (converted to a 0-100 scale) were plotted over time, from inception to last available follow-up time. RESULTS: Forty records (39 cohort studies) were included with a total of 13,883 patients with sciatica. Before surgery, the pooled mean leg pain score was 75.2 (95% CI 68.1-82.4) which reduced to 15.3 (95% CI 8.5-22.1) at 3 months. Patients were never fully recovered in the long-term and pain increased to 21.0 (95% CI 12.5-29.5) at 5 years. The pooled mean disability score before surgery was 55.1 (95% CI 52.3-58.0) and this decreased to 15.5 (95% CI 13.3-17.6) at 3 months, and further reduced to 13.1 (95% CI 10.6-15.5) at 5 years. CONCLUSIONS: Although surgery is followed by a rapid decrease in pain and disability by 3 months, patients still experience mild to moderate pain and disability 5 years after surgery. WHAT DOES THIS REVIEW ADD?: This review provides a quantitative summary of the postoperative course of patients with sciatica. Patients with sciatica experienced a rapid reduction in pain and disability in the first 3 months, but still had mild to moderate symptoms 5 years after surgery. Although no significant differences were found, microdiscectomy showed larger improvements compared to other surgical techniques.

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.

Properties of the satellite RNA of nepoviruses.

Satellite RNA depend for their multiplication on the co-infection of a host cell by a helper virus which can itself multiply independently of the satellite. Four types of satellite RNA have been distinguished on the basis of the size of the RNA and what sort, if any, of protein they encode. One of them, the B-type, comprises relatively large RNA which are messenger RNA for non-structural proteins. Many of these satellites are typified by having nepoviruses as helper viruses. In general, the presence of nepovirus mRNA satellites in a virus culture causes little or no modification to the symptoms of infection by the helper virus and has little effect on its yield. Some satellites appear to be highly specific to a strain of helper virus but others can be helped by heterologous viruses. The proteins encoded by nepovirus mRNA satellites have a M(r) of 38,000 to 48,000 and are relatively basic, in particular in the N-terminal and C-terminal parts of the molecules. However, there is little similarity in amino acid sequence between proteins encoded by different satellites and no peptide motif could be found in all satellite proteins. The results of reverse genetics experiments with satellites suggest that the satellite-encoded protein is essential for the multiplication of the satellite RNA. This system has considerable potential for the study of the mechanisms of replication both of satellite and helper virus RNA.

Aminolevulinic acid: pharmacological profile and clinical indication.

The role of aminolevulinic acid hydrochloride (ALA) in photodynamic therapy (PDT) of in situ neoplasias and tumours of epithelial tumours is steadily increasing and it has been shown to be the drug with most clinical use in PDT. In dermatology, topical PDT with ALA is already postulated to be the treatment of choice for actinic keratoses and superficial basal cell carcinomas. In gastroenterology, pulmonology, uro- and nephrology, neurology and gynaecology ALA has an important role as a photosensitiser not only in the diagnosis of neoplastic tissue but as therapy; first experiences have been made with PDT in these organs. Besides the therapeutic efficacy of this technique, the fluorescence of ALA-induced porphyrins can be effectively used to detect and delineate epithelial and endothelial neoplasms. In dermatology, other indications for ALA-treatment are non-tumoural applications, especially psoriasis, viral-induced diseases, or acne vulgaris. ALA is an effective compound in the diagnosis or therapy of various epithelial and endothelial neoplastic lesions.

Evaluation of c-erbB-2 amplification in breast carcinoma by differential polymerase chain reaction.

Previous studies have found that amplification and overexpression of the c-erbB-2 oncogene in mammary ductal adenocarcinomas predicts decreased disease-free or overall survival. Information regarding the prognostic and pathogenetic significance of oncogene amplification has been limited by difficulty obtaining sufficient quantities of high molecular weight DNA for Southern blot analysis. Differential polymerase chain reaction (PCR) has been suggested as an alternative method for evaluating gene amplification and can be performed using formalin-fixed paraffin-embedded specimens. The authors of this study used differential PCR to detect c-erbB-2 gene amplification and immunohistochemistry to evaluate c-erbB-2 expression. A highly significant degree of concordance (P < .002) between c-erbB-2 amplification and expression was observed. Abnormalities of c-erbB-2 copy number or expression were more common in tumors with higher histologic grade, and trends were noted toward association with other prognostically unfavorable biologic markers, such as reduced progesterone receptor content and DNA aneuploidy.

Tissue culture conditions determine the effects of estrogen and growth factors on the anchorage independent growth of human breast cancer cell lines.

We determined the effects of epidermal growth factor, insulin-like-growth-factor-1 and estradiol on the anchorage independent growth of the estrogen receptor positive human breast cancer cell lines MCF7 and T-47D. In serum free conditions growth factors but not estrogen induced a dose dependent stimulation of growth in both cell lines. The ability of estrogen to induce colony formation of early passage MCF7 cells (less than 100) was strictly correlated to the concentration of sulfatase and charcoal treated calf serum (CCS) with a maximal effect at a concentration of 5% CCS and 10 nM estradiol. CCS alone had no stimulatory effect on the anchorage independent growth of early passage MCF7 cells, but increased colony formation in late passage (greater than 1000) MCF7 and T-47D cells. The growth of late passage MCF7 cells was inhibited by antiestrogen. Thus, the presence of serum components is necessary for the effect of estrogen but not for the effects of growth factors on the anchorage independent growth of estrogen receptor positive human breast cancer cell lines; after a prolonged period of tissue culture serum components switch their function from indirectly modulating estrogen effects to directly stimulating growth in the absence of estrogen.

Intestinal epithelial-mesenchymal cell interactions.

Intestinal morphogenesis, as well as maintenance of the stem cell population and of the steady state between cell proliferation and differentiation, results from controlled cell interactions. There is growing evidence that the mesenchymal cells control epithelial cell behavior via their own expression and induction in the epithelial cells of key regulatory genes. This heterologous cross talk involves basement membrane molecules and paracrine factors. New in vitro/in vivo cellular models allowed us to analyze various mesenchymal cell phenotypes and to show that they exhibit different inductive properties on epithelial cells and that their proliferation and metabolic properties are differentially modulated by cytokines. Finally the epithelial-mesenchymal unit is controlled by hormonal and exogenous factors.

Differential polymerase chain reaction assay of cyclin D1 gene amplification in esophageal carcinoma.

The cyclin D1 gene, located on chromosome 11q13, is frequently rearranged in parathyroid neoplasms and amplified in some carcinomas of other organs. Recent studies have detected amplification of cyclin D1 and other markers on chromosome 11q13 (evaluated by Southern or slot blot assays) in approximately 25-50% of squamous cell carcinomas of the esophagus and noted that amplification was associated with lessened survival time. We applied the technique of differential polymerase chain reaction to the evaluation of cyclin D1 gene amplification in squamous cell carcinomas of the esophagus. Cyclin D1 was found to be amplified in 10 of 45 (22%) primary tumors and three of 12 (25%) lymph node metastases. Lymph node metastases tended to be more common in patients with cyclin D1 amplification (70%) than in those without amplification (37%). In 36 patients with follow-up, cyclin D1 amplification was associated with decreased 1 year survival (28% vs. 59%). Cyclin D1 gene amplification in esophageal carcinomas can be evaluated by differential polymerase chain reaction and may provide useful prognostic information.

Photodynamic therapy in dermatology.

Photodynamic therapy (PDT) uses exogenously administered or endogenously formed photosensitizers activated by light to induce cell death via formation of singlet oxygen and other free radicals. Photodynamic therapy is increasingly used for the treatment of skin cancers and other indications. The efficacy of PDT depends on the structure of the photosensitizer, the administration modality, the light source, and the treatment procedure. We reviewed the most recent clinical and experimental developments in PDT research related to dermatology. The substrate under most intense investigation in PDT research is delta-aminolevulinic acid (ALA). Photodynamic therapy with topically applied ALA has been shown to be highly efficient in the treatment of cutaneous neoplasms by using intralesionally formed porphyrins as photosensitizers. For solar keratoses, best response rates have been described. delta-Aminolevulinic-PDT is also efficient in the treatment of superficial basal cell and squamous cell carcinomas. In addition, the fluorescence of ALA-induced porphyrins under a Wood light is highly selective in neoplastic cutaneous tissue and offers a useful technique in detecting and delineating skin tumors with ill-defined borders.

Intraoperative detection of malignant gliomas by 5-aminolevulinic acid-induced porphyrin fluorescence.

OBJECTIVE: Survival after surgery and radiotherapy for the treatment of malignant gliomas is linked to the completeness of tumor removal. Therefore, methods that permit intraoperative identification of residual tumor tissue may be of benefit. In a preliminary investigation, we have studied the value of fluorescent porphyrins that accumulate in malignant tissue after administration of a precursor (5-aminolevulinic acid) for labeling of malignant gliomas in nine patients. METHODS: Three hours before the induction of anesthesia, 10 mg 5-aminolevulinic acid/kg body weight was administered orally. Intraoperatively, red porphyrin fluorescence was observed with a 455-nm long-pass filter after excitation with violet-blue (375-440 nm) xenon light and was verified by analysis of fluorescence spectra. Fluorescing and nonfluorescing samples taken from the tumor perimeters were examined histologically or used to study the photobleaching of porphyrins by excitation light and white light from the operating microscope. Plasma and erythrocyte porphyrin levels were determined by fluorescence photometry. RESULTS: Normal brain tissue revealed no porphyrin fluorescence, whereas tumor tissue was distinguished by bright red fluorescence. For a total of 89 tissue biopsies, sensitivity was 85% and specificity was 100% for the detection of malignant tissue. For seven of nine patients, visible porphyrin fluorescence led to further resection of the tumor. Under operating light conditions, fluorescence decayed to 36% in 25 minutes for violet-blue light and in 87 minutes for white light. Plasma and erythrocyte porphyrin contents increased slightly, without exceeding normal levels. CONCLUSION: Our observations suggest that 5-aminolevulinic acid-induced porphyrin fluorescence may label malignant gliomas safely and accurately enough to enhance the completeness of tumor removal.

Ex vivo application of delta-aminolevulinic acid induces high and specific porphyrin levels in human skin tumors: possible basis for selective photodynamic therapy.

In photodynamic therapy with topically applied delta-aminolevulinic acid porphyrins are acting as photosensitizers. The profile of porphyrin metabolites in normal or in neoplastic skin after administration of delta-aminolevulinic acid has not been determined in detail yet. Thus, to study porphyrin biosynthesis in human skin an organ culture model was developed. Explant pieces of normal skin, keratoacanthoma, and basal cell carcinoma were incubated with 1 mM delta-aminolevulinic acid for 36 h. Levels of delta-aminolevulinic acid, porphyrins and porphyrin metabolites were measured in tissues and supernatants. After incubation with delta-aminolevulinic acid, higher porphyrin levels were demonstrated in tumors as compared to normal skin. In supernatants, most of formed porphyrins, preferentially highly carboxylated porphyrin metabolites, were measured. The pattern of synthesized porphyrins differed between normal and neoplastic skin explants. In tissues of basal cell carcinomas protoporphyrin was preferentially shown and tissues of keratoacanthomas were characterized by a predominance of coproporphyrin as compared to normal skin. The results show that explant cultures offer an easy approach to examine the porphyrin biosynthesis of various tissues. The tumor-specific delta-aminolevulinic acid metabolism indicates additional porphyrin metabolites such as coproporphyrin apart from protoporphyrin as effective photosensitizers and may offer a novel approach to tumor-selective photodynamic damage.

Preferential relative porphyrin enrichment in solar keratoses upon topical application of delta-aminolevulinic acid methylester.

Topically applied delta-aminolevulinic acid is used efficiently for the treatment of solar keratoses by photodynamic therapy. Recent animal studies suggest that porphyrin sensitization of epithelial tissue is improved by using esters rather than free delta-aminolevulinic acid. The present study examines porphyrin metabolite formation after topical application of delta-aminolevulinic acid or delta-amino-levulinic acid methylester in human solar keratoses versus adjacent normal skin. Level of total porphyrins, porphyrin metabolites and protein were measured in skin samples excised after 1 and 6 h. Higher levels of porphyrins were observed in solar keratoses than in normal skin with both substances. Maximum porphyrin levels were present in solar keratoses treated with delta-aminolevulinic acid for 6 h. However, the ratio of porphyrins in solar keratoses versus adjacent normal skin was higher with delta-aminolevulinic acid methylester. The pattern of porphyrins showed no significant difference between normal and afflicted skin, protoporphyrin being predominant. The results suggest that application of free delta-aminolevulinic acid may be more effective in sensitizing solar keratoses. However, treatment with delta-aminolevulinic acid methylester leads to a preferential enrichment of porphyrins within lesional skin.

Influence of topical photodynamic therapy with 5-aminolevulinic acid on porphyrin metabolism.

Photodynamic therapy (PDT) with topically applied 5-aminolaevulinic acid (5-ALA) is increasingly used for treating tumours. The efficacy of topical PDT is limited to superficial and initial tumours. The topically applied doses of 5-ALA vary from 0.02 to 7.0 g per session according to the type of lesion. There are no studies on the influence of topically applied 5-ALA on the systemic accumulation of porphyrins or porphyrin precursors. A group of 20 patients with actinic keratoses (AK) and basal cell carcinomas (BCC) were treated by topical PDT with 5-ALA. Prior to and 6 and 24 h after PDT, 5-ALA and total porphyrin concentrations were determined in red blood cells and plasma, respectively. In addition, before and after 5-ALA treatment, 24-h urine samples were collected and porphyrins and porphyrin precursors were measured. There was no significant alteration in porphyrin metabolism. In some patients, a slight but insignificant increase in erythrocyte and plasma porphyrins was found 6 h after 5-ALA PDT. This investigation confirms clearly the safety of this treatment modality and demonstrates that 5-ALA application (up to 7 g) in the course of PDT has no influence on the concentrations of porphyrins and porphyrin precursors measured in various compartments.