ALA induced photodynamic effects on gram positive and negative bacteria

In the present study we examined the production of high amounts of porphyrins upon induction by delta-aminolevulinic acid (ALA) in 9 bacterial strains. This was performed by solely inducing the porphyrin biosynthesis pathway. Four of the strains were Gram positive bacteria and five were Gram negative strains. All strains, except Streptococcus faecalis, produced porphyrins when incubated in PBS with 0.38 mM ALA for 4 h. Excess porphyrin production was excreted to the medium. Gram positive bacteria exhibited fluorescent emission peaks at 622 nm for the endogenous and 617 nm for the excreted porphyrins. Gram negative bacteria exhibited a 630 nm emission peak for the endogenous and a 615 nm emission peak for the excreted extracellular porphyrins. Upon illumination of the ALA induced Staphylococcal strains with 407-420 nm blue light, a decrease of five orders of magnitude was demonstrated with a light dose of 50 J cm(-2). Total eradication of the Staphylococcal strains could be achieved with a 100 J cm(-2) dose, which resulted in a decrease in viability of seven orders of magnitude. The viability of all the induced Gram negative strains and B. cereus decreased by one or two orders of magnitude upon illumination with 50 and 100 J cm(-2), respectively. This difference in the photoinactivation rate was found to be due to the distribution and amounts of the various porphyrins in the bacterial strains. The predominant porphyrin in the Staphylococcal strains was coproporphyrin (68.3-74.6%). In the Gram negative strains there was no predominant porphyrin and the porphyrins found were mostly 5-carboxyporphyrin, uroporphyrin, 7- carboxyporphyrin, coproporphyrin and protoporphyrin. In the B. cereus(Gram positive) strain the predominant porphyrin was uroporphyrin (75.8%). Although the total production of porphyrins in the Gram negative bacteria was higher than in the Staphylococcal strains, the amount of coproporphyrin produced by the latter was twice to three times higher than in the Gram negative strains. The extracellular excreted porphyrins did not contribute to the photoinactivation in any of the tested strains. Significant decreases in the Na(+) and K(+) content were detected in induced S. aureus after illumination while only small changes were observed in E. coli B. The green fluorescent protein within the cytoplasm of induced E. coli strains was only partially disrupted (by 60% only). These results indicate a partial yield of the effects generated by (1)O(2) radicals resulting from the photoinactivation of Gram negative bacteria and a successful generation of the same effects in the Staphylococcal strains.

Mechanistic aspects of Escherichia coli photodynamic inactivation by cationic tetra-meso(N-methylpyridyl)porphine

The mechanistic aspects of Escherichia coli photodynamic inactivation (PDI) have been studied in bacteria expressing the reporter protein GFP, following transfection with wild type pGFP plasmid and treatment with the hydrophilic cationic sensitizer tetra-meso(N-methyl-4-pyridyl)porphine tetratosylate (TMPyP). Cell survival and morphology during PDI were correlated with plasmid-GFP degradation in comparison to DNA and RNA strand-breaks, while photobleaching of the GFP chromophore was used to monitor protein photodamage. Singlet oxygen generated upon TMPyP photoactivation interacted with target nucleic acid polymers in a drug-and light-dose dependent manner. The hierarchy and cascade of the photodamage was in the order: genomic-DNA > total RNA > plasmid-DNA, as revealed by specific extraction and agarose electrophoresis. The notable resistance of the plasmid DNA in comparison to genomic DNA has implications for PDI of antibiotic-resistant bacteria. Re-growth of the treated cells in fresh medium showed structural features of an SOS response. Under these conditions, DNA repair machinery was initiated by typical alignment of DNA-protein co-aggregates accompanied by lateral assembly of ribosomes, apart from damaged DNA-arrays, as depicted by electron microscopy. GFP-TMPyP interactions were demonstrated by double green and red fluorescence on electrophoresis plates analyzed by spectral imaging. Photobleaching measurements revealed specific GFP photodamage directly related to PDI of the E. coli. The kinetics of both the GFP photobleaching and the K(+) efflux, representing photodamage to cytosolic proteins and membrane damage, respectively, were found to be similar. The survival curves were correlated to chromosomal degradation and ultrastructural damage. We conclude that TMPyP-dependent PDI of E. coli is primarily dependent on genomic DNA photodamage rather than on protein or membrane malfunctions.

A porphobilinogen deaminase (PBGD) Ran-binding protein interaction is implicated in nuclear trafficking of PBGD in differentiating glioma cells

Porphobilinogen deaminase (PBGD) is a rate-limiting enzyme of the heme biosynthesis pathway, whose level is elevated in various human tumors. PBGD was observed in both nuclear and cytoplasmic fractions of C6 glioma cells by immunostaining. During mitosis, chromatids were intensely stained for PBGD in comparison to the interphase chromatin. Using the yeast two-hybrid system, we identified RanBPM, the nuclear Ran-binding protein, as an interacting partner of PBGD. During butyrate-induced differentiation of C6, both nuclear and cytoplasmic PBGD levels declined as did Ran protein and its nucleotide exchange factor RCC1. N,N'-hexamethylene bis-acetamide-dependent differentiation resulted in an increase of the cytoplasmic PBGD, whereas nuclear PBGD, Ran protein and RCC1 remained unchanged. mRNA levels of PBGD remained unchanged during stimulation with both butyrate and N,N'-hexamethylene bis-acetamide. The enzymatic activity of PBGD and protoporphyrin IX synthesis in C6 cells were dependent on the differentiation induction agent. We conclude that PBGD possibly has a nuclear role in addition to its cytosolic enzymatic activity required for heme synthesis, which is related to cell transformation and differentiation.

Specificity of photosensitizer accumulation in undifferentiated versus differentiated colon carcinoma cells

The relationship between tumor cell differentiation and photosensitizer accumulation used in PDT is poorly defined. In the present work, specific cell differentiation of colon carcinoma CT26 cells induced by sodium butyrate was manifested by morphological changes, proliferation and protein expression and was correlated with the accumulation of endogenous and exogenous photosensitizes. Reduced accumulation of the endogenous protoporphyrin IX and the exogenous hypericin and MC540 was detected in differentiated cells. In contrast, a differentiation-dependent increase was measured with TPPS4, TMPyP, the pheophorbides (C5, C6, C12), HypS4 and helianthrone. In conclusion, PpIX, Hypericin and MC540 show specific binding and accumulation in poorly differentiated tumors, giving these tumors tissue-specific advantage in photo-diagnostic PDT applications.

Classification of lymphoproliferative disorders by spectral imaging of the nucleus

Spectral nuclear morphometry was used for the classification of lymphocytes in lymphoproliferative disorders. May-Grunwald-Giemsa-stained blood specimens were taken from thirty patients with infectious mononucleosis, non-Hodgkin lymphoma or chronic lymphocytic leukemia, and from ten healthy individuals. Blood specimens were analyzed by spectral imaging. Seventeen distinct spectra were collected into a spectral library and a distinct pseudo color was assigned to each one of them. The library was used to scan all the cells in the database and to create a spectrally classified image of each cell. The spectral map, per cell, reveals distinct spectral-response regions in each cellular compartment, via the distinct region colors. Computational analysis of the spectral maps allows for the objective quantification of a set of parameters, or features, representing the cell. The features used in this work include the area and perimeter of the nucleus, circularity, edginess and the spectral pattern. The analysis pursued showed that each class of cells is associated with a set of unique parameters. We conclude that spectral analysis combined with feature analysis provides significant information in the analysis of lymphoproliferative disorders and may serve as an additional tool for the histopathological evaluation of disease.

Eradication of Propionibacterium acnes by its endogenic porphyrins after illumination with high intensity blue light

Propionibacterium acnes is a Gram-positive, microaerophilic bacterium that causes skin wounds. It is known to naturally produce high amounts of intracellular porphyrins. The results of the present study confirm that the investigated strain of P. acnes is capable of producing endogenic porphyrins with no need for any trigger molecules. Extracts from growing cultures have demonstrated emission peaks around 612 nm when excited at 405 nm, which are characteristic for porphyrins. Endogenic porphyrins were determined and quantified after their extraction from the bacterial cells by fluorescence intensity and by elution retention time on high-performance liquid chromatography (HPLC). The porphyrins produced by P. acnes are mostly coproporphyrin, as shown by the HPLC elution patterns. Addition of delta-aminolevulinic acid (ALA) enhanced intracellular porphyrin synthesis and higher amounts of coproporphyrin have been found. Eradication of P. acnes by its endogenic porphyrins was examined after illumination with intense blue light at 407-420 nm. The viability of 24 h cultures grown anaerobically in liquid medium was reduced by less than two orders of magnitude when illuminated once with a light dose of 75 J cm(-2). Better photodynamic effects were obtained when cultures were illuminated twice or three times consecutively with a light dose of 75 J cm(-2) and an interval of 24 h between illuminations. The viability of the culture under these conditions decreased by four orders of magnitude after two illuminations and by five orders of magnitude after three illuminations. When ALA-triggered cultures were illuminated with intense blue light at a light dose of 75 J cm(-2) the viability of the treated cultures decreased by seven orders of magnitude. This decrease in viability can occur even after a single exposure of illumination for the indicated light intensity. X-ray microanalysis and transmission electron microscopy revealed structural damages to membranes in the illuminated P. acnes. Illumination of the endogenous coproporphyrin with blue light (407-420 nm) apparently plays a major role in P. acnes photoinactivation. A treatment protocol with a series of several illuminations or illumination after application of ALA may be suitable for curing acne. Treatment by both pathways may overcome the resistance of P. acnes to antibiotic treatment.

Spectrally resolved microscopy of GFP trafficking

Folding and chromophore cyclization-oxidation processes of green and cyan fluorescent fusion proteins (GFP and CFP) in subcellular microenvironments of transfected C6 glioma cells were studied by multipixel spectrally resolved microscopy (SRM). Discrete time-dependent spectral transitions were characterized during protein folding and chromophore maturation in the cytosol, nucleus, mitochondria, endoplasmic reticulum (ER), and Golgi. Spectral similarity mapping of fluorophore transition phases demarcated spatio-temporal fluorescence correlation at a subcellular level. Folding stages were characterized by a transition from red-shifted spectral populations in the time interval of 7-10 hr after transfection to a fully matured fluorophore emitting typical GFP or CFP fluorescence after 10-15 hr. The nascent protein revealed an initial focal accumulation in cytosol emitting in the range of 580-680 nm. After 10 hr, mixed pixel population spectra were measured and at 15 hr GFP was visualized in the cytoplasm by its specific spectral fingerprints with maxima at 545 nm. For nucleus- and mitochondrion-targeted CFPs, the mature conformer was discovered only in its final destination, whereas intermediate steps of fluorophore synthesis (at 10 hr) were found in the cytoplasm. Enhanced fluorescence maturation was manifested only by the ER-Golgi-targeted CFP after 10 hr post transfection by spectral imaging. Moreover, only remnants of initial intermediate fluorescent pixels were localized externally to the Golgi framework at 15 hr. SRM assessed the competence of ER-Golgi to maintain efficient CFP folding in comparison to the rest of the cellular compartments.

The correlation between hydrophilicity of hypericins and helianthrone: internalization mechanisms, subcellular distribution and photodynamic action in colon carcinoma cells

The internalization mechanism and subcellular distribution of hypericin (Hyp), hypericin tetrasulfonic acid (HypS4) and 1,3,4,6-tetrahydroxyhelianthrone (Hel) were studied in murine colon carcinoma CT26 cells, in protein-free medium or in the presence of serum proteins. The correlation between the extent of uptake of the sensitizers by cells that were incubated in the presence of different serum components, and the internalization mechanisms, was studied. The results indicate that sensitizer internalization may be a result of three mechanisms: partitioning, pinocytosis and endocytosis, and as a direct consequence is targeted to specific subcellular sites. While Hyp and Hel, the two lipophilic sensitizers, were localized in the endoplasmic reticulum after protein-free internalization, the hydrophilic HypS4 was localized in the cytoplasmic membrane and in lysosomes. An endolysosomal internalization route was revealed for Hyp and Hel under serum-enriched conditions showing lysosomal localization, as for HypS4. The lysosomal accumulation of Hyp-serum and specifically Hyp-LDL points to an endocytotic mechanism which is supported by its higher uptake parameter in an LDL-enriched medium, compared to the medium with 10% serum. The different uptake parameters of Hyp to cells, with or without serum, reflect the different mechanisms. Smaller differences in the uptake parameter for HypS4 reflect the distinction between partitioning and endocytosis, which, in this case, are both targeted to the lysosomes. The same uptake parameter of Hel to cells incubated in media with or without serum indicates the absence of the endocytotic mechanism. The interrelationship between subcellular targeting and photodynamic treatment was shown for the three sensitizers Hyp was found to be the most efficient sensitizer for PDT under our illumination protocol and it was dependent on internalization and localization sites.

Nuclear distribution of porphobilinogen deaminase (PBGD) in glioma cells: a regulatory role in cancer transformation?

Recently, considerable interest has been directed to red-fluorescence photodiagnosis of brain and other tumours during surgery using the protoporphyrin IX natural precursor, 5-aminolaevulinic acid. In the present study we focused on the role of the rate-limiting enzyme porphobilinogen deaminase in glioma C6 cell activity, differentiation and sub-cellular distribution. Over-expression of the human housekeeping porphobilinogen deaminase in the glioma cells, using the housekeeping-porphobilinogen deaminase plasmid, induced a G1 cell cycle attenuation accompanied by increases in enzyme activity and c6 differentiation toward astrocytes. Visualisation of subcellular localisation of the porphobilinogen deaminase using the independent techniques of fluorescence immuno-staining with specific anti-human porphobilinogen deaminase antibodies and cellular expression of porphobilinogen deaminase fused to green fluorescent protein, revealed (unexpectedly) a major fraction of porphobilinogen deaminase in the nucleus and only a minor fraction in the cytoplasm. Both C and N terminals of porphobilinogen deaminase fused to green fluorescent protein revealed a major fraction of the newly synthesized fused porphobilinogen deaminase in the nucleus. Furthermore, newborn rat brain cells grown in a primary culture showed the same localisation pattern of porphobilinogen deaminase in the nuclei. Stimulation of C6 glioma cell differentiation by butyrate induced a marked decrease in porphobilinogen deaminase both in the nucleus and in the cytoplasm as determined by Western blotting and fluorescence immuno-localisation. These findings suggest a possible dual role for housekeeping porphobilinogen deaminase in fast dividing glioma cells, one related to the porphyrin synthesis pathway and another coupled to nuclear function, which might be linked to tumorigenesis.

Nuclear transport of photosensitizers during photosensitization and oxidative stress

The nuclear transport pathways of the photosensitizers meso-tetra(4-sulfonatophenyl)porphyrin (TPPS4) and meso-tetra(4-N-methylpyridyl)porphyrin (TMPyP) during photosensitization and oxidative stress were characterized in CT-26 murine colon carcinoma cells using fluorescence microscopy and multi-pixel spectral imaging. Prior to irradiation, TPPS4 and TMPyP localized mainly in the lysosomes, while irradiation or H2O2 treatment induced a relocalization into the nucleus and nucleoli. Flow cytometry analysis of isolated nuclei from the treated cells showed an increase in nuclear fluorescence accompanying the relocalization. Isolation and separation of the nuclear proteins according to molecular weight was performed using a sephadex G-100 column. The protein fractions exhibiting high fluorescence were separated by high performance liquid chromatography. Five major classes of proteins with a retention time of 1, 7, 11, 12 and 15 min were obtained. Each photosensitizer was associated with a distinct class of proteins. While TPPS4 fluorescence was detected in the protein fraction with a retention time of 11 min, TMPyP fluorescence was associated with a protein fraction having a retention time of 7 min. We conclude that although oxidative stress triggers entry into the nucleus of both TPPS4 and TMPyP, each sensitizer uses a distinct transport mechanism based on its chemical properties.

Effects of water-soluble antioxidant from spinach, NAO, on doxorubicin-induced heart injury

Doxorubicin (DOX) produces clinically restorative responses in numerous human cancers, but its cardiotoxicity has limited its usefulness. Because reactive oxygen species may affect DOX-induced antitumor activity and cardiotoxicity, we evaluated the prophylactic effect of spinach natural antioxidant (NAO) on DOX-induced cardiotoxicity and oxidative stress in female Balb/c mice using histological, electron microscopical and biochemical parameters. Mice were treated with NAO for 7 days prior to and/or for 6 days after DOX administration. Pretreatment with NAO (cumulative dose: 130 mg/kg) did not hinder the effectiveness of DOX. Light and electron microscopy of DOX-treated heart revealed myocardial degeneration. When administered combined before and after DOX, NAO conferred the most significant cardiac protection. The effects of NAO on the lipid peroxidation product, malondialdehyde, and on H2O2/ hydroperoxides were examined on day 6 following DOX administration; levels of both were elevated in DOX-treated mice, compared to control. Pretreatment with NAO prevented these changes. Pretreatment with NAO before DOX administration decreased catalase and increased superoxide dismutase activities compared to the DOX group. Our results suggest usage of NAO in combination with DOX as a prophylactic strategy to protect heart muscle from DOX-induced cellular damage.

Structural characterization of erythroid and megakaryocytic differentiation in Friend erythroleukemia cells

OBJECTIVE

The aim of this study was to examine the structural characterization of erythroid and megakaryocytic cell differentiation in Friend erythroleukemic cells using spectral imaging and electron microscopy.

MATERIALS AND METHODS

Two variants of Friend erythroleukemia cells were treated with hexamethylene bisacetamide (HMBA) to induce differentiation: 1) MEL, which exhibit the normal phenotype and are susceptible to differentiation; and 2) the resistant R1 cells. The cells were analyzed by spectral imaging along with transmission and scanning electron microscopy. The expression of cell cycle regulatory proteins was analyzed by Western blotting.

RESULTS

Spectral imaging of HMBA-treated MEL and R1 cells stained by May-Grünwald-Giemsa and subjected to spectral similarity mapping revealed five morphologic cell types: proerythroblast-like cells, normoblast-like cells, reticulocyte-like cells, megakaryocytes, and apoptotic cells. In MEL cells, both megakaryocytic differentiation characterized by nuclear lobes and erythroid differentiation characterized by accumulation of hemoglobin were detected; R1 cells were not committed to terminal differentiation. HMBA-induced cell cycle arrest at G(1) affected the expression of regulatory proteins in a similar manner in both types of cells. Expression of cyclin-dependent kinase 4 decreased and expression of p21(WAF1) increased. The level of the underphosphorylated form of phosphorylated retinoblastoma protein increased, inducing a decrease in the level of c-myc. In addition, we detected a decrease in the expression of the anti-apoptotic regulator, Bcl-2, and an increased expression of the pro-apoptotic regulator, Bax.

CONCLUSIONS

Spectral imaging provides new insight for the morphologic characterization of erythroid and megakaryocytic cell differentiation as well as apoptosis. Image analysis was well correlated to cell cycle arrest and the expression of regulatory proteins.

Spectral imaging of MC540 during murine and human colon carcinoma cell differentiation

We studied the staining pattern of merocyanine 540 (MC540) by spectral imaging of murine CT26 and human HT29 colon carcinoma cells incubated with the dye MC540. This dye, usually considered a potential membrane probe, localized mainly in the cytoplasmic vesicles of the colon carcinoma cells. However, in cells incubated in an environment similar to that of a tumor (pH 6.7), high fluorescence was detected in the nuclear membrane and nucleoli. Under these acidic conditions, resembling the Krebs effect, a population of CT26 cells displayed fluorescent plasma membranes. In differentiating cells, exhibiting cell cycle arrest at G(1)-phase and an elevated level of alkaline phosphatase, MC540 fluorescence was confined to cytoplasmic vesicles and was not detected in the plasma membrane or in the nucleoli. Cell sorting analysis of both cell types at pH 5.0 revealed higher fluorescence intensity in proliferating cells compared to differentiating cells. The fluorescence intensity of MC540-stained cells reached a maximum at pH 5.0, although the fluorescence of MC540 dye was maximal at pH 7.2. This phenomenon may result from increased binding of MC540 monomers to the cells because disaggregation of the dye with Triton X-100 produced similar results. We conclude that nucleolar localization of MC540 and an elevated fluorescence intensity can be used as indicators for proliferating cells in the characteristically acidic tumor environment. (J Histochem Cytochem 49:147-153, 2001)

Mitochondrial localization and photodamage during photodynamic therapy with tetraphenylporphines

The subcellular localization sites of TPPS4 and TPPS1 and the subsequent cellular site damage during photodynamic therapy were investigated in CT-26 colon carcinoma cells using spectroscopic and electron microscopy techniques. The association of both porphyrins with the mitochondria was investigated and the implications of this association on cellular functions were determined. Spectrofluorescence measurements showed that TPPS4 favors an aqueous environment, while TPPS1 interacts with lipophilic complexes. The subcellular localization sites of each sensitizer were determined using spectral imaging. Mitochondrial-CFP transfected cells treated with porphyrins revealed localization of TPPS1 in the peri-nuclear region, while TPPS4 localized in the mitochondria, inducing structural damage and swelling upon irradiation, as shown by transmission electron microscopy. TPPS4 fluorescence was detected in isolated mitochondria following irradiation. The photodamage induced a 38% reduction in mitochondrial activity, a 30% decrease in cellular ATP and a reduction in Na(+)/K(+)-ATPase activity. As a result, cytosolic concentrations of Na(+) and Ca(2+) increased, and the level of K(+) decreased. In contrast, the lipophilic TPPS1 did not affect mitochondrial structure or function and ATP content remained unchanged. We conclude that TPPS4 induces mitochondrial structural and functional photodamage resulting in an altered cytoplasmic ion concentration, while TPPS1 has no effect on the mitochondria.

Green fluorescent protein photobleaching: a model for protein damage by endogenous and exogenous singlet oxygen

Characterization of protein damage during photosensitization of chlorin e6-treated cells was performed using the green fluorescent protein (GFP). The GFP-chromophore damage caused by singlet oxygen was studied in COS 7 kidney cells and E. coli bacteria following light irradiation. Electron spin resonance (ESR) revealed the generation of endogenous singlet oxygen (1O2) by photoactivated GFP, an effect similar to that produced by the exogenous photosensitizer chlorin e6. A light dose-dependent photobleaching effect of GFP was pronounced at low pH or upon photosensitization with chlorin e6. However, the 1O2 quenchers beta-carotene and sodium azide minimized GFP photo-bleaching. Gel electrophoresis of photosensitized GFP followed by fluorescence multi-pixel spectral imaging revealed the binding of chlorin e6 to GFP, affecting the photobleaching efficacy. Fluorescence multi-pixel spectral imaging of GFP-transfected COS 7 cells demonstrated the presence of GFP in the cytoplasm and nucleus, while chlorin e6 was found to be concentrated in the perinuclear vesicles. Exposure of the cells to light induced GFP photobleaching in the close vicinity of chlorin e6 vesicles. We conclude that photoactivated GFP generates endogenous 1O2, inducing chromophore damage, which can be enhanced by the cooperation of exogenous chlorin e6.

Potential use of spectral image analysis for the quantitative evaluation of estrogen receptors in breast cancer

Evaluation of estrogen receptor (ER) content is an important factor in the choice of therapy and prognosis of breast cancer patients. In this study, we demonstrate a new spectral image analysis technique for objective and quantitative evaluations of stained specimens. The SpectraCube system was used to analyze nuclear antigens in thirteen cases of breast cancer stained by the immunoperoxidase method with hematoxylin counterstain. Spectral imaging segregated the spectrum of diaminobenzidine (DAB) from the background color of hematoxylin and a spectral index was calculated. The spectral index essentially agreed with the pathologist's index (on a scale of 0 to 3) in seven out of the thirteen cases. A substantial number of ER positive pixels was detected in the two cases scored as 0 by the pathologist's index. In a test case scored as 1 by the pathologist's index we detected a significant number of pixels, representing 47% of the nuclei, with DAB-intensity values higher than the cut-off value of 1.2. These data suggest that spectral image analysis is a sensitive method providing intensive information with high reproducibility. Our spectral imaging method is highly flexible, enabling the user to define the spatial resolution of the analyzed specimen by choosing the number of pixels per one nucleus.

Photothermic treatment of pigmented B16 melanoma using a broadband pulsed light delivery system

Pulsed photothermic treatment (PTT) of pigmented B16 mice melanoma tumors was carried out using a Photodyne incoherent light delivery system. Tumor heating with average temperature of 41-44 degrees C was observed during broadband photoirradiation (600-800 nm) at light doses of 60-120 J/cm(2) delivered using 0.6 J/cm(2) pulses (2 ms) at 1 Hz repetition rate. Electron microscopy of tumor samples revealed pronounced structural changes in microvasculature and melanosomes. Pulsed PTT caused damage to endothelial cells and vascular walls, swelling of mitochondria and melanosomal disruption without nuclear alteration. Significant tumor response with necrosis formation followed by tumor regression was observed by a tumor growth study after PTT at 120 J/cm(2).

Photodynamic therapy of cutaneous lymphoma using 5-aminolevulinic acid topical application

BACKGROUND

Photodynamic therapy (PDT) with topical application of 5-aminolevulinic acid (ALA) is a new and effective modality for treatment of superficial basal and squamous cell carcinomas.

OBJECTIVE

We present the kinetics of ALA-induced protoporphyrin IX (PP) accumulation and the results of ALA PDT treatment on two patients with different stages (stage I and stage III) of mycosis fungoides (MF)-type cutaneous T-cell lymphoma (CTCL).

METHODS

ALA-Decoderm cream was applied to the lesions for 16 hours. Spectrofluorescence measurements of PP accumulation were carried out before, during, and 1 hour after photoirradiation (580-720 nm) using the VersaLight system.

RESULTS

Different patterns of PP fluorescence kinetics were observed in patients with early and advanced stages of the disease. During photoirradiation the intensity of fluorescence decreased depending on the lesion thickness. One hour after the photoirradiation procedure no PP fluorescence was observed in the stage I MF lesion, while in the thick stage III MF lesions, PP fluorescence reappeared; after an additional 10-15 minutes of irradiation PP fluorescence disappeared. Complete response with excellent cosmetic results was observed in the stage I lesion after a single irradiation with a light dose of 170 J/cm2; in five stage III lesions, complete response was achieved after fractionated irradiation with a total light dose of 380 J/cm2 (follow-up at 27 and 24 months, respectively).

CONCLUSION

The results showed a high response of both stage I and stage III MF lesions to ALA PDT. This modality appears to be very effective and can be used successfully for MF treatment.

Treatment of viral infections with 5-aminolevulinic acid and light

BACKGROUND AND OBJECTIVE

When 5-aminolevulinic acid (ALA) is exogenously supplied, protoporphyrin IX (PpIX) is accumulated in various cells and makes them light sensitive. The possibility of using such an approach for the treatment of viral infections was studied in this work.

STUDY DESIGN/MATERIALS AND METHODS

ALA was added to cultured cells infected with human immunodeficiency virus (HIV). Accumulation of PpIX in the cells as well as virus infectivity after photodynamic treatment (PDT) were assessed. For in vivo studies, guinea pigs were infected with herpes simplex virus (HSV) and then administered ALA at intervals after infection. The animals were exposed to PDT at the site of infection 3 hours after ALA administration. Clinical observations and virus titration were made daily. For clinical studies, two patients with Molluscum contagiosum and Verrucae vulgares were treated with ALA fortified with an iron chelating agent and dimethylsulfoxide, followed 4 hours later by PDT.

RESULTS

Cells that are infected with HIV accumulated PpIX upon addition of ALA in vitro. This accumulation was enhanced approximately two-fold in the presence of an iron chelator. Subsequent exposure to red light PDT drastically reduced the virus titer (> 99% for U1 cells latently infected with HIV). In guinea pigs infected with HSV, subsequent administration of ALA and exposure of the lesions to red light shortened the duration of vesicles' appearance from more than a week to a few days and reduced HSV titer in the lesions by > or = 5 log10. ALA-PDT treated AIDS patient suffering from Molluscum contagiosum or a kidney transplant patient with Verrucae vulgares showed greatly improved clinical symptoms one month after treatment.

CONCLUSION

It is concluded that ALA-PDT could be effective in treating certain viral infections, particularly those resulting in warts.

Spectral imaging of red blood cells in experimental anemia of Cyprinus carpio

In the present work we have studied the effect of experimental anemia induced at both low and optimal temperatures on erythropoiesis in Cyprinus carpio. The results showed that hemoglobin concentration per cell was similar in both temperature conditions, however, red blood cell (RBC) concentration was higher at the optimal temperature. Induced anemia caused an abrupt decrease in RBC concentration, while the hemoglobin concentration per cell remained unchanged. Recovery, as shown by electron microscopy, was characterized by the release of differentiating young and intermediate cells to the peripheral blood. It was revealed that with the progression of differentiation the nucleus/cytoplasm ratio decreases, the chromatin condenses and the shape of the nucleus changes from round to elliptical. Spectral imaging revealed an increase in the optical density of chromatin with the maturation of the cells. The chromatin that was dispersed over the nuclear volume in the young cells becomes highly ordered in the mature cells. Spectral similarity mapping revealed the formation of a novel structure of high symmetry, representing chromatin rearrangement during the process of cellular differentiation.

Proteinase inhibitors from desert locust, Schistocerca gregaria: engineering of both P(1) and P(1)' residues converts a potent chymotrypsin inhibitor to a potent trypsin inhibitor

Two peptides, SGCI and SGTI, that inhibited chymotrypsin and trypsin, respectively, were isolated from the haemolymph of Schistocerca gregaria. Their primary structures were found to be identical with SGP-2 and SGP-1, two of a series of peptides isolated from ovaries of the same species (A. Hamdaoui et al., FEBS Lett. 422 (1998) 74-78). All these peptides are composed of 35-36 amino acid residues and contain three homologous disulfide bridges. The residues imparting specificity to SGCI and SGTI were identified as Leu-30 and Arg-29, respectively. The peptides were synthesised by solid-phase peptide synthesis, and the synthetic ones displayed the same inhibition as the natural forms: SGCI is a strong inhibitor of chymotrypsin (K(i) = 6.2 x 10(-12) M), and SGTI is a rather weak inhibitor of trypsin (K(i) = 2.1 x 10(-7) M). The replacement of P(1) then P(1)' residues of SGCI with trypsin-specific residues increased affinity towards trypsin 3600- and 1100-fold, respectively, thus SGCI was converted to a strong trypsin inhibitor (K(i) = 5.0 x 10(-12) M) that retained some inhibitory affinity towards chymotrypsin (K(i) = 3.5 x 10(-8) M). The documented role of both P(1) and P(1)' highlights the importance of S(1)'P(1)' interactions in enzyme-inhibitor complexes.

Photoproduct formation from a zinc benzochlorin iminium salt detected by fluorescence microscopy

When examined by fluorescence microscopy, tumor cells loaded with a zinc benzochlorin iminium salt showed a very faint deep-red fluorescence that was rapidly transformed to a substantially brighter red-orange fluorescence. Fourier transfer spectroscopy analysis with a red-sensitive detection system revealed that an initial fluorescence at 770 nm was gradually converted to 640 nm fluorescence during excitation. Image analysis showed that photoproduct formation was accompanied by a change in the site of drug localization from the cytoplasm to the nucleus. These studies illustrate the power of interferometry for the characterization of photoproducts and changes in sensitizer localization during photoproduct formation.

Enhancement of ALA-PDT damage by IR-induced hyperthermia on a colon carcinoma model

The interaction of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) and hyperthermia is not well understood. In the present study, significant enhancement of tumor damage was observed after simultaneous application of ALA-PDT and IR-induced hyperthermia using a broad-band incoherent light source. One hour after systemic administration of ALA at a dose of 200 mg/kg, subcutaneously transplanted C26 colon carcinoma tumors were irradiated with two bands of the VersaLight system, red (R, 580-720 nm) and red plus IR (R + IR, 580-720 nm and 1250-1600 nm). Photoirradiation using the R + IR band at different fluence rates and exposures caused mild heating of the tumor to 39-43 degrees C at a 3 mm depth. Electron microscopy after ALA + R, ALA + R + IR and R + IR treatments showed early mitochondrial swelling that was more pronounced in the ALA + R + IR group. Tumor necrosis assessment, using histology and vital staining, revealed an enhancement of tumor necrosis depth in the ALA + R + IR group compared to ALA + R and R + IR. The results showed that subhyperthermic heating to 39-39.5 degrees C in the ALA + R + IR group decreased the threshold light dose required for 100% tumor necrosis from 210 J/cm2 (observed in the ALA + R group) to 140 J/cm2. A tumor growth delay test, based on tumor volume measurement, also revealed significant enhancement of antitumor effect after application of ALA + R + IR compared to ALA + R.