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J Moan

Publications and source records attributed to J Moan.

At least 91 records · Page 5Linked to original sources
PubMed1994

Lysosomes as photochemical targets.

Sulfonated tetraphenyl porphines (TPPSn) are photosensitizing dyes that localize in lysosomes of NHIK 3025 cells. In order to elucidate the mechanisms of cell inactivation by photochemical treatment with TPPSn, lysosomal enzyme inactivation and release of lysosomal contents were examined after treatment. In cells treated with TPPS4 and light, the lysosomal enzymes beta-N-acetyl-D-glucosaminidase (beta-AGA) and cathepsin(L+B) were almost completely inactivated and no enzyme activities were released from the lysosomes. In contrast, a maximum of 30 and 50% of the initial beta-AGA activity was released from lysosomes after treatment with TPPS1 and TPPS2a, respectively. Forty per cent of the initial beta-AGA activity was released after treatment with TPPS2a and a non-cytotoxic dose of light. After such a treatment only approximately 10% of the initial cathepsin activity was found in the cytosol fraction and in all other cases no cathepsin activity was recovered in the cytosol fraction after photochemical treatment. It was found that the constituents of the cytosol partly inhibited cathepsin activity. This inhibitory effect was not influenced by the photochemical treatment, neither was the colony-forming ability of photochemically treated cells influenced by pre-treatment with the cathepsin inhibitor E64. The present results indicate that NHIK 3025 cells are not killed by lysosomal disruption after photochemical treatment. This is partly due to photochemical inactivation of the lysosomal enzymes and to the action of cytosolic cysteine cathepsin inhibitors. The present results also indicate that cells can survive a partial lysosomal disruption.

Acetylglucosaminidase↗
PubMed1994

Sulfonated aluminium phthalocyanines as sensitizers for photochemotherapy. Effects of small light doses on localization, dye fluorescence and photosensitivity in V79 cells.

V79 cells incubated with di- or tetrasulfonated aluminium phthalocyanines (AlPcS2 or AlPcS4) showed a granular fluorescence pattern. Co-staining with the lysosomotropic dye acridine orange (AO) indicated that the granules that were stained by these photoactive phthalocyanines were identical to lysosomes. Small light exposures made the lysosomes permeable to the dyes without inactivating the cells. Also, the lysosomal enzymes beta-AGA and cathepsin (L+B) were inactivated by small light exposures when AlPcS4 was present. Such small and almost nontoxic light exposures caused a redistribution of the dyes in the cells that was accompanied by a more than 10-fold increase in the fluorescence quantum yields of the dyes. Surprisingly, this redistribution and increase in fluorescence did not result in any significant increase in the photosensitivity of the cells.

Acetylglucosaminidase↗
PubMed1994

Pressure against the tumor can reduce the efficiency of photochemotherapy.

C3D2/F1 mice with mammary carcinoma tumors growing subcutaneously on their right foot were given 10 mg/kg aluminium phthalocyanine tetrasulfonate (AlPcS4) by intraperitoneal injection. Twenty-four hours later these tumors were exposed to light at 680 nm. The size of the tumors was measured daily. An exposure of 135 J/cm2 (150 mW/cm2) reduced the tumor growth rate so that the time needed for the tumors to reach a volume five times larger than that at the time of exposure increased from 4 days for control tumors to 15 days. However, when a glass plate was gently pressed against the tumor surface during irradiation, the effect of an identical exposure was significantly smaller. In agreement with this, microscopic studies showed that tumors exposed to laser light without any pressure applied during irradiation were more damaged than tumors receiving a slight pressure. Thus, pressure against the tumor can obviously reduce the oxygen concentration in this tumor enough to reduce the efficiency of the treatment.

Animals↗
PubMed1994

Evaluation of a new photosensitizer, meso-tetra-hydroxyphenyl-chlorin, for use in photodynamic therapy: a comparison of its photobiological properties with those of two other photosensitizers.

The properties of a new photosensitizer, meso-tetra-hydroxyphenyl-chlorin (mTHPC), were studied using V79 cells (Chinese-hamster lung fibroblasts). Comparisons were made with 2 other photosensitizers: photofrin II (PII) and meso-tetra-hydroxyphenyl-porphyrin (mTHPP). A main advantage of mTHPC is that it has a strong absorption at 652 nm. Maximal cellular uptake of the dye was observed after 24 hr incubation of the cells with the drug. Using a confocal laser-scanning fluorescence microscope, we observed a diffuse distribution of mTHPC in the cytoplasm. Furthermore, the lipophilicity of mTHPC was compared with that of the components of PII by means of high-pressure liquid chromatography (HPLC). Absorption and fluorescence spectroscopy indicated that aggregated as well as monomeric mTHPC was bound to the cells. The action spectrum for photo-inactivation of the cells showed that aggregated mTHPC did not contribute significantly to its photosensitizing effects. In the present cellular system, the efficiency of photodynamic therapy (PDT) with mTHPC (cells were irradiated at a wavelength of 652 nm) was higher than with PII (irradiation at 630 nm) or with mTHPP (648 nm). The quantum yield for photo-inactivation of cells was smaller for mTHPC than for mTHPP and PII. The addition of 1,3-diphenylisobenzofuran (DPBF) reduced cell inactivation during PDT. Thus, PDT with mTHPC seems to act at least partly via a type-II process.

Animals↗
PubMed1994

[Is UV-A a cause of malignant melanoma?].

The first action spectrum for cutaneous malignant melanoma was published recently (2). This spectrum was obtained using the fish Xiphophorus. If the same action spectrum applies to humans, the following statements are true: Sunbathing products (agents to protect against the sun) that absorb UV-B radiation provide almost no protection against cutaneous malignant melanoma. UV-A-solaria are more dangerous than expected so far. If people are determined to use artificial sources of radiation for tanning, they should choose UV-B-solaria rather than UV-A-solaria. Fluorescent tubes and halogen lamps may have weak melanomagnetic effects. Ozone depletion has almost no effect on the incidence rates of CMM, since ozone absorbs very little UV-A radiation. Sunbathing products which contain UV-A-absorbing compounds or neutral filters (like titanium oxide) provide real protection against cutaneous malignant melanoma, at least if they are photochemically inert.

Animals↗
PubMed1994

Effects of ultraviolet radiation on intercellular communication in V79 Chinese hamster fibroblasts.

The effects of ultraviolet (UV) radiation on gap junctional intercellular communication (GJIC) in V79 Chinese hamster fibroblasts were studied by means of a dye transfer assay. Intercellular communication was shown to be altered by UVB (297/302 nm) and UVA (365 nm) radiation, the effect depending on the wavelength of exposure and time between irradiation and microinjection of the dye in the dye transfer assay. Exposure to 297/302 nm radiation induced a reduction in intercellular communication 6 min after exposure. Incubation of the cells post-irradiation reversed the inhibition of GJIC. From 2 to 24 h after exposure an increase in GJIC over the control cells was seen, with a maximum at 8 h post-irradiation. UVA (365 nm) radiation, on the other hand, induced an increase in the intercellular communication 6 min after irradiation. Incubation of the cells post-irradiation led to a decrease in the number of communicating cells, with a minimum seen 4 h after exposure. The reduction in communication observed after exposure to UVB and UVA was not correlated with similar modifications in the gap junction protein connexin43 as found when exposing the cells to the tumour promoter 12-O-tetradecanoyl-phorbol-13-acetate. For the higher fluences of UVA, a decrease in immunorecognizable connexin43 was seen, concomitant with a markedly increased background of higher mol. wt compounds. This may be due to UVA-induced crosslinking of connexin43. No correlation was found between changes in communication induced by UV radiation and levels of cyclic AMP.

Animals↗
PubMed1994

Quantitative assessment of epidermal melanogenesis in C3H/Tif hr/hr mice treated with topical furocoumarins and UVA radiation.

We report quantitative data on epidermal melanogenesis by established and new furocoumarins. The ears and dorsal skin of pigmented hairless mice were treated for 12 d with compounds in ethanol, at equi-optical concentrations, and exposed to subphototoxic doses of ultraviolet A. Increased pigmentation was observed with 6,4,4'-trimethylangelicin > psoralen > 8-methoxypsoralen > 5-methoxypsoralen > 4,4',5'-trimethylazapsoralen = bergamot oil. Assessment of melanocyte numbers and morphology in epidermal sheet dihydroxyphenylalanine preparations showed that 6,4,4'-trimethylangelicin was the best compound with 536 ear melanocytes/mm2 +/- 15 SEM compared with 46 +/- 4 in controls. Psoralen induced 297/mm2 +/- 33, compared with its methoxy derivatives with ranges between 200 and 240/mm2.6,4,4'-trimethylangelicin had a striking effect on dorsal skin with 462 +/- 18 melanocytes/mm2 compared to less than 80/mm2 in all other ultraviolet A treatment groups. Khellin, 5-GOP and ultraviolet A only and all non-ultraviolet A controls had no effect. Melanogenesis was associated with increased dendricity, melanocyte size, especially with 5-methoxypsoralen, and giant melanocytes were noted with some treatments. The potency of 6,4,4'-trimethylangelicin, which does not form DNA interstrand crosslinks, may be related to its high DNA binding constant. Our data may be useful in the selection of compounds to treat vitiligo.

Administration, Topical↗
PubMed1993

Uptake and distribution of intravenously or intravesically administered photosensitizers in the rat.

Photodynamic therapy using i.v. injected porphyrin photosensitizers have been used to treat selected cases of superficial bladder cancer. Since cutaneous photosensitivity, lasting 6-8 weeks, is a well known undesirable side effect of this therapy, we instilled the photosensitizers intravesically in rats and compared the uptake of photosensitizers in different tissues by this route of administration with the uptake after intravenous injection. The intravesical mode of delivery enhanced photosensitizer uptake in the bladder wall, while giving low concentrations in extravesical organs. Intravesical instillation of the photosensitizers may therefore increase their efficacy and reduce phototoxicity as compared with intravenous injection. Comparing the results obtained by two assays, one based on porphyrin fluorescence and the other based on the application of radioactively labelled photosensitizers, it was concluded that the i.v. administration route may result in tissue uptake of significant amounts of aggregated non-fluorescent, supposedly inactive drug, while the intravesical administration led to less uptake of aggregates relative to active drug monomers.

Animals↗
PubMed1993

Photochemical treatment with the lysosomally localized dye tetra(4-sulfonatophenyl)porphine results in lysosomal release of the dye but not of beta-N-acetyl-D-glucosaminidase activity.

Tetra(4-sulfonatophenyl)porphine (TPPS4) sensitizes cells to photoinactivation mainly through formation of singlet oxygen. In human cervix carcinoma cells of the line NHIK 3025 TPPS4 localizes to a large extent in lysosomes as previously shown by fluorescence microscopical and spectroscopical techniques. In the present study photodamage to lysosomes was investigated. This was accomplished by measuring the activity of the lysosomal marker enzyme beta-N-acetyl-D-glucosaminidase (beta-AGA) after photochemical treatment (PCT). beta-AGA activity was highly sensitive to light exposure in the presence of TPPS4. The enzymatic activity was reduced by approximately 70% by non-lethal doses of photochemical treatment, indicating that inactivation of lysosomal hydrolases is not likely to contribute significantly to the cytotoxic effects of PCT. Centrifugation studies showed that TPPS4, but not beta-AGA activity, was released from lysosomes after light exposure. 20-30% of the total beta-AGA activity was resistant to the photochemical treatment. This was due to beta-AGA activity in Golgi-derived vesicles (4-5%) and in vesicles with similar density as lysosomes but not containing TPPS4. The present results indicate that lysosomal hydrolases are inactivated by photochemical treatment before they eventually escape the lysosomal compartment.

Acetylglucosaminidase↗
PubMed1993

Binding of drugs to human plasma proteins, exemplified by Sn(IV)-etiopurpurin dichloride delivered in cremophor and DMSO.

1. The mode-delivery-effect upon the binding of Sn(IV)-etiopurpurin dichloride (SnET2) in human plasma has been studied by ultracentrifugation, combined with absorption and fluorescence spectroscopy. SnET2 was delivered to plasma either in Cremophore EL (CRM) or in dimethyl sulfoxide (DMSO). To facilitate interpretation, optical, conductivity and aggregation properties of SnET2 were obtained for various solutions. 2. The second order rate constant for the aggregation of SnET2 monomers seemed to be remarkably small, of the order of 10(3) M-1 min-1. 3. SnET2 was bound as monomeric entities. Such entities had environmental-sensitive fluorescent properties dependent on the type of protein or solvent (DMSO, CRM, H2O) with which they interacted. 4. SnET2 showed saturable binding with high density subfraction(s) of high density lipoproteins and with one or more high density proteins. Complete or substantial saturation was achieved at the SnET2 level of 3.5 micrograms/ml. Such binding might be mediated by apolipoprotein D and alpha 1-acid glycoprotein. 5. There was little effect of SnET2 concentrations (3.5-35 micrograms SnET2/ml) upon the plasma binding of SnET2, irrespective of the mode of delivery. 6. The percentages of SnET2 bound to low density lipoproteins (LDL), high density lipoproteins (HDL), and high density proteins (HDP) were 10, 70 and 20%, respectively, for delivery in DMSO. The value for LDL also includes binding with very low density lipoproteins (VLDL). For delivery in CRM the corresponding values were 20, 50 and 30%. Apparently, CRM interacted with HDL entities and reduced their affinity for SnET2. 7. The distribution pattern of SnET2 among lipoproteins reflects interactions with apoproteins and/or with surface phospholipids rather than with core lipid constituents of lipoproteins. 8. Conductivity measurements showed that SnET2 was partly an ionic entity in water. 9. The plasma binding of SnET2 is compared with the corresponding binding of other drugs, both tetrapyrroles and nontetrapyrroles.

Adsorption↗
PubMed1993

Photobiological properties of hematoporphyrin diesters: evaluation for possible application in photochemotherapy of cancer.

The dimethyl, diethyl, dipropyl, dibutyl, diamyl, dihexyl and diheptyl esters of hematoporphyrin (Hp) were synthesized and shown to be more strongly retained on a reverse phase (C18) high performance liquid chromatography column than most components of Photofrin II (PII) - the sensitizer used for photochemical treatment of cancer in the clinic. The Hp diesters were found to be less efficient than PII in sensitizing cells to photoinactivation. This was partly due to de-esterification of the Hp diesters by esterase activity in the serum. The de-esterification of the Hp diesters was highly dependent on the ester group, with Hp dimethyl ester (t1/2 for conversion to Hp monomethyl ester was 6 min) being de-esterified with a rate 500 times faster than that for Hp diheptyl ester. Incubation of NHIK 3025 cells with these dyes showed that the Hp diesters were all partly located in extranuclear spots and partly diffusely distributed in the cytoplasm. The fluorescing spots may be due to lysosomally located Hp diesters, since the lysosomal marker enzyme beta-Nacetyl-D-glucosaminidase was partly inactivated by Hp diesters and light.

Biological Transport, Active↗
PubMed1993

Biodistribution of a methylene blue derivative in tumor and normal tissues of rats.

By using a chemical extraction procedure and confocal laser scanning fluorescence microscopy we have investigated the kinetic patterns of uptake and biolocalization of a methylene blue derivative (MBD) in tumors and various normal tissues of Wistar rats bearing fibrosarcoma (Leeds ovarian tumor) after intravenous injection of MBD (10 mg kg-1 body weight). Similar kinetics of accumulation and elimination of MBD fluorescence were found in tumor tissue and surrounding normal skin and muscle tissues. However, the tumor:skin and tumor:muscle ratios of the MBD fluorescence intensity were found to be 9 and 4, respectively, 4 h after intravenous injection, indicating selective uptake of MBD by the tumor tissue. MBD was localized on the walls of all the vessels and extensively in the area of neoplastic cellular and tumorigenic fibrous components in the tumor tissue. Interestingly, no MBD fluorescence could be detected in the metastatic neoplastic cells in the remote lymph nodes. In the skin, MBD was mainly distributed in the keratinized epithelium of the epidermis, hair follicles and their accessories, while little was found both in the epidermis and dermis. In most other tissues, the maximal fluorescence intensity of MBD was found 1-4 h after injection, after which it decreased dramatically to almost undetectable levels 120 h postinjection. Strong fluorescence of MBD was seen in the tracheal mucosal epithelium, while little fluorescence was noted in the transitional epithelium of bladder. The kinetics of biolocalization of MBD in some other tissues (liver, spleen, kidney, brain, muscle, lung, heart) were also studied.

Animals↗
PubMed1993

Combination therapy: photochemotherapy; electric current; and ionizing radiation. Different combinations studied in a WiDr human colon adenocarcinoma cell line.

The interactions of pairs of the modalities Photofrin II-sensitized photochemotherapy (PCT), ionizing radiation and an electric current were investigated by the colony formation assay in WiDr cells, a human colon adenocarcinoma cell line. When the cells were treated simultaneously with PCT and an electric current, a slightly synergistic effect was observed at low exposures (surviving fraction approximately 0.1) while a seemingly antagonist effect was found at higher exposures. The same was found to be true for the combinations of PCT plus ionizing radiation and ionizing radiation plus electric current.

Adenocarcinoma↗
PubMed1993

An action spectrum for UV-induced attachment of V79 Chinese hamster cells to a substratum.

When cells growing in monolayers are exposed to ultraviolet radiation (UV) their binding to the substratum is increased in strength. An action spectrum for such UV-induced binding was determined, using the time needed for trypsin-EDTA to detach the cells as a measure of the binding strength. This action spectrum was significantly different from the action spectrum for cell inactivation, which was also determined. At the shortest wavelengths (297/302, 313 nm) lethal fluences were needed to induce measurable binding while at the longest wavelengths (365, 405 nm) completely nonlethal fluences induced strong and persistent binding. Thus, different chromophores are involved in the two processes: while DNA may be the main chromophore for cell inactivation, other and unidentified chromophores may be more important for induction of increased cell binding to the substratum.

Animals↗
PubMed1993

Primary DNA damage, HPRT mutation and cell inactivation photoinduced with various sensitizers in V79 cells.

DNA strand breaks and hypoxanthine guanine phosphoribosyl transferase (HPRT) mutants were measured in parallel in photochemically treated (PCT) cells and compared at the same level of cell survival. Chinese hamster fibroblasts (V79 cells) were either incubated with the lipophilic dyes tetra(3-hydroxyphenyl)porphyrin (3THPP) and Photofrin II (PII), the anionic dye meso-tetra(4-sulfonatophenyl)porphine (TPPS4) or the cationic dye meso-tetra(N-methyl-4-pyridyl)porphine (p-TMPyPH2) before light exposure. In the cells, the lipophilic dyes were localized in membranes, including the nuclear membrane, while the hydrophilic dyes were taken up primarily into spots in the cytoplasm. In addition, the hydrophilic TPPS4 was distributed homogeneously throughout the whole cytoplasm and nucleoplasm. According to the HPRT mutation test, the mutagenicity of light doses survived by 10% of the cells was a factor of six higher in the presence of 3THPP than of PII, whereas for X-rays it was a factor of three higher than for PCT with 3THPP. Light exposure in the presence of the hydrophilic dyes TPPS4 and p-TMPyPH2 was not significantly mutagenic. There was no correlation between the induced rates of HPRT mutants and of DNA strand breaks. Thus, TPPS4 was the most efficient sensitizer with regard to DNA strand breaks when compared at the same level of cell survival, followed by 3THPP, PII and p-TMPyPH2. Hence, the rate of DNA strand breaks cannot be used to predict the mutagenicity of PCT.

Animals↗
PubMed1993

Potentiation of photodynamic therapy by mitomycin C in cultured human colon adenocarcinoma cells.

The effects of photodynamic therapy (PDT) alone and in combination with Mitomycin C (MMC) on WiDr cells, a human colon adenocarcinoma cell line, were investigated. The addition of MMC increased the cytotoxicity of PDT. The presence of MMC resulted in a reduction or a removal of the shoulder of the PDT survival curves as well as an increase in their slopes. Increasing with the concentrations of MMC from 0.01 to 0.025 micrograms/ml, the cytotoxic effects of the two treatments changed from additivity to supra-additivity as judged by comparing dose-response curves for each treatment alone with survival curves after combination therapy and by isobologram analysis. The cytotoxicity of MMC could also be enhanced by a practically nontoxic treatment of PDT (8% cell inactivation). The cytotoxicities of MMC and PDT in combination were found to be dependent on the sequence of the two treatments. When MMC (> or = 0.02 micrograms/ml) and Photofrin II were given simultaneously for 16 h and then followed by irradiation, the combination was found to be more effective than when MMC was given to the cells immediately after PDT and kept in the medium for 16 h. Possible mechanisms of the combination effects of PDT and MMC are discussed briefly.

Adenocarcinoma↗