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J Moan

Publications and source records attributed to J Moan.

At least 73 records · Page 4Linked to original sources
PubMed1996

Enhanced antitumour effect of photodynamic therapy by microtubule inhibitors.

The combination of photodynamic therapy (PDT) and the microtubule (MT) inhibitor, vincristine (VCR) or taxol, was studied in the CaD2 mammary tumour model in mice. Meso-tetra(di-adjacent-sulphonatophenyl) porphine (TPPS2a) was used as a photosensitizer. An enhanced antitumour effect was found when VCR, at an almost non-toxic dose (1 mg/kg1, was injected i.p. into the mice 6 h before PDT, while no such enhanced effect was observed when the same dose of VCR was given either 12 or 24 h before PDT or immediately before PDT. Furthermore, it was found that the number of mitotic cells increased 4-5-fold 6 h after the injection of VCR into the mice. VCR did not enhance the sensitivity of normal skin to PDT. Combination of PDT and taxol was also studied. The antitumour activity of PDT could be increased by taxol when the drug (35 mg/kg) was administered i.p. either 6 h prior to PDT or immediately after or before PDT. No significant enhancement in PDT efficiency was found when PDT with photofrin was combined with VCR.

Animals↗
PubMed1996

Effects of the inhibitors of energy metabolism, lonidamine and levamisole, on 5-aminolevulinic-acid-induced photochemotherapy.

The ability of endogenously synthesized protoporphyrin IX (PpIX) to damage Chinese hamster lung fibroblasts of the line V79 by exposure to light was examined. This treatment induced reduction of cellular ATP, GTP, of the NADH/NAD+ ratio and of oxygen consumption. The present results indicate a close relationship between inhibition of respiration of irradiated cells and their ability to survive, e.g. 1 min of light exposure induced 90% inhibition of oxygen consumption and inactivation of approximately 95% of the cells, while the cellular content of ATP was reduced by only 15%. This indicates that the mitochondria are one of the primary targets of 5-aminolevulinic acid (ALA)-mediated photochemotherapy (PCT). In the present study, ALA-PCT was combined with the modulators of the glycolysis and the respiration chain, levamisole (LEV) and lonidamine (LND). A synergistic effect of combining ALA-PCT with non-toxic concentrations of LND was observed when LND was given prior to light exposure. This synergism was observed despite a substantial LND-induced inhibition of PpIX formation. At increasing doses of LND (>0.15 mM) the combination treatment becomes less efficient. This is due to the inhibition of PpIX synthesis induced by LND. A synergistic effect of ALA-PDT and LEV was found when LEV was given prior to light exposure. This was at least partly due to an LEV-stimulated effect on ALA-induced PpIX formation. However, it is not clear from the present results whether LEV may perturb energy metabolism in V79 cells since LEV alone did not reduce the energy charge or the NADH/NAD+ ratio. When LEV or LND were given after ALA-PCT, these 2 treatment modalities acted in an additive or slightly synergistic manner.

Aminolevulinic Acid↗
PubMed1996

Induction and repair of DNA damage in UV-irradiated human lymphocytes. Spectral differences and repair kinetics.

The alkaline elution assay has been employed to study the induction and repair kinetics of DNA damage in human lymphocytes after irradiation with biologically relevant doses of UVB (297 and 302 nm) or UVA (365 nm) radiation. At 365 nm, when the predominant lesions are single-strand breaks, the rate of lesion induction was 1.5 x 10(-3) per 10(8) Da per kJ m-2. The number of breaks decayed with a half-life of about 50 min after a dose of 20 kJ m-2. In the UVB region, cyclobutyl pyrimidine dimers and 6-4 photoproducts are formed, both of which are repairable via the nucleotide excision repair pathway. By using repair inhibitors, the rate of induction of such lesions at 297 and 302 nm was found to be 0.07 per 10(8) Da per J m-2. Lesions were removed with a half-life of about 100 min. Mathematical modelling of the excision repair process revealed a time-dependent polymerization-ligation rate: after an initial lag phase the polymerization-ligation rate increased, reaching 50% of its maximum rate at 80-100 min after the start of repair incubation. This course of development might be due to a damage-associated regulation of DNA precursors synthesis.

Cell Survival↗
PubMed1996

The influence of iron chelators on the accumulation of protoporphyrin IX in 5-aminolaevulinic acid-treated cells.

Human adenocarcinoma cells of the line WiDr and Chinese hamster lung fibroblasts of the line V79 were treated with 5-aminolaevulinic acid (5-ALA) and exposed to light. The effects of the iron chelators ethylenediaminetetraacetic acid (EDTA) and desferrioxamine (DEF) were assessed. Both cell lines were treated with various concentrations of 5-ALA in the presence or absence of the iron chelators for 4 h in serum-free medium. The accumulation of protoporphyrin IX (PpIX) reached a maximum level at 1 mM 5-ALA in WiDr cells [280 ng PpIX (mg protein x 4 h-1] and at 0.1 mM 5-ALA in V79 cells [55 ng PpIX (mg protein x 4 h)-1]. PpIX was the only fluorescing porphyrin in these cells after 5-ALA treatment alone or in combination with the chelators. The iron chelators did not influence the intracellular localisation pattern of PpIX in 5-ALA-treated cells. While both chelators enhanced the accumulation of PpIX in 5-ALA-treated cells, DEF was found to be superior at equal concentrations. A linear relationship between the applied concentration of DEF and the DEF-induced increase in PpIX accumulation was observed in double-reciprocal plots. The intercepts of the regression lines with the ordinate indicate that the ferrochelatase is saturated with PpIX when the 5-ALA concentration exceeds 0.3 mM and 0.05 mM in WiDr and V79 cells respectively. The DEF-induced enhancement of PpIX accumulation in 5-ALA-treated cells was cell line and 5-ALA concentration dependent. At a 5-ALA concentration inducing a maximum level of PpIX accumulation, inhibition of ferrochelatase activity enhanced the PpIX accumulation 3- and 1.4-fold in V79 and WiDr cells respectively. The relative gain in PpIX accumulation increased with decreasing concentration of 5-ALA. In cells treated with the lowest concentrations of 5-ALA used in this study, DEF enhanced PpIX accumulation 44- and 3.5-fold in V79 and WiDr cells respectively. The iron chelator-induced increase in cellular PpIX accumulation was followed by a similar increase in sensitivity to photoinactivation. The ferrochelatase inhibitor dihydropyridine 3,5-diethoxycarbonyl-1,4-dihydrocollidine reduced the accumulation of PpIX in both cell lines.

Adenocarcinoma↗
PubMed1996

Phototoxicity due to sulphonamide derived oral antidiabetics and diuretics: investigations in a cell culture model.

A number of sulphonamide-derived oral antidiabetics (chlorpropamide, glibenclamide, glipizide, gliquidone, glymidine, tolazamide and tolbutamide) and diuretics (bemetizide, bendroflumethiazide, benzylhydrochlorothiazide, bumetanide, butizide, chloratalidone, furosemide, hydrochlorothiazide, hydroflumethiazide, indapamide, piretanide, polythiazide, trichlormethiazide and xipamide) were investigated for phototoxicity in a cell culture model. Cell death dependent on ultraviolet A fluence and test substance concentration was observed in the presence of the oral antidiabetics glibenclamide and gliquidone, as well as the diuretics bemetizide, bendroflumethiazide, benzyl-hydrochlorothiazide, bumetanide, butizide, hydrochlorothiazide, hydroflumethiazide, piretanide, polythiazide and trichlormethiazide. Bendroflumethiazide was phototoxic at 5x10(-5) M and higher concentrations, bemetizide, benzylhydrochlorothiazide, bumetanide and hydroflumethiazide were phototoxic at 2.5x10(-4) M and higher concentrations, and the oral antidiabetics glibenclamide and gliquidone as well as the diuretics butizide, hydrochlorothiazide, piretanide, polythiazide and trichlormethiazide were phototoxic at 5(-4) M and higher concentrations. Electron microscopic investigations showed swelling of mitochondria and endoplasmic reticulum as well as aggregation of euchromatin when the cells were irradiated in the presence of photosensitizers.

Administration, Oral↗
PubMed1995

Uptake, localization, and photodynamic effect of meso-tetra(hydroxyphenyl)porphine and its corresponding chlorin in normal and tumor tissues of mice bearing mammary carcinoma.

By using a chemical extraction assay and confocal laser scanning fluorescence microscopy, the kinetic patterns of uptake, elimination, and localization of meso-tetra(hydroxyphenyl)porphine (m-THPP) and its corresponding chlorin (m-THPC) in tumors and various normal tissues of female C3D2/F1 mice bearing CaD2 mammary carcinoma were studied after an i.p. injection of either 5 mg/kg body weight of m-THPP or 1 mg/kg body weight of m-THPC. Moreover, the histological and ultrastructural alterations of the tumors were evaluated after photodynamic therapy (PDT) with m-THPP or m-THPC. The PDT efficacy with m-THPP and m-THPC was also compared. Both m-THPP and m-THPC had a similar kinetic pattern of distribution in the tumors and most normal tissues examined. The concentrations of the dyes in the tissues peaked at 24-48 h after injection. The peak values of the uptake of m-THPP by the tissues were found to decrease in the following order: spleen > urinary tract > kidney > liver > lung > tumor > heart > skin > muscle > brain. However, higher concentrations of m-THPC were taken up by the tumors than by most of the normal tissues studied except for the liver, urinary tract, and skin. m-THPP was mainly localized in the stroma of the tumors, whereas m-THPC was distributed in both vascular interstitium and neoplastic cells of the tumors. Morphological studies showed that PDT with m-THPP resulted in destructive changes in the microvasculature of the tumors, whereas m-THPC-based PDT destroyed both vascular walls and tumor cells of the tumors. The m-THPP-PDT of the tumors was much less efficient than m-THPC-PDT of the tumors, although the dose of m-THPP used was five times higher than that of m-THPC. m-THPP and m-THPC have different efficiency of sensitizing tumors to photodestruction, although they are similar with respect to hydrophobicity. This is likely due to the differences in their intratumoral localization patterns and in their absorption spectra.

Animals↗
PubMed1995

The influence of the cysteine protease inhibitor L-trans-epoxysuccinyl-leucyl amido(4-guanidio)butane (E64) on photobiological effects of tetra(4-sulfonatophenyl)porphine.

Human cervix carcinoma cells of the line NHIK 3025 were exposed to light after 18 h incubation with tetra(4-sulfonatophenyl)porphine (TPPS4) in the absence or presence of the cysteine protease inhibitor L-trans-epoxysuccinyl-leucyl amido(4-guanidino)butane (E64) followed by 1 h in sensitizer-free medium. E64 changed the photochemical properties of TPPS4 in NHIK 3025 cells, i.e., TPPS4 fluorescence yield was enhanced 2.5-fold and photochemically induced lysosomal rupture and loss of cell bound TPPS4 were inhibited. Additionally, E64 slightly (10%) reduced the sensitivity of the NHIK 3025 cells to photoinactivation. This is not likely to be due to its inhibitory effect on protease activity, but correlates with its inhibition of lysosomal rupture. The present results indicate that the release of lysosomal cysteine proteases from the lysosomal compartments are of little or no importance in the photochemical inactivation of NHIK 3025 cells when TPPS4 is used as photosensitizer.

Carcinoma in Situ↗
PubMed1995

Binding of etiopurpurin and tin-coordinated etiopurpurin to human plasma proteins. Delivery in cremophore EL and dimethyl sulfoxide (paper II).

Purpurins are potent hydrophobic photosensitizers in vivo. Cremopfore EL is an important vehicle for the administration of hydrophobic drugs. Mode-delivery-effects on the binding of etiopurpurin (ET2) to human plasma (LDL, HDL, and high density proteins, HDP) is studied for delivery in CRMaq and in DMSO by ultracentrifugation. A similar study of SnET2 is available (Kongshaug et al., 1993) and has been extended. In the absence of plasma, only nonfluorescent ET2 entities (aggregates) were present, a portion of which moved unaffected by gravity (small aggregates), the remainder according to their densities (high density aggregates). Aggregated ET2 showed, at high salt density, similar positions and halfwidths in the gradient, and similar adsorption properties as the aggregates in plasma-containing samples. In CRMaq (1 mg CRM/ml) the adsorptive loss of the dye affected only marginally the binding of fluorescent monomeric ET2. In this mode (i) 20% of ET2 was bound as monomers, about 70% of which to CRM-modified LDL, most of the remainder to CRM-modified HDL; (ii) such HDL also marginally bound small aggregates; (iii) only monomeric ET2 was bound to CRM-modified LDL. In delivery in DMSO, aggregated ET2 (98% of ET2 in the gradient) converted, post centrifugally, into minor amounts of HDL-bound monomeric ET2; LDL-bound ET2 included monomers (about 50%) and small aggregates, mainly dimers. The percentage binding of SnET2 to HDP was independent of the concentrations of CRMaq and HDL. Plasma-bound small aggregates (such as dimers) and plasma-unbound high density aggregates (mean densities of 1.13-1.19 g/ml) were substantially present in the plasma-containing samples. There were mode-delivery-effects upon the yields and properties of aggregated ET2, and upon the yields of plasma-bound monomeric ET2. Monomeric ET2 showed a remarkably high percentage binding to LDL and was similarly distributed among the lipoproteins as is total cholesterol. There was little or no real mode-delivery-effect upon the distribution of monomeric ET2 among the plasma proteins. The affinity of CRM-modified LDL for SnET2 was similar to that of HDL plus HDP in native plasma.

Blood Proteins↗
PubMed1995

Separation of lipoproteins, albumin and gamma-globulin by single-step ultracentrifugation of human serum. Application. I: Binding of hematoporphyrin to human serum and to albumin.

Previous studies of the serum binding of the photosensitizer hematoporphyrin (Hp) have given widely different results. The serum binding of Hp is therefore further illuminated by experiment and discussion. Ultracentrifugal separation of serum is improved and applied to study the binding of Hp to human serum and HSA. The observed distribution of Hp among the serum proteins is compared with the distribution expected from available association constants for Hp binding with individual proteins. The lipoprotein classes and the two major high density proteins (HDP), albumin and gamma-globulin, were separated in a NaCl-KBr gradient by single spin ultracentrifugation (SW 40; 30,000 rpm). HSA- and HDP-bound Hp were similarly distributed in the centrifuged gradient. Centrifugation of Hp-doped HSA separated the unbound Hp (75%) and the HSA-bound Hp (25%). The present association constant for the Hp-HSA complex (10(3)/M) was much lower than earlier published ones (10(6)/M) found by other techniques. The association of Hp with HDP in serum was much stronger than the association of Hp with the isolated HSA (electrophoretic grade). The estimated ratio of HSA-bound to LDL-bound HP in serum was at least 25 times larger than the experimental value. The percentage of LDL-bound Hp decreased with increasing Hp concentration. The serum binding of Hp is the same as that found previously using another rotor and another salt gradient (70.1 Ti, 70,000 rpm, NaCl-CsCl). LDL has high-affinity-low-capacity binding sites for Hp. HSA is the major HDP protein that binds Hp in human serum. The strength of the HSA-Hp complex may depend on the batch of HSA used and upon the absence/presence of other proteins. Proteins may interact in serum in manners that affect the binding of certain drugs. Neither the type of gradient salt nor the field of gravity affected the serum binding of Hp.

Blood Proteins↗
PubMed1995

Binding of etiopurpurin to human plasma proteins. Delivery in cremophor EL and dimethyl sulphoxide. III.

Binding of the photosensitizer etiopurpurin (ET2) to human plasma was assessed, using conditions that would yield a high percentage of ET2 in the form of LDL-bound monomers which may favor photosensitizer tumor localization. Two delivery systems, Cremophor EL (CRM) and dimethyl sulphoxide (DMSO), were used. The binding of ET2 to CRM-modified lipoproteins was compared to the binding of the dye to the native proteins using delivery in DMSO. Plasma-bound monomers and unbound high density aggregates were shown to coexist. The density and rate of formation of the dye aggregates were correlated. The aggregates formed by delivery in DMSO could be partially converted into plasma-bound monomeric ET2. There was no mode-delivery-effect upon the distribution of monomeric ET2 among the plasma proteins. 70% of monomeric ET2 was bound to LDL and most of the remainder to HDL. In delivery in DMSO the yield of LDL-bound dye monomers (up to 30% of added ET2) increased with decreasing concentration of ET2 in the delivery solution and with increasing time of incubation (< or = 48 hr). Long incubation also induced changes in the densities of LDL and HDL. The yields of LDL-bound monomers (up to 40%) increased with increasing concentration of CRM-bound ET2. High yields of LDL-bound monomers were obtained using both modes of delivery. Although the aggregates associated with the two modes of delivery had different properties. The change in lipoprotein composition might be involved in the conversion of aggregates into plasma-bound monomers.

Adsorption↗
PubMed1995

Anti-tumour activity of photodynamic therapy in combination with mitomycin C in nude mice with human colon adenocarcinoma.

The interaction of photodynamic therapy (PDT) and a chemotherapeutic drug, mitomycin C (MMC), was investigated using WiDr human colon adenocarcinoma tumours implanted on Balb/c athymic nude mice. The WiDr tumours were treated with PDT alone, MMC alone or with both. It was found that the combined treatment produced a greater retardation in the growth of the WiDr tumour than monotherapy with MMC or PDT. The synergistic effect was especially prominent when PDT was used in combination with a low dose of MMC (1 mg kg-1), since treatment of 1 mg kg-1 MMC alone had no effect on the tumour. The anti-tumour activity of PDT was found to be increased with MMC of 5 mg kg-1. The response of normal skin on mice feet to PDT slightly greater when PDT was combined with 5 mg kg-1 MMC than when PDT was applied alone, while no detectable additional effect on skin photosensitivity was observed when PDT was combined with 1 mg kg-1 MMC. An enhanced uptake of Photofrin in tumours was found 12 h and 24 h after administration of MMC. The effect of MMC on the cell cycle distribution of cell dissociated directly from the tumours was studied. The results suggest that the increased susceptibility to photoinactivation of Photofrin-sensitised tumours may be due to MMC-induced accumulation of the tumour cells in S-phase.

Adenocarcinoma↗
PubMed1995

Correlation of distribution of sulphonated aluminium phthalocyanines with their photodynamic effect in tumour and skin of mice bearing CaD2 mammary carcinoma.

A chemical extraction assay and fluorescence microscopy incorporating a light-sensitive thermoelectrically cooled charge-coupled device (CCD) camera was used to study the kinetics of uptake, retention and localisation of disulphonated aluminium phthalocyanine (A1PcS2) and tetrasulphonated aluminium phthalocyanine (A1PcS4) at different time intervals after an i.p. injection at a dose of 10 mg kg-1 body weight (b.w.) in tumour and surrounding normal skin and muscle of female C3D2/F1 mice bearing CaD2 mammary carcinoma. Moreover, the photodynamic effect on the tumour and normal skin using sulphonated aluminium phthalocyanines (A1PcS1, A1PcS2, A1pcS4) and Photofrin was compared with respect to dye, dye dose and time interval between dye administration and light exposure. The maximal concentrations of A1PcS2 in the tumour tissue were reached 2-24 h after injection of the dye, while the amounts of A1PcS4 peaked 1-2 h after the dye administration. A1PcS2 was simultaneously localised in the interstitium and in the neoplastic cells of the tumour, whereas A1PcS4 appeared to localise only in the stroma of the tumour. The photodynamic efficiency (light was applied 24 h after dye injection at a dose of 10 mg kg-1 b.w.) of the tumours was found to decrease in the following order: A1PcS2 > A1PcS4 > Photofrin > A1PcS1. Furthermore, photodynamic efficacy was strongly dependent upon dye doses and time intervals between dye administration and light exposure: the higher the dose, the higher the photodynamic efficiency. The most efficient photodynamic therapy (PDT) of the tumour was reached (day 20 tumour-free) when light exposure took place 2 h after injection of A1PcS2 (10 mg kg-1). A dual intratumoral localisation pattern of the dye, as found for A1PcS2, seems desirable to obtain a high photodynamic efficiency. The kinetic patterns of uptake, retention and localisation of A1PcS2 and A1PcS4 are roughly correlated with their photodynamic effect on the tumour and normal skin.

Animals↗
PubMed1995

S phase arrest and induction of multinucleated cells after exposure to ultraviolet radiation.

The effects of UVA (365 nm) and UVB (297/302 nm) radiation on cellular proliferation, cell cycle progression, aneuploidy and multinucleus induction have been studied in two different fibroblast cell lines; V79 Chinese hamster lung fibroblasts and 3T3 Swiss albino mouse fibroblasts. UVA and UVB were found to inhibit proliferation of the cells in a fluence-dependent manner. This inhibition was due to a temporary accumulation of cells in the S phase of the cell cycle, as determined by flow cytometry of UV-irradiated V79 cells. The UVA- and UVB-induced S phase delay was observed a few hours after irradiation and by 48 h post-irradiation the cells had recovered from cell cycle arrest. For UVA, but not for UVB, the elongation of S phase was followed by a small accumulation of cells in the G2 phase. After exposure to UVA and a post-irradiation time long enough for the cells to recover from cell cycle arrest, a large proportion of the cells were polyploid, with two or more nuclei. Multinucleated cells were not, however, induced by UVB irradiation.

3T3 Cells↗
PubMed1995

Detection of UVR-induced DNA damage in mouse epidermis in vivo using alkaline elution.

Alkaline elution has been used to detect ultraviolet radiation (UVR)-induced DNA damage in the epidermis of C3H/Tif hr/hr mice. This technique detects DNA damage in the form of single-strand breaks and alkali-labile sites (SSB) formed directly by UVA (320-400 nm) or indirectly by UVB (280-320 nm). The latter induces DNA damage such as cyclobutane pyrimidine dimers and pyrimidine-pyrimidone (6-4)-photoproducts, which are then converted into transient SSB by cellular endonucleases, during nucleotide excision repair (NER). The irradiation system used had a spectral output similar in effect to solar UVR, with the UVB component inducing 94% of the edema response observed in mice. Consequently, the majority of SSB detected were those formed via NER of UVB-induced photoadducts. The number of SSB detected immediately after 8 kJ/m2 (2.7 minimum erythema doses determined at 48 h post-UVR [MED]) was low, indicating the formation of only small numbers of transient SSB. When DNA repair inhibitors hydroxyurea and 1-beta-D-arabinofuranosylcytosine were administered (intraperitoneally) to mice 30 min before UVR, they prevented sealing of the DNA SSB formed during NER. A four-fold increase in the number of SSB detected resulted, which was found to be linearly related to the UVR dose. The SSB induced by 2 kJ/m2 (less than an MED) were readily detected, with the ear showing lower numbers of SSB than the dorsum. When repair inhibitors were added post-UVR, the rate of formation of SSB declined rapidly with time of administration, reflecting repair of DNA lesions. After a UVR dose of 6 kJ/m2 (2 MED), 50% of the initial repair-dependent SSB had been removed after approximately 2 h in the ear and 4 h in the dorsum; no more SSB appeared to be incised by 24 h post-UVR. The technique described is an efficient and highly sensitive one for the quantification of SSB induced in UV-irradiated skin samples in vivo.

Animals↗
PubMed1995

Distribution of 5-aminolevulinic acid-induced porphyrins in noduloulcerative basal cell carcinoma.

Microscopic fluorescence photometry incorporating a light-sensitive thermo-electrically cooled charge-coupled device (CCD) camera was employed to investigate the fluorescence distribution of 5-aminolevulinic acid (ALA)-induced porphyrins in 22 patients with a total number of 52 noduloulcerative basal cell carcinomas (BCC) after topical ALA application with or without dimethylsulfoxide (DMSO)/ethylenediaminetetraacetic acid (EDTA) or after intravenous administration of ALA. Both localization patterns and amounts of ALA-induced porphyrins in the BCC were studied. The ALA-induced porphyrins were localized only in the superficial layers of the noduloulcerative BCC lesions after topical application of 20% ALA alone for 3 h. However, both the penetration of ALA into deep lesions and the production of the ALA-induced porphyrin fluorescence were increased after topical administration of 20% ALA and 20% DMSO/4% EDTA for 3 h. Prior treatment with 99% DMSO for 15 min further enhanced the ALA penetration into the BCC lesions after topical application of the ALA/DMSO/EDTA mixture and produced more ALA-induced porphyrins by a factor of about three compared with those treated with ALA alone. The penetration of ALA into the deep BCC lesions could also be increased by prolonging the time of topical application of 20% ALA/4% EDTA to 29-48 h (without DMSO). Intravenous injection of ALA led to a more homogeneous distribution of the ALA-derived porphyrins in the whole noduloulcerative BCC lesions.

Adult↗
PubMed1995

Combined treatment of ionizing radiation and photosensitization by 5-aminolevulinic acid-induced protoporphyrin IX.

The response of human colon adenocarcinoma cells of the line WiDr to the combined treatment of ionizing radiation and photosensitization by 5-aminolevulinic acid-induced protoporphyrin IX was assessed by a colony-forming assay. A dose of X rays inactivating approximately 50% of the cells was used. Seventy to 85% of the cells accumulated in S and G2 + M phase 12-24 h after such a treatment as measured by flow cytometry, while the distribution of cells in the phases of the cell cycle approached that of untreated cells 48 h after X-ray treatment. Cellular photosensitization was developed by endogenous synthesis of protoporphyrin IX (PPIX) from the precursor 5-aminolevulinic acid (5-ALA). This was performed by treating the cells with 1 mM 5-ALA for 4 h in a serum-free medium. The endogenous synthesis of PPIX increased with time after the cells had been subcultured, i.e. the ability of the cells to synthesize PPIX increased 1.5-2-fold within 48 h of incubation. This was not due to effects of trypsin on the cells. Photochemotherapy with 5-ALA was given 0-48 h after X rays. The combined cytotoxic effect was analyzed by an isobologram after correction of the survival curves for microcolony formation and differences in intracellular concentration of PPIX. The results indicate that 5-ALA PCT given 0-4 h after X rays acts slightly antagonistically while 5-ALA PCT given 12-48 h after X rays acts slightly synergistically.

Adenocarcinoma↗