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1.
Indian J Biochem Biophys ; 1997 Aug; 34(4): 379-84
Artículo en Inglés | IMSEAR | ID: sea-26398

RESUMEN

Mechanism of merocyanine 540 (MC540) mediated photosensitization in glioblastoma (U-87MG) and neuroblastoma (Neuro 2a) cells was investigated. Photoinduced lipid peroxidation was measured in the presence of mechanistic probes-deuterium oxide (D2O), sodium azide, superoxide dismutase (SOD), mannitol and sodium benzoate. In both the types of cells, the photoinduced lipid peroxidation was enhanced in D2O whereas it showed inhibition in the presence of sodium azide. SOD also inhibited the lipid peroxidation while sodium benzoate and mannitol had no effect. These results suggest that photosensitization of U-87MG and Neuro 2a cells by MC 540 involves both type I (free radical mediated) and type II (singlet oxygen mediated) mechanisms.


Asunto(s)
Animales , Ensayos de Selección de Medicamentos Antitumorales , Glioblastoma/tratamiento farmacológico , Humanos , Peroxidación de Lípido/efectos de los fármacos , Ratones , Neuroblastoma/tratamiento farmacológico , Fármacos Fotosensibilizantes/uso terapéutico , Pirimidinonas/uso terapéutico , Células Tumorales Cultivadas
2.
Indian J Exp Biol ; 1995 Oct; 33(10): 721-4
Artículo en Inglés | IMSEAR | ID: sea-58493

RESUMEN

Effect of hematoporphyrin derivative (HpD) and light on sulfhydryl (SH) groups in brain tumor cells was studied. Sulfhydryl groups were measured by 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) and a fluorescent probe 3,4-maleimidylphenyl-4-methyl-7-diethylaminocoumarin (CPM). Incubation of cells with HpD in dark resulted in the loss of DTNB as well as CPM reactive SH groups. After 2 hr of incubation DTNB reactive SH groups showed a negligible change while a continuous decrease was observed in CPM reactive SH groups. Cells treated with HpD showed a further degradation of SH groups upon light irradiation. A comparison of cytotoxicity and SH groups under identical conditions showed that blockage of SH groups by HpD binding is not leathal to the cells where as photoinduced cell death was observed on photodegradation of SH groups.


Asunto(s)
Neoplasias Encefálicas/tratamiento farmacológico , Derivado de la Hematoporfirina/farmacología , Humanos , Fotoquimioterapia , Compuestos de Sulfhidrilo/efectos de la radiación , Células Tumorales Cultivadas
3.
Indian J Biochem Biophys ; 1995 Aug; 32(4): 200-6
Artículo en Inglés | IMSEAR | ID: sea-27920

RESUMEN

Photodynamic action of hematoporphyrin derivative (HpD) on the plasma membrane of human glioblastoma U-87MG cells was investigated using lipid and protein specific fluorescent probes trimethylammonium-1,6-diphenyl 1,3,5-hexatriene (TMA-DPH) and N-(1-pyrene)-maleimide (PM) respectively. Steady state anisotropy, decay time and time dependent anisotropy of these probes in U-87MG cells were measured. Light irradiation caused an increase in the steady state anisotropy of TMA-DPH in cells treated with HpD; however, no change in decay time was observed. Time dependent anisotropy measurements were performed and the data were analyzed using wobbling in cone model. A decrease in the rotational relaxation time (phi) as well as the cone angle (theta(c)) and an increase in the order parameter (S) of TMA-DPH were observed on photosensitization of cells. A decrease in the order parameter (S) of TMA-DPH were observed on photosensitization of cells. A decrease in the steady rate anisotropy and the rotational relaxation time (phi) of PM and enhancement in the lipid peroxidation were also observed. Our results show that the photodynamic action of HpD increases the order in the lipid bilayer and the mobility of the proteins in the plasma membrane of cells.


Asunto(s)
Antineoplásicos/uso terapéutico , Membrana Celular/efectos de los fármacos , Glioblastoma/tratamiento farmacológico , Derivado de la Hematoporfirina/uso terapéutico , Humanos , Fotoquimioterapia , Fármacos Fotosensibilizantes/uso terapéutico , Espectrometría de Fluorescencia , Células Tumorales Cultivadas
4.
Indian J Exp Biol ; 1994 Nov; 32(11): 763-6
Artículo en Inglés | IMSEAR | ID: sea-58286

RESUMEN

Plateau phase glioblastoma (U 87MG) cells were found more photosensitive than the exponentially growing cells. In both phases of growth, the photosensitivity showed further enhancement on incubating the cells with HpD for longer duration. Plateau phase cells accumulated more HpD than exponential phase cells for shorter duration of incubation with HpD, however, for longer duration of incubation, the amount of drug uptake was almost the same in both phases of growth. Fluorescence spectra of cell bound HpD showed a difference in spectral intensity distribution in exponential and plateau phase cells. In exponential phase cells, the fluorescence maximum of cell bound HpD was at 615 nm whereas in plateau phase cells the same was at 636 nm.


Asunto(s)
Neoplasias Encefálicas/metabolismo , Ciclo Celular/fisiología , Glioblastoma/metabolismo , Derivado de la Hematoporfirina/metabolismo , Humanos
5.
Artículo en Inglés | IMSEAR | ID: sea-17306

RESUMEN

Binding and photodynamic action of merocyanine 540 (MC540) has been studied in glioma (U-87MG) and neuroblastoma (Neuro 2A) cells as a function of dye concentration, incubation time of cells with MC540 and growth phase of cells. In the plateau phase, U-87MG cells accumulated more MC540 as compared to exponentially growing cells, whereas in Neuro 2A cells the opposite effect was observed. Exponentially growing U-87MG cells were more photosensitive than plateau phase cells. However, the photosensitivity of Neuro 2A cells was not dependent on the growth phase. Thus, MC540 mediated photosensitization may be useful for photodynamic therapy of brain tumours.


Asunto(s)
Colorantes Fluorescentes , Glioma/tratamiento farmacológico , Neuroblastoma/tratamiento farmacológico , Fotoquimioterapia , Fármacos Fotosensibilizantes/farmacología , Pirimidinonas/farmacología , Coloración y Etiquetado , Células Tumorales Cultivadas
6.
Artículo en Inglés | IMSEAR | ID: sea-18405

RESUMEN

The relationship between photosensitizer concentration, light dose, incubation time and cellular damage in human cerebral glioma cells in culture, was studied. Cells were incubated with hematoporphyrin derivative (Hpd) for different durations at 37 degrees C. Immediately after specified period of incubation, cells were irradiated with white light. Cellular damage was assessed by colony forming ability of cells. A progressive reduction in the surviving fraction was observed as a function of drug and light dose. The survival curves were of exponential nature with an initial shoulder. The cell survival was found to be dependent on the time of incubation with Hpd. These results suggest that photodynamic cellular damage can be enhanced at low drug and light dose by increasing the incubation time.


Asunto(s)
Neoplasias Encefálicas/patología , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Relación Dosis-Respuesta en la Radiación , Glioma/patología , Derivado de la Hematoporfirina , Fotorradiación con Hematoporfirina/métodos , Hematoporfirinas/farmacología , Humanos , Factores de Tiempo , Células Tumorales Cultivadas/efectos de los fármacos
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