RESUMEN
The aim is to investigate the radiosensitivity of noninfected cultured human glioma cells to ascertain that intracutaneously administered cells are viable enough to produce interferon-gamma but not able to proliferate. Cell cultures were established from five patients undergoing brain tumour surgery. By karyotyping, we found four malignant (three glioblastoma multiforme (GBM), one giant cell glioma) and one normal. The cells were irradiated with (137)Cs-gamma rays at absorbed dose levels of 0, 20, 40, 60, 80, 100 and 120 Gy. The fraction of viable cells was examined by MTT incorporation assay. The average of the data obtained from three GBM cell cultures was fitted to an exponential model. The parameters were: extrapolation number n=0.85+/-0.10, mean lethal dose D(0)=12.4+/-3.2 Gy and an additional uncertainty parameter deltaS=0.14+/-0.03. By setting deltaS=0, the corresponding values of the parameters were n=0.86+/-0.16 and D(0)=30.0+/-8.1 Gy. The rate of proliferation was examined by (3)H-thymidine incorporation. The average of the proliferation data obtained from three GBM cell cultures was fitted to an exponential model yielding n=0.943+/-0.005 and D(0)=5.8+/-0.5 Gy for deltaS=0.057+/-0.005, and by setting deltaS=0, n=1.00+/-0.02 and D(0)=8.4+/-1.6 Gy. No outgrowth of plated cells was observed after 4 weeks at an absorbed dose of 100 Gy. This absorbed dose is recommended for irradiation of 2 x 10(6) glioma cells used for clinical immunisation.
Asunto(s)
Neoplasias Encefálicas/patología , Supervivencia Celular , Terapia Genética/métodos , Glioblastoma/patología , Glioma/patología , Inmunoterapia , Interferón gamma/biosíntesis , Tolerancia a Radiación , División Celular , Radioisótopos de Cesio/uso terapéutico , Humanos , Esterilización/métodos , Timidina/metabolismo , Tritio , Células Tumorales CultivadasRESUMEN
The question of whether very weak low frequency magnetic fields can affect biological systems, has attracted attention by many research groups for quite some time. Still, today, the theoretical possibility of such an interaction is often questioned and the site of interaction in the cell is unknown. In the present study, the influence of extremely low frequency (ELF) magnetic fields on the transport of Ca(2+) was studied in a biological system consisting of highly purified plasma membrane vesicles. We tested two quantum mechanical theoretical models that assume that biologically active ions can be bound to a channel protein and influence the opening state of the channel. Vesicles were exposed for 30 min at 32 degrees C and the calcium efflux was studied using radioactive (45)Ca as a tracer. Static magnetic fields ranging from 27 to 37 micro T and time varying magnetic fields with frequencies between 7 and 72 Hz and amplitudes between 13 and 114 micro T (peak) were used. We show that suitable combinations of static and time varying magnetic fields directly interact with the Ca(2+) channel protein in the cell membrane, and we could quantitatively confirm the model proposed by Blanchard.
Asunto(s)
Calcio/metabolismo , Membrana Celular/metabolismo , Membrana Celular/efectos de la radiación , Campos Electromagnéticos , Modelos Biológicos , Spinacia oleracea/metabolismo , Spinacia oleracea/efectos de la radiación , Canales de Calcio/fisiología , Canales de Calcio/efectos de la radiación , Células Cultivadas , Simulación por Computador , Relación Dosis-Respuesta a Droga , Activación del Canal Iónico/fisiología , Activación del Canal Iónico/efectos de la radiación , Hojas de la Planta/metabolismo , Hojas de la Planta/efectos de la radiación , Dosis de RadiaciónRESUMEN
The purpose of this publication was to present and evaluate the methods for reference dosimetry in the epithermal neutron beam at the neutron capture therapy facility at Studsvik. Measurements were performed in a PMMA phantom and in air using ionization chambers and activation probes in order to calibrate the epithermal neutron beam. Appropriate beam-dependant calibration factors were determined using Monte Carlo methods for the detectors used in the present publication. Using the presented methodology, the photon, neutron and total absorbed dose to PMMA was determined with an estimated uncertainty of +/- 5.0%, +/- 25%, and +/- 5.5% (2 SD), respectively. The uncertainty of the determination of the photon absorbed dose was comparable to the case in conventional radiotherapy, while the uncertainty of the neutron absorbed dose is much higher using the present methods. The thermal neutron group fluence, i.e., the neutron fluence in the energy interval 0-0.414 eV, was determined with an estimated uncertainty of +/- 2.8% (2 SD), which is acceptable for dosimetry in epithermal neutron beams.