| 1. |
- Andersson-Engels, Stefan, et al.
(författare)
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Identification of brain tumours in rats using laser-induced fluorescence and haematoporphyrin derivative
- 1989
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Ingår i: Lasers in Medical Science. - 0268-8921. ; 4:4, s. 241-249
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced fluorescence has been used for the identification of brain tumours in rats, which have been previously given tumour-seeking haematoporphyrin derivative. A pulsed nitrogen laser (λ=337 nm) was used in conjunction with an optical multichannel analyzer. For both inoculated RG-2 and TCVC rat-brain-tumour models, the blue autofluorescence was strongly reduced in the tumour compared with normal brain tissue, and at the same time the characteristic red-drug signal increased. The contrast between tumour and normal tissue was strongly enhanced by forming the ratio between the two signals. Implications for possible improvement of tumour delineation in brain tumour surgery are discussed.
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| 2. |
- Andersson-Engels, S., et al.
(författare)
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Tissue diagnostics using laser-induced fluorescence
- 1989
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Ingår i: Berichte der Bunsengesellschaft für Physikalische Chemie. - : Wiley. - 0005-9021. ; 93:3, s. 335-342
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Tidskriftsartikel (refereegranskat)abstract
- We have performed extensive investigations of laser-induced fluorescence in animal and human tissue aimed at instant tissue characterization. Autofluorescence, as well as specific fluorescence from HPD/DHE and other photosensitizers, has been utilized. The studies have been focused on the demarcation of malignant tumours and atheroscleortic plaques. A nitrogen laser or an excimer-pumped dye laser was used to induce fluorescence, which was analysed with an intensified optical multichannel system. A fibre-optic sensor system was developed for the clinical work. Multi-colour fluorescence imaging has also been demonstrated along a line and equipment for two-dimensional imaging is being constructed. Dimensionless spectroscopic functions, which are not affected by factors that are clinically uncontrollable have been employed for optimum tissue discrimination. The investigations have so far been performed in a time-integrated mode, but time-resolved studies are now being initiated to fully exploit the diagnostic power of tissue laser-induced fluorescence. In addition to a presentation of our own work a brief review of tissue fluorescence studies performed by other groups is also given.
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| 3. |
- Andersson, P. S., et al.
(författare)
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TISSUE CHARACTERIZATION USING LASER-INDUCED FLUORESCENCE.
- 1987
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Ingår i: Conference on Lasers and Electro-Optics. - 0936659491 ; 14, s. 46-48
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Konferensbidrag (refereegranskat)abstract
- In cancer tumor detection, tissue autofluorescence and characteristic features of injected hematoporphyrin derivative (HPD) can be utilized. The authors have studied the importance of the excitation wavelength for the achievable contrast between tumor and surrounding tissue using a rat tumor model. They have also compared the relative merits of two HPD preparations for tumor fluorescence detection. The real-time capability of the fluorescence technique is discussed.
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| 4. |
- Ceberg, Crister, et al.
(författare)
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Enhanced boron uptake in RG 2 rat gliomas by electropermeabilization in vivo--a new possibility in boron neutron capture therapy
- 1994
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Ingår i: Anti-Cancer Drugs. - 0959-4973. ; 5:4, s. 463-466
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Tidskriftsartikel (refereegranskat)abstract
- Accumulation of boron in tumor tissue is an indispensable requirement for boron neutron capture therapy and it is important that the uptake is as high as possible. In this work we have studied the influence of electropermeabilization in vivo on the uptake of boron in normal and RG 2 glioma bearing Fischer 344 rats. Two different boron compounds, a sulfhydryl boron hydride (BSH) and a boronated porphyrin (BOPP), have been investigated. The rats were infused intravenously during 5 min with 175 micrograms BSH/g body weight or 12 micrograms BOPP/g body weight. Two electrodes were placed 5 mm apart in the brain and electropermeabilization was performed with eight square 400 V pulses at 4 and 7 min after the end of the infusion. After 6 h the animals were killed, and the boron content in the tumors and the surrounding brain was measured with neutron-activated autoradiography. In electropermeabilized healthy animals the BOPP uptake was low and limited to the electrode lesions, whereas BSH was spread extensively throughout the hemisphere. Rats with gliomas showed doubled (BOPP) to 10-fold (BSH) uptake of boron in the tumor when electropermeabilization was performed as compared with untreated animals. We conclude that electropermeabilization in the future may provide an interesting possibility to increase the uptake of certain boron compounds before neutron capture therapy.
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| 5. |
- Engstrom, P.E., et al.
(författare)
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Electrically mediated drug delivery for treatment of an adenocarcinoma transplanted into rat liver
- 2001
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Ingår i: Anticancer research. - 1791-7530. ; 21:3B, s. 1817-1822
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In this study, electrochemotherapy (ECT), i.e. tumour treatment based on local augmentation of intracellular drug delivery from short, intense electric pulses, was evaluated in rats with an adenocarcinoma implanted into the liver. Tumour response and concentrations of macrophages and T-lymphocytes (CD4 and CD8) in and around the tumour were measured.MATERIALS AND METHODS: Rats were treated with permeabilizing electric pulses, bleomycin, or both, eight days after implantation of the tumour, while one group received sham treatment.RESULTS: Treatment with electric pulses and bleomycin resulted in a significantly reduced lesion volume and 92% cure rate (12 out of 13, p<0.0002 compared to the other treatment groups). The highest concentration of CD8 lymphocytes was found in tumours treated with electric pulses and bleomycin. Macrophages were found mainly in tumours treated with electric pulses, with or without bleomycin.CONCLUSION: Electrochemotherapy using millisecond exponential pulses and bleomycin is efficient in a rat liver tumour model and appears to stimulate the host's immune system.
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| 6. |
- Engström, P, et al.
(författare)
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Distribution of bleomycin in a rat model
- 2000
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Ingår i: Electrochemotherapy, Electrogenetherapy, and Transdermal Drug Delivery : Electrically Mediated Delivery of Molecules to Cells - Electrically Mediated Delivery of Molecules to Cells. - New Jersey : Humana Press. - 9780896036062 - 9781592590803 ; 37, s. 92-285
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Bokkapitel (refereegranskat)abstract
- Bleomycin has, in the years of developing electrochemotherapy (ECT), proven to be an extremely potent drug for this cancer treatment modality and is also the most frequently applied chemical agent. It is of importance to investigate the pharmacokinetics of bleomycin under normal conditions and particularly in combination with ECT.
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| 7. |
- Engström, P E, et al.
(författare)
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A new antitumour treatment combining radiation and electric pulses
- 2001
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Ingår i: Anticancer research. - 0250-7005. ; 21:3B, s. 15-1809
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To investigate the antitumour effect of radiation in combination with electropermeabilization on subcutaneous rat glioma tumours.MATERIALS AND METHODS: Sub-optimal radiation treatment was administered separately or in combination with electric pulses of high voltage to subcutaneous rat brain tumours. The treatment was repeated on four consecutive days and evaluated by TGD and microscopical examination. The tumours were stained for Factor VlII/von Willebrand Factor to investigate the effects on the tumour vasculature.RESULTS: Radiation and electric pulses applied concomitantly resulted in a cure rate of 67% (tumour free >80 days after treatment). Radiation-treated animals showed progressive disease. Histological and immunohistochemical examination of electric impulse-treated tumours showed instant and severe deteriorating effects on tumour vasculature.CONCLUSION: A distinct antitumour effect of the combined treatment of electric pulses and radiation treatment was observed. We believe that the tumouricidal effect arises from destruction of the tumour vasculature but also from DNA related damage from reactive oxygen formed by the electric pulses and the radiation treatment.
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| 8. |
- Engström, P E, et al.
(författare)
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Studies of in vivo electropermeabilization by gamma camera measurements of (99m)Tc-DTPA
- 1999
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Ingår i: Biochimica et Biophysica Acta. - 0006-3002. ; 1473:2-3, s. 8-321
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Tidskriftsartikel (refereegranskat)abstract
- A protocol was developed to study the drug uptake from in vivo electropermeabilization at different settings of parameters influencing the uptake efficiency. Radiolabelled diethylenetriaminepentaacetic acid (DTPA) was used to trace the distribution and internalization of a hydrophilic drug after in vivo electropermeabilization. Skeletal muscle tissue in rat was treated with permeabilizing electric pulses before or after intravenous administration of (99m)Tc-DTPA. The drug accumulation in the treated volume was subsequently evaluated with a scintillation camera. The dependence of uptake on field strength and duration of the applied electric pulses was investigated for exponentially decaying pulses and square wave pulses. Further, the uptake dependence on time interval between injection and pulsation was studied as well as the uptake dependence on the number of pulses applied in a single electropermeabilization treatment. Dynamic gamma camera studies were performed to quantify the time scale of the drug uptake in electropermeabilized tissue.
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| 9. |
- Martens, L., et al.
(författare)
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Electromagnetic field calculations used for exposure experiments on small animals in TEM-cells
- 1993
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Ingår i: Bioelectrochemistry and Bioenergetics. - : Elsevier BV. - 0302-4598. ; 30:C, s. 73-81
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional electromagnetic calculations for loaded transverse electromagnetic (TEM) transmission cells are presented. Based on those calculations a prediction of the perturbation of the standard uniform field in the TEM-cell, due to the scattering by inhomogeneous structures placed inside the cell cavity, is given. The influence of the dimensions of a lossy structure and its position in the TEM-cell on its absorption of the electromagnetic fields is presented. Knowing the perturbation of the uniform field is important for good interpretation of the biological experimental results.
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| 10. |
- Persson, B. R. R., et al.
(författare)
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Tissue response of radiation therapy assessed by electrical impedance spectroscopy (EIS) in subcutaneous tumours in rats.
- 2021
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Ingår i: Acta Scientiarum Lundensia. - 1651-5013. ; 2021:002, s. 1-19
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The present investigation aims to evaluate the possibility of using bio-impedance spectrometry to measure tumour and tissue response to radiation therapy. Bio -impedance measurements performed with CythorLab™ equipped with a signal generator with a known high output impedance and signal measuring device able to measure the voltage applied by the generator. The control unit triggers the signal generator that generates an MLS-sequence. The same control unit process the signal that simultaneously measured by the voltage-recording device. An FFT analysis performed to obtain the magnitude of the real and imaginary parts of the impedance spectrum. The effect of various numbers of fractions of radiation therapy (RT) on the impedance measured with surface plate electrodes investigated in male rats of the Fischer-344 strain with rat glioma N32 tumours implanted subcutaneously on the flank. Tumours produced by injecting 100 000 N32 tumour cells just below the skin. Tumours were treated about four weeks after injection when a solid tumour has developed with a diameter of 1-1.5 cm. Before treating the tumours, animals anaesthetised, and the fur over the tumour shaven and carefully to ensure good electrical contact between electrodes and skin. The electrical impedance dispersion of tissue modelled with an RC-equivalent circuit from which collective impedance parameters corresponding the cell membranes, Rm Cm intra -cellular resistance, Ri, and extra-cellular resistance R0.Impedance measurements performed over a tumour before irradiation to 5 Gy and every minute after the irradiation up to 8 minutes. A slight increase of impedance, and with a time constant of 10 minutes. The growth might be due to dry skin after irradiation or a decrease of tumour vascularity during the treatment. The capacitance of the cell membrane related to the characteristic frequency fc does not change significantly before and after radiation exposure. A special parameter, the "Loss Change Index" (LCI) which defined to vary between zero if there is no change in the phase angle and one if the phase angle after exposure approach zero. LCI reach an extreme at the characteristic frequency. The LCI value recorded at the characteristic frequency fc varied with the accumulated absorbed dose and fitted to a sigmoidal dose/response relationship.
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