11. A web-application that extends functionality of medical device for tumor treatment by means of electrochemotherapyIvan Pavlović, Peter Kramar, Selma Čorović, David Cukjati, Damijan Miklavčič, 2004, original scientific article Abstract: Electrochemotherapy (ECT) is a novel method for efficient tumor treatment in clinical environment. It combines local drug delivery and application of shorthigh voltage pulses, which permeabilize the plasma membrane by electroporation. Drug can enter only the cells with permeabilzed membrane. Recently, medical device CliniporatorTM for controlled electroporation was developed. Here, we present a web-application that extends the functionality of this medical device. The aim of the application is to collect, store and toallow the analysis of every ECT application using this medical device. The application helps transferring data collected by devčce during the electroporation process to the central database, and enables filling of medical records through the web forms. The application is based on technologies ASP, HTML, Flash, JavaScript, XML and others. The application main advantages are easy and rapid data access, scalability and independence of client computer operating system as well as easy application debugging and upgrading.
Keywords: neoplasms- drug therapy, drug delivery systems, elektroporation instrumentation
Published in DiRROS: 07.02.2024; Views: 172; Downloads: 44
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12. Tumor blood flow modifying effects of electrochemotherapy : a potential vascular targeted mechanismGregor Serša, Maja Čemažar, Damijan Miklavčič, 2003, original scientific article Abstract: Background. The aim of this study was to determine the tumor blood flow modifying, and potential vascular targeted effect of electrochemotherapy with bleomycin or cisplatin. Materials and methods. Electrochemotherapy was performed by application of short intense electric pulses to the tumors after systemic administration of bleomycin or cisplatin. Evaluated were antitumor effectiveness of electrochemotherapy by tumor measurement, tumor blood flow modifying effect by Patent blue staining technique, and sensitivity of endothelial and tumor cells to the drugs and electrochemotherapy by clonogenicity assay. Results. Electrochemotherapy was effective in treatment of SA-1 tumors in A/J mice resulting in substantial tumor growth delay and also tumor cures. Tumor blood flow reduction following electrochemotherapy correlated well with its antitumor effectiveness. Virtually complete shut downof the tumor blood flow was observed already at 24 h after electrochemotherapy with bleomycin whereas only 50% reduction was observed after electrochemotherapy with cisplatin. Sensitivity of human endothelial HMEC-1 cells to electrochemotherapy suggests a vascular targeted effect for electrochemotherapy in vivo with bleomycin as well as with cisplatin. Conclusion. These results show that in addition to direct electroporation of tumor cells, other vascular targeted mechanisms are involved in electrochemotherapy with bleomycin or cisplatin, potentially mediated by tumorblood flow reduction, and enhanced tumor cell death as a result of endothelial damage by electrochemotherapy.
Published in DiRROS: 06.02.2024; Views: 127; Downloads: 31
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13. Cell electropermeabilization to small molecules in vitro : control by pulse parametersAlenka Maček Lebar, Damijan Miklavčič, 2001, original scientific article Abstract: A systematic study concerning the role of the different electric field parameters (pulse number, duration and amplitude) on electropermeabilization of DC3F cells to small molecules (propidium iodide) and on cell viability is presented. Cell permeabilization and viability dependence on the pulse amplitude was determined by twenty different sets of electrical parameters. The number of pulses varied between 1 and 64 and pulse duration between 20 micros and 1 ms. The most important parameter was the pulse amplitude because at triggered the electropermeabilization process and the process of cell death. Either in the case of electropermeabilization as well as in the case ofcell viability experiments, the parameter Uso (the pulse amplitude leading to permeabilization or to the death of 50% of cell population) was not changedif the set of electrical parameters consisted of more than 16 pulses. This was independent of the pulse duration. The efficiency of permeabilizationwas enhanced by using of longer pulses. Such a systematic study of the influence of different electric field parameters on electropermeabilization and cell viability may serve as a base for optimization of the electropermeabilization conditions for different applications.
Published in DiRROS: 25.01.2024; Views: 181; Downloads: 40
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14. First experience with a novel luminescence-based optical sensor for measurement of oxygenation in tumorsTomaž Jarm, Hotimir Lešničar, Gregor Serša, Damijan Miklavčič, 2001, original scientific article Abstract: Background. The purpose of this preliminary study was to evaluate a novel luminescence-based fiber-optic sensor (OxyLite system) for the measurement of partial pressure of oxygen (pO2) in tumors and for the detection of changes inpO2 as a function of time. The new method was used simultaneously with the laser Doppler flowmetry method for the measurement of relative tissue perfusion. Materials and methods. Blood perfusion and pO2 were measured continuously via fiber-optic sensors inserted into SA-1 tumors in anesthetizedAžJ mice. The changes in blood flow and oxygenation of tumors wereinduced by transient changes of the parameters of anesthesia and by injection of a vasoactive drug hydralazine. Results. Both optical methods usedin the study successfully detected the induced changes in blood flow and pO2. The measurements of pO2 were well correlated with measurements of microcirculatory blood perfusion. In the majority of pO2 measurements, we observed an unexpected behavior of the signal during the stabilization processimmediately after the insertion of the probe into tumor. This behaviourof the pO2 signal was most probably caused by local tissue damage induced by the insertion of the probe. Conclusion. The novel luminescence-based optical oximetry can reliably detect local pO2 changes in tumors as a function of time but some aspects of prolonged pO2 measurement by this method require further investigation.
Keywords: sarcoma experimental, blood supply, laser-doppler flowmetry, oxygen, luminiscence
Published in DiRROS: 25.01.2024; Views: 181; Downloads: 43
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15. Electroporator for in vitro cell permeabilizationMarko Puc, Karel Flisar, Stanislav Reberšek, Damijan Miklavčič, 2001, original scientific article Abstract: The use of high voltage electric pulse technology, electroporation, in cell biology, biotechnology and medicine has attracted an enormous interest. Electroporation is a transient phenomenon that increases the permeability of cell plasma membrane. In the state of high permeability, the plasma membrane allows small and large molecules to be introduced into the cytoplasm, althoughthe cell plasma membrane represents a considerable barrier for them inits normal state. The effectiveness of electroporation depends on many parameters that can be divided into the parameters of the electric field and the parameters that define the state of cells and their surrounding i.e, temperature, osmotic pressure, etc. In this article, we present a prototype electroporator GT-1 for in vitro electropermeabilization that we have developed. Our electroporator offers a vast flexibility of parameters and can generate high and low voltage pulses, of which the latter ones are used for electrophoretic transfer of charged molecules through permeabilized cell plasma membrane.
Keywords: electroporation instrumentation methods, cell membrane permeabilization
Published in DiRROS: 25.01.2024; Views: 199; Downloads: 44
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16. Influence of hydralazine on interstitial fluid pressure in experimental tumors - a preliminary study : Vpliv hydralazina na tlak medcelične tekočine v poskusnih tumorjihBlaž Podobnik, Damijan Miklavčič, 2000, original scientific article Abstract: Background. Interstitial fluid pressure (IFP) has been recognised as the most important obstacle in macromolecular drug delivery to solid tumors. Our interest was to reduce differentialy tumor IFP with respect to IFP in surrounding and normal tissues in order to increase drug delivery to tumors aswell to increase tumor blood flow and potentialy tumor tissue oxygenation. In this preliminary study we used hydralazine, a longacting arterial vasodilator. Materials and methods. Measurements of interstitial fluid pressure were performed in vivo on CBA mice bearing SAF tumors using wick-in-needle technigue. Altogether eleven measurements were obtained on different animals with tumors of different size. Results. IFP in tumors after hydralazine administration was significantly lower than initial values in corresponding tumors. On average tumor IFP decreased for 33 % from initial value. On the contrary, no change in IFP in normal tissue was observed after hydralazine administration. Also, after injection of physiological saline instead of hydralazine there was no change in IFP neither in tumors nor in muscle. The results of our preliminary study on the effect of hydralazine on IFP in SAF tumor model is in accordance to previously reported studies. The decrease in tumor IFP was only observed in tumors, but not in muscle and surrounding subcutis. Conclusion. Hydralazine is a vasodilator which is capable of decreasing tumor IFP, reproducibly and with favorably long lasting dynamics.
Keywords: sarcoma, experimental drug therapy, hydralazine, extracellular space, interstitial fluid pressure, manometry
Published in DiRROS: 23.01.2024; Views: 194; Downloads: 50
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19. Study of blood perfusion with patent blue staining method in LPB fibrosarcoma tumors in immuno-competent and immuno-deficient mice after electrotherapy by direct currentTomaž Jarm, Dong Jian An, Jean Belehradek, Lluis M. Mir, Gregor Serša, Maja Čemažar, Tadej Kotnik, Jani Pušenjak, Damijan Miklavčič, 1997, original scientific article Published in DiRROS: 16.01.2024; Views: 156; Downloads: 35
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20. Electrochemotherapy with bleomycin : The first clinical experience in malignant melanoma patientsZvonimir Rudolf, Borut Štabuc, Maja Čemažar, Damijan Miklavčič, Lojze Vodovnik, Gregor Serša, 1995, original scientific article Keywords: melanoma therapy, bleomycin, electric stimulation therapy
Published in DiRROS: 15.01.2024; Views: 169; Downloads: 45
Full text (418,42 KB) |
