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Iskalni niz: "avtor" (Maja Čemažar) .

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Evaluation of shRNA-mediated gene silencing by electroporation in LPB fibrosarcoma cells
Suzana Vidic, Urška Kamenšek, Maja Čemažar, 2008, izvirni znanstveni članek

Povzetek: Background. Silencing oncogenes or other genes that contribute to tumor malignancy and progression offers a promising approach to treating cancer. Specific and efficient silencing of gene expression can be achieved by RNA interference (RNAi) technology using small interfering RNA (siRNA) or short hairpin RNA (shRNA). However, a major challenge in RNAi technology is effective delivery of interfering molecules into target cells. The aim of our study was to evaluate electroporation as a perspective method for efficient invitro transfection of LPB fibrosarcoma cells with plasmid DNA expressing shRNA. Methods. Induction of shRNA-mediated gene silencing by electroporation was determined by fluorescence microscopy, flow cytometry and western blot analysis. The effect of electroporation conditions on cell survival and proliferation was determined by clonogenic assay. Results and conclusions. Ourresults demonstrated that electroporation is a feasible and effective method for delivery of plasmid DNA expressing shRNA into cancer cells in vitro. Electrotransfection of murine LPB fibrosarcoma cells, continuously expressing green fluorescence protein - GFP (LPBGFP), with plasmid DNA encoding shRNA-GFP, reduced GFP expression, which was determined on the protein level, as well as by measurement of GFP fluorescence intensity. A pronounced reduction in GFP expression level was detected from the second to the fifth day after treatment. Moreover, the method is easy to perform and showed low cell damaging effects, which are the most important and preferential factors for further in vivo studies.
Objavljeno v DiRROS: 08.03.2024; Ogledov: 51; Prenosov: 15
.pdf Celotno besedilo (391,23 KB)

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Electrochemotherapy of tumours
Gregor Serša, Maja Čemažar, Damijan Miklavčič, Zvonimir Rudolf, 2006, pregledni znanstveni članek

Povzetek: Electroehemotherapy consists of chemotherapy followed by local application of electrie pulses to the tumour to increase drug delivery into cells. Drug uptake can be inereased by electroporation for only those drugs whose transport through the plasma membrane is impeded. Among many drugs that have been tested so far, only bleomycin and cisplatin found their way from preclinical testing to clinical trials. In vitro studies demonstrated several fold inerease of their cytotoxicity after electroporation of cells. In vivo, electroporation of tumours after local or systemic administration of either ofthe drugs, i.e. electrochemotherapy, proved to be an effective antitumour treatment. In preclinical studies on several tumour models, electrochemotherapy either with bleomycin or cisplatin was elaborated and parameters for effective local tumour control were determined. In veterinary medicine, electrochemotherapy also proved to be effective in the treatment of primary tumours in cats, dogs and horses. In human clinical studies, electrochemotherapy was performed on the patients with progressive disease andaccessible tumour nodules of different malignancies. All clinical studies demonstrated that electrochemotherapy is an effective treatment for local tumour control in cancer patients.
Objavljeno v DiRROS: 15.02.2024; Ogledov: 113; Prenosov: 31
.pdf Celotno besedilo (225,92 KB)

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Schedule-dependency of doxorubicin and vinblastine in EAT tumours in mice
Marija Auersperg, Ana Pogačnik, Veronika Kloboves-Prevodnik, Gregor Serša, Maja Čemažar, 2006, izvirni znanstveni članek

Povzetek: Background. Antitumour schedule-dependency of the doxorubicin and vinblastine combination was explored. Materials and methods. Intraperitoneal Ehrlich ascites tumours (EAT) syngeneic to CBA mice were treated with vinblastine ar doxorubicin alone, or in combined treatment schedules. Results. Combinations of doxorubicin and vinblasfine administered at 48-h, but not at 24-h interval,regardless of the sequence of drugs, significantly reduced the numberof tumour cells in the ascites in corrtparison with all other treatments. In the combined treatment schedules, the predominant morphologicalchanges as well as DNA distribution pattern were dependent on thefirst drug applied. Regardless of the sequence of the drugs, median survival times of animals did not significantly differ between the treatment groups. Conclusions. The effect of combination of vinblastine and doxorubicin is schedule-dependent. The time interval, but not the sequence of drugs seems to be crucial for the observed effect. The data from preclinical studies are important for planning combined treatment schedules in clinical setting.
Objavljeno v DiRROS: 15.02.2024; Ogledov: 76; Prenosov: 13
.pdf Celotno besedilo (250,21 KB)

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Effect of electroporation on radiosensitization with cisplatin in two cell lines with different chemo- and radiosensitivity
Simona Kranjc Brezar, Maja Čemažar, Alenka Grošel, Živa Pipan Tkalec, Gregor Serša, 2003, izvirni znanstveni članek

Povzetek: Aim. Radiosensitization with cisplatin can be enhanced by electroporation of cells and tumours. The aim of this study was to extend our previous studies ontwo carcinoma tumour models with different chemo-and radiosensitivity in order to evaluate whether this treatment is effective also on less chemo-and radiosensitive tumour cells. Materials and methods. This in vitro study was performed on carcinoma SCK and EAT-E cells. The cytotoxicity of three-modalitytreatment consisting of cisplatin, electroporation and irradiation was determined by the clonogenic assay. Results. The radiosensitizing effect of cisplatin on the two cell lines was greatly enhanced by electroporation. By this combined treatment, less chemo and radiosensitive EAT-E cells were rendered as sensitive as more chemo and radiosensitive SCK cells. Conclusion. The enhancement of cisplatin-induced radiosensitization of cells by electroporation could be beneficially used in the treatment of intrinsically less chemo- and radiosensitive tumours.
Objavljeno v DiRROS: 06.02.2024; Ogledov: 104; Prenosov: 23
.pdf Celotno besedilo (144,48 KB)

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Tumor blood flow modifying effects of electrochemotherapy : a potential vascular targeted mechanism
Gregor Serša, Maja Čemažar, Damijan Miklavčič, 2003, izvirni znanstveni članek

Povzetek: 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.
Objavljeno v DiRROS: 06.02.2024; Ogledov: 102; Prenosov: 21
.pdf Celotno besedilo (205,34 KB)

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Klinično raziskovanje v onkologiji : učbenik za študente medicine in specializante onkologije
Maja Čemažar, 2024, ni določena

Ključne besede: onkologija
Objavljeno v DiRROS: 29.01.2024; Ogledov: 147; Prenosov: 33
.pdf Celotno besedilo (1,39 MB)

10.
MRI macromolecular contrast agents as indicators of changed tumor blood flow
Teodora Ivanuša, Katarina Beravs, Maja Čemažar, Vladimir Jevtič, Franci Demšar, Gregor Serša, 2001, izvirni znanstveni članek

Povzetek: Background. A rapid mapping technique derived from dynamic contrast enhanced MRI data was used to identify and characterize reduction of blood flow in fibrosarcoma SA-1 tumors treated either by application of electric pulses or vinblastine. Materials and methods. Tissue permeability surface area product (PS) and fractional blood volume (BV) were calculated on a pixel-by-pixel basis using dynamic MRI intensity data after administration of gadomer - 17 orpolylysine-Gd-DTPA; prototypic macromolecular contrast agents designed for blood pool enhancement. PS and BV values of untreated tumors were compared to those of tumors treated by local application of 8 electric pulses (amplitude/distance ratio, 1300 V/cm; duration, 100 us, frequency, 1 Hz) percutaneously to the tumor or by systemic administration of vinblastine (2.5 mg/kg). Results. Both treatments transiently, but significantly reduced tumor blood flow, application of electric pulses to the tumors being by 40% more effective in reducing tumor blood flow than systemic administration of vinblastine. PS and BV values derived with polylysine-Gd-DTPA-enhanced MRI were lower compared to those with gadomer-17, due to larger molecular size. Interestingly, Gd-DTPA-enhanced MRI did not show any significant changes of PSand BV between untreated and treated tumors. Conclusion. This study demonstrates that dynamic contrast enhanced MRI can be effectively used to qualitatively monitor tumor blood flow, and quantitatively by means of BV and PS.
Objavljeno v DiRROS: 25.01.2024; Ogledov: 130; Prenosov: 31
.pdf Celotno besedilo (234,93 KB)

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