Digital repository of Slovenian research organisations

Search the repository
A+ | A- | Help | SLO | ENG

Query: search in
search in
search in
search in

Options:
  Reset


Query: "author" (Maja Čemažar) .

11 - 20 / 94
First pagePrevious page12345678910Next pageLast page
11.
Evaluation of shRNA-mediated gene silencing by electroporation in LPB fibrosarcoma cells
Suzana Vidic, Urška Kamenšek, Maja Čemažar, 2008, original scientific article

Abstract: 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.
Published in DiRROS: 08.03.2024; Views: 58; Downloads: 20
.pdf Full text (391,23 KB)

12.
Electrochemotherapy of tumours
Gregor Serša, Maja Čemažar, Damijan Miklavčič, Zvonimir Rudolf, 2006, review article

Abstract: 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.
Published in DiRROS: 15.02.2024; Views: 118; Downloads: 32
.pdf Full text (225,92 KB)

13.
Schedule-dependency of doxorubicin and vinblastine in EAT tumours in mice
Marija Auersperg, Ana Pogačnik, Veronika Kloboves-Prevodnik, Gregor Serša, Maja Čemažar, 2006, original scientific article

Abstract: 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.
Published in DiRROS: 15.02.2024; Views: 78; Downloads: 15
.pdf Full text (250,21 KB)

14.
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, original scientific article

Abstract: 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.
Published in DiRROS: 06.02.2024; Views: 107; Downloads: 23
.pdf Full text (144,48 KB)

15.
Tumor blood flow modifying effects of electrochemotherapy : a potential vascular targeted mechanism
Gregor 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: 107; Downloads: 22
.pdf Full text (205,34 KB)

16.
Klinično raziskovanje v onkologiji : učbenik za študente medicine in specializante onkologije
Maja Čemažar, 2024, not set

Keywords: onkologija
Published in DiRROS: 29.01.2024; Views: 166; Downloads: 35
.pdf Full text (1,39 MB)

17.
MRI macromolecular contrast agents as indicators of changed tumor blood flow
Teodora Ivanuša, Katarina Beravs, Maja Čemažar, Vladimir Jevtič, Franci Demšar, Gregor Serša, 2001, original scientific article

Abstract: 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.
Published in DiRROS: 25.01.2024; Views: 149; Downloads: 33
.pdf Full text (234,93 KB)

18.
Antitumor effectiveness of bleomycin on SA-1 tumor after pretreatment with vinblastine
Maja Čemažar, Marija Auersperg, Gregor Serša, 2000, original scientific article

Abstract: In our previous study, vinblastine (VLB) was shown to increase the plasma membrane fluidity. This effect of VLB might be exploited for better transport of drugs through the plasma membrane. The aim of the present study was to determine whether pretreatment with VLB can increase the cytotoxic effect of BLM on intraperitoneal SA-1 tumors in mice. Materials and methods. BLM and VLBwere used as single agents or in various combinations, i.e. BLM injected 24h before VLB or vice-versa, VLB injected 24 h before BLM. Cell and animal survival together with DNA histograms were the end-points used to determine the effect of these combined treatments. Results. Both drugs, either as singletreatment or in different combined therapy schedules reduced significantly the number of cells in peritoneal lavage, compared to control, saline treated animals. The combination of VLB, followed by BLM after 24 h reduced significantly the number of cells in peritoneal lavage, compared to the treatment in which BLM was followed by VLB or to the treatment with singledrugs alone. Median survival time of mice treated with VLB alone, BLM alone and combination of both drugs was significantly prolonged compared to the control untreated mice. When VLB and BLM were combined, both treatment combinations were more effective than monochemotherapies with VLB or BLM. The best results were obtained when VLB was followed by BLM after 24 h. The DNA histogram of cells treated with VLB showed a decreased number of cells in S phase and an increased number of cells with DNA values greater than in G2M compartment compared to the control untreated cells. BLM in the dosage used inthese experiments did not affect the progression of cells through cell cycle. Both combinations of VLB and BLM produced similar cell kinetic effect as VLB alone. Conclusion. (Abstract truncated at 2000 characters.)
Published in DiRROS: 23.01.2024; Views: 121; Downloads: 27
.pdf Full text (499,47 KB)

19.
Comparison of colorimetric MTT and clonogenic assays for irradiation and cisplatin treatment on murine fibrosarcoma SA-1 cells
Maja Čemažar, Darja Marolt, Mira Lavrič, Gregor Serša, 1999, original scientific article

Abstract: Background. The aim of our study was to determine the relationship between cell survival of SA-1 tumor cells measured by clonogenic assay and MTT assay after irradiation and cisplatin treatment. Materials and methods. Survival of SA-1 cells was measured after irradiation (2-8 Gy) and cisplatin treatment (0.05-0.5 u g/ml) by clonogenic assay performed 7 days after treatment, and byMTT assay performed on day 3, 4, 5, and 7 after the treatment. Results. The results showed good correlation between MTT assay and clonogenic assay for irradiation doses below 4 Gy. For higher doses good correlation between MTT and clonogenic assay was determined only when MTT assay was performed on day 5and 7 after the treatment. In the case of cisplatin treatment, similar pattern was observed, good correlation between IC50 values for MTT and clonogenic assay was found when MTT assay was performed on day 5 and 7 after the treatment. Conclusion. Results of our study confirmed the results of previous studies addressing this topic and further support the use of MTT testas an alternative test for clonogenic test as a predictive assay of tumourresponse to the radio or chemotherapy.
Published in DiRROS: 22.01.2024; Views: 151; Downloads: 33
.pdf Full text (419,17 KB)

20.
Adenocarcinoma skin metastases treated by electrochemotherapy with cisplatin combined with radiation
Gregor Serša, Maja Čemažar, Zvonimir Rudolf, Albert-Peter Fras, 1999, original scientific article

Abstract: Background. The aim of this study was to determine the interaction between electrochemotherapy as a means of facilitated cisplatin delivery into the cells and irradiation of adenocarcinoma skin metastases. Case report. A patient with progressive disease presenting skin metastases of tubal dedifferentiated pappilary adenocarcinoma was enrolled in the study. Skin metastases were treated by electrochemotherapy with intratumoral injection of cisplatin. Its antitumor effectiveness was compared to that of combined treatment of irradiation with electrochemotherapy. After a two week observation time, the response to treatment was comparable between the electrochemotherapy and electrochemotherapy combined with irradiation. Both ofthese treatments were more effective than irradiation alone. Furthermore, antitumor effectiveness of the combined electrochemo- and radiotherapy was found to be quicker than that of electrochemotherapy alone. Comment. This study shows that electrochemotherapy with cisplatin is also effective in the treatment of adenocarcinoma skin metastases. Inspite of the short observation time, positive interaction between radiotherapy and electrochemotherapy with cisplatin was found.
Published in DiRROS: 22.01.2024; Views: 132; Downloads: 33
.pdf Full text (410,27 KB)

Search done in 0.29 sec.
Back to top