501. Tertiary collimator system for stereotactic radiosurgery with linear acceleratorBožidar Casar, 1998, original scientific article Abstract: In the last decade, stereotactic radiosurgery (SRS) with linear accelerator (linac) has become an important irradiation technique for a variety of malignant and benign intracranial lesions. Although there exist some other radiosurgery techniques, linac based SRS meets the requirements needed for SRSwith low cost modifications. On of the most important additional parts of the equipment is tertiary collimator system which can be attached onto the linac head. We designed and built such system that can be easily fixed onto linac PHILIPS SL - 75/5 with 5 MV photon energy. In our department, we alreadyuse this linac for conventional radiation therapy. Our tertiary collimator system meets all the requirements important for this special modality of radiation therapy. It allows fine centering of the system and has ten various collimators with divergent circular openings having a nominal field diameter ranging from 1.0 cm to 4.0 cm at the isocenter. The accuracy ofthe system was checked by exposing x - ray films at various gantry positions, and recording misalignment of the beams. The width of penumbra was determined using two different dosimetry techniques (film dosimetry and diode measurements).
Published in DiRROS: 19.01.2024; Views: 183; Downloads: 42
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503. Flow cytometric pitfalls in immunophenotyping of lymphomasAlojz Ihan, 1998, review article Abstract: Flow cytometry has been introduced as the most reliable method for the analysis of lymphocyte subsets. The advantage of flow cytometry is that it enables application of virtually all monoclonal antibodies (native cells), a quantitative estimation of different lymphoid cells, and that cell can be simultaneously analysed for multiple marker expression. The usage of flow cytometers requiers considerable knowledge of physics and its technical application. Moreover, several problems arise from the complexity of the biolocal systems investigated.
Published in DiRROS: 19.01.2024; Views: 167; Downloads: 41
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505. Genetic polymorphisms of xenobiotic metabolizing enzymes in human colorectal cancerVita Dolžan, Metka Ravnik-Glavač, Katja Breskvar, 1998, published scientific conference contribution Abstract: It was proposed that both hereaditary and environmental factors contribute to the development of colorectal cancer (CRC). Carcinogenic polycyclic aromatic hydrocarbons (PAHs) from food or tobacco smoke can form DNA adducts and thus initiate carcinogenesis after metabolic activation via cytochrome P4501A1 (CYP1A1). Intermediate metabolites are detoxified by conjugation with glutathione S-transferases. Our aim was to look for inherited metabolic suceptibility to CRC. We used PCR-based genotyping approach to determine the frequencies of polymorphic alleles of two cytochromes P450 (CYP2D6 and CYP1A1)and two glutathione S-transferases (GSTM1 and GSTT1) in DNA samples from 31 sporadic, 25 familial CRC cases and 73 healthy controls. The difference in frequencies of poor metabolisers due to CYP2D6 gene polymorphismwas close to the limit of statistical significance between sporadiCRC and healthy control group (lambda 2=5.52, m=2, p=0.06) despite the small sample size. The frequencies of either CYP1A1 MspI, GST M1 or GST T1 genotypes were not significantly different in both CRC cases and in controls. Although our study suggests some difference in metabolic susceptibility between sporadic and familial CRC, further studies are needed to investigate the combined effect of polymorphic genes involved in carcinogen metabolism in a larger group of patients with defined exposure to dietary carcinogens and smoking.
Published in DiRROS: 19.01.2024; Views: 224; Downloads: 49
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508. On mechanisms of cell plasma membrane vesiculationVeronika Kralj-Iglič, Urška Batista, Henry Hägerstrand, Aleš Iglič, Janja Majhenc, Mihael Sok, 1998, original scientific article Keywords: budding, membrane bilayer, vesiculation
Published in DiRROS: 19.01.2024; Views: 175; Downloads: 49
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510. Vinblastine increases antitumor effectiveness of bleomycinMaja Čemažar, Marija Auersperg, Gregor Serša, 1997, original scientific article Abstract: In our previous vinblastine (VELBE) was shown to increase the plasma membrane fluidity. This effect of VELBE might be expolited for better transport of drugs through the plasma membrane. Bleomycin (BLM) is a highly cytotoxic drug when present inside the cells but has a hampered transport through the plasma membrane. The aim of the present study was to determine whether pretreatment with VELBE can increase the effect of BLM on intraperitoneal SA-1 tumors in mice. BLM and VELBE were used as single agents or in various combinations, i.e. VELBE and BLM injected simultanously, BLM injected 24 h before VELBE or VELBE injected 24 h before BLM. Mice survival was the end-point used for determining the effect of this combined treatments. VELBE and BLM as a single treatment significantly prolonged median survival time of study animals compared to controls. Furthermore, when VELBE and BLM were combined, all threetested combinations were more effective than VELBE or BLM as single treatments. The effect on animal survival was equal when VELBE was given 24 h after or simultanously with BLM. The longest survival, however was obtained when VELBE was injected 24 h before BLM. From these results we can conclude that the underlying mechanisms for more than additive effect of VELBE and BLM when VELBE was given 24 h before BLM could be attributed to an increased membrane fluidity, possibly in combination with a cell kinetic effect.
Published in DiRROS: 18.01.2024; Views: 165; Downloads: 38
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