1191. Molecular alterations induced in drug-resistant cellsMaja Osmak, 1998, izvirni znanstveni članek Povzetek: The major obstacle to the ultimate success in cancer therapy is the ability oftumor cells to develop resistance to anticancer drugs. Several molecular mechanisms have been suggested to be involved in drugresistance: a) decrease in the intracellular drug accumulation (increased activity of membrane transporters such as P-glycoprotein or multidrug-resistance-associated protein), b) changes in intracellular detoxification system (increased concentrations of glutathione or metallothioneins, or increased activity of related enzymed), c) alteration in nuclear enzymes (enhanced DNA repair and/orbetter tolerance of DNA damage, decreased acitivty of topoisomerases), d) altered expression of oncogenes (inducing increased level of protective molecules in cells or the inhibition of apoptosis). Drug resistance is a multifactorial phenomenon. The complexity of molecular alterations in drug-resistant cells is and will stay the main problem for the successful treatment of cancer.
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1192. Influence of UV-B radiation on Norway spruce seedlings (Picea abies (L.) Karst.)Jože Bavcon, Nada Gogala, Alenka Gaberščik, 1998, izvirni znanstveni članek Povzetek: On the basis of the hypothesis that the ultraviolet radiation is one of the main causes for damage at higher altitudes, we have monitored the effect of UVradiation on Norway spruce for two and a half years. The influence of UV-B radiation on Picea abies (L). Karst.seedlings cultured in pots in open greenhouses was examined by measuring photochemical efficiency of photosystem II, changes in chlorophyll a, b, and changes in anthocyanins. The seedlings were grown in a mixture of peat and vermiculite (4:1). We used Osram ultravitaluks bulbs as a source of UV-B radiation. In the experiment plants were treated with 21.24+-3.5 kJ/m2 and 31.9+-2.5 KJ/m2. The control plants were grown under ambient conditions in the greenhouse without artificial source of UV-B radiation. The mean yearly values were as high as 11.5+-5.2 kJ/m2. The photochemical efficiency of photosystem II (PS II) in experimental plants did not vary during the experiment. It showed obvious decrease in the winter period, due to low temperatures and physical draught. The decrease in chlorophyll a and b, was already detected after one year of treatment with simultaneous changes in a/b ration. An increase of anthocyanins amount was detected as well.
Objavljeno v DiRROS: 19.01.2024; Ogledov: 253; Prenosov: 72
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1193. Apparatus for positron emission tomographyMarko Starič, Samo Korpar, Erik Margan, Marko Šifrar, Aleš Stanovnik, Nataša Budihna, Metka Milčinski, Boris Šket, 1998, izvirni znanstveni članek Objavljeno v DiRROS: 19.01.2024; Ogledov: 220; Prenosov: 52
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1194. Bone marrow toxicity and antitumor action of adriamycin in relation to the antioxidant effects of melatoninValentina Rapozzi, Laura Perissin, Sonja Zorzet, Marina Comelli, Irene Mavelli, Marjeta Šentjurc, Alja Pregelj, Milan Valter Schara, Tullio Giraldi, 1998, izvirni znanstveni članek Objavljeno v DiRROS: 19.01.2024; Ogledov: 233; Prenosov: 54
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1195. Phase II study of fluorouracil, leucovorin and interferon alpha-2a in patients with advanced colon cancerBorut Štabuc, Aleksandra Markovič, Erik Brecelj, Samir Bešlija, Tomaž-Edvard Cizej, 1998, izvirni znanstveni članek Povzetek: Based on in viro studies that have demonstrated synergy between fluorouracil (5-FU) and leucovorin (LV) as well as between 5-FU and recombinant alpha-2a interferon (IFN) against colon cancer cell lines a phase II study was carried out to evaluate the toxicity and clinical activity of 5-FU modulated with LV and IFN in patients with metastatic colon cancer. Twenty-two chemotherapy naive patients with measurable metastases of colon cancer have been treated with daily doses of 5-FU 600 mg/m2 in 6-hr intravenous infusion, and of LV 20 mg/m2 intravenously and IFN 6 MU subcutaneously, for 5 days every 4 weeks. Median age was 60 years, median PS (ECOG) was 1 (range 0-2). Liver, soft tissue and lung metastases were found in 12, 5 and 8 patients, respectively. Nineteen patients had a single metastatic site, two double, whereas one had more than two metastatic sites. Patients had 2-9 (mean 5) cycles of treatment.Objective response was observed in 7 patients (32%), and stable disease in 7 patients (32%). Overall median survival was 12.5 months, and for responders 14.4 months. Responses were generally short and median time for progression was 5.5 months. The most frequent adverse reactions were flu-like syndrome (50%), nausea/vomiting (36%), diarhoea (13Č), stomatitis (27%) and leucopenia (13%). This regimen of 5-FU with LV and IFN administration does notappear to be superior to previously published shedules of 5-FU with IFN or 5-FU with LV.
Objavljeno v DiRROS: 19.01.2024; Ogledov: 243; Prenosov: 68
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1196. Experimental and numerical investigation of restrained shrinkage of concreteLucija Hanžič, Jurij Karlovšek, Tomaž Hozjan, Sabina Huč, Zhongyu Xu, Igor Planinc, Johnny Ching Ming Ho, 2020, objavljeni znanstveni prispevek na konferenci Povzetek: To promote the understanding of shrinkage related behaviour of concrete used for tunnel linings the experimental and theoretical investigation including numerical and analytical approach was performed on ring-shaped specimens. Overall one analytical (an.) and two numerical models, namely (i) and (ii) were also developed. Models (an.) and (i) considered the restraining steel ring to be rigid, thus not exhibiting any deformation. Numerical model (ii) considered the steel ring to be deformable. The experimental set-up consisted of a large concrete ring with an inner diameter of 120 cm, an outer diameter of 160cm and 20 cm in height. The restraining steel ring was 5.5 cm thick. Two concrete rings were made, namely R1 with a low compressive strength of ~26MPa and the other, R2, with medium compressive strength of ~40 MPa. The strain was measured in the hoop direction on the inner circumference of the steel ring and on the outer circumference of the concrete ring. Concrete rings were subjected to circumferential drying. Numerical model (ii) predicted critical time to the formation of the first crack to be between 13 and 14 days. The experimentally determined critical time is found to be 11 to 13 days with cracks gradually opening over several days. This was indicated by changes in measured concrete and steel strain. Modelled concrete strain just before cracking was between -20 and -30 % 10-6 m m-1 however, measured concrete strain was ~150 % 10-6 m m-1. Modelled steel strain was between -30 and -40 % 10-6 m m-1 while measured steel strain was between -10 and 20 % 10-6 m m-1. These discrepancies, in particular the positive steel strain obtained in experiments, require further investigation and improvements of the experimental set-up.
Ključne besede: concrete, tunnel lining, restrained shrinkage, Reissner beam theory, modelling
Objavljeno v DiRROS: 19.01.2024; Ogledov: 305; Prenosov: 115
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1197. The role of thyroid radiation carcinogenesis in ratsKatarina Koritnik, Andrej Cör, 1998, izvirni znanstveni članek Povzetek: The aimof this study was to test the hypothesis on the protective role of thyroxin administration before and during irradiation on the occurrence of thyroid carcinoma in rats. Application of thyroxin before and during irradiation was expected to decrease production of thyrotropin by the hypophyseal feedback mechanism, caused by radiation damage of thyroid tissue. Stabilizing the thyroid cells in this way during irradiation would thus make them less radiosensitive. In the experiment, we first divided 81 three to fourweek old Wistar strain rats of both sexes into two groups, i.e. thyroxin (T4) and water (H2O). The T4 rats were injected 1% thyroxin solution (0.01 mg/100 g body weight) twice a day for 15 days, while the H2O rats received saline in the same way. After ten days, the two main groups were divided each into two subgroups. The rats from both irradiated subgroups (T4/X and (H2O/X) recieved 10 Gy to the neck area. They were iradiated with a telecobalt machinefor five consecutive days with one direct field. During a two years follow - up, all moribund animals were sacrificed and their thyroid glands taken. The rest of the thyroid glands were taken at the end of the experiment.All glands were pathohistologically analysed. Besides, all suspicious and enlarged extrathyroid organs and tissues were examined and the occurrence of tumors was noted. Pathohistological examination revealed the occurrence of 8 thyroid carcinomas and 7 adenomas in the H2O/X group, and 3 adenomas in the T4/X group. In the iradiated group of rats without thyroxin, significantly (P = 0.01) more thyroid carcinomas occurred than in the irradiated group without thyroxin.
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1198. Micronuclei in cytokinesis-blocked lymphocytes as an index of occupational exposure to antineoplastic drugsVera Garaj-Vrhovec, Nevenka Kopjar, 1998, izvirni znanstveni članek Povzetek: In order to investigate possible DNA damiging effects of antineoplastic drugs,the micronucleus assay combined with Giemsa, DAPI and silver staining was performed. Blood samples were taken from nurses working without adequate protection in oncological department on preparing and administration of different antineoplastic drugs. Lymphocytes were cultivated in vitro at 37 degrees C. To prevent cytokinesis, at 44th cytochalasine-B at a final concentration of 3 micro g/ml was added. The results obtained indicate statistically significant increases in the total number of micronuclei in the exposed subjects compontrols. DAPI staining has revealed signal-positive and signal-negative miuclei while silver staiing has revealed Ag-NOR+ and Ag-NOR- micronuclei. Compred to controls, the number of signal-positive exposed subjects were increased, indicating a greater susceptibility of particular chromosomes to damage caused by antineopalstic agents.
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1199. p53 - the paradigm of tumor-suppresor genes?Barbara Jezeršek Novaković, Srdjan Novaković, 1998, pregledni znanstveni članek Povzetek: p53 is a tumor-suppressor gene the alterations of which are among the most frequent genetic changes detected in human neoplasms. Its product - p53 protein is a component of several biochemical pathways that are central to carcinogenesis: DNA transcription, genomic stability, DNA repair, cell cycle control, and apoptosis. The analysis of the spectrum of p53 mutations and insight into the p53 mediated biochemical pathways of programmed cell death and cell cycle arrest, provide clues to understanding of molecular pathogenesis of cancer of mechanisms related to p53 mediated tumor suppression. The purpose of the resent article is to summarise the most important facts concerning p53 since understanding of the above listed processes might provide the potential molecular targets for the development ofa rational cancer treatment.
Objavljeno v DiRROS: 19.01.2024; Ogledov: 216; Prenosov: 59
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