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Iskalni niz: "avtor" (K��hdorf Katja) .

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1.
Genetic polymorphisms in homologous recombination repair genes in healthy Slovenian population and their influence on DNA damage
Katja Goričar, Nina Erčulj, Maja Zadel, Vita Dolžan, 2012, izvirni znanstveni članek

Povzetek: Background. Homologous recombination (HR) repair is an important mechanism involved in repairing double-strand breaks in DNA and for maintaining genomic stability. Polymorphisms in genes coding for enzymes involved in this pathway may influence the ca pa city for DNA repair. The aim of this study was to select tag single nucleotide polymorphisms (SNPs) in specific genes involved in HR repair, to determine their allele frequencies in a healthy Slovenian population and their influence on DNA damage detected with comet assay. Materials and methods. In total 373 individuals were genotyped for nine tag SNPs in three genes: XRCC3 722C>T, XRCC3 -316A>G, RAD51 -98G>C, RAD51 -61G>T, RAD51 1 522T>G, NBS1 553G>C, NBS1 1197A>G, NBS1 37117C>T and NBS1 3474A>C using competitive allele-specific amplification (KASPar assay). Comet assay was performed in a subgroup of 26 individuals to determine the influence of selected SNPs on DNA damage. Results. We observed that age significantly affected genotype frequencies distribution of XRCC3 -316A>G (P = 0.039) in healthy male blood donors. XRCC3 722C>T (P = 0.005), RAD51 -61G>T IP = 0.023) and NBS1 553G>C (P = 0.008) had a statistically significant influence on DNA damage. Conclusions. XRCC3 722C> T, RAD51 -61 G> T and NBS 1 553G>C polymorphisms significantly affect the repa ir of damaged DNA and may be of clinical importance as they are common in Slovenian population.
Objavljeno v DiRROS: 22.03.2024; Ogledov: 35; Prenosov: 16
.pdf Celotno besedilo (532,36 KB)

2.
Effects of electrochemotherapy on immunologically important modifications in tumor cells
Urša Kešar, Boštjan Markelc, Tanja Jesenko, Katja Uršič Valentinuzzi, Maja Čemažar, Primož Strojan, Gregor Serša, 2023, izvirni znanstveni članek

Povzetek: Electrochemotherapy (ECT) is a clinically acknowledged method that combines the use of anticancer drugs and electrical pulses. Electrochemotherapy with bleomycin (BLM) can induce immunogenic cell death (ICD) in certain settings. However, whether this is ubiquitous over different cancer types and for other clinically relevant chemotherapeutics used with electrochemotherapy is unknown. Here, we evaluated in vitro in the B16-F10, 4T1 and CT26 murine tumor cell lines, the electrochemotherapy triggered changes in the ICD-associated damage-associated molecular patterns (DAMPs): Calreticulin (CRT), ATP, High Mobility Group Box 1 (HMGB1), and four immunologically important cellular markers: MHCI, MHC II, PD-L1 and CD40. The changes in these markers were investigated in time up to 48 h after ECT. We showed that electrochemotherapy with all three tested chemotherapeutics induced ICD-associated DAMPs, but the induced DAMP signature was cell line and chemotherapeutic concentration specific. Similarly, electrochemotherapy with CDDP, OXA or BLM modified the expression of MHC I, MHC II, PD-L1 and CD40. The potential of electrochemotherapy to change their expression was also cell line and chemotherapeutic concentration specific. Our results thus put the electrochemotherapy with clinically relevant chemotherapeutics CDDP, OXA and BLM on the map of ICD inducing therapies.
Ključne besede: electrochemotherapy, cisplatin, immune response
Objavljeno v DiRROS: 21.03.2024; Ogledov: 50; Prenosov: 27
.pdf Celotno besedilo (7,17 MB)
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3.
The prognostic and predictive value of human gastrointestinal microbiome and exosomal mRNA expression of PD-L1 and IFNγ for immune checkpoint inhibitors response in metastatic melanoma patients : protocol trial
Ana Erman, Marija Ignjatović, Katja Leskovšek, Simona Miceska, Urša Lampreht Tratar, Maša Omerzel, Veronika Kloboves-Prevodnik, Maja Čemažar, Lidija Kandolf Sekulović, Gorazd Avguštin, Janja Ocvirk, Tanja Mesti, 2023, izvirni znanstveni članek

Povzetek: Background: Immunotherapy has been successful in treating advanced melanoma, but a large proportion of patients do not respond to the treatment with immune checkpoint inhibitors (ICIs). Preclinical and small cohort studies suggest gastrointestinal microbiome composition and exosomal mRNA expression of PD-L1 and IFNγ from the primary tumor, stool and body fluids as potential biomarkers for response. Methods: Patients treated with immune checkpoint inhibitors as a first line treatment for metastatic melanoma are recruted to this prospective study. Stool samples are submitted before the start of treatment, at the 12th (+/−2) week and 28th (+/−2) week, and at the occurrence of event (suspected disease progression/hyperprogression, immune-related adverse event (irAE), deterioration). Peripheral venous blood samples are taken additionally at the same time points for cytologic and molecular tests. Histological material from the tumor tissue is obtained before the start of immunotherapy treatment. Primary objectives are to determine whether the human gastrointestinal microbiome (bacterial and viral) and the exosomal mRNA expression of PD-L1 and IFNγ and its dynamics predicts the response to treatment with PD-1 and CTLA-4 inhibitors and its association with the occurrence of irAE. The response is evaluated radiologically with imaging methods in accordance with the irRECIST criteria. Conclusions: This is the first study to combine and investigate multiple potential predictive and prognostic biomarkers and their dynamics in first line ICI in metastatic melanoma patients.
Ključne besede: gastrointestinal microbiome, mRNA expression of PD-L1 and IFNγ, immune checkpoint inhibitors, metastatic melanoma
Objavljeno v DiRROS: 21.03.2024; Ogledov: 56; Prenosov: 26
.pdf Celotno besedilo (642,09 KB)
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4.
Cell size dynamics and viability of cells exposed to hypotonic treatment and electroporation for electrofusion optimization
Marko Ušaj, Katja Trontelj, Rosana Hudej, Maša Kandušer, Damijan Miklavčič, 2009, izvirni znanstveni članek

Povzetek: Background. Various electrofusion parameters have to be adjusted to obtain theoptimal electrofusion efficiency. Based on published data, good electrofusion conditions can be achieved with the hypotonic treatment. However, the duration of the hypotonic treatment before electroporation and buffer hypoosmolarity have to be adjusted in order to cause cell swelling, to avoid regulatory volume decrease and to preserve cell viability. The aims of our study were to determine cell size dynamics and viability of four different cell lines in hypotonic buffer and to study the influence of the electroporation on the selected cell line in hypotonic buffer. Materials and methods. Cell size dynamics of different cell lines exposed to hypotonic buffer and electroporation were analyzed by time-resolvedcell size measurements. The viability of hypotonically treated oržand electroporated cells was determined 24 h after the experiment by a modified crystal violet (CV) viability assay. Results. In our experimental conditions the hypotonic treatment at 100 mOsm was efficient for CHO, V79 and B16-F1 cell lines. The optimal duration of the treatment was between two and five minutes. On the other hand the same hypotonic treatment did not cause cell swelling of NS1 cells. Cell swelling was also observed after electroporation of B16-F1 in isotonic buffer and it was amplified when hypotonic buffer was used. In addition, the regulatory volume decrease was successfully inhibited with electroporation. Conclusions. Cell size dynamicsin hypotonic conditions should be studied for each cell line since they differ in their sensitivity to the hypotonic treatment. The inhibition of cell regulatory volume decrease by electroporation may be beneficial in achieving higher electrofusion efficiency. (Abstract truncated at 2000 characters)
Ključne besede: hypotonic treatment, cell swelling, regulatory volume decrease, cell size measurements, viability, electrofusion, electroporation
Objavljeno v DiRROS: 08.03.2024; Ogledov: 79; Prenosov: 28
.pdf Celotno besedilo (263,01 KB)

5.
Evaluation of fly ash-based alkali activated foams at room and elevated temperatures
Katja Traven, Mark Češnovar, Srečo D. Škapin, Vilma Ducman, 2020, objavljeni znanstveni prispevek na konferenci

Povzetek: Alkali activated materials (AAM) are, in their broadest classification, any binder systems derived by the reaction of an alkali metal source (silicates, alkali hydroxides, carbonates , sulphates) with a solid, amorphous alumosilicate powder (found in precursors such as slag, fly ash and bottom ash). A wide variety of products can be obtained by the alkali activation process and could replace traditional construction products. Among the se, alkali activated foams (AAF) represent one of the most promising materials, owing to their economically accessible alumosilicate rich source materials, including industrial waste materials, clean processing, higher added value and most importantly, pro ducts with competitive properties. In the present study, the properties of alkali activated fly ash - based foam materials were studied at room temperature as well as at elevated temperatures (up to 1200 °C ) in order to develop a durable material in terms o f mechanical properties and suitability for high temperature applications.
Ključne besede: lightweight porous insulating material, alkali activated materials, microstructural analysis
Objavljeno v DiRROS: 05.03.2024; Ogledov: 80; Prenosov: 36
.pdf Celotno besedilo (970,74 KB)
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6.
The deformation of alkali-activated materials at different curing temperatures
Mark Češnovar, Katja Traven, Vilma Ducman, 2020, objavljeni znanstveni prispevek na konferenci

Povzetek: Alkali activation is a chemical process whereby materials rich in aluminosilicate, which dissolves in basic media at room temperature, form binding phases by polycondensation. The alkali- activated materials (AAM) are a promising alternative to binding materials such as cement or other products in civil engineering (van Deventer et al., 2012). This study investigates the early age shrinkage behavior of Slovenian ladle and electric arc furnace slag - based alkali activated materials at different curing temperatures. The dimensions of specimens cured at room temperature and elevated temperatures up to 90 °C were measured over the first 7 hours (every 10 min). The results show that the most shrinkage occurred at the highest temperature, owing to the highest rate of evaporation of liquid content. Loss of mass follows from the drying shrinkage.
Ključne besede: alkali activated materials, shrinkage, compressive strength
Objavljeno v DiRROS: 01.03.2024; Ogledov: 88; Prenosov: 56
.pdf Celotno besedilo (670,52 KB)
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7.
Quantifying the environmental implication of cotton-fiber-based nanocrystalline cellulose : a life-cycle assessment
Katja Malovrh Rebec, Janez Turk, Matjaž Kunaver, 2024, izvirni znanstveni članek

Povzetek: Considering the increasing demand for nanocrystalline-cellulose in the industry, due to its exceptional physical and biological properties, cheaper and more efficient production processes are sought. Addressing environmental concerns, especially within the framework of EU policies, this study employs Life Cycle Assessment (LCA) to evaluate the environmental performance of a novel nanocrystalline-cellulose production procedure, encompassing biomass depolymerization, rinsing, and bleaching. The LCA aims to identify environmental hotspots, explore mitigation measures, and enables comparisons with other LCA studies on nanocrystalline-cellulose. The results are calculated and reported for 19 environmental impact categories, using the ReCiPe 2016 impact assessment method. The production of 1 kg of dry nanocrystalline-cellulose using the novel process emits 63.7 kg CO2 equivalent, which is lower than the literature average (68 kg CO2 equivalent). The solvent (e.g. diethylene glycol) is the major contributor to the global warming potential and fossil-fuel depletion potential in the product stage of the nanocellulose, while the electricity requirements and glycerin represent environmental hotspots regarding 15 of the 19 impact categories assessed. In terms of the water-consumption potential, the environmental hotspot is production of raw materials (e.g. cotton fibers). Electricity contributes more than 50 % of the burden to the impact categories associated with ionizing radiation, the pollution of aquatic ecosystems and human toxicity related to cancer. It also holds a significant share of the burdens for terrestrial acidification (48 % of the impact), the formation of fine particulate matter (46 % of the impact), and human toxicity related to non-cancer diseases (37 % of the impact). This underscores the importance of optimizing the production process, possibly through upscaling. Additionally, incorporating on-site renewable energy sources and utilizing biomass-derived diethylene glycol can enhance the environmental performance of nanocrystalline-cellulose.
Ključne besede: LCA, cascade use, cellulose nanocrystals, pilot production, environmental performance
Objavljeno v DiRROS: 06.02.2024; Ogledov: 104; Prenosov: 59
.pdf Celotno besedilo (5,07 MB)
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9.
The influence of different fibres quantity on mechanical and microstructural properties of alkali-activated foams
Katja Traven, Mark Češnovar, Barbara Horvat, Vilma Ducman, 2022, objavljeni znanstveni prispevek na konferenci

Povzetek: Alkali activated foams (AAFs) were produced using electric arc furnace steel slag (EAF) and ladle furnace basic slag (LS), obtained from two metallurgical companies in Slovenia. They were activated with a mixture of sodium water glass (Na2SiO3) and solid NaOH and foamed with hydrogen peroxide (H2O2). Pores were stabilized with the addition of Triton as a surfactant. Four types of fibres were added to the studied mixture (polypropylene (PP), polyvinyl-alcohol (PVA), basalt (B), and glass wool (GW)) in five different quantities: 0.5, 1.0, 1.25, 1.5 and 2.0 vol % in order to additionally stabilize the structure and thus improve its mechanical properties. The results of mechanical properties showed, that compressive strength was increased in all 20 specimens, partially due to the increased density as well as to the fibre addition. Flexural strength on the other hand was the most improved in the samples where PP and PVA fibres were added. The samples with the addition of B and GW fibres on the other hand showed only small or no improvement in flexural strength in comparison to the referenced sample. Additionally, the microstructure of used fibres and selected foams was also investigated by the means of SEM analysis.
Ključne besede: fibers, alkali activated foams, properties
Objavljeno v DiRROS: 31.01.2024; Ogledov: 117; Prenosov: 48
.pdf Celotno besedilo (4,05 MB)
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10.
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