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1303. Mesenchymal stem cells differentially affect the invasion of distinct glioblastoma cell linesBarbara Breznik, Helena Motaln, Miloš Vittori, Ana Rotter, Tamara Lah Turnšek, 2017, original scientific article Abstract: Glioblastoma multiforme are an aggressive form of brain tumors that are characterized by distinct invasion of single glioblastoma cells, which infiltrate the brain parenchyma. This appears to be stimulated by the communication between cancer and stromal cells. Mesenchymal stem cells (MSCs) are part of the glioblastoma microenvironment, and their ‘cross-talk’ with glioblastoma cells is still poorly understood. Here, we examined the effects of bone marrow-derived MSCs on two different established glioblastoma cell lines U87 and U373. We focused on mutual effects of direct MSC/glioblastoma contact on cellular invasion in three-dimensional invasion assays in vitro and in a zebrafish embryo model in vivo. This is the first demonstration of glioblastoma cell-type-specific responses to MSCs in direct glioblastoma co-cultures, where MSCs inhibited the invasion of U87 cells and enhanced the invasion of U373. Inversely, direct cross-talk between MSCs and both of glioblastoma cell lines enhanced MSC motility. MSC-enhanced invasion of U373 cells was assisted by overexpression of proteases cathepsin B, calpain1, uPA/uPAR, MMP-2, -9 and -14, and increased activities of some of these proteases, as determined by the effects of their selective inhibitors on invasion. In contrast, these proteases had no effect on U87 cell invasion under MSC co-culturing. Finally, we identified differentially expressed genes, in U87 and U373 cells that could explain different response of these cell lines to MSCs. In conclusion, we demonstrated that MSC/glioblastoma cross-talk is different in the two glioblastoma cell phenotypes, which contributes to tumor heterogeneity.
Keywords: glioblastoma multiforme, proteases, mesenchymal stem cells, tumor heterogeneity, zebrafish model
Published in DiRROS: 24.07.2024; Views: 382; Downloads: 234
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1305. Pridobivanje in uporaba ekstraktivov iz lesa in drevesne skorjePrimož Oven, Ida Poljanšek, Urša Osolnik, Viljem Vek, 2024, original scientific article Abstract: Ekstraktivi so nizkomolekularne spojine, ki so v vseh rastlinskih tkivih, tudi v lesu in drevesni skorji. V drevesu imajo pomembne ekološke in fiziološke funkcije, obenem pa predstavljajo bioosnovane proizvode z visoko dodano vrednostjo, ki jih je mogoče pridobivati tudi iz lesa slabše kakovosti in biomasnih ostankov gozdnih lesnih verig. V prispevku bomo ekstraktive razvrstili, pojasnili, kakšna je kakovostna in količinska spremenljivost po posameznih tkivih izbranih drevesnih vrst, predstavili bomo načine pridobivanja in področja uporabe. Ocenjujemo, da je pridobivanje ekstraktivov dokaj enostaven tehnološki postopek, ki bi bil v obliki manjše biorafinerije izvedljiv v lokalnih okoljih, kjer so na voljo zadostne količine lesne biomase.
Keywords: les, skorja, ekstraktivi, kaskadna raba, biorafinacija
Published in DiRROS: 24.07.2024; Views: 386; Downloads: 103
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1306. Inter-laboratory assessment of different digital PCR platforms for quantification of human cytomegalovirus DNAJernej Pavšič, Alison S. Devonshire, Andrej Blejec, Carole A. Foy, Fran Van Heuverswyn, Gerwyn M. Jones, Heinz Schimmel, Jana Žel, Jim F. Huggett, Nicholas Redshaw, Maria Karczmarczyk, Erkan Mozioglu, Sema Akyürek, Müslüm Akgöz, Mojca Milavec, 2017, original scientific article Abstract: Quantitative PCR (qPCR) is an important tool in pathogen detection. However, the use of different qPCR components, calibration materials and DNA extraction methods reduces comparability between laboratories, which can result in false diagnosis and discrepancies in patient care. The wider establishment of a metrological framework for nucleic acid tests could improve the degree of standardisation of pathogen detection and the quantification methods applied in the clinical context. To achieve this, accurate methods need to be developed and implemented as reference measurement procedures, and to facilitate characterisation of suitable certified reference materials. Digital PCR (dPCR) has already been used for pathogen quantification by analysing nucleic acids. Although dPCR has the potential to provide robust and accurate quantification of nucleic acids, further assessment of its actual performance characteristics is needed before it can be implemented in a metrological framework, and to allow adequate estimation of measurement uncertainties. Here, four laboratories demonstrated reproducibility (expanded measurement uncertainties below 15%) of dPCR for quantification of DNA from human cytomegalovirus, with no calibration to a common reference material. Using whole-virus material and extracted DNA, an intermediate precision (coefficients of variation below 25%) between three consecutive experiments was noted. Furthermore, discrepancies in estimated mean DNA copy number concentrations between laboratories were less than twofold, with DNA extraction as the main source of variability. These data demonstrate that dPCR offers a repeatable and reproducible method for quantification of viral DNA, and due to its satisfactory performance should be considered as candidate for reference methods for implementation in a metrological framework.
Keywords: digital PCR, DNA quantification, inter-laboratory assessment, human cytomegalovirus, virus reference materials
Published in DiRROS: 24.07.2024; Views: 417; Downloads: 239
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1307. Učinkovitost zatiranja invazivne tujerodne vrste navadne barvilnice : poraba časa in potencialne izboljšave pri negi mladjaPeter Smolnikar, Urban Žitko, Marija Kolšek, Matevž Triplat, 2024, original scientific article Abstract: V svetu invazivne tujerodne vrste rastlin (ITVR) povzročajo mnoge spremembe v okolju. Za zatiranje ITVR je znanih precej metod, primernost posamezne in posledično tudi uspešnost pa sta odvisni od vsakega primera posebej – predvsem od cilja, ki ga želimo doseči z zatiranjem. V študiji smo spremljali zatiranje navadne barvilnice v okviru nege mladja, tj. z rezjo pri tleh. Študija je potekala na objektu s površino 2,82 ha, dela so izvajali trije delavci. Cilji študije so bili ugotoviti porabo časa na površino in pridobiti manjkajoča znanja na področju izvajanja dodatnih ukrepov pri negi mladja. V povprečju so delavci za en hektar obžetve potrebovali 18,8 ure produktivnega časa. Po simulaciji študije na osemurni delavnik faktor neproduktivnega časa znaša 1,39 (σ = 0,053) in je nižji od priznanega državnega faktorja neproduktivnega časa (1,58) za sečnjo. Pri interpretaciji rezultatov je potrebna previdnost, ker so pri kratkotrajnih (manj obsežnih) študijah pogosto podcenjeni faktorji neproduktivnega časa. Teoretični izračun, ki temelji na linearni regresiji podatkov, kaže, da je za obžetev enega hektara v celoti potrebno okrog dvaindvajset ur. Kljub že tako nizkemu faktorju neproduktivnega časa je še rezerva za optimizacijo delovnega procesa, vendar so za to potrebne dolgotrajnejše in obsežnejše študije časa.
Keywords: gozdarstvo, invazivne rastline, zatiranje, nega pomladka, časovna študija, Phytolacca americana
Published in DiRROS: 24.07.2024; Views: 333; Downloads: 120
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1308. Usmerjanje obnove, nege in varstva gozdovaBoris Rantaša, Aleš Poljanec, 2024, preface, editorial, afterword Keywords: obnova načrtov, gospodarjenje z gozdovi, nega gozdov, varstvo gozdov
Published in DiRROS: 24.07.2024; Views: 434; Downloads: 125
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1310. Cathepsin K cleavage of SDF-1[alpha] inhibits its chemotactic activity towards glioblastoma stem-like cellsVashendriya V. V. Hira, Urška Verbovšek, Barbara Breznik, Matic Srdič, Marko Novinec, Hala Kakar, Jill Wormer, Britt van der Swaan, Brigita Lenarčič, Luiz Juliano, Shwetal Mehta, Cornelis J. F. van Noorden, Tamara Lah Turnšek, 2017, original scientific article Abstract: Glioblastoma (GBM) is the most aggressive primary brain tumor with poor patient survival that is at least partly caused by malignant and therapy-resistant glioma stem-like cells (GSLCs) that are protected in GSLC niches. Previously, we have shown that the chemo-attractant stromal-derived factor-1α (SDF-1α), its C-X-C receptor type 4 (CXCR4) and the cysteine protease cathepsin K (CatK) are localized in GSLC niches in glioblastoma. Here, we investigated whether SDF-1α is a niche factor that through its interactions with CXCR4 and/or its second receptor CXCR7 on GSLCs facilitates their homing to niches. Furthermore, we aimed to prove that SDF-1α cleavage by CatK inactivates SDF-1α and inhibits the invasion of GSLCs. We performed mass spectrometric analysis of cleavage products of SDF-1α after proteolysis by CatK. We demonstrated that CatK cleaves SDF-1α at 3 sites in the N-terminus, which is the region of SDF-1α that binds to its receptors. Confocal imaging of human GBM tissue sections confirmed co-localization of SDF-1α and CatK in GSLC niches. In accordance, 2D and 3D invasion experiments using CXCR4/CXCR7-expressing GSLCs and GBM cells showed that SDF-1α had chemotactic activity whereas CatK cleavage products of SDF-1α did not. Besides, CXCR4 inhibitor plerixafor inhibited invasion of CXCR4/CXCR7-expressing GSLCs.
In conclusion, CatK can cleave and inactivate SDF-1α. This implies that CatK activity facilitates migration of GSLCs out of niches. We propose that activation of CatK may be a promising strategy to prevent homing of GSLCs in niches and thus render these cells sensitive to chemotherapy and radiation.
Keywords: glioma stem-like cells, niche, stromal derived factor-[alpha], cathepsin K
Published in DiRROS: 24.07.2024; Views: 337; Downloads: 258
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