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Query: "author" (Damjana Drobne) .

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Morphological characteristics of young and old murine hematopoietic stem cell niches, as modeled in vitro
Mojca Justin, Ema Rogac Randl, Veno Kononenko, Matej Hočevar, Damjana Drobne, Primož Rožman, 2023, original scientific article

Abstract: The hematopoietic stem cell (HSC) niche undergoes detrimental changes with age. The molecular differences between young and old niches are well studied and understood; however, young and old niches have not yet been extensively characterized in terms of morphology. In the present work, a 2D stromal model of young and old HSC niches isolated from bone marrow was investigated using light and scanning electron microscopy (SEM) to characterize cell density after one, two, or three weeks of culturing, cell shape, and cell surface morphological features. Our work is aimed at identifying morphological differences between young and old niche cells that could be used to discriminate between their respective murine HSC niches. The results show several age- specific morphological characteristics. The old niches differ from the young ones in terms of lower cell proliferating capacity, increased cell size with a flattened appearance, increased number of adipocytes, and the presence of tunneling nanotubes. In addition, proliferating cell clusters are present in the young niches but not in the old niches. Together, these characteristics could be used as a relatively simple and reliable tool to discriminate between young and old murine HSC niches and as a complementary approach to imaging with specific cellular markers.
Keywords: bone marrow, hematoopetic stem cell niche, aging, adipocytes, scanning electron microscopy
Published in DiRROS: 26.01.2024; Views: 152; Downloads: 67
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Environmental hazard of polypropylene microplastics from disposable medical masks : acute toxicity towards Daphnia magna and current knowledge on other polypropylene microplastics
Anita Jemec Kokalj, Andraž Dolar, Damjana Drobne, Marjan Marinšek, Matej Dolenec, Luka Škrlep, Gregor Strmljan, Branka Mušič, Andrijana Sever Škapin, 2022, original scientific article

Abstract: The COVID-19 pandemic has increased the use of disposable plastics, including medical masks, which have become a necessity in our daily lives. As these are often improperly disposed of, they represent an important potential source of microplastics in the environment. We prepared microplastics from polypropylene medical masks and characterised their size, shape, organic chemical leaching, and acute toxicity to the planktonic crustacean Daphnia magna. The three layers of the masks were separately milled and characterised. Each of the inner frontal, middle filtering, and outer layers yielded different types of microplastics: fibres were obtained from the inner and outer layer, but irregular fragments from the middle layer. The shape of the obtained microplastics differed from the initial fibrous structure of the intact medical mask layers, which indicates that the material is deformed during cryo-milling. The chemical compositions of plastics-associated chemicals also varied between the different layers. Typically, the inner layer contained more chemicals related to antimicrobial function and flavouring. The other two layers also contained antioxidants and their degradation products, plasticisers, cross-linking agents, antistatic agents, lubricants, and non-ionic surfactants. An acute study with D. magna showed that these microplastics do not cause immobility but do physically interact with the daphnids. Further long-term studies with these microplastics are needed using a suite of test organisms. Indeed, studies with other polypropylene microplastics have shown numerous adverse effects on other organisms at concentrations that have already been reported in the environment. Further efforts should be made to investigate the environmental hazards of polypropylene microplastics from medical masks and how to handle this new source of environmental burden.
Keywords: COVID-19 pandemic, plastics-associated chemicals, Daphnia magna, fibres, fragments, nanofibres, polypropylene microplastics, single-use plastic
Published in DiRROS: 05.05.2023; Views: 301; Downloads: 190
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5.
Decrease in cellular nanovesicles concentration in blood of athletes more than 15 hours after marathon
Zala Jan, Mitja Drab, Damjana Drobne, Apolonija Bedina Zavec, Mojca Benčina, Barbara Drašler, Matej Hočevar, Judita Lea Krek, Ljubiša Pađen, Manca Pajnič, Neža Repar, Boštjan Šimunič, Roman Štukelj, Veronika Kralj-Iglič, 2021, original scientific article

Abstract: Introduction: Cellular nanovesicles (CNVs), that are shed from cells, have been recognized as promising indicators of health status. We analyzed the effect of long-distance running on concentration of CNVs, along with some standard blood parameters, in 27 athletes two days before and > 15 hours after physical effort. Methods: CNVs were isolated by repetitive centrifugation and washing of samples, and assessed by flow cytometry. Cholinesterase (ChE) and glutathione S-transferase (GST) activity were measured spectrophotometrically. Interleukin 6 (IL-6) and tumor necrosis factor-% (TNF-%) concentrations were measured using enzyme-linked immunosorbent assay (ELISA). C-reactive protein (CRP) was measured with immunoturbidimetric determination and lipidogram parameters were measured by enzymatic colorimetric assay. Flow cytometry was used for blood cell count and mean platelet volume (MPV) measurement. Results: More than 15 hours after physical effort a decrease was found in CNVs% concentration in isolates from blood (46%; p< 0.05), in ChE activity in whole blood (47%; p< 0.001), in plasma (34%; p< 0.01), and in erythrocyte suspension (54%; p< 0.001), as well as in GST activity in erythrocyte suspension (16%; p< 0.01) and in IL-6 concentration in plasma (63%; p< 0.05). We found no change in GST activity in plasma and in TNF-% concentration in plasma. Correlations (> 0.8; p< 0.001) between CNVs% concentration and ChE activity, and GST activity, respectively, in erythrocyte suspension were found. Conclusion: We found that > 15 hours post-physical effort, CNVs% concentration was below the initial value, concomitant with other measured parameters: ChE and GST activity as well as IL-6 concentration, indicating a favorable effect of physical effort on health status. CNVs% concentration and ChE activity in isolates from peripheral blood proved to have potential as indicators of the response of the human body to inflammation after physical effort. Physical activity should be considered as an important factor in preparation of subjects for blood sampling in procedures focusing on CNV-containing diagnostic and therapeutic compounds.
Keywords: membrane vesiculation, physical effort, blood samples, inflammation process, cellular nanovesicles, marathon
Published in DiRROS: 25.01.2021; Views: 1242; Downloads: 1014
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