1. Parodontalna bolezen in mitohondrijska disfunkcijaRomana Mance Kristan, 2025, doktorska disertacija Opis: Uvod: Parodontalna bolezen (PB) kot posledica porušenega ravnotežja med bakterijami in gostiteljem vodi v vnetno-imunski odgovor gostitelja ter vpliva na splošno zdravstveno stanje posameznika. Oceno napredovalosti PB merimo s parodontalnimi parametri, iz katerih lahko izračunamo površino parodontalnega vnetja (PISA). Naša hipoteza je, da večje število globokih obzobnih žepov in večja PISA pomenijo višjo vrednost vnetnih biomarkerjev, kot so C-reaktivni protein (CRP), število levkocitov, predvsem nevtrofilcev, nižje razmerje med magnezijem in kalcijem, manjšo količino antioksidantov ter nižje število kopij mitohondrijske deoksiribonukleinske kisline (mtDNAcn).
Materiali in metode: S pomočjo parodontalnih parametrov smo izračunali vrednost PISA. V serumu smo izmerili nivo vnetnih biomarkerjev in antioksidantov ter iz brisa lične sluznice izolirali mitohondrijsko (mtDNA) in jedrno DNA (nDNA) ter izračunali mtDNAcn.
Rezultati: Večje število globokih obzobnih žepov in višjo vrednost PISA smo povezali z višjim CRP, večjim številom levkocitov, nevtrofilcev in eritrocitov, nižjim razmerjem magnezija in kalcija ter višjim nivojem sečne kisline v serumu, ne pa z nižjim mtNDAcn v brisu lične sluznice.
Zaključki: Med številom globokih obzobnih žepov in vrednostjo PISA obstaja pozitivna korelacija. Vrednost PISA je ustrezen parameter za določanje vnetnega bremena PB, ni pa nujno ustrezen parameter za določanje mitohondrijske disfunkcije po izolaciji mtDNA iz brisa lične sluznice.
Ključne besede: velikost vnetnega področja v obzobnem žepu (PISA), biomarkerji mitohondrijske disfunkcije, število kopij mitohondrijske DNA (mtDNAcn)
Objavljeno v DKUM: 05.11.2025; Ogledov: 0; Prenosov: 1
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2. Learning analytics : a case study on exploring social interaction and problem-solving strategiesVladimir Grubelnik, Nataša Rizman Herga, Andrej Flogie, Mihaela Brumen, Marko Marhl, Dejan Dinevski, 2025, izvirni znanstveni članek Opis: Purpose: The purpose of this study is to preliminarily verify the concept of personalised and collaborative learning and to formatively observe students' knowledge, skills, problem-solving strategies and social dynamics in the classroom. Study design/methodology/approach: The study was conducted with 8th grade students (N=21) using the ClassRoom Analytica (CRA) application as part of a thematic unit on ionic bonds. Students participated in digitally facilitated group problem-solving activities guided by predefined parameters for accessing information. Findings: The use of the CRA application proved highly beneficial in a heterogeneous class as it was responsive to all students and provided the teacher with detailed information about each individual’s role within the class. Originality/value: This study presents CRA as a novel integration of learning analytics and domain-specific visualisations in the science classroom.
Ključne besede: learning analytics, social interaction, problem-solving
Objavljeno v DKUM: 23.07.2025; Ogledov: 0; Prenosov: 11
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3. Optimizing digital image quality for improved skin cancer detectionBogdan Dugonik, Marjan Golob, Marko Marhl, Aleksandra Vučinič Dugonik, 2025, izvirni znanstveni članek Opis: The rising incidence of skin cancer, particularly melanoma, underscores the need for improved diagnostic tools in dermatology. Accurate imaging plays a crucial role in early detection, yet challenges related to color accuracy, image distortion, and resolution persist, leading to diagnostic errors. This study addresses these issues by evaluating color reproduction accuracy across various imaging devices and lighting conditions. Using a ColorChecker test chart, color deviations were measured through Euclidean distances (∆E*, ∆C*), and nonlinear color differences (∆E00, ∆C00), while the color rendering index (CRI) and television lighting consistency index (TLCI) were used to evaluate the influence of light sources on image accuracy. Significant color discrepancies were identified among mobile phones, DSLRs, and mirrorless cameras, with inadequate dermatoscope lighting systems contributing to further inaccuracies. We demonstrate practical applications, including manual camera adjustments, grayscale reference cards, post-processing techniques, and optimized lighting conditions, to improve color accuracy. This study provides applicable solutions for enhancing color accuracy in dermatological imaging, emphasizing the need for standardized calibration techniques and imaging protocols to improve diagnostic reliability, support AI-assisted skin cancer detection, and contribute to high-quality image databases for clinical and automated analysis.
Ključne besede: dermoscopy, melanoma, color analysis, color error, spectral power distribution, grey card, digital imaging standards
Objavljeno v DKUM: 08.04.2025; Ogledov: 0; Prenosov: 4
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4. The changing world dynamics of research performanceMarko Marhl, Rene Markovič, Vladimir Grubelnik, Matjaž Perc, 2025, izvirni znanstveni članek Opis: In recent years, a notable diversification in the geographical representation of the World's top universities could be observed. Chinese universities play an increasingly prominent role in these rankings, thus indicating that we might be in the midst of a regional shift in academic performance. To explore this dynamics, we analyze seven years' worth of data used for university rankings by academic subjects from the Academic Ranking of World Universities (ARWU). We focus on China, Europe, the USA, and other global regions of the world. We find that China has indeed seen an unprecedented growth in Engineering and Life Sciences research, positioning itself rather firmly as a leader in these fields. Conversely, the USA leads in the Social Sciences, while Europe excels in Geography, Ecology, Public and Business Administration, and Pharmacy. Other regions worldwide stand out in Transportation Science, Nursing, and Hospitality & Tourism Management. These results reveal the evolving landscape of global academic research, highlighting regional strengths and emerging world trends in subject-specifc excellence.
Ključne besede: research dynamics, academic excellence, geographical diversifcation, University rankings
Objavljeno v DKUM: 11.02.2025; Ogledov: 0; Prenosov: 8
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7. NMDA receptor inhibition increases, synchronizes, and stabilizes the collective pancreatic beta cell activity : insights through multilayer network analysisMarko Šterk, Lidija Križančić Bombek, Maša Skelin, Marjan Rupnik, Marko Marhl, Andraž Stožer, Marko Gosak, 2021, izvirni znanstveni članek Opis: NMDA receptors promote repolarization in pancreatic beta cells and thereby reduce glucose-stimulated insulin secretion. Therefore, NMDA receptors are a potential therapeutic target for diabetes. While the mechanism of NMDA receptor inhibition in beta cells is rather well understood at the molecular level, its possible effects on the collective cellular activity have not been addressed to date, even though proper insulin secretion patterns result from well-synchronized beta cell behavior. The latter is enabled by strong intercellular connectivity, which governs propagating calcium waves across the islets and makes the heterogeneous beta cell population work in synchrony. Since a disrupted collective activity is an important and possibly early contributor to impaired insulin secretion and glucose intolerance, it is of utmost importance to understand possible effects of NMDA receptor inhibition on beta cell functional connectivity. To address this issue, we combined confocal functional
multicellular calcium imaging in mouse tissue slices with network science approaches. Our results revealed that NMDA receptor inhibition increases, synchronizes, and stabilizes beta cell activity without affecting the velocity or size of calcium waves. To explore intercellular interactions more precisely, we made use of the multilayer network formalism by regarding each calcium wave as an individual network layer, with weighted directed connections portraying the intercellular propagation. NMDA receptor inhibition stabilized both the role of wave initiators and the course of waves. The findings obtained with the experimental antagonist of NMDA receptors, MK-801, were additionally validated with dextrorphan, the active metabolite of the approved drug dextromethorphan, as well as with experiments on NMDA receptor KO mice. In sum, our results provide additional and new evidence for a possible
role of NMDA receptor inhibition in treatment of type 2 diabetes and introduce the multilayer network paradigm as a general strategy to examine effects of drugs on connectivity in multicellular systems.
Ključne besede: pancreas, beta cells, insulin, Islets of Langerhans
Objavljeno v DKUM: 29.11.2024; Ogledov: 0; Prenosov: 6
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8. Socio-demographic and health factors drive the epidemic progression and should guide vaccination strategies for best COVID-19 containmentRene Markovič, Marko Šterk, Marko Marhl, Matjaž Perc, Marko Gosak, 2021, izvirni znanstveni članek Opis: We propose and study an epidemiological model on a social network that takes into account heterogeneity of the population and different vaccination strategies. In particular, we study how the COVID-19 epidemics evolves and how it is contained by different vaccination scenarios by taking into account data showing that older people, as well as individuals with comorbidities and poor metabolic health, and people coming from economically depressed areas with lower quality of life in general, are more likely to develop severe COVID-19 symptoms, and quicker loss of immunity and are therefore more prone to reinfection. Our results reveal that the structure and the spatial arrangement of subpopulations are important epidemiological determinants. In a healthier society the disease spreads more rapidly but the consequences are less disastrous as in a society with more prevalent chronic comorbidities. If individuals with poor health are segregated within one community, the epidemic outcome is less favorable. Moreover, we show that, contrary to currently widely adopted vaccination policies, prioritizing elderly and other higher-risk groups is beneficial only if the supply of vaccine is high. If, however, the vaccination availability is limited, and if the demographic distribution across the social network is homogeneous, better epidemic outcomes are achieved if healthy people are vaccinated first. Only when higher-risk groups are segregated, like in elderly homes, their prioritization will lead to lower COVID-19 related deaths. Accordingly, young and healthy individuals should view vaccine uptake as not only protecting them, but perhaps even more so protecting the more vulnerable socio-demographic groups.
Ključne besede: epidemic model, COVID-19, vaccination strategy, vaccination strategy, population heterogeneity, socio-demographic structure, metabolic disease, social network
Objavljeno v DKUM: 14.11.2024; Ogledov: 0; Prenosov: 12
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9. Modelling of dysregulated glucagon secretion in type 2 diabetes by considering mitochondrial alterations in pancreatic ▫$\alpha$▫-cellsVladimir Grubelnik, Rene Markovič, Saška Lipovšek Delakorda, Gerd Leitinger, Marko Gosak, Jurij Dolenšek, Ismael Valladolid-Acebes, Per-Olof Berggren, Andraž Stožer, Matjaž Perc, Marko Marhl, 2020, izvirni znanstveni članek Opis: Type 2 diabetes mellitus (T2DM) has been associated with insulin resistance and the failure of β-cells to produce and secrete enough insulin as the disease progresses. However, clinical treatments based solely on insulin secretion and action have had limited success. The focus is therefore shifting towards α-cells, in particular to the dysregulated secretion of glucagon. Our qualitative electron-microscopy-based observations gave an indication that mitochondria in α-cells are altered in Western-diet-induced T2DM. In particular, α-cells extracted from mouse pancreatic tissue showed a lower density of mitochondria, a less expressed matrix and a lower number of
cristae. These deformities in mitochondrial ultrastructure imply a decreased efficiency in mitochondrial ATP production, which prompted us to theoretically explore and clarify one of the most challenging problems associated with T2DM, namely the lack of glucagon secretion in hypoglycaemia and its oversecretion at high blood glucose concentrations. To this purpose, we constructed a novel computational model that links α-cell metabolism with their electrical activity and glucagon secretion. Our results show that defective mitochondrial metabolism in α-cells can
account for dysregulated glucagon secretion in T2DM, thus improving our understanding of T2DM pathophysiology and indicating possibilities for new clinical treatments.
Ključne besede: diabetes, pancreatic alpha cells, glucagon, mitochondrial dysfunction, free fatty acid
Objavljeno v DKUM: 03.09.2024; Ogledov: 49; Prenosov: 7
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10. Mitochondrial dysfunction in pancreatic alpha and beta cells associated with type 2 diabetes mellitusVladimir Grubelnik, Jan Zmazek, Rene Markovič, Marko Gosak, Marko Marhl, 2020, izvirni znanstveni članek Opis: Type 2 diabetes mellitus is a complex multifactorial disease of epidemic proportions. It involves genetic and lifestyle factors that lead to dysregulations in hormone secretion and metabolic homeostasis. Accumulating evidence indicates that altered mitochondrial structure, function, and particularly bioenergetics of cells in different tissues have a central role in the pathogenesis of type 2 diabetes mellitus. In the present study, we explore how mitochondrial dysfunction impairs the coupling between metabolism and exocytosis in the pancreatic alpha and beta cells. We demonstrate that reduced mitochondrial ATP production is linked with the observed defects in insulin and glucagon secretion by utilizing computational modeling approach. Specifically, a 30-40% reduction in alpha cells' mitochondrial function leads to a pathological shift of glucagon secretion, characterized by oversecretion at high glucose concentrations and insufficient secretion in hypoglycemia. In beta cells, the impaired mitochondrial energy metabolism is accompanied by reduced insulin secretion at all glucose levels, but the differences, compared to a normal beta cell, are the most pronounced in hyperglycemia. These findings improve our understanding of metabolic pathways and mitochondrial bioenergetics in the pathology of type 2 diabetes mellitus and might help drive the development of innovative therapies to treat various metabolic diseases.
Ključne besede: pancreatic endocrine cells, mathematical model, mitochondrial dysfunction, cellular bioenergetics, diabetes, glucagon, insulin
Objavljeno v DKUM: 03.09.2024; Ogledov: 47; Prenosov: 16
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