1. From isles of Königsberg to islets of Langerhans: examining the function of the endocrine pancreas through network scienceAndraž Stožer, Marko Šterk, Eva Paradiž, Rene Markovič, Maša Skelin, Cara E. Ellis, Lidija Križančić Bombek, Jurij Dolenšek, Patrick E. MacDonald, Marko Gosak, 2022, review article Abstract: Islets of Langerhans are multicellular microorgans located in the pancreas that play a central role in whole-body energy homeostasis. Through secretion of insulin and other hormones they regulate postprandial storage and interprandial usage of energy-rich nutrients. In these clusters of hormone-secreting endocrine cells, intricate cell-cell communication is essential for proper function. Electrical coupling between the insulin-secreting beta cells through gap junctions composed of connexin36 is particularly important, as it provides the required, most important, basis for coordinated responses of the beta cell population. The increasing evidence that gap-junctional communication and its modulation are vital to well-regulated secretion of insulin has stimulated immense interest in how subpopulations of heterogeneous beta cells are functionally arranged throughout the islets and how they mediate intercellular signals. In the last decade, several novel techniques have been proposed to assess cooperation between cells in islets, including the prosperous combination of multicellular imaging and network science. In the present contribution, we review recent advances related to the application of complex network approaches to uncover the functional connectivity patterns among cells within the islets. We first provide an accessible introduction to the basic principles of network theory, enumerating the measures characterizing the intercellular interactions and quantifying the functional integration and segregation of a multicellular system. Then we describe methodological approaches to construct functional beta cell networks, point out possible pitfalls, and specify the functional implications of beta cell network examinations. We continue by highlighting the recent findings obtained through advanced multicellular imaging techniques supported by network-based analyses, giving special emphasis to the current developments in both mouse and human islets, as well as outlining challenges offered by the multilayer network formalism in exploring the collective activity of islet cell populations. Finally, we emphasize that the combination of these imaging techniques and network-based analyses does not only represent an innovative concept that can be used to describe and interpret the physiology of islets, but also provides fertile ground for delineating normal from pathological function and for quantifying the changes in islet communication networks associated with the development of diabetes mellitus.
Keywords: pancreatic islets, beta cells, calcium imaging, intercellular communication, functional networks, multilayer networks
Published in DKUM: 20.12.2024; Views: 0; Downloads: 3
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2. Network representation of multicellular activity in pancreatic islets : Technical considerations for functional connectivity analysisMarko Šterk, Yaowen Zhang, Viljem Pohorec, Eva Paradiž, Jurij Dolenšek, Richard K. P. Benninger, Andraž Stožer, Vira Kravets, Marko Gosak, 2024, original scientific article Abstract: Within the islets of Langerhans, beta cells orchestrate synchronized insulin secretion, a pivotal aspect of metabolic homeostasis. Despite the inherent heterogeneity and multimodal activity of individual cells, intercellular coupling acts as a homogenizing force, enabling coordinated responses through the propagation of intercellular waves. Disruptions in this coordination are implicated in irregular insulin secretion, a hallmark of diabetes. Recently, innovative approaches, such as integrating multicellular calcium imaging with network analysis, have emerged for a quantitative assessment of the cellular activity in islets. However, different groups use distinct experimental preparations, microscopic techniques, apply different methods to process the measured signals and use various methods to derive functional connectivity patterns. This makes comparisons between findings and their integration into a bigger picture difficult and has led to disputes in functional connectivity interpretations. To address these issues, we present here a systematic analysis of how different approaches influence the network representation of islet activity. Our findings show that the choice of methods used to construct networks is not crucial, although care is needed when combining data from different islets. Conversely, the conclusions drawn from network analysis can be heavily affected by the pre-processing of the time series, the type of the oscillatory component in the signals, and by the experimental preparation. Our tutorial-like investigation aims to resolve interpretational issues, reconcile conflicting views, advance functional implications, and encourage researchers to adopt connectivity analysis. As we conclude, we outline challenges for future research, emphasizing the broader applicability of our conclusions to other tissues exhibiting complex multicellular dynamics.
Keywords: islets of Langerhans, beta cells, calcium signaling, intercellular communication, functional networks, myosin model
Published in DKUM: 09.12.2024; Views: 0; Downloads: 3
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3. An optimal permutation routing algorithm on full-duplex hexagonal networksIgnasi Sau Walls, Janez Žerovnik, 2008, original scientific article Abstract: In the permutation routing problem, each processor is the origin of at most one packet and the destination of no more than one packet. The goal is to minimize the number of time steps required to route all packets to their respective destinations, under the constraint that each link can be crossed simultaneously by no more than one packet. We study this problem in a hexagonal network, i.e. a finite subgraph of a triangular grid, which is a widely used network in practical applications. We present an optimal distributed permutation routing algorithm for full-duplex hexagonal networks, using the addressing scheme described by Nocetti et al. Furthermore, we prove that this algorithm is oblivious and translation invariant.
Keywords: mathematics, hexagonal networks, permutation routing, shortest path, distributed algorithm, communication networks, oblivious algorithm
Published in DKUM: 10.07.2015; Views: 1210; Downloads: 200
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4. Elderly people and information communication technology (ICT) : issues, challenges, and opportunities for better quality of lifeHelena Blažun Vošner, Kaija Saranto, Sari Rissanen, Samo Bobek, 2013, independent scientific component part or a chapter in a monograph Keywords: information communication technology (ICT), online social networks, quality of life, elderly people
Published in DKUM: 10.07.2015; Views: 1928; Downloads: 93
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6. An optimal permutation routing algorithm for full-duplex hexagonal mesh networksIgnasi Sau Walls, Janez Žerovnik, 2006 Abstract: In the permutation routing problem, each processor is the origin of at most one packet and each processor is the destination of no more than one packet. We study this problem in an hexagonal network (that is, a finite convex subgraph of a triangular grid), a widely used network in practical applications. We use the addressing scheme described by F.G. Nocetti, I. Stojmenovic and J. Zhang (2002, IEEE Trans. on Parallel and Distrib. Systems). In this paper, a distributed optimal routing algorithm for full-duplex hexagonal mesh networks is presented. Furthermore, we prove that this algorithm is oblivious and translation invariant.
Keywords: mathematics, hexagonal networks, permutation routing, shortest path, distributed algorithm, communication networks, oblivious algorithm
Published in DKUM: 10.07.2015; Views: 1223; Downloads: 42
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7. Financial Times marketing casebookLevela Rickard, Kit Jackson, 2000, higher education textbook Keywords: consumerism, customer, consumer psychology, communication, market analysis, segmentation, marketing research, market structure, marketing, strategic planning, advertising, sale, sales promotion, personal selling, direct marketing, international business, international marketing, internet, computer networks, international business operation, market mechanism, textbooks, cases, case study
Published in DKUM: 01.06.2012; Views: 2153; Downloads: 68
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8. Advanced modelling and simulation methods for communication networksJože Mohorko, Matjaž Fras, Saša Klampfer, 2008, original scientific article Abstract: This paper contains a brief overview of suitable simulation tools available for education and research on network technologies and protocols. Among the mentioned tools we present advanced methods for network simulations using the OPNET modeler simulation tool. This is one of the most widespread simulation tools for network simulations, appropriate for both for teaching and also for the researching procedures of new internet devices and protocols. The basic package is intended for simulating communication networks and for protocols and devices development. There are also additional specific modules, such as a module assigned to the simulation of wireless networks, an ACE module for application analyzing, 3DNV module for visualizing networks on virtual terrain and the "System in the loop" module for simulating networks with real communication equipment in the loop, in real-time.
Keywords: network simulation, simulation tools, modelling, communication networks, OPNET
Published in DKUM: 31.05.2012; Views: 2209; Downloads: 60
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