Extrachromosomal Circular DNA (eccDNA): From Chaos to Function

Extrachromosomal circular DNA (eccDNA) is a type of double-stranded circular DNA that is derived and free from chromosomes. It has a strong heterogeneity in sequence, length, and origin and has been identified in both normal and cancer cells. Although many studies suggested its potential roles in various physiological and pathological procedures including aging, telomere and rDNA maintenance, drug resistance, and tumorigenesis, the functional relevance of eccDNA remains to be elucidated. Recently, due to technological advancements, accumulated evidence highlighted that eccDNA plays an important role in cancers by regulating the expression of oncogenes, chromosome accessibility, genome replication, immune response, and cellular communications. Here, we review the features, biogenesis, physiological functions, potential functions in cancer, and research methods of eccDNAs with a focus on some open problems in the field and provide a perspective on how eccDNAs evolve specific functions out of the chaos in cells.

Cellular coverage probability is independent of base station density under stochastic geometric models

Stochastic geometry (SG) has been extensively used to model cellular communications, under the assumption that the base stations (BS) are deployed as a Poisson point process in the Euclidean plane. This has spawned a huge number of articles over the past years for different scenarios, culminating in an equally huge number of expressions for the coverage probability in both the uplink (UL) and downink (DL) directions. The trouble is that those expressions include the BS density, $\lambda$, which we prove irrelevant in this article. We start by developing a SG model for a baseline cellular scenario, then prove that the coverage probability is independent of $\lambda$, contrary to popular belief.

Actual problems of counteraction to crimes committed using cellular communications

The article deals with issues related to the current state of crimes committed using mobile phones. The existing statistics indicate a stable growth in this type of crimes, while their disclosure and investigation are particularly difficult, which is explained by their high latency and complexity of proof. The necessary scientific developments lagged significantly behind practice and became widespread only at the end of the last decade, while not finding widespread implementation in the activities of law enforcement agencies. These circumstances make it necessary to work proactively, taking into account the widespread introduction of new technical devices and software tools.

Cardiac Fibrosis: Cellular Effectors, Molecular Pathways, and Exosomal Roles

Cardiac fibrosis, a common pathophysiologic process in most heart diseases, refers to an excess of extracellular matrix (ECM) deposition by cardiac fibroblasts (CFs), which can lead to cardiac dysfunction and heart failure subsequently. Not only CFs but also several other cell types including macrophages and endothelial cells participate in the process of cardiac fibrosis via different molecular pathways. Exosomes, ranging in 30–150 nm of size, have been confirmed to play an essential role in cellular communications by their bioactive contents, which are currently a hot area to explore pathobiology and therapeutic strategy in multiple pathophysiologic processes including cardiac fibrosis. Cardioprotective factors such as RNAs and proteins packaged in exosomes make them an excellent cell-free system to improve cardiac function without significant immune response. Emerging evidence indicates that targeting selective molecules in cell-derived exosomes could be appealing therapeutic treatments in cardiac fibrosis. In this review, we summarize the current understandings of cellular effectors, molecular pathways, and exosomal roles in cardiac fibrosis.

Individual Abuse of Collective Dominance in Cellular Communications: Problems of Identification

Recently, discussions about the validity of the Russian practice of establishing the facts of individual abuse of collective dominance have been escalating: many experts point to a contradiction between the meaning of collective dominance, in which a small number of companies have a joint dominant position, in connection with each other, and the possibility of an individual company to abuse this position. The purpose of the article is to assess the correctness of this approach in the context of recent antitrust cases in the cellular communications market – in particular, two cases against the mobile operator “Tele2”. In the article, the applied practice is assessed in relation to the currently known results in the field of economic theory, as well as international best practices in the application of the concept of collective dominance. The findings indicate that the conclusion of the FAS Russia on the presence of the dominant position of Tele2 as part of collective dominance and the possibility of the company to exercise its market power does not correspond to either foreign practice or industrial organization theory. The source of error in the qualification of behavior is largely due to the focus of the antimonopoly authority on quantitative criteria of collective dominance to the detriment of the analysis of qualitative criteria and behavior. This case illustrates a typical tendency for such cases not to investigate the behavior of other collectively dominant market participants in relation to the behavior of the company accused of individual abuse, as well as not to investigate consumer behavior, and, in particular, their real possibilities to switch and switching actions. The article was written on the basis of the RANEPA state assignment research programme.

Modeling of the Сellular Сommunication System Coverage Area Taking into Account the External Details of the Terrain

This paper proposes a new approach to estimating the contour of the coverage zone for a cellular communications base station that takes into account meaningful reflecting objects located out of the considering zone. Based on this approach, the procedure for modeling and designing the cellular system coverage area. Unlike known methods, the developed procedure considers the influence of electromagnetic wave reflection from external details of the relief, in particular essential reflecting objects located outside the considered cell. The effect of the external objects on the formation of the coverage area resulting contour is considered analytically, numerically and experimentally. The proposed solution leads to more accurate designing of the coverage area for each cell. This creates the opportunity for further development of designing techniques to more effective engineering solutions at developing and applying cellular communication systems in real situations and at various scenarios.

High-throughput production of functional prototissues capable of producing NO for vasodilation

Bottom-up synthesis of prototissues helps us to understand the internal cellular communications in the natural tissues and their functions, as well as to improve or repair the damaged tissues. The existed prototissues are rarely used to improve the function of living tissues. We demonstrated a methodology to produce spatially programmable prototissues based on the magneto-Archimedes effect in a high-throughput manner. More than 2000 prototissues are produced once within 2 hours. Two-component and three-component spatial coded prototissues are fabricated by varying the addition giant unilamellar vesicles (GUVs) order/number, and the magnetic field distributions. Two-step and three-step signal communications in the prototissues are realized using cascade enzyme reactions. More importantly, the two-component prototissues capable of producing nitric oxide (NO) cause vasodilation of rat blood vessels in the presence of glucose and hydroxyurea. The tension force decreases 2.59 g, meanwhile the blood vessel relaxation is of 31.2%. Our works pave the path to fabricate complicated programmable prototissues, and hold great potential in tissue transplantation in the biomedical field.