Biophysical Mechanisms Research Articles

Structure and function of SARS-CoV-2 nucleocapsid protein measured using optical tweezers, confocal fluorescence, and AFM.

The nucleocapsid (N) protein, one of four structural proteins expressed by SARS-CoV-2, primarily functions by binding and compacting the ∼30 kilobase viral RNA genome (>10 μm linear length) to enable packaging into viral particles (<100 nm diameter). We use optical tweezers to isolate a single ssDNA substrate and observe the binding and compacting function of N protein in real time. The compaction is a multistep process, with kinetics consistent with initial diffusion-limited binding of free protein to the substrate followed by a sudden stochastically triggered reorganization of the protein-DNA complex into a compacted form. Experiments utilizing truncated protein variants lacking either the ordered N or C terminal domains (NTD and CTD) and the intrinsically disordered linker demonstrate that initial binding is driven by the NTD while the formation of the compacted DNA structure requires the CTD. We further localize the binding of fluorescently labeled protein along the substrate using confocal imaging, showing N protein able to both uniformly coat the entire length of the substrate non specifically and subsequently form dense protein clusters through interprotein oligomerization. Finally, various DNA and RNA substrates of differing lengths and sequences are incubated with either full length or truncated N protein and imaged using AFM. Measurement of these nucleic acid-protein complexes reveal both the binding activity of N protein and its ability to remodel complex, folded nucleic acid structures. Our results help elucidate the biophysical mechanism through which N protein enables efficient packaging of the long vRNA under physiological conditions.

Investigating the biophysical mechanisms regulating transcription in starved Escherichia coli via single-molecule tracking.

Bacteria have a robust stress response in starvation conditions, entering a quiescent stationary phase and remaining viable despite depletion of resources. An important component of this stress response is the upregulation of DNA-binding protein from starved cells (Dps) upon entry into the stationary phase. Dps promotes nucleoid condensation, protecting genetic information from harm. Intriguingly, this condensation does not affect the ability of RNA polymerase (RNAP) to access the nucleoid and transcribe RNA. The mechanism by which RNAP accesses the nucleoid under starvation conditions remains unclear. To investigate the dynamics of stationary-phase RNAP, we are applying live-cell single-molecule tracking of RNAP tagged with a photo-activatable fluorescent protein. In living E. coli cells, we find that compared to the dynamics of RNAP in the exponential growth phase, RNAP in the stationary phase spends less time bound to DNA, reflective of an expected decline in protein synthesis. Instead, stationary-phase RNAP spends the majority of its time in an intermediate dynamic state that we hypothesize results from frequent interactions with DNA as RNAP searches for its target sequence. Unexpectedly, the diffusion coefficient of this intermediate state increases in the stationary phase, even though the nucleoid is more compact and thus has a smaller pore size that could restrict motion. To isolate how Dps upregulation leads to changes in the dynamics of RNAP throughout the cell cycle, we over-expressed Dps and found that the RNAP dynamics were nearly identical to those measured with native Dps expression. Ultimately, these studies suggest that the interactions between RNAP and DNA are primarily biochemically driven, and do not depend on nucleoid pore size. Additionally, our results may indicate that Dps can be rapidly displaced by RNAP such that it does not interfere with target searching.

Isotope Substitution Effects on the Magnetic Compass Properties of Cryptochrome-Based Radical Pairs: A Computational Study.

The biophysical mechanism of the magnetic compass sense of migratory songbirds is thought to rely on the photochemical reactions of flavin-containing radical pairs in cryptochrome proteins located in the birds' eyes. A consequence of this hypothesis is that the effect of the Earth's magnetic field on the quantum yields of reaction products should be sensitive to isotopic substitutions that modify the hyperfine interactions in the radicals. In this report, we use spin dynamics simulations to explore the effects of 1H → 2H, 12C → 13C, and 14N → 15N isotopic substitutions on the functioning of cryptochrome 4a as a magnetic direction sensor. Two main conclusions emerge. (1) Uniform deuteration of the flavin chromophore appears to be the best way to boost the anisotropy of the magnetic field effect and to change its symmetry. (2) 13C substitution of three of the 12 flavin carbons, in particular C4, C4a, and C8α, seems to be the best recipe for attenuating the anisotropy. These predictions should give insight into the factors that control the magnetic sensitivity once spectroscopic techniques are available for measuring magnetic field effects on oriented protein samples.

Energy-guided synapse coupling between neurons under noise.

From a physical viewpoint, any external stimuli including noise disturbance can inject energy into the media, and the electric response is regulated by the equivalent electric stimulus. For example, mode transition in electric activities in neurons occurs and kinds of spatial patterns are formed during the wave propagation. In this paper, a feasible criterion is suggested to explain and control the growth of electric synapse and memristive synapse between Hindmarsh-Rose neurons in the presence of noise. It is claimed that synaptic coupling can be enhanced adaptively due to energy diversity, and the coupling intensity is increased to a saturation value until two neurons reach certain energy balance. Two identical neurons can reach perfect synchronization when electric synapse coupling is further increased. This scheme is also considered in a chain neural network and uniform noise is applied on all neurons. However, reaching synchronization becomes difficult for neurons in presenting spiking, bursting, and chaotic and periodic patterns, even when the local energy balance is corrupted to continue further growth of the coupling intensity. In the presence of noise, energy diversity becomes uncertain because of spatial diversity in excitability, and development of regular patterns is blocked. The similar scheme is used to control the growth of memristive synapse for neurons, and the synchronization stability and pattern formation are controlled by the energy diversity among neurons effectively. These results provide possible guidance for knowing the biophysical mechanism for synapse growth and energy flow can be applied to control the synchronous patterns between neurons.

The super elongation complex (SEC) mediates phase transition of SPT5 during transcriptional pause release.

Release of promoter-proximally paused RNA Pol II into elongation is a tightly regulated and rate-limiting step in metazoan gene transcription. However, the biophysical mechanism underlying pause release remains unclear. Here, we demonstrate that the pausing and elongation regulator SPT5 undergoes phase transition during transcriptional pause release. SPT5 per se is prone to form clusters. The disordered domain in SPT5 is required for pause release and gene activation. During early elongation, the super elongation complex (SEC) induces SPT5 transition into elongation droplets. Depletion of SEC increases SPT5 pausing clusters. Furthermore, disease-associated SEC mutations impair phase properties of elongation droplets and transcription. Our study suggests that SEC-mediated SPT5 phase transition might be essential for pause release and early elongation and that aberrant phase properties could contribute to transcription abnormality in diseases.

Magnetic field and nuclear spin influence on the DNA synthesis rate

The rate of a chemical reaction can be sensitive to the isotope composition of the reactants, which provides also for the sensitivity of such “spin-sensitive” reactions to the external magnetic field. Here we demonstrate the effect of the external magnetic field on the enzymatic DNA synthesis together with the effect of the spin-bearing magnesium ions (^{25}Mg). The rate of DNA synthesis monotonously decreased with the external magnetic field induction increasing in presence of zero-spin magnesium ions (^{24}Mg). On the contrary, in the presence of the spin-bearing magnesium ions, the dependence of the reaction rate on the magnetic field induction was non-monotonous and possess a distinct minimum at 80–100 mT. To describe the observed effect, we suggested a chemical scheme and biophysical mechanism considering a competition between Zeeman and Fermi interactions in the external magnetic field.

Alternating electric field stimulation: Phenotype analysis and osteoclast activity of differentiated RAW 264.7 macrophages on hydroxyapatite-coated Ti6Al4V surfaces and their crosstalk with MC3T3-E1 pre-osteoblasts

Biophysical stimuli can mimic endogenous electric potentials and currents in the natural bone to enhance tissue healing and reconstruction in diseased bone. However, little is known about the influence of electric fields on osteoclasts. Therefore, this study aimed to investigate the effects of alternating electric fields on osteoclast differentiation and activity. In this in vitro study, RAW 264.7 cells were seeded on Ti6Al4V substrates, as a loadbearing implant material modified with biomimetic calcium phosphate (BCP) and stimulated towards osteoclastic differentiation via growth factors. The effects of directly coupled alternating electric fields (0.7 Vrms, 20 Hz) on cell behavior were examined for up to 28 days. Alternating electric field simulation was performed using the finite element method. Changes in cell and substrate morphology were examined via light and fluorescence imaging. Cell viability was assessed via WST-8 assay. The effect of electrical stimulation (ES) on intercellular signaling and crosstalk was evaluated using indirect co-cultures with murine MC3T3-E1 pre-osteoblasts by qPCR. Morphological analysis proved the successful differentiation of macrophages into osteoclast-like cells for both electrically stimulated samples as well as unstimulated controls. ES promoted RAW 264.7 viability within the first seven days and induced a cellular response at gene expression levels. Gradually decreased expression rates of genes related to osteoclast differentiation and activity within 28 days could indicate a long-term inhibitory effect of ES on osteoclastogenesis and osteoclast activity while significantly upregulated carbonic anhydrase type 2 expressions could be a consequence of membrane depolarization to maintain intercellular pH levels. In this context, we were also able to demonstrate the degradation of the BCP surface by cellular influence. ES affected the crosstalk between osteoblast-, and osteoclast-like cells. Supernatants of electrically stimulated RAW 264.7 specimens led to decreased MC3T3-E1 viabilities and mineralization. While osteopontin expression in MC3T3-E1 cells was significantly decreased, markers of osteogenic differentiation showed higher expression rates. Underlying biophysical mechanisms in combination with biomaterials are part of ongoing research.

Scaling Limit of a Generalized Contact Process

We derive macroscopic equations for a generalized contact process that is inspired by a neuronal integrate and fire model on the lattice $$\mathbb {Z}^d$$ . The states at each lattice site can take values in $$0,\ldots ,k$$ . These can be interpreted as neuronal membrane potential, with the state k corresponding to a firing threshold. In the terminology of the contact processes, which we shall use in this paper, the state k corresponds to the individual being infectious (all other states are noninfectious). In order to reach the firing threshold, or to become infectious, the site must progress sequentially from 0 to k. The rate at which it climbs is determined by other neurons at state k, coupled to it through a Kac-type potential, of range $$\gamma ^{-1}$$ . The hydrodynamic equations are obtained in the limit $$\gamma \rightarrow 0$$ . Extensions of the microscopic model to include excitatory and inhibitory neuron types, as well as other biophysical mechanisms, are also considered.

Characterizing spatial, diurnal, and seasonal patterns of agricultural irrigation expansion-induced cooling in Northwest China from 2000 to 2020

In the last two decades, agricultural irrigation areas expanded rapidly in arid Northwest China (NWC, including North and South Xinjiang and Hexi Corridor) and altered local and regional climates. However, the increasing irrigation's climatic effects with underlying biophysical mechanisms have rarely been investigated. Here we characterized the impact patterns of irrigation expansion on land surface temperature (LST) in NWC from spatial, diurnal, and seasonal dimensions from 2000 to 2020; we then decomposed the LST changes related to multiple biophysical components using the energy balance equation and quantified the contributions of albedo and evapotranspiration (ET) to LST changes based on partial correlation and dominance analyses. We found the space-and-time method can better represent the cooling effects of long-term irrigation expansion than the space-for-time method, despite that they derived similar cooling trends. The cooling effects were most evident in South Xinjiang, followed by North Xinjiang and Hexi Corridor, and varied in different irrigation expansion sources. Specifically, more intensive cooling occurred in new irrigated areas from unused lands (-0.69 ± 0.02 K) than that from grasslands (-0.47 ± 0.05 K) and forests (-0.28 ± 0.04 K). The cooling effects were dominated by marked daytime cooling compared to negligible nighttime warming. Seasonally, the cooling effects were concentrated in the growing season (May to September), especially in July and August. LST changes related to latent heat and sensible heat fluxes significantly surpassed other biophysical components. The changes in ET and albedo jointly modulated LST variations and increased ET dominated the daytime cooling effect (r = 0.52, p < 0.001) with a relative importance of over 55%, especially in North Xinjiang. But the ET-dominated cooling would be dampened by enhanced precipitation, implying the non-trivial impact of background climate. This study can provide important references for evaluating the climatic effects caused by irrigation expansion in arid regions and for improving the climate models.

Immotile cilia mechanically sense the direction of fluid flow for left-right determination.

Immotile cilia at the ventral node of mouse embryos are required for sensing leftward fluid flow that breaks left-right symmetry of the body. However, the flow-sensing mechanism has long remained elusive. In this work, we show that immotile cilia at the node undergo asymmetric deformation along the dorsoventral axis in response to the flow. Application of mechanical stimuli to immotile cilia by optical tweezers induced calcium ion transients and degradation of Dand5 messenger RNA (mRNA) in the targeted cells. The Pkd2 channel protein was preferentially localized to the dorsal side of immotile cilia, and calcium ion transients were preferentially induced by mechanical stimuli directed toward the ventral side. Our results uncover the biophysical mechanism by which immotile cilia at the node sense the direction of fluid flow.

Robustness and Universality in Organelle Size Control.

One of the grand challenges in cellular biophysics is understanding the precision with which cells assemble and maintain subcellular structures. Organelle sizes, for example, must be flexible enough to allow cells to grow or shrink them as environments demand yet be maintained within homeostatic limits. Despite identification of molecular factors that regulate organelle sizes we lack insight into the quantitative principles underlying organelle size control. Here we show experimentally that cells can robustly control average fluctuations in organelle size. By demonstrating that organelle sizes obey a universal scaling relationship we predict theoretically, our framework suggests that organelles grow in random bursts from a limiting pool of building blocks. Burstlike growth provides a general biophysical mechanism by which cells can maintain on average reliable yet plastic organelle sizes.

Causes of widespread foliar damage from the June 2021 Pacific Northwest Heat Dome: more heat than drought.

This scientific commentary refers to ‘Conifer desiccation in the 2021 NW heatwave confirms the role of hydraulic damage’ by Klein et al. (doi: 10.1093/treephys/tpac007). Most of the Pacific Northwest (PNW, USA) and British Columbia experienced extraordinarily high air temperatures during an extreme heat wave event (‘Heat Dome’) in the late June of 2021 (Neal et al. 2022, Qian et al. 2022). In many locations, all-time record high air temperatures (Tair) exceeding 40–45 °C were observed during the Heat Dome. Within days of the event, widespread foliar damage was observed in many locations of this region along with some reports of tree mortality. As the frequency of coincident heat waves and drought has increased and is expected to continue to increase (Alizadeh et al. 2020), understanding the environmental drivers, biophysical and physiological mechanisms, and ecological consequences of heat damage incurred by forests is of broad relevance. Indeed, there is an increasing recognition that forest vulnerabilities to heat waves can lead to widespread growth reductions and even mortality (Breshears et al. 2021).

Ultrasound meets the cell membrane: for enhanced endocytosis and drug delivery.

Endocytosis plays a crucial role in drug delivery for precision therapy. As a non-invasive and spatiotemporal-controllable stimulus, ultrasound (US) has been utilized for improving drug delivery efficiency due to its ability to enhance cell membrane permeability. When US meets the cell membrane, the well-known cavitation effect generated by US can cause various biophysical effects, facilitating the delivery of various cargoes, especially nanocarriers. The comprehension of recent progress in the biophysical mechanism governing the interaction between ultrasound and cell membranes holds significant implications for the broader scientific community, particularly in drug delivery and nanomedicine. This review will summarize the latest research results on the biological effects and mechanisms of US-enhanced cellular endocytosis. Moreover, the latest achievements in US-related biomedical applications will be discussed. Finally, challenges and opportunities of US-enhanced endocytosis for biomedical applications will be provided.

Mechanics of morphogenesis in neural development: In vivo, in vitro, and in silico

Morphogenesis in the central nervous system has received intensive attention as elucidating fundamental mechanisms of morphogenesis will shed light on the physiology and pathophysiology of the developing central nervous system. Morphogenesis of the central nervous system is of a vast topic that includes important morphogenetic events such as neurulation and cortical folding. Here we review three types of methods used to improve our understanding of morphogenesis of the central nervous system: in vivo experiments, organoids (in vivo), and computational models (in silico). The in vivo experiments are used to explore cellular- and tissue-level mechanics and interpret them on the roles of neurulation morphogenesis. Recent advances in human brain organoids have provided new opportunities to study morphogenesis and neurogenesis to compensate for the limitations of in vivo experiments, as organoid models are able to recapitulate some critical neural morphogenetic processes during early human brain development. Due to the complexity and costs of in vivo and in vitro studies, a variety of computational models have been developed and used to explain the formation and morphogenesis of brain structures. We review and discuss the advantages and disadvantages of these methods and their usage in the studies on morphogenesis of the central nervous system. Notably, none of these methods alone is sufficient to unveil the biophysical mechanisms of morphogenesis, thus calling for the interdisciplinary approaches using a combination of these methods in order to test hypotheses and generate new insights on both normal and abnormal development of the central nervous system.Statement of Significance: The understanding of the central nervous system is essential to provide supports to treat and prevent neurological conditions. Mechanisms of morphogenesis therein can be elucidated from multiple unique perspectives via multidisciplinary approaches. The in vivo experiments, organoid models, and computational modeling are three most effective ways to study brain morphogenesis. In vivo experiments on live animals provide important evidence for studying the roles of mechanical forces in morphogenetic events. The human brain organoid models can greatly assist to study early human brain development and closely simulate the in-vivo counterpart. Moreover, computational models based on physical principles can test hypotheses in conjunctions with experiments to facilitate understanding of the spatial and temporal evolution of these complex structures. The combination of these approaches can complement each other to unveil fundamental mechanisms of the neural morphogenesis and shed light on the development, prevention, and treatment of neurological disorders.

A hippocampal-entorhinal cortex neuronal network for dynamical mechanisms of epileptic seizure.

Temporal lobe epilepsy (TLE) is thought to be associated with neuronal hyperexcitability in the hippocampal-entorhinal cortical (EC) circuit. Due to the complexity of the hippocampal-EC network connections, the biophysical mechanisms of the different circuits in epilepsy generation and propagation are still not fully established. In this work, we propose a hippocampal-EC neuronal network model to explore the mechanism of epileptic generation. We demonstrate that enhanced excitability of pyramidal neurons in cornu ammonis 3 (CA3) can drive hippocampal-EC to produce a transition from background to seizure state and cause exaggerated phase-amplitude coupling (PAC) phenomenon of theta modulated high-frequency oscillations (HFO) in CA3, cornu ammonis 1 (CA1), dentate gyrus, and EC. Interestingly, PAC strength indirectly responds to the degree of CA3 pyramidal (PY) neuron hyperexcitability, suggesting that PAC can be used as a potential marker of seizures. Furthermore, we find that enhanced synaptic connectivity of mossy cells to granule cells and CA3 PY neurons drives the system to produce epileptic discharges. These two channels may play a key role in mossy fiber sprouting. In particular, the PAC phenomenon of delta-modulated HFO and theta-modulated HFO can be generated according to the different degrees of moss fiber sprouting. Finally, the results suggest that hyperexcitability of stellate cells in EC can lead to seizures, which supports the argument that EC can act as an independent source of seizures. Overall, these results highlight the key role of different circuits in seizures, providing a theoretical basis and new insights into the generation and propagation of TLE.

Micromechanical remodeling of the extracellular matrix by invading tumors: anisotropy and heterogeneity.

Altered tissue mechanics is an important signature of invasive solid tumors. While the phenomena have been extensively studied by measuring the bulk rheology of the extracellular matrix (ECM) surrounding tumors, micromechanical remodeling at the cellular scale remains poorly understood. By combining holographic optical tweezers and confocal microscopy on in vitro tumor models, we show that the micromechanics of collagen ECM surrounding an invading tumor demonstrate directional anisotropy, spatial heterogeneity and significant variations in time as tumors invade. To test the cellular mechanisms of ECM micromechanical remodeling, we construct a simple computational model and verify its predictions with experiments. We find that collective force generation of a tumor stiffens the ECM and leads to anisotropic local mechanics such that the extension direction is more rigid than the compression direction. ECM degradation by cell-secreted matrix metalloproteinase softens the ECM, and active traction forces from individual disseminated cells re-stiffen the matrix. Together, these results identify plausible biophysical mechanisms responsible for the remodeled ECM micromechanics surrounding an invading tumor.

Mapping of structural arrangement of cells and collective calcium transients: an integrated framework combining live cell imaging using confocal microscopy and UMAP-assisted HDBSCAN-based approach.

Live cell calcium (Ca2+) imaging is one of the important tools to record cellular activity during in vitro and in vivo preclinical studies. Specially, high-resolution microscopy can provide valuable dynamic information at the single cell level. One of the major challenges in the implementation of such imaging schemes is to extract quantitative information in the presence of significant heterogeneity in Ca2+ responses attained due to variation in structural arrangement and drug distribution. To fill this gap, we propose time-lapse imaging using spinning disk confocal microscopy and machine learning-enabled framework for automated grouping of Ca2+ spiking patterns. Time series analysis is performed to correlate the drug induced cellular responses to self-assembly pattern present in multicellular systems. The framework is designed to reduce the large-scale dynamic responses using uniform manifold approximation and projection (UMAP). In particular, we propose the suitability of hierarchical DBSCAN (HDBSCAN) in view of reduced number of hyperparameters. We find UMAP-assisted HDBSCAN outperforms existing approaches in terms of clustering accuracy in segregation of Ca2+ spiking patterns. One of the novelties includes the application of non-linear dimension reduction in segregation of the Ca2+ transients with statistical similarity. The proposed pipeline for automation was also proved to be a reproducible and fast method with minimal user input. The algorithm was used to quantify the effect of cellular arrangement and stimulus level on collective Ca2+ responses induced by GPCR targeting drug. The analysis revealed a significant increase in subpopulation containing sustained oscillation corresponding to higher packing density. In contrast to traditional measurement of rise time and decay ratio from Ca2+ transients, the proposed pipeline was used to classify the complex patterns with longer duration and cluster-wise model fitting. The two-step process has a potential implication in deciphering biophysical mechanisms underlying the Ca2+ oscillations in context of structural arrangement between cells.

Model of inverse bleb growth explains giant vacuole dynamics during cell mechanoadaptation.

Cells can withstand hostile environmental conditions manifest as large mechanical forces such as pressure gradients and/or shear stresses by dynamically changing their shape. Such conditions are realized in the Schlemm's canal of the eye where endothelial cells that cover the inner vessel wall are subjected to the hydrodynamic pressure gradients exerted by the aqueous humor outflow. These cells form fluid-filled dynamic outpouchings of their basal membrane called giant vacuoles. The inverses of giant vacuoles are reminiscent of cellular blebs, extracellular cytoplasmic protrusions triggered by local temporary disruption of the contractile actomyosin cortex. Inverse blebbing has also been first observed experimentally during sprouting angiogenesis, but its underlying physical mechanisms are poorly understood. Here, we hypothesize that giant vacuole formation can be described as inverse blebbing and formulate a biophysical model of this process. Our model elucidates how cell membrane mechanical properties affect the morphology and dynamics of giant vacuoles and predicts coarsening akin to Ostwald ripening between multiple invaginating vacuoles. Our results are in qualitative agreement with observations from the formation of giant vacuoles during perfusion experiments. Our model not only elucidates the biophysical mechanisms driving inverse blebbing and giant vacuole dynamics, but also identifies universal features of the cellular response to pressure loads that are relevant to many experimental contexts.

In vitro effects of eslicarbazepine (S-licarbazepine) as a potential precision therapy on SCN8A variants causing neuropsychiatric disorders.

Variants in SCN8A, the NaV 1.6 channel's coding gene, are characterized by a variety of symptoms, including intractable epileptic seizures, psychomotor delay, progressive cognitive decline, autistic features, ataxia or dystonia. Standard anticonvulsant treatment has a limited impact on the course of disease. We investigated the therapeutic potential of eslicarbazepine (S-licarbazepine; S-lic), an enhancer of slow inactivation of voltage gated sodium channels, on two variants with biophysical and neuronal gain-of-function (G1475R and M1760I) and one variant with biophysical gain-of-function but neuronal loss-of-function (A1622D) in neuroblastoma cells and in murine primary hippocampal neuron cultures. These three variants cover the broad spectrum of NaV 1.6-associated disease and are linked to representative phenotypes of mild to moderate epilepsy (G1475R), developmental and epileptic encephalopathy (M1760I) and intellectual disability without epilepsy (A1622D). Similar to known effects on NaV 1.6 wildtype channels, S-lic predominantly enhances slow inactivation on all tested variants, irrespective of their particular biophysical mechanisms. Beyond that, S-lic exhibits variant-specific effects including a partial reversal of pathologically slowed fast inactivation dynamics (A1622D and M1760I) and a trend to reduce enhanced persistent Na+ current by A1622D variant channels. Furthermore, our data in primary transfected neurons reveal that not only variant-associated hyperexcitability (M1760I and G1475R) but also hypoexcitability (A1622D) can be modulated by S-lic. S-lic hasnot only substance-specific effects but also variant-specific effects. Personalized treatment regimens optimized to achieve such variant-specific pharmacological modulation may help to reduce adverse side effects and improve the overall therapeutic outcome of SCN8A-related disease.

Electron-donor and regulatory effects of superoxide anion radicals on the processes of osteogenesis and bone remodeling: literature review

The analysis of scientific publications on the regulatory effect of peroxide anion radicals and electronic activation of the body on the function of osteogenesis and associated systems of the body is presented according to the following information sources: Scopus database, MEDLINE, Web of Science, eLibrary.ru, Google academy for the availability of peer-reviewed original and review publications on the key words: osteogenesis, musculoskeletal system, reoxygenation, hormonal regulators, electron-donor activity, associated water phase, rehabilitation, on the basis of which search phrases on the research topic were formed. Based on a number of evidencebased scientific studies on the regulatory effect of peroxide anion radicals and electronic activation on biological processes (changes in the functional state of the liver, hematological parameters, macro- and microelement composition of liquid media and animal organs, the course of reparative processes in damaged tissues), a biophysical mechanism of systemic homeostatic action of oxygen anion radicals is proposed. This mechanism consists in antihypoxic and detoxifying action during reoxygenation of ischemic tissues, in increasing proliferative activity and shifting osteogenesis regulators (sRANKL-OPG system) towards osteoprotegerin. At the same time, the processes of binding of intracellular free calcium and trace elements in osteoblasts, activation of the macrophage reaction, neoangiogenesis and restoration of myeloid tissue in the area of bone breakdown occur. It is shown that the use of micellar mechanoactivated calcium carbonate as a source of formation of peroxide anion radicals in an aqueous medium leads to a decrease in the redox state and stabilization of cell pH, activation of mitochondrial activity accompanied by intensification of metabolism, including the exchange of micro- and macroelements, improvement of the functions of the antioxidant defense system and nonspecific immunity of the body, stabilization of physiological and biochemical parameters and the functional state of internal organs.