Principal Function Research Articles

Impact of a cognitive stimulation program on the reading comprehension of children in primary education.

At present, numerous studies can be found in which influences and relationships between the principal executive functions, reading comprehension, and academic performance associated with reading are reported. However, there is still a lack of convergence regarding the impact of computerized cognitive training on children's executive development and its transfer in academic reading performance and comprehension of written texts. This study analyzes the effect of implementing a cognitive stimulation program on the performance of reading comprehension and academic performance in the subject of Spanish Language and Literature. To this end, a total sample of 196 children from 23 educational centers received the cognitive intervention for 8 weeks, with three weekly sessions of between 15 and 20 min each occurring on non-consecutive days. Pre-test and post-test measurements were collected and analyzed. The results demonstrate a significant increase in the reading comprehension scores. In addition, a significant impact of the training on the participants' academic performance in the subject Spanish Language and Literature was found. These results highlight the usefulness of computerized cognitive stimulation programs for reading comprehension enhancement.

Text-Mining to Identify Gene Sets Involved in Biocorrosion by Sulfate-Reducing Bacteria: A Semi-Automated Workflow.

A significant amount of literature is available on biocorrosion, which makes manual extraction of crucial information such as genes and proteins a laborious task. Despite the fast growth of biology related corrosion studies, there is a limited number of gene collections relating to the corrosion process (biocorrosion). Text mining offers a potential solution by automatically extracting the essential information from unstructured text. We present a text mining workflow that extracts biocorrosion associated genes/proteins in sulfate-reducing bacteria (SRB) from literature databases (e.g., PubMed and PMC). This semi-automatic workflow is built with the Named Entity Recognition (NER) method and Convolutional Neural Network (CNN) model. With PubMed and PMCID as inputs, the workflow identified 227 genes belonging to several Desulfovibrio species. To validate their functions, Gene Ontology (GO) enrichment and biological network analysis was performed using UniprotKB and STRING-DB, respectively. The GO analysis showed that metal ion binding, sulfur binding, and electron transport were among the principal molecular functions. Furthermore, the biological network analysis generated three interlinked clusters containing genes involved in metal ion binding, cellular respiration, and electron transfer, which suggests the involvement of the extracted gene set in biocorrosion. Finally, the dataset was validated through manual curation, yielding a similar set of genes as our workflow; among these, hysB and hydA, and sat and dsrB were identified as the metal ion binding and sulfur metabolism genes, respectively. The identified genes were mapped with the pangenome of 63 SRB genomes that yielded the distribution of these genes across 63 SRB based on the amino acid sequence similarity and were further categorized as core and accessory gene families. SRB's role in biocorrosion involves the transfer of electrons from the metal surface via a hydrogen medium to the sulfate reduction pathway. Therefore, genes encoding hydrogenases and cytochromes might be participating in removing hydrogen from the metals through electron transfer. Moreover, the production of corrosive sulfide from the sulfur metabolism indirectly contributes to the localized pitting of the metals. After the corroboration of text mining results with SRB biocorrosion mechanisms, we suggest that the text mining framework could be utilized for genes/proteins extraction and significantly reduce the manual curation time.

Development potential of the school management team in modern context

The article considers the established in official documents and recommendations governing educational policy, as well as the distribution of functional responsibilities and tasks of the management of these educational organizations in the practice of schools in Russia and a number of foreign countries. It has been revealed that the functional composition of the requirements for the work of school management in different countries largely coincides, and as perspective tasks aimed at the development of schools, there are tasks of quality management of learning results. However, Russian school administrators underestimate the role and possibilities of creating in-school systems of distributed leadership and responsibility for the work of the school to solve these tasks. The mechanisms of creation of such management teams in our country are in the stage of formation, although these tasks are set in the leading documents defining the directions of development of the education system in Russia, in the professional standard «Head of educational organization». Possible solutions should be sought in redistribution of the functions of deputy school principals in accordance with the tasks of the school, in the distribution of responsibilities among leading specialists-leaders, in the search for a new functional public school councils, school board of trustees. Another important direction in the search for mechanisms to solve the problem of training school management teams to manage the quality of learning results is the improvement of their competences in the field of ownership of the results of modern research and development in the field of pedagogy, development of curricula, evaluation and accountability systems, in the field of national policy in general, and education policy in particular, in the field of motivating educational participants to achieve a common goal. The development of the capacity of the school management team is also facilitated by targeted leadership development of each of its members.

The role of school principals in addressing the educational loss in English Language resulting from COVID-19 pandemic from teachers’ perspective

Introduction. Disruptions to the educational system and ESL programmes have been particularly severe as a result of the COVID-19 pandemic. Significant losses in learning outcomes, have resulted from the forced shift from traditional to remote learning modes, exposing weaknesses and large holes in the educational framework. These disruptions in the classroom have highlighted the critical need for thorough research into and comprehension of the new educational landscapes, which are characterised by decreased language exposure, fewer practise opportunities, and lessened interactive learning. To create innovative and adaptable educational frameworks that can lessen the effects of global disruptions on language acquisition and academic success, this knowledge is essential. Aim. The study aimed to identify the role of public-school principals in addressing the effects of educational loss resulting from the COVID-19 pandemic from the teachers’ perspective, and to reveal the significance of differences in estimates according to the classification variables of the research. Study participants and methods. The researchers used the descriptive method in its analytical and constructive style, and they used the focus group method (focused), and the questionnaire was used and applied to a random sample of (153) English teachers chosen from 30 public schools in the capital Amman. The results. The study showed that the total score of the overall relative weight of the four domains (administrative role, technical, supervisory, and societal role) was determined to be 70.24%, with the relative weights of the administrative role being 68.86%, the technical role being 68.20%, the supervisory role being 73.46%, and the societal role being 69.58%. From the teachers’ perspective, the principals' high levels of involvement in all of these areas are indicative of the significance principals place on their supervisory role in the regular course of school life. High levels of implementation can be seen in the relative weights given to certain sections within these domains, such as the preparation of school schedules and the listing of abilities lost among children as a result of dropping out of school (71.36% and 71.50%, respectively). The "T" and "Sig" values in all sections of the survey show that there are no statistically significant differences in school principals' perspectives on preventing and reversing student learning loss on the basis of gender or educational background; similar patterns were identified across roles, highlighting consistency of approach regardless of gender or academic credentials; for example, the Significance value for the teachers perspectives about the administrative role of male (Mean=3.537, N=83) principals was 0.142 compared to female principals (Mean=3.332, N=70), which means male principals act their administrative role more effective than female principals. Conclusions. The spread of COVID-19 has clearly altered the status quo of education, especially for ESL classes. As a result, the transition to online education has highlighted critical flaws in the traditional model. This study sought to better understand the critical function of public school principals in preventing educational losses from the perspective of English instructors in Amman. On average, the data showed that principals played a significant influence in preventing these dropouts throughout the administrative, technical, supervisory, and sociological spheres, with the latter function appearing as the most important. Principals' approaches were constant across gender and educational boundaries. There was a small but noticeable disparity between the administrative efficacy of male and female principals. Given these findings, it's evident that schools need to change their teaching methods to better prepare students for the future. This is especially true when it comes to English Language Acquisition (ELA), where students need to be prepared for both current and future issues.

Вasic methods of strategic management of commodity flows in the domestic market

The internal market as a factor in the efficiency of reproduction processes is an effective engine for other branches of the national economy. With the help of the mechanism of supply and demand coordination, the market provides effective business relations. However, today the functions of market self-regulation are necessarily combined with the functions of the state regulation mechanism. Considering today’s problems, the regulation of the consumer market should be carried out according to a three-level system: at the central level, at the level of regions, and at the level of local governments. At each level, appropriate structural subdivisions with their specific tasks and functions should be created. The main task of society in regulating the consumer goods market is to optimize the circulation of goods. It is obvious that the lack of an effective mechanism is a serious destructive factor in the development of the sphere of consumer circulation in the modern economy. At the present stage, strategic planning is one of the principal management functions and in no way can be overlooked by either practitioners or scientists. From various aspects of planning (operational, current, prospective), the majority of experts now pay maximum attention to the prospective one, which is based on models of the enterprise development strategy in the conditions of the changing external and internal environment. The strategy is implemented in the context of the organization’s mission, and its fundamental objective is to ensure that the mission is connected with the organisation’s main goals in the changing economic environment. A person is always a potential creator of the necessary conditions for the evolution of society, and such action is determined through the mechanisms of consumption. Therefore, consumption should be considered as a process of satisfying needs with material and spiritual goods, which generates motivation to work, involves the use of the social product of certain needs, and is the final sign of social reproduction. The article examines the theoretical foundations of methods of strategic management of commodity flows at the micro level. The tasks of forming an organizational and economic mechanism for managing commodity flows (macro level), which provides the optimal variant for the movement of goods are defined. A mathematical description of the general equilibrium is presented. The basic methods of managing intra-production commodity flows at the micro level are formulated. The authoritarian solution of the rationing mechanism is substantiated, and the difficulties of implementing the rationing mechanism are outlined.

A Fast Piecewise-Defined Neural Network Method to Retrieve Temperature and Humidity Profile for the Vertical Atmospheric Sounding System of FengYun-3E Satellite

A fast piecewise-defined neural network (PDNN) method is presented to produce accurate atmospheric temperature and humidity profiles from satellite hyperspectral infrared and microwave observations in all-sky conditions. The PDNN method relies on a novel classification approach and a principal component-based neural network function to better capture the nonlinear relationship between the spectral radiances and atmospheric state vectors. The algorithm was designed to only rely on satellite measurements. Large datasets were used for network training to make the retrieval robust to random errors in the reference data. For each retrieved profile, an effective quality indicator was obtained by training against the absolute value of the retrieval error. In addition, a reliable rain cloud flag was generated based on the scattering difference of cloud particles between the 50 and 118 GHz channels. Besides the independent reanalysis field data, the algorithm’s performance was also evaluated using radiosonde measurements. Preliminary validation shows that the best temperature retrieval occurred in the mid-troposphere (around 1.0 K). Depending on the reference data, errors in the boundary layer typically ranged from 1.8 K to 2.5 K. For water vapor, the retrieval error was less than 22% in the low-troposphere and less than 35% in the mid-and upper-troposphere when validated against the reanalysis field. The humidity error was approximately 10% lower when compared to radiosondes. The PDNN is used operationally to produce atmospheric temperature and moisture soundings from the Vertical Atmospheric Sounding System of the FengYun-3E satellite, an early-morning-orbit meteorological satellite launched in 2021.

High Throughput Sequencing Analysis of Exosomal miRNA Expressions in Early-Onset Preeclampsia Patients.

The goal of this study was to screen for differentially expressed exosomal miRNAs in peripheral blood samples of early-onset preeclampsia and normal pregnant patients using high-throughput sequencing methods and explore their effects on the pathogenesis of preeclampsia. Peripheral blood samples from 5 patients with early-onset preeclampsia and 5 normal pregnant women (control group) were enrolled. Then, exosomes were extracted from each sample, and the procedure was replicated three times. An Illumina HiSeq4000 sequencing platform was used to analyze exosomal miRNAs in all samples before comparison. The target genes and signaling pathway predictions and the biological function enrichments of significant and differentially expressed miRNAs were assessed using Miranda and Starbase software, as well as GO and KEGG databases. Compared with the control, patients in the early-onset preeclampsia group had 65 significantly and differentially expressed exosomal miRNAs in their peripheral blood samples. The results have shown that of the 65 differentially expressed miRNAs, 17, including has-miR-6855, has-miR-7151, and has-miR-6777, were up-regulated, and 48, including has-miR-1247, has-miR-29B2, and has-miR-941, were down-regulated (p < 0.05). The Miranda and TargetScanS algorithms predicted a total of 2,231 target genes from the differentially expressed miRNAs. The Go and KEGG analyses showed that the principal biological function of these target genes was the regulation of Ras protein signal transduction, histone modification, GTPase-mediated signal transduction, and transforming growth factor (TGF)-β. Additionally, the results also showed that the major pathways involved in the regulation of these functions were the PI3K Akt, MAPK, tumor necrosis factor, and EGFR tyrosine kinase inhibition signaling pathways. There are significant differences in the expression profiles of exosomal miRNAs between early-onset preeclampsia patients and normal pregnant women. These differentially expressed miRNAs may not only play an important regulatory role in the occurrence of early-onset preeclampsia but also participate in its pathophysiological process through genetic regulation of a variety of biological functions and signal pathways.

Experimental study on mechanical properties of Textile Reinforced Concrete (TRC)

Textile-reinforced concrete (TRC) is a variant of reinforced concrete in which textiles are used in place of steel reinforcing bars. Reinforcing the concrete with steel means increasing its tensile strength, but steel also corrodes and wears out over time. The TRC is a novel idea that has the potential to overcome these drawbacks. TRC is a composite reinforcing material that is made from cement and has the benefits of being resistant to corrosion, having a high bearing capacity, and performing well in terms of its fracture limit. The principal function of TRC in buildings has been as reinforcement and as a means of enhancing the ductility and performance of concrete. This experimental work utilizes a 145 gsm (grams squared per meter) alkali-resistant (AR) glass fiber textile mesh. Specimens were cast with and without fibers, and the number of layers was increased from 1 to 3 at 25 mm spacing. In this experimental work, the mechanical behavior of TRC was investigated by conducting tests on its impact, compressive, and flexural strengths. From these results, the TRC specimen exhibits more flexibility than the control specimen. The TRC specimen bends under force and returns to a new position when the load is removed, indicating a good energy absorption capability. As a result, it infers that the specimen with fibrehave the capacity to withstand a higher maximum load than conventional specimens. TRC has a greater fracture control system compared to conventional steel-reinforced concrete.

FAT/CD36 Participation in Human Skeletal Muscle Lipid Metabolism: A Systematic Review

Fatty acid translocase/cluster of differentiation 36 (FAT/CD36) is a multifunctional membrane protein activated by a high-fat diet, physical exercise, fatty acids (FAs), leptin, and insulin. The principal function of FAT/CD36 is to facilitate the transport of long-chain fatty acids through cell membranes such as myocytes, adipocytes, heart, and liver. Under high-energy expenditure, the different isoforms of FAT/CD36 in the plasma membrane and mitochondria bind to the mobilization and oxidation of FAs. Furthermore, FAT/CD36 is released in its soluble form and becomes a marker of metabolic dysfunction. Studies with healthy animals and humans show that physical exercise and a high-lipid diet increase FAT/CD36 expression and caloric expenditure. However, several aspects such as obesity, diabetes, Single Nucleotide polymorphisms (SNPs), and oxidative stress affect the normal FAs metabolism and function of FAT/CD36, inducing metabolic disease. Through a comprehensive systematic review of primary studies, this work aimed to document molecular mechanisms related to FAT/CD36 in FAs oxidation and trafficking in skeletal muscle under basal conditions, physical exercise, and diet in healthy individuals.

ISOLATION AND CHARACTERIZATION OF CELLULOSE DEGRADING MICROORGANISMS GENERATING ELECTRICITY USING MICROBIAL FUEL CELL

Global warming and the accumulation of organic waste constitute a serious environmental problem. Therefore, microbial fuel cells (MFC) are an eco-friendly device that have significant capability for the production of electricity using biodegradable waste as fuel. Microorganisms used as catalysts in the anode compartment, execute a principal function in operating MFCs. The present study was conducted to isolate and to screen potential bioelectricity generating microorganisms from dumpsite soil samples and also to construct a domestic dual-chambered microbial fuel cell (MFC). Streptomyces fimicarius was found to be the best isolate for the degradation of cellulose and the production of bioelectricity. The bacterial isolate was identified based on morphological characteristics, biochemical characteristics and molecular identification using 16S rRNA. Double-chambered MFC was constructed by using two polypropylene plastic containers of 1.4 L volume each. The two chambers were joined by using an agar salt bridge and carbon rods were utilized as electrodes. The generation of electricity by the isolate was compared using glucose and cellulose as sole carbon source in a minimal medium. The maximum voltage was found to be 322 mV in the presence of cellulose used as substrate after 5 days of incubation at room temperature and last for 10 days.

An Overview about the Relationship between Cystatin C and Inflammatory Diseases

Cystatin C (Cys-C) is a protease inhibitor that can be produced by nuclear cells in the human body. Its principal function is to inhibit the activity of various cysteine proteases in vivo. In addition, Cys-C also plays an essential role in regulating antigen presentation, extracellular matrix degradation, and the balance of protein production and decomposition in living cells. Cys-C is involved in the pathophysiological processes of chronic inflammatory diseases, including cardiovascular, cerebrovascular, and respiratory diseases. This article reviews the effects of Cys-C on chronic inflammatory diseases and its therapeutic prospects.

The management and governance conundrum in South African public schools: principals’ perspectives

The introduction of school governing bodies (hereinafter SGBs) changed the roles and functions of principals dramatically when this new approach to school governance and professional management (referred to as a participatory decision-making approach) was activated when the South African Schools Act 84 of 1996 (hereinafter SASA) was implemented in January 1997. Consequently, the principal is no longer the only decision-maker in the school. The principal as the protagonist in school management and governance (implementing SGB policy) is the role-player most affected by the introduction of the participatory decision-making approach. In this article, we discuss principals’ perspectives regarding the shared participatory decision-making approach and the effects thereof on the relationship between the principal and the SGB. In this regard, it is important to note that the perceptions the two parties have of each other are established by the SGB’s encroachment on the professional management functions of the principal and vice versa. The research findings concluded that the relationship between the principal and the SGB is often a relationship characterised by tension, no trust and irrational actions by the SGB. The relationship is further influenced by the functionality or lack of functionality of SGBs as well as prevailing socio-economic conditions and SGB members’ levels of literacy. On the other hand, principals who do not adapt to participatory decision-making, and who still implement an assertive autocratic management approach, also contribute to a turbulent relationship.

The Impact of the Swedish National Principal Training Programme on Principals’ Leadership and the Structuration Process of School Organisations

Principals have an important function in schools’ ability to create high-quality learning and teaching. As the expectations placed on principals are high, large resources are invested in school leadership training, thus necessitating research on the impact of such initiatives. In this article, we report on a longitudinal research study on the training programme for principals in Sweden. The aim was to examine the programme’s impacts on the principals’ leadership and school organisations. We did this by interviewing principals, teachers and students at four schools during the principals’ participation in the programme. Giddens’s theory of structuration was used to analyse the study. The results showed that leadership needs to be foregrounded throughout the training and that awareness of the function of principals in leading schools’ structuration processes (i.e., their creation of meaning making) should be clarified.

Analytical ray tracing based on Hamilton principal function and conjugate variable pairs.

A transformation method based on optical Hamilton equations is proposed for 3D ray tracing in axially inhomogeneous gradient-index (GRIN) media with cylindrical symmetry. For a given GRIN field, the optical conjugate variable pairs of physical space can be transformed into a virtual space by applying canonical transformation. The virtual trace can be simply solved as a uniform expression regardless of what the GRIN field is, and one can inversely transform it into the physical space. The transformation is intimately related to a Hamilton principal function, called the S function, which simultaneously gives the real ray trace and its conjugate. The "conjugate trace" displays the direction cosines of the ray trace and thus shows the information about propagation direction at every point, and it can be independently derived from the S function without knowing the real trace. In addition, as two special dimension-reduction cases, the S function is also applicable for 2D structures with only axial inhomogeneity or cylindrical symmetry.

Machine Learning Based Signaling DDoS Detection System for 5G Stand Alone Core Network

Research to deal with distributed denial of service (DDoS) attacks was kicked off from long ago and has seen technological advancement along with an extensive 5G footprint. Prior studies, and still newer ones, in the realm of DDoS attacks in the 5G environment appear to be focused primarily on radio access network (RAN) and voice service network, meaning that there is no attempt to mitigate DDoS attacks targeted on core networks (CN) by applying artificial intelligence (AI) in modeling. In particular, such components of a CN as the Access and Mobility Management Function (AMF), Session Management Function (SMF), and User Plane Function (UPF), all being principal functions enabled to provide 5G services as base stations do, provide expansive connectivity with geographically very large area coverage that cannot be matched by the base stations. Moreover, to complete re-registration for one UE, required messages in protocols Packet Forwarding Control Protocol (PFCP) and HTTP/2 are approximately 40 in number. This implies that a DDoS attack targeting the CN has, once accomplished, a greater than expected impact, when compared to DDoS attacks targeting the RAN. Therefore, security mechanisms for the CN must be put into practice. This research proposes a method, along with a threat detection system, to mitigate signaling DDoS attacks targeted on 5G SA (standalone) CNs. It is verified that the use of fundamental ML classifiers together with preprocessing with entropy-based analysis (EBA) and statistics-based analysis (SBA) enables us to proactively react against signaling DDoS attacks. Additionally, the evaluation results manifest that the random forest achieves the best detection performance, with an average accuracy of 98.7%.

The contribution of numerical models to Lamb wave driven NDT processes – part I: model building

Components made of fibre-reinforced polymers (FRP) may suffer from various types of damages, such as cracks or delamination. In order to monitor the structures’ material condition, non destructive testing (NDT) methods have emerged – among them, the use of ultrasonic waves. Inter alia, research focused on Lamb waves (LW), which offer promising conditions for NDT processes. However, prior implementation in a specific production environment, practitioners are faced with many open questions such as excitation frequencies to be used or which mode to select for defect identification. Therefore, the study aimed at demonstrating how a finite element analysis (FEA) can assist the experimental design of an LW driven NDT process. For that, a numerical model was developed, capable of computing LW propagations in an exemplary component: Stringer-stiffened C-FRP panels. The study was divided into two parts: In this part, all information regarding the model building is presented and principal functionality demonstrated. In the second part, the FEA is validated and then used to perform parameter studies, highlighting important conditions for practical application. The results of the present paper showed that stiffeners provoke varying interactions with LW modes – effects that increase wave field complexity but do not limit defect identification within or behind the stringer.

Seasonal characterization of the prokaryotic microbiota of full-scale anaerobic UASB reactors treating domestic sewage in southern Brazil.

Upflow Anaerobic Sludge Blanket (UASB) reactors are alternatives in the anaerobic treatment of sanitary sewage in different parts of the world; however, in temperate environments, they are subject to strong seasonal influence. Understanding the dynamics of the microbial community in these systems is essential to propose operational alternatives, improve projects and increase the quality of treated effluents. In this study, for one year, high-performance sequencing, associated with bioinformatics tools for taxonomic annotation and functional prediction was used to characterize the microbial community present in the sludge of biodigesters on full-scale, treating domestic sewage at ambient temperature. Among the most representative phyla stood out Desulfobacterota (20.21-28.64%), Proteobacteria (7.48-24.90%), Bacteroidota (10.05-18.37%), Caldisericota (9.49-17.20%), and Halobacterota (3.23-6.55%). By performing a Canonical Correspondence Analysis (CCA), Methanolinea was correlated to the efficiency in removing Chemical Oxygen Demand (COD), Bacteroidetes_VadinHA17 to the production of volatile fatty acids (VFAs), and CI75cm.2.12 at temperature. On the other hand, Desulfovibrio, Spirochaetaceae_uncultured, Methanosaeta, Lentimicrobiaceae_unclassified, and ADurb.Bin063-1 were relevant in shaping the microbial community in a co-occurrence network. Diversity analyses showed greater richness and evenness for the colder seasons, possibly, due to the lesser influence of dominant taxa. Among the principal metabolic functions associated with the community, the metabolism of proteins and amino acids stood out (7.74-8.00%), and the genes related to the synthesis of VFAs presented higher relative abundance for the autumn and winter. Despite the differences in diversity and taxonomic composition, no significant changes were observed in the efficiency of the biodigesters.

The Quantum Hamilton–Jacobi Equation and the Link Between Classical and Quantum Mechanics

We study how the classical Hamilton's principal and characteristic functions are generated from the solutions of the quantum Hamilton–Jacobi equation. While in the classically forbidden regions these quantum quantities directly tend to the classical ones, this is not the case in the allowed regions. There, the limit is reached only if the quantum fluctuations are eliminated by means of coarse-graining averages. Analogously, the classical Hamilton–Jacobi scheme bringing to the motion's equations arises from a similar formal quantum procedure.Quanta 2022; 11: 42–52.

A Wheeler–DeWitt Equation with Time

The equation for canonical gravity produced by Wheeler and DeWitt in the late 1960s still presents difficulties both in terms of its mathematical solution and its physical interpretation. One of these issues is, notoriously, the absence of an explicit time. In this short note, we suggest one simple and straightforward way to avoid this occurrence. We go back to the classical equation that inspired Wheeler and DeWitt (namely, the Hamilton–Jacobi–Einstein equation) and make explicit, before quantization, the presence of a known, classically meaningful notion of time. We do this by allowing Hamilton’s principal function to be explicitly dependent on this time locally. This choice results in a Wheeler–DeWitt equation with time. A working solution for the de Sitter minisuperspace is shown.

After the Storm: Regeneration, Repair, and Reestablishment of Homeostasis Between the Alveolar Epithelium and Innate Immune System Following Viral Lung Injury.

The mammalian lung has an enormous environmental-epithelial interface that is optimized to accomplish the principal function of the respiratory system, gas exchange. One consequence of evolving such a large surface area is that the lung epithelium is continuously exposed to toxins, irritants, and pathogens. Maintaining homeostasis in this environment requires a delicate balance of cellular signaling between the epithelium and innate immune system. Following injury, the epithelium can be either fully regenerated in form and function or repaired by forming dysplastic scar tissue. In this review, we describe the major mechanisms of damage, regeneration, and repair within the alveolar niche where gas exchange occurs. With a focus on viral infection, we summarize recent work that has established how epithelial proliferation is arrested during infection and how the innate immune system guides its reconstitution during recovery. The consequences of these processes going awry are also considered, with an emphasis on how this will impact postpandemic pulmonary biology and medicine.