Within food purchase habits, the number of respondents who declared choosing a low-fat lunch away from home decreased, often buying pastries or cakes decreased, and buying a low-fat crisps brand increased (p < 0.05). Within food preparation habits, the number of respondents who declared trying to keep overall fat intake down increased, trying to keep overall sugar intake down increased, eating at least one serving of vegetables or salad with evening meal increased, and usually including some chocolate and/or biscuits in a packed lunch decreased (p < 0.05). Within food consumption habits, the number of respondents who declared making sure that they eat at least one serving of fruit a day increased, eating at least three servings of fruit most days increased, making sure that they eat at least one serving of vegetables or salad a day increased, trying to ensure that they eat plenty of fruit and vegetables increased, often choosing a fruit when they have a snack between meals increased, eating at least three servings of fruit most days increased, and generally trying to have a healthy diet increased (p < 0.05). It was concluded that in the period of the COVID-19 pandemic and resultant remote education, adolescents in Poland presented different food habits than before, while the majority of changes were positive. The positive food purchase, preparation, and consumption habits were observed mainly in sub-groups of adolescents declaring decreased body mass or increased physical activity during the COVID-19 pandemic. It may be suggested that physical activity may support positive changes of dietary behaviors and while combined positive changes of diet and increased physical activity, they may effectively promote body mass reduction in adolescents.The improper dietary behaviors of children and adolescents during the COVID-19 pandemic, which are associated with lockdowns and reduced physical activity, are a complex problem, potentially resulting in increased risk of diet-related diseases, including overweight and obesity and their consequences. The aim of the study was to assess the food habits during the COVID-19 pandemic and to define their association with physical activity and body mass changes in a Polish population of primary school adolescents within the Diet and Activity of Youth During COVID-19 (DAY-19) Study. The DAY-19 Study was conducted in June 2020 in a national cohort of 1334 primary school students aged 10–16 years, recruited based on a stratified random sampling of schools (sampling counties from voivodeships and schools from counties). The Adolescent Food Habits Checklist (AFHC) was used to assess food habits, associated with food purchase, preparation, and consumption, which in the studied group were analyzed separately for the period before (retrospective data) and during the COVID-19 pandemic (prospective data). The recognizable physical activity changes and recognizable body mass changes were also assessed (retrospective data) and respondents were classified as those declaring that their physical activity and body mass decreased, remained stable, or increased during the COVID-19 pandemic. It was observed that during the COVID-19 pandemic the majority of food habits changed in a statistically significant way ( The puberty period is crucial for the development of organisms due to key changes of anatomy, physiology, neurology, and behavior . In thisEspecially important are fruit and vegetables, being directly associated with decreased risk of non-communicable diseases, including obesity ,7, but aThe current situation of the outbreak of Coronavirus Disease 2019 (COVID-19) pandemic, which was associated with lockdowns and social isolation in numerous studies, also caused changes of nutritional behaviors, including shopping behaviors, that were observed both for adults ,22. HoweSimultaneously, the COVID-19 pandemic reduced for children and adolescents the possibilities of physical activity and team sports’ practicing, due to remote learning systems as well as closed playgrounds and courts, which caused, in a number of studies, a reduced physical activity level in this population group ,26,27,28Among various tools used to assess food habits, one of the commonly used questionnaires is the Adolescent Food Habits Checklist (AFHC) by Johnson et al. , which iTaking into consideration the issues described above, the aim of this study was to assess food habits during the COVID-19 pandemic and to define their association with physical activity and body mass changes in a Polish population of primary school adolescents within the Diet and Activity of Youth During COVID-19 (DAY-19) Study.The conducted study was approved by the Ethics Committee of the Institute of Human Nutrition Sciences of the Warsaw University of Life Sciences (no. 18/2020). Within the study, the diet and physical activity were assessed  and theiAll the procedures were based on the recommendations of the Declaration of Helsinki. From the participants of the study and their parents/legal guardians, their informed consent for the study participation was obtained. The DAY-19 Study was conducted in a Polish national cohort of primary school students aged 10–16 years. The participants of the study were recruited in June 2020, based on a stratified random sampling of schools, which was conducted in two phases, including: (1) sampling of counties from voivodeships (basic administrative units of Poland) and (2) sampling of schools from counties, which was conducted while using the Polish register of primary schools. The procedure was in agreement with the general approach applied in Poland to obtain a representative sample of students from all regions of the country, chosen especially during the COVID-19 pandemic ,45. In tAll the students were encouraged to participate in the study, but similarly as for schools, a low response rate was observed. The participation in the study was voluntary both for schools and within the schools for students. The final number of participating schools was 43, and they represented all the regions of Poland.−Being a student of the sampled school; −Being 10–16 years old;−Informed consent for the study participation provided from both students and their parents/legal guardians.The inclusion criteria for the participants of the study were as follows: No exclusion criteria based on the health status of participants were formulated, which was associated with the fact that the aim of the study was to assess general food habits during the COVID-19 pandemic in a population of Polish adolescents, independently from the presence of diet-related diseases. −Any missing data in the provided questionnaire;−Any unreliable data in the provided questionnaire . At the same time, the question about recognizable body mass changes during the COVID-19 pandemic was supported by the information about the current height and weight of participants, as well as their height and weight before the period of remote learning. The participants were asked about their current weight, and afterwards they were asked to within a simple one-choice question choose one option: that it decreased, remained stable, or increased during the COVID-19 pandemic. If they declared that their weight increased or decreased, they were asked to declare what was their weight before the COVID-19 pandemic. The Body Mass Index (BMI) values were calculated for each participant using a standard Quetelet equation  and they−Period of the COVID-19 pandemic (comparison of the answers provided for the period before and during the COVID-19 pandemic);−Physical activity changes ;−Body mass changes .The statistical analysis was based on the comparison of the frequency of the specific answers provided by respondents for the periods before and during the COVID-19 pandemic, assessed based on identical questions formulated twice (separately for the indicated periods), while the AFHC was used. The assessment included assessment of the following factors:p ≤ 0.05 were interpreted as statistically significant differences.The statistical analysis was conducted while using the chi-square test (for the comparison of the frequency of specific answers for the period before and during the COVID-19 pandemic) and McNemar’s test . The Statgraphics Plus for Windows 5.1 software  was used. The values of p < 0.0001). At the same time, the number of respondents who declared often buying pastries or cakes decreased , but the number of respondents who declared buying a low-fat crisps brand increased . The longitudinal analysis confirmed the significant changes of the food purchase habits in the period of the COVID-19 pandemic, which was stated for all the habits except for choosing a low-fat option while having lunch away from home. The food purchase habits assessed while using AFHC in the period before the COVID-19 pandemic and during the COVID-19 pandemic, as declared by the adolescents from the DAY-19 Study cohort, are presented in p < 0.01) and the number of respondents who declared trying to keep overall sugar intake down also increased . At the same time, the number of respondents who declared eating at least one serving of vegetables or salad with evening meal increased , while the number of respondents who declared usually including some chocolate and/or biscuits in a packed lunch decreased . The longitudinal analysis confirmed the significant changes of the food preparation habits in the period of the COVID-19 pandemic, which was stated for all the habits except for eating at least one serving of vegetables with the evening meal.The food preparation habits assessed while using AFHC in the period before the COVID-19 pandemic and during the COVID-19 pandemic, as declared by the adolescents from the DAY-19 Study cohort, are presented in p < 0.004) and eating at least three servings of fruit most days increased , while the number of respondents who declared making sure that they eat at least one serving of vegetables or salad a day also increased . Moreover, the number of respondents who declared trying to ensure that they eat plenty of fruit and vegetables increased , while the number of respondents who declared often choosing a fruit when they have a snack between meals increased  and the number of respondents who declared eating at least three servings of fruit most days also increased . At the same time, the number of respondents who declared that they generally try to have a healthy diet also increased . The longitudinal analysis confirmed significant changes of food consumption habits in the period of the COVID-19 pandemic, which was stated for all the habits except for eating sweet snacks between meals.The food consumption habits assessed while using AFHC in the period before the COVID-19 pandemic and during the COVID-19 pandemic, as declared by the adolescents from the DAY-19 Study cohort, are presented in p < 0.0001), rarely eating takeaway meals , choosing a low-fat crisps brand , and choosing a diet soft drink , as well as usually choosing the healthiest dessert or pudding in a restaurant . At the same time, a higher number of respondents who reported increased body mass, when compared with those who reported decreased body mass, declared often buying pastries or cakes .The food purchase habits assessed while using AFHC in the period during the COVID-19 pandemic, as declared by the adolescents from the DAY-19 Study cohort in sub-groups of adolescents declaring decreased, stable, and increased body mass during the COVID-19 pandemic are presented in p < 0.0001), trying to keep their overall fat intake down , trying to keep their overall sugar intake down , trying to have something low in fat while having a dessert at home , usually eating at least one serving of vegetables or salad with evening meal , and usually including some chocolate and/or biscuits while having a packed lunch .The food preparation habits assessed while using AFHC in the period during the COVID-19 pandemic, as declared by the adolescents from the DAY-19 Study cohort, in sub-groups of adolescents declaring decreased, stable, and increased body mass during the COVID-19 pandemic are presented in p < 0.01) and often eating sweet snacks between meals . At the same time, lower number of respondents who reported increased body mass, when compared with those who reported decreased body mass, declared avoiding eating lots of sausages and burgers , making sure they eat at least one serving of vegetables or salad a day , trying to ensure they eat plenty of fruit and vegetables , often choosing fruit while having a snack between meals , eating at least three servings of fruit most days , and generally trying to have a healthy diet.The food consumption habits assessed while using AFHC in the period during the COVID-19 pandemic, as declared by the adolescents from the DAY-19 Study cohort, in sub-groups of adolescents declaring decreased, stable, and increased body mass during the COVID-19 pandemic are presented in p < 0.01), often choosing a low-fat crisps brand , usually choosing a diet soft drink , and usually choosing the healthiest dessert or pudding in a restaurant . At the same time, a higher number of respondents who reported decreased physical activity, when compared with those who reported increased physical activity, declared often buying pastries or cakes .The food purchase habits assessed while using AFHC in the period during the COVID-19 pandemic, as declared by the adolescents from the DAY-19 Study cohort, in sub-groups of adolescents declaring decreased, stable, and increased physical activity during the COVID-19 pandemic are presented in p < 0.0001), trying to keep their overall fat intake down , trying to keep their overall sugar intake down , trying to have something low in fat while having a dessert at home , and usually eating at least one serving of vegetables or salad with evening meal . At the same time, a higher number of respondents who reported decreased physical activity, when compared with those who reported increased physical activity, declared usually spreading butter or margarine on bread thinly , and usually including some chocolate and/or biscuits to a packed lunch .The food preparation habits assessed while using AFHC in the period during the COVID-19 pandemic, as declared by the adolescents from the DAY-19 Study cohort, in sub-groups of adolescents declaring decreased, stable, and increased physical activity during the COVID-19 pandemic are presented in p < 0.0001), and often eating sweet snacks between meals . At the same time, a lower number of respondents who reported decreased physical activity, when compared with those who reported increased physical activity, declared making sure they eat at least one serving of fruit a day , avoiding eating lots of sausages and burgers , making sure they eat at least one serving of vegetables or salad a day , trying to ensure they eat plenty of fruit and vegetables , often choosing fruit while having a snack between meals , eating at least three servings of fruit most days , and generally trying to have a healthy diet .The food consumption habits assessed while using AFHC in the period during the COVID-19 pandemic, as declared by the adolescents from the DAY-19 Study cohort, in sub-groups of adolescents declaring decreased, stable, and increased physical activity during the COVID-19 pandemic are presented in The food purchase habits assessed while using AFHC in the period before the COVID-19 pandemic  and the The food purchase habits assessed while using AFHC in the period before the COVID-19 pandemic  and the Social isolation, caused by the COVID-19 pandemic, induced a lot of changes of everyday life, influencing also the nutrition of children and adolescents. However, based on a review by Stavridou et al. , it may The results of numerous studies indicate a growing problem of the excessive body mass of adolescents during the COVID-19 pandemic ,54,56, sAmong various factors influencing food habits of adolescents, there is an important impact of their parents on the food choices of their progeny . In spitThe previous studies by other authors indicated that social isolation and prolonging stays at home, commonly associated with internet and social media overuse, are a factors which may have a negative impact on a mental health of children and adolescents in this period, causing anxiety symptoms, depression, and post-traumatic stress . Some stIt should be indicated that increased screen time, which is commonly observed during the COVID-19 pandemic , may alsTaking into account the fact that during the period of adolescence some physical activity patterns are developed and strengthened, the observations made in this group during the COVID-19 pandemic may be especially important. The research conducted before the pandemic revealed that adolescents declaring a higher physical activity level at the same time have better nutritional behaviors than the other adolescents . MoreoveAs indicated by Barwais , during In spite of the fact that the conducted study presented some novel observations of the food habits during the COVID-19 pandemic and their association with physical activity and body mass changes in a Polish population of primary school adolescents, some limitations of the study should be listed. The most important issue is associated with the fact that participants were asked about their situation before the COVID-19 pandemic, so gathering retrospective data was included, which may generate so-called recall bias, being a systematic error caused by possible errors of the recollections retrieved by study participants regarding events or experiences from the past. However, it should be indicated that the COVID-19 pandemic was unexpected, so it was not possible to plan an adequate prospective study to conduct such an assessment without recall bias. As such, in spite of the existing bias, the study provided some valuable observations. At the same time, there is also a risk of a self-selection bias, which may have caused that some potential participants of the study did not intend to participate and those who intended had some specific characteristics. The other issue is associated with a fact that participants were not asked about their diet-related diseases diagnosed during the COVID-19 pandemic, and about those diagnosed previously, so some of the observed results may be influenced by specific dietary recommendations which must be followed due to some diseases or disorders. Last but not least, in spite of the fact that some interfering factors were taken into account, there are also other potential factors that were not studied, such as changes of the family socioeconomic status, which may have been caused by the pandemic  and also may have influenced the food habits of adolescents. In the period of the COVID-19 pandemic and resultant remote education, adolescents in Poland presented different food habits than before. Positive food purchase, preparation, and consumption habits were observed mainly in the sub-groups of adolescents declaring decreased body mass or increased physical activity during the COVID-19 pandemic. It may be suggested that physical activity may support positive changes of dietary behaviors and, when combined positive changes of diet and increased physical activity, they may effectively promote body mass reduction.


One of the main aims of current biology is to understand the origin of the molecular organization that underlies the complex dynamic architecture of cellular life. Here, we present an overview of the main sources of biomolecular order and complexity spanning from the most elementary levels of molecular activity to the emergence of cellular systemic behaviors. First, we have addressed the dissipative self-organization, the principal source of molecular order in the cell. Intensive studies over the last four decades have demonstrated that self-organization is central to understand enzyme activity under cellular conditions, functional coordination between enzymatic reactions, the emergence of dissipative metabolic networks (DMN), and molecular rhythms. The second fundamental source of order is molecular information processing. Studies on effective connectivity based on transfer entropy (TE) have made possible the quantification in bits of biomolecular information flows in DMN. This information processing enables efficient self-regulatory control of metabolism. As a consequence of both main sources of order, systemic functional structures emerge in the cell; in fact, quantitative analyses with DMN have revealed that the basic units of life display a global enzymatic structure that seems to be an essential characteristic of the systemic functional metabolism. This global metabolic structure has been verified experimentally in both prokaryotic and eukaryotic cells. Here, we also discuss how the study of systemic DMN, using Artificial Intelligence and advanced tools of Statistic Mechanics, has shown the emergence of Hopfield-like dynamics characterized by exhibiting associative memory. We have recently confirmed this thesis by testing associative conditioning behavior in individual amoeba cells. In these Pavlovian-like experiments, several hundreds of cells could learn new systemic migratory behaviors and remember them over long periods relative to their cell cycle, forgetting them later. Such associative process seems to correspond to an epigenetic memory. The cellular capacity of learning new adaptive systemic behaviors represents a fundamental evolutionary mechanism for cell adaptation. The cell is a highly self-organized dynamic molecular system that constitutes the basic fundamental unit of all known life forms.A breakthrough has been made in the knowledge of the cellular molecular components and understanding the basic mechanisms of many of their interactions. However, we still do not know many of the essential aspects of the highly self-ordered dynamics that characterize the biochemical life of cells.All molecular components of cells exhibit complex chemical transformations shaping an extreme super complex system, where simultaneously the concentrations of millions of ions and molecules change permanently following high-ordered patterns, structured in space and in time.The consequences of these incessant self-organized and self-regulated dynamics of reactive molecular transformations are adequate cellular growth, the development of all physiological processes to maintain its functional structures, continuous adaptation to the environment, and, lastly, mitosis. Alterations in these self-organized dynamics lead to different pathologies and, on certain occasions, the dynamic order collapses and cell dies.The limitations in the study of cellular molecular dynamics by traditional methods have been compensated by the efforts of quantitative sciences applied to Biology, especially Systems Biology. Physical-mathematical approaches are making possible to understand the principles underlying the complex cellular molecular dynamics adequately, so concepts such as self-organized dissipative structures, self-regulation, the emergence of functional properties, systemic attractors, and information processing, are part of the new landscape of contemporary biology.In light of these quantitative advances, each cell is not a mere molecular aggregate but a super complex dynamic system where highly self-ordered dissipative patterns, the main source of molecular order in the cell, do emerge together with self-regulatory behaviors originated by biomolecular information processing, another fundamental source of organization in the cell.Here, we present an overview of the main sources of biomolecular order and complexity that underline the molecular dynamics of cells. These sources span from the most elementary levels of molecular activity to the emergence of systemic behaviors.-In the “The Dynamics Originated by the Molecular Turnover and the Role of the Enzymes in These Super Complex Dynamics” section, we have approached two fundamental issues: the dynamics originated by the molecular turnover of cells and the role of the enzymes in these super complex dynamics.All molecular components of the cell are synthesized and degraded continually following sophisticated interdependent processes that defy the human intellect. This continuous molecular turnover is produced by a super complex dynamic system formed by millions of biochemical reactions, which occur continuously at every moment of cellular life. The continuous recycling and incessant chemical transformations, that encompass practically all molecules, shape a critical scenario, only in which cellular life is possible .The super complex dynamics originated by this huge molecular turnover constitute the fundamental systemic characteristic of all basic life units.The specialists of the life sciences and those of the quantitative sciences, attracted by the biological fact, should adequately understand the fundamental molecular dynamics of the cell, and the surprising magnitude that they reach at a global level.Numerous works have been carried out on molecular recycling, mainly of proteins . HoweverAll reactive molecular transformations occurring in the cell are essentially chemical reactions, that is, modifications on how atoms are bonded. Practically, all these dynamics of chemical changes in the cell are mediated by enzymes, the most extraordinary macromolecular nanomachines, responsible for breaking and joining covalent bonds, the fundamental chemical bonds in biological molecules. Through their ability to decrease the bond activation energy, enzymes permanently modify the way atoms are bonded, making possible the accelerated creation and destruction of molecules. Accordingly, enzymes are fundamental and essential molecules for metabolic life. They are the main focus of attention of this review.metabolic dynamics (which means activities developed by enzymes), it is not possible to properly understand what a cell is, nor the essential elements that underlie in its self-ordered and self-regulated functionality.Without understanding the meaning and magnitude of the dynamic molecular turnover that occurs in all living cells, as well as the fundamental role of enzymes in these permanent -Section “Dissipative Self-Organization of Enzymatic Activities, the Main Source of Molecular Organization in the Cell” addresses the dissipative self-organization of enzymatic activities, the main source of molecular organization in the cell.Enzymes are responsible for molecular recycling processes shaping multienzyme complexes , which carry out their activity with autonomy between them playing distinctive and essential roles in cellular physiology. When a multienzyme complex operates far enough from equilibrium dissipative self-organization can emerge , 2014.Here, we show the main enzymatic dissipative structures: biomolecular oscillations (metabolic rhythms). Even though self-organized structures are very diverse, and we also cover other different dissipative patterns including circadian rhythms, birhythmicity, multi-stability, and spatial traveling waves.Numerous physical-mathematical analyses of enzymatic pathways have contributed to a better understanding of the emergence of self-organized processes. They are essential to research the main source of molecular organization in the cell. Most of these functional biochemical studies have been carried out using systems of differential equations e.g., the Krebs cycle , the amiThe dissipative structures that emerge in self-organized multi-enzymatic complexes constitute one of the most genuine properties of cells, and the rigorous knowledge of their nature and significance is an essential element in the comprehension of the biological fact at its most basic and elementary levels.-Dissipative metabolic networks (DMN) and the emergence of the systemic metabolic structure (SMS) are covered in the “Dissipative Metabolic Networks and the Emergence of the Systemic Metabolic Structure” section.Enzymes form basic functional metabolic subsystems (multienzyme complexes) for turnover activities where dissipative patterns emerge. At a higher level of complexity, they shape different DMN, which originate the emergence of the SMS at a global level.Saccharomyces cerevisiae, Helicobacter pylori, and Escherichia coli  at a systemic level, taking into account the self-organized behavior, DMN was created in 1999 . Essentihia coli .Adenylate energy system constitutes another global process responsible for the functional enzymatic integration in the SMS at a global level. A primary systemic ratio between ATP, ADP, and AMP concentrations was proposed by Atkinson  to calcuCellular energy quantification shows that almost all organisms keep their AEC within narrow values under growth conditions, more specifically between 0.7 and 0.95, despite the extreme complex fluctuations in the adenine nucleotide concentrations.Further quantitative studies have shown that each cell is a complex non-linearly open system in which there is not a specific energy value that is conserved, but rather dynamic forms of energy change . Specifi-The “Enzymatic Information Processing, the Second Leading Source of Molecular Order in the Cell” section of this review deals with enzymatic information processing: the second fundamental source of molecular order in the cell.Enzyme activity during molecular turnover not only originates the emergence of high self-organized dissipative patterns, structured in space and time, but is also capable of producing complex self-regulatory behavior by information processing which highly increases the functional complexity of cellular system. The sophisticated cycles of construction and destruction of the molecular components could not be accomplished adequately without this source of new information, order, and organization.The first quantitative work on the processing of molecular information in bits, in a multi-enzymatic complex, was performed in 2012 in the yeast glycolysis , one of On the other hand, a dynamic structure of information processing appears in the DMN when TE is considered under systemic activity . AccordiAlong with these works, different biological examples are displayed in the text showing that unicellular organisms possess a complex self-regulatory behavior originated by biomolecular information processing, the second fundamental source of organization in the cell.-Finally, in the “Hopfield-Type Systemic Attractors in Dissipative Metabolic Networks. Cellular Systemic Behaviors” section, the emergence of Hopfield-type systemic attractors in DMN is analyzed. It is necessary to underline that these attractors allow the cellular metabolic structure (CMS) to behave as an individual and complete integral system. As a consequence, cellular systemic behaviors occur.The emergence of Hopfield-type dynamics was quantitatively observed using advanced tools of Statistic Mechanics and techniques of Artificial Intelligence in complex enzymatic dynamics . HopfielAmoeba proteus sp. and Metamoeba leningradensis sp.) showed associative learning behaviors , the self-regulation of metabolic dynamics (molecular information processing), and the emergence of the cellular systemic properties (Hopfield-like dynamics). All these issues are essential to correctly understand what a cell is.To help life scientists who are unfamiliar with quantitative sciences understand these fundamental multidisciplinary issues, we have not used mathematical formulations here. Besides, we have reinforced the fundamental ideas with a considerable number of biological examples.Systems Biology is being increasingly used as an appropriate methodology to address dynamic metabolic processes and the higher-level properties emerging in the cell from interactions between its elementary molecular parts, forming complex self-organized and self-regulated structures, from basic enzymatic activities to complex cellular adaptive behavior.Systems biology is fundamental to understand the functional architecture of the most complex, sophisticated, and overwhelming molecular system known in nature, the living cell.Cells are dynamic metabolic reactors in which millions of biochemical reactions, tightly interrelated and integrated into sophisticated networks, shape the most complex molecular system in nature.All molecular components of the cell are in a dynamic state of reactive transformations. The proteome, lipidome, glycome, metabolome, and transcriptome are synthesized and degraded continually in all cell types see .Not only molecules but also cellular structures are subjected to cycles of construction and destruction. For instance, the endoplasmic reticulum, the largest endomembrane system, exhibits a permanent turnover; the cytoskeleton is another molecular dynamic system that undergoes continuous reorganization through the synthesis and degradation of its structural elements during the cell cycle; the mitochondria are dynamic organelles that are incessantly undergoing fusion, fission, and molecular destruction; the peroxisome turnover also takes place by autophagy-related mechanism; also, cellular membranes are highly reactive dynamic structures in non-stop recycling, so, in 30 min, an active cell such as a macrophage recycles by endocytosis and exocytosis an amount of plasma membrane that equals its complete plasma membrane see .From a molecular perspective, each cell is in a permanent state of self-construction and self-destruction. This is the fundamental systemic characteristic of all basic units of life. The continuous molecular recycling that defines the systemic cellular functionality relies on a super complex dynamic system formed by millions and millions of biochemical reactions which occur continuously, at every moment of the cellular life.metabolism  and anabolic processes . These anabolic and catabolic reactions ensure molecular recycling in the cell.Enzymes are the biomolecules that perform the most important biological cellular functions. Unlike the rest of the biomolecules, enzymes are not passive. They are the only ones that can carry out a catalytic activity, transforming some molecules into others and developing complex interrelated reactive dynamics . These biocatalysts are responsible for the formation of all the ATP in the cell, DNA synthesis, apoptosis, mitosis, cytoskeleton organization, DNA repair, alternative splicing, chromosome regulation, gene expression, post-translational modifications, Golgi apparatus activity, etc. In short, all the main activities in the cell are mediated by enzymes. They constitute the fundamental elements of all essential physiological processes, which allow a cell to grow, multiply, and adapt to the external medium. However, being biologically essential, many issues of enzyme activities remain poorly understood which warrant further investigation.There are a lot of important biomolecules in the cell, such as ATP, nucleotides, lipids, structural proteins, etc., but enzymes constitute the unique active biomolecules with the capacity to reordering the atoms, i.e., the ability to transform some molecules into others creating or destroying bonds between atoms.catalytic specificity. However, the enzymatic functionality, the set of different patterns of activity carried out by every enzyme, cannot be predicted from the primary structure alone. Enzymes are not rigid molecular structures; they have complex dynamic conformations and are continuously undergoing a wide range of conformational fluctuations which modify their catalytic activities. Even in the native state, an enzyme exhibits a range of complex interconverting conformations driven by thermodynamic fluctuations . The time of diffusion between successive catalytic steps is minimized. This non-covalent direct transfer process of metabolic intermediates originates faster catalysis, making the catalysis more efficient in the multienzyme sets  in such a way that all the substrate and product concentrations spontaneously start to oscillate along time , see All metabolite concentrations of multienzyme sets that exhibit dissipative self-organization processes present transitions between complex oscillations and quasi-steady states under cellular conditions . The qua2 . These endogenous autonomous oscillators can adapt their internal metabolism to changes in the external environment  during 24-h day/night cycles . CircadiCircadian transcription-translation cycles are intertwined with different metabolic activities and respiratory oscillations, which ensures the systematic coordination and integration of cellular physiological processes .–1 for calcium waves; Lastly, a fundamental type of dissipative structure in cells is the spatial traveling waves which consist of three-dimensional self-organized coherent oscillation of metabolite concentrations that propagates progressively across the intracellular medium, reminiscent of a wave moving across water. These wave pulses of biochemical activity, moving through subcellular domains over large intracellular distances, are too fast .All modular metabolic networks that shape the cell can be considered as discrete dynamic sets, which perform relatively autonomous activities with specific and coherent enzymatic functionalities. Several scientific works have demonstrated that these elemental networks shape specialized modular units showing the genuine segregation of the metabolic activity . SegregaDissipative multienzyme complexes can also be considered fundamental modular networks , 2014. Imetabolic segregation, catalytic activities present another essential property of organization: systemic metabolic integration.Aside from the Biocatalytic sets organized into distinct basic modular networks are functionally integrated with the cell through global coordination resulting from the concerted metabolic actions of the different specialized biochemical activities as a whole .functional segregation expresses the partial interdependence of specialized metabolic nets , functional connectivity , and effective connectivity , see an example in A significant number of experimental and numerical works have shown that basic units of life exhibit complex self-regulatory behaviors originated by biomolecular information processing, the second essential source of order and organization in cells.According to the Information Theory, TE permits quantifying, in bits, the information of biomolecular patterns see . The infTE ≤ 1.00 (with mean ± SD = 0.79 ± 0.12), which suggests highly effective connectivity in the dissipative multienzyme subsystem. The analysis also indicated that the flows of functional connectivity (contained in the different metabolite patterns) change in all catalytic transitions studied , and it occurred with the emergence of complex quasiperiodic patterns. The phosphofructokinase (E2) was the principal source of molecular information in the system, and the pyruvate kinase worked as a sink, which corresponds to a functional target; the irreversible enzyme hexokinase appeared with a flow close to zero and less constrained .In summary, as a whole, the glycolytic pathway operates as a molecular information processing system, which at every moment redefines metabolic information flows that make each irreversible enzyme evolve with well-defined catalytic activities, under different inputs of glucose concentrations. The glycolytic metabolic subsystem behaves as a catalytic unit highly self-organized (dissipative processes) and self-regulated against the external changes of glucose input concentrations (molecular information processing). Each irreversible enzyme carries out three informative operations simultaneously: molecular information reception, molecular information integration, and source of new informative molecular flows. Thus, the dissipative multienzyme subsystems exhibit, at any time, precise sets of molecular instruction fluxes, and, as a result, each multienzyme complex shows specific and well-defined metabolic activities that permanently self-regulate the system. These dissipative multienzyme complexes can be considered the most fundamental units to accomplish the processing of molecular information in the cell .To understand how different multienzyme complexes functionally operate together, TE was applied for the study of the catalytic activities of DMNs . In thisSMS was observed under these external conditions, i.e., MSb12 was permanently active working as the metabolic core, the other subsystems presented on-off shifting states, and MSb15 was inactive . Even more, the network adapted its metabolic activity to the new environmental situation (a single stimulus) through its structural and flux plasticity , exhibiting both metabolic structural plasticity  and metabolic flux plasticity ; this type of global self-regulation has been observed in several unicellular organisms . There are multiple functional stable states for a DMN.Second, due to self-organized and self-regulated processes in the DMN, systemic attractors  emerge and globally govern the network. All enzymatic dynamics are stabilized in these systemic attractors. Multiple attractors  define the complex landscape on which the systemic enzymatic dynamics rely. As a consequence of the attractor dynamics, the metabolic system works as a fully integrated and individual entity.Third, “the systemic attractors that emerge in the system correspond to Hopfield-like dynamics which can store metabolic information patterns . The bioIn sort, Hopfield-like metabolic attractors store systemic enzymatic dynamics which may be properly recovered from external stimuli. Metabolic dynamics are systemically governed by these metabolic attractors which modulate the enzymatic activities, change the connections among dissipative multienzyme associations, and stably store these dynamic connections.The study with Hopfield networks  quantitaThe principles of associative memory were discovered at the beginning of the 20th century by Nobel Laureate Ivan Pavlov in his classic studies with dogs, which opened up a new paradigm in behavioral sciences.In all organisms with a nervous system, associative learning and memory are essential cognitive characteristics that allow obtaining critical information for adaptation and survival, mastering new behaviors through the association of diverse stimuli. These characteristics are ubiquitous in numerous species from mollusks to humans, but until now they have never been observed in individual cells.A. proteus and M. leningradensis were analyzed under an associative conditioning setting , the DC electric field and the peptide related to the nutrition of amoeba, placed at the positive pole, some amoebae seem to relate these stimuli (anode and peptide), and subsequent control tests showed that most of the conditioned They acquired a new persistent pattern of cellular motion, described by the move toward the anode , insteadThese experiments, in which a single cell links two different simultaneous stimuli thus developing a new behavior, are the first published evidence that an associative Pavlovian-like memory is present in single cells .Cellular conditioning may be necessary for critical functions, for example, the regulation of migration. Locomotion movements are fundamental not only to survive and avoid predators, but also in individual cells of multicellular organisms to carry out essential life processes like embryogenesis, organogenesis, immune response, tissue repair, and others. Several severe health conditions, such as cancer, vascular and heart diseases, and intellectual disability, may develop as the consequences of inaccurate control of this systemic motility property. Such migratory cellular abilities are also present in the metastatic process of cancer .In this review, we have mainly approached four aspects that characterize cellular functioning: the role of dynamic molecular processes, the mechanisms implicated in self-organization (dissipative structures) and the self-regulation of metabolic dynamics (molecular information processing), and the emergence of the cellular systemic properties.More specifically, the work focuses on the main principles that govern enzymatic activity, under complex dynamic conditions prevailing inside the cell, which are crucial to elucidate the structural and functional architecture of basic units of life.The scope of Systems Biology applied here is based on integrating concepts and knowledge in Biochemistry, Enzymology, Molecular and Cell Biology, and other biological sciences. We also discussed the results of quantitative research, analyzed by application of physical-mathematical tools such as statistical mechanics, differential calculus, discrete mathematics, artificial intelligence, computing, and others. Nevertheless, favoring the didactic purpose of the review we did not use the mathematical formulations.The following paragraphs add some conclusive examples and summarize the main aspects of this review in an integrative way.Strictly speaking from a biochemical viewpoint, the cell is a complex molecular reactor, extremely self-organized in a sophisticated manner, and in a permanent biomolecular recycling status (section “The Dynamics Originated by the Molecular Turnover and the Role of the Enzymes in These Super Complex Dynamics”).Millions of biochemical reactions happen simultaneously in every basic unit of life at any time. This process of reactive transformations also includes subcellular structures. Nothing is inert, all the molecules and structures that make up each cell undergo complex chemical transformations see . Notice The cell is an extremely complex and dynamic system; the endless molecular turnover, which characterizes it, modifies the chemical composition of the whole reactor every second and, as a consequence, the concentration patterns of ions and molecules change permanently over time. These continuous cycles of synthesis and destruction, and incessant chemical molecular transformations shape the essential scenario in which cellular life is possible. When this dynamic process of molecular turnover collapses, the cell dies. This is the main systemic characteristic of all living unicellular organisms.The consequences of self-regulated turnover dynamics are adequate cellular growth, the development of all physiological processes to maintain its functional structures, continuous adaptation to the environment, and mitosis.in vitro or in silico, has failed so far. In every cell, molecular synthesis and destruction are compensated and harmonized between them, following complex and unrepeatable reactive patterns, whose laws and defining principles are still unknown.The highly complex organization of cellular turnover dynamics defies the human intellect. Any attempt to synthetically reproduce this global molecular turnover, either Enzymes are fundamental molecules for metabolic life. Molecular reactive transformations are essentially chemical reactions, modifications on how atoms are bonded. Practically, all reactive transformations in the cell are mediated by enzymes, extraordinary macromolecular nanomachines responsible for breaking and joining covalent bonds, the fundamental chemical links in biological molecules (section “The Dynamics Originated by the Molecular Turnover and the Role of the Enzymes in These Super Complex Dynamics”). Cellular life would be impossible without enzymes; they are key protagonists in all reactive and physiological processes in the cell.active macromolecules responsible for the chemical work. Through their ability to decrease the activation energy of bonds, enzymes permanently modify how atoms are bonded, making possible the accelerated creation and destruction of molecules.Unlike other cellular molecules, enzymes are Catalytic enzymatic activities are termed metabolic processes. There are two basic types of enzymatic reactions, catabolism (implicated in molecule destruction) and anabolism (implicated in molecule synthesis). Together, these enzymatic activities are called cellular metabolism. In short, the cell is a complex enzyme-mediated metabolic system where reactive molecular transformations of synthesis and destruction happen unceasingly mediated by catalytic activities.Reactive cellular processes have little to do with the Chemistry of Equilibrium. The fundamental characteristic of cellular biochemistry is that the catalytic reactions, considered globally, occurs far from the Thermodynamic Equilibrium. Under these particular conditions, irreversible enzymatic processes raise the spontaneous emergence of self-organized dissipative structures .Different catalytic mechanisms allow processes far from Thermodynamic Equilibrium, and one of the most important is the non-linear enzyme kinetics of many irreversible enzymes with allosteric regulation , 2007.Two principal types of self-organized dissipative structures emerge in the cell, temporal molecular rhythms, and spatial waves. In temporal rhythms, molecular concentrations fluctuate over time in an oscillatory manner . Every cSo, the cell is a metabolic system in which self-construction and self-destruction occur following complex catalytic rhythms, mainly coordinated by spatial molecular waves.The self-organized dissipative structures were discovered by Nobel Laureate Ilya Prigogine , and themetabolic segregation and systemic metabolic integration, operating simultaneously (section “Dissipative Metabolic Networks and the Emergence of the Systemic Metabolic Structure”).At the cellular level, enzymatic activity dramatically depends on the collective functional structure of catalytic processes which is defined by the two fundamental principles that connect the main forms of enzyme organization in the cell: Enzymes do not work independently of each other in the cellular molecular crowding, but instead shape different types of multienzyme associations, grouped by their metabolic tasks and catalytic roles. Thus all chemical reactions that occur in living cells are segregated functionally .Moreover, these catalytic complexes interact reversibly with structural proteins and membranes originating thermodynamically open microcompartments, in which molecular rhythms can regulate the efficiency of the enzymatic reactions involved .Metabolic Subsystem was suggested in 1999 to refer to these self-organized multienzyme sets in which complex quasi-steady-state behavior and molecular oscillations may emerge spontaneously inside the cell (The term the cell . These dthe cell  representhe cell .systemic metabolic integration) forming a very complex dynamic super-system, the CMS. Such global structure was observed for the first time in 1999 by analyzing DMN through numerical studies .The dissipative multienzyme complexes permanently send information through metabolite patterns between their different enzyme components. As a result of the overall process, these enzymatic assemblies operate as basic molecular information processing units . Thus, eCMS behaves as a self-regulated dynamic entity that permanently sends specific regulatory signals to multi-enzyme complexes make them evolve in well-defined and precise metabolic activities by information processing, see On the other hand, a complex parallel super-system of information processing appears in the metabolic networks when the systemic activity is considered . CMS behPhysarum polycephalum is a paradigmatic example of the emergence of complex cellular behaviors mediated by information processing in unicellular organisms. This microorganism can discover the minimum-length option between two distant points in a labyrinth . Besides, the information generated in these processes highly increases the complexity of cellular system. abyrinth . Note thabyrinth . P. polyutrients ; 2004b.  NP-hard . This mu NP-hard . During  happens . It has  happens . Recentllearning . Molecullearning .Efficient information processing is impossible without memory (section “Hopfield-Type Systemic Attractors in Dissipative Metabolic Networks. Cellular Systemic Behaviors”). The presence of Hopfield-like dynamics characterized by associative memory in dissipative enzymatic networks was numerically verified in 2013 . Such a A. proteus and M. leningradensis  amoebae. This research also allowed the quantification of the importance of the nucleus during the cellular migration  in cells and cytoplasts matches with the Pavlovian-like dynamic memory (44 min on average)” ” .The nucleus has been classically considered an essential element governing cell movement, nevertheless direct quantitative evidence was lacking. The migratory analysis of enucleated and non-enucleated amoebae described above  also demCMS exists , to research the mechanism behind the emergence of the omplexes . The funThe high redundancy of the enzymes (with an increased number of copies) and the consequent multiplicity of dissipative self-organized multienzyme complexes that prevail inside the cell would determine the spontaneous formation of the SMS.CMS.A continuous process of molecular synthesis and destruction represents thousands of metabolic reactions that happen permanently and simultaneously in the cell, ensuring the emergence, robustness, and stability of the The only possible scenario for cellular life is a dynamic system in permanent self-construction and self-destruction process that guarantee the functionality of a high number of dissipative self-organized multienzyme complexes. There is no other alternative. This sophisticated and massive dynamics of endless molecular transformations encompasses the whole metabolic system and constitutes the most critical dynamic property, essential and definitory, of cellular life.metabole meaning “change” or “transformation.” This word reflects exactly the essential characteristic of the basic units of life. Rather than a molecular genotheque (box of genes) in evolution, the cell could be considered a singular dynamic metabolic unit capable to self-organize and self-regulate in an endless process of molecular turnover.The word “metabolism” comes from the Greek de novo.”“Metabolism can be considered the largest known source of molecular complexity in nature” . RoughlyCMS. “Through the structural and functional complexities, the metabolic evolution has developed a large diversity of biochemical organizational forms, ranging from sophisticated bacterial metabolism, via the complex enzymatic networks, characteristic of protists, to the extraordinary structures and processes derived from the multicellular eukaryotic organization, such as embryogenesis or the neural networks present in higher mammals. The millions of living metabolic species represent the inexhaustible source of complexity developed by the dynamic forces of the cellular metabolism” (Across the millennia, many adaptive molecular mechanisms have been acquired in the biological evolution by the abolism” .Every unicellular organism results from the direct and uninterrupted transmission of this extraordinary and singular metabolic organization. Over millions of years, sophisticated metabolic dynamics have evolved to originate complex biological supracellular structures, reproducing at different scales the singular intrinsic organization enclosed in itself … up to become self-aware.ID, LM, MF, JC-P, JL, and IM performed the analysis and design of the research mapping. LM involved in main funding. All authors wrote the manuscript and agreed with its submission. IM conceived, designed, and directed the investigation.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Drug-induced liver injury (DILI) encompasses the unexpected damage that drugs can cause to the liver. DILI may develop in the context of an immunoallergic syndrome with cutaneous manifestations, which are sometimes severe (SCARs). Nevirapine, allopurinol, anti-epileptics, sulfonamides, and antibiotics are the most frequent culprit drugs for DILI associated with SCARs. Interestingly, alleles HLA-B*58:01 and HLA-A*31:01 are associated with both adverse reactions. However, there is no consensus about the criteria used for the characterization of liver injury in this context, and the different thresholds for DILI definition make it difficult to gain insight into this complex disorder. Moreover, current limitations when evaluating causality in patients with DILI associated with SCARs are related to the plethora of causality assessment methods and the lack of consensual complementary tools. Finally, the management of this condition encompasses the treatment of liver and skin injury. Although the use of immunomodulant agents is accepted for SCARs, their role in treating liver injury remains controversial. Further randomized clinical trials are needed to test their efficacy and safety to address this complex entity. Therefore, this review aims to identify the current gaps in the definition, diagnosis, prognosis, and management of DILI associated with SCARs, proposing different strategies to fill in these gaps. Idiosyncratic drug-induced liver injury (DILI) is an unpredictable, host-dependent, generally not dose-related and not reproducible in animal models adverse reaction that drugs, herbal, and dietary supplements can cause to the liver .DILI manifests in a variety of clinical presentations, including hypersensitivity features, which are present in a small proportion of patients. Indeed, in different DILI registries in which usually liver damage is the predominant adverse reaction, the prevalence of these hypersensitivity manifestations varies from 14% to 25% . On the Moreover, in DILI cases associated with cutaneous adverse drug reactions (ADRs), liver involvement is not usually accurately assessed when skin injuries are predominant and represent the first clinical manifestation, which is partially due to the lack of information regarding liver injury in the SCARs cohorts retrospectively analyzed ,12,13,14Although there are significant differences in which drugs are most likely to cause SCARs versus DILI , a numbeThe immune checkpoints inhibitors (ICI) by targeting immune checkpoints favor a vigorous and sustained immune response and represent a new paradigm in the treatment of advanced cancer. The ICI block the CTLA-4 and PD-1 pathways . HoweverInterestingly, recent studies reported that candidate drugs for the treatment of coronavirus disease 2019 (COVID-19), such as azithromycin, hydroxychloroquine, ivermectin, or tocilizumab ,27,28,29Immediate withdrawal of the causative drug is the first and critical step in the management of DILI. Under the rationale that SCARs are immunoallergic adverse reactions to drugs, steroids remain the cornerstone of therapeutic approach of these patients. Furthermore, clinicians are prone to use corticosteroids in severe DILI or DILI associated with prominent hypersensitivity features, including autoimmune-like hepatitis ,30. HoweTherefore, this review aims to identify and discuss the current research gaps in the diagnosis and management of DILI associated with SCARs, focusing on the disparities of the definition criteria used in the studies conducted to date. Finally, different approaches will be put forward to fill in those gaps.Liver is the internal organ most frequently involved in SCARs . HoweverIn the past years, international groups have worked toward the correct identification of conditions involving DILI associated with SCARs, such as the DRESS syndrome. Thus, the criteria and scoring system proposed by the RegiSCAR group are the currently most accepted definition for DRESS . RegiSCAThis low specificity in the definition of liver injury previously commented contrasts with the updated DILI criteria proposed by a multidisciplinary expert group in the framework of the International Serious Adverse Events Consortium in 2011 . This paThe adoption of the stringent DILI diagnostic criteria proposed by the aforesaid expert consensus  would reOn the other hand, the presence of hypersensitivity features might not be considered a specific criterion in the diagnosis of idiosyncratic DILI. The prevalence of hypersensitivity features such as eosinophilia among DILI patients ranged from 11 to 23% across prospective DILI registries . In a stDue to the lack of biomarkers or specific tests in the diagnosis of DILI associated with SCARs, the careful exclusion of other competing liver causes becomes crucial to identify a specific drug as the cause of the adverse reaction. Thus, the usefulness of causality assessment tools to determine the role of a suspected drug is particularly relevant, although this process is challenging in those cases when multiple suspected drugs are involved.Currently, the relationship between drugs and related adverse events can be evaluated by different methodologies: expert judgment, probabilistic methods, algorithms, or scales. The consensus judgment provided by experts based on clinical experience and thorough analysis of competing etiologies tends to maximize the specificity and is currently considered as the best standard ,50. HoweIn addition to the expert’s consensus agreement, there are complementary causality assessment tools available to help in the identification of the causative agent responsible for the DILI episode associated with SCARs. Nonetheless, despite this availability, these tools have shortcomings in the correct evaluation of DILI associated with SCARs . One of More recently, a group of experts built up an algorithm of drug causality in epidermal necrolysis, the so-called ALDEN, to evaluate the causality of medications in SJS or TEN . HoweverOn the other hand, the RegiSCAR study group has developed its own scoring criteria to conduct a case assessment . They scThe most extended causality assessment tool for DILI is the validated Council for International Organizations of Medical Sciences/Roussel Uclaf Causality Assessment Method (CIOMS/RUCAM) scale . This scThe Digestive Disease Week-Japan (DDW-J) scale was developed by the Japan Society of Hepatology . Despitein vitro systems such as patient-derived cells. Monocyte-derived hepatocyte-like (MH) cells from DILI patients have been proposed for the identification of drug-specific immune-mediated reactions [in vitro, despite it exhibiting limited sensitivity and specificity depending on the reaction and the culprit drug [A different approach to delve into the impact of both individual and drug-specific factors on the pathogenesis of DILI associated with SCARs is the use of eactions , althougrit drug ,64. A ferit drug . The userit drug . Recent rit drug .Therefore, the gap to address in the causality assessment of DILI associated with SCARs relies on the need to standardize the use of an easy-to-use scale in the clinical setting that evaluates both hepatic and extrahepatic manifestations. Novel proposals, such as the modified electronic version of the CIOMS/RUCAM scale, namely Revised Electronic (version) of Causality Assessment Method (RECAM)  Supplem, which sThe occasional occurrence of DILI with SCARs strengthens the immunological mechanisms underpinning these manifestations and implications for therapy . IncreasThere is also growing evidence that DILI and different ADRs are dependent on the superposition of many different factors such as gender, age, genetics, and environmental and physiological factors ,76,77. TThis might partially explain why the disease is so infrequent despite several genome-wide association studies (GWAS) reporting associations between HLA alleles and the predisposition to ADRs related to a number of drugs . The disSome investigations have suggested an overlap of HLA alleles of risk, where one allele may increase the predisposition to different drug-induced hypersensitivity reactions and phenotypes . For exaAt the same time, the HLA-B*15:02 allele is associated with phenytoin-induced SCARs . In factp < 0.001) [Regarding drug hypersensitivity with cutaneous manifestations, there can be HLA alleles shared by both SCARS and DILI. Carriers of the HLA-B*58:01 allele showed increased susceptibility to allopurinol-induced SCARs, both DRESS and SJS/TEN ,93,94. I< 0.001) .Moreover, it has been reported that HLA-A*31:01 was the strongest predictor of carbamazepine-induced SCARs, as well as the predisposition to carbamazepine-induced liver injury, indicating that HLA-A*31:01 carriage is a shared risk factor for SCARs and DILI induced by this drug . In the However, to date, only the alleles mentioned above have been associated with both DILI and SCARs predisposition. It is unknown whether these alleles play a role in the severity of liver injury manifested in cases of DILI associated with SCARs or whether they constitute a prognostic factor for DILI in patients with SCARs. Further GWAS studies are needed to establish genetic risk factors associated with both SCARs and DILI hypersensitivity reactions induced by other drugs.Alternatively, some drugs are well known to cause both DILI and SCARs, but the genetic risk factors for cutaneous reactions appear to be different from those related to liver injury. Nevirapine, a widely prescribed antiretroviral treatment, has been associated with both DILI and cutaneous ADRs. Carriage of the HLA-B*35 and HLA-C*04 alleles increase by 2.45-fold and 2.63-fold, respectively, the risk of nevirapine-induced cutaneous ADRs. On the other hand, carriage of the HLA-B*58:01 and HLA-DRB*01 alleles increase by 3.51-fold and 2.94-fold, respectively, the risk of nevirapine-induced liver injury . HoweverThe correct identification of prognostic factors is paramount in order to provide an adequate medical approach to the management of these reactions.One of the well-established models to predict death is SCORTEN, which has been tested using data from patients enrolled in the RegiSCAR. This validated score includes suspected prognostic factors for hospital mortality   and showNonetheless, one of the limitations of these scores is their restriction to SJS/TEN entities. More importantly, liver involvement is not considered among the prognostic risk factors analyzed. In a systematic review including both observational studies and case reports, Lorenz et al. (2012) found that in patients treated with dapsone who developed hypersensitivity reactions, hepatitis was significantly associated with a fatal outcome . FurtherThe presence of liver involvement and associated comorbidities is a critical factor that determines outcome in SCARs, particularly in DRESS and SJS/TEN . This ceWhen a patient is diagnosed with DILI associated with SCARs, the main steps to be taken in the management of the disease are the identification and immediate withdrawal of the offending drug, which is followed by the needed administration of supporting treatment. Nonetheless, regarding symptomatic treatment, clinical trials designed to test the efficacy of specific treatments are still scarce, consequently leading to a gap of high-quality evidence in the treatment of this disorder.Treatment with systemic corticosteroids is currently considered the most successful treatment, which is based on the role played by T cells in the pathogenesis of drug-induced hypersensitivity syndrome ,106. NonIn addition to the widely established treatment with corticosteroids, especially for SCARs, the use of intravenous immunoglobulins (IVIg) as an immunomodulatory agent deserves further attention. A group of experts of the French Society of Dermatology developed a decisional tree where the use of IVIg was restricted to severe DRESS cases with life-threatening signs or a major viral reactivation . The debIn a systematic review including mostly observational studies, the authors concluded that treatment with IVIg did not reduce mortality risk when compared to supportive care in patients with SJS and TEN, neither when data were meta-analyzed at a study nor patient level . HoweverIn those patients with contraindications for steroids treatment, cyclosporine administration has been considered as a candidate therapeutic option, despite its known nephrotoxicity . The eviEvidence from randomized clinical trials is still scarce. Findings from one open single-arm trial with 29 patients with SJS/TEN receiving cyclosporine suggested a beneficial effect of treatment on decreasing mortality . More reHence, in the light of the scientific evidence, and bearing in mind that the treatment of this complex and heterogeneous disorder comprises the treatment of both liver and skin injuries, it is necessary to conduct high-quality evidence-based studies to reach conclusions about the efficacy and safety of the above-mentioned treatments and other novel systemic immunomodulating treatments, such as tumor necrosis factor inhibitors.This study was conceived as an opportunity to critically revise the current gaps in the scientific literature in a rare but potentially fatal condition, as DILI is associated with SCARs . DespiteFirst, diagnostic criteria are heterogeneous. Most studies in the context of DILI associated with SCARs use the RegiSCAR or the J-SCAR criteria. However, these criteria lack specificity, as thresholds proposed may reflect an abnormal liver function but not a real DILI. To overcome this limitation, in a DILI expert meeting held in 2011, the panel aimed to harmonize the criteria and standardize a definition. The consensus reached led to a rise of the previous thresholds . HoweverIn addition, there is a need for new diagnostic tools that take into account the involvement of host factors in ADRs susceptibility. Numerous associations between HLA alleles and DILI/SCARs risk have been discovered in the last years. Although the majority of them have a very high negative predictive value, due to the low incidence of these ADRs, HLA testing should become a complementary test to facilitate diagnosis and prevent severe DILI/SCARs episodes .in vitro diagnostic test systems, such as MetaHepsTM, which uses MH cells from the affected patients, could help to identify the drug responsible for DILI/SCARs episodes in cases of polypharmacy. In this line, within the IMI2—TransBioLine project , the Work Package 2 aims to discover, validate, and qualify novel biomarkers in liver injury, which represents a step toward the future availability of diagnostic tests in the clinical setting. Moreover, some authors have suggested that the inclusion of in vivo diagnostics, such as the patch or delayed intradermal testing, may improve the clinical identification of immune-mediated adverse reactions and act as potential preventive biomarkers, although they are not widely available [In the next steps, external validation of new vailable ,126. ObtWith regard to causality assessment, experts’ judgment based on their experience and the exclusion of other competing etiologies remains as the best standard available up to date. The availability of a wide range of tools may help in the ascertainment of the role of a suspected culprit drug in the development of the condition, but the great variability across scales may, paradoxically, result in a disadvantage. The widely accepted CIOMS/RUCAM scale is considered the most appropriate tool to ascertain causality in DILI, but its usefulness is limited in the context of SCARs because hypersensitivity features are not scored. Therefore, this scale needs refinement to be useful in the evaluation of broad conditions. Furthermore, the time from first drug intake to the onset of the symptoms may vary according to the drug and the condition. Thus, DRESS patients exposed to antimicrobials showed a shorter latency compared to those who had taken anticonvulsants or allopurinol . LikewisThe lack of high-quality evidence-based studies in the context of DILI associated with SCARs remains as the main limitation in the evaluation of efficacy and safety of the available systemic immunomodulating treatments. Despite this, recent investigations using novel approaches, such as network meta-analysis to compare the efficacy of the different therapeutic options, have yielded that corticosteroid therapy showed benefits in treating SCARs , and itsAnother complementary tool to clinical trials to retrieve information about the safety and efficacy of tested compounds would be the use of real-world evidence, in which data from different sources such as electronic health records, claims data, prescription records, and environmental data confluence and provide a holistic view of an individual’s health status . Given tin vitro and ex vivo models to provide a confident diagnosis. The publication of specific international clinical practice guidelines would likely address most of the gaps summarized in this review.In conclusion, there are opportunities for improvement in the diagnosis and management of DILI associated with SCARs. We have critically reviewed some of the gaps and proposed some ideas to fill them. A multidisciplinary expert consensus meeting is necessary to harmonize diagnostic criteria and causality assessment. There is a need for a consensus on a list of biomarkers and


The global literature on the links between climate change and human health is large, increasing exponentially, and it is no longer feasible to collate and synthesise using traditional systematic evidence mapping approaches. We aimed to use machine learning methods to systematically synthesise an evidence base on climate change and human health.We used supervised machine learning and other natural language processing methods (topic modelling and geoparsing) to systematically identify and map the scientific literature on climate change and health published between Jan 1, 2013, and April 9, 2020. Only literature indexed in English were included. We searched Web of Science Core Collection, Scopus, and PubMed using title, abstract, and keywords only. We searched for papers including both a health component and an explicit mention of either climate change, climate variability, or climate change-relevant weather phenomena. We classified relevant publications according to the fields of climate research, climate drivers, health impact, date, and geography. We used supervised and unsupervised machine learning to identify and classify relevant articles in the field of climate and health, with outputs including evidence heat maps, geographical maps, and narrative synthesis of trends in climate health-related publications. We included empirical literature of any study design that reported on health pathways associated with climate impacts, mitigation, or adaptation.We predict that there are 15 963 studies in the field of climate and health published between 2013 and 2019. Climate health literature is dominated by impact studies, with mitigation and adaptation responses and their co-benefits and co-risks remaining niche topics. Air quality and heat stress are the most frequently studied exposures, with all-cause mortality and infectious disease incidence being the most frequently studied health outcomes. Seasonality, extreme weather events, heat, and weather variability are the most frequently studied climate-related hazards. We found major gaps in evidence on climate health research for mental health, undernutrition, and maternal and child health. Geographically, the evidence base is dominated by studies from high-income countries and China, with scant evidence from low-income counties, which often suffer most from the health consequences of climate change.Our findings show the importance and feasibility of using automated machine learning to comprehensively map the science on climate change and human health in the age of big literature. These can provide key inputs into global climate and health assessments. The scant evidence on climate change response options is concerning and could significantly hamper the design of evidence-based pathways to reduce the effects on health of climate change. In the post-2015 Paris Agreement era of climate solutions, we believe much more attention should be given to climate adaptation and mitigation options and their effects on human health.Foreign, Commonwealth & Development Office. The effects of climate change on health are already evident in populations worldwide and threaten to undermine the past 50 years of global gains in public health.14Identification of the most crucial links between climate change and health to enable mitigation and adaptation responses that support health is underpinned by timely and regularly updated review of the scientific evidence base.21Evidence before this studySubstantial efforts to track and assess the links at the global level between climate and health are underway. An example is the Intergovernmental Panel on Climate Change (IPCC)'s assessment reports, which synthesise and update scientific research every 5–8 years on the effects of climate on health, and adaptation and mitigation responses and synergies related to health. The IPCC reports attempt to synthesise the state of evidence, but can only include a small fraction of the literature base, which is large and increasing exponentially. To date, there is no comprehensive evidence using machine-learning methods for systematic evidence mapping or synthesis to capture the breadth of the literature on this topic.To contextualise this study and identify previous similar work, we searched for publications that used systematic methods to synthesise the global literature on climate and health. We used a wide definition of systematic methods, including systematic reviews, meta-analyses, meta-syntheses, scoping or mapping reviews, bibliometric analyses, and other approaches with explicit and transparent review methodologies. For peer-reviewed articles published in English between Jan 1, 2013, and April 9, 2020, we did a rapid title and abstract review of literature indexed in Web of Science and Scopus for articles including the topic terms “climat*” AND “health*” AND “systematic” , and in PubMed using the MeSH terms “climate change” AND “systematic review” . We screened for articles that were global in scope and not restricted to particular health outcomes, climate-related drivers, or particular populations. We found studies reviewing the relationship between climate and health (using a range of systematic approaches) for specific regions and nations, climate-related hazards, and health outcomes or determinants.Our search returned only one relevant published article without geographical or topic restrictions that provided a bibliometric analysis of global climate and health literature between 2003 and 2018. Bibliometric results focused largely on authorship networks, additionally identifying frequent keywords and keyword co-occurrence. Their results showed scarce published studies outside of high-income nations and China, and substantial overlap of keywords across articles. The bibliometric analysis used a single database (Web of Science) and a narrow set of search terms (retrieving 6719 articles). It used bibliometric analysis methods that did not include screening or coding of articles, and did not apply machine learning approaches. There is also an emerging literature drawing on the synthesis of national or urban policy documents to empirically assess adaptation or mitigation policy, or both, related to the effects of climate change on health.Added value of this studyThis is the first study to combine machine learning and systematic evidence mapping approaches to comprehensively describe and map the global scientific literature on climate and health. Given the exponential increase in literature on climate and health, almost all conventional systematic mapping approaches have narrowed their geographical or topical scope to maintain the robustness of systematic methods. The literature on automation in evidence synthesis has mainly focused on specific machine learning interventions in different stages of the systematic review process. We leverage machine learning to more accurately identify and classify relevant literature at both the screening and analysis stages, reflecting significant advancements on standard bibliometric methods, and showing the potential benefit of these methods to support multiple stages of the assessment pipeline.We build on our previous work, and show how evidence mapping can be scaled to vast literatures that characterise entire research fields through the development of a (semi)automated machine learning pipeline. Such automation is crucial for assessments of the scientific literature on climate and health, where individuals and groups of authors can no longer manually manage increasing volumes of literature, and where conventional systematic mapping approaches increasingly introduce bias through increasingly restrictive inclusion criteria.Implications of all the available evidenceLancet Countdown, or the Pathfinder Commission. Our results additionally provide a basis for identifying and highlighting key research and knowledge gaps and prioritising allocation of research funding and resources. National and international institutions are investing in climate change mitigation and adaptation, with climate funding expected to increase substantially over the next decade. To ensure effective and adequate preparedness and mitigation of the health impacts of climate change, governments urgently need a robust evidence base to guide, prioritise, and justify interventions. Our synthesis shows geographical variation in evidence about health effects, with vulnerable regions under-represented, and key gaps in evidence across a number of climate-health pathways.The integration of machine learning with systematic evidence mapping approaches can help to maintain transparency and scientific scrutiny of scientific assessments as we move into an era of big literature. Our comprehensive map of the literature on climate and health, and the methods we used, can contribute to ongoing initiatives to assess the full breadth of the scientific evidence base in a robust and systematic way, including the IPCC, the In an age of big literature, new approaches are needed to systematically synthesise the available evidence in a timely manner.27We aimed to use machine learning methods (supervised and unsupervised) to systematically synthesise the evidence base on climate change and human health, including the impacts of climate change on health, climate change mitigation, and adaptation responses relevant to health. In doing so, we hope to provide the first comprehensive, semi-automated systematic map of the scientific literature on climate change and human health.We used machine learning approaches to systematically synthesise evidence on the associations between human health and climate change, climate variability, and weather (CCVW), globally. The protocol for this analysis has been published online.We defined key concepts using the Intergovernmental Panel on Climate Change definitions of risk, impacts, hazards, exposure, vulnerability, and adaptation and mitigation responses. We focused on global literature, but we assessed the distribution of literature based on country income status, using the 2020 World Bank income classification rankings to define low-income, lower middle-income, upper middle-income, and high-income nations.NACSOS platform.We included all empirical study designs published and indexed in English between Jan 1, 2013, and April 9, 2020, reflecting publishing since the Intergovernmental Panel on Climate Change's fifth assessment report. We searched Web of Science Core Collection, Scopus, and PubMed using title, abstract, and keywords only. Full texts were not retrieved, screened, or analysed. Grey literature were not included. A detailed description of search strings for Scopus is in online.Screening was done based on titles and abstracts using a combination of manual assessment against a set of a priori inclusion criteria and machine learning methods. For inclusion, documents had to meet the following criteria: be indexed in English; be published between Jan 1, 2013, and April 9, 2020; provide a clear link to actual, projected, or perceived impacts of climate change, responses to reduce the impacts of climate change (adaptation), or the mitigation of greenhouse gas emissions; include substantial focus on a perceived, experienced, or observed eligible health-related outcome or health system; and present empirically driven research or a review (including non-systematic reviews) of such research. Detailed screening criteria and a ROSES checklist for systematic mapping are available We used supervised machine learning to facilitate screening. This approach is based on the concept that a computer algorithm can be trained to predict the decisions that would be made by a human screener or coder. Team members manually screened a training sample of abstracts (3730 unique documents of which 2100 were randomly sampled), and coded them as relevant to the impacts, adaptation, or mitigation categories, or any combination of the three. 11% (n=410) of the training sample was reviewed by multiple team members, and differences were discussed until a consensus was reached. This human-screened sample set was used to train a supervised machine learning algorithm to predict for the remaining articles (1) whether each article is likely to be relevant to our inclusion and exclusion criteria and (2) how the document should be categorised . We compared several supervised learning algorithms from the Scikit-learn packageonline.We extracted the bibliographic meta-data for all documents retrieved through search strings. To determine where studies were taking place, we used a pre-trained geoparserWe used a method of unsupervised machine learning, topic modelling, to support analysis of literature included in this review. Topic modelling is a method that automatically identifies clusters of words that frequently occur together based on a pre-specified number of topics.online.We generated topic maps based on the outcomes of the topic model and created heat maps to visualise the relative co-occurrence of topics. We identified the most frequent and least frequent topics from among all topics in our topic model by global region for key meta-topics. We generated geographical maps to visualise the locations of studies globally. We used narrative synthesis to assess the frequency of key topics within the climate and health literature, as well as the extent of co-occurrence of topics within the topic and heat maps. We assessed the extent to which trends in the literature differ by country income class. Source code for both machine learning and data analyses are available The funder of the study reviewed and provided comments on the study protocol and draft results. The funder of the study had no role in data collection, data analysis, data interpretation, or writing of the report.Our findings showed that the literature on climate and health is vast and growing quickly . Based oClimate-health literature is dominated by impact studies, with only a minority of studies focusing on solutions and co-benefits . 13 380 12 629 (79%) of 15 914 studies on climate and health with identified place names focus on high-income and upper middle-income nations, particularly China . PublishUsing topic modelling, we mapped key hazards, health impacts, mediating pathways and risk modifiers, and responses across global regions. The resulting 70 topics, with their relative prevalence in the literature, are shown in Hazards topics include meteorological variability, the role of extreme events, and particulate emissions . As a prWe found that health topics are dominated by air quality, all-cause mortality, infectious disease, and heat stress . VariousMediating pathways include social vulnerability and urban exposure to heat risk and infectious disease . MediatiWithin the available mitigation and adaptation literature, energy policy  was the most common topic and, together with greenhouse gas emission pathways, was among the top three response topics in all regions except Oceania and Latin America . LiteratWe saw poor integration of research on impacts, mitigation, and adaptation across key topics . We mappWith higher national income level, there is a gradient of decreasing focus on infectious disease, maternal and child health, and nutritional illness, and an increasing focus on chronic disease, health system demand, and respiratory health . CompareWe assessed the co-occurrence of topics by hazard, health, mediating pathway, and response option categories, with results shown as heat maps . Co-occuAmong mediating pathways and risk factors, age and sex frequently co-occurred with child health outcomes, and maternal and child health, reflecting the unique risks associated with women and children . StudiesOptions and responses to the human health impacts of climate change included strong co-occurrence of literature on the respiratory health co-benefits of mitigation . Co-beneOur findings reveal novel geographically distributed patterns in the published evidence base linking climate change and health. We identified a predominance of evidence from high-income and upper middle-income countries, and a markedly diverse prevalence of topics across world regions, reflecting national burdens of disease and regional engagement with, and capacity to conduct, relevant research. The contrasting patterns of evidence across different country income groups highlights the need for localised responses to the effects of climate change on health, and the large evidence base emerging from China shows the changing nature of research priorities with increasing national incomes.We noted multiple evidence gaps, most notably under-representation of evidence from central Asia, north and central Africa, and South America. The disconnect in foci of research is also a concern. In Africa, for example, research is largely focused on vector-borne disease and public health systems, despite the potential for substantial climate change impacts on maternal and child health, respiratory infections, and nutritional deficiencies—which are the first, second, and 11th causes, respectively, of disability-adjusted life-years lost in Africa in 2019.Our approach to systematic evidence mapping rooted in machine learning provides a much more comprehensive and specific view of the evidence on the climate and health nexus than existing work,In summary, reliance on the meta-data of studies highlights the importance of adequate reporting by authors to enable research discovery using machine learning methods. The development of curated climate-health vocabularies , structured abstracts, and author awareness of how meta-data affect research discovery will be important in further enabling the potential of machine learning for evidence synthesis. New approaches to timely evidence synthesis will be necessary if researchers and policy makers are to keep up with rapid transitions in climate policy and a growing evidence base. The integration of methodological standards in systematic review with new machine learning approaches will be key to advancing evidence synthesis over the next decade. Development and curation of living evidence platforms, for example, are feasible and represent potentially cost-effective opportunities to support decision-making to prepare for, and reduce the current and future effects of, climate change on health.NACSOS platform and source code for this work are available online. Extended materials are available at https://doi.org/10.5281/zenodo.4352030. Data in this study take the form of published journal articles. All study data  are available at https://doi.org/10.5281/zenodo.4972515. Requests for further access to study data should be made to the corresponding author.The We declare no competing interests.