Cardiac Rhythm Regulation in Children during the Initial Period of School Education under Conditions of the North

Cardiac rhythm parameters recorded in healthy children during the initial weeks of schoolwork immediately after the transition from kindergarten to the first grade of the elementary school or from the elementary school to the fifth grade of the middle school showed that their regulatory systems were stressed to different degrees, reflecting different costs of adaptation to environmental conditions. The most pronounced changes in these parameters were observed in the first graders: because of more significant stress (sometimes, overstress) of their regulatory mechanisms, in 70% of these children complete adaptation to new living conditions was associated with greater physiological costs. In the fifth graders, a similar situation was observed only in 25% of the children examined. The less pronounced physiological changes observed in 30% of the first graders and in 75% of the fifth graders can be related to the more mature state of their cardiac regulatory mechanisms, as well as to their greater adaptability to environmental conditions during the period examined.     

Effectiveness of physical exercises for regulation of the functional state of six- to eight-year-old anxious children

The study aimed at optimizing the functional state (FS) of anxious six- to eight-year-old children showed that integrated use of physical exercises of a mainly aerobic character, relaxation training, respiratory exercises, and functional music is more effective in the long-term aspect than selective use of these means. Only physical exercises exert a marked influence in the FS of six- to eight-year-old anxious children under a stressful informational load. The use of other means of optimizing the FS appears to be less effective. The high effectiveness of physical exercises is determined by adaptive changes in the mechanisms of FS regulation in anxious children. Apparently, long-term adaptation to an adequate muscular activity ensures improved functioning of, and a better interaction between, the activating and inactivating structures of the modulating brain system located at different levels of the CNS, in particular, in the frontal cortical areas. It is emphasized that the peculiarities of the influence of different means of regulation of the FS on the body of anxious elementary school children are, largely determined by the immaturity of the frontothalamic regulatory system and the specifics of the functional organization of the limbic brain structures.     

Complex estimation of adaptation abilities of the organism in children using the indices of responsiveness of the cardiovascular system and characteristics of EEG

Based on the complex analysis of the data of cardiointervalographic (CIG) and rheoencephalographic (REG) examination of 37 healthy children and 63 children suffering from bronchial asthma (BA), we identified the most informative indices characterizing reactions of the cardiovascular system under conditions of an active orthostatic test (coefficient of autonomic responsiveness and index of responsiveness of the vessels). We conclude that the relation between the values of these indices allows one to identify the level of strain of the regulatory mechanisms and the state of the adaptation systems of the organism, which determine the adequacy of control of the autonomic sphere. The following gradations can be classified: an optimum level, compensated adaptation disorders (strain and overstrain of the regulatory mechanisms), and decompensated adaptation disorders (exhaustion of the regulatory mechanisms and failure of adaptation). Among clinically healthy children, we found a risk group (about 30%) with manifestations of lowering of the organism’s adaptive abilities. It is shown that groups of healthy children and children suffering from BA differ from each other in the shares of different patterns of EEG and variants of EEG responses to a hyperventilation test. Qualitative and quantitative characteristics of EEG in children, despite high interindividual variability, clearly correlate with the state of adaptation processes. The expedience of a complex approach in estimating the adaptation ability of the child based on the data of CIG, REG and EEG examinations is discussed. Neirofiziologiya/Neurophysiology, Vol. 38, No. 1, pp. 72–84, January–February, 2006.     

Peculiarities of formation of the cognitive functions in junior school children with different maturity of regulatory brain systems

To reveal the specific role of maturation of modulating, regulatory brain systems in formation of cognitive processes at the junior school age, was performed a complex electroencephalographic and neuropsychological examination of the 7–8-year-old children with different degrees of functional maturity of the regulatory systems. It has been shown that an essential factor determining formation of the higher psychic functions (HPF) at the junior school age is maturation of the fronto-thalamic system. Immaturity of this system in the 7–8-year-old children leads to a deficiency of functions of programming, regulation, and control of the activity. The most substantial changes were revealed for the components of the voluntary organization of the activity, which are connected with its selectivity both in realization of current tasks and in creation of the activity strategy. The deficiency of processes of voluntary regulation in the 7–8-year-old children with immaturity of the fronto-thalamic system is combined with a delay of development of the meaning-forming speech function. Comparison of data of the neuropsychological and electroencephalographic examination has permitted suggesting that the basis of the revealed changes in the HPF formation in the 7–8-year-old children is immaturity of the main neurophysiological mechanisms that provide a selective involvement of different cortical regions in providing their activity both in the course of its realization and during preparation to it as well as an under-development of differentiated intracortical connections in the left hemisphere.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 5, 2004, pp. 427–435.Original Russian Text Copyright © 2004 by Machinskaya, Semenova.To the 100-Anniversary of N. N. Traugott     

Ecophysiological studies on citrate synthase: (II) enzyme regulation of selected crustaceans with regard to life-style and the climatic zone

Citrate synthase is a regulatory enzyme of the energy metabolism pathway controlling the citric acid cycle. It was studied in order to determine modes of enzyme regulation with regard to the life-style of the investigated species. Citrate synthase from crustaceans with different life-styles were compared: the pelagic euphausiids Euphausia superba from the Antarctic and Meganyctiphanes norvegica from the Scandinavian Kattegat and the Mediterranean were compared to the benthic isopods Serolis polita from the Antarctic and Idotea baltica from the Baltic. Citrate synthase was partly purified chromatographically and the influence of adenosine 5′-triphosphate on enzyme activity was examined. Mechanisms of inhibition and inhibitor constants were determined. Two different mechanisms of enzyme regulation by ATP were found. Citrate synthase from isopods was only competitively inhibited, while citrate synthase from euphausiids showed not only competitive inhibition but also activation by low concentrations of ATP. This activation is equivalent to the reversed methanism of uncompetitive inhibition. The ecophysiological relevances of the coupling of these mechanisms are discussed. The degree of competitive inhibition was different in the two groups of investigated crustaceans. Inhibitor constants were similar within the euphausiids but not in isopods, which showed higher or lower inhibition depending on the climatic zone: the colder the ambient temperature the lower the ATP inhibition. A possible mechanism of temperature adaptation through effects of varying inhibition constants is concluded.     

Psychophysiological condition of first-year students with different levels of physical activity

The psychophysiological condition of first-year students (males) going or not going in for sport in the course of training was investigated. Baevskii’s method was used to determine the level of stress of regulatory mechanisms. The functional level of the nervous system, the stability of neural responses, and the level of functional abilities of the developed functional system were evaluated using the variation chronoreflexometric method. It was established that an improvement in the mental capacity parameters (increased mental capacity, reduction in the number of errors, an increase in the level of functional abilities, and shortening of the latent period of visuomotor response) was accompanied by an increase of stress of the body regulatory systems, which was more marked in individuals with a low level of physical activity. This fact indicates that physical activity reduces the cost of the adaptation of the body to permanently changing environmental conditions. The optimal human adaptive systemic reactions are ensured by the dynamic interaction of the functional systems forming complex correlations in the somatic, autonomic, motor, and psychoemotional spheres of the body’s activity.     

Adaptations of heart activity to physical exercise in female physical education teachers in the European North

Characteristics of heart activity were studied in female residents of the European North with ages between 25 and 59 years who were adapted to physical exercise. The results of studies of the biological age and the degree of training are presented. The mechanisms of adaptation and the specific features of the cardiovascular system (CVS) response to physical exercise depending on the duration of professional experience of subjects were determined. The greatest changes in the functional CVS characteristics were observed in the youngest (25–35 years) and oldest (46–59 years) subjects. This was shown to depend on the type of adaptation, age-specific characteristics, and moderately severe climatic conditions. Comparison of groups of subjects with different durations of professional experience showed that the speed of nervous processes decreased, the regulation of blood circulation became inert, and age-related shifts in some of the variables accelerated. These changes are considered to be the result of an increased expenditure of the physiological reserves of the body under different environmental conditions.     

Efficiency of use of physical exercises for management of the functional state of 6-8 year-old anxious children

In the research directed on optimisation of a functional state (FS) of disturbing children of 6-8 years, complex application of physical activities of mainly aerobic character, relaxation training is shown, that, respiratory exercises and functional music in long-term aspect selective use of considered means possesses more efficiency. At selective influence the expressed influence on FS disturbing children of 6-8 years in the conditions of intense information loading is rendered only by physical exercises. Application of other ways of optimisation FS is less effective. High effectiveness of use of physical exercises is caused by adaptable changes of mechanisms of regulation FS of disturbing children. Apparently, long-term adaptation to adequate muscular activity provides improvement of functioning and perfection of interaction activating and nonactivating structures of modulating system of the brain, localised on different levels the central nervous system (CNS) and, in particular, frontal departments of a bark. It is underlined, that features of influence of various receptions of regulation FS on an organism of disturbing children of younger school age are substantially caused by immaturity frontocortical-thalamic regulating system and specificity of the functional organisation limbic brain structures.     

Longitudinal Study of the Development of Higher Mental Functions in Primary School Children

This article presents the results of a longitudinal population-based neuropsychological study of the development of higher mental functions (HMFs) in primary school children from grades 1 through 3 at a Moscow public school (n = 84). We monitored changes in HMFs in the total sample and in groups of children with different baseline HMFs (high, medium, low), as measured in the first grade, using seven indexes that reflect individual HMF components such as executive functions (voluntary regulation of activity), serial organization of movements and actions, processing of kinesthetic, auditory, visual, and visual-spatial information, and regulation of activation, at three time points (first, second, and third grades). The study found a generally positive trend in the structural and functional components of HMFs in the children who were tested. Groups of children with different baseline levels of HMFs steadily maintained their differences in the degree of development of the HMFs at each evaluation time point, although the greatest change in HMF components was found in children with initially low scores, and the least change was in children with initially high HMF scores. Among the components with the least change was voluntary regulation—that is, the programming, regulation, and control of one's activity. The fact that children with high baseline functioning did not change significantly in a given function from first to third grades may be related to a decline in learning motivation, insofar as their learning is then occurring in the zone of actual and not proximal development.     

Environmental adaptations as windows on molecular evolution

Changes in gene regulation may play an important role in adaptive evolution, particularly during adaptation to a changing environment. However, little is known about the molecular mechanisms underlying adaptively significant variation in gene regulation. To address this question, we are using environmental adaptations in populations of a fish, Fundulus heteroclitus as a window into the molecular evolution of gene regulation. F. heteroclitus are found along the East Coast of North America, with populations distributed along a steep thermal gradient. At the extremes of the species range, populations have undergone local adaptation to their habitat temperatures. A variety of genes differ in their regulation between these populations. We have determined the mechanism responsible for changes in lactate dehydrogenase-B (Ldh-B) gene regulation. A limited number of mutations in the regulatory sequence of this gene result in changes in its expression. Both the phenotypic (increased LDH activity) and genotypic (changes in Ldh-B regulatory sequences) differences between populations have been shown to be affected by natural selection, rather than genetic drift. Therefore, even a small number of mutations within important regulatory sequences can provide evolutionarily significant variation and have an impact on environmental adaptation.     

Integrated influence of environmental factors on the state of microcirculation

The microcirculation system and its regulation at rest and after gradually growing physical activity in subjects living in different environmental regions was studied using laser Doppler flowmetry. Three main types of microcirculation were found. The activity of regulation mechanisms depended on the microcirculation type, residence region, and level of physical activity. Subjects living in relatively clean regions displayed stable regulation mechanisms irrespective of the level of activity. Subjects with the mesoemic type of microcirculation from regions with a high toxic contamination, high radiation background, or exposed to combined adverse factors, as well as subjects with the hypoemic type exposed to toxic and combined factors displayed a decreased contribution of VLF and LF oscillations (p < 0.05), and subjects with the hyperemic type from toxically contaminated regions displayed a decreased contribution of LF oscillations (p < 0.05). The results indicate that, under environmental pressure, regulatory mechanisms are exerted to the extent verging on adaptation failure.     

The complex influence of environmental factors on the state of microcirculation

The state of microcirculation system and its regulation in peace and after growing physical activity is analyzed on people living in different ecological regions. There are three main types of microcirculation. The level of regulation mechanisms activity depends on the type of microcirculation, region of residence and the value of physical activity. People living in a relatively clean regions have stable mechanisms of regulation despite of the level of activity. Mesoemic type living in toxic radiation regions have reduced contribution of VLF and LF-fluctuation (p < 0.05); hypoemic type living in toxic regions have VLF and LF-fluctuation (p < 0.05); hyperemic type living in toxic regions have LF-fluctuation (p < 0.05). We can conclude the tension of regulatory machanisms in microcirculation system increases under ecological pressure and borders on failure of adaptation process.     

Brain Mechanisms of Voluntary Regulation of Activity during Acquisition of the Skill of Writing in Seven- to Eight-Year-Old Children

With the aim of studying the formation of brain mechanisms of voluntary activity regulation in junior schoolchildren and the role of these mechanisms in the acquisition of the skill of writing, a complex neuropsychological investigation was carried out. In the EEG of children with learning problems and a deficit of voluntary activity regulation (VAR), signs of the functional immaturity of the fronto–thalamic regulatory system (FTS) were found. Comparative neuropsychological analysis revealed a specific impairment of the VAR in these children in the form of pronounced impulsiveness, instability of a program, problems in switching over from one program to another, and self-control difficulties. It is concluded that the functional maturation of the FTS is a mechanism of VAR development. It is shown that the VAR deficiency in children with FTS immaturity is combined with a delay in the development of semantic and mediating speech functions. It was found that the features of the development of the higher mental functions in seven- to eight-year-old children with FTS immaturity specifically affect both the semantic and graphic aspects of writing acquisition.     

Autonomic regulation and cytochemical status of lymphocytes in children at the beginning of school education

Examination of children at the beginning of school education showed that their autonomic regulatory mechanisms were stressed to various degrees, correlated with the rate of energy consumption in cells, which determines their performance and the adaptability to the adverse environment of Western Siberia. Most children displayed initial moderate or high sympathetic hypertonia (35 and 10% of children examined, respectively); in contrast, 26% of first graders were vagotonic. The highly stressed state of the regulatory mechanisms manifested itself as an unfavorable hypersympathicotonic type of autonomic reactivity. This was accompanied by certain cytochemical changes, mainly, a compensatory activation of succinate dehydrogenase, the degree of which depended on the degree of its inhibition. An optimum state of the regulatory mechanisms was found in only 29% of children, and 44% of them displayed a rather stressed state of energy-producing processes, threatening to disturb adaptive processes and the autonomic equilibrium.     

Features of brain mechanisms of regulation of the level of wakefulness, organization of cognitive functions and adaptive reactions in children with attention deficit with hyperactivity syndrome and healthy children

In work results of research of features of infringement superslow cortical-truncal, limbic-reticular and upsegmentary mechanisms of regulation of a level of wakefulness at children of 6-7 years with a syndrome of deficiency of attention and hyperactivity and healthy children, pupils of 1 class of a comprehensive school with different type of psychological adaptation are generalized. At use system-integrativity psychophysiology the approach features are established: a) organization emotional-motivational and cognitive spheres; b) psychophysiology mechanisms of formation of adaptive reactions at tactile interaction about earlier unknown alive object--a dolphin at the surveyed contingent of healthy and ill children.     

Lipids in mammalian hibernation and artificial hypobiosis

Membrane lipids—phospholipids, fatty acids, and cholesterol—participate in thermal adaptation of ectotherms (bacteria, amphibians, reptiles, fishes) mainly via changes in membrane viscosity caused by the degree of fatty acids unsaturation, cholesterol/phospholipids ratio, and phospholipid composition. Studies of thermal adaptation of endotherms (mammals and birds) revealed the regulatory role of lipids in hibernation. Cholesterol and fatty acids participate in regulation of the parameters of torpor, gene expression, and activity of enzymes of lipid metabolism. Some changes in lipid metabolism during artificial and natural hypobiosis, namely, increased concentration of cholesterol and fatty acids in blood and decreased cholesterol concentration in neocortex, are analogous to those observed under stress conditions and coincide with mammalian nonspecific reactions to environmental agents. It is shown that the effects of artificial and natural hypobiosis on lipid composition of mammalian cell membranes are different. Changes in lipid composition cause changes in membrane morphology during mammalian hibernation. The effect of hypobiosis on lipid composition of membranes and cell organelles is specific and seems to be defined by the role of lipids in signaling systems. Comparative study of lipid metabolism in membranes and organelles during natural and artificial hypobiosis is promising for elucidation of adaptation of mammals to low ambient temperatures.     

Functional state of the cardiovascular system in 13-year-old adolescents with different types of autonomic nervous regulation

The features of the functional state of cardiovascular system in 13-year-old children with different types of autonomic nervous regulation were studied. Children with normotonic and parasympathetic types of autonomic regulation were found to have the highest adaptation capacities. The autonomic nervous system influences the bioelectrical processes in myocardium, the duration of cardiac cycle phases, and cerebral blood flow. Schoolchildren aged 13 years with higher sympathetic activity have shorter duration of the cardiac cycle, the phase of isometric contraction, and diastole. They have a lower pulse blood flow rate and a higher tone of large and medium cerebral vessels. No relationship was revealed between the initial autonomic nervous regulation of heart rate and the type of adaptation of myocardium to physical dynamic loads, as well as the type of adaptation of cerebral circulation to mental stress.     

Comparative studies of gene expression and the evolution of gene regulation

The hypothesis that differences in gene regulation have an important role in speciation and adaptation is more than 40 years old. With the advent of new sequencing technologies, we are able to characterize and study gene expression levels and associated regulatory mechanisms in a large number of individuals and species at an unprecedented resolution and scale. We have thus gained new insights into the evolutionary pressures that shape gene expression levels and have developed an appreciation for the relative importance of evolutionary changes in different regulatory genetic and epigenetic mechanisms. The current challenge is to link gene regulatory changes to adaptive evolution of complex phenotypes. Here we mainly focus on comparative studies in primates and how they are complemented by studies in model organisms.     

Signal transduction and virulence regulation in human and animal pathogens

Abstract Pathogens have developed many strategies for survival in animals and humans which possess very effective defense mechanisms. Although there are many different ways, in which pathogenic bacteria solved the problem to overcome the host defense, some common features of virulence mechanisms can be detected even in phylogenetically very distant bacteria (Finlay and Falkow (1989) Microb. Rev. 6 1375–1383). One important feature is that the regulation of expression of virulence factors and the exact timing of their expression is very important for many of the pathogenic bacteria, as most of them have to encounter different growth situations during an infection cycle, which require a fast adaptation to the new situation by the expression of different factors. This review gives an overview about the mechanisms used by pathogenic bacteria to accomplish the difficult task of regulation of their virulence potential in response to environmental changes. In addition, the relationship of these virulence regulatory systems with other signal transduction mechanisms not involved in pathogenicity is discussed.     

Human Systemic Reactions to a Dosed Exposure to Hypoxia: A Multiparameter Study

Human physiological reactions to acute hypoxic hypoxia were studied. Analysis of simultaneously recorded parameters of various physiological systems showed the following: activation of the general antihypoxic defense system is based on the formation of an intricate structure of intra- and intersystemic relations of specific and nonspecific elements of adaptation that support vital body functions during environmental oxygen deficit. These specific elements become more important in more severe hypoxia, which suppresses metabolism in some organs and tissues because of redistribution of blood flow. These factors allow the body to function at a lower oxygen tension in its tissues owing to an increased efficiency of mitochondria as a result of changes in the kinetics of enzymes of the mitochondrial respiratory chain. In acute hypoxia, the structure of intra- and intersystemic relations is rather intricate; its functional hierarchy is maintained by stronger individual amplitude-related controlling factors and by modulation of their phase- and time-related links. Advanced stages of hypoxia are associated with disintegration of central regulatory mechanisms, which is manifested by disturbances in amplitude-frequency and spatiotemporal parameters of the brain bioelectrical activity, changes in phasic interactions between elements of regulatory mechanisms, and signs of deregulation and decompensation of vital functions. The interpretation of the results is based on the general theory of adaptation, Medvedev's idea of adaptation as a successive involvement of genetically predetermined and newly-formed regulatory programs of the brain, Anokhin's theory of functional systems, and modern concepts of molecular and biochemical mechanisms of hypoxia. It was concluded that artificial normobaric hypoxia is a unique, biologically adequate model that makes it possible to study the rearrangements in systemic and autonomic regulatory mechanisms in response to strictly determined changes in the environmental concentration of oxygen as a principal factor supporting life.