Psychophysiological study of the effects of adaptation to tactile interaction with dolphins in six- to seven-year-old children

The possibility of the use of an integrative psychophysiological approach to the investigation of the role of ultraslow information-controlling brain systems in the mechanisms regulating the wakefulness level and the actual development of cognitive functions in six- to seven-year-old children was estimated. For the studied children, with different types of psychological adaptation to an unfamiliar emotional situation (tactile interaction with dolphins), we found the features of the development of (a) corticosubcortical and limbic-reticular mechanisms of regulation of the wakefulness level and (b) suprasegmental mechanisms of autonomic, hemodynamic, and oxygen-dependent energy supply of the wakefulness level. The idea of a correlation between (1) the level of actual emotional and cognitive development and the type of adaptation to psychoemotional stress and (2) age-specific features of the formation of reflex and neurohumoral mechanisms of regulation of the wakefulness level in six- to seven-year-old children is substantiated.     

Functional organization of cerebral cortical areas at rest in five-, six-, and seven-year-old children

The coherence functions of the main EEG rhythmical components in five-, six-, and seven-year-old children were analyzed. The results of factor analysis showed four types of the basic structure of cortico-cortical interactions at rest. It was shown that these structures are rather stable; however, some of their connections change with age, reflecting the general trend of gradual heterochronous maturation of cerebral cortical areas.     

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.     

Error and individual difference in cardiovascular responses to orthostatic stress in humans

Variations in cardiovascular responses to orthostatic stress were investigated in terms of physiological polymorphism. Variations of physiological measurements are subdivided into individual differences and measurement errors. However, individual differences are often considered to be an error in statistical analysis due to its limitations in experimental design. In order to discuss about the relative contribution of individual difference in cardiovascular responses to postural changes, percent contribution (PC) was estimated using the Taguchi method. Six healthy male adults (age range: 21-27) were subjected to orthostatic stress by inducing a postural inclination of 60 degrees head-up-tilting to the horizontal, and the responses were measured thrice in each subject on different days. The respective changes of heart rate (HR) and stroke volume (SV) in the period from the resting supine to the head-up-tilt position were significantly increased (p < 0.01) and decreased (p < 0.01) without affecting the mean blood pressure (MBP). The PC of individual difference in HR showed a significantly higher ratio of individual difference during the head-up-tilt (71.4-76.2%) compared with supine rest (0.0-50.4%). While the main variations of HR during supine rest were not the individual differences between the subjects, the day-to-day differences within the subject were significant. The PC of individual differences in MBP and SV constantly displayed a significant difference between the subjects. These results suggest that the strategy for maintaining stable cardiovascular regulation may be different even in normal subjects. In the perspective of physiological parameters, PC monitoring may serve as an empirical approach to evaluate physiological polymorphism.     

Main Factors of a Decrease in Stress Resistance in Six- to Eight-Year-Old Children with Long-Term Consequences of Perinatal CNS Pathology during Transition to School Period of Their Activity

Central disorders that determine a decrease in stress resistance and compensatory-adaptive possibilities of six- to eight-year-old children with remote consequences of a perinatal hypoxic-ischemic CNS injury were comprehensively characterized on the basis of literature data and results of the complex psychophysiological and neurophysiological examination using complementary integral indices. The main factors responsible for constraints of adaptive possibilities of such children at a preschool age and aggravation of the central regulatory disorders during the transition to school period of their life were revealed.     

Short-term adaptation of five- to seven-year-old children to mental load

Tetrapolar rheography according to Kubicek has been used to estimate the adaptive capacity of the cardiovascular system in 150 five- to seven-year-old children at rest and during mental load. Mental load evokes two variants of stroke volume (SV) responses, one of them characterized by an increase in the SV, and the other, by a decrease in the SV and an increase in the diastolic blood pressure (BP_d). Irrespective of the direction of the change in the SV, short-term adaptation to mental load in most five- to seven-year-old children does not stress the mechanisms of the cardiovascular system control and is generally favorable. In 13–15% of the children examined, short-term adaptation to mental load considerably stressed the cardiovascular system control. This is expressed in increased systolic blood pressure (BP_s), BP_d, and heart rate (HR); decreased CV and cardiac output (Q); and a prolonged restoration period for most central hemodynamic parameters.     

Characteristics of the cerebral mechanisms controlling the level of wakefulness,maturity of cognitive functions,and adaptive responses in children with attention deficit hyperactivity disorder and healthy children of the same age

Data on the characteristics of the disturbance of ultraslow cortical-brainstem, limbic-reticular, and suprasegmental mechanisms controlling the wakefulness level (WL) in six- to seven-year-old children with attention deficit hyperactivity disorder (ADHD) and age-matched healthy children (first-year comprehensive primary school pupils) with different types of psychological adaptation have been summarized. An integrated systemic psychophysiological approach has been used to determine the characteristics of (a) the emotional-motivational and cognitive maturities and (b) the psychophysiological mechanisms of the formation of adaptive responses upon tactile interaction with an unfamiliar live object (a dolphin) in the examined groups of healthy and ADHD children.     

Autonomic Cardiac Rhythm Regulation and Temperament in Infancy

The specific features of the cardiac rhythm (CR) and temperament were studied in 92 children aged from 15 to 31 months. The average cardiac interval in a recumbent position and its variability (standard deviation) were determined. The parasympathetic tone (PT) was determined by analyzing the CR wave structure according to CR spectrum power within the range of 0.2 to 1.2 Hz. The sympathetic tone was measured by subtracting the PT contribution from the spectrum power within the range of 0 to 0.2 Hz by means of regression. The children's temperament was measured using their parents' questionnaires. Repeated examination showed the stability of the CR characteristics. The PT was shown to correlate with the children's motor activity (0.52), approaching a new subject (0.39), distraction (–0.34), and the age of entering a nursery (–0.35). The results evidenced a relationship between the parasympathetic tone and the behavioral activity during the first years of life and the role of the parasympathetic tone in physiological regulation of approach/avoidance responses and sustained attention.     

In vitro binding of auxin to particulate fractions from the shoots of dark-grown wheat seedlings

A binding site for auxins was found in the 50,000g pellet from a homogenate of shoots from dark-grown wheat seedlings. The optimum conditions for the binding of native auxin, IAA, were within the range of physiological conditions of growth (pH 5.2, temperature 20° C). The binding site displayed a high affinity to IAA (affinity constant about 10⁷ M ^–1, i.e. dissociation constant about 10^–8 M) and low capacity, 60 p mol per 1 g of fresh weight. The binding capacity of 3.5-days-old shoots is represented by about 56% and 44% of that of leaves and coleoptiles, respectively. The more rapidly growing leaves also contained more endogenous free IAA (64%) than the coleoptiles from the same seedlings (36%). The binding site was very specific, distinguishing well between strong auxins and structurally related substances which exhibit very weak auxin activity. These physiological properties of this binding site indicate that it may have a certain role in the regulation of physiological processes, such as elongation growth and cell division.     

Adaptive cardiac responses to local muscular work in children and adults with visual impairment

Preschool children and adults with visual impairments and healthy subjects were examined at rest and after local muscular efforts with the use of a hand dynamometer. In contrast to healthy children, a retarded development of the structure of the cardiac rhythm was found in children with visual impairments. These children, like adults with similar impairments, displayed a high degree of strain of the central mechanisms of cardiac regulation.     

Cyclic AMP level in relation to different conditions of sporulation rhythm regulation in Leptosphaeria michotii (West) Sacc

When Leptophaeria michotii was grown in conditions that permitted a stable periodicity of sporulation (asparagine 6.6 mM in darkness or asparagine 2.6 mM in continuous white light), the level of intracellular cyclic AMP was lower and the activity of the cyclic AMP phosphodiesterase higher in contrast to the cultures with an instable periodicity.With asparagine 6.6 mM and in darkness, theophylline (1 mM) increased the intracellular cyclic AMP level whereas caffeine (1 mM) had no effect. Theophylline (0.01 and 0.1 mM) or caffeine (0.01–1 mM) provoked a rhythm instability under these conditions. Isoproterenol (1 mM) increased the cyclic AMP level. Nevertheless, the instable rhythm observed in control fed with asparagine 2.6 mM in darkness, was partially stabilized with isoproterenol 0.01 M or 0.01–1 mM. Exogenous cyclic AMP (0.01–1 mM) provoked a complete regulation of the rhythm with asparagine 2.6 mM and a shortening of the stable period (from 27 to 21 h) when the fungus was grown on asparagine 6.6 mM.These results underlined the fact that Leptosphaeria rhythm regulation was not dependent on the cyclic AMP level only.     

Change of Parameters of Functioning of the Cardiovascular and Respiratory Systems in Rats of Different Ages under Effects of Low Doses of the Cholinesterase Inhibitor Phosphacol

In the 4-day old rat pups and adult animals there were studied effects of subacute and acute phosphacol intoxication at the doses producing and not producing inhibition of aetylcholinesterase on ECG parameters and respiration rate. Analysis of the heart rhythm variability (HRV) was performed using an original program designed in the Labview media. The frequency diapason of cardiointervals was divided as follows: the high-frequency component (HF)-0.8-2.5 Hz, the low-frequency (LF, waves of the II order)-0.8-0.3 Hz; frequencies lower than 0.3 Hz-VLF (slow waves of the III order). Under the conditions of the subacute intoxication the heart rate frequency in the 4-day old and in adult rats increases by 36% and 13%, respectively, the respiration rate frequency increases by 73% in the newborn and does not change in adult rats. The VHR analysis indicates an increase of the tone of the parasympathetic nervous system. The level of the sympathetic activity somewhat increases in adults, but decreases in the 5-day old rat pups, which leads to an essential shift of the vagosympathetic balance towards predominance of parasympathetic influences. In adult rats, unlike the newborns, the role of the humoral-metabolic factors in regulation of the cardiac rhythm and vasomotor reactions increases significantly. Remarkably, the decrease of the nervous sympathetic effects in the rat pups leads to the positive chronotropic effect and stabilization of the cardiac rhythm. Acute phosphacol intoxication (doses of 0.25 and 1 µg/kg) is studied in the 4-day old rat pups. The low dose of the drug leads to development of a moderate bradycardia without disturbances of the cardiac rhythm. The high phosphacol dose produces pronounced bradycardia; on its background there develops a long-term transitory arrhythmia representing complexes of the heart rhythm, which alternate in the decasecond or nearminute rhythm and are separated by periodicity that is one order slower. We observed such rhythm earlier during activation of central N-cholinoreactive structures and development of bilateral pneumothorax. Results of the present study allow stating the paradoxical heart rhythm not as agonic, non-peculiar to the “living” organism, but as a special form of functioning of cardiac pacemakers due to disturbances of the heart regulatory mechanism.__________Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 2, 2005, pp. 160–167.Original Russian Text Copyright © 2005 by Kuznetsov, Goncharov, Glashkina.     

Interrelations between the sympathoadrenal system,adrenal cortex,and autonomic tone in seven- to nine-year-old children

Comprehensive study of the functional state of the sympathoadrenal system (SAS) and adrenal cortex (AC) and the specific features of the autonomic regulation of the cardiac rhythm revealed close correlations between the excretion of catecholamines (CAs) and androgens, on the one hand, and the initial autonomic tone (IAT) of the cardiovascular system of children, on the other hand. Most schoolchildren of both sexes with a predominant dependence of their cardiac rhythm on sympathetic influences were shown to excrete more noradrenaline (NA), 17-hydroxycorticosteroids, and 17-ketosteroids and less dopamine than their normotonic and vagotonic counterparts, which was accompanied by an increase in the NA-to-adrenaline ratio. In contrast, eight-and nine-year-old girls exhibited a relatively decreased activity of glucocorticoid functions of the AC associated with sympathicotonia. A local static effort performed as a functional test caused similarly directed changes in the functional states of the SAS and AC in a manner dependent on the child’s IAT, age, and sex. In the states of sympathicotonia or normotonia, nine-year-old girls exhibited a decrease in the excretion of CAs and DOPA or their insignificant increase accompanied by strengthening of the functional activity of the AC, especially of its androgen function. This may be interpreted as a manifestation of specific neuroendocrine interrelations in the adaptive mechanisms of nine-year-old girls and a higher stability of the pituitary-adrenal system, which controls metabolic processes in the growing body. In contrast, in normotonic and vagotonic seven-year-old boys (as well as in sympathicotonic eight-year-old boys), the local static effort revealed simultaneous decreases in the reserve potentials of the SAS and AC, probably caused by fatigue and asthenization of these children during their schoolwork.     

Assimilation of rhythm by the isolated dog heart during gradual raising of stimulation frequency

An ability for a forestalling regulation of contractility of the heart with calculation of the tendency of rhythm increasing was revealed under a gradual increasing of heart rhythm. A forestalling regulation of heart contractility occurs with rhythm assimilation at the cell level of the heart and irrespective of the influence of Frank-Starling law and neurohumoral factors on the work of the heart. A 5-10% increasing of heart rhythm is characterized by optimal rhythm assimilation. A 15-40% increasing of heart rhythm is not optimal and results in transformation of the rhythm. The following sequence of events take place in the process of transition from rhythm assimilation to rhythm transformation under a gradual increasing of heart rhythm: rhythm assimilation--rhythm by mechanical function--incomplete rhythm assimilation by electrical function-transformation of rhythm by electrical function.     

Soliton-Like Regimes and Excitation Pulse Reflection (Echo) in Homogeneous Cardiac Purkinje Fibers: Results of Numerical Simulations

On the basis of numerical simulations of the partial McAllister-Noble-Tsien equations quantitatively describing the dynamics of electrical processes in conductive cardiac Purkinje fibers we reveal unusual – soliton-like – regimes of interaction of nonlinear excitation pulses governing the heart contraction rhythm: reflection of colliding pulses instead of their annihilation. The phenomenological mechanism of the reflection effects is that in a narrow (but finite) range of the system parameters the traveling pulse presents a doublet consisting of a high-amplitude leader followed by a low-amplitude subthreshold wave. Upon collisions of pulses the leaders are annihilated, but subthreshold waves summarize becoming superthreshold and initiating two novel echo-pulses traveling in opposite directions. The phenomenon revealed presents an analogy to the effect of reflection of colliding nerve pulses, predicted recently, and can be of use in getting insight into the mechanisms of heart rhythm disturbances.     

Early and late responses to oxidative stress in human dermal fibroblasts of healthy donors and rheumatoid arthritis patients. Relationship between the cell death rate and the genomic dosage of active ribosomal genes

A study was done regarding the effect of the oxidizing agent potassium chromate (K₂CrO₄, PC) on cultured dermal fibroblasts of a healthy donor and three patients with rheumatoid arthritis (RA). Characteristics of the rRNA gene (RG) complex—RG copy number, active RG (ARG) dosage, and 18S rRNA content—were determined for each cell line. In cells of the healthy donor, oxidative stress caused by low doses of PC (2–4 µM, 1–4 h) induced an early response, including a 50–80% increase in total RNA and rRNA. An appreciable activation of the nucleolus was observed cytochemically, by silver staining and morphometry. The early response grew considerably lower with the increasing passage number and/or PC concentration. Exposure to 6–12 µM PC for 24 h led to a progressively increasing cell death rate (late response). The existence and intensity of the early response correlated positively with cell survival during further culturing. Cells of the RA patients displayed almost no early response even at early passages: total RNA did not increase, and rRNA increased by no more than 10%. Cell disruption (apoptosis) during further culturing was more intense than in the line originating from the healthy donor. The apoptosis intensity characterized by the increase in the content of DNA fragments in the culture medium and in the caspase 3 activity was inversely proportional to the ARG dosage in the genome. The results provide the first quantitative characterization of the early and late responses of cells to PC-induced oxidative stress and suggest the role of ARG dosage in cell survival during stress.__________Translated from Molekulyarnaya Biologiya, Vol. 39, No. 2, 2005, pp. 264–275.Original Russian Text Copyright © 2005 by Veiko, Terekhov, Shubaeva, Smirnova, Ivanova, Egolina, Tsvetkova, Spitkovsky, Lyapunova.     

Current MUAC Cut-Offs to Screen for Acute Malnutrition Need to Be Adapted to Gender and Age: The Example of Cambodia

Background

Early identification of children <5 yrs with acute malnutrition is a priority. Acute malnutrition is defined by the World Health Organization as a mid-upper-arm circumference (MUAC) <12.5 cm or a weight-for-height Z-score (WHZ) <-2. MUAC is a simple and low-cost indicator to screen for acute malnutrition in communities, but MUAC cut-offs currently recommended by WHO do not identify the majority of children with weight-for-height Z-score (<-2 (moderate malnourished) or r<-3 (severe malnourished). Also, no cut-offs for MUAC are established for children >5 yrs. Therefore, this study aimed at defining gender and age-specific cut-offs to improve sensitivity of MUAC as an indicator of acute malnutrition.

Methods

To establish new age and gender-specific MUAC cut-offs, pooled data was obtained for 14,173 children from 5 surveys in Cambodia (2011–2013). Sensitivity, false positive rates, and areas under receiver-operator characteristic curves (AUC) were calculated using wasting for children <5yrs and thinness for children ≥5yrs as gold standards. Among the highest values of AUC, the cut-off with the highest sensitivity and a false positive rate ≤33% was selected as the optimal cut-off.

Results

Optimal cut-off values increased with age. Boys had higher cut-offs than girls, except in the 8–10.9 yrs age range. In children <2yrs, the cut-off was lower for stunted children compared to non stunted children. Sensitivity of MUAC to identify WHZ<-2 and <-3 z-scores increased from 24.3% and 8.1% to >80% with the new cut-offs in comparison with the current WHO cut-offs.

Conclusion

Gender and age specific MUAC cut-offs drastically increased sensitivity to identify children with WHZ-score <-2 z-scores. International reference of MUAC cut-offs by age group and gender should be established to screen for acute malnutrition at the community level.     

Psychophysiological Mechanisms of Writing Difficulties in Schoolchildren

The temporal and qualitative organization of writing movements was studied in six- to seven-year-old and nine- to ten-year-old right-handed and left-handed children with underdeveloped visuomotor coordination. The characteristic features of the temporal and qualitative organization of these movements at different stages of motor skill formation were found. Regarding the temporal structure of the series of writing movements, a pause was observed between individual movements in the series of motor task formation. The duration of this pause may serve as a criterion of the degree and efficiency of writing skill formation. The disturbance of the temporal structure of movements during the formation of handwriting speed at the initial stages of learning deteriorated the temporal organization of movements, drastically decreased the quality, and impeded the formation of the skill. The destructive processes were more pronounced in the case of accelerated handwriting in left-handed children and especially in children with underdeveloped visuomotor coordination.     

Fractal dynamics in circadian cardiac time series of corticotropin-releasing factor receptor subtype-2 deficient mice

Non-linear fractal analysis of circadian 24 hr heartbeat interval time series was performed in corticotropin releasing factor receptor-subtype 2 (CRFR2) deficient mice. We hypothesized that, as a result of its central as well as its peripheral expression, CRFR2 would mediate or interfere with the circadian rhythmicity. The dynamical properties of cardiac interbeat intervals were expected to be different between CRFR2 (+/+) and CRFR2 (–/–) mice when studied over an extended circadian 24 hr cycle. The dynamics of neurocardiac control were found to remain remarkably stable throughout the circadian cycle. In disagreement with the initial hypothesis, the dynamical properties underlying the cardiac control process were common to both CRFR2 (+/+) and CRFR2 (–/–) mice suggesting that control of heart rate does not rely on the elaborate interaction of the CRFR2-sensor and its intrinsic feedback arrangement. Lack of expression of CRFR2 would not compromise cardiac control and its dynamical output or is subserved by other, unknown mechanisms. Functional integrity of CRFR2 would not constitute an indispensable requirement of physiologic cardiac control. The circadian rhythm of heart rate is generated centrally and is independent of expression of CRFR2. While `normal' strain C57BL/6N mice exhibit a circadian dark/light cycle of heart rate, absence of circadian fluctuations in transgenic CRFR2-mice (both +/+ and –/–) and `normal' strain C57BL/6J mice points at the importance of other deficiencies that may be related to a common genetic background. Mutant mice that share a common 129SvJ- or C57BL/6J-derived genetic background may not present an optimal model for physiological studies of cardiovascular control.