Effects of voluntary control of the functional state on the organization of cortical processes during mnemenic activity in schoolchildren aged nine to ten years

In schoolchildren aged nine to ten years, the analysis of EEG indices (spectral power density, the function of coherence in the α band) of different cortex regions in four experimental situations—quiet wakefulness, mnemenic activity, relaxation, and mnemenic activity in the postrelaxation period—was performed. In the mnemenic activity situations, a task for determining the short-term auditory-speech memory span was used. A positive effect of relaxation on the efficiency of mnemenic activity expressed in an increase in the short-term memory span was found. Comparison of groups formed according to the increase in the memory span showed differences in the dynamics of coherence indices. Only in children with a pronounced postrelaxation increase in the memory span in the situation of mnemenic activity was an increase in coherence in the high-frequency subrange of the α band of the EEG detected, whose functional significance is related to selective inhibition.     

Neurophysiological indices of CNS plasticity in the course of treatment of head trauma in adolescents

Using the methods of quantitative EEG analysis and cognitive evoked potentials, we investigated delayed consequences of head trauma (HT) after nootropic therapy with cerebrolysin. The study was performed in 30 12-to 19-year-old adolescents who had had severe HT with brain contusion one to five years prior to the study and manifested asthenic symptoms. During the study, they underwent treatment with 30 daily intramuscular injections of cerebrolysin at a dose of 0.1 ml/kg body weight. A positive effect on the functional state of the brain was found in 77% of patients. It was expressed as the appearance of the occipital α rhythm in the EEGs, an increase in the EEG spectral power, normalization of frequency parameters of the α rhythm, a decrease in the power spectrum of the low-frequency θ and δ EEG activity, and shortening of the P300 peak latency. These changes were associated with an improvement of the general clinical state and the psychometric indices of attention and memory in the patients.     

System analysis of heart rate variability,hemodynamics, and bioelectrical activity of the human brain at moderate altitudes

Heart rate variability (HRV), hemodynamics, cerebral α rhythm, and systemic relations between them have been investigated in 35 normal human subjects at the age of 37.2 ± 3.8 years. The results of comprehensive clinical, functional and instrumental HRV investigation, electroencephalography (EEG) using 21 monopolar electrodes, and blood pressure (BP) monitoring were embodied in mathematical models that describe the relations of these parameters, multiple regression equations, and generated 3D diagrams. It has been found that a relative increase in the LF range and a decrease in HF one are accompanied by elevations of BP. The EEG α amplitude has been depressed, and α index has decreased. The HRV reduction and modification of the α rhythm structure have been demonstrated to affect the BP values. These data indicate interactions and close relations between the autonomic and central nervous systems and BP.     

A pair of inhibitory neurons are required to sustain labile memory in the Drosophila mushroom body

Labile memory is thought to be held in the brain as persistent neural network activity. However, it is not known how biologically relevant memory circuits are organized and operate. Labile and persistent appetitive memory in Drosophila requires output after training from the α'β' subset of mushroom body (MB) neurons and from a pair of modulatory dorsal paired medial (DPM) neurons. DPM neurons innervate the entire MB lobe region and appear to be pre- and postsynaptic to the MB, consistent with a recurrent network model. Here we identify a role after training for synaptic output from the GABAergic anterior paired lateral (APL) neurons. Blocking synaptic output from APL neurons after training disrupts labile memory but does not affect long-term memory. APL neurons contact DPM neurons most densely in the α'β' lobes, although their processes are intertwined and contact throughout all of the lobes. Furthermore, APL contacts MB neurons in the α' lobe but makes little direct contact with those in the distal α lobe. We propose that APL neurons provide widespread inhibition to stabilize and maintain synaptic specificity of a labile memory trace in a recurrent DPM and MB α'β' neuron circuit.     

Structure activity relationships for central and peripheral alpha adrenergic activities of imidazoline derivatives.

The α adrenergic agonistic activity of a number of imidazolines was measured on the α adrenergic receptors of the isolated rabbit intestine. A number of imidazolines were full agonists having an intrinsic activity constant equal to 1 in relation to noradrenaline as a standard. Some other derivatives had only partial agonist activity. The affinities of the imidazolines for these adrenergic receptors was assessed using pD₂ values. The pD₂ values were correlated with a number of physicochemical parameters of the drugs, i.e. pK_a, the molar volume and the apparent and true partition coefficients (APC and TPC respectively) by stepwise regression analysis.Results indicate that pD₂ was correlated with pK_a primarily, whereas molar volume also was a factor determining agonistic activity at the peripheral α adrenergic receptor.Central α adrenergic receptor stimulating properties of the imidazolines were determined by measuring bradycardia induced by these agents after intrahypothalamic injection into rats. Although it was not possible to correlate central α adrenergic activity with any of the physicochemical parameters due to the lack of action of a number of imidazolines, results show that structural requirements for central α adrenergic activity clearly differ from those for peripheral α adrenergic activity.These data are discussed in view of the mechanism of action of the antihypertensive imidazoline clonidine.     

Preference of oxygenation between α and β subunits of haemoglobin: Results of multidimensional spectroscopic observation

The distribution of oxygen between the subunits of haemoglobin was studied spectrophotometrically. The difficulty in discriminating the spectral changes upon oxygen binding to the α or β subunit can be surmounted by means of multidimensional spectroscopic observations and a correlation analysis of the data. M-type abnormal haemoglobins are used as a control against normal haemoglobin because only one type of its subunits can bind oxygen.A multidimensional spectroscopic measuring system, which has been developed in our laboratory, makes it possible to carry out simultaneous and continuous acquisition of a set of spectroscopic data at several wavelengths on one sample solution during the course of increasing or decreasing the partial pressure of oxygen. The data-storing function of a magnetic disk memory provides enough precision for a rigorous investigation of the correlation of oxygen equilibrium curves measured at several wavelengths. No chemical modification to enhance the spectral difference between subunits is necessary.In conclusion, by detecting slight differences between the oxygenation-sensitive bands of α and β subunits, the β subunits are found to have a higher affinity for oxygen than the α subunits.     

Use of the regression of mean crowding on mean density for estimating sample size and the transformation of data for the analysis of variance

An approximate method for estimating the sample size in simple random sampling and a systematic way of transformation of sample data are derived by using the parameters α and β of the regression of mean crowding on mean density in the spatial distribution per quadrat of animal populations (Iwao , 1968). If the values of α and β have been known for the species concerned, the sample size needed to attain a desired precision can be estimated by simply knowing the approximate level of mean density of the population to be sampled. Also, an appropriate variance stabilizing transformation of sample data can be obtained by the method given here without restrictions on the distribution pattern of the frequency counts.     

Influence of Tonal Modulation in a Melodic Line on the Spectral Parameters of Human EEG

The influence of tonal modulation in pieces of music on the EEG parameters was studied. An EEG was recorded while subjects were listening to two series of fragments with modulations: controlled harmonic progressions and the fragments of classical musical compositions. Each series included modulations to the subdominant, the dominant, and the ascending minor sixth. The highly controlled and artistically impoverished harmonic progressions of the first series contrasted with the real music excerpts in the second series, which differed in tempo, rhythm, tessitura, duration, and style. Listening to harmonic progressions and musical fragments produced event-related synchronization in the α frequency band. Real musical fragments with modulation to the dominant generated lower synchronization in the α band as compared with other modulations. A lower decrease of synchronization in the α frequency band after listening was observed in the case of fragments of classical music compared with harmonic progressions.     

Changes in Sphingomyelinase Activity,Tumor Necrosis Factor α Level,and Lipid Peroxidation Intensity in the Course of Development of Cholestatic Liver Injury

Changes in sphingomyelinase activity, tumor necrosis factor α expression, and level of lipid peroxidation products in the course of development of cholestatic liver injury have been studied. The same type phase shifts in the analyzed parameters were observed, which included a marked decrease at the early stages of cholestasis (days 3–6) and a pronounced increase at the later stages (days 12–16), i.e., under the conditions of developed pathology. There was a significant positive linear correlation between tumor necrosis factor α expression, sphingomyelinase activity, and lipid peroxidation intensity in cholestatic injury. We propose that detected changes may reflect the balance between the effects of the two major bile components—bilirubin, which is accumulated in the liver at the early stages of cholestasis, and bile acids, whose influence dominates at the later stages of pathologic process. Our results indicate that tumor necrosis factor α overexpression, sphingomyelin cycle activation, and lipid peroxidation intensification may cause apoptosis of hepatocytes at the late stages of cholestasis.     

Tyrosine phosphorylation of vinexin in v-Src-transformed cells attenuates the affinity for vinculin

Vinexin is an adaptor-type focal adhesion protein that interacts with vinculin. Here, we report the tyrosine phosphorylation of vinexin α in v-Src-transformed NIH3T3 cells. Point mutational analysis of vinexin α clarified that three tyrosine residues in vinexin α were phosphorylated. A non-phosphorylatable mutant of vinexin α had higher binding affinity for vinculin than its wild-type counterpart. In conclusion, vinexin α is tyrosine phosphorylated in v-Src-transformed cells, and this tyrosine phosphorylation of vinexin α attenuates the association of vinexin α with vinculin.     

Studies on the induction of mitotic gene conversion by ultraviolet irradiation: I. Analysis of dose-frequency relationship

The UV (270-nm) dose-frequency relationship for the induction of intragenic mitotic recombination at trp5 locus in Saccharomyces cerevisiae was non-linear. Two parameters, α and a, in the proposed equation for the non-linear relationship f = (at)α were determined so as to fit the experimental data by the method of least squares. The analysis was extended over 5 cell stages during synchronous growth. It was found that (1) parameter α changed from 2.02 for unbudded small cells to 1.09 for the stage where the cell had finished the division of the nucleus, and (2) parameter a changed correspondingly from 7.25·10⁻⁴ to 0.180·10⁻⁴ sec⁻¹ during the same period.One interesting outcome in this analysis was the deduction of a dose-dependent nature of relative sensitivity with respect to the stage. The determination of these two parameters enabled us to calculate dose-effect relationships beyond the limits of experimental restrictions. Such an “imaginary” relationship, calculated at an extremely low dose, revealed the existence of maximal sensitivity around the DNA synthesis period. It was further shown that this maximum would easily be masked even in the moderate dose range. Thus, we conclude that the validity of single dose comparisons is diminished unless α is constant regardless of the cell stage. Some considerations on the proposed parameters have been made in relation to the mechanisms of the induction of gene conversion by UV.     

Studies on pituitary follitropin. II. Isolation and characterization of the subunits of the ovine hormone.

The α and β subunits of highly potent ovine follitropin have been isolated by dissociation in 8 m urea, pH 7.5, and chromatography on DEAE-Sephadex A25. The isolated subunits display microheterogeneity on polyacrylamide gel electrophoresis and have very low activity in follitropin-specific radioreceptor and radioimmunoassays. The tryptophan fluorescence spectra of native follitropin and the isolated β subunit are different. The recombinant of follitropin α + β subunit had the same activity as the native hormone in the radioimmunoassay, but its activity in the radioreceptor and in vivo bioassay was about 65% of the intact hormone. Substitution of the follitropin α by ovine lutropin α subunit (prepared by a method not involving urea) to form the recombinant restored full activity in all the three assays investigated. The formation of recombined hormone proceeds at a rapid rate and is almost complete by 6 h. The α and β subunits of ovine follitropin differ from each other in amino acid composition. No significant differences were apparent in their carbohydrate composition. The amino acid composition of the ovine follitropin α and lutropin α subunits are very similar. The oxidized α subunit has phenylalanine at its NH₂-terminus while aspartic acid is present at this position in the oxidized β subunit.     

Interhemispheric Differences in Indices of α Activity Spectral Power Electroencephalogram during Bicycle Ergometry

An EEG study during bicycle ergometry in the prone position with the load growing stepwise to submaximal heart rate was carried out in 30 volunteers in order to investigate the spectrum parameters and interhemispheric differences in α activity on the encephalogram. Comparative analysis of EEG data showed a statistically significant increase in α power indices in both hemispheres at the final stage of aerobic exercise and in the course of recovery period with the highest power values recorded in the left hemisphere. Analysis of interhemispheric differences demonstrated right-hemisphere activation during the entire period of the research.     

Dependence of the energy lifetime on the type of anomalous losses in stellarators

A relatively simple model of transport process in stellarators that was proposed earlier by the author on the basis of neoclassical theory makes it possible to determine the density and temperature profiles of the plasma components, the ambipolar electric field profile, and the particle and energy lifetimes from the given device parameters and given particle and energy sources with allowance for anomalous losses. The results of numerical simulations carried out with this model for the L-2M, ATF, CHS, and LHD stellarators over broad ranges of plasma densities and absorbed powers showed that the plasma energy lifetimes in these devices coincide to within factors on the order of two with those found from empirical scalings. A specific model of anomalous losses was chosen for calculations. Results are presented from simulations with a more general form of the anomalous thermal conductivity. Namely, the thermal conductivity is chosen to be K _j ^(a) ≈ N ^α T _j ^β B ₀ ^?γ , where N(r) is the plasma density and T _j (r) is the temperature of the jth plasma component (j = e, i). The parameters α, β, and γ are set equal to α = 1, β = 2, and γ = 1; α = 0.5, β = 2.5, and γ = 1; α = 1.5, β = 2, and γ = 2; α = 1, β = 2.5, and γ = 2; and α = 1.5, β = 2.5, and γ = 2. The simulations have been done for the L-2M and LHD stellarators. It is found that, in all the five models, the calculated energy lifetimes τ _c are essentially independent of the functional form of the anomalous thermal conductivity and coincide to within a factor on the order of two with those following from the LHD scaling.     

EEG markers of the stabilotraining effect during the rehabilitation of patients with posttraumatic Korsakoff’s syndrome

Nine patients with posttraumatic Korsakoff syndrome (KS) were examined before and after a rehabilitation course of feedback stability training (ST) using EEG, posturographic and clinical tests (with the FIM and Mayo Portland scales used for estimation). During 7 to 12 sessions, the patients tried to perform static and motor tasks. A group of 18 healthy subjects were examined to provide standard parameters. The results demonstrated a disturbed spatiotemporal EEG pattern in patients with KS before ST in the form of a reduced coherence for short derivation pairs (intrahemispheric, interhemispheric, and diagonal ones) in frontal and parietooccipital areas. Analysis of specific EEG rhythms demonstrated the maximum decrease in coherence in the α band (with the aforementioned regional specificity) and for long diagonal pairs (between the left frontal and right parietooccipital areas). The ST course was accompanied by KS regression (according to clinical scales and posturographic study); an original increase in EEG coherence, especially that of α waves, was recorded in the occipitoparietal and central frontal areas of the right hemisphere; a subsequent increase in coherence of the frontal areas in both hemispheres was observed. Late after the ST course, further positive changes were characteristic of the EEG spatiotemporal pattern. However, comparison with standard data suggested incomplete recovery of various coherence parameters: hypertrophied coherence in intrahemispheric pairs and still reduced values in interhemispheric derivations. This EEG pattern suggested incomplete KS regression, which was confirmed by clinical data.     

Hidden prenatal malnutrition in the rat: role of β₁-adrenoceptors on synaptic plasticity in the frontal cortex

Moderate reduction in the protein content of the mother's diet (hidden malnutrition) does not alter body and brain weights of rat pups at birth, but leads to dysfunction of neocortical noradrenaline systems together with impaired long-term potentiation and visuo-spatial memory performance. As β?-adrenoceptors and downstream protein kinase signaling are critically involved in synaptic long-term potentiation and memory formation, we evaluated the β?-adrenoceptor density and the expression of cyclic-AMP dependent protein kinase, calcium/calmodulin-dependent protein kinase and protein kinase Fyn, in the frontal cortex of prenatally malnourished adult rats. In addition, we also studied if β?-adrenoceptor activation with the selective β? agonist dobutamine could improve deficits of prefrontal cortex long-term potentiation presenting these animals. Prenatally malnourished rats exhibited half of β?-adrenoceptor binding, together with a 51% and 65% reduction of cyclic AMP-dependent protein kinase α and calcium/calmodulin-dependent protein kinase α expression, respectively, as compared with eutrophic animals. Administration of the selective β? agonist dobutamine prior to tetanization completely rescued the ability of the prefrontal cortex to develop and maintain long-term potentiation in the malnourished rats. Results suggest that under-expression of neocortical β?-adrenoceptors and protein kinase signaling in hidden malnourished rats functionally affects the synaptic networks subserving prefrontal cortex long-term potentiation. β?-adrenoceptor activation was sufficient to fully recover neocortical plasticity in the PKA- and calcium/calmodulin-dependent protein kinase II-deficient undernourished rats, possibly by producing extra amounts of cAMP and/or by recruiting alternative signaling cascades.     

Biophysical regulations of NEE light response in a steppe and a cropland in Inner Mongolia

Aims Ecosystem carbon models often require accurate net ecosystem exchange of CO₂ (NEE) light-response parameters, which can be derived from the Michaelis–Menten equation. These parameters include maximum net ecosystem exchange (NEE max), apparent quantum use efficiency (α) and daytime ecosystem respiration rate (R e). However, little is known about the effects of land conversion between steppe and cropland on these parameters, especially in semi-arid regions. To understand how these parameters vary in responses to biotic and abiotic factors under land conversions, seasonal variation of light-response parameters were evaluated for a steppe and a cropland of Inner Mongolia, China, during three consecutive years (2006–08) with different precipitation amounts.Methods NEE was measured over a steppe and a cropland in Duolun, Inner Mongolia, China, using the eddy covariance technique, and NEE light-response parameters (NEE max, α and R e) were derived using the Michaelis–Menten model. Biophysical regulations of these parameters were evaluated using a stepwise regression analysis.Important findings The maximum absolute values of NEE max occurred in the meteorological regimes of 15°C ≤ T a < 25°C, vapor pressure deficit (VPD) < 1 KPa and 0.21 m 3 m ? 3 ≤ volumetric soil water content at 10 cm (SWC) < 0.28 m 3 m ? 3 for both the steppe and the cropland ecosystems. The variations of α and R e showed no regular variation pattern in different T air, VPD and SWC regimes. Under the same regime of T air, VPD and SWC, the cropland had higher absolute values of NEE max than the steppe. Canopy conductance and leaf area index (LAI) were dominant drivers for variations in NEE light-response parameters of the steppe and the cropland. The seasonal variation of NEE light-response parameters followed the variation of LAI for two ecosystems. The peak values of all light-response parameters for the steppe and the cropland occurred from July to August. The values of NEE light-response parameters (NEE max, α and R e) were lower in the driest year (2007). Seasonally averaged NEE light-response parameters for the cropland surpassed those for the steppe. Land conversion from steppe to cropland enhanced NEE light-response parameters during the plant growing period. These results will have significant implications for improving the models on regional NEE variation under climate change and land-use change scenarios.     

Ablation of primary afferent terminals reduces nicotinic receptor expression and the nociceptive responses to nicotinic agonists in the spinal cord

A variety of studies indicate that spinal nicotinic acetylcholine receptors modulate the behavioral and autonomic responses elicited by afferent stimuli. To examine the location of and role played by particular subtypes of nicotinic receptors in mediating cardiovascular and nociceptive responses, we treated neonatal and adult rats with capsaicin to destroy C-fibers in primary afferent terminals. Reduction of C-fiber terminals was ascertained by the loss of isolectin B4, CGRP and vanilloid receptors as monitored by immunofluorescence. Receptor autoradiography shows a reduction in number of epibatidine binding sites following capsaicin treatment. The reduction is particularly marked in the dorsal horn and primarily affects the class of high affinity epibatidine binding sites thought to modulate nociceptive responses. Accompanying the loss of terminals and nicotinic binding sites were significant reductions in the expression of α 3, α 4, α 5, β 2 and β 4 nicotinic receptor subunits in the superficial layers of the spinal cord as determined by antibody staining and confocal microscopy. The loss of nicotinic receptors that follows capsaicin treatment results in attenuation of the nociceptive responses to both spinal cytisine and epibatidine. Capsaicin treatment also diminishes the capacity of cytisine to desensitize nicotinic receptors mediating nociception, but it shows little effect on intrathecal nicotinic agonist elicited pressor and heart rate responses. Hence, our data suggest that α 3, α 4, α 5, β 2 and β 4 subunits of nicotinic receptors are localized in the spinal cord on primary afferent terminals that mediate nociceptive input. A variety of convergent data based on functional studies and subunit expression suggest that α 3 and α 4, in combination with β 2 and α 5 subunits, form the majority of functional nicotinic receptors on C-fiber primary afferent terminals. Conversely, spinal nicotinic receptors not located on C-fibers play a primary role in the spinal pathways evoking spinally coordinated autonomic cardiovascular responses.     

Polymorphic Alleles of the Gene for the β Chain of Rabbit Haemoglobin

THE primary structure of the haemoglobin chains from individuals of many species is not unique. The α chain of rabbit haemoglobin has six positions at which more than one amino-acid occurs¹. Such amino-acid multiplicities have also been found for the α chain of mouse^2,3, goat⁴ and horse⁵ haemoglobin and for the γ chain of human haemoglobin⁶. In some cases a simple mechanism can be put forward to explain the variability, as for the human γ chain⁶ and the mouse α chain³, where the presence of tandem genes seems to be established. Three of the variable positions of the α chain of rabbit haemoglobin can be explained as resulting from polymorphic alleles of a single α chain gene⁷.