Constant brain potentials as neurophysiological markers of autoimmune process]

Neuroimmune interactions in systemic rheumatic diseases were studied. The state of the central nervous system was assessed from the parameters of constant brain potentials, and the state of the immune system, from a complex of immunobiochemical parameters. The highest multiple correlation coefficients were revealed between the immunobiochemical parameters and the parameters of the constant brain potential, which characterize linear and standard deviations of potentials in temporal zones from potentials at other points of recording. The results are discussed in terms of structural and functional integration of the immune and nervous systems.     

Planktonic herbivorous food webs in the catalan Sea (NW Mediterranean): temporal variability and comparison of indices of phyto-zooplankton coupling based on state variables and rate processes

The structural properties and functional relationships betweenphyto- and zooplankton were studied during two cruises, FR92(October–November 1992) and ME93 (June 1993), at two fixedstations placed in a transect crossing the Catalan density front(NW Mediterranean), one located in the vicinity of the densityfront and another offshore. Both stations were sampled at variableintervals during each cruise in order to determine possibletendencies in the temporal changes in the phyto-zoo-planktoncoupling. This coupling (i.e. the matter and energy transferthrough planktonic herbivorous food webs) was estimated by meansof two categories of quantitative indicators: (i) structuralindices, based on the relationships between state variablesof producers and consumers; (ii) functional indices, based ontheir rate processes. Structural indices showed lower temporalvariability, both at a short time scale (within cruises) andinterannually (amongst cruises), than those based on rate processes.The values of both categories of indices at offshore stationscoincided for the two cruises, and were similar to the averagevalues for the whole area observed in previous cruises. At stationsnear the front, while structural indices suggested a more intensephyto-zooplankton coupling during FR92 (although differencesbetween cruises were not statistically significant), functionalindices indicated an opposite trend, being significantly higherduring ME93. The different functional indices allowed coincidenttendencies on the phyto-zooplankton coupling and seemed to respondfaster to any change in the relative importance of planktonicfood webs than structural ones. This suggests that the relativeimportance of planktonic herbivorous food webs can be betterestimated through the relationships between rate processes ofproducers and consumers, than through the relationships betweenmore conservative state variables, like biomass or communitystructure.     

The prognostic significance of the adaptation potential of the cardiovascular system in 10- and 11-year-old children

Experimental physiological studies were made in 10–11-year-old boys and girls, students of a gymnasium and an education-upbringing complex. The functional parameters recorded in children momentarily included: the heart rate, systolic and diastolic arterial pressure, Roufier index, and the adaptation potential (AP) of the cardiovascular system as an integral index of the adaptivity level of human organism on the whole, measured according to special formulas, and the index of the risk of disease development. Apart from it, the height, body mass, vital lung capacity, and strength of hand grip were measured, the puberty stage and deviations in the functioning of organs and systems were revealed. The AP levels used to evaluate adults’ adaptation did not agree with 10–11-year-old children’s physical development degree, puberty stages, and health condition (belonging to different health groups). No agreement was found between the levels of these parameters and the degrees of AP of the cardiovascular system in 10–11-year-old children based on their individual values and sigmal deviations of this index. Therefore, a conclusion on the adaptation capacities of a child’s organism and the risk of disease development in it based on the AP values may be erroneous. The authors suggest an age scale of the AP levels for 10–11-year-old children.     

Correlation of biophysical parameters of biologically active points and variations of heliogeophysical factors

The correlation between the parameters of biologically active points and the dynamics of solar activity was studied. Statistically significant correlations between electroconductivity of biologically active points and solar activity indices (sunspot number, Ap-index, solar radiowave flux) were revealed. The spectral analysis of the temporal organization of biologically active points revealed a set of periods present in the dynamics of solar activity. It was concluded that bioelectric system of the human organism is a complicated multilevel time-structure, which effectively reacts to changes in heliogeophysical dynamics. The bioelectric system of biologically active points is considered to be one of general information channels of electromagnetic nature, which realize the connection of organism with environment.     

The Tubifex tubifex assay for the determination of acute toxicity

An express (3-minute) test for acute toxicity determination by using the oligochaete annelid, Tubifex tubifex, is described. The EC50(Tubifex tubifex) [EC50(Tt)] for movement inhibition was calculated by using a concentration-response dependence. The reproducibility of the test was checked over several years and by several workers. Its applicability is limited to compounds which are soluble in water. The calculated EC50(Tt) indices correlate with LC50 values determined by using the fish, Pimephales promelas (96-hour assay), and with ICG50 values determined by using the ciliate, Tetrahymena pyriformis (48-hour assay) with high statistical significance (r = 0.822, n = 35, and r = 0.927, n = 80, respectively). The correlation between the EC50(Tt) indices and rat oral LD50 values (48-hour assay) was r = 0.519 (n = 67). The correlation within organic compounds was closer (r = 0.635, n = 60) than with the heterogeneous series of chemicals. A similar trend was noticed for the correlation with mouse oral LD50 values (r = 0.479, n = 56) with the heterogeneous series of chemicals, as compared that with the series without inorganic salts (r = 0.605, n = 42), and similarly with mouse intraperitoneal LD50 values, where r = 0.543 (n = 50) with the heterogeneous series of chemicals and r = 0.893 (n = 33) with the series of organic chemicals.     

Relationship between parameters of early growth in Israeli infants

A sample of 1931 Israeli infants was measured for body weight (WT), length (HT) and head circumference (HC) for approximately 2 years. The Count model with 3 parameters was chosen as the best fitting and most parsimonious function to approximate growth of all 3 studied traits. In the model parameter a relates to birth indices, b--to velocity of growth, and c--to rapid early childhood growth, or acceleration. Assuming a difference in growth patterns in the periods of different length, the whole sample was divided into 3 groups: 1) infants with last measurement around the age of 12 months; 2) infants with last measurement around the age of 18 months, and 3) infants with last measurement around the age of 24 months. The individuals measured up to 12 months were presented in all three groups. 27 curve fitting parameters, corresponding to 3 different follow-up intervals for WT, HT and HC were computed for each individual. A high correlation was detected between the a parameters regardless of time interval for 3 measured traits. A negative correlation was found between b and c parameters within the same time interval. A consistent positive correlation was indicated between a and b parameters, especially for body length and head circumference. A principal component analysis extracted five independent factors explaining 88.1% of the total variance. Three first factors retained parameters b and c, describing growth rate and pattern of each trait separately, namely, F1 was responsible for head circumference, F2 was a body length factor, F3 was a body weight factor. F4 extracted all birth indices, observed (HC0, HT0 and WT0) and expected (parameters a). The composition of principal factors allowed us to assume that there might be a strong involvement of a pleiotropic genetic source in determination of birth size traits and an independent genetic source controlling the pattern of growth for each trait separately.     

Examining stability of independent component analysis based on coefficient and component matrices for voxel-based morphometry of structural magnetic resonance imaging

Independent component analysis (ICA) on group-level voxel-based morphometry (VBM) produces the coefficient matrix and the component matrix. The former contains variability among multiple subjects for further statistical analysis, and the latter reveals spatial maps common for all subjects. ICA algorithms converge to local optimization points in practice and the mostly applied stability investigation approach examines the stability of the extracted components. We found that the practically stable components do not guarantee to produce the practically stable coefficients of ICA decomposition for the further statistical analysis. Consequently, we proposed a novel approach including two steps: (1), the stability index for the coefficient matrix and the stability index for the component matrix were examined, respectively; (2) the two indices were multiplied to analyze the stability of ICA decomposition. The proposed approach was used to study the sMRI data of Type II diabetes mellitus group and the healthy control group (HC). Group differences in VBM were found in the superior temporal gyrus. Besides, it was revealed that the VBMs of the region of the HC group were significantly correlated with Montreal Cognitive Assessment (MoCA) describing the level of cognitive disorder. In contrast to the widely applied approach to investigating the stability of the extracted components for ICA decomposition, we proposed to examine the stability of ICA decomposition by fusion the stability of both coefficient matrix and the component matrix. Therefore, the proposed approach can examine the stability of ICA decomposition sufficiently.     

Age-dependent cadmium accumulation in organs of intoxicated rats and changes of indices of acid-base balance of blood in different conditions of antioxidant defence

Age peculiarities of cadmium cumulation in the organs of rats under different conditions of antioxidants administration. Considerable hepato- and nefrotoxic effect of the given xenobiotic under different conditions of its supply into the organism was revealed. The strongly pronounced differences between the age distribution of cadmium in the organisms have been marked. It is proved that the most antioxidantal activity is shown by sodium selenite when administered into the organism before poisoning with cadmium. It is stated that the indices showing the acid-alkaline state are subject to the greatest changes in the bodies of young animals. In this case they have more expressed toxic effects under the influence of ions of heavy metals as well as the receptivity to the positive influence of antioxidants.     

Effect of naphthoquinones and tocopherols on the level of integral proteins in mitochondrial membranes and DNA levels in rat and rabbit tissue

Naphthoquinones and tocopherols are studied for their effect on the state of integral proteins of the mitochondrial liver and myocardium membranes in the experiments on the male rats and rabbits. It is established that deficiency of vitamins K and E in the organism (naphthoquinones and tocopherols) is followed by a decrease in the content of integral proteins and by disturbances in correlation of their fractions. These changes in K, E-avitaminosis are accompanied by a decrease of the DNA content in the tissues. Realization of K and E vitamins on the level of structural biomembrane organization is supposed to be possible.     

Selenium status and its correlates in a British national diet and nutrition survey: people aged 65 years and over.

Plasma selenium (Se) concentrations were measured in 1134 British people aged 65 years and over, living in mainland Britain during 1994-1995. Eight hundred and eighty-three lived in the community ("free-living"), while the remainder lived in institutions (residential and nursing homes). The overall mean plasma Se concentrations was 0.90 micromol/l (inner 95% range 0.50-1.36 micromol/l). Free-living people had significantly higher values than counterparts living in institutions, and there was an overall inverse correlation with age. Plasma Se varied with season (lower from October to December than at other times of the year), while values were higher in southern Britain than in the North. Socio-economic associations also existed (lower plasma Se in people receiving state benefits or with poorer educational attainment), while smokers had lower values than non-smokers. Several indices of poor health status or of medicine use were correlated with lower plasma Se, which was also predicted by several biochemical or haematological indices of infection or inflammation. Plasma Se was strongly and directly correlated with plasma albumin, zinc, cholesterol, vitamin C, several carotenoids, alpha-tocopherol, pyridoxal phosphate, and with blood haemoglobin and several anthropometric indices. All relationships were independent of age and gender, and are consistent with the view that plasma Se levels are higher in fit and well-nourished elderly people and lower in those who are frail, poorly-nourished and unwell. Whole-blood glutathione peroxidase generally did not share these relationships, was only very weakly correlated with plasma Se, and appeared to be less useful as a status indicator in this population group.     

Multivariate statistical analysis of tissue basophils in acute radiation sickness

By means of mark scale estimation method, discriminant and factor analyses, changes in integral indices on the state of mast cells in the rat mesentery have been investigated in dynamics of medullary, intestinal and cerebral forms of an acute radiation sickness. The integral indices are calculated basing on the morphometric parameters of the cells, that are obtained after the histological preparations are treated in a special automatic system for analysing images. At the medullary form of the acute radiation sickness, the greatest structural rearrangements of the mast cells take place during the first hours after the radiation, as well as during the climax of the disease, at the intestinal form, the analogous changes are revealed 1-3 days after the effect, and at the cerebral form--3 h after the radiation. The integral indices, calculated by means of the three methods, are well correlated with each other.     

Left ventricular diastolic function in diabetics

Left ventricular diastolic function was studied in 29 young diabetic patients (aged from 14 to 44 years) without any clinical sign of heart disease. The metabolic state, the presence and the degree of microvascular and neuropathic complications have been established. Age and sex matched 32 healthy subjects served as controls. The parameters of left ventricular diastolic function were determined by means of phonomechanocardiography. By this method in diabetic patients impaired diastolic function of the left ventricle was found. This alteration could be best characterized by the values of normalized relaxation index referring to the isovolumetric relaxation of the left ventricle. A close correlation was found between the microvascular and neuropathic complications and the left ventricular diastolic dysfunction, while no correlation could be demonstrated between the metabolic state and the diastolic cardiac disorder.     

Interresidual distance determination by four-pulse double electron-electron resonance in an integral membrane protein: the Na+/proline transporter PutP of Escherichia coli

Proximity relationships within three doubly spin-labeled variants of the Na+/proline transporter PutP of Escherichia coli were studied by means of four-pulse double electron-electron resonance spectroscopy. The large value of 4.8 nm for the interspin distance determined between positions 107 in loop 4 and 223 in loop 7 strongly supports the idea of these positions being located on opposite sides of the membrane. Significant smaller values of between 1.8 and 2.5 nm were found for the average interspin distances between spin labels attached to the cytoplasmic loops 2 and 4 (position 37 and 107) and loops 2 and 6 (position 37 and 187). The large distance distribution widths visible in the pair correlation functions reveal a high flexibility of the studied loop regions. An increase of the distance between positions 37 and 187 upon Na+ binding suggests ligand-induced structural alterations of PutP. The results demonstrate that four-pulse double electron-electron resonance spectroscopy is a powerful means to investigate the structure and conformational changes of integral membrane proteins reconstituted in proteoliposomes.     

Effect of synchronization of firings of different motor unit types on the force variability in a model of the rat medial gastrocnemius muscle

The synchronized firings of active motor units (MUs) increase the oscillations of muscle force, observed as physiological tremor. This study aimed to investigate the effects of synchronizing the firings within three types of MUs (slow—S, fast resistant to fatigue–FR, and fast fatigable–FF) on the muscle force production using a mathematical model of the rat medial gastrocnemius muscle. The model was designed based on the actual proportion and physiological properties of MUs and motoneurons innervating the muscle. The isometric muscle and MU forces were simulated by a model predicting non-synchronized firing of a pool of 57 MUs (including 8 S, 23 FR, and 26 FF) to ascertain a maximum excitatory signal when all MUs were recruited into the contraction. The mean firing frequency of each MU depended upon the twitch contraction time, whereas the recruitment order was determined according to increasing forces (the size principle). The synchronization of firings of individual MUs was simulated using four different modes and inducing the synchronization of firings within three time windows (± 2, ± 4, and ± 6 ms) for four different combinations of MUs. The synchronization was estimated using two parameters, the correlation coefficient and the cross-interval synchronization index. The four scenarios of synchronization increased the values of the root-mean-square, range, and maximum force in correlation with the increase of the time window. Greater synchronization index values resulted in higher root-mean-square, range, and maximum of force outcomes for all MU types as well as for the whole muscle output; however, the mean spectral frequency of the forces decreased, whereas the mean force remained nearly unchanged. The range of variability and the root-mean-square of forces were higher for fast MUs than for slow MUs; meanwhile, the relative values of these parameters were highest for slow MUs, indicating their important contribution to muscle tremor, especially during weak contractions.     

Correlations between forest stand diversity and landscape pattern in Otepää Nature Park, Estonia

Rank correlations between tree species diversity in forest stands and parameters of landscape pattern were calculated using data from 4933 locations in Otepää Nature Park. Stand diversity was characterised by the number of tree species in the stand formula and by the index of dominance of tree species’ coverage. Landscape diversity was characterised by locally calculated pattern parameters from three categorical map layers (1:10 000 base map, 1:10 000 soil map, combination of these maps) and from six numerical variables (elevation, slope angle, four channels of a Landsat 7 ETM image).A weak trend appeared for more diverse forest stands to be located in more diverse landscapes according to the base map. Forest stand diversity is also higher on steeper slopes and in places surrounded by slopes of varying steepness. The correlation between landscape diversity and biodiversity depends on the radius of the kernel in which landscape characteristics are calculated. Evidence of an indicative neighbourhood could be seen in many spatial relationships. The spatial correlation between stand diversity and indices calculated from the base map was most visible at distances ranging from 400 to 500 m; surface elevation and its variation correlates with stand diversity at distances of 100–200 m. Some relationships between forest diversity and landscape diversity that had a different sign of correlation in proximate and distant kernels can be interpreted as a need to standardise local landscape indices with the index values in a wider neighbourhood as a reference.     

The human body response to factors related to solar activity variations

The effect of nonstationary solar processes on human organism was studied. Daily measurements of electrical conductivity of 22 biologically active points on human skin, arterial pressure, and pulse frequency of 30 persons were performed, and their subjective sensations were registered. A comparative analysis of the data and variations in environment parameters, such as local A-index, atmospheric pressure, temperature, and indices of cosmic rays indicated a coincidence of their main periods. The conclusion is made that the reaction of the human organism on abrupt solar disturbances is biphasic and that there is a semiannual wave of synchronization of work of internal organs. The results are confirmed by simultaneous measurements in different cities.     

The pH dependence of the reductive carboxylation of pyruvate by malic enzyme

The maximum velocity of the malic enzyme (L-malate: NADP+ oxidoreductase (oxaloacetate-decarboxylating), EC 1.1.1.40) reductive carboxylation of pyruvate and V/KCO2 are pH-independent from pH 5.5 to pH 8.5. V/K for pyruvate exhibits pK values values of 6.50 +/- 0.25 and 7.25 +/- 0.25. These data suggest that the binding of pyruvate locks the protonation state of enzyme. In addition, the pK values are within experimental error identical for the pH dependence of V/Kmalate and V/Kpyruvate. Thus, the catalytic groups appear to have reverse protonation states in the two reaction directions. The ratio of (V/Kmalate)/(V/Kpyruvate) is 100, suggesting that the protonation state of enzyme is optimum in the malate oxidative decarboxylation direction. Thus, the group with a pK of about 6 is unprotonated and the group with a pK of 7.5 is protonated for malate decarboxylation, and the opposite is true for pyruvate reductive carboxylation.