The asymmetry of cerebral hemispheric activity in dogs in a state of quiet wakefulness under the action of sensory stimuli and food deprivation]

The EEG was recorded in four dogs from symmetrical cortical areas of the left and right brain hemispheres. Activation foci were determined by the maximal values of the mean frequency of EEG oscillations and coherence function. In the background experiments, the hemispheric activation asymmetry was observed in all dogs. The individual differences were in the frequency ranges, which were asymmetrically localized. In three dogs the coherence level was significantly more frequently higher in the right hemisphere than in the left one, in one dog the opposite relations were observed. These differences in activation foci localization were correlated with different tactics of choice between two feeders under conditions of free behavior. Under the action of external stimuli, changes in hemispheric activation were observed, predominantly, in the corresponding projection areas, and at the shifts of food excitability they were localized in symmetrical frontal areas. The results suggest that the left hemisphere becomes more activated during the first presentations of indifferent stimuli, i.e., during the development of the reaction to novelty, and under conditions of food deprivation, which rises the level of brain activation.     

Physical criteria of pathological processes. I. Change in the functional hemispheric asymmetry at various stages of rheumatic diseases]

The functional interhemispheric asymmetry of brain in patients with systemic rheumatic diseases was estimated by measuring brain direct current potentials. It is shown that different types of functional interhemispheric asymmetry correspond to different stages of systemic rheumatic diseases. At early stages, the left hemisphere asymmetry dominates, at expressed stages, the right hemisphere asymmetry is prevalent, and the terminal stage is characterized by the loss of functional interhemispheric asymmetry.     

Changes in pain sensitivity under increased atmospheric pressure]

It has been established that augmentation of air pressure from 0.1 to 1.1 MPa (with 0.1 MPa intervals) was accompanied in rats with the development of progressive analgesia which was measured according to the threshold of vocalization in the test of electrical stimulation of the tail. The highest analgesic response arose at 0.7-1.1 MPa. All the animals might be divided into two groups: group 1-72% of the animals with a 200% increase of the threshold, group 2--animals with such an increase by 15%. The augmentation of the pressure of heliox (79.1% of helium, 20.9% of oxygen) also caused analgesia, but not so strong. In patients pain thresholds to the mechanical nociceptive stimulation also increased by about 43-67% and 95-100% under the influence of increased air pressure of 0.4 and 0.7 MPa, respectively. In group 1 patients (67%) pain threshold increased by 50-100%, in group 2 by 15-25%. Pretreatment with naloxone (1 mg/kg), atropine (1 mg/kg), yohimbine (1 mg/kg), parachloramphetamine (5 mg/kg) and prasosin (1 mg/kg) decreased hyperbaric analgesia in rats by 41-56, 41-56, 17-19, 17-19%, respectively. The role of increased partial pressure of nitrogen in hyperbaric analgesia and possible neurochemical mechanisms of its realization are discussed.     

Changes in heart rate variability under informational loading]

Three-dimensional vector spaces were constructed by the method of principal components from large sets of cardiac rhythm spectra obtained in the state of rest and under informational load. The individual and group spaces of cardiac rhythm revealed three common factors having the maximal factor loads within the domain of action of metabolic (0.02-0.04 Hz), vascular (0.06-0.08 Hz), and respiratory (0.12-0.16 Hz) oscillators. Each particular cardiac spectrum in this universal autonomic space can be represented by a three-dimensional vector. Changes in the functional state are reflected in a specific trajectory of this vector in the space. It was found that coactivation of the metabolic, vascular, and respiratory oscillators in combination with a decrease in the heart rate and index of tension is positively correlated with efficiency of task performance and appears to reflect the orienting reflex. The vector autonomic space, in which the metabolic, vascular, and respiratory oscillators act, may be a useful instrument for distinguishing the mechanisms underlying the orienting and defensive reflexes.     

Changes in rat testis glandulocytes under deep hypothermia]

White mongrel rats weighing 180-220 g were daily cooled in water at 4-5 degrees C up to 21-23 degrees C in the rectum. The animals were killed on the 1, 5, 10, 15, 20 and 25th days of experiment. The total amount of glandulocytes counted per a cross section of the tubule did not change throughout the experiment. The total weight of pictures of 100 glandulocytes (taken randomly), obtained through a drawing apparatus on a standard paper was reliably decreased by 28%. By the end of the observation period the amount of degenerating glandulocytes increased 2 times and that of slightly active in a functional respect so-called "small" glandulocytes increased 4 times, while the number of active ("large") glandulocytes diminished approximately 1,5 times. The activity of SDG and ICDG in interstitial cells dropped by 26% and 18%. The activity of LDG was 52% greater. The G-6-PhDG activity was 40% greater while the activity of clue enzyme steroidgenase--3beta-OSD under hypothermia was inhibited by 36%.     

Changes in soil phosphorus fractions in a calcareous paddy soil under intensive rice cropping

We conducted a 4-year field experiment on a calcareous paddy soil in Zhejiang province of China to measure the changes in chemically extracted soil P fractions in an irrigated double-cropping rice system. Treatments included four fertilizer combinations (unfertilized control, NK, NP, and NPK) as main-plots and two rice cultivar types (inbred vs. hybrid rice) as sub-plots. Total plant P uptake and grain yield of rice declined in all treatments over time. Severe P-deficiency and significant rice yield losses began in treatments without P application after the second rice crop. Compared to inbred rice, hybrid rice increased grain yield (+18%), N uptake (+11%) and K uptake (+27%) but there was no significant difference in total plant P uptake. Recovery efficiencies of fertilizer-P averaged 31–32% in both cultivars. In treatments without P application, the P mass balance was negative (−6 to −8 kg P ha⁻¹ crop⁻¹) and phosphorus was drawn down in all inorganic P fractions, including resin, alkali- (NaHCO₃-Pi and NaOH-Pi) and acid-soluble P fractions (dilute HCl-P, concentrated HCl-P, residual-P). Only small amounts were removed from organic P fractions, 1–3 mg P kg⁻¹ year⁻¹ from NaHCO₃-Po and none from NaOH-Po. In treatments with fertilizer-P addition, the P mass balance was positive (+8 to 10 kg P ha⁻¹ crop⁻¹), soil P declined at a slower rate in inorganic P fractions and it increased (+51%) in the residual-P fraction. Hybrid rice generally caused greater depletion of inorganic soil P fractions than inbred rice, but there was no difference among cultivars in their effect on NaHCO₃-Po and NaOH-Po. Positive correlations (r = 0.63–0.81, P < 0.001) were observed between all inorganic P fractions (except residual-P) and total P uptake by rice. Our results suggest that rice plants draw P from a continuum of chemically extracted fractions that are assumed to have widely differing plant P availability. Regular P additions are required to maintain the effective soil P supply and differences between inbred and hybrid rice should be taken into account in P management strategies.     

The corpus callosum in primates: processing speed of axons and the evolution of hemispheric asymmetry

Interhemispheric communication may be constrained as brain size increases because of transmission delays in action potentials over the length of axons. Although one might expect larger brains to have progressively thicker axons to compensate, spatial packing is a limiting factor. Axon size distributions within the primate corpus callosum (CC) may provide insights into how these demands affect conduction velocity. We used electron microscopy to explore phylogenetic variation in myelinated axon density and diameter of the CC from 14 different anthropoid primate species, including humans. The majority of axons were less than 1 µm in diameter across all species, indicating that conduction velocity for most interhemispheric communication is relatively constant regardless of brain size. The largest axons within the upper 95th percentile scaled with a progressively higher exponent than the median axons towards the posterior region of the CC. While brain mass among the primates in our analysis varied by 97-fold, estimates of the fastest cross-brain conduction times, as conveyed by axons at the 95th percentile, varied within a relatively narrow range between 3 and 9 ms across species, whereas cross-brain conduction times for the median axon diameters differed more substantially between 11 and 38 ms. Nonetheless, for both size classes of axons, an increase in diameter does not entirely compensate for the delay in interhemispheric transmission time that accompanies larger brain size. Such biophysical constraints on the processing speed of axons conveyed by the CC may play an important role in the evolution of hemispheric asymmetry.     

Changes in lipid asymmetry and transport of glutathione conjugates under the influence of calcium ions in human erythrocytes

The influence of calcium ions on the distribution of the fluorescent analog of phosphatidylcholine 2-(6-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)hexanoyl-1-hexadecanoyl-sn-glycero-3-phosphocholine (C6-NBD-PC) in membranes and transport of glutathione-S-conjugates in human erythrocytes was studied. It was supposed that both processes were performed by the multidrug resistance protein. It was found that the increase in intracellular calcium concentration tended to both the redistribution of about 35% of C6-NBD-PC in the inner layer of the membrane and a decrease in the exit of glutathione-S-conjugates from erythrocytes. In both cases, the intracellular calcium concentration varied in the physiological (nanomolar) range. The results testify that Ca2+ participates in the regulation of the activity of the multidrug resistance protein.     

Changes in the ionization equilibrium of erythrocyte suspension under heating]

The effects of ionic strength, urea, calcium and fluorine ions, ouabain and cholinesterase inhibitors on the changes in the ionization equilibrium of an erythrocyte suspension under heating were studied. Proton release by erythrocytes was compared to a release of potassium ions and hemoglobin from the cells. The proton release under heating is mainly determined by the physico--chemical properties of superficial structures of erythrocytes and does not depend on the activity of cholinesterase, ATPase and glycolytic processes.     

Changes in N and P availability and P fractions in Iwo soil from Nigeria under intensive cultivation

Summary Two N-P factorial experiments, one on a site previously in bush fallow and the other previously in arable crops, were used to follow changes in the P status of Iwo soils under continuous cultivation. Marked yield response of maize to N was found at both sites, with the response being relatively small in the early crop at the fallowed site. Yield response to P was found only at the cropped site and then only if N was applied. About 25% of the organic P in the surface soil was mineralized during the two cropping periods of the rainy season which resulted in release of about 3 times as much P as was taken up by the maize. Most of the mineralized P as well as any added P was converted to Fe and Al-P. Apparently the rate of organic P mineralization in this soil is rapid enough for a few years following clearing to maintain adequate P activity for plant growth whereas N deficiency shows up very early. Lecturer, Department of Soil Science, University of Ife, Nigeria, and Professor of Soil Science, University of Wisconsin, Madison, Wisconsin, formerly Professor of Soil Science, University of Ife, respectively. Lecturer, Department of Soil Science, University of Ife, Nigeria, and Professor of Soil Science, University of Wisconsin, Madison, Wisconsin, formerly Professor of Soil Science, University of Ife, respectively.     

The bilateral asymmetry of the number of bristles in Drosophila occurring under the influence of methotrexate]

The data are analyzed on the bilateral asymmetry of the number of dorsal and scutellar chaeta observed under the action of methotrexate in Drosophila of wild strain. It was shown that the incidence of asymmetric specimens induced by methotrexate was abruptly increased as compared to the control. The asymmetry was found to have a statistically significant trend to left side both of the control and the variants of treatment. There was no sex difference revealed between targets of the asymmetry.     

Changes in rat liver mitochondria under conditions of bilateral subdiaphramatic vagotomy]

A study was made of the changes in the mitochondria of the rat liver under conditions of bilateral subphrenic vagotomy. Two stages in the dynamics of the response of the mitochondrial apparatus to denervation were distingished. During the first stage (0.5-3 days after vagotomy) there occurred reversible functional disturbances of the mitochondria caused by the postoperative stress. The second stage (7 to 60 days after the denervation) was charaterized by more marked structural-functional changes having a number od common features with those seen in hypoxia and being result of vagotomy proper.     

Vegetation asymmetry in Hawaii under the trade wind regime

Abstract. Interpretation of aerial photographs (1962–1965) revealed vegetation asymmetry on opposite valley slopes in the semi-arid to semi-humid zones of the island of Oahu. Field studies after 5 and 10 yr showed that this asymmetry is a transitional feature during recovery from disturbance (fire). The types of asymmetry ranged from difference in vigour of shrub canopies to total difference in floristic composition. Slopes exposed to the trade winds are typically characterized by grassy vegetation and landslides, whereas on the protected part of the upper west-facing slope immediately behind a ridge, vigorous shrubs and trees grow without any mechanical damage or deformation of crowns. This part of the slope is richer in species, including rare ones, than other parts. It is also characterized by the invasion of grasses from more exposed sites and the elongation of shrub canopies above the crest line. Different levels of exposure to exceptionally strong trade winds and salt spray at different parts of slopes seem to allow different speeds of recovery and thus contrasting vegetation structure and species composition. The existence of many shrub seedlings on the exposed upper slope suggests that succession is taking place and the vegetation asymmetry seems at least structurally to be a transitional feature.