Dynamic Mapping of the Temperature Fields of the Brain

The thermal fields and biopotentials of the brain were studied in 11 healthy subjects in the states of quiet wakefulness and sleep (stages I–IV). To this end, a new method of dynamic radiomapping was applied in parallel with the traditional method of EEG recording. The method of dynamic radiomapping is based on measuring the brain thermal radiation in the decimeter (40 cm) wave range. It allows the integral brain temperature to be recorded from deep inside and up to 2.5 cm from the surface with the help of 12 antennas applied to the skin. The temperature of the cerebral cortex of the human subject in the state of quiet wakefulness varied stochastically in the range of deviations of ±0.3°C in all areas. Changes in the brain functional state, i.e., the transition from wakefulness to sleep, were accompanied by either an increase in the variation range to ±0.5°C or the appearance of stationary foci of heating (by 0.9–1.3°C) or cooling (by –0.7°C) of individual locations and amplitudes.     

Role of Monoamine Oxidase Type A and B on the Dopamine Metabolism in Discrete Regions of the Primate Brain

The role of monoamine oxidase (MAO) type A and B on the metabolism of dopamine (DA) in discrete regions of the monkey brain was studied. Monkeys were administered (–)-deprenyl (0.25 mg/kg) or clorgyline (1.0 mg/kg) or deprenyl and clorgyline together by intramuscular injections for 8 days. Levels of DA and its metabolites, dihydroxy phenylacetic acid (DOPAC) and homovanillic acid (HVA) were estimated in frontal cortex (FC), motor cortex (MC), occipital cortex (OC), entorhinal cortex (EC), hippocampus (HI), hypothalamus (HY), caudate nucleus (CN), globus pallidus (GP) and substantia nigra (SN). (–)-Deprenyl administration significantly increased DA levels in FC, HY, CN, GP and SN (39–87%). This was accompanied by a reduction in the levels of DOPAC (37–66%) and HVA (27–79%). Clorgyline administration resulted in MAO-A inhibition by more than 87% but failed to increase DA levels in any of the brain regions studied. Combined treatment of (–)-deprenyl and clorgyline inhibited both types of MAO by more than 90% and DA levels were increased (57–245%) in all brain regions studied with a corresponding decrease in the DOPAC (49–83%) and HVA (54–88%) levels. Our results suggest that DA is metabolized preferentially, if not exclusively by MAO-B in some regions of the monkey brain.     

Brain metabolic effects of acute nicotine

(–)Nicotine acetylcholine receptors are located on both nerve cell bodies and synaptic terminals, are permeable to calcium, and function perhaps predominantly by facilitating the release of neurotransmitters and neuropeptides. The behavioral rewards from (–)nicotine and perhaps addiction appear to be related to dopamine release. ³¹P NMR analysis reveals subcutaneously administered (–)nicotine produces acute alterations in brain membrane phospholipid and high-energy phosphate metabolism of Fischer 344 rats. These metabolic responses to (–)nicotine could contribute to nicotine's behavioral effects.     

Modification of [3H]MK801 Binding to Rat Brain NMDA Receptors after the Administration of a Convulsant Drug and an Adenosine Analogue: A Quantitative Autoradiographic Study

Specific [³H]MK801 binding to rat brain NMDA receptors after the administration of the convulsant drug 3-mercaptopropionic acid (MP) and the adenosine analogue cyclopentyladenosine (CPA) was studied by means of a quantitative autoradiographic method. MP administration (150 mg/kg, i.p.) caused significant decreases in [³H]MK801 binding in several hippocampus subareas and layers, mainly in CA1 and CA3 at seizure (11–27%) and postseizure (8–16%) and in cerebral occipital cortex at seizure (18–22%). In nucleus accumbens, a rise was observed at postseizure (44%) and a tendency to increase at seizure (24%). CPA (2mg/kg, i.p.) decreased ligand binding in hippocampus (CA1, CA2, CA3) (17–22%) and in occipital cerebral cortex (18–24%). When CPA was administered 30 minutes before MP (which delayed seizure onset) and rats were sacrified at seizure, decreases in [³H]MK801 binding in several layers of CA1 and CA3 of hippocampus (11–27%) and in CA1, CA2, CA3 (24–35%) after CPA+MP postseizure, and an increase in CA2 after CPA and CPA+MP postseizure (20–34%), were observed. A drop was found in the occipital subarea (18–24%) after CPA and in the frontal and occipital subarea after CPA+MP postseizure (24–34%) while no changes were observed in any treatment involving the other cerebral cortex regions, thalamic nuclei, caudate putamen and olfactory tubercle. These results show that [³H]MK801 binding changes according to drug treatment and the area being studied, thus indicating a different role in seizure activity.     

Unit responses in the anterior zone of the suprasylvian gyrus to peripheral stimuli of different modalities

Unit responses in the anterior zone of the suprasylvian gyrus to visual, electrodermal, and acoustic stimulation were investigated in experiments on unanesthetized cats immobilized with tubocurarine. Electrical activity was recorded from 131 units, 121 of which were spontaneously active. In 65.5% of cells responses consisted of a short or long increase or a decrease in intensity of spike activity. Most cells (58.2%) were monosensory. Responses to visual stimulation were given by 72% of neurons, to electrodermal by 61.6%, and to acoustic by 9.3%. The corresponding latent periods were 20–40, 20–30, and 15–20 msec. Responses of the same neurons to different peripheral stimuli were uniform or they differed in their dynamics. Intracellular recording gave responses in the form of EPSPs (amplitude 4–5 mV, duration 60–80 msec) or, rarely, IPSPs (amplitude 2–3 mV, duration 160–200 msec). The functional organization of the associative cortex and mechanisms of analysis of incoming afferent information are discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 4, No. 4, pp. 368–374, July–August, 1972.     

Influence of aging in the thermoregulatory efficiency of man

Studies were carried out to evaluate the effect of aging on the thermoregulatory efficiency in man. The efficiency of thermoregulatory system was assessed on the basis of tolerance to acute cold stress, Tromp test and cold induced vasodilatation (CIVD) response. The experiments were done in 9 groups (15 each) of human volunteers in the age ranges of 20–25, 26–30, 31–35, 36–40, 41–45, 46–50, 51–55, 56–60 and 61–70 years. They were made to relax in a thermoneutral laboratory (27 ± 1C) for one hour; thereafter their resting heart rate, blood pressure, oxygen consumption, oral, mean skin, mean body and peripheral temperatures were measured. Then they were exposed to cold (10C) in a cold chamber wearing shorts and vests for two hours. The above parameters and shivering responses were recorded at 30 min intervals during cold exposures. On other occasions, their thermoregulatory efficiency test (Tromp Test) and cold induced vasodilatation response were also studied in the same thermoneutral laboratory. The results showed comparatively poor cold tolerance and thermoregulatory efficiency in elderly people. The middle aged category (above 40 years) showed a gradual reduction in the thermoregulatory efficiency, but highly significant reduction was noticed in those who exceeded sixty years of age.     

Stress-Induced Tau Phosphorylation in Mouse Strains with Different Brain Erk 1 + 2 Immunoreactivity

Quantitative blot immunolabeling techniques were used to compare the effect of cold water stress (CWS) on the phosphorylation of brain tau protein in two strains of C57BL/6J mice: ob/ob and ob/+. CWS induced immediate, significant (4–6 fold) and continuous accumulation of Alzheimer's like forms of tau phosphorylated at Ser 202. The effect was considerably (150–200%) higher in ob/ob mice compared to ob/+ mice. By contrast, the unphosphorylated tau immunoreactivity decreased after the CWS, whereas no changes were detected in the abundance of several other antigens. The level of anti Erk 1 + 2 immunoreactivity corresponding to 36–37 kDa polypeptide was 2–3 fold higher in ob/ob than in ob/+ mice. No strain differences were detected in the abundance of several other protein kinases. Obtained results support the hypothesis that Erk 1 or 2 like protein kinase may be involved in the restructuring of neuronal cytoskeleton in response to environmental stress.     

Effects of Ellagic Acid by Oral Administration on N-Acetylation and Metabolism of 2-Aminofluorene in Rat Brain Tissues

Numerous studies have demonstrated that the Acetyl Coenzyme A-dependent arylamine NAT enzyme exist in many tissues of experimental animals including humans, and that NAT has been shown to be exist in mouse brain tissue. Increased NAT activity levels are associated with increased sensitivity to the mutagenic effects of arylamine carcinogens. Attenuation of liver NAT activity is related to breast and bladder cancer processes. Therefore, the effects of ellagic acid (EA) on the in vitro and in vivo N-acetylation of 2-aminofluorene (AF) were investigated in cerebrum, cerebellum and pineal gland tissues from male Sprague-Dawley rats. For in vitro examination, cytosols with or without EA (0.5–500 M) co-treatment decreased 7–72%, 15–63% and 10–78% of AF acetylation for cerebrum, cerebellum and pineal gland tissues, respectively. For in vivo examination, EA and AF at the same time treated groups with all 3 examined tissues did show significant differences (the changes of total amounts of AF and AF metabolites based on the Anova analysis) when compared to the ones without EA cotreatment rats. The pretreatment of male rats with EA (10 mg/kg) 24 hr prior to the administration of AF (50 mg/kg) (one day of EA administration suffice to induce large changes in phase II enzyme activity) resulted in a 76% decrease in total AF and metabolites in pineal gland but did not show significant differences in cerebrum and cerebellum tissues. This is the first demonstration to show that EA decreases the N-acetylation of carcinogens in rat brain tissues.     

Dynamics of auditory cortical unit responses of the waking cat during defensive conditioning to acoustic stimulation

In chronic experiments on cats unit responses of the primary auditory cortex (area 50) were studied by microelectrode recording during defensive conditioning to sound. During formation of the reflex biphasic responses with relatively short-latency (50–100 msec) and longer-latency (400–500 and 800–900 msec) activation predominated. Neighboring neurons, whose activity was recorded by the same microelectrode, also were involved more intensively in activity. Application of a differential stimulus in 70% of cases produced definite changes in unit activity, among which responses of activation type predominated. Analysis of the course of spike responses of the same neuron during the period of action of a large number of combinations and its comparison with the formation of the conditioned-reflex motor response revealed no direct correlation between these events.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 11, No. 2, pp. 99–108, March–April, 1979.     

Rhizosphere priming effects on the decomposition of soil organic matter in C4 and C3 grassland soils

Using a natural abundance ¹³C method, soil organic matter (SOM) decomposition was studied in a C₃ plant – `C<sub>4</sub> soil' (C<sub>3</sub> plant grown in a soil obtained from a grassland dominated by C<sub>4</sub> grasses) system and a C<sub>4</sub> plant – `C₃ soil' (C₄ plant grown in a soil taken from a pasture dominated by C₃ grasses) system. In C₃ plant – `C<sub>4</sub> soil' system, cumulative soil-derived CO<sub>2</sub>–C were higher in the soils planted with soybean (5499 mg pot<sup>–1</sup>) and sunflower (4484 mg pot<sup>–1</sup>) than that in `C₄ soil' control (3237 mg pot^–1) without plants. In other words, the decomposition of SOM in soils planted with soybean and sunflower were 69.9% and 38.5% faster than `C<sub>4</sub> soil' control. In C<sub>4</sub> plant – `C₃ soil' system, there was an overall negative priming effect of live roots on the decomposition of SOM. The cumulative soil-derived CO₂–C were lower in the soils planted with sorghum (2308 mg pot^–1) and amaranthus (2413 mg pot^–1) than that in `C<sub>3</sub> soil' control (2541 mg pot<sup>–1</sup>). The decomposition of SOM in soils planted with sorghum and amaranthus were 9.2% and 5.1% slower than `C₃ soil' control. Our results also showed that rhizosphere priming effects on SOM decomposition were positive at all developmental stages in C₃ plant – `C<sub>4</sub> soil' system, but the direction of the rhizosphere priming effect changed at different developmental stages in the C<sub>4</sub> plant – `C₃ soil' system. Implications of rhizosphere priming effects on SOM decomposition were discussed.     

Allozymic variation of the endangered killifishAphanius iberus and its application to conservation

Synopsis Genetic differentiation and patterns of variability in the endangered Iberian endemic,Aphanius iberus, were analyzed by allozyme electrophoresis as a valuable database for conservation purposes. Genetic variability values expressed as heterozygosity (H = 0.015–0.097) were close to the values found in other members of Cyprinodontidae (H = 0.012–0.123). Polymorphism values (P = 0.125–0.542) were higher than reported in the literature (P = 0.036–0.150) for Cyprinodontidae. Significant correlation existed between salinity values and genetic variability expressed as heterozygosity (r = – 0.76, p < 0.01) and polymorphism (r = – 0.60, p = 0.04). Low genetic variability values (H = 0.024–0.055, P = 0.125–0.292) were exhibited by populations which inhabit salty lagoons. The highest values were found in populations occurring in marshes and irrigation channels (H = 0.051–0.097, P = 0.250–0.542). Associations among genetic, geographic and ecological parameters were tested using a Mantel test indicated that most of the genetic distances were explained by geographic distances but not by ecological factors, suggesting that isolation by distance could be the main factor explaining the differentiation between sites. According to the genetic distances obtained, two mainA. iberus groups were discernible: the Atlantic and Mediterranean. Genetic distances between both groups (DRogers = 0.179–0.261) were higher than values between recognized species of other cyprinodontids (DRogers = 0.11–0.27). On the basis of genetic distances we have dated the fragmentation of both populations to the Upper Miocene-Pliocene when most of the Mediterranean sea dried up. Subsequently, gene flow between Mediterranean and Atlantic populations was interrupted. The results of our genetic analyses suggested the existence of five operational conservation units (OCUs) forA. iberus. These units are defined as a continuous area limited by geographical boundaries, and inhabited by one or more populations sharing the same genetic pattern.     

Early Effects of Neonatal Rat Desympathization on Secondary Heart Rhythms

Neonatal Wistar rats for the first 3 weeks of life were injected intraperitoneally with isobarine every other day. The single doze was 40 mg/kg. Control animals were injected with saline. Degenerative changes in sympathetic ganglia were evident as early as in the 10-day old animals and increased by 18–19 days. The heart rate in the desympathized animals was lower than in control from 10–11 to 18–19 days, but by the end of the 3rd week the differences were eliminated. The same occurred with respiration rate. At same terms there was an essential decrease of amplitude of the heart rate high-frequency fluctuations synchronous with respiration and of the periodogram slow waves with the period about 1 min. Using the method of fast Fourier transform, the power spectra of heart rate fluctuations (secondary heart rhythms) in 5 frequency ranges (0–0.01, 0.01–0.03, 0.03–0.1, 0.1–1.0, and 1.0–2.5 Hz) were calculated. Desympathization leads to a decrease of the fluctuation power in all ranges, but in the ultralow-frequency range this decrease is the least pronounced, which suggests the presence of non- sympathetic mechanisms in their genesis. The greatest changes occur in the middle-frequency area. In all cases, differences from control values increase from the 10–11th to the 18–19th days, after which a tendency for restoration is observed, in spite of an enhancement of processes of degeneration of sympathetic neurons. This indicates an activation of the compensatory mechanisms, due to which consequences of desympathization are partially smoothed at distant terms of studies.     

Conduction of excitation in the cat visual system

Unit responses in area 17 of the visual cortex to stimulation of the lateral geniculate body and optic tract were studied in experiments on unanesthetized cats immobilized with D-tubocurarine. Of the neurons tested, 53.6% responded to stimulation of the lateral geniculate body. In 92% of these cells the responses were orthodromic with latent periods of between 2 and 12.5 msec. Most cells responded with latent periods of 2.0–2.5, 3.0–3.5, and 4.0–4.5 msec, corresponding to latent periods of the components of the electropositive wave of the primary response. Antidromic responses to stimulation of the lateral geniculate body were given by 8% of neurons. The difference between the latent periods of responses of the same visual cortical neurons to stimulation of the optic tract and lateral geniculate body was 0.1–1.8 msec, but for most neurons (55.8%) it was 0.5–1 msec. The histograms of response latencies of visual cortical neurons to stimulation of the above-mentioned formations were found to be similar. It is concluded that the optic radiation contains three principal groups of fibers with conduction velocities of 28.5–16.6, 11.7–8.9, and 7.4–6.0 m/sec, respectively.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 7, No. 6, pp. 589–596, November–December, 1975.     

Effect of response inhibition in cat motor cortex neurons during the expectation of conditioning stimulus

The spike responses of the motor cortex neurons (area 4) associated with forelimb movement were studied in awake cats earlier trained to perform placing motor reactions. Responses produced by the same neurons were compared in two situations: 1) when a sound-click conditioning stimulus (CS) was applied in isolation; 2) when a CS followed a preliminary warning stimulus (WS), a light flash, with a 100–1000 msec delay. During the reflex initiation by combined action of the WS and CS, response components that occurred prior to the placing movement (PM) performance under isolated CS action weakened and arrived 50–150 msec later; yet, response components that appeared in the same situation simultaneously with PM onset or later remained unchanged. PM latent periods were not changed when WS was applied. The temporal interval between WS and CS was characterized by depression of neuronal activity; depression duration was determined by the interstimulus delay. It is conceivable that the described transformations in spike responses of cortical neurons occurred due to changes in the sensory direction of the animal's attention; this direction, in all cases, is a crucial factor in the formation of neuronal activity in the cortex.Translated from Neirofiziologiya, Vol. 25, No. 1, pp. 21–27, January–February, 1993.t     

Different Metabolic Effects of Ganglioside GM1 in Brain Synaptosomes and Phagocytic Cells

The metabolic effects of ganglioside GM1 were found to be quite different in brain synaptosomes and phagocytic cells. Incubation of rat brain cortex synaptosomes with GM1 was shown to decrease the production of reactive oxygen species induced by Fe²⁺-H₂O₂ system and measured by chemiluminometric method in the presence of luminol. Gangliosides GM1, GD1a, and GT1b significantly diminished the induced accumulation of lipid peroxidation product in brain synaptosomes, but protein kinase inhibitor (polymyxin B) abolished this effect. Incubation with antioxidants or GM1 significantly diminished the increase of ⁴⁵Ca²⁺ influx and oxidative inactivation of Na⁺,K⁺-ATPase in brain synaptosomes exposed to glutamate, the effect of GM1 was concentration-dependent in the range 10^–11–10^–8 M. But the incubation of human neutrophils and mouse peritoneal macrophages with 10^–11–10^–10 M GM1, on the contrary, increased several times the luminol-dependent chemiluminescence response of these cells to activation by low concentrations of 12-myristate-13-acetate phorbol ester. The opposite effects of GM1 in the nerve endings and phagocytic cells seem to be protective in both cases as the inhibition of reactive oxygen species production in the nerve cells may enhance their viability in damaged brain, while the intensification of their production in phagocytic cells may promote the resistance of organism to infection.     

Ionic mechanisms of the fast (nicotinic) phase of the acetylcholine response of identified Planorbarius corneus neurons

Responses to electrophoretic application of acetylcholine and suberyldicholine were investigated in identified neurons (LPed-2 and LPed-3) isolated from the left pedal ganglion ofPlanorbarius corneus. When microelectrodes filled with potassium chloride were used the reversal potentials of responses to acetylcholine and suberyldicholine were less negative than when microelectrodes filled with potassium sulfate were used; these reversal potentials were shifted toward depolarization if chloride ions in the medium were replaced by sulfate. These facts indicate that the responses in both LPed-2 and LPed-3 depend on chloride ions. Reversal potentials for acetylcholine and suberyldicholine in LPed-3 were virtually identical (–51 and –50 mV respectively), but in LPed-2 they differed significantly (–46 and –62 mV respectively). Replacement of sodium ions by Tris ions shifted the reversal potential for acetylcholine in LPed-2 toward hyperpolarization but did not change the reversal potential for suberyldicholine. Benzohexonium had the same action. The reversal potential for acetylcholine in medium with a reduced sodium concentration or in the presence of benzohexonium was the same as for suberyldicholine. It is concluded that on neuron LPed-2 acetylcholine activates both acetylcholine receptors which control conductance for chloride ions and acetylcholine receptors which change conductance for sodium ions, whereas suberyldicholine acts only on acetylcholine receptors responsible for the chloride conductance of the membrane.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 12, No. 5, pp. 533–540, September–October, 1980.     

Nodularin in feathers and liver of eiders (Somateria mollissima) caught from the western Gulf of Finland in June–September 2005

Nodularins are cyanobacterial hepatotoxins, which may cause intoxication at very low exposure levels. The nodularin-producing cyanobacterium Nodularia spumigena usually forms massive blooms in much of the Baltic Sea during the summer season. Breast feathers and liver samples from common eider (Somateria mollissima) were analysed for nodularins by liquid chromatography–mass spectrometry (LC–MS) and enzyme-linked immunosorbent assay (ELISA). Fifteen eiders from the western Gulf of Finland were caught by hunters between June and September 2005. Blue mussels (Mytilus edulis), a dietary component of the birds, were also obtained by diving near the same marine area and time as the collection of the ducks. Eider breast feathers contained 6–52 μg nodularin-R (Nod-R)/kg dry weight (dw) by ELISA, and 8–43 μg Nod-R/kg dw by LC–MS. No Nodularia filaments were adhered to feather samples according to light microscopy assessment. Liver samples from the same individuals contained Nod-R between 3 and 48 μg/kg dw by LC–MS. Mussel samples from the area contained Nod-R at concentrations of 12–80 μg/kg dw by LC–MS. Analysis of bird feathers offers a facile and non-invasive means of assessing the exposure of birds to nodularins.     

Influence of soil water potential on respiration and nitrogen fixation ofAzotobacter vinelandii

Summary Respiration and N₂-fixation (acetylene reduction) ofAzotobacter vinelandii have been studied at a variety of soil water potentials. Both processes were strictly linked and strongly reduced at water potentials between –0.6 and –1.3 MPa. Complete inhibition occurred below –2.1MPa. Osmotic potentials in soil compared to matric potentials of the same value were less inhibitory to respiration and acetylene reduction by Azotobacter. The N₂-fixing efficiency (mg N/g glucose) was not influenced by water potentials ranging from –0.1 to –2.1 MPa.