Dynamics of spectral characteristics of theta- and alpha-range EEG during negative emotional reactions]

Power characteristics of the EEG theta and alpha rhythms were studied in a human in neutral state and during a conditioned negative emotional reaction (Fp1, Fp2, F3, F4, C3, C4, P3, P4, O1, O2, F7, F8, T3, T4, T5, and T6 derivations). A significant increase in the relative spectral power in the narrow theta band of 7.4-8.1 Hz in the frontocentral and temporal brain regions was observed during the development of the negative emotional reaction. The alpha-rhythm dynamics during the negative reaction was substantially individual and could be expressed in either an increase, or decrease in relative spectral power of different alpha-frequencies. No pronounced changes in their dynamics could also be observed. In some subjects the spectral power of the medium-frequency alpha-rhythm significantly decreased, that of the high-frequency rhythm increased, and changes in the spectral power of the low-frequency alpha range varied.     

Identification of type-II alveolocytes in cryostatic sections of human lungs

The tannic acid-polychromic stain method (Mason et al., 1985) designed for the identification of the cultured alveolar type II cells has been adapted to cryostat sections of human lungs. Both biopsy and autopsy specimens obtained within one hour post mortem could be effectively processed with this method to visualize at the light microscope level the lamellar bodies, i.e. characteristic intracellular inclusions of alveolar type II cells.     

Benzodiazepine receptors in the mammalian central nervous system

A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 2, pp. 269–279, March–April, 1988.     

Individual optimization: Mechanisms shaping the optimal reaction norm

In general, optimal reaction norms in heterogeneous populations can be obtained only by iterative numerical procedures (McNamara, 1991; Kawecki and Stearns, 1993). We consider two particular, but biologically plausible and analytically tractable cases of individual optimization to gain insight into the mechanisms which shape the optimal reaction norm of fecundity in relation to an environmental variable or an individual trait. In the first case, we assume that the quality of the environment (e.g. food abundance) or the quality of the individual (e.g. body size) is fixed during its entire life; it may also be a heritable individual trait. In the second case, individual quality is assumed to change randomly such that the probability distribution of quality in the next year is the same for the parent and for her offspring. For these two cases, we obtain analytical expressions for the shape of the optimal reaction norm, which are heuristically interpretable in terms of underlying selective mechanisms. It is shown that better quality may reduce the optimal fecundity. This outcome is particularly likely if better quality increases a fecundity-independent factor of parental survival in a long-lived species with fixed quality. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of magnesium ions on heat denaturation of DNA

The dependence of animal DNA denaturation on magnesium ion concentration has been studied in the range (10(-6)--10(-1) M with sodium ion content of 10(-3) and 10(-2) M. Special attention has been given to the effect of multivalent metallic impurities bound to DNA. An increase of DNA thermal stability has been shown to occur in the magnesium concentration rage of 10(-6)--10(-4) M. At concentrations exceeding 10(-3) M the T M begins to decrease. The dependence of the DNA melting range on magnesium ion concentration has a maximum at approximately 10(-5) M Mg2+. At low magnesium and sodium ion concentrations a strong asymmetry of the melting curves has been observed. This effect can be described in terms of the melting theory for DNA complexed with small molecules and is explained by magnesium ion redistribution from the denatured portions of DNA to native ones. The method for calculation of melting curves in the DNA-ligand system has been proposed. Studies of thermal denaturation parameters have been shown to be an effective method for the estimation of binding constants of ligands to native and denatured DNA.     

Effects of allapinin on sodium currents in isolated neurons of the trigeminal ganglia and cardiomyocytes of rats

Block of sodium currents by allapinin (diterpene alkaloid with strong antiarrhythmic properties) was investigated in isolated, voltage clamped rat trigeminal neurons and cultured neonatal rat single ventricular myocytes. Allapinin produces a decrease in sodium current amplitude without any changes in voltage dependent properties. Possible differences between the mechanisms of antiarrhythmic effect of diterpene alkaloids and classic antiarrhythmic agents have been analysed.     

Studies of calcium ion binding to poly A

Ultraviolet differential spectra of poly A we studied in the presence of Ca2+ ions with 10(-3)M Na+ in the solution. At concentrations lower than 10(-3)M Ca2+, the ions bind to phosphate groups of the single helical polymer, thus increasing its degree of helicity. At higher concentrations, the ions start binding to the bases of poly A, producing aggregates whose effective radius, as found with an electric microscope, is not more than 10(2) A. These particles stack to form aggregates of an order-of-magnitude higher size. The mutual orientation of bases in the poly A aggregates is of a high degree of order. The calculation of concentration dependences of Ca2+-poly A binding constants shows that this process is cooperative.