Receptive fields of auditory cortical neurons in the cat

Receptive fields of auditory cortical neurons were studied by electrical stimulation of nerve fibers in different parts of the cochlea in cats anesthetized with pentobarbital. The dimensions of the receptive fields were shown to depend on the topographic arrangement of the neuron in the auditory cortex. The more caudad the neuron on the cortical projection of the cochlea in the primary auditory cortex, the more extensive its receptive field. The receptive fields were narrowest in the basal turn of the cochlea and were symmetrical with respect to their center. It is suggested that the region of finest discrimination of acoustic stimuli in cats is located in the basal region of the cochlea, i.e., in that part of its receptor system which has the narrowest receptive field and is represented by significantly more (than the middle and apical regions of the cochlea) nerve cells in the primary auditory cortex [1].A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 13, No. 5, pp. 467–473, September–October, 1981.     

Transport of Rb+ via activated sodium channels of clone N 18 phi 1 neuroblastoma cells

A study was made of the Rb+ transport via activated sodium channels of clone N 18 phi 1 neuroblastoma cells cultured in the Eagle medium with 10% bovine serum. The time of population doubling was about 10 h. The cell differentiation was induced by adding bromdeoxyuridine in a concentration of 1-4 10(-5) M. The cells contained 172 +/- 12 and 340 +/- 35 micrograms of protein per 10(6) cells at the logarithmic growth phase and in differentiated state, respectively. It is shown that veratrin produced a 1.3-fold increase in the rate of 86Rb+ removal from undifferentiated cells and 2.5-fold increase in that from differentiated cells. Tetrodotoxin removed completely the effect of veratrin. A conclusion is made on the presence of a new clone of fast sodium channels in cell membranes.     

Study of the Compression Dynamics of a Fiber Liner with a Deuterated Target Mounted on the Axis

Plasma Physics Reports - Compression of a fiber array with a deuterated target mounted on its axis is studied at the Angara-5-1 facility (3.5 MA, 100 ns). Cylindrical arrays with an initial...     

Magnetic core-shell nanoparticles for drug delivery by nebulization

Background

Aerosolized therapeutics hold great potential for effective treatment of various diseases including lung cancer. In this context, there is an urgent need to develop novel nanocarriers suitable for drug delivery by nebulization. To address this need, we synthesized and characterized a biocompatible drug delivery vehicle following surface coating of Fe₃O₄ magnetic nanoparticles (MNPs) with a polymer poly(lactic-co-glycolic acid) (PLGA). The polymeric shell of these engineered nanoparticles was loaded with a potential anti-cancer drug quercetin and their suitability for targeting lung cancer cells via nebulization was evaluated.

Results

Average particle size of the developed MNPs and PLGA-MNPs as measured by electron microscopy was 9.6 and 53.2 nm, whereas their hydrodynamic swelling as determined using dynamic light scattering was 54.3 nm and 293.4 nm respectively. Utilizing a series of standardized biological tests incorporating a cell-based automated image acquisition and analysis procedure in combination with real-time impedance sensing, we confirmed that the developed MNP-based nanocarrier system was biocompatible, as no cytotoxicity was observed when up to 100 μg/ml PLGA-MNP was applied to the cultured human lung epithelial cells. Moreover, the PLGA-MNP preparation was well-tolerated in vivo in mice when applied intranasally as measured by glutathione and IL-6 secretion assays after 1, 4, or 7 days post-treatment. To imitate aerosol formation for drug delivery to the lungs, we applied quercitin loaded PLGA-MNPs to the human lung carcinoma cell line A549 following a single round of nebulization. The drug-loaded PLGA-MNPs significantly reduced the number of viable A549 cells, which was comparable when applied either by nebulization or by direct pipetting.

Conclusion

We have developed a magnetic core-shell nanoparticle-based nanocarrier system and evaluated the feasibility of its drug delivery capability via aerosol administration. This study has implications for targeted delivery of therapeutics and poorly soluble medicinal compounds via inhalation route.     

Electrotonic and action potentials in the Venus flytrap

The electrical phenomena and morphing structures in the Venus flytrap have attracted researchers since the nineteenth century. We have observed that mechanical stimulation of trigger hairs on the lobes of the Venus flytrap induces electrotonic potentials in the lower leaf. Electrostimulation of electrical circuits in the Venus flytrap can induce electrotonic potentials propagating along the upper and lower leaves. The instantaneous increase or decrease in voltage of stimulating potential generates a nonlinear electrical response in plant tissues. Any electrostimulation that is not instantaneous, such as sinusoidal or triangular functions, results in linear responses in the form of small electrotonic potentials. The amplitude and sign of electrotonic potentials depend on the polarity and the amplitude of the applied voltage. Electrical stimulation of the lower leaf induces electrical signals, which resemble action potentials, in the trap between the lobes and the midrib. The trap closes if the stimulating voltage is above the threshold level of 4.4 V. Electrical responses in the Venus flytrap were analyzed and reproduced in the discrete electrical circuit. The information gained from this study can be used to elucidate the coupling of intracellular and intercellular communications in the form of electrical signals within plants.     

Texture formation in DNA films with alkali metal chlorides

The formation of textures in DNA films with LiCl, NaCl, KCl, RbCl, and CsCl salts has been studied. The films are prepared by evaporation of water solution with highly polymerized calf thymus DNA and excess salt of specific type. For DNA solution with 10 mM concentration of NaCl, KCl, and RbCl the films with dendritic textures have been obtained, whereas in case of CsCl the textures in the films appear only at 30 mM concentration of excess salt in the initial solution. In the solution with LiCl, the textures in DNA films have not been observed within the whole range of concentration of excess salt under consideration. The analysis of parameters of DNA films with different salts has showed that evaporation of solution leads to crystallization of salt ions on DNA macromolecule and formation of DNA‐salt complexes. Electrostatic energy of the system of crystalline ordered ions and charges of DNA chains has been estimated to study the stability of DNA‐salt complexes. The results obtained for different salts have been showed that the presence of DNA macromolecule enhances crystallization as compared with solution without DNA. The property of excess salt to form the crystalline structures has been found to decrease in the following order: KCl > NaCl > RbCl > CsCl > LiCl. The results of estimation are in good agreement with the experimentally observed dependence of texture formation on excess salt type. © 2013 Wiley Periodicals, Inc. Biopolymers 99: 508–516, 2013.     

Mitochondrial DNA polymorphism of atlantic cod of the Barents and White seas

High level of intraspecific polymorphism of the mtDNA cytochrome b gene in the Atlantic cod Gadus morhua L. from the northeastern part of the species range (Barents and White seas) is detected. The absence of genetic differentiation between the samples from different areas of the Norwegian and Barents seas is shown, and the fact that these samples belong to the same population of Northeast Arctic cod is confirmed. Significant differences in the frequences of mitochondrial DNA haplotypes between the cod from the Barents and White seas, as well as from the northwestern part of the range, are found. The cod Gadus morhua kildinensis Derjugin, 1920 from Mogilnoye Lake and Gadus morhua marisalbi Derjugin, 1920 from the White Sea were revealed to have common haplotypes with the cod from the Barents Sea, confirming the recent origin of these forms from the Atlantic cod G. morhua.