Changes in myelin structure and fatty-acid tail ordering upon nerve fiber excitation

Using laser interference microscopy and Raman spectroscopy of frog myelinated nerve, it has been found that upon a train of action potentials passing along the fiber, the phase height (refractive index) of paranodal myelin declines while the ordering of fatty-acid tails therein increases. In contrast, at the node of Ranvier where excitation is generated, both the phase height of the axoplasm and the ordering of axolemmal lipid tails decline. It is supposed that such changes in myelin are caused by desorption of membrane-bound Ca²⁺.     

Electrical feedback in the chemical synapses

Electrical feedback in chemical synapses and the efficacy of synaptic transmission grow with the increase in the gap resistance, so they should be higher in invaginated synapses than in the flat ones. So the plastic changes in the invagination depth may provide a morphological basis for long-term changes in synaptic efficacy: long-term potentiation (LTP) in brain and retinal synapses. In retinal photoreceptor triad synapses, the electrical feedback can provide an "operational" (instantaneous) control of synaptic transmission.     

Selection of the medium for the simultaneous synthesis of an antibiotic, protease and pigment by a Nocardia fructiferi culture

Using method of mathematical planning of experiment the culture medium ensuring the simultaneous intensive production of ristomycin, protease and violet pigment by Nocardia fructiferi has been worked out.     

The role of the state of protein-lipid interactions in stimulated membranes in the conformation of C40-carotenoids

It was shown by Raman spectroscopy that conformation of carotenoid in the frog nerve membranes at rest and at propagation of rhythmic excitation depends on the state of protein-lipid interaction modified by exposition of the nerve in solution with trypsin, alpha-chymotrypsin, urea, glutaraldehyde, SH-reagents, isopropanol and system "Fe-ascorbate". It is suggested that the level of the protein-lipid interactions in excitable membranes with the intramembrane potential determines C40-carotenoid conformation at the propagation of rhythmic excitation by he nerve.     

Subcellular reorganization of cardiomyocytes during and after temporary experimental hypothermic circulatory arrest

Ultrastructure of cardiomyocytes of the left ventricle has been studied in dogs during the experiments, performed with a general external cooling, prolonged circulatory arrest, as well as during long term periods after the operation. In the experiment without cooling it is not possible to restore hemodynamics after 30 min of total ischemia. In cardiomyocytes severe, sometimes irreversible lytic lesions are registered. Opposite to this, by the end of one hour's cardiac arrest under total cooling up to 24-22 degrees C, changes in ultrastructure of cardiomyocytes are minimal. This is proved by a stabilizing action of hypothermia to membranous, fibrillar and even labile granular cellular components. More manifested changes occur in cells after restoration of the cardiac activity and worming, though even at this stage certain morphological signs of partial restoration of synthetic processes are noted. By the third day after the operation ultrastructure of cardiomyocytes is fully normalized at an essential hypertrophy and hyperplasia of protein synthesis organels and lysosomes. Thus, under conditions of aperfusional hypothermia (24-22 degrees C) and cardiac arrest, produced with pharmacological cooling, cardiomyocytes safely survive one hour's total ischemia, presenting their ability to intracellular regeneration in full.     

Microfluorometric study of pH in frog nerves at rest and during rhythmic stimulation]

With the use of microspectrofluorimetry the pH-dynamics in the frog nerve at rest and during rhythmic excitation was investigated. Rhythmic excitation results in an increase of hydrogen ion concentration in the nerve fibres. Metabolic and ion channel inhibitors affect intracellular pH changes. The results obtained suggest different role of various transport systems (sodium pump and ion channels) in the regulation of pH at rest and during rhythmic excitation.     

Raman spectroscopy of the "potential sensor" of potential-dependent channels.

Raman spectroscopy (RS) study shows that the "potential sensor" responds to changes in intramembrane potential by conformational changes. The mechanism of regulation of the channel "gate" by the carotenoid potential sensor is discussed.