Showing papers by "Moscow State University published in 1982"

The role of lipid peroxidation in pathogenesis of ischemic damage and the antioxidant protection of the heart.

Abstract: A working hypothesis on pathogenesis of ischemic heart damage has been proposed. According to this hypothesis, a crucial role in conversion of reversible damage into irreversible damage is played by cardiomyocyte membrane destruction caused by the so-called “lipid triad”. The latter comprises activation of lipid peroxidation, activation of phospholipases, and the degergentlike action of excessive amounts of free fatty acids and lysophospholipids. Marked activation of lipid peroxidation in experimental myocardial infarction, as well as reoxygenation following transitory ischemia, have been demonstrated. The proposed hypothesis and experimental data underly successful application of synthetic free radical scavengers (antioxidants) for heart protection against experimental myocardial infarction, transitory ischemia, and emotional, painful stress.

Centrioles in the cell cycle. I. Epithelial cells.

Abstract: A study was made of the structure of the centrosome in the cell cycle in a nonsynchronous culture of pig kidney embryo (PE) cells. In the spindle pole of the metaphase cell there are two mutually perpendicular centrioles (mother and daughter) which differ in their ultrastructure. An electron-dense halo, which surrounds only the mother centriole and is the site where spindle microtubules converge, disappears at the end of telophase. In metaphase and anaphase, the mother centriole is situated perpendicular to the spindle axis. At the beginning of the G1 period, pericentriolar satellites are formed on the mother centriole with microtubules attached to them; the two centrioles diverge. The structures of the two centrioles differ throughout interphase; the mother centriole has appendages, the daughter does not. Replication of the centrioles occurs approximately in the middle of the S period. The structure of the procentrioles differs sharply from that of the mature centriole. Elongation of procentrioles is completed in prometaphase, and their structure undergoes a number of successive changes. In the G2 period, pericentriolar satellites disappear and some time later a fibrillar halo is formed on both mother centrioles, i.e., spindle poles begin to form. In the cells that have left the mitotic cycle (G0 period), replication of centrioles does not take place; in many cells, a cilium is formed on the mother centriole. In a small number of cells a cilium is formed in the S and G2 periods, but unlike the cilium in the G0 period it does not reach the surface of the cell. In all cases, it locates on the centriole with appendages. At the beginning of the G1 period, during the G2 period, and in nonciliated cells in the G0 period, one of the centrioles is situated perpendicular to the substrate. On the whole, it takes a mature centriole a cycle and a half to form in PE cells.

Liquid-crystalline ordering in the solution of partially flexible macromolecules

Abstract: The liquid-crystalline ordering in the solution of persistent chains which length, L, is comparable with the length of the effective Kuhn segment, l, is considered by means of a generalization of the Onsager method. The orientational entropy for this case is calculated using the method proposed by I.M. Lifshitz (for another problem) in 1968. It is shown that a slight flexibility of the persistent chain is sufficient for the complete change in the properties of the liquid-crystalline transition: for example, at L l ∼0.1 these properties are more similar to those which are characteristic for the semi-flexible limit ( L l ⪢1), than for the rigid rod limit ( L l ⪡1), although at such L l the geometric form of the macromolecule is much closer to the rodlike one.

The large scale structure of the universe I. General properties. One-and two-dimensional models

Abstract: Evolution of initially smooth perturbations in a cold self-gravitating medium in a Friedmann Universe gives rise to the formation of singularities in the distribution of density in a manner similar...

Colloidal solution of water in organic solvents: a microheterogeneous medium for enzymatic reactions.

Abstract: To simulate in vitro the conditions under which enzymes act in vivo, enzyme molecules have been entrapped in hydrated reverse micelles of a surfactant in organic solvents. In this system the catalytic activity of one of the enzymes studied (peroxidase) became much higher than in water, and the specificity of the other enzyme (alcohol dehydrogenase) was dramatically altered.

Classical and quantum limitations on energy consumption in computation

Abstract: Fundamental limitations on the energy dissipated during one elementary logical operation are discussed. A model of a real physical device (parametric quantron) based on the Josephson effect in superconductors is used throughout the discussion. This device is shown to be physically reversible, and moreover it can serve as the clementary cell of a logically reversible computer, both these properties being necessary to achieve the fundamental limits of energy dissipation. These limits due to classical and quantum statistics are shown to lie well below the earlier estimates,k B T and ηϑ, respectively.

Critical-current oscillations as a function of the exchange field and thickness of the ferromagnetic metal (F) in an S-F-S Josephson junction

Abstract: The Josephson current in an S-F-S junction is calculated for a short weak link. The current amplitude depends in an oscillatory manner on the exchange field of the pure ferromagnetic metal. When certain conditions are satisfied in a superconducting ring with an S-F-S junction, the energy minimum of the system corresponds to the state with spontaneous current and magnetic flux.

Stochastic partial differential equations and diffusion processes

Abstract: CONTENTS § 1. Introduction § 2. Solubility of the direct and inverse Cauchy problems § 3. The direct equation of inverse diffusion. The method of variation of constants § 4. The method of characteristics. First integrals and the Liouville equations for diffusion processes § 5. Inverse filtration equations References

The generalized Einstein-Maxwell theory of gravitation

Abstract: A new Lagrangian theory of gravitation in which the metric and the arbitrary affine connection are regarded as independent field variables has been considered. Making use of the pure geometrical objects only from the variational principle the empty field equations are derived. It is shown that the metric obeys the ordinary Einstein equations of general relativity. However, the covariant derivative of the metric tensor does not vanish, so that the vector's length is generally nonintegrable under the parallel displacement. The torsion trace vector turns out to be the natural dynamical variable, satisfying the Maxwell-like equations with tensor of homothetic curvature as the Maxwell tensor. The equations of motion are explored; they are shown to be identical to the motion of electric charge under the Lorentz force. The conservation laws are discussed.

Radiation reaction in the Kerr gravitational field

Abstract: The radiative Green functions for the massless scalar, electromagnetic and gravitational perturbations of the Kerr space-time are constructed using the Teukolsky (1973) formalism. The reaction force acting upon a test particle, which can emit radiation of any spin s=0, 1, 2, is calculated and shown to account correctly for the energy and the angular momentum carried away by radiation to infinity and to the event horizon. The azimuthal component of the reaction force is found to remain finite for a particle at rest in the Boyer-Lindquist coordinates owing to non-zero angular momentum transfer to the rotating hole. This anomalous static force of radiation reaction emerges as the counteraction to Hawking's tidal friction.

Thermotropic liquid crystalline polymers, 12. Smectic “C” phase in liquid crystalline polyacrylates with CN-containing mesogenic groups†

Abstract: The study of thermotropic liquid crystalline (LC) polymers with mesogenic side groups, which is intensively carried out nowadays widenes our knowledge about the structure of such systems. The synthesis and the identification of nematic and cholesteric polymeric liquid crystals’) as well as of some smectic phases such as disordered smectics S, and ordered smectics S, have already been reported2-@. Studying the polymeric mesophases, some authors claimed formation of an S, tilted smectic phase’). In this paper we report on the direct observation of the smectic C phase in LC polymers with polar mesogenic groups and on the results of the study of the structure by means of optical microscopy, X-ray analysis and differential scanning calorimetry. S, and S, phases were discovered in polyacrylates of the general formula:

On the theory of Ψ‐condensation

Abstract: We suggest a theory of Ψ-condensation, based on the assumption that a compact DNA particle is a globule, and specifically that a polymer solution is a strongly fluctuating system and that double-stranded DNA is a stiff homopolymer single-stranded chain. We show the DNA globule as it appears in a dilute poly(ethylene oxide) (PEO) solution. The corresponding phase transition is investigated in detail. Growth of the PEO concentration should lead to a decrease in the size of the compact particle and to an increase in its optical rotatory power. Conditions are defined at which drastic compaction of DNA takes place, accompanied by the loss of its optic rotatory power, in regions of high PEO concentrations.

Delayed fluorescence and phosphorescence of plant pigments

Abstract: The term “delayed luminescence” is usually applied to photoinduced light emissions with lifetimes much longer than those of fluorescence of the objects. Under this term are included a wide variety of luminescence phenomena with essentially different mechanisms. A generally adopted terminology for different types of delayed luminescence based on their mechanisms is lacking so far. In biological literature all types of delayed luminescence of pigments are often divided into two large groups: delayed fluorescence and phosphorescence. The delayed fluorescence includes afterglows with spectra similar to those of pigment fluorescence: the phosphorescence corresponds to light emissions accompanying radiative electronic transitions from triplet to ground states of pigment molecules. The present paper deals mostly with these two groups of delayed luminescence. Moreover, a related phenomenon, the photosensitized luminescence of singlet oxygen, is also briefly reviewed. The review covers the literature from January, 1980, through June, 1982, as well as some earlier papers which escaped attention in previous reviews in this field.

Thermotropic Liquid-Crystalline Polymers

Abstract: Investigators in the field of physical chemistry of macromolecular compounds have recently turned to problems in the creation and study of polymeric liquid-crystalline (LC) systems [1–25]. The great interest in these systems is due to the significant advances in the study and practical application of low-molecular-weight liquid-crystals in such new fields of technology as electronics, electrooptics, holography, etc., as well as in medicine, chemistry, and biology [26–32]. On the other hand, the interest in this field is also due to the possibility of creating polymer systems which successfully combine the unique properties of low-molecular-weight liquid crystals and low-molecular-weight compounds, which allows for the preparation of films, fibers, and coatings with unusual properties. The use of low-molecular-weight thermotropic liquid crystals in most cases involves the creation of special hermetic membranes (electro-optical cells, microcapsules, etc.) which form the required shape and protect the LC compound from external effects. In the case of thermotropic LC polymers, the creation of these shapes can be and is optional, since the properties of low-and high-molecular-weight liquid crystals are combined in a single polymer, and this opens up new prospects for their use by significantly extending the number of LC compounds.

Damage of photoreceptor membrane lipids and proteins induced by photosensitized generation of singlet oxygen

Abstract: It has been shown that illumination of rod outer segment suspension in the presence of photosensitizers (methylene blue λ ≥ 620 run; retinal 370 ≥ λ ≥ 390 nm) results in chemical modification of the lipid and protein components of the photoreceptor membranes. This modification can be registered by accumulation of lipid peroxidation (LPO) products as well as oligomerisation of rhodopsin and a decrease of rhodopsin thermal stability. These effects are prevented by ′02-quenchers and free radical scavengers. It has been found that the electric activity (ERG) of isolated frog retina is inhibited due to photosensitized generation of ′02 which can be overcome by preliminary addition of ′03-quenchers and free radical scavengers to the incubation medium. The LPO products are accumulated in the retinae of rats exposed to high intensity light in vivo. It is concluded that ′02 and LPO are involved in light-induced damage of the retina.