Lattice dynamics and superconductivity in cerium at high pressure.

We have measured phonon dispersion relations of the high-pressure phase cerium-oC4 (α' phase with the α-uranium crystal structure) at 6.5 GPa by using inelastic x-ray scattering. Pronounced phonon anomalies are observed, which are remarkably similar to those of α-U. First-principles electronic structure calculations reproduce the anomalies and allow us to identify strong electron-phonon coupling as their origin. At the low-pressure end of its stability range, Ce-oC4 is on the verge of a lattice-dynamical instability and possibly a charge density wave. The superconducting transition temperatures of the fcc, oC4, and mC4 phases of Ce have been calculated, and the superconductivity observed experimentally by Wittig and Probst is attributed to the oC4 phase.

[The use of colloidal gold-labelled antibodies for demonstrating viral antigens]. / Primenenie mechennykh kolloidnym zolotom antitel dlia indikatsii virusnykh antigenov.

The principal possibility of using antibodies conjugated with colloid gold for better visualization of viruses, viral antigens, and their immune complexes in electron microscope was studied on the experimental model of HBs-antigen and Venezuelan equine encephalomyelitis virus. The same method was used for the study of the thin structure of influenza A (H1N1) virus hemagglutinins using monoreceptor antisera.

Elastic phase transitions in metals at high pressures.

The elastic phase transitions of cubic metals at high pressures are investigated within the framework of Landau theory. It is shown that at pressures comparable with the magnitude of the bulk modulus the phase transition is connected with the loss of stability relative to uniform deformation of the crystalline lattice. Discontinuity of the order parameter at the transition point and its equilibrium value are expressed through the second- to fourth-order elastic constants. The second-,third- and fourth-order elastic constants and phonon dispersion curves of vanadium under hydrostatic pressure are obtained by first-principles calculations. Structural transformation in vanadium under pressure is studied using the obtained results. It is shown that the experimentally observed at P ≈ 69 GPa phase transition in vanadium is the first-order phase transition close to a second-order phase transition.

[Organ-sparing gastrectomy in peptic ulcer]. / Organosokhraniaiushchaia rezektsiia zheludka pri gastroduodenal'nykh iazvakh.

Experimental and clinical data show the zone of hormonal stimulation of gastric juice secretion and that of parietal gastric hydrolysis to have well-defined borders coinciding with anatomical reference points, to be characterized by multidirectional gradient and to be a local mechanism regulating secretory and motor gastric activity. The condition of the lesser curvature ++muco-epithelial complex is one of the factors operable in development of gastroduodenal ulcer. It is hold that resection of hormone--contact zone of the stomach is a preserving, effective and available means of surgical management of gastroduodenal ulcer.

[Quantitative properties and biosynthesis of phospholipids in rat embryonic tissues in the process of development]. / Kolichestvennyi sostav i biosintez fosfolipidov v tkaniakh émbrionov krys v protsesse razvitiia.

The content of lipid phosphorus and the rate of [1-14C]palmitate incorporation into individual phospholipids of rat embryonic liver, kidney, spleen, brain, and placenta at different stages of prenatal development were studied. It was shown that the level of neutral phospholipids at all stages is much higher than that in acid fractions; however, the rate of the acid fraction exchange is 10 times higher depending on the age of the embryos. The specific radioactivity of individual fractions of embryonic rat tissue largely exceeds that in adult animals.

[Thyroid tissue phospholipids in different forms of pathology]. / Fosfolipidy tkani shchitovidnoi zhelezy pri razlichnykh formakh ee patologii.

Phospholipid localization in the thyroid was studied in patients with nodose euthyroid- and diffuse-toxic goiter by means of histochemistry. At the same time biochemical studies on the total amount of phospholipids and their separate fractions were carried out. The maximum phospholipid number was seen in C-cells of patients with all the forms of nodose and diffuse-toxic goiter and in the control group. The C-cell amount in the nodes of the thyroid with pronounced lymphoid infiltration and in the tissue of diffuse-toxic goiter was 5 to 10 times higher comparatively to that of the controls. The total phospholipid content was twice higher in nodose goiter and 3 times higher in the diffuse-toxic forms. Correlation between the increased amount of phospholipids, particularly of phosphatidylcholine, and the enhanced C-cell number was found. The near-nodose tissue is not suitable for the control, as this part of the gland undergoes functional tension, according to the total phospholipid content and the number of C-cells, enriched with phospholipids.

[Autologous liposomes]. / Autologichnye liposomy.

A possibility to increase liposomal tropism to different organs by obtaining them from target lipid cells is considered. The interaction of liposomes of varying phospholipid and ganglioside composition with hepatic cells of rats was studied in vitro. It was found that this interaction was governed both by the phospholipid and ganglioside composition of the vesicles. Liposomes formed of phospholipids and gangliosides of target cells were captured better by the cells. Liposomes formed by summary hepatic phospholipids and gangliosides were shown to be eliminated more rapidly from the flow and to accumulate in the liver of the rats. This suggests that liposomal affinity for specific organs may be increased by changing the content and proportion of lipids in the liposomes to attain the maximal similarity to the composition of the target cell membranes.

[Quantitative composition and functional role of thyroid phospholipids in nodular hypothyroid goiter]. / Kolichestvennyi sostav i funktsional'naia rol' fosfolipidov shchitovidnoi zhelezy pri uzlovom gipotireoidnom zobe.

Correlations between change in the composition of thyroid nodal tissue individual phospholipids and intensity of oxidizing processes under the influence of various phospholipid liposomes were studied. The thyroid phospholipid fraction level was investigated in patients with nodular goiter. A decrease in the level of sphingomyelin and phosphatidylinositide by 54%, cardiolipin by 63%, phosphatidic acid by 70%, phosphatidylserine by 46%, phosphatidylcholine by 7% and a two-fold increase in the level of phosphatidylethanolamine as compared to the control one were shown. A study of a degree of reduction of oxidation metabolism by adding phospholipid liposomes to thyroid sections showed that the tissue of a node possessed weaker oxidizing activity as compared to the control one. O2 absorption and 14CO2 excretion up to 30% were lowered in a hyperthyroid node. An activating liposome effect was noted in thyroid nodal tissue, mostly in the presence of phosphatidylserine, cardiolipin and phosphatidylinositide; the weakest effect was produced by phosphatidylethanolamine and phosphatidylserine.

[Sialic acid content of individual tissue glycolipids in rats under normal conditions and in alloxan diabetes]. / Soderzhanie sialovykh kislot individual'nykh glikolipidov tkanei v norme i pri alloksanovom diabete u krys.

Thin-layer chromatography on silica gel was used to identify individual gangliosides in the rat brain, cardiac, renal, spleen, pancreatic and skeletal muscles in health and to measure the content of sialic acid in the above organs. A dramatic decrease in mono-, di-, tri- and polysialoganglioside levels was seen in tissues of rats with alloxan diabetes. The data obtained indicate that insulin reception disorders may be provoked by the reduced content of acidic glycolipids in plasma membranes.

[Relation between the changes in glycolipid levels and substrate oxidation in skeletal muscle in alloxan diabetes in rats]. / Izuchenie vzaimosviazi mezhdu izmeneniem soderzhaniia glikolipidov i okisleniem substratov v skeletnoi myshtse pri alloksanovom diabete u krys.

Administration of alloxan to rats in a dose of 50-150 mg/kg raises blood sugar level from 200 +/- 14 to 800 +/- +/- 16 mg/100 ml. Under these conditions, the content of total gangliosides in the rat femoral muscle progressively decreases, namely from 137 +/- 9 micrograms sialic acid per g tissue to 63 +/- 4, which is linked with alloxan diabetes severity and hyperglycemia. At the same time there was a 3-4-fold inhibition of 14C-glucose oxidation intensity by tissue sections of the skeletal muscles in the presence of a 1.5-2-fold activation of 1-14C-palmitate. Fractionation of glycolipids on silica gel KSK demonstrated a 33% decrease in the content of monosialogangliosides, and a lesser diminution in the content of other fractions. Total muscle gangliosides, added to the incubation medium exogenously, produced a pathogenetic correcting action on disturbed oxidation of 14C-glucose in alloxan diabetes.

[Fatty acid composition of individual phospholipids in skeletal muscle at different insulin levels in the rat]. / Zhirnokislotnyi sostav individual'nykh fosfolipidov skeletnykh myshts pri razlichnom soderzhanii insulina v organizme krys.

Insulin injections cause an increase of the total content of saturated fatty acids in the sphingomyelin and phosphatidylethanolamine fractions of rat skeletal muscles as well as in the amount of unsaturated fatty acids in the phosphatidyl choline, phosphatidyl serine and phosphatidyl inositol fractions. These effects are not always opposite in case of alloxan diabetes.

[Content, intensity of exchange, and metabolic interaction of phospholipids and glycolipids in various tissues in experimental diabetes]. / Soderzhanie, intensivnost' obmena i metabolicheskie vzaimootnosheniia fosfolipidov i glikolipidov tkanei pri eksperimental'nom diabete.

The contents of individual gangliosides in various tissues (e. g. heart, skeletal muscles, liver, brain, kidney, spleen, pancreas) under normal conditions and in alloxan diabetes as well as the incorporation of 1-14C-stearate into the phospholipid, glyceride and total ganglioside fractions were studied. The oxidation of 14C-fatty acid and the activities of neuraminidase and lipase in these tissues were determined. It was found that diabetes is concomitant with a marked decrease of the content and exchange of gangliosides, which is paralleled with activation of neuraminidase. The incorporation of 14C-stearate in the sphingomyelin and phosphatidylcholine fractions is significantly decreased, while that in the cardiolipin fraction is increased 1.5 - 2-fold. The oxidation of 14C-stearate is also increased, the degree of this increase being tissue-specific.

[Phospholipid makeup and content in various organs of rats with alloxan diabetes]. / Sostav i soderzhanie fosfolipidov v razlichnykh organakh krys pri alloksanovom diabtee.

The phospholipid spectrum and their content in the liver, heart, kidneys and the brain of rats was studied comparatively under normal conditions and in alloxan diabetes. Under pathological conditions there occurred significant changes in the amount of individual phospholipids in all the organs, but the most pronounced changes were noted in the brain. A sharp increase of cardiolipin content and a regular reduction of choline-containing lipids--lecithin and sphyngomyelin--in the organs under study were characteristic of alloxan diabetes. Oscillations in the concentration of other phospholipid fractions (phosphatidyl serine, phosphatidylinositol, phosphatidylethanolamine) had a definite organic specificity.

Defect-induced magnetic structure in (Ga(1)-(x)Mn(x))As.

We show that magnetic structures involving partial disorder of local magnetic moments on the Mn atoms in (Ga(1)-(x)Mn(x))As lower the total energy, compared to the case of perfect ferromagnetic ordering, when As defects on the Ga sublattice are present. Such magnetic structures are found to be stable for a range of concentrations of As antisites, and this result accounts for the observed magnetic moments and critical temperatures in (Ga(1)-(x)Mn(x))As. We propose an explanation for the stabilization of the partially disordered magnetic structures and conclude that the magnetization and critical temperatures should increase substantially by reducing the number of As antisite defects.