Characterization of oxidation of glutathione by cytochrome c.

Cytochrome c is a member of the respiratory chain of the mitochondria. Non-membrane-bound (free) cytochrome c can be reduced by gluthatione as well as ascorbic acid. We investigated the effect of pH, Ca2+, Mg2+ and anionic phospholipids on the reduction of cytochrome c by glutathione.The reduction of cytochrome c by thiols was measured using photometry. Mitochondrial oxygen consumption was detected by use of oxygen electrode. Glutathione does not reduce cytochrome c at pH = 7.0 in the absence of Ca2+ and Mg2+. The reduction of cytochrome c by glutathione is inhibited by anionic lipids, especially cardiolipin. The typical conditions of apoptosis-elevated pH, Ca2+ level and Mg2+-increases the reduction of cytochrome c. Glutathione (5 mM) causes increased mitochondrial O2 consumption at pH = 8.0, in the presence of ADP either 1 mM Mg2+ or 1 mM Ca2+. Our results suggest that membrane bound cyt c does not oxidize glutathione. Free (not membrane bound) cytochrome c can oxidize glutathione. In mitochondria, O2 is depleted only in the presence of ADP, so the O2 depletion observed in the presence of glutathione can be related to the respiratory chain. Decreased glutathione levels play a role in apoptosis. Therefore, membrane unbound cyt c can contribute to apoptosis by oxidation of glutathione.

Spontaneous Rotation of Ferrimagnetism Driven by Antiferromagnetic Spin Canting.

Spin-reorientation phase transitions that involve the rotation of a crystal's magnetization have been well characterized in distorted-perovskite oxides such as orthoferrites. In these systems spin reorientation occurs due to competing rare-earth and transition metal anisotropies coupled via f-d exchange. Here, we demonstrate an alternative paradigm for spin reorientation in distorted perovskites. We show that the R_{2}CuMnMn_{4}O_{12} (R=Y or Dy) triple A-site columnar-ordered quadruple perovskites have three ordered magnetic phases and up to two spin-reorientation phase transitions. Unlike the spin-reorientation phenomena in other distorted perovskites, these transitions are independent of rare-earth magnetism, but are instead driven by an instability towards antiferromagnetic spin canting likely originating in frustrated Heisenberg exchange interactions, and the competition between Dzyaloshinskii-Moriya and single-ion anisotropies.

Emergence of a Magnetostructural Dipolar Glass in the Quadruple Perovskite Dy_{1-δ}Mn_{7+δ}O_{12}.

We show that a polar, pseudo-Jahn-Teller instability exists for the underbonded rare-earth A-site cations in the quadruple perovskite Dy_{1-δ}Mn_{7+δ}O_{12}, which leads to the spontaneous formation of a dipolar glass. This observation alone expands the applicability of pseudo-Jahn-Teller physics in perovskite-derived materials, for which it is typically confined to B-site cations. We demonstrate that the dipolar glass order parameter is coupled to a ferrimagnetic order parameter via strain, leading to a first order magnetostructural phase transition that can be tuned by magnetic field. This phenomenology may emerge in a broad range of perovskite-derived materials in which A-site cation ordering and octahedral tilting are mutually tied to meet the criteria of structural stability.

Catalytic properties and amino acid sequence of endo-1→3-ß-D-glucanase from the marine mollusk Tapes literata.

A specific 1→3-ß-D-glucanase with molecular mass 37 kDa was isolated in homogeneous state from crystalline style of the commercial marine mollusk Tapes literata. It exhibits maximal activity within the pH range from 4.5 to 7.5 at 45°C. The 1→3-ß-D-glucanase catalyzes hydrolysis of ß-1→3 bonds in glucans as an endoenzyme with retention of bond configuration, and it has transglycosylating activity. The K(m) for hydrolysis of laminaran is 0.25 mg/ml. The enzyme is classified as a glucan endo-(1→3)-ß-D-glucosidase (EC 3.2.1.39). The cDNA encoding this 1→3-ß-D-glucanase from T. literata was sequenced, and the amino acid sequence of the enzyme was determined. The endo-1→3-ß-D-glucanase from T. literata was assigned to the 16th structural family (GHF 16) of O-glycoside hydrolases.

Structural stability of CuAl2O4under pressure.

Structural properties of CuAl2O4, which was recently argued to show unusual suppression of the Jahn-Teller distortions by the spin-orbit coupling, are investigated under pressures up to 6 GPa. Analysis of x-ray powder diffraction experiments shows that CuAl2O4gets unstable and decomposes onto CuO and Al2O3at pressures ∼6 GPa and temperature ∼1000 K. This finding is complemented by the density-functional theory +U+ spin-orbit coupling calculations, which demonstrate that this instability is partially driven by a (relatively) large compressibility of strongly Jahn-Teller distorted CuO.

[Shunting operations in the hypertensive hydrocephalic syndrome in children with developmental defects of the central nervous system]. / Shuntiruiushchie operatsii pri gipertenzionno-gidrotsefal'nom sindrome u detei s porokami razvitiia tsentral'noi nervnoi sistemy.

By analyzing the outcomes of surgical treatment of 105 children with hypertensive syndrome of various genesis, the authors present their data on the detection, diagnosis, and treatment of children with malformations of the central nervous system (CNS). The paper defines the present feasibilities of neurosonography, magnetic resonance imaging, neuroendoscopic verification of CNS malformations and their place in determining the policy and choice of a surgical treatment. The rationale for and the efficiency of cerebrospinal fluid corrective operations in children with these abnormalities are defined. Less good prognosis and a higher risk of surgery for hydrocephalic complications have been revealed and statistically evidenced.

[The endoscopic diagnosis and differential treatment of the complications of shunting operations in children]. / Endoskopicheskaia diagnostika i differentsirovannoe lechenie oslozhnenii shuntiruiushchikh operatsii u detei.

The authors present their experience with endoscopic diagnosis and differential treatment of children with complications after bypass surgery. They show the present-day potentialities, spectrum of surgical interventions and role of video-assisted neuroendoscopic surgery in determining a treatment policy and choosing its method. A principle of multiportality was defined and substantiated, a diagnosis and treatment algorithm for children with this pathology was proposed by using the new minimum invasive technique video-assisted surgery.