Self-organization and FORC-based magnetic characterization of ultra-high aspect ratio epitaxial Co nanostrips produced by oblique deposition on an ordered step-bunched silicon surface.

Further development of microelectronics requires novel or improved technological approaches for device nanofabrication and functional properties characterization. In this paper, we studied the crystal structure and magnetic properties of epitaxial Co nanostrips with the average width of 32.6, 45.3, and 62.6 nm grown on a step-bunched Si(111)5.55 × 5.55-Cu/Cu surface. Technological conditions, under which the ultra-high aspect ratio (∼104) structurally solid, straight nanostrips of hcp-Co with crystallographic axis [0001] oriented along their long side can be grown, were determined. The dependence of the coercive force on the width of the nanostrips was demonstrated. Magnetization reversal through the transverse domain-wall nucleation and propagation in a Co nanostrip was defined with an analytical approach based on the Stoner-Wohlfarth model. Using the first-order reversal curve method, we analyzed the effect of nanostrip uniformity degree on magnetic behavior and the influence of the magnetostatic interactions on the coercive force of individual nanostrips.

Large contributions of coupled protonation equilibria to the observed enthalpy and heat capacity changes for ssDNA binding to Escherichia coli SSB protein.

Many macromolecular interactions, including protein-nucleic acid interactions, are accompanied by a substantial negative heat capacity change, the molecular origins of which have generated substantial interest. We have shown previously that temperature-dependent unstacking of the bases within oligo(dA) upon binding to the Escherichia coli SSB tetramer dominates the binding enthalpy, DeltaH(obs), and accounts for as much as a half of the observed heat capacity change, DeltaC(p). However, there is still a substantial DeltaC(p) associated with SSB binding to ssDNA, such as oligo(dT), that does not undergo substantial base stacking. In an attempt to determine the origins of this heat capacity change, we have examined by isothermal titration calorimetry (ITC) the equilibrium binding of dT(pT)(34) to SSB over a broad pH range (pH 5. 0-10.0) at 0.02 M, 0.2 M NaCl and 1 M NaCl (25 degrees C), and as a function of temperature at pH 8.1. A net protonation of the SSB protein occurs upon dT(pT)(34) binding over this entire pH range, with contributions from at least three sets of protonation sites (pK(a1) = 5.9-6.6, pK(a2) = 8.2-8.4, and pK(a3) = 10.2-10.3) and these protonation equilibria contribute substantially to the observed DeltaH and DeltaC(p) for the SSB-dT(pT)(34) interaction. The contribution of this coupled protonation ( approximately -260 to -320 cal mol(-1) K(-1)) accounts for as much as half of the total DeltaC(p). The values of the "intrinsic" DeltaC(p,0) range from -210 +/- 33 cal mol(-1) degrees K(-1) to -237 +/- 36 cal mol(-1)K(-1), independent of [NaCl]. These results indicate that the coupling of a temperature-dependent protonation equilibria to a macromolecular interaction can result in a large negative DeltaC(p), and this finding needs to be considered in interpretations of the molecular origins of heat capacity changes associated with ligand-macromolecular interactions, as well as protein folding.

Structure of the DNA binding domain of E. coli SSB bound to ssDNA.

The structure of the homotetrameric DNA binding domain of the single stranded DNA binding protein from Escherichia coli (Eco SSB) bound to two 35-mer single stranded DNAs was determined to a resolution of 2.8 A. This structure describes the vast network of interactions that results in the extensive wrapping of single stranded DNA around the SSB tetramer and suggests a structural basis for its various binding modes.

Adenine base unstacking dominates the observed enthalpy and heat capacity changes for the Escherichia coli SSB tetramer binding to single-stranded oligoadenylates.

Isothermal titration calorimetry (ITC) was used to test the hypothesis that the relatively small enthalpy change (DeltaHobs) and large negative heat capacity change (DeltaCp,obs) observed for the binding of the Escherichia coli SSB protein to single-stranded (ss) oligodeoxyadenylates result from the temperature-dependent adenine base unstacking equilibrium that is thermodynamically coupled to binding. We have determined DeltaH1,obs for the binding of 1 mole of each of dT(pT)34, dC(pC)34, and dA(pA)34 to the SSB tetramer (20 mM NaCl at pH 8.1). For dT(pT)34 and dC(pC)34, we found large, negative values for DeltaH1,obs of -75 +/- 1 and -85 +/- 2 kcal/mol at 25 degrees C, with DeltaCp,obs values of -540 +/- 20 and -570 +/- 30 cal mol-1 K-1 (7-50 degrees C), respectively. However, for SSB-dA(pA)34 binding, DeltaH1,obs is considerably less negative (-14 +/- 1 kcal/mol at 25 degrees C), even becoming positive at temperatures below 13 degrees C, and DeltaCp,obs is nearly twice as large in magnitude (-1180 +/- 40 cal mol-1 K-1). These very different thermodynamic properties for SSB-dA(pA)34 binding appear to result from the fact that the bases in dA(pA)34 are more stacked at any temperature than are the bases in dC(pC)34 or dT(pT)34 and that the bases become unstacked within the SSB-ssDNA complexes. Therefore, the DeltaCp,obs for SSB-ssDNA binding has multiple contributions, a major one being the coupling to binding of a temperature-dependent conformational change in the ssDNA, although SSB binding to unstacked ssDNA still has an "intrinsic" negative DeltaCp,0. In general, such temperature-dependent changes in the conformational "end states" of interacting macromolecules can contribute significantly to both DeltaCp,obs and DeltaHobs.

Calorimetric studies of E. coli SSB protein-single-stranded DNA interactions. Effects of monovalent salts on binding enthalpy.

Isothermal titration calorimetry (ITC) was used to examine the effects of monovalent salts (NaCl, NaBr, NaF and ChCl) on the binding enthalpy (DeltaHobs) for E. coli SSB tetramer binding to the single-stranded oligodeoxythymidylates, dT(pT)69 and dT(pT)34 over a wide range of salt concentrations from 10 mM to 2.0 M (25 degrees C, pH 8.1), and when possible, the binding free energy and entropy (DeltaG degrees obs, DeltaS degrees obs). At low monovalent salt concentrations (<0.1 M), the total DeltaHobs for saturating all sites on the SSB tetramer with ssDNA shows little dependence on salt concentration, but is extremely large and exothermic (DeltaHobs=-150(+/-5) kcal/mol). This is much larger than any DeltaHobs previously reported for a protein-nucleic acid interaction. However, at salt concentrations above 0.1 M, DeltaHobs is quite sensitive to NaCl and NaBr concentration, becoming less negative with increasing salt concentration (DeltaHobs=-70(+/-1)-kcal/mol in 2 M NaBr). These salt effects on DeltaHobs were mainly a function of anion type and concentration, with the largest effects observed in NaBr, and then NaCl, with little effect of [NaF]. These large effects of salt on DeltaHobs appear to be coupled to a net release of weakly bound anions (Br- and Cl-) from the SSB protein upon DNA binding. However, at lower salt concentrations (

A highly salt-dependent enthalpy change for Escherichia coli SSB protein-nucleic acid binding due to ion-protein interactions.

We have examined the linkage between salt concentration and temperature for the equilibrium binding of the tetrameric Escherichia coli single-stranded binding (SSB) protein to three single-stranded nucleic acids, poly(U), dA(pA)69, and dT(pT)69, by van't Hoff analysis and isothermal titration calorimetry (ITC). For SSB binding to poly(U) in its (SSB)65 mode, the equilibrium association constant, Kobs, decreases with increasing salt concentration at all temperatures examined, and binding is enthalpy-drive; however, the value of [symbol see text] log Kobs/ [symbol see text] log [NaCl] is highly temperature- dependent, varying from -9.3 +/- 0.3 at 10 degrees C to -5.1 +/- 0.4 at 37 degrees C. This indicates that delta Hobs for SSB-poly(U) binding is strongly dependent on [NaCl]; based on van't Hoff analyses, delta Hobs varies from -57 +/- 3 kcal/mol at 0.18 M NaCl to -34 +/- 3 kcal/mol at 042 M NaCl ([symbol see text] delta Hobs/[symbol see text] log [NaCl] = 60 +/- 5 kcal/mol). However, [symbol see text] delta Hobs/[symbol see text] log [NaF] is independent of temperature (25-37 degrees C), indicating that the effect of [NaCl] on delta Hobs is due primarily to Cl-. Similar effects were also observed for SSB binding to dA(pA)69. We also measured delta Hobs and its dependence on [NaCl] for SSB binding dT(pT)69 by ITC and find delta Hobs = -144 +/- 4 kcal/mol (0.175 M NaCl, pH 8.1, 25 degrees C) and [symbol see text] delta Hobs/ [symbol see text] log [NaCl] = 46 +/- 2 kcal/ mol (0.175-2.0 M NaCl). These large effects of [NaCl] on delta Hobs appear to result, at least partly, from the release of preferentially bound Cl- from SSB protein upon binding nucleic acid, with the release of Cl- being linked to a process with delta H > > 0. Effects of salt concentration on delta Hobs are not observed for processes in which only monovalent cations are released from the nucleic acid, presumably since Na+ of K+ are bound to linear nucleic acids as delocalized, fully hydrated cations. Such salt effects on delta Hobs may serve as a signature for differential ion-protein binding. These results underscore the need to examine the linkage of [salt] to delta Hobs, as well as delta Hobs degrees and delta S(obs) degrees, in order to understand the bases for stability and specificity of protein-nucleic acid interactions.

[A comparative evaluation of the efficacy of pharmacotherapeutic agents in hypoxia in the presence of hyperthermia]. / Sravnitel'naia otsenka éffektivnosti farmakoterapevticheskikh sredstv pri gipoksii na fone gipertermii.

In conditions of acute hypoxia in the presence of hyperthermia drugs were shown to exhibit various degrees of protective activity. Antihypoxic action coupled with thermoprotective activity is manifested by beneficial affect on the course of the pathological process. It is quercitrol that proved to be the most effective drug; it is capable of correcting simultaneously the disturbances emerging in different links of the pathological process: effect on the processes of lipid peroxidation and metabolism of arachidonic acid as well as on the activity of enzymes belonging to the monooxigenaze system in the experiment.

[Treatment of generalized suppurative peritonitis]. / Lechenie obshchego gnoinogo peritonita.

In the period from 1980 to 1986 fifty-nine patients were treated for generalized purulent peritonitis of 72-hour duration. The traditional methods of therapy were applied--removal of the source of peritonitis and drainage of the abdominal cavity. The mortality was 62.7%. Since 1987, peritoneal lavage with enteral administration of oxygenized 5% glucose solution is used in the treatment of patients with generalized peritonitis in the stage of poly-organic insufficiency. Peritoneal-enteral lavage was applied in the management of 41 patients, 10 of them died. The mortality was 36.5%. The efficacy of the method was judged on basis of bacteriological study, electroenterography, and functional tests for the absorptive capacity of the small intestine. The results of stage peritoneal lavage and the findings of bacteriological study lead to the conclusion that it is extremely dangerous to postpone repeated cleansing of the abdominal cavity in such patients because progressive deterioration of the condition with a fatal outcome occurs in this case. Cleansing of the abdominal cavity must be accomplished during the first lavage or 24 hours later during relaparotomy and no hope should be entertained that inadequate cleansing will be compensated for during subsequent relaparotomies.

[Peritoneo-enteric lavage in generalized purulent peritonitis during multiple organ insufficiency]. / Peritoneal'no-énteral'nyi lavazh pri obshchem gnoinom peritonite v stadii poliorgannoi nedostatochnosti.

The article analyses two matched groups of patients with generalized purulent peritonitis of 72-hour duration in the stage of polyorganic insufficiency. There were 100 patients. Application of organ-resuscitation measures in the abdominosplanchnic zone is the key moment of the surgical treatment of patients with generalized purulent peritonitis. In view of this, peritoneoenteric lavage with oxygenated energy mass of 5-10% glucose solution is indicated together with intensive infusion-transfusion, antibacterial therapy, and extracorporeal detoxification for such patients. Combination of peritoneal lavage with enteric through a distal retrograde immobilizing dehydrostatic iliostomy produces the best results.

[The bacteriological and immunological assessment of peritoneal-enteral lavage in the treatment of general suppurative peritonitis at the stage of multiple organ failure]. / Bakteriologicheskaia i immunologicheskaia otsenka peritoneal'no-énteral'nogo lavazha v lechenii obshchego gnoinogo peritonita v stadii poliorgannoi nedostatochnosti.

The article shows that peritoneal-enteral lavage reduced the yield of microorganisms from the suppurative focus, the reduced yield after a single lavage might be considered as a favourable prognostic sign. Results of a quantitative bacteriological analysis are thought to be an objective criterion for performing or completing the stage of the peritoneal lavage. The peritoneal-enteral lavage promotes the activation of local defensive reactions in the abdominal cavity.

Polyelectrolyte properties of biopolymers: conductivity and secondary structure of polyriboadenylic acid and its salts in solutions.

Polyriboadenylates of alkali metals were obtained from (1) K(+)-poly(A) (salts 1) and (2) H(+)-poly(A) (salts II) by the ion-exchange method. The conductivity of these salts as well as of H(+)-poly(A) were studied. Salts I and II of the same counterion were shown to have significantly different conductivity coefficients (f) and polyion conductances (lambda 0p). the charge density parameter (xi) was 1.3 and 2.5, respectively, with lambda 0p equal to 44 and 83 ohm-1 cm2 mole-1 for poly(A)-I and poly(A)-II salts, respectively. This is credited to the difference in the conformations of corresponding polyions. The linear dependence of equivalent conductivity on the square root of polymer concentration (Kohlrausch coordinates), earlier obtained for DNA, is also satisfied for the studied polynucleotides. A comparison of the slopes of straight lines in Kohlrausch coordinates for poly(A), simple electrolytes, and for earlier studied polyribouridylic acid salts lends credence to the concepts, developed by a number of authors, that DNA can act as a "buffer" against the ion-ion interaction in concentrated electrolyte solutions. Using the approximation that the polyion conductance is independent of the counterion nature, parameter f (agreeing in this case with Eisenberg parameter phi) has been shown to decrease as the polynucleotide concentration is increased; the decrease is caused by the relaxation effect. The transference numbers of counterions, which have negative values in poly (A)-II solutions, grow with the increase in polymer concentration; the higher the xi, the more apparent is this increase. This is explained by the increase in the fraction of conductivity along the polyion chains ("surface" conductivity) with the growth of polyelectrolyte concentration.

[Pathogenetic mechanisms of the effect of vacuum therapy on the course of the wound process]. / Patogeneticheskie mekhanizmy vliianiia vakuum-terapii na techenie ranevogo protsessa.

On the basis of the analysed results of treatment of 248 patients with abscesses, phlegmons, and purulent wounds who received vacuum therapy and 215 patients with the same diseases treated by the traditional incision-drainage-method, as well as on the grounds of additional examination findings, the authors show the mechanisms of the effect of vacuum therapy on the course of the wound process. They substantiate pathogenetically the marked therapeutic effect of this method in patients with acute purulent diseases of the soft tissues and purulent wounds.

[Catecholamine-induced changes of the kinetic properties of adrenergic receptors of the myocardium]. / Izmenenie kineticheskikh svoistv adrenoretseptorov serdechnoi myshtsy pri deistvii katekholaminov.

The pattern of changes in kinetic properties of beta-adrenoreceptor (Cd, c+ and c-) relative to anapriline adrenoblocker under conditions of muscle perfusion by catecholamines has been estimated on papillary cardiac muscles of the rat as based on the isometric voltage. A priority increase of the receptors' affinity to the blocker is determined, that may be a result of changes in microviscosity of the lipid sarcolemma bilayer.

[Effect of liposomes on the adrenoreactivity of the papillary muscle]. / Vliianie liposom na adrenoreaktivnost' papilliarnoi myshtsy serdtsa.

Unloaded phosphatidylcholine-cholesterol liposomes enhanced the affinity of adrenoreactive system of the rat heart muscle with the ligands and altered the degree of adrenoreceptors' negative cooperativity. The radioligand analysis with 3H-dihydroalprenolol revealed that the liposomes altered kinetic properties of sarcolemma's receptors as revealed by the enhancement of affinity with the marker, decreasing of maximal specific binding and augmentation of the degree of receptors' negative cooperativity.

[Effect of prolonged intracardiac catecholamine infusion on the active nature of neuronal uptake in the atrium of the rat]. / Vliianie dlitel'noi vnutriserdechnoi infuzii katekholaminov na aktivnost' neironal'nogo zakhvata v predserdii krysy.

A preliminary saturation of the blood with catecholamines enhanced the ability of atria for neuronal uptake of labeled 3H-noradrenaline. Reserpine potentiated the effect. Issuing from the pattern of formation and disintegration of the agonist receptor complexes, the data obtained are interpreted as the mechanism of increasing the heart adrenoreactivity. The activating effect of catecholamines on the neuronal uptake has a certain threshold and does not depend on the duration of pre-infusion or concentration of administered catecholamines.

[Relation between neuronal uptake and beta-adrenoreactivity of the rat heart]. / Vzaimosviaz' neironal'nogo zakhvata i beta-adrenoreaktivnosti serdtsa krysy.

A positive correlation exists between the activity of neuronal uptake and the heart beta-adrenoreactivity. The amount of catecholamines in the myocardium is unrelated to this interconnection.