Millisecond dynamics of deformation bands during discontinuous creep in an AlMg polycrystal.

Formation of bands of macroscopic strain localization during staircase creep in an AlMg polycrystal is studied by the acoustic emission (AE) technique and high-speed video recording with an image acquisition rate up to 50 000 frames per second. The simultaneous measurements by two methods allow us to distinguish different types of embryo deformation bands and concomitant AE signals, and to establish correlations between the band evolution and the acoustic response. It is found that the fastest stages of band formation, associated with its emergence to the surface and subsequent accelerated expansion, generate complex AE bursts in the frequency band ∼0.05-1 MHz. The correlations hidden in the complex structure of an individual acoustic burst are investigated by methods of statistical and fractal analysis. On the other hand, relationships between average parameters of various physical responses to discontinuous creep are assessed. Particularly, a close correspondence is found between the envelope of the acoustic burst and the rate of stress change during formation of a single deformation band. Evolution of dynamical behavior of embryo bands with increasing creep stress is discussed. Notably, a qualitative change in the AE waveform observed on approaching the ultimate stress is considered from the viewpoint of anticipation of the oncoming fracture.

[A paradigm of early gonarthrosis: a review of the current diagnostic and treatment options (Part 1)]. / Paradigma rannego gonartroza: obzor sovremennykh vozmozhnostei diagnostiki i lecheniia (Chast' 1).

The prevalence of chronic joint diseases, among which osteoarthritis (OA) prevails, continues to grow worldwide. So far, many OA patients starting to get any kind of treatment only at the stage of organ failure, when the progression of the pathological process cannot be considerably delayed. The long-felt need for a change in thinking how to effectively diagnose and treat OA patients at early stage induced to prepare this review. Its first part is devoted to discussion of the limitations of traditional approaches and to analysis of the current diagnostic capabilities, particularly the clinical features of early OA, its morphological characteristics based on the magnetic resonance imaging and arthroscopic criteria, as well as the perspectives of biochemical and genetic markers implementation.

The Russian experience in brucellosis veterinary public health.

Russia has extensive experience in controlling brucellosis in large and small animals, based on systematic animal health and disease control measures, combined with the use of specific prophylaxis. Widespread application of the live brucellosis vaccine Brucella abortus strain 82 has led to a dramatic reduction in the prevalence of brucellosis. Among the distinctive properties of this vaccine are weak agglutinogenicity and high anti-epizootic efficacy, which allow differentiation between infected animals and vaccinated animals, combined with protection against brucellosis infection. In this paper, the authors review brucellosis epidemiology, diagnostics, the application of vaccines and management procedures that allow the Russian Federation to reduce the overall prevalence of brucellosis.

[Evolution of diagnostics and treatment methods of closed isolated spleen injuries in children].

An analysis of treatment of 75 children of the age from 3 years to 17 admitted to the St. Petersburg Pediatric Medical Academy was made. All the children were admitted with the diagnoses of blunt (closed) injuries of the abdomen, ruptures of the spleen, intra-abdominal bleedings. The patients were divided into 3 groups according to the periods of hospitalization. In each group the patients were examined and treated which corresponded to the surgical strategy for rupture of the spleen at that period. Different methods of examinations and therapy were determined in the three groups of patients with similar pathology.

Generation of excitatory postsynaptic potentials in the hippocampus after functional modification of glycosaminoglycans.

Experiments on hippocampal slices form 4-week-old rats (n=28) showed that addition of lidase (1.0 and 10.0 U/ml) to the perfusion solution (artificial cerebrospinal fluid) was accompanied by the impaired generation or blockade of excitatory postsynaptic potentials and population spikes in the hippocampal CA1 region during stimulation of Schaffer collaterals. Removal of lidase from this solution normalized the amplitude of evoked responses. Hence, lidase in these concentrations produced a reversible effect on synaptic transmission. Our results indicate that structure and function of glycosaminoglycans in the extracellular matrix determine signal transduction in the nervous tissue.

[Individual professional colour perception by doctors-stomatologists].

Taking into account wide use of photopolymer materials in practical stomatology and increasing patients' desire in improving their appearance very actual is the question of optimal colour selection by doctors-stomatologists in the process of making esthetic restorations of the teeth. Thereupon the authors have studied the influence of stable personal behaviour and psychological status of doctor-stomatologist upon its ability to pick up tints.

[Automated system of radiation monitoring in Moscow region].

The authors consider one trend in activities of "Radon"--Center of Radiation and Ecologic Control. The article covers foundation reasons and longstanding function results of operative radiation monitoring system for large industrial city. Features of construction and functioning of the system are shown. Devices for operative radiation monitoring are subjected to comparative analysis. Prospective trends of the system development are described.

Spot Weld Analysis With 2D Ultrasonic Arrays.

This paper describes a threefold method of testing the performance of an array-based ultrasonic tool for nondestructive testing of spot welds. The tool is described in its capabilities, use, and advantages over existing counterparts. Performance testing for and the results from carrying out the testing are described. The three performance testing methods include 1) the use of calibrated samples, 2) comparisons with actual spot-welds, and 3) a performance evaluation of the embedded fitting software. The test of the fitting software was carried out by a comparison of results with reference fits supplied by the National Institute of Standards and Technology.

[Antimutagenic hypoxen activity in vivo]. / Izuchenie antimutagennoi aktivnosti gipoksena in vivo.

The antimutagen effect of the drug hypoxen, representing poly(2,5-dihydroxyphenylene)-4-thiosulfonic acid sodium salt, was studied by chromosome aberration assay in the bone marrow cells of C57BL/6 mice. Hypoxen (20 mg/kg, i.p.) administered simultaneously with dioxidine (300 mg/kg, i.p.) reduced genotoxicity of the latter compound by 35% over a time period of 24 h. Preliminary five-day administration of hypoxen (70 mg/kg, p.o.) did not decrease the dioxidine damage. The genoprotector activity of hypoxen upon interaperitoneal injection is more pronounced as compared to that of the reference drug sladex (aspartam).

[Acoustic microscopy methods in studies of the filling materials microstructure]. / Ispol'zovanie metodov akusticheskoi mikroskopii dlia issledovaniia mikrostruktury plombirovochnykh materialov.

The structure of filling materials (kemfil, polyacrylate cement, and Dentis, material produced by Stomadent Firm in Russia) at the interface with human dentin was studied in teeth subjected to retrograde filling with preliminary appendectomy. A prototype of table wide-field short pulse scanning acoustic microscope (50 mHz) (Acoustic Microscopy Center, Institute of Biochemical Physics of Russian Academy of Sciences) and Elsam acoustic microscope (200 mHz) (Leitz, Germany) were used. The results indicate that analysis of acoustic characteristics, including the data of acoustic microscopy, helps investigate the cement microstructure and evaluate the compactness and elasticity of samples; moreover, structural elements of the material, which are undetectable by other methods, are seen on acoustic images. These data can be used for evaluating the relationship between the microstructure and formation of mechanical properties, and, maybe, the patterns of cement interactions with dental tissues.

Investigation of biosynthesis of human lymphotoxin in cells of recombinant Escherichia coli strain.

The effect of cultivation conditions on the biosynthesis of human lymphotoxin in recombinant Escherichia coli SG20050/pLT21 strain was studied. Cells of the producing strain were grown in Luria broth containing chloramphenicol. The highest biomass yield of the recombinant strain and plasmid DNA stability were observed under these conditions. To enhance the level of lymphotoxin production an inoculate containing freshly obtained or frozen with glycerol transformants of the producing strain were used, and the cultivation process was performed at 32 degrees C. As a result, lymphotoxin was synthesized in a soluble form without the formation of inclusion bodies. A study of the protein synthesis dynamics during the cultivation of E. coli at 32 degrees C showed that the highest lymphotoxin activity was observed during the exponential growth phase, being maximal at the end of the exponential phase and at the beginning of the stationary phase. The set of indicated methods allowed us to maximize and stabilize the production of lymphotoxin in a biologically active form with a final yield of 18-20% from cell protein.

[Antiviral properties of recombinant human lymphotoxin]. / Protivovirusnye svoistva rekombinantnogo limfotoksina cheloveka.

Study of the antiviral properties of recombinant human lymphotoxin obtained from Escherichia coli SG20050/pLT21 strain by microbiological synthesis showed this lymphotoxin to inhibit vesicular stomatitis virus on M-19 cells and exert a synergistic effect with recombinant human gamma-interferon. The drug exhibited no anti-HIV1 activity in experiments with MT4 cells pretreated with the virus or the drug itself; on the contrary, HIV1 reproduction in these cells was enhanced at low concentrations of the recombinant lymphotoxin.

[Recombinant human lymphotoxin: synthesis in Escherichia coli cells, purification, and certain properties]. / Rekombinantnyi limfotoksin cheloveka: sintez v kletkakh Escherichia coli, ochistka i nekotorye svoistva.

The biosynthesis of recombinant human lymphotoxin produced by E. coli SG20050/pLT21 cells and deprived of 21 amino acid residues has been studied. It has been shown that the bulk of the recombinant protein in E. coli cells is in the soluble form and predominantly localized in the cytoplasm. The maximal synthesis of soluble recombinant lymphotoxin is achieved during 24-hour cultivation of producing strain cells at 32 degrees C. A procedure for isolation and purification of the recombinant protein from E. coli cells has been developed. The purification is accomplished by gel-filtration on Sephadex G-150, ion-exchange chromatography on DEAE-Sephadex and CM-Sephadex, resulting in 97-fold purification and a 62% yield. The specific activity of the protein is about 1-10(8) U per mg of protein. Some physico-chemical properties of the recombinant protein have been studied.

[Properties of aminoglycoside-3'-phosphotransferases determined by kanamycin transposones Tn 601 and Tn 5]. / Svoistva aminoglikozid-6'-fosfotransferaz, determiniruemykh Kapamitsinovymi transpozonami Tn 601 i Tn 5.

Aminoglycoside-3'-phosphotransferase I and II (APT-3'-I and APT-3'-II) has been purified to homogenity from the cells of E. coli containing the plasmids R6 and JR67, respectively. The purification procedure involved competitive affinity chromatography on neomycin-sepharose and gel-filtration on Sephadex G-100. The specific activity of APT-3'-I with the substrates--lividomycin A, neomycin B, paromycin, ribostamycin, kanamycins A and B--are 4.3, 2.8, 2.1, 1.6, 0.9 and 0.8 mol/min. mg protein, respectively. The specific activity of APT-3'-II with the substrates--ribostamycin, paromycin, kanamycins A and B, neomycin B--are 8.0, 7.2, 4.0, 4.5 and 3.6, respectively. Mg2+ is required for the activity of both enzymes. Co2+, Zn2+ and Mn2+ are active in case of APT-3'-I; however, these cations are less active than Mg2+. The pH-optimum of APT-3'-I and APT-3'-II is 7.0--7.5. High ionic strength is required for the activity of both enzymes. The molecular weights of APT-3'-I and APT-3'-II are about 36 000 and 26 000, respectively. The amino acid composition of APT-3'-I and APT-3'-II was determined. Both enzymes contain tryptophane residues whose fluorescence intensity decreased when ATP, but not amino-glycoside antibiotics, is added. The interrelationship between the molecular weights of these enzymes and the sizes of the loops of transposones Tn 601 and Tn 5, encoding APT-3'-I and APT-3'-II, is discussed.

[Transposition of the kanamycin resistance determinant (Tn601) from plasmid 5T to the genome of bacteriophage lambda and the expression of this gene after prophage induction]. / Transpozitsiia determinanta kanamitsinrezistentnosti (Tn601) iz plazmidy R6 v genom bakteriofaga lambda i vyrazhenie étogo gena posle induktsii profaga.

Tn601, determinging kanamycin resistance of Escherichia coli, has been transposed into the bacteriophage lambda genome from R6 plasmid. After curing lambda gtc1857 (Tn601) lysogenes on the kanamycin containing medium, the clones with stable and unstable integrations of the Tn6-1 into the chromosome were obtained. After the lysogenization of these clones with the phage lambda att80c1857S7, the phages lambda att80c1857S7 (Tn601) were obtained. These phages contained the Tn601 from the sites of stable or unstable integrations. The frequency of the Tn601 transposition from the sites of unstable integration was 10(-7), that was two order of magnitude higher than the frequency of the Tn601 transpostion from the site of stable integration. Temperature induction of the lambda att80c1857 (Tn601) prophage resulted in 10--15 times increase of the yeild of aminoglycoside-3'-phosphotransferase I, the enzyme coded by the aphA gene of the Tn601.

[Phosphate group donors for neomycin inactivation by resistant microorganism strains]. / Donory fosfatnykh grupp dlia inaktivatsii neomitsina rezistentnymi shtammami mikroorganizmov.

The substrate specificity of aminoglycoside phosphotransferases isolated from 3 strain of E. coli and purified was studied. All pure enzymes phosphorilated neomycin, paromomycin, lividomycin, neamine, ribostamycin, kanamycins A and B. Only ATP was the donor of the phosphate groups in these reactions, while in the non-purified extracts GTP but not UTP or CTP served as the donor of the phosphate group for inactivation of neomycin. The substrate specificity indicated that the above enzymes were aminoglycoside-3(1)-phosphotransferases. Inactivation of neomycin with the use of the phosphate group of phosphoenolpiruvate as the donor in the non-purified enzymatic preparations of the neomycin-resistant strains of E. coli and Pseudomonas was not observed.