Decrease in zinc adsorption onto soil in the presence of EPS-rich and EPS-poor Pseudomonas aureofaciens.

The adsorption of Zn onto the humic and illuvial horizons of the podzol soil in the presence of soil bacteria was studied using a batch-reactor technique as a function of the pH (from 2 to 9) and the Zn concentration in solution (from 0.076mM to 0.760mM). Exopolysaccharides-forming aerobic heterotrophs Pseudomonas aureofaciens were added at 0.1 and 1.0gwetL(-1) concentrations to two different soil horizons, and Zn adsorption was monitored as a function of the pH and the dissolved-Zn concentration. The pH-dependent adsorption edge demonstrated more efficient Zn adsorption by the humic horizon than the mineral horizon at otherwise similar soil concentrations. The Zn adsorption onto the EPS-poor strain was on slightly lower than that onto EPS-rich bacteria. Similar differences in the adsorption capacities between the soil and bacteria were also detected by "langmuirian" constant-pH experiments conducted in soil-Zn and bacteria-Zn binary systems. The addition of 0.1gwetL(-1)P. aureofaciens to a soil-bacteria system (4gdryL(-1)soil) resulted in statistically significant decrease in the adsorption yield, which was detectable from both the pH-dependent adsorption edge and the constant-pH isotherm experiments. Increasing the amount of added bacteria to 1gwetL(-1) further decreased the overall adsorption in the full range of the pH. This decrease was maximal for the EPS-rich bacteria and minimal for the EPS-poor bacteria (a factor of 2.8 and 2.2 at pH=6.9, respectively). These observations in binary and ternary systems were further rationalized by linear-programming modeling of surface equilibria that revealed the systematic differences in the number of binding sites and the surface-adsorption constant of zinc onto the two soil horizons with and without bacteria. The main finding of this work is that the adsorption of Zn onto the humic soil-bacteria system is lower than that in pure, bacteria-free soil systems. This difference is statistically significant (p<0.05). As such, EPS-rich bacteria are capable of efficiently shielding the soil particles from heavy-metal adsorption. The removal efficiency of heavy metals in an abiotic organic-rich soil system should therefore be significantly higher than that in the presence of bacteria. This effect can be explained by the shielding of strongly bound metal sites on the organic-rich soil particles by inert bacterial exopolysaccharides.

[The first clinical experience with a new type of stents -scaffolds, under optical coherence tomography guidance].

OBJECTIVE: To analyze the first clinical experience with new types of stents, absorbable carcasses (scaffolds), under guidance of intravascular imaging techniques. MATERIAL AND METHODS: The paper gives the authors' experience in implanting eight Absorb BVS scaffolds in three patients during one operating session. All operations were performed under intravascular imaging guidance: three patients underwent 8 examinations of four vessels, by using optical coherence tomography (OCT) and 2 did using intravascular ultrasound study (IVUSS). RESULTS: The investigation demonstrated the possibility of implanting two devices partially applied to cover longer lesion lengths, the use of scaffolds after occlusion recanalization, and that of rather high pressure values to adapt a carcass if predilation was adequately performed. In one of the cases, control OCT could reveal timely the signs of extensive prolapse and early thrombosis, which had been unrecorded by angiography and IVUSS. To correct of the occurring problem, implantation of the second absorbable carcass into the first one was first successfully used by optimally adapting the girders and completely correcting the prolapse. CONCLUSION: The absorbable scaffolds may potentially signify a new stage in the development of interventional cardiology. However, their use requires the careful adherence of implantation specifications and primarily the accurate estimation of vessel sizes and accordingly a device that may be needed. The application of absorbable carcasses makes higher standards for the equipment and experience of interventional laboratories that plan their use. The possibility of using intravascular imaging is one the priorities in this series.

[Sorption of humic acids by bacteria].

Capacity for sorption of humic acid (HA) from water solutions was shown for 38 bacterial strains. Isotherms of HA sorption were determined for the cells of 10 strains. The bonding strength between the cells and HA (k) and the terminal adsorption (Q(max)) determined from the Langmuir equation for gram-positive and gram-negative bacteria were reliably different. Gram-positive bacteria sorbed greater amounts of HA than gram-negative ones (Q(max) = 23 ± 10 and 5.6 ± 1.2 mg/m2, respectively). The bonding strength between HA and the cells was higher in gram-negative bacteria than in gram-positive: k = 9 ± 5 and 3.3 ± 1.1 mL/mg, respectively.

[Earthworms as modifiers of the structure and biological activity of humic acids].

Passage of humic acids (HAs) through the digestive tract of the earthworm, Eiseniafetida andrei, resulted in a decrease in molecular masses of the HAs. The effect of earthworm-modified HAs on individual bacteria and on bacterial communities as a whole is different from the effect of native HAs. Modified HA probably induces and regulates microbial successions in soils and composts in a different manner than the native HA, suppressing or stimulating different groups of microorganisms. These results may explain why the positive effects of commercial humates in real soil ecosystems, unlike model communities, attenuate rapidly.

High-resolution atomic force microscopy of DNA.

A method using high resolution atomic force microscopy for imaging DNA has been elaborated. Using super-sharp probes and modified graphite as support for molecule adsorption, DNA molecule images were obtained whose resolution made possible the observation of their fine structure with repeated helical motifs. The method can be used to visualize individual spread molecules of single-stranded DNA.

[Effect of supporting substrates on the structure of DNA and DNA-trivaline complexes studied by atomic force microscopy]. / Vliianie podlozhek pri atomno-silovoi mikroskopii DNK i kompleksov DNK s trivalinom na ikh strukturu.

Linear DNA, circular DNA, and circular DNA complexes with trivaline (TV), a synthetic oligopeptide, were imaged by atomic force microscopy (AFM) using mica as a conventional supporting substrate and modified highly ordered pyrolytic graphite (HOPG) as an alternative substrate. A method of modifying the HOPG surface was developed that enabled the adsorption of DNA and DNA-TV complexes onto this surface. On mica, both purified DNA and DNA-TV complexes were shown to undergo significant structural distortions: DNA molecules decrease in height and DNA-TP displays substantial changes in the shape of its circular compact structures. Use of the HOPG support helps preserve the structural integrity of the complexes and increase the measured height of DNA molecules up to 2 nm. AFM with the HOPG support was shown to efficiently reveal the particular points of the complexes where, according to known models of their organization, a great number of bent DNA fibers meet. These results provide additional information on DNA organization in its complexes with TV and are also of methodological interest, since the use of the modified HOPG may widen the possibilities of AFM in studying DNA and its complexes with various ligands.

[Successful correction with stent-graft of coronary artery rupture after angioplasty]. / Sluchai uspeshnoi korrektsii razryva koronarnoi arterii posle angioplastiki pri pomoshchi implantatsii stent-grafta.

Rupture and perforation of coronary arteries complicate in average 0.5% of radiosurgical coronary interventions and often are accompanied by serious consequences and high mortality. According to-type of coronary perforation different methods of correction are used, ranging from conservative measures to urgent cardiosurgical interventions. Coronary stent-grafts with 'sandwich' type of construction ore composed from two metal stents and PTFE layer between them. Development of such stents enabled effective radioguided endovascular repair of coronary ruptures. The paper presents the first Russian experience of stout-graft implantation for coronary artery rupture occurred during direct stenting of proximal anterior descending artery and balloon angioplasty in distal segment. The rupture occurred probably because of wall fragility between affected segment and muscular bridge. Stent-graft JoStent 16 mm in length connected with 3-mm balloon was implanted with subsequent complete restitution of blood flow, resolution of pain syndrome and ECG normalization. Echocardiography in operative theatre and one day after surgery showed no intrapericardial fluid. Stent-graft devices for urgent implantation in cases of coronary rupture must be included into obligatory equipment of radiosurgical facilities.

[Roentgenosurgery for aortic coarctation and open arterial duct with intravascular ultrasonic examination]. / Rentgenokhirurgicheskie operatsii po povodu koarktatsii aorty i otkrytogo arterial'nogo protoka s ispol'zovaniem vnutrisosudistogo ul'trazvukovogo issledovaniia.

Forty-five patients (32 with open arterial duct and 13 with aortic coarctation) were examined. Forty-nine intravascular ultrasonic examinations were performed, qualitative and quantitative analysis of 139 vascular segments was carried out. Despite the fact that mean morphometric indices of open arterial duct and aorta in angiography and intravascular ultrasonic examination had no significant difference, real confidence of the o data was seen only in 13.3% cases for open arterial duct an in 16.7% cases--for aortic coarctation. In 37.5 and 50% patients, respectively, difference in the dimensions was so significant that dictated choice of instruments with difference size. Roentgenoendovascular surgeries were performed in 23 patients with open arterial duct and in 12--with aortic coarctation. Choice of instruments parameters based on data of intravascular ultrasonic examination provided safer and more efficient procedures.

[Detection of DNA packing density in bacteriophages Phi KZ and T4 by atomic force microscopy]. / Opredelenie plotnosti upakovki DNK u bakteriofagov Phi KZ i T4 metodami atomnoi silovoi mikroskopii.

Comparative analysis of DNA packing density in Phi KZ and T4 bacteriophages was carried out by atomic force microscopy. Irrespective of the support (mica or highly ordered pyrrolytic graphite), Phi KZ bacteriophage was compressed stronger than T4. The most probable causes of this difference are analyzed.

Accelerated fractionation of heavy metals in contaminated soils and sediments using rotating coiled columns.

A new approach to performing an accelerated sequential extraction of trace elements from solid samples has been proposed. It has been shown that rotating coiled columns (RCC) earlier used in counter-current chromatography can be successfully applied to the dynamic leaching of heavy metals from soils and sediments. A solid sample was retained in the rotating column as the stationary phase under the action of centrifugal forces while different eluents (aqueous solutions of complexing reagents, mineral salts and acids) were continuously pumped through. The procedure developed is time saving and requires only 4-5 h instead of the several days needed for traditional sequential extraction (TSE), complete automation being possible. Losses of solid sample are minimal. In most cases the recoveries of readily bioavailable and leachable forms of Pb, Zn, and Cd are higher, if a dynamic extraction in RCC is used. Since naturally occurring processes are always dynamic, continuous extraction in RCC may help to estimate the contents of leachable forms and their potential risk for the environment more correctly than batch TSE. The Kersten-Foerstner and McLaren-Crawford leaching schemes have been compared, the former has been found to be preferable.

[Rheolytic thrombectomy using the "Angiojet" complex in treating arterial thrombosis]. / Reoliticheskaia trombéktomiia s ispol'zovaniem kompleksa "Angiodzhet" v lechenii arterial'nykh trombozov.

Results of roentgenendovascular treatment of arterial thrombosis by rheolytic thrombectomy with "Angiojet" are presented. 18 patients (1 woman, 17 men) underwent 19 rheolytic thrombectomies from peripheral arteries. Mean age of patients was 53.3 +/- 3.0 years, time of thrombosis--from 20-30 min to 60 days (mean 121 +/- 17 hours). Thrombectomy was performed from superficial femoral, popliteal or tibial arteries, or from all these vessels simultaneously. In one case thrombus was removed from femoro-popliteal graft. Rheolytic thrombectomy was combined with balloon angioplasty of hemodynamicaly important stenosis, 5 patients underwent implantation of 9 stents. Good and satisfactory results were achieved in 77.8% patients; thrombectomy as the stage of operation was ineffective in one case only. Rheolytic thrombectomy from coronary arteries was performed 3 times, with complete effect in 1 and with partial--also in 1 patient.

Atomic force and electron microscopy of high molecular weight circular DNA complexes with synthetic oligopeptide trivaline.

Intramolecular compact structures formed by high molecular weight circular superhelical DNA molecules due to interaction with synthetic oligopeptide trivaline (1) were studied by atomic force and electron microscopy. Three DNA preparations were used: plasmids pTbol, pRX10 and cosmid 27,877, with sizes 6,120 bp, 10,500 bp and 44,890 bp respectively. Plasmid pTbo1 and pRX10 preparations along with monomers contained significant amount of dimers and trimers. Main structures in all preparations observed were compact particles, which coincide in their appearance and compaction coefficient (3,5-3,7) with triple rings described earlier. The size and structure characteristics of triple rings and other compact particles on atomic force images in general coincide with those obtained by EM (2). AFM (3) images allow to get additional information about the ultrastructural organization and arrangement of DNA fibers within the compact structures. Along with triple rings in pTbol and pRX10-TVP complexes significant amount of compact structures were observed having the shape of two or three compact rings attached to each other by a region of compact fibre. Basing on the data of contour length measurements and the shape of the particles it was concluded that these structures were formed due to compaction of dimeric and trimeric circular DNA molecules. Structures consisting of several attached to each other triple rings were not found for pTbol, pRX10 monomers or cosmid preparations--TVP complexes where only single triple rings were observed. The conclusion is made that initiation of compact fibre formation within the circular molecules depends on the primary structure and for dimeric or trimeric circular molecules two or three compaction initiation points are present, located in each monomer unit within one circular DNA molecule. The nucleotide sequence dependent compaction mechanism providing independent compaction of portions of one circular molecule can be of interest for understanding of DNA compaction processes in vivo.

High resolution mapping DNAs by R-loop atomic force microscopy.

R-loops formed by short RNA transcripts have been imaged by atomic force microscopy (AFM) at a constant force in the height mode. The technique was applied to mapping the human endogenous retrovirus K10 family (HERV-K10) long terminal repeats (LTR) within individual plasmids and cosmids. RNA probes specific for the U3 (384 nt) and U5 (375 nt) LTR regions separated by a span of 200 bp were used for R-loop formation with LTRs located within plasmid (3.8 kb) or cosmid ( approximately 40 kb) DNAs. R-loops stabilized by glyoxal treatment and adsorbed onto the mica surface in the presence of magnesium ions looked like looped out segments of RNA:DNA hybrids. The total yield of R-loops was usually approximately 95%. The RNA:DNA hybrids were found to be 12-15% shorter than the corresponding DNA:DNA duplex. The two regions of the LTR could be easily discerned in the AFM images as clearly separated loops. R-loop positions determined on cosmids by AFM were accurate to approximately 0.5% of the cosmid length. This technique might be easily adapted for mapping various sequences such as gene exons or regulatory regions and for detecting insertions, deletions and rearrangements that cause human genetic diseases.

[Use of an antioxidant complex in the treatment of endotoxicosis in reconstructive surgery of lower limb arteries]. / Primenenie kompleksa antioksidantov dlia lecheniia éndotoksikoza pri rekonstruktivnykh operatsiiakh na arteriiakh nizhnykh konechnostei.

During a dynamic examination of 69 patients with obliterating atherosclerosis of the lower extremity vessels who were subjected to different reconstructive operations on the distal portion of the aorta and arteries the content of the dienic conjugate and malonic dialdehyde was studies both before the operation and during different stages of the latter, as well as at the postoperative period. It was found that the patients had higher content of these substances both before and after operations. A scheme is proposed for the complex antioxidant therapy which allows the degree of endotoxicosis resulting from the activation of lipid peroxidation to be decreased.

[Differences in the cellular surface of hybrid Escherichia coli K12 bacteria inheriting the rfb a3,4 gene of Shigella flexneri detected using atomic-force microscopy]. / Razlichiia v kletochnoi poverkhnosti gibridnykh bakterii Escherichia coli K12, nasleduiushchikh rfb a3,4 gen Shigella flexneri, vyiavliaemye s pomoshch'iu atomno-silovoi mikroskopii.

The cell surface of E. coli initial parent strain K12 J62 his-, chemotype Ra, and E. coli transductant strain K12 J62 his+, acquiring the capacity for synthesizing primary S-specific side chains of the lipopolysaccharide of S. flexneri O-antigen (group-specific factor 3,4), was studied by the method of atomic force microscopy. The comparative analysis of the images of the genetically linked pair of E.coli strains K12 J62 revealed the presence of essential differences in the topography of the surface structure of the compared bacterial cells, differing in their capacity for synthesizing S. flexneri factor 3,4 represented by repeating chains of L-rhamnose and N-acetyl-D-glucosamine.

Determination of the patterns of hexanucleotide distribution along DNA by electron microscopy.

Hexanucleotides containing modified bases (5-methylcytosine and 2-aminoadenine instead of cytosine and adenine) with increased capacities to bind complementary DNA sequences were used to map the distribution of their complementary sequences in a DNA target using electron microscopy. The method used hexamers to initiate DNA polymerase directed DNA synthesis at complementary sequences along a template. DNA synthesis was limited to about 200 residues by using a low concentration of deoxynucleotide precursors. During DNA synthesis a biotin ligand was incorporated to facilitate the subsequent binding of an electron-dense label (streptavidin-labeled colloidal gold particles) into newly synthesized DNA chains. The method can be implemented with commercially available products. The results demonstrate that the approach can be used to compare primary structural features of DNA fragments. The principles of the method can be adapted to a variety of single molecule detection methods such as electron, scanning tunneling, or atomic force microscopies.

[Nonchemical methods of modifying substrates for studying biopolymers with atomic force microscopy]. / Nekhimicheskie metody modifikatsii podlozhek dlia issledovanii biopolimerov metodami atomno-silovoi mikroskopii.

Two simple procedures of DNA molecule fixation on mica for following imaging by the atomic force microscopy were developed. The distinctive features of the procedures are their simplicity, absence of chemical modification stages, and the possibility to obtain the images in air under relative high humidity. Comparison of the features of the images obtained indicated that the procedures developed were competitive with the procedures earlier suggested.