Holliday junction formation by the Borrelia burgdorferi telomere resolvase, ResT: implications for the origin of genome linearity

Spirochetes of the genus Borrelia include the causative agents of Lyme disease and relapsing fever. They possess unusual, highly segmented genomes composed mostly of linear replicons with covalently closed hairpin telomeres. The telomeres are formed from inverted repeat replicated telomere junctions ( rTel s) by the telomere resolvase, ResT. ResT uses a reaction mechanism with similarities to that employed by the type IB topoisomerases and tyrosine recombinases. Here, we report that the relationship of ResT to the tyrosine recombinases extends to the ability to synapse-replicated telomeres and to catalyse the formation of a Holliday junction. We also report that ResT can use asymmetrized substrates that mimic the properties of a recombination site for a tyrosine recombinase, to form Holliday junctions. We propose a model for how this explains the origin of genome linearity in the genus Borrelia.     

Interplay between recombinant Hsp70 and proteasomes: proteasome activity modulation and ubiquitin-independent cleavage of Hsp70

The heat shock protein 70 (Hsp70, human HSPA1A) plays indispensable roles in cellular stress responses and protein quality control (PQC). In the framework of PQC, it cooperates with the ubiquitin-proteasome system (UPS) to clear damaged and dysfunctional proteins in the cell. Moreover, Hsp70 itself is rapidly degraded following the recovery from stress. It was demonstrated that its fast turnover is mediated via ubiquitination and subsequent degradation by the 26S proteasome. At the same time, the effect of Hsp70 on the functional state of proteasomes has been insufficiently investigated. Here, we characterized the direct effect of recombinant Hsp70 on the activity of 20S and 26S proteasomes and studied Hsp70 degradation by the 20S proteasome in vitro. We have shown that the activity of purified 20S proteasomes is decreased following incubation with recombinant human Hsp70. On the other hand, high concentrations of Hsp70 activated 26S proteasomes. Finally, we obtained evidence that in addition to previously reported ubiquitin-dependent degradation, Hsp70 could be cleaved independent of ubiquitination by the 20S proteasome. The results obtained reveal novel aspects of the interplay between Hsp70 and proteasomes.     

Long-term results of chronic occlusion recanalization in patients with coronary heart disease

The study was undertaken to assess the long-term results of recanalization of chronically occluded coronary arteries, by applying drug-eluting stents to patients with coronary heart disease. The study enrolled 585 patients with one-vessel occlusive lesion of one of three great coronary arteries (TIMI 0; occlusion duration, > or = 3 months): 321 patients who underwent successful recanalization of chronic occlusion and further implantation of drug-eluting stents and 264 patients who received drug therapy (a control group). The short- and long-term results of recanalization were investigated. The follow-up averaged 1095 +/- 36 days; reexaminations were made after 1, 2, and 3 years. The direct success rate of recanalization of chronically occluded coronary arteries was 84.9% (321/378). The results of a 3-year follow-up showed the efficiency and expediency of endovascular recanalization of chronic occlusions: the invasively treated patients had the symptoms of angina pectoris and heart failure significantly less frequently, showed higher exercise tolerance and a less need for antianginal therapy, and had a better long-term prognosis.     

Stimulus-Selective Regulation of Human Mast Cell Gene Expression,Degranulation and Leukotriene Production by Fluticasone and Salmeterol

Despite the fact that glucocorticoids and long acting beta agonists are effective treatments for asthma, their effects on human mast cells (MC) appear to be modest. Although MC are one of the major effector cells in the underlying inflammatory reactions associated with asthma, their regulation by these drugs is not yet fully understood and, in some cases, controversial. Using a human immortalized MC line (LAD2), we studied the effects of fluticasone propionate (FP) and salmeterol (SM), on the release of early and late phase mediators. LAD2 cells were pretreated with FP (100 nM), SM (1 µM), alone and in combination, at various incubation times and subsequently stimulated with agonists substance P, C3a and IgE/anti-IgE. Degranulation was measured by the release of β-hexosaminidase. Cytokine and chemokine expression were measured using quantitative PCR, ELISA and cytometric bead array (CBA) assays. The combination of FP and SM synergistically inhibited degranulation of MC stimulated with substance P (33% inhibition compared to control, n = 3, P<.05). Degranulation was inhibited by FP alone, but not SM, when MC were stimulated with C3a (48% inhibition, n = 3, P<.05). As previously reported, FP and SM did not inhibit degranulation when MC were stimulated with IgE/anti-IgE. FP and SM in combination inhibited substance P-induced release of tumor necrosis factor (TNF), CCL2, and CXCL8 (98%, 99% and 92% inhibition, respectively, n = 4, P<.05). Fluticasone and salmeterol synergistically inhibited mediator production by human MC stimulated with the neuropeptide substance P. This synergistic effect on mast cell signaling may be relevant to the therapeutic benefit of combination therapy in asthma.     

A phased poly-linker for cloning and expression of genes

15 oligodeoxynucleotides were synthesized using the phosphotriether technique which were subsequently enzymatically ligated in polylinker with subsequent phasing of left and right sides. Based on the phased polylinker a series of vehicles for the gene cloning and expression was constructed. The vectors of pRK series contain all three variants of polylinker with the frame shift of the reading frame for 1, 2, or 3 nucleotides in both chains. The obtained polylinkers do not effect the enzymatic activity of the beta-galactosidase alpha-peptide. Structure of the phased polylinker was confirmed by Maxam and Gilbert's sequencing method.     

Investigation of mechanisms of interaction between inulinase from Kluyveromyces marxianus and the matrices of ion-exchange resins and fiber

It is established that ion exchange resins AV-17-2P, KU-2, AV-16-GS, AM 21A, IMAC-HP, PUROLITE and fiber VION KN-1 can be applied as carriers for inulinase immobilization. The analysis of IR spectra for an enzyme, carriers and heterogeneous enzyme preparations showed that inulinase binding to matrices of various carriers occurs in general through electrostatic interactions. It is assumed that the mechanisms of interaction between inulinase from Kluyveromyces marxianus and the matrices of cation and anion exchange polymers differ essentially from each other: different sites of protein molecule take part in adsorption that causes various conformational reorganizations in an enzyme molecule.     

MAGO-IX Experiment

The results of the last (in the thermonuclear program “Magnetic compression”) MAGO-IX experiment with a plasma chamber including a third compartment designed to compress plasma with a converging liner are presented. An X-ray pulse consisting of an intense peak of 1-μs duration, followed by a low-intensity tail with a duration of more than 10 μs, was recorded. In the MAGO-IX experiment, the neutrons were generated mainly in the third compartment. A neutron yield of 2 × 10¹² was obtained. The results demonstrate that the expected compression of preheated plasma in chambers similar to MAGO-IX is promising for achieving thermonuclear ignition.     

The clinical and economic efficacies of short courses of azithromycin in acute sinusitis]

A randomized study of a 3-day course of azithromycin therapy (500 mg once daily) vs. a 10-day course of co-amoxiclav therapy (625 mg thrice daily) in patients with acute sinusitis was performed with an account of the GCP criteria. One hundred patients in 2 groups each of 50 persons were enrolled. The estimates of the patient body temperature, headache, pain on palpation in the area of the accessory nasal sinuses, nasal cavity stuffing, nasal discharge nature and the nose mucous membrane appearance were recorded prior to the treatment, in 72 hours and on the 10th-12th and 26th-30th days of the treatment. The microbiological analysis of the punctate from the accessory nasal sinuses was undertaken before the antibiotic therapy and 72 hours after its start. The economic analysis included the cost of the antibiotic therapy course, hospitalization term, medical manipulations and laboratory tests as well as the cost/efficacy index. The frequency of the relapses within 6 months after the cure was estimated in the two groups compared. In 72 hours and on the 10th-12th days after the treatment start the efficacy of azithromycin was significantly higher than that of co-amoxiclav. The cure was stated in 41 (82 per cent) and 26 (52 per cent) patients on the 10th-12th days, in 6 (12 per cent) and 21 (42 per cent) patients the improvement was stated and the fail was stated in 3 (6 per cent) and 2 (4 per cent) patients respectively. The efficacy of the drugs on the 26th-30th days after the treatment start did not differ. The isolates of Staphylococcus aureus and Streptococcus pyogenes were the main pathogens. The bacteriologic eradication was recorded in 29 (90.6 per cent) patients treated with azithromycin and only in 18 (69.2 per cent) patients treated with co-amoxiclav. Adverse reactions and relapses of the disease within 6 months after the cure were more frequent in the patients treated with co-amoxiclav. The cost of the azithromycin therapy was significantly lower. It was shown that the shortened course of the azithromycin therapy provided earlier cure of the patients with acute sinusitis, better tolerance of the drug, less frequent adverse reactions, lower cost as compared to the use of co-amoxiclav and no relapses.