Comparative binding of soluble fragments (derCD23, sCD23, and exCD23) of recombinant human CD23 to CD21 (SCR 1-2) and native IgE, and their effect on IgE regulation

IgE, responsible for type I hypersensitivities, is regulated by interactions between its receptor, CD23, and co-receptor CD21. To examine comparative binding of recombinant human CD21 SCR 1-2 and native human IgE to CD23 plus the effect of CD23 on IgE production, we engineered recombinant soluble human CD23 fragments; (1) derCD23, (2) sCD23 and (3) exCD23, formed in vivo by proteolysis. SPR analysis revealed a progressive increment in affinity of soluble fragments for IgE, upon increasing length of CD23 “stalk” domain, exCD23 > sCD23 > derCD23. Soluble CD23 fragments and their oligomeric state are shown to fine-tune the immune response. Oligomers appear more important in enhancing IgE synthesis and monomers lacking the tail residues fail to bind CD21 yet bind membrane IgE and down-regulate IgE synthesis. Co-ligation of membrane IgE and CD21 through soluble CD23 monomers is disturbed. This study supports anti-allergic therapies involving stabilizing membrane CD23, or preventing shedding of soluble CD23.     

Comparing COI and ITS as DNA barcode markers for mushrooms and allies (Agaricomycotina)

DNA barcoding is an approach to rapidly identify species using short, standard genetic markers. The mitochondrial cytochrome oxidase I gene (COI) has been proposed as the universal barcode locus, but its utility for barcoding in mushrooms (ca. 20,000 species) has not been established. We succeeded in generating 167 partial COI sequences (~450 bp) representing ~100 morphospecies from ~650 collections of Agaricomycotina using several sets of new primers. Large introns (~1500 bp) at variable locations were detected in ~5% of the sequences we obtained. We suspect that widespread presence of large introns is responsible for our low PCR success (~30%) with this locus. We also sequenced the nuclear internal transcribed spacer rDNA regions (ITS) to compare with COI. Among the small proportion of taxa for which COI could be sequenced, COI and ITS perform similarly as a barcode. However, in a densely sampled set of closely related taxa, COI was less divergent than ITS and failed to distinguish all terminal clades. Given our results and the wealth of ITS data already available in public databases, we recommend that COI be abandoned in favor of ITS as the primary DNA barcode locus in mushrooms.     

Efficacy and safety of moxifloxacin in acute exacerbations of chronic bronchitis: a prospective, multicenter, observational study (AVANTI)

Background

Acute exacerbations of chronic bronchitis (AECB), including chronic obstructive pulmonary disease (AECOPD), represent a substantial patient burden. Few data exist on outpatient antibiotic management for AECB/AECOPD in Eastern/South Eastern Europe, in particular on the use of moxifloxacin (Avelox®), although moxifloxacin is widely approved in this region based on evidence from international clinical studies.

Methods

AVANTI (AVelox® in Acute Exacerbations of chroNic bronchiTIs) was a prospective, observational study conducted in eight Eastern European countries in patients?>?35 years with AECB/AECOPD to whom moxifloxacin was prescribed. In addition to safety and efficacy outcomes, data on risk factors and the impact of exacerbation on daily life were collected.

Results

In the efficacy population (N?=?2536), chronic bronchitis had been prevalent for?>?10 years in 31.4% of patients and 66.0% of patients had concomitant COPD. Almost half the patients had never smoked, in contrast to data from Western Europe and the USA, where only one-quarter of COPD patients are non-smokers. The mean number of exacerbations in the last 12 months was 2.7 and 26.3% of patients had been hospitalized at least once for exacerbation. Physician compliance with the recommended moxifloxacin dose (400 mg once daily) was 99.6%. The mean duration of moxifloxacin therapy for the current exacerbation (Anthonisen type I or II in 83.1%; predominantly type I) was 6.4?±?1.9 days. Symptom improvement was reported after a mean of 3.4?±?1.4 days. After 5 days, 93.2% of patients reported improvement and, in total, 93.5% of patients were symptom-free after 10 days. In the safety population (N?=?2672), 57 (2.3%) patients had treatment-emergent adverse events (TEAEs) and 4 (0.15%) had serious TEAEs; no deaths occurred. These results are in line with the known safety profile of moxifloxacin.

Conclusions

A significant number of patients in this observational study had risk factors for poor outcome, justifying use of moxifloxacin. The safety profile of moxifloxacin and its value as an antibiotic treatment were confirmed. Physicians complied with the recommended 400 mg once-daily dose in a large proportion of patients, confirming the advantages of this simple dosing regimen.

Trial registration

ClinicalTrials.gov identifier: NCT00846911     

Features of Interspecific Contacts and Hybridization of Ground Squirrels (Marmotinae,Sciuridae, Rodentia) in Mongolia

Using molecular genetic methods, we investigated the secondary contact zones of two pairs of species of ground squirrels of Mongolia. In common colonies of marmots M. sibirica and M. baibacina, we revealed a high frequency of occurrence of hybrid individuals that were viable and fertile. A hybridization between S. alaschanicus and S. pallidicauda was sporadic in nature. The hypothesis about an extensive hybrid zone in these species of ground squirrels was not confirmed. An occupation of suboptimal biotopes by individuals of different species was the main factor contributing to hybridization in both case. The complex social behavior in marmots affected on the localization and diffusion of the hybridization process.     

Quinoline Hydrazone Derivatives as New Antibacterials against Multidrug Resistant Strains

To develop novel antimicrobial agents a series of 2(4)-hydrazone derivatives of quinoline were designed, synthesized and tested. QSAR models of the antibacterial activity of quinoline derivatives were developed by the OCHEM web platform using different machine learning methods. A virtual set of quinoline derivatives was verified with a previously published classification model of anti-E. coli activity and screened using the regression model of anti-S. aureus activity. Selected and synthesized 2(4)-hydrazone derivatives of quinoline exhibited antibacterial activity against the standard and antibiotic-resistant S. aureus and E. coli strains in the range from 15 to 30 mm by the diameter of growth inhibition zones. Molecular docking showed the complex formation of the studied compounds into the catalytic domain of dihydrofolate reductase with an estimated binding affinity from −8.4 to −9.4 kcal/mol.     

Compensation of DNA stabilization and destabilization effects caused by cisplatin is partially disturbed in alkaline medium

Binding of the antitumor compound cisplatin to DNA locally distorts the double helix. These distortions correlate with a decrease in DNA melting temperature (Tm). However, the influence of cisplatin on DNA stability is more complex because it decreases the DNA charge density. In this way, cisplatin increases the melting temperature and partially compensates for the destabilizing influence of structural distortions. The stabilization is stronger at low Na+ ion concentration. Due to this compensation, the total decrease in the DNA melting temperature after cisplatin binding is much lower than the decrease caused by the distortions themselves, especially at low [Na+]. It is shown in this study that, besides Na+ concentration, pH also strongly influences the value of a change in the melting temperature caused by cisplatin. In alkaline medium (pH=10.5-10.8), a fall in the melting temperature caused by platination is enhanced several times with respect to neutral medium. Such a stronger drop in Tm is explained by a decrease in pK values of base pairs caused by lowering the charge density under platination that facilitates proton release. At neutral pH, the proton release is low for both control and platinated DNA and does not influence the melting behavior. Therefore, lowering in the charge density under platination, besides stabilization, gives additional destabilization just in alkaline medium. Destabilization caused by structural distortions due to this pH induced compensation of stabilizing effect is more pronounced. In the presence of carbonate ion, destabilization caused by high pH value is strengthened. As a decrease in DNA charge density, interstrand crosslinking caused by cisplatin also increases the DNA stability due to loss in the entropy of the melted state. However, computer modeling of DNA stability demonstrates that interstrand crosslinks formed by cisplatin do not stabilize long DNA. It is shown that the increase in Tm caused by interstrand crosslinking itself is compensated for by a local destabilization of the double helix at the sites of location of interstrand crosslinks formed by cisplatin.     

Lower expression of mRNA for interferon-gamma in T helper cells of children with newly diagnosed lymphomas

The complex interactions between cancer and host cells are far from being fully elucidated. Assessment of Th1/Th2/Th3/Tr1 balance is an interesting approach to explain immunological disturbances in lymphomas. The aim of our study was to assess mRNA for pro- and anti-inflammatory cytokines in T-cells in 20 children with Hodgkin- and non-Hodgkin lymphomas. CD4+ and CD8+ cells were isolated from whole peripheral blood and four different cytokine mRNA levels (IFN-gamma, IL-10, IL-4, TGF-beta) were determined by real-time PCR technique. Comparing to the control group, we found lower expression of mRNA for IFN-gamma in CD4+ cells at the time of lymphoma diagnosis. It may be one of the pathogenetic mechanisms of impaired immunity in these patients.     

Structural dynamics of precursor and product of the RNA enzyme from the hepatitis delta virus as revealed by molecular dynamics simulations

The hepatitis delta virus (HDV) ribozyme is a self-cleaving RNA enzyme involved in the replication of a human pathogen, the hepatitis delta virus. Recent crystal structures of the precursor and product of self-cleavage, together with detailed kinetic analyses, have led to hypotheses on the catalytic strategies employed by the HDV ribozyme. We report molecular dynamics (MD) simulations (approximately 120 ns total simulation time) to test the plausibility that specific conformational rearrangements are involved in catalysis. Site-specific self-cleavage requires cytidine in position 75 (C75). A precursor simulation with unprotonated C75 reveals a rather weak dynamic binding of C75 in the catalytic pocket with spontaneous, transient formation of a H-bond between U-1(O2') and C75(N3). This H-bond would be required for C75 to act as the general base. Upon protonation in the precursor, C75H+ has a tendency to move towards its product location and establish a firm H-bonding network within the catalytic pocket. However, a C75H+(N3)-G1(O5') H-bond, which would be expected if C75 acted as a general acid catalyst, is not observed on the present simulation timescale. The adjacent loop L3 is relatively dynamic and may serve as a flexible structural element, possibly gated by the closing U20.G25 base-pair, to facilitate a conformational switch induced by a protonated C75H+. L3 also controls the electrostatic environment of the catalytic core, which in turn may modulate C75 base strength and metal ion binding. We find that a distant RNA tertiary interaction involving a protonated cytidine (C41) becomes unstable when left unprotonated, leading to disruptive conformational rearrangements adjacent to the catalytic core. A Na ion temporarily compensates for the loss of the protonated hydrogen bond, which is strikingly consistent with the experimentally observed synergy between low pH and high Na+ concentrations in mediating residual self-cleavage of the HDV ribozyme in the absence of divalents.     

Monocytes in children with leukemias and lymphomas -- down-regulation of HLA and costimulatory molecules

The aim of the study was to evaluate the function of monocytes in children with leukemias and lymphomas based on the expression of critical costimulatory, activatory and adhesion molecules (CD80, CD86, HLA-DR and CD54 = ICAM-1), estimated with tricolor flow cytometry. In comparison to the control group we found a lower percentage of monocytes with costimulatory molecules (CD80 before and CD86 after lipopolysaccharide stimulation) at the time of diagnosis and of monocytes with HLA-DR molecules after remission induction. We also noted a lower percentage of monocytes with HLA-DR expression in the group with severe or therapy resistant infections. The results of our investigation suggest some defect in costimulation and antigen presentation in lymphoproliferative diseases in children.