Cross-specificity of protective human antibodies against Klebsiella pneumoniae LPS O-antigen

Humoral immune responses to microbial polysaccharide surface antigens can prevent bacterial infection but are typically strain specific and fail to mediate broad protection against different serotypes. Here we describe a panel of affinity-matured monoclonal human antibodies from peripheral blood immunoglobulin M-positive (IgM⁺) and IgA⁺ memory B cells and clonally related intestinal plasmablasts, directed against the lipopolysaccharide (LPS) O-antigen of Klebsiella pneumoniae, an opportunistic pathogen and major cause of antibiotic-resistant nosocomial infections. The antibodies showed distinct patterns of in vivo cross-specificity and protection against different clinically relevant K. pneumoniae serotypes. However, cross-specificity was not limited to K. pneumoniae, as K. pneumoniae-specific antibodies recognized diverse intestinal microbes and neutralized not only K. pneumoniae LPS but also non-K. pneumoniae LPS. Our data suggest that the recognition of minimal glycan epitopes abundantly expressed on microbial surfaces might serve as an efficient humoral immunological mechanism to control invading pathogens and the large diversity of the human microbiota with a limited set of cross-specific antibodies.

Preventive andTherapeutic Effects of Chlorhexidine Containing Varnish on Candida Biofilm

The aim of the study was to assess the preventive and therapeutic efficacy of a sustained-release varnish (SRV) Cervitec Plus� compared with Corsodyl� mouthwash against Candida albicans, Candida parapsilosis, Candida tropicalis and Candida glabrata on acrylate surfaces. Nystatin as the positive control, and sterile saline solution as the negative control, were used. To examine the preventive efficacy of the agents, Candida biofilms were developed in Sabouraud liquid medium, and mature biofilms were treated with the antifungal. To investigate the preventive efficacy, the agents were applied to the wells of the plates and the biofilms were grown in the treated wells. To determine the metabolic activity of biofilms, the XTT-assay was used. In the case of C. albicans and C. parapsilosis, the most effective therapeutic product was Corsodyl� followed by Cervitec Plus� and Nystatin. The differences were statistically significant when Corsodyl� was compared to Nystatin ( p � 0.05). In relation to C. tropicalis and C. glabrata, Corsodyl� showed the greatest therapeutic efficacy followed by Nystatin and Cervitec Plus�. For both species, the results of Corsodyl� and Cervitec Plus� showed statistically significant difference ( p � 0.05). The most effective preventive product for each examined Candida species was Nystatin, followed by Cervitec Plus� and Corsodyl�. Significant differences were between Nystatin and Corsodyl� (p � 0.05). The preventive and therapeutic efficacy of Cervitec Plus� and Corsodyl�, against the examined Candida species, was detected. Because of the disadvantageous side-effects of Nystatin, Cervitec Plus� can be considered as an alternative preventive agent against Candida species.

Mycoplasma infection followed by time-lapse microscopy

Early detection of mycoplasma infection is crucial for saving precious often irreplaceable data from the tissues of patients. Mycoplasma infections cause diseases in the upper and lower respiratory tracts, urethritis in men resulting in painful dysuria, urgency and urethral discharge. Cough, fever, headache, urethritis may persist for several weeks and convalescence is slow. The symptoms of these diseases are aggravated by the detection of mycoplasma infections, that takes either a long time, besides being expensive or is specific and restricted to only a limited number of contaminant strains. Mycoplasmas are hard to detect visually but could be seen and followed by time-lapse microscopy. Our hypothesis is that one can detect mycoplasma infection irrespective of its origin and type of mycoplasma. Main lines of supporting evidence are provided by the time-lapse microscopy showing dynamic morphological alterations caused by mycoplasmas before changes in human cell cultures become visible. Morphometric measurements of mycoplasma infections revealed four subphases: i) detachment of infected cells, ii) aggregation, iii) biofilm formation and iv) shrinkage of infected cells. The applicability of time-lapse microscopy for the detection of mycoplasma infection was validated by a mycoplasma test Kit. Most important implications related to morphometric parameters include the observation of mycoplasma infected cultures for an extended period of time instead of applying static snap-shot microscopy. A reliable method is offered to estimate the time of mycoplasma exposure that elapsed during the cell growth. This microphotometric approach served a more economical detection of mycoplasma contamination at its early stage of cell growth and spread, irrespective of the origin of contaminated serum, without defining the type of mycoplasma.

Exploring the binding pathways of the 14-3-3ζ protein: Structural and free-energy profiles revealed by Hamiltonian replica exchange molecular dynamics with distancefield distance restraints

The 14-3-3 protein family performs regulatory functions in eukaryotic organisms by binding to a large number of phosphorylated protein partners. Whilst the binding mode of the phosphopeptides within the primary 14-3-3 binding site is well established based on the crystal structures of their complexes, little is known about the binding process itself. We present a computational study of the process by which phosphopeptides bind to the 14-3-3ζ protein. Applying a novel scheme combining Hamiltonian replica exchange molecular dynamics and distancefield restraints allowed us to map and compare the most likely phosphopeptide-binding pathways to the 14-3-3ζ protein. The most important structural changes to the protein and peptides involved in the binding process were identified. In order to bind phosphopeptides to the primary interaction site, the 14-3-3ζ adopted a newly found wide-opened conformation. Based on our findings we additionally propose a secondary interaction site on the inner surface of the 14-3-3ζ dimer, and a direct interference on the binding process by the flexible C-terminal tail. A minimalistic model was designed to allow for the efficient calculation of absolute binding affinities. Binding affinities calculated from the potential of mean force along the binding pathway are in line with the available experimental estimates for two of the studied systems.

Low Efficacy of Antibiotics Against Staphylococcus aureus Airway Colonization in Ventilated Patients

Background

Airway-colonization by Staphylococcus aureus predisposes to the development of ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). Despite extensive antibiotic treatment of intensive care unit patients, limited data are available on the efficacy of antibiotics on bacterial airway colonization and/or prevention of infections. Therefore, microbiologic responses to antibiotic treatment were evaluated in ventilated patients.

Methods

Results of semiquantitative analyses of S. aureus burden in serial endotracheal-aspirate (ETA) samples and VAT/VAP diagnosis were correlated to antibiotic treatment. Minimum inhibitory concentrations of relevant antibiotics using serially collected isolates were evaluated.

Results

Forty-eight mechanically ventilated patients who were S. aureus positive by ETA samples and treated with relevant antibiotics for at least 2 consecutive days were included in the study. Vancomycin failed to reduce methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus (MSSA) burden in the airways. Oxacillin was ineffective for MSSA colonization in approximately 30% of the patients, and responders were typically coadministered additional antibiotics. Despite antibiotic exposure, 15 of the 39 patients (approximately 38%) colonized only by S. aureus and treated with appropriate antibiotic for at least 2 days still progressed to VAP. Importantly, no change in antibiotic susceptibility of S. aureus isolates was observed during treatment. Staphylococcus aureus colonization levels inversely correlated with the presence of normal respiratory flora.

Conclusions

Antibiotic treatment is ineffective in reducing S. aureus colonization in the lower airways and preventing VAT or VAP. Staphylococcus aureus is in competition for colonization with the normal respiratory flora. To improve patient outcomes, alternatives to antibiotics are urgently needed.

A Consensus-Based Set of Measures for Oral Health Care

Increasingly more responsive and accountable health care systems are demanded, which is characterized by transparency and explicit demonstration of competence by health care providers and the systems in which they work. This study aimed to establish measures of oral health for transparent and explicit reporting of routine data to facilitate more patient-centered and prevention-oriented oral health care. To accomplish this, an intermediate objective was to develop a comprehensive list of topics that a range of stakeholders would perceive as valid, important, and relevant for describing oral health and oral health care. A 4-stage approach was used to develop the list of topics: 1) scoping of literature and its appraisal, 2) a meeting of experts, 3) a 2-stage Delphi process (online), and 4) a World Café discussion. The aim was to create consensus through structured conversations via a range of stakeholders (general dental practitioners, patients, insurers, and policy makers) from the Netherlands, Germany, the United Kingdom, Ireland, Hungary, and Denmark. The study was part of the ADVOCATE project, and it resulted in a list of 48 topics grouped into 6 clusters: 1) access to dental care, 2) symptoms and diagnosis, 3) health behaviors, 4) oral treatments, 5) oral prevention, and 6) patient perception. All topics can be measured, as they all have a data source with defined numerators and denominators. This study is the first to establish a comprehensive and multiple-stakeholder consented topic list designed for guiding the implementation of transparent and explicit measurement of routine data of oral health and oral health care. Successful measurement within oral health care systems is essential to facilitate learning from variation in practice and outcomes within and among systems, and it potentiates improvement toward more patient-centered and prevention-oriented oral health care.

Chemically Induced Cell Cycle Arrest in Perfusion Cell Culture

In contrast to most present methods, continuous imaging of live cells would require full automation in each processing step. As an integrated system that would meet all requirements does not exist, we have established a long-term scanning-perfusion platform that: (a) replaces old medium with fresh one, (b) bypasses physical contact with the cell culture during continuous cell growth, (c) provides uninterrupted photomicrography of single cells, and (d) secures near physiological conditions and sterility up to several weeks. The system was validated by synchronizing cells using serum starvation and butyrate-induced cell cycle arrest of HaCaT cells.

In Situ Electron Microscopy of Lactomicroselenium Particles in Probiotic Bacteria

Electron microscopy was used to test whether or not (a) in statu nascendi synthesized, and in situ measured, nanoparticle size does not differ significantly from the size of nanoparticles after their purification; and (b) the generation of selenium is detrimental to the bacterial strains that produce them. Elemental nano-sized selenium produced by probiotic latic acid bacteria was used as a lactomicroselenium (lactomicroSel) inhibitor of cell growth in the presence of lactomicroSel, and was followed by time-lapse microscopy. The size of lactomicroSel produced by probiotic bacteria was measured in situ and after isolation and purification. For these measurements the TESLA BS 540 transmission electron microscope was converted from analog (aTEM) to digital processing (dTEM), and further to remote-access internet electron microscopy (iTEM). Lactobacillus acidophilus produced fewer, but larger, lactomicroSel nanoparticles (200-350 nm) than Lactobacillus casei (L. casei), which generated many, smaller lactomicroSel particles (85-200 nm) and grains as a cloudy, less electrodense material. Streptococcus thermophilus cells generated selenoparticles (60-280 nm) in a suicidic manner. The size determined in situ in lactic acid bacteria was significantly lower than those measured by scanning electron microscopy after the isolation of lactomicroSel particles obtained from lactobacilli (100-500 nm), but higher relative to those isolated from Streptococcus thermopilus (50-100 nm). These differences indicate that smaller lactomicroSel particles could be more toxic to the producing bacteria themselves and discrepancies in size could have implications with respect to the applications of selenium nanoparticles as prebiotics.

Activation of GCN2 kinase by ribosome stalling links translation elongation with translation initiation

Ribosome stalling during translation has recently been shown to cause neurodegeneration, yet the signaling pathways triggered by stalled elongation complexes are unknown. To investigate these pathways we analyzed the brain of C57BL/6J-Gtpbp2^nmf205-/- mice in which neuronal elongation complexes are stalled at AGA codons due to deficiencies in a tRNA^Arg_UCU tRNA and GTPBP2, a mammalian ribosome rescue factor. Increased levels of phosphorylation of eIF2α (Ser51) were detected prior to neurodegeneration in these mice and transcriptome analysis demonstrated activation of ATF4, a key transcription factor in the integrated stress response (ISR) pathway. Genetic experiments showed that this pathway was activated by the eIF2α kinase, GCN2, in an apparent deacylated tRNA-independent fashion. Further we found that the ISR attenuates neurodegeneration in C57BL/6J-Gtpbp2^nmf205-/- mice, underscoring the importance of cellular and stress context on the outcome of activation of this pathway. These results demonstrate the critical interplay between translation elongation and initiation in regulating neuron survival during cellular stress.

DOI:http://dx.doi.org/10.7554/eLife.14295.001

Information stored in DNA is used to make proteins in a two-step process. First, the DNA is copied to make molecules of messenger ribonucleic acid (or messenger RNA for short). Next, machines called ribosomes use the messenger RNAs as templates to assemble chains of amino acids – the building blocks of proteins – in a process called translation. Another type of RNA molecule called transfer RNA carries each amino acid to the ribosomes. If a specific transfer RNA is not available for translation at the right time, the ribosome might stall as it moves along the messenger RNA. At this point, the ribosome needs to be restarted or it will fall off the mRNA without finishing the protein.

In 2014, a group of researchers reported that certain types of brain cells are very sensitive to ribosome stalling, and tend to die if translation does not continue. A protein called GTPBP2 was shown to play an important role in restarting stalled ribosomes in these cells. Here, Ishimura, Nagy et al. – including some of the researchers from the earlier work – investigated the molecular pathways that ribosome stalling triggers in brain cells using mutant mice that lacked the GTPBP2 protein. The experiments show that ribosome stalling activates an enzyme known as GCN2, which was already known to sense other types of malfunctions in cellular processes.

Ishimura, Nagy et al. also show that GCN2 triggers stress responses in the cells by activating a communication system called the ATF4 pathway. This pathway protects the cells from damage, and its absence results in more rapid cell deterioration and death. The next challenges are to understand the exact mechanism by which GCN2 senses stalled ribosomes, and to find out how ribosome stalling causes the death of brain cells.

DOI:http://dx.doi.org/10.7554/eLife.14295.002

Multidimensional Analysis of 16 Glucose Isomers by Ion Mobility Spectrometry

Diastereomeric adducts comprising an enantiomerically pure monosaccharide analyte, a peptide, and/or an amino acid and a divalent metal ion (for 16 different monosaccharide isomers) are generated by electrospray ionization and analyzed by combined ion mobility spectrometry-mass spectrometry (IMS-MS) techniques. Mobility distributions of [l-Ser + M + H](+) (where l-Ser is l-serine and M is a given monosaccharide), [l-Phe-Gly + M + H](+) (where l-Phe-Gly is l-phenylalanine-glycine), and [Mn(II) + (l-Phe-Gly - H) + M](+) complex ions are used to determine collision cross sections (ccs in Å(2)), and groups of cross sections for different clusters are proposed as means of identifying the sugar isomers. Within one type of complex, variations in ccs do not always allow delineation between the 16 glucose isomers, but interestingly, when ccs of three different ions are combined as a spatial vector, enantiomers are partially resolved. As a result of this analysis, l-glucose, d-glucose, l-allose, d-allose, d-gulose, d-galactose, and l-mannose are delineated, and for all eight enantiomeric pairs, d and l entities display different coordinates. In addition, different combinations of amino acids, peptide, and metal ions are surveyed, and the potential for yielding unique coordinates for the generated diastereomeric complexes is assessed.

Radiosurgery for cerebral cavernomas

The role of stereotactic radiosurgery (SRS) in the management of cerebral cavernomas (CCMs) remains controversial. However, during the last decade the increasing knowledge on natural history and numerous publications from SRS centers using modern treatment protocols has been changing the initial resistance of the neurosurgical community. Unfortunately, the quality of publications on CCM SRS remains heterogeneous. Controversies arise from the lack of control groups, the different definition of hemorrhage, heterogeneous patient populations, and poor definition of treatment protocols. The key for proper interpretation of results is the understanding of the natural history of CCMs, which is varied both according to anatomical location and the presence or absence of previous hemorrhage. Hemispheric lesions appear to be more benign with lower annual bleed rate and risk of persisting disability, whereas those found in the thalamus, basal ganglia and brainstem typically have higher rebleed risk resulting in higher cumulative morbidity following subsequent hemorrhages. However, we are still unable at presentation to predict the future behavior of an individual lesion. In the present paper we critically review and analyze the modern SRS literature on CCMs. The expanding number of available data with current treatment protocols strongly supports the initial intuition that SRS is an effective treatment alternative for deep-seated CCMs with multiple hemorrhages reducing pretreatment annual rebleed rates from 32% pre-treatment to 1.5% within 2 years after treatment (N.=197). Moreover, it appears to stabilize lesions with no more than one bleed, and it is also effective for CCMs causing therapy resistant epilepsy especially if applied within 3 years after presentation. In modern SRS series the rate of persisting adverse radiation effects is low, resulting only in mild morbidity even in deep-seated lesions (4.16%, N.=376), and morbidity caused by post-treatment hemorrhages is also low (5.3%, N.=132). Admittedly, there is no high quality evidence to define the relative roles of microsurgery, SRS and wait-and-see policy in the management of detected CCMs at present. However, based on increasing positive experience, we recommend early SRS soon after presentation in neurologically intact or minimally disabled patients harboring deep-seated CCMs, because waiting for the cumulative morbidity of the natural history to justify an otherwise low-risk intervention does not serve the patient well.

Dynamic Reorganization of Vortex Matter into Partially Disordered Lattices

We report structural evidence of dynamic reorganization in vortex matter in clean NbSe(2) by joint small-angle neutron scattering and ac susceptibility measurements. The application of oscillatory forces in a transitional region near the order-disorder transition results in robust bulk vortex lattice configurations with an intermediate degree of disorder. These dynamically originated configurations correlate with intermediate pinning responses previously observed, resolving a long-standing debate regarding the origin of such responses.

Increased levels of anti-heat-shock protein 60 (anti-Hsp60) indicate endothelial dysfunction, atherosclerosis and cardiovascular diseases in patients with mixed connective tissue disease

Heat-shock protein 60 (Hsp60) has been shown to provoke inflammation, and anti-Hsp60 may facilitate the development of atherosclerosis. In this study, we have investigated 30 patients with mixed connective tissue disease (MCTD) and assessed anti-Hsp60 and their relationship to cardiovascular diseases (CVD). Out of 30 patients with MCTD, 15 had CVDs. Anti-Hsp60 antibody was determined by enzyme-linked immunosorbent assay. Since endothelial dysfunction and accelerated atherosclerosis are characteristic to MCTD, a wide array of MCTD-, endothelial dysfunction- and CVD-associated parameters was investigated: serum lipid levels, paraoxonase activity (PON1), rich nuclear ribonucleoprotein U1 (anti-U1RNP), anti-endothelial cell antibodies, anti-cardiolipin and anti-β2-glycoprotein I antibody isotypes (anti-CL and anti-β2GPI), endothelin-1 (ET-1) levels, also intima-media thickness (IMT), a quantitative indicator of atherosclerosis. In MCTD, anti-Hsp60 antibody levels were significantly higher than in healthy individuals (p < 0.02). MCTD patients with CVD had significantly higher levels of anti-Hsp60 compared to MCTD without CVD (p = 0.001). Patients with MCTD had significantly lower high-density lipoprotein cholesterol (p = 0.02) and PON activity (p < 0.001), and significantly increased systolic (p < 0.0002) and diastolic (p < 0.001) blood pressure compared to healthy individuals. Anti-U1RNP levels (p < 0.002) and IMT were higher in patients compared to controls (p = 0.002). The CVD-positive MCTD patients had increased anti-Hsp60 (p < 0.0013), anti-CL IgG (p = 0.0005), ET-1 serum concentration (p < 0.05) and IMT levels (p < 0.001) compared to MCTD patients without CVD. Anti-Hsp60 showed a strong correlation with anti-oxLDL (r = 0.36, p = 0.01) and serum ET-1 (r = 0.62, p < 0.001) and negative correlation with PON activity (r = -0.47, p = 0.01). Anti-Hsp60 indicates endothelial injury, CVD, and can function as a novel atherosclerotic risk factor, also a valuable diagnostic marker in patients with MCTD.