Mycoplasma hominis variable adherence-associated antigen: a major adhesin and highly variable surface membrane protein

Mycoplasma hominis is a member of the genus mycoplasma and has only been isolated from humans. It is most frequently isolated from the urogenital tract in the absence of symptoms, but has been isolated from wounds, brain abscess, inflamed joints, blood and placenta from pregnancy with adverse outcomes (especially preterm birth and occasionally term stillbirth). Controversy surrounds whether this organism is a commensal or a pathogen; however, Mycoplasma hominis has been shown to induce preterm birth and foetal lung injury in an experimental primate model as a sole pathogen. These bacteria are known to exist as a parasitic infection, due to a number of missing synthetic and metabolism pathway enzymes from their minimal genome; therefore, the ability to adhere to host cells is important. Here we provide a review that clarifies the different nomenclature (variable adherence-associated antigen and P50) that has been used to investigate the major surface adhesin for this organism, as well as reported mechanisms responsible for turning off its expression. Variation in the structure of this protein can be used to separate strains into six categories, a method that we were able to use to distinguish and characterise 12 UK strains isolated from between 1983 and 2012. We propose that the Vaa should be used in further investigations to determine if commensal populations and those that are associated with disease utilise different forms of this adhesin, as this is under-studied and identification of pathogenic determinants is overdue for this organism

Relationship of Proteinases and Proteinase Inhibitors with Microbial Presence in Chronic Lung Disease of Prematurity

Background: A proteolytic imbalance has been implicated in the development of “classical” chronic lung disease of prematurity (CLD). However, in “new” CLD this pattern has changed. This study examines the longitudinal relationship between neutrophil proteinases and their inhibitors in ventilated preterm infants and their relationship to microbial colonisation. Methods: Serial bronchoalveolar lavage fluid was obtained from ventilated newborn preterm infants. Neutrophil elastase (NE) activity, cell counts, metalloproteinase (MMP)-9, MMP-9/TIMP-1 complex, SerpinB1 concentration and percentage of SerpinB1 and α1-antitrypsin (AAT) in complex with elastase were measured. The presence of microbial genes was examined using PCR for 16S rRNA genes. Results: Statistically more infants who developed CLD had NE activity in at least one sample (10/20) compared with infants with resolved respiratory distress syndrome (RDS) (2/17). However, NE activity was present in a minority of samples, occurring as episodic peaks. Peak levels of MMP-9, MMP-9/TIMP-1 complex, percentage of AAT and SerpinB1 in complex and cell counts were all statistically greater in infants developing CLD than in infants with resolved RDS. Peak values frequently occurred as episodic spikes and strong temporal relationships were noted between all markers. The peak values for all variables were significantly correlated to each other. The presence of bacterial 16S rRNA genes was associated with the development of CLD and with elevated elastase and MMP-9. Conclusion: NE activity and MMP-9 appear to be important in the development of “new” CLD with both proteinase and inhibitor concentrations increasing episodically, possibly in response to postnatal infection

Compensatory mutations modulate the competitiveness and dynamics of plasmid-mediated colistin resistance in Escherichia coli clones

The emergence of mobile colistin resistance (mcr) threatens to undermine the clinical efficacy of the last antibiotic that can be used to treat serious infections caused by Gram-negative pathogens. Here we measure the fitness cost of a newly discovered MCR-3 using in vitro growth and competition assays. mcr-3 expression confers a lower fitness cost than mcr-1, as determined by competitive ability and cell viability. Consistent with these findings, plasmids carrying mcr-3 have higher stability than mcr-1 plasmids across a range of Escherichia coli strains. Crucially, mcr-3 plasmids can stably persist, even in the absence of colistin. Recent compensatory evolution has helped to offset the cost of mcr-3 expression, as demonstrated by the high fitness of mcr-3.5 as opposed to mcr-3.1. Reconstructing all of the possible evolutionary trajectories from mcr-3.1 to mcr-3.5 reveals a complex fitness landscape shaped by negative epistasis between compensatory and neutral mutations. Our findings highlight the importance of fitness costs and compensatory evolution in driving the dynamics and stability of mobile colistin resistance in bacterial populations, and they highlight the need to understand how processes (other than colistin use) impact mcr dynamics

Decay-accelerating factor expression in the rat kidney is restricted to the apical surface of podocytes

Decay-accelerating factor expression in the rat kidney is restricted to the apical surface of podocytes.BackgroundDecay-accelerating factor (DAF) has inhibitory activity toward complement C3 and C5 convertases. DAF is present in human glomeruli and on cultured human glomerular visceral epithelial cells (GEC). We studied the distribution and function of rat DAF.MethodsFunction-neutralizing antibodies (Abs) were raised against DAF. The distribution of DAF in vivo was determined by immunoelectron microscopy. Functional studies were performed in cultured GEC and following IV injection of anti-DAF Abs into rats.ResultsDAF was present exclusively on the apical surfaces of GEC, and was not present on the basal surfaces of GEC, nor other glomerular or kidney cells. DAF was functionally active on cultured GEC, and served to limit complement activation in concert with CD59, an inhibitor of C5b-9 formation. Upon injection into normal rats, anti-DAF F(ab′)2 Abs bound to GEC in vivo, yet there was no evidence for complement activation and animals did not develop abnormal albuminuria. Anti-megalin complement-activating IgG Abs were “planted” on GEC, which activated complement as evidenced by the presence of C3d on GEC. Attempts to inhibit DAF function with anti-DAF Abs did not affect the quantity of complement activation by these anti-megalin Abs, nor did it lead to development of abnormal albuminuria. In contrast, in the puromycin aminonucleoside model of GEC injury and proteinuria, anti-DAF Abs slowed the recovery from renal failure that occurs in this model.ConclusionIn cultured rat GEC, DAF is an effective complement regulator. In vivo, DAF is present on GEC apical surfaces. Yet, it appears that DAF is not essential to prevent complement activation from occurring under normal circumstances and in those cases in which complement-activating Abs are present on the basal surfaces of GEC in vivo. However, in proteinuric conditions, DAF appears to be protective to GEC

Calcium Gluconate in Phosphate Buffered Saline Increases Gene Delivery with Adenovirus Type 5

Peer reviewe

Detrimental effects of an inhaled phosphodiesterase-4 inhibitor on lung inflammation in ventilated preterm lambs exposed to chorioamnionitis are dose dependent

Background: Treatment of bronchopulmonary dysplasia in preterm infants is challenging due to its multifactorial origin. In rodent models of neonatal lung injury, selective inhibition of phosphodiesterase 4 (PDE4) has been shown to exert anti-inflammatory properties in the lung. We hypothesized that GSK256066, a highly selective, inhalable PDE4 inhibitor, would have beneficial effects on lung injury and inflammation in a triple hit lamb model of Ureaplasma parvum (UP)-induced chorioamnionitis, prematurity, and mechanical ventilation. Methods: Twenty-one preterm lambs were surgically delivered preterm at 129 days after 7 days intrauterine exposure to UP. Sixteen animals were subsequently ventilated for 24 hours and received endotracheal surfactant and intravenous caffeine citrate. Ten animals were randomized to receive twice a high (10 μg/kg) or low dose (1 μg/kg) of nebulized PDE4 inhibitor. Results: Nebulization of high, but not low, doses of PDE4 inhibitor led to a significant decrease in pulmonary PDE activity, and was associated with lung injury and vasculitis, influx of neutrophils, and increased proinflammatory cytokine messenger RNA levels. Conclusion: Contrary to our hypothesis, we found in our model a dose-dependent proinflammatory effect of an inhaled highly selective PDE4 inhibitor in the lung. Our findings indicate the narrow therapeutic range of inhaled PDE4 inhibitors in the preterm population

Detection of volatile organic compounds as potential novel biomarkers for chorioamnionitis - proof of experimental models

Background: Histologic chorioamnionitis is only diagnosed postnatally which prevents interventions. We hypothesized that volatile organic compounds (VOCs) in the amniotic fluid might be useful biomarkers for chorioamnionitis and that VOC profiles differ between amnionitis of different origins. Methods: Time-mated ewes received intra-amniotic injections of media or saline (controls), or live Ureaplasma parvum serovar 3 (Up) 14, 7 or 3d prior to c-section at day 124 gestational age (GA). 100 μg recombinant ovine IL-1α was instilled at 7, 3 or 1d prior to delivery. Headspace VOC profiles were measured from amniotic fluids at birth using ion mobility spectrometer coupled with multi-capillary columns. Results: 127 VOC peaks were identified. 27 VOCs differed between samples from controls and Up- or IL-1α induced amnionitis. The best discrimination between amnionitis by Up vs. IL-1α was reached by 2-methylpentane, with a sensitivity/specificity of 96/95% and a positive predictive value/negative predictive values of 96 and 95%. The concentration of 2-methylpentane in VOCs peaked 7d after intra-amniotic instillation of Up. Discussion: We established a novel method to study headspace VOC profiles of amniotic fluids. VOC profiles may be a useful tool to detect and to assess the duration of amnionitis induced by Up. 2-methylpentane was previously described in the exhalate of women with pre-eclampsia and might be a volatile biomarker for amnionitis. Amniotic fluids analyzed by ion mobility spectrometry coupled with multi-capillary columns may provide bedside diagnosis of amnionitis and understanding inflammatory mechanisms during pregnancy

Proposals for the Future of Leadership Scholarship:Suggestions in Phronesis

“Phronesis” can be summarized as “wisdom in determining ends and the means of attaining them.” This unique article originated from comments made by scholars on a podcast hosted by Dr. Scott Allen titled “Phronesis: Practical Wisdom for Leaders.” Here, we propose ten specific agendas focused on the future of scholarship in the field of leadership studies, authored by some of these scholars. Topics include how to think about effective leadership in “the age of emotion” where truth can seem up for debate; specific topical suggestions for expanded study–such as more comprehensively studying place and space, indigenous wisdom, equity issues, games that teach, and focusing more on lifespan perspectives; better integrating scholarship with professional settings where leading occurs; and more effectively framing what it even means to lead and follow

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements