The plasma membrane of microaerophilic protists : oxidative and nitrosative stress

The trans-plasma-membrane electrochemical potential of microaerophilic protists was monitored by the use of voltage-sensitive charged lipophilic fluorophores; of the many availableprobes, the anionic oxonol dye bis (1,3-dibarbituric acid)-trimethine oxonol [DiBAC4(3)] is an example of one which has been successfully employed using fluorescence microscopy, confocal laser-scanning microscopy and flow cytometry. Several microaerophilic protists have been investigated with this dye; these were Giardia intestinalis, Trichomonas vaginalis, Tritrichomonas foetus, Hexamita inflata and Mastigamoeba punctachora. Under conditions where they exhibit normal vitality, these organisms exclude DiBAC4(3) by virtue of their maintenance of a plasma-membrane potential (negative inside). Uptake of the fluorophore is indicative of disturbance to this membrane (i.e. by inhibition of pump/leak balance, blockage of channels or generation of ionic leaks), and is indicative of metabolic perturbation or environmental stress. Here, it is shown that oxidative or nitrosative stress depolarizes the plasma membranes of the aforementioned O2-sensitive organisms and allows DiBAC4(3) influx. Oxonol uptake thereby provides a sensitive and early indication of plasma-membrane perturbation by agents that may lead to cytotoxicity and eventually to cell death by necrotic or apoptotic pathways

Learning at times and places chosen by the learner : adapting to study with mobile digital devices

There has been substantial research into the use of Information and Communication Technologies (ICT) in higher education but, as mobile access to the Internet becomes the norm, there is a need to explore how mLearning can offer the flexibility expected by increasing numbers of undergraduate university students. This DEHub funded project, conducted by two Queensland Universities, investigated the potential of mobile devices to enhance student learning by increasing time on task at times and locations more convenient for the learner. This paper describes the conceptual background and approaches and reports some initial findings. The key finding is that the presentation of study materials and learning activities requires adjustment to support effective mobile access

The three-peat challenge: business as usual, responsible agriculture, and conservation and restoration as management trajectories in global peatlands

Peatlands are a globally important carbon store, but peatland ecosystems from high latitudes to the tropics are highly degraded due to increasingly intensive anthropogenic activity, making them significant greenhouse gas (GHG) sources. Peatland restoration and conservation have been proposed as a nature-based solution to climate change, by restoring the function of peatlands as a net carbon sink, but this may have implications for many local communities who rely on income from activities associated with transformed peatlands, particularly those drained for agriculture. However, without changing the way that humans interact with and exploit peatlands in most regions, peatlands will continue to degrade and be lost. We propose that there are ultimately three potential trajectories for peatland management: business as usual, whereby peatland carbon sink capacity continues to be eroded, responsible agricultural management (with the potential to mitigate emissions, but unlikely to restore peatlands as a net carbon sink), and restoration and conservation. We term this the three-peat challenge, and propose it as a means to view the benefits of restoring peatlands for the environment, as well as the implications of such transitions for communities who rely on ecosystem services (particularly provisioning) from degraded peatlands, and the consequences arising from a lack of action. Ultimately, decisions regarding which trajectories peatlands in given localities will follow torequire principles of equitable decision-making, and support to ensure just transitions, particularly for communities who rely on peatland ecosystems to support their livelihoods

Camostat attenuates airway epithelial sodium channel function in vivo through the inhibition of a channel-activating protease

Inhibition of airway epithelial sodium channel (ENaC) function enhances mucociliary clearance (MCC). ENaC is positively regulated by channel-activating proteases (CAPs), and CAP inhibitors are therefore predicted to be beneficial in diseases associated with impaired MCC. The aims of the present study were to 1) identify low-molecular-weight inhibitors of airway CAPs and 2) to establish whether such CAP inhibitors would translate into a negative regulation of ENaC function in vivo, with a consequent enhancement of MCC. To this end, camostat, a trypsin-like protease inhibitor, provided a potent (IC 50 ~50 nM) and prolonged attenuation of ENaC function in human airway epithelial cell models that was reversible upon the addition of excess trypsin. In primary human bronchial epithelial cells, a potency order of placental bikunin < camostat < 4-guanidino-benzoic acid 4-carboxymethyl-phenyl ester < aprotinin << soybean trypsin inhibitor = a1-antitrypsin, was largely consistent with that observed for inhibition of prostasin, a molecular candidate for the airway CAP. In vivo, topical airway administration of camostat induced a potent and prolonged attenuation of ENaC activity in the guinea pig trachea (ED 50 = 3 µg/kg). When administered by aerosol inhalation in conscious sheep, camo-stat enhanced MCC out to at least 5 h after inhaled dosing. In summary, camostat attenuates ENaC function and enhances MCC, providing an opportunity for this approach toward the negative regulation of ENaC function to be tested therapeutically. Copyright © 2009 by The American Society for Pharmacology and Experimental Therapeutics

Irbesartan in Marfan syndrome (AIMS): a double-blind, placebo-controlled randomised trial

Background: Irbesartan, a long acting selective angiotensin-1 receptor inhibitor, in Marfan syndrome might reduce aortic dilatation, which is associated with dissection and rupture. We aimed to determine the effects of irbesartan on the rate of aortic dilatation in children and adults with Marfan syndrome. Methods: We did a placebo-controlled, double-blind randomised trial at 22 centres in the UK. Individuals aged 6–40 years with clinically confirmed Marfan syndrome were eligible for inclusion. Study participants were all given 75 mg open label irbesartan once daily, then randomly assigned to 150 mg of irbesartan (increased to 300 mg as tolerated) or matching placebo. Aortic diameter was measured by echocardiography at baseline and then annually. All images were analysed by a core laboratory blinded to treatment allocation. The primary endpoint was the rate of aortic root dilatation. This trial is registered with ISRCTN, number ISRCTN90011794. Findings: Between March 14, 2012, and May 1, 2015, 192 participants were recruited and randomly assigned to irbesartan (n=104) or placebo (n=88), and all were followed for up to 5 years. Median age at recruitment was 18 years (IQR 12–28), 99 (52%) were female, mean blood pressure was 110/65 mm Hg (SDs 16 and 12), and 108 (56%) were taking β blockers. Mean baseline aortic root diameter was 34·4 mm in the irbesartan group (SD 5·8) and placebo group (5·5). The mean rate of aortic root dilatation was 0·53 mm per year (95% CI 0·39 to 0·67) in the irbesartan group compared with 0·74 mm per year (0·60 to 0·89) in the placebo group, with a difference in means of −0·22 mm per year (−0·41 to −0·02, p=0·030). The rate of change in aortic Z score was also reduced by irbesartan (difference in means −0·10 per year, 95% CI −0·19 to −0·01, p=0·035). Irbesartan was well tolerated with no observed differences in rates of serious adverse events. Interpretation: Irbesartan is associated with a reduction in the rate of aortic dilatation in children and young adults with Marfan syndrome and could reduce the incidence of aortic complications

Longitudinal immune profiling reveals key myeloid signatures associated with COVID-19

COVID-19 pathogenesis is associated with an exaggerated immune response. However, the specific cellular mediators and inflammatory components driving diverse clinical disease outcomes remain poorly understood. We undertook longitudinal immune profiling on both whole blood and peripheral blood mononuclear cells of hospitalized patients during the peak of the COVID-19 pandemic in the United Kingdom. Here, we report key immune signatures present shortly after hospital admission that were associated with the severity of COVID-19. Immune signatures were related to shifts in neutrophil to T cell ratio, elevated serum IL-6, MCP-1, and IP-10 and modulation of CD14+ monocyte phenotype and function. Modified features of CD14+ monocytes included poor induction of the prostaglandin-producing enzyme, COX-2, and enhanced expression of the cell cycle marker Ki-67. Longitudinal analysis revealed reversion of some immune features back to the healthy median level in patients with a good eventual outcome. These findings identify previously unappreciated alterations in the innate immune compartment of patients with COVID-19 and lend support to the idea that therapeutic strategies targeting release of myeloid cells from bone marrow should be considered in this disease. Moreover, they demonstrate that features of an exaggerated immune response are present early after hospital admission, suggesting that immunomodulating therapies would be most beneficial at early time points