Bioengineered Nisin A Derivatives with Enhanced Activity against Both Gram Positive and Gram Negative Pathogens

peer-reviewedNisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G), with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E) with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria.This work was supported by the Irish Government under the National Development Plan, through Science Foundation Ireland Investigator awards (10/IN.1/B3027) and (06/IN.1/B98) (http://www.sfi.ie)

Implementing social health insurance in Ireland: Report of a meeting and workshop held in Dublin, on December 6th 2010

We considered two basic questions, 'Is it possible to implement Social Health Insurance in Ireland?', and 'How can this be done?'. Can Social Health Insurance be implemented in Ireland? Our answer is a very definite yes. Furthermore, there would be many opportunities, while working towards this end, to improve the performance of our health care system. How can it be implemented? This process will need to be actively managed. There are many difficulties in the Irish health services, but also many opportunities. The greatest strengths are the talented, well-trained and very committed staff. Getting and keeping the support of these staff, for the necessary changes in service delivery, will be critical. Ireland has the capacity to make these changes, but without high quality management, a detailed focussed plan for change, and political support, little will happen. Each step in the change needs to be planned to maintain services, improve service delivery, improve service accountability, and improve service governance. Each sector of the service will need someone to lead the change, and mind that service during the change. Primary care remains under-developed. The HSE plan to develop primary care teams (PCT) has not succeeded. There are several established PCTs which work well. In other areas there are informal arrangements for collaboration, which work well. Overall, there are many useful lessons to learn from the experience so far. Future developments will need to place general practice at the centre of primary care. The mechanisms for doing this will vary from place to place, but need to be developed urgently. Acute hospitals face a crisis of governance. Maurice Hayes' (1) recent report on Tallaght hospital gives an idea of the scale of the changes needed. Tallaght is, we believe, not atypical, and is reputed to be by no means the worst governed hospital in the system. This, alone, should provide a pressing motive for change. Redesigning Irish hospitals to a new mission of supporting primary care, of supporting care in the community where possible can, and must, be done. Long-term care for older people is also a challenge. We advise moving to an integrated needs based system with smooth transitions between different degrees of support at home, and different degrees of support in specialized housing facilities including nursing homes. A similar model should apply to other forms of long-term care, for example for people with a substantial disability. Information systems and management processes both need a major overhaul. The health service remains strikingly under-managed, and fixing this will need a substantial culture change within the services. Wide use of standardized formal project management processes will be vital. There is a separate plan being developed to improve health service IT systems, and implementing this needs to be a high priority. We have not considered other key sectors, for example mental health, disability services, and social services. This does not mean that these are unimportant, merely that we had limited time, and a great deal to cover

Control of Cheese Microflora using Bacteriocins.

End of Project ReportBacteriocins are proteins, produced by some bacteria which are capable of inhibiting other bacteria. The overall aim of this project was the development and exploitation of bacteriocins such as Lacticin 3147 (produced by a food-grade microorganism), as biological tools to control the microflora of foods. Lacticin 3147-producing strains were evaluated for their ability to improve the microbial quality of a variety of dairy products and in particular, Cheddar cheese. The manipulation of cheese flora using bacteriocins should offer manufacturers greater control in the consistency and quality of the final product, in addition to improving its safety. In concert with these studies, Lacticin 3147 was studied in detail at the molecular level resulting in its biochemical and genetic analysis. These studies have demonstrated the complexity and uniqueness of this potent antimicrobial.Department of Agriculture, Food and the Marin

An investigation of capacitance-voltage hysteresis in metal/high-k/In0.53Ga0.47As metal-oxide-semiconductor capacitors

In this work, we present the results of an investigation into charge trapping in metal/high-k/In0.53Ga0.47As metal-oxide-semiconductor capacitors (MOS capacitors), which is analysed using the hysteresis exhibited in the capacitance-voltage (C-V) response. The availability of both n and p doped In0.53Ga0.47As epitaxial layers allows the investigation of both hole and electron trapping in the bulk of HfO2 and Al2O3 films formed using atomic layer deposition (ALD). The HfO2/In0.53Ga0.47As and Al2O3/In0.53Ga0.47As MOS capacitors exhibit an almost reversible trapping behaviour, where the density of trapped charge is of a similar level to high-k/In0.53Ga0.47As interface state density, for both electrons and holes in the HfO2 and Al2O3 films. The experimental results demonstrate that the magnitude of the C-V hysteresis increases significantly for samples which have a native oxide layer present between the In0.53Ga0.47As surface and the high-k oxide, suggesting that the charge trapping responsible for the C-V hysteresis is taking place primarily in the interfacial oxide transition layer between the In0.53Ga0.47As and the ALD deposited oxide. Analysis of samples with a range of oxide thickness values also demonstrates that the magnitude of the C-V hysteresis window increases linearly with the increasing oxide thickness, and the corresponding trapped charge density is not a function of the oxide thickness, providing further evidence that the charge trapping is predominantly localised as a line charge and taking place primarily in the interfacial oxide transition layer located between the In0.53Ga0.47As and the high-k oxide. (C) 2013 AIP Publishing LLC

The prevalence of injection-site reactions with disease-modifying therapies and their effect on adherence in patients with multiple sclerosis: an observational study

<p>Abstract</p> <p>Background</p> <p>Interferon beta (IFNβ) and glatiramer acetate (GA) are administered by subcutaneous (SC) or intramuscular (IM) injection. Patients with multiple sclerosis (MS) often report injection-site reactions (ISRs) as a reason for noncompliance or switching therapies. The aim of this study was to compare the proportion of patients on different formulations of IFNβ or GA who experienced ISRs and who switched or discontinued therapy because of ISRs.</p> <p>Methods</p> <p>The Swiss MS Skin Project was an observational multicenter study. Patients with MS or clinically isolated syndrome who were on the same therapy for at least 2 years were enrolled. A skin examination was conducted at the first study visit and 1 year later.</p> <p>Results</p> <p>The 412 patients enrolled were on 1 of 4 disease-modifying therapies for at least 2 years: IM IFNβ-1a (n = 82), SC IFNβ-1b (n = 123), SC IFNβ-1a (n = 184), or SC GA (n = 23). At first evaluation, ISRs were reported by fewer patients on IM IFNβ-1a (13.4%) than on SC IFNβ-1b (57.7%; <it>P </it>< 0.0001), SC IFNβ-1a (67.9%; <it>P </it>< 0.0001), or SC GA (30.4%; <it>P </it>= not significant [NS]). No patient on IM IFNβ-1a missed a dose in the previous 4 weeks because of ISRs, compared with 5.7% of patients on SC IFNβ-1b (<it>P </it>= 0.044), 7.1% of patients on SC IFNβ-1a (<it>P </it>= 0.011), and 4.3% of patients on SC GA (<it>P </it>= NS). Primary reasons for discontinuing or switching therapy were ISRs or lack of efficacy. Similar patterns were observed at 1 year.</p> <p>Conclusions</p> <p>Patients on IM IFNβ-1a had fewer ISRs and were less likely to switch therapies than patients on other therapies. This study may have implications in selecting initial therapy or, for patients considering switching or discontinuing therapy because of ISRs, selecting an alternative option.</p

The involvement of the low-oxygen-activated locus of Burkholderia cenocepacia in adaptation during cystic fibrosis infection

Chronic infection with opportunistic pathogens including Burkholderia cepacia complex (Bcc) is a hallmark of cystic fibrosis (CF). We investigated the adaptive mechanisms facilitating chronic lung infection in sequential Bcc isolates from two siblings with CF (P1 and P2), one of whom also experienced intermittent blood-stream infections (P2). We previously showed increased lung cell attachment with colonisation time in both P1 and P2. WGS analysis confirmed that the isolates are closely related. Twelve genes showed three or more mutations, suggesting these were genes under selection. Single nucleotide polymorphisms (SNVs) in 45 regulatory genes were also observed. Proteomic analysis showed that the abundance of 149 proteins increased over 61-months in sputum isolates, and both time- and source-related alterations in protein abundance between the second patient’s isolates. A consistent time-dependent increase in abundance of 19 proteins encoded by a low-oxygen-activated (lxa) locus was observed in both sets of isolates. Attachment was dramatically reduced in a B. cenocepacia K56-2Δlxa-locus deletion mutant, further indicating that it encodes protein(s) involved in host-cell attachment. Time-related changes in virulence in Galleria mellonella or motility were not observed. We conclude that the lxa-locus, associated with anoxic persistence in vitro, plays a role in host-cell attachment and adaptation to chronic colonization in the hypoxic niche of the CF lung

Understanding Detergent Effects on Lipid Membranes: A Model Study of Lysolipids

Lysolipids and fatty acids are the natural products formed by the hydrolysis of phospholipids. Lysolipids and fatty acids form micelles in solution and acts as detergents in the presence of lipid membranes. In this study, we investigate the detergent strength of a homologous series of lyso-phosphatidylcholine lipids (LPCs) on 1-palmitoyl-2-oleyl-sn-glycerol-3-phosphatidylcholine (POPC) lipid membranes by use of isothermal titration calorimetry and vesicle fluctuation analysis. The membrane partition coefficient (K) and critical micelle concentration (cmc) are determined by isothermal titration calorimetry and found to obey an inverse proportionality relation (cmc·K ∼ 0.05–0.3). The partition coefficient and critical micelle concentration are used for the analysis of the effect of LPCs on the membrane bending rigidity. The dependency of the bending rigidity on LPC membrane coverage has been analyzed in terms of a phenomenological model based on continuum elastic theory, which yields information about the curvature-inducing properties of the LPC molecule. The results reveal: 1), an increase in the partition coefficient with increasing LPC acyl-chain length; and 2), that the degree of acyl-chain mismatch between LPC and POPC determines the magnitude of the membrane mechanical perturbation per LPC molecule in the membrane. Finally, the three-stage model describing detergent membrane interaction has been extended by a parameter DMCI, which governs the membrane curvature stability in the detergent concentration range below the cmc-value of the LPC molecule