Controlling Multivalent Binding through Surface Chemistry: Model Study on Streptavidin.

Although multivalent binding to surfaces is an important tool in nanotechnology, quantitative information about the residual valency and orientation of surface-bound molecules is missing. To address these questions, we study streptavidin (SAv) binding to commonly used biotinylated surfaces such as supported lipid bilayers (SLBs) and self-assembled monolayers (SAMs). Stability and kinetics of SAv binding are characterized by quartz crystal microbalance with dissipation monitoring, while the residual valency of immobilized SAv is quantified using spectroscopic ellipsometry by monitoring binding of biotinylated probes. Purpose-designed SAv constructs having controlled valencies (mono-, di-, trivalent in terms of biotin-binding sites) are studied to rationalize the results obtained on regular (tetravalent) SAv. We find that divalent interaction of SAv with biotinylated surfaces is a strict requirement for stable immobilization, while monovalent attachment is reversible and, in the case of SLBs, leads to the extraction of biotinylated lipids from the bilayer. The surface density and lateral mobility of biotin, and the SAv surface coverage are all found to influence the average orientation and residual valency of SAv on a biotinylated surface. We demonstrate how the residual valency can be adjusted to one or two biotin binding sites per immobilized SAv by choosing appropriate surface chemistry. The obtained results provide means for the rational design of surface-confined supramolecular architectures involving specific biointeractions at tunable valency. This knowledge can be used for the development of well-defined bioactive coatings, biosensors and biomimetic model systems

Surfaces: An interdisciplinary project to understand and enhance health in the vulnerable rainforests of Papua New Guinea

Background New Guinea has the third largest tropical rainforest on Earth. However, one quarter of the forests of Papua New Guinea (PNG, New Guinea’s eastern half) have been cleared or degraded, nearly half through commercial logging.Sustainable development requires supporting good health (Sustainable Development Goal [SDG] 3) and protecting life on land (SDG 15). To remote communities in PNG with low levels of health provision, these goals can seem in conflict. Logging companies’ offer of roads and income can partly extinguish the remoteness that bars access to health services, making desire for health a driver for forest destruction and erosion of health related ecosystem services. Conservation success thus requires synergies be developed with delivery of other SDGs, particularly those pertaining to health. We aim to provide a model of integrated health and conservation in PNGs rainforests. Methods We are mapping and piloting biological, anthropological, and medical methods to address SDGs on health and biodiversity, focusing first on scabies and fungal diseases. At Wanang, team members have a long term collaboration with nine clans with unmet health needs who collectively chose to preserve their 10,000 hectare forest whilst surrounding communities allowed logging. Similar collaborations are being developed along an altitudinal transect on Mt.Wilheim (4,509m). Stage 1 of Surfaces will (i) systematically map evidence on integrated conservation and health programmes, (ii) conduct clinical examinations and rapid anthropological assessments to understand medical needs, and survey skin disease, and (iii) produce a case study of the Wanang agreement, based on interviews with participants. This will lay the foundation for a multi-year health intervention and interdisciplinary study. Findings We are in the projects’ early stages (so do not yet have findings), and would appreciate advice and suggestions of collaboration from others in the Planetary Health community. Funding Sussex Sustainability Research Programme, University of Sussex, UK. Contributions All authors have commented on multiple drafts and approved the final version of the abstract for publication. Conflicts of interest We declare we have no conflicts of interest. Acknowledgments We thank the projects partner communities; New Guinea Binatang Research Centre; and our advisory group

Comparative study of three lactate oxidases from Aerococcus viridans for biosensing applications

A comparison between engineered and commercially available L-lactate oxidases from Aerococcus viridans was conducted for biosensing applications. Enzymes were adsorbed onto the surfaces of graphite electrodes modified with multi-walled carbon nanotubes. Thermostable L-lactate oxidases were cloned with a (i) N-, (ii) a C-terminal His-tag and (iii) a wild-type enzyme. Subsequently to the heterologous expression in Escherichia coil and purification, we determined the kinetic parameters of these enzymes in solution. The kinetics of the wild-type, of the N-terminally His-tagged enzyme and of the commercial L-lactate oxidase from A. viridans were studied with a classical Michaelis-Menten as well as with a substrate inhibition model, while the enzyme carrying a C-terminal His-tag showed no activity. The active enzymes were used to fabricate and comparatively investigate multi-walled carbon nanotubes-based biosensors. The enzyme kinetic results were compared with electrochemical studies. By using both spectrophotometric and amperometric techniques, the inhibition phenomenon fits better to the data especially those data related with Lox-His-N. The electrochemical data of the fabricated enzymatic biosensors showed that the N-terminally His-tagged L-lactate oxidase performed best on carboxyl-modified carbon nanotubes. The sensor based on this engineered enzyme showed the highest sensitivity and lowest detection limit in the range of L-lactate concentration 0-1 mM as well as long term stability over one month. (C) 2013 Elsevier Ltd. All rights reserved

Rationale, experience and ethical considerations underpinning integrated actions to further global goals for health and land biodiversity in Papua New Guinea

The SURFACES project is integrating action on good health and wellbeing (Sustainable Development Goal [SDG] 3) and conservation of life on land (SDG 15) in the threatened rainforests of Papua New Guinea (PNG), and mapping evidence of similar projects worldwide. Our approach is framed by Planetary Health, aiming to safeguard both human health and the natural systems that underpin it. Our rationale is demonstrated through a summary of health needs and forest conservation issues across PNG, and how these play out locally. We outline differing types of integrated conservation and health interventions worldwide, providing examples from Borneo, Uganda, India and elsewhere. We then describe what we are doing on-the-ground in PNG, which includes expansion of a rainforest conservation area alongside the establishment of a nurse-staffed aid post, and an educational intervention conceptually linking forest conservation and health. Importantly, we explore some ethical considerations on the conditionality of medical provision, and identify key challenges to successful implementation of such projects. The latter include: avoiding cross-sectoral blindness and achieving genuine interdisciplinary working; the weak evidence base justifying projects; and temporal-spatial issues. We conclude by suggesting how projects integrating actions on health and conservation SDGs can benefit from (and contribute to) the energy of the emerging Planetary Health movement

Human peroxisomal coenzyme A diphosphatase (NUDT7): a target enabling package (TEP)

In an effort to characterise the human NUDIX family SGC Oxford has expressed recombinant human NUDT7 as part of the SGC chemical probe programme and solved the first crystal structure of this enzyme. This enabled a crystallographic fragment screen which in conjunction with a separate covalent fragment approach yielded a first-in-class small molecule inhibitor of NUDT7 with activity in the single-digit micromolar range in a catalytic assay. This compound paves the way for chemical probe development and further functional exploration of NUDT7 in physiological and disease contexts

Factors associated with time delay to carotid stenting in patients with a symptomatic carotid artery stenosis

Treatment of a symptomatic stenosis is known to be most beneficial within 14 days after the presenting event but this can frequently not be achieved in daily practice. The aim of this study was the assessment of factors responsible for this time delay to treatment. A retrospective analysis of a prospective two-center CAS database was carried out to investigate the potential factors that influence a delayed CAS treatment. Of 374 patients with a symptomatic carotid stenosis, 59.1% were treated beyond ≥14 days. A retinal TIA event (OR = 3.59, 95% CI 1.47–8.74, p < 0.01) was found to be a predictor for a delayed treatment, whereas the year of the intervention (OR = 0.32, 95% CI 0.20–0.50, p < 0.01) and a contralateral carotid occlusion (OR = 0.42, 95% CI 0.21–0.86, p = 0.02) were predictive of an early treatment. Similarly, within the subgroup of patients with transient symptoms, the year of the intervention (OR = 0.28, 95% CI 0.14–0.59, p < 0.01) was associated with an early treatment, whereas a retinal TIA as the qualifying event (OR = 6.96, 95% CI 2.37–20.47, p < 0.01) was associated with a delayed treatment. Treatment delay was most pronounced in patients with an amaurosis fugax, whereas a contralateral carotid occlusion led to an early intervention. Although CAS is increasingly performed faster in the last years, there is still scope for an even more accelerated treatment strategy, which might prevent future recurrent strokes prior to treatment

Health service needs and perspectives of remote forest communities in Papua New Guinea: study protocol for combined clinical and rapid anthropological assessments with parallel treatment of urgent cases

Introduction Our project follows community requests for health service incorporation into conservation collaborations in the rainforests of Papua New Guinea (PNG). This protocol is for health needs assessments, our first step in coplanning medical provision in communities with no existing health data. Methods and analysis The study includes clinical assessments and rapid anthropological assessment procedures (RAP) exploring the health needs and perspectives of partner communities in two areas, conducted over 6 weeks fieldwork. First, in Wanang village (population c.200), which is set in lowland rainforest. Second, in six communities (population c.3000) along an altitudinal transect up the highest mountain in PNG, Mount Wilhelm. Individual primary care assessments incorporate physical examinations and questioning (providing qualitative and quantitative data) while RAP includes focus groups, interviews and field observations (providing qualitative data). Given absence of in-community primary care, treatments are offered alongside research activity but will not form part of the study. Data are collected by a research fellow, primary care clinician and two PNG research technicians. After quantitative and qualitative analyses, we will report: ethnoclassifications of disease, causes, symptoms and perceived appropriate treatment; community rankings of disease importance and service needs; attitudes regarding health service provision; disease burdens and associations with altitudinal-related variables and cultural practices. To aid wider use study tools are in online supplemental file, and paper and ODK versions are available free from the corresponding author. Ethics and dissemination Challenges include supporting informed consent in communities with low literacy and diverse cultures, moral duties to provide treatment alongside research in medically underserved areas while minimising risks of therapeutic misconception and inappropriate inducement, and PNG research capacity building. Brighton and Sussex Medical School (UK), PNG Institute of Medical Research and PNG Medical Research Advisory Committee have approved the study. Dissemination will be via journals, village meetings and plain language summaries