Navigating the shifting sands of filtering facepiece respirator provision during the COVID-19 pandemic: a system response for maximising staff safety.

INTRODUCTION: Personal protective equipment is essential to protect health workers and patients and to ensure confidence when dealing with aerosolised disease transmission. We describe the process for ensuring adequate filtering facepiece respirator (FFR) qualitative fit testing at a local level during the COVID-19 pandemic. METHODS: Cascaded training is described, which allowed rapid spreading of the testing process, with supervision allowing quality assurance throughout. Testing consisted of subjective 'fit checking', checking for leaks, followed by qualitative hood testing. RESULTS: The original respirators (3M 1870) had a hood test pass rate of 87.5%. Following identification of this as a non-renewable and unsustainable option, a domestically manufactured and sustainable Help-It P2 duckbill-type respirator was adopted as the primary FFR. The hood test pass rate for this respirator was only 54%. A third respirator was made available (3M 1860), with a high pass rate of 80% but also a limited and non-renewable resource. Algorithms were constructed highlighting different proportional use of the respirators depending on the most limited resource. CONCLUSION: The testing format used is simple, reproducible and can be used by any hospital organisation when occupational health and safety departments are unable to provide the service during overwhelming demand. Qualitative fit testing is a scalable and effective method for ensuring appropriately sized and shaped FFRs, minimising resource consumption in the process. The use of a product with appropriate filtration capacity but a lower fit test pass rate (domestic duckbill respirator) as a replaceable resource facilitated adequate respirator availability for staff that would otherwise not have been possible. The provision of an FFR fit registry allows an organisation to make appropriate respirators available to staff from different sources as supply and demand changes.

The PRECOS framework: Measuring the impacts of the global changes on soils, water, agriculture on territories to better anticipate the future.

In a context of increased land and natural resources scarcity, the possibilities for local authorities and stakeholders of anticipating evolutions or testing the impact of envisaged developments through scenario simulation are new challenges. PRECOS's approach integrates data pertaining to the fields of water and soil resources, agronomy, urbanization, land use and infrastructure etc. It is complemented by a socio-economic and regulatory analysis of the territory illustrating its constraints and stakes. A modular architecture articulates modeling software and spatial and temporal representations tools. It produces indicators in three core domains: soil degradation, water and soil resources and agricultural production. As a territory representative of numerous situations of the Mediterranean Basin (urban pressures, overconsumption of spaces, degradation of the milieus), a demonstration in the Crau's area (Southeast of France) has allowed to validate a prototype of the approach and to test its feasibility in a real life situation. Results on the Crau area have shown that, since the beginning of the 16th century, irrigated grasslands are the cornerstones of the anthropic-system, illustrating how successfully men's multi-secular efforts have maintained a balance between environment and local development. But today the ecosystem services are jeopardized firstly by urban sprawl and secondly by climate change. Pre-diagnosis in regions of Emilia-Romagna (Italy) and Valencia (Spain) show that local end-users and policy-makers are interested by this approach. The modularity of indicator calculations and the availability of geo-databases indicate that PRECOS may be up scaled in other socio-economic contexts.

Direct placement of a brachial plexus neural catheter for analgesia after traumatic upper limb amputation.

We report a case of traumatic upper limb injury that resulted in above elbow amputation. A multimodal approach was employed to optimize postoperative analgesia; this included continuous peripheral nerve blockade, initiated intraoperatively. Surgical access onto the axillary artery for proximal vascular control allowed placement of the nerve catheter under direct vision onto the brachial plexus. The pathophysiology of phantom pain is related to our case experience. This report highlights the complex challenge of controlling pain in combat casualties and promotes employment of multimodal analgesic strategies, including advanced regional anesthesia, in the military setting.

Selection of molecules based on shape and electrostatic similarity: proof of concept of "electroforms".

Molecular shape and electrostatic distribution play a crucial role in enzyme and receptor recognition and contribute extensively to binding affinity. Molecular similarity and bioisosterism are much-discussed topics in medicinal chemistry. Many molecular representations and similarity metrics are available to help drug discovery, and activities such as compound hit explosion and library design can be undertaken using them. The quality of the resulting compound series is highly dependent upon the molecular representation and similarity metric used. We have used a range of software to investigate whether molecules can be represented and compared effectively using measures of three-dimensional shape and electrostatic distribution ("electroforms"). We find that these descriptors allow for the assessment of molecular similarities using standard molecular visualization tools and offer a method for comparing molecules that may be considered superior to other methods.

Crystal structure of human cytochrome P450 2D6.

Cytochrome P450 2D6 is a heme-containing enzyme that is responsible for the metabolism of at least 20% of known drugs. Substrates of 2D6 typically contain a basic nitrogen and a planar aromatic ring. The crystal structure of human 2D6 has been solved and refined to 3.0A resolution. The structure shows the characteristic P450 fold as seen in other members of the family, with the lengths and orientations of the individual secondary structural elements being very similar to those seen in 2C9. There are, however, several important differences, the most notable involving the F helix, the F-G loop, the B'helix, beta sheet 4, and part of beta sheet 1, all of which are situated on the distal face of the protein. The 2D6 structure has a well defined active site cavity above the heme group, containing many important residues that have been implicated in substrate recognition and binding, including Asp-301, Glu-216, Phe-483, and Phe-120. The crystal structure helps to explain how Asp-301, Glu-216, and Phe-483 can act as substrate binding residues and suggests that the role of Phe-120 is to control the orientation of the aromatic ring found in most substrates with respect to the heme. The structure has been compared with published homology models and has been used to explain much of the reported site-directed mutagenesis data and help understand the metabolism of several compounds.

Discovery strategies in a pharmaceutical setting: the application of computational techniques.

This review explores some of the techniques available to the computational chemist to maximise the success rate when attempting to identify pharmaceutically relevant ligands in a discovery environment. The authors introduce and discuss methods of constructing various types of compound collections and consider an alternative approach to measuring compound similarity. The discussion is illustrated with an example of a kinase collection constructed using these methods and the results obtained from it. As an example of predicting absorption, distribution, metabolism, excretion and toxicology liabilities, this review focuses on the CYP450 isozyme family. The field of high-throughput docking is touched on with further examples and discussion.

Structural and kinetic analysis of the substrate specificity of human fibroblast activation protein alpha.

Fibroblast activation protein alpha (FAPalpha) is highly expressed in epithelial cancers and has been implicated in extracellular matrix remodeling, tumor growth, and metastasis. We present the first high resolution structure for the apoenzyme as well as kinetic data toward small dipeptide substrates. FAPalpha exhibits a dipeptidyl peptidase IV (DPPIV)-like fold, featuring an alpha/beta-hydrolase domain and an eight-bladed beta-propeller domain. Known DPPIV dipeptides are cleaved by FAPalpha with an approximately 100-fold decrease in catalytic efficiency compared with DPPIV. Moreover, FAPalpha, but not DPPIV, possesses endopeptidase activity toward N-terminal benzyloxycarbonyl (Z)-blocked peptides. Comparison of the crystal structures of FAPalpha and DPPIV revealed one major difference in the vicinity of the Glu motif (Glu(203)-Glu(204) for FAPalpha; Glu(205)-Glu(206) for DPPIV) within the active site of the enzyme. Ala(657) in FAPalpha, instead of Asp(663) as in DP-PIV, reduces the acidity in this pocket, and this change could explain the lower affinity for N-terminal amines by FAPalpha. This hypothesis was tested by kinetic analysis of the mutant FAPalpha/A657D, which shows on average an approximately 60-fold increase in the catalytic efficiency, as measured by k(cat)/K(m), for the cleavage of dipeptide substrates. Furthermore, the catalytic efficiency of the mutant is reduced by approximately 350-fold for cleavage of Z-Gly-Pro-7-amino-4-methylcoumarin. Our data provide a clear understanding of the molecular determinants responsible for the substrate specificity and endopeptidase activity of FAPalpha.

Crystal structure of human dipeptidyl peptidase IV in complex with a decapeptide reveals details on substrate specificity and tetrahedral intermediate formation.

Dipeptidyl peptidase IV (DPPIV) is a member of the prolyl oligopeptidase family of serine proteases. DPPIV removes dipeptides from the N terminus of substrates, including many chemokines, neuropeptides, and peptide hormones. Specific inhibition of DPPIV is being investigated in human trials for the treatment of type II diabetes. To understand better the molecular determinants that underlie enzyme catalysis and substrate specificity, we report the crystal structures of DPPIV in the free form and in complex with the first 10 residues of the physiological substrate, Neuropeptide Y (residues 1-10; tNPY). The crystal structure of the free form of the enzyme reveals two potential channels through which substrates could access the active site-a so-called propeller opening, and side opening. The crystal structure of the DPPIV/tNPY complex suggests that bioactive peptides utilize the side opening unique to DPPIV to access the active site. Other structural features in the active site such as the presence of a Glu motif, a well-defined hydrophobic S1 subsite, and minimal long-range interactions explain the substrate recognition and binding properties of DPPIV. Moreover, in the DPPIV/tNPY complex structure, the peptide is not cleaved but trapped in a tetrahedral intermediate that occurs during catalysis. Conformational changes of S630 and H740 between DPPIV in its free form and in complex with tNPY were observed and contribute to the stabilization of the tetrahedral intermediate. Our results facilitate the design of potent, selective small molecule inhibitors of DPPIV that may yield compounds for the development of novel drugs to treat type II diabetes.