De novo design of pH-responsive self-assembling helical protein filaments.

Biological evolution has led to precise and dynamic nanostructures that reconfigure in response to pH and other environmental conditions. However, designing micrometre-scale protein nanostructures that are environmentally responsive remains a challenge. Here we describe the de novo design of pH-responsive protein filaments built from subunits containing six or nine buried histidine residues that assemble into micrometre-scale, well-ordered fibres at neutral pH. The cryogenic electron microscopy structure of an optimized design is nearly identical to the computational design model for both the subunit internal geometry and the subunit packing into the fibre. Electron, fluorescent and atomic force microscopy characterization reveal a sharp and reversible transition from assembled to disassembled fibres over 0.3 pH units, and rapid fibre disassembly in less than 1 s following a drop in pH. The midpoint of the transition can be tuned by modulating buried histidine-containing hydrogen bond networks. Computational protein design thus provides a route to creating unbound nanomaterials that rapidly respond to small pH changes.

The role of surgery for anaplastic thyroid carcinoma in the era of targeted therapeutics: A scoping review.

Background: Questions exist regarding patient selection for surgery in anaplastic thyroid carcinoma (ATC), particularly with the advent of neoadjuvant-targeted therapeutics. The present scoping review sought to evaluate what extent of surgical resection should be performed in ATC. Methods: A scoping review was carried out in accordance with Joanna Briggs Institute and the preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews (PRISMA-ScR) protocols. Included studies were required to provide clear description of the surgery performed for ATC. Results: The final search identified 6901 articles. Ultimately only 15 articles including 1484 patients met inclusion criteria. A total of 765 patients (51.5%) underwent attempted curative intent surgery. The approach to resection of adjacent tissues varied between studies. Eight studies considered laryngeal ± pharyngeal resection (8/15, 53.3%), eight studies (53.3%) considered tracheal resection and again eight studies (53.3%) considered esophageal resection. More extensive resections increased morbidity without improving overall survival (OS) (<9 months in the 12 studies using a combination of surgery and chemoradiotherapy). In the three studies utilizing targeted therapy in addition to surgery, OS was notably improved while surgical resection following neoadjuvant therapy was less extensive. Conclusions: There is no clear agreement in the literature regarding the limits of surgical resection in locoregionally advanced ATC. A definition of surgically resectable disease will be required to guide surgical decision making in ATC, particularly with the potential to reduce tumor burden using neoadjuvant targeted treatment in suitable patients. Level of evidence: III.

Local structural flexibility drives oligomorphism in computationally designed protein assemblies.

Many naturally occurring protein assemblies have dynamic structures that allow them to perform specialized functions. For example, clathrin coats adopt a wide variety of architectures to adapt to vesicular cargos of various sizes. Although computational methods for designing novel self-assembling proteins have advanced substantially over the past decade, most existing methods focus on designing static structures with high accuracy. Here we characterize the structures of three distinct computationally designed protein assemblies that each form multiple unanticipated architectures, and identify flexibility in specific regions of the subunits of each assembly as the source of structural diversity. Cryo-EM single-particle reconstructions and native mass spectrometry showed that only two distinct architectures were observed in two of the three cases, while we obtained six cryo-EM reconstructions that likely represent a subset of the architectures present in solution in the third case. Structural modeling and molecular dynamics simulations indicated that the surprising observation of a defined range of architectures, instead of non-specific aggregation, can be explained by constrained flexibility within the building blocks. Our results suggest that deliberate use of structural flexibility as a design principle will allow exploration of previously inaccessible structural and functional space in designed protein assemblies.

Precisely patterned nanofibres made from extendable protein multiplexes.

Molecular systems with coincident cyclic and superhelical symmetry axes have considerable advantages for materials design as they can be readily lengthened or shortened by changing the length of the constituent monomers. Among proteins, alpha-helical coiled coils have such symmetric, extendable architectures, but are limited by the relatively fixed geometry and flexibility of the helical protomers. Here we describe a systematic approach to generating modular and rigid repeat protein oligomers with coincident C2 to C8 and superhelical symmetry axes that can be readily extended by repeat propagation. From these building blocks, we demonstrate that a wide range of unbounded fibres can be systematically designed by introducing hydrophilic surface patches that force staggering of the monomers; the geometry of such fibres can be precisely tuned by varying the number of repeat units in the monomer and the placement of the hydrophilic patches.

Factors associated with red blood cells transfusion during first bloodless priming cardiac surgery in children.

INTRODUCTION: Red blood cell (RBC) transfusion is often required during cardiac surgery in children. However, RBC is a rare product, and its transfusion is associated with adverse events and a worse surgical outcome. Characterization of factors related to RBC transfusion during cardiac surgery in children would provide prevention strategies. METHODS: We conducted a retrospective single-center study, including all children who underwent their first cardiac surgery using bloodless priming cardiopulmonary bypass (CPB). RESULTS: The study included 173 children between 2011 and 2019,; 57 had intraoperative transfusion and 17 postoperative transfusion. Age (OR: 0.76, p<0.001), weight (OR: 0.93, p<0.001), body mass index ([BMI] OR: 0.83, p<0.001), hemoglobin level (OR: 0.68, p<0.05), hematocrit level (OR: 0.88, p<0.05), mean corpuscular volume ([MCV] (OR: 0.86, p<0.001), hemodilution (OR: 100, p<0.01), and CPB duration (OR: 1.01, p<0.05) were associated with an increased risk of intraoperative transfusion in univariate analysis. In multivariate analysis, only CPB duration (OR: 1.02, p<0.001) and MCV (OR: 0.89, p<0.05) were associated with transfusion. Concerning postoperative transfusions, the RACHS surgical difficulty score (OR: 6.83, p<0.01), duration of CPB (OR: 1.01, p<0,001), length of stay in the PICU (OR: 2.37, p<0.001), length of hospitalization (OR: 1.2, p<0.001), and reoperation (OR: 20.59, p<0.001) were significant using univariate analysis, and only the need for a reoperation (OR: 19.16, p<0.01) remained significant in multivariate analysis. CONCLUSION: Low MCV appears to be one of the main risk factors for intraoperative transfusion in RBC. It may reflect iron deficiency that should be checked and supplemented preoperatively in order to reduce the risk of transfusion.

Natural and Designed Proteins Inspired by Extremotolerant Organisms Can Form Condensates and Attenuate Apoptosis in Human Cells.

Many organisms can survive extreme conditions and successfully recover to normal life. This extremotolerant behavior has been attributed in part to repetitive, amphipathic, and intrinsically disordered proteins that are upregulated in the protected state. Here, we assemble a library of approximately 300 naturally occurring and designed extremotolerance-associated proteins to assess their ability to protect human cells from chemically induced apoptosis. We show that several proteins from tardigrades, nematodes, and the Chinese giant salamander are apoptosis-protective. Notably, we identify a region of the human ApoE protein with similarity to extremotolerance-associated proteins that also protects against apoptosis. This region mirrors the phase separation behavior seen with such proteins, like the tardigrade protein CAHS2. Moreover, we identify a synthetic protein, DHR81, that shares this combination of elevated phase separation propensity and apoptosis protection. Finally, we demonstrate that driving protective proteins into the condensate state increases apoptosis protection, and highlights the ability of DHR81 condensates to sequester caspase-7. Taken together, this work draws a link between extremotolerance-associated proteins, condensate formation, and designing human cellular protection.

Systematic skin and nasal decolonization lowers Staphylococcus infection in pediatric cardiac surgery.

BACKGROUND: Postoperative infections occur in approximately 10% of pediatric cardiac surgeries, involving Staphylococcus species in most cases. Nasal decontamination of Staphylococcus with mupirocin has been reported to reduce postoperative Staphylococcus infections after cardiac surgery in adults, but the effect of preoperative decontamination in children undergoing cardiac surgery has not been sufficiently studied to reach consensus. METHODS: We conducted a single-center retrospective study to evaluate the impact of systematic preoperative decolonization with intranasal mupirocin application and skin-washing with chlorhexidine soap on postoperative Staphylococcus infection in children undergoing cardiac surgery. Our population was divided into three groups according to decolonization protocol (group N: no decolonization; group T: targeted decolonization in Staphylococcus aureus [SA] carriers only; and group S: systematic decolonization). RESULTS: A total of 393 children were included between October 2011 and August 2015 (122 in group N, 148 in group T, and 123 in group S). The Staphylococcus infection rate significantly decreased in group S compared to group N (0.8% vs. 7.7%; p < 0.05) and tended to decrease in group S compared to group T (0.8% vs. 4.7%; p = 0.06). Systematic decontamination also significantly reduced the rate of infections starting from the skin (including surgical site infections and bloodstream infections) compared to targeted decolonization or lack of decolonization, but had no effect on the rate of pulmonary infections. CONCLUSION: The results of our study suggest that systematic preoperative skin and nasal decontamination, regardless of SA carriage status, could reduce the rate of postoperative Staphylococcus infections after cardiac surgery in children.

Social justice, activism and dentistry in the era of #BLM.

The #Black Lives Matter (BLM) movement thrust the dental profession into a period of critical reflection. Whilst there is enthusiasm for critical reflection and change now, we know from other social movements, like feminism, that this initial phase or 'wave' of activity will subside, hopefully to be replaced by a next 'wave'. How will we nurture this moment of activism and ensure that this initial energetic phase of activism and mobilisation transforms into more sustained and sustainable change? This article offers a sociological-ethical framework to ascertain if dentistry is the progressive and responsive profession it claims to be in the immediate aftermath of the #BLM movement. The dual theory of justice developed by Nancy Fraser (2001, 2004, 2005) and its distinction of the role played by redistribution and recognition in the pursuit of justice will be used to illuminate the challenges that dentistry and oral health face in this regard. It then plots the current efforts of the dental profession against the known trajectory of social movements to adjudicate what has been achieved and what work is yet to be done to ensure inclusion and race-based justice.

Dentistry, e-health and digitalisation: A critical narrative review of the dental literature on digital technologies with insights from health and technology studies.

OBJECTIVE: To overview current developments in e-health and digitalisation in dentistry and identify gaps in the dental literature on this topic; Basic research design: a critical narrative review of published articles and relevant online materials; Results: Four themes are identified as characterising the current dental literature on e-health and digitalisation: 1) the impact of digitalisation on dental surgeries, 2) digital technology and practice management, 3) digitalisation beyond the dental surgery and in dentist-patient communication, and 4) digital technology and education. However, gaps remain in our understanding of the impact of digital technology on dental practice, particularly in relation to its ethical considerations. Following the example of the wider medical literature, the review introduces the field of critical digital health studies and identifies areas for future investigation and exploration based on its four characteristics: devices and software, data materialisation, data practices and data mobilities; Conclusion and Clinical significance: Digital technology is changing clinical practice and patient care. Dentistry needs to expand its understanding of how dental apps, digital workflow models and digital health information are transforming and disrupting dental practice in order to anticipate how this digital shift will impact on dentistry. The emerging field of critical digital health studies can signpost ways to improve research and practice on the topic in the future.

A multiscale model of mechanotransduction by the ankyrin chains of the NOMPC channel.

Our senses of touch and hearing are dependent on the conversion of external mechanical forces into electrical impulses by the opening of mechanosensitive channels in sensory cells. This remarkable feat involves the conversion of a macroscopic mechanical displacement into a subnanoscopic conformational change within the ion channel. The mechanosensitive channel NOMPC, responsible for hearing and touch in flies, is a homotetramer composed of four pore-forming transmembrane domains and four helical chains of 29 ankyrin repeats that extend 150 Å into the cytoplasm. Previous work has shown that the ankyrin chains behave as biological springs under extension and that tethering them to microtubules could be involved in the transmission of external forces to the NOMPC gate. Here we combine normal mode analysis (NMA), full-atom molecular dynamics simulations, and continuum mechanics to characterize the material properties of the chains under extreme compression and extension. NMA reveals that the lowest-frequency modes of motion correspond to fourfold symmetric compression/extension along the channel, and the lowest-frequency symmetric mode for the isolated channel domain involves rotations of the TRP domain, a putative gating element. Finite element modeling reveals that the ankyrin chains behave as a soft spring with a linear, effective spring constantof 22 pN/nm for deflections ≤15 Å. Force-balance analysis shows that the entire channel undergoes rigid body rotation during compression, and more importantly, each chain exerts a positive twisting moment on its respective linker helices and TRP domain. This torque is a model-independent consequence of the bundle geometry and would cause a clockwise rotation of the TRP domain when viewed from the cytoplasm. Force transmission to the channel for compressions >15 Å depends on the nature of helix-helix contact. Our work reveals that compression of the ankyrin chains imparts a rotational torque on the TRP domain, which potentially results in channel opening.

Perceptions of e-professionalism among dental students: a UK dental school study.

Introduction: The social media activity of some healthcare students has created doubt about their ability to uphold and defend the ethical principles of healthcare in their online behaviours. A lot of research has been conducted on the online behaviours of medical and allied health professional students, however, less has been undertaken on dental students. Aims: The aim was to determine whether students were aware of the guidelines set by the General Dental Council (GDC) regarding social media and whether they believed they were being professional in their online activities. Methods and materials: Eighty-eight dental students (46 from year 2; 42 from year 4) at one UK dental school completed a questionnaire study examining their attitude towards and perceptions of e-professionalism. Results: The results show that most students were heavy users of social media with an awareness of social media guidelines set out by the GDC. However, student responses to various e-professionalism scenarios reveals disagreement on whether posts referring to alcohol and work colleagues were deemed unprofessional. Conclusion: Student perceptions of and attitudes towards e-professionalism is complicated and contradictory. More research will need to be undertaken to explore how we can inculcate e-professional values and behaviours in dental professionalism teaching.

Chemically induced vesiculation as a platform for studying TMEM16F activity.

Calcium-activated phospholipid scramblase mediates the energy-independent bidirectional translocation of lipids across the bilayer, leading to transient or, in the case of apoptotic scrambling, sustained collapse of membrane asymmetry. Cells lacking TMEM16F-dependent lipid scrambling activity are deficient in generation of extracellular vesicles (EVs) that shed from the plasma membrane in a Ca2+-dependent manner, namely microvesicles. We have adapted chemical induction of giant plasma membrane vesicles (GPMVs), which require both TMEM16F-dependent phospholipid scrambling and calcium influx, as a kinetic assay to investigate the mechanism of TMEM16F activity. Using the GPMV assay, we identify and characterize both inactivating and activating mutants that elucidate the mechanism for TMEM16F activation and facilitate further investigation of TMEM16F-mediated lipid translocation and its role in extracellular vesiculation.

Developing a Dental Scrubs Ceremony to define professional identity and teach professionalism to dental undergraduates; lessons learned.

INTRODUCTION: The UK General Dental Council stipulates that professionalism is a key aspect of the teaching and training of dental students. However, dental educators highlight that teaching dental student's professionalism can be challenging and students often rate this teaching activity negatively. This article documents a teaching initiative at one UK Dental School that aimed to strengthen the professionalism curriculum by introducing a Dental Scrubs Ceremony for second-year students. MATERIALS AND METHOD: The Dental Scrubs Ceremony is inspired by the White Coat Ceremonies that medical students have in universities in North America. It marks the students' first step in their professional and clinical development, with the signing of a pledge of conduct and public presentation of dental scrubs to each student. We report student feedback questionnaire data over a three-year period together with reflections on the merits and limitations of this alternative approach to teaching professionalism. RESULTS: Student evaluation data show that the perceived usefulness and worthwhileness of a Dental Scrubs Ceremony have grown since its inception in 2015. Most students enjoyed the symbolism of the ceremony, receiving their dental scrubs in a formal event. However, there was mixed evaluation for its effectiveness to teach professionalism. CONCLUSION: A Dental Scrubs Ceremony is a useful addition to the formal curriculum of professionalism in a dental school. It provides dental students with an opportunity to be inducted into the dental profession as novice dental students starting out on their professional career.

Neighbourhood incidence rate of paediatric dental extractions under general anaesthetic in South West England.

Introduction Extraction of decayed teeth is the most common reason for UK children aged 5-9 years to receive a general anaesthetic. Inequalities in oral health are well recognised, but is under-explored in dental general anaesthesia (DGA).Methods Secondary analysis of routinely collected data from three local authorities in South West England was used to assess: 1) dental activities recorded for children <18 years attending NHS general dental practitioners (GDP); 2) the incidence rate of DGA and disease severity among <16-year-olds; and 3) individual and neighbourhood factors associated with higher rates of child DGA, and greater severity of disease.Results Among 208,533 GDP appointments, rates of preventive action were low where 1/7 included fluoride varnish but 1/5 included permanent fillings. The incidence rate of DGA was 6.6 admissions for every 1,000 children, rising to 12.4/1,000 among 5-9-year-olds. A total of 86 (7.6%) children had previously received a DGA at the same hospital. Area deprivation was strongly associated with higher rates of DGA, but rates of DGA remained high in less deprived areas. No associations were observed between number of teeth removed and socio-economic status.Conclusion Too many children are receiving DGA, and too few preventive actions are recorded by GDPs. Area-based inequalities in DGA were apparent, but wealthy areas also experienced substantial childhood dental decay.

The Sixth Transmembrane Segment Is a Major Gating Component of the TMEM16A Calcium-Activated Chloride Channel.

Calcium-activated chloride channels (CaCCs) formed by TMEM16A or TMEM16B are broadly expressed in the nervous system, smooth muscles, exocrine glands, and other tissues. With two calcium-binding sites and a pore within each monomer, the dimeric CaCC exhibits voltage-dependent calcium sensitivity. Channel activity also depends on the identity of permeant anions. To understand how CaCC regulates neuronal signaling and how CaCC is, in turn, modulated by neuronal activity, we examined the molecular basis of CaCC gating. Here, we report that voltage modulation of TMEM16A-CaCC involves voltage-dependent occupancy of calcium- and anion-binding site(s) within the membrane electric field as well as a voltage-dependent conformational change intrinsic to the channel protein. These gating modalities all critically depend on the sixth transmembrane segment.

Social media and professionalism: a retrospective content analysis of Fitness to Practise cases heard by the GDC concerning social media complaints.

Introduction Since 2013, all General Dental Council (GDC) registrants' online activities have been regulated by the GDC's social media guidelines. Failure to comply with these guidelines results in a Fitness to Practise (FtP) complaint being investigated.Aims This study explores the prevalence of social media related FtP cases investigated by the GDC from 1 September 2013 to 21 June 2016.Method Documentary analysis of social media related FtP cases published on the GDC's website was undertaken. All cases that met the study's inclusion criteria were analysed using a quantitative content analysis framework.Findings It was found that 2.4% of FtP cases published on the GDC website during that period were related to breaches of the social media guidelines. All of the cases investigated were proven and upheld. Most of those named in the complaints were dental nurses and the most common type of complaint was inappropriate Facebook comments.Conclusions The low incidence rate should be interpreted with caution, being illustrative of the types of issues that might arise rather than the volume. The GDC will need to remain vigilant in this area and ensure that social media awareness training is an active part of CPD for all the dental team.