Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is associated with thrombotic complications in adults, but the incidence of COVID-19 related thrombosis in children and adolescents is unclear. Most children with acute COVID-19 have mild disease, but coagulopathy has been associated with multisystem inflammatory syndrome in children (MIS-C), a post-infectious complication. We conducted a multicenter retrospective cohort study to determine the incidence of thrombosis in children hospitalized with COVID-19 or MIS-C and to evaluate associated risk factors. We classified patients into one of three groups for analysis: COVID-19, MIS-C, or asymptomatic SARS-CoV-2. Among a total of 853 admissions (426 COVID-19, 138 MIS-C, and 289 asymptomatic SARS-CoV-2) in 814 patients, there were 20 patients with thrombotic events (TE) (including 1 stroke). Patients with MIS-C had the highest incidence (6.5%, 9/138) versus COVID-19 (2.1%, 9/426) or asymptomatic SARS-CoV-2 (0.7%, 2/289). In patients with COVID-19 or MIS-C, the majority of thrombotic events (89%) occurred in patients ≥12 years. Patients > 12 years with MIS-C had the highest rate of thrombosis at 19% (9/48). Notably, 71% of TE that were not present on admission occurred despite thromboprophylaxis. Multivariable analysis identified the following as significantly associated with thrombosis: age ≥12 years, cancer, presence of a central venous catheter, and MIS-C. In patients with COVID-19 or MIS-C, hospital mortality was 2.3% (13/564), but was 28% (5/18) in patients with thrombotic events. Our findings may help inform pediatric thromboprophylaxis strategies.

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ABSTRACT Background Understanding nosocomial acquisition, outbreaks and transmission chains in real-time will be fundamental to ensuring infection prevention measures are effective in controlling COVID-19 in healthcare. We report the design and implementation of a hospital-onset COVID-19 infection (HOCI) surveillance system for an acute healthcare setting to target prevention interventions. Methods The study took place in a large teaching hospital group in London, UK. All patients tested for SARS-CoV-2 between 4th March and 14th April 2020 were included. Utilising data routinely collected through electronic healthcare systems we developed a novel surveillance system for determining and reporting HOCI incidence and providing real-time network analysis. We provided daily reports on incidence and trends over time to support HOCI investigation, and generated geo-temporal reports using network analysis to interrogate admission pathways for common epidemiological links to infer transmission chains. By working with stakeholders the reports were co-designed for end users. Results Real-time surveillance reports revealed: changing rates of HOCI throughout the course of the COVID-19 epidemic; key wards fuelling probable transmission events; HOCIs over-represented in particular specialities managing high-risk patients; the importance of integrating analysis of individual prior pathways; and the value of co-design in producing data visualisation. Our surveillance system can effectively support national surveillance. Conclusions Through early analysis of the novel surveillance system we have provided a description of HOCI rates and trends over time using real-time shifting denominator data. We demonstrate the importance of including the analysis of patient pathways and networks in characterising risk of transmission and targeting infection control interventions.

Amelogenins are a group of extracellular enamel matrix proteins which are believed to be involved in the regulation of the size and habits of forming enamel crystals. The aim of this study was to compare the solubility properties of several amelogenins at various pH (from 4.0 to 9.0) at constant ionic strength (IS), and to examine the influence of buffer composition, IS, and divalent metal ions (including Ca2+, Mg2+, and Zn2+) on amelogenin solubility. The solubility of the recombinant murine amelogenin ("rM179") was minimum near its isoelectric point and increased rapidly below and above, regardless of buffer composition. A similar trend was observed for the native porcine ("25K") amelogenin. Porcine "23K" amelogenin was only sparingly soluble from pH of 4.0 to 9.0, in contrast to the analogous recombinant "rM166", which was more soluble in acidic solutions. The synthetic amelogenin polypeptide "TRAP" was extremely insoluble, while synthetic LRAP was readily soluble. Porcine "20K" amelogenin solubility increased strikingly as the solution pH was lowered from 7.0 to 6.0. Increasing IS decreased the solubility of rM179. While Zn2+ reduced rM179 solubility, Ca2+ and Mg2+ showed no significant effects. We conclude that the solubility of amelogenin was dependent on the primary structure, solution pH, and IS, and the low solubility of amelogenins under physiological conditions may result from their tendency to form quaternary (aggregate) structures in vivo.

Amelogenins are a group of extracellular enamel matrix proteins which are believed to be involved in the regulation of the size and habit of enamel crystals. The aim of this study was to compare the solubility properties of several amelogenins in various pH (4.0-9.0) solutions with an ionic strength (IS) of 0.15 M using the Micro BCA protein assay at 25 degrees C or 37 degrees C. The solubility of the recombinant amelogenin rM179 was lowest (0.7 mg/ml) close to its isoelectric point and it increased below and above this point. The solubility of the recombinant amelogenin rM166 remained almost the same (1-2 mg/ml) as the pH rose from 6.0 to 9.0 and it increased as the solution became more acidic. Synthetic "tyrosine-rich amelogenin polypeptide" (TRAP) was extremely insoluble (<0.2 mg/ml) in the pH range studied while synthetic "leucine-rich amelogenin polypeptide" (LRAP) was readily soluble (>3.3 mg/ml). The native porcine amelogenin with apparent molecular weight 25 kDa shared similar solubility behavior to rM179. The porcine 23 kDa amelogenin was only sparingly soluble (0.3-0.8 mg/ml) over a wide range of pH. Interestingly, the porcine 20 kDa amelogenin was remarkably soluble in the pH range of 4.0 to 6.0 (approximately 12 mg/ml), but the solubility dropped strikingly to only approximately 0.2 mg/ml at pH larger than approximately 7.0. The strong dependence of amelogenin solubility on solution pH may be involved in the regulation of aggregation, enzymatic degradation and the binding properties of amelogenins, thus playing an important role in enamel biomineralization.

Background The COVID-19 pandemic has presented one of the biggest challenges to healthcare providers worldwide. The appropriate use of Personal Protective Equipment (PPE) has been essential to ensuring staff and patient safety. To counteract sub-optimal PPE practice, a PPE helper programme was developed at a large London hospital group. Based on a behaviour change model of Capability, Opportunity and Motivation (COM-B), the programme provided PPE support, advice and education to ward staff. Aim Evaluation of the PPE Helper Programme. Methods Clinical and non-clinical ward staff completed a questionnaire informed by the Theoretical Domains Framework and COM-B. The questionnaire was available in paper and electronic versions. Quantitative responses were analysed using descriptive and non-parametric statistics, free-text responses were analysed thematically. Findings Over a six-week period, PPE helpers made 268 ward visits. Overall, 261 questionnaires were available for analysis. Across the Trust, 68% of respondents reported having had contact with a PPE helper. Staff who had encountered a PPE helper responded significantly more positively to a range of statements about using PPE than those who had not. Black and Minority Ethnic (BAME) staff were significantly more anxious in relation to the adequacy of PPE. Non-clinical and redeployed staff (e.g. domestic staff) were most positive about the impact of PPE helpers. Free-text comments showed that staff found the programme supportive and would have liked it earlier in the pandemic. Conclusion A PPE Helper programme is a feasible and beneficial intervention for providing support, advice and education to ward staff during infectious disease outbreaks.

We have proposed that these nanosphere structures are functionally involved in the organization and control of initial enamel biomineralization at the ultrastructural level. Based on the observed nanosphere hydrodynamic radii (18-20 nm diameter) computation suggests these structures to be compounded of some 100 amelogenin monomers, raising the question as to the possible molecular mechanism for the assembly of such structures? Based on recent dynamic light scattering experiments using the recombinant murine amelogenin M179, and employing a newer size distribution algorithm we now report that the size distribution data for M179 are better described by a bimodal distribution model, than the monomodal distribution as previously described. We suggest that amelogenin nanosphere assembly proceeds through intermediate structures (perhaps represented in vivo by "stippled material") of some 4-5 nm hydrodynamic radius, and computed to comprise 4-6 amelogenin monomers. We suggest that such intermediary, sub-unit structures, assemble through inter-molecular hydrophobic interactions to generate the 20 nm diameter nanospheres observed by TEM in the secretory stage enamel matrix.