Characterization of a unique attachment organelle: Single-cell force spectroscopy of Giardia duodenalis trophozoites

The unicellular parasite Giardia duodenalis is the causative agent of giardiasis, a gastrointestinal disease with global spread. In its trophozoite form, G. duodenalis can adhere to the human intestinal epithelium and a variety of other, artificial surfaces. Its attachment is facilitated by a unique microtubule-based attachment organelle, the so-called ventral disc. The mechanical function of the ventral disc, however, is still debated. Earlier studies postulated that a dynamic negative pressure under the ventral disc, generated by persistently beating flagella, mediates the attachment. Later studies suggested a suction model based on structural changes of the ventral discs, substrate clutching or grasping, or unspecific contact forces. In this study, we aim to contribute to the understanding of G. duodenalis attachment by investigating detachment characteristics and determining adhesion forces of single trophozoites on a smooth glass surface (RMS = 1.1 ± 0.2 nm) by fluidic force microscopy (FluidFM)-based single-cell force spectroscopy (SCFS). Briefly, viable adherent trophozoites were approached with a FluidFM micropipette, immobilized to the micropipette aperture by negative pressure, and detached from the surface by micropipette retraction while retract force curves were recorded. These force curves displayed novel and so far undescribed characteristics for a microorganism, namely, gradual force increase on the pulled trophozoite, with localization of adhesion force shortly before cell detachment length. Respective adhesion forces reached 7.7 ± 4.2 nN at 1 μm s-1 pulling speed. Importantly, this unique force pattern was different from that of other eukaryotic cells such as Candida albicans or oral keratinocytes, considered for comparison in this study. The latter both displayed a force pattern with force peaks of different values or force plateaus (for keratinocytes) indicative of breakage of molecular bonds of cell-anchored classes of adhesion molecules or membrane components. Furthermore, the attachment mode of G. duodenalis trophozoites was mechanically resilient to tensile forces, when the pulling speeds were raised up to 10 μm s-1 and adhesion forces increased to 28.7 ± 10.5 nN. Taken together, comparative SCSF revealed novel and unique retract force curve characteristics for attached G. duodenalis, suggesting a ligand-independent suction mechanism, that differ from those of other well described eukaryotes.

Endotracheal Tube Size Adjustments Within Seven Days of Neonatal Intubation

BACKGROUND AND OBJECTIVES

Neonatal endotracheal tube (ETT) size recommendations are based on limited evidence. We sought to determine data-driven weight-based ETT sizes for infants undergoing tracheal intubation and to compare these with Neonatal Resuscitation Program (NRP) recommendations.

METHODS

Retrospective multicenter cohort study from an international airway registry. We evaluated ETT size changes (downsizing to a smaller ETT during the procedure or upsizing to a larger ETT within 7 days) and risk of procedural adverse outcomes associated with first-attempt ETT size selection when stratifying the cohort into 200 g subgroups.

RESULTS

Of 7293 intubations assessed, the initial ETT was downsized in 5.0% of encounters and upsized within 7 days in 1.5%. ETT downsizing was most common when NRP-recommended sizes were attempted in the following weight subgroups: 1000 to 1199 g with a 3.0 mm (12.6%) and 2000 to 2199 g with a 3.5 mm (17.1%). For infants in these 2 weight subgroups, selection of ETTs 0.5 mm smaller than NRP recommendations was independently associated with lower odds of adverse outcomes compared with NRP-recommended sizes. Among infants weighing 1000 to 1199 g: any tracheal intubation associated event, 20.8% with 2.5 mm versus 21.9% with 3.0 mm (adjusted OR [aOR] 0.62, 95% confidence interval [CI] 0.41-0.94); severe oxygen desaturation, 35.2% with 2.5 mm vs 52.9% with 3.0 mm (aOR 0.53, 95% CI 0.38-0.75). Among infants weighing 2000 to 2199 g: severe oxygen desaturation, 41% with 3.0 mm versus 56% with 3.5mm (aOR 0.55, 95% CI 0.34-0.89).

CONCLUSIONS

For infants weighing 1000 to 1199 g and 2000 to 2199 g, the recommended ETT size was frequently downsized during the procedure, whereas 0.5 mm smaller ETT sizes were associated with fewer adverse events and were rarely upsized.

Factors that impact second attempt success for neonatal intubation following first attempt failure: a report from the National Emergency Airway Registry for Neonates

OBJECTIVE

To determine the factors associated with second attempt success and the risk of adverse events following a failed first attempt at neonatal tracheal intubation.

DESIGN

Retrospective analysis of prospectively collected data on intubations performed in the neonatal intensive care unit (NICU) and delivery room from the National Emergency Airway Registry for Neonates (NEAR4NEOS).

SETTING

Eighteen academic NICUs in NEAR4NEOS.

PATIENTS

Neonates requiring two or more attempts at intubation between October 2014 and December 2021.

MAIN OUTCOME MEASURES

The primary outcome was successful intubation on the second attempt, with severe tracheal intubation-associated events (TIAEs) or severe desaturation (≥20% decline in oxygen saturation) being secondary outcomes. Multivariate regression examined the associations between these outcomes and patient characteristics and changes in intubation practice.

RESULTS

5805 of 13 126 (44%) encounters required two or more intubation attempts, with 3156 (54%) successful on the second attempt. Second attempt success was more likely with changes in any of the following: intubator (OR 1.80, 95% CI 1.56 to 2.07), stylet use (OR 1.65, 95% CI 1.36 to 2.01) or endotracheal tube (ETT) size (OR 2.11, 95% CI 1.74 to 2.56). Changes in stylet use were associated with a reduced chance of severe desaturation (OR 0.74, 95% CI 0.61 to 0.90), but changes in intubator, laryngoscope type or ETT size were not; no changes in intubator or equipment were associated with severe TIAEs.

CONCLUSIONS

Successful neonatal intubation on a second attempt was more likely with a change in intubator, stylet use or ETT size.

Safety of primary nasotracheal intubation in the pediatric intensive care unit (PICU)

Background

Nasal tracheal intubation (TI) represents a minority of all TI in the pediatric intensive care unit (PICU). The risks and benefits of nasal TI are not well quantified. As such, safety and descriptive data regarding this practice are warranted.

Methods

We evaluated the association between TI route and safety outcomes in a prospectively collected quality improvement database (National Emergency Airway Registry for Children: NEAR4KIDS) from 2013 to 2020. The primary outcome was severe desaturation (SpO2 > 20% from baseline) and/or severe adverse TI-associated events (TIAEs), using NEAR4KIDS definitions. To balance patient, provider, and practice covariates, we utilized propensity score (PS) matching to compare the outcomes of nasal vs. oral TI.

Results

A total of 22,741 TIs [nasal 870 (3.8%), oral 21,871 (96.2%)] were reported from 60 PICUs. Infants were represented in higher proportion in the nasal TI than the oral TI (75.9%, vs 46.2%), as well as children with cardiac conditions (46.9% vs. 14.4%), both p < 0.001. Severe desaturation or severe TIAE occurred in 23.7% of nasal and 22.5% of oral TI (non-adjusted p = 0.408). With PS matching, the prevalence of severe desaturation and or severe adverse TIAEs was 23.6% of nasal vs. 19.8% of oral TI (absolute difference 3.8%, 95% confidence interval (CI): - 0.07, 7.7%), p = 0.055. First attempt success rate was 72.1% of nasal TI versus 69.2% of oral TI, p = 0.072. With PS matching, the success rate was not different between two groups (nasal 72.2% vs. oral 71.5%, p = 0.759).

Conclusion

In this large international prospective cohort study, the risk of severe peri-intubation complications was not significantly higher. Nasal TI is used in a minority of TI in PICUs, with substantial differences in patient, provider, and practice compared to oral TI.A prospective multicenter trial may be warranted to address the potential selection bias and to confirm the safety of nasal TI.

Adverse Tracheal Intubation Events in Critically Ill Underweight and Obese Children: Retrospective Study of the National Emergency Airway for Children Registry (2013-2020)

OBJECTIVES

Extremes of patient body mass index are associated with difficult intubation and increased morbidity in adults. We aimed to determine the association between being underweight or obese with adverse airway outcomes, including adverse tracheal intubation (TI)-associated events (TIAEs) and/or severe peri-intubation hypoxemia (pulse oximetry oxygen saturation < 80%) in critically ill children.

DESIGN/SETTING

Retrospective cohort using the National Emergency Airway for Children registry dataset of 2013-2020.

PATIENTS

Critically ill children, 0 to 17 years old, undergoing TI in PICUs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Registry data from 24,342 patients who underwent TI between 2013 and 2020 were analyzed. Patients were categorized using the Centers for Disease Control and Prevention weight-for-age chart: normal weight (5th-84th percentile) 57.1%, underweight (< 5th percentile) 27.5%, overweight (85th to < 95th percentile) 7.2%, and obese (≥ 95th percentile) 8.2%. Underweight was most common in infants (34%); obesity was most common in children older than 8 years old (15.1%). Underweight patients more often had oxygenation and ventilation failure (34.0%, 36.2%, respectively) as the indication for TI and a history of difficult airway (16.7%). Apneic oxygenation was used more often in overweight and obese patients (19.1%, 19.6%) than in underweight or normal weight patients (14.1%, 17.1%; p < 0.001). TIAEs and/or hypoxemia occurred more often in underweight (27.1%) and obese (24.3%) patients ( p < 0.001). TI in underweight children was associated with greater odds of adverse airway outcome compared with normal weight children after adjusting for potential confounders (underweight: adjusted odds ratio [aOR], 1.09; 95% CI, 1.01-1.18; p = 0.016). Both underweight and obesity were associated with hypoxemia after adjusting for covariates and site clustering (underweight: aOR, 1.11; 95% CI, 1.02-1.21; p = 0.01 and obesity: aOR, 1.22; 95% CI, 1.07-1.39; p = 0.002).

CONCLUSIONS

In underweight and obese children compared with normal weight children, procedures around the timing of TI are associated with greater odds of adverse airway events.

A multi-pronged approach to improve blood culture diagnostics in different clinical departments: a single-centre experience

PURPOSE

Blood culture (BC) diagnostics are influenced by many factors. We performed a targeted interdisciplinary analysis to analyse effects of various measures on BC diagnostics performance.

METHODS

A diagnostic stewardship initiative was conducted at two intervention and two control wards in a German tertiary level hospital. The initiative comprised staff training on the correct indications and sampling for BC, implementation of information cards, labels to identify the collection site, regular BC bottle feedback including the number of bottles, filling volumes and identified pathogens; and the use of a specific sampling device (BD Vacutainer®). Before and after the interventions, two three-month measurement periods were performed, as well as a one-month follow-up period to assess the sustainability of the conducted measures.

RESULTS

In total, 9362 BC bottles from 787 patients were included in the analysis. The number of BCs obtained from peripheral venous puncture could be increased at both intervention wards (44.0 vs. 22.2%, 58.3 vs. 34.4%), while arterial sampling could be reduced (30.6 vs. 4.9%). A total of 134 staff members were fully trained. The intervention led to a considerable increase in BC knowledge (from 62.4 to 79.8% correct answers) with differences between the individual professional groups. Relevant reduced contamination rates could be detected at both intervention wards.

CONCLUSIONS

As knowledge on the correct BC sampling and strategies to reduce contamination varies considerably between clinical departments and healthcare professionals, a targeted training should be adapted to the specific needs of the individual professional groups. An additional filling device is not necessary.

Ketamine Use in the Intubation of Critically Ill Children with Neurological Indications: A Multicenter Retrospective Analysis

BACKGROUND

Ketamine has traditionally been avoided for tracheal intubations (TIs) in patients with acute neurological conditions. We evaluate its current usage pattern in these patients and any associated adverse events.

METHODS

We conducted a retrospective observational cohort study of critically ill children undergoing TI for neurological indications in 53 international pediatric intensive care units and emergency departments. We screened all intubations from 2014 to 2020 entered into the multicenter National Emergency Airway Registry for Children (NEAR4KIDS) registry database. Patients were included if they were under the age of 18 years and underwent TI for a primary neurological indication. Usage patterns and reported periprocedural composite adverse outcomes (hypoxemia < 80%, hypotension/hypertension, cardiac arrest, and dysrhythmia) were noted.

RESULTS

Of 21,562 TIs, 2,073 (9.6%) were performed for a primary neurological indication, including 190 for traumatic brain injury/trauma. Patients received ketamine in 495 TIs (23.9%), which increased from 10% in 2014 to 41% in 2020 (p < 0.001). Ketamine use was associated with a coindication of respiratory failure, difficult airway history, and use of vagolytic agents, apneic oxygenation, and video laryngoscopy. Composite adverse outcomes were reported in 289 (13.9%) Tis and were more common in the ketamine group (17.0% vs. 13.0%, p = 0.026). After adjusting for location, patient age and codiagnoses, the presence of respiratory failure and shock, difficult airway history, provider demographics, intubating device, and the use of apneic oxygenation, vagolytic agents, and neuromuscular blockade, ketamine use was not significantly associated with increased composite adverse outcomes (adjusted odds ratio 1.34, 95% confidence interval CI 0.99-1.81, p = 0.057). This paucity of association remained even when only neurotrauma intubations were considered (10.6% vs. 7.7%, p = 0.528).

CONCLUSIONS

This retrospective cohort study did not demonstrate an association between procedural ketamine use and increased risk of peri-intubation hypoxemia and hemodynamic instability in patients intubated for neurological indications.

Evaluation of the Qvella FAST System and the FAST-PBC cartridge for rapid species identification and antimicrobial resistance testing directly from positive blood cultures

Blood culture diagnostics require rapid and accurate identification (ID) of pathogens and antimicrobial susceptibility testing (AST). Standard procedures, involving conventional cultivation on agar plates, may take up to 48 hours or more until AST completion. Recent approaches aim to shorten the processing time of positive blood cultures (PBC). The FAST System is a new technology, capable of purifying and concentrating bacterial/fungal pathogens from positive blood culture media and producing a bacterial suspension called "liquid colony" (LC), which can be further used in downstream analyses (e.g., ID and AST). Here, we evaluated the performance of the FAST System LC generated from PBC in comparison to our routine workflow including ID by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using Sepsityper, AST by automatized MicroScan WalkAway plus and directly inoculated disk diffusion (DD), and MICRONAUT-AM for yeast/fungi. A total of 261 samples were analyzed, of which 86.6% (226/261) were eligible for the comparative ID and AST analyses. In comparison to the reference technique (culture-grown colonies), ID concordance of the FAST System LC and Sepsityper was 150/154 (97.4%) and 123/154 (79.9%), respectively, for Gram positive; 67/70 (95.7%) and 64/70 (91.4%), respectively, for Gram negative. For AST, categorical agreement (CA) of the FAST System LC in comparison to the routine workflow for Gram-positive bacteria was 96.1% and 98.7% for MicroScan and DD, respectively. Similar results were obtained for Gram-negative bacteria with 96.6% and 97.5% of CA for MicroScan and DD, respectively. Taken together, the FAST System LC allowed the laboratory to significantly reduce the time to obtain correct ID and AST (automated MicroScan) results 1 day earlier and represents a promising tool to expedite the processing of PBC.

[Update 2022: interdisciplinary statement on airway management with supraglottic airway devices in pediatric emergency medicine-The laryngeal mask is and remains state of the art : Joint statement of the Institute for Emergency Medicine and Medicine Management (INM), the University Clinic Munich, LMU Munich, Germany, the Working Group for Pediatric Critical Care and Emergency Medicine of the German Interdisciplinary Society for Critical Care and Emergency Medicine (DIVI), the Medical Directors of Emergency Medical Services in Bavaria (ÄLRD), the Scientific Working Group for Pediatric Anesthesia (WAKKA) of the German Society for Anesthesiology and Intensive Care Medicine (DGAI), the Scientific Working Group for Emergency Medicine of the German Society for Anesthesiology and Intensive Care Medicine (DGAI) and the Society of Neonatology and Pediatric Critical Care Medicine (GNPI)]

BACKGROUND

Airway management with supraglottic airway devices (SGA) in life-threatening emergencies in children is increasingly being used. Different specifications of laryngeal masks (LM) and the laryngeal tube (LT) are commonly used devices for this purpose. We present a literature review and interdisciplinary consensus statement of different societies on the use of SGA in pediatric emergency medicine.

MATERIAL AND METHODS

Literature review in the PubMed database and classification of studies according to the criteria of the Oxford Centre for Evidence-based Medicine. Levels and consensus finding within the group of authors.

RESULTS

The evidence for successful applications of the various types of LM is significantly higher than for LT application. Reported smaller series of successful applications of LT are currently limited to selected research groups and centers. Especially for children below 10 kg body weight there currently exists insufficient evidence for the successful application of the LT and therefore its routine use cannot be recommended. SGAs used for emergencies should have a gastric drainage possibility.

DISCUSSION

Considering the scientific data and the large clinical experience with the LM in medical routine and emergency situations in children currently only the LM can be recommended for alternative (i.e., non-intubation) emergency airway management in children. If alternative airway management is part of a local emergency strategy, the LM should be provided in all pediatric sizes (1, 1½, 2, 2½, 3) for out of hospital use and in hospital emergency use and all users should regularly be trained in its application.

Electrophysiological and calcium-handling development during long-term culture of human-induced pluripotent stem cell-derived cardiomyocytes

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are increasingly used for personalised medicine and preclinical cardiotoxicity testing. Reports on hiPSC-CM commonly describe heterogenous functional readouts and underdeveloped or immature phenotypical properties. Cost-effective, fully defined monolayer culture is approaching mainstream adoption; however, the optimal age at which to utilise hiPSC-CM is unknown. In this study, we identify, track and model the dynamic developmental behaviour of key ionic currents and Ca2+-handling properties in hiPSC-CM over long-term culture (30-80 days). hiPSC-CMs > 50 days post differentiation show significantly larger ICa,L density along with an increased ICa,L-triggered Ca2+-transient. INa and IK1 densities significantly increase in late-stage cells, contributing to increased upstroke velocity and reduced action potential duration, respectively. Importantly, our in silico model of hiPSC-CM electrophysiological age dependence confirmed IK1 as the key ionic determinant of action potential shortening in older cells. We have made this model available through an open source software interface that easily allows users to simulate hiPSC-CM electrophysiology and Ca2+-handling and select the appropriate age range for their parameter of interest. This tool, together with the insights from our comprehensive experimental characterisation, could be useful in future optimisation of the culture-to-characterisation pipeline in the field of hiPSC-CM research.

Pre-hospital analgesia in pediatric trauma and critically ill patients: An analysis of a German air rescue service

BACKGROUND

Pain management in the pre-hospital setting remains a particular challenge for paramedics and emergency physicians, especially in children. This study evaluates the pre-hospital use and effect of analgesics in children with trauma or pain due to other reasons.

METHODS

This study is a retrospective analysis of the database of a German air rescue service and was conducted over a period of 9 years (2012-2020) to assess pain in general and whether patients with trauma pain due to other reasons received treatment with analgesics. We included all patients in the registry under the age of 16 years. Patients with a Glasgow Coma Scale of 3 at hospital admission and incomplete records were excluded. The intensity of pain was determined by the emergency physician on scene at arrival and hospital admission in a ten-point rating scale (0 = no pain). Effective pain reduction was analyzed.

RESULTS

Out of 227,458 cases, a total of 22,025 emergency cases involved pediatric patients aged 0-16 years. 20,405 cases were included in the study. 12,000 (58.8%) children had suffered a trauma, 8108 (39.7%) had pain due to other reasons and 297 (1.5%) had both. In total, 4,608 (38.4%) of the children with trauma were assessed having a numerical rating scale (NRS) > 4 at EMS arrival. These patients received mainly ketamine (34.5%) and the opioids fentanyl (38.7%) and piritramide (19.1%). The value on the NRS was significantly lower at admission to hospital (mean 1.9) compared with the EMS arrival (mean 6.9). In 4.9% the NRS at hospital admission was still > 4. 282 patients within the non-trauma group had a pre-hospital NRS of > 4. The pain therapy consisted of opioids (35.8%) and ketamine (2.8%). 28.4% patients in the non-trauma group received no pain medication. In 16.0% the NRS at hospital admission was still > 4.

CONCLUSIONS

German emergency physicians achieved a sufficient pain therapy in pediatric patients with a NRS > 4 after trauma. In case of non-trauma, the pain management by the emergency physicians is restrained and less successful. The most common analgesic medications administered were ketamine and fentanyl, followed by piritramide.

TRIAL REGISTRATION

The study has been retrospectively registered at DRKS (DRKS00026222).

Characterization of the Elasticity of CD4+ T Cells: An Approach Based on Peak Force Quantitative Nanomechanical Mapping

CD4⁺ T cells are essential players in orchestrating the specific immune response against intracellular pathogens, and in inhibiting tumor development in an early stage. The activation of T cells is triggered by engagement of T cell receptors (TCRs). Here, CD3 and CD28 molecules are key factors, (co)stimulating signaling pathways essential for activation and proliferation of CD4⁺ T cells. T cell activation induces the formation of a tight mechanical bond between T cell and target cell, the so-called immunological synapse (IS). Due to this, mechanical cell properties, including stiffness, play a significant role in modulating cell functions. In the past, many approaches were made to investigate mechanical properties of immune cells, including micropipette aspiration, microplate-based rheometry, techniques based on deformation during cytometry, or the use of optical tweezers. However, the stiffness of T lymphocytes at a subcellular level at the IS still remains largely elusive. With this protocol, we introduce a method based on atomic force microscopy (AFM), to investigate the local cellular stiffness of T cells on functionalized glass/Polydimethylsiloxan (PDMS) surfaces, which mimicks focal stimulation of target cells inducing IS formation by T cells. By applying the peak force nanomechanical mapping (QNM) technique, cellular surface structures and the local stiffness are determined simultaneously, with a resolution of approximately 60 nm. This protocol can be easily adapted to investigate the mechanical impact of numerous factors influencing IS formation and T cell activation. Graphical abstract: Overview of the experimental workflow. Individual experimental steps are shown on the left, hands on and incubation times for each step are shown right.

Intubation practice and outcomes among pediatric emergency departments: A report from National Emergency Airway Registry for Children (NEAR4KIDS)

BACKGROUND

Tracheal intubation (TI) practice across pediatric emergency departments (EDs) has not been comprehensively reported. We aim to describe TI practice and outcomes in pediatric EDs in contrast to those in intensive are units (ICUs) and use the data to identify quality improvement targets.

METHODS

Consecutive TI encounters from pediatric EDs and ICUs in the National Emergency Airway Registry for Children (NEAR4KIDS) database from 2015 to 2018 were analyzed for patient, provider, and practice characteristics and outcomes: adverse TI-associated events (TIAEs), oxygen desaturation (SpO₂ < 80%), and procedural success. A multivariable model identified factors associated with TIAEs in the ED.

RESULTS

A total of 756 TIs in 13 pediatric EDs and 12,512 TIs in 51 pediatric/cardiac ICUs were reported. Median (interquartile range [IQR]) patient age for ED TIs was higher (32 [7-108] months) than that for ICU TIs (15 [3-91] months; p < 0.001). Proportion of TIs for respiratory decompensation (52% of ED vs. 64% ICU), shock (26% vs. 14%), and neurologic deterioration (30% vs. 11%) also differed by location. Limited neck mobility was reported more often in the ED (16% vs. 6%). TIs in the ED were performed more often via video laryngoscopy (64% vs. 29%). Adverse TIAE rates (15.6% ED, 14% ICU; absolute difference = 1.6%, 95% confidence interval [CI] = -1.1 to 4.2; p = 0.23) and severe TIAE rates (5.4% ED, 5.8% ICU; absolute difference = -0.3%, 95% CI = -2.0 to 1.3; p = 0.68) were not different. Oxygen desaturation was less commonly reported in ED TIs (13.6%) than ICU TIs (17%, absolute difference = -3.4%, 95% CI = -5.9 to -0.8; p = 0.016). Among ED TIs, shock as an indication (adjusted odds ratio [aOR] = 2.15, 95% CI = 1.26 to 3.65) and limited mouth opening (aOR = 1.74, 95% CI = 1.04 to 2.93) were independently associated with TIAEs.

CONCLUSIONS

While TI characteristics vary between pediatric EDs and ICUs, outcomes are similar. Shock and limited mouth opening were independently associated with adverse TI events in the ED.

Antigen-Specific vs. Neutralizing Antibodies Against Conditioned Media of Patients With Clostridioides difficile Infection: A Prospective Exploratory Study

The immunological response against Clostridioides difficile (C. difficile) is crucial for an improved understanding of disease mechanisms and the development of novel therapeutic strategies. From April 2014 to February 2015, adult patients with C. difficile infection (CDI) were recruited, and the clinical course and treatment response were carefully monitored. On day 1, 3, and 6 after diagnosis, patient plasma samples were screened for anti-GDH (glutamate dehydrogenase), anti-TcdA, anti-TcdB, and anti-CWP84 (cell-wall protein 84) antibodies by ELISA. Additionally, neutralization assays of toxins from conditioned media of clinical isolates (RT010, RT014, and RT027) were performed. Most patients with CDI (n = 46) had antibodies against GDH (85%) and CWP84 (61%), but only few had antibodies against TcdA (11%) and TcdB (28%). We found patients with neutralizing antibodies against C. difficile toxins (conditioned media) produced by RT027 (26%). A subgroup of these samples could neutralize both toxins from RT027 and RT014 [11%, (5/46)]; however, no single sample neutralized only RT014. Overall, neutralizing antibody titers were low (≤1:16). In a one week follow-up of acute infection, we never observed an early booster effect with seroconversion or antibody increases, irrespective of disease severity. No correlation was found between the presence of antigen-specific (ELISA) or neutralizing antibodies and the clinical course of disease. Anti-TcdB but not anti-TcdA antibodies correlated with the occurrence of neutralizing antibodies. In conclusion, natural antibody titers against C. difficile toxins were absent or low and were not associated with disease severity. The correlation between the anti-TcdB with toxin neutralization confirms the importance of TcdB for virulence of CDI. Alternative sensitization strategies, e.g., through vaccine development, are required to overcome the regular low-titer antibody production following natural intestinal C. difficile exposure.

Does videolaryngoscopy improve tracheal intubation first attempt success in the NICUs? A report from the NEAR4NEOS

OBJECTIVE

We hypothesized that videolaryngoscope use for tracheal intubations would differ across NICUs, be associated with higher first attempt success and lower adverse events.

STUDY DESIGN

Data from the National Emergency Airway Registry for Neonates (01/2015 to 12/2017) included intubation with direct laryngoscope or videolaryngoscope. Primary outcome was first attempt success. Secondary outcomes were adverse tracheal intubation associated events and severe desaturation.

RESULTS

Of 2730 encounters (13 NICUs), 626 (23%) utilized a videolaryngoscope (3% to 64% per site). Videolaryngoscope use was associated with higher first attempt success (p < 0.001), lower adverse tracheal intubation associated events (p < 0.001), but no difference in severe desaturation. After adjustment, videolaryngoscope use was not associated with higher first attempt success (OR:1.18, p = 0.136), but was associated with lower tracheal intubation associated events (OR:0.45, p < 0.001).

CONCLUSION

Videolaryngoscope use is variable, not independently associated with higher first attempt success but associated with fewer tracheal intubation associated events.

Anatomic accuracy, physiologic characteristics, and fidelity of very low birth weight infant airway simulators

BACKGROUND

Medical simulation training requires realistic simulators with high fidelity. This prospective multi-center study investigated anatomic precision, physiologic characteristics, and fidelity of four commercially available very low birth weight infant simulators.

METHODS

We measured airway angles and distances in the simulators Premature AirwayPaul (SIMCharacters), Premature Anne (Laerdal Medical), Premie HAL S2209 (Gaumard), and Preterm Baby (Lifecast Body Simulation) using computer tomography and compared these to human cadavers of premature stillbirths. The simulators' physiologic characteristics were tested, and highly experienced experts rated their physical and functional fidelity.

RESULTS

The airway angles corresponded to those of the reference cadavers in three simulators. The nasal inlet to glottis distance and the mouth aperture to glottis distance were only accurate in one simulator. All simulators had airway resistances up to 20 times higher and compliances up to 19 times lower than published reference values. Fifty-six highly experienced experts gave three simulators (Premature AirwayPaul: 5.1 ± 1.0, Premature Anne 4.9 ± 1.1, Preterm Baby 5.0 ± 1.0) good overall ratings and one simulator (Premie HAL S2209: 2.8 ± 1.0) an unfavorable rating.

CONCLUSION

The simulator physiology deviated significantly from preterm infants' reference values concerning resistance and compliance, potentially promoting a wrong ventilation technique.

IMPACT

Very low birth weight infant simulators showed physiological properties far deviating from corresponding patient reference values. Only ventilation with very high peak pressure achieved tidal volumes in the simulators, as aimed at in very low birth weight infants, potentially promoting a wrong ventilation technique. Compared to very low birth weight infant cadavers, most tested simulators accurately reproduced the anatomic angular relationships, but their airway dimensions were relatively too large for the represented body. The more professional experience the experts had, the lower they rated the very low birth weight infant simulators.

Using Knock-Out Mutants to Investigate the Adhesion of Staphylococcus aureus to Abiotic Surfaces

The adhesion of Staphylococcus aureus to abiotic surfaces is crucial for establishing device-related infections. With a high number of single-cell force spectroscopy measurements with genetically modified S. aureus cells, this study provides insights into the adhesion process of the pathogen to abiotic surfaces of different wettability. Our results show that S. aureus utilizes different cell wall molecules and interaction mechanisms when binding to hydrophobic and hydrophilic surfaces. We found that covalently bound cell wall proteins strongly interact with hydrophobic substrates, while their contribution to the overall adhesion force is smaller on hydrophilic substrates. Teichoic acids promote adhesion to hydrophobic surfaces as well as to hydrophilic surfaces. This, however, is to a lesser extent. An interplay of electrostatic effects of charges and protein composition on bacterial surfaces is predominant on hydrophilic surfaces, while it is overshadowed on hydrophobic surfaces by the influence of the high number of binding proteins. Our results can help to design new models of bacterial adhesion and may be used to interpret the adhesion of other microorganisms with similar surface properties.

Quantification of the Adhesion Strength of Candida albicans to Tooth Enamel

Caries is one of the most prevalent diseases worldwide, which is caused by the degradation of the tooth enamel surface. In earlier research the opportunistic pathogen Candida albicans has been associated with the formation of caries in children. Colonization of teeth by C. albicans starts with the initial adhesion of individual yeast cells to the tooth enamel surface. In this study, we visualized the initial colonization of C. albicans yeast cells on pellicle-covered enamel by scanning electron microscopy. To quantitatively unravel the initial adhesion strength, we applied fluidic force microscopy-based single-cell force spectroscopy to examine the key adhesion parameters adhesion force, rupture length and de-adhesion work. We analyzed single saliva-treated or untreated yeast cells on tooth enamel specimens with or without salivary pellicle. Under all tested conditions, adhesion forces in the lower nanonewton range were determined. Furthermore, we have found that all adhesion parameters were enhanced on the pellicle-covered compared to the uncovered enamel. Our data suggest that initial adhesion occurs through a strong interaction between yeast cell wall-associated adhesins and the salivary pellicle. Future SCFS studies may show whether specific management of the salivary pellicle reduces the adhesion of C. albicans on teeth and thus contributes to caries prophylaxis.

Experiences with pre-travel diagnostic PCR testing for SARS-CoV-2: challenges and opportunities

This study explores challenges and opportunities arising from pre-travel severe acute respiratory syndrome coronavirus 2 diagnostics for the conduct of travel medicine clinics. We found that such testing might offer huge opportunities to reach individuals who would otherwise not present to travel medicine clinics, such as individuals visiting friends and relatives in malaria-endemic countries.

T cell stiffness is enhanced upon formation of immunological synapse

T cells are activated by target cells via an intimate contact, termed immunological synapse (IS). Cellular mechanical properties, especially stiffness, are essential to regulate cell functions. However, T cell stiffness at a subcellular level at the IS still remains largely elusive. In this work, we established an atomic force microscopy (AFM)-based elasticity mapping method on whole T cells to obtain an overview of the stiffness with a resolution of ~60 nm. Using primary human CD4⁺ T cells, we show that when T cells form IS with stimulating antibody-coated surfaces, the lamellipodia are stiffer than the cell body. Upon IS formation, T cell stiffness is enhanced both at the lamellipodia and on the cell body. Chelation of intracellular Ca²⁺ abolishes IS-induced stiffening at the lamellipodia but has no influence on cell-body-stiffening, suggesting different regulatory mechanisms of IS-induced stiffening at the lamellipodia and the cell body.

Associations between family presence and neonatal intubation outcomes: a report from the National Emergency Airway Registry for Neonates: NEAR4NEOS

OBJECTIVE

Describe the current practice of family presence during neonatal tracheal intubations (TIs) across neonatal intensive care units (NICUs) and examine the association with outcomes.

DESIGN

Retrospective analysis of TIs performed in NICUs participating in the National Emergency Airway Registry for Neonates (NEAR4NEOS).

SETTING

Thirteen academic NICUs.

PATIENTS

Infants undergoing TI between October 2014 and December 2017.

MAIN OUTCOME MEASURES

Association of family presence with TI processes and outcomes including first attempt success (primary outcome), success within two attempts, adverse TI-associated events (TIAEs) and severe oxygen desaturation ≥20% from baseline.

RESULTS

Of the 2570 TIs, 242 (9.4%) had family presence, which varied by site (median 3.6%, range 0%-33%; p<0.01). Family member was more often present for older infants and those with chronic respiratory failure. Fewer TIs were performed by residents when family was present (FP 10% vs no FP 18%, p=0.041). Among TIs with family presence versus without family presence, the first attempt success rate was 55% vs 49% (p=0.062), success within two attempts was 74% vs 66% (p=0.014), adverse TIAEs were 18% vs 20% (p=0.62) and severe oxygen desaturation was 49% vs 52%, (p=0.40). In multivariate analyses, there was no independent association between family presence and intubation success, adverse TIAEs or severe oxygen desaturation.

CONCLUSION

Family are present in less than 10% of TIs, with variation across NICUs. Even after controlling for important patient, provider and site factors, there were no significant associations between family presence and intubation success, adverse TIAEs or severe oxygen desaturation.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

Impact of Physician Training Level on Neonatal Tracheal Intubation Success Rates and Adverse Events: A Report from National Emergency Airway Registry for Neonates (NEAR4NEOS)

INTRODUCTION

Neonatal tracheal intubation (TI) outcomes have been assessed by role, but training level may impact TI success and safety. Effect of physician training level (PTL) on the first-attempt success, adverse TI-associated events (TIAEs), and oxygen desaturation was assessed.

METHODS

Prospective cohort study in 11 international NEAR4NEOS sites between October 2014 and December 2017. Primary TIs performed by pediatric/neonatal physicians were included. Univariable analysis evaluated association between PTL, patient/practice characteristics, and outcomes. Multivariable analysis with generalized estimating equation assessed for independent association between PTL and outcomes (first-attempt success, TIAEs, and oxygen desaturation ≥20%; attending as reference).

RESULTS

Of 2,608 primary TIs, 1,298 were first attempted by pediatric/neonatal physicians. PTL was associated with patient age, weight, comorbidities, TI indication, difficult airway history, premedication, and device. First-attempt success rate differed across PTL (resident 23%, fellow 53%, and attending 60%; p < 0.001). There was no statistically significant difference in TIAEs (resident 22%, fellow 20%, and attending 25%; p = 0.34). Desaturation occurred more frequently with residents (60%), compared to fellows and attendings (46 and 53%; p < 0.001). In multivariable analysis, adjusted odds ratio of the first-attempt success was 0.18 (95% CI: 0.11-0.30) for residents and 0.80 (95% CI: 0.51-1.24) for fellows. PTL was not independently associated with adjusted odds of TIAEs or severe oxygen desaturation.

CONCLUSION

Higher PTL was associated with increased first-attempt success but not TIAE/oxygen desaturation. Identifying strategies to decrease adverse events during neonatal TI remains critical.

Team Stress and Adverse Events during Neonatal Tracheal Intubations: A Report from NEAR4NEOS

OBJECTIVE

This study aimed to examine the association between team stress level and adverse tracheal intubation (TI)-associated events during neonatal intubations.

STUDY DESIGN

TIs from 10 academic neonatal intensive care units were analyzed. Team stress level was rated immediately after TI using a 7-point Likert scale (1 = high stress). Associations among team stress, adverse TI-associated events, and TI characteristics were evaluated.

RESULT

In this study, 208 of 2,009 TIs (10%) had high stress levels (score < 4). Oxygenation failure, hemodynamic instability, and family presence were associated with high stress level. Video laryngoscopy and premedication were associated with lower stress levels. High stress level TIs were associated with adverse TI-associated event rates (31 vs. 16%, p < 0.001), which remained significant after adjusting for potential confounders including patient, provider, and practice factors associated with high stress (odds ratio: 1.90, 96% confidence interval: 1.36-2.67, p < 0.001).

CONCLUSION

High team stress levels during TI were more frequently reported among TIs with adverse events.

Genetic variants in calcium regulatory cardiac genes and their contribution to Takotsubo syndrome

Background and purpose

Takotsubo syndrome (TTS) is characterized by an acute left ventricular dysfunction similar to a myocardial infarction (MI) in the absence of coronary artery stenosis. Patients show symptoms similar to the acute MI with increased biomarkers and blood serum catecholamines. Recently, we developed a patient-specific TTS stem cell model and identified a higher sensitivity to catecholamine-induced stress. Furthermore, familial TTS cases and genetic studies point to a genetic predisposition. The purpose of this study was to analyze a genetic predisposition by characterizing genetic variants in genes associated with cardiac pathologies and their impact on calcium homoeostasis in TTS.

Methods and results

Whole exome sequencing analysis of a TTS patient discovered 2 missense AHNAK variants in its C-terminal domain and in addition the missense variant F189L in the calcium buffering calsequestrin 2 gene (CASQ2). AHNAK is a 700kDa big nucleoprotein and is involved in the β-adrenergic regulation of the cardiac calcium channel Cav1.2. 3-month old TTS-iPSC-derived cardiomyocytes (CM) were generated and the variants were confirmed by sequencing. We found AHNAK higher expressed in TTS-iPSC-CMs compared to control, whereas no expression alteration was observed for Cav1.2. Since AHNAK is described to act as a repressor towards Cav1.2, which is relieved under β-adrenergic stimulation, we analyzed the effect of AHNAK variants on a potential co-localization and interaction between both proteins. AHNAK and Cav1.2 were shown to co-localize in the cytoplasm as well as the membranes and co-immunoprecipitation experiments confirmed an interaction of AHNAK and Cav1.2 in all tested control- and TTS-iPSC-CMs. On a functional level, we were able to show by patch clamp analysis that Cav1.2 calcium currents are significantly increased in TTS-iPSC-CMs compared to control. The influence of CASQ2-F189L on sarcomeric reticulum (SR) calcium load was analyzed by epifluorescence microscopy using FURA4 and caffeine-applications. We found significantly decreased SR calcium content with an increased fractional release during systole in TTS-iPSC-CMs. To test, whether these variants are the main reason for altered interaction of AHNAK and Cav1.2, calcium currents or SR calcium load in TTS need to be proven in the future by using CRISPR/Cas9-rescued AHNAK/CASQ2 lines.

Conclusion

Here we show the cardiac functional consequences of AHNAK and CASQ2 missense mutations in TTS-iPSC-CMs with regard to calcium currents and SR calcium load. These results show that AHNAK and CASQ2 variants may predispose to TTS and enable a new therapeutic option for TTS.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Else Kröner-Fresenius Foundation

Candida albicans adhesion to central venous catheters: Impact of blood plasma-driven germ tube formation and pathogen-derived adhesins

Candida albicans-related bloodstream infections are often associated with infected central venous catheters (CVC) triggered by microbial adhesion and biofilm formation. We utilized single-cell force spectroscopy (SCFS) and flow chamber models to investigate the adhesion behavior of C. albicans yeast cells and germinated cells to naïve and human blood plasma (HBP)-coated CVC tubing. Germinated cells demonstrated up to 56.8-fold increased adhesion forces to CVC surfaces when compared to yeast cells. Coating of CVCs with HBP significantly increased the adhesion of 60-min germinated cells but not of yeast cells and 30-min germinated cells. Under flow conditions comparable to those in major human veins, germinated cells displayed a flow directional-orientated adhesion pattern to HBP-coated CVC material, suggesting the germ tip to serve as the major adhesive region. None of the above-reported phenotypes were observed with germinated cells of an als3Δ deletion mutant, which displayed similar adhesion forces to CVC surfaces as the isogenic yeast cells. Germinated cells of the als3Δ mutant also lacked a clear flow directional-orientated adhesion pattern on HBP-coated CVC material, indicating a central role for Als3 in the adhesion of germinated C. albicans cells to blood exposed CVC surfaces. In the common model of C. albicans, biofilm formation is thought to be mediated primarily by yeast cells, followed by surface-triggered the formation of hyphae. We suggest an extension of this model in which C. albicans germ tubes promote the initial adhesion to blood-exposed implanted medical devices via the germ tube-associated adhesion protein Als3.

Different binding mechanisms of Staphylococcus aureus to hydrophobic and hydrophilic surfaces

Bacterial adhesion to surfaces is a crucial step in initial biofilm formation. In a combined experimental and computational approach, we studied the adhesion of the pathogenic bacterium Staphylococcus aureus to hydrophilic and hydrophobic surfaces. We used atomic force microscopy-based single-cell force spectroscopy and Monte Carlo simulations to investigate the similarities and differences of adhesion to hydrophilic and hydrophobic surfaces. Our results reveal that binding to both types of surfaces is mediated by thermally fluctuating cell wall macromolecules that behave differently on each type of substrate: on hydrophobic surfaces, many macromolecules are involved in adhesion, yet only weakly tethered, leading to high variance between individual bacteria, but low variance between repetitions with the same bacterium. On hydrophilic surfaces, however, only few macromolecules tether strongly to the surface. Since during every repetition with the same bacterium different macromolecules bind, we observe a comparable variance between repetitions and different bacteria. We expect these findings to be of importance for the understanding of the adhesion behaviour of many bacterial species as well as other microorganisms and even nanoparticles with soft, macromolecular coatings, used e.g. for biological diagnostics.

Dynamic catch-bonding generates the large stall forces of cytoplasmic dynein

Cytoplasmic dynein is an important molecular motor involved in the transport of vesicular and macromolecular cargo along microtubules in cells, often in conjunction with kinesin motors. Dynein is larger and more complex than kinesin and the mechanism and regulation of its movement is currently the subject of intense research. While it was believed for a long time that dynein motors are relatively weak in terms of the force they can generate, recent studies have shown that interactions with regulatory proteins confer large stall forces comparable to those of kinesin. This paper reports on a theoretical study which suggests that these large stall forces may be the result of an emergent, ATP-dependent, bistability resulting in a dynamic catch-bonding behavior that can cause the motor to switch between high and low load-force states.

Active perinatal care of preterm infants in the German Neonatal Network

OBJECTIVE

To determine if survival rates of preterm infants receiving active perinatal care improve over time.

DESIGN

The German Neonatal Network is a cohort study of preterm infants with birth weight <1500 g. All eligible infants receiving active perinatal care are registered. We analysed data of patients discharged between 2011 and 2016.

SETTING

43 German level III neonatal intensive care units (NICUs).

PATIENTS

8222 preterm infants with a gestational age between 22/0 and 28/6 weeks who received active perinatal care.

INTERVENTIONS

Participating NICUs were grouped according to their specific survival rate from 2011 to 2013 to high (percentile >P75), intermediate (P25-P75) and low (<P25) survival. We compared these survival rates with data in 2014-2016.

MAIN OUTCOME MEASURES

Death by any cause before discharge.

RESULTS

Total survival increased from 85.8% in 2011-2013 to 87.4% in 2014-2016. This increase was due to reduced mortality of NICUs with low survival rates in 2011-2013. Survival increased in these centres from 53% to 64% in the 22-24 weeks strata and from 73% to 84% in the 25-26 weeks strata.

CONCLUSIONS

Our data support previous reports that active perinatal care of very immature infants improves outcomes at the border of viability and survival rates at higher gestational ages. The high total number of surviving infants below 24 weeks of gestation challenges national recommendations exclusively referring to gestational age as the single criterion for providing active care. However, more data are needed before recommendations for parental counselling should be reconsidered.

TRIAL REGISTRATION

Approval by the local institutional review board for research in human subjects of the University of Lübeck (file number 08-022) and by the local ethic committees of all participating centres has been given.

Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA

We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of compact objects, that is binary neutron star, neutron star-black hole, and binary black hole systems. The ability to localize the sources is given as a sky-area probability, luminosity distance, and comoving volume. The median sky localization area (90% credible region) is expected to be a few hundreds of square degrees for all types of binary systems during O3 with the Advanced LIGO and Virgo (HLV) network. The median sky localization area will improve to a few tens of square degrees during O4 with the Advanced LIGO, Virgo, and KAGRA (HLVK) network. During O3, the median localization volume (90% credible region) is expected to be on the order of 10 5 , 10 6 , 10 7 Mpc 3 for binary neutron star, neutron star-black hole, and binary black hole systems, respectively. The localization volume in O4 is expected to be about a factor two smaller than in O3. We predict a detection count of 1 - 1 + 12 ( 10 - 10 + 52 ) for binary neutron star mergers, of 0 - 0 + 19 ( 1 - 1 + 91 ) for neutron star-black hole mergers, and 17 - 11 + 22 ( 79 - 44 + 89 ) for binary black hole mergers in a one-calendar-year observing run of the HLV network during O3 (HLVK network during O4). We evaluate sensitivity and localization expectations for unmodeled signal searches, including the search for intermediate mass black hole binary mergers.

More Than 500 Kids Could Be Saved Each Year! Ten Consensus Actions to Improve Quality of Pediatric Resuscitation in DACH-Countries (Austria, Germany, and Switzerland)

• Quality and outcome of pediatric resuscitation often does not achieve recommended goals. • Quality improvement initiatives with the aim of better survival rates and decreased morbidity of resuscitated children are urgently needed. • These initiatives should include an action framework for a comprehensive, fundamental, and interprofessional reorientation of clinical and organizational structures concerning resuscitation and post-resuscitation care of children. • The authors of this DACH position statement suggest the implementation of 10 evidence-based actions (for out-of-hospital and in-house cardiac arrests) that should improve survival rates and decrease morbidity of resuscitated children with better neurological outcome and quality of life.

Glycidyl Tosylate: Polymerization of a "Non-Polymerizable" Monomer permits Universal Post-Functionalization of Polyethers

Glycidyl tosylate appears to be a non-polymerizable epoxide when nucleophilic initiators are used because of the excellent leaving group properties of the tosylate. However, using the monomer-activated mechanism, this unusual monomer can be copolymerized with ethylene oxide (EO) and propylene oxide (PO), respectively, yielding copolymers with 7-25 % incorporated tosylate-moieties. The microstructure of the copolymers was investigated via in situ 1 H NMR spectroscopy, and the reactivity ratios of the copolymerizations have been determined. Quantitative nucleophilic substitution of the tosylate-moiety is demonstrated for several examples. This new structure provides access to a library of functionalized polyethers that cannot be synthesized by conventional oxyanionic polymerization.

DNA accessibility of chromatosomes quantified by automated image analysis of AFM data

DNA compaction and accessibility in eukaryotes are governed by nucleosomes and orchestrated through interactions between DNA and DNA-binding proteins. Using QuantAFM, a method for automated image analysis of atomic force microscopy (AFM) data, we performed a detailed statistical analysis of structural properties of mono-nucleosomes. QuantAFM allows fast analysis of AFM images, including image preprocessing, object segmentation, and quantification of different structural parameters to assess DNA accessibility of nucleosomes. A comparison of nucleosomes reconstituted with and without linker histone H1 quantified H1's already described ability of compacting the nucleosome. We further employed nucleosomes bearing two charge-modifying mutations at position R81 and R88 in histone H2A (H2A R81E/R88E) to characterize DNA accessibility under destabilizing conditions. Upon H2A mutation, even in presence of H1, the DNA opening angle at the entry/exit site was increased and the DNA wrapping length around the histone core was reduced. Interestingly, a distinct opening of the less bendable DNA side was observed upon H2A mutation, indicating an enhancement of the intrinsic asymmetry of the Widom-601 nucleosomes. This study validates AFM as a technique to investigate structural parameters of nucleosomes and highlights how the DNA sequence, together with nucleosome modifications, can influence the DNA accessibility.

Incidence, impact and indicators of difficult intubations in the neonatal intensive care unit: a report from the National Emergency Airway Registry for Neonates

OBJECTIVE

To determine the incidence, indicators and clinical impact of difficult tracheal intubations in the neonatal intensive care unit (NICU).

DESIGN

Retrospective review of prospectively collected data on intubations performed in the NICU from the National Emergency Airway Registry for Neonates.

SETTING

Ten academic NICUs.

PATIENTS

Neonates intubated in the NICU at each of the sites between October 2014 and March 2017.

MAIN OUTCOME MEASURES

Difficult intubation was defined as one requiring three or more attempts by a non-resident provider. Patient (age, weight and bedside predictors of difficult intubation), practice (intubation method and medications used), provider (training level and profession) and outcome data (intubation attempts, adverse events and oxygen desaturations) were collected for each intubation.

RESULTS

Out of 2009 tracheal intubations, 276 (14%) met the definition of difficult intubation. Difficult intubations were more common in neonates <32 weeks, <1500 g. The difficult intubation group had a 4.9 odds ratio (OR) for experiencing an adverse event and a 4.2 OR for severe oxygen desaturation. Bedside screening tests of difficult intubation lacked sensitivity (receiver operator curve 0.47-0.53).

CONCLUSIONS

Difficult intubations are common in the NICU and are associated with adverse event and severe oxygen desaturation. Difficult intubations occur more commonly in small preterm infants. The occurrence of a difficult intubation in other neonates is hard to predict due to the lack of sensitivity of bedside screening tests.

Neonatal Intubation Practice and Outcomes: An International Registry Study

BACKGROUND AND OBJECTIVES

Neonatal tracheal intubation is a critical but potentially dangerous procedure. We sought to characterize intubation practice and outcomes in the NICU and delivery room (DR) settings and to identify potentially modifiable factors to improve neonatal intubation safety.

METHODS

We developed the National Emergency Airway Registry for Neonates and collected standardized data for patients, providers, practices, and outcomes of neonatal intubation. Safety outcomes included adverse tracheal intubation-associated events (TIAEs) and severe oxygen desaturation (≥20% decline in oxygen saturation). We examined the relationship between intubation characteristics and adverse events with univariable tests and multivariable logistic regression.

RESULTS

We captured 2009 NICU intubations and 598 DR intubations from 10 centers. Pediatric residents attempted 15% of NICU and 2% of DR intubations. In the NICU, the first attempt success rate was 49%, adverse TIAE rate was 18%, and severe desaturation rate was 48%. In the DR, 46% of intubations were successful on the first attempt, with 17% TIAE rate and 31% severe desaturation rate. Site-specific TIAE rates ranged from 9% to 50% (P < .001), and severe desaturation rates ranged from 29% to 69% (P = .001). Practices independently associated with reduced TIAEs in the NICU included video laryngoscope (adjusted odds ratio 0.46, 95% confidence interval 0.28-0.73) and paralytic premedication (adjusted odds ratio 0.38, 95% confidence interval 0.25-0.57).

CONCLUSIONS

We implemented a novel multisite neonatal intubation registry and identified potentially modifiable factors associated with adverse events. Our results will inform future interventional studies to improve neonatal intubation safety.

The Staphylococcus aureus Extracellular Adherence Protein Eap Is a DNA Binding Protein Capable of Blocking Neutrophil Extracellular Trap Formation

The extracellular adherence protein (Eap) of Staphylococcus aureus is a secreted protein known to exert a number of adhesive and immunomodulatory properties. Here we describe the intrinsic DNA binding activity of this multifunctional secretory factor. By using atomic force microscopy, we provide evidence that Eap can bind and aggregate DNA. While the origin of the DNA substrate (e.g., eukaryotic, bacterial, phage, and artificial DNA) seems to not be of major importance, the DNA structure (e.g., linear or circular) plays a critical role with respect to the ability of Eap to bind and condense DNA. Further functional assays corroborated the nature of Eap as a DNA binding protein, since Eap suppressed the formation of "neutrophil extracellular traps" (NETs), composed of DNA-histone scaffolds, which are thought to function as a neutrophil-mediated extracellular trapping mechanism. The DNA binding and aggregation activity of Eap may thereby protect S. aureus against a specific anti-microbial defense reaction from the host.