Facile Generation of Heterotelechelic Poly(2-Oxazoline)s Towards Accelerated Exploration of Poly(2-Oxazoline)-Based Nanomedicine.

Controlling the end-groups of biocompatible polymers is crucial for enabling polymer-based therapeutics and nanomedicine. Typically, end-group diversification is a challenging and time-consuming endeavor, especially for polymers prepared via ionic polymerization mechanisms with limited functional group tolerance. In this study, we present a facile end-group diversification approach for poly(2-oxazoline)s (POx), enabling quick and reliable production of heterotelechelic polymers to facilitate POxylation. The approach relies on the careful tuning of reaction parameters to establish differential reactivity of a pentafluorobenzyl initiator fragment and the living oxazolinium chain-end, allowing the selective introduction of N-, S-, O-nucleophiles via the termination of the polymerization, and a consecutive nucleophilic para-fluoro substitution. The value of this approach for the accelerated development of nanomedicine is demonstrated through the synthesis of well-defined lipid-polymer conjugates and POx-polypeptide block-copolymers, which are well-suited for drug and gene delivery. Furthermore, we investigated the application of a lipid-POx conjugate for the formulation and delivery of mRNA-loaded lipid nanoparticles for immunization against the SARS-COV-2 virus, underscoring the value of POx as a biocompatible polymer platform.

Validation of the Clavien-Madadi Classification for Unexpected Events in Pediatric Surgery: A Collaborative ERNICA Project.

BACKGROUND: The Clavien-Madadi classification is a novel instrument for the assessment and grading of unexpected events in pediatric surgery, based on the Clavien-Dindo classification. The system has been adjusted to better fit the pediatric population in a prospective single-center study. There is a need now to validate the Clavien-Madadi classification within an international expert network. METHODS: A pediatric surgical working group created 19 case scenarios with unexpected events in a multi-staged process. Those were circulated within the European Reference Network of Inherited and Congenital Anomalies (ERNICA) and surgeons were instructed to rate the scenarios according to the Clavien-Madadi vs. Clavien-Dindo classification. RESULTS: 59 surgeons from 12 European countries completed the questionnaire. Based on ratings of the case scenarios, the Clavien-Madadi classification showed significantly superior agreement rates of the respondents (85.9% vs 76.2%; p < 0.05) and was less frequently considered inaccurate for rating the pediatric population compared to Clavien-Dindo (2.1% vs 11.1%; p = 0.05). Fleiss' kappa analysis showed slightly higher strength of agreement using the Clavien-Madadi classification (0.74 vs 0.69). Additionally, intraclass correlation coefficient was slightly higher for the Clavien-Madadi compared to the Clavien-Dindo classification (ICCjust 0.93 vs 0.89; ICCunjust 0.93 vs 0.89). More pediatric surgeons preferred the Clavien-Madadi classification for the case scenarios (43.0% vs 11.8%; p = 0.002) and advantages of the Clavien-Madadi were confirmed by 81.4% of the surgeons. CONCLUSION: The Clavien-Madadi classification is an accurate and reliable instrument for the grading of unexpected events in pediatric surgery. We therefore recommend its application in clinical and academic pediatric surgical practice. LEVEL OF EVIDENCE: III.

A Twin Study of Altered White Matter Heritability in Youth With Autism Spectrum Disorder.

OBJECTIVE: White matter alterations are frequently reported in autism spectrum disorder (ASD), yet the etiology is currently unknown. The objective of this investigation was to examine, for the first time, the impact of genetic and environmental factors on white matter microstructure in twins with ASD compared to control twins without ASD. METHOD: Diffusion-weighted MRIs were obtained from same-sex twin pairs (6-15 years of age) in which at least 1 twin was diagnosed with ASD or neither twin exhibited a history of neurological or psychiatric disorders. Fractional anisotropy (FA) and mean diffusivity (MD) were examined across different white matter tracts in the brain, and statistical and twin modeling were completed to assess the proportion of variation associated with additive genetic (A) and common/shared (C) or unique (E) environmental factors. We also developed a novel Twin-Pair Difference Score analysis method that produces quantitative estimates of the genetic and environmental contributions to shared covariance between different brain and behavioral traits. RESULTS: Good-quality data were available from 84 twin pairs, 50 ASD pairs (32 concordant for ASD [16 monozygotic; 16 dizygotic], 16 discordant for ASD [3 monozygotic; 13 dizygotic], and 2 pairs in which 1 twin had ASD and the other exhibited some subthreshold symptoms [1 monozygotic; 1 dizygotic]) and 34 control pairs (20 monozygotic; 14 dizygotic). Average FA and MD across the brain, respectively, were primarily genetically mediated in both control twins (A = 0.80, 95% CI [0.57, 1.02]; A = 0.80 [0.55, 1.04]) and twins concordant for having ASD (A = 0.71 [0.33, 1.09]; A = 0.84 [0.32,1.36]). However, there were also significant tract-specific differences between groups. For instance, genetic effects on commissural fibers were primarily associated with differences in general cognitive abilities and perhaps some diagnostic differences for ASD because Twin-Pair Difference-Score analysis indicated that genetic factors may have contributed to ∼40% to 50% of the covariation between IQ scores and FA of the corpus callosum. Conversely, the increased impact of environmental factors on some projection and association fibers were primarily associated with differences in symptom severity in twins with ASD; for example, our analyses suggested that unique environmental factors may have contributed to ∼10% to 20% of the covariation between autism-related symptom severity and FA of the cerebellar peduncles and external capsule. CONCLUSION: White matter alterations in youth with ASD are associated with both genetic contributions and potentially increased vulnerability or responsivity to environmental influences. DIVERSITY & INCLUSION STATEMENT: We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure race, ethnic, and/or other types of diversity in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented sexual and/or gender groups in science. One or more of the authors of this paper self-identifies as living with a disability. The author list of this paper includes contributors from the location and/or community where the research was conducted and they participated in the data collection, design, analysis, and/or interpretation of the work.

Amphiphilic Poly(2-oxazoline)s with Glycine-Containing Hydrophobic Blocks Tailored for Panobinostat- and Imatinib-Loaded Micelles.

Aiming toward the development of tailored carrier materials for the cytostatics panobinostat and imatinib, an amphiphilic block copolymer composed of poly(2-ethyl-2-oxazoline) and a degradable poly(2-(3-phenylpropyl)-2-oxazoline) analogue (dPPhPrOx-b-PEtOx) was synthesized via a postpolymerization synthesis route based on reacylation of oxidized linear poly(ethylene imine). The obtained dPPhPrOx-b-PEtOx was found to readily self-assemble into well-defined micelles with a critical micelle concentration of 1 µg mL-1. The incubation of HUVEC cells with the blank micelles revealed their excellent cytocompatibility (up to 2 mg mL-1), thus confirming the polymers' suitability for potential drug delivery application. Subsequently, the encapsulation of the two cytostatics, panobinostat and imatinib, into the dPPhPrOx-b-PEtOx micelles was successfully demonstrated (Dh ≈ 80 nm, PDI ≈ 0.16), whereby the well-defined nature of the micelle was maintained upon extended incubation at 37 °C (36 h) and storage at 4 °C (1 month). Labeling of the micelles with Alexa Fluor 594 and Alexa Fluor 647, which form a Förster resonance energy transfer (FRET) pair, indicated the stability of loaded micelles upon dilution until the CMC. Finally, the cytotoxicity of the loaded micelles was investigated against three different cell lines: Medulloblastoma cell lines ONS-76 and DAOY as well as the glioblastoma cell line U87MG. While the panobinostat-loaded micelles displayed similar cytotoxicity compared to the pure drug in the cell lines, imatinib-loaded micelles were found to be more potent compared to the pristine drug, as significantly higher cytotoxicity was observed across all three cell lines.

Titanium nitride coating of pectus bar increases metal contamination after minimally-invasive repair of pectus excavatum.

INTRODUCTION: Previous studies demonstrated a release of toxic metals, e.g. nickel and chromium, from stainless steel bars used for minimally invasive repair of pectus excavatum (MIRPE). In the present study, we investigated the impact of titanium nitride coating on the metal release and exposure of MIRPE patients. MATERIAL AND METHODS: We analyzed the courses of nickel and chromium levels in blood, urine and local tissue in patients undergoing MIRPE with a titanium nitride coated pectus bar between 03/2017 and 10/2018. Sample collection was scheduled prior to MIRPE, at defined postoperative time points and at bar removal. Additionally, we evaluated irritative symptoms. Results were compared to a control group who received uncoated stainless steel bars in a previous time period (03/2015-02/2017). RESULTS: 12 patients received coated pectus bars (mean age 15.7 years). The control group included 28 patients. After implantation of a titanium nitride coated bar, significant increase in systemic nickel and chromium levels after one, two and three years was noted. In an interim analysis one year after MIRPE, we observed patients with coated bars to have significantly elevated trace metal values compared to the control group. This elevation persisted throughout the observation period. Tissue metal values were also significantly increased. Irritative symptoms occurred significantly more often in study patients compared to controls (50.0% vs. 14.3%). CONCLUSIONS: Coating of pectus bars with titanium nitride failed to reduce metal contamination after MIRPE. Instead, it resulted in a significant increase of trace metal levels after MIRPE, compared to patients with stainless steel bars, which may be explained by wear of the coating and inter-component mobilization processes.

Non-activated Esters as Reactive Handles in Direct Post-Polymerization Modification.

Non-activated esters are prominently featured functional groups in polymer science, as ester functional monomers display great structural diversity and excellent compatibility with a wide range of polymerization mechanisms. Yet, their direct use as a reactive handle in post-polymerization modification has been typically avoided due to their low reactivity, which impairs the quantitative conversion typically desired in post-polymerization modification reactions. While activated ester approaches are a well-established alternative, the modification of non-activated esters remains a synthetic and economically valuable opportunity. In this review, we discuss past and recent efforts in the utilization of non-activated ester groups as a reactive handle to facilitate transesterification and aminolysis/amidation reactions, and the potential of the developed methodologies in the context of macromolecular engineering.

Implementation and validation of a novel instrument for the grading of unexpected events in paediatric surgery: Clavien-Madadi classification.

BACKGROUND: Inconsistent definitions of complications and unexpected events have limited accurate analysis of surgical outcomes. Perioperative outcome classifications currently used for adult patients have limitations when used for children. METHODS: A multidisciplinary group of experts modified the Clavien-Dindo classification to increase its utility and accuracy in paediatric surgery cohorts. Organizational and management errors were considered in the novel Clavien-Madadi classification, which focuses on procedural invasiveness rather than anaesthetic management. Unexpected events were prospectively documented in a paediatric surgery cohort. Results of the Clavien-Dindo and Clavien-Madadi classifications were compared and correlated with procedure complexity. RESULTS: Unexpected events were prospectively documented in a cohort of 17 502 children undergoing surgery between 2017 and 2021. The results of both classifications were highly correlated (ρ = 0.95), although the novel Clavien-Madadi classification identified 449 additional events (organizational and management errors) over the Clavien-Dindo classification, increasing the total number of events by 38 per cent (1605 versus 1158 events). The results of the novel system correlated significantly with the complexity of procedures in children (ρ = 0.756). Furthermore, grading of events > grade III according to the Clavien-Madadi classification showed a higher correlation with procedure complexity (ρ = 0.658) than the Clavien-Dindo classification (ρ = 0.198). CONCLUSION: The Clavien-Madadi classification is a tool for the detection of surgical and non-medical errors in paediatric surgery populations. Further validation in paediatric surgery populations is required before widespread use.

Surgical management of large tracheoesophageal fistula in infants after button battery ingestion.

OBJECTIVES: In recent years, an increase in severe and even fatal outcomes related to oesophageal or airway button battery (BB) ingestion by infants and small children has been reported. Extensive tissue necrosis caused by lodged BB can lead to major complications, including tracheoesophageal fistula (TEF). In these instances, best treatment remains controversial. While small defects may warrant a conservative approach, surgery often remains inevitable in highly complex cases with large TEF. We present a series of small children that underwent successful surgical management by a multidisciplinary team in our institution. METHODS: This is a retrospective analysis of n = 4 patients <18 months undergoing TEF repair from 2018 to 2021. RESULTS: Surgical repair under extracorporeal membrane oxygenation (ECMO) support was feasible in n = 4 patients by reconstructing the trachea with decellularized aortic homografts that were buttressed with pedicled latissimus dorsi muscle flaps. While direct oesophageal repair was feasible in 1 patient, 3 required esophagogastrostomy and secondary repair. The procedure was completed successfully in all 4 children with no mortality and acceptable morbidity. CONCLUSIONS: Tracheo-oesophageal repair after BB ingestion remains challenging and is associated with major morbidity. Bioprosthetic materials in conjunction with the interposition of vascularized tissue flaps between trachea and oesophagus appear to be a valid approach to manage severe cases.

Poly(N-allyl acrylamide) as a Reactive Platform toward Functional Hydrogels.

The synthesis of poly(N-allyl acrylamide) (PNAllAm) as a platform for the preparation of functional hydrogels is described. The PNAllAm was synthesized via organocatalyzed amidation of poly(methyl acrylate) (PMA) with allylamine and characterized by 1H NMR spectroscopy, size exclusion chromatography (SEC), and turbidimetry, which allowed an estimation of the lower critical solution temperature of ∼26 °C in water. The PNAllAm was then used to make functional hydrogels via photoinitiated thiol-ene chemistry, where dithiothreitol (DTT) was used to cross-link the polymer chains. In addition, mercaptoethanol (ME) was added as a functional thiol to modulate the hydrogel properties. A decrease of the volume-phase transition temperature of the resulting hydrogels was observed with increasing ME content. Altogether this work introduces a straightforward way for the preparation of PNAllAm from PMA and demonstrates its value as a reactive polymer platform for the generation of functional hydrogels.

Definition, Documentation, and Classification of Complications in Pediatric Surgical Literature-A Plea for Standardization.

Severity grading systems for complications in surgical patients have been used since 1992. An increasing assessment of these instruments in pediatric surgery is also noticed, without their validation in children. To analyze the current practice, we performed a literature review with focus on the assessment and grading of complications. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies reporting on postoperative complications as a primary or secondary endpoint using a severity grading system were included. Definition for simple adverse events, classification systems used, and the time horizon of postoperative documentation were analyzed. A total of 566 articles were screened, of which 36 met the inclusion criteria. About 86.1% of the papers were retrospective and 13.9% prospective analyses. None of the studies were prospective-randomized trials. Twenty (55.6%) studies did not include a definition of adverse events, whereas the remaining 16 (44.4%) showed variations in their definitions. All studies applied the Clavien-Dindo classification, whereas five (13.9%) additionally used the Comprehensive Complication Index. One study compared alternative grading instruments with the Clavien-Dindo classification, without demonstrating the superiority of any classification in pediatric surgery. Twenty-two studies (61.1%) did not report the time horizon of perioperative complication documentation, while 8 studies (22.2%) used 30 days and 6 studies (16.7%) used 3 months of postoperative documentation. Definition and classification of postoperative complications are inconsistent in the pediatric surgical literature. Establishment of a standardized protocol is mandatory to accurately compare outcome data.

Pleural CD14+ monocytes/macrophages of healthy adolescents show a high expression of metallothionein family genes.

Nowadays laparoscopic interventions enable the collection of resident macrophage populations out of the human cavities. We employed this technique to isolate pleural monocytes/macrophages from healthy young adults who underwent a correction of pectus excavatum. High quality CD14+ monocytes/macrophages (plMo/Mφ) were used for RNA-sequencing (RNA-seq) in comparison with human monocyte-derived macrophages (MDM) natural (MDM-0) or IL-4-polarized (MDM-IL4). Transcriptome analysis revealed 7166 and 7076 differentially expressed genes (DEGs) in plMo/Mφ relative to natural MDM-0 and polarized MDM-IL4, respectively. The gene set enrichment analysis, which was used to compare RNA-seq data from plMo/Mφ with single-cell (scRNA-seq) data online from human bronchial lavage macrophages, showed that plMo/Mφs are characterized by a high expression of genes belonging to the metallothionein (MT) family, and that the expression of these genes is significantly higher in plMo/Mφ than in MDM-0 or MDM-IL4. Our results provide additional insights on high MTs-expressing macrophage subsets, which seem to be present not only in bronchial lavage of healthy adults or in pleural exudates of lung cancer patients but also in pleural fluid of healthy young adults. Macrophage subsets expressing high MTs may have specific roles in lung defense, repair, and homeostasis, and require further investigations.

Nickel contamination after minimally-invasive repair of pectus excavatum persists after bar removal.

BACKGROUND: Minimally-invasive repair of pectus excavatum (MIRPE) has been shown to be associated with high release of trace metals into patient's body. The aim of our study was to analyze the kinetics of metal contamination after MIRPE and after bar removal. METHODS: We prospectively assessed nickel and chromium changes in blood, urine, and local tissue in patients undergoing MIRPE with stainless-steel bar(s). Baseline samples were taken prior to surgery, further samples were taken at six defined time points until 30 months after bar removal. Clinical symptoms were evaluated at the time of every sample collection. RESULTS: 28 patients were included (mean age 16.4 years). At four weeks after MIRPE and persisting up to bar removal, we found significantly elevated trace metal levels in blood and urine. Tissue nickel and chromium levels were significantly elevated at the time of bar removal. After bar removal, the concentration of trace metal in urine and the concentration of chromium in plasma decreased gradually. In contrast, nickel levels in blood further increased. Five patients showed irritative symptoms after MIRPE, all symptomatic patients had elevated metal levels. CONCLUSIONS: Following MIRPE, we found a rapid systemic increase of nickel and chromium. Our data indicate that trace metal release could cause irritative symptoms. The prolonged elevated systemic nickel levels beyond bar removal necessitate further investigations of the long-term side effects of MIRPE.

Accumulation of Postoperative Unexpected Events Assessed by the Comprehensive Complication Index® as Prognostic Outcome Parameters for Kasai Procedure.

Introduction The Kasai procedure in children with biliary atresia (BA) is associated with several complications in the short-term. The Comprehensive Complication Index (CCI®) is a validated metric in adult surgery for the analysis of complications and morbidity in surgical patients. We aimed to analyze the CCI® for the first time in BA infants and to correlate its association with outcomes. Material and Methods We conducted a retrospective review of medical records of infants with type III BA undergoing the Kasai procedure between January 2011 and December 2021 at our institution. All unexpected events were ranked according to the Clavien−Dindo classification, and the CCI® per patient was subsequently calculated. Clavien−Dindo grades, individual events, CCI®, and total event numbers per patient were correlated with one- and two-year outcomes post-surgery. Results A total of 131 events were identified in 101 patients (ranging 0−11 per patient). Forty-four Grade I (33.6%), 67 Grade II (51.1%), 18 Grade III (13.7%), and two sentinel events [>Grade IV] (1.5%) were documented according to Clavien−Dindo, including one death in a cardiac-associated BA patient. None of the complications significantly correlated with a poor outcome. Sixty-three (62.4%) CCI® scores were calculated (range 0−100). The mean CCI® score during the in-patient treatment post-surgery was significantly higher in patients with a poorer outcome than patients with native liver survival at one- and two-year follow-up (22.7 ± 21.7 vs. 13.2 ± 18.1; p = 0.02). Conclusion Not the severity of complications, but the accumulation of numerous events related to Kasai procedure were associated with a poorer outcome. Therefore, the CCI® is an excellent instrument for the postoperative morbidity assessment of BA patients.

Bioresponsive Polymers for Nanomedicine-Expectations and Reality!

Bioresponsive polymers in nanomedicine have been widely perceived to selectively activate the therapeutic function of nanomedicine at diseased or pathological sites, while sparing their healthy counterparts. This idea can be described as an advanced version of Paul Ehrlich's magic bullet concept. From that perspective, the inherent anomalies or malfunction of the pathological sites are generally targeted to allow the selective activation or sensory function of nanomedicine. Nonetheless, while the primary goals and expectations in developing bioresponsive polymers are to elicit exclusive selectivity of therapeutic action at diseased sites, this remains difficult to achieve in practice. Numerous research efforts have been undertaken, and are ongoing, to tackle this fine-tuning. This review provides a brief introduction to key stimuli with biological relevance commonly featured in the design of bioresponsive polymers, which serves as a platform for critical discussion, and identifies the gap between expectations and current reality.

Stable amorphous solid dispersion of flubendazole with high loading via electrospinning.

In this work, an important step is taken towards the bioavailability improvement of poorly water-soluble drugs, such as flubendazole (Flu), posing a challenge in the current development of many novel oral-administrable therapeutics. Solvent electrospinning of a solution of the drug and poly (2-ethyl-2-oxazoline) (PEtOx) is demonstrated to be a viable strategy to produce stable nanofibrous amorphous solid dispersions (ASDs) with ultrahigh drug-loadings (up to 55 wt% Flu) and long-term stability (at least one year). Importantly, at such high drug loadings, the concentration of the polymer in the electrospinning solution has to be lowered below the concentration where it can be spun in absence of the drug as the interactions between the polymer and the drug result in increased solution viscosity. A combination of experimental analysis and molecular dynamics simulations revealed that this formulation strategy provides strong, dominant and highly stable hydrogen bonds between the polymer and the drug, which is crucial to obtain the high drug-loadings and to preserve the long-term amorphous character of the ASDs upon storage. In vitro drug release studies confirm the remarkable potential of this electrospinning formulation strategy by significantly increased drug solubility values and dissolution rates (respectively tripled and quadrupled compared to the crystalline drug), even after storing the formulation for one year.

The Role of Laparoscopic Treatment of Choledochal Malformation in Europe: A Single-Center Experience and Review of the Literature.

BACKGROUND: Numerous studies from Asian countries, including large collectives, have reported excellent results after laparoscopic resection of choledochal malformation (CM). However, the role of laparoscopic CM resection is still controversial outside Asia. We aimed to analyze the outcome of laparoscopic CM resection in our institution and to compare our outcome with the data reported in the literature. METHODS: All patients who underwent laparoscopic CM resection in our pediatric surgical department from 2002 to 2019 were retrospectively analyzed for surgical details and postoperative complications, which were graded according to the Clavien-Dindo classification. A systematic literature search identified all reports on over 10 cases of laparoscopic pediatric CM resection and surgical details, follow-up, and complication rates were extracted. RESULTS: Fifty-seven patients (72% female) with a mean age of 3.6 + 4.1 years underwent laparoscopic CM resection in our department. Conversion rate was 30%. Total complication rate was 28%. The rate of major complications (Clavien-Dindo grade III or more) was 16% and included stricture of the biliodigestive or enteric anastomosis (n = 4), adhesive ileus (n = 3), portal vein thrombosis (n = 1), and recurrent cholangitis with consecutive liver transplantation (n = 1). With increasing experience, complication rates decreased. The majority of publications on laparoscopic CM resections originated from Asia (n = 36) and reported on low complication rates. In contrast, publications originating from non-Asian countries (n = 5) reported on higher complications following laparoscopic CM resection. CONCLUSION: Our data indicate that laparoscopic CM resection can be safely performed. The learning curve in combination with the low incidence calls for a centralization of patients who undergo laparoscopic CM resection. There seems to be a discrepancy on complications rates reported from Asian and non-Asian countries following laparoscopic CM resection.

Accelerated Post-Polymerization Amidation of Polymers with Side-Chain Ester Groups by Intramolecular Activation.

The catalytic conversion of esters to amides represents new opportunities in the synthetic diversification and upcycling of polymers, as esters are commonly featured in various polymer structures. Yet, direct amidation is typically hampered by poor reaction kinetics and the effects of polymer structure on the reactivity remain poorly understood. We report the accelerated amidation for amines with additional hydrogen bond donating or accepting groups. These amines facilitate the expeditious (co)amidation of polymers with pendant ester groups, displaying at least a 400-fold higher reactivity relative to polyesters with esters in the main chain. Furthermore, a positive correlation between the reactivity and degree of polymerization for poly(methyl acrylate) suggests a hydrogen-bond mediated intramolecular activation of the esters, which was confirmed by FT-IR spectroscopy and basic molecular mechanics modeling. The reported method paves the way to synthesize diverse (co)polymers with amide side chains from readily available polymeric precursors.

Effective mRNA Protection by Poly(l-ornithine) Synergizes with Endosomal Escape Functionality of a Charge-Conversion Polymer toward Maximizing mRNA Introduction Efficiency.

For efficient delivery of messenger (m)RNA, delivery carriers need two major functions: protecting mRNA from nucleases and translocating mRNA from endolysosomes to the cytoplasm. Herein, these two complementary functionalities are integrated into a single polyplex by fine-tuning the catiomer chemical structure and incorporating the endosomal escape modality. The effect of the methylene spacer length on the catiomer side chain is evaluated by comparing poly(l-lysine) (PLL) with a tetramethylene spacer and poly(L-ornithine) (PLO) with a trimethylene spacer. Noteworthily, the nuclease stability of the mRNA/catiomer polyplexes is largely affected by the difference in one methylene group, with PLO/mRNA polyplex showing enhanced stability compared to PLL/mRNA polyplex. To introduce the endosomal escape function, the PLO/mRNA polyplex is wrapped with a charge-conversion polymer (CCP), which is negatively charged at extracellular pH but turns positive at endosomal acidic pH to disrupt the endosomal membrane. Compared to the parent PLO/mRNA polyplex, CCP facilitated the endosomal escape of the polyplex in cultured cells to improve the protein expression efficiency from mRNA by approximately 80-fold. Collectively, this system synergizes the protective effect of PLO against nucleases and the endosomal escape capability of CCP in mRNA delivery.

Controversies in Choledochal Malformation in Children: An International Survey among Pediatric Hepatobiliary Surgeons and Gastroenterologists.

BACKGROUND: While congenital choledochal malformation (CCM) is relatively well known within the pediatric surgical and pediatric gastroenterological communities, many controversies and questions remain. METHODS: In this paper, we will discuss the results of an international Delphi survey among members of the European Reference Network RARE-LIVER and of the faculty of the Biliary Atresia and Related Diseases (BARD) network to identify the most common practices as well as controversies regarding diagnosis, treatment and follow-up of this still enigmatic disease. RESULTS: Twenty-two individual respondents completed the survey. While there seems to be agreement on the definitions of CCM, preoperative workup, surgical approach and follow-up still vary considerably. The mainstay of treatment remains the removal of the entire extrahepatic biliary tract, clearance of debris both proximally and distally, followed by reconstruction with (according to 86% of respondents) a Roux-en-Y hepaticojejunostomy. Nonetheless, both laparoscopic and robotic-assisted resections are gaining ground with the suggestion that this might be facilitated by concentration of care and resources in specialized centers. However, long-term outcomes are still lacking. CONCLUSIONS: As even post-surgical CCM has to be considered as having premalignant potential, follow-up should be well-organized and continued into adulthood. This seems to be lacking in many centers. International cooperation for both benchmarking and research is paramount to improving care for this rare disease.