Irreversible synthesis of an ultrastrong two-dimensional polymeric material.

Polymers that extend covalently in two dimensions have attracted recent attention1,2 as a means of combining the mechanical strength and in-plane energy conduction of conventional two-dimensional (2D) materials3,4 with the low densities, synthetic processability and organic composition of their one-dimensional counterparts. Efforts so far have proven successful in forms that do not allow full realization of these properties, such as polymerization at flat interfaces5,6 or fixation of monomers in immobilized lattices7-9. Another frequently employed synthetic approach is to introduce microscopic reversibility, at the cost of bond stability, to achieve 2D crystals after extensive error correction10,11. Here we demonstrate a homogenous 2D irreversible polycondensation that results in a covalently bonded 2D polymeric material that is chemically stable and highly processable. Further processing yields highly oriented, free-standing films that have a 2D elastic modulus and yield strength of 12.7 ± 3.8 gigapascals and 488 ± 57 megapascals, respectively. This synthetic route provides opportunities for 2D materials in applications ranging from composite structures to barrier coating materials.

A fluorescent nanosensor paint detects dopamine release at axonal varicosities with high spatiotemporal resolution.

The neurotransmitter dopamine (DA) controls multiple behaviors and is perturbed in several major brain diseases. DA is released from large populations of specialized structures called axon varicosities. Determining the DA release mechanisms at such varicosities is essential for a detailed understanding of DA biology and pathobiology but has been limited by the low spatial resolution of DA detection methods. We used a near-infrared fluorescent DA nanosensor paint, adsorbed nanosensors detecting release of dopamine (AndromeDA), to detect DA secretion from cultured murine dopaminergic neurons with high spatial and temporal resolution. We found that AndromeDA detects discrete DA release events and extracellular DA diffusion and observed that DA release varies across varicosities. To systematically detect DA release hotspots, we developed a machine learning­based analysis tool. AndromeDA permitted the simultaneous visualization of DA release for up to 100 dopaminergic varicosities, showing that DA release hotspots are heterogeneous and occur at only ∼17% of all varicosities, indicating that many varicosities are functionally silent. Using AndromeDA, we determined that DA release requires Munc13-type vesicle priming proteins, validating the utility of AndromeDA as a tool to study the molecular and cellular mechanism of DA secretion.

Challenges and patient outcomes in chronic subdural haematoma at the level of a regional care system A multi-centre, mixed-methods study from the East of England.

BACKGROUND: Chronic subdural haematoma (cSDH) is a common neurosurgical pathology affecting older patients with other health conditions. A significant proportion (up-to 90%) of referrals for surgery in neurosciences units (NSU) come from secondary care. However, the organisation of this care and the experience of patients repatriated to non-specialist centres are currently unclear. OBJECTIVES: This study aimed to clarify patient outcome in non-specialist centres following NSU discharge for cSDH surgery and to understand key system challenges. The study was set within a representative neurosurgical care system in the east of England. DESIGN AND METHODS: We performed a retrospective cohort analysis of patients referred for cSDH surgery. Alongside case record review, patient and staff experience were explored using surveys as well as an interactive c-design workshop. Challenges were identified from thematic analysis of survey responses and triangulated by focussed workshop discussions. RESULTS: Data on 381 patients referred for cSDH surgery from six centres was reviewed. One hundred and fifty-six (41%) patients were repatriated following surgery. Sixty-one (39%) of those repatriated suffered an inpatient complication (new infection, troponin rise or renal injury) following NSU discharge, with 58 requiring institutional discharge or new care. Surveys for staff (n = 42) and patients (n = 209) identified that resourcing, communication, and inter-hospital distance posed care challenges. This was corroborated through workshop discussions with stakeholders from two institutions. CONCLUSIONS: A significant amount of perioperative care for cSDH is delivered outside of specialist centres. Future improvement initiatives must recognise the system-wide nature of delivery and the challenges such an arrangement presents.

Homozygous truncating variant in MAN2A2 causes a novel congenital disorder of glycosylation with neurological involvement.

BACKGROUND: Enzymes of the Golgi implicated in N-glycan processing are critical for brain development, and defects in many are defined as congenital disorders of glycosylation (CDG). Involvement of the Golgi mannosidase, MAN2A2 has not been identified previously as causing glycosylation defects. METHODS: Exome sequencing of affected individuals was performed with Sanger sequencing of the MAN2A2 transcript to confirm the variant. N-glycans were analysed in patient-derived lymphoblasts to determine the functional effects of the variant. A cell-based complementation assay was designed to assess the pathogenicity of identified variants using MAN2A1/MAN2A2 double knock out HEK293 cell lines. RESULTS: We identified a multiplex consanguineous family with a homozygous truncating variant p.Val1101Ter in MAN2A2. Lymphoblasts from two affected brothers carrying the same truncating variant showed decreases in complex N-glycans and accumulation of hybrid N-glycans. On testing of this variant in the developed complementation assay, we see the complete lack of complex N-glycans. CONCLUSION: Our findings show that pathogenic variants in MAN2A2 cause a novel autosomal recessive CDG with neurological involvement and facial dysmorphism. Here, we also present the development of a cell-based complementation assay to assess the pathogenicity of MAN2A2 variants, which can also be extended to MAN2A1 variants for future diagnosis.

Exploring the lived experiences and care challenges of formal paid caregivers for people with intellectual disability and dementia.

A greater number of people with intellectual disability are living into older age and are at increased risk of developing conditions such as dementia. Caring for a person with dementia presents several challenges for formal caregivers due to the progressive nature of the disease. An interpretive phenomenological analysis was used to understand the lived experiences of a purposive sample of formal caregivers in caring for people with intellectual disability and dementia. Discussions from 14 individual interviews generated data were analysed. Four key super-ordinate themes emerged which were: (1) recognising early indicators and diagnosis, (2) post diagnostic support, (3) coping with change and (4) need for future development. Themes reflected the experiences, barriers to dementia diagnosis and provide a valuable insight into the challenges faced by formal caregivers in providing aged care services.

Differential effects of teprotumumab treatment based on fat-to-muscle ratio in patients with thyroid eye disease.

PURPOSE: To characterize the distribution of fat-to-muscle ratio (FMR) across patients with thyroid eye disease (TED) and to assess the association between FMR and therapeutic response to teprotumumab. METHODS: A retrospective cohort study of patients completing a full course of teprotumumab for TED between January 2020 and March 2022 at a single tertiary referral center. Patients without baseline orbital imaging were excluded. Quantitative analysis of FMR was performed by manual segmentation of patients' imaging using OsiriX software. The primary outcome measure was change in clinical measurement of proptosis. Linear regression modelled change in proptosis against FMR. Statistical significance was set at p < .05. RESULTS: Twenty-two patients (3 M:19F) were included with a mean age of 49.4 ± 15.5 years. The FMR ranged from 1.11 to 6.54, mean 3.15 ± 1.30. The data did not deviate from a normal distribution (Shapiro-Wilk test for normality, p = .18). Pre- and post-treatment average proptosis measurements were 21.72 ± 3.56 mm and 18.81 ± 3.07 mm, respectively. Univariable linear regression demonstrated a 0.78 ± 0.36 mm greater reduction in proptosis for every 1 unit decrease in FMR (p = .038). CONCLUSIONS: Contrary to the traditional dichotomous characterization of TED into type 1 and type 2 phenotypes, orbital FMR may represent a continuum of disease manifestation, more closely following a normal rather than bimodal distribution. Furthermore, pre-treatment FMR is associated with response to teprotumumab; those with lower FMR experiencing a greater reduction in proptosis. This has implications for patient selection and counselling regarding the expected treatment outcome.

Universal Kinetic Mechanism Describing CO2 Photoreductive Yield and Selectivity for Semiconducting Nanoparticle Photocatalysts.

Photocatalytic conversion of CO2 to generate high-value and renewable chemical fuels and feedstock presents a sustainable and renewable alternative to fossil fuels and petrochemicals. Currently, there is a dearth of kinetic understanding to inform better catalyst design, especially at uniform reaction conditions across diverse catalytic species. In this work, we investigate 12 active, stable, and unique but common nanoparticle photocatalysts for CO2 reduction at room temperature and low partial pressure in aqueous phase: TiO2, SnO2, and SiC deposited with silver, gold, and platinum. Our analysis reveals a single consistent chemical kinetic mechanism, which accurately describes the yield and selectivity of all single-carbon containing (C1) products obtained in spite of the diverse catalysts employed. Formaldehyde is predicted as the first product in the reaction network and we report, to the best of our knowledge, the highest selectivity to date toward formaldehyde during CO2 photoreduction when compared against all other C1 products (∼80%) albeit at low CO2 conversion (<0.5 µmol gcat-1 h-1, <16.8 nmol m-2 h-1). Further, we observe a volcano-like relationship between the electron-transfer rate of a given photocatalyst for CO2 reduction and the net rate at which reduced products are produced in the reaction mixture taking into account unfavorable product oxidation. We establish an empirical upper limit for the maximum rate of production of CO2 reduction products for any nanoparticle photocatalyst in the absence of a hole-scavenging agent. These results form the basis for the design and optimization of the next generation of highly efficiency and active photocatalysts for CO2 reduction.

Predictors of survival following liver transplantation for pediatric hepatoblastoma and hepatocellular carcinoma: Experience from the Society of Pediatric Liver Transplantation (SPLIT).

Management of unresectable pediatric hepatoblastoma (HB) and hepatocellular carcinoma (HCC) remains challenging. The Society of Pediatric Liver Transplantation (SPLIT) database was used to study survival predictors in pediatric liver transplantation (LT) for HB and HCC. Event-free survival (EFS), associated risk factors, and postoperative complications were studied in children requiring LT for HB/HCC at 16 SPLIT centers. Three-year EFS was 81% for HB (n = 157) and 62% for HCC (n = 18) transplants. Of HB transplants, 6.9% were PRETEXT II and 15.3% were POST-TEXT I/II. Tumor extent did not impact survival (p = NS). Salvage (n = 13) and primary HB transplants had similar 3-year EFS (62% versus 78%, p = NS). Among HCC transplants, 3-year EFS was poorer in older patients (38% in ≥8-year-olds vs 86% <8-year-olds) and those with larger tumors (48% for those beyond versus 83% within Milan criteria, p = NS). Risk of infection (HR 1.5, 95% CI 1.1-2.2, p = .02) and renal injury (HR 2.4, 95% CI 1.7-3.3, p < .001) were higher in malignant versus nonmalignant LT. Survival is favorable for pediatric HB and HCC LT, including outcomes after salvage transplant. Unexpected numbers of LTs occurred in PRE/POST-TEXT I/II tumors. Judicious patient selection is critical to distinguish tumors that are potentially resectable; simultaneously, we must advocate for patients with unresectable malignancies to receive organs.

Organ-Specific Comorbidities Are Associated With Distinct Complications After Liver Transplantation for Biliary Atresia.

Although transplant outcomes for biliary atresia (BA) have improved, there are few data to predict the risk of specific posttransplant complications. We therefore defined the impact of comorbidities in BA on posttransplant outcomes. Patients enrolled in the Society of Pediatric Liver Transplantation registry from 2011 to 2019 (n = 1034) were grouped by comorbidities of >1.0% incidence: any supplemental feeding, dialysis, other abdominal surgery (not Kasai portoenterostomy [KPE]), hepatopulmonary syndrome, and cardiac disease requiring intervention. Demographic and outcome data were compared using the Kruskal-Wallis, chi-square, and log-rank tests. Cox proportional hazards models and binary logistic regression were performed for modeling. Patients with BA with comorbidities comprised 77% (n = 799) of our cohort and had evidence of greater medical acuity, including higher calculated Pediatric End-Stage Liver Disease scores and hospitalizations in the intensive care unit before transplant (P < 0.001 for both) versus those without comorbidities. After transplant, patients with BA with comorbidities had more graft loss (P = 0.02), longer initial hospitalization and intubation (P < 0.001 for both), and increased rates of reoperation (P = 0.001) and culture-proven infection (P < 0.001) within 30 days after transplant. Only patients with BA with comorbidities on supplemental feed had increased rates of patient death (P = 0.02). Multivariate analysis identified lower z weight and higher creatinine as risk factors for graft and patient loss in patients with BA with comorbidities. Prior KPE was protective against culture-proven infection and vascular complications within 30 and 90 days, respectively. Patients with BA with comorbidities have evidence of higher medical acuity at transplant and reduced graft survival; however, they overall did not experience greater incidence of patient death. Our data provide organ-system-specific data to risk-stratify patients with BA and posttransplant outcomes.

Evaluation of Frailty Assessment Compliance in Acute Care Surgery: Changing Trends, Lessons Learned.

BACKGROUND: Routine frailty assessment has emerged recently in the surgical literature and is an important prognostication and risk stratification tool. The aim of our study was to review our 7-y experience with two frailty assessment tools and changing trends in their use. METHODS: We performed a 7-y (2011-2017) analysis of our prospectively maintained frailty database. Frail patients were identified using the emergency general surgery and trauma specific frailty indices. Outcome measures were rates of compliance with frailty assessment, overall complications, discharge to skilled nursing facility (SNF)/rehab, and mortality over the study period. Multivariate logistic regression and Cochran-Armitage trend analyses were performed. RESULTS: We evaluated a total of 1045 geriatric patients (Trauma: 587, EGS: 458). Mean age was 74.5 ± 7.9 y, 74% were males, and 81% were white. Overall, 34% of the patients were frail. Compared to non-frail patients, frail patients had higher adjusted rates of complications (OR 2.4 [1.9-2.9]), mortality (OR 1.8 [1.4-2.3]), and rehab/SNF disposition (OR 3.7 [3.1-4.3]). The compliance rate of measuring frailty increased from 12% in 2011 to 78% in 2017, P < 0.001 (Figure). The complication rate decreased (33% versus 21%, P < 0.001), while the rate of discharge disposition to SNF/Rehab increased (41% versus 58%, P < 0.001). There was no difference in mortality (11% versus 9.8%, P = 0.48) over the study period. CONCLUSIONS: Adherence to frailty measurement increased over the study period. This was accompanied by a significant decline in overall in-hospital complications. Frailty indices can be utilized to identify high-risk patients and develop post-operative strategies to improve outcomes in acute care surgery.

Organisational failure: rethinking whistleblowing for tomorrow's doctors.

The duty to protect patient welfare underpins undergraduate medical ethics and patient safety teaching. The current syllabus for patient safety emphasises the significance of organisational contribution to healthcare failures. However, the ongoing over-reliance on whistleblowing disproportionately emphasises individual contributions, alongside promoting a culture of blame and defensiveness among practitioners. Diane Vaughan's 'Normalisation of Deviance' (NoD) provides a counterpoise to such individualism, describing how signals of potential danger are collectively misinterpreted and incorporated into the accepted margins of safe operation. NoD is an insidious process that often goes unnoticed, thus minimising the efficacy of whistleblowing as a defence against inevitable disaster. In this paper, we illustrate what can be learnt by greater attention to the collective, organisational contributions to healthcare failings by applying NoD to The Morecambe Bay Investigation. By focusing on a cluster of five 'serious untoward incidents' occurring in 2008, we describe a cycle of NoD affecting trust handling of events that allowed poor standards of care to persist for several years, before concluding with a poignant example of the limitations of whistleblowing, whereby the raising of concerns by a senior consultant failed to generate a response at trust board level. We suggest that greater space in medical education is needed to develop a thorough understanding of the cultural and organisational processes that underpin healthcare failures, and that medical education would benefit from integrating the teaching of medical ethics and patient safety to resolve the tension between systems approaches to safety and the individualism of whistleblowing.

A theory of mechanical stress-induced H2O2 signaling waveforms in Planta.

Recent progress in nanotechnology-enabled sensors that can be placed inside of living plants has shown that it is possible to relay and record real-time chemical signaling stimulated by various abiotic and biotic stresses. The mathematical form of the resulting local reactive oxygen species (ROS) wave released upon mechanical perturbation of plant leaves appears to be conserved across a large number of species, and produces a distinct waveform from other stresses including light, heat and pathogen-associated molecular pattern (PAMP)-induced stresses. Herein, we develop a quantitative theory of the local ROS signaling waveform resulting from mechanical stress in planta. We show that nonlinear, autocatalytic production and Fickian diffusion of H2O2 followed by first order decay well describes the spatial and temporal properties of the waveform. The reaction-diffusion system is analyzed in terms of a new approximate solution that we introduce for such problems based on a single term logistic function ansatz. The theory is able to describe experimental ROS waveforms and degradation dynamics such that species-dependent dimensionless wave velocities are revealed, corresponding to subtle changes in higher moments of the waveform through an apparently conserved signaling mechanism overall. This theory has utility in potentially decoding other stress signaling waveforms for light, heat and PAMP-induced stresses that are similarly under investigation. The approximate solution may also find use in applied agricultural sensing, facilitating the connection between measured waveform and plant physiology.

Decision-making experiences of health professionals in withdrawing treatment for children and young people: A qualitative study.

OBJECTIVE: To explore factors that influence professionals in deciding whether to withdraw treatment from a child and how decision making is managed amongst professionals as an individual and as a team. STUDY DESIGN: Semi-structured interviews were conducted with a purposive sample of health professionals working at a UK Children's Hospital, with children with life-limiting illnesses whose treatment has been withdrawn. Data were transcribed verbatim, anonymized and analysed using a thematic framework method. RESULTS: A total of 15 participants were interviewed. Five interrelated themes with associated subthemes were generated to help understand the experiences of health professionals in decision making on withdrawing a child's treatment: (1) understanding the child's best interests, (2) multidisciplinary approach, (3) external factors, (4) psychological well-being and (5) recommendations to support shared decision making. CONCLUSION: A shared decision-making approach should be adopted to support professionals, children and their families to make decisions collectively.

Pre-Hospital Administration of Opioids in Trauma Patients: Is Dose Associated With Outcomes?

BACKGROUND: Opioids are commonly used as an analgesic agent in the prehospital setting. Current efforts to prevent and control prescription opioid overuse are focused on the in-hospital and post-discharge phases. The aim of our study was to assess the associations between pre-hospital opioids use and in-hospital outcomes among trauma patients. METHODS: We performed a 2 year (2016-2017) retrospective analysis of our Level-I trauma center database. We included all adult trauma patients (age > 18y) who received pre-hospital opioids (Fentanyl (F) or Morphine-Sulfate (MS)). Outcome measures were emergency-department (ED) hypotension (SPB < 90 mmHg), ED intubation, prescription opioid medication upon discharge, and mortality. Multivariate logistic regression was performed. RESULTS: In total, 709 patients were included in the analysis. Cutoff values of 200 mcg F and 15 mg MS were significantly associated with adverse outcomes. Overall, the ED hypotension rate was 14.4%, ED intubation rate was 6%, and ED mortality rate was 3.1%. On regression analysis, higher dosages of both pre-hospital F and pre-hospital MS were independently associated with increased odds of ED hypotension, ED intubation, and discharge on opioid medications, but not with ED mortality. CONCLUSION: Pre-hospital administration of high dose opioids is associated with increased odds of adverse outcomes. Collaborative efforts to standardize and control the overuse of opioids should target the pre-hospital setting to limit opioid associated adverse effects.

Peginterferon Alfa-2a (40KD) Plus Lamivudine or Entecavir in Children With Immune-Tolerant Chronic Hepatitis B.

OBJECTIVE: Treatment guidelines for chronic hepatitis B (CHB) do not recommend antiviral therapy for patients in the immune-tolerant phase of the disease, which generally occurs in children who acquire hepatitis B virus (HBV) vertically and may last for decades. On the basis of promising results of a pilot study, we conducted a randomized, controlled, multicenter study to evaluate the efficacy and safety of antiviral therapy in children and adolescents with immune-tolerant CHB. METHODS: Fifty-nine children aged 3 to <18 years hepatitis B e antigen-positive with an HBV DNA titer >20,000 IU/mL and persistently normal alanine aminotransferase levels were randomized to 56 weeks of antiviral therapy with an oral nucleoside analogue [entecavir or lamivudine], combined with subcutaneous peginterferon alfa-2a from week 8, or 80 weeks of untreated observation. The primary efficacy outcome was hepatitis B surface antigen loss 24 weeks post-treatment in the antiviral therapy group or at the end of observation in the control group. RESULTS: Enrollment was terminated after the results of two similar studies showed that similar antiviral regimens were ineffective in children and adults with immune-tolerant CHB. At 24 weeks post-treatment, 1 of 26 patients in the antiviral treatment group experienced HBsAg loss (vs none of 33 patients in the control group). No serious treatment-related adverse events were reported, and no patients discontinued treatment because of adverse events. CONCLUSIONS: The antiviral regimen evaluated in this trial had an acceptable tolerability profile, but was ineffective in children and adolescents with immune-tolerant CHB.

Quantifying Emergency Physician Interruptions due to Electrocardiogram Review.

BACKGROUND: Interruptions are recognized as potentially harmful to safety and efficiency, and are especially prevalent in the emergency department (ED) setting. Policies urging immediate review of all electrocardiograms (ECGs) may lead to numerous and frequent interruptions. OBJECTIVE: We assessed the role of ECG review as a source of ED interruptions to characterize a potential target for interventions. METHODS: We analyzed emergency physician time use during the course of a clinical shift using a time-and-motion design. A research assistant observed a convenience sample of shifts, observing and logging transitions between different tasks using an electronic device. Instances of ECG review were tallied, with start and ending times of ECG review recorded to the nearest second. An ECG review was considered an interruption if the immediate prior and subsequent tasks were the same. RESULTS: Twenty shifts were observed for a total of 149 h. There were 211 ECG reviews, (mean rate 1.4 per hour), with more frequent review among physicians staffing a zone with higher-acuity patients (2.8 per hour), where clustering of multiple ECG reviews in succession was more common. Seventy-five percent of ECG reviews required < 30 s. Of all 211 ECG reviews, 102 (48%) were an interruption. The tasks most frequently interrupted were electronic medical record system use (68 of 102, 67%) and communicating with ED staff in person (18 of 102, 18%). CONCLUSIONS: Review of ECGs was a substantial driver of interruptions for emergency physicians. Interventions to integrate ECG review more naturally into physician workflow may improve patient safety by reducing these interruptions.

Expression of Concern to: Diet restriction inhibits apoptosis and HMGB1 oxidation and promotes inflammatory cell recruitment during acetaminophen hepatoxicity.

The Editors-in-Chief would like to alert readers that this article [1] is part of an investigation being conducted by the journal following the conclusions of an institutional enquiry at the University of Liverpool with respect to the quantitative mass spectrometry-generated results regarding acetylated and redox-modified HMGB1.

Improved Outcomes for Liver Transplantation in Patients with Biliary Atresia Since Pediatric End-Stage Liver Disease Implementation: Analysis of the Society of Pediatric Liver Transplantation Registry.

OBJECTIVE: To identify changes in demographics, outcomes, and risk factors for patient and graft loss in patients with biliary atresia undergoing liver transplantation since Pediatric End-Stage Liver Disease implementation (2002). STUDY DESIGN: Demographics and outcomes were compared between patients enrolled in the Society of Pediatric Liver Transplantation registry before (n = 547) and after (n = 1477) 2002. Kruskal-and χ2 Wallis tests identified significant differences between eras. Risk factors for patient and graft loss after 2002 were determined by Cox regression model analysis of time to event data. RESULTS: Significant patient differences after 2002 support increasing disease severity including more status 1 patients and those with a derived Model for End-Stage Liver Disease/Pediatric End-Stage Liver Disease score of greater than 30 awaiting transplant. Both patient and graft survival improved after 2002 from 90% to 97% and 81% to 90%, respectively (primary transplant; P < .0001). Significant differences in complications within 30 days included reduced relisting for transplant, rejection, culture-positive infection, repeat operation, hepatic artery thrombosis, portal vein thrombosis, and death/transplant before discharge. Multivariable analysis identified deceased technical variant vs whole graft and retransplantation predictive for patient death, hazard ratios of 4.041 and 8.308, respectively. Deceased technical variant vs whole graft (hazard ratio, 1.963) and donor age 0-5 months vs 1-17 years (hazard ratio, 5.525) were risk factors for graft loss. CONCLUSIONS: The overall outcomes of patients receiving liver transplantation for patients with biliary atresia have improved since 2002 despite evidence of increased disease severity at the time of transplant. Risk factors impacting post-transplant morbidity and mortality in patients with biliary atresia are now mainly surgical including donor variables.

Complications of Cryptosporidium infection after pediatric liver transplantation: Diarrhea, rejection, and biliary disease.

BACKGROUND: Cryptosporidium enteritis can be devastating in the immunocompromised host. In pediatric liver transplant recipients, infection may be complicated by prolonged carriage of the parasite, rejection, and biliary tree damage and fibrosis. Herein, we report on six patients and their long-term outcomes following cryptosporidiosis. METHODS: We reviewed all cases of cryptosporidiosis in a pediatric liver transplant population over a 17-year period at a single center. Six patients with infection were identified, and their outcomes were analyzed. RESULTS: Infection was associated with significant diarrhea and dehydration in all cases, and led to hospitalization in one-half of patients. Four of the six patients developed biopsy-proven rejection following infection, with three of those patients developing rejection that was recalcitrant to intravenous steroid treatment. Additionally, three patients developed biliary tree abnormalities with similarity to sclerosing cholangitis. In one patient, those biliary changes led to repeated need for biliary drain placement and advancing fibrotic liver allograft changes. CONCLUSIONS: Cryptosporidiosis in pediatric liver transplant recipients may lead to significant complications, including recalcitrant episodes of rejection and detrimental biliary tree changes. We advocate for increased awareness of this cause of diarrheal disease and the allograft injuries that may accompany infection.

Distinct but overlapping binding sites of agonist and antagonist at the relaxin family peptide 3 (RXFP3) receptor.

The relaxin-3 neuropeptide activates the relaxin family peptide 3 (RXFP3) receptor to modulate stress, appetite, and cognition. RXFP3 shows promise as a target for treating neurological disorders, but realization of its clinical potential requires development of smaller RXFP3-specific drugs that can penetrate the blood-brain barrier. Designing such drugs is challenging and requires structural knowledge of agonist- and antagonist-binding modes. Here, we used structure-activity data for relaxin-3 and a peptide RXFP3 antagonist termed R3 B1-22R to guide receptor mutagenesis and develop models of their binding modes. RXFP3 residues were alanine-substituted individually and in combination and tested in cell-based binding and functional assays to refine models of agonist and antagonist binding to active- and inactive-state homology models of RXFP3, respectively. These models suggested that both agonists and antagonists interact with RXFP3 via similar residues in their B-chain central helix. The models further suggested that the B-chain Trp27 inserts into the binding pocket of RXFP3 and interacts with Trp138 and Lys271, the latter through a salt bridge with the C-terminal carboxyl group of Trp27 in relaxin-3. R3 B1-22R, which does not contain Trp27, used a non-native Arg23 residue to form cation-π and salt-bridge interactions with Trp138 and Glu141 in RXFP3, explaining a key contribution of Arg23 to affinity. Overall, relaxin-3 and R3 B1-22R appear to share similar binding residues but may differ in binding modes, leading to active and inactive RXFP3 conformational states, respectively. These mechanistic insights may assist structure-based drug design of smaller relaxin-3 mimetics to manage neurological disorders.