Recruitment of a Middling Promiscuous Enzyme Drives Adaptive Metabolic Evolution in Escherichia coli.

A key step in metabolic pathway evolution is the recruitment of promiscuous enzymes to perform new functions. Despite the recognition that promiscuity is widespread in biology, factors dictating the preferential recruitment of one promiscuous enzyme over other candidates are unknown. Escherichia coli contains four sugar kinases that are candidates for recruitment when the native glucokinase machinery is deleted-allokinase (AlsK), manno(fructo)kinase (Mak), N-acetylmannosamine kinase (NanK), and N-acetylglucosamine kinase (NagK). The catalytic efficiencies of these enzymes are 103- to 105-fold lower than native glucokinases, ranging from 2,400 M-1 s-1 for the most active candidate, NagK, to 15 M-1 s-1 for the least active candidate, AlsK. To investigate the relationship between catalytic activities of promiscuous enzymes and their recruitment, we performed adaptive evolution of a glucokinase-deficient E. coli strain to restore glycolytic metabolism. We observed preferential recruitment of NanK via a trajectory involving early mutations that facilitate glucose uptake and amplify nanK transcription, followed by nonsynonymous substitutions in NanK that enhance the enzyme's promiscuous glucokinase activity. These substitutions reduced the native activity of NanK and reduced organismal fitness during growth on an N-acetylated carbon source, indicating that enzyme recruitment comes at a cost for growth on other substrates. Notably, the two most active candidates, NagK and Mak, were not recruited, suggesting that catalytic activity alone does not dictate evolutionary outcomes. The results highlight our lack of knowledge regarding biological drivers of enzyme recruitment and emphasize the need for a systems-wide approach to identify factors facilitating or constraining this important adaptive process.

Rising rates of anterior cruciate ligament reconstruction in Australian adults: An analysis of Australian Medicare Benefits Schedule database.

PURPOSE: Anterior cruciate ligament (ACL) reconstruction is an evolving field, though there remains sparse epidemiological data on the treatment of ACL ruptures. The objective of this study is to analyse the trends in the rate of ACL reconstruction (ACLR) in adult patients over the past two decades in the Australian population. METHODS: The incidence of ACLR between 2001 and 2020 in patients 15 years and over was analysed using the Australian Medicare Benefits Schedule (MBS) database. The data reflect patients with private health coverage (45% of the Australian population). An offset term was introduced using national population data to account for population changes over the study period. RESULTS: A total of 160,353 ACLRs were performed in Australia under the MBS in the 20-year period from 2001 to 2020. An annual increase in the total volume and per capita rate of ACLRs was found (p < 0.05). The annual volume of cases increased by 82%, from 5512 in 2001 to a peak of 10,011 in 2017. This increase was seen across all age groups (p < 0.05) and both sexes (p < 0.05), with a greater proportion of reconstructions performed on males (n = 102,357, 64%) than females (n = 57,996, 36%). In 2020, the rate of adult ACLRs decreased to a level last seen in 2004, likely due to the effects of COVID-19. CONCLUSIONS: The incidence of ACLR in adult patients has increased in Australia over the 20-year study period. The trends noted provide information that can be used to guide resource allocation and health provision in the future. LEVEL OF EVIDENCE: Level IV.

Trends in Pediatric Anterior Cruciate Ligament Reconstruction in Australia: An Analysis of Australian Medicare Benefits Schedule Database From 2001 to 2020.

BACKGROUND: Anterior cruciate ligament (ACL) injuries are common and increasingly prevalent in the pediatric population. However, there remain sparse epidemiological data on the surgical treatment of these injuries. The objective of this study is to assess the trends in the rate of pediatric ACL reconstruction in Australia over the past 2 decades. METHODS: The incidence of ACL reconstruction from 2001 to 2020 in patients 5 to 14 years of age was analyzed using the Australian Medicare Benefits Schedule (MBS) database. Data were stratified by sex and year. An offset term was introduced using population data from the Australian Bureau of Statistics to account for population changes over the study period. RESULTS: A total of 3719 reconstructions for the management of pediatric ACL injuries were performed in Australia under the MBS in the 20-year period from 2001 to 2020. There was a statistically significant annual increase in the total volume and per capita volume of pediatric ACL reconstructions performed across the study period ( P <0.0001). There was a significant increase in the rate of both male and female reconstructions ( P <0.0001), with a greater proportion of reconstructions performed on males (n=2073, 56%) than females (n=1646, 44%). In 2020, the rate of pediatric ACL reconstructions decreased to a level last seen in 2015, likely due to the effects of COVID-19. CONCLUSIONS: The incidence of ACL reconstruction in skeletally immature patients has increased in Australia over the 20-year study period. This increase is in keeping with evidence suggesting poor outcomes with nonoperative or delayed operative management.

Fluorescent A2A and A3 adenosine receptor antagonists as flow cytometry probes.

Adenosine receptor (AR) ligands are being developed for metabolic, cardiovascular, neurological, and inflammatory diseases and cancer. The ease of drug discovery is contingent on the availability of pharmacological tools. Fluorescent antagonist ligands for the human A2A and A3ARs were synthesized using two validated pharmacophores, 1,3-dipropyl-8-phenylxanthine and triazolo[1,5-c]quinazolin-5-yl)amine, which were coupled to eight reporter fluorophores: AlexaFluor, JaneliaFluor (JF), cyanine, and near infrared (NIR) dyes. The conjugates were first screened using radioligand binding in HEK293 cells expressing one of the three AR subtypes. The highest affinities at A2AAR were Ki 144-316 nM for 10, 12, and 19, and at A3AR affinity of Ki 21.6 nM for 19. Specific binding of JF646 conjugate MRS7774 12 to the HEK293 cell surface A2AAR was imaged using confocal microscopy. Compound 19 MRS7535, a triazolo[1,5-c]quinazolin-5-yl)amine containing a Sulfo-Cy7 NIR dye, was suitable for A3AR characterization in whole cells by flow cytometry (Kd 11.8 nM), and its bitopic interaction mode with an A3AR homology model was predicted. Given its affinity and selectivity (11-fold vs. A2AAR, ~ 50-fold vs. A1AR and A2BAR) and a good specific-to-nonspecific binding ratio, 19 could be useful for live cell or potentially a diagnostic in vivo NIR imaging tool and/or therapy targeting the A3AR.

Self-reported reflective functioning and father-child interactions in a sample of fathers who have used intimate partner violence.

Reflective functioning (RF) has been found to be associated with mother-child interactions, but less is known about the association of fathers' self and child-focused RF and father-child relationships.  Fathers who have histories of intimate partner violence (IPV) are known to have poor RF, which may impact their father-child interactions.  The current study was designed to examine how types of RF are associated with father-child relationships.  Pretreatment assessments and recorded, coded father-child play interactions were used to examine associations among fathers' history of adverse childhood experiences (ACES), RF and coded father-child play interactions in a sample of 47 fathers with a history of IPV use in the last 6 months with their coparent.  Fathers' ACES and their child's mental states (CM) were associated with father-child dyadic play interactions.  Fathers with greater ACES and higher scores on CM had the most dyadic tension and constriction during play interactions.  Those with high ACES but low CM had scores similar to those with low ACES and low CM.  These results indicate that fathers who have used IPV and have a history of significant adversity may benefit from interventions to increase their child-focused RF and further improve their interactions with their children.

Se ha determinado que el Funcionamiento con Reflexión (RF) está asociado con las interacciones madre-niño, pero menos se conoce acerca de la asociación del propio RF de los papás y enfocado en el niño con las relaciones papá-niño. A los papás que cuentan con un historial de violencia con la pareja íntima (IPV) se les conoce por tener un débil RF, lo cual puede impactar sus interacciones papá-niño. El presente estudio se diseñó para examinar cómo los tipos de RF se asocian con las relaciones papá-niño. Las evaluaciones anteriores al tratamiento y el juego papá niño grabado y codificado se usaron para examinar las asociaciones entre el historial de los papás sobre experiencias adversas de niñez (ACES), RF y las codificadas interacciones papá-niño en un grupo muestra de 47 papás con un historial de uso de IPV en los últimos 6 meses con sus co-progenitores. Las ACES de los papás y ciertamente de los estados mentales de sus niños (CM) se asociaron con las interacciones de juego diádicas papá-niño. Los papás con mayor cantidad de ACES y más altos puntajes en CM presentaron la tensión y constricción más diádica durante las interacciones de juego. Aquellos con alto número de ACES, pero un bajo CM presentaron puntajes similares a aquellos con bajo número de ACES y un bajo CM. Estos resultados indican que los papás que han usado IPV y que tienen un historial de adversidad significativo pudieran beneficiarse de intervenciones para incrementar su RF con enfoque en el niño a fin de mejorar sus interacciones con sus niños.

Il est établi que le fonctionnement de réflexion (en anglais Reflective functioning, ici abrégé selon le français FR) est lié aux interactions mère-enfant mais on sait peu de choses sur le lien entre le FR sur soi et l'enfant des pères et les relations père-enfant. On sait que les pères ayant un passé de violence entre partenaires intimes (ici VPI) ont un FR diminué qui peut impacter leurs interactions père-enfant. Cette étude a été conçue afin d'examiner la manière dont les types de FR sont liés aux relations père-enfant. Des évaluations pré-traitement et des jeux père-enfant enregistrés et codés ont été utilisés afin d'examiner les liens entre l'histoire d'expériences négatives durant l'enfance (ACE) des pères, le FR et les interactions de jeu père-enfant codées chez un échantillon de 47 pères ayant un passé de VPI dans les six derniers mois avec leur coparent. Les ACE des pères et certainement des états mentaux de leur enfant (CM en anglais) ont été liés aux interactions de jeu dyadique père-enfant. Les pères avec plus de ACE et des scores CM plus élevés avaient le plus de tension dyadique et de constriction durant les interactions de jeu. Ceux avec des ACE élevés mais des CM bas avaient des scores similaires à ceux avec des ACE faibles et des CM faibles. Ces résultats indiquent que les pères ayant fait preuve de VPI qui ont un passé d'adversité importante peuvent bénéficier d'interventions pour accroître leur FR focalisé sur l'enfant afin d'améliorer leurs interactions avec leurs enfants.

SNAP/CLIP-Tags and Strain-Promoted Azide-Alkyne Cycloaddition (SPAAC)/Inverse Electron Demand Diels-Alder (IEDDA) for Intracellular Orthogonal/Bioorthogonal Labeling.

Labeling a protein of interest (POI) with a fluorescent reporter is a powerful strategy for studying protein structures and dynamics in their native environments. Compared to fluorescent proteins, synthetic dyes provide more choices in photophysical or photochemical attributes to microscopic characterizations. The specificity of bioorthogonal reactions in conjunction with the fidelity of subcellular destinations of genetically encoded protein tags can be employed to label POIs in live and fixed cells in a two-step process. In the present study the orthogonality of the strain-promoted azide-alkyne cycloaddition (SPAAC) and the inverse electron demand Diels-Alder (IEDDA) reaction is corroborated in concurrent labeling of two different intracellular targets. An azido group and a strained alkene are first installed at specific subcellular locations via orthogonal enzymatic reactions of the genetically incorporated SNAP- and CLIP-tags. The subsequent bioorthogonal reactions with fluorophores carrying matching reactive functionalities result in simultaneous dual labeling. The two-step "orthogonal-bioorthogonal" labeling process would increase the utilities of SNAP/CLIP-tags and, as a consequence, would expand the capability of decorating biological specimens with functionalities beyond fluorophores to potentially include spin labels, radioactive tracers, or catalysts.

Systematic review and meta-analysis of postoperative troponin as a predictor of mortality and major adverse cardiac events after vascular surgery.

BACKGROUND: The prognostic value of asymptomatic perioperative troponin rise in vascular surgery is unclear. We conducted this systematic review and meta-analysis to determine the significance of clinical and subclinical troponin elevation after vascular surgery. METHODS: We searched MEDLINE (Ovid), Embase (Ovid), and the Cochrane Library, without language restriction, from inception to May 2019 and included studies that reported associations between elevated postoperative troponin and short-term mortality, major adverse cardiac events (MACEs), or long-term mortality in a vascular surgery cohort. We synthesized study-level data on the maximally adjusted estimates using mixed effects modeling to generate summary odds ratios (ORs) for fixed-interval outcomes and summary hazard ratios for long-term mortality. Between-study heterogeneity was assessed with meta-regression. Methodologic quality and publication bias were formally assessed. RESULTS: We included 24 studies involving 11,657 participants. Postoperative troponin was found to have a strong, positive association with short-term mortality (OR, 4.95; 95% confidence interval [CI], 2.87-8.52; 7 studies; 2661 people) and MACEs (OR, 5.33; 95% CI, 1.59-17.82; 12 studies; 5047 people) independent of meeting the criteria for myocardial infarction. Subclinical postoperative troponin elevation was further demonstrated to be associated with greater long-term mortality (hazard ratio, 1.94; 95% CI, 1.56-2.42; 13 studies; 7630 people; median follow-up, 24 months). Time to troponin sampling, hypertension, and type of surgery partially accounted for between-study heterogeneity. The methodologic quality of included studies was variable, and publication bias was not detected. CONCLUSIONS: Elevated postoperative troponin is strongly prognostic of worse survival and greater likelihood of MACEs after vascular surgery, regardless of whether symptoms of myocardial ischemia are present. These data support the benefit of postoperative troponin monitoring in identifying patients at increased risk of worse outcomes and who may be candidates for personalized preventive interventions.

The Prognostic Value of Elevated Perioperative Neutrophil-Lymphocyte Ratio in Predicting Postoperative Atrial Fibrillation After Cardiac Surgery: A Systematic Review and Meta-Analysis.

BACKGROUND: The neutrophil-lymphocyte ratio (NLR) is an emerging inflammatory perioperative biomarker which has been studied to predict the incidence of postoperative atrial fibrillation (POAF) after cardiac surgery. This systematic review and meta-analysis aimed to evaluate the prognostic accuracy of elevated perioperative NLR in predicting POAF after cardiac surgery. METHODS: Multiple databases were searched from inception to May 2019 for prognostic studies on perioperative NLR and POAF following cardiac surgery. Maximally adjusted odds ratios (OR) with associated confidence intervals were obtained from each included study and pooled using random effects inverse variance modelling for preoperative NLR measurements, while standardised mean differences were pooled for postoperative NLR values. The significance of inter- and intra-study heterogeneity was explored using meta-regression. RESULTS: 1,799 unique studies satisfied selection criteria, from which 12 studies incorporating 9,262 participants were included. Elevated preoperative NLR significantly predicted POAF, with a pooled OR of 1.42 (95% CI 1.16-1.72). Multiple predefined covariates contributed to inter-study heterogeneity; however, only prevalence of hypertension (p=0.0055), history of congestive cardiac failure (p=0.0282) and average ejection fraction (p=0.0359) were significant effect modifiers. Elevated postoperative NLR was not a significant predictor of POAF (standardised mean difference 1.60 [95% CI -0.56-3.77] between POAF+ and POAF- groups). CONCLUSIONS: Elevated preoperative NLR is a promising prognostic biomarker for POAF, but residual sources of heterogeneity remain. Larger scale validation studies are required to justify the integration of preoperative NLR testing into routine clinical practice.

Mechanism of 6-Hydroxynicotinate 3-Monooxygenase, a Flavin-Dependent Decarboxylative Hydroxylase Involved in Bacterial Nicotinic Acid Degradation.

6-Hydroxynicotinate 3-monooxygenase (NicC) is a Group A FAD-dependent monooxygenase that catalyzes the decarboxylative hydroxylation of 6-hydroxynicotinic acid (6-HNA) to 2,5-dihydroxypyridine (2,5-DHP) with concomitant oxidation of NADH in nicotinic acid degradation by aerobic bacteria. Two mechanisms for the decarboxylative hydroxylation half-reaction have been proposed [Hicks, K., et al. (2016) Biochemistry 55, 3432-3446]. Results with Bordetella bronchiseptica RB50 NicC here show that a homocyclic analogue of 6-HNA, 4-hydroxybenzoic acid (4-HBA), is decarboxylated and hydroxylated by NicC with a 420-fold lower catalytic efficiency than is 6-HNA. The 13( V/ K), measured with wild-type NicC by isotope ratio mass spectrometry following the natural abundance of 13C in the CO2 product, is inverse for both 6-HNA (0.9989 ± 0.0002) and 4-HBA (0.9942 ± 0.0004) and becomes negligible (0.9999 ± 0.0004) for 5-chloro-6-HNA, an analogue that is 10-fold more catalytically efficient than 6-HNA. Covalently bound 6-HNA complexes of NicC are not observed by mass spectrometry. Comparative steady-state kinetic and Kd6HNA analyses of active site NicC variants (C202A, H211A, H302A, H47E, Y215F, and Y225F) identify Tyr215 and His47 as critical determinants both of 6-HNA binding ( KdY215F/ KdWT > 240; KdH47E/ KdWT > 350) and in coupling rates of 2,5-DHP and NAD+ product formation ([2,5-DHP]/[NAD+] = 1.00 (WT), 0.005 (Y215F), and 0.07 (H47E)]. Results of these functional analyses are in accord with an electrophilic aromatic substitution reaction mechanism in which His47-Tyr215 may serve as the general base to catalyze substrate hydroxylation and refine the structural model for substrate binding by NicC.

Propagation of an Aß Dodecamer Strain Involves a Three-Step Mechanism and a Key Intermediate.

Proteinaceous deposits composed of fibrillar amyloid-ß (Aß) are the primary neuropathological hallmarks in Alzheimer disease (AD) brains. The nucleation-dependent aggregation of Aß is a stochastic process with frequently observed heterogeneity in aggregate size, structure, and conformation that manifests in fibril polymorphism. Emerging evidence indicates that polymorphic variations in Aß fibrils contribute to phenotypic diversity and the rate of disease progression in AD. We recently demonstrated that a dodecamer strain derived from synthetic Aß42 propagates to morphologically distinct fibrils and selectively induces cerebral amyloid angiopathy phenotype in transgenic mice. This report supports the growing contention that stable oligomer strains can influence phenotypic outcomes by faithful propagation of their structures. Although we determined the mechanism of dodecamer propagation on a mesoscopic scale, the molecular details of the microscopic reactions remained unknown. Here, we have dissected and evaluated individually the kinetics of macroscopic phases in aggregation to gain insight into the process of strain propagation. The bulk rates determined experimentally in each phase were used to build an ensemble kinetic simulation model, which confirmed our observation that dodecamer seeds initially grow by monomer addition toward the formation of a key intermediate. This is followed by conversion of the intermediate to fibrils by oligomer elongation and association mechanisms. Overall, this report reveals important insights into the molecular details of oligomer strain propagation involved in AD pathology.

Dietary signals in the premolar dentition of primates.

Dietary adaptations specific to the premolar row remain largely undocumented across primates. This study examines how relative premolar size varies among broad dietary groups (i.e., folivores, frugivores, insectivores, hard-object feeders) using a phylogenetically and ecologically diverse sample of species. We quantified relative premolar size with shape ratios computed using mandibular length, body mass, palate area, and M1 area to evaluate hypotheses that link variation in relative premolar size to differences in tooth loading, energy requirements, the probability of tooth-food-tooth contact during mastication, and shifts in preferred bite point. Our results revealed the following dietary signals. First, primate folivores have large premolar rows relative to palate area in comparison to frugivores and insectivores. This contrast is consistent with the hypothesis that folivores require large postcanine teeth relative to the size of the oral cavity to increase the probability of particle fracture during mastication. Second, hard-object feeders are distinct from other groups in having P4s that are large relative to their M1s. This morphology is not associated with an increase in the size of the premolar row relative to mandibular length. This combination challenges the idea that hard-object feeders have large premolars as an adaptive response to resisting the loads incurred when processing mechanically challenging foods. We therefore interpret the large P4/M1 ratios of hard-object feeders as indicating greater functional integration across the premolar-molar boundary owing to a mesial shift in preferred bite point. Finally, in a restricted subset of anthropoids, we found that, relative to mandibular length, premolar area increases with dietary elastic modulus (E) and toughness (R), indicating that relative premolar size is evolutionarily sensitive to food mechanical properties. Thus, our results show that relative premolar size is correlated with diet, highlighting the importance of this region for understanding the evolutionary history of primate dietary adaptations.

Variation in obstetric dimensions of the human bony pelvis in relation to age-at-death and latitude.

OBJECTIVES: Previous studies associate females who died in young adulthood with narrower obstetric pelvic dimensions, presumably in association with obstetric insufficiency (though this causal relationship is unresolved). In this study, we examine whether females within groups living at higher latitudes present this pattern, as high-latitude groups have larger pelvic dimensions than groups previously examined. These patterns are compared with males. We assess whether there is evidence for younger ages-at-death in females to have been in response to natural selection against narrower true pelvis dimensions. METHODS: We measured 14 pelvic dimensions in 327 adults (188 females, 139 males), representing archaeological sites from mid-latitude and high-latitude North America. Individuals were placed into a "young" or "not young" age-at-death category. Latitude, sex, and age-at-death groups were compared using ANOVAs and scaled variance, and evidence for selection was examined with F-tests. RESULTS: Pelvic dimensions were larger in high-latitude females and males. Females but not males who died at younger ages had smaller pelvic canals than older individuals, especially in the mediolateral inlet and anteroposterior outlet dimensions. Variance in all pelvic dimensions is equal between the two female age-at-death groups. CONCLUSIONS: We found narrower obstetrical dimensions in the female pelvis among individuals who died at younger ages. However, statistically equivalent variances in the two female age-at-death groups does not support natural selection on pelvic dimensions as leading to younger ages at death. We instead argue that this difference is result of continued growth due to remodeling in the pelvis occurring in females, but not males, after early adulthood.

Multifocal but non-disseminated phaeohyphomycosis in a healthy man via a unique mechanism: Ejection from motor vehicle accident into a vegetable field in Afghanistan resulting in multiple contaminated skin wounds.

A 20-year-old male presented with multiple subcutaneous nodules on the head, neck, chest and oral cavity. FNA and biopsy showed pigmented fungal hyphae diagnostic of multifocal phaeohyphomycosis, found to be Exophiala spinifera by molecular diagnostics. The presentation initially raised concern for disseminated disease and occult immunosuppression. However, the patient appeared to be immunocompetent and otherwise healthy. Upon further inquiry, the patient was in a motor vehicle accident 4 years before presentation; he was ejected into a vegetable field resulting in multiple open wounds. Multifocal phaeohyphomycosis usually indicates disseminated systemic disease from immunosuppression and carries a grave prognosis.

Engineers' Responsibilities for Global Electronic Waste: Exploring Engineering Student Writing Through a Care Ethics Lens.

This paper provides an empirically informed perspective on the notion of responsibility using an ethical framework that has received little attention in the engineering-related literature to date: ethics of care. In this work, we ground conceptual explorations of engineering responsibility in empirical findings from engineering student's writing on the human health and environmental impacts of "backyard" electronic waste recycling/disposal. Our findings, from a purposefully diverse sample of engineering students in an introductory electrical engineering course, indicate that most of these engineers of tomorrow associated engineers with responsibility for the electronic waste (e-waste) problem in some way. However, a number of responses suggested attempts to deflect responsibility away from engineers towards, for example, the government or the companies for whom engineers work. Still other students associated both engineers and non-engineers with responsibility, demonstrating the distributed/collective nature of responsibility that will be required to achieve a solution to the global problem of excessive e-waste. Building upon one element of a framework for care ethics adopted from the wider literature, these empirical findings are used to facilitate a preliminary, conceptual exploration of care-ethical responsibility within the context of engineering and e-waste recycling/disposal. The objective of this exploration is to provide a first step toward understanding how care-ethical responsibility applies to engineering. We also hope to seed dialogue within the engineering community about its ethical responsibilities on the issue. We conclude the paper with a discussion of its implications for engineering education and engineering ethics that suggests changes for educational policy and the practice of engineering.

Tourniquets in Trauma Care: A Review of Application.

Traumatic hemorrhage has been identified as the leading cause of battlefield death in recent conflicts. Although injury patterns are not directly reproducible to the civilian world, treatment advancements can be used to provide care to patients worldwide. Long-standing dogma regarding the use of tourniquets has been disproved, and there is now recognition of the critical role that tourniquets play in trauma care. The history and evolution of tourniquets, including the identification of previous faults in application, will lead to an examination of the current devices in use along with evidence-based recommendations for use. A review of ongoing programs to reduce hemorrhage as a cause of death in civilian and law enforcement medicine promotes the application analysis. Tourniquets, as simple technology, have the potential to save many lives through appropriate use, but preconceived myths and notions have limited its use to combat medicine. An increase in utilization could have a much greater impact in areas other than combat.

Risk of early revision in total hip arthroplasty: the relative contribution of the surgeon versus the hospital.

BACKGROUND: Early revision for total hip arthroplasty is a serious adverse outcome. There are multiple contributing risk factors for early revision. Risk factors can exist at the level of the surgeon and the level of the institution. The primary research question of this study was to determine the relative contribution of surgeon-level and hospital-level variance to rates of early revision (overall and for infection) after primary total hip arthroplasty. METHODS: This is a registry-based study from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Data for the most commonly used stem (Exeter V40) were used to reduce prosthesis variation from the analysis. A mixed effects Cox Model (also known as a frailty model) with crossed random effects for surgeon and hospital was used. Outcomes were early revision (within 2 years) for all causes and for infection. This model allowed for the risk of early revision to be explained by the variability at the surgeon level or hospital level. RESULTS: There were 32 031 procedures performed by 735 surgeons across 250 hospitals between 1 January 2015 and 31 December 2019. Surgeon variability significantly contributed to overall variation in revision for any cause and revision for infection (P < 0.0001). There was no significant contribution of hospital-level variation to overall revision or for infection. CONCLUSIONS: Surgeon-level factors play a more important role than institution-level factors in early revision after primary total hip arthroplasty. If surgeons are identified as having a higher risk of revision, there is potential for surgeon-level practice change to reduce the risk of early revision.

C1-C2 sublaminar taping for displaced odontoid synchondrosis fracture in an infant: A case report and novel surgical technique.

Pediatric cervical spine injuries are rare, and the diagnosis and management can be challenging. Surgical intervention has been recommended in unstable odontoid synchondrosis injuries or those that have failed nonoperative measures. However, the literature remains sparse on the operative management of severe injuries due to the low incidence. An 18-month-old female sustained an unstable odontoid synchondrosis fracture from a motor vehicle accident. Due to ongoing instability after initial immobilization in a halo, the decision was made to proceed with surgical management. With the patient positioned prone and neural monitoring throughout, a posterior approach was utilized. Subperiosteal exposure of the C1 posterior arch was performed bilaterally. A spinal fixation band was passed under the right C1 posterior arch, around the C2 spinous process, under the left C1 posterior arch, and finally back under the C2 spinous process. The C1-C2 distraction was reduced using intraoperative imaging, and the sublaminar tape construct was secured and reinforced. The halo was then reattached. Postoperative recovery was complicated by a halo pin-site infection which was treated with oral antibiotics. The halo was removed after 3 months, following a computerized tomography that demonstrated union. X-rays at 6 months revealed anatomical alignment with the union. Surgery is recommended in pediatric odontoid synchondrosis fractures refractory to nonoperative management. Sublaminar taping of C1-C2 with a spinal fixation band has been demonstrated to be an effective surgical technique in the management of an unstable odontoid synchondrosis fracture.

Examining the role of ChatGPT in the management of distal radius fractures: insights into its accuracy and consistency.

BACKGROUND: The optimal management of distal radius fractures remains a challenge for orthopaedic surgeons. The emergence of Artificial Intelligence (AI) and Large Language Models (LLMs), especially ChatGPT, affords significant potential in improving healthcare and research. This study aims to assess the accuracy and consistency of ChatGPT's knowledge in managing distal radius fractures, with a focus on its capability to provide information for patients and assist in the decision-making processes of orthopaedic clinicians. METHODS: We presented ChatGPT with seven questions on distal radius fracture management over two sessions, resulting in 14 responses. These questions covered a range of topics, including patient inquiries and orthopaedic clinical decision-making. We requested references for each response and involved two orthopaedic registrars and two senior orthopaedic surgeons to evaluate response accuracy and consistency. RESULTS: All 14 responses contained a mix of both correct and incorrect information. Among the 47 cited references, 13% were accurate, 28% appeared to be fabricated, 57% were incorrect, and 2% were correct but deemed inappropriate. Consistency was observed in 71% of the responses. CONCLUSION: ChatGPT demonstrates significant limitations in accuracy and consistency when providing information on distal radius fractures. In its current format, it offers limited utility for patient education and clinical decision-making.

2-Substituted (N)-Methanocarba A3 Adenosine Receptor Agonists: In Silico, In Vitro, and In Vivo Characterization.

2-Arylethynyl (N)-methanocarba adenosine 5'-methylamides are selective A3 adenosine receptor (AR) agonists containing a preestablished receptor-preferred pseudoribose conformation. Here, we compare analogues having bulky 2-substitution, either containing or lacking an ethynyl spacer between adenine and a cyclic group. 2-Aryl compounds 9-11, 13, 14, 19, 22, 23, 27, 29, 31, and 34, lacking a spacer, had human (h) A3AR K i values of 2-30 nM, and others displayed lower affinity. Mouse (m) A3AR affinity varied, with 2-arylethynyl having a higher affinity than 2-aryl analogues (7, 8 > 3c, 3d > 3b). However, 2-aryl-4'-truncated derivatives had greatly reduced hA3AR affinity, even containing affinity-enhancing N 6-dopamine-derived substituents. Molecular modeling, including molecular dynamics simulation, predicted stable poses in the canonical A3AR agonist binding site, but 2-aryl (ECL2 interactions) and 2-arylethynyl (TM2 interactions) substituents have different conformations and environments. In a hA3AR miniGαi recruitment assay, 31 (MRS8062) was (slightly) more potent compared to a ß-arrestin2 recruitment assay, both in engineered HEK293T cells, and its maximal efficacy (E max) was much higher (165%) than reference agonist NECA's. Thus, in the 2-aryl series, A3AR affinity and selectivity were variable and generally reduced compared to the 2-arylethynyl series, with a greater dependence on the specific aryl group present. Selected compounds were studied in vivo in an ischemic model of peripheral artery disease (PAD). Rigidified 2-arylethynyl analogues 3a-3c were protective in this model of skeletal muscle ischemia-reperfusion injury/claudication, as previously shown only for moderately A3AR-selective ribosides or (N)-methanocarba derivatives. Thus, we have expanded the A3AR agonist SAR for (N)-methanocarba adenosines.