Sublithospheric diamond ages and the supercontinent cycle.

Subduction related to the ancient supercontinent cycle is poorly constrained by mantle samples. Sublithospheric diamond crystallization records the release of melts from subducting oceanic lithosphere at 300-700 km depths1,2 and is especially suited to tracking the timing and effects of deep mantle processes on supercontinents. Here we show that four isotope systems (Rb-Sr, Sm-Nd, U-Pb and Re-Os) applied to Fe-sulfide and CaSiO3 inclusions within 13 sublithospheric diamonds from Juína (Brazil) and Kankan (Guinea) give broadly overlapping crystallization ages from around 450 to 650 million years ago. The intracratonic location of the diamond deposits on Gondwana and the ages, initial isotopic ratios, and trace element content of the inclusions indicate formation from a peri-Gondwanan subduction system. Preservation of these Neoproterozoic-Palaeozoic sublithospheric diamonds beneath Gondwana until its Cretaceous breakup, coupled with majorite geobarometry3,4, suggests that they accreted to and were retained in the lithospheric keel for more than 300 Myr during supercontinent migration. We propose that this process of lithosphere growth-with diamonds attached to the supercontinent keel by the diapiric uprise of depleted buoyant material and pieces of slab crust-could have enhanced supercontinent stability.

A Delphi-method-based consensus guideline for definition of treatment-resistant depression for clinical trials.

Criteria for treatment-resistant depression (TRD) and partially responsive depression (PRD) as subtypes of major depressive disorder (MDD) are not unequivocally defined. In the present document we used a Delphi-method-based consensus approach to define TRD and PRD and to serve as operational criteria for future clinical studies, especially if conducted for regulatory purposes. We reviewed the literature and brought together a group of international experts (including clinicians, academics, researchers, employees of pharmaceutical companies, regulatory bodies representatives, and one person with lived experience) to evaluate the state-of-the-art and main controversies regarding the current classification. We then provided recommendations on how to design clinical trials, and on how to guide research in unmet needs and knowledge gaps. This report will feed into one of the main objectives of the EUropean Patient-cEntric clinicAl tRial pLatforms, Innovative Medicines Initiative (EU-PEARL, IMI) MDD project, to design a protocol for platform trials of new medications for TRD/PRD.

Structure and Functional Characterization of a Humanized Anti-CCL20 Antibody following Exposure to Serum Reveals the Formation of Immune Complex That Leads to Toxicity.

mAbs have revolutionized the treatment of autoimmune disorders. Even though mAbs have shown impressive efficacy in blocking T cell or B cell activation and/or recruitment to sites of inflammation, this group of biologicals are not devoid of adverse effects. The most serious adverse effects include infusion reactions, including the activation of the complement pathway. In this study, we present a detailed structure-function study of an anti-CCL20 humanized IgG1 mAb that neutralizes CCL20 chemokine and prevents the recruitment of Th17 cells to sites of inflammation. We demonstrate that the anti-CCL20 Ab changes significantly following administration to humans and monkeys and exposure to human serum. Analysis of the drug product revealed that the anti-CCL20 Ab has unexpectedly high C1q binding. This high binding was linked to immune complex formation in vivo but not during in vitro serum incubation. The immune complex contained multiple complement components. Anti-CCL20 Ab-mediated, complement-dependent cytotoxicity occurred when the Ab bound to CCL20 tethered to the cell membrane of target cells. Taken together, these results provide a likely cause for the animal toxicity observed. In addition, anti-CCL20 revealed progressive acidification because of N100 (located in CDR) deamidation over time, which did not directly impact Ag binding. Our study demonstrates that the safety profiling of mAbs should include the evaluation of effector functions in addition to typical stressed conditions.

Perspectives on informative Bayesian methods in pediatrics.

Bayesian methods have been proposed as a natural fit for pediatric extrapolation, as they allow the incorporation of relevant external data to reduce the required sample size and hence trial burden for the pediatric patient population. In this paper we will discuss our experience and perspectives with these methods in pediatric trials. We will present some of the background and thinking underlying pediatric extrapolation and discuss the use of Bayesian methods within this context. We will present two recent case examples illustrating the value of a Bayesian approach in this setting and present perspectives on some of the issues that we have encountered in these and other cases.

A longitudinal rat model for assessing postoperative recovery and bone healing following tibial osteotomy and plate fixation.

BACKGROUND: Rodent models are commonly employed to validate preclinical disease models through the evaluation of postoperative behavior and allodynia. Our study investigates the dynamic interplay between pain and functional recovery in the context of traumatic osteotomy and surgical repair. Specifically, we established a rat model of tibial osteotomy, followed by internal fixation using a 5-hole Y-plate with 4 screws, to explore the hypothesis that histological bone healing is closely associated with functional recovery. OBJECTIVE: Our primary objective was to assess the correlation between bone healing and functional outcomes in a rat model of tibial osteotomy and plate fixation. METHODS: Seventeen male Sprague-Dawley rats underwent a metaphyseal transverse osteotomy of the proximal tibia, simulating a fracture-like injury. The resultant bone defect was meticulously repaired by realigning and stabilizing the bone surfaces with the Y-plate. To comprehensively assess recovery and healing, we performed quantitative and qualitative evaluations at 2, 4, 6, and 8 weeks post-surgery. Evaluation methods included micro-CT imaging, X-ray analysis, and histological examination to monitor bone defect healing. Concurrently, we employed video recording and gait analysis to evaluate functional recovery, encompassing parameters such as temporal symmetry, hindlimb duty factor imbalance, phase dispersion, and toe spread. RESULTS: Our findings revealed complete healing of the bone defect at 8 weeks, as confirmed by micro-CT and histological assessments. Specifically, micro-CT data showed a decline in fracture volume over time, indicating progressive healing. Histological examination demonstrated the formation of new trabecular bone and the resolution of inflammation. Importantly, specific gait analysis parameters exhibited longitudinal changes consistent with bone healing. Hindlimb duty factor imbalance, hindlimb temporal symmetry, and phase dispersion correlated strongly with the healing process, emphasizing the direct link between bone healing and functional outcomes. CONCLUSIONS: The establishment of this tibia osteotomy model underscores the association between bone healing and functional outcomes, emphasizing the feasibility of monitoring postoperative recovery using endpoint measurements. Our overarching objective is to employ this model for assessing the local efficacy of drug delivery devices in ameliorating post-surgical pain and enhancing functional recovery.

ERCP in patients with prior sphincterotomy has a 50% lower rate of post-ERCP pancreatitis and fewer unplanned hospital admissions.

OBJECTIVES: ERCP is essential in managing pancreaticobiliary disease, with well-documented complications. Rates of clinically significant complications are about 10%, approximately half of which is related to post-ERCP pancreatitis (PEP). We aimed to quantify the effect of previous sphincterotomy on post-endoiscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP). MATERIALS AND METHODS: Data were collated from a contemporaneously collected database of 2876 consecutive ERCP procedures of a single operator in a tertiary referral centre. Analysis was conducted using R software, and logistic regression models. RESULTS: Of 2876 procedures (mean age 63 years, 56% female), 120 (4.2%) developed PEP and 268 (9.3%) had prolonged/unplanned hospital admission. Univariate analysis showed patients with previous sphincterotomy 28/1054 (2.7%) had decreased risk of PEP compared with those without sphincterotomy 92/1822 (5.0%) (OR 0.52, p = .0021). This difference was not evident when multivariate analysis for age, sex and indication was undertaken due to a particularly low risk of PEP in stent change patients (1.4%), which were disproportionately represented in the previous sphincterotomy group. The rate of prolonged/unplanned hospital admission was recorded for a total of 2876 patients, occurring in 184/1802 (10.1%) in the native ampulla group, versus 84/1045 (8.0%) in the previous sphincterotomy group. CONCLUSIONS: The risk of PEP is halved by prior sphincterotomy. The presence of a biliary stent conferred an even lower risk of PEP (1.4%), but those without an in situ stent at the time of ERCP had a similar risk of PEP (4.6%) of prolonged/unplanned hospitalisation to those with a native ampulla.

Slab melting as a barrier to deep carbon subduction.

Interactions between crustal and mantle reservoirs dominate the surface inventory of volatile elements over geological time, moderating atmospheric composition and maintaining a life-supporting planet. While volcanoes expel volatile components into surface reservoirs, subduction of oceanic crust is responsible for replenishment of mantle reservoirs. Many natural, 'superdeep' diamonds originating in the deep upper mantle and transition zone host mineral inclusions, indicating an affinity to subducted oceanic crust. Here we show that the majority of slab geotherms will intersect a deep depression along the melting curve of carbonated oceanic crust at depths of approximately 300 to 700 kilometres, creating a barrier to direct carbonate recycling into the deep mantle. Low-degree partial melts are alkaline carbonatites that are highly reactive with reduced ambient mantle, producing diamond. Many inclusions in superdeep diamonds are best explained by carbonate melt-peridotite reaction. A deep carbon barrier may dominate the recycling of carbon in the mantle and contribute to chemical and isotopic heterogeneity of the mantle reservoir.

Prolonged endoscopic retrograde cholangiopancreatography results in higher rates of pancreatitis and unplanned hospitalisation.

BACKGROUND AND AIM: Although complications from endoscopic retrograde cholangiopancreatography (ERCP) are well described, procedure duration has received scant attention. The relationship between ERCP duration and patient demographics, indications, results and complications were examined. METHODS: A contemporaneously recorded database of 2572 consecutive ERCPs performed between 2008 and 2018 by a single endoscopist was analysed. Those taking under 40 min were compared with those taking over 40 min. RESULTS: Of 2572 cases, 2213 took under 40 min and 359 took over 40 min. Emergency cases (relative risk 2.10), older age (66.6 vs 61.6 years p value < 0.01) and no previous sphincterotomy (relative risk 1.94) were factors which resulted in prolonged procedures. The indication of change or removal of stent for benign conditions resulted in fewer prolonged procedures (relative risk 0.37). Indications of pancreatitis, cholangitis and positive intraoperative cholangiogram were not associated with procedure length. Findings of biliary stricture(s) (relative risk 2.02) and failure to cannulate desired duct (relative risk 3.69) were associated with prolonged procedures. Choledocholithiasis (relative risk 0.62), dilated bile duct without stricture/stone (relative risk 0.46) and normal ductal anatomy (relative risk 0.50) resulted in fewer prolonged procedures. Procedures taking over 40 min had increased risks of complications resulting in unplanned or prolongation of hospitalisation (relative risk 1.41) and pancreatitis (relative risk 1.74). CONCLUSIONS: Prolonged procedures had increased rates of pancreatitis and unplanned/prolonged hospitalisation. Failed access to desired duct, advanced age, biliary strictures, no previous sphincterotomy and unplanned emergency cases were associated with prolonged procedures.

The State of Point-of-Care Teleultrasound Use for Educational Purposes: A Scoping Review.

Bedside ultrasound has been shown to change and direct patient management in the emergent setting. Demand, use, and diagnostic potential of point-of-care ultrasound (POCUS) has continually increased throughout the years. The ongoing COVID-19 pandemic and physical distancing have necessitated further POCUS innovation. With the advent of affordable portable ultrasound devices, teleultrasound teaching has become a more viable method of POCUS education, especially in resource-limited settings. Here, we provide a scoping review of the current state of teleultrasound, specifically its use for educational purposes.

How Coiled-Coil Assemblies Accommodate Multiple Aromatic Residues.

Rational protein design requires understanding the contribution of each amino acid to a targeted protein fold. For a subset of protein structures, namely, α-helical coiled coils (CCs), knowledge is sufficiently advanced to allow the rational de novo design of many structures, including entirely new protein folds. Current CC design rules center on using aliphatic hydrophobic residues predominantly to drive the folding and assembly of amphipathic α helices. The consequences of using aromatic residues-which would be useful for introducing structural probes, and binding and catalytic functionalities-into these interfaces are not understood. There are specific examples of designed CCs containing such aromatic residues, e.g., phenylalanine-rich sequences, and the use of polar aromatic residues to make buried hydrogen-bond networks. However, it is not known generally if sequences rich in tyrosine can form CCs, or what CC assemblies these would lead to. Here, we explore tyrosine-rich sequences in a general CC-forming background and resolve new CC structures. In one of these, an antiparallel tetramer, the tyrosine residues are solvent accessible and pack at the interface between the core and the surface. In another more complex structure, the residues are buried and form an extended hydrogen-bond network.

Refractive enhancements for residual refractive error after cataract surgery.

PURPOSE OF REVIEW: Advances in cataract surgery have allowed surgeons to achieve superior refractive outcomes but have also led to higher patient expectations. Despite ever-evolving technology, residual refractive errors still occur. Postcataract refractive enhancements may be required to deliver satisfactory visual outcomes. This review aims to discuss the potential causes of residual refractive errors and the various enhancement modalities to correct them. RECENT FINDINGS: A thorough preoperative workup to detect and address underlying pathologic causes of impaired vision should be performed prior to enhancement or corrective procedures. Corneal-based procedures are the safest and most accurate methods of correcting mild cases of residual refractive error. Hyperopic, high myopic, and high astigmatic errors are best managed with lens-based enhancements. Piggyback intraocular lenses (IOLs) are safer and more effective compared with IOL exchange. Toric IOL rotation and IOL exchange are ideally performed in the early postoperative period. SUMMARY: A multitude of options exist for effective correction of residual refractive errors. The choice on how to best manage these patients depends on many factors such as the cause of refractive error, type of IOL used, ocular comorbidities, and patient preference.

Use of presbyopia-correcting intraocular lenses in patients with prior corneal refractive surgery.

PURPOSE OF REVIEW: Corneal refractive surgery has achieved spectacle-free vision for millions of patients, but this aging population is now developing cataracts. Many of these patients may wish to avoid reliance on glasses after cataract surgery. Presbyopia-correcting intraocular lenses (IOLs) offer a solution, but corneal changes after refractive surgery may compound higher order aberrations and dysphotopic symptoms associated with these IOLs. This review aims to discuss potential factors that could aid in determining suitable postkeratorefractive candidates for presbyopia-correcting IOLs. RECENT FINDINGS: Studies investigating which preoperative measures influence outcomes are lacking. The few studies that have examined presbyopia-correcting IOLs in postkeratorefractive patients report that satisfactory outcomes are possible. However, recommendations for preoperative thresholds appear limited to expert opinion and studies involving virgin corneas. SUMMARY: As the number of presbyopia-correcting IOLs and postkeratorefractive patients grows, continued investigation into relevant preoperative factors and appropriate IOLs is required to make evidence-based decisions. The current literature shows that with rigorous counseling and appropriate patient selection, presbyopia-correcting IOLs can provide postkeratorefractive patients with satisfactory results and spectacle independence. In addition, the development of postoperative modifiable IOLs may prove to be the preferred option.

Vitrifying multiple embryos in different arrangements does not alter the cooling rate.

Vitrification is the most common method of cryopreservation of gametes in fertility clinics due to its improved survival rates compared to slow freezing techniques. For the Open Cryotop® vitrification device, the number of oocytes, or embryos, mounted onto a single device can vary. In this work, a mathematical model is developed for the cooling of oocytes and embryos (samples). The model is solved computationally, to investigate whether varying the number of samples mounted onto the Open Cryotop® affects the cooling rates, and consequently the survival rates, of vitrified samples. Several realistic spatial arrangements of samples are examined, determining their temperature over time. In this way we quantify the effect of spatial arrangement on the cooling rate. Our results indicate that neither the spatial arrangement nor the number of mounted samples has a large effect on cooling rates, so long as the volume of the cryoprotectant remains minimal. The time taken for cooling is found to be on the order of half a second, or less, regardless of the spatial arrangement or number of mounted samples. Hence, rapid cooling can be achieved for any number or arrangement of samples, as long as device manufacturer guidelines are adhered to.

Outpatient Virtual Visits and the "Right" Amount of Telehealth Going Forward.

Background: An exponential increase in outpatient telehealth visits occurred early in the pandemic period that has been followed by volumes that, although lower than peak numbers, are substantially greater than the pre-pandemic period. This provided an opportunity to assess provider perceptions regarding the right prevalence going forward and key obstacles to achieving it. Methods: A 10-question survey was distributed to all outpatient providers within the Dartmouth-Hitchcock Health System. Domains included practice location, specialty, professional degree, experience with telehealth, satisfaction, perception of the amount of telehealth that could be adequately delivered going forward, role of audio-only, and obstacles. Results: Three hundred thirty-six providers completed the survey representing 51 specialties. The most common response regarding the proportion of outpatient visits that could be delivered by video going forward was 21-50% (n = 104) followed by 6-20% (n = 99) and >50% (n = 71). A minority of respondents chose ≤5% (n = 17). In terms of the fraction of video visits for which phone was equally effective, a similar percentage of respondents felt that it was 1/10 (22%), 1/4 (20%), or 1/2 (26%) of visits. Fewer felt that all (7%) or 3/4 (15%) of visits were equally effective, and 10% felt that it was none. Common obstacles identified were the need for a physical exam, unique aspects of providers' patients, patient preference, and issues regarding technology and internet speed/connectivity. Conclusions: After a period of exponential growth in virtual visits due to the pandemic, outpatient providers within an academic health system felt that a substantial portion of future visits could be delivered by this modality.

Mass spectrometric identification of intermediates in the O2-driven [4Fe-4S] to [2Fe-2S] cluster conversion in FNR.

The iron-sulfur cluster containing protein Fumarate and Nitrate Reduction (FNR) is the master regulator for the switch between anaerobic and aerobic respiration in Escherichia coli and many other bacteria. The [4Fe-4S] cluster functions as the sensory module, undergoing reaction with O2 that leads to conversion to a [2Fe-2S] form with loss of high-affinity DNA binding. Here, we report studies of the FNR cluster conversion reaction using time-resolved electrospray ionization mass spectrometry. The data provide insight into the reaction, permitting the detection of cluster conversion intermediates and products, including a [3Fe-3S] cluster and persulfide-coordinated [2Fe-2S] clusters [[2Fe-2S](S) n , where n = 1 or 2]. Analysis of kinetic data revealed a branched mechanism in which cluster sulfide oxidation occurs in parallel with cluster conversion and not as a subsequent, secondary reaction to generate [2Fe-2S](S) n species. This methodology shows great potential for broad application to studies of protein cofactor-small molecule interactions.

Navigating the Structural Landscape of De Novo α-Helical Bundles.

The association of amphipathic α helices in water leads to α-helical-bundle protein structures. However, the driving force for this-the hydrophobic effect-is not specific and does not define the number or the orientation of helices in the associated state. Rather, this is achieved through deeper sequence-to-structure relationships, which are increasingly being discerned. For example, for one structurally extreme but nevertheless ubiquitous class of bundle-the α-helical coiled coils-relationships have been established that discriminate between all-parallel dimers, trimers, and tetramers. Association states above this are known, as are antiparallel and mixed arrangements of the helices. However, these alternative states are less well understood. Here, we describe a synthetic-peptide system that switches between parallel hexamers and various up-down-up-down tetramers in response to single-amino-acid changes and solution conditions. The main accessible states of each peptide variant are characterized fully in solution and, in most cases, to high resolution with X-ray crystal structures. Analysis and inspection of these structures helps rationalize the different states formed. This navigation of the structural landscape of α-helical coiled coils above the dimers and trimers that dominate in nature has allowed us to design rationally a well-defined and hyperstable antiparallel coiled-coil tetramer (apCC-Tet). This robust de novo protein provides another scaffold for further structural and functional designs in protein engineering and synthetic biology.

Applying graph theory to protein structures: an Atlas of coiled coils.

Motivation: To understand protein structure, folding and function fully and to design proteins de novo reliably, we must learn from natural protein structures that have been characterized experimentally. The number of protein structures available is large and growing exponentially, which makes this task challenging. Indeed, computational resources are becoming increasingly important for classifying and analyzing this resource. Here, we use tools from graph theory to define an Atlas classification scheme for automatically categorizing certain protein substructures. Results: Focusing on the α-helical coiled coils, which are ubiquitous protein-structure and protein-protein interaction motifs, we present a suite of computational resources designed for analyzing these assemblies. iSOCKET enables interactive analysis of side-chain packing within proteins to identify coiled coils automatically and with considerable user control. Applying a graph theory-based Atlas classification scheme to structures identified by iSOCKET gives the Atlas of Coiled Coils, a fully automated, updated overview of extant coiled coils. The utility of this approach is illustrated with the first formal classification of an emerging subclass of coiled coils called α-helical barrels. Furthermore, in the Atlas, the known coiled-coil universe is presented alongside a partial enumeration of the 'dark matter' of coiled-coil structures; i.e. those coiled-coil architectures that are theoretically possible but have not been observed to date, and thus present defined targets for protein design. Availability and implementation: iSOCKET is available as part of the open-source GitHub repository associated with this work (https://github.com/woolfson-group/isocket). This repository also contains all the data generated when classifying the protein graphs. The Atlas of Coiled Coils is available at: http://coiledcoils.chm.bris.ac.uk/atlas/app.

Commentary on the EMA Reflection Paper on the use of extrapolation in the development of medicines for paediatrics.

Adopted guidelines reflect a harmonised European approach to a specific scientific issue and should reflect the most recent scientific knowledge. However, whilst EU regulations are mandatory for all member states and EU directives must be followed by national laws in line with the directive, EMA guidelines do not have legal force and alternative approaches may be taken, but these obviously require more justification. This new series of the BJCP, developed in collaboration with the EMA, aims to address this issue by providing an annotated version of some relevant EMA guidelines and regulatory documents by experts. Hopefully, this will help in promoting their diffusion and in opening a forum for discussion with our readers.