Changes in upstream land-use have significantly transformed downstream coastal ecosystems around the globe. Restoration of coastal ecosystems often focuses on local-scale processes, thereby overlooking landscape-scale interactions that can ultimately determine restoration outcomes. Here we use an idealized bio-morphodynamic model, based on estuaries in New Zealand, to investigate the effects of both increased sediment inputs caused by upstream deforestation following European settlement and mangrove removal on estuarine morphology. Our results show that coastal mangrove removal initiatives, guided by knowledge on local-scale bio-morphodynamic feedbacks, cannot mitigate estuarine mud-infilling and restore antecedent sandy ecosystems. Unexpectedly, removal of mangroves enhances estuary-scale sediment trapping due to altered sedimentation patterns. Only reductions in upstream sediment supply can limit estuarine muddification. Our study demonstrates that bio-morphodynamic feedbacks can have contrasting effects at local and estuary scales. Consequently, human interventions like vegetation removal can lead to counterintuitive responses in estuarine landscape behavior that impede restoration efforts, highlighting that more holistic management approaches are needed. Upstream land-use changes are transforming coastal environments around the globe. Mangrove removal aims at restoring estuarine ecosystems but counterintuitively enhances sediment trapping. More holistic management approaches are needed. Over the last few centuries, land-use changes and coastal development have markedly increased sediment supply to the coast in many parts of the world7, leading to substantial physical transformations of coastal landscapes4 and ecosystems8. Such increases in sediment load and accelerated sedimentation in coastal areas, following large-scale catchment deforestation, jeopardize pristine ecosystems and affect ecosystem services10. Paleorecords indicate that long-term fluvial sediment supply leads to the natural gradual infilling of estuaries, but human activities can accelerate this process causing more rapid coastal progradation and the expansion of coastal wetlands such as mangrove forests and salt marshes12. Wetlands, in turn, can stabilize fine sediment and are believed to accelerate the infilling of estuarine environments13. Although coastal restoration typically involves wetland re-establishment, restoration in rapidly infilling ecosystems often focuses on vegetation clearance17. For instance, the removal of rapidly expanding wetland vegetation aims to protect habitat diversity and is thought to promote the restoration of open estuary sand dominated systems which are of high socio-economic value15. The question of how to manage wetland vegetation in accreting coastal environments is highly relevant especially given the increasing level of human-induced disturbances in such systems, where it remains unclear whether local interventions can reverse impacted ecosystem states to previous more diverse and ecosystem service-rich conditions20.Coastal wetlands are crucially important but under pressure from a range of different drivers including changing sediment availability. The loss of coastal wetlands due to the shortage of riverine sediment supply (driven by human activities such as dam construction) in combination with sea-level rise has received significant attention in recent decades21. These land-use changes caused at least an order-of-magnitude increase of suspended sediment yields to the coast compared to pre-European times23. Sedimentation in estuaries therefore magnified from relatively low rates (0.1–1 mm/yr prior to European settlement) to continually increasing rates   Fig. 21,24,25,ion Fig. . Such ex30. Vegetation locally enhances hydraulic resistance, which then reduces flow velocity and increases sediment deposition33. In addition, vegetation stabilizes mud deposits and thus optimizes conditions for seedling colonization36. Given such interactions, mangrove vegetation should accelerate mud accumulation and promote mangrove growth37. Indeed, to halt and revert muddification of New Zealand estuaries, knowledge of such local-scale bio-morphodynamic feedbacks has been applied to restore coastal ecosystems and create incentives for mangrove removal within rapidly infilling systems38. However, estuaries do not only host homogenous vegetated areas, but instead consist of intricate networks of tidal channels, tidal flats and vegetated platforms30. These interconnected landforms in turn have significant effects on bio-morphodynamic development at the landscape scale, i.e. the estuary scale, causing complex flow and sedimentation patterns, impacts of which have not been explored in detail. Furthermore, rather than significantly increasing sedimentation rates, it has been suggested that mangroves are opportunistic and colonize areas that have already reached a suitable intertidal elevation through historic sedimentation40. Removing mangroves may therefore not measurably reduce sediment trapping and sedimentation, but rather lead to a redistribution of water flow and sediment with unknown effects on estuary-scale development. Due to limitations in studying various temporal and spatial scales in the field post mangrove removal, insights thus far remain inconclusive41. Results of bio-morphodynamic model predictions can fill this gap, by accounting for small-scale interactions between vegetation, hydrodynamic forces and sediment transport, and the emergent effects of these bio-morphodynamic feedbacks on estuary-scale development.In recent decades, bio-morphodynamic feedbacks have been increasingly shown to shape coastal landscape evolution as vegetation interacts with water flow and sediment transportIn this work, we investigate the effects of changing sediment supply on estuarine bio-geomorphic landscape development with a focus on whether local measures, like mangrove removal, can reduce mud infilling and potentially restore ecosystems in estuaries with a history of anthropogenically increased fine sediment input. We assess whether established knowledge of local-scale bio-morphodynamic feedbacks can be extrapolated to the estuary scale to deliver anticipated restoration outcomes. The idealized model setup used here represents a back-barrier estuary with multiple river inputs as often observed in estuarine systems globally, including the North Island of New Zealand Fig. . Model dAn increase in fluvial sediment supply led to significant differences in morphological development and mangrove distribution in the estuary. At the pre-disturbance stage (year 200–400), mangroves first colonized levees  close to the river mouths where sediment from catchments was deposited Fig. . The morTo understand the impact of management actions on the estuary, we investigated the scenario of continued high mud supply in combination with different mangrove removal strategies from year 500, including no removal Fig.  and 25%,We found that changes in catchment sediment yield had a much stronger control on key characteristics of estuarine landscapes than the removal of mangrove vegetation Figs.  and S1. A current management practice in New Zealand estuaries involved localized mangrove clearance but model simulations indicated that this intervention did not limit ongoing muddification. Mangrove removal in fact enhanced estuarine infilling and resulted in a larger portion of the estuary consisting of muddy substrate Fig. . These eThe removal of mangrove vegetation caused changes in sediment dynamics in both channelized and unchannelized areas of the estuary. Within the channels, we found that mangrove removal resulted in a larger mud thickness  against the non-dimensional catchment sediment yield Fig. . Large b43. This in turn enhances mangrove growth, forming a reinforcing bio-morphodynamic feedback loop at the local scale  than in most other tropical mangrove sites, contributing less than 1% sedimentation volume52. Such a limited root production is expected to result in a negligible accretion rate , compared to the high sedimentation rate (10–100 mm/yr)59. However, projected accelerations in sea-level rise may create additional accommodation space61, thus slowing down the estuarine infilling process. Sedimentation rates along vegetated tidal flats have been found to be non-linearly related to sea-level rise rates42, such that future estuarine infilling is likely to be a complex process that needs to be further explored62.In this study, the infilling of accommodation space is fully driven by mineral sedimentation, while organic accretion driven by root production is not included. We acknowledge that belowground root growth can be an important or even dominant process controlling surface elevation changeon Fig. S. However64. The ability of vegetation to confine flow and sediment within channels has also been found to reduce total deltaic sediment retention65. For a freshwater tidal marsh, vegetation removal experiments have shown that vegetation clearance reduced channel flow velocities while increasing flow velocities on the platform66. This causes a spatial redistribution of sediment with the potential of enhanced sedimentation in the inner marsh67 which is in agreement with our model findings.The importance of mangrove removal on sedimentation patterns and estuarine infilling as found by our models is underpinned by recent studies that reveal vegetation effects for other types of coastal systems. Specifically, for deltaic salt marshes, contrasting effects on sedimentation patterns have been revealed, whereby vegetation can enhance sedimentation but also divert flow away from dense vegetation so that sediment deposition is reduced68. Levee development is of critical importance as levees not only store sediment locally directly adjacent to channels, but also because they influence channel hydro-sedimentary processes and the delivery of sediment to the vegetated platform70. Our research reveals that vegetation effects on levee formation and associated channel flow depend on along-channel location and whether the channels are dominated by tides or river flow 19, but also through climate change driven ecotone shifts 73 and man-made introduction of particular mangrove species (e.g. Taiwan)16. Similar reports exist for salt marsh expansion in historic Europe and North America, and recent China74. Public concerns about such changes in coastal ecosystems and highly contrasting views on vegetation removal increases the demand on sustainable and well-founded management approaches. In stark contrast, in vegetation-sparse coastal systems where ongoing erosion is typically the main concern, vegetation re-establishment is carried out where Building with Nature projects were able to show promising results, raising the question whether these approaches can be upscaled75. However, bio-morphodynamic effects on larger spatial and temporal scales are still largely unknown. Our study highlights that, in complex and highly coupled human-biogeomorphic systems, any interventions related to either vegetation removal or re-establishment requires a multi-scale assessment of bio-morphodynamic feedbacks ranging from local effects to emerging effects at the coastal landscape scale, to ensure that restoration efforts and human interventions more broadly are delivering anticipated outcomes.While global mangrove loss has received much attention in recent years76 to two-dimensions to capture spatial mangrove behaviors and sediment dynamics in an estuary, specifically a back-barrier fluvial-tidal basin. The two-dimensional bio-morphodynamic model is composed of a hydro-morphodynamic model  and a dynamic vegetation model , which are connected seasonally.We extend a previously developed one-dimensional bio-morphodynamic model78. The presence of vegetation is incorporated by including additional hydraulic resistance through calculation of the bed roughness (Cr) and the additional resistance term  and will be introduced in the next section  is applied to enable long-term simulations based on a sensitivity analysis86.Following previous observations in New Zealand estuaries, the model considers both cohesive (mud) and non-cohesive (sand) sediments87, which was implemented to allow for multiple fractions of different vegetation types in one numerical grid cell88. Based on the relative relations between the height of vegetation objects (such as stems or roots) hv (m) and local water depth h (m), the bed roughness Cr (m1/2/s) is calculated as follows:1/2/s); 2) calculated as 2) and To account for the effects of vegetation on hydrodynamics, we quantify the vegetation-induced flow resistance through the Baptist predictorVegetation causes a higher hydraulic resistance which could then lead to a higher bed shear stress and larger sediment transport rates during morphological calculations. To correct this, Delft3D includes a term .The dynamic mangrove model includes colonization, growth and mortality based on our previous research94:95. 76.After initial settling, mangroves grow each ecological season which is evaluated through an increase in stem diameter , which are used to calculate hydraulic resistance in Delft3D so that the effects of mangroves on tidal flow and consequently sediment transport are accounted for96. New Zealand mangroves usually colonize barrier-enclosed or headland-enclosed estuaries with inlets restricted by rocky headlands, typically with multiple catchments that are small relative to estuary surface area21. Here we simulate an idealized back-barrier fluvial-tidal basin to represent these typical estuarine systems in the North Island, New Zealand, most of which are characterized by similar spatial scales, similar historical vegetation expansion trends and similar sedimentation accumulation processes   Fig. . The chohttps://niwa.co.nz, also see Supplementary Data 102. We apply an M2 tidal cycle with a 1.5-m range and 30-deg/hr frequency at the seaward boundary103. Both the northern- and southern-seaward boundaries are set as Neumann conditions. The river discharge is set to 18 m3/s based on the average of the data from 73 New Zealand river reaches  and Q is the flow discharge (m3/s). When applying a flow discharge Q of 18 m3/s in Eq. 100.We use the NIWA tide model to calculate the annual mean tidal range at Whangapoua, Whangamatā and Wharekawa estuaries , we apply the concept of equilibrium sediment concentration for sand such that the amount of sand imported into/exported from the system depends on the flow velocity. This setup allows model boundaries to adapt to local flow conditions such that little deposition and erosion can occur near the boundaries78. Mud supply is controlled to represent upstream land-use changes. Catchment deforestation, agriculture and mining have enhanced soil erosion. Sediment is then washed into rivers and subsequently deposited in estuarine systems24. To model estuarine infilling for different types of upstream land-use and variations in catchment characteristics, low, intermediate and high concentrations of cohesive sediment are supplied at the river boundaries in different simulation periods. Based on sensitivity tests, we use 5 mg/L as the sediment concentration before human disturbances and 15 mg/L when simulating bio-geomorphic change under enhanced sediment inputs. These sediment settings provide annual sediment yields that are within the range reported for New Zealand systems  for mangrove pneumatophores but vary the number of pneumatophores as a function of mangrove tree size following previous mangrove modeling studies92.ry Table 55. The h108. A sensitivity analysis was carried out to evaluate the impacts of root persistence on estuarine infilling processes as shown in Fig. S57, estuarine infilling and muddy area development follow similar trends as the reference in which both stems and roots were removed completely. Thus, the influence of root persistence on general trends in estuarine dynamics is limited. We also conducted scenarios in which mud supply was reduced to pre-disturbance and intermediate levels, after different disturbance durations. Overall, this allowed us to evaluate the effects of contrasting management approaches on estuarine landscape development.The models were initiated by a 200-year spinup period to create an initial morphology with a stable cross-sectional inlet depth Fig. S. In the 96. The sediment yield (SY) is estimated through use of the USGS SPARROW model based on data from the NZ River Environment Classification calibrated by Elliott et al. 109 and Hicks et al. 110 with a regression fit (r2) of 0.925. The sediment yields of Whangapoua, Wharekawa and Whangamatā estuaries are derived from NIWA sediment model111. The relative basin area above mean sea level (AMSL/Atot) is defined as the ratio between the area of intertidal habitat above mean sea level and estuary surface during high tide. The data source of these surface measurements is based on NIWA Estuarine Environment Classification Database112.The modeled estuarine infilling patterns among different scenarios were compared to previous published data from different estuarine systems in New Zealand Fig. . For theSupplementary InformationPeer Review FileDescription of Additional Supplementary FilesSupplementary Data 1Supplementary Data 2Supplementary Data 3Supplementary Data 4


Structural and functional imaging prior to surgery in drug-resistant focal epilepsy, has an important role to play alongside electroencephalography (EEG) techniques, in planning the surgical approach and predicting post-operative outcome. This paper reviews the role of structural and functional imaging of the brain, namely computed tomography (CT), magnetic resonance imaging (MRI), functional MRI (fMRI), single photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging in the preoperative work-up of people with medically refractory epilepsy. In MRI-negative patients, the precise localisation of the epileptogenic zone may be established by demonstrating hypometabolism on PET imaging or hyperperfusion on SPECT imaging in the area surrounding the seizure focus. These imaging modalities are far less invasive than intracranial EEG, which is the gold standard but requires surgical placement of electrodes or recording grids. Even when intracranial EEG is needed, PET or SPECT imaging can assist in the planning of EEG electrode placement, due to its’ limited spatial sampling. Multimodal imaging techniques now allow the multidisciplinary epilepsy surgery team to identify and better characterise focal pathology, determine its’ relationship to eloquent areas of the brain and the degree of interconnectedness within both physiological and pathological networks, as well as improve planning and surgical outcomes for patients. This paper will update the reader on this whole field and provide them with a practical guide, to aid them in the selection of appropriate investigations, interpretation of the findings and facilitating patient discussions in individuals with drug-resistant focal epilepsy. All patIn many cases, these investigations do not provide enough information to confidently proceed to surgery or may in fact show discordant results. In this subset of patients, functional imaging techniques such as positron emission tomography (PET) and/or single photon emission computerised tomography (SPECT), can help clinicians develop a clearer picture of the epileptogenic zone and eloquent areas, facilitating discussions around the role and aims of surgery and aid prognostication. Advanced techniques such as magnetoencephalography (MEG), electrical or magnetic source imaging (ESI/MSI), simultaneous EEG and fMRI, as well as automated imaging protocols for lesion detection, are being evaluated in research settings to gather additional information. Functional imaging may be used in select cases to determine where further invasive testing such as intracranial EEG may be helpful, or in some cases enable patients to proceed to direct surgical resection .Seizures are a dynamic process; brain states in an individual patient can vary dramatically during a seizure or the ‘ictal’ state, compared to the ‘interictal’ state representing the period between seizures. This means that the interpretation of imaging results must consider whether the patient is in an ictal or interictal state. Using functional imaging in the same patient in these two different states can be an invaluable tool for the clinician to better understand the physiological basis and the neural networks associated with epilepsy in an individual. The presurgical workup of PWE who are candidates for epilepsy surgery involves the identification of the symptomatogenic zone, the irritative zone, the ictal onset zone, the epileptogenic lesion, the epileptogenic zone and the eloquent cortex . These tThis paper will focus on the role of functional imaging techniques of the brain, with an initial overview of structural imaging techniques, in the preoperative workup of people with medically refractory epilepsy.In an emergency setting, when a patient has new onset seizures, a non-contrast CT of the head is appropriate to diagnose or rapidly exclude several life-threatening conditions such as an epidural haematoma or subarachnoid haemorrhage. MRI is more time consuming and, therefore, less appropriate for these pathologies in the acute setting . In refrThe presurgical workup of refractory epilepsy patients begins with structural imaging using MRI. This modality is more sensitive, more specific, has a higher spatial resolution than CT for subtle structural abnormalities, and can be used to acquire several different sequences. The optimal epilepsy surgery protocol includes axial and coronal slices of volumetric T1-weighted sequences for improved grey-white matter differentiation, detection of cortical thickness and malformations of cortical development. Fluid-attenuated inversion recovery (FLAIR) sequences are sensitive to pathologies such as hippocampal sclerosis (HS), FCD, tumours, inflammation, and scars. Quantification of hippocampal changes can also be assessed with volumetry and T2 relaxometry. T2* gradient echo or susceptibility weighted sequences are useful to detect calcified and vascular lesions, such as cavernomas and arteriovenous malformations. Voxel based morphometry (VBM) is a neuroimaging technique that involves a voxel-wise comparison of the local concentration of grey matter between two groups of subjects . AlthougAs the primary role of MRI in epilepsy is in the detection of structural abnormalities, the quality and resolution of the images generated could determine the outcomes of epilepsy surgery . A repeaNewer testing modalities in conjunction with 7T MRI include glutamate-weighted chemical exchange saturation transfer (GluCEST) for mapping hippocampal glutamate distribution in epilepsy, allowing researchers and clinicians to differentiate lesional from non-lesional mesial temporal lobe epilepsy (TLE) .Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are MRI sequences that are highly sensitive to the diffusion of water molecules . When diDTI can also better inform us about radiographic diagnoses such as mesial temporal sclerosis (MTS), the most common cause of TLE . MTS patDiffusion kurtosis imaging (DKI) is an emerging technique, extending DTI’s capabilities, enabling the characterisation of non-Gaussian water diffusion behaviour , and is Functional imaging techniques broadly investigate dynamic processes of metabolism, perfusion, or gas exchange to identify abnormal areas, as opposed to structural imaging which demonstrates anatomical static abnormalities.FMRI is mostly utilised in the presurgical evaluation of patients with drug-resistant epilepsy to localise eloquent brain areas such as language and motor cortices. This enables planning of surgery to minimise any damage to these areas, and to reduce postsurgical language or motor impairments .FMRI uses the diamagnetic and paramagnetic properties of oxygenated and deoxygenated blood respectively, to produce signals by measuring their relative ability to induce local magnetic field distortions. This so-called ‘blood oxygen level dependent’ (BOLD) response alters in conjunction with an increase in local neuronal activity and, therefore, is regarded as an indirect measure of local neuronal activity .To investigate motor function, self-triggered movements are commonly used. These include tongue, finger, and toe movements, contralateral to the side of the lesion, to localise the motor homunculus in relation to the lesion. The somatosensory functional areas can also be studied using tactile stimuli. Language functions are examined using various paradigms involving auditory or visual stimulation, such as the “verbal fluency task” for anterior  language areas, and “semantic decision-making task” for more widely distributed networks including anterior and posterior language areas . In tempMore invasive techniques for localisation of functions include direct cortical stimulation (DCS), which involves testing of motor, sensory, or higher level neurocognitive functions with stimulus presentation, coordinated with the administration of electrical stimulation to the exposed brain following craniotomy, to localise functions . DisadvaFMRI appears to be a promising alternative to invasive tests such as DCS or the Wada test, particularly in cases where the invasive localisation of the eloquent cortex has proven to be challenging but more importantly because of the much lower morbidity of the procedure itself . Wada teInterictal PET or ictal SPECT have been established as useful investigations to localise the origins of focal epilepsies. These modalities can be used to predict outcomes in selected epilepsy patients proceeding to surgical resection, particularly for those with normal MRI or discordance between MRI, clinical and EEG data.Ictal and interictal patterns of local cerebral metabolic rate have been studied in PWE using PET with 18F-labeled 2-fluoro-2-deoxy-D-glucose (18F-FDG) since the 1980s. PET  reflects the rate of glucose uptake in the brain parenchyma , while SPECT represents cerebral blood flow changes . GlucoseBoth visual PET analysis and quantitative PET (qPET) analysis predict outcome after temporal lobectomy, although quantitative measures offer more precise information . In qPETThere are several patterns of PET hypometabolism that have now been associated with distinct types of focal epilepsies, and in some cases have been shown to predict post-surgical outcomes . In TLE TLE is the most common type of focal epilepsy, and with careful investigation and preoperative planning, it is associated with the best outcomes following epilepsy surgery. TLE patients show asymmetries in FDG uptake which may be due to mild hypermetabolism or mild hypometabolism in the epileptic temporal lobe . PatientTLE with amygdala enlargement probably represents a distinct nosological and less homogeneous syndrome without ipsilateral HS. Chronic inflammatory processes in the temporal lobe or an amygdala FCD could possibly lead to amygdala enlargement. Interictal 18F-FDG PET shows regional glucose hypometabolism in the ipsilateral temporal lobe in these cases in concordance with EEG and MRI data . The undMore extensive patterns of PET hypometabolism can also be seen in TLE patients, including extra-temporal and frontal lobes , which m11C]K-2 that specifically bound in vivo to AMPA receptors, and found increased [11C]K-2 uptake in the epileptogenic focus of patients with mesial TLE, which was closely correlated with the local AMPA receptor protein distribution in surgical specimens resected from these same individuals [Whilst FDG-PET is used in clinical practice for epilepsy surgery, in research studies using PET with specific ligands, one is able to probe the neurochemistry associated with the pathophysiology of epilepsy . AMPA  are diverse, due to the broad range of underlying aetiologies. An important cause of ETLE is FCD. PET may provide a complimentary role in recognising and defining these often subtle lesions through co-registration with MRI . The incIn contrast to PET imaging which detects changes in local cerebral metabolic rates, SPECT imaging commonly uses Technetium-99-based radiotracers to detect changes in cerebral perfusion in areas surrounding the epileptogenic zone. This is based on the concept of cerebral metabolic and perfusion coupling, which is that an increase in neuronal metabolic activity in the seizure propagating regions is associated with an increase in CBF or hyperperfusion in those areas . CerebraAlthough SPECT imaging can be performed in the ictal, interictal or post-ictal period, the highest sensitivity for seizure localisation is in the ictal period . Ictal SRaw data obtained from a SPECT scanner is smoothed using a Butterworth filter. The goal of filtering is to compensate for the loss of detail in an image while reducing noise . AttenuaComputer-aided image post-processing, with subtraction of ictal SPECT co-registered to MRI (SISCOM), can significantly improve the clinical usefulness of SPECT in localising the seizure focus prior to surgical resection  Fig. 2)2). SISCOThe accuracy of SPECT in localising the seizure focus pre-operatively in patients with drug-refractory epilepsy has been found to be high when considering the final diagnosis reached by the convergence of clinical, electrophysiological, structural, pathological and outcome data, as discussed below.In a study of 75 consecutive patients with epilepsy (48 with TLE and 27 with ETLE), ictal SPECT correctly identified the epileptogenic zone in 91% of patients when the two study groups were analysed separately. The specificity and positive predictive values were greater than 90% for the whole series of patients. In up to two-thirds of these cases, ictal SPECT either obviated the need for invasive EEG, thus avoiding the associated risks, or helped to define where to concentrate the efforts of more invasive investigations .Ictal SPECT has a lower localising value in ETLE (90%) compared to TLE (97%) . This diBoth PET and SPECT imaging can be used to localise a seizure focus but PET has a better spatial resolution (2–3 mm) than SPECT. Local expertise and available technology usually determine the choice of modality used. SPECT scanning with CT is less expensive  and SPECT in 39 cases (87% sensitivity) . In anotResearchers have endeavoured to define an optimal battery of imaging modalities for presurgical localisation of the epileptogenic zone in MR-negative focal epilepsies . QuadrimQuantitative PET (qPET) has a higher sensitivity than morphometric analysis programs  of 73% versus 64% in MRI-negative epilepsy patients. However, combining MAP and qPET from a simultaneous PET/MRI scanner has higher specificity (88%) compared to either MAP (69%) or qPET (65%) alone. Any combination that can improve sensitivity and specificity would be valuable in aiming for Engel Class 1 outcomes post-resective surgery  but thisA meta-analysis of 21 studies involving almost 1,200 patients undergoing epilepsy surgery showed an overall rate of post-operative seizure freedom (Engel Class I outcome) of 45.1% . One of While PET or SPECT may enable one to proceed to direct surgical resection in some cases, it is now recognised that the generators of epilepsy in individual patients may extend beyond an identified lesion, or involve highly connected, distant regions of the brain . IntracrAutomated imaging analysis for presurgical planning and prediction of epilepsy surgical outcomes using machine learning techniques are being investigated . With inFunctional imaging for localising the seizure focus in drug refractory epilepsy, particularly in those with no structural lesion identified on MRI, plays an important role in the workup of PWE. It enables the highest chance of being rendered seizure-free by surgery and minimises risks to eloquent areas. The techniques vary from fMRI to PET and SPECT.Other emerging imaging techniques such arterial spin labelling (ASL) are capable of quantifying local cerebral blood flow by measuring the inflow of magnetically labelled arterial blood into the target region. Pulsed ASL may be a promising alternative to PET imaging for the detection of interictal hypoperfusion in TLE, due to its’ relatively easy accessibility, in places where PET imaging is not available. This would be practically very useful for patients in smaller hospitals if its’ sensitivity was similar to PET; data from larger studies is still needed though to validate this finding.Further research is required to evaluate higher-resolution MRI and identify radiotracers and ligands for PET and SPECT imaging with higher sensitivity, particularly for extra-temporal epilepsy. Using PET with specific ligands could help us understand the pathophysiology of seizures, and improve the future management of epilepsy patients. Looking to the future, artificial intelligence and machine learning approaches hold promise for improving localisation and surgical outcomes Table .Table 2K


The mitochondrion is a major hub of cellular metabolism and involved directly or indirectly in almost all biological processes of the cell. In mitochondrial diseases, compromised respiratory electron transfer and oxidative phosphorylation (OXPHOS) lead to compensatory rewiring of metabolism with resemblance to the Warburg-like metabolic state of cancer cells. The transcription factor MYC (or c-MYC) is a major regulator of metabolic rewiring in cancer, stimulating glycolysis, nucleotide biosynthesis, and glutamine utilization, which are known or predicted to be affected also in mitochondrial diseases. Albeit not widely acknowledged thus far, several cell and mouse models of mitochondrial disease show upregulation of MYC and/or its typical transcriptional signatures. Moreover, gene expression and metabolite-level changes associated with mitochondrial integrated stress response (mt-ISR) show remarkable overlap with those of MYC overexpression. In addition to being a metabolic regulator, MYC promotes cellular proliferation and modifies the cell cycle kinetics and, especially at high expression levels, promotes replication stress and genomic instability, and sensitizes cells to apoptosis. Because cell proliferation requires energy and doubling of the cellular biomass, replicating cells should be particularly sensitive to defective OXPHOS. On the other hand, OXPHOS-defective replicating cells are predicted to be especially vulnerable to high levels of MYC as it facilitates evasion of metabolic checkpoints and accelerates cell cycle progression. Indeed, a few recent studies demonstrate cell cycle defects and nuclear DNA damage in OXPHOS deficiency. Here, we give an overview of key mitochondria-dependent metabolic pathways known to be regulated by MYC, review the current literature on MYC expression in mitochondrial diseases, and speculate how its upregulation may be triggered by OXPHOS deficiency and what implications this has for the pathogenesis of these diseases. It is ain vivo . In mammife span . Its expMYC-Associated factor X) to exert their transcriptional functions. MAX can homodimerize or heterodimerize with other proteins than MYC family, and these dimers compete for a common DNA sequence element called the E box, providing a complex transcriptional regulation system. After DNA binding, the MYC-MAX dimers can recruit further transcriptional cofactors and chromatin modiflers that license RNA polymerase II activation and transcription. The MYC-driven transcriptional programs are complex and almost genome wide because MYC acts as a global transcriptional amplifier that binds and increases expression at active promoters , Myc mRNA is highly expressed in stem cells and other rapidly proliferating cell types, whereas in terminally differentiated cells, its expression is not detectable, suggesting an overall conserved role in cell proliferation (Drosophila melanogaster) MYC homolog  (1/S progression but not G2/M progression or cell division (dMyc haploinsufficiency decreases mutation load and extends lifespan (The MYC-MAX dimerization domain function is conserved from human to zebrafish  and fruiferation . The fruinutive)  has beendivision . It alsolifespan , similarlifespan , as we sMyc knockout in mice is lethal by embryonic day 10.5 due to developmental defects in the placenta, hematopoietic system, and vasculature  brings no adverse effects but about 20% decrease in adult body mass and increased lifespan in mice   . This inMyc in these compartments in mice does not result in a noticeable proliferation defect. For example, quite unexpectedly, MYC is dispensable for postnatal liver growth and regeneration  show a 50%–80% decrease in basal Myc expression but are homozygous viable and fertile, with no overt phenotype and only a slight decrease in the number of B lymphocytes. These mice fail to induce MYC overexpression during early tumorigenesis, and cultured fibroblasts from these mice grow slowly and are unable to upregulate MYC in response to serum stimulation. In a recent paper, Wang et al. revisit the question of MYC functions in postnatal development and tissue homeostasis by generating a mouse line with tamoxifen-inducible Cre-mediated loss of Myc  longer than wild-type controls, probably due to a 4-5-fold lower cancer incidence. Transcriptional profiling of the liver, white adipose tissue and skeletal muscle showed changes related to mitochondrial and ribosomal function, cellular senescence, DNA damage recognition and repair, and mRNA splicing upon loss of MYC  . Direct Myc−/− fibroblasts is about 50% of that of parental wild-type cells (Cellular metabolism can be divided into catabolic (degradative) and anabolic (biosynthetic) branches that intertwine widely. Catabolism is the collective term for breaking complex molecules into simpler ones with concomitant release of energy from chemical bonds to drive cellular functions and to produce biosynthetic precursors. Uncovering the central role of MYC as a regulator of both catabolism and anabolism started with studies on cancer cells in the mid-1980s. To begin with, MYC plays a crucial role in the regulation of glycolysis by upregulating glucose transporters and nearly all the glycolytic enzymes and by regulating pyruvate kinase splicing . Indeed,pe cells . An exampe cells .GLS-1 transcription start site near the 5′UTR  over glycolysis for energy production. Loss or inhibition of MYC leads to exaggerated reliance on FAO as an energy source in several cell and tissue models ; 2016. Fynthesis .2 from oxidative metabolism into H+ and bicarbonate. Excessive lactate-proton export results in extracellular acidification, which may drive further malignant cancer progression . The survival of these mice varied from 6 to 21 weeks. In end-stage hearts of all five cardiospecific knockouts, c-Myc was induced 4-12-fold. The authors also reported the upregulation of several known target gene sets of MYC, the most highly upregulated of them being related to the one-carbon metabolism. Kühl et al. did not study the role of MYC beyond mRNA expression but devoted a chapter to discussing the implications of this finding. In brief, they propose that MYC contributes to the remodeling of metabolism under severe mitochondrial dysfunction  subunit UQCRFS1 from mid-gestation . TranscrBcs1lp.S78G knock-in mice, Myc expression was highly upregulated (12-fold) and that it was the top predicted transcriptional regulator explaining the overall gene expression changes induced by CIII deficiency in the liver , kidney (4.1-fold), and heart (2.3-fold), the three tissues studied. Notably, the heart is presymptomatic at this age, dilating cardiomyopathy developing by postnatal day 200 (P200)  at both mRNA and protein level. In the P30 kidney (symptomatic), Myc mRNA was upregulated about 10-fold. In the skeletal muscle, which has very low CIII activity (∼25% of wild-type) but no clear myopathy  . We rece0 (P200)  extendedmyopathy , Myc mRNt 2-fold . Interest 2-fold , despiteBcs1lp.S78G mice, we see 50- to 600-fold upregulation of the EGFR ligand amphiregulin (AREG)  or signaling proteins such as Ras . Again, n (AREG) , a recenn (AREG) . A simpln (AREG) .Saccharomyces cerevisae). In this organism, Retrograde regulation protein 1 (Rtg1), the key conveyor of mitochondrial stress signals to the nucleus, has been suggested to be a MYC homolog  . It has ynthesis . Four diynthesis . Of thesynthesis . In addiynthesis .de novo serine biosynthesis, one-carbon metabolism, and the transsulfuration pathway  to interrogate the OXPHOS-dependent mechanisms. AOX is a mitochondrial enzyme from lower animals like yeasts, sea squirt  and plants and can transfer electrons directly from the coenzyme Q (CoQ) pool to oxygen when the CIII-CIV segment of the respiratory electron transfer is defective .The diseases . The condiseases . Furtherversus regeneration-capable  versus permanently postmitotic  tissues that are also metabolically quite different. Our recent findings in the Bcs1lp.S78G knock-in mouse model of severe CIII deficiency provide evidence that MYC forces illicit cell cycle entry against depletion of energy and biosynthetic precursors like nucleotides—with catastrophic consequences leading to cellular senescence and progeroid disease. However, the clinical phenotypes of CIII deficiencies caused by other BCS1L mutations or by mutations in other genes differ markedly from each other, and there is currently no knowledge about similar mechanisms in these phenotypes. Some key questions that remain to be studied are 1) What signals induce MYC in OXPHOS deficiency, 2) How does MYC contribute to the metabolic shift upon OXPHOS deficiency, and 3) Are the potentially harmful effects of MYC induction a general phenomenon in mitochondrial diseases or do they restrict to those diseases affecting proliferating or regenerating tissues? If MYC-driven DNA damage and cellular senescence occur also as a consequence of other mitochondrial disease mutations than those causing severe CIII deficiency, understanding the role of MYC could enable several novel therapeutic options. While MYC has a reputation of being an undruggable target in cancer, several MYC inhibitors have been developed and some of them have proceeded to clinical trials. Understanding the upstream factors leading to MYC upregulation would further diversify the options to target MYC in mitochondrial disease and potentially also in cancer.Here, we argue that MYC could be a functionally important player in mitochondrial diseases, hoping to stimulate researchers of mitochondrial medicine and physiology to study MYC in their models. Given the overarching roles of MYC as a regulator of energy metabolism in cancer and in normal tissue homeostasis, this proposition is not that surprising and has perhaps been hiding in plain sight during the almost 3 decades that mitochondrial diseases have been studied with modern molecular biology tools and methods. What is less clear at this point is the role of MYC in cell proliferation with respect to the widely varying manifestations of mitochondrial diseases in continuously proliferating


Medical students in China and other non-English speaking countries are susceptible to English as a Foreign Language (EFL) writing anxiety. English writing is not only a vital component tested for admission to postgraduate and doctoral programs, but it is also critical for the publication of academic papers. Although there is mounting evidence indicating relationships between anxiety, self-esteem and mobile phone addiction, pathways between these three constructs within a structural equation model have not yet been examined. Furthermore, there has been a dearth of studies exploring EFL writing anxiety, from which medical students in China as well as other non-English speaking countries are prone to suffer. The study was to assess EFL writing anxiety among Chinese medical students and to examine the relationships between EFL writing anxiety, self-esteem, and mobile phone addiction, with an aim to offer empirical evidence for effective preventive or intervention measures to alleviate EFL writing anxiety. Cross-sectional data were obtained from 1,238 medical students in China, with the administration of a self-administered questionnaire comprising the Second Language Writing Anxiety Inventory (SLWAI), the Rosenberg Self Esteem Scale (RSES) and the Mobile Phone Addiction Tendency Scale (MPATS). The results indicated that both self-esteem and mobile phone addiction exerted significant direct effects on EFL writing anxiety. Self-esteem also had a significant indirect effect on EFL writing anxiety via the mediating role of mobile phone addiction. The path coefficients of self-esteem on EFL writing anxiety were significantly reduced when mobile phone addiction was modeled as a mediator. Efforts to alleviate EFL writing anxiety among medical students may benefit from enhancing self-esteem and establishing a healthy relationship with mobile phones. English as a Foreign Language (EFL) learning has been the focus of a wealth of research efforts due to the accepted role of English as a lingua franca in academic settings and numerous other domains of globalization ,2. MountForeign language writing involves not only the grammatical and lexical accuracy but cultural appropriateness to construct content ,12, whicSelf-esteem, as one of learners’ individual affective factors, is conceptualized as an individual’s personal assessment of self-worth , which sMobile phone addiction has emerged as an increasingly serious issue which has aroused wide public concern. Admittedly, the convenient internet connectivity and user-friendly features of mobile phones enable them to be the most widely-used internet-access device  and to pWith findings from prior research raising the possibility that relationships might exist between anxiety, self-esteem and mobile phone addiction among university students, the pathways between these three constructs within a structural equation model has not yet been examined. Furthermore, despite mounting evidence linking either self-esteem or mobile phone addiction with anxiety, there has been a dearth of studies exploring EFL writing anxiety in the language learning contexts, with which medical students in China as well as other non-English speaking countries are prone to experience. Therefore, the study was to assess EFL writing anxiety among Chinese medical students and to examine the relationships between EFL writing anxiety, self-esteem and mobile phone addiction, with an aim to offer empirical evidence for effective preventive or intervention measures to alleviate EFL writing anxiety. Two hypotheses formulated for the present study were thus tested: (1) self-esteem and mobile phone addiction are positively associated with writing anxiety and (2) mobile phone addiction plays a mediating role in the relationship between self-esteem and writing anxiety among medical students in China.This study was conducted online from March to April in 2021 in China Medical University and Dalian Medical University, located in Liaoning province in the northeast of China. The study incorporated a cross-sectional survey design using stratified sampling methods. The sample consists of first-year, second-year and third-year medical students from 24 randomly-selected classes (with 8 classes from each grade) at China Medical University and Dalian Medical University. Eligibility for study participation included being 18 years old or older, able to read and respond in Chinese, and have access to the internet. A self-administered electronic questionnaire pertaining to demographic characteristics, EFL writing anxiety, self-esteem and mobile phone addiction was distributed via a widely-recognized professional online survey platform in China (“Wenjuanxing”) and the questionnaire link was sent to participants through the most widely-used social media applications (WeChat and Tencent QQ). Participants clicked the link to start filling the questionnaire and clicked the submit button to complete the submission once they finish it. The questionnaire was configured to ensure that it could be submitted only when all the questions had been fully completed and participants could go back to the previous questions and revise them before submitting their responses, which prevented the possibility of incomplete, inconsistent and duplicate data. After the elimination of the questionnaires with illogical answers, a logic and data consistency test was conducted, the result of which fulfilled the prerequisites of statistical analysis. The questionnaire was completely anonymous and confidential, which took approximately 15 to 20 minutes to finish. A total of 1,238 medical students provided complete and valid responses, thus constituting our final sample with the valid response rate being 88.7%.This study was conducted in accordance with the Helsinki declaration and was approved by the Committee on Human Experimentation of China Medical University. All participants were fully informed of the purpose and contents of study and provided written informed consent before participation.Demographic information collected in this study included age, gender, year of medical education, major, family monthly income, parents’ level of education, family location and history of major diseases .EFL writing anxiety was assessed based on the Second Language Writing Anxiety Inventory (SLWAI), which was developed by Cheng (2004) as a reliable measurement instrument for learners’ anxiety experiences during second or foreign language writing . SLWAI cSelf-esteem was measured with the Rosenberg Self Esteem Scale (RSES), which has been widely used and adapted into different languages with adequate reliability and validity . It consMobile phone addiction was assessed with the Mobile Phone Addiction Tendency Scale (MPATS), the most widely used tool for measuring mobile phone addiction among Chinese college students . It compSPSS 17.0 was used for the statistical analyses in this study with statistical significance determined by a two-tailed probability value of <0.05. T-tests and one-way ANOVA were conducted to test significant differences in EFL writing anxiety among the categorical variables. Descriptive statistics were calculated to summarize the distribution of demographic characteristics, self-esteem, mobile phone addiction and EFL writing anxiety. Correlations between self-esteem, mobile phone addiction, and EFL writing anxiety were assessed with Spearman’s correlation. Hierarchical regression analysis (HMR) was employed to measure the effects of demographic characteristics, self-esteem and mobile phone addiction on EFL writing anxiety. Blocks of independent variables including demographic characteristics, self-esteem and mobile phone addiction were entered in the regression model successively so that their incremental contributions to the HMR model could be examined.2/df < 5, RMSEA < 0.08, GFI > 0.90, CFI > 0.90, and TLI > 0.90), demonstrating good fitness. When mobile phone addiction was added, decrease of the direct path coefficient of self-esteem on EFL writing anxiety would indicate a mediating effect of mobile phone addiction. The bootstrapping procedure based on 5000 bootstrapping sample, a bias-corrected and accelerated 95% confidence interval (BCa 95% CI), and 95% percentile confidence intervals (percentile 95% CI) was adopted in this study, with a two-tailed probability value of <0.05 being considered statistically significant.Structural Equation Model (SEM) analysis was conducted by using Amos 17.0 to test whether mobile phone addiction played a mediating role between self-esteem and EFL writing anxiety. EFL writing anxiety and self-esteem were modeled as the dependent variable and the independent variable, respectively, with mobile phone addiction as the mediator. All indices involved were fitted with the SEM criteria . Those whose family monthly income was over 6000 yuan RMB tended to be less anxious about EFL writing than those whose family monthly income was below that level (P<0.01). Those whose parents received college education or above had lower scores of EFL writing anxiety than those whose parents have not attended college (P<0.01). Medical students from rural areas were more susceptible to EFL writing anxiety than those from urban areas (P<0.01).Medical students aged over 19 years old reported a higher level of EFL writing anxiety than those aged 19 or below (P<0.01). Specifically, self-esteem was significantly negatively correlated with EFL writing anxiety (P<0.01), while mobile phone addiction was significantly positively correlated with EFL writing anxiety (P<0.01).As illustrated in As shown in 2/df = 3.222<5, GFI = 0.982>0.90, AGFI = 0.965>0.90, CFI = 0.990>0.90, TLI = 0.983>0.90, RMSEA = 0.042<0.05), indicating that self-esteem had a significant direct effect on EFL writing anxiety . P<0.01) and EFL writing anxiety , with a high-level of goodness of fit . The path coefficient of self-esteem on EFL writing anxiety was significantly decreased  when mobile phone addiction was modeled as a mediating variable. It was revealed that mobile phone addiction played a statistically significant mediating role between self-esteem and EFL writing anxiety . Hence, self-esteem not only exerted a significant direct effect on EFL writing anxiety, but also had a significant indirectly effect on EFL writing anxiety via the mediating role of mobile phone addiction.This study examined the mediating effect of mobile phone addiction in the relationship between self-esteem and EFL writing anxiety, which has not yet been explored in the existing literature. The finding of this study were congruent with previous studies confirming the alleviating effect of self-esteem on anxiety and went further by proving its negative effect on EFL writing anxiety. This study echoed findings from recent cross-sectional studies conducted among university students in Spain, Vietnam and Indian, respectively, confirming that those with lower self-esteem tended to exhibit higher levels of anxiety ,30,31. TThis study extended the existing research by revealing that self-esteem not only exerts a direct effect on EFL writing anxiety but also has an indirect effect on it through the mediating path of mobile phone addiction. This negative influence of self-esteem on mobile phone addiction revealed in this study lends support to previous studies conducted among college students which indicated that self-esteem could be an important predictor for mobile phone addiction ,56. One Meanwhile, this study revealed that mobile phone addiction was positively associated with EFL writing anxiety among medical students, which was to some extent congruent with prior research indicating that mobile phone addiction was linked to an increased likelihood of higher levels of anxiety ,46. A reMeanwhile, findings of this study indicated that increased age, lower family income, lower education background of parents, and rural hometowns are linked to higher levels of EFL anxiety. One possible interpretation for these findings is that older medical students may be more aware of the importance of English writing competence both for medical education and for their future career as medical professionals. Meanwhile, those whose parents have comparatively lower levels of education and those who come from rural hometowns might have fewer social support resources available to them to improve English writing, which could also exacerbate their EFL writing anxiety.Findings of this study have potential implications for the design of foreign language teaching programs and curriculum that may aid in alleviating writing anxiety and facilitate language learning for EFL learners. This study extends existing literature by providing empirical evidence on the mediating role of mobile phone addiction in the association between self-esteem and EFL writing anxiety among Chinese medical students. It appeals for more attention to EFL writing anxiety among both language researchers and teachers and highlights the importance of better preparing medical students for addressing EFL writing anxiety. EFL medical students could be offered more opportunity to obtain insight into the underlying mechanism of the effects of self-esteem and mobile phone addiction on EFL writing anxiety. Also, more emphasis could be placed on individual affective factors in the pedagogical practices of EFL writing instruction and activities aimed at alleviating EFL writing anxiety could devote more efforts to enhancing self-esteem among EFL learners. Furthermore, EFL learners should be informed of the detrimental impact of smartphone addiction and provided with training programs to establish a healthy relationship with mobile phones and effectively interact with teachers or peers so that they could be better equipped to fulfill foreign language writing demands with lower levels of anxiety.One major limitation of this study is its cross-sectional design, in which no causal relationships between self-esteem, mobile phone addiction, and EFL writing anxiety could be concluded. Bidirectional relationships between these three variables might exist. Prospective studies are therefore necessary to provide longitudinal evidence for causal directions between self-esteem, mobile phone addiction, and EFL writing anxiety. Second, despite the large sample size and high response rate, participants were recruited from two medical universities located in two cities in one province of northeastern China, so the generalizability of the findings to a broader population of medical students needs to be verified by further empirical evidence.This study revealed that self-esteem exerts not only a direct effect but also an indirect effect on EFL writing anxiety through the mediating path of mobile phone addiction. Previous prevention and treatment of EFL writing anxiety mostly focus on students’ English competence without taking into consideration that students might be experiencing low self-esteem or mobile phone addiction. Hence, medical students in non-English speaking countries should be provided more opportunity to gain insight into the underlying mechanism of EFL writing anxiety and how self-esteem and mobile phone addiction could exert effects on EFL anxiety. Also, it is advisable that training programs on how to enhance self-esteem and establish a healthy relationship with mobile phones should be incorporated into the preclinical curriculum of medical education. Meanwhile, more activities involving interaction with teachers or peers could be taken into consideration to cope with challenges and alleviate anxiety in the EFL writing context.S1 Fig(TIF)Click here for additional data file.S2 Fig(TIF)Click here for additional data file.S1 Table(TIF)Click here for additional data file.S2 Table(TIF)Click here for additional data file.S3 Table(TIF)Click here for additional data file.S4 Table(TIF)Click here for additional data file.S1 Dataset(XLSX)Click here for additional data file.


A Dieulafoy lesion is an important consideration every gastroenterologist and internal medicine physician has to make in cases of recurrent, unidentifiable, and hemodynamically compromising gastrointestinal (GI) bleeding. A Dieulafoy lesion is an aberrant vessel that does not reduce in caliber when it extends from the submucosa to the mucosa. Damage to this artery can result in severe, intermittent arterial bleeding from tiny, difficult-to-visualize vessel stumps. Furthermore, these catastrophic bleeding episodes frequently result in hemodynamic instability and the need for transfusion of multiple blood products. As the patients presenting with Dieulafoy lesions often have concomitant cardiac and renal disease, familiarity with this condition is relevant as these patients are at risk of transfusion-related injuries. This case is unique as the Dieulafoy lesion was not visualizable in a standard location despite multiple esophagogastroduodenoscopy (EGD) and CT angiography, illustrating the difficulty of accurately managing and diagnosing this condition. A Dieulafoy lesion accounts for only 1%-2% of acute all gastrointestinal (GI) bleeds -4. DespiA 65-year-old male with a past medical history significant for heart failure with preserved ejection fraction, non-insulin-dependent diabetes mellitus type II, hypertension, and partial left nephrectomy, presented with upper abdominal pain and melenic stools. The patient embraced the use of non-steroidal anti-inflammatory drugs, including acetylsalicylic acid and ibuprofen, for chronic lower extremity pain. He was found hypotensive but responsive to IV volume resuscitation. The patient received empirically IV pantoprazole and was immediately taken to emergent endoscopy. Endoscopy did not reveal signs of acute bleeding in the duodenum. Despite pre-procedural erythromycin, the gastric examination remained limited due to adherent blood clots and blood pooling in the stomach (Figure The underlying case underscores a fundamental source of obscure GI bleeding, which is routinely challenging to visualize and is likely underrecognized . A DielaA Dieulafoy lesion is an aberrant vessel that can result in a catastrophic GI bleed. This entity is underrecognized among gastroenterologists and internal medicine physicians, and proper identification is crucial to decrease morbidity. A Dieulafoy lesion represents a critical differential diagnosis in cases of obscure GI bleeding, which frequently necessitates multiple transfusions of blood products, resulting in a high risk of volume overload or other transfusion-associated injuries, especially in patients with already pre-existing cardiovascular diseases. Endoscopic treatment options remain the treatment of choice for Dieulafoy lesions. Still, the obscure and intermittent bleeding character of Dieulafoy lesions often necessitates consideration of other diagnostic modalities, such as CT angiography and capsule endoscopy. The familiarity of this lesion and the proper identification of its drastic and recurring bleeding character might help facilitate correctly diagnosing this condition.


R-loops are inherent byproducts of transcription consisting of an RNA:DNA hybrid and a displaced single-stranded DNA. These structures are of key importance in controlling numerous physiological processes and their homeostasis is tightly controlled by the activities of several enzymes deputed to process R-loops and prevent their unproper accumulation. Senataxin (SETX) is an RNA/DNA helicase which catalyzes the unwinding of RNA:DNA hybrid portion of the R-loops, promoting thus their resolution. The key importance of SETX in R-loops homeostasis and its relevance with pathophysiological events is highlighted by the evidence that gain or loss of function SETX mutations underlie the pathogenesis of two distinct neurological disorders. Here, we aim to describe the potential impact of SETX on tumor onset and progression, trying to emphasize how dysregulation of this enzyme observed in human tumors might impact tumorigenesis. To this aim, we will describe the functional relevance of SETX in regulating gene expression, genome integrity, and inflammation response and discuss how cancer-associated SETX mutations might affect these pathways, contributing thus to tumor development. Senataxin (SETX) is an RNA/DNA helicase which catalyzes the resolution of R- loops, inherent byproducts of transcription consisting of an RNA:DNA hybrid and a displaced single-stranded DNA.Gain or loss of function mutations of SETX gene underlies the pathogenesis of two distinct neurological disorders: AOA2 (ataxia with oculomotor apraxia - type 2) and ALS4 , respectively.SETX physiological functions ranging from gene expression regulation to genome integrity maintenance and inflammation response.SETX dysregulation has been observed in human tumors and several evidence pointed towards a tumor suppressive role of this helicase.Are SETX defects directly involved in tumor onset and progression?Which specific SETX functions underlie its potential tumor suppressive role?Is it possible that SETX gain of function alterations might drive tumor development, similar to what is observed in neurological context?loci, including either coding or noncoding sequences, and their accumulation/stabilization is promoted at specific DNA regions, typically enriched with purine-rich sequences, or during replication-transcription collisions [Cells have evolved an intricate network of signaling activated in response to DNA damage that ensures that DNA lesions might not be converted into heritable mutations. Paradoxically, the major sources of mutagenic events are represented by physiological processes involving DNA and RNA metabolism. During DNA replication or gene transcription DNA undergoes a series of changes which may generate structural intermediates which can facilitate DNA mutations. An example of such structural intermediates are R- loops, RNA:DNA hybrids generated during transcription when the non-coding DNA strand is displaced as the transcribed DNA strand forms a hybrid with the nascent pre-mRNA , 2. Thesllisions .R-loops formation can impact numerous biological processes, such as antibodies diversification in B cells, DNA damage response and gene expression at multiple levels, including regulation of the chromatin architecture at the promoter region, transcription elongation, and termination –10. In hAlthough physiologically relevant for many biological processes, the persistence of the R-loops might be deleterious for cell viability –21. TherSETX is one of the best-characterized R-loops resolving helicase enzyme. The human SETX gene is localized on chromosome 9 and includes 33 exons codifying a 302-kDa protein. SETX protein presents key protein domains: an N-terminal protein interaction domain, the helicase domain, and a C-terminal Nuclear Localization Signal (NLS) Fig. . SETX isThe scientific interest in this enzyme started in 2004 when two independent groups found that recessive and dominant mutations of SETX gene are responsible for the pathology of two distinct neurological disorders: AOA2 (ataxia with oculomotor apraxia - type 2)  and ALS4SETX mutations in AOA2 patients (approximately 120 mutations identified so far) are localized throughout the entire sequence and include missense, nonsense, splice site, frameshift, and insertion/deletions. ALS4 mutations are mainly localized in the N-terminal portion and in the helicase domain. The type of mutations associated with these neurological diseases supports the concept that SETX loss of function underlines the pathogenesis of AOA2, while SETX gain of function is responsible for ASL4 , 31–33.The delineation of the physiological functions of human SETX has been markedly influenced by studies done on its yeast homolog, Sen1p which shares with the human SETX a conserved helicase domain, suggesting that both proteins may have similar functions. Indeed, SETX and Sen1p can resolve RNA Polymerase II-driven R-loops and direct the exosome to sites of transcription-replication collisions , 35. BotSimilarly to its yeast homolog, SETX is involved in the regulation of gene expression. SETX interacts with RNA pol II and other RNA transcription and processing factors, such as poly(A)-binding proteins 1 and 2 (PABP1/2), hnRNPs, SAP155, SMN, SPT5, TAF4, KAP1/TRIM28, and TP63 –43. ThesThe function of SETX to facilitate the transcriptional termination process is more relevant in highly expressed genes such as house-keeping genes. As line of principle, actively expressed genes should be more prone to undergo mutagenic events and therefore it is not surprising that R-loops processing at the termination sites and DNA damage response are functionally linked in order to limiting DNA lesions and preserve genome integrity. A relevant example of such functional interactions is represented by the ability of SETX to interact with BRCA1 , a tumorIn addition to BRCA1, SETX might regulate transcription termination through its recruitment by other factors that might dictate gene specificity. In human keratinocytes the master epithelial transcription factor ΔNp63 is able to recruit SETX on the termination region of early epidermal differentiation genes favoring R-loops removal on those loci and allowing efficient transcriptional termination and gene expression  Fig. 2A2A. RemarSETX interacting partners can also inhibit its activity as it happens in the circadian clock oscillation where a molecular complex involving the repressor PER binds to SETX blocking subsequent processing by XRN2  Fig. 2A2A. This,In addition to positively regulate gene expression, SETX may also act as transcriptional repressor. During meiosis, SETX-BRCA1 complex is recruited to XY sex chromosomes, where it mediates transcriptional sex chromosome inactivation . FurtherAlterations of the DNA damage and DNA repair signaling are hallmarks of many, if not all, human cancers , 58–62. Defects in R-loops homeostasis might interfere with the DNA damage response and impair DNA repair mechanisms, mainly when DNA lesions occurs at transcriptionally active regions. When double strand breaks (DSB) occur at transcribed loci, the transient formation of R-loops favors DNA repair and prevents illegitimate rejoining of broken ends . R-loopsThe critical role of SETX in preserving the genome integrity is also demonstrated by its ability to promote the removal of cytotoxic DNA interstrand crosslinks (ICLs) . GeneralIn addition to impair DNA repair pathway, SETX loss might induce per se DNA damage by inducing transcription stress. Mouse and human studies have indeed demonstrated that SETX deficiency results into R-loop accumulation at promoter-proximal regions, which in turn promotes RNA Pol II pausing/stalling  Fig. 2B2B. In th+/− and Setx−/− females are characterized by a decline of the ovarian activity, known as premature ovarian ageing (POA). In detail, SETX knock-out increases the DNA damage in ovarian follicles and reduces the ovarian follicular reserve. This phenotype does not seem to be related to defects of the DNA repair pathway but rather to the acquisition of de novo DNA damage, likely due to an increase of the oxidative stress. Intriguingly, BRCA1 deficiency has also been linked to POA and SETX deletion has been observed in ovarian cancers with a similar extent than BRCA1 deletions [Another example of the functional relationship between DNA damage and SETX has been recently reported by analyzing oocyte derived from SETX knock-out mice . Subramaeletions , 73.2O2, camptothecin, and mitomycin C, but not to ionizing radiation [2O2-induced DSB and enhanced chromosomal instability in response to H2O2. Along the same line, in Hela cells SETX loss is associated with impeded mtDNA replication and increased levels of intracellular reactive oxygen species (ROS) [The functional link between SETX activity and oxidative stress is not restricted to the female germline. AOA2 cells are characterized by an increased sensitivity to oxidative DNA damage insults such as Hadiation . Importaes (ROS) . These ees (ROS) . BRCA2 ies (ROS) –79.All together, these data indicate that defects of SETX activity impact the fidelity of DNA repair and DNA damage response signaling, induce transcription stress and lead to increased levels of DNA damage, which ultimately result to genomic rearrangements and genomic instability.It is well known that transcription may constitute a barrier for DNA replication mainly when replication and transcription machinery collides in head-on conformation on the lagging strand DNA , 81. TheInflammation signaling represents an essential physiological cellular response of the innate immunity involved in many biological processes, such as tissue repairing and defense against pathogens. However, chronic inflammation response has been largely proved to be related to pathogenesis of several human diseases, including cancer –89. In tMore recently, dysregulation of R-loops homeostasis by SETX loss has been linked with the activation of innate immune response . In detaL389S+/− knock-in animals suggesting that gain or loss of function SETX mutations differently impact inflammatory response, leading likely to different biological outcomes [Notably, SETX and IRF3-dependent signaling are also interconnected during virus infection. SETX is indeed able to attenuate the transcription of IRF3-dependent antiviral genes during the early phase of viral infection . Accordioutcomes .In the tumor context IRF3 activation by R-loops dysregulation should represent a cellular defense mechanism to limit the propagation of genomically unstable cells harboring aberrant DNA or RNA metabolism. Accordingly, in cancerous and immune cells cGAS-STING signaling has been linked to induction of cell death, cell senescence, and with the activation of antitumor immunity. However, the precise role of cGAS-STING signaling on cancer occurrence and progression is controversial. Indeed, several evidence indicates that this pathway may favor tumor metastasis and facilitate cancer progression , 97. It SETX gene and a tumor suppressive screening identified SETX as a mutated gene in breast cancer [http://www.cbioportal.org/public-portal). Some SETX residues are more prone to undergo mutations. For instances, R1623X mutations have been reported in in 4 cases of Uterine Endometrioid Carcinoma, 2 cases of stomach carcinoma and 2 cases of colon adenocarcinoma. Tumors with the highest rate of SETX mutations are uterine endometrial carcinoma , skin melanoma  and colon adenocarcinoma . Remarkably, cutaneous SCC patients harboring SETX mutation showed a decrease of the overall survival compared to wild-type counterpart. Three AOA2-related SETX mutations, Q868X, R1363X, and P413L have been reported in Uterine Carcinoma, colon carcinoma and skin melanoma, respectively, suggesting that loss of SETX function might be beneficial for tumor development and progression  SETX gene is frequently mutated or its expression is downmodulated in different malignancies; (ii) R-loops are generally considered oncogenic events since their unscheduled formation affects genome integrity; (iii) SETX controls DNA damage response and DNA repair mechanisms whose dysregulation is frequently observed in many, if not all, tumors; (iv) SETX physically interacts with the tumor suppressor gene BRCA1 to promote DNA repair at the transcribed loci; (v) SETX together with the exonuclease SAN1 is able to induce the repair of ICLs whose defects are associated with the cancer susceptibly syndrome Fanconi anemia (FA); (vi) SETX attenuates the replication stress, which in the tumor context is an early event triggered by the activity of many oncogenes; (vii) SETX activity is involved in inflammatory response which is often deregulated in many human tumors.Over the past years, multiple evidence have clearly established the critical role of the R-loops resolving enzyme SETX in different physiological and pathological processes. The most compelling evidence that SETX dysregulation affects human health is the finding that gain or loss of function mutations of Although these observations suggest a potential tumor suppressive role of SETX, the genetic and molecular evidence of the direct involvement of SETX defects in tumor onset and progression has not been provided so far. The lack of the cancer susceptibility phenotype in AOA2 patients as well as the absence of spontaneous tumorigenesis in SETX knock-out mice further complicates our comprehension of the potential impact SETX on tumor development. Furthermore, it is not clear which specific SETX functions underlie its potential tumor suppressive role. Analysis of AOA2 and ALS4 cells has clearly indicated that the unscheduled turnover of R-loops is a central hallmark of those neurological disorders. However, as discussed above, alterations of R-loops homeostasis by SETX dysregulation impinge on many processes, each of them potentially contributing to the development of neurological disorders as well as tumor development. Furthermore, it is possible that not only loss of function but also gain of function alterations might drive tumor development, similarly to what is observed in the neurological context. While AOA2 patients do not show an increase of cancer susceptibility, a cohort of ALS4 patients harboring SETX L389S mutation show the presence of benign and malignant intestinal lesions linking colon carcinoma development with SETX gain of function mutations. Although this phenotype has been reported in a single study and the molecular pathways underlying this phenotype are missing, we can argue that the biological outcome exerted by an efficient SETX enzyme, as much as one that removes R-loops inefficiently, could be instrumental for tumor development. For instances, in contrast to AOA2, ALS4 mutations affect the TGF-beta pathway which is commonly dysregulated in human colon adenocarcinoma. ALS4 mutations do not interfere with SETX sumoylation, which is required of its interaction with the RNA exosome complex at sites of replication-transcription conflicts , 44. It Another consideration emerging from these observations is that SETX levels need to be tightly regulated since slight alterations of its expression or activity may induce dramatic effect on cell homeostasis. Our understanding of the mechanisms regulating SETX expression is still limited. A recent report demonstrated that similarly to yeast Senp1, SETX protein levels are regulated by the ubiquitin proteasome system , a regulSETX is ubiquitously expressed. Nevertheless, SETX mutations affect only limited types of human tissues leading mainly to neurological disorders and defects in germline homeostasis. It is possible that these tissues are more sensitive to R-loop unscheduled turnover due to the type of transcribed genes or to the lack of an efficient compensatory mechanism. The same scenario might take place during tumor onset and only specific tissues might be sensitive to SETX dysregulation.In conclusion, these observations will certainly fuel future research aimed to formally clarify the impact of SETX on tumor evolution and enlighten the ambiguous boundary between the physiological and pathological outcome of SETX-driven R-loops resolution. The analysis of the functional consequences of SETX loss in mice models of cancer research will help our understanding of how and whether this important DNA/RNA helicase may impact tumor development and progression.


A ball valve thrombus is a common entity in rheumatic mitral stenosis where a large clot forms in the left atrial appendage, the clot detaches from the left atrial appendage, swirls in the left atrium in a clockwise manner, obstructs the mitral inflow producing cyclic acute pulmonary edema, and likely causes left ventricular outflow tract obstruction producing transient syncope or embolism to the brain producing dense hemiplegia. Besides rheumatic mitral stenosis, ball valve thrombus has been described in post-mitral valve replacement patients and restrictive cardiomyopathy. Left atrial myxoma sometimes rocks across the mitral valve producing the effect of a ball valve thrombus. Right atrial ball valve thrombus has been described after prolonged parenteral nutrition through a central line in intensive care units and in carcinoma patients with cardiac metastasis. We report an extremely rare case of a ball valve thrombus in an obese individual where dyslipidemia was the sole triggering factor for the formation of a ball valve thrombus in the left atrium. In critical mitral stenosis, due to mitral inflow obstruction, blood flow velocity across the orifice of the left atrial appendage slows down to less than 40 cm/second and blood starts to clot inside the left atrial appendage. Hence, the left atrial appendage becomes a nidus for thrombus formation in critical mitral stenosis. Sometimes a large thrombus forms inside the left atrial appendage, which detaches from the wall of the left atrial appendage, swirls inside the left atrium in a clockwise manner, and obstructs the mitral valve producing acute pulmonary edema known as a ball valve thrombus. This freely moving large clot inside the left atrium is prone to produce massive hemispheric embolization and catastrophic stroke in middle-aged and elderly individuals. Paroxysmal atrial fibrillation in these patients also makes them prone to developing thrombus inside the left atrial appendage, as during atrial fibrillation and fast ventricular rate, the left atrium behaves as a lake where the blood pool remains relatively stagnant producing a thrombus inside the atrium. The most important aspect of a ball valve thrombus is that sometimes it produces acute left ventricular outflow tract obstruction, hemodynamic collapse, and syncope before producing a hemispheric stroke. Post-cardiac surgery, especially post-mitral valve surgery, postoperative coagulopathy besides mechanical mitral valve in position also predisposes to the formation of a ball valve thrombus in the left atrium . The hug2. All serum chemistries were within normal limits except for dyslipidemia with a low-density lipoprotein (LDL) level of 197 mg/dL, total cholesterol of 264 mg/dL, and triglyceride (TG) of 335 mg/dL. A chest X-ray posteroanterior view revealed cephalization suggestive of passive pulmonary venous congestion. His N-terminal pro-brain natriuretic peptide level was 366 ng/mL suggestive of acute heart failure. Bedside echocardiography was done to evaluate the cause of dyspnea which revealed a freely mobile thrombus of 15 mm × 15 mm  was the provoking factor for the formation of a large clot inside the left atrium. Besides rheumatic mitral stenosis, degenerative calcific mitral valve disease, restrictive cardiomyopathy, and post-cardiac surgery hypercoagulable state with a prosthetic mitral valve in situ, isolated obesity with dyslipidemia can also be a predisposing factor for the formation of a ball valve thrombus in the left atrium. Early recognition of such ball valve thrombi with adequate systemic heparinization with anticoagulation can save young patients from a catastrophic large embolic hemispheric stroke.