Mycobacterium tuberculosis (Mtb) transmission substantially impacts health workers, patients and communities. Guidelines for tuberculosis infection prevention and control (TB IPC) exist but implementation in many settings remains suboptimal. Evidence is needed on cost-effective investments to prevent Mtb transmission that are feasible in routine clinic environments.Nosocomial Mtb transmission within the clinics and in their catchment populations. Intervention costs included the costs of the enablers  identified by stakeholders to ensure uptake and adherence.A set of TB IPC interventions was codesigned with local stakeholders using system dynamics modelling techniques that addressed both core activities and enabling actions to support implementation. An economic evaluation of these interventions was conducted at two clinics in KwaZulu-Natal, employing agent-based models of All intervention scenarios modelled, inclusive of the relevant enablers, cost less than US$200 per disability-adjusted life-year (DALY) averted and were very cost-effective in comparison to South Africa’s opportunity cost-based threshold (US$3200 per DALY averted). Two interventions, building modifications to improve ventilation and maximising use of the existing Central Chronic Medicines Dispensing and Distribution system to reduce the number of clinic attendees, were found to be cost saving over the 10-year model time horizon. Incremental cost-effectiveness ratios were sensitive to assumptions on baseline clinic ventilation rates, the prevalence of infectious TB in clinic attendees and future HIV incidence but remained highly cost-effective under all uncertainty analysis scenarios.TB IPC interventions in clinics, including the enabling actions to ensure their feasibility, afford very good value for money and should be prioritised for implementation within the South African health system. Mycobacterium tuberculosis transmission in clinics is a public health concern in South Africa.Guidelines for nosocomial infection prevention and control (IPC) are available but implementation is limited: barriers to successful implementation at both strategic and operational level are documented in the literature.Complexity science methods that consider the necessary enablers to overcome these barriers can inform economic evaluations to assist priority setting around investments in IPC.Interventions codesigned with tuberculosis (TB) IPC stakeholders in South Africa to include health system strengthening enablers are highly cost-effective.Two interventions were cost saving compared with base case: optimising the use of the existing Central Chronic Medicines Dispensing and Distribution system; and building modifications to improve ventilation.Operational-level enablers, including improved training and supervision and community sensitisation activities, are relatively inexpensive and do not affect the cost-effectiveness of IPC interventions.Investments in TB IPC, including additional budget to enable implementation, should be prioritised in South Africa, and similar settings.Low-cost enablers to ensure feasibility of TB IPC interventions in clinic settings can be identified by local and national stakeholders.Mycobacterium tuberculosis (Mtb) transmission, as evidenced by the higher incidence of latent Mtb infection among healthcare workers compared with the general population in high burden countries.Primary care clinics are important sites of Mtb transmission in clinics, the Umoya omuhle (‘good air’ in isiZulu) project adopted a multidisciplinary ‘whole systems’ approach to understand this complexity and to design IPC interventions that are appropriate and feasible to scale up to an optimal level of coverage in the South African context.8Guidelines for nosocomial TB infection prevention and control (IPC) are widely available.TB is a major public health concern in South Africa, which experienced rates of incidence and mortality among the highest in the world in 2020, driven by HIV.16The aim of this study is to estimate the value for money of TB IPC investment in the South African health system, including enabling interventions. To our knowledge, Umoya omuhle is the first study applying SDM in conjunction with an agent-based model to inform priority setting for TB IPC. Thus, we also aim to demonstrate this novel research method that can be used to assess cost-effectiveness of complex interventions more broadly.We conducted a cost-effectiveness analysis of TB IPC interventions compared with a counterfactual scenario without interventions (base case) for the general population in KwaZulu-Natal. Health benefits of the interventions were measured in terms of the disability-adjusted life-years (DALYs) averted. We conducted the analysis from the perspective of healthcare providers over a 10-year time horizon.A reflexivity statement covering all components of our international research partnership is included in the 10.1136/bmjgh-2022-010306.supp1Supplementary dataMtb transmission at clinic level, as well as from qualitative data from the Umoya omuhle study. The variable elicitation and causal loop diagram elaboration activities were designed based on published group model building scripts.The TB IPC interventions to be evaluated were selected using group model building, a participatory SDM technique used for the qualitative elaboration of causal loop diagrams.The intervention scenarios included are described in Mtb transmission among clinic attendees. The first model simulated the movement of attendees within the clinic space during their visits, while the second model simulated social contact behaviour in homes, clinics and other congregate settings to estimate the proportion of community TB incidence that resulted from clinic-acquired infections. The clinic-based model was parametrised using movement data collected on a single day at each of six primary care clinics in KwaZulu-Natal and five clinics in Western Cape. The community-based model was parametrised using data from a social contact survey conducted in the catchment areas of two clinics in KwaZulu-Natal. Methods, parameters and results of the modelling analyses are described briefly in Two agent-based models were built as part of the Umoya omuhle project to generate estimates of the impact of TB IPC interventions to reduce the risk of Annual costs of core intervention activities and enablers were estimated from a provider perspective by combining price and quantity data from the published literature and local supplier quotes. A full description of the interventions and enablers cost model, alongside an explanation of how SDM results were used to inform the costing exercise, is published elsewhere.The unit costs of consequential TB and HIV care were also derived from the published literature . All cosAgent-based simulations of each intervention were run for the 10-year period between 2021 and 2031. Consequential TB and antiretroviral therapy (ART) unit costs were attached to simulation outputs to estimate total diagnosis and treatment costs under different intervention scenarios. These were added to total intervention and enabler costs to calculate the incremental costs of each intervention scenario over the study period.DALYs averted in the population were also calculated from agent-based model outputs, including deaths by age and year and the annual population distribution across TB-related and HIV-related health states. Disability weights were derived from the 2019 Global Burden of Disease study,25Intervention scenarios were then ranked based on their incremental cost-effectiveness ratios (ICERs) compared with the base case. ICERs were compared with the current cost-effectiveness threshold for healthcare priority setting in South Africa, estimated at US$3200 per DALY averted.26et al.22Parameter uncertainty in the mathematical model was explored by conducting univariate sensitivity analyses around baseline ventilation rates and contact time in the clinics, the prevalence of TB in clinic attendees, and future HIV incidence. These analyses were used to construct a plausible range around the estimate of overall disease resulting from clinic transmission and of intervention impact. The sensitivity of the results to a range of other factors  was also considered in the effect modelling. The impact of these additional sensitivity analyses on reductions in TB incidence was far lower, however, and so they were not considered in the economic modelling. Full details of the univariate sensitivity analyses are reported by McCreesh A probabilistic sensitivity analysis using a Monte Carlo simulation was conducted to explore uncertainty around cost and disability weight parameters. Cost-effectiveness ratios were recalculated 10 000 times by randomly drawing parameters from appropriate probability distributions . Cost-efAll interventions and combination scenarios modelled were highly cost-effective compared with the current opportunity cost-based threshold for South Africa . The intFrom the univariate sensitivity analysis, the mathematical model parameters with the largest impact on intervention ICERs were baseline ventilation rates within the clinics and rates of clinic visits by individuals with infectious TB; and future HIV incidence . ICERs fOur study found that TB IPC interventions are an extremely efficient investment for South Africa, even when the full opportunity costs of investing in the necessary enablers to ensure effective intervention implementation are included. The wearing of surgical masks by patients and N95 respirators by clinic staff, the intervention with the highest ICER in our model, costs only US$151 per DALY averted and is considerably lower than the opportunity cost threshold for South Africa (US$3200 per DALY averted).28Our analysis indicates that the South African government should not face stark choices between funding new TB IPC interventions and investing in the necessary enablers to strengthen the health system and achieve the desired level of coverage and adherence to TB care and control measures. ICERs falling significantly below the cost-effectiveness threshold indicate that both interventions and enablers are affordable and should be implemented. Moreover, many of the enablers are shared by several of the interventions in the package, so costs will further decrease when combinations are implemented, and there may be positive spill over effects from strengthening administrative and clinical processes within facilities that can benefit interventions other than TB IPC. In addition to this, all the interventions we simulated would reduce airborne transmission of other infections in clinics and many would also reduce droplet transmission. Our study predates the COVID-19 pandemic, which may have caused an increase in the uptake of measures such as ensuring spaces are well ventilated and using personal protective equipment since our model was specified. Yet, if the benefits of averting other respiratory infections (including SARS-CoV-2) were taken into account, the interventions may be even more cost-effective.The current lack of prioritisation of TB IPC may rather stem from concerns around implementation barriers that stand in the way of achieving impact.The importance of considering health system constraints when assessing the cost-effectiveness of new interventions is now established in the literature.To our knowledge, our study is the first to test a systematic approach for stakeholder engagement to identify the specific constraints arising in a given setting and link that to an economic evaluation. Employing SDM to design the interventions allowed us to identify constraints that act not only at the operational level but also at the strategic, above-service level and even outside the remit of the health sector. The latter include, for example, unavailability of regular public transport links to the clinics, which impairs the successful implementation of appointment systems, or substantial time delays imposed on building retrofitting projects by the complex process for obtaining permissions and mobilising resources.23Our study has several limitations. First, estimates of intervention effects on clinic staff were derived using a more simplistic statistical model than the transmission models used for clinic attendees. However, DALYs averted in clinic staff were only 1%–2% of those averted in the general population, and so the effects of this on the overall cost-effectiveness estimates will have been minimal. Second, we did not explore all possible intervention combinations, largely due to lack of data on their joint effects. To the extent possible, SDM evidence was used to inform decisions on which interventions to include in the combination scenarios among those that could be modelled, so that the scenarios could be as informative as possible for policymakers in terms of both cost-effectiveness and feasibility. Thus, for example, building retrofits were excluded from the combinations considered due to the time delays inherent in their implementation. Finally, we assumed in the impact modelling that each intervention would be implemented in a fixed way, and/or achieve a fixed impact on behaviour . If the interventions are implemented differently , or have different effects on behaviour, then the reductions in TB incidence and DALYs averted may be higher or lower than our estimates. Future research should focus on how the complexity of relationships in the system could be explored more dynamically by using SDM to directly inform the agent-based model structure rather than just intervention design.Despite these limitations, our study demonstrated that investments in TB IPC represent very good value for money for South Africa, and are very cost-effective even when the costs of the necessary enablers to strengthen the health system are considered.


As countries embark on defining their guaranteed package of services, the existing laboratory network represents an extraordinary opportunity to use the already existing equipment at its install base and full capacity across programmes, and to expand the laboratory testing menu in the UHC package. This article focuses on diagnostics and describes the reasons why flexible and high-throughput molecular platforms are critical to ensure access to quality testing and to improve diagnostic service coverage in the context of UHC initiatives. Integrated models of service delivery are instrumental for ensuring impactful and sustainable UHC interventions. Horizontal integration links healthcare professionals operating at the same level of care and ensures multiple diagnostic tests are available in the same laboratory tier. The focus of vertical integration is to increase coordination among testing sites and to improve communication within the different tiers of the laboratory network  are to ensure that all people can access the quality health services that they need, to protect people from public health threats and to avoid catastrophic health expenditure. network . As a reMost testing has been carried out in central laboratories serving a large network of health facilities. Unfortunately, the role of laboratory-based platforms that allow the expansion of laboratories’ menus of assays  on the same analyser across different public health programmes has been undervalued, resulting in inadequate investments in vertical integration. This lack of investment has exacerbated the persistent issues related to communications between health facilities with the consequence of long turn-around times to get actionable results back to clinicians. Instead of strengthening the infrastructural gaps, the focus of different vertical programmes switched to bringing diagnostic services closer to patients, which increased the divides within laboratory networks.3 Global and national guidelines accompanied this transition to lower-level health facilities; however, many programmes for major diseases in low- and middle-income countries are still organised in vertical silos and lack the vision of combining platforms allowing menu expansion in different tiers of the laboratory network.4 Combined vertical and horizonal integration of diagnostic services across diseases has the potential to bring numerous benefits. For patients this results in more comprehensive care and services, added convenience due to time savings and reduced out-of-pocket expenses. For programmes, this results in cost savings from a more efficient use of resources, earlier treatment initiation and hence reallocation of resources to additional services. Lastly, this would increase the resilience of the health system to adapt to the onset of new diseases and public health threats that happen unexpectedly, such as outbreaks and epidemics.The development of diagnostics that can generate results in primary healthcare settings has favoured the decentralisation of diagnostic services in several areas, including tuberculosis, HIV, viral hepatitis and malaria, with the main result being that diagnostic capacity is now closer to the patients.5 A significant number of countries, including low- and middle-income countries, have built up their infrastructure in a short time. Diagnostics manufacturers responded to the pressing need for COVID-19 testing with rapid development and the launch of new COVID-19 tests. The increased awareness of the importance of diagnostic testing provides the opportunity to look at other diseases that can be eliminated and where diagnostics plays a key role. Tuberculosis, HIV, cervical cancer and viral hepatitis, although treatable, are still underdiagnosed in many high burden countries. Considering these concerns, over the years the World Health Organization has released several global strategies to end these diseases6  without disrupting routine sample processing.8 Menus comprising multiplex polymerase chain reaction assays allow differentiation of several pathogens in a single test, such as for respiratory or sexually transmitted infections. Multiplex assays enable laboratories to process more tests on demand in a given period of time. This conserves important testing materials that may be in short supply during an outbreak situation, and it saves sample volume that can be used for additional analyses. The addition of middleware solutions to the automated molecular diagnostic platforms could provide auto-verification capabilities that automate data transfer, improve turn-around time, reduce manual labour and the potential for human error. Centralised statistics and consolidated reports provided from the laboratories can give public health officials information for their ongoing surveillance programmes to control the spread of diseases and to monitor programme successes. Taken together, the HIV viral load and the COVID-19-driven uptake of molecular diagnostic platforms with expanded menus of assays provides a unique opportunity for laboratories to scale up molecular testing for HIV, viral hepatitis, tuberculosis, respiratory viruses, and high-risk human papillomavirus. The high automation level would enable laboratories to become more efficient in delivering high-quality results to support global health strategies in high burden countries. Furthermore, the flexibility of such platforms, both in terms of volumes and testing menus, place them at the forefront of regional initiatives for coordinated outbreak response and other initiatives of concern to public health.9 Simply increasing the number of shifts in the laboratory allows increases in the number of samples run on the platform. This flexibility is key for countries’ ability to rapidly cope with an increased demand for testing due to outbreaks and epidemics. The capability to use laboratory-developed tests on automated molecular diagnostic platforms can further strengthen the laboratories’ capabilities to respond in a timely manner to newly emerging diseases or variants.The recent coronavirus disease 2019 (COVID-19) pandemic exacerbated the need for expanded diagnostic capacity in such situations and the importance of a quick response time to address the increased demand for testing.iseases6 . COVID-1iseases6 . Previou10 The incremental cost-effectiveness of adding assays to the same high-throughput molecular diagnostic platform and the transportation of multiple specimens to the same laboratory would provide better use of scarce resources.11 This is particularly effective for infections like viral hepatitis C and human papillomavirus, where related diseases progress slowly, and access to results in a follow up visit does not impact clinical management. If required, results can be reported rapidly in situations where immediate clinical decisions must be made.8 Good coordination across multiple programmes is the foundation for more integrated testing to combine the advantages of both point-of-care tests and high-throughput molecular diagnostic platforms. Ideally, vertical and horizontal integration should occur simultaneously as part of the laboratory network optimisation supported by United States President’s Emergency Plan for AIDS Relief, the African Society for Laboratory Medicine and the Africa Centres for Disease Control and Prevention, with the ultimate goal of deploying laboratory-based platforms and point-of-care technologies where they are needed the most. High-throughput molecular diagnostic platforms, when used at full capacity, allow better use of resources across the laboratory network, which is central for achieving more people-centred care.While enabling scalability to react in an outbreak situation, an expanded menu of assays is a strong basis to continue expanding UHC packages. Countries can leverage existing sample referral networks, such as for HIV viral load testing, to serve multiple disease programmes by using the current infrastructure to move different specimen types from peripheral sites to the testing laboratory.


Under-ice eddies are prevalent in the major circulation system in the western Arctic Ocean, the Beaufort Gyre. Theoretical studies hypothesize that the eddy-driven overturning and the ice-ocean drag are crucial mechanisms of the gyre equilibration in response to atmospheric winds. However, due to severe weather conditions and limitations of remote sensing instruments, there are only sparse eddy observations in the ice-covered Arctic Ocean. Hence, the evolution of the under-ice eddy field, its impact on the gyre variability, and their mutual response to the ongoing Arctic warming remain uncertain. Here, we infer the characteristics of the under-ice eddy field by establishing its tight connection to the angular velocities of isolated spinning sea ice floes in marginal ice zones. Using over two decades of satellite observations of marginal ice zones in the western Arctic Ocean, we identified and tracked thousands of floes and used idealized eddy modeling to infer the interannual evolution of the eddy energetics underneath the ice. We find that the eddy field is strongly correlated to the strength of the Beaufort Gyre on interannual timescales, which provides the major observational evidence consistent with the hypothesis of the gyre equilibration by eddies. The inferred trends over the past two decades signify that the gyre and its eddy field have been intensifying as the sea ice cover has been declining. Our results imply that with continuing sea ice decline, the eddy field and the Beaufort Gyre will keep intensifying and leading to enhanced transport of freshwater and biogeochemical tracers. On the other hand, the sea ice cover can act as the dominant gyre equilibration mechanism by slowing down the currents via ice-ocean drag, leaving a minor role for eddies5. While the gyre state is likely somewhere in between these two limiting cases, it is expected that as the sea ice continues to retreat in the Arctic Ocean, the gyre will shift towards the eddy-governed regime5. Indeed, bulk estimates of the BG energy budget suggest that since 2008 eddies have been considerably draining potential energy and eventually dissipating it as kinetic energy at the ice-ocean interface6. However, the presence of sea ice in the Arctic Ocean imposes significant limitations on in situ field campaigns and hinders the acquisition of satellite eddy measurements common in temperate oceans. Without comprehensive eddy observations, projections of the BG transition to a climate with a dramatically reduced sea ice cover remain uncertain.The mechanisms governing the variability of the basin-scale anticyclonic circulation in the western Arctic Ocean—the Beaufort Gyre (BG) Fig. a—have be8 due to repeating wind bursts and surface waves. As a result, vast BG areas are covered by ice floes behaving like brittle solid bodies floating over a turbulent ocean. The floes range dramatically in size, forming a power-law distribution that evolves seasonally and regionally between marginal ice zones and the pack ice11. Because of the overall thermodynamic melting that opens up ice-free ocean areas and the frequent atmospheric storms that pull the floes apart from each other, many floes at the edge of the BG marginal ice zone are weakly- or non-interacting. The BG region is unique since its broken-up floes are vast, Here, we infer the BG eddy characteristics by taking advantage of the unique seasonality of its sea ice field. While the BG ice pack remains consolidated for most of the year, it naturally breaks up in late spring and summer14. This component is dominant given the generally strong winds and low interactions between the floes in the BG marginal ice zone. Nonetheless, here we emphasize that the translation of isolated floes is accompanied by a considerable spin  of the BG marginal ice zone to track individual floes and retrieve their spinning rates  model . The simulated translational and spinning motion of floes is qualitatively consistent with the observations  and drifted to the BG interior as has been previously hypothesized30.By tuning the two-layer QG model parameters, we found the eddy field characteristics that lead to the best fit between the observed and simulated rotational statistics of floes, specifically matching the rotation rate variances across all floe length scales with an average error of 19% . Such large BG eddies have been recently identified in remote sensing imagery from their signatures on the sea ice distribution in marginal ice zones24 as well as from open-ocean altimetry25.Our novel method resulted in eddy field characteristics that are in many ways consistent with observations from various measurement platforms as well as with large-scale BG energy constraints. The surface eddies are abundant, ranging from 10 to 60 km in size with characteristic Rossby numbers of .1) Fig. a. While 6. During the 2008–2014 period, the rate of kinetic energy input to geostrophic BG currents was about 0.1 mW m6. The missing energy dissipation rate needed to close the BG energy budget in the 2007–2014 period was about 0.1-0.2 mW m6. Another way of gauging the importance of eddies is to compare the gyre equilibration timescale with the time eddies would take to drain the excess APE gained during the gyre spinup. The APE variation over the 2003–2014 period was estimated at 40 PJ6. At a rate of 0.7 mW m32, highlighting the major role of eddies in BG energy cycle and equilibration.The inclusion of the quadratic ice-ocean drag played a crucial role in finding the optimal eddy field. Consequently, in contrast with ice-free oceans, the dominant mechanism of eddy energy dissipation in ice-covered oceans is at the surface, not at the bottom. Our best-fit model allows to estimate that the dissipation of eddy kinetic energy (EKE) by the sea ice-ocean drag occurs at a rate of about 0.7 mW min situ observations from moorings A,C, and D that are away from bathymetric features . The surface and subsurface EKE in the QG model are both linearly proportional to the variance of the simulated floe rotation rates  matches well with the BG strength index and the magnitude of the regional currents; correlations between pairs of indices range from 0.83 to 0.9. The low energy years for the eddy field were 2005–2006 and 2013, while 2008–2010 and 2016–2018 were the high energy years. The tightly correlated interannual variability of the eddy field and the BG strength supports the eddy equilibration hypothesis. However, recent moderate-resolution numerical simulations of the wind-driven BG spinup suggest that its eddy field does not significantly change in response to the spinup of the gyre34, which contradicts our observations. This incongruence implies that even comprehensive general circulation models do not adequately simulate eddy formation processes in the BG, significantly underestimating EKE likely due to inaccurate representation of the stratification and vertical shear of the large-scale currents.The reconstruction of floe rotation rates over the 2003–2020 period allows us to identify the relation between the strength of eddies and large-scale BG currents and assess their interannual and decadal trends Fig. . In compThe presence of sea ice and its associated ice-ocean drag is crucial in constraining the evolution of the large-scale BG currents and its eddy field. On interannual timescales, the gyre indices and the floe rotation follow opposite trends with the sea ice concentration Fig. . Broad tThis study presents a unique method of inferring the under-ice eddy variability in the western Arctic Ocean by analyzing the motions of relatively isolated sea ice floes in marginal ice zones. Specifically, using theoretical arguments and idealized modeling, we deduced that the scale-dependency of the floe rotation rate is directly related to the characteristics of the underlying oceanic eddy field. Piecing together almost two decades of satellite floe observations with a physical model of eddy dynamics, we inferred the best-fit characteristics of the ocean eddy field, including eddy lengthscales, EKE, and dissipation rates.in situ observations of subsurface EKE at the four BG mooring locations. Since our estimated subsurface EKE levels agreed well with mooring observations, it is reasonable to conclude that the surface eddies driving floe rotation extend into the halocline layer, i.e., these are not predominantly mixed layer eddies. Note, marginal ice zones are known to have strong density gradients that support surface eddy formation via frontal instabilities36. However, most of our floe observations are taken shortly after the consolidated pack ice breaks up into smaller floes, and hence surface density gradients have not been fully developed. Since the eddy field requires some time to adjust to the relatively ice-free conditions after the sea ice breaks up in spring/summer, our estimated eddy characteristics are likely more attributable to winter-like eddy fields formed under consolidated sea ice. Highly concentrated winter sea ice can significantly suppress mixed layer instabilities and surface eddies38. Thus, the expected lack of mixed layer eddies implies that floes are rotated predominantly by eddies that have origins in the interior of the ocean, not at the surface. This rationalizes the good fit between the observed subsurface EKE and that estimated from floe rotation that depends on surface eddies.Our method was validated with independent in situ eddy observations because their spatial or temporal coverage is very sparse given the heterogeneity and interannual variability of the eddy field. We note that existing mesoscale and submesoscale eddy parameterizations were developed and calibrated based on ice-free theory and modeling40. They do not account for additional EKE dissipation at the ice-ocean interface and hence likely overestimate eddy diffusivities and associated overturning in ice-covered regions. As global warming drives the Arctic Ocean towards a seasonally ice-covered state, developing improved eddy parameterizations is particularly important to accurately capture changes in eddy dynamics, their impact on large-scale currents, and distribution of water masses in ice-covered regions.Our analysis unveiled the ongoing under-ice eddy response to climate change in the western Arctic Ocean and demonstrated its tight connection to the BG currents and sea ice cover. The critical finding of our study is that the eddy field has been responding rapidly to changes in sea ice, with decadal trends indicating that the floes and underlying ocean eddies are now spinning significantly faster than two decades ago. The presence of sea ice dramatically suppresses the eddy field as its EKE is dissipated by friction due to the ice-ocean drag. As a result, the large-scale currents and the eddy field in the region can be expected to become much more energetic given the observed trend in sea ice extent. To this day, it had not been possible to reach this conclusion using existing 6. It was estimated that from 2008 to 2014, the gyre was storing less potential energy relative to the kinetic energy it was receiving from combined wind and sea ice stress work. The apparent energy surplus can be explained by the intensifying energy transfer from the BG potential energy via interior baroclinic instabilities towards eddies and the eventual dissipation of EKE by sea ice-ocean drag. The conclusion that the increasing imbalance between the cumulative surface-stress work and the available potential energy is a signature of increasing eddy energy relied crucially on the hypothesis that the gyre is significantly equilibrated by eddies. However, the lack of comprehensive eddy observations questions the conclusion about the possible eddy intensification. Our study of floe rotation provided the much-needed independent estimate of the BG eddy field characteristics under sea ice, right where the dissipation of eddy kinetic energy occurs. Our comprehensive analysis spanning observations from 2003 to 2020 concludes that the BG eddy intensification is indeed ongoing. It is not simply a part of interannual gyre variability but rather represents a strong decadal trend in response to the continuing sea ice loss in the western Arctic Ocean.The hypothesis regarding the intensification of the BG eddy field with declining sea ice cover has been put forward based on the analysis of sources/sinks of gyre mechanical energy from 2003 to 2014Finally, we comment on the implications of our results for the ongoing debate on the mechanisms of gyre equilibration. We provided the first observational evidence linking the EKE to large-scale BG currents and established that the EKE dissipation at the ice-ocean boundary layer is an important term in the BG energy budget. These results are consistent with the eddy equilibration hypothesis. They imply that the sea ice-ocean drag on its own does not entirely equilibrate the gyre, even though it does significantly reduce the Ekman pumping and the kinetic energy input into the gyre. These conclusions come with a noteworthy caveat that our method does not distinguish the eddy formation mechanisms and reconstructs combined characteristics of all eddies with surface expressions capable of driving floe rotation. To better understand the role of mesoscale eddies in the BG equilibration and interannual variability, it is necessary to quantify the eddy formation mechanisms and the associated eddy overturning, focusing on eddies formed via baroclinic instabilities of the large-scale currents in the BG interior.https://worldview.earthdata.nasa.gov). In this study, both Corrected Reflectance True and False Color images spanning spring and summer from 2003 to 2020 are employed. The reader is referred to the work of Lopez-Acosta et al.15 and Wolfe et al.41 for specifications regarding satellite acquisitions.Satellite Imagery. Sea ice measurements are retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) optical imagery (Level 1B 250M). This dataset can be directly downloaded from the open-access Earth Observing System Data and Information System (EOSDIS) Worldview platform (42. These measurements combine SSH estimates from open and ice-covered waters derived from Envisat (2003–2011) and CryoSat-2 (2012–2014).Ocean SSH. We employ measurements of monthly dynamic ocean topography (DOT) and geostrophic velocity currents in the Arctic basin retrieved by Armitage et al.26.Atmosphere. The effect of atmospheric forcing is assessed using ERA5 10 m wind speed reanalysis data  and the Advanced Microwave Scanning Radiometer 2 (AMSR2) products.Sea Ice Concentration. We evaluate sea ice concentration to discard interactions between identified ice floes. It is obtained from the NSIDC product MASAM2https://www2.whoi.edu/site/beaufortgyre/data/mooring-data/.Beaufort Gyre Moorings. Mooring velocity measurements are analysed to estimate the strength of mean currents and the subsurface eddy kinetic energy. The data (and its description) from the four BG moorings named A, B, C, and D  can be downloaded from the Beaufort Gyre Exploration Project website: Regional mean flow velocity. We characterized the strength of oceanic and atmospheric forcing in the BG from kinetic energy (KE) estimates. The seasonal oceanic and the wind surface KE is calculated as BG SSH anomaly. To characterize the strength of the BG, we calculate the characteristic sea surface height difference between an area encompassing the center of the gyre and its periphery. The center of the gyre is defined as the region enclosing most of the gyre during the spring and summer seasons from 2003 to 2020 . The area surrounding the gyre excludes shallow waters that are below 100 m deep  are analyzed per satellite to extract sea ice features amid changing atmospheric conditions. The process consists of three main modules: image processing, feature identification, and sea ice tracking.We identified and tracked ice floes using a newly developed feature matching algorithm that analyzes Moderate Resolution Imaging Spectroradiometer (MODIS) imagery from the EOS-NASA satellites, Terra and AquaThe image processing module effectively minimizes noise due to uneven illumination and cloud coverage while increasing the contrast between ice floes and ocean water. Geometrical parameters are then extracted, including perimeter, major and minor axes of the ellipse that matches the second central moment of the floes, centroid position, and surface and convex areas. The convex area is defined as the area of the smallest convex polygon enclosing an ice floe. As a result, ice floes with length scales ranging from 4 to 75 km are readily identified in each image.Ice floes are tracked by (1) comparing the suite of geometrical parameters of the ice in successive images, (2) finding potential matches, and (3) selecting the best candidates based on the assessment of a similarity metric and the surface area difference between them. The rotation rates of tracked ice floes are calculated by superimposing the shapes of ice floe pairs, rotating one over its axis, and tracking the angle change until the overlapping area is minimal. Finally, the angular velocity of each ice floe is calculated by averaging Aqua and Terra outputs and taking into account the timestamp at which the MODIS images being analyzed were acquired.The last step in creating our library of floes and their rotation rates is identifying and retaining the relatively isolated floes, i.e., those that do not significantly interact with nearby floes. This ensures that ice floe rotation is primarily due to the effect of external atmospheric and oceanic stresses rather than collisions. To achieve this, we computed the bounding box of identified ice floes. Interacting floes were detected based on the proximity of their respective bounding box and the instantaneous value of their rotation rates. Finally, sea ice concentration was evaluated (from MASAM2) to discard any identifications in regions with concentrations higher than 90mentclass2pt{minimA its surface area, h its characteristic thickness, I its moment of inertia, g is the acceleration due to gravity, The statistical characteristics of ice floe rotation rates are obtained by evolving the floes with observed shapes as solid bodies subject to forces and torques due to ice-ocean and atmosphere-ice stresses. No collisions between the floes are simulated as the statistics are compared against those of observed non-colliding floes. The ocean- and atmosphere-ice stresses are parameterized using quadratic drag laws as:15. An Eulerian grid with a resolution of 250 m is defined in the coordinate system moving with the center of mass of a rotating ice floe and used to calculate the surface integrals of forces and torques. Floe thickness observations are not available in the BG, but floes are expected to be between 0.5 to 2 m thick during the breakup events of the winter ice pack. Even though the equilibration timescale is sensitive to the thickness of the floes, it ends up being relatively short (ranging from one to a few hours), implying negligible inertial terms in Eq. The ice floe area is estimated from the library of geometrical properties obtained from MODIS imageryt=1 d since the start of the simulations after the dependence on the initial floe conditions is completely lost. For a given oceanic flow corresponding to a snapshot of equilibrated mesoscale turbulence, floe rotation rates are recorded, from which the histogram of rotation rate variance is computed as a function of floe size for quantitative comparisons with observations.The oceanic mesoscale flow, 46 to identify an eddy field that reproduces the observed rotational statistics of ice floes. The QG model generates eddies from baroclinic instabilities of vertically-sheared horizontal currents, which is the most common eddy-formation mechanism in the ocean47. The simplicity of the QG model is matched by its flexibility to generate a wide range of eddy field characteristics by varying only a few of its parameters: the Rossby deformation radius, 46 within a square doubly-periodic domain of 400 km by side and 256 spectral modes (resolution of about 1.5 km). The spectral filtering is applied for the smallest (grid size) eddies in the domain to halt the forward enstrophy cascade and ensure numerical stability.We use an idealized two-layer quasi-geostrophic (QG) modelThe simulated background flow becomes unstable and generates mesoscale eddies that actively interact with each other, developing a homogeneous and isotropic turbulent eddy field with a clear inertial range of the kinetic energy spectrum. The production of eddy kinetic energy is balanced by its frictional dissipation, predominantly by the ice-ocean drag. A commonly used quadratic ice-ocean drag law , the rotation rate Err, defined asThe key adjustable parameters of the QG two-layer model include the bulk vertical shear of the background horizontal velocity Rd or decreasing Rd and U, while the effective velocity shear U is only a slight overestimate of The three QG model parameters dramatically affect the corresponding eddy field and hence the rotational statistics of the simulated floes. The magnitude of the vertical velocity shear affects the strength of the eddies and hence variances of floe rotations at each length scale, moving the variance–length-scale curve  vertically on a log scale. For a given velocity shear, changing the deformation radius and the ratio of layer depths affects the overall energy of eddies and, more importantly, the scales of the equilibrated eddies and hence the slope of the variance-lengthscale curve. Specifically, increasing 48.To validate our results that the statistics of floe rotation contain direct information about the oceanic eddy field, we compare the predictions of subsurface EKE from the floe statistics with the point EKE measurements from BG moorings. The EKE from floe rotation is calculated as nce Fig. . Most ofWhile the majority of predicted and observed EKE points are close to the 1:1 line, there are clear outliers (Fig. Supplementary Information 1.Supplementary Information 2.


Mitochondrial homeostasis -including function, morphology, and inter-organelle communication- provides guidance to the intrinsic developmental programs of corticogenesis, while also being responsive to environmental and intercellular signals. Two- and three-dimensional platforms have become useful tools to interrogate the capacity of cells to generate neuronal and glia progeny in a background of metabolic dysregulation, but the mechanistic underpinnings underlying the role of mitochondria during human neurogenesis remain unexplored. Here we provide a concise overview of cortical development and the use of pluripotent stem cell models that have contributed to our understanding of mitochondrial and metabolic regulation of early human brain development. We finally discuss the effects of mitochondrial fitness dysregulation seen under stress conditions such as metabolic dysregulation, absence of developmental apoptosis, and hypoxia; and the avenues of research that can be explored with the use of brain organoids. From the brain, and from the brain only, arise our pleasures, joys, laughter and jests, as well as our sorrows, pains, griefs, and tears. Through it, in particular, we think, see, hear, and distinguish the ugly from the beautiful, the bad from the good, the pleasant from the unpleasant, in some cases using custom as a test, in others perceiving them from their utility.-Hippocrates (c. 460 B.C. - c. 370 B.C.)    Studies on human brain function and development have been a topic of controversy and ethical concerns throughout scientific history . It is uHomo sapiens from even the closest primate relatives. Cortical expansion, upper neuronal layer enlargement, increased neuronal diversity and function, complex connectivity and circuitry, are unique features of the human brain , non-human models have shown to reproduce the developmental stages, cellular composition, cytoarchitecture, and activity seen in the human brain . The advMitochondrial diseases, which are traditionally linked to disruption in OXPHOS, are usually associated with neurological phenotypes such as developmental delay, atrophy, and epileptic encephalopathy . Due to Remodeling of the mitochondrial network as human pluripotent stem cells (hPSCs) commit to a neuronal cell fate is necessary for their survival and function . Likewisin the first part of this review we provide an overview of cortical development and the use of PSC models. In the second part, we discuss our current understanding of mitochondrial and metabolic regulation during early human brain development and the effects of mitochondrial fitness dysregulation seen under stress conditions such as metabolic dysregulation, absence of developmental apoptosis, and hypoxia.The human CNS is composed of approximately 86 billion neurons, with a roughly equal number of glial cells . Ninety-The human brain has specie-specific characteristics that highlight the need for more representative modeling of development. For example, the developing brain has expanded proliferative zones  with diverse subtypes of neural stem and progenitor cells  that facilitate the expansion of the neocortex . The timHuman brain development is a prolonged and intricate process that starts around 2 weeks post conception and continues until early adulthood. The initial stages of this process rely primarily on the genetic control and the correct activation of neural programs, although, environmental factors can also affect the efficiency of the process.The genesis of the nervous system initiates about 2 weeks post conception. At this stage, the developing embryo is organized as a three-layered spherical structure. Cells in the ectoderm, one of the three germ layers, thicken to form the neural plate. The lateral edges of the neural plate will give rise to the neural fold that will join at the midline forming the neural tube. The closure of these tube occurs from the center to the cranial and caudal ends. Developmental defects at this point can cause anencephalia or spina bifida. The formation of the neural tube leads to the formation of the CNS by the cells located in the inner part of the tube, while the outer cells will give rise to the peripheral nervous system .Once the neural tube closes, around 4 weeks post-conception, the cranial end will expand to become a three-vesicle structure: the prosencephalon, the mesencephalon, and the rhombencephalon. By week 5 post-conception, the prosencephalon will give rise to the telencephalon, which will correspond with the forebrain and includes the cerebral hemispheres; and the diencephalon that will develop into the thalamus and hypothalamus . The mesMorphogen signaling during this period is crucial for the establishment of the development axis. The notochord, a structure derived from the axial mesoderm immediately ventral to the ectoderm , and theFGF8 is produced by the paraxial mesoderm and it’s downregulated before neural differentiation . This doXenopus implicated WNT (blend of the names Wingless and Int-1), RA and FGF as dorsalizing factors (Retinoic acid (RA) signaling is generated by the paraxial mesoderm for the induction of neural differentiation and patterning by downregulating fibroblast growth factor (FGF) production . RA gene factors .in vitro and in vivo (Sonic hedgehog (SHH) is produced by the notochord for the ventralization of neural cell types in a concentration dependent manner . Mouse e in vivo .The activation of WNT signaling, especially from Wnt3a, is necessary for the induction of posterior patterning . WNT sigBone morphogenetic protein (BMP) are produced by the non-neural ectoderm and the ventral mesoderm. High BMP signaling in the ventral ectoderm promotes the epidermal fate and represses the neural fate. BMP antagonists, such as Noggin, Chordin, Cerberus and Follistatin, are secreted by the Spemann-Mangold organizer , generatOnce the closure of the neural tube is complete, the cells lining the lumen of the tube will develop into the ventricles. This single cell layer of neuroepithelia is a pseudostratified epithelium composed by neuroepithelial progenitor cells . These aThis epithelium appears as stratified due to the cell nuclei migrating up and down the apical–basal axis during the cell cycle in a process known as interkinetic nuclear migration . In thisThe neuroepithelial progenitor cells divide in either a symmetric or asymmetric manner . SymmetrRounds of cell division from the neuroepithelial cells form several layers surrounding the lumen . The innNeuroepithelial cells give rise to a progenitor cell type that is more cell fate-restricted, the radial glial cells (RGCs) . These cPrior to the peak in neurogenesis, RGCs divide symmetrically to amplify the progenitor cell population . HoweverOuter radial glia and intermediate progenitors will establish the SVZ around week 9 post conception . oRGs reThe different types of progenitors can be identified not only by their morphology and presence of polarizing membrane proteins, but by the expression of certain fate markers . Radial The generation of cortical neurons, or corticogenesis, can be distinguished by the enlargement of the SVZ that has an inner (ISVZ) and outer region (OSVZ), and it is separated by a thin fiber layer . Cells uEarly born neurons migrate away from the ventricular surface, segregating themselves from the progenitors and forming the pre-plate. The first wave of neurons is composed by specialized pioneering cells or Cajal-Retzius neurons. These neurons organize adjacent to the pial surface forming the marginal zone, that in the adult human brain correspond with Layer I  and thatAs new neurons are born and start migrating into the pre-plate, this area is divided into the marginal zone, which is pushed outwards, and the subplate . The subBetween the marginal zone and the subplate, newborn neurons migrate and organize forming the cortical plate around post-conception weeks 8–9 . In thisCortical neurons are generated primarily (∼80%) by IPCs, while the other 10–20% can be traced back to RGCs . MoreoveFate acquisition has also been linked with the expression of subtype-specific transcription factors expressed in progenitors before neurogenesis; suggesting an early commitment to a particular cortical layer . The traDeep-layer progenitors express the transcription factors FEZF2 (Fez family zinc finger 2), OTX1 (Orthodenticle Homeobox 1), and EMX2 (Empty Spiracles Homeobox 2)  that havThe generation of layer VI neurons, around post-conception weeks 11–12 , is mediAs deep layer progenitors express OTX1 before neurogenesis, upper layer progenitors express the non-coding RNA SVET1. The expression of this marker is exclusive of layer II–IV and its activation is dependent on the correct expression of PAX6 . ExpressTransition to the production of upper layer neurons is mediated by the interaction of FEZF2, CTIP2, TBR1, and SATB2 . TBR1 is a downstream target of SATB2, and its repression is necessary for the differentiation of layer IV neurons . MoreoveCo-expression of Brain-Specific Homeobox/POU Domain Protein 1 (BRN1) and Brain-Specific Homeobox/POU Domain Protein 2 (BRN2/POU3F2) in most layer II–V cortical neurons is preceded by its expression in VZ progenitors and they are required for the control of radial migration in neurons residing in those cortical layers . MoreoveExpression of the transcription factor CUX2 in progenitors has been associated with the generation of cortical neurons from layers II/III  at post-During cortical neurogenesis, the promoters for astrocytic fate, such as GFAP, are heavily methylated and inaccessible to be activated by STAT3  . ExpressAstrocytes arise from radial glia in the VZ and PAX6+/HOPX+ oRGs in the outer SVZ  around pAnother class of glial cells, oligodendrocytes, originate from precursors in the proliferative dorsal and ventral zones of the developing brain . These cSonic Hedgehog signaling, through the activation of OLIG2, is necessary for oligodendrocyte development ; yet theAnimal models  and braiThe study of human embryonic development described in the previous section, specifically organogenesis and cell fate specification, has been greatly improved by the isolation and maintenance of PSCs . The accThe generation of neural cells was based on observations of the grafting effects of mouse teratocarcinoma lines in early embryos and in vitro . Cell agThe first account of human neural precursor cells differentiation from hESC was reported by the Thomson and Ben-Hur laboratories in 2001. After aggregation in embryoid bodies, neural tube-like structures were generated in the presence of FGF2 . RemovalXenopus laevis with neural-inducing properties following a dorsal fate pattern , PAX6 and Neuroepithelial stem cell protein (NESTIN). The intermediate filament NESTIN is expressed in both neuroepithelial cells and RGCs with different morphologies depending on the cell type and size . ExpressFurther differentiation to different neuronal cell types from different regions of the CNS have been achieved . PreviouAs an alternative to hPSC-derived neurons, direct differentiation from somatic cells into functional NPCs and neurons have been achieved, using either genetic or chemical manipulation of the embryonic pathways that promote transdifferentiation. The transcription factors BRN2, ASCL1, Myelin Transcription Factor 1-Like Protein (MYTL1), and Neurogenic differentiation 1 (NEUROD1); as well as the microRNAs miR-9* and miR-124, were initially used to generate different types of neurons from fibroblasts . Single in vitro recapitulation of nervous system development are neural rosettes (NR). These structures correspond to the third week of gestation  and interkinetic nuclear migration. Additionally, cells in NRs are positive for neuroepithelial markers such as PAX6, SOX1, NESTIN, Mushahi-1 (MSI1) and polysialylated neuronal cell adhesion molecule (PSA-NCAM). These cells also show self-renewal capacity, engraftment capacity, and can differentiate into different region-specific neural and glial types in response to developmental cues  can be isolated, expanded, and regionally specified without losing the rosette properties. Maintenance of the multipotency capacity has been shown to depend on the Notch signaling pathway, as low plating densities or the pharmacological inhibition of the pathway, increases the neuronal differentiation and causes a reduction in the rosette formation efficiency. Activation of the SHH has also been shown to be a key pathway in the maintenance of multipotency of NR-NSCs. Inhibition of both pathways cause rapid loss of rosette organization and reduction in the differentiation capacity .Although the default fate pathway for NR cells is the anterior CNS pattern by the expression of FOXG1 , re-specNeural rosette formation consists of five morphogenetic changes: intercalation of two or more cell rows, cellular constriction or shrinkage, polarization, elongation, and lumen formation. The formation of the lumen is mediated by apoptosis, inhibition of cell death via caspase inhibition disrupts lumen formation and delay neurogenesis. Ca2+ regulation is also critical in the formation of the NR by regulating multiple cytoskeletal proteins during the first three morphogenesis events. Calcium dysregulation also affects the localization of the polarizing proteins ZO1, PARD3 and β-catenin, which in turn impairs lumen formation. Disruption of the cytoskeleton  promotes premature neurogenesis and astrogenesis .FGF and BMP signaling are also necessary for the correct formation of the NRs. FGF2 and its receptor FGFR1 present an apical polarization in the lumen of the NR. FGF2 overexpression or inhibition disrupts the formation of the NRs and affects ZO1 expression and localization. The malformation of the NRs can be mediated by the displacement of ZO1 from the apical membrane which in time disrupts the membrane anchorage of FGFR1, causing the disruption on FGF2 signaling gradient, reduced cell proliferation, cell cycle exit and the premature differentiation of the NPCs . BMP sigThe brain organoid field started with the groundbreaking observations of the Yoshiki Sasai group. These initial studies demonstrated the ability of mouse ESCs to directly differentiate into telencephalic precursors in a serum-free suspension culture (SFEB culture). Treatments with WNT and Nodal antagonist resulted in a high yield of PAX6+ cells that could be further differentiated into ventral or dorsal fate after WNT3a or SHH, respectively . OptimizThe derivation of optimized mouse and human culture media allowed for the generation of three-dimensional aggregates that recapitulate embryonic corticogenesis and regional specification . PolarizCerebral organoids can be generated via undirected or directed differentiation. The undirected differentiation technique was described by the Knoblich group in 2013 . Single Directed differentiation uses small molecules to induce regional specification . The absAlthough a remarkable system to study neural development, iPSC-derived models present a set of limitations: cellular variability, lack of maturation, and limited reproduction of the brain cellular complexity . These lThe generation of NPCs relied on the differentiation of the hPSCs into neuroectodermal fate , which cSimilarities of iPSC-derived cortical neurons to primary cortical neurons have been established through single cell analysis but, layer-specific subtype characterization remains challenging . NPC culGeneration of astrocytes and oligodendrocytes is also challenging. Glial cell types appear later in development and require changes in the developmental cues. Current protocols, especially for oligodendrocyte generation, require the use of multiple small molecules and morphogens as well as month-long maintenance to generate cell populations suitable for experimentation .Due to the lack of vascularization, brain organoids display limited growth . Brain oAnother limitation of the brain organoid system is the inability to recapitulate developmental gradients. Fusion of regional aggregates has been useful to study neural migratory patterns and complex interregional interactions , but thiMitochondria are ubiquitous and essential organelles for cell survival. Known primarily for their capacity to generate energy via oxidative phosphorylation (OXPHOS) and their role in cell death, mitochondria also act as a signaling hub and coordination center for a myriad of cellular processes including metabolite synthesis and calcium buffering. Mitochondrial network remodeling, through fusion and fission, is necessary for discarding damaged or not functional mitochondria (mitophagy), to adapt to new energetic requirements, and to redistribute the organelle throughout the cytoplasm (motility) . StudiesThe energy producing machinery of the mitochondria is located in the cristae, invaginations of the inner mitochondrial membrane that increase the surface area . The proAll five complexes are localized along the cristae membrane with an overlapping distribution . The forThe correct formation and maturation of the cristae is considered a hallmark of cellular maturation and differentiation. PSCs have fragmented mitochondria with immature cristae  and whilDrosophila inhibits the cell cycle exit and promotes proliferation  that control cell fate and function . EndogenThese aspects of mitochondrial signaling beyond ATP production are certainly crucial during the cellular transitions that underlie human brain development. Brain organoids provide a useful tool to gain a mechanistic understanding of the involvement of these unique mitochondrial signaling pathways in human neurogenesis.The active remodeling of the mitochondrial network is crucial for the homeostatic and metabolic adaptation of the cell. Mitochondria are highly dynamic organelles that undergo fission and fusion event according to the cellular and environmental necessities. These highly conserved processes are regulated by large dynamin-related GTPases .Mitochondrial fission or fragmentation is executed by the highly conserved protein Dynamin-related protein 1 (DRP1) . ActivatMitochondrial fusion occurs when the outer and inner mitochondrial membrane merge with the corresponding membranes on another mitochondrion. Both fusion events are coordinated and occur simultaneously, resulting in the mixing of the mitochondrial contents in the matrix, membranes and intermembrane space and the homogenization of the mitochondrial DNA (mtDNA) and the formation and assembly of the electron transport chain (ETC) . AlthougNeurodevelopmental studies have shown mitochondrial dynamics are essential in neurogenesis. Mouse models deficient in DRP1 show smaller brain size and reduced developmental apoptosis in the neural tube ; as wellStudies in mouse models have shown significant cristae structural changes at the end of neural tube closure, as cells progress into neural progenitor stage. This modification in the mitochondria morphology correlates with the transition from a highly glycolytic metabolism to an OXPHOS dependent one . This swDisruption of mitochondrial fission and fusion proteins has been shown to result in both neurodevelopmental and neurodegenerative disease, both age-associated and progressive . MitochoThe regulation of mitochondrial dynamics and its physiological relevance in the context of tissue architecture is still an unexplored landscape . StudiesIn the developing mouse brain, In a follow up study, Although we are beginning to elucidate the role of mitochondria morphology and homeostasis during neuronal specification, little is known in human models about the role that these organelles play during gliogenesis. Astrocytes rely on glycolysis more than OXPHOS for their energy production, specially by the utilization of fatty-acids as source of fuel . MoreoveOligodendrocytes, on the other hand, rely on OXPHOS during the progenitor stage and switch to glycolysis when mature . Mitochoin vivo and 3-D settings. Most of the existing classification have resorted to manual and morphological classification  of the mitochondrial networks, utilizing qualitative or semi-quantitative approaches  is one of these rare inherited neurometabolic diseases. Mutations in more than 75 genes associated with ATP production have been identified as causal, both in nuclear and mitochondrial DNA. It affects mostly infants within their first year of life and has a poor prognosis and a low survival expectancy . It is cNdufs4–/– mice has shown partial rescue of the phenotype  and CRISPR/Cas9 corrected lines. As early as NPCs, deficiencies in the ability to switch to an OXPHOS energetic program and failure to differentiate into neurons were observed in both monolayer and brain organoid cultures. Aberrant cytoarchitecture was also observed in the LS mutant organoids. Importantly, rescue with SURF1 gene augmentation was able to rescue the observed phenotype, as well as pharmacological induction of PGC1A via bezafibrate, an antilipemic agent that lowers cholesterol and triglycerides  necessary for the acquisition of cardiac lineage . EMT is Particularly in the brain, developmental cell death is crucial for the during development and maturation of the neuronal connections. In the specific case of neuronal pruning, studies suggest that dysregulation of the mitochondrial membrane potential and the production of ROSs are signals for axonal retraction and degradation . Yet, itExtreme prematurity and complications prior to or during birth can contribute to hypoxic episodes and subsequent brain injury in neonates . As survStudies using rat brains showed that the mitochondrial morphology in neurons shifts from elongated to more granular/fragmented appearance after the hypoxic insult . Mitochoin vivo and in vitro models. Loss of the mitochondrial membrane potential leads to the cleavage OPA1 – responsible for inner mitochondrial membrane fusion. Oxygen deprivation increases the amount of a short non-functional form of OPA1, resulting in rapid induction of fission and ultimately cell death , MELAS syndrome  (a neurodegenerative disorder), and Autism Spectrum Disorder . But, the mechanisms by which mitochondrial morphology and function influence human brain development are largely unexplored.A massive challenge in the past has been the lack of appropriate model systems that can reproducibly recapitulate the heterogeneous nature as well as the highly complex properties of the human brain. As reviewed here, brain organoids reproduce several key features of human cortical development, including progenitor zone organization, neurogenesis, migration, and synaptic activity. Studies using human brain organoids will continue to provide insight into the mitochondrial mechanisms underlying neurogenesis as well as provide new angles to understand mitochondrial disorders.AR-M performed the initial literature review. AR-M and VG wrote the manuscript. Both authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


The gastrointestinal tract (GI tract) is the tract of the digestive system that contains all the major organs of the digestive system. Disorder in any part of the GI tract results in various disease forms such as malignancies. The occurrence of GI cancer is very high in developed countries including Europe. A wide variety of natural products containing anticancer properties showed significant effects. Ginger, the rhizome of Zingiber officinale, is among one of the natural herbal remedies widely used for its spice and medicinal properties. It is fair sources of vitamins like, β-carotene, vitamin C and minerals. Recently ginger has shown significant attention in clinical studies due to its anti-cancer effects that possesses promising potential for inhibiting the proliferation of multiple cancer cells. The aim of this review is to provide a summarized report of clinical trials on ginger constituents and its effects on gastrointestinal malignancies. A systematic search was conducted by two independent authors on the databases of Scopus, Clinical Trials, PubMed and Science with the search term of the key words. This review article supported that ginger is an important plant with several constituents and gastrointestinal medicinal effects. Ginger constituents suppress the growth and induce apoptosis of variety of cancer types including colon, gastric, pancreatic and other GI cancers. It is mainly the 6-gingerol and 6-shogaol, of the major compounds in ginger rhizomes, among hundreds of molecules. It is reported that antioxidant and anti-inflammatory properties of ginger support its preventive role against the gastrointestinal malignancies.• This review article provided evidences supporting the effects of ginger on gastrointestinal malignancies and demonstrates the importance of future studies.• Therefore, more extensive and well-controlled clinical trial studies of ginger are required to demonstrate its effect on gastrointestinal malignancies.


Bilateral vestibulopathy is a rare chronic condition with multiple etiologies. Bilateral vestibulopathy is characterized mainly by unsteadiness when walking or standing, which worsens in darkness, as well as oscillopsia. The degree of handicap caused by bilateral vestibulopathy is variable and remains controversial.To determine the value of the video Head Impulse Test in quantifying vestibular deficit and to establish its impact on the quality of life.Twenty patients  fulfilling the recent Barany criteria of bilateral vestibulopathy, responded to the Situational Vertigo Questionnaire and underwent vestibular examination including fixation, positional tests, oculomotor test battery and video head impulse test.The relation between each of the video head impulse test parameters and the scores from the questionnaire were statistically analyzed. We observed that patients with covert saccades on the video head impulse test were more likely to have a better quality of life than those with both covert and overt saccades, regardless of the vestibulo-ocular reflex gain in each semicircular canal. The presence of covert saccades was found to be associated with an improved quality of life regardless of the severity of vestibule ocular reflex-deficit. Our conclusion was that vestibule ocular reflex gain, measured by video head impulse test, does not quantify the severity of affection of quality of life in patients with bilateral vestibulopathy.Covert saccades are strategies aiming at minimizing the blurring of vision during head movement, that is an adaptive mechanism that improves quality of life. Therefore, we recommend that video head impulse test should be a part of the routine diagnostic workup of bilateral vestibulopathy. Bilateral Vestibulopathy (BVP) is a rare, heterogeneous, chronic vestibular disorder with different etiologies.The degree of handicap caused by BVP and its impact on a patient’s Quality Of Life (QOL) remain controversial.The purpose of the present study was to explore the association between vHIT results and the degree of handicap caused by BVP. We hypothesized that vHIT could be used to quantify the severity of BVP and its impact on QOL. If this relationship exists, Vhit could be a useful preliminary test to quantify the severity of BVP, which is important for patient rehabilitation.This was a cross-sectional observational study aimed to explore the association between the quantity of VOR deficit measured via vHIT, and the impact of BVP on QOL.This study was performed in the audio-vestibular unit of the Department of Otorhinolaryngology at the Main University Hospital in Alexandria, Egypt. The study was approved by the Ethics Committee of the Faculty of Medicine at Alexandria University in Egypt, IRB number 00007555. Twenty patients, fulfilling the recent Barany criteria of BVP, were included in this study. The enrolled patients presented with a minimum of 3 months of clinical history symptoms. All patients responded to the SVQ and pure tone audiometry. All subjects were evaluated using Videonystagmography (VNG) and vHIT.Scoring of the dizziness complaint was performed using a translated form of the SVQ.The impact on the patient’s QOL was classified as moderate if the symptoms mildly affected the patient’s routine daily activities, and as severe, if the patient needed assistance while performing those routine activities. Pure tone threshold sensitivity was measured. VNG examination was performed using the ICS Impulse 3-Dimensional vHIT system . The normal VOR-gain was > 0.8 for the lateral and > 0.7 for the vertical canals, as specified by the manufacturer.Fixation testing in neutral eye position, with and without vision, and positioning testing were performed. The battery of oculomotor tests  and vHIT using ICS Impulse  were performed. Regarding vHIT, both lateral and vertical canal stimulation tests were performed via passive head thrusts at 10°‒20° and a velocity range of 150°‒200°/sec.t-test was used to study both the relationship between the VOR-gain in each canal and its accompanying impact on QOL, as well as the relationship between the type of saccade and the associated SVQ score.The Chi-Square test was used to study the relationship between the type of saccade and its impact on QOL. The Twenty patients  were included in this study. Etiology of BVP for each of the 20 patients is shown in Six subjects showed bilateral normal hearing thresholds and one subject with bilateral schwannomas showed asymmetrical, moderately severe Sensorineural Hearing Loss (SNHL). The two subjects with Usher syndrome had unilateral cochlear implants with the other ear being profoundly deaf. Eight subjects had different levels of hearing loss, varying from mild to moderately severe SNHL.Fourteen patients (70%) showed a low VOR-gain in all six canals. The remaining six patients (30%) with idiopathic etiology showed no affection of the anterior canals on vHIT.Three types of saccades were reported: during vHIT (covert), after vHIT (overt), and a combination of during and after vHIT (scattered covert and overt saccades).None of the patients showed spontaneous nystagmus with vision. Six patients (30%) showed spontaneous nystagmus with vision denied. Patients with unilaterally spared anterior canal showed torsional downbeat nystagmus toward the spared canal.t-test performed to assess the relationship between type of saccades and SVQ score revealed a predictable relationship between the presence of covert saccades and a higher SVQ score .The proportion of BVP patients whose QOL was severely impacted with both covert and overt saccades was 100% (n = 8), whereas the proportion of BVP patients whose QOL was severely impacted with only covert saccades was 0%. The difference in proportions was statistically significant  and defining its severity is the rotary chair testing. Computerized Dynamic Posturography has been used to assess overall balance in BVP patients. A study by Sprenger et al. found a direct proportional relationship between the postural sway and the vestibular impairment, when recording the center of sway in BVP patients using posturography.Caloric test, vHIT, and dynamic visual field test are adjuvant tests in diagnosing BVH.Using vHIT is advantageous for testing each of the semicircular canals separately. Also, aging has no effect on the VOR measured by vHIT, except for faster head impulses in subjects older than 70 years.Weber et al. studied the relationship between vHIT gain and caloric responses in cases of gentamicin vestibulotoxicity and found an agreement between both tests.However, in the present study, the vHIT gains were not a reflection of the severity of BVP, inconsistent with the results of other studies. A study on 20 patients with BVH showed an association between low vHIT gains and the severity of BVP.The impact of covert saccades on visual performance in patients with BVP has been studied using dynamic visual acuity and vHIT.Additionally, covert saccades have been shown to decrease 37% of gaze error in patients with vestibular deficits.The present study demonstrated that the presence of covert saccades was associated with a moderate QOL impact and a lower SVQ score. Conversely, the presence of overt saccades was mostly associated with a severe QOL impact. Covert saccades, thus, play an important role in improving BVP symptomatology. This is in agreement with another study by Herman et al. that demonstrated the value of covert saccades in improving the dynamic visual acuity in BVP and in compensating for vestibular deficits.Thus, symptoms of BVP and their QOL impact should improve with time, regardless of the severity of the vestibular deficit. VOR-gain, as measured by vHIT, does not quantitatively reflect the severity of BVP. Future studies, involving larger numbers of BVP patients, are needed to validate our findings.The type of saccades measured by vHIT could reflect the severity of BVP and its impact on QOL. We recommend including vHIT in the diagnosis of BVP, as it is currently the only test able to evaluate the involvement of each semicircular canal and sparing of the vertical canals.The authors declare no conflicts of interest.


The Double Facets of Social Behavior in Drug Addiction” includes reviews and research articles spanning from preclinical animal models to human studies.The Special Issue of Frontiers in Behavioral Neuroscience “Social behaviors are important determinants for the etiology of several neuropsychiatry disorders, such as substance use disorders. Social interactions as an alternative to addictive drugs, in the form of social play and social support, tend to be protective against initiation, maintenance or relapse to drug use in both laboratory animals and humans. Conversely, negative social interaction in the form of stress and peer pressure, has an opposite effect with increasing drug use and relapse. This Special Issue covers the double facets of social behaviors in modulating substance use disorders with six research articles and one review.Pomrenze et al. reviewed the literature about the neurobiology of social brain. The authors focused on the effects of social defeat and social isolation, two major relevant social stressors, on drug dependence, on the neural circuits and the molecular mechanisms by which these stressors enhance vulnerability to drugs use. Additionally, the authors discussed how a history of drug use can also affect social behaviors, inducing a continuous circle of socio-addictive behaviors that influence each other. Finally, they identified candidate brain mechanisms that underlie the competitive nature of social and drug-rewards.Shuai et al. investigated the mechanisms underlying the alcohol harm paradox when socioeconomic deprivation is associated with greater alcohol problems despite lower alcohol consumption. The authors evaluated a multistage causal risk pathway that has been proposed to contribute to the alcohol harm paradox, in the form of questionnaires assessed by hazardous drinkers from an undergraduate population. The authors found that socioeconomic deprivation increased the probability of being exposed to aversive experiences, which enhanced the risk of internalizing symptoms, which augmented the risk of drinking to cope, which conferred susceptibility to alcohol dependence.Sharp and Smith determined the extent to which drugs that increase synaptic dopamine, norepinephrine, and serotonin influence the positive reinforcing effects of social contact relative to a non-social stimulus in both male and female rats. The study showed that increases in extracellular dopamine, but not extracellular norepinephrine or serotonin, enhance the positive reinforcing effects of social contact in both male and female rats without affecting the responding maintained by a non-social stimulus.Altshuler et al. explored the effect of housing conditions on incubation of oxycodone craving in rats with a history of oxycodone self-administration during either adult or adolescent phases. The authors reported no age differences in oxycodone self-administration and incubated oxycodone seeking at late abstinence phase after forced abstinence. Critically, the authors found that group-housing decreased oxycodone craving relative to the social isolation group showing the importance of social support during abstinence.Fulenwider et al. characterized the effects of social housing on ethanol intake in male mice using a two-bottle choice procedure. The authors reported that social-housed mice consumed more ethanol compared to single-housed mice. However, the overall intake levels of social-housed mice were lower than the levels of single-housed mice. This suggests that while environmental enrichment attenuates ethanol intake, social enrichment could potentiate it. Additionally, using immunohistochemistry, the authors reported a correlation between ethanol intake and FosB-positive cells in the Edinger-Westphal nucleus and nucleus accumbens shell in individually housed mice, but not in socially housed mice.Seidisarouei et al. using a novel behavioral social-sucrose behavioral procedure, classified the ultrasonic vocalization subtype for both sucrose and social reward. The authors demonstrated that time spent with the social stimuli was dependent on the concentration of sucrose available. Additionally, they found a difference in the emission of flat and frequency-modulated calls in the social and non-social reward zones. Lastly the authors reported a large variability in the rat vocalization repertoire toward non-social and social rewards.Kamens et al. investigated the biological and genetic mechanisms underlying the adolescent stress-induced long-term risk of opioid use in male and female C57BL/6J and BALB/cJ mice. The authors reported that adolescent stress did not influence morphine sensitization or consumption in BALB/cJ animals, and there was limited evidence of stress effects in female C57BL/6J mice. In contrast, male C57BL/6J mice exposed to chronic variable social stress during adolescence had blunted morphine sensitization compared to control animals. Additionally, C57BL/6J mice exposed to social stress during adolescence had attenuated corticosterone recovery following an acute stressor and downregulation of twelve miRNA in the prefrontal cortex compared to control mice.Altogether, this Special Issue highlights the importance of incorporating different aspects of social behavior spanning from housing conditions to sensory cues and different types of stressors in the investigation of the behavioral and biological mechanisms underlying its effect on substance use disorders with different abused drugs. Finally, we hope that this collection of articles will facilitate the development of fora and discussion groups to improve translational utility of animal models together with better social-based interventions for substance use disorders.RE and MV wrote the editorial. All authors approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Single-wall carbon nanotubes (SWCNTs) are promising materials for electronic applications, such as transparent electrodes and thin-film transistors. However, the dispersion of isolated SWCNTs into solvents remains an important issue for their practical applications. SWCNTs are commonly dispersed in solvents via ultrasonication. However, ultrasonication damages SWCNTs, forming defects and cutting them into short pieces, which significantly degrade their electrical and mechanical properties. Herein, we demonstrate a novel approach toward the large-scale dispersion of long and isolated SWCNTs by using hydrodynamic cavitation. Considering the results of atomic force microscopy and dynamic light-scattering measurements, the average length of the SWCNTs dispersed via the hydrodynamic cavitation method is larger than that of the SWCNTs dispersed by using an ultrasonic homogenizer. Single-wall carbon nanotubes (SWCNTs) have a wide range of promising applications in electronic devices such as transparent electrodes and field-effect transistors . In partHerein, for the first time, a hydrodynamic cavitation dispersion (HCD) method is applied to obtain the dispersion of SWCNTs in water with surfactant. The lengths of SWCNTs dispersed by using HCD method and a well-established ultrasonic homogenizer were compared. It is shown that the average length of SWCNTs dispersed via HCD method was larger than those dispersed by using the ultrasonic homogenizer. The result supports the advantage of HCD method for the retention of the superior electronic properties of SWCNTs during their dispersing process.g to remove SWCNT bundles, and the resulting supernatant was collected as the SWCNT dispersion. The control sample of SWCNT dispersion was prepared by using the same procedure, except for the dispersion process that uses a horn-type ultrasonic homogenizer . For these SWCNT solutions, the absorption spectra of the SWCNT solutions were measured by using a UV-vis-NIR spectrophotometer . The morphology of the SWCNTs, such as the lengths and diameters, was characterized via atomic force microscopy (AFM) . The samples for AFM observation were prepared by drop-casting of SWCNT dispersions onto SiO2/Si substrates. The AFM images were obtained in air. Dynamic light scattering (DLS)  measurements for the SWCNT dispersions were performed at a laser wavelength of 660 nm.Herein, SWCNTs produced via an enhanced direct-injection pyrolytic synthesis (eDIPS) method ,17 were We also measured the particle size for SWCNT dispersions by DLS  with a 6As mentioned above, the HCD method provides well-dispersed, longer SWCNTs than ultrasonic homogenization. Here, we discuss the plausible reasons for the higher length values of SWCNTs during the HCD process than the ultrasonication dispersing. During the HCD process, the mild force generated by the expansion and shrinkage of the cavitation microbubbles  and the Herein, the HCD method was applied for the large-scale dispersion of SWCNTs in an aqueous surfactant solution. Based on AFM analysis, it was concluded that the average length of the SWCNTs dispersed via the HCD method is about two times larger than that dispersed by using the ultrasonic homogenizer, and that the large-scale dispersion of long and isolated SWCNTs can be achieved by using the HCD method. The results were also supported by DLS measurements for the SWCNT dispersion solutions. The HCD method has the potential to contribute to the mass production of long-SWCNT dispersions in water containing surfactants.