Equipping for risk: Lessons learnt from the UK shale-gas experience on assessing environmental risks for the future geoenergy use of the deep subsurface

findings are presented from an investigation to improve understanding of the environmental risks associated with developing an unconventional-hydrocarbons industry in the UK. The EQUIPT4RISK project, funded by UK Research Councils, focused on investigations around Preston New Road (PNR), Fylde, Lancashire, and Kirby Misperton Site A (KMA), North Yorkshire, where operator licences to explore for shale gas by hydraulic fracturing (HF) were issued in 2016, although exploration only took place at PNR. EQUIPT4RISK considered atmospheric (greenhouse gases, air quality), water (groundwater quality) and solid-earth (seismicity) compartments to characterise and model local conditions and environmental responses to HF activities. Risk assessment was based on the source-pathway-receptor approach. Baseline monitoring of air around the two sites characterised the variability with meteorological conditions, and isotopic signatures were able to discriminate biogenic methane (cattle) from thermogenic (natural-gas) sources. Monitoring of a post-HF nitrogen-lift (well-cleaning) operation at PNR detected the release of atmospheric emissions of methane (4.2 ± 1.4 t CH4). Groundwater monitoring around KMA identified high baseline methane concentrations and detected ethane and propane at some locations. Dissolved methane was inferred from stable-isotopic evidence as overwhelmingly of biogenic origin. Groundwater-quality monitoring around PNR found no evidence of HF-induced impacts. Two approaches for modelling induced seismicity and associated seismic risk were developed using observations of seismicity and operational parameters from PNR in 2018 and 2019. Novel methodologies developed for monitoring include use of machine learning to identify fugitive atmospheric methane, Bayesian statistics to assess changes to groundwater quality, a seismicity forecasting model seeded by the HF-fluid injection rate and high-resolution monitoring of soil-gas methane. The project developed a risk-assessment framework, aligned with ISO 31000 risk-management principles, to assess the theoretical combined and cumulative environmental risks from operations over time. This demonstrated the spatial and temporal evolution of risk profiles: seismic and atmospheric impacts from the shale-gas operations are modelled to be localised and short-lived, while risk to groundwater quality is longer-term.

Age-dependent effects of metformin on human oligodendrocyte lineage cell ensheathment capacity

Metformin restores the myelination potential of aged rat A2B5+ oligodendrocyte progenitor cells and may enhance recovery in children with post-radiation brain injury. Human late progenitor cells (O4+A2B5+) have a superior capacity to ensheath nanofibres compared to mature oligodendrocytes, with cells from paediatric sources exceeding adults. In this study, we assessed the effects of metformin on ensheathment capacity of human adult and paediatric progenitors and mature oligodendrocytes and related differences to transcriptional changes. A2B5+ progenitors and mature cells, derived from surgical tissues by immune-magnetic separation, were assessed for ensheathment capacity in nanofibre plates over 2 weeks. Metformin (10 µM every other day) was added to selected cultures. RNA was extracted from treated and control cultures after 2 days. For all ages, ensheathment by progenitors exceeded mature oligodendrocytes. Metformin enhanced ensheathment by adult donor cells but reduced ensheathment by paediatric cells. Metformin marginally increased cell death in paediatric progenitors. Metformin-induced changes in gene expression are distinct for each cell type. Adult progenitors showed up-regulation of pathways involved in the process of outgrowth and promoting lipid biosynthesis. Paediatric progenitors showed a relatively greater proportion of down- versus up-regulated pathways, these involved cell morphology, development and synaptic transmission. Metformin-induced AMP-activated protein kinase activation in all cell types; AMP-activated protein kinase inhibitor BML-275 reduced functional metformin effects only with adult cells. Our results indicate age and differentiation stage-related differences in human oligodendroglia lineage cells in response to metformin. Clinical trials for demyelinating conditions will indicate how these differences translate in vivo.

Regulation of stress granule formation in human oligodendrocytes

Oligodendrocyte (OL) injury and subsequent loss is a pathologic hallmark of multiple sclerosis (MS). Stress granules (SGs) are membrane-less organelles containing mRNAs stalled in translation and considered as participants of the cellular response to stress. Here we show SGs in OLs in active and inactive areas of MS lesions as well as in normal-appearing white matter. In cultures of primary human adult brain derived OLs, metabolic stress conditions induce transient SG formation in these cells. Combining pro-inflammatory cytokines, which alone do not induce SG formation, with metabolic stress results in persistence of SGs. Unlike sodium arsenite, metabolic stress induced SG formation is not blocked by the integrated stress response inhibitor. Glycolytic inhibition also induces persistent SGs indicating the dependence of SG formation and disassembly on the energetic glycolytic properties of human OLs. We conclude that SG persistence in OLs in MS reflects their response to a combination of metabolic stress and pro-inflammatory conditions.

MerTK is a mediator of alpha-synuclein fibril uptake by human microglia

Mer tyrosine kinase (MerTK) is a receptor tyrosine kinase that mediates non-inflammatory, homeostatic phagocytosis of diverse types of cellular debris. Highly expressed on the surface of microglial cells, MerTK is of importance in brain development, homeostasis, plasticity and disease. Yet, involvement of this receptor in the clearance of protein aggregates that accumulate with ageing and in neurodegenerative diseases has yet to be defined. The current study explored the function of MerTK in the microglial uptake of alpha-synuclein fibrils which play a causative role in the pathobiology of synucleinopathies. Using human primary and induced pluripotent stem cell-derived microglia, the MerTK-dependence of alpha-synuclein fibril internalization was investigated in vitro. Relevance of this pathway in synucleinopathies was assessed through burden analysis of MERTK variants and analysis of MerTK expression in patient-derived cells and tissues. Pharmacological inhibition of MerTK and siRNA-mediated MERTK knockdown both caused a decreased rate of alpha-synuclein fibril internalization by human microglia. Consistent with the non-inflammatory nature of MerTK-mediated phagocytosis, alpha-synuclein fibril internalization was not observed to induce secretion of pro-inflammatory cytokines such as IL-6 or TNF, and downmodulated IL-1β secretion from microglia. Burden analysis in two independent patient cohorts revealed a significant association between rare functionally deleterious MERTK variants and Parkinson's disease in one of the cohorts (P = 0.002). Despite a small upregulation in MERTK mRNA expression in nigral microglia from Parkinson's disease/Lewy body dementia patients compared to those from non-neurological control donors in a single-nuclei RNA-sequencing dataset (P = 5.08 × 10-21), no significant upregulation in MerTK protein expression was observed in human cortex and substantia nigra lysates from Lewy body dementia patients compared to controls. Taken together, our findings define a novel role for MerTK in mediating the uptake of alpha-synuclein fibrils by human microglia, with possible involvement in limiting alpha-synuclein spread in synucleinopathies such as Parkinson's disease. Upregulation of this pathway in synucleinopathies could have therapeutic values in enhancing alpha-synuclein fibril clearance in the brain.

Analysis of the microglia transcriptome across the human lifespan using single cell RNA sequencing

BACKGROUND

Microglia are tissue resident macrophages with a wide range of critically important functions in central nervous system development and homeostasis.

METHOD

In this study, we aimed to characterize the transcriptional landscape of ex vivo human microglia across different developmental ages using cells derived from pre-natal, pediatric, adolescent, and adult brain samples. We further confirmed our transcriptional observations using ELISA and RNAscope.

RESULTS

We showed that pre-natal microglia have a distinct transcriptional and regulatory signature relative to their post-natal counterparts that includes an upregulation of phagocytic pathways. We confirmed upregulation of CD36, a positive regulator of phagocytosis, in pre-natal samples compared to adult samples in situ. Moreover, we showed adult microglia have more pro-inflammatory signature compared to microglia from other developmental ages. We indicated that adult microglia are more immune responsive by secreting increased levels of pro-inflammatory cytokines in response to LPS treatment compared to the pre-natal microglia. We further validated in situ up-regulation of IL18 and CXCR4 in human adult brain section compared to the pre-natal brain section. Finally, trajectory analysis indicated that the transcriptional signatures adopted by microglia throughout development are in response to a changing brain microenvironment and do not reflect predetermined developmental states.

CONCLUSION

In all, this study provides unique insight into the development of human microglia and a useful reference for understanding microglial contribution to developmental and age-related human disease.

Systematic comparison of culture media uncovers phenotypic shift of primary human microglia defined by reduced reliance to CSF1R signaling

Efforts to understand microglia function in health and diseases have been hindered by the lack of culture models that recapitulate in situ cellular properties. In recent years, the use of serum-free media with brain-derived growth factors (colony stimulating factor 1 receptor [CSF1R] ligands and TGF-β1/2) have been favored for the maintenance of rodent microglia as they promote morphological features observed in situ. Here we study the functional and transcriptomic impacts of such media on human microglia (hMGL). Media formulation had little impact on microglia transcriptome assessed by RNA sequencing which was sufficient to significantly alter microglia capacity to phagocytose myelin debris and to elicit an inflammatory response to lipopolysaccharide. When compared to immediately ex vivo microglia from the same donors, the addition of fetal bovine serum to culture media, but not growth factors, was found to aid in the maintenance of key signature genes including those involved in phagocytic processes. A phenotypic shift characterized by CSF1R downregulation in culture correlated with a lack of reliance on CSF1R signaling for survival. Consequently, no improvement in cell survival was observed following culture supplementation with CSF1R ligands. Our study provides better understanding of hMGL in culture, with observations that diverge from those previously made in rodent microglia.

Risk of hospitalisation or death in households with a case of COVID-19 in England: an analysis using the HOSTED data set

Objective

To determine whether household contacts of confirmed cases of COVID-19 have an increased risk of hospitalisation or death.

Methods

We used the HOSTED data set of index cases of COVID-19 in England between June and November 2020, linked to Secondary Uses Service data on hospital episodes and Office for National Statistics’ mortality data. Multivariable logistic regression models of the odds of household contacts being hospitalised or dying within six weeks of an index case, adjusted for case type, age, sex and calendar month were calculated. Excess risk was determined by comparing the first six weeks after the index case with 6–12 weeks after the index case in a survival analysis framework.

Results

Index cases were more likely to be hospitalised or die than either secondary cases or non-cases, having adjusted for age and sex. There was an increased risk of hospitalisation for non-cases (adjusted hazard ratio (aHR) 1.10; 95% confidence interval (CI) 1.04, 1.16) and of death (aHR 1.57; 95% CI 1.14, 2.16) in the first six weeks after an index case, compared to 6–12 weeks after.

Conclusion

Risks of hospitalisation and mortality are predictably higher in cases compared to non-cases. The short-term increase in risks for non-case contacts following diagnosis of the index case may suggest incomplete case ascertainment among contacts, although this was relatively small.

Reduced Metabotropic Glutamate Receptor Type 5 Availability in the Epileptogenic Hippocampus: An in vitro Study

Abnormalities in the expression of metabotropic glutamate receptor type 5 (mGluR5) have been observed in the hippocampus of patients with drug-resistant mesial Temporal Lobe Epilepsy (mTLE). Ex-vivo studies in mTLE hippocampal surgical specimens have shown increased mGluR5 immunoreactivity, while in vivo whole brain imaging using positron emission tomography (PET) demonstrated reduced hippocampal mGluR5 availability. To further understand mGluR5 abnormalities in mTLE, we performed a saturation autoradiography study with [³H]ABP688 (a negative mGluR5 allosteric modulator). We aimed to evaluate receptor density (B_max) and dissociation constants (K_D) in hippocampal mTLE surgical specimens and in non-epilepsy hippocampi from necropsy controls. mTLE specimens showed a 43.4% reduction in receptor density compared to control hippocampi, which was independent of age, sex and K_D (multiple linear regression analysis). There was no significant difference in K_D between the groups, which suggests that the decreased mGluR5 availability found in vivo with PET cannot be attributed to reduced affinity between ligand and binding site. The present study supports that changes within the epileptogenic tissue include mGluR5 internalization or conformational changes that reduce [³H]ABP688 binding, as previously suggested in mTLE patients studied in vivo.

Regional and age-related diversity of human mature oligodendrocytes

Morphological and emerging molecular studies have provided evidence for heterogeneity within the oligodendrocyte population. To address the regional and age-related heterogeneity of human mature oligodendrocytes (MOLs) we applied single-cell RNA sequencing to cells isolated from cortical/subcortical, subventricular zone brain tissue samples, and thoracolumbar spinal cord samples. Unsupervised clustering of cells identified transcriptionally distinct MOL subpopulations across regions. Spinal cord MOLs, but not microglia, exhibited cell-type-specific upregulation of immune-related markers compared to the other adult regions. SVZ MOLs showed an upregulation of select number of development-linked transcription factors compared to other regions; however, pseudotime trajectory analyses did not identify a global developmental difference. Age-related analysis of cortical/subcortical samples indicated that pediatric MOLs, especially from under age 5, retain higher expression of genes linked to development and to immune activity with pseudotime analysis favoring a distinct developmental stage. Our regional and age-related studies indicate heterogeneity of MOL populations in the human CNS that may reflect developmental and environmental influences.

Postsurgical seizure outcome in temporal lobe epilepsy patients with normal or subtle, nonspecific MRI findings

OBJECTIVE

The authors' objective was to report postsurgical seizure outcome of temporal lobe epilepsy (TLE) patients with normal or subtle, nonspecific MRI findings and to identify prognostic factors related to seizure control after surgery.

METHODS

This was a retrospective study of patients who underwent surgery from 1999 to 2014 at two comprehensive epilepsy centers. Patients with a clear MRI lesion according to team discussion and consensus were excluded. Presurgical information, surgery details, pathological data, and postsurgical outcomes were retrospectively collected from medical charts. Multiple logistic regression analysis was used to assess the effect of clinical, surgical, and neuroimaging factors on the probability of Engel class I (favorable) versus class II-IV (unfavorable) outcome at last follow-up.

RESULTS

The authors included 73 patients (59% were female; median age at surgery 35.9 years) who underwent operations after a median duration of epilepsy of 13 years. The median follow-up after surgery was 30.6 months. At latest follow-up, 44% of patients had Engel class I outcome. Favorable prognostic factors were focal nonmotor aware seizures and unilateral or no spikes on interictal scalp EEG.

CONCLUSIONS

Favorable outcome can be achieved in a good proportion of TLE patients with normal or subtle, nonspecific MRI findings, particularly when presurgical investigation suggests a rather circumscribed generator. Presurgical factors such as the presence of focal nonmotor aware seizures and unilateral or no spikes on interictal EEG may indicate a higher probability of seizure freedom.

Human oligodendrocyte myelination potential; relation to age and differentiation

OBJECTIVE

Myelin regeneration in the human central nervous system relies on progenitor cells within the tissue parenchyma, with possible contribution from previously myelinating oligodendrocytes. In multiple sclerosis, a demyelinating disorder, variables affecting remyelination efficiency include age, severity of initial injury, and progenitor cell properties. Our aim was to investigate the effects of age and differentiation on the myelination potential of human oligodendrocyte lineage cells.

METHODS

We derived viable primary oligodendrocyte lineage cells from surgical resections of pediatric and adult brain tissue. Ensheathment capacity using nanofiber assays and transcriptomic profiles from RNA sequencing were compared between A2B5+ antibody-selected progenitors and mature oligodendrocytes (non-selected cells).

RESULTS

We demonstrate that pediatric progenitor and mature cells ensheathed nanofibers more robustly than did adult progenitor and mature cells respectively. Within both age groups, the percentage of fibers ensheathed and ensheathment length per fiber were greater for A2B5+ progenitors. Gene expression of oligodendrocyte progenitor markers PDGFRA and PTPRZ1 were higher in A2B5+ vs A2B5- cells and in pediatric A2B5+ vs adult A2B5+ cells. p38 MAP kinases and actin cytoskeleton-associated pathways were upregulated in pediatric cells; both have been shown to regulate OL process outgrowth. Significant upregulation of "cell senescence" genes was detected in pediatric samples; this could reflect their role in development and the increased susceptibility of pediatric oligodendrocytes to activating cell death responses to stress.

INTERPRETATION

Our findings identify specific biological pathways relevant to myelination that are differentially enriched in human pediatric and adult oligodendrocyte lineage cells and suggest potential targets for remyelination enhancing therapies. This article is protected by copyright. All rights reserved.

Correcting for physiological ripples improves epileptic focus identification and outcome prediction

Objective

The integration of high‐frequency oscillations (HFOs; ripples [80–250 Hz], fast ripples [250–500 Hz]) in epilepsy evaluation is hampered by physiological HFOs, which cannot be reliably differentiated from pathological HFOs. We evaluated whether defining abnormal HFO rates by statistical comparison to region‐specific physiological HFO rates observed in the healthy brain improves identification of the epileptic focus and surgical outcome prediction.

Methods

We detected HFOs in 151 consecutive patients who underwent stereo‐electroencephalography and subsequent resective epilepsy surgery at two tertiary epilepsy centers. We compared how HFOs identified the resection cavity and predicted seizure‐free outcome using two thresholds from the literature (HFO rate > 1/min; 50% of the total number of a patient's HFOs) and three thresholds based on normative rates from the Montreal Neurological Institute Open iEEG Atlas (https://mni‐open‐ieegatlas.research.mcgill.ca/): global Atlas threshold, regional Atlas threshold, and regional + 10% threshold after regional Atlas correction.

Results

Using ripples, the regional + 10% threshold performed best for focus identification (77.3% accuracy, 27% sensitivity, 97.1% specificity, 80.6% positive predictive value [PPV], 78.2% negative predictive value [NPV]) and outcome prediction (69.5% accuracy, 58.6% sensitivity, 76.3% specificity, 60.7% PPV, 74.7% NPV). This was an improvement for focus identification (+1.1% accuracy, +17.0% PPV; p < .001) and outcome prediction (+12.0% sensitivity, +1.0% PPV; p = .05) compared to the 50% threshold. The improvement was particularly marked for foci in cortex, where physiological ripples are frequent (outcome: +35.3% sensitivity, +5.3% PPV; p = .014). In these cases, the regional + 10% threshold outperformed fast ripple rate > 1/min (+3.6% accuracy, +26.5% sensitivity, +21.6% PPV; p < .001) and seizure onset zone (+13.5% accuracy, +29.4% sensitivity, +17.0% PPV; p < .05–.01) for outcome prediction. Normalization did not improve the performance of fast ripples.

Significance

Defining abnormal HFO rates by statistical comparison to rates in healthy tissue overcomes an important weakness in the clinical use of ripples. It improves focus identification and outcome prediction compared to standard HFO measures, increasing their clinical applicability.

Association of EEG-fMRI Responses and Outcome After Epilepsy Surgery

BACKGROUND AND OBJECTIVES

To assess the utility of EEG-fMRI for epilepsy surgery, we evaluated surgical outcome in relation to the resection of the most significant EEG-fMRI response.

METHODS

Patients with postoperative neuroimaging and follow-up of at least 1 year were included. In EEG-fMRI responses, we defined as primary the cluster with the highest absolute t value located in the cortex and evaluated 3 levels of confidence for the results. The threshold for low confidence was t ≥ 3.1 (p < 0.005); the one for medium confidence corresponded to correction for multiple comparisons with a false discovery rate of 0.05; and a result reached high confidence when the primary cluster was much more significant than the next highest cluster. Concordance with the resection was determined by comparison to postoperative neuroimaging.

RESULTS

We evaluated 106 epilepsy surgeries in 84 patients. An increasing association between concordance and surgical outcome with higher levels of confidence was demonstrated. If the peak response was not resected, the surgical outcome was likely to be poor: for the high confidence level, no patient had a good outcome; for the medium and low levels, only 18% and 28% had a good outcome. The positive predictive value remained low for all confidence levels, indicating that removing the maximum cluster did not ensure seizure freedom.

DISCUSSION

Resection of the primary EEG-fMRI cluster, especially in high confidence cases, is necessary to obtain a good outcome but not sufficient.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that failure to resect the primary EEG-fMRI cluster is associated with poorer epilepsy surgery outcomes.

Women's experiences of early pregnancy assessment unit services: a qualitative investigation

OBJECTIVE

To explore the experiences of women who had used an Early Pregnancy Assessment Unit (EPAU) service in the UK and make recommendations for their improvement.

DESIGN

Qualitative interview study.

SETTING

Early Pregnancy Assessment Units in the UK.

SAMPLE

A maximum variation sample of women who had consented to be interviewed having attended one of 26 EPAUs involved in the VESPA study in 2018.

METHODS

In-depth telephone interviews with 38 women. A thematic framework analysis was conducted, with a focus on how experiences varied according to EPAU service configuration and clinical pathway.

MAIN OUTCOME MEASURES

Women's experiences of EPAU services.

RESULTS

We found that EPAUs are highly valued, and women's experiences were generally positive. However, women reported a range of issues that negatively affected their experience. These included difficulties accessing the service, insensitive management of the investigation and treatment options of pregnancy loss, poor communication, insufficient information and a lack of support for their psychological health. These issues were not strongly associated with EPAU configuration or clinical pathway.

CONCLUSIONS

Recommendations to improve women's experiences include the separation of EPAUs from general maternity services, and we make suggestions on how to remove barriers to access by reviewing opening hours, how to provide sensitive patient management, such as automatically cancelling appointments and scans following pregnancy loss, and how to improve communication, both with women and their partners as well as with other parts of the health service.

Patient specific prediction of temporal lobe epilepsy surgical outcomes

OBJECTIVE

Drug-resistant temporal lobe epilepsy (TLE) is the most common type of epilepsy for which patients undergo surgery. Despite the best clinical judgment and currently available prediction algorithms, surgical outcomes remain variable. We aimed to build and to evaluate the performance of multidimensional Bayesian network classifiers (MBCs), a type of probabilistic graphical model, at predicting probability of seizure freedom after TLE surgery.

METHODS

Clinical, neurophysiological, and imaging variables were collected from 231 TLE patients who underwent surgery at the University of California, San Francisco (UCSF) or the Montreal Neurological Institute (MNI) over a 15-year period. Postsurgical Engel outcomes at year 1 (Y1), Y2, and Y5 were analyzed as primary end points. We trained an MBC model on combined data sets from both institutions. Bootstrap bias corrected cross-validation (BBC-CV) was used to evaluate the performance of the models.

RESULTS

The MBC was compared with logistic regression and Cox proportional hazards according to the area under the receiver-operating characteristic curve (AUC). The MBC achieved an AUC of 0.67 at Y1, 0.72 at Y2, and 0.67 at Y5, which indicates modest performance yet superior to what has been reported in the state-of-the-art studies to date.

SIGNIFICANCE

The MBC can more precisely encode probabilistic relationships between predictors and class variables (Engel outcomes), achieving promising experimental results compared to other well-known statistical methods. Multisite application of the MBC could further optimize its classification accuracy with prospective data sets. Online access to the MBC is provided, paving the way for its use as an adjunct clinical tool in aiding pre-operative TLE surgical counseling.

HOSTED-England's Household Transmission Evaluation Dataset: preliminary findings from a novel passive surveillance system of COVID-19

BACKGROUND

Household transmission of SARS-CoV-2 is an important component of the community spread of the pandemic. Little is known about the factors associated with household transmission, at the level of the case, contact or household, or how these have varied over the course of the pandemic.

METHODS

The Household Transmission Evaluation Dataset (HOSTED) is a passive surveillance system linking laboratory-confirmed COVID-19 cases to individuals living in the same household in England. We explored the risk of household transmission according to: age of case and contact, sex, region, deprivation, month and household composition between April and September 2020, building a multivariate model.

RESULTS

In the period studied, on average, 5.5% of household contacts in England were diagnosed as cases. Household transmission was most common between adult cases and contacts of a similar age. There was some evidence of lower transmission rates to under-16s [adjusted odds ratios (aOR) 0.70, 95% confidence interval (CI) 0.66-0.74). There were clear regional differences, with higher rates of household transmission in the north of England and the Midlands. Less deprived areas had a lower risk of household transmission. After controlling for region, there was no effect of deprivation, but houses of multiple occupancy had lower rates of household transmission [aOR 0.74 (0.66-0.83)].

CONCLUSIONS

Children are less likely to acquire SARS-CoV-2 via household transmission, and consequently there was no difference in the risk of transmission in households with children. Households in which cases could isolate effectively, such as houses of multiple occupancy, had lower rates of household transmission. Policies to support the effective isolation of cases from their household contacts could lower the level of household transmission.

In vivo hippocampal cornu ammonis 1-3 glutamatergic abnormalities are associated with temporal lobe epilepsy surgery outcomes

OBJECTIVE

Previous positron emission tomography (PET) studies using [¹¹ C]ABP688 show reduced metabotropic glutamate receptor type 5 (mGluR5) allosteric binding site availability in the epileptogenic hippocampus of mesial temporal lobe epilepsy (MTLE) patients. However, the link between mGluR5 abnormalities and postsurgical outcomes remains unclear. Here, we test whether reduced PET [¹¹ C]ABP688 binding in cornu ammonis (CA) sectors more vulnerable to glutamatergic excitotoxicity relates to surgical outcomes.

METHODS

We obtained magnetic resonance imaging (MRI) and [¹¹ C]ABP688-PET from 31 unilateral MTLE patients and 30 healthy controls. MRI hippocampal subfields were segmented using FreeSurfer. To respect the lower PET special resolution, MRI-derived anatomical subfields were combined into CA1-3, CA4/dentate gyrus, and Subiculum. Partial volume corrected [¹¹ C]ABP688 nondisplaceable binding potential (BP_ND ) values were averaged across each subfield, and Z-scores were calculated. Subfield [¹¹ C]ABP688-BP_ND was compared between seizure-free and non-seizure-free patients. In addition, we also assessed subfield volumes and [¹⁸ F]fluorodeoxyglucose (FDG) uptake in each clinical group.

RESULTS

MTLE [¹¹ C]ABP688-BP_ND was reduced in ipsilateral (epileptogenic) CA1-3 and CA4/dentate-gyrus (p < .001, 95% confidence interval [CI] = .29-.51) compared to controls, with no difference in Subiculum. [¹¹ C]ABP688-BP_ND and subfield volumes were compared between seizure-free (Engel IA, n = 13) and non-seizure-free patients (Engel IC-III, n = 10). In ipsilateral CA1-3 only, [¹¹ C]ABP688-BP_ND was lower in seizure-free patients than in non-seizure-free patients (p = .012, 95% CI = 1.46-11.0) independently of volume. A subset analysis of 12 patients with [¹¹ C]ABP688-PET+[¹⁸ F]FDG-PET showed no between-group significant difference in [¹⁸ F]FDG uptake, whereas CA1-3 [¹¹ C]ABP688-BP_ND remained significantly lower in the seven of 12 seizure-free patients (p = .03, 95% CI = -3.13 to -.21).

SIGNIFICANCE

Reduced mGluR5 allosteric site availability in hippocampal CA1-3, measured in vivo by [¹¹ C]ABP688-PET, is associated with postsurgery seizure freedom independent of atrophy or hypometabolism. Information derived from hippocampal CA1-3 [¹¹ C]ABP688-PET is a promising imaging biomarker potentially impactful in surgical decisions for MRI-negative/PET-negative MTLE patients.

Brain Shift in Neuronavigation of Brain Tumors: An Updated Review of Intra-Operative Ultrasound Applications

Neuronavigation using pre-operative imaging data for neurosurgical guidance is a ubiquitous tool for the planning and resection of oncologic brain disease. These systems are rendered unreliable when brain shift invalidates the patient-image registration. Our previous review in 2015, Brain shift in neuronavigation of brain tumours: A review offered a new taxonomy, classification system, and a historical perspective on the causes, measurement, and pre- and intra-operative compensation of this phenomenon. Here we present an updated review using the same taxonomy and framework, focused on the developments of intra-operative ultrasound-based brain shift research from 2015 to the present (2020). The review was performed using PubMed to identify articles since 2015 with the specific words and phrases: “Brain shift” AND “Ultrasound”. Since 2015, the rate of publication of intra-operative ultrasound based articles in the context of brain shift has increased from 2–3 per year to 8–10 per year. This efficient and low-cost technology and increasing comfort among clinicians and researchers have allowed unique avenues of development. Since 2015, there has been a trend towards more mathematical advancements in the field which is often validated on publicly available datasets from early intra-operative ultrasound research, and may not give a just representation to the intra-operative imaging landscape in modern image-guided neurosurgery. Focus on vessel-based registration and virtual and augmented reality paradigms have seen traction, offering new perspectives to overcome some of the different pitfalls of ultrasound based technologies. Unfortunately, clinical adaptation and evaluation has not seen as significant of a publication boost. Brain shift continues to be a highly prevalent pitfall in maintaining accuracy throughout oncologic neurosurgical intervention and continues to be an area of active research. Intra-operative ultrasound continues to show promise as an effective, efficient, and low-cost solution for intra-operative accuracy management. A major drawback of the current research landscape is that mathematical tool validation based on retrospective data outpaces prospective clinical evaluations decreasing the strength of the evidence. The need for newer and more publicly available clinical datasets will be instrumental in more reliable validation of these methods that reflect the modern intra-operative imaging in these procedures.

Limits on the Existence of sub-MeV Sterile Neutrinos from the Decay of ^{7}Be in Superconducting Quantum Sensors

Sterile neutrinos are natural extensions to the standard model of particle physics and provide a possible portal to the dark sector. We report a new search for the existence of sub-MeV sterile neutrinos using the decay-momentum reconstruction technique in the decay of ^{7}Be. The experiment measures the total energy of the ^{7}Li daughter atom from the electron capture decay of ^{7}Be implanted into sensitive superconducting tunnel junction (STJ) quantum sensors. This first experiment presents data from a single STJ operated at a low count rate for a net total of 28 days, and provides exclusion limits on sterile neutrinos in the mass range from 100 to 850 keV that improve upon previous work by up to an order of magnitude.

Large-scale mGluR5 network abnormalities linked to epilepsy duration in focal cortical dysplasia

To determine the extent of metabotropic glutamate receptor type 5 (mGluR5) network abnormalities associated with focal cortical dysplasia (FCD), we performed graph theoretical analysis of [11C]ABP688 PET binding potentials (BPND), which allows for quantification of mGluR5 availability. Undirected graphs were constructed for the entire cortex in 17 FCD patients and 33 healthy controls using inter-regional similarity of [11C]ABP688 BPND. We assessed group differences in network integration between healthy controls and the ipsilateral and contralateral hemispheres of FCD patients. Compared to healthy controls, FCD patients showed reduced network efficiency and reduced small-world connectivity. The mGluR5 network of FCD patients was also less resilient to targeted removal of high centrality nodes, suggesting a less integrated network organization. In highly efficient hub nodes of FCD patients, we observed a significant negative correlation between local efficiency and duration of epilepsy only in the contralateral hemisphere, suggesting that some nodes may be more vulnerable to persistent epileptic activity. Our study provides the first in vivo evidence for a widespread reduction in cortical mGluR5 network integration in FCD patients. In addition, we find that ongoing epileptic activity may alter chemoarchitectural brain organization resulting in reduced efficiency in distant regions that are essential for network integration.

Technical Aspects of SEEG and Its Interpretation in the Delineation of the Epileptogenic Zone

Stereo-electroencephalography (SEEG) has gained global popularity in recent years. In Japan, a country in which invasive studies using subdural electrodes (SDEs) have been the mainstream, SEEG has been approved for insurance coverage in 2020 and is expected to gain in popularity. Some concepts supporting SEEG methodology are fundamentally different from that of SDE studies. Clinicians interested in utilizing SEEG in their practice should be aware of those aspects in which they differ. Success in utilizing the SEEG methodology relies heavily on the construction of an a priori hypothesis regarding the putative seizure onset zone (SOZ) and propagation. This article covers the technical and theoretical aspects of SEEG, including the surgical techniques and precautions, hypothesis construction, and the interpretation of the recording, all with the aim of providing an introductory guide to SEEG.

A multi-scale cortical wiring space links cellular architecture and functional dynamics in the human brain

The vast net of fibres within and underneath the cortex is optimised to support the convergence of different levels of brain organisation. Here, we propose a novel coordinate system of the human cortex based on an advanced model of its connectivity. Our approach is inspired by seminal, but so far largely neglected models of cortico-cortical wiring established by postmortem anatomical studies and capitalises on cutting-edge in vivo neuroimaging and machine learning. The new model expands the currently prevailing diffusion magnetic resonance imaging (MRI) tractography approach by incorporation of additional features of cortical microstructure and cortico-cortical proximity. Studying several datasets and different parcellation schemes, we could show that our coordinate system robustly recapitulates established sensory-limbic and anterior-posterior dimensions of brain organisation. A series of validation experiments showed that the new wiring space reflects cortical microcircuit features (including pyramidal neuron depth and glial expression) and allowed for competitive simulations of functional connectivity and dynamics based on resting-state functional magnetic resonance imaging (rs-fMRI) and human intracranial electroencephalography (EEG) coherence. Our results advance our understanding of how cell-specific neurobiological gradients produce a hierarchical cortical wiring scheme that is concordant with increasing functional sophistication of human brain organisation. Our evaluations demonstrate the cortical wiring space bridges across scales of neural organisation and can be easily translated to single individuals.

Treatment of Epilepsy Associated with Periventricular Nodular Heterotopia

PURPOSE OF REVIEW

Epilepsy associated with periventricular nodular heterotopia (PNH), a developmental malformation, is frequently drug-resistant and requires focal therapeutic intervention. Invasive EEG study is usually necessary to delineate the epileptogenic zone, but constructing an accurate hypothesis to define an appropriate electrode implantation scheme and the treatment is challenging. This article reviews recent studies that help understanding the epileptogenicity and potential therapeutic options in PNH.

RECENT FINDINGS

New noninvasive diagnostic and intracerebral EEG analytic tools demonstrated that cortical hyperexcitability and aberrant connectivity (between nodules and cortices and among nodules) are likely mechanisms causing epilepsy in most patients. The deeply seated PNH, if epileptogenic, are ideal target for stereotactic ablative techniques, which offer concomitant ablation of multiple regions with relatively satisfactory seizure outcome. Advance in diagnostic and analytic tools have enhanced our understanding of the complex epileptogenicity in PNH. Development in stereotactic ablative techniques now offers promising therapeutic options for these patients.

Impacts of operating conditions on efficiency of electrokinetically enhanced filtration for de-watering of orange juice and malt extract

The effects of operational factors an on an electrokinetic-enhanced filtration (EKEF) application to dewater orange juice (OJ) and malt extract (ME) was investigated. EKEF improved dewatering of both foodstuffs and resulted in net dewatering efficiencies of 7.4% and 4.9% for OJ and 10.7% and 6.3% for ME after 5.5 h processing under 30 V and 15 V, respectively. Dry matter content was increased by 19.2% and 15.6% for OJ after 5.5 h and 14.8% and 12.8% for ME after 3.5 h under 30 V and 15 V, respectively, compared with 14.9% and 10.3% under the control conditions for OJ and ME, respectively. The EKEF process effectively improved dewatering of high moisture-content foods with positive impacts on process efficiency by increased voltage, pressure, and the pore size of filters. The initial distance between electrodes had a negative impact as the distance increased. EKEF is a useful adjunct to improve high pressure filtration of foodstuffs.

Molecular detection of Streptococcus equi subspecies equi in face flies (Musca autumnalis) collected during a strangles outbreak on a Thoroughbred farm

The objective of this study was to detect Streptococcus equi subspecies equi (S. equi) (Lactobacillales: Streptococcaceae) using quantitative polymerase chain reaction (qPCR) in flies collected from a farm with a documented outbreak of strangles. A total of 1856 face flies [Musca autumnalis (Diptera: Muscidae)] were collected using conventional fly traps. The flies were processed for nucleic acid purification and tested for the presence of S. equi by qPCR. A total of 10/1856 flies (0.54%) tested qPCR-positive for S. equi. The results may implicate the presence of face flies as a risk factor for the transmission of S. equi and highlight the need to institute proper husbandry measures, biosecurity protocols and fly control in order to reduce the potential for infection in at-risk horses.

On the Stability of Reported Pregnancy Intentions from Pregnancy to 1 Year Postnatally: Impact of Choice of Measure, Timing of Assessment, Women's Characteristics and Outcome of Pregnancy

OBJECTIVES

Retrospective, cross-sectional estimates of pregnancy intention, as used in the Demographic Health Survey (DHS), are the global norm. The London Measure of Unplanned Pregnancy (LMUP) is a newer, psychometrically validated measure which may be more reliable. This paper assesses the reliability of the LMUP and the DHS question over the first postnatal year and explores the effects of maternal characteristics or pregnancy outcome on reported pregnancy intention.

METHODS

We compared the test-retest reliability of the LMUP (using the AC coefficient) and DHS question (using the weighted Kappa) over the first postnatal year using data from Malawian women. We investigated the effect of maternal characteristics and pregnancy outcome using t-tests, Chi squared or Fisher's exact tests, and calculated odds ratios to estimate effect size.

RESULTS

The DHS question was associated with a statistically significant decrease in the prevalence of unplanned pregnancies from 1-to-12 months postnatally; the LMUP was not. The LMUP had moderate to substantial reliability (0.51-0.66); the DHS had moderate reliability (0.56-0.58). The LMUP's stability was not related to any of the factors examined; the stability of the DHS varied by marital status (p = 0.033), number of children (p = 0.048) and postnatal depression (p < 0.001). Both underestimated unintended pregnancy postnatally vis-à-vis the LMUP in pregnancy.

CONCLUSIONS FOR PRACTICE

The LMUP is a more reliable measure of pregnancy intention than the DHS in the first postnatal year and does not vary by maternal characteristics or pregnancy outcome. The LMUP should become the gold-standard for measuring pregnancy intention and should be collected in pregnancy or at the first postnatal opportunity.

Spike-related haemodynamic responses overlap with high frequency oscillations in patients with focal epilepsy

Simultaneous scalp EEG/functional MRI measures non-invasively haemodynamic responses to interictal epileptic discharges, which are related to the epileptogenic zone. High frequency oscillations are also an excellent indicator of this zone, but are primarily recorded from intracerebral EEG. We studied the spatial overlap of these two important markers in patients with drug-resistant epilepsy to assess if their combination could help better define the extent of the epileptogenic zone. We included patients who underwent EEG-functional MRI and later intracerebral EEG. Based on intracerebral EEG findings, we separated patients with unifocal seizures from patients with multifocal or unknown onset seizures. Haemodynamic t-maps were coregistered with the intracerebral electrode positions. Each EEG channel was classified as pertaining to one of the following categories: primary haemodynamic cluster (maximum t-value), secondary cluster (t-value > 90% of the primary cluster) or outside the primary and secondary clusters. We marked high frequency oscillations (ripples: 80-250 Hz; fast ripples: 250-500 Hz) during 1 h of slow wave sleep, and compared their rates in each haemodynamic category. After classifying channels as high- or low-rate, the proportion of high-rate channels within the primary or primary plus secondary clusters was compared to the proportion expected by chance. Twenty-five patients, 11 with unifocal and 14 with multifocal/unknown seizure onsets, were studied. We found a significantly higher median high frequency oscillation rate in the primary cluster compared to secondary cluster and outside these two clusters for the unifocal group (P < 0.0001), but not for the multifocal/unknown group. For the unifocal group, the number of high-rate channels within the primary or primary plus secondary clusters was significantly higher than expected by chance. This held only for the high-ripple-rate channels in the multifocal/unknown group. At the patient level, most patients (18/25, or 72%) had at least one high-rate channel within a primary cluster. In patients with unifocal epilepsy, the maximum haemodynamic response (primary cluster) related to scalp interictal discharges overlaps with the tissue generating high frequency oscillations at high rates. If intracranial EEG is warranted, this response should be explored. As a tentative clinical use of the combination of these techniques we propose that higher high frequency oscillation rates inside than outside the maximum response indicates that the patient has indeed a focal epileptogenic zone demarcated by this response, whereas similar rates inside and outside may indicate a widespread epileptogenic zone or an epileptogenic zone not covered by the implantation.

Internodular functional connectivity in heterotopia-related epilepsy

Objective

A vast network involving the nodules and overlying cortices is believed to be responsible for the epileptogenicity in gray matter heterotopia with multiple nodules, which often associated with difficult‐to‐treat epilepsy. We sought to determine if functional magnetic resonance imaging (fMRI) could detect internodular functional connectivity (FC), and if this connectivity reflects an actual synchronized neuronal activity and partakes in epileptogenicity.

Methods

We studied 16 epilepsy patients with multiple heterotopic nodules; eight underwent subsequent intracerebral EEG. We examined the internodular FC using fMRI and its correspondence with internodular synchrony of intracerebral interictal activity. We then compared the spreading speed of ictal activity between connected and unconnected nodules; and the FC among possible combinations of nodule pairs in terms of their involvement at seizure onset.

Results

Seventy nodules were studied: 83% have significant connection to at least one other nodule. Among the 49 pairs studied with intracerebral EEG, (1) synchronized interictal activity is more prevalent in fMRI‐connected pairs (P < 0.05), (2) ictal activity spreads faster between connected pairs (P < 0.0001), and (3) stronger FC was observed between pairs in which both nodules were involved at seizure onset (P < 0.01).

Interpretation

fMRI could reliably and noninvasively detect the FC between heterotopic nodules. These functional connections correspond to the synchrony of interictal epileptic activity between the nodules and to the ability of nodules to generate synchronous seizure onsets or rapid seizure spread. These findings may help in understanding the complexity of the epileptogenic network in multiple heterotopic nodules and better targeting the likely epileptogenic nodules.

In vivo metabotropic glutamate receptor type 5 abnormalities localize the epileptogenic zone in mesial temporal lobe epilepsy

OBJECTIVE

Surgical specimens from patients with mesial temporal lobe epilepsy (MTLE) show abnormalities in tissue concentrations of metabotropic glutamate receptor type 5 (mGluR5). To clarify whether these abnormalities are specific to the epileptogenic zone (EZ), we characterized in vivo whole-brain mGluR5 availability in MTLE patients using positron emission tomography (PET) and [¹¹ C]ABP688, a radioligand that binds specifically to the mGluR5 allosteric site.

METHODS

Thirty-one unilateral MTLE patients and 30 healthy controls underwent [¹¹ C]ABP688 PET. We compared partial volume corrected [¹¹ C]ABP688 nondisplaceable binding potentials (BP_ND ) between groups using region-of-interest and whole-brain voxelwise analyses. [¹⁸ F]Fluorodeoxyglucose (FDG) PET was acquired in 15 patients, for whom we calculated asymmetry indices of [¹¹ C]ABP688 BP_ND and [¹⁸ F]FDG uptake to compare lateralization and localization differences.

RESULTS

[¹¹ C]ABP688 BP_ND was focally reduced in the epileptogenic hippocampal head and amygdala (p < 0.001). Patients with hippocampal atrophy showed more extensive abnormalities, including the ipsilateral temporal neocortex (p = 0.006). [¹¹ C]ABP688 BP_ND showed interhemispheric differences of higher magnitude and discriminated the epileptogenic structures more accurately when compared to [¹⁸ F]FDG uptake, which showed more widespread hypometabolism. Among 23 of 25 operated patients with >1 year of follow-up, 13 were seizure-free (Engel Ia) and showed significantly lower [¹¹ C]ABP688 BP_ND in the ipsilateral entorhinal cortex.

INTERPRETATION

[¹¹ C]ABP688 PET provides a focal biomarker for the EZ in MTLE with higher spatial accuracy compared to [¹⁸ F]FDG PET. Focally reduced mGluR5 availability in the EZ might reflect receptor internalization or conformational changes in response to excessive extracellular glutamate, supporting a potential role for mGluR5 as therapeutic target in human MTLE. Ann Neurol 2019; 1-11 ANN NEUROL 2019;85:218-228.

Combining intraoperative ultrasound brain shift correction and augmented reality visualizations: a pilot study of eight cases

We present our work investigating the feasibility of combining intraoperative ultrasound for brain shift correction and augmented reality (AR) visualization for intraoperative interpretation of patient-specific models in image-guided neurosurgery (IGNS) of brain tumors. We combine two imaging technologies for image-guided brain tumor neurosurgery. Throughout surgical interventions, AR was used to assess different surgical strategies using three-dimensional (3-D) patient-specific models of the patient's cortex, vasculature, and lesion. Ultrasound imaging was acquired intraoperatively, and preoperative images and models were registered to the intraoperative data. The quality and reliability of the AR views were evaluated with both qualitative and quantitative metrics. A pilot study of eight patients demonstrates the feasible combination of these two technologies and their complementary features. In each case, the AR visualizations enabled the surgeon to accurately visualize the anatomy and pathology of interest for an extended period of the intervention. Inaccuracies associated with misregistration, brain shift, and AR were improved in all cases. These results demonstrate the potential of combining ultrasound-based registration with AR to become a useful tool for neurosurgeons to improve intraoperative patient-specific planning by improving the understanding of complex 3-D medical imaging data and prolonging the reliable use of IGNS.

Metabotropic Glutamate Receptor Type 5 (mGluR5) Cortical Abnormalities in Focal Cortical Dysplasia Identified In Vivo With [11C]ABP688 Positron-Emission Tomography (PET) Imaging

Metabotropic glutamate receptor type 5 (mGluR5) abnormalities have been described in tissue resected from epilepsy patients with focal cortical dysplasia (FCD). To determine if these abnormalities could be identified in vivo, we investigated mGluR5 availability in 10 patients with focal epilepsy and an MRI diagnosis of FCD using positron-emission tomography (PET) and the radioligand [¹¹C]ABP688. Partial volume corrected [¹¹C]ABP688 binding potentials (BP_ND) were computed using the cerebellum as a reference region. Each patient was compared to homotopic cortical regions in 33 healthy controls using region-of-interest (ROI) and vertex-wise analyses. Reduced [¹¹C]ABP688 BP_ND in the FCD was seen in 7/10 patients with combined ROI and vertex-wise analyses. Reduced FCD BP_ND was found in 4/5 operated patients (mean follow-up: 63 months; Engel I), of whom surgical specimens revealed FCD type IIb or IIa, with most balloon cells showing negative or weak mGluR5 immunoreactivity as compared to their respective neuropil and normal neurons at the border of resections. [¹¹C]ABP688 PET shows for the first time in vivo evidence of reduced mGluR5 availability in FCD, indicating focal glutamatergic alterations in malformations of cortical development, which cannot be otherwise clearly demonstrated through resected tissue analyses.

Clinical yield of magnetoencephalography distributed source imaging in epilepsy: A comparison with equivalent current dipole method

OBJECTIVE

Source localization of interictal epileptic discharges (IEDs) is clinically useful in the presurgical workup of epilepsy patients. It is usually obtained by equivalent current dipole (ECD) which localizes a point source and is the only inverse solution approved by clinical guidelines. In contrast, magnetic source imaging using distributed methods (dMSI) provides maps of the location and the extent of the generators, but its yield has not been clinically validated. We systematically compared ECD versus dMSI performed using coherent Maximum Entropy on the Mean (cMEM), a method sensitive to the spatial extent of the generators.

METHODS

340 source localizations of IEDs derived from 49 focal epilepsy patients with foci well-defined through intracranial EEG, MRI lesions, and surgery were analyzed. The comparison was based on the assessment of the sublobar concordance with the focus and of the distance between the source and the focus.

RESULTS

dMSI sublobar concordance was significantly higher than ECD (81% vs 69%, P < 0.001), especially for extratemporal lobe sources (dMSI = 84%; ECD = 67%, P < 0.001) and for seizure free patients (dMSI = 83%; ECD = 70%, P < 0.001). The median distance from the focus was 4.88 mm for ECD and 3.44 mm for dMSI (P < 0.001). ECD dipoles were often wrongly localized in deep brain regions.

CONCLUSIONS

dMSI using cMEM exhibited better accuracy. dMSI also offered the advantage of recovering more realistic maps of the generator, which could be exploited for neuronavigation aimed at targeting invasive EEG and surgical resection. Therefore, dMSI may be preferred to ECD in clinical practice. Hum Brain Mapp 39:218-231, 2018. © 2017 Wiley Periodicals, Inc.

A longitudinal study on the acceptance and effects of a therapeutic renal food in pet dogs with IRIS-Stage 1 chronic kidney disease

Currently, nutritional management is recommended when serum creatinine (Cr) exceeds 1.4 mg/dl in dogs with IRIS-Stage 2 chronic kidney disease (CKD) to slow progressive loss of kidney function, reduce clinical and biochemical consequences of CKD, and maintain adequate nutrition. It is unknown if dietary interventions benefit non-azotemic dogs at earlier stages. A prospective 12-month feeding trial was performed in client-owned dogs with IRIS-Stage 1 CKD (n = 36; 20 had persistently dilute urine with urine specific gravity (USG) <1.020 without identifiable non-renal cause; six had persistent proteinuria of renal origin with urine protein creatinine (UPC) ratio >0.5; 10 had both). Ease of transition to therapeutic renal food and effects on renal biomarkers and quality of life attributes were assessed. Dogs were transitioned over 1 week from grocery-branded foods to renal food. At 0, 3, 6, 9, and 12-months a questionnaire to assess owner's perception of their pet's acceptance of renal food and quality of life was completed. Renal biomarkers, including serum Cr, blood urea nitrogen (BUN), and symmetric dimethylarginine (SDMA), and USG and UPC ratio were measured. Of 36 dogs initially enrolled, 35 (97%) dogs were transitioned to therapeutic renal food. Dogs moderately or extremely liked the food 88% of the time, ate most or all of the food 84% of the time, and were moderately or extremely enthusiastic while eating 76% of the time. All renal biomarkers (Cr, BUN, and SDMA) were decreased (p ≤ .05) from baseline at 3-months, and remained decreased from baseline at 12-months in dogs completing the study (n = 20). Proteinuria was reduced in 12 of 16 dogs (p = .045) with proteinuria. Owners reported improvement in overall health and quality of life attributes, and hair and coat quality (all p < .01). In summary, dogs with IRIS-Stage 1 CKD readily transition to renal food. Decreasing serum biomarker concentrations and reduction in proteinuria suggest stabilized kidney function.

Multimodal MRI profiling of focal cortical dysplasia type II

OBJECTIVE

To characterize in vivo MRI signatures of focal cortical dysplasia (FCD) type IIA and type IIB through combined analysis of morphology, intensity, microstructure, and function.

METHODS

We carried out a multimodal 3T MRI profiling of 33 histologically proven FCD type IIA (9) and IIB (24) lesions. A multisurface approach operating on manual consensus labels systematically sampled intracortical and subcortical lesional features. Geodesic distance mapping quantified the same features in the lesion perimeter. Logistic regression assessed the relationship between MRI and histology, while supervised pattern learning was used for individualized subtype prediction.

RESULTS

FCD type IIB was characterized by abnormal morphology, intensity, diffusivity, and function across all surfaces, while type IIA lesions presented only with increased fluid-attenuated inversion recovery signal and reduced diffusion anisotropy close to the gray-white matter interface. Similar to lesional patterns, perilesional anomalies were more marked in type IIB extending up to 16 mm. Structural MRI markers correlated with categorical histologic characteristics. A profile-based classifier predicted FCD subtypes with equal sensitivity of 85%, while maintaining a high specificity of 94% against healthy and disease controls.

CONCLUSIONS

Image processing applied to widely available MRI contrasts has the ability to dissociate FCD subtypes at a mesoscopic level. Integrating in vivo staging of pathologic traits with automated lesion detection is likely to provide an objective definition of lesional boundary and assist emerging approaches, such as minimally invasive thermal ablation, which do not supply tissue specimen.

Brain shift in neuronavigation of brain tumors: A review

PURPOSE

Neuronavigation based on preoperative imaging data is a ubiquitous tool for image guidance in neurosurgery. However, it is rendered unreliable when brain shift invalidates the patient-to-image registration. Many investigators have tried to explain, quantify, and compensate for this phenomenon to allow extended use of neuronavigation systems for the duration of surgery. The purpose of this paper is to present an overview of the work that has been done investigating brain shift.

METHODS

A review of the literature dealing with the explanation, quantification and compensation of brain shift is presented. The review is based on a systematic search using relevant keywords and phrases in PubMed. The review is organized based on a developed taxonomy that classifies brain shift as occurring due to physical, surgical or biological factors.

RESULTS

This paper gives an overview of the work investigating, quantifying, and compensating for brain shift in neuronavigation while describing the successes, setbacks, and additional needs in the field. An analysis of the literature demonstrates a high variability in the methods used to quantify brain shift as well as a wide range in the measured magnitude of the brain shift, depending on the specifics of the intervention. The analysis indicates the need for additional research to be done in quantifying independent effects of brain shift in order for some of the state of the art compensation methods to become useful.

CONCLUSION

This review allows for a thorough understanding of the work investigating brain shift and introduces the needs for future avenues of investigation of the phenomenon.

Rumen Microorganisms Decrease Bioavailability of Inorganic Selenium Supplements

Despite the availability of selenium (Se)-enriched trace mineral supplements, we have observed low Se status in cattle and sheep offered traditional inorganic Se supplements. Reasons for this may include inadequate intake or low bioavailability of inorganic Se sources. The objective of this study was to determine whether rumen microorganisms (RMO) alter the bioavailability of Se sources commonly used in Se supplements. Rumen microorganisms were isolated from ewes (n = 4) and incubated ex vivo with no Se (control), with inorganic Na selenite or Na selenate, or with organic selenomethionine (SeMet). Total Se incorporated into RMO and the amount of elemental Se formed were determined under equivalent conditions. Incorporation of Se from Na selenite, Na selenate, or SeMet into RMO was measured as fold change compared with control (no added Se). Incorporation of Se into microbial mass was greater for SeMet (13.2-fold greater than no-Se control) compared with inorganic Se supplements (P = 0.02); no differences were observed between inorganic Na selenate (3.3-fold greater than no-Se control) and Na selenite (3.5-fold greater than no-Se control; P = 0.97). Formation of non-bioavailable, elemental Se was less for RMO incubated with SeMet compared with inorganic Se sources (P = 0.01); no differences were observed between Na selenate and Na selenite (P = 0.09). The clinical importance of these results is that the oral bioavailability of organic SeMet should be greater compared with inorganic Se sources because of greater RMO incorporation of Se and decreased formation of elemental Se by RMO.

Serum Concentrations of Symmetric Dimethylarginine and Creatinine in Dogs with Naturally Occurring Chronic Kidney Disease

Background

Serum concentrations of symmetric dimethylarginine (SDMA) detected chronic kidney disease (CKD) in cats an average of 17.0 months before serum creatinine (Cr) concentrations increased above the reference interval.

Objectives

To report on the utility of measuring serum SDMA concentrations in dogs for detection of CKD before diagnosis by measurement of serum Cr.

Animals

CKD dogs (n = 19) included those persistently azotemic for ≥3 months (n = 5), dogs that were azotemic at the time of death (n = 4), and nonazotemic dogs (n = 10). CKD dogs were compared with healthy control dogs (n = 20).

Methods

Retrospective study, whereby serum Cr concentrations were determined by enzymatic colorimetry and serum SDMA concentrations were determined by liquid chromatography‐mass spectrometry in dogs with necropsy confirmed CKD.

Results

Serum SDMA increased before serum Cr in 17 of 19 dogs (mean, 9.8 months; range, 2.2–27.0 months). Duration of elevations in serum SDMA concentrations before the dog developed azotemia (N = 1) or before the dog died (N = 1) was not determined. Serum SDMA and Cr concentrations were linearly related (r = 0.84; P < .001). Serum SDMA (r = −0.80) and serum Cr (r = −0.89) concentrations were significantly related to glomerular filtration rate (both P < .001).

Conclusion and Clinical Importance

Using serum SDMA as a biomarker for CKD allows earlier detection of kidney dysfunction in dogs than does measurement of serum Cr. Earlier detection might be desirable for initiating renoprotective interventions that slow progression of kidney disease.

Source localization of the seizure onset zone from ictal EEG/MEG data

INTRODUCTION

Surgical treatment of drug-resistant epilepsy relies on the identification of the seizure onset zone (SOZ) and often requires intracranial EEG (iEEG). We have developed a new approach for non-invasive magnetic and electric source imaging of the SOZ (MSI-SOZ and ESI-SOZ) from ictal magnetoencephalography (MEG) and EEG recordings, using wavelet-based Maximum Entropy on the Mean (wMEM) method. We compared the performance of MSI-SOZ and ESI-SOZ with interictal spike source localization (MSI-spikes and ESI-spikes) and clinical localization of the SOZ (i.e., based on iEEG or lesion topography, denoted as clinical-SOZ).

METHODS

A total of 46 MEG or EEG seizures from 13 patients were analyzed. wMEM was applied around seizure onset, centered on the frequency band showing the strongest power change. Principal component analysis applied to spatiotemporal reconstructed wMEM sources (0.4-1 s around seizure onset) identified the main spatial pattern of ictal oscillations. Qualitative sublobar concordance and quantitative measures of distance and spatial overlaps were estimated to compare MSI/ESI-SOZ with MSI/ESI-Spikes and clinical-SOZ.

RESULTS

MSI/ESI-SOZ were concordant with clinical-SOZ in 81% of seizures (MSI 90%, ESI 64%). MSI-SOZ was more accurate and identified sources closer to the clinical-SOZ (P = 0.012) and to MSI-Spikes (P = 0.040) as compared with ESI-SOZ. MSI/ESI-SOZ and MSI/ESI-Spikes did not differ in terms of concordance and distance from the clinical-SOZ.

CONCLUSIONS

wMEM allows non-invasive localization of the SOZ from ictal MEG and EEG. MSI-SOZ performs better than ESI-SOZ. MSI/ESI-SOZ can provide important additional information to MSI/ESI-Spikes during presurgical evaluation. Hum Brain Mapp 37:2528-2546, 2016. © 2016 Wiley Periodicals, Inc.

Hemodynamic Response to Interictal Epileptiform Discharges Addressed by Personalized EEG-fNIRS Recordings

Objective: We aimed at studying the hemodynamic response (HR) to Interictal Epileptic Discharges (IEDs) using patient-specific and prolonged simultaneous ElectroEncephaloGraphy (EEG) and functional Near InfraRed Spectroscopy (fNIRS) recordings.

Methods: The epileptic generator was localized using Magnetoencephalography source imaging. fNIRS montage was tailored for each patient, using an algorithm to optimize the sensitivity to the epileptic generator. Optodes were glued using collodion to achieve prolonged acquisition with high quality signal. fNIRS data analysis was handled with no a priori constraint on HR time course, averaging fNIRS signals to similar IEDs. Cluster-permutation analysis was performed on 3D reconstructed fNIRS data to identify significant spatio-temporal HR clusters. Standard (GLM with fixed HRF) and cluster-permutation EEG-fMRI analyses were performed for comparison purposes.

Results: fNIRS detected HR to IEDs for 8/9 patients. It mainly consisted oxy-hemoglobin increases (seven patients), followed by oxy-hemoglobin decreases (six patients). HR was lateralized in six patients and lasted from 8.5 to 30 s. Standard EEG-fMRI analysis detected an HR in 4/9 patients (4/9 without enough IEDs, 1/9 unreliable result). The cluster-permutation EEG-fMRI analysis restricted to the region investigated by fNIRS showed additional strong and non-canonical BOLD responses starting earlier than the IEDs and lasting up to 30 s.

Conclusions: (i) EEG-fNIRS is suitable to detect the HR to IEDs and can outperform EEG-fMRI because of prolonged recordings and greater chance to detect IEDs; (ii) cluster-permutation analysis unveils additional HR features underestimated when imposing a canonical HR function (iii) the HR is often bilateral and lasts up to 30 s.

MerTK Is a Functional Regulator of Myelin Phagocytosis by Human Myeloid Cells

Multifocal inflammatory lesions featuring destruction of lipid-rich myelin are pathologic hallmarks of multiple sclerosis. Lesion activity is assessed by the extent and composition of myelin uptake by myeloid cells present in such lesions. In the inflamed CNS, myeloid cells are comprised of brain-resident microglia, an endogenous cell population, and monocyte-derived macrophages, which infiltrate from the systemic compartment. Using microglia isolated from the adult human brain, we demonstrate that myelin phagocytosis is dependent on the polarization state of the cells. Myelin ingestion is significantly enhanced in cells exposed to TGF-β compared with resting basal conditions and markedly reduced in classically activated polarized cells. Transcriptional analysis indicated that TGF-β-treated microglia closely resembled M0 cells. The tyrosine kinase phagocytic receptor MerTK was one of the most upregulated among a select number of differentially expressed genes in TGF-β-treated microglia. In contrast, MerTK and its known ligands, growth arrest-specific 6 and Protein S, were downregulated in classically activated cells. MerTK expression and myelin phagocytosis were higher in CNS-derived microglia than observed in monocyte-derived macrophages, both basally and under all tested polarization conditions. Specific MerTK inhibitors reduced myelin phagocytosis and the resultant anti-inflammatory biased cytokine responses for both cell types. Defining and modulating the mechanisms that regulate myelin phagocytosis has the potential to impact lesion and disease evolution in multiple sclerosis. Relevant effects would include enhancing myelin clearance, increasing anti-inflammatory molecule production by myeloid cells, and thereby permitting subsequent tissue repair.

Intracranial EEG potentials estimated from MEG sources: A new approach to correlate MEG and iEEG data in epilepsy

Detection of epileptic spikes in MagnetoEncephaloGraphy (MEG) requires synchronized neuronal activity over a minimum of 4cm2. We previously validated the Maximum Entropy on the Mean (MEM) as a source localization able to recover the spatial extent of the epileptic spike generators. The purpose of this study was to evaluate quantitatively, using intracranial EEG (iEEG), the spatial extent recovered from MEG sources by estimating iEEG potentials generated by these MEG sources. We evaluated five patients with focal epilepsy who had a pre-operative MEG acquisition and iEEG with MRI-compatible electrodes. Individual MEG epileptic spikes were localized along the cortical surface segmented from a pre-operative MRI, which was co-registered with the MRI obtained with iEEG electrodes in place for identification of iEEG contacts. An iEEG forward model estimated the influence of every dipolar source of the cortical surface on each iEEG contact. This iEEG forward model was applied to MEG sources to estimate iEEG potentials that would have been generated by these sources. MEG-estimated iEEG potentials were compared with measured iEEG potentials using four source localization methods: two variants of MEM and two standard methods equivalent to minimum norm and LORETA estimates. Our results demonstrated an excellent MEG/iEEG correspondence in the presumed focus for four out of five patients. In one patient, the deep generator identified in iEEG could not be localized in MEG. MEG-estimated iEEG potentials is a promising method to evaluate which MEG sources could be retrieved and validated with iEEG data, providing accurate results especially when applied to MEM localizations. Hum Brain Mapp 37:1661-1683, 2016. © 2016 Wiley Periodicals, Inc.

Nutritional Interventions that Slow the Age-Associated Decline in Renal Function in a Canine Geriatric Model for Elderly Humans

OBJECTIVE

To determine the effects of feeding traditional and renal protective foods (RPF) supplemented with functional food bioactives on glomerular filtration rate (GFR), lean body percent (LB%), and selected circulating biomarker and metabolite concentrations in a geriatric dog model.

DESIGN

Randomized block design and cross-sectional study.

SETTING

Hill's Pet Nutrition, Inc. dog colony.

PARTICIPANTS

Eighty-one geriatric dogs (mean age, 10.4; range, 7.9-14.2 years) and 30 mature-adult dogs (mean age, 5.0; range, 3.3-6.9 years).

INTERVENTION

Geriatric dogs were fed one of three foods (n = 27 per group) for 6 months: a traditional RPF (control) that was energy dense and mildly protein-restricted, or control food supplemented with increasing amounts of functional food bioactives: fish oil, lipoic acid, fruits and vegetables, and higher quality protein sources [functional foods one (FF1) and two (FF2)]. Geriatric dogs were compared before and after the feeding trial with mature adult dogs.

MEASUREMENTS

Renal function was assessed by GFR, LB% was determined by dual energy x-ray absorptiometry, and circulating biomarkers and metabolites were measured in blood.

RESULTS

Before the feeding trial, GFR (+28.2%), LB% (+18.6%), and serum total protein (+10.0%) were higher in mature versus healthy geriatric dogs (all P<0.001). Geriatric dogs consuming all three foods increased (P<0.001) GFR over time; group averages ranged from 13.0-16.9%. Dogs fed the highest supplemented level of bioactives (FF2) had lower (P<0.001) symmetric dimethylarginine (SDMA) concentrations (-14.3%). Feeding functional foods did not alter body weight, but increased (P<0.001) serum protein concentration (+6.7%).

CONCLUSION

Supplementation with functional food bioactives can temporarily reverse the age-associated decline in renal function and serum total protein.

New Protocol for Skin Landmark Registration in Image-Guided Neurosurgery: Technical Note

BACKGROUND

Newer versions of the commercial Medtronic StealthStation allow the use of only 8 landmark pairs for patient-to-image registration as opposed to 9 landmarks in older systems. The choice of which landmark pair to drop in these newer systems can have an effect on the quality of the patient-to-image registration.

OBJECTIVE

To investigate 4 landmark registration protocols based on 8 landmark pairs and compare the resulting registration accuracy with a 9-landmark protocol.

METHODS

Four different protocols were tested on both phantoms and patients. Two of the protocols involved using 4 ear landmarks and 4 facial landmarks and the other 2 involved using 3 ear landmarks and 5 facial landmarks. Both the fiducial registration error and target registration error were evaluated for each of the different protocols to determine any difference between them and the 9-landmark protocol.

RESULTS

No difference in fiducial registration error was found between any of the 8-landmark protocols and the 9-landmark protocol. A significant decrease (P &lt; .05) in target registration error was found when using a protocol based on 4 ear landmarks and 4 facial landmarks compared with the other protocols based on 3 ear landmarks.

CONCLUSION

When using 8 landmarks to perform the patient-to-image registration, the protocol using 4 ear landmarks and 4 facial landmarks greatly outperformed the other 8-landmark protocols and 9-landmark protocol, resulting in the lowest target registration error.

Improving recorded volume in mesial temporal lobe by optimizing stereotactic intracranial electrode implantation planning

PURPOSE

Intracranial electrodes are sometimes implanted in patients with refractory epilepsy to identify epileptic foci and propagation. Maximal recording of EEG activity from regions suspected of seizure generation is paramount. However, the location of individual contacts cannot be considered with current manual planning approaches. We propose and validate a procedure for optimizing intracranial electrode implantation planning that maximizes the recording volume, while constraining trajectories to safe paths.

METHODS

Retrospective data from 20 patients with epilepsy that had electrodes implanted in the mesial temporal lobes were studied. Clinical imaging data (CT/A and T1w MRI) were automatically segmented to obtain targets and structures to avoid. These data were used as input to the optimization procedure. Each electrode was modeled to assess risk, while individual contacts were modeled to estimate their recording capability. Ordered lists of trajectories per target were obtained. Global optimization generated the best set of electrodes. The procedure was integrated into a neuronavigation system.

RESULTS

Trajectories planned automatically covered statistically significant larger target volumes than manual plans [Formula: see text]. Median volume coverage was [Formula: see text] for automatic plans versus [Formula: see text] for manual plans. Furthermore, automatic plans remained at statistically significant safer distance to vessels [Formula: see text] and sulci [Formula: see text]. Surgeon's scores of the optimized electrode sets indicated that 95% of the automatic trajectories would be likely considered for use in a clinical setting.

CONCLUSIONS

This study suggests that automatic electrode planning for epilepsy provides safe trajectories and increases the amount of information obtained from the intracranial investigation.