Low-voltage fast seizures in humans begin with increased interneuron firing

OBJECTIVE

Intracellular recordings from cells in entorhinal cortex tissue slices show that low-voltage fast (LVF) onset seizures are generated by inhibitory events. Here, we determined whether increased firing of interneurons occurs at the onset of spontaneous mesial-temporal LVF seizures recorded in patients.

METHODS

The seizure onset zone (SOZ) was identified using visual inspection of the intracranial electroencephalogram. We used wavelet clustering and temporal autocorrelations to characterize changes in single-unit activity during the onset of LVF seizures recorded from microelectrodes in mesial-temporal structures. Action potentials generated by principal neurons and interneurons (ie, putative excitatory and inhibitory neurons) were distinguished using waveform morphology and K-means clustering.

RESULTS

From a total of 200 implanted microelectrodes in 9 patients during 13 seizures, we isolated 202 single units; 140 (69.3%) of these units were located in the SOZ, and 40 (28.57%) of them were classified as inhibitory. The waveforms of both excitatory and inhibitory units remained stable during the LVF epoch (p > > 0.05). In the mesial-temporal SOZ, inhibitory interneurons increased their firing rate during LVF seizure onset (p < 0.01). Excitatory neuron firing rates peaked 10 seconds after the inhibitory neurons (p < 0.01). During LVF spread to the contralateral mesial temporal lobe, an increase in inhibitory neuron firing rate was also observed (p < 0.01).

INTERPRETATION

Our results suggest that seizure generation and spread during spontaneous mesial-temporal LVF onset events in humans may result from increased inhibitory neuron firing that spawns a subsequent increase in excitatory neuron firing and seizure evolution. Ann Neurol 2018;84:588-600.

Enhanced co-registration methods to improve intracranial electrode contact localization

Background

Electrode contact locations are important when planning tailored brain surgeries to identify pathological tissue targeted for resection and conversely avoid eloquent tissue. Current methods employ trained experts to use neuroimaging scans that are manually co-registered and localize contacts within ~2 mm. Yet, the state of the art is limited by either the expertise needed for each type of intracranial electrode or the inter-modality co-registration which increases error, reducing accuracy. Patients often have a variety of strips, grids and depths implanted; therefore, it is cumbersome and time-consuming to apply separate localization methods for each type of electrode, requiring expertise across different approaches.

New method

To overcome these limitations, a computational method was developed by separately registering an implant magnetic resonance image (MRI) and implant computed tomography image (CT) to the pre-implant MRI, then calculating an iterative closest point transformation using the contact locations extracted from the signal voids as ground truth.

Results

The implant MRI is robustly co-registered to the pre-implant MRI with a boundary-based registration algorithm. By extracting and utilizing ‘signal voids’ (the metal induced artifacts from the implant MRI) as electrode fiducials, the novel method is an all-in-one approach for all types of intracranial electrodes while eliminating inter-modality co-registration errors.

Comparison with existing methods

The distance between each electrode centroid and the brain's surface was measured, for the proposed method as well as the state of the art method using two available software packages, SPM 12 and FSL 4.1. The method presented here achieves the smallest distances to the brain's surface for all strip and grid type electrodes, i.e. contacts designed to rest directly on the brain surface.

Conclusion

We use one of the largest reported sample sizes in localization studies to validate this novel method for localizing different kinds of intracranial electrodes including grids, strips and depth electrodes.

•

Co-registration between intramodal pre- and implant images allows for accurate localization of all subdural electrode types.

•

Iterative closest point (ICP) assisted grid electrode localization is comparable to existing implant MRI based methods.

•

ICP is a novel, semi-automated method to localize grid, strip and depth electrodes with state-of-the-art accuracy

Increased neuronal synchrony prepares mesial temporal networks for seizures of neocortical origin

OBJECTIVE

To gain understanding of the neuronal mechanisms underlying regional seizure spread, the impact of regional synchrony between seizure focus and downstream networks on neuronal activity during the transition to seizure in those downstream networks was assessed.

METHODS

Seven patients undergoing diagnostic intracranial electroencephalographic studies for surgical resection of epileptogenic regions were implanted with subdural clinical electrodes into the cortex (site of seizure initiation) and mesial temporal lobe (MTL) structures (downstream) as well as microwires into MTL. Neural activity was recorded (24/7) in parallel with the clinical intracranial electroencephalogram recordings for the duration of the patient's diagnostic stay. Changes in (1) regional synchrony (ie, coherence) between the presumptive neocortical seizure focus and MTL, (2) local synchrony between MTL neurons and their local field potential, and (3) neuronal firing rates within MTL in the time leading up to seizure were examined to study the mechanisms underlying seizure spread.

RESULTS

In seizures of neocortical origin, an increase in regional synchrony preceded the spread of seizures into MTL (predominantly hippocampal). Within frequencies similar to those of regional synchrony, MTL networks showed an increase in unit-field coherence and a decrease in neuronal firing rate, specifically for inhibitory interneuron populations but not pyramidal cell populations.

SIGNIFICANCE

These results suggest a mechanism of spreading seizures whereby the seizure focus first synchronizes local field potentials in downstream networks to the seizure activity. This change in local field coherence modifies the activity of interneuron populations in these downstream networks, which leads to the attenuation of interneuronal firing rate, effectively shutting down local interneuron populations prior to the spread of seizure. Therefore, regional synchrony may influence the failure of downstream interneurons to prevent the spread of the seizures during generalization.

Management of obesity in adult Asian Indians

The prevalence of obesity in India is increasing and ranges from 8% to 38% in rural and 13% to 50% in urban areas. Obesity is a risk factor for development of type 2 diabetes mellitus (T2DM), hypertension, dyslipidemia, coronary heart disease and many cancers. In Asian Indians excess abdominal and hepatic fat is associated with increased risk for T2DM and cardiovascular disease. There is higher risk for development of obesity related non-communicable diseases at lower body mass index levels, compared to white Caucasians. Despite being a commonly encountered medical problem, obesity poses challenges in treatment. Many Indian physicians find themselves to be lacking time and expertise to prepare an appropriate obesity management plan and patients experience continuous weight gain over time despite being under regular medical supervision. In this article, we outline approaches to obesity management in ‘real life mode’ and in context to Asian Indian patients.

Prevalence and trends of metabolic syndrome among adults in the asia-pacific region: a systematic review

Background

The Asia-Pacific region is home to nearly half of the world’s population. The region has seen a recent rapid increase in the prevalence of obesity, type-2 diabetes and cardiovascular disease. The present systematic review summarizes the recent prevalence and trends of Metabolic Syndrome (MetS) among adults in countries of the Asia-Pacific Region.

Methods

Data on MetS in Asia-Pacific countries were obtained using a stepwise process by searching the online Medline database using MeSH terms ‘Metabolic Syndrome X’ and ‘Epidemiology/EP’. For the purpose of describing prevalence data for the individual countries, studies that were most recent, nationally representative or with the largest sample size were included. When evaluating secular trends in prevalence in a country we only considered studies that evaluated the temporal change in prevalence between similar populations, prospective studies based on the same population or National surveys conducted during different time periods.

Results

This literature search yielded a total of 757 articles, and five additional article were identified by screening of reference lists. From this total, 18 studies were eligible to be included in the final analysis. Of the 51 Asia-Pacific countries (WHO) we only located data for 15. There was wide between country variation in prevalence of MetS. A national survey from Philippines conducted in 2003 revealed the lowest reported prevalence of 11.9% according to NCEP ATP III criteria. In contrast, the highest recorded prevalence in the region (49.0%) came from a study conducted in urban Pakistan (Karachchi, 2004). Most studies reported a higher prevalence of MetS in females and urban residents. Data on secular trends were available for China, South Korea and Taiwan. An increase in the prevalence of MetS was observed in all three countries.

Conclusion

Despite differences in methodology, diagnostic criteria and age of subjects studied, the Asia-Pacific region is facing a significant epidemic of MetS. In most countries nearly 1/5th of the adult population or more were affected by MetS with a secular increase in prevalence. Strategies aimed at primary prevention are required to ameliorate a further increase in the epidemic and for the reduction of the morbidity and mortality associated with MetS.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-017-4041-1) contains supplementary material, which is available to authorized users.

Obesity, Diabetes and Cardiovascular Diseases in India: Public Health Challenges

Non-communicable diseases (NCDs; including coronary heart disease and type 2 diabetes) are rapidly increasing in India causing nearly 5.8 million deaths per year. Primary reasons for rise in NCDs in India are nutrition and lifestyle transitions. Further, presence of higher body fat, abdominal fat, liver and pancreatic fat and lower lean mass than whites, contribute to heightened metabolic and cardiovascular risk in Asian Indians. Importantly, conversion from pre-diabetes to diabetes occurs more rapidly, and reversion to normal glucose regulation with appropriate lifestyle measures is more difficult in Asian Indians than white population. Huge number of patients with diabetes and with complications increase morbidity, mortality and pose substantial economic burden. It is difficult, though not impossible, to decrease pace of rapidly expanding juggernaut of NCDs in India. Only concerted efforts from multiple stakeholders, consistently sincere efforts and intensely focused attention from health officialdom and clear political will may help counter this increasingly difficult challenge. Finally, all prevention and management approaches should be cost-effective, pragmatic, and focused on children and underprivileged populations.

Vascular Cells in Blood Vessel Wall Development and Disease

The vessel wall is composed of distinct cellular layers, yet communication among individual cells within and between layers results in a dynamic and versatile structure. The morphogenesis of the normal vascular wall involves a highly regulated process of cell proliferation, migration, and differentiation. The use of modern developmental biological and genetic approaches has markedly enriched our understanding of the molecular and cellular mechanisms underlying these developmental events. Additionally, the application of similar approaches to study diverse vascular diseases has resulted in paradigm-shifting insights into pathogenesis. Further investigations into the biology of vascular cells in development and disease promise to have major ramifications on therapeutic strategies to combat pathologies of the vasculature.

Neonatal isolated ACTH deficiency (IAD): a potentially life-threatening but treatable cause of neonatal cholestasis

Isolated ACTH deficiency (IAD) is a rare cause of neonatal cholestasis and hypoglycaemia. This diagnosis has a 20% mortality potential if unrecognised. We describe a case of an infant presenting with cholestatic jaundice and hypoglycaemia. The patient had laboratory findings suggestive of IAD, which was later confirmed with molecular genetic testing. One of the mutations this patient had is a new finding. The patient was started on glucocorticoid replacement therapy after which his bilirubin and glucose levels normalised.

Phonon-Assisted Resonant Tunneling of Electrons in Graphene-Boron Nitride Transistors

We observe a series of sharp resonant features in the differential conductance of graphene-hexagonal boron nitride-graphene tunnel transistors over a wide range of bias voltages between 10 and 200 mV. We attribute them to electron tunneling assisted by the emission of phonons of well-defined energy. The bias voltages at which they occur are insensitive to the applied gate voltage and hence independent of the carrier densities in the graphene electrodes, so plasmonic effects can be ruled out. The phonon energies corresponding to the resonances are compared with the lattice dispersion curves of graphene-boron nitride heterostructures and are close to peaks in the single phonon density of states.

Vegetation indices mapping for Bhiwani district of Haryana (India) through LANDSAT-7ETM+ and remote sensing techniques

This study describes the VIs Vegetation Condition Index in term of vegetation health of wheat crop; with help of LANDSAT-7ETM+ data based NDVI and LAI for Bhiwani District of Haryana states (India) and gave the spatial development pattern of wheat crop in year 2005 over the study area of India. NDVI is found to vary from 0.3 to 0.8. In northern and southern parts of study area NDVI varied from 0.6 to 0.7 but in western part of Bhiwani showed NDVI 0.2 to 0.4 due to fertility of soil and well canal destitution. LAI showed variation from 1 to 6 accordingto the health of crop as the same manner of NDVI because LAI VI is NDVI dependent only change the manner of representation of vegetation health, due to this fact relation curve (r2=) between NDVI and LAI of four different growing date of sates are in successively increasing order 0.509, 0.563, 0.577 and 0.719. The study reveals that VIs can be mapped with LANDSAT-7ETM+ through remote sensing, which can be further used for many studies like crop yield or estimating evaptranspiration on regional basis for water management because satellite observations provide better spatial and temporal coverage, the VIs based system will provide efficient tools for monitoring health of crop for improvement of agricultural planning. VIs based monitoring will serve as a prototype in the other parts of the world where ground observations are limited or not available.

Quantification of dislocation nucleation stress in TiN through high-resolution in situ indentation experiments and first principles calculations

Through in situ indentation of TiN in a high-resolution transmission electron microscope, the nucleation of full as well as partial dislocations has been observed from {001} and {111} surfaces, respectively. The critical elastic strains associated with the nucleation of the dislocations were analyzed from the recorded atomic displacements, and the nucleation stresses corresponding to the measured critical strains were computed using density functional theory. The resolved shear stress was estimated to be 13.8 GPa for the partial dislocation 1/6 <110> {111} and 6.7 GPa for the full dislocation ½ <110> {110}. Such an approach of quantifying nucleation stresses for defects via in situ high-resolution experiment coupled with density functional theory calculation may be applied to other unit processes.

Experimental Quantification of Resolved Shear Stresses for Dislocation Motion in TiN

Experimental quantification of the critical resolved shear stress (CRSS) at the level of unit dislocation glide is still a challenge. By using in situ nanoindentation in a high-resolution transmission electron microscope and strain analysis of the acquired structural images, the CRSS for the motion of individual dislocations on {110}⟨011⟩ slip system and glide dislocation re-emission from a tilt grain boundary in TiN are quantified. This work offers an approach to measure the local stresses associated with dislocation motion in high-strength materials.

Decadal changes in the land use/land cover and shoreline along the coastal districts of southern Gujarat, India

The coastal zone along the districts of Surat, Navsari, and Valsad in southern Gujarat, India, is reported to be facing serious environmental challenges in the form of shoreline erosion, wetland loss, and man-made encroachments. This study assesses the decadal land use/ land cover (LULC) changes in these three districts for the years 1990, 2001, and 2014 using satellite datasets of Landsat TM, ETM, and OLI. The LULC changes are identified by using band ratios as a pre-classification step, followed by implementation of hybrid classification (a combination of supervised and unsupervised classification). An accuracy assessment is carried out for each dataset, and the overall accuracy ranges from 90 to 95%. It is observed that the spatial extents of aquaculture, urban built-up, and barren classes have appreciated over time, whereas the coverage of mudflats has depreciated due to rapid urbanization. The changes in the shoreline of these districts have also been analyzed for the same years, and significant changes are found in the form of shoreline erosion. The LULC maps prepared as well as the shoreline change analysis done for this study area will enable the local decision makers to adopt better land-use planning and shoreline protection measures, which will further aid in sustainable future developments in this region.

Polymerization behavior of hydrophilic-rich phase of dentin adhesive

The 2-fold objectives of this study were 1) to understand whether model hydrophobic- and hydrophilic-rich phase mimics of dentin adhesive polymerize similarly and 2) to determine which factor, the dimethacrylate component, bisphenol A glycerolate dimethacrylate (BisGMA) or photoinitiator concentration, has greater influence on the polymerization of the hydrophilic-rich phase mimic. Current dentin adhesives are sensitive to moisture, as evidenced by nanoleakage in the hybrid layer and phase separation into hydrophobic- and hydrophilic-rich phases. Phase separation leads to limited availability of the cross-linkable dimethacrylate monomer and hydrophobic photoinitiators within the hydrophilic-rich phase. Model hydrophobic-rich phase was prepared as a single-phase solution by adding maximum wt% deuterium oxide (D2O) to HEMA/BisGMA neat resins containing 45 wt% 2-hydroxyethyl methacrylate (HEMA). Mimics of the hydrophilic-rich phase were prepared similarly but using HEMA/BisGMA neat resins containing 95, 99, 99.5, and 100 wt% HEMA. The hydrophilic-rich mimics were prepared with standard or reduced photoinitiator content. The photoinitiator systems were camphorquinone (CQ)/ethyl 4-(dimethylamino)benzoate (EDMAB) with or without [3-(3, 4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-2-hydroxypropyl]trimethylammonium chloride (QTX). The polymerization kinetics was monitored using a Fourier transform infrared spectrophotometer with a time-resolved collection mode. The hydrophobic-rich phase exhibited a significantly higher polymerization rate compared with the hydrophilic-rich phase. Postpolymerization resulting in the secondary rate maxima was observed for the hydrophilic-rich mimic. The hydrophilic-rich mimics with standard photoinitiator concentration but varying cross-linker (BisGMA) content showed postpolymerization and a substantial degree of conversion. In contrast, the corresponding formulations with reduced photoinitiator concentrations exhibited lower polymerization and inhibition/delay of postpolymerization within 2 h. Under conditions relevant to the wet, oral environment, photoinitiator content plays an important role in the polymerization of the hydrophilic-rich phase mimic. Since the hydrophilic-rich phase is primarily water and monomethacrylate monomer (e.g., HEMA as determined previously), substantial polymerization is important to limit the potential toxic response from HEMA leaching into the surrounding tissues.