A microphysiological system for parallelized morphological and electrophysiological read-out of 3D neuronal cell culture

Three-dimensional in vitro models in microfluidic systems are promising tools for studying cell biology, with complex models using multiple cell types combined with high resolution imaging. Neuronal models demand electrical readout of the activity of networks of single neurons, yet classical planar microelectrode arrays struggle to capture extracellular action potentials when neural soma are suspended distant from the microelectrodes. This study introduces sophisticated microfluidic microelectrode arrays, specifically tailored for electrophysiology of 3D neuronal cultures. Using multilayer photolithography of permanent epoxy photoresists, we developed devices having 12 independent culture modules in a convenient format. Each module has two adjacent compartments for hydrogel-based 3D cell culture, with tunnels allowing projection of neurites between compartments. Microelectrodes integrated in the tunnels record action potentials as they pass between the compartments. Mesh ceilings separate the compartments from overlying wells, allowing for simple cell seeding and later nutrient, gas and waste exchange and application of test substances. Using these devices, we have demonstrated 3D neuronal culture, including electrophysiological recording and live imaging. This microphysiological platform will enable high-throughput investigation of neuronal networks for investigation of neurological disorders, neural pharmacology and basic neuroscience. Further models could include cocultures representing multiple brain regions or innervation models of other organs.

A flexible implant for acute intrapancreatic electrophysiology

Microelectrode arrays (MEAs) have proven to be a powerful tool to study electrophysiological processes over the last decades with most technology developed for investigation of the heart or brain. Other targets in the field of bioelectronic medicine are the peripheral nervous system and its innervation of various organs. Beyond the heart and nervous systems, the beta cells of the pancreatic islets of Langerhans generate action potentials during the production of insulin. In vitro experiments have demonstrated that their activity is a biomarker for blood glucose levels, suggesting that recording their activity in vivo could support patients suffering from diabetes mellitus with long-term automated read-out of blood glucose concentrations. Here, we present a flexible polymer-based implant having 64 low impedance microelectrodes designed to be implanted to a depth of 10 mm into the pancreas. As a first step, the implant will be used in acute experiments in pigs to explore the electrophysiological processes of the pancreas in vivo. Beyond use in the pancreas, our flexible implant and simple implantation method may also be used in other organs such as the brain.

A mesh microelectrode array for non-invasive electrophysiology within neural organoids

Organoids are emerging in vitro models of human physiology. Neural models require the evaluation of functional activity of single cells and networks, which is commonly measured by microelectrode arrays. The characteristics of organoids clash with existing in vitro or in vivo microelectrode arrays. With inspiration from implantable mesh electronics and growth of organoids on polymer scaffolds, we fabricated suspended hammock-like mesh microelectrode arrays for neural organoids. We have demonstrated the growth of organoids enveloping these meshes and the culture of organoids on meshes for up to one year. Furthermore, we present proof-of-principle recordings of spontaneous electrical activity across the volume of an organoid. Our concept enables a new class of microelectrode arrays for in vitro models of three-dimensional electrically active tissue.

Sorption behaviour and toxicity of an herbicide safener "cyprosulfamide"

Cyprosulfamide is a herbicide safener that works against the injurious effects of herbicides such as isoxaflutole, dicamba, nicosulfuron, tembotrione, thiencarbazone-methyl. However, its sorption behaviour in soils and toxicity to aquatic organisms are yet to be thoroughly examined. This study determined the octanol-water partition coefficient, sorption properties, acute and chronic toxic effects, and potency of cyprosulfamide to the cladoceran water flea (Daphnia magna). The influence of soil properties such as organic carbon content, cation exchange capacity, pH, and field capacity on adsorption and desorption properties were also examined. The Log K_ow (0.55) of cyprosulfamide was less than that of some other safeners, such as benoxacor or furilazole, found in aquatic environments. The sorption of cyprosulfamide to the soil was driven by pH, so sorption decreased with an increase in pH. Other characteristics, such as cation exchange capacity (CEC), organic carbon content, and field capacity, do not directly correlate with the distribution coefficient. Cyprosulfamide generally has a low affinity for soil and is thus mobile and prone to transport to surrounding surface waters. No lethality was observed at the highest concentration (120 mg/L) tested for acute toxicity to D. magna; hence the LC50 will be >120 mg/L. During chronic exposures, cyprosulfamide caused adverse effects at a concentration of 120 mg/L on the number of neonates and brood size. The death rate for the chronic study was a function of concentration and increased with days of exposure. Cyprosulfamide is unlikely to cause lethality to D. magna at relevant environmental concentrations.

The COVID-19 e-lective: using innovation to manage disrupted medical student clinical placements

BACKGROUND

The COVID-19 pandemic changed the way we work, spend, live, and learn. The impact was felt in the health sector where hospitals cancelled elective surgery, put on hold outpatient services, and implemented new social distancing procedures and telehealth systems, to enable hospitals to increase bed capacity. For medical students, these factors meant significant disruption to their clinical placements, remote delivery of their education, cessation of international and interstate placements, complicated by significant travel restrictions and border closures. There were concerns that final year students might be unable to graduate that year due to this lack of clinical exposure.

INNOVATION

As a result of this disruption in late March 2020 we developed an innovative 6 week 'COVID-19 e-lective' rotation, consisting of online modules, virtual clinical tutorials and a COVID project totalling the equivalent of 200 h of work.

RESULTS

An evaluation was undertaken that found it to be remarkably successful in meeting the students' learning needs and alleviating concerns about disrupted placements. It was also conducted during 2021 for all Year 4 students to help expand clinical placement opportunities.

OUTCOMES

This paper describes the e-lective, its innovations, its challenges, and its evaluation findings, for others to learn from.

A flexible protruding microelectrode array for neural interfacing in bioelectronic medicine

Recording neural signals from delicate autonomic nerves is a challenging task that requires the development of a low-invasive neural interface with highly selective, micrometer-sized electrodes. This paper reports on the development of a three-dimensional (3D) protruding thin-film microelectrode array (MEA), which is intended to be used for recording low-amplitude neural signals from pelvic nervous structures by penetrating the nerves transversely to reduce the distance to the axons. Cylindrical gold pillars (Ø 20 or 50 µm, ~60 µm height) were fabricated on a micromachined polyimide substrate in an electroplating process. Their sidewalls were insulated with parylene C, and their tips were optionally modified by wet etching and/or the application of a titanium nitride (TiN) coating. The microelectrodes modified by these combined techniques exhibited low impedances (~7 kΩ at 1 kHz for Ø 50 µm microelectrode with the exposed surface area of ~5000 µm²) and low intrinsic noise levels. Their functionalities were evaluated in an ex vivo pilot study with mouse retinae, in which spontaneous neuronal spikes were recorded with amplitudes of up to 66 µV. This novel process strategy for fabricating flexible, 3D neural interfaces with low-impedance microelectrodes has the potential to selectively record neural signals from not only delicate structures such as retinal cells but also autonomic nerves with improved signal quality to study neural circuits and develop stimulation strategies in bioelectronic medicine, e.g., for the control of vital digestive functions.

The FES Gene at the 15q26 Coronary-Artery-Disease Locus Inhibits Atherosclerosis

BACKGROUND

Genome-wide association studies have discovered a link between genetic variants on human chromosome 15q26.1 and increased coronary artery disease (CAD) susceptibility; however, the underlying pathobiological mechanism is unclear. This genetic locus contains the FES (FES proto-oncogene, tyrosine kinase) gene encoding a cytoplasmic protein-tyrosine kinase involved in the regulation of cell behavior. We investigated the effect of the 15q26.1 variants on FES expression and whether FES plays a role in atherosclerosis.

METHODS AND RESULTS

Analyses of isogenic monocytic cell lines generated by CRISPR (clustered regularly interspaced short palindromic repeats)-mediated genome editing showed that monocytes with an engineered 15q26.1 CAD risk genotype had reduced FES expression. Small-interfering-RNA-mediated knockdown of FES promoted migration of monocytes and vascular smooth muscle cells. A phosphoproteomics analysis showed that FES knockdown altered phosphorylation of a number of proteins known to regulate cell migration. Single-cell RNA-sequencing revealed that in human atherosclerotic plaques, cells that expressed FES were predominately monocytes/macrophages, although several other cell types including smooth muscle cells also expressed FES. There was an association between the 15q26.1 CAD risk genotype and greater numbers of monocytes/macrophage in human atherosclerotic plaques. An animal model study demonstrated that Fes knockout increased atherosclerotic plaque size and within-plaque content of monocytes/macrophages and smooth muscle cells, in apolipoprotein E-deficient mice fed a high fat diet.

CONCLUSIONS

We provide substantial evidence that the CAD risk variants at the 15q26.1 locus reduce FES expression in monocytes and that FES depletion results in larger atherosclerotic plaques with more monocytes/macrophages and smooth muscle cells. This study is the first demonstration that FES plays a protective role against atherosclerosis and suggests that enhancing FES activity could be a potentially novel therapeutic approach for CAD intervention.

Contribution of NOTCH1 genetic variants to bicuspid aortic valve and other congenital lesions

INTRODUCTION

Bicuspid aortic valve (BAV) affects 1% of the general population. NOTCH1 was the first gene associated with BAV. The proportion of familial and sporadic BAV disease attributed to NOTCH1 mutations has not been estimated.

AIM

The aim of our study was to provide an estimate of familial and sporadic BAV disease attributable to NOTCH1 mutations.

METHODS

The population of our study consisted of participants of the University of Leicester Bicuspid aoRtic vAlVe gEnetic research-8 pedigrees with multiple affected family members and 381 sporadic patients. All subjects underwent NOTCH1 sequencing. A systematic literature search was performed in the NCBI PubMed database to identify publications reporting NOTCH1 sequencing in context of congenital heart disease.

RESULTS

NOTCH1 sequencing in 36 subjects from 8 pedigrees identified one variant c.873C>G/p.Tyr291* meeting the American College of Medical Genetics and Genomics criteria for pathogenicity. No pathogenic or likely pathogenic NOTCH1 variants were identified in 381 sporadic patients. Literature review identified 64 relevant publication reporting NOTCH1 sequencing in 528 pedigrees and 9449 sporadic subjects. After excluding families with syndromic disease pathogenic and likely pathogenic NOTCH1 variants were detected in 9/435 (2.1%; 95% CI: 0.7% to 3.4%) of pedigrees and between 0.05% (95% CI: 0.005% to 0.10%) and 0.08% (95% CI: 0.02% to 0.13%) of sporadic patients. Incomplete penetrance of definitely pathogenic NOTCH1 mutations was observed in almost half of reported pedigrees.

CONCLUSIONS

Pathogenic and likely pathogenic NOTCH1 genetic variants explain 2% of familial and <0.1% of sporadic BAV disease and are more likely to associate with tetralogy of Fallot and hypoplastic left heart.

Noise versus Resolution in Optical Chemical Imaging-How Reliable Are Our Measurements?

Optical chemical imaging has established itself as a valuable technique for visualizing analyte distributions in 2D, notably in medical, biological, and environmental applications. In particular for image acquisitions on small scales between few millimeter to the micrometer range, as well as in heterogeneous samples with steep analyte gradients, image resolution is essential. When individual pixels are inspected, however, image noise becomes a metric as relevant as image accuracy and precision, and denoising filters are applied to preserve relevant information. While denoising filters smooth the image noise, they can also lead to a loss of spatial resolution and thus to a loss of relevant information about analyte distributions. To investigate the trade-off between image resolution and noise reduction for information preservation, we studied the impact of random camera noise and noise due to incorrect camera settings on oxygen optodes using the ratiometric imaging technique. First, we estimated the noise amplification across the calibration process using a Monte Carlo simulation for nonlinear fit models. We demonstrated how initially marginal random camera noise results in a significant standard deviation (SD) for oxygen concentration of up to 2.73% air under anoxic conditions, although the measurement was conducted under ideal conditions and over 270 thousand sample pixels were considered during calibration. Second, we studied the effect of the Gaussian denoising filter on a steep oxygen gradient and investigated the impact when the smoothing filter is applied during data processing. Finally, we demonstrated the effectiveness of a Savitzky-Golay filter compared to the well-established Gaussian filter.

A multimodal 3D neuro-microphysiological system with neurite-trapping microelectrodes

Three-dimensional cell technologies as pre-clinical models are emerging tools for mimicking the structural and functional complexity of the nervous system. The accurate exploration of phenotypes in engineered 3D neuronal cultures, however, demands morphological, molecular and especially functional measurements. Particularly crucial is measurement of electrical activity of individual neurons with millisecond resolution. Current techniques rely on customized electrophysiological recording set-ups, characterized by limited throughput and poor integration with other readout modalities. Here we describe a novel approach, using multiwell glass microfluidic microelectrode arrays, allowing non-invasive electrical recording from engineered 3D neural tissues. We demonstrate parallelized studies with reference compounds, calcium imaging and optogenetic stimulation. Additionally, we show how microplate compatibility allows automated handling and high-content analysis of human induced pluripotent stem cell-derived neurons. This microphysiological platform opens up new avenues for high-throughput studies on the functional, morphological and molecular details of neurological diseases and their potential treatment by therapeutic compounds.

Prefertilization Exposure of Rainbow Trout Eggs to Per- and Polyfluoroalkyl Substances to Simulate Accumulation During Oogenesis

Aqueous film-forming foams (AFFFs) are used in firefighting and are sources of per- and polyfluoroalkyl substances (PFAS) to the environment through surface runoff and groundwater contamination at defense and transportation sites. Little is known regarding the toxicity and bioaccumulation of newer AFFF formulations containing novel PFAS. To mimic maternal transfer of PFAS, prefertilization rainbow trout eggs were exposed to three PFAS using novel methodologies. Batches of unfertilized oocytes were exposed for 3 h to 0, 0.01, 0.1, 1, or 10 µg/ml separately to perfluorooctanoic acid, perfluorohexanoic acid, or perfluorooctanesulfonic acid in either coelomic fluid or Cortland's solution. After exposure, the gametes were fertilized and rinsed with dechlorinated water. Egg yolk was aspirated from a subset of fertilized eggs for PFAS quantification. Each PFAS was detected in yolks of eggs exposed to the respective PFAS, and yolk concentrations were directly proportional to concentrations in aqueous media to which they were exposed. Exposure in coelomic fluid or Cortland's solution resulted in similar concentrations of PFAS in egg yolks. Ratios of PFAS concentrations in oocytes to concentrations in exposure media (oocyte fluid ratios) were <0.99 when exposed from 0.01 to 10 µg/ml and <0.45 when exposed from 0.1 to 10 µg/ml for both media and all three PFAS, demonstrating that the water solubility of the chemicals was relatively great. Prefertilization exposure of eggs effectively introduced PFAS into unfertilized egg yolk. This method provided a means of mimicking maternal transfer to evaluate toxicity to developing embryos from an early stage. This method is more rapid and efficient than injection of individual fertilized eggs and avoids trauma from inserting needles into eggs. Environ Toxicol Chem 2021;40:3159-3165. © 2021 SETAC.

Health status of fathead minnow (Pimephales promelas) populations in a municipal wastewater effluent-dominated stream in the Canadian prairies, Wascana Creek, Saskatchewan

Their unique hydrological and climatic conditions render surface water systems in the southern Canadian Prairies at an elevated risk from exposure to contaminants released from municipal wastewater effluents (MWWEs). The aim of this study was to characterize the potential health effects and their underlying molecular mechanisms in populations of fathead minnow (Pimephales promelas; FHM) in Wascana Creek, an effluent dominated stream in Southern Saskatchewan, Canada. Studies were conducted during the spawning season in 2014 and 2015 to assess responses in terms of overall health, reproductive functions, plasma sex steroid hormone levels, and expression of selected genes along the hypothalamus-pituitary-gonadal axis. FHM downstream of the effluent fallout had lower gonadosomatic indices and significantly greater hepatosomatic indices compared to upstream populations. In both male and female FHMs, significantly greater occurrence and severity of gonadal degradation and delayed maturation were observed in downstream fish compared to upstream fish. Downstream males also displayed lower scores of secondary sexual characteristics and a decreasing trend in plasma 11-ketotestosterone levels. Interestingly, no indications of exposure to estrogenic compounds, such as occurrence of testicular oocytes were observed, which was in accordance with the lack of presence of key biomarkers of estrogenic exposure, such as induction of vitellogenin. In general, expression of the majority of transcripts measured in FHMs downstream of the effluent fallout was significantly downregulated, which supports observations of the general deterioration of the health and reproductive status of these fish. Chemical analysis indicated that 10 pharmaceuticals and personal care products (PPCPs) were present at the downstream site, some at sufficiently great concentrations that may present a risk to aquatic organisms. With continuous exposure to a diverse number of stressors including high nutrient and ammonia levels, the presence of a variety of PPCPs and other contaminants, Wascana Creek should be considered as an ecosystem at risk.

High contrast ultrasonic method with multi-spatiotemporal compounding for monitoring catheter-based ultrasound thermal therapy: Development and Ex Vivo Evaluations

OBJECTIVE

Changes in ultrasound backscatter energy (CBE) imaging can monitor thermal therapy. Catheter-based ultrasound (CBUS) can treat deep tumors with precise spatial control of energy deposition and ablation zones, of which CBE estimation can be limited by low contrast and robustness due to small or inconsistent changes in ultrasound data. This study develops a multi-spatiotemporal compounding CBE (MST-CBE) imaging approach for monitoring specific to CBUS thermal therapy.

METHODS

Ex vivo thermal ablations were performed with stereotactic positioning of a 180 directional CBUS applicator, temperature monitoring probes, endorectal US probe, and subsequent lesion sectioning and measurement. Five frames of raw radiofrequency data were acquired throughout in 15s intervals. Using window-by-window estimation methods, absolute and positive components of MST-CBE images at each point were obtained by the compounding ratio of squared envelope data within an increasing spatial size in each short-time window.

RESULTS

Compared with conventional US, Nakagami, and CBE imaging, the detection contrast and robustness quantified by tissue-modification-ratio improved by 37.24.7 (p<0.001), 37.55.2 (p<0.001), and 6.44.0 dB (p<0.05) in the MST-CBE imaging, respectively. Correlation coefficient and bias between cross-sectional dimensions of the ablation zones measured in tissue sections and estimated from MST-CBE were up to 0.91 (p<0.001) and -0.02 mm2, respectively.

CONCLUSION

The MST-CBE approach can monitor the detailed changes within target tissues and effectively characterize the dimensions of the ablation zone during CBUS energy deposition.

SIGNIFICANCE

The MST-CBE approach could be practical for improved accuracy and contrast of monitoring and evaluation for CBUS thermal therapy.

Ractopamine and Other Growth-Promoting Compounds in Beef Cattle Operations: Fate and Transport in Feedlot Pens and Adjacent Environments

The current study represents a comprehensive investigation of the occurrence and fates of trenbolone acetate (TBA) and metabolites 17α-trenbolone (17α-TBOH), 17β-TBOH, and trendione (TBO); melengesterol acetate (MGA); and the less commonly studied β-andrenergic agonist ractopamine (RAC) in two 8 month cattle feeding trials and simulated rainfall runoff experiments. Cattle were administered TBA, MGA, or RAC, and their residues were measured in fresh feces, pen floor material, and simulated rainfall runoff from pen floor surfaces and manure-amended pasture. Concentrations of RAC ranged from 3600 ng g^-1, dry weight (dw), in pen floor to 58 000 ng g^-1 in fresh feces and were, on average, observed at 3-4 orders of magnitude greater than those of TBA and MGA. RAC persisted in pen floors (manure t_1/2 = 18-49 days), and contamination of adjacent sites was observed, likely via transport of windblown particulates. Concentrations in runoff water from pen floors extrapolated to larger-scale commercial feedlots revealed that a single rainfall event could result in mobilization of gram quantities of RAC. This is the first report of RAC occurrence and fate in cattle feedlot environments, and will help understand the risks posed by this chemical and inform appropriate manure-management practices.

Microbubble-Facilitated Ultrasound Catheter Ablation Causes Microvascular Damage and Fibrosis

High-intensity ultrasound (US) ablation produces deeper myocardial lesions than radiofrequency ablation. The presence of intravascular microbubble (MB) contrast agents enhances pulsed-wave US ablation via cavitation-related histotripsy, potentially facilitating ablation in persistently perfused/conducting myocardium. US ablation catheters were developed and tested in the presence of MBs using ex vivo and in vivo models. High-frame-rate videomicroscopy and US imaging of gel phantom models confirmed MB destruction by inertial cavitation. MB-facilitated US ablation in an ex vivo perfused myocardium model generated shallow (2 mm) lesions and, in an in vivo murine hindlimb model, reduced perfusion by 42% with perivascular hemorrhage and inflammation, but no myonecrosis.

The noise and impedance of microelectrodes

OBJECTIVE

While the positive correlation between impedance and noise of microelectrodes is well known, their quantitative relationship is too rarely described. Knowledge of this relationship provides useful information for both microsystems engineers and electrophysiologists.

APPROACH

We discuss the physical basis of noise in recordings with microelectrodes, and compare measurements of impedance spectra to noise of microelectrodes.

MAIN RESULTS

Microelectrode recordings intrinsically include thermal noise, [Formula: see text], with the real component of impedance integrated over the recording frequency band. Impedance spectroscopy allows the quantitative prediction of thermal noise. Optimization of microelectrode noise should also consider the contribution of amplifier noise. These measures enable a quantitative evaluation of microelectrodes' recording quality which is more informative than common but limited comparisons based on the impedance magnitude at 1 kHz.

SIGNIFICANCE

Improved understanding of the origin of microelectrode noise will support efforts to produce smaller yet low noise microelectrodes, capable of recording from higher numbers of neurons. This tutorial is relevant for single microelectrodes, tetrodes, neural probes and microelectrode arrays, whether used in vitro or in vivo.

HepaChip-MP - a twenty-four chamber microplate for a continuously perfused liver coculture model

HepaChip microplate (HepaChip-MP) is a microfluidic platform comprised of 24 independent culture chambers with continuous, unidirectional perfusion. In the HepaChip-MP, an automated dielectrophoresis process selectively assembles viable cells into elongated micro tissues. Freshly isolated primary human hepatocytes (PHH) and primary human liver endothelial cells (HuLEC) were successfully assembled as cocultures aiming to mimic the liver sinusoid. Minimal quantities of primary human cells are required to establish micro tissues in the HepaChip-MP. Metabolic function including induction of CYP enzymes in PHH was successfully measured demonstrating a high degree of metabolic activity of cells in HepaChip-MP cultures and sufficient sensitivity of LC-MS analysis even for the relatively small number of cells per chamber. Further, parallelization realized in HepaChip-MP enabled the acquisition of dose-response toxicity data of diclofenac with a single device. Several unique technical features should enable a widespread application of this in vitro model. We have demonstrated fully automated preparation of cell cultures in HepaChip-MP using a pipetting robot. The tubeless unidirectional perfusion system based on gravity-driven flow can be operated within a standard incubator system. Overall, the system readily integrates in workflows common in cell culture labs. Further research will be directed towards optimization of media composition to further extend culture lifetime and study oxygen gradients and their effect on zonation within the sinusoid-like microorgans. In summary, we have established a novel parallelized and scalable microfluidic in vitro liver model showing hepatocyte function and anticipate future in-depth studies of liver biology and applications in pre-clinical drug development.

Novel loss of function mutation in NOTCH1 in a family with bicuspid aortic valve, ventricular septal defect, thoracic aortic aneurysm, and aortic valve stenosis

Background

Bicuspid aortic valve is the most common congenital valvular heart defect in the general population. BAV is associated with significant morbidity due to valve failure, formation of thoracic aortic aneurysm, and increased risk of infective endocarditis and aortic dissection. Loss of function mutations in NOTCH1 (OMIM 190198) has previously been associated with congenital heart disease involving the aortic valve, left ventricle outflow tract, and mitral valve that segregates in affected pedigrees as an autosomal dominant trait with variable expressivity.

Methods

We performed whole‐exome sequencing in four members of a three‐generational family (three affected and one unaffected subject) with clinical phenotypes including aortic valve stenosis, thoracic aortic aneurysm, and ventricular septal defect.

Results

We identified 16 potentially damaging genetic variants (one stop variant, one splice variant, and 14 missense variants) cosegregating with the phenotype. Of these variants, the nonsense mutation (p.Tyr291*) in NOTCH1 was the most deleterious variant identified and the most likely variant causing the disease.

Conclusion

Inactivating NOTCH1 mutations are a rare cause of familial heart disease involving predominantly left ventricular outflow tract lesions and characterized by the heterogeneity of clinical phenotype.

Low-Impedance 3D PEDOT:PSS Ultramicroelectrodes

The technology for producing microelectrode arrays (MEAs) has been developing since the 1970s and extracellular electrophysiological recordings have become well established in neuroscience, drug screening and cardiology. MEAs allow monitoring of long-term spiking activity of large ensembles of excitable cells noninvasively with high temporal resolution and mapping its spatial features. However, their inability to register subthreshold potentials, such as intrinsic membrane oscillations and synaptic potentials, has inspired a number of laboratories to search for alternatives to bypass the restrictions and/or increase the sensitivity of microelectrodes. In this study, we present the fabrication and in vitro experimental validation of arrays of PEDOT:PSS-coated 3D ultramicroelectrodes, with the best-reported combination of small size and low electrochemical impedance. We observed that this type of microelectrode does not alter neuronal network biological properties, improves the signal quality of extracellular recordings and exhibits higher selectivity toward single unit recordings. With fabrication processes simpler than those reported in the literature for similar electrodes, our technology is a promising tool for study of neuronal networks.

LIPUS far-field exposimetry system for uniform stimulation of tissues in-vitro: development and validation with bovine intervertebral disc cells

Therapeutic Low-intensity Pulsed Ultrasound (LIPUS) has been applied clinically for bone fracture healing and has been shown to stimulate extracellular matrix (ECM) metabolism in numerous soft tissues including intervertebral disc (IVD). In-vitro LIPUS testing systems have been developed and typically include polystyrene cell culture plates (CCP) placed directly on top of the ultrasound transducer in the acoustic near-field (NF). This configuration introduces several undesirable acoustic artifacts, making the establishment of dose-response relationships difficult, and is not relevant for targeting deep tissues such as the IVD, which may require far-field (FF) exposure from low frequency sources. The objective of this study was to design and validate an in-vitro LIPUS system for stimulating ECM synthesis in IVD-cells while mimicking attributes of a deep delivery system by delivering uniform, FF acoustic energy while minimizing reflections and standing waves within target wells, and unwanted temperature elevation within target samples. Acoustic field simulations and hydrophone measurements demonstrated that by directing LIPUS energy at 0.5, 1.0, or 1.5 MHz operating frequency, with an acoustic standoff in the FF (125-350 mm), at 6-well CCP targets including an alginate ring spacer, uniform intensity distributions can be delivered. A custom FF LIPUS system was fabricated and demonstrated reduced acoustic intensity field heterogeneity within CCP-wells by up to 93% compared to common NF configurations. When bovine IVD cells were exposed to LIPUS (1.5 MHz, 200 μs pulse, 1 kHz pulse frequency, and ISPTA = 120 mW cm-2) using the FF system, sample heating was minimal (+0.81 °C) and collagen content was increased by 2.6-fold compared to the control and was equivalent to BMP-7 growth factor treatment. The results of this study demonstrate that FF LIPUS exposure increases collagen content in IVD cells and suggest that LIPUS is a potential noninvasive therapeutic for stimulating repair of tissues deep within the body such as the IVD.

Genome-wide Association Analysis in Humans Links Nucleotide Metabolism to Leukocyte Telomere Length

Leukocyte telomere length (LTL) is a heritable biomarker of genomic aging. In this study, we perform a genome-wide meta-analysis of LTL by pooling densely genotyped and imputed association results across large-scale European-descent studies including up to 78,592 individuals. We identify 49 genomic regions at a false dicovery rate (FDR) < 0.05 threshold and prioritize genes at 31, with five highlighting nucleotide metabolism as an important regulator of LTL. We report six genome-wide significant loci in or near SENP7, MOB1B, CARMIL1, PRRC2A, TERF2, and RFWD3, and our results support recently identified PARP1, POT1, ATM, and MPHOSPH6 loci. Phenome-wide analyses in >350,000 UK Biobank participants suggest that genetically shorter telomere length increases the risk of hypothyroidism and decreases the risk of thyroid cancer, lymphoma, and a range of proliferative conditions. Our results replicate previously reported associations with increased risk of coronary artery disease and lower risk for multiple cancer types. Our findings substantially expand current knowledge on genes that regulate LTL and their impact on human health and disease.

Noninvasive, Targeted Creation of Neuromyelitis Optica Pathology in AQP4-IgG Seropositive Rats by Pulsed Focused Ultrasound

Neuromyelitis optica spectrum disorders (herein called NMO) is an autoimmune disease of the CNS characterized by astrocyte injury, inflammation, and demyelination. In seropositive NMO, immunoglobulin G autoantibodies against aquaporin-4 (AQP4-IgG) cause primary astrocyte injury. A passive transfer model of NMO was developed in which spatially targeted access of AQP4-IgG into the CNS of seropositive rats was accomplished by pulsed focused ultrasound through intact skin. Following intravenous administration of microbubbles, pulsed ultrasound at 0.5 MPa peak acoustic pressure was applied using a 1 MHz transducer with 6-cm focal length. In brain, the transient opening of the blood-brain barrier (BBB) in an approximately prolate ellipsoidal volume of diameter ∼3.5 mm and length ∼44 mm allowed entry of IgG-size molecules for up to 3-6 hours. The ultrasound treatment did not cause erythrocyte extravasation or inflammation. Ultrasound treatment in AQP4-IgG seropositive rats produced localized NMO pathology in brain, with characteristic astrocyte injury, inflammation, and demyelination after 5 days. Pathology was not seen when complement was inhibited, when non-NMO human IgG was administered instead of AQP4-IgG, or in AQP4-IgG seropositive AQP4 knockout rats. NMO pathology was similarly created in cervical spinal cord in seropositive rats. These results establish a noninvasive, spatially targeted model of NMO in rats, and demonstrate that BBB permeabilization, without underlying injury or inflammation, is sufficient to create NMO pathology in AQP4-IgG seropositive rats.

Transition from an MBBS to an MD program – Using innovation and thinking outside the square

This article was migrated. The article was marked as recommended. Background There has been a trend globally to move from a Bachelor of Medicine, Bachelor of Surgery (MBBS) to a Doctor of Medicine (MD) for primary medical education. This shift has seen many Australian universities change to an MD, mostly from graduate entry programs. This paper describes the novel and unique 3+2 model from one Australian university, that enabled undergraduate entry, student flexibility, and a master's exit qualification without increasing time.Methods The method included a curriculum review in 2013 where its problem-based learning curriculum shifted from a seven to a five-semester program; changing the third year to a virtual hospital clinical year using simulation, and introducing in 2016 a new 3+2 curriculum model in the final two years using a 100 point system as a masters level program. ResultsThe MD model was described in the external evaluation as 'novel and innovative', where students can choose from three project options - a research project, or a professional project or an international capstone experience as well as a number of scholarly tasks. The structure is fully integrated with the existing curriculum and assessment process, supported by an innovative technology platform.ConclusionNow in its third year of implementation this innovative model is breaking new ground in the way in which a masters level MD program could be developed, whilst maintaining undergraduate entry.

JCAD, a Gene at the 10p11 Coronary Artery Disease Locus, Regulates Hippo Signaling in Endothelial Cells

Objective- A large number of genetic loci have been associated with risk of coronary artery disease (CAD) through genome-wide association studies, however, for most loci the underlying biological mechanism is unknown. Determining the molecular pathways and cellular processes affected by these loci will provide new insights into CAD pathophysiology and may lead to new therapies. The CAD-associated variants at 10p11.23 fall in JCAD, which encodes an endothelial junction protein, however, its molecular function in endothelial cells is not known. In this study, we characterize the molecular role of JCAD (junctional cadherin 5 associated) in endothelial cells. Approach and Results- We show that JCAD knockdown in endothelial cells affects key phenotypes related to atherosclerosis including proliferation, migration, apoptosis, tube formation, and monocyte binding. We demonstrate that JCAD interacts with LATS2 (large tumor suppressor kinase 2) and negatively regulates Hippo signaling leading to increased activity of YAP (yes-associated protein), the transcriptional effector of the pathway. We also show by double siRNA knockdown that the phenotypes caused by JCAD knockdown require LATS2 and that JCAD is involved in transmission of RhoA-mediated signals into the Hippo pathway. In human tissues, we find that the CAD-associated lead variant, rs2487928, is associated with expression of JCAD in arteries, including atherosclerotic arteries. Gene co-expression analyses across disease-relevant tissues corroborate our phenotypic findings and support the link between JCAD and Hippo signaling. Conclusions- Our results show that JCAD negatively regulates Hippo signaling in endothelial cells and we suggest that JCAD contributes to atherosclerosis by mediating YAP activity and contributing to endothelial dysfunction.

HHIPL1, a Gene at the 14q32 Coronary Artery Disease Locus, Positively Regulates Hedgehog Signaling and Promotes Atherosclerosis

Supplemental Digital Content is available in the text.

Background:

Genome-wide association studies have identified chromosome 14q32 as a locus for coronary artery disease. The disease-associated variants fall in a hitherto uncharacterized gene called HHIPL1 (hedgehog interacting protein-like 1), which encodes a sequence homolog of an antagonist of hedgehog signaling. The function of HHIPL1 and its role in atherosclerosis are unknown.

Methods:

HHIPL1 cellular localization, interaction with sonic hedgehog (SHH), and influence on hedgehog signaling were tested. HHIPL1 expression was measured in coronary artery disease–relevant human cells, and protein localization was assessed in wild-type and Apoe^−/− (apolipoprotein E deficient) mice. Human aortic smooth muscle cell phenotypes and hedgehog signaling were investigated after gene knockdown. Hhipl1^−/− mice were generated and aortic smooth muscle cells collected for phenotypic analysis and assessment of hedgehog signaling activity. Hhipl1^−/− mice were bred onto both the Apoe^−/− and Ldlr^−/− (low-density lipoprotein receptor deficient) knockout strains, and the extent of atherosclerosis was quantified after 12 weeks of high-fat diet. Cellular composition and collagen content of aortic plaques were assessed by immunohistochemistry.

Results:

In vitro analyses revealed that HHIPL1 is a secreted protein that interacts with SHH and increases hedgehog signaling activity. HHIPL1 expression was detected in human smooth muscle cells and in smooth muscle within atherosclerotic plaques of Apoe^−/− mice. The expression of Hhipl1 increased with disease progression in aortic roots of Apoe^−/− mice. Proliferation and migration were reduced in Hhipl1 knockout mouse and HHIPL1 knockdown aortic smooth muscle cells, and hedgehog signaling was decreased in HHIPL1-deficient cells. Hhipl1 knockout caused a reduction of >50% in atherosclerosis burden on both Apoe^−/− and Ldlr^−/− knockout backgrounds, and lesions were characterized by reduced smooth muscle cell content.

Conclusions:

HHIPL1 is a secreted proatherogenic protein that enhances hedgehog signaling and regulates smooth muscle cell proliferation and migration. Inhibition of HHIPL1 protein function might offer a novel therapeutic strategy for coronary artery disease.

Genetic interactions between ABA signalling and the Arg/N-end rule pathway during Arabidopsis seedling establishment

The Arg/N-end rule pathway of ubiquitin-mediated proteolysis has multiple functions throughout plant development, notably in the transition from dormant seed to photoautotrophic seedling. PROTEOLYSIS6 (PRT6), an N-recognin E3 ligase of the Arg/N-end rule regulates the degradation of transcription factor substrates belonging to Group VII of the Ethylene Response Factor superfamily (ERFVIIs). It is not known whether ERFVIIs are associated with all known functions of the Arg/N-end rule, and the downstream pathways influenced by ERFVIIs are not fully defined. Here, we examined the relationship between PRT6 function, ERFVIIs and ABA signalling in Arabidopsis seedling establishment. Physiological analysis of seedlings revealed that N-end rule-regulated stabilisation of three of the five ERFVIIs, RAP2.12, RAP2.2 and RAP2.3, controls sugar sensitivity of seedling establishment and oil body breakdown following germination. ABA signalling components ABA INSENSITIVE (ABI)4 as well as ABI3 and ABI5 were found to enhance ABA sensitivity of germination and sugar sensitivity of establishment in a background containing stabilised ERFVIIs. However, N-end rule regulation of oil bodies was not dependent on canonical ABA signalling. We propose that the N-end rule serves to control multiple aspects of the seed to seedling transition by regulation of ERFVII activity, involving both ABA-dependent and independent signalling pathways.

High perinatal mortality rates persist in Kirakira: The sustainable development goals for health remain out of reach in the provinces of Solomon Islands

AIM

This study aimed to calculate the perinatal mortality rate in Kirakira Hospital, a remote provincial hospital in Solomon Islands, over a 3-year period, from 2014 to 2016.

METHODS

A retrospective audit of the labour ward admission books for the years 2014-2016 was conducted. Patient files of all perinatal deaths and caesarean sections were accessed and reviewed. Stillbirths and early neonatal deaths were classified, and results were compared with the national health statistics of Australia (2014).

RESULTS

Between 2014 and 2016, there were 1311 births and 40 perinatal deaths (mortality rate of 31 per 1000). This is approximately three times the Australian rate of 9.6 deaths per 1000. Of these deaths, 28 were stillbirths, and 12 were neonatal deaths. Detailed information was available for 88% (35/40) of the perinatal deaths. Only 15 caesarean sections (1.1% of deliveries) were performed, compared to a rate of 32.1% of caesarean sections in Australia (2014).

CONCLUSIONS

Kirakira continues to have a very high perinatal mortality rate that has not changed over the last 6 years. The rate is double that reported for Solomon Islands in current World Health Organization data. This discrepancy is likely due to an absence of clinical data outside of the National Referral Hospital in Honiara. This paper identifies clinical indicators that could be targeted to help lower the perinatal mortality rate in this remote and impoverished community.

Endoluminal ultrasound applicators for MR-guided thermal ablation of pancreatic tumors: Preliminary design and evaluation in a porcine pancreas model

PURPOSE

Endoluminal ultrasound may serve as a minimally invasive option for delivering thermal ablation to pancreatic tumors adjacent to the stomach or duodenum. The objective of this study was to explore the basic feasibility of this treatment strategy through the design, characterization, and evaluation of proof-of-concept endoluminal ultrasound applicators capable of placement in the gastrointestinal (GI) lumen for volumetric pancreas ablation under MR guidance.

METHODS

Two variants of the endoluminal applicator, each containing a distinct array of two independently powered transducers (10 × 10 mm 3.2 MHz planar; or 8 × 10 × 20 mm radius of curvature 3.3 MHz curvilinear geometries) at the distal end of a meter long flexible catheter assembly, were designed and fabricated. Transducers and circulatory water flow for acoustic coupling and luminal cooling were contained by a low-profile polyester balloon covering the transducer assembly fixture. Each applicator incorporated miniature spiral MR coils and mechanical features (guiding tips and hinges) to facilitate tracking and insertion through the GI tract under MRI guidance. Acoustic characterization of each device was performed using radiation force balance and hydrophone measurements. Device delivery into the upper GI tract, adjacent to the pancreas, and heating characteristics for treatment of pancreatic tissue were evaluated in MR-guided ex vivo and in vivo porcine experiments. MR guidance was utilized for anatomical target identification, tracking/positioning of the applicator, and MR temperature imaging (MRTI) for PRF-based multislice thermometry, implemented in the real-time RTHawk software environment.

RESULTS

Force balance and hydrophone measurements indicated efficiencies of 48.8% and 47.8% and -3 dB intensity beam-widths of 3.2 and 1.2 mm for the planar and curvilinear transducers, respectively. Ex vivo studies on whole-porcine carcasses revealed capabilities of producing ablative temperature rise (ΔT > 15 °C) contours in pancreatic tissue 4-40 mm long and 4-28 mm wide for the planar transducer applicator (1-13 min sonication duration, ∼4 W/cm(2) applied acoustic intensity). Curvilinear transducers produced more selective heating, with a narrower ΔT > 15 °C contour length and width of up to 1-24 mm and 2-7 mm, respectively (1-7 min sonication duration, ∼4 W/cm(2) applied acoustic intensity). Active tracking of the miniature spiral coils was achieved using a Hadamard encoding tracking sequence, enabling real-time determination of each coil's coordinates and automated prescription of imaging planes for thermometry. In vivo MRTI-guided heating trials in three pigs demonstrated capability of ∼20 °C temperature elevation in pancreatic tissue at 2 cm depths from the applicator, with 5-7 W/cm(2) applied intensity and 6-16 min sonication duration. Dimensions of thermal lesions in the pancreas ranged from 12 to 28 mm, 3 to 10 mm, and 5 to 10 mm in length, width, and depth, respectively, as verified through histological analysis of tissue sections. Multiple-baseline reconstruction and respiratory-gated acquisition were demonstrated to be effective strategies in suppressing motion artifacts for clear evolution of temperature profiles during MRTI in the in vivo studies.

CONCLUSIONS

This study demonstrates the technical feasibility of generating volumetric ablation in pancreatic tissue using endoluminal ultrasound applicators positioned in the stomach lumen. MR guidance facilitates target identification, device tracking/positioning, and treatment monitoring through real-time multislice PRF-based thermometry.

The Coronary Artery Disease-associated Coding Variant in Zinc Finger C3HC-type Containing 1 (ZC3HC1) Affects Cell Cycle Regulation

Genome-wide association studies have to date identified multiple coronary artery disease (CAD)-associated loci; however, for most of these loci the mechanism by which they affect CAD risk is unclear. The CAD-associated locus 7q32.2 is unusual in that the lead variant, rs11556924, is not in strong linkage disequilibrium with any other variant and introduces a coding change in ZC3HC1, which encodes NIPA. In this study, we show that rs11556924 polymorphism is associated with lower regulatory phosphorylation of NIPA in the risk variant, resulting in NIPA with higher activity. Using a genome-editing approach we show that this causes an effective decrease in cyclin-B1 stability in the nucleus, thereby slowing its nuclear accumulation. By perturbing the rate of nuclear cyclin-B1 accumulation, rs11556924 alters the regulation of mitotic progression resulting in an extended mitosis. This study shows that the CAD-associated coding polymorphism in ZC3HC1 alters the dynamics of cell-cycle regulation by NIPA.

The dangers to children from coconut tree trauma, in KiraKira, Solomon Islands: a retrospective clinical audit

Background

Kirakira is small community of 3,000 people and is the capital of Makira-Ulawa province in Solomon Islands. Kirakira is an impoverished community with a small 30 bed hospital with limited resources. This audit was conducted by final year students from Bond University as part of a selective clinical placement.

Methods

The audit included admissions to the hospital from 2011 to 2014. Trauma-related admissions were identified and classified according to the patient’s age, sex, description of injury, mechanism of injury and whether they were transferred to the National Referral Hospital (NRH) in Honiara for further treatment. Injuries due to Coconut tree trauma were classified as being due to falls from the tree, or trauma from either falling branches or falling coconut fruit.

Results

There were 3455 admissions and 23(0.7 %) non-neonatal deaths over the 3 year period. 126(3.6 %) admissions were referred on to the NRH for further treatment. 277 (8.02 %) admissions were trauma-related with 57(21 %) of these referred on to the NRH. 142 (55 %) of the trauma admissions involved children. Coconut Tree trauma was the commonest cause of a traumatic admission to hospital. There were 49 Coconut Tree trauma admissions including 35 from falls, 12 from falling branches and two from falling coconuts. 80 % of Coconut tree trauma involved Males and the median age of those injured was 13. Primary School age children aged 6–14 years were most at risk for Coconut Tree Trauma. 15(31 %) of the Coconut tree trauma admissions were referred to NRH for further treatment.

Conclusions

Coconut Tree Trauma is common in Kirakira and is an important preventable cause of serious injury that particularly affects primary school aged boys in Kirakira, Solomon Islands. A public education campaign that focuses on this at risk age group warning of the dangers of climbing Coconut trees should be considered.

Can Nanofluidic Chemical Release Enable Fast, High Resolution Neurotransmitter-Based Neurostimulation?

Artificial chemical stimulation could provide improvements over electrical neurostimulation. Physiological neurotransmission between neurons relies on the nanoscale release and propagation of specific chemical signals to spatially-localized receptors. Current knowledge of nanoscale fluid dynamics and nanofluidic technology allows us to envision artificial mechanisms to achieve fast, high resolution neurotransmitter release. Substantial technological development is required to reach this goal. Nanofluidic technology—rather than microfluidic—will be necessary; this should come as no surprise given the nanofluidic nature of neurotransmission. This perspective reviews the state of the art of high resolution electrical neuroprostheses and their anticipated limitations. Chemical release rates from nanopores are compared to rates achieved at synapses and with iontophoresis. A review of microfluidic technology justifies the analysis that microfluidic control of chemical release would be insufficient. Novel nanofluidic mechanisms are discussed, and we propose that hydrophobic gating may allow control of chemical release suitable for mimicking neurotransmission. The limited understanding of hydrophobic gating in artificial nanopores and the challenges of fabrication and large-scale integration of nanofluidic components are emphasized. Development of suitable nanofluidic technology will require dedicated, long-term efforts over many years.

Epicardial Catheter Ablation Using High-Intensity Ultrasound: Validation in a Swine Model

BACKGROUND

Epicardial radiofrequency catheter ablation of ventricular tachycardia remains challenging because of the presence of deep myocardial scar and adjacent cardiac structures, such as the coronary arteries, phrenic nerve, and epicardial fat that limit delivery of radiofrequency energy. High-intensity ultrasound (HIU) is an acoustic energy source able to deliver deep lesions through fat, while sparing superficial structures. We developed and tested an epicardial HIU ablation catheter in a closed chest, in vivo swine model.

METHODS AND RESULTS

The HIU catheter is an internally cooled, 14-French, side-facing catheter, integrated with A-mode ultrasound guidance. Swine underwent percutaneous subxyphoid epicardial access and ablation with HIU (n=10 swine) at 15, 20, and 30 W. Compared with irrigated radiofrequency lesions in control swine (n = 5), HIU demonstrated increased lesion depth (HIU 11.6±3.2 mm versus radiofrequency 4.7±1.6 mm; mean±SD) and epicardial sparing (HIU 2.9±2.1 mm versus radiofrequency 0.1±0.2 mm) at all HIU powers, and increased lesion volume at HIU 20 and 30 W (P<0.0001 for all comparisons). HIU ablation over coronary arteries and surrounding epicardial fat resulted in deep lesions with normal angiographic flow. Histological disruption of coronary adventitia, but not media or intima, was noted in 44% of lesions.

CONCLUSIONS

Compared with radiofrequency, HIU ablation in vivo demonstrates significantly deeper and larger lesions with greater epicardial sparing in a dose-dependent manner. Further development of this catheter may lead to a promising alternative to epicardial radiofrequency ablation.

Quantifying temperature-dependent T1 changes in cortical bone using ultrashort echo-time MRI

PURPOSE

To demonstrate the feasibility of using ultrashort echo-time MRI to quantify T1 changes in cortical bone due to heating.

METHODS

Variable flip-angle T1 mapping combined with 3D ultrashort echo-time imaging was used to measure T1 in cortical bone. A calibration experiment was performed to detect T1 changes with temperature in ex vivo cortical bone samples from a bovine femur. Ultrasound heating experiments were performed using an interstitial applicator in ex vivo bovine femur specimens, and heat-induced T1 changes were quantified.

RESULTS

The calibration experiment demonstrated that T1 increases with temperature in cortical bone. We observed a linear relationship between temperature and T1 with a linear coefficient between 0.67 and 0.84 ms/°C over a range of 25-70°C. The ultrasound heating experiments showed increased T1 changes in the heated regions, and the relationship between the temperature changes and T1 changes was similar to that of the calibration.

CONCLUSION

We demonstrated a temperature dependence of T1 in ex vivo cortical bone using a variable flip-angle ultrashort echo-time T1 mapping method.

Development of an endoluminal high-intensity ultrasound applicator for image-guided thermal therapy of pancreatic tumors

An ultrasound applicator for endoluminal thermal therapy of pancreatic tumors has been introduced and evaluated through acoustic/biothermal simulations and ex vivo experimental investigations. Endoluminal therapeutic ultrasound constitutes a minimally invinvasive conformal therapy and is compatible with ultrasound or MR-based image guidance. The applicator would be placed in the stomach or duodenal lumen, and sonication would be performed through the luminal wall into the tumor, with concurrent water cooling of the wall tissue to prevent its thermal injury. A finite-element (FEM) 3D acoustic and biothermal model was implemented for theoretical analysis of the approach. Parametric studies over transducer geometries and frequencies revealed that operating frequencies within 1-3 MHz maximize penetration depth and lesion volume while sparing damage to the luminal wall. Patient-specific FEM models of pancreatic head tumors were generated and used to assess the feasibility of performing endoluminal ultrasound thermal ablation and hyperthermia of pancreatic tumors. Results indicated over 80% of the volume of small tumors (~2 cm diameter) within 35 mm of the duodenum could be safely ablated in under 30 minutes or elevated to hyperthermic temperatures at steady-state. Approximately 60% of a large tumor (~5 cm diameter) model could be safely ablated by considering multiple positions of the applicator along the length of the duodenum to increase coverage. Prototype applicators containing two 3.2 MHz planar transducers were fabricated and evaluated in ex vivo porcine carcass heating experiments under MR temperature imaging (MRTI) guidance. The applicator was positioned in the stomach adjacent to the pancreas, and sonications were performed for 10 min at 5 W/cm² applied intensity. MRTI indicated over 40°C temperature rise in pancreatic tissue with heating penetration extending 3 cm from the luminal wall.

Approaches for modelling interstitial ultrasound ablation of tumours within or adjacent to bone: theoretical and experimental evaluations

PURPOSE

The objectives of this study were to develop numerical models of interstitial ultrasound ablation of tumours within or adjacent to bone, to evaluate model performance through theoretical analysis, and to validate the models and approximations used through comparison to experiments.

METHODS

3D transient biothermal and acoustic finite element models were developed, employing four approximations of 7-MHz ultrasound propagation at bone/soft tissue interfaces. The various approximations considered or excluded reflection, refraction, angle-dependence of transmission coefficients, shear mode conversion, and volumetric heat deposition. Simulations were performed for parametric and comparative studies. Experiments within ex vivo tissues and phantoms were performed to validate the models by comparison to simulations. Temperature measurements were conducted using needle thermocouples or magnetic resonance temperature imaging (MRTI). Finite element models representing heterogeneous tissue geometries were created based on segmented MR images.

RESULTS

High ultrasound absorption at bone/soft tissue interfaces increased the volumes of target tissue that could be ablated. Models using simplified approximations produced temperature profiles closely matching both more comprehensive models and experimental results, with good agreement between 3D calculations and MRTI. The correlation coefficients between simulated and measured temperature profiles in phantoms ranged from 0.852 to 0.967 (p-value < 0.01) for the four models.

CONCLUSIONS

Models using approximations of interstitial ultrasound energy deposition around bone/soft tissue interfaces produced temperature distributions in close agreement with comprehensive simulations and experimental measurements. These models may be applied to accurately predict temperatures produced by interstitial ultrasound ablation of tumours near and within bone, with applications toward treatment planning.

Reconstructing long-term trends in municipal sewage discharge into a small lake in northern Manitoba, Canada

Ross Lake lies within the City of Flin Flon (Manitoba, Canada), a mining community originally formed by the Hudson Bay Mining and Smelting Company (now Hudbay Minerals Inc.) in 1927. At the time of this investigation, a continuous effluent stream from Hudbay Minerals (approximately 80 years) and a discontinuous and unknown amount of raw and minimally treated municipal sewage (>20 years, likely ending in 1951) was discharged into the north basin of the lake. Maximum concentrations of fecal sterols, such as coprostanol and terrestrial phytosterols, such as: β-sitosterol, campesterol, stigmastanol were measured in vertical sections of sediment cores, collected from Ross Lake, in the 15-16-cm section, which likely corresponds to the 1930s. Concentrations of coprostanol increased from <1 μg g(-1) in older sediments, to 252.3 μg g(-1) organic carbon at the peak. Observed changes in concentrations of sterols, in combination with radiometric dating and changes to sediment physicochemical characteristics, support the conclusion that sediments of a depth of less than 17.5-cm depth were deposited during the post-industrial era from approximately 1930 onwards. Ratios of coprostanol to cholesterol>1, peaking at 3.6 are consistent with anecdotal information that municipal sewage was discharged into Ross Lake during the early years of urbanization, prior to changes in treatment of sewage and discharge practices that began in 1951. Finally, historical concentrations of terrestrial phytosterols followed trends similar to those of coprostanol and cholesterol and may possibly be the result of an increase in the flux of terrestrial organic matter into Ross Lake as the result of regional deforestation due to logging and fire.

Liver transplantation in 2013: challenges and controversies

Liver transplantation has changed over the past 50 years from an experimental surgery to a life saving intervention that is the treatment of choice for selected patients with end stage liver disease. Since Starzl attempted the first liver transplant in 1963, the procedure has evolved into one that occurs over 12000 times a year worldwide and has one year survival rates approaching 90% and five year survival rates above 70%. With the success of liver transplantation, challenges and controversies have arisen as well. The aim of this review is to discuss the epidemiology of liver transplantation and highlight those challenges and controversies that exist. Current controversies include appropriate selection of recipients and equitable prioritization for allograft distribution. Future challenges include a decrement in donor quality and availability and an ageing medically complex patient and donor population. Addressing these challenges and controversies will dominate transplantation research for the foreseeable future.

Pharmacokinetics and in vivo potency of soluble epoxide hydrolase inhibitors in cynomolgus monkeys

BACKGROUND AND PURPOSE

Soluble epoxide hydrolase inhibitors (sEHIs) possess anti-inflammatory, antiatherosclerotic, antihypertensive and analgesic properties. The pharmacokinetics (PK) and pharmacodynamics in terms of inhibitory potency of sEHIs were assessed in non-human primates (NHPs). Development of a sEHI for use in NHPs will facilitate investigations on the role of sEH in numerous chronic inflammatory conditions.

EXPERIMENTAL APPROACH

PK parameters of 11 sEHIs in cynomolgus monkeys were determined after oral dosing with 0.3 mg·kg(-1). Their physical properties and inhibitory potency in hepatic cytosol of cynomolgus monkeys were examined. Dose-dependent effects of the two inhibitors 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU) and the related acetyl piperidine derivative, 1-trifluoromethoxyphenyl-3-(1-acetylpiperidin-4-yl) urea (TPAU), on natural blood eicosanoids, were determined.

KEY RESULTS

Among the inhibitors tested, TPPU and two 4-(cyclohexyloxy) benzoic acid urea sEHIs displayed high plasma concentrations (>10 × IC(50)), when dosed orally at 0.3 mg·kg(-1). Although the 4-(cyclohexyloxy) benzoic acid ureas were more potent against monkey sEH than piperidyl ureas (TPAU and TPPU), the latter compounds showed higher plasma concentrations and more drug-like properties. The C(max) increased with dose from 0.3 to 3 mg·kg(-1) for TPPU and from 0.1 to 3 mg·kg(-1) for TPAU, although it was not linear over this range of doses. As an indication of target engagement, ratios of linoleate epoxides to diols increased with TPPU administration.

CONCLUSION AND IMPLICATIONS

Our data indicate that TPPU is suitable for investigating sEH biology and the role of epoxide-containing lipids in modulating inflammatory diseases in NHPs.

Differences and similarities in the practice of medicine between australia and the United States of america: challenges and opportunities for the university of queensland and the ochsner clinical school

BACKGROUND

In 2008, The University of Queensland (UQ) in Australia and the Ochsner Health System (OHS) in Louisiana entered into a partnership that will allow a cohort of United States (US) citizens to enroll in an Australian medical degree program in which students will study for their first 2 years of medical school in Brisbane, Australia, and then complete the final 2 years of clinical education at OHS in New Orleans. The program's goal is to create graduates eligible to practice in Australia, New Zealand, and/or the US.

METHODS

We reviewed the UQ School of Medicine-established Ochsner Clinical School (OCS) and the translation of the UQ clinical curriculum to the US.

RESULTS

The curriculum presented both challenges and opportunities, revealing the similarities and differences in the practice of medicine between Australia and the US. This paper highlights some of them, in terms of the healthcare systems, the health professional workforce, and medical education. For example, the healthcare system and medical school curriculum in Australia have a strong focus on primary care.

CONCLUSIONS

This new model in education may help train more primary care physicians for the US, providing physicians with a unique global perspective to face the future challenges of medical practice.

Suitability of live and fire-killed small-diameter ponderosa and lodgepole pine trees for manufacturing a new structural wood composite

Finding alternative uses for raw material from small-diameter trees is a critical problem throughout the United States. In western states, a lack of markets for small-diameter ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta) can contribute to problems associated with overstocking. To test the feasibility of producing structural composite lumber (SCL) beams from these two western species, we used a new technology called steam-pressed scrim lumber (SPSL) based on scrimming technology developed in Australia. Both standing green and fire-killed ponderosa and lodgepole pine logs were used in an initial test. Fire-killed logs of both species were found to be unsuitable for producing SPSL but green logs were suitable for producing SPSL. For SPSL from green material, ponderosa pine had significantly higher modulus of rupture and work-to-maximum load values than did SPSL from lodgepole pine. Modulus of elasticity was higher for lodgepole pine. The presence of blows was greater with lodgepole pine than with ponderosa. Blows had a negative effect on the mechanical properties of ponderosa pine but no significant effect on the mechanical properties of SPSL from lodgepole pine. An evaluation of non-destructive testing methods showed that X-ray could be used to determine low density areas in parent beams. The use of a sonic compression wave tester for NDE evaluation of modulus of rupture showed some promise with SPSL but requires further research.

Precipitation Fluctuations over Northern Hemisphere Land Areas Since the Mid-19th Century

An extensive array of measurements extending back to the mid-19th century was used to investigate large-scale changes in precipitation over Northern Hemisphere land areas. Significant increases in mid-latitude precipitation and concurrent decreases in low-latitude precipitation have occurred over the last 30 to 40 years. Although these large-scale trends are consistent with general circulation model projections of precipitation changes associated with doubled concentrations of atmospheric carbon dioxide, they should be viewed as defining large-scale natural climatic variability. Additional work to refine regional variations and address potential network inhomogeneitics is needed. This study attempts to show secular precipitation fluctuations over hemispheric and continental-scale areas of the Northern Hemisphere.

In situ hybridization to detect spatial gene expression in medaka

A whole-animal tissue section in situ hybridization (ISH) system with radio-labeled probes was developed to detect differential gene expression among tissues of the small, oviparous teleost fish, Japanese medaka (Oryzias latipes). Because of its tissue- and gender-specific expression, gonadal aromatase (CYP19a) was selected as a model gene to demonstrate the potential of the system. The ISH system was validated with a 7d exposure to the model aromatase inhibitor, fadrozole. Fadrozole did not affect the magnitude of gene expression in testes, but significantly up-regulated CYP19a gene expression in ovaries. These results were confirmed with quantitative real-time-polymerase chain reaction (RT-PCR). Histological evaluation revealed that females exposed to 100microg/L fadrozole lacked mature oocytes. Male gonadal morphology was normal in all treatments. The ISH method developed in this study allowed tissue-specific resolution of gene expression in a whole animal model, as well as the ability to analyze cellular morphological detail in the same organism.