Neutrophil extracellular traps activate hepatic stellate cells and monocytes via NLRP3 sensing in alcohol-induced acceleration of MASH fibrosis

OBJECTIVE

Alcohol use in metabolic dysfunction-associated steatohepatitis (MASH) is associated with an increased risk of fibrosis and liver-related death. Here, we aimed to identify a mechanism through which repeated alcohol binges exacerbate liver injury in a high fat-cholesterol-sugar diet (MASH diet)-induced model of MASH.

DESIGN

C57BL/6 mice received either chow or the MASH diet for 3 months with or without weekly alcohol binges. Neutrophil infiltration, neutrophil extracellular traps (NETs) and fibrosis were evaluated.

RESULTS

We found that alcohol binges in MASH increase liver injury and fibrosis. Liver transcriptomic profiling revealed differential expression of genes involved in extracellular matrix reorganisation, neutrophil activation and inflammation compared with alcohol or the MASH diet alone. Alcohol binges specifically increased NET formation in MASH livers in mice, and NETs were also increased in human livers with MASH plus alcohol use. We discovered that cell-free NETs are sensed via Nod-like receptor protein 3 (NLRP3). Furthermore, we show that cell-free NETs in vitro induce a profibrotic phenotype in hepatic stellate cells (HSCs) and proinflammatory monocytes. In vivo, neutrophil depletion using anti-Ly6G antibody or NET disruption with deoxyribonuclease treatment abrogated monocyte and HSC activation and ameliorated liver damage and fibrosis. In vivo, inhibition of NLRP3 using MCC950 or NLRP3 deficiency attenuated NET formation, liver injury and fibrosis in MASH plus alcohol diet-fed mice (graphical abstract).

CONCLUSION

Alcohol binges promote liver fibrosis via NET-induced activation of HSCs and monocytes in MASH. Our study highlights the potential of inhibition of NETs and/or NLRP3, as novel therapeutic strategies to combat the profibrotic effects of alcohol in MASH.

Comparison of predictive validity of two Autism Spectrum Disorder Rat Models: Behavioural investigations

The valproic acid model has been shown to reproduce ASD-like behaviours observed in patients and is now widely validated for construct, face, and predictivity as ASD model in rat. The literature agrees on using a single exposition to 500mg/kg of VPA at gestational day 12 to induce ASD phenotype with the intraperitoneal route being the most commonly used. However, some studies validated this model with repeated exposure by using oral route. The way of administration may be of great importance in the induction of the ASD phenotype and a comparison is greatly required. We compared two ASD models, one induced by a unique IP injection of 500mg/kg of body weight at GD12 and the other one by repeated PO administration of 500mg/kg of body weight/day between GD11 and GD13. The behavioural phenotypes of the offspring were assessed for the core signs of ASD (impaired social behaviour, stereotypical/repetitive behaviours, sensory/communication deficits) as well as anxiety as comorbidity, at developmental and juvenile stages in both sexes. The VPA IP model induced a more literature-compliant ASD phenotype than the PO one. These results confirmed that the mode of administration as well as the window of VPA exposure are key factors in the ASD-induction phenotype. Interestingly, the effects of VPA administration were similar at the developmental stage between both sexes and then tended to differ later in life.

Pharmacokinetic characterisation of a valproate Autism Spectrum Disorder rat model in a context of co-exposure to α-Hexabromocyclododecane

Assessing the role of α-hexabromocyclododecane α-HBCDD as a factor of susceptibility for Autism Spectrum disorders by using valproic acid-exposed rat model (VPA) required characterizing VPA pharmacokinetic in the context of α-HBCDD-co-exposure in non-pregnant and pregnant rats. The animals were exposed to α-HBCDD by gavage (100 ng/kg/day) for 12 days. This was followed by a single intraperitoneal dose of VPA (500 mg/kg) or a daily oral dose of VPA (500 mg/kg) for 3 days. Exposure to α-HBCDD did not affect the pharmacokinetics of VPA in pregnant or non-pregnant rats. Surprisingly, VPA administration altered the pharmacokinetics of α-HBCDD. VPA also triggered higher foetal toxicity and lethality with the PO than IP route. α-HBCDD did not aggravate the embryotoxicity observed with VPA, regardless of the route of exposure. Based on this evidence, a single administration of 500 mg/kg IP is the most suitable VPA model to investigate α-HBCDD co-exposure.

Altered ethanol metabolism and increased oxidative stress enhance alcohol-associated liver injury in farnesoid X receptor-deficient mice

BACKGROUND & AIMS

Pharmacological activation of farnesoid X receptor (FXR) ameliorates liver injury, steatosis and inflammation in mouse models of alcoholic liver disease (ALD), but the underlying mechanisms of the protective effect of FXR against ALD remain unclear.

METHODS

To investigate the role of FXR in ALD, we used the NIAAA model of chronic plus binge ethanol feeding in FXR-deficient knockout (FXR KO) mice.

RESULTS

Ethanol-mediated liver injury and steatosis were increased in FXR KO mice, while both WT and FXR KO mice consumed the same amount of alcohol. Ethanol feeding induced liver inflammation and neutrophil infiltration that were further increased in FXR KO mice. In addition, collagen accumulation and expression of profibrotic genes were markedly elevated in the liver of alcohol-fed FXR KO compared to wild-type mice, suggesting that ethanol-induced liver fibrosis is enhanced in the absence of FXR. Surprisingly, FXR KO mice showed reduced blood alcohol levels post-binge, while CYP2E1 and ALDH1A1 were upregulated compared to WT mice, suggesting that alcohol metabolism is altered in FXR KO mice. Notably, exacerbated liver injury in FXR KO mice was associated with increased oxidative stress. ALDH1A1 activity was upregulated in FXR-deficient mouse primary hepatocytes, contributing to reactive oxygen species (ROS) generation, in vitro. Finally, using an ALDH1A1 inhibitor, we showed that ALDH1A1 activity is a key contributor to alcohol-induced ROS generation in FXR-deficient hepatocytes, in vitro.

CONCLUSION

ALD pathogenesis in FXR KO mice correlates with altered ethanol metabolism and increased oxidative stress, providing new insights into the protective function of FXR in ALD.

Granulocyte colony-stimulating factor attenuates liver damage by M2 macrophage polarization and hepatocyte proliferation in alcoholic hepatitis in mice

Massive inflammation and liver failure are main contributors to the high mortality in alcohol-associated hepatitis (AH). In recent clinical trials, granulocyte colony-stimulating factor (G-CSF) therapy improved liver function and survival in patients with AH. However, the mechanisms of G-CSF-mediated beneficial effects in AH remain elusive. In this study, we evaluated effects of in vivo G-CSF administration, using a mouse model of AH. G-CSF treatment significantly reduced liver damage in alcohol-fed mice even though it increased the numbers of liver-infiltrating immune cells, including neutrophils and inflammatory monocytes. Moreover, G-CSF promoted macrophage polarization toward an M2-like phenotype and increased hepatocyte proliferation, which was indicated by an increased Ki67-positive signal colocalized with hepatocyte nuclear factor 4 alpha (HNF-4α) and cyclin D1 expression in hepatocytes. We found that G-CSF increased G-CSF receptor expression and resulted in reduced levels of phosphorylated β-catenin in hepatocytes. In the presence of an additional pathogen-associated molecule, lipopolysaccharide (LPS), which is significantly increased in the circulation and liver of patients with AH, the G-CSF-induced hepatoprotective effects were abolished in alcohol-fed mice. We still observed increased Ki67-positive signals in alcohol-fed mice following G-CSF treatment; however, Ki67 and HNF-4α did not colocalize in LPS-challenged mice. Conclusion: G-CSF treatment increases immune cell populations, particularly neutrophil counts, and promotes M2-like macrophage differentiation in the liver. More importantly, G-CSF treatment reduces alcohol-induced liver injury and promotes hepatocyte proliferation in alcohol-fed mice. These data provide new insights into the understanding of mechanisms mediated by G-CSF and its therapeutic effects in AH.

Abstract 1870: A simple and quantitative immunoassay for evaluation of receptor occupancy and antibody binding capacity in fixed cells or tissue samples for immune-directing antibody development

Receptor occupancy (RO) assays are used to quantify the binding of therapeutic antibodies to their targets on the cell surface. This method can be used to in early drug discovery to determine the antibody binding capacity (ABC) of drug candidates to cells in culture to hone the desired drug characteristics during candidate screening or lead optimization. This method can also be used in xenografts or patient tissues to create pharmacodynamic (PD) data that directs the efficacy hypothesis and biomarker selection for clinical trials. The current approaches use flow cytometry on fresh specimens, which introduces many technical and logistical challenges and does not retain spatial information about the tissue. Here we introduce a new, simple method which can be performed on Formalin Fixed, Paraffin Embedded (FFPE) cells or tissues. This approach eliminates the challenges of flow cytometry methods, provides the type of quantitative data needed, and maintains the tissue contexture to study the effects of immune-directing antibodies in patient tissue samples. We describe a method for developing a standard curve to determine antibody binding capacity (ABC) using our Quanticell ™ fluorescent nanoparticle technology. We demonstrate this in a typical bispecific antibody use case, where both the immune-directing (CD3) and targeting (Her2) arms of the bispecific are modulated to create the desired efficacy characteristics. We demonstrate the establishment of a standard calibration curve for Her2 (BT474/Her2+) and CD3 (Jurkat/CD3+) in cells with titrated amounts of anti-Her2 and anti-CD3 antibodies which target the extracellular domain necessary for these studies. We also show how the same Quanticell assay can be used in clinical tissue, to evaluate the localization of the drug targets and immune cells within the tissue context of human patient samples necessary to understand how pharmacodynamic properties of the drug can modulate immune contexture changes. The Quanticell™ method is a simple immunohistochemistry (IHC) based method which allows extremely sensitive detection of therapeutic antibodies bound on FFPE fixed cells or tissue, which thus does not require the use of flow cytometry in fresh tissues, allowing simple use from early discovery through clinical research studies. Importantly, the Quanticell™ method is capable of detecting a very large and linear dynamic range of analyte concentration to allow full quantification of ABC for RO studies. Critically, the Quanticell™ method retains the tissue context, allowing for simultaneous and spatial evaluation of multiple analytes such as the target of the antibody and the immune contexture. This method allows for a consistent method for RO studies that can be applied to early discovery, translational, and clinical research to optimize drug efficacy.

Citation Format: Atsuro Tatsumi, Keisuke Morichika, Caroline Morel, Omid Ghasemi, Hiroyuki Yokota, Joseph S. Krueger. A simple and quantitative immunoassay for evaluation of receptor occupancy and antibody binding capacity in fixed cells or tissue samples for immune-directing antibody development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1870.

Chronic alcohol-induced neuroinflammation involves CCR2/5-dependent peripheral macrophage infiltration and microglia alterations

Background

Chronic alcohol consumption is associated with neuroinflammation, neuronal damage, and behavioral alterations including addiction. Alcohol-induced neuroinflammation is characterized by increased expression of proinflammatory cytokines (including TNFα, IL-1β, and CCL2) and microglial activation. We hypothesized chronic alcohol consumption results in peripheral immune cell infiltration to the CNS. Since chemotaxis through the CCL2-CCR2 signaling axis is critical for macrophage recruitment peripherally and centrally, we further hypothesized that blockade of CCL2 signaling using the dual CCR2/5 inhibitor cenicriviroc (CVC) would prevent alcohol-induced CNS infiltration of peripheral macrophages and alter the neuroinflammatory state in the brain after chronic alcohol consumption.

Methods

C57BL/6J female mice were fed an isocaloric or 5% (v/v) ethanol Lieber DeCarli diet for 6 weeks. Some mice received daily injections of CVC. Microglia and infiltrating macrophages were characterized and quantified by flow cytometry and visualized using CX3CR1^eGFP/+ CCR2^RFP/+ reporter mice. The effect of ethanol and CVC treatment on the expression of inflammatory genes was evaluated in various regions of the brain, using a Nanostring nCounter inflammation panel. Microglia activation was analyzed by immunofluorescence. CVC-treated and untreated mice were presented with the two-bottle choice test.

Results

Chronic alcohol consumption induced microglia activation and peripheral macrophage infiltration in the CNS, particularly in the hippocampus. Treatment with CVC abrogated ethanol-induced recruitment of peripheral macrophages and partially reversed microglia activation. Furthermore, the expression of proinflammatory markers was upregulated by chronic alcohol consumption in various regions of the brain, including the cortex, hippocampus, and cerebellum. Inhibition of CCR2/5 decreased alcohol-mediated expression of inflammatory markers. Finally, microglia function was impaired by chronic alcohol consumption and restored by CVC treatment. CVC treatment did not change the ethanol consumption or preference of mice in the two-bottle choice test.

Conclusions

Together, our data establish that chronic alcohol consumption promotes the recruitment of peripheral macrophages into the CNS and microglia alterations through the CCR2/5 axis. Therefore, further exploration of the CCR2/5 axis as a modulator of neuroinflammation may offer a potential therapeutic approach for the treatment of alcohol-associated neuroinflammation.

MAPSSIC, a communicating MAPS-based intracerebral positrons probe for deep brain imaging in awake and freely-moving rats

Radioisotope imaging is a powerful tool to understand the biological mechanisms in-vivo, especially in the brain of small animals, providing a significant model to study the human brain.

In this context, we have developed and built a pixelated intracerebral positron probe to be embedded on awake and freely moving small animals, typically rats. This pixelated probe will represent a key instrument for neuroscientists to study neural mechanisms and correlate them to behavioral experiments.

We describe in this paper the simulations carried out to design the intracerebral sensor, its architecture, and the detection of positrons in a volume with a couple of sensors assembled back-to-back. We also depict the architecture of the wireless acquisition system. Finally, we present the first measurements performed in real-time by this miniaturized probe with sealed radioactive sources and a 18F solution.

OS7.6 Socioeconomic burden and associations with quality of life in meningioma patients

BACKGROUND

Socioeconomics affect the outcome of neurological patients, but the socioeconomic burden of brain tumors has not been studied in detail.

PATIENTS AND METHODS

This survey study in a clinically well-annotated cohort of meningioma patients was designed to explore socioeconomic status parameters at diagnosis and one year thereafter. The survey comprised level of education, profession, employment status, subjective work ability, monthly income and the EPICES social deprivation score. Quality of life (QoL) and symptom burden were queried utilizing the EORTC-QLQ-C30/BN20 and MDASI-BT. A multivariate binary regression model was applied to explore associations of socioeconomics with QoL.

RESULTS

Completed surveys were obtained from 249 of 410 patients (61%) who were invited to participate. The level of education was an apprenticeship or higher in 214 patients (86%). One year after diagnosis, there was a 20% decline in the fraction of employed patients and a more than twofold increase in unemployment and disability (p<0.001). There was a decrease in monthly income among patients with a baseline income below national average (p=0.008). On multivariate analyses, there was an association of inferior QoL with pre-operative unemployment or retirement (OR 2.43, 95% CI 1.02–5.88), whereas a subjective work ability of >70% was associated with better QoL (OR 0.37, 95% CI 0.15–0.92).

CONCLUSION

Socioeconomics assessments should be incorporated in prospective neuro-oncology clinical trials. A more detailed knowledge of the effects of socioeconomics on patient outcome will aid in identifying patients at risk for deterioration and allow to implement improved preventive and supportive strategies.

Multidisciplinary team meeting and EUSOMA quality indicators in breast cancer care: A French regional multicenter study

INTRODUCTION

We evaluate breast cancer (BC) pathway at a regional level including public, private and university institutions. We assessed the quality of multidisciplinary team meetings (MTM) and compliance with a panel of European high-quality indicators (EUSOMA QIs).

METHODS

We conducted a retrospective multicenter (n = 20) study in the largest health care region in France. Between January and April 2015, we included all patients discussed at an MTM after a diagnosis of BC (n = 619). We analyzed quality of MTM by assessing the quorum, the reliability of data transcription and the exhaustivity of pre-therapeutic MTM. We then analyzed the compliance with a selected panel of 16 EUSOMA QIs.

RESULTS

During MTM discussion, data were more than 95% consistent with medical records for 9/11 items. Pre-operative tumor histology (90.6%) and post-operative resection margins (84.3%) were the least concordant between medical records and MTM. Minimum standards as defined by EUSOMA were reached for 11/16 QIs, but not reached for pathology reports in non-invasive BC (78.2%), proportion of exclusive sentinel lymph node biopsies in patients with clinically negative axilla (85.2%), performing adjuvant chemotherapy (76.6%), and proportion of patients discussed in pre-therapeutic and post-operative MTM (63.5%).

CONCLUSIONS

In this multicentric study evaluating the quality of BC care with a representative sample of institutions, compliance with EUSOMA indicators was satisfactory for all type of institutions. However, too few patients were discussed in pre-therapeutic MTM (especially in non-university hospitals 43.7% [39.4-48.1]) versus 88.7% for others [82.2-95.1]) and data transcription was likely responsible for up to 15% of discordance.

Impact of post-procedural glycemic variability on cardiovascular morbidity and mortality after transcatheter aortic valve implantation: a post hoc cohort analysis

Background

Glycemic variability is associated with worse outcomes after cardiac surgery, but the prognosis value of early glycemic variability after transcatheter aortic valve implantation is not known. This study was therefore designed to analyze the prognosis significance of post-procedural glycemic variability within 30 days after transcatheter aortic valve implantation.

Methods

A post hoc analysis of patients from our center included in the FRANCE and FRANCE-2 registries was conducted. Post-procedural glycemic variability was assessed by calculating the mean daily δ blood glucose during the first 2 days after transcatheter aortic valve implantation. Major complications within 30 days were death, stroke, myocardial infarction, acute heart failure, and life-threatening cardiac arrhythmias.

Results

We analyzed 160 patients (age (median [interquartile] = 84 [80–88] years; diabetes mellitus (n) = 41 (26%) patients; logistic Euroscore = 20 [12–32]). The median value of mean daily δ blood glucose was 4.3 mmol l⁻¹. The rate of major complications within 30 days after procedure among patients with the lowest quartile of glycemic variability was 12%, increasing from 12 to 26%, and 39% in the second, third, and fourth quartiles, respectively. In multivariate analysis, glycemic variability was independently associated with an increased risk of major complications within 30 days after the procedure (odds ratio [95% CI] = 1.83 [1.19–2.83]; p = 0.006).

Conclusions

This study showed that post-procedural glycemic variability was associated with an increased risk of major complications within 30 days after transcatheter aortic valve implantation.

Trial registration Clinical trial registration number https://www.clinicaltrials.gov/; identifier: NCT02726958; date: April 4th, 2016

Nicotinic receptors mediate stress-nicotine detrimental interplay via dopamine cells' activity

Epidemiological studies report strong association between mood disorders and tobacco addiction. This high comorbidity requires adequate treatment but the underlying mechanisms are unknown. We demonstrate that nicotine exposure, independent of drug withdrawal effects, increases stress sensitivity, a major risk factor in mood disorders. Nicotine and stress concur to induce long-lasting cellular adaptations within the dopamine (DA) system. This interplay is underpinned by marked remodeling of nicotinic systems, causing increased ventral tegmental area (VTA) DA neurons' activity and stress-related behaviors, such as social aversion. Blocking β2 or α7 nicotinic acetylcholine receptors (nAChRs) prevents, respectively, the development and the expression of social stress-induced neuroadaptations; conversely, facilitating α7 nAChRs activation specifically in the VTA promotes stress-induced cellular and behavioral maladaptations. Our work unravels a complex nicotine-stress bidirectional interplay and identifies α7 nAChRs as a promising therapeutic target for stress-related psychiatric disorders.

A Protein Scaffold Coordinates SRC-Mediated JNK Activation in Response to Metabolic Stress

Obesity is a major risk factor for the development of metabolic syndrome and type 2 diabetes. How obesity contributes to metabolic syndrome is unclear. Free fatty acid (FFA) activation of a non-receptor tyrosine kinase (SRC)-dependent cJun NH₂-terminal kinase (JNK) signaling pathway is implicated in this process. However, the mechanism that mediates SRC-dependent JNK activation is unclear. Here, we identify a role for the scaffold protein JIP1 in SRC-dependent JNK activation. SRC phosphorylation of JIP1 creates phosphotyrosine interaction motifs that bind the SH2 domains of SRC and the guanine nucleotide exchange factor VAV. These interactions are required for SRC-induced activation of VAV and the subsequent engagement of a JIP1-tethered JNK signaling module. The JIP1 scaffold protein, therefore, plays a dual role in FFA signaling by coordinating upstream SRC functions together with downstream effector signaling by the JNK pathway.

Temporal Imaging CeBr3 Compton Camera: A New Concept for Nuclear Decommissioning and Nuclear Waste Management

During nuclear decommissioning or waste management operations, a camera that could make an image of the contamination field and identify and quantify the contaminants would be a great progress. Compton cameras have been proposed, but their limited efficiency for high energy gamma rays and their cost have severely limited their application. Our objective is to promote a Compton camera for the energy range (200 keV – 2 MeV) that uses fast scintillating crystals and a new concept for locating scintillation event: Temporal Imaging.

Temporal Imaging uses monolithic plates of fast scintillators and measures photons time of arrival distribution in order to locate each gamma ray with a high precision in space (X,Y,Z), time (T) and energy (E). This provides a native estimation of the depth of interaction (Z) of every detected gamma ray. This also allows a time correction for the propagation time of scintillation photons inside the crystal, therefore resulting in excellent time resolution. The high temporal resolution of the system makes it possible to veto quite efficiently background by using narrow time coincidence (< 300 ps). It is also possible to reconstruct the direction of propagation of the photons inside the detector using timing constraints. The sensitivity of our system is better than 1 nSv/h in a 60 s acquisition with a 22Na source.

The project TEMPORAL is funded by the ANDRA/PAI under the grant No. RTSCNADAA160019.

Excitatory transmission onto AgRP neurons is regulated by cJun NH2-terminal kinase 3 in response to metabolic stress

The cJun NH₂-terminal kinase (JNK) signaling pathway is implicated in the response to metabolic stress. Indeed, it is established that the ubiquitously expressed JNK1 and JNK2 isoforms regulate energy expenditure and insulin resistance. However, the role of the neuron-specific isoform JNK3 is unclear. Here we demonstrate that JNK3 deficiency causes hyperphagia selectively in high fat diet (HFD)-fed mice. JNK3 deficiency in neurons that express the leptin receptor LEPRb was sufficient to cause HFD-dependent hyperphagia. Studies of sub-groups of leptin-responsive neurons demonstrated that JNK3 deficiency in AgRP neurons, but not POMC neurons, was sufficient to cause the hyperphagic response. These effects of JNK3 deficiency were associated with enhanced excitatory signaling by AgRP neurons in HFD-fed mice. JNK3 therefore provides a mechanism that contributes to homeostatic regulation of energy balance in response to metabolic stress.

DOI:http://dx.doi.org/10.7554/eLife.10031.001

Consuming the right amount of food is important for health. Eating too little for a long time causes damage to organs, and overeating can cause harm as well, in the form of conditions such as obesity and type 2 diabetes. Several signaling molecules and brain regions are linked to controlling food consumption and ensuring the body receives the correct amount of nutrients to fuel its activities.

Previous studies have found that two proteins called JNK1 and JNK2, which are found in most tissues of the body, can reduce how much energy cells use. This can trigger insulin resistance and fat accumulation, and so suggests that blocking the activity of these proteins may help to treat type 2 diabetes and obesity. However, the role of another JNK protein – JNK3, which is mostly found in the brain – was not known.

Now, Vernia, Morel et al. have investigated the role of JNK3 in metabolism. It was found that JNK3 reduced the amount of food consumed by mice provided with a cafeteria (high fat) diet. Mice that lacked JNK3 ate far more food and gained more weight on a high fat diet than normal mice. However, JNK3 played no role in food consumption when mice were fed a standard chow diet. Treating normal mice with leptin – an appetite-suppressing hormone – caused them to lose weight, but did not affect mice that lacked JNK3.

Examining the brains of the mice revealed that in normal mice, JNK3 in a specific sub-population of neurons decreases the production of proteins that promote eating. However, the proteins continued to be produced in mice that lacked JNK3, encouraging overeating.

Overall, the results suggest that blocking the activity of all the JNK proteins will not help treat obesity and diabetes as shutting down JNK3 could encourage overeating. Therefore, future investigation into treatments for these conditions should focus on drugs that specifically target JNK1 and JNK2, and not JNK3.

DOI:http://dx.doi.org/10.7554/eLife.10031.002

K-edge imaging with the XPAD3 hybrid pixel detector, direct comparison of CdTe and Si sensors

We investigate the improvement from the use of high-Z CdTe sensors for pre-clinical K-edge imaging with the hybrid pixel detectors XPAD3. We compare XPAD3 chips bump bonded to Si or CdTe sensors in identical experimental conditions. Image performance for narrow energy bin acquisitions and contrast-to-noise ratios of K-edge images are presented and compared. CdTe sensors achieve signal-to-noise ratios at least three times higher than Si sensors within narrow energy bins, thanks to their much higher detection efficiency. Nevertheless Si sensors provide better contrast-to-noise ratios in K-edge imaging when working at equivalent counting statistics, due to their better estimation of the attenuation coefficient of the contrast agent. Results are compared to simulated data in the case of the XPAD3/Si detector. Good agreement is observed when including charge sharing between pixels, which have a strong impact on contrast-to-noise ratios in K-edge images.

A wireless beta-microprobe based on pixelated silicon for in vivo brain studies in freely moving rats

The investigation of neurophysiological mechanisms underlying the functional specificity of brain regions requires the development of technologies that are well adjusted to in vivo studies in small animals. An exciting challenge remains the combination of brain imaging and behavioural studies, which associates molecular processes of neuronal communications to their related actions. A pixelated intracerebral probe (PIXSIC) presents a novel strategy using a submillimetric probe for beta(+) radiotracer detection based on a pixelated silicon diode that can be stereotaxically implanted in the brain region of interest. This fully autonomous detection system permits time-resolved high sensitivity measurements of radiotracers with additional imaging features in freely moving rats. An application-specific integrated circuit (ASIC) allows for parallel signal processing of each pixel and enables the wireless operation. All components of the detector were tested and characterized. The beta(+) sensitivity of the system was determined with the probe dipped into radiotracer solutions. Monte Carlo simulations served to validate the experimental values and assess the contribution of gamma noise. Preliminary implantation tests on anaesthetized rats proved PIXSIC's functionality in brain tissue. High spatial resolution allows for the visualization of radiotracer concentration in different brain regions with high temporal resolution.

JNK expression by macrophages promotes obesity-induced insulin resistance and inflammation

The cJun NH(2)-terminal kinase (JNK) signaling pathway contributes to inflammation and plays a key role in the metabolic response to obesity, including insulin resistance. Macrophages are implicated in this process. To test the role of JNK, we established mice with selective JNK deficiency in macrophages. We report that feeding a high-fat diet to control and JNK-deficient mice caused similar obesity, but only mice with JNK-deficient macrophages remained insulin-sensitive. The protection of mice with macrophage-specific JNK deficiency against insulin resistance was associated with reduced tissue infiltration by macrophages. Immunophenotyping demonstrated that JNK was required for pro-inflammatory macrophage polarization. These studies demonstrate that JNK in macrophages is required for the establishment of obesity-induced insulin resistance and inflammation.

GATE V6: a major enhancement of the GATE simulation platform enabling modelling of CT and radiotherapy

GATE (Geant4 Application for Emission Tomography) is a Monte Carlo simulation platform developed by the OpenGATE collaboration since 2001 and first publicly released in 2004. Dedicated to the modelling of planar scintigraphy, single photon emission computed tomography (SPECT) and positron emission tomography (PET) acquisitions, this platform is widely used to assist PET and SPECT research. A recent extension of this platform, released by the OpenGATE collaboration as GATE V6, now also enables modelling of x-ray computed tomography and radiation therapy experiments. This paper presents an overview of the main additions and improvements implemented in GATE since the publication of the initial GATE paper (Jan et al 2004 Phys. Med. Biol. 49 4543-61). This includes new models available in GATE to simulate optical and hadronic processes, novelties in modelling tracer, organ or detector motion, new options for speeding up GATE simulations, examples illustrating the use of GATE V6 in radiotherapy applications and CT simulations, and preliminary results regarding the validation of GATE V6 for radiation therapy applications. Upon completion of extensive validation studies, GATE is expected to become a valuable tool for simulations involving both radiotherapy and imaging.

Role of the hypothalamic-pituitary-thyroid axis in metabolic regulation by JNK1

The cJun N-terminal kinase 1 (JNK1) is implicated in diet-induced obesity. Indeed, germline ablation of the murine Jnk1 gene prevents diet-induced obesity. Here we demonstrate that selective deficiency of JNK1 in the murine nervous system is sufficient to suppress diet-induced obesity. The failure to increase body mass is mediated, in part, by increased energy expenditure that is associated with activation of the hypothalamic-pituitary-thyroid axis. Disruption of thyroid hormone function prevents the effects of nervous system JNK1 deficiency on body mass. These data demonstrate that the hypothalamic-pituitary-thyroid axis represents an important target of metabolic signaling by JNK1.

Imaging performance of the hybrid pixel detectors XPAD3-S

Hybrid pixel detectors, originally developed for tracking particles in high-energy physics experiments, have recently been used in material sciences and macromolecular crystallography. Their capability to count single photons and to apply a threshold on the photon energy suggests that they could be optimal digital x-ray detectors in low energy beams such as for small animal computed tomography (CT). To investigate this issue, we have studied the imaging performance of photon counting hybrid pixel detectors based on the XPAD3-S chip. Two detectors are considered, connected either to a Si or to a CdTe sensor, the latter being of interest for its higher efficiency. Both a standard 'International Electrotechnical Commission' (IEC) mammography beam and a beam used for mouse CT results published in the literature are employed. The detector stability, linearity and noise are investigated as a function of the dose for several imaging exposures ( approximately 0.1-400 microGy). The perfect linearity of both detectors is confirmed, but an increase in internal noise for counting statistics higher than approximately 5000 photons has been found, corresponding to exposures above approximately 110 microGy and approximately 50 microGy for the Si and CdTe sensors, respectively. The noise power spectrum (NPS), the modulation transfer function (MTF) and the detective quantum efficiency (DQE) are then measured for two energy threshold configurations (5 keV and 18 keV) and three doses ( approximately 3, 30 and 300 microGy), in order to obtain a complete estimation of the detector performances. In general, the CdTe sensor shows a clear superiority with a maximal DQE(0) of approximately 1, thanks to its high efficiency ( approximately 100%). The DQE of the Si sensor is more dependent on the radiation quality, due to the energy dependence of its efficiency its maximum is approximately 0.4 with respect to the softer radiation. Finally, we compare the XPAD3-S DQE with published curves of other digital devices in a similar radiation condition. The XPAD3-S/CdTe detector appears to be the best with the highest DQE at low frequency, although some improvements are expected to reduce the increase of noise with the counts statistics and to guarantee a better stability of the detector response.

Nuclear receptor and nuclear receptor target gene messenger ribonucleic acid levels at different sites of the gastrointestinal tract and in liver of healthy dogs

Nuclear receptors (NR) are ligand-activated transcription factors that regulate different metabolic pathways by influencing the expression of target genes. The current study examined mRNA abundance of NR and NR target genes at different sites of the gastrointestinal tract (GIT) and the liver of healthy dogs (Beagles; n = 11). Samples of GIT and liver were collected postmortem and homogenized, total RNA was extracted and reverse transcribed, and gene expression was quantified by real-time reverse-transcription PCR relative to the mean of 3 housekeeping genes (beta-actin, glyceraldehyde-3-phosphate dehydrogenase, and ubi-quitin). Differences were observed (P < or = 0.05) in the mRNA abundance among stomach (St), duodenum (Du), jejunum (Je), ileum (Il), and colon (Col) for NR [pregnane X receptor (Du, Je > Il, Col > St), peroxisome proliferator-associated receptor gamma (St, Du, Col > Je, Il), constitutive androstane receptor (Je, Du > Il, Col), and retinoid x receptor alpha (Du > Il)] and NR target genes [glutathione-S-transferase A3-3 (Du > Je > St, Il; St > Col), phenol-sulfating phenol sulfotransferase 1A1 (Du, Je > Il, St; Col > St), cytochrome P450 3A12 (Du, Je > St, Il, Col), multiple drug resistance gene 1 (Du, Je, Il, Col > St), multiple drug resistance-associated protein 2 (Je, Du > Il > St, Col), multiple drug resistance-associated protein 3 (Col > St > Il; Du > Je, Il; St > Il), NR corepressor 2 (St > Il, Col), and cytochrome P450 reductase (St, Du, Je > Il, Col)], but not for peroxisome proliferator-associated receptor alpha. Differences (P > 0.05) in mRNA abundance in the liver relative to the GIT were also observed. In conclusion, the presence of numerous differences in expression of NR and NR target genes in different parts of the GIT and in liver of healthy dogs may be associated with location-specific functions and regulation of GIT regions.

Nuclear receptor and target gene mRNA abundance in duodenum and colon of dogs with chronic enteropathies

Nuclear receptors (NR), such as constitutive androstane receptor (CAR), pregnane X receptor (PXR) and peroxisome proliferator-associated receptors alpha and gamma (PPARalpha, PPARgamma) are mediators of inflammation and may be involved in inflammatory bowel disease (IBD) and food responsive diarrhea (FRD) of dogs. The present study compared mRNA abundance of NR and NR target genes [multi drug-resistance gene-1 (MDR1), multiple drug-resistance-associated proteins (MRD2, MRD3), cytochrome P450 (CYP3A12), phenol-sulfating phenol sulfotransferase (SULT1A1) and glutathione-S-transferase (GST A3-3)] in biopsies obtained from duodenum and colon of dogs with IBD and FRD and healthy control dogs (CON; n=7 per group). Upon first presentation of dogs, mRNA levels of PPARalpha, PPARgamma, CAR, PXR and RXRalpha in duodenum as well as PPARgamma, CAR, PXR and RXRalpha in colon were not different among groups (P>0.10). Although mRNA abundance of PPARalpha in colon of dogs with FRD was similar in both IBD and CON (P>0.10), PPARalpha mRNA abundance was higher in IBD than CON (P<0.05). Levels of mRNA of MDR1 in duodenum were higher in FRD than IBD (P<0.05) or CON (P<0.001). Compared with CON, abundances of mRNA for MRP2, CYP3A12 and SULT1A1 were higher in both FRD and IBD than CON (P<0.05). Differences in mRNA levels of PPARalpha and MRP2 in colon and MDR1, MRP2, CYP3A12 and SULT1A1 in duodenum may be indicative for enteropathy in FRD and (or) IBD dogs relative to healthy dogs. More importantly, increased expression of MDR1 in FRD relative to IBD in duodenum may be a useful diagnostic marker to distinguish dogs with FRD from dogs with IBD.

Abundance of mRNA of Growth Hormone Receptor and Insulin-Like Growth Factors-1 and -2 in Duodenal and Colonic Biopsies of Dogs with Chronic Enteropathies*

Repair processes of the inflamed intestine are very important for dissolution of chronic enteropathies (CE). Therefore, we examined the mRNA abundance of growth hormone receptor (GHR), insulin-like growth factors (IGF)-1 and -2 in duodenal and colonic biopsies of dogs with CE such as food-responsive diarrhoea (FRD) and inflammatory bowel disease (IBD) before and after treatment as compared with each other and healthy dogs. A clinical score (Canine IBD Activity Index = CIBDAI) was applied to judge the severity of CE. Biopsies of duodenum and colon from client-owned dogs with CE were sampled before (FRD(bef), n = 5; IBD(bef), n = 5) and after treatment (FRD(aft), n = 5; IBD(aft), n = 5). Intestinal control samples were available from a homogenous control population (n = 15; C). Intestinal samples were homogenized, total RNA was extracted, reverse transcribed and analysed by real-time polymerase chain reaction to measure mRNA levels of GHR, IGF-1 and IGF-2. Results were normalized with glyceraldehyde phosphate dehydrogenase as housekeeping gene. The CIBDAI decreased during the treatment period in FRD and IBD (P < 0.01). In duodenum, GHR mRNA levels were higher in all groups than in C (P < 0.001). Duodenal IGF-1 mRNA levels in FRD(aft) and IBD(aft) tended to be higher than in C (P < 0.1). The IGF-2 mRNA abundance in FRD(aft) was higher than in C (P < 0.05) in duodenum. In colon, mRNA levels of IGF-1 in IBD(aft) were higher than in FRD(aft) (P < 0.05) and levels differed between IBD(aft) and C (P < 0.05). In conclusion, mRNA levels of GHR, IGF-1 and IGF-2 in the gastrointestinal tract were increased during CE when compared with gastrointestinally healthy dogs. The data suggest that GHR, IGF-1 and IGF-2 are involved in gastrointestinal repair processes.