The electrophysiological and morphological characterisation of aminergic responsive neurones within the rat hypothalamic arcuate nucleus in vitro

1. The hypothalamic arcuate nucleus (Arc) is a key integrative centre of the central nervous system (CNS) involved in the control and maintenance of energy balance. Whole-cell patch clamp recording techniques were utilised, in isolated hypothalamic brain slice preparations, to investigate the electrophysiological and morphological properties of Arc neurones. Differential expression of subthreshold active conductances were identified and used to functionally classify Arc neurones into 8 electrophysiological clusters. This classification was based based upon differential expression of the following conductances: anomalous inward rectification (Ian); hyperpolarisation-activated non-selective cation conductance (Ih); transient outward rectification (Ia); T-type-like calcium conductance. Morphological analysis of recorded neurones, revealed retrospectively with biocytin staining, showed four populations based upon the orientation and number of primary dendrites. There were no obvious direct correlations between morphology and electrophysiological properties, suggesting considerable functional diversity of neurones and their associated circuits at the level of the Arc. 2. The physiological levels of glucose to which the brain is exposed are believed to be around 1-2.5 mM, and glucose-sensing neurones have been identified in the Arc. However, in vitro slice studies routinely use glucose around 10 mM in aCSF. The impact of this high level of glucose on fundamental properties and operation of hypothalamic circuits remains unclear. Here the effect of different ambient glucose levels (10 mM, hyperglycaemic and 2 mM, euglycaemic) on electrophysiological properties of Arc neurones was compared. Significant differences in passive and active subthreshold membrane properties of Arc neurones were observed, including: changes in neuronal input resistance, spontaneous activity and magnitude of Ih and Ia. Data from this study suggests a need to re-evaluate studies previously conducted in non-physiological levels of glucose. 3. The effects of noradrenaline (NA) on the neuronal excitability of hypothalamic Arc neurones were studied. Application of NA induced a membrane depolarisation and increase in electrical excitability in 51% of Arc neurones, including orexigenic NPY/AgRP neurones, a response that persisted in the presence of TTX indicating a direct effect. NA-induced depolarisation was mediated through α1-ARs, in particular through α1A-ARs, and associated with multiple ionic mechanisms including: closure of a potassium conductance, activation of a non-selective cation conductance, or a combination of the two. 4. NA also induced a membrane hyperpolarisation in a sub-population of Arc neurones (15%) including 4/9 putative anorexigenic CART-expressing neurones, the remaining CART neurones responded with a NA-induced excitation. NA-induced hyperpolarisation, mediated via α2-ARs and activation of one or more potassium conductances, persisted in the presence of TTX indicating a direct effect on Arc neurones. 7.5% of neurones responded to NA with biphasic inhibitory/excitatory responses. Taken together, these data suggest that NA, at least in part, excites a subpopulation of NPY/AgRP neurones and inhibits a population of CART expressing neurones which may serve an orexigenic role at the level of the Arc. 5. Histamine induced membrane depolarisation in a population of Arc neurones (65%), most likely through H1 receptors, via a direct effect on the postsysnaptic membrane. Histamine induced depolarisation through multiple ionic mechanisms, including closure of a potassium conductance or activation of an electrogenic pump

Phosphorylation of the pro-apoptotic protein BAD on serine 155, a novel site, contributes to cell survival

AbstractPhosphorylation of BAD, a pro-apoptotic member of the Bcl-2 protein family, on either Ser112 or Ser136 is thought to be necessary and sufficient for growth factors to promote cell survival. Here we report that Ser155, a site phosphorylated by protein kinase A (PKA), also contributes to cell survival. Ser112 is thought to be the critical PKA target, but we found that BAD fusion proteins containing Ala at Ser112 (S112A) or Ser136 (S136A) or at both positions (S112/136A) were still heavily phosphorylated by PKA in an in vitro kinase assay. BAD became insensitive to phosphorylation by PKA only when both Ser112 and Ser136, or all three serines (S112/136/155) were mutated to alanine. In HEK293 cells, BAD fusion proteins mutated at Ser155 were refractory to phosphorylation induced by elevation of cyclic AMP(cAMP) levels. Phosphorylation of the S112/136A mutant was >90% inhibited by H89, a PKA inhibitor. The S155A mutant induced more apoptosis than the wild-type protein in serum-maintained CHO-K1 cells, and apoptosis induced by the S112/136A mutant was potentiated by serum withdrawal. These data suggest that Ser155 is a major site of phosphorylation by PKA and serum-induced kinases. Like Ser112 and Ser136, phosphorylation of Ser155 contributes to the cancellation of the pro-apoptotic function of BAD

The electrophysiological and morphological characterisation of aminergic responsive neurones within the rat hypothalamic arcuate nucleus in vitro

1. The hypothalamic arcuate nucleus (Arc) is a key integrative centre of the central nervous system (CNS) involved in the control and maintenance of energy balance. Whole-cell patch clamp recording techniques were utilised, in isolated hypothalamic brain slice preparations, to investigate the electrophysiological and morphological properties of Arc neurones. Differential expression of subthreshold active conductances were identified and used to functionally classify Arc neurones into 8 electrophysiological clusters. This classification was based based upon differential expression of the following conductances: anomalous inward rectification (Ian); hyperpolarisation-activated non-selective cation conductance (Ih); transient outward rectification (Ia); T-type-like calcium conductance. Morphological analysis of recorded neurones, revealed retrospectively with biocytin staining, showed four populations based upon the orientation and number of primary dendrites. There were no obvious direct correlations between morphology and electrophysiological properties, suggesting considerable functional diversity of neurones and their associated circuits at the level of the Arc. 2. The physiological levels of glucose to which the brain is exposed are believed to be around 1-2.5 mM, and glucose-sensing neurones have been identified in the Arc. However, in vitro slice studies routinely use glucose around 10 mM in aCSF. The impact of this high level of glucose on fundamental properties and operation of hypothalamic circuits remains unclear. Here the effect of different ambient glucose levels (10 mM, hyperglycaemic and 2 mM, euglycaemic) on electrophysiological properties of Arc neurones was compared. Significant differences in passive and active subthreshold membrane properties of Arc neurones were observed, including: changes in neuronal input resistance, spontaneous activity and magnitude of Ih and Ia. Data from this study suggests a need to re-evaluate studies previously conducted in non-physiological levels of glucose. 3. The effects of noradrenaline (NA) on the neuronal excitability of hypothalamic Arc neurones were studied. Application of NA induced a membrane depolarisation and increase in electrical excitability in 51% of Arc neurones, including orexigenic NPY/AgRP neurones, a response that persisted in the presence of TTX indicating a direct effect. NA-induced depolarisation was mediated through α1-ARs, in particular through α1A-ARs, and associated with multiple ionic mechanisms including: closure of a potassium conductance, activation of a non-selective cation conductance, or a combination of the two. 4. NA also induced a membrane hyperpolarisation in a sub-population of Arc neurones (15%) including 4/9 putative anorexigenic CART-expressing neurones, the remaining CART neurones responded with a NA-induced excitation. NA-induced hyperpolarisation, mediated via α2-ARs and activation of one or more potassium conductances, persisted in the presence of TTX indicating a direct effect on Arc neurones. 7.5% of neurones responded to NA with biphasic inhibitory/excitatory responses. Taken together, these data suggest that NA, at least in part, excites a subpopulation of NPY/AgRP neurones and inhibits a population of CART expressing neurones which may serve an orexigenic role at the level of the Arc. 5. Histamine induced membrane depolarisation in a population of Arc neurones (65%), most likely through H1 receptors, via a direct effect on the postsysnaptic membrane. Histamine induced depolarisation through multiple ionic mechanisms, including closure of a potassium conductance or activation of an electrogenic pump.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The role of the GP in managing suspected transient ischaemic attack: a qualitative study.

BACKGROUND: National guidelines recommend patients with suspected transient ischaemic attack (TIA) should be seen by a specialist within 24 h. However, people with suspected TIA often present to non-specialised services, particularly primary care. Therefore, general practitioners (GPs) have a crucial role in recognition and urgent referral of people with suspected TIA. This study aims to explore the role of GPs in the initial management of suspected TIA in the United Kingdom (UK). METHODS: One-to-one, semi-structured interviews with GPs, TIA clinic staff and patients with suspected TIA from two sites in the UK: Cambridge and Birmingham. Thematic analysis was undertaken to explore views on the role of the GP in managing suspected TIA. Thirty semi-structured interviews were conducted with stroke patients (n = 12), GPs (n = 9) and TIA clinic hospital staff (n = 9) from two hospitals and nine GP practices in surrounding areas. RESULTS: Three overarching themes were identified: (1) multiple management pathways for suspected TIA; (2) uncertainty regarding suspected TIA as an emergency or routine situation; and (3) influences on the urgency of GP management. CONCLUSIONS: Guidelines on the primary care management of TIA describe only a small proportion of the factors which influence GP management and referral of suspected TIA. Efforts to improve treatment, appropriate referral and patient experience should use a real rather than idealised model of the GP role in managing suspected TIA.This research was funded by the National Institute for Health Research. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. The funders had no role in the design of the study and collection, analysis, and interpretation of data or in writing the manuscript. JM and GT receive funding from the National Institute for Health Research NIHR Senior Investigator Award and Postdoctoral Fellowship Award, respectively. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care

Herschel-SPIRE-Fourier Transform Spectroscopy of the nearby spiral galaxy IC342

We present observations of the nearby spiral galaxy IC342 with the Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer. The spectral range afforded by SPIRE, 196-671 microns, allows us to access a number of 12CO lines from J=4--3 to J=13--12 with the highest J transitions observed for the first time. In addition we present measurements of 13CO, [CI] and [NII]. We use a radiative transfer code coupled with Bayesian likelihood analysis to model and constrain the temperature, density and column density of the gas. We find two 12CO components, one at 35 K and one at 400 K with CO column densities of 6.3x10^{17} cm^{-2} and 0.4x10^{17} cm^{-2} and CO gas masses of 1.26x10^{7} Msolar and 0.15x10^{7} Msolar, for the cold and warm components, respectively. The inclusion of the high-J 12CO line observations, indicate the existence of a much warmer gas component (~400 K) confirming earlier findings from H_{2} rotational line analysis from ISO and Spitzer. The mass of the warm gas is 10% of the cold gas, but it likely dominates the CO luminosity. In addition, we detect strong emission from [NII] 205microns and the {3}P_{1}->{3}P_{0} and {3}P_{2} ->{3}P_{1} [CI] lines at 370 and 608 microns, respectively. The measured 12CO line ratios can be explained by Photon-dominated region (PDR) models although additional heating by e.g. cosmic rays cannot be excluded. The measured [CI] line ratio together with the derived [C] column density of 2.1x10^{17} cm^{-2} and the fact that [CI] is weaker than CO emission in IC342 suggests that [CI] likely arises in a thin layer on the outside of the CO emitting molecular clouds consistent with PDRs playing an important role.Comment: 9 pages, 8 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS

Locating Community among People with Schizophrenia living in a Diverse Urban Environment

Increasing the community participation of people with severe mental illness is a primary goal of recovery-oriented services. Despite this emphasis, the construct of community remains understudied and poorly articulated. This study provides an in-depth examination of the experiences, beliefs, behaviors, and spaces that constitute community participation for a highly diverse group of people with schizophrenia who are urban dwellers. An in-depth, longitudinal qualitative design was employed with 30 individuals with schizophrenia residing in inner-city neighborhoods in Canada’s largest city. For these individuals, community participation is a dynamic process, shaped by illness and non-illness-associated social relationships and spaces, self-concept, and the resources accessible to the person. The complexity of factors that are associated with “community” for people with schizophrenia, with overlays of culture, poverty, victimization, and discrimination, calls for a critical examination of the community rhetoric employed in practice and policy contexts

Counteractive effects of antenatal glucocorticoid treatment on D1 receptor modulation of spatial working memory.

RATIONALE: Antenatal exposure to the glucocorticoid dexamethasone dramatically increases the number of mesencephalic dopaminergic neurons in rat offspring. However, the consequences of this expansion in midbrain dopamine (DA) neurons for behavioural processes in adulthood are poorly understood, including working memory that depends on DA transmission in the prefrontal cortex (PFC). OBJECTIVES: We therefore investigated the influence of antenatal glucocorticoid treatment (AGT) on the modulation of spatial working memory by a D1 receptor agonist and on D1 receptor binding and DA content in the PFC and striatum. METHODS: Pregnant rats received AGT on gestational days 16-19 by adding dexamethasone to their drinking water. Male offspring reared to adulthood were trained on a delayed alternation spatial working memory task and administered the partial D1 agonist SKF38393 (0.3-3 mg/kg) by systemic injection. In separate groups of control and AGT animals, D1 receptor binding and DA content were measured post-mortem in the PFC and striatum. RESULTS: SKF38393 impaired spatial working memory performance in control rats but had no effect in AGT rats. D1 binding was significantly reduced in the anterior cingulate cortex, prelimbic cortex, dorsal striatum and ventral pallidum of AGT rats compared with control animals. However, AGT had no significant effect on brain monoamine levels. CONCLUSIONS: These findings demonstrate that D1 receptors in corticostriatal circuitry down-regulate in response to AGT. This compensatory effect in D1 receptors may result from increased DA-ergic tone in AGT rats and underlie the resilience of these animals to the disruptive effects of D1 receptor activation on spatial working memory.The authors’ research is funded by the Wellcome Trust (grant number 086871/Z/08/Z), the MRC (G0701500), a joint award from the MRC (G1000183) and Wellcome Trust (093875/Z/10/ Z) in support of the Behavioral and Clinical Neuroscience Institute at Cambridge University, and an MRC strategic award to the Imperial College-Cambridge University-Manchester University (ICCAM) addiction cluster (G1000018).This is the final version of the article. It first appeared from Springer at http://dx.doi.org/10.1007/s00213-016-4405-8

Structural Analysis of Nano Core PCF With Fused Cladding for Supercontinuum Generation in 6G Networks

The Sixth Generation (6G) networks have identified the use of frequency range between 95 GHz and 3 THz with a targeted data rate of 1 Terabytes/second at the access network for holographic video applications. As is demands broadening of spectrum at the core network, this paper proposes a Supercontinuum Generation (SCG) through photonic crystal fiber (PCF) as it provides excellent broadening of the optical spectrum. Discussed in the paper is supercontinuum generation at high pumping power as per the standards specified by the International Telecommunications Union. The proposed PCF is designed with silicon nanocrystal core and the cladding microstructures is arranged in a fusion approach to effectively optimize the optical parameters such as dispersion, nonlinearity, birefringence, group-velocity dispersion, and confinement loss. The fused cladding comprises of a flower-cladding assembly in which air-holes arrangement is inspired from petals in a pleated structure. Such arrangement is shown here to provide high nonlinearity and negative dispersion for high power supercontinuum generation. The novel nanocore assembly with improved structural constraints delivers a non-linearity of 6.37 × 106 W−1 km−1 and a negative dispersion of −142.1 (ps/nm-km) at 1,550 nm. Moreover, a supercontinuum spectrum is generated using different pulse widths ranging from 350 to 650 ps with 25 kW pump power for PCF lengths of 10 and 15 mm

Response of FDG avid pelvic bone marrow to concurrent chemoradiation for anal cancer

BACKGROUND AND PURPOSE: To determine if suppression of active bone marrow, as defined on FDG PETCT, is seen in on-treatment imaging of anal cancer patients receiving concurrent chemoradiation. METHODS AND MATERIALS: Scans from 26 patients participating in the ART trial (full title: Anal squamous cell carcinoma: Investigation of functional imaging during chemoRadioTherapy), a single center observational study with FDG PETCT prior to radiotherapy and at fraction 8-10 of concurrent chemoradiation were analysed. Active bone marrow was contoured in both the pelvis and un-irradiated thoracic spine. SUV and volume of active bone marrow after 8-10 fractions of treatment were compared to baseline. Dose metrics to pelvic active bone marrow were extracted and compared to reduction in SUV/active bone marrow volume and to blood count nadir using linear regression. RESULTS: Suppression of active bone marrow is seen in the pelvis by a reduction in mean SUV and volume of active bone marrow after 8-10 fractions of treatment. Suppression is not seen in un-irradiated thoracic spine. Dose metrics were associated with reduced SUV and reduced volume of active bone marrow. Volume of active bone marrow receiving <20 Gy was associated with WCC/ANC nadir. 20 Gy was identified as the most likely clinically meaningful dose threshold for toxicity. Volume of active bone marrow receiving <20 Gy correlated to WCC and ANC with an increase of 100 cc being associated with an increase of 0.4 and 0.3 respectively. CONCLUSION: The effect of concurrent chemoradiation in suppression of active bone marrow is seen in on-treatment FDG PETCT scans. Chemotherapy appears well tolerated after 2 weeks of treatment

Herschel-ATLAS/GAMA: A difference between star formation rates in strong-line and weak-line radio galaxies

We have constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) Phase 1 fields. Classifying the radio sources in terms of their optical spectra, we find that strong-emission-line sources ('high-excitation radio galaxies') have, on average, a factor of ~4 higher 250-μm Herschel luminosity than weak-line ('lowexcitation') radio galaxies and are also more luminous than magnitude-matched radio-quiet galaxies at the same redshift. Using all five H-ATLAS bands, we show that this difference in luminosity between the emission-line classes arises mostly from a difference in the average dust temperature; strong-emission-line sources tend to have comparable dust masses to, but higher dust temperatures than, radio galaxies with weak emission lines. We interpret this as showing that radio galaxies with strong nuclear emission lines are much more likely to be associated with star formation in their host galaxy, although there is certainly not a one-to-one relationship between star formation and strong-line active galactic nuclei (AGN) activity. The strong-line sources are estimated to have star formation rates at least a factor of 3-4 higher than those in the weak-line objects. Our conclusion is consistent with earlier work, generally carried out using much smaller samples, and reinforces the general picture of high-excitation radio galaxies as being located in lower-mass, less evolved host galaxies than their low-excitation counterparts.Peer reviewe