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12 result(s) for "Fowler, Maxine"
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Photoperiodic changes in adiposity increase sensitivity of female Siberian hamsters to systemic VGF derived peptide TLQP-21
TLQP-21, a peptide encoded by the highly conserved vgf gene, is expressed in neuroendocrine cells and has been the most prominent VGF-derived peptide studied in relation to control of energy balance. The recent discovery that TLQP-21 is the natural agonist for the complement 3a receptor 1 (C3aR1) has revived interest in this peptide as a potential drug target for obesity. We have investigated its function in Siberian hamsters (Phodopus sungorus), a rodent that displays natural seasonal changes in body weight and adiposity as an adaptation to survive winter. We have previously shown that intracerebroventricular administration of TLQP-21 reduced food intake and body weight in hamsters in their long-day fat state. The aim of our current study was to determine the systemic actions of TLQP-21 on food intake, energy expenditure and body weight, and to establish whether adiposity affected these responses. Peripheral infusion of TLQP-21 (1mg/kg/day for 7 days) in lean hamsters exposed to short photoperiods (SP) reduced cumulative food intake in the home cage (p<0.05), and intake when measured in metabolic cages (P<0.01). Energy expenditure was significantly increased (p<0.001) by TLQP-21 infusion, this was associated with a significant increase in uncoupling protein 1 mRNA in brown adipose tissue (BAT) (p<0.05), and body weight was significantly reduced (p<0.05). These effects of systemic TLQP-21 treatment were not observed in hamsters exposed to long photoperiod (LP) with a fat phenotype. C3aR1 mRNA and protein were abundantly expressed in the hypothalamus, brown and white adipose tissue in hamsters, but changes in expression cannot explain the differential response to TLQP-21 in lean and fat hamsters.
Fructose Metabolism in the Adult Mouse Optic Nerve, A Central White Matter Tract
Our recent report that fructose supported the metabolism of some, but not all axons, in the adult mouse optic nerve prompted us to investigate in detail fructose metabolism in this tissue, a typical central white matter tract, as these data imply efficient fructose metabolism in the central nervous system (CNS). In artificial cerebrospinal fluid containing 10 mmol/L glucose or 20 mmol/L fructose, the stimulus-evoked compound action potential (CAP) recorded from the optic nerve consisted of three stable peaks. Replacing 10 mmol/L glucose with 10 mmol/L fructose, however, caused delayed loss of the 1st CAP peak (the 2nd and 3rd CAP peaks were unaffected). Glycogen-derived metabolic substrate(s) temporarily sustained the 1st CAP peak in 10 mmol/L fructose, as depletion of tissue glycogen by a prior period of aglycaemia or high-frequency CAP discharge rendered fructose incapable of supporting the 1st CAP peak. Enzyme assays showed the presence of both hexokinase and fructokinase (both of which can phosphorylate fructose) in the optic nerve. In contrast, only hexokinase was expressed in cerebral cortex. Hexokinase in optic nerve had low affinity and low capacity with fructose as substrate, whereas fructokinase displayed high affinity and high capacity for fructose. These findings suggest an explanation for the curious fact that the fast conducting axons comprising the 1st peak of the CAP are not supported in 10 mmol/L fructose medium; these axons probably do not express fructokinase, a requirement for efficient fructose metabolism.
Calbindin Deficits May Underlie Dissociable Effects of 5-HT6 and mGlu7 Antagonists on Glutamate and Cognition in a Dual-Hit Neurodevelopmental Model for Schizophrenia
Despite several compounds entering clinical trials for the negative and cognitive symptoms of schizophrenia, few have progressed beyond phase III. This is partly attributed to a need for improved preclinical models, to understand disease and enable predictive evaluation of novel therapeutics. To this end, one recent approach incorporates “dual-hit” neurodevelopmental insults like neonatal phencyclidine plus isolation rearing (PCP-Iso). Glutamatergic dysfunction contributes to schizophrenia pathophysiology and may represent a treatment target, so we used enzyme-based microsensors to evaluate basal- and drug-evoked glutamate release in hippocampal slices from rats that received neonatal PCP and/or isolation rearing. 5-HT6 antagonist-evoked glutamate release (thought to be mediated indirectly via GABAergic disinhibition) was reduced in PCP-Iso, as were cognitive effects of a 5-HT6 antagonist in a hippocampal glutamate-dependent novel object discrimination task. Yet mGlu7 antagonist-evoked glutamatergic and cognitive responses were spared. Immunohistochemical analyses suggest these findings (which mirror the apparent lack of clinical response to 5-HT6 antagonists in schizophrenia) are not due to reduced hippocampal 5-HT input in PCP-Iso, but may be explained by reduced calbindin expression. This calcium-binding protein is present in a subset of GABAergic interneurons receiving preferential 5-HT innervation and expressing 5-HT6 receptors. Its loss (in schizophrenia and PCP-Iso) would be expected to reduce interneuron firing and potentially prevent further 5-HT6 antagonist-mediated disinhibition, without impacting on responses of VIP-expressing interneurons to mGlu7 antagonism. This research highlights the importance of improved understanding for selection of appropriate preclinical models, especially where disease neurobiology impacts on cells mediating the effects of potential therapeutics.
Characterization of Behavioral, Signaling and Cytokine Alterations in a Rat Neurodevelopmental Model for Schizophrenia, and Their Reversal by the 5-HT6 Receptor Antagonist SB-399885
Post-weaning social isolation of rats produces neuroanatomical, neurochemical and behavioral alterations resembling some core features of schizophrenia. This study examined the ability of the 5-HT6 receptor antagonist SB-399885 to reverse isolation-induced cognitive deficits, then investigated alterations in hippocampal cell proliferation and hippocampal and frontal cortical expression of selected intracellular signaling molecules and cytokines. Male Lister hooded rats (weaned on post-natal days 21–24 and housed individually or in groups of 3–4) received six i.p. injections of vehicle (1% Tween 80, 1 mL/kg) or SB-399885 (5 or 10 mg/kg) over a 2-week period starting 40 days post-weaning, on the days that locomotor activity, novel object discrimination (NOD), pre-pulse inhibition of acoustic startle and acquisition, retention and extinction of a conditioned freezing response (CFR) were assessed. Tissue was collected 24 h after the final injection for immunohistochemistry, reverse-phase protein microarray and western blotting. Isolation rearing impaired NOD and cue-mediated CFR, decreased cell proliferation within the dentate gyrus, and elevated hippocampal TNFα levels and Cdc42 expression. SB-399885 reversed the NOD deficit and partially normalized CFR and cell proliferation. These effects were accompanied by altered expression of several members of the c-Jun N-terminal Kinase (JNK) and p38 MAPK signaling pathways (including TAK1, MKK4 and STAT3). Although JNK and p38 themselves were unaltered at this time point hippocampal TAK1 expression and phosphorylation correlated with visual recognition memory in the NOD task. Continued use of this neurodevelopmental model could further elucidate the neurobiology of schizophrenia and aid assessment of novel therapies for drug-resistant cognitive symptoms.
The toxicity of tricresyl phosphate towards cultured nerve cells and isolated nerve
The aim of this work was to study the effects of tricresyl phosphate (TCP; mixed isomers), triorthocresyl phosphate (TOCP), triparacresyl phosphate (TPCP) and one of the metabolites of TOCP, cyclic phenyl saligenin phosphate (CPSP), on the outgrowth of neurites by differentiating mouse N2a neuroblastoma and rat C6 glioma cells. At a concentration of 1 μg/ml (2.7 μM) TCP inhibited the outgrowth of axon-like processes in differentiating N2a cells. By contrast, TCP had no effect on the production of extensions by C6 glioma cells induced to differentiate by the addition of sodium butyrate suggesting a selective effect on neuronal cells under these conditions. Further work showed that 1 μg/ml TCP, TOCP (2.7μM) and 1 μ/ml CPSP (3.8 μM) inhibit the outgrowth of axon-like processes by N2a for up to 48 hours, whilst 1 μg/ml TPCP (2.7μM) demonstrates a transient inhibition at 24 hours which diminishes after 48 horns. Inhibition of axon outgrowth was also seen with TOCP and CPSP after 4 hours exposure whereas no inhibitory effects were seen with TCP or TPCP at this time point. It was found that TCP and TOCP but not TPCP could be microsomally activated into a form that caused greater inhibition of axon outgrowth than seen in the corresponding control situations after 4 hours of exposure. The Western blot data has showed that inhibited axon outgrowth was associated with cytoskeletal changes, consistently involving a reduction in neurofilament heavy chain (NF-H) phosphorylation and sometimes associated with a reduction in the levels of NF- H, tubulin and GAP-43. The inhibitory effects of these OPs on differentiating N2a cells were shown to be attenuated in the presence of conditioned medium from rat C6 glioma cells, which are known to produce neurotrophic factors. This protective effect was observed at all time points. Preliminary studies showed that the effects of OPs on pre-differentiated cells mirrored the principal effect seen on the typical differentiating N2a cellular system, with a reduction in the number of pre-formed axons. Taken together, the findings from this in vitro cellular system indicate that TOCP and its metabolite, which are both strongly neuropathic in vivo, cause selective inhibition of the outgrowth of axon-like processes by differentiating N2a cells, and that this effect is associated with cytoskeletal changes, notably in NFs. These in vitro patterns of toxicity agree with those observed in vivo, indicating that differentiating N2a cells represent a useful cellular system for studying the neurodegenerative effects of OPs and other similar compounds.
Letter: VIEWPOINTS - Where is our choice as parents?
Council leader Rodney Berman is quoted on Thursday, March 12, as saying: \"There are more places than required within the catchment area regarding the primary schools and they are taking pupils from other catchment areas.\" I have some questions to ask Mr Berman - through the Echo, as neither he nor two fellow councillors, Freda Salway or Kirsty Davies, have bothered to provide me with answers to the e-mails I sent them in December. Council figures show there are schools which have much higher numbers of out-of-catchment pupils than Eglwys Newydd.
Family Integrated Care (FICare) in Level II Neonatal Intensive Care Units: study protocol for a cluster randomized controlled trial
Background Every year, about 15 million of the world’s infants are born preterm (before 37 weeks gestation). In Alberta, the preterm birth rate was 8.7% in 2015, the second highest among Canadian provinces. Approximately 20% of preterm infants are born before 32 weeks gestation (early preterm), and require care in a Level III neonatal intensive care unit (NICU); 80% are born moderate (32 weeks and zero days [32 0/7 ] to 33 6/7 weeks) and late preterm (34 0/7 to 36 6/7 weeks), and require care in a Level II NICU. Preterm birth and experiences in the NICU disrupt early parent-infant relationships and induce parental psychosocial distress. Family Integrated Care (FICare) shows promise as a model of care in Level III NICUs. The purpose of this study is to evaluate length of stay, infant and maternal clinical outcomes, and costs following adaptation and implementation of FICare in Level II NICUs. Methods We will conduct a pragmatic, cluster randomized controlled trial (cRCT) in ten Alberta Level II NICUs allocated to one of two groups: FICare or standard care. The FICare Alberta model involves three theoretically-based, standardized components: information sharing, parenting education, and family support. Our sample size of 181 mother-infant dyads per group is based on the primary outcome of NICU length of stay, 80% participation, and 80% retention at follow-up. Secondary outcomes (e.g., infant clinical outcomes and maternal psychosocial distress) will be assessed shortly after admission to NICU, at discharge and 2 months corrected age. We will conduct economic analysis from two perspectives: the public healthcare payer and society. To understand the utility, acceptability, and impact of FICare, qualitative interviews will be conducted with a subset of mothers at the 2-month follow-up, and with hospital administrators and healthcare providers near the end of the study. Discussion Results of this pragmatic cRCT of FICare in Alberta Level II NICUs will inform policy decisions by providing evidence about the clinical effectiveness and costs of FICare. Trial registration ClinicalTrials.gov, ID: NCT02879799 . Registered on 27 May 2016. Protocol version: 9 June 2016; version 2.
Bitter harvest: how EU sugar subsidies devastate Africa
The £1.34bn that the EU pays out in sugar subsidies each year means that some of the richest farmers in the world benefit at the expense of the poorest. European consumers and tax payers are paying three times the world sugar price in order to finance a system that lines the pockets of the European sugar industry, while denying African countries the chance to grow out of poverty. Looks at the injustice of a trade regime that victimizes the poorest. (Quotes from original text)