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2.
Eur J Hum Genet ; 2024 Feb 15.
Article in English | MEDLINE | ID: mdl-38355960

ABSTRACT

Genetic counselling education and training in Europe spans a continuum of 30 years. More master programs are opening due the demand for qualified genetic counselors. This report describes the evolution of training in Europe and the current state of genetic counselling training programs. Directors of master programs in Europe were invited to complete an online survey describing their program, including year of commencement, course duration, number of students and frequency of intake and number graduating. Results of the survey were presented at a closed meeting at the European Society of Human Genetics conference in 2022 along with a facilitated stakeholder engagement session in which 19 professionals participated to understand the challenges in delivering genetic counselling education in Europe. A total of 10 active programs exists in Europe with the first training program starting in 1992. The majority of training programs have a 2-year duration, with just over half of programs having an annual intake of students. Up to May 2022, 710 students have graduated from genetic counseling training programs across Europe. Of these, 670 students graduated from European Board of Medical Genetics-registered programs. Arranging clinical placements, clinical and counseling supervision of students, research collaboration for MSc research projects and incorporating genomics into the curriculum were identified as current challenges for genetic counseling education. Genetic counseling is still a developing profession in Europe and this historical and current view of the European genetic counselor pathways, allows for educational and professional standards to be examined as the profession evolves into the future.

3.
Int J Pediatr Otorhinolaryngol ; 150: 110861, 2021 Nov.
Article in English | MEDLINE | ID: mdl-34583300

ABSTRACT

INTRODUCTION: Corona-virus Disease 2019 (COVID-19) has had a huge impact on the delivery of healthcare worldwide, particularly elective surgery. There is a lack of data regarding risk of postoperative COVID-19 infection in children undergoing elective surgery, and regarding the utility of pre-operative COVID-19 testing, and preoperative "cocooning" or restriction of movements. The purpose of this present study was to examine the safety of elective paediatric Otolaryngology surgery during the COVID-19 pandemic with respect to incidence of postoperative symptomatic COVID-19 infection or major respiratory complications. MATERIALS AND METHODS: Prospective cohort study of paediatric patients undergoing elective Otolaryngology surgery between September and December 2020. Primary outcome measure was incidence of symptomatic COVID-19 or major respiratory complications within the 14 days after surgery. Parents of prospectively enrolled patients were contacted 14 days after surgery and enquiry made regarding development of postoperative symptoms, COVID-19 testing, or diagnosis of COVID-19. RESULTS: 302 patients were recruited. 125 (41.4%) underwent preoperative COVID-19 RT-PCR testing. 66 (21.8%) restricted movements prior to surgery. The peak 14-day COVID-19 incidence during the study was 302.9 cases per 100,000 population. No COVID-19 infections or major respiratory complications were reported in the 14 day follow-up period. CONCLUSION: The results of our study support the safety of elective paediatric Otolaryngology surgery during the pandemic, in the setting of community incidence not exceeding that observed during the study period.


Subject(s)
COVID-19 , Pandemics , COVID-19 Testing , Child , Elective Surgical Procedures , Humans , Prospective Studies , SARS-CoV-2
4.
Nat Commun ; 12(1): 4303, 2021 07 14.
Article in English | MEDLINE | ID: mdl-34262037

ABSTRACT

Lipid droplets (LDs) are increasingly recognized as critical organelles in signalling events, transient protein sequestration and inter-organelle interactions. However, the role LDs play in antiviral innate immune pathways remains unknown. Here we demonstrate that induction of LDs occurs as early as 2 h post-viral infection, is transient and returns to basal levels by 72 h. This phenomenon occurs following viral infections, both in vitro and in vivo. Virally driven in vitro LD induction is type-I interferon (IFN) independent, and dependent on Epidermal Growth Factor Receptor (EGFR) engagement, offering an alternate mechanism of LD induction in comparison to our traditional understanding of their biogenesis. Additionally, LD induction corresponds with enhanced cellular type-I and -III IFN production in infected cells, with enhanced LD accumulation decreasing viral replication of both Herpes Simplex virus 1 (HSV-1) and Zika virus (ZIKV). Here, we demonstrate, that LDs play vital roles in facilitating the magnitude of the early antiviral immune response specifically through the enhanced modulation of IFN following viral infection, and control of viral replication. By identifying LDs as a critical signalling organelle, this data represents a paradigm shift in our understanding of the molecular mechanisms which coordinate an effective antiviral response.


Subject(s)
Interferons/immunology , Lipid Droplets/immunology , Virus Diseases/immunology , Animals , ErbB Receptors/antagonists & inhibitors , ErbB Receptors/metabolism , Herpesvirus 1, Human/physiology , Humans , Immunity, Innate , Interferons/genetics , Interferons/metabolism , Lipid Droplets/metabolism , Mice , Nucleic Acids/metabolism , Virus Replication/drug effects , Zika Virus/physiology
5.
Clin Transl Radiat Oncol ; 21: 98-103, 2020 Mar.
Article in English | MEDLINE | ID: mdl-32072031

ABSTRACT

There is an increasing need to measure treatment-related side effects in normal tissues following cancer therapy. The ALERT-B (Assessment of Late Effects of RadioTherapy - Bowel) questionnaire is a screening tool that is composed of four items related specifically to bowel symptoms. Those patients that respond with a "yes" to any of these items are referred on to gastroenterologist in order to improve the long-term consequences of these side effects of radiological treatment. Here we wish to test the ability of this questionnaire to identify these subsequent gastroenterological complications by tracking prostate cancer patients that were positive with respect to ALERT-B. We also carry out receiver-operator curve (ROC) analysis for baseline data for an overall ALERT-B questionnaire score with respect to subscale data for the Gastrointestinal Symptom Rating Scale (GSRS) and the Expanded Prostate Cancer Index Composite (EPIC-26) questionnaire. 84.4% and 95.7% of patients identified by the ALERT-B questionnaire demonstrated complications diagnosed at 6 and 12 months post-treatment, respectively. ROC curve analysis of baseline data showed that ALERT-B detected clinically relevant levels of side effects established at baseline by the GSRS diarrhoea subscale (AUC = 0.867, 95% CI = 0.795 to 0.926) and at the minimally important level of side effects for the EPIC bowel subscale (AUC = 0.765, 95% CI = 0.617 to 0.913). These results show that ALERT-B provides a simple and effective screening tool for identifying gastroenterological complications after treatment for prostate cancer.

6.
Ir Med J ; 111(2): 694, 2018 Feb 09.
Article in English | MEDLINE | ID: mdl-29952443

ABSTRACT

Correct technique with inhalers is vital for therapeutic effect. Efficacy of DVD inhaler instruction was investigated. Secondary aims were to examine feasibility of an inhaler technique outcome measure, and to compare knowledge and self-efficacy after DVD or individual education. This was a randomised controlled trial conducted in a regional hospital paediatric ward, involving new or existing paediatric inhaler users. Inhaler technique was assessed pre-education in existing inhaler users. Participants were then randomised to message equivalent education by DVD or individually with a physiotherapist. Inhaler technique, self-efficacy and knowledge were assessed immediately post- and three months after education. Twenty one participants received DVD or individual education. There were no significant differences between groups for technique, self-efficacy or knowledge at any time. The outcome measure was feasible for use in a research study. DVD education was equivalent to individual instruction to teach parents how to use inhalers with their child.


Subject(s)
Nebulizers and Vaporizers , Patient Education as Topic , Physical Therapists , Video Recording , Child , Feasibility Studies , Humans
7.
J Psychiatr Res ; 100: 24-32, 2018 05.
Article in English | MEDLINE | ID: mdl-29475018

ABSTRACT

Current first-line antidepressants can take weeks or months to decrease depressive symptoms. Low dose ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, shows potential for a more rapid antidepressant effect, with efficacy also evident in previously treatment-resistant populations. However, a greater understanding of the physiological mechanisms underlying such effects is required. We assessed the potential impact of ketamine infusion on neurobiological drivers of kynurenine pathway metabolism in major depression (HPA axis hyperactivity, inflammation) in patients with treatment-resistant depression compared to gender-matched healthy controls. Furthermore, we assessed these biomarkers before and after electroconvulsive therapy (ECT), which is currently the gold standard for management of treatment-resistant depression. As previously demonstrated, treatment with ketamine and ECT was associated with improved depressive symptoms in patients. At baseline, waking cortisol output was greater in the ECT cohort, kynurenine was greater in the ketamine cohort, and kynurenic acid was lower in patients compared to healthy controls, although inflammatory markers (IL-6, IL-8, IL-10 or IFN-γ) were similar in patients and controls. Furthermore, in patients who responded to ECT, the cortisol awakening response was decreased following treatment. Despite a trend towards reduced kynurenine concentrations in those who responded to ketamine, ketamine was not associated with significant alterations in any of the biomarkers assessed.


Subject(s)
Antidepressive Agents/pharmacology , Cytokines/drug effects , Depressive Disorder, Treatment-Resistant/blood , Depressive Disorder, Treatment-Resistant/drug therapy , Electroconvulsive Therapy/methods , Hydrocortisone/blood , Ketamine/pharmacology , Kynurenine/drug effects , Outcome Assessment, Health Care , Adult , Antidepressive Agents/administration & dosage , Biomarkers/blood , Humans , Ketamine/administration & dosage , Metabolic Networks and Pathways/drug effects
8.
Fam Cancer ; 17(1): 123-128, 2018 01.
Article in English | MEDLINE | ID: mdl-28509937

ABSTRACT

The increased availability of next generation sequencing (NGS) and multi gene panel testing has resulted in more frequent TP53 testing of families that do not meet classic testing criteria. We investigated testing criteria, family history and result outcome in a cohort of Irish probands undergoing TP53 full sequencing. All TP53 test requests processed through the national genetic testing laboratory between 2012 and 2014 were retrospectively reviewed. Personal and family cancer histories were collected, including tumour type and age at diagnosis, from two adult cancer genetic services in Ireland. Association between Li Fraumeni syndrome (LFS) or Li Fraumeni like syndrome (LFL) criteria and test result was examined. One hundred and 35 TP53 test requests were identified. Family history data and test results were available on 123 of the TP53 test requests (118 female; 5 male). 59/123 (48%) did not meet classic LFS or LFL criteria. Two individuals from this group harboured pathogenic TP53 mutations, giving a 3% mutation detection rate in those not meeting testing criteria. Both were female and had a personal history of early onset bilateral breast cancer with no reported LFS cancers in the family. 64/123 (52%) met LFS or LFL criteria and were all TP53 negative. 37/64 (57.8%) met Chompret criteria, 19/64 (29.7%) met Eeles and 7/64 (10.9%) met Eeles and Chompret and 1/64 (1.6%) met Classic LFS criteria. Stringent testing criteria miss germline mutations in TP53. Broadening the criteria for TP53 testing may improve our understanding of the phenotype and penetrance in the association syndrome.


Subject(s)
Breast Neoplasms/diagnosis , High-Throughput Nucleotide Sequencing/statistics & numerical data , Li-Fraumeni Syndrome/diagnosis , Penetrance , Tumor Suppressor Protein p53/genetics , Adult , Aged , Breast Neoplasms/genetics , DNA Mutational Analysis/statistics & numerical data , Female , Genetic Predisposition to Disease , Genetic Testing/methods , Genetic Testing/standards , Genetic Testing/statistics & numerical data , Germ-Line Mutation , Humans , Ireland , Li-Fraumeni Syndrome/genetics , Male , Middle Aged , Patient Selection , Retrospective Studies
9.
Bioresour Technol ; 216: 238-49, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27240240

ABSTRACT

Four feedstocks were assessed for use in a demand driven biogas system. Biomethane potential (BMP) assays were conducted for grass silage, food waste, Laminaria digitata and dairy cow slurry. Semi-continuous trials were undertaken for all feedstocks, assessing biogas and biomethane production. Three kinetic models of the semi-continuous trials were compared. A first order model most accurately correlated with gas production in the pulse fed semi-continuous system. This model was developed for production of electricity on demand, and biomethane upgrading. The model examined a theoretical grass silage digester that would produce 435kWe in a continuous fed system. Adaptation to demand driven biogas required 187min to produce sufficient methane to run a 2MWe combined heat and power (CHP) unit for 60min. The upgrading system was dispatched 71min following CHP shutdown. Of the biogas produced 21% was used in the CHP and 79% was used in the upgrading system.


Subject(s)
Biofuels , Biotechnology/methods , Methane/biosynthesis , Animals , Biofuels/analysis , Biotechnology/instrumentation , Cattle , Dairying , Electricity , Female , Food , Kinetics , Laminaria , Manure , Models, Theoretical , Poaceae , Silage , Waste Management/instrumentation , Waste Management/methods
10.
Bioresour Technol ; 202: 172-80, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26708485

ABSTRACT

A two-stage food waste digestion system involved a first stage hydrolysis reactor followed by a second stage methanogenic reactor. Organic loading rates (OLR) were increased from 6 to 15 g VS L(-1) d(-1) in the hydrolysis reactor and from 2 to 5 g VS L(-1) d(-1) in the methanogenic reactor. The retention time was fixed at 4 days (hydrolysis reactor) and 12 days (methane reactor). A single-stage digester was subjected to similar loading rates as the methanogenic reactor at 16 days retention. Increased OLR resulted in higher quantities of liquid fermentation products from the first stage hydrolysis reactor. Solubilisation of chemical oxygen demand peaked at 47% at the maximum loading. However, enhanced hydrolysis yields had no significant impact on the specific methane yields. The two-stage system increased methane yields up to 23% and enriched methane content by an average of 14% to levels of 71%.


Subject(s)
Digestion , Food , Waste Products , Anaerobiosis , Biological Oxygen Demand Analysis , Bioreactors/standards , Fermentation , Hydrolysis , Methane/analysis , Methane/metabolism
11.
Ir Med J ; 109(10): 485, 2016 Dec 12.
Article in English | MEDLINE | ID: mdl-28644590

ABSTRACT

MUTYH is involved in DNA damage repair. Bi-allelic MUTYH mutations predispose to polyposis and gastrointestinal malignancies, distinct genetically from autosomal dominant familial adenomatous polyposis coli. Two common European MUTYH mutations account for 90% of MUTYH-associated polyposis (MAP). We aimed to examine the incidence of MAP in Ireland. A retrospective cohort study was undertaken. Patients undergoing MUTYH testing from 2003-2016 were identified by searching electronic databases using terms "MUTYH" and "MYH". Phenotypic and genotypic details were obtained by chart review. Bi-allelic mutations were confirmed in 26 individuals (17 families), of whom 16 (62%) developed colorectal malignancies, and 22(85%) polyposis. Eleven families had bi-allelic status for one/both common European mutations. Regional variation was noted, with over-representation of bi-allelic mutation carriers in the South-west of Ireland. MAP is under-diagnosed in Ireland. Increased awareness is required to facilitate appropriate identification and surveillance of bi-allelic mutation carriers for colorectal pathology.


Subject(s)
Colorectal Neoplasms/epidemiology , Colorectal Neoplasms/genetics , DNA Glycosylases/genetics , Intestinal Polyps/epidemiology , Intestinal Polyps/genetics , Mutation/genetics , Adenomatous Polyposis Coli/genetics , Genetic Predisposition to Disease , Genotype , Humans , Incidence , Ireland/epidemiology , Phenotype , Retrospective Studies
12.
Philos Trans A Math Phys Eng Sci ; 373(2035)2015 Feb 28.
Article in English | MEDLINE | ID: mdl-25583866

ABSTRACT

Understanding of dynamic behaviour of offshore wind floating substructures is extremely important in relation to design, operation, maintenance and management of floating wind farms. This paper presents assessment of nonlinear signatures of dynamic responses of a scaled tension-leg platform (TLP) in a wave tank exposed to different regular wave conditions and sea states characterized by the Bretschneider, the Pierson-Moskowitz and the JONSWAP spectra. Dynamic responses of the TLP were monitored at different locations using load cells, a camera-based motion recognition system and a laser Doppler vibrometer. The analysis of variability of the TLP responses and statistical quantification of their linearity or nonlinearity, as non-destructive means of structural monitoring from the output-only condition, remains a challenging problem. In this study, the delay vector variance (DVV) method is used to statistically study the degree of nonlinearity of measured response signals from a TLP. DVV is observed to create a marker estimating the degree to which a change in signal nonlinearity reflects real-time behaviour of the structure and also to establish the sensitivity of the instruments employed to these changes. The findings can be helpful in establishing monitoring strategies and control strategies for undesirable levels or types of dynamic response and can help to better estimate changes in system characteristics over the life cycle of the structure.

13.
Neuroscience ; 254: 335-46, 2013 Dec 19.
Article in English | MEDLINE | ID: mdl-24095695

ABSTRACT

Astrocytes are plastic cells that play key roles in brain physiology and pathology, including via their glutamate transporters, excitatory amino acid transporter (EAAT)1 and EAAT2, maintaining low extracellular glutamate concentrations and protecting against excitotoxic neuronal injury. Alterations in cell surface expression of EAATs and astrocytic cytoskeleton are important for regulating transporter activity. This study employed the actions of rottlerin, to interrogate the regulation of EAAT activity, expression and localization, and interfaces with Na(+)/K(+)-ATPase and astrocytic morphology. EAAT activity and expression were determined in primary cultures of mouse astrocytes in the presence of and after rottlerin removal, with or without trafficking inhibitors, using uptake ([(3)H]d-aspartate, (86)Rb(+)) and molecular analyses. Astrocytic morphology and EAAT localization were investigated using Western blotting and immunocytochemistry, in concert with image analysis of glial fibrillary acidic protein, F-actin and EAAT1/2. Rottlerin induced a time-dependent inhibition of glutamate transport (Vmax). Rapid changes in cytoskeletal arrangement were observed and immunoblotting revealed increases in EAAT2 total and cell surface expression, despite reduced EAAT activity. Rottlerin-induced inhibition was reversible and its rate was increased by monensin co-treatment. Rottlerin inhibited, while monensin stimulated Na(+)/K(+)-ATPase. Removal of rottlerin rapidly elevated Na(+)/K(+)-ATPase activity beyond control levels, while co-treatment with monensin failed to stimulate the Na(+)/K(+)-ATPase. These data reveal inhibition of EAAT activity by rottlerin is not associated with loss of EAATs at the cell surface, but rather linked to cytoskeletal rearrangement, and inhibition of the Na(+)/K(+)-ATPase. Rapid recovery of Na(+)/K(+)-ATPase activity, and subsequent restoration of glutamate uptake indicates that astrocytic morphology and EAAT activity are co-regulated by a tightly coupled, homeostatic relationship between l-glutamate uptake, the electrochemical gradient and the activity of the Na(+)/K(+)-ATPase.


Subject(s)
Acetophenones/pharmacology , Astrocytes/metabolism , Benzopyrans/pharmacology , Cytoskeleton/metabolism , Excitatory Amino Acid Transporter 1/metabolism , Excitatory Amino Acid Transporter 2/metabolism , Sodium-Potassium-Exchanging ATPase/metabolism , Animals , Astrocytes/drug effects , Cell Survival/drug effects , Cell Survival/physiology , Cells, Cultured , Cytoskeleton/drug effects , Enzyme Inhibitors/pharmacology , Excitatory Amino Acid Transporter 1/antagonists & inhibitors , Excitatory Amino Acid Transporter 2/antagonists & inhibitors , Mice , Mice, Inbred C57BL , Sodium-Potassium-Exchanging ATPase/antagonists & inhibitors
14.
Br J Pharmacol ; 163(3): 533-45, 2011 Jun.
Article in English | MEDLINE | ID: mdl-21309758

ABSTRACT

BACKGROUND AND PURPOSE: Glutamate transporters play a major role in maintaining brain homeostasis and the astrocytic transporters, EAAT1 and EAAT2, are functionally dominant. Astrocytic excitatory amino acid transporters (EAATs) play important roles in various neuropathologies wherein astrocytes undergo cytoskeletal changes. Astrocytic plasticity is well documented, but the interface between EAAT function, actin and the astrocytic cytoskeleton is poorly understood. Because Rho kinase (ROCK) is a key determinant of actin polymerization, we investigated the effects of ROCK inhibitors on EAAT activity and astrocytic morphology. EXPERIMENTAL APPROACH: The functional activity of glutamate transport was determined in murine cultured astrocytes after exposure to the ROCK inhibitors Fasudil (HA-1077) and Y27632 using biochemical, molecular and morphological approaches. Cytochemical analyses assessed changes in astrocytic morphology, F-/G-actin, and localizations of EAAT1/2. RESULTS: Fasudil and Y27632 increased [(3)H]-D-aspartate (D-Asp) uptake into astrocytes, and the action of Fasudil was time-dependent and concentration-related. The rapid stellation of astrocytes (glial fibrillary acidic protein immunocytochemistry) induced by Fasudil was accompanied by reduced phalloidin staining of F-actin and increased V(max) for [(3)H]-D-Asp uptake. Immunoblotting after biotinylation demonstrated that Fasudil increased the expression of EAAT1 and EAAT2 on the cell surface. Immunocytochemistry indicated that Fasudil induced prominent labelling of astrocytic processes by EAAT1/2. CONCLUSION AND IMPLICATIONS: These data show for the first time that ROCK plays a major role in determining the cell surface expression of EAAT1/2, providing new evidence for an association between transporter function and astrocytic phenotype. ROCK inhibitors, via the actin cytoskeleton, effect a consequent elevation of glutamate transporter function - this activity profile may contribute to their beneficial actions in neuropathologies.


Subject(s)
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/analogs & derivatives , Actins/ultrastructure , Astrocytes/drug effects , Excitatory Amino Acid Transporter 1/metabolism , Excitatory Amino Acid Transporter 2/metabolism , Glutamic Acid/metabolism , rho-Associated Kinases/antagonists & inhibitors , 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine/pharmacology , Animals , Aspartic Acid/metabolism , Astrocytes/metabolism , Astrocytes/ultrastructure , Biological Transport , Cells, Cultured , Glial Fibrillary Acidic Protein , Mice , Mice, Inbred C57BL , Nerve Tissue Proteins/metabolism , Prosencephalon/cytology , Up-Regulation
15.
J Affect Disord ; 125(1-3): 336-40, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20609481

ABSTRACT

BACKGROUND: In euthymic bipolar disorder patients, scores on the Mini-Mental State Examination (MMSE) are not abnormal but general functioning remains impaired. Recent studies provide ample evidence that euthymic patients show significant impairment on more comprehensive neuropsychological test batteries. There is no definitive relationship between performance on neuropsychological test batteries and the ability to cope in everyday life. Ecologically valid tests of cognitive function aim to bridge this gap as they use everyday tasks to explore cognitive function. The aims of the study were to examine if euthymic bipolar disorder patients were impaired on ecologically valid tests of cognitive function and measures of general, social and occupational function. We examined the relationships between cognitive impairment and residual symptoms, clinical history, general functioning and employment. METHOD: Cognitive tasks, functional assessments and mood scales were administered to 29 euthymic bipolar disorder patients and 29 matched controls. RESULTS: Patients were impaired on ecologically valid tests of attention, memory and executive function. Patients showed impairment in general, social and occupational functioning. Unemployment was associated with impairment in attention. Memory impairment correlated with number of previous manic episodes. LIMITATIONS: All patients were on psychotropic medication, which may affect cognition. Traditional neuropsychological tests were not performed concurrently with ecologically valid tests. CONCLUSIONS: Ecologically valid tests of cognitive function are sensitive in detecting cognitive impairment in euthymic bipolar disorder. Clinicians should consider using these tests in the recovery phase of bipolar illness, as they may be particularly helpful in showing where rehabilitation should focus.


Subject(s)
Activities of Daily Living/psychology , Bipolar Disorder/diagnosis , Cognition Disorders/diagnosis , Neuropsychological Tests/statistics & numerical data , Social Environment , Adaptation, Psychological , Adult , Aged , Attention , Bipolar Disorder/psychology , Cognition Disorders/psychology , Disability Evaluation , Employment , Executive Function , Female , Humans , Male , Mental Recall , Middle Aged , Psychometrics , Social Adjustment
16.
Neurochem Int ; 51(8): 507-16, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17590480

ABSTRACT

While studies with [(3)H]D-aspartate ([(3)H]d-Asp) illustrate specific interactions with excitatory amino acid transporters (EAATs), new insights into the pharmacological characteristics and localization of specific EAAT subtypes depend upon the availability of novel ligands. One such ligand is [(3)H]-(2S,4R)-4-methylglutamate ([(3)H]4MG) which labels astrocytic EAATs in homogenate binding studies. This study examined the utility of [(3)H]4MG for binding and autoradiography in coronal sections of rat brain. Binding of [(3)H]4MG was optimal in 5mM HEPES buffer containing 96 mM NaCl, pH 7.5. Specific binding of [(3)H]4MG exhibited two components, but was to a single site when glutamate receptor (GluR) sites were masked with kainate (KA; 1 microM): t(1/2) approximately 5 min, K(d) 250 nM and B(max) 5.4 pmol/mg protein. Pharmacological studies revealed that [(3)H]4MG, unlike [(3)H]d-Asp, labeled both EAAT and ionotropic GluR sites. Further studies employed 6-cyano-7-nitroquinoxaline (30 microM) to block GluR sites, but selective EAAT ligands displayed lower potency than expected for binding to transporters relative to drugs possessing mixed transporter/receptor activities. Autoradiography in conjunction with densitometry with [(3)H]4MG and [(3)H]d-Asp revealed wide, but discrete distributions in forebrain; significant differences in binding levels were found in hippocampus, nucleus accumbens and cortical sub-areas. Although EAAT1 and EAAT2 components were detectable using 3-methylglutamate and serine-O-sulphate, respectively, the majority of [(3)H]4MG binding was to KA-related sites. Overall, in tissue sections [(3)H]4MG proved unsuitable for studying the autoradiographic localization of EAATs apparently due to its inability to selectively discriminate Na(+)-dependent binding to Glu transporters.


Subject(s)
Binding, Competitive/drug effects , D-Aspartic Acid/metabolism , Excitatory Amino Acid Transporter 1/metabolism , Glutamates/metabolism , Glutamic Acid/metabolism , Radioligand Assay/methods , Animals , Autoradiography/methods , Binding, Competitive/physiology , Excitatory Amino Acid Agonists/pharmacology , Excitatory Amino Acid Antagonists/pharmacology , Excitatory Amino Acid Transporter 1/drug effects , Excitatory Amino Acid Transporter 2/drug effects , Excitatory Amino Acid Transporter 2/metabolism , Female , Ligands , Rats , Rats, Sprague-Dawley , Receptors, Glutamate/drug effects , Receptors, Glutamate/metabolism , Tritium/metabolism
17.
Br J Pharmacol ; 150(1): 5-17, 2007 Jan.
Article in English | MEDLINE | ID: mdl-17088867

ABSTRACT

L-Glutamate (Glu) is the major excitatory neurotransmitter in the mammalian CNS and five types of high-affinity Glu transporters (EAAT1-5) have been identified. The transporters EAAT1 and EAAT2 in glial cells are responsible for the majority of Glu uptake while neuronal EAATs appear to have specialized roles at particular types of synapses. Dysfunction of EAATs is specifically implicated in the pathology of neurodegenerative conditions such as amyotrophic lateral sclerosis, epilepsy, Huntington's disease, Alzheimer's disease and ischemic stroke injury, and thus treatments that can modulate EAAT function may prove beneficial in these conditions. Recent advances have been made in our understanding of the regulation of EAATs, including their trafficking, splicing and post-translational modification. This article summarises some recent developments that improve our understanding of the roles and regulation of EAATs.


Subject(s)
Amino Acid Transport System X-AG/physiology , Amino Acid Transport System X-AG/classification , Amino Acid Transport System X-AG/drug effects , Animals , Biological Transport , Humans
18.
Clin Exp Pharmacol Physiol ; 29(11): 1018-23, 2002 Nov.
Article in English | MEDLINE | ID: mdl-12366395

ABSTRACT

1. Glutamate transporters (also known as excitatory amino acid transporters or EAAT) are solely responsible for the removal of the excitatory neurotransmitter l-glutamate (Glu) from the extracellular space and, thus, permit normal transmission, as well as preventing cell death due to the excessive activation of Glu receptors. 2. Five subtypes of glutamate transporter (EAAT1-5) exist, possessing distinct pharmacology, cellular localization and modulatory mechanisms. 3. Experimental inhibition of EAAT activity in vitro and in vivo results in increased extracellular concentrations of Glu and in neuronal death via excitotoxicity, highlighting the importance of EAAT in normal excitatory neurotransmission. 4. Dysfunction of EAAT may contribute to the pathology of both acute neuronal injury and chronic neurodegenerative conditions, so correction of EAAT function under these conditions may provide a valuable therapeutic strategy. 5. The present review describes basic pharmacological studies that allow new insights into EAAT function and suggest possible strategies for the therapeutic modulation of EAAT.


Subject(s)
Amino Acid Transport System X-AG/physiology , Central Nervous System/metabolism , Amino Acid Transport System X-AG/classification , Amino Acid Transport System X-AG/metabolism , Animals , Brain/metabolism , Humans , Neurodegenerative Diseases/metabolism
20.
J Neurochem ; 77(5): 1218-25, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11389172

ABSTRACT

[(3)H](2S,4R)-4-Methylglutamate ([(3)H]4MG), used previously as a ligand for low-affinity kainate receptors, was employed to establish a binding assay for glutamate transporters (GluTs), as 4MG has also been shown to have affinity for the glial GluTs, GLT1 and GLAST. In rat brain membrane homogenates in the presence of Na(+) ions at 4 degrees C, specific binding of [(3)H]4MG was rapid and saturable (t(1/2) approximately 15 min), representing > 90% of total binding. Dissociation of [(3)H]4MG occurred in a biphasic manner, however, saturation studies and Scatchard analysis indicated a single site of binding (n(H) = 0.85) and a K(d) of 6.2 +/- 0.8 microM with a B(max) of 111.8 +/- 23.8 pmol/mg protein. Specific binding of [(3)H]4MG was Na(+)-dependent and inhibited by K(+) and HCO(3-). Pharmacological inhibition with compounds acting at GluTs revealed that Glu, D- and L-aspartate, L-serine-O-sulfate and Ltrans-pyrrolidine-2,4-dicarboxylate fully displaced specific binding. Drugs having preferential affinity for GLT1, kainate, dihydrokainate and Lthreo-3-methylglutamate, all inhibited approximately 40% of specific binding. The inhibition pattern of L-serine-O-sulfate in the presence of a saturating concentration of dihydrokainate was suggestive of [(3)H]4MG also labelling GLAST. 6-Cyano-7-nitroquinoxaline, a kainate receptor antagonist, and a range of Glu receptor agonists and antagonists failed to significantly inhibit [(3)H]4MG binding. The pharmacological profile of binding of [(3)H]4MG resembled that found for [(3)H]D-aspartate, a ligand specific for GluTs, reinforcing the hypothesis that [(3)H]4MG was labelling GluTs in this assay. Together, these data illustrate the development of an efficient, economic binding assay that is suitable for the characterization of different subtypes of GLuTs.


Subject(s)
ATP-Binding Cassette Transporters/metabolism , Glutamates/pharmacology , Amino Acid Transport System X-AG , Animals , Aspartic Acid/metabolism , Binding, Competitive/drug effects , Female , Kinetics , Ligands , Membranes/drug effects , Membranes/metabolism , Nerve Tissue Proteins/metabolism , Rats , Rats, Sprague-Dawley
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