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2010-01-01
Proteins of the G-protein coupled receptor (GPCR) family present numerous attractive targets for rational drug design, but also a formidable challenge for identification and conformational modeling of their 3D structure. A recently performed assessment of blind predictions of adenosine A2a receptor (AA2AR) structure in complex with ZM241385 (ZMA) antagonist provided a first example of unbiased evaluation of the current modeling algorithms on a GPCR target with 30% sequence identity to the closest structural template. Several of the 29 groups participating in this assessment exercise (Michino et al., doi: 10.1038/nrd2877) successfully predicted the overall position of the ligand ZMA in the AA2AR ligand binding pocket, however models from only three groups captured more than 40% the ligand-r...
2010-01-01
Proteins of the G-protein coupled receptor (GPCR) family present numerous attractive targets for rational drug design, but also a formidable challenge for identification and conformational modeling...Full Text Available
2010-01-01
Full Text Available.Proteins of the G-protein coupled receptor (GPCR) family present numerous attractive targets for rational drug design, but also a formidable challenge for identification and conformational modeling of their 3D structure. A recently performed assessment of blind predictions of adenosine A2a receptor (AA2AR) structure in complex with ZM241385 (ZMA) antagonist provided a first example of unbiased evaluation of the current modeling algorithms on a GPCR target with ~30% sequence identity to the closest structural template. Several of the 29 groups participating in this assessment exercise (Michino et al., doi:10.1038/nrd2877) successfully predicted the overall position of the ligand ZMA in the AA2AR ligand binding pocket, however models from only three groups captured more than 40% of the ligand-receptor contacts.Here we describe two of these top performing approaches, in which all-atom models of the AA2AR were generated by homology modeling followed by ligand guided backbone ensemble receptor optimization (LiBERO). The resulting AA2AR-ZMA models, along with the best models from other groups are assessed here for their virtual ligand screening (VLS) performance on a large set of GPCR ligands.We show that ligand guided optimization was critical for improvement of both ligand-receptor contacts and VLS performance as compared to the initial raw homology models. The best blindly predicted models performed on par with the crystal structure of AA2AR in selecting known antagonists from decoys, as well as from antagonists for other adenosine subtypes and AA2AR agonists. These results suggest that despite certain inaccuracies, the optimized homology models can be useful in the drug discovery process.
2007-01-01
Adenosine is a neuromodulator with complex effects on pain pathways. Mice lacking the adenosine A2A receptor are hypoalgesic, and have altered analgesic responses to receptor-selective opioid agonists. These and other findings suggest a role for the adenosine A2A receptor in sensitizing afferent fibres projecting to the spinal cord. To test this hypothesis formalin (20ml, 5%) was injected into the paw and nociceptive responses were measured in wildtype and adenosine A2A receptor knockout mice. There was a significant reduction in nociception associated with sensory nerve activation in the knockout mice as measured by time spent biting/licking the formalin-injected paw and number of flinches seen during the first phase, but only the number of flinches was reduced during the second inflammat...
Thermostabilization of the Neurotensin Receptor NTS1
2009-01-01
Structural studies on G-protein-coupled receptors have been hampered for many years by their instability in detergent solution and by the number of potential conformations that receptors can adopt. Recently, the structures of the β1 and β2 adrenergic receptors and the adenosine A2a receptor were determined in the antagonist-bound state, a receptor conformation that is thought to be more stable than the agonist-bound state. In contrast to these receptors, the neurotensin (NT) receptor NTS1 is much less stable in detergent solution. We have therefore used a systematic mutational approach coupled with activity assays to identify receptor mutants suitable for crystallization, both alone and in complex with the peptide agonist NT. The best receptor mutant NTS1-7m contained four point mutation...
Adenosine receptors have been implicated as important mediators of a diversity of physiological processes throughout the body. These receptors are members of the G protein-coupled receptor superfamily, a class of cell-surface receptors that, when activated, couple to a heterotrimeric G protein complex to effect signal transduction. Four different subtypes of adenosine receptor have been identified through molecular cloning and subsequent pharmacological and biochemical analyses. Of these subtypes, the Al and A2a receptors have been mapped to chromosome 22q11.2-q13.1 and 11q11-q13, respectively. The A3 receptor has been localized to chromosome 3 in the mouse, by interspecific backcross analysis, suggesting a human chromosomal localization of 1p13 from known mouse human linkage homologies. In determining the chromosomal localization of the A2a receptor, a minor hybridization peak was detected on chromosome 10q25.3-q26.3, and the authors of this study concluded that this site was likely to correspond to an adenosine A2-like receptor. With the molecular identification of the adenosine A2b receptor, the hybridization site on chromosome 10 was assigned to the A2b receptor (MIM 102777). We have used fluorescence in situ hybridization (FISH) and PCR screening of a somatic cell hybrid panel to determine the true chromosomal localization of the A2b adenosine receptor subtype. 12 refs., 1 fig., 1 tab.
1995-01-20
Adenosine receptors have been implicated as important mediators of a diversity of physiological processes throughout the body. These receptors are members of the G protein-coupled receptor superfamily, a class of cell-surface receptors that, when activated, couple to a heterotrimeric G protein complex to effect signal transduction. Four different subtypes of adenosine receptor have been identified through molecular cloning and subsequent pharmacological and biochemical analyses. Of these subtypes, the Al and A2a receptors have been mapped to chromosome 22q11.2-q13.1 and 11q11-q13, respectively. The A3 receptor has been localized to chromosome 3 in the mouse, by interspecific backcross analysis, suggesting a human chromosomal localization of 1p13 from known mouse human linkage homologies. In determining the chromosomal localization of the A2a receptor, a minor hybridization peak was detected on chromosome 10q25.3-q26.3, and the authors of this study concluded that this site was likely to correspond to an adenosine A2-like receptor. With the molecular identification of the adenosine A2b receptor, the hybridization site on chromosome 10 was assigned to the A2b receptor (MIM 102777). We have used fluorescence in situ hybridization (FISH) and PCR screening of a somatic cell hybrid panel to determine the true chromosomal localization of the A2b adenosine receptor subtype. 12 refs., 1 fig., 1 tab.
Localization of the adenosine A1 receptor subtype gene (ADORA1) to chromosome 1q32.1
Adenosine, acting through its receptors, exerts effects on almost all organ systems, influencing a diversity of physiological responses, including the inhibition of neurotransmitter release, the modulation of cardiac rhythmicity and contractility, and the potentiation of IgE-dependent mediator release. Adenosine receptors belong to the G protein-coupled receptor superfamily, a class of cell-surface receptors that, when activated, couple to a heterotrimeric G protein complex to effect signal transduction. Molecular cloning and subsequent pharmacological and biochemical analyses have led to the identification of four different subtypes of adenosine receptor. The A3 receptor has been localized to chromosome 3 in the mouse by interspecific backcross analysis, suggesting a human chromosomal localization of 1p13 from known mouse-human linkage homologies. We have previously mapped the A2b adenosine receptor subtype to chromosome 17p11.2-p12 using fluorescence in situ hybridization (FISH) and PCR-based screening of somatic cell hybrid DNAs. A previous report has concluded that the Al and A2a receptor subtypes are localized on chromosome 22q11.2-q13.1 and 11q11-q13, respectively, but conflicts with that of MacCollin et al., who have mapped the A2a gene to chromosome 22. In this report, we show that the human A1 adenosine receptor subtype does not map to chromosome 22q11.2-q13.1, but is instead localized on chromosome 1q32. 13 refs., 1 fig.
A2A adenosine receptor antagonists protect the striatum against rotenone-induced neurotoxicity
2009-01-01
Adenosine A2A receptor has emerged as an attractive non-dopaminergic target in the experimental pharmacological therapy for Parkinson's disease (PD). Moreover, it has been postulated that A2A adenosine receptor antagonists exert neuroprotective effects in experimental models of PD and progressive supranuclear palsy (PSP). Interestingly, in both these pathological conditions a deficit of mitochondrial complex I has been found. Thus, utilizing extracellular and intracellular recordings from corticostriatal brain slices, we have tested the possible neuroprotective action of two A2A receptor antagonists, ST1535 and ZM241385, on the irreversible electrophysiological effects induced by the acute application of rotenone, a pesticide acting as a selective inhibitor of mitochondrial complex I activ...
Localization of the adenosine A1 receptor subtype gene (ADORA1) to chromosome 1q32.1
1995-03-20
Adenosine, acting through its receptors, exerts effects on almost all organ systems, influencing a diversity of physiological responses, including the inhibition of neurotransmitter release, the modulation of cardiac rhythmicity and contractility, and the potentiation of IgE-dependent mediator release. Adenosine receptors belong to the G protein-coupled receptor superfamily, a class of cell-surface receptors that, when activated, couple to a heterotrimeric G protein complex to effect signal transduction. Molecular cloning and subsequent pharmacological and biochemical analyses have led to the identification of four different subtypes of adenosine receptor. The A3 receptor has been localized to chromosome 3 in the mouse by interspecific backcross analysis, suggesting a human chromosomal localization of 1p13 from known mouse-human linkage homologies. We have previously mapped the A2b adenosine receptor subtype to chromosome 17p11.2-p12 using fluorescence in situ hybridization (FISH) and PCR-based screening of somatic cell hybrid DNAs. A previous report has concluded that the Al and A2a receptor subtypes are localized on chromosome 22q11.2-q13.1 and 11q11-q13, respectively, but conflicts with that of MacCollin et al., who have mapped the A2a gene to chromosome 22. In this report, we show that the human A1 adenosine receptor subtype does not map to chromosome 22q11.2-q13.1, but is instead localized on chromosome 1q32. 13 refs., 1 fig.
2007-01-01
Adenosine A2A receptors are preferentially expressed in rat striatum, where they are concentrated in dendritic spines of striatopallidal medium spiny neurons and exist in a heteromeric complex with D2 dopamine (DA) receptors. Behavioral and biochemical studies indicate an antagonistic relationship between A2A and D2 receptors. Previous studies have demonstrated that food-restricted (FR) rats display behavioral and striatal cellular hypersensitivity to D1 and D2 DA receptor stimulation. These alterations may underlie adaptive, as well as maladaptive, behaviors characteristic of the FR rat. The present study examined whether FR rats are hypersensitive to the A2A receptor agonist, CGS-21680. In Experiment 1, spontaneous horizontal motor activity did not differ between FR and ad libitum fed (A...
http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050901.161632
Chapter 1 of thesis is a literature review of adenosine research. The central importance of the contributions of both classical pharmacology and, more recently, molecular biology to adenosine research is demonstrated. These disciplines have enabled the classification and characterisation of adenosine receptors and as well an understanding of the physiological significance of endogenous adenosine. The significant benefits of developing therapeutics for regulation of the diverse physiological functions of adenosine, by regulation of adenosine receptors, is outlined. For this therapeutic potential to be realised both high affinity and subtype selective adenosine agonists and antagonists are required. The structure-activity relationships for agonists and xanthine antagonists are discussed. The assimilation of these structure-activity relationships have guided the development of ligand based models of the adenosine receptor pharmacophore. The 'flipped', 'N6-C8' and 'three binding domain' models were described. These models aim to direct the future design of high affinity and selective ligands for adenosine receptors. The development of receptor based models by modelling of the receptor-ligand complex is also presented. The main body of this thesis presents a study of the structure-activity relationships for pyrazolo(3,4-d) pyrimidines binding to adenosine Ai and A2a receptors. Prior to this study few non-xanthine adenosine antagonists had been well defined or optimised in terms of structure-activity relationships. However, the value of such ligands is immense, facilitating further definition of structural requirements for high affinity and selective adenosine receptor binding. These ligands should complement existing agonists and xanthine antagonists in developing an understanding of adenosine receptor binding. The experimental approach to development of the lead compound of this study, a-(6-(l'-carbamoylethylthio)- l-phenylpyrazolo(3,4-d)pyrimidin-4-ylthio)propanamide (5), is outlined in Chapter 2 of this thesis. 5 is substituted at C-4, C-6 and N-i of the pyrazolo(3,4-d)pyrimidine heterocycle. The experimental approach to optiniising 5 was approached in a rational manner, requiring an iterative approach i.e. design of generation I target compounds --synthesis -- biological evaluation -- structure-activity relationships -- design of generation II target compounds, etc. Chapters 3, 4 and 5 of this thesis describe this experimental approach as it relates to optimising the lead compound, 5, for adenosine receptor affinity and subtype selectivity. The importance of receptor interactions with multiple ligand domains, to achieve both potency and selectivity, was recognised so that optimisation of the C-4, C-6 and N-i substituents of the lead compound was targeted and achieved. Previous structure-activity studies with agonists and xanthine antagonists have concentrated on modifying a single ligand domain. Chapter 3 presents twelve generation I target compounds to examine C-4 and C-6 substituent structure-activity relationships. Chapter 4 presents twelve generation II target compounds to further examine C-4 and C-6 substituent structure-activity relationships. Chapter 5 presents sixteen generation ifi target compounds to examine N-I substituent structure-activity relationships. A major outcome from the research presented in these chapters was the development of highly potent and highly selective ligands for the adenosine A1 receptor subtype. a(4-Methylamino- I -phenylpyrazolo(3,4-d)pyrimidin-6-ylthio)hexanamide (29) was the most potent ligand at the Ai receptor identified in this study, and is one of the most potent Ai selective antagonists ever reported. 29 has an A1 K1 value of 0.745±0.045 nM and is 332-fold selective for the A1 receptor over the A2a receptor. a-(1-Phenyl-4-propylthiopyrazolo(3,4-d)pyrimidin-6-ylthio)butanainide (27) was the most selective ligand of this study. It is four orders of magnitude selective for the A1 receptor (up to 16900-fold), and one of the most selective antagonists ever reported. This high selectivity has been achieved with the maintenance of good A1 affinity (A1 K1 = 29.5±6.6 nM). These results prove the value of modifying multiple substituents of adenosine receptor ligands, generating ligands which bind with high potency and selectivity to adenosine Al receptors compared to adenosine A2a receptors. Publisher: Griffith University. School of Science Language: en Rights: http://www.gu.edu.au/disclaimer.html); Copyright Sally-Ann Poulsen
Adenosine receptor agonists for promotion of dermal wound healing
2009-01-01
Wound healing is a dynamic and complex process that involves a well-coordinated, highly regulated series of events including inflammation, tissue formation, revascularization and tissue remodeling. However, this orderly sequence is impaired in certain pathophysiological conditions such as diabetes mellitus, venous insufficiency, chronic glucocorticoid use, aging and malnutrition. Together with proper wound care, promotion of the healing process is the primary objective in the management of chronic poorly healing wounds. Recent studies have demonstrated that A2A adenosine receptor agonists promote wound healing in normal and diabetic animals and one such agonist, Sonedenoson, is currently being evaluated as a prospective new therapy of diabetic foot ulcers. We will review the mechanisms by ...
2010-01-01
Adenosine can show anti-inflammatory as well as pro-inflammatory activities. The contribution of the specific adenosine receptor subtypes in various cells, tissues and organs is complex. In this study, we examined the effect of the adenosine A2A receptor agonist CGS 21680 and the A2BR antagonist PSB-1115 on acute inflammation induced experimentally by 2,4,6-trinitrobenzenesulfonic acid (TNBS) on rat ileum/jejunum preparations. Pre-incubation of the ileum/jejunum segments with TNBS for 30 min resulted in a concentration-dependent inhibition of acetylcholine (ACh)-induced contractions. Pharmacological activation of the A2AR with CGS 21680 (0.1–10 µM) pre-incubated simultaneously with TNBS (10 mM) prevented concentration-dependently the TNBS-induced inhibition of the ACh contractions. S...
2007-01-01
This review summarizes recent developments that have contributed to understand how adenosine receptors, particularly A2A receptors, modulate brain injury in various animal models of neurological disorders, including Parkinsons disease (PD), stroke, Huntingtons disease (HD), multiple sclerosis, Alzheimers disease (AD) and HIV-associated dementia. It is clear that extracellular adenosine acting at adenosine receptors influences the functional outcome in a broad spectrum of brain injuries, indicating that A2ARs may modulate some general cellular processes to affect neuronal cells death. Pharmacological, neurochemical and molecular/genetic approaches to the complex actions of A2A receptors in different cellular elements suggest that A2A receptor activation can be detrimental or protective afte...
2007-01-01
The aim of this review is to summarize and critically discuss the complex role played by adenosine A2A receptors (A2ARs) in Huntingtons disease (HD). Since A2ARs are mainly localized on the neurons, which degenerate early in HD, and given their ability to stimulate glutamate outflow and inflammatory gliosis, it was hypothesized that they could be involved in the pathogenesis of HD, and that A2AR antagonists could be neuroprotective. This was further sustained by the demonstration that A2ARs and underlying signaling systems undergo profound changes in cellular and animal models of HD. More recently, however, the equation A2A receptor blockade=neuroprotection has appeared too simplistic. First, it is now definitely clear that, besides mediating `bad' responses (for example, stimulation of gl...
http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20061120.095902
The sphincter of Oddi (SO) is a neuromuscular structure located at the junction of the bile and pancreatic ducts with the duodenum. The primary functions of the SO are to regulate the delivery of bile and pancreatic juice into the duodenum, and to prevent reflux of duodenal contents into the biliary and pancreatic systems. Neural, hormonal or functional disturbances of biliary motility can lead to painful and sometimes life threatening clinical conditions, such as SO dysfunction and acute pancreatitis. Clearly understanding the regulation of biliary and duodenal motility patterns is necessary and may provide useful pharmacological sites for drug development to aid in the treatment of these diseases. Spontaneous activity of the SO is regulated by complex interactions between the enteric nervous system, hormones, possibly interstitial cells of Cajal and other bioactive agents, together with modulation via neural reflexes between the duodenum, common bile duct/gallbladder, and stomach. Purines are one group of neurotransmitters/regulatory agents that have been shown to effect gastrointestinal motility, however their functions in the regulation of SO motility have not been elucidated. The studies described in this thesis used in vitro organ bath techniques and in vivo preparations to determine the effects of exogenous purines on possum SO and duodenal motility. The possum SO has been extensively characterized and is an excellent model for motility studies. In vitro, exogenous adenosine was found to decrease spontaneous activity in both the SO and duodenum. In contrast exogenous ATP induced both excitatory and inhibitory responses in the SO and duodenum. Interestingly, the adenosine and ATP-induced effects were predominantly exhibited by the proximal portion of the SO (proximal-SO), with no or little effect observed in the distal portion of the SO (distal-SO). These data support the hypothesis that the SO is comprised of different functional components that can act differently in response to certain stimuli, and highlights the importance of studying each of the SO components. Agonists and antagonists, together with immunohistochemical studies, were used in an attempt to identify the P1 and P2 receptor sub-types responsible for mediating the adenosine- and ATP-induced responses. In the duodenum the adenosine-induced decrease in spontaneous activity was likely to be mediated by A2A and A3 receptors, but the receptors mediating the proximal-SO response could not be identified. In the duodenum ATP induced a complex non-neural response consisting of a P2X1, and P2Y2 and/or P2Y4 mediated immediate inhibition. This was followed by a return to baseline activity or small excitation. The response concluded with a late inhibitory response, likely to be mediated by P2Y1 receptors, but the effects of other P2Y receptors could not be excluded. In contrast, ATP application to the proximal-SO evoked a partially neurally mediated early excitation, likely via P2X receptors, followed by an inhibition of activity, likely via activation of non-neural P2Y2 and/or P2Y4 receptors. In vivo studies with exogenous application of adenosine and ATP to the SO activated neural pathways to produce increased motor activity. Characterisation of these neural pathways found ATP and/or adenosine to activate excitatory cholinergic motor neurons. ATP also activated an inhibitory nicotinic/nitrergic pathway. This is the first comprehensive investigation of the possible involvement of purines in the regulation of SO motility. These studies demonstrate that exogenous purines influence SO and duodenal motility, inducing complex neural and non-neural responses, acting via multiple P1 and P2 receptors. It now remains to be determined if endogenously released purines induce similar responses, together with elucidation and location of the receptor sub-types involved. Publisher: Flinders University. School of Medicine Language: en Rights: http://www.flinders.edu.au/disclaimer/); Copyright Charmaine Michelle Woods
2005-01-01
Dopamine (DA) and other receptors physically interact in the plasma membrane of basal ganglia neurons forming receptor mosaics (RMs). Two types of RMs are discussed, homomers formed only by DA-receptor (DA-R) subtypes and heteromers formed by DA-R associated with other receptors, such as A2A, A1, mGluR5, N-methyl-d-aspartate (NMDA), γ-aminobutryic acid (GABA)-A, and α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid. By being part of horizontal molecular networks, RMs tune multiple effector systems already at membrane level, such as G protein regulated inward rectifying potassium channels and dopamine transporter activity. Also, ligand-gated ion channels such as GABA-A and NMDA receptors are modulated by DA-R, e.g., in the striatal GABA output neurons through the formation of heterome...
Hypoxia induces neurite outgrowth in PC12 cells that is mediated through adenosine A2A receptors
2005-01-01
Development of the nervous system is a complex process, involving coordinated regulation of diverse cellular processes including proliferation, differentiation and synaptogenesis. Disturbances to brain development such as pre- and perinatal hypoxia have been linked to behavioural and late onset of neurological disorders. This study examines the effect of hypoxia on neurite outgrowth in PC12 cells. Hypoxia not only caused a rapid induction of neurite outgrowth, but also synergistically enhanced nerve growth factor (NGF)-induced neurite outgrowth up to 24 h. Transactivation of TrkA receptors was ruled out since the TrkA inhibitor K252a did not block hypoxia-induced neurite outgrowth. Adenosine deaminase prevented hypoxia-induced neurite outgrowth indicating that the effect is mediated by ade...
2007-01-01
Abstract The neuroprotective potential of cannabinoids has been examined in rats with striatal lesions caused by 3-nitropropionic acic (3NP), an inhibitor of mitochondrial complex II. We used the CB1 agonist arachidonyl-2-chloroethylamide (ACEA), the CB2 agonist HU-308, and cannabidiol (CBD), an antioxidant phytocannabinoid with negligible affinity for cannabinoid receptors. The administration of 3NP reduced GABA contents and also mRNA levels for several markers of striatal GABAergic projection neurons, including proenkephalin (PENK), substance P (SP) and neuronal-specific enolase (NSE). We also found reductions in mRNA levels for superoxide dismutase-1 (SOD-1) and -2 (SOD-2), which indicated that 3NP reduced the endogenous antioxidant defences. The administration of CBD, but not ACEA or H...
http://hdl.handle.net/2440/55915
© 2005 Taylor & FrancisG-protein coupled receptors (GPCRs) form a ternary complex of agonist, receptor and G-proteins during primary signal transduction at the cell membrane. Downstream signalling is thought to be preceded by the process of dissociation of Gα and Gβγ subunits, thus exposing new surfaces to interact with downstream effectors. We demonstrate here for the first time, the dissociation of heterotrimeric G-protein subunits (i.e., Gα and Gβγ) following agonist-induced GPCR (α2A-adrenergic receptor; α2A-AR) activation in a cell-free assay system. α2A-AR membranes were reconstituted with the G-proteins (±hexahistidine-tagged) Gαi1 and Gβ1γ2 and functional signalling was determined following activation of the reconstituted receptor:G-protein complex with the potent agonist UK-14304, and [35S]GTPγS. In the presence of Ni2+-coated agarose beads, the activated his-tagged Gαi1his-[35S]GTPγS complex was captured on the Ni2+-presenting surface. When his-tagged Gβ1γ2 (Gβ1γ2his) was used with Gαi1, the [35S]GTPγS-bound Gαi1 was not present on the Ni2+-coated beads, but rather, it was separated from the β1γ2(his)-beads, demonstrating receptor-induced dissociation of Gα and Gβγ subunits. Treatment of the reconstituted α2A-AR membranes containing Gβ1γ2his:Gαi1 with imidazole confirmed the specificity for the Ni2+:G-protein surface dissociation of Gαi1 from Gβ1γ2his. These data demonstrate for the first time, the complete dissociation of the G-protein subunits and extend observations on the role of G-proteins in the assembly and disassembly of the ternary complex in the primary events of GPCR signalling.Wayne R. Leifert, Amanda L. Aloia, Olgatina Bucco, and Edward J. McMurchie Publisher: Taylor & Francis Contributor: School of Molecular and Biomedical Science Other identifier: Molecular Membrane Biology, 2005; 22(6):507-517; 0968-7688; 0020092099; 10.1080/09687860500370604; 000234127000005 Language: en
Workshop on measurement quality assurance for ionizing radiation: Proceedings
This workshop was held to review the status of secondary level calibration accreditation programs, review related measurement accreditation programs, document lessons learned, and to present changes in programs due to new national priorities involving radioactivity measurements. Contents include: fundamentals of measurement quality assurance (MQA), standards for MQA programs; perspectives and policies; complete MQA programs; future MQA programs; QA/QC programs--radioactivity; QA/QC programs--dosimetry; laboratory procedures for QA/QC; in-house control of reference dosimetry laboratories; in-house controls of radioactivity laboratories; and poster session. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.
Accepted mechanism is impaired immuncompetence In a mouse model, a benign strain of coxsackievirus B3 became virulent and caused myocarditis in selenium- and vitamin E-deficient mice.
Accepted mechanism is impaired immuncompetence In a mouse model, a benign strain of coxsackievirus B3 became virulent and caused myocarditis in selenium- and vitamin E-deficient mice.
US Army primary radiation standards complex
1993-12-31
This paper describes the U.S. Army Primary Radiation Standards Complex (PRSC) to be constructed at Redstone Arsenal, Alabama. The missions of the organizations to be located in the PRSC are described. The health physics review of the facility design is discussed. The radiation sources to be available in the PRSC and the resulting measurement capabilities of the Army Primary Standards Laboratory Nucleonics section are specified. Influence of the National Voluntary Laboratory Accrediation Program (NVLAP) accreditation criteria on facility design and source selection is illustrated.
Tuning microbial hosts for membrane protein production
The last four years have brought exciting progress in membrane protein research. Finally those many efforts that have been put into expression of eukaryotic membrane proteins are coming to fruition...Full Text Available
Tuning microbial hosts for membrane protein production
Full Text Available.The last four years have brought exciting progress in membrane protein research. Finally those many efforts that have been put into expression of eukaryotic membrane proteins are coming to fruition and enable to solve an ever-growing number of high resolution structures. In the past, many skilful optimization steps were required to achieve sufficient expression of functional membrane proteins. Optimization was performed individually for every membrane protein, but provided insight about commonly encountered bottlenecks and, more importantly, general guidelines how to alleviate cellular limitations during microbial membrane protein expression. Lately, system-wide analyses are emerging as powerful means to decipher cellular bottlenecks during heterologous protein production and their use in microbial membrane protein expression has grown in popularity during the past months.This review covers the most prominent solutions and pitfalls in expression of eukaryotic membrane proteins using microbial hosts (prokaryotes, yeasts), highlights skilful applications of our basic understanding to improve membrane protein production. Omics technologies provide new concepts to engineer microbial hosts for membrane protein production.
This treatability study was conducted by Pacific Northwest National Laboratory (PNNL), at the request of the U. S. Environmental Protection Agency (EPA) Region 2, to evaluate the feasibility of using in situ treatment technologies for chromate reduction and immobilization at the Puchack Well Field Superfund Site in Pennsauken Township, New Jersey. In addition to in situ reductive treatments, which included the evaluation of both abiotic and biotic reduction of Puchack aquifer sediments, natural attenuation mechanisms were evaluated (i.e., chromate adsorption and reduction). Chromate exhibited typical anionic adsorption behavior, with greater adsorption at lower pH, at lower chromate concentration, and at lower concentrations of other competing anions. In particular, sulfate (at 50 mg/L) suppressed chromate adsorption by up to 50%. Chromate adsorption was not influenced by inorganic colloids.
2006-11-13
This treatability study was conducted by Pacific Northwest National Laboratory (PNNL), at the request of the U. S. Environmental Protection Agency (EPA) Region 2, to evaluate the feasibility of using in situ treatment technologies for chromate reduction and immobilization at the Puchack Well Field Superfund Site in Pennsauken Township, New Jersey. In addition to in situ reductive treatments, which included the evaluation of both abiotic and biotic reduction of Puchack aquifer sediments, natural attenuation mechanisms were evaluated (i.e., chromate adsorption and reduction). Chromate exhibited typical anionic adsorption behavior, with greater adsorption at lower pH, at lower chromate concentration, and at lower concentrations of other competing anions. In particular, sulfate (at 50 mg/L) suppressed chromate adsorption by up to 50%. Chromate adsorption was not influenced by inorganic colloids.
The Role of Adenosine A2A Receptor Signaling in Bronchiolitis Obliterans
2009-10-01
Full Text Available.BackgroundBinding of adenosine to the anti-inflammatory Gs-coupled adenosine 2A receptor (A2AR) inhibits the activity of most inflammatory cells. Extensive preclinical evidence exists for the use of A2AR agonists in the prevention of acute ischemia-reperfusion injury. Activation of A2ARs on lymphocytes and antigen-presenting cells also attenuates the alloimmune response. Because ischemia-reperfusion injury and alloimmunity are risk factors for the development of bronchiolitis obliterans (BO), the objective of this study was to determine the effect of A2AR signaling on tracheal rejection in a mouse model of BO.MethodsA non-revascularized heterotopic tracheal model across a total alloantigenic mismatch was used to study A2AR signaling in a mouse model of BO. Tracheal transplants were performed using Balb/c donors into wild-type or A2AR knockout C57BL/6 recipient mice. Another group of Balb/c transplants into C57BL/6 recipients were also treated with a selective A2AR agonist. Tracheas were assessed at 3, 7, 12, 21, and 28 days after transplantation by hematoxylin and eosin staining, immunohistochemical staining, and collagen staining.ResultsCompared with allograft tracheas in wild-type recipients, allografts in A2AR knockout recipients had increased inflammation and more severe BO development. Recipient wild-type mice treated with a selective A2AR agonist were significantly protected from lymphocyte infiltration and luminal occlusion, but fibro-obliteration still developed by 28 days after transplantation.ConclusionsEndogenous adenosine signals through the A2AR to attenuate inflammatory and immune factors involved in BO development. Synthetic A2AR agonists may provide a novel treatment strategy to prevent BO.
The Role of Adenosine A2A Receptor Signaling in Bronchiolitis Obliterans
2009-10-01
BackgroundBinding of adenosine to the anti-inflammatory Gs-coupled adenosine 2A receptor (A2AR) inhibits the activity of most inflammatory cells. Extensive...Full Text Available
2009-01-01
Full Text Available. Background. We studied the effect of fast induction of cardiac arrest with denosine on myocardial bax and bcl-2 expression. Methods and Results. 40 elective CABG patients were allocated into two groups. The adenosine group (n = 20) received 250 μg/kg adenosine into the aortic root followed by blood potassium cardioplegia. The control group received potassium cardioplegia in blood. Bcl-2 and bax were measured. Bax was reduced in the postoperative biopsies (1.38 versus 0.47, P = .002) in the control group. Bcl-2 showed a reducing tendency (0.14 versus 0.085, P = .07). After the adenosine treatment, the expression of both bax (0.52 versus 0.59, P = .4) and bcl-2 (0.104 versus 0.107, P = .4) remained unaltered after the operation. Conclusion. Open heart surgery is associated with rapid reduction in the expression of apoptosis regulating genes bax and bcl-2. Fast Adenosine induction abolished changes in their expression.
2009-01-01
Background. We studied the effect of fast induction of cardiac arrest with denosine on myocardial bax and bcl-2 expression. Methods and Results. 40 elective CABG...Full Text Available
September 2006 25 The NCI-Frederick Poster NCI-Frederick Welcomes New Staff New Faces at NCI-Frederick Seventy-fi ve people joined our Facility in April, May, and June 2006.
1993-12-31
This paper presents an overview of the procedures and requirements for accreditation under the Secondary Calibration Laboratory for Ionizing Radiation Program (SCLIR LAP). The requirements for a quality system, proficiency testing and the onsite assessment are discussed. The purpose of the accreditation program is to establish a network of secondary calibration laboratories that can provide calibrations traceable to the primary national standards.
Scripps Research scientists define structure of important neurological receptor
Scientists from the Scripps Research Institute have determined the structure of an adenosine receptor that plays a critical role in a number of important physiological processes including pain, breathing, and heart ...
Role of platelets in neuroinflammation: a wide-angle perspective
ObjectivesThis review summarizes recent developments in platelet biology relevant to neuroinflammatory disorders. Multiple sclerosis (MS) is taken as the "Poster Child" of these...Full Text Available
Role of platelets in neuroinflammation: a wide-angle perspective
Full Text Available.ObjectivesThis review summarizes recent developments in platelet biology relevant to neuroinflammatory disorders. Multiple sclerosis (MS) is taken as the "Poster Child" of these disorders but the implications are wide. The role of platelets in inflammation is well appreciated in the cardiovascular and cancer research communities but appears to be relatively neglected in neurological research.OrganizationAfter a brief introduction to platelets, topics covered include the matrix metalloproteinases, platelet chemokines, cytokines and growth factors, the recent finding of platelet PPAR receptors and Toll-like receptors, complement, bioactive lipids, and other agents/functions likely to be relevant in neuroinflammatory diseases. Each section cites literature linking the topic to areas of active research in MS or other disorders, including especially Alzheimer's disease.ConclusionThe final section summarizes evidence of platelet involvement in MS. The general conclusion is that platelets may be key players in MS and related disorders, and warrant more attention in neurological research.
Rheumatoid arthritis: GWAS or TMI?
Genome-wide association studies are the most comprehensive and straightforward approach to teasing out the identity of genetic polymorphisms associated with any given disease or characteristic. With...Full Text Available
Rheumatoid arthritis: GWAS or TMI?
Full Text Available.Genome-wide association studies are the most comprehensive and straightforward approach to teasing out the identity of genetic polymorphisms associated with any given disease or characteristic. With the availability of DNA banks from large cohorts of ethnically matched patients and healthy individuals it is now possible to define even marginal genetic associations between genetic polymorphisms and diseases. As increasing numbers of these studies are carried out and as associations with smaller and smaller risks are identified, there is the growing concern that the findings will be of increasingly marginal value. Thus, the glut of new genetic associations is rapidly overwhelming our interest in the results, a situation that could be described as TMI (too much information). Recent genetic association studies in rheumatoid arthritis suggest that we may be approaching the TMI stage of genome-wide association studies.
Research sheds new light on heroin addiction
Researchers from the Howard Florey Institute in Melbourne have identified a factor that may contribute towards the development of heroin addiction by manipulating the adenosine A2A receptor, which plays a major role in ...
Remedial investigation/feasibility study report for Lower Watts Bar Reservoir Operable Unit
This document is the combined Remedial Investigation and Feasibility Study Report for the lower Watts Bar Reservoir (LWBR) Operable Unit (OU). The LWBR is located in Roane, Rhea, and Meigs counties, Tennessee, and consists of Watts Bar Reservoir downstream of the Clinch river. This area has received hazardous substances released over a period of 50 years from the US Department of Energy`s Oak Ridge Reservation (ORR), a National Priority List site established under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). As required by this law, the ORR and all off-site areas that have received contaminants, including LWBR, must be investigated to determine the risk to human health and the environment resulting from these releases, the need for any remedial action to reduce these risks, and the remedial actions that are most feasible for implementation in this OU. Contaminants from the ORR are primarily transported to the LWBR via the Clinch River. There is little data regarding the quantities of most contaminants potentially released from the ORR to the Clinch River, particularly for the early years of ORR operations. Estimates of the quantities released during this period are available for most radionuclides and some inorganic contaminants, indicating that releases 30 to 50 years ago were much higher than today. Since the early 1970s, the release of potential contaminants has been monitored for compliance with environmental law and reported in the annual environmental monitoring reports for the ORR.
2007-01-01
Summary. The molecular basis for the known intramembrane receptorâreceptor interactions among heptahelical receptors (G protein coupled receptors, GPCR) was postulated to be heteromerization based on receptor subtype specific interactions between different types of homomers of GPCR. Adenosine and dopamine receptors in the basal ganglia have been fundamental to demonstrate the existence of receptor heteromers and the functional consequences of such molecular interactions. The heterodimer is only one type of heteromeric complex and the evidence is equally compatible with the existence of higher order heteromeric complexes, where also adapter proteins such as homer proteins and scaffolding proteins can exist, assisting in the process of linking the GPCR and ion channel receptors together in...
1993-12-31
The U.S. Department of Energy`s (DOE`s) Office of Environmental Restoration and Waste Management (EM) has been tasked with addressing environmental contamination and waste problems facing the Department. A key element of any environmental restoration or waste management program is environmental data. An effective and efficient sampling and analysis program is required to generate credible environmental data. The bases for DOE`s EM Analytical Services Program (ASP) are contained in the charter and commitments in Secretary of Energy Notice SEN-13-89, EM program policies and requirements, and commitments to Congress and the Office of Inspector General (IG). The Congressional commitment by DOE to develop and implement an ASP was in response to concerns raised by the Chairman of the Congressional Environment, Energy, and Natural Resources Subcommittee, and the Chairman of the Congressional Oversight and Investigations Subcommittee of the Committee on Energy and Commerce, regarding the production of analytical data. The development and implementation of an ASP also satisfies the IG`s audit report recommendations on environmental analytical support, including development and implementation of a national strategy for acquisition of quality sampling and analytical services. These recommendations were endorsed in Departmental positions, which further emphasize the importance of the ASP to EM`s programs. In September 1990, EM formed the Laboratory Management Division (LMD) in the Office of Technology Development to provide the programmatic direction needed to establish and operate an EM-wide ASP program. In January 1992, LMD issued the {open_quotes}Analytical Services Program Five-Year Plan.{close_quotes} This document described LMD`s strategy to ensure the production of timely, cost-effective, and credible environmental data. This presentation describes the overall LMD Analytical Services Program and, specifically, the various QA programs.
Quality assurance measurement for emergency management
1993-12-31
Under the Federal Civil Defense Act of 1950, as amended, the Federal Emergency Management Agency (FEMA) is charged with maintenance of a nationwide inventory of 4.3 million radiological instruments procured and granted by the federal government to state and local governments. These instruments are used by trained state Radiological Response Team Members, first responders, and critical workers to support the population from a national security or large-scale peacetime radiological disaster, e.g., Chernobyl, Three Mile Island, Satellite Reentry, etc. The inventory is maintained through a network of 100% federally funded state maintenance and calibration facilities, with overall technical guidance and standardization provided by the FEMA Radiological Instrumentation Test Facility. The system used to support maintenance and standardized calibration of the inventory consists of CDV-794 Radiation Calibrator (High Range), CDV-765 Model 2 Gamma Transfer Standard, CDV-790 Model 1 Calibrator (Low Range), and Dosimeter Transfer Standards. Past studies have indicated the {open_quotes}Readiness{close_quotes} and {open_quotes}Reliability{close_quotes} of the inventory to meet mission requirements based upon a standardized system of maintenance and calibration. FEMA has just initiated a new instrument Readiness and Reliability study with the State of Ohio Radiological Instrument Maintenance and Calibration Program to provide data to reassess the capability of the current inventory to support all types of peacetime and national security missions.
Shelley N. Jackson National Institute on Drug Abuse Intramural Research Program National Institutes of Health Protein-protein or peptide-peptide interactions are usually studied in the context of the lock and key model.
P1 receptors and cytokine secretion
2007-01-01
Evidence has accumulated in the last three decades to suggest tissue protection and regeneration by adenosine in multiple different cell types. Adenosine produced in hypoxic or inflamed environments reduces tissue injury and promotes repair by receptor-mediated mechanisms. Among other actions, regulation of cytokine production and secretion by immune cells, astrocytes and microglia (the brain immunocytes) has emerged as a main mechanism at the basis of adenosine effects in diseases characterized by a marked inflammatory component. Many recent studies have highlighted that signalling through A1 and A2A adenosine receptors can powerfully prevent the release of pro-inflammatory cytokines, thus inhibiting inflammation and reperfusion injury. However, the activation of adenosine receptors is no...
Overview of the EPA quality system for environmental programs
1993-12-31
Formalized quality assurance program requirements for the U.S. Environmental Protection Agency (EPA) have been established for more than a decade. During this period, the environmental issues and concerns addressed by the EPA have changed. Many issues, such as ozone depletion and global climate warming, have become international concerns among the world environmental community. Other issues, such as hazardous waste cleanup and clean air, remain a focus of national environmental concerns. As the environmental issues of the 1980`s evolved, the traditional quality assurance (QA) program was transformed through the use of quality management principles into a Quality System to help managers meet the needs of the 1990`s and beyond.
NVLAP calibration laboratory program
1993-12-31
This paper presents an overview of the progress up to April 1993 in the development of the Calibration Laboratories Accreditation Program within the framework of the National Voluntary Laboratory Accreditation Program (NVLAP) at the National Institute of Standards and Technology (NIST).
NVLAP activities at Department of Defense calibration laboratories
1993-12-31
There are 367 active radiological instrument calibration laboratories within the U.S. Department of Defense (DoD). Each of the four services in DoD manages, operates, and certifies the technical proficiency and competency of those laboratories under their cognizance. Each service has designated secondary calibration laboratories to trace all calibration source standards to the National Institute of Standards and Technology. Individual service radiological calibration programs and capabilities, present and future, are described, as well as the measurement quality assurance (MQA) processes for their traceability. National Voluntary Laboratory Accreditation Program (NVLAP) programs for dosimetry systems are briefly summarized. Planned NVLAP accreditation of secondary laboratories is discussed in the context of current technical challenges and future efforts.
NIST commitment to national MQA programs
1993-12-31
The program of the Ionizing Radiation Division, Physics Laboratory is discussed, especially relating to standards, calibrations, and measurement quality assurance (MQA). The NIST program is {open_quotes}vertically integrated,{close_quotes} meaning that activities extend from fundamental research to measurement research to supplying services and data. Typical methods NIST uses to assure the quality of the national standards are presented. Some of the programs in x-ray, gamma-ray, electron, neutron, and radioactivity research which support MQA are presented. Examples are given of MQA activities.
NCI Funded Research Portfolio - Search Results
Cancer types as defined by NCI-designated cancer organ sites, such as Breast or Liver; or related cancers, such as Hodgkins Lymphoma, are reporting categories for NCI research projects.
Microsoft Word - poster-0308.doc
The molecular structure of the interface of the DA receptor containing heteromers. Shelley N. Jackson and Amina S. Woods; NIDA IRP, NIH, Baltimore MD, USA. Biological mass spectrometry has emerged as an important tool for the study of noncovalent
Measurement quality assurance for radioassay laboratories
1993-12-31
Until recently, the quality of U.S. radioassay laboratory services has been evaluated by a limited number of governmental measurement assurance programs (MAPs). The major programs have been limited to the U.S. Department of Energy (DOE), the U.S. Environmental Protection Agency (EPA) and the U.S. Nuclear Regulatory Commission (NRC). In 1988, an industry MAP was established for the nuclear power utility industry through the U.S. Council for Energy Awareness/National Institute of Standards and Technology (USCEA/NIST). This program functions as both a MAP for utility laboratories and/or their commercial contractor laboratories, and as a traceability program for the U.S. radioactive source manufacturers and the utility laboratories. Each of these generic MAPs has been initiated and is maintained to serve the specific needs of the sponsoring agency or organization. As a result, there is diversification in their approach, scope, requirements, and degree of traceability to NIST. In 1987, a writing committee was formed under the American National Standards Institute (ANSI) N42.2 committee to develop a standard to serve as the basis document for the creation of a national measurement quality assurance (MQA) program for radioassay laboratories in the U.S. The standard is entitled, {open_quotes}Measurement Quality Assurance For Radioassay Laboratories.{open_quotes} The document was developed to serve as a guide for MQA programs maintained for the specialized sectors of the radioassay community, such as bioassay, routine environmental monitoring, environmental restoration and waste management, radiopharmaceuticals, and nuclear facilities. It was the intent of the writing committee to develop a guidance document that could be utilized to establish a laboratory`s specific data quality objectives (DQOs) that govern the operational requirements of the radioassay process, including mandated protocols and recommendations.
1993-12-31
The Conference of Radiation Control Program Directors, or CRCPD, was formed by state radiation control programs, and exists to serve the needs of and provide a resource to these programs. One of the fundamental requirements of a radiation control program is the ability to accurately and reliably make radiation measurements. The CRCPD has a continuing commitment to promoting measurement quality assurance (MQA) in several areas, including having an accreditation program for calibration laboratories. As the needs of radiation control programs in the area of MQA increase, the CRCPD will also increase its activities in this area.
Figure 9.1 Example of How Potential Endophenotypes Can Link Genes to Nicotine-Dependence Risk CHRNA4, CHRNA7, CHRNB2 CYP2A6 OPRM1 5-HTTLPR DRD2 COMT Nicotine Metabolism nAChRs Opioid Serotonin Dopamine Sensory Behavior Cognitive Affective Craving Reward Self-Administration Nicotine Dependence Motivational Mechanisms Acute Smoking or Abstinence Effects Note.
133 Detailed studies of inbred mouse strains have provided remarkable insights into how genetics shape complex processes, ranging from cancer susceptibility to immunity. The mouse models of response to addictive substances such as nicotine are now showing
June 2006 17 The NCI-Frederick Poster Spring Research Festival Congratulations to the 2006 Spring Research Festival Poster Winners Associate Director Dr. Ester Rozenblum ? Laboratory of Molecular Technology (New Technology) Laboratory of Molecular Technology (LMT) Technology Development Associate Scientist John M.
Inflammasomes bridge signalling between pathogen identification and the immune response
2009-11-01
Microbial organisms express pathogen-associated molecular patterns (PAMPs) that can stimulate expression of pro-inflammatory mediators following ligation of pathogen recognition receptors. However,...Full Text Available
Inflammasomes bridge signalling between pathogen identification and the immune response
2009-11-01
Full Text Available.Microbial organisms express pathogen-associated molecular patterns (PAMPs) that can stimulate expression of pro-inflammatory mediators following ligation of pathogen recognition receptors. However, both commensal organisms and pathogens can express PAMPs. The immune system can distinguish between commensals and pathogens in part through secretion of the key inflammatory cytokines IL-1β and IL-18. A PAMP such as lipopolysaccharide can induce production of intracellular pro-IL-1β and pro-IL-18, but not their secretion. A second “danger signal”, derived from host-cell molecules that are released from stressed or infected cells, or detected as a PAMP that is present in the cytosol, can stimulate assembly of an inflammasome that activates the protease caspase-1. Caspase-1, in turn, is responsible for processing and secretion of the mature IL-1β and IL-18. Many diverse ligands leading to inflammasome activation have been identified, but the cell signaling pathways initiated by the ligands tend to converge on a small set of common mechanisms.
1993-12-31
For more than 20 years, the American Association of Physicists in Medicine (AAPM) has operated an accreditation program for secondary standards laboratories that calibrate radiation measuring instruments. Except for one short period, that program has been able to provide the facilities to satisfy the national need for accurate calibrations of such instruments. That exception, in 1981, due to the combination of the U.S. Nuclear Regulatory Commission (NRC) requiring instrument calibrations by users of cobalt-60 teletherapy units and the withdrawal of one of the three laboratories accredited at that time. However, after successful operation as a Task Group of the Radiation Therapy Committee (RTC) of the AAPM for two decades, a reorganization of this structure is now under serious consideration by the administration of the AAPM.
HPS instrument calibration laboratory accreditation program
1993-12-31
The purpose of this paper is to provide an accurate overview of the development and structure of the program established by the Health Physics Society (HPS) for accrediting instrument calibration laboratories relative to their ability to accurately calibrate portable health physics instrumentation. The purpose of the program is to provide radiation protection professionals more meaningful direct and indirect access to the National Institute of Standards and Technology (NIST) national standards, thus introducing a means for improving the uniformity, accuracy, and quality of ionizing radiation field measurements. The process is designed to recognize and document the continuing capability of each accredited laboratory to accurately perform instrument calibration. There is no intent to monitor the laboratory to the extent that each calibration can be guaranteed by the program; this responsibility rests solely with the accredited laboratory.
Full Text Available.BackgroundGPR17 is a hybrid G-protein-coupled receptor (GPCR) activated by two unrelated ligand families, extracellular nucleotides and cysteinyl-leukotrienes (cysteinyl-LTs), and involved in brain damage and repair. Its exploitment as a target for novel neuro-reparative strategies depends on the elucidation of the molecular determinants driving binding of purinergic and leukotrienic ligands. Here, we applied docking and molecular dynamics simulations (MD) to analyse the binding and the forced unbinding of two GPR17 ligands (the endogenous purinergic agonist UDP and the leukotriene receptor antagonist pranlukast from both the wild-type (WT) receptor and a mutant model, where a basic residue hypothesized to be crucial for nucleotide binding had been mutated (R255I) to Ile.ResultsMD suggested that GPR17 nucleotide binding pocket is enclosed between the helical bundle and extracellular loop (EL) 2. The driving interaction involves R255 and the UDP phosphate moiety. To support this hypothesis, steered MD experiments showed that the energy required to unbind UDP is higher for the WT receptor than for R255I. Three potential binding sites for pranlukast where instead found and analysed. In one of its preferential docking conformations, pranlukast tetrazole group is close to R255 and phenyl rings are placed into a subpocket highly conserved among GPCRs. Pulling forces developed to break polar and aromatic interactions of pranlukast were comparable. No differences between the WT receptor and the R255I receptor were found for the unbinding of pranlukast.ConclusionsThese data thus suggest that, in contrast to which has been hypothesized for nucleotides, the lack of the R255 residue doesn't affect the binding of pranlukast a crucial role for R255 in binding of nucleotides to GPR17. Aromatic interactions are instead likely to play a predominant role in the recognition of pranlukast, suggesting that two different binding subsites are present on GPR17.
BackgroundGPR17 is a hybrid G-protein-coupled receptor (GPCR) activated by two unrelated ligand families, extracellular nucleotides and cysteinyl-leukotrienes (cysteinyl-LTs), and...Full Text Available
FEASIBILITY STUDY REPORT FOR THE 200-ZP-1 GROUNDWATER OPERABLE UNIT
The Hanford Site, managed by the U.S. Department of Energy (DOE), encompasses approximately 1,517 km{sup 2} (586 mi{sup 2}) in the Columbia Basin of south-central Washington State. In 1989, the U.S. Environmental Protection Agency (EPA) placed the 100, 200, 300, and 1100 Areas of the Hanford Site on the 40 Code of Federal Regulations (CFR) 300, 'National Oil and Hazardous Substances Pollution Contingency Plan' National Contingency Plan [NCPD], Appendix B, 'National Priorities List' (NPL), pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). The 200 Areas NPL sites consist of the 200 West and 200 East Areas (Figure 1-1). The 200 Areas contain waste management facilities, inactive irradiated fuel reprocessing facilities, and the 200 North Area (formerly used for interim storage and staging of irradiated fuel). Several waste sites in the 600 Area, located near the 200 Areas, also are included in the 200 Areas NPL site. The 200 Areas NPL site is in a region referred to as the 'Central Plateau' and consists of approximately 700 waste sites, excluding sites assigned to the tank farm waste management areas (WMAs). The 200-ZP-1 Groundwater Operable Unit (OU) consists of the groundwater located under the northern portion of the 200 West Area. Waste sources that contributed to the 200-ZP-1 OU included cribs and trenches that received liquid and/or solid waste in the past from the Z Plant and T Plant aggregate areas, WMA-T, WMA-TX/TY, and the State-Approved Land Disposal Site (SALDS). This feasibility study (FS) for the 200-ZP-1 Groundwater OU was prepared in accordance with the requirements of CERCLA decision documents. These decision documents are part of the Administrative Record for the selection of remedial actions for each waste site and present the selected remedial actions that are chosen in accordance with CERCLA, as amended by the Superfund Amendments and Reauthorization Act of 1986, and to the extent practicable, the NCP. This FS conforms to the conditions set forth in the Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) (Ecology et al. 2003) and amendments, signed by the Washington State Department of Ecology (Ecology), EPA, and DOE Richland Operations Office (RL). This also includes Tri-Party Agreement Milestone M-015-00C for completing all 200 Area non-tank farm OU pre-Record of Decision (ROD) documents on or before December 31, 2011. This FS supports the final remedy selection for the 200-ZP-1 OU, as described in the Remedial Investigation/Feasibility Study Work Plan for the 200-ZP-1 Groundwater Operable Unit (referred to as the 200-ZP-1 RI/FS work plan) (DOE/RL-2003-55), as agreed upon by RL and EPA. Tri-Party Agreement Milestone M-015-48B required Draft A of the 200-ZP-1 OU FS and proposed plan to be transmitted to EPA by September 30, 2007. As agreed to with EPA in the 200 Area Unit Managers Meeting Groundwater Operable Unit Status (FH-0503130), the baseline risk assessment (BRA) was delayed from inclusion in the remedial investigation (RI) report and is completed and documented in this FS. The Remedial Investigation Report for 200-ZP-1 Groundwater Operable Unit (referred to as the 200-ZP-1 RI report) (DOE/RL-2006-24) included an evaluation of human health and ecological risks and hazards. The RI report identified the radiological and chemical contaminants of potential concern (COPCs) that represent the primary risks to human health and the environment. The complete risk assessment in this FS incorporates additional analytical data from the unconfined aquifer that were obtained during or after preparation of the RI report, particularly for carbon tetrachloride and technetium-99. This FS also includes the initial results from an ongoing study of technetium-99 contamination near WMA-T, the sampling of new wells near the 216-W-LC laundry waste crib and T Plant, updated Hanford vadose zone fate and transport modeling, and groundwater particle-tracking analysis. The purpose of this FS is to develop and evaluate alternatives for remediation of the groundwater in the 200-ZP-1 OU. The alternatives considered provide a range of potential response actions (i.e., no action; institutional controls and monitored natural attenuation [MNA]; and pump-and-treat with MNA, flow-path control, and institutional controls) that are appropriate to address site-specific conditions. The alternatives are evaluated against seven of the nine CERCLA evaluation criteria defined in Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA (EPA/540/G-891004). The remaining two CERCLA criteria will be formally assessed during the public comment period. The FS evaluation serves as the basis for identifying a remedy to mitigate potential risks to human health and the environment. A preferred alternative (or alternatives) will be presented to the public for review and comment in the proposed plan.
Endocytosis restricts Arabidopsis KNOLLE syntaxin to the cell division plane during late cytokinesis
2010-02-03
Full Text Available.Cytokinesis represents the final stage of eukaryotic cell division during which the cytoplasm becomes partitioned between daughter cells. The process differs to some extent between animal and plant cells, but proteins of the syntaxin family mediate membrane fusion in the plane of cell division in diverse organisms. How syntaxin localization is kept in check remains elusive. Here, we report that localization of the Arabidopsis KNOLLE syntaxin in the plane of cell division is maintained by sterol-dependent endocytosis involving a clathrin- and DYNAMIN-RELATED PROTEIN1A-dependent mechanism. On genetic or pharmacological interference with endocytosis, KNOLLE mis-localizes to lateral plasma membranes after cell-plate fusion. Fluorescence-loss-in-photo-bleaching and fluorescence-recovery-after-photo-bleaching experiments reveal lateral diffusion of GFP-KNOLLE from the plane of division to lateral membranes. In an endocytosis-defective sterol biosynthesis mutant displaying lateral KNOLLE diffusion, KNOLLE secretory trafficking remains unaffected. Thus, restriction of lateral diffusion by endocytosis may serve to maintain specificity of syntaxin localization during late cytokinesis.
Endocytosis restricts Arabidopsis KNOLLE syntaxin to the cell division plane during late cytokinesis
2010-02-03
Cytokinesis represents the final stage of eukaryotic cell division during which the cytoplasm becomes partitioned between daughter cells. The process differs to some extent between animal and plant...Full Text Available
E AREA LOW LEVEL WASTE FACILITY DOE 435.1 PERFORMANCE ASSESSMENT
This Performance Assessment for the Savannah River Site E-Area Low-Level Waste Facility was prepared to meet requirements of Chapter IV of the Department of Energy Order 435.1-1. The Order specifies that a Performance Assessment should provide reasonable assurance that a low-level waste disposal facility will comply with the performance objectives of the Order. The Order also requires assessments of impacts to water resources and to hypothetical inadvertent intruders for purposes of establishing limits on radionuclides that may be disposed near-surface. According to the Order, calculations of potential doses and releases from the facility should address a 1,000-year period after facility closure. The point of compliance for the performance measures relevant to the all pathways and air pathway performance objective, as well as to the impact on water resources assessment requirement, must correspond to the point of highest projected dose or concentration beyond a 100-m buffer zone surrounding the disposed waste following the assumed end of active institutional controls 100 years after facility closure. During the operational and institutional control periods, the point of compliance for the all pathways and air pathway performance measures is the SRS boundary. However, for the water resources impact assessment, the point of compliance remains the point of highest projected dose or concentration beyond a 100-m buffer zone surrounding the disposed waste during the operational and institutional control periods. For performance measures relevant to radon and inadvertent intruders, the points of compliance are the disposal facility surface for all time periods and the disposal facility after the assumed loss of active institutional controls 100 years after facility closure, respectively. The E-Area Low-Level Waste Facility is located in the central region of the SRS known as the General Separations Area. It is an elbow-shaped, cleared area, which curves to the northwest, situated immediately north of the Mixed Waste Management Facility. The E-Area Low-Level Waste Facility is comprised of 200 acres for waste disposal and a surrounding buffer zone that extends out to the 100-m point of compliance. Disposal units within the footprint of the low-level waste facilities include the Slit Trenches, Engineered Trenches, Component-in-Grout Trenches, the Low-Activity Waste Vault, the Intermediate-Level Vault, and the Naval Reactor Component Disposal Area. Radiological waste disposal operations at the E-Area Low-Level Waste Facility began in 1994. E-Area Low-Level Waste Facility closure will be conducted in three phases: operational closure, interim closure, and final closure. Operational closure will be conducted during the 25-year operation period (30-year period for Slit and Engineered Trenches) as disposal units are filled; interim closure measures will be taken for some units. Interim closure will take place following the end of operations and will consist of an area-wide runoff cover along with additional grading over the trench units. Final closure of all disposal units in the E-Area Low-Level Waste Facility will take place at the end of the 100-year institutional control period and will consist of the installation of an integrated closure system designed to minimize moisture contact with the waste and to serve as a deterrent to intruders. Radiological dose to human receptors is analyzed in this PA in the all-pathways analysis, the inadvertent intruder analysis and the air pathway analysis, and the results are compared to the relevant performance measures. For the all-pathways analysis, the performance measure of relevance is a 25-mrem/yr EDE to representative members of the public, excluding dose from radon and its progeny in air. For the inadvertent intruder, the applicable performance measures are 100-mrem/yr EDE and 500 mrem/yr EDE for chronic and exposure scenarios, respectively. The relevant performance measure for the air pathway is 10-mrem/yr EDE via the air pathway, excluding dose from radon and its progeny in air. Protection of groundwater resources is addressed by comparing calculated compliance point concentrations in groundwater with the relevant performance measure, which was determined to be the Safe Drinking Water Act MCLs for beta-gamma and alpha-emitting radionuclides, and for radium and uranium. Radon fluxes for each disposal unit are calculated and compared to the average flux of 20 pCi/m{sup 2}/s upper limit specified in the relevant performance objective. Thirty-five parent radionuclides are addressed in the groundwater transport calculations, 15 radionuclides in the air pathway calculations, and 78 parent radionuclides in the intruder analysis for all disposal units. Radon-222 fluxes are also evaluated for all disposal units.
E AREA LOW LEVEL WASTE FACILITY DOE 435.1 PERFORMANCE ASSESSMENT
2008-03-31
This Performance Assessment for the Savannah River Site E-Area Low-Level Waste Facility was prepared to meet requirements of Chapter IV of the Department of Energy Order 435.1-1. The Order specifies that a Performance Assessment should provide reasonable assurance that a low-level waste disposal facility will comply with the performance objectives of the Order. The Order also requires assessments of impacts to water resources and to hypothetical inadvertent intruders for purposes of establishing limits on radionuclides that may be disposed near-surface. According to the Order, calculations of potential doses and releases from the facility should address a 1,000-year period after facility closure. The point of compliance for the performance measures relevant to the all pathways and air pathway performance objective, as well as to the impact on water resources assessment requirement, must correspond to the point of highest projected dose or concentration beyond a 100-m buffer zone surrounding the disposed waste following the assumed end of active institutional controls 100 years after facility closure. During the operational and institutional control periods, the point of compliance for the all pathways and air pathway performance measures is the SRS boundary. However, for the water resources impact assessment, the point of compliance remains the point of highest projected dose or concentration beyond a 100-m buffer zone surrounding the disposed waste during the operational and institutional control periods. For performance measures relevant to radon and inadvertent intruders, the points of compliance are the disposal facility surface for all time periods and the disposal facility after the assumed loss of active institutional controls 100 years after facility closure, respectively. The E-Area Low-Level Waste Facility is located in the central region of the SRS known as the General Separations Area. It is an elbow-shaped, cleared area, which curves to the northwest, situated immediately north of the Mixed Waste Management Facility. The E-Area Low-Level Waste Facility is comprised of 200 acres for waste disposal and a surrounding buffer zone that extends out to the 100-m point of compliance. Disposal units within the footprint of the low-level waste facilities include the Slit Trenches, Engineered Trenches, Component-in-Grout Trenches, the Low-Activity Waste Vault, the Intermediate-Level Vault, and the Naval Reactor Component Disposal Area. Radiological waste disposal operations at the E-Area Low-Level Waste Facility began in 1994. E-Area Low-Level Waste Facility closure will be conducted in three phases: operational closure, interim closure, and final closure. Operational closure will be conducted during the 25-year operation period (30-year period for Slit and Engineered Trenches) as disposal units are filled; interim closure measures will be taken for some units. Interim closure will take place following the end of operations and will consist of an area-wide runoff cover along with additional grading over the trench units. Final closure of all disposal units in the E-Area Low-Level Waste Facility will take place at the end of the 100-year institutional control period and will consist of the installation of an integrated closure system designed to minimize moisture contact with the waste and to serve as a deterrent to intruders. Radiological dose to human receptors is analyzed in this PA in the all-pathways analysis, the inadvertent intruder analysis and the air pathway analysis, and the results are compared to the relevant performance measures. For the all-pathways analysis, the performance measure of relevance is a 25-mrem/yr EDE to representative members of the public, excluding dose from radon and its progeny in air. For the inadvertent intruder, the applicable performance measures are 100-mrem/yr EDE and 500 mrem/yr EDE for chronic and exposure scenarios, respectively. The relevant performance measure for the air pathway is 10-mrem/yr EDE via the air pathway, excluding dose from radon and its progeny in air. Protection of groundwater resources is addressed by comparing calculated compliance point concentrations in groundwater with the relevant performance measure, which was determined to be the Safe Drinking Water Act MCLs for beta-gamma and alpha-emitting radionuclides, and for radium and uranium. Radon fluxes for each disposal unit are calculated and compared to the average flux of 20 pCi/m{sup 2}/s upper limit specified in the relevant performance objective. Thirty-five parent radionuclides are addressed in the groundwater transport calculations, 15 radionuclides in the air pathway calculations, and 78 parent radionuclides in the intruder analysis for all disposal units. Radon-222 fluxes are also evaluated for all disposal units.
Dopamine receptor loss of function is not protective of rd1 rod photoreceptors in vivo
PurposeThe retinal degeneration (rd1) mouse undergoes a rapid loss of rod photoreceptors due to a defect in the cGMP-phosphodiesterase gene. We have previously...Full Text Available
Dopamine receptor loss of function is not protective of rd1 rod photoreceptors in vivo
Full Text Available.PurposeThe retinal degeneration (rd1) mouse undergoes a rapid loss of rod photoreceptors due to a defect in the cGMP-phosphodiesterase gene. We have previously demonstrated that dopamine (DA) antagonists or DA depletion blocks photoreceptor degeneration and that DA is necessary for photoreceptor degeneration in the rd1 mouse retinal organ culture model. Antagonists for either D1- or D2-family DA receptors are protective in rd1 organ cultures.MethodsTo determine whether photoreceptor survival can be increased in vivo in the rd1 mouse, we used both a pharmacological and a genetic approach. The pharmacological approach involved three techniques to administer 6-hydroxydopamine (6-OHDA) in an attempt to deplete DA in postnatal mouse retina in vivo. As a genetic alternative, DA receptor signaling was inactivated by crossbreeding rd1 mice to D1, D2, D4, and D5 knockout mice to create four lines of double mutants.ResultsPharmacological DA depletion was incomplete due to the limiting size of the postnatal mouse eye and the lethality of systemic inhibition of DA signaling. In all four lines of double mutants, no increase in rod photoreceptor survival was observed. To determine whether protection of rd1 photoreceptors by inhibition of dopaminergic signaling is a result of conditions specific to the organ culture environment, we grew in vitro retinas from the four lines of double mutant mice for four weeks. Again, no increase in photoreceptor survival was seen. Finally, three triple mutants were generated that lacked two DA receptors (D1/D2; D1/D4; and D2/D4) on a rd1 background. In all three cases, rod photoreceptors were not protected from degeneration.ConclusionsThe dramatic protection of rd1 rod photoreceptors by inhibition of DA signaling in organ culture has not been reproduced in vivo by either a pharmacological approach, due to technical limitations, or by genetic manipulations. The possible role of compensatory effects during retinal development in DA receptor deficient mice is considered.
Current NRC activities related to MQA
1993-12-31
The U.S. Nuclear Regulatory Commission`s (NRC`s) interest in measurement quality assurance (MQA) goes back to before 1963, when the Atomic Energy Commission (AEC) published a notice in the Federal Register concerning the need for establishing a Film Dosimetry Calibration Laboratory, and also provided a set of minimum performance criteria to be used by the laboratory in evaluating film dosimetry services used by licensees. The proposed laboratory was not established, but in 1967 the AEC contracted with Battelle`s Pacific Northwest Laboratory (PNL) to evaluate film dosimeter performance criteria and provide a basis for establishing a Film Dosimetry Calibration Laboratory if the study showed that it was needed. Then, in 1973, the Conference of Radiation Control Program Directors (CRCPD), concerned with the state of dosimetry processing and the lack of adequate standards, recommended that the National Bureau of Standards (NBS) direct a performance testing program for personnel dosimetry processing services. Later, in 1976, NRC asked PNL to conduct a study to evaluate the four existing performance standards for personnel dosimetry processing. One result of this study was that the HPSSC standard, which later became ANSI N13.11, was recommended as the standard for use in a national dosimetry processing program. The rest is common knowledge. With the support of numerous other federal agencies and the CRCPD, NRC published a regulation, effective in 1988, that required all processors of personnel dosimeters be accredited under the National Voluntary Laboratory Accreditation Program (NVLAP), operated by the NBS, which is now called the National Institute of Standards and Technology (NIST). At present, there are 75 dosimetry processing laboratories accredited under NVLAP. NRC has also been involved in extremity dosimeters, health physics survey instruments, bioassay measurements, electronic personnel dosimeters, and environmental monitoring around nuclear power plants.
Characteristics of GABA Release Induced by Free Radicals in Mouse Hippocampal Slices
2008-01-01
The release of the inhibitory neurotransmitter GABA is generally enhanced under potentially cell-damaging conditions. The properties and regulation of preloaded [3H]GABA release from mouse hippocampal slices were now studied in free radical-containing medium in a superfusion system. Free radical production was induced by 0.01% of H2O2 in the medium. H2O2 markedly potentiated GABA release, which was further enhanced about 1.5-fold by K+ stimulation (50 mM). In Ca2+-free media this stimulation was not altered, indicating that the release was mostly Ca2+-independent. Moreover, omission of Na+ increased the release, suggesting that it is mediated by Na+-dependent transporters operating outwards, a conception confirmed by the enhancement with GABA homoexchange. Inhibition of the release with t...
CRCPD`S laboratory accrediation program
1993-12-31
The Conference of Radiation Control Program Directors, or CRCPD, first became involved in a calibration laboratory accreditation program about 17 years ago. Since that time, the CRCPD has formed a Committee on Ionizing Measurements which writes criteria for the accreditation of laboratories, and performs the accreditation review process. To become accredited, a laboratory must agree to an administrative review, and an onsite review, and participate in measurement quality assurance (MQA) testing with the National Institute of Standards and Technology (NIST). The CRCPD currently has four accredited laboratories. All the laboratories are working with the Conference in promoting the improvement of MQA in radiation control programs.
CIRMS role in coordinating MQA programs
1993-12-31
This paper presents the purposes, functions, and expected benefits of the Council on Ionizing Radiation Measurements and Standards (CIRMS), a new association of ionizing radiation measurers and users. The initial activities are reported, including the program of the inaugural meeting. The organizational structure, members of the executive committee, and chairmen of the standing committees are also given. Governmental and professional organizations, industrial corporations, and interested individuals may join. Broad participation in CIRMS will support the principles of measurement quality assurance for ionizing radiation.
2009-09-29
Full Text Available.CD39/ENTPD1 hydrolyzes proinflammatory nucleotides to generate adenosine. As purinergic mediators have been implicated in intestinal inflammation, we hypothesized that CD39 might protect against inflammatory bowel disease. We studied these possibilities in a mouse model of colitis using mice with global CD39 deletion. We then tested whether human genetic polymorphisms in the CD39 gene might influence susceptibility to Crohn's disease. We induced colitis in mice using Dextran Sodium Sulfate (DSS). Readouts included disease activity scores, histological evidence of injury, and markers of inflammatory activity. We used HapMap cell lines to find SNPs that tag for CD39 expression, and then compared the frequency of subjects with high vs. low CD39-expression genotypes in a case-control cohort for Crohn's disease. Mice null for CD39 were highly susceptible to DSS injury, with heterozygote mice showing an intermediate phenotype compared to wild type (WT). We identified a common SNP that tags CD39 mRNA expression levels in man. The SNP tagging low levels of CD39 expression was associated with increased susceptibility to Crohn's disease in a case-control cohort comprised of 1,748 Crohn's patients and 2,936 controls (P = 0.005–0.0006). Our data indicate that CD39 deficiency exacerbates murine colitis and suggest that CD39 polymorphisms are associated with inflammatory bowel disease in humans.
2009-09-29
CD39/ENTPD1 hydrolyzes proinflammatory nucleotides to generate adenosine. As purinergic mediators have been implicated in intestinal inflammation, we hypothesized that CD39 might protect against inflammatory...Full Text Available
Biophysical Society announces winners of 2008 Student Travel Awards
The Biophysical Society has announced the winners of its student travel award to attend the Joint Meeting of the Biophysical Society and the International Biophysics Congress in Long Beach, Calif., Feb. 2-6, 2008. The ...
2010-03-01
Full Text Available.Bone marrow-derived mesenchymal stem cells (MSC) have therapeutic potential in liver injury, but the signals responsible for MSC localization to sites of injury and initiation of differentiation are not known. Adenosine concentration is increased at sites of cellular injury and inflammation, and adenosine is known to signal a variety of cellular changes. We hypothesized that local elevations in the concentration of adenosine at sites of tissue injury regulate MSC homing and differentiation. Here we demonstrate that adenosine does not induce MSC chemotaxis, but dramatically inhibits MSC chemotaxis in response to the chemoattractant hepatocyte growth factor (HGF). Inhibition of HGF-induced chemotaxis by adenosine requires the A2a receptor, and is mediated via up-regulation of the cyclic AMP/protein kinase A pathway. This results in inhibition of cytosolic calcium signaling, and down-regulation of HGF-induced Rac1. Due to the important role of Rac1 in formation of actin stress fibers, we examined the effect of adenosine on stress fiber formation and found that adenosine inhibits HGF-induced stress fiber formation. In addition, we found that adenosine induces the expression of some key endodermal and hepatocyte-specific genes in mouse and human MSC in vitro. We propose that the inhibition of MSC chemotaxis at sites of high adenosine concentration results in localization of MSC to areas of cellular injury and death in the liver. We speculate that adenosine might initiate the process of differentiation of MSC into hepatocyte-like cells.
2010-03-01
Bone marrow-derived mesenchymal stem cells (MSC) have therapeutic potential in liver injury, but the signals responsible for MSC localization to sites of injury and initiation of differentiation...Full Text Available
Adaptation of NS cells growth and differentiation to high-throughput screening-compatible plates
Full Text Available.BackgroundThere is an urgent need of neuronal cell models to be applied to high-throughput screening settings while recapitulating physiological and/or pathological events occurring in the Central Nervous System (CNS). Stem cells offer a great opportunity in this direction since their self renewal capacity allows for large scale expansion. Protocols for directed differentiation also promise to generate populations of biochemically homogenous neuronal progenies. NS (Neural Stem) cells are a novel population of stem cells that undergo symmetric cell division in monolayer and chemically defined media, while remaining highly neurogenic.ResultsWe report the full adaptation of the NS cell systems for their growth and neuronal differentiation to 96- and 384-well microplates. This optimized system has also been exploited in homogeneous and high-content assays.ConclusionsOur results show that these mouse NS cells may be suitable for a series of applications in high-throughput format.
Adaptation of NS cells growth and differentiation to high-throughput screening-compatible plates
BackgroundThere is an urgent need of neuronal cell models to be applied to high-throughput screening settings while recapitulating physiological and/or pathological events occurring...Full Text Available
2005-01-01
Rationale There is no consensus on the contribution of adenosine A1 and A2A receptor blockade to motor-activating effects of caffeine. Objective Our aim was to use a detailed and continuous observational method to compare the motor effects induced by caffeine with those induced by selective A1 and A2A receptor antagonists. Methods The behavioral repertoire induced by systemic administration of caffeine (3, 10, and 30Â mg/kg), A1 receptor antagonist 8-cyclopentyl-1,3-dimethylxanthine (CPT; 1.2, 4.8 and 7.2Â mg/kg), and A2A receptor antagonist 3-(3-hydroxypropyl)-8-(m-methoxystyryl)-7-methyl-1-propargylxanthine phosphate disodium salt (MSX-3; 1, 3, and 10Â mg/kg) was analyzed. The effects of pretreatment with the selective A1 receptor agonist N 6-cyclopentyladenosine (CPA; 0.1Â mg/g) and the...
2010-03-01
Full Text Available.
2007-01-01
Abstract Estradiol plays a critical role in the feedback regulation of reproduction, in part by modulating the neurosecretory activity of gonadotropin-releasing hormone (GnRH) neurons. While indirect effects of estradiol on GnRH neurons have been clearly demonstrated, direct actions are still controversial. In the current study, we examined direct effects of 17b-estradiol upon the expression of receptors for afferent signals at the level of the GnRH neuron, using immortalized GT1-7 cells. Using RT-PCR, we confirmed the expression of mRNA for the adrenergic receptors (AR) a1A-, a1B-, a1D-, a2A-, a2C-, and b1-AR, and showed for the first time that mRNAs for a2B-, b2- and b3-AR, for kisspeptin and its receptor GPR54 and for the novel estrogenic receptor GPR30 are expressed in GT1-7 cells. Aft...
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