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Sample records for adenosine stress cmr

  1. Caffeine intake inverts the effect of adenosine on myocardial perfusion during stress as measured by T1 mapping.

    PubMed

    Kuijpers, Dirkjan; Prakken, Niek H; Vliegenthart, Rozemarijn; van Dijkman, Paul R M; van der Harst, Pim; Oudkerk, Matthijs

    2016-10-01

    Caffeine intake before adenosine stress myocardial perfusion imaging may cause false negative findings. We hypothesized that the antagonistic effect of caffeine can be measured by T1 relaxation times in rest and adenosine stress cardiac magnetic resonance imaging (CMR), as T1 mapping techniques are sensitive to changes in myocardial blood volume. We prospectively analyzed 105 consecutive patients with adenosine stress perfusion CMR on a 1.5-T MRI system. Rest and stress T1 mapping was performed using Modified Look-Locker Inversion recovery. T1 reactivity was defined as difference in T1rest and T1stress (∆T1). Fifteen patients drank coffee within 4 h of CMR (<4H caffeine group), and 10 patients had coffee the day before (>8H caffeine group). Comparison was made to patients without self-reported coffee intake: 50 with normal CMR (control group), 18 with myocardial ischemia, and 12 with myocardial infarction. The national review board approved the study; all patients gave written informed consent. The <4H caffeine group showed inverted ∆T1 of -7.8 % (T1rest 975 ± 42 ms, T1stress 898 ± 51 ms, p < 0.0005). The >8H caffeine group showed reduced T1 reactivity (1.8 %; T1rest 979 ms, T1stress 997 ms) compared to the controls (4.3 %; T1rest 977 ± 40 ms, T1stress 1018 ± 40 ms), p < 0.0005. Ischemic and infarcted myocardium showed minimal T1 reactivity (0.2 and 0.3 %, respectively). Caffeine intake inverts the adenosine effect during stress perfusion CMR as measured by T1 mapping. T1 reactivity can assess the adequacy of adenosine-induced stress in perfusion CMR. PMID:27473274

  2. Cmr1/WDR76 defines a nuclear genotoxic stress body linking genome integrity and protein quality control

    PubMed Central

    Gallina, Irene; Colding, Camilla; Henriksen, Peter; Beli, Petra; Nakamura, Kyosuke; Offman, Judith; Mathiasen, David P.; Silva, Sonia; Hoffmann, Eva; Groth, Anja; Choudhary, Chunaram; Lisby, Michael

    2015-01-01

    DNA replication stress is a source of genomic instability. Here we identify changed mutation rate 1 (Cmr1) as a factor involved in the response to DNA replication stress in Saccharomyces cerevisiae and show that Cmr1—together with Mrc1/Claspin, Pph3, the chaperonin containing TCP1 (CCT) and 25 other proteins—define a novel intranuclear quality control compartment (INQ) that sequesters misfolded, ubiquitylated and sumoylated proteins in response to genotoxic stress. The diversity of proteins that localize to INQ indicates that other biological processes such as cell cycle progression, chromatin and mitotic spindle organization may also be regulated through INQ. Similar to Cmr1, its human orthologue WDR76 responds to proteasome inhibition and DNA damage by relocalizing to nuclear foci and physically associating with CCT, suggesting an evolutionarily conserved biological function. We propose that Cmr1/WDR76 plays a role in the recovery from genotoxic stress through regulation of the turnover of sumoylated and phosphorylated proteins. PMID:25817432

  3. Unpredictable Chronic Stress Alters Adenosine Metabolism in Zebrafish Brain.

    PubMed

    Zimmermann, F F; Altenhofen, S; Kist, L W; Leite, C E; Bogo, M R; Cognato, G P; Bonan, C D

    2016-05-01

    Stress is considered a risk factor for several human disorders. Despite the broad knowledge of stress responses in mammals, data on the relationship between unpredictable chronic stress (UCS) and its effects on purinergic signaling are limited. ATP hydrolysis by ectonucleotidases is an important source of adenosine, and adenosine deaminase (ADA) contributes to the control of the nucleoside concentrations. Considering that some stress models could affect signaling systems, the objective of this study was to investigate whether UCS alters ectonucleotidase and ADA pathway in zebrafish brain. Additionally, we analyzed ATP metabolism as well as ada1, ada2.1, ada2.2, adaL, and adaasi gene expression in zebrafish brain. Our results have demonstrated that UCS did not alter ectonucleotidase and soluble ADA activities. However, ecto-ADA activity was significantly decreased (26.8%) in brain membranes of animals exposed to UCS when compared to the control group. Quantitative reverse transcription PCR (RT-PCR) analysis did not show significant changes on ADA gene expression after the UCS exposure. The brain ATP metabolism showed a marked increase in adenosine levels (ADO) in animals exposed to UCS. These data suggest an increase on extracellular adenosine levels in zebrafish brain. Since this nucleoside has neuromodulatory and anxiolytic effects, changes in adenosine levels could play a role in counteracting the stress, which could be related to a compensatory mechanism in order to restore the homeostasis.

  4. Unpredictable Chronic Stress Alters Adenosine Metabolism in Zebrafish Brain.

    PubMed

    Zimmermann, F F; Altenhofen, S; Kist, L W; Leite, C E; Bogo, M R; Cognato, G P; Bonan, C D

    2016-05-01

    Stress is considered a risk factor for several human disorders. Despite the broad knowledge of stress responses in mammals, data on the relationship between unpredictable chronic stress (UCS) and its effects on purinergic signaling are limited. ATP hydrolysis by ectonucleotidases is an important source of adenosine, and adenosine deaminase (ADA) contributes to the control of the nucleoside concentrations. Considering that some stress models could affect signaling systems, the objective of this study was to investigate whether UCS alters ectonucleotidase and ADA pathway in zebrafish brain. Additionally, we analyzed ATP metabolism as well as ada1, ada2.1, ada2.2, adaL, and adaasi gene expression in zebrafish brain. Our results have demonstrated that UCS did not alter ectonucleotidase and soluble ADA activities. However, ecto-ADA activity was significantly decreased (26.8%) in brain membranes of animals exposed to UCS when compared to the control group. Quantitative reverse transcription PCR (RT-PCR) analysis did not show significant changes on ADA gene expression after the UCS exposure. The brain ATP metabolism showed a marked increase in adenosine levels (ADO) in animals exposed to UCS. These data suggest an increase on extracellular adenosine levels in zebrafish brain. Since this nucleoside has neuromodulatory and anxiolytic effects, changes in adenosine levels could play a role in counteracting the stress, which could be related to a compensatory mechanism in order to restore the homeostasis. PMID:26081145

  5. Relevance of Cooperative Lattice Effects and Stress Fields in Phase-Separation Theories for CMR Manganites

    NASA Astrophysics Data System (ADS)

    Burgy, Jan; Moreo, Adriana; Dagotto, Elbio

    2004-03-01

    Previous theoretical investigations of colossal magnetoresistance (CMR) materials explain this effect using a “clustered” state with preformed ferromagnetic islands that rapidly align their moments with increasing external magnetic fields. While qualitatively successful, explicit calculations indicate drastically different typical resistivity values in two- and three-dimensional lattices, contrary to experimental observations. This conceptual bottleneck in the phase-separated CMR scenario is resolved here considering the cooperative nature of the Mn-oxide lattice distortions. This effectively induces power-law correlations in the quenched disorder used in toy models with phase competition. When these effects are incorporated, resistor-network calculations reveal very similar results in two and three dimensions, qualitatively modifying previous scenarios and solving the puzzle.

  6. Adenosine triphosphate stress echocardiography in the detection of myocardial ischemia.

    PubMed

    Fukai, T; Koyanagi, S; Tashiro, H; Ichiki, T; Tsutsui, H; Matsumoto, T; Takeshita, A

    1995-10-01

    The purpose of this study was to assess feasibility and safety in the diagnosis of coronary artery in the diagnosis of coronary artery disease and myocardial ischemia using adenosine triphosphate (ATP) stress echocardiography. ATP, a product of human myocardial tissue, is more potent than adenosine in increasing coronary blood flow. Like adenosine, ATP also has a short half-life (<10 s). Left ventricular echocardiograms were recorded during step-wise infusions of ATP in 86 patients who underwent coronary angiography and stress thallium 201 scintigraphy. No serious complications occurred with ATP infusion and most of the side effects were mild and transient. Significant coronary artery disease (>75% diameter stenosis) was present in 34 of 48 patients who had normal echocardiograms at rest. The sensitivity and specificity of ATP-induced wall motion abnormalities for coronary artery disease was 65% (22 of 34) and 100% (14 of 14), respectively. The sensitivity was 50% (10 of 20) in those with one-vessel disease and 86% (12 of 14) in those with multivessel disease (P < .05). In patients with normal echocardiograms at rest and without prior myocardial infarction, the sensitivity of ATP stress echocardiography for the detection of myocardial ischemia assessed by 201Tl single proton emission computed tomography was 58%, with a specificity of 76%, and a diagnostic accuracy of 66%. The sensitivity was 43% in those with one-vessel disease, and 86% in those with multivessel disease (P = .05). In patients with prior myocardial infarction, the sensitivity of ATP stress echocardiography for the detection of viable but jeopardized myocardium was 81%, with a specificity of 91%. The patients with well-developed collateral circulation had a higher incidence of developing wall motion abnormality than those without collaterals (70% v 40%, P < .01). ATP stress echocardiography is valuable for the assessment of coronary artery disease in patients with multivessel disease, coronary

  7. Adenosine Stress and Rest T1 Mapping Can Differentiate Between Ischemic, Infarcted, Remote, and Normal Myocardium Without the Need for Gadolinium Contrast Agents

    PubMed Central

    Liu, Alexander; Wijesurendra, Rohan S.; Francis, Jane M.; Robson, Matthew D.; Neubauer, Stefan; Piechnik, Stefan K.; Ferreira, Vanessa M.

    2016-01-01

    Objectives The aim of this study was to evaluate the potential of T1 mapping at rest and during adenosine stress as a novel method for ischemia detection without the use of gadolinium contrast. Background In chronic coronary artery disease (CAD), accurate detection of ischemia is important because targeted revascularization improves clinical outcomes. Myocardial blood volume (MBV) may be a more comprehensive marker of ischemia than myocardial blood flow. T1 mapping using cardiac magnetic resonance (CMR) is highly sensitive to changes in myocardial water content, including MBV. We propose that T1 mapping at rest and during adenosine vasodilatory stress can detect MBV changes in normal and diseased myocardium in CAD. Methods Twenty normal controls (10 at 1.5-T; 10 at 3.0-T) and 10 CAD patients (1.5-T) underwent conventional CMR to assess for left ventricular function (cine), infarction (late gadolinium enhancement [LGE]) and ischemia (myocardial perfusion reserve index [MPRI] on first-pass perfusion imaging during adenosine stress). These were compared to novel pre-contrast stress/rest T1 mapping using the Shortened Modified Look-Locker Inversion recovery technique, which is heart rate independent. T1 values were derived for normal myocardium in controls and for infarcted, ischemic, and remote myocardium in CAD patients. Results Normal myocardium in controls (normal wall motion, MPRI, no LGE) showed normal resting T1 (954 ± 19 ms at 1.5-T; 1,189 ± 34 ms at 3.0-T) and significant positive T1 reactivity during adenosine stress compared to baseline (6.2 ± 0.5% at 1.5-T; 6.3 ± 1.1% at 3.0-T; all p < 0.0001). Infarcted myocardium showed the highest resting T1 of all tissue classes (1,442 ± 84 ms), without significant T1 reactivity (0.2 ± 1.5%). Ischemic myocardium showed elevated resting T1 compared to normal (987 ± 17 ms; p < 0.001) without significant T1 reactivity (0.2 ± 0.8%). Remote myocardium, although having comparable resting T1 to normal (955 ± 17 ms

  8. Adenosine A2(A) receptor modulates the oxidative stress response of primed polymorphonuclear leukocytes after parabolic flight.

    PubMed

    Kaufmann, Ines; Feuerecker, Matthias; Salam, Alex; Schelling, Gustav; Thiel, Manfred; Choukèr, Alexander

    2011-07-01

    Space flight and gravitational stress can alter innate immune function. Parabolic flights (PFs) as a model for short-term gravitational changes prime the cytotoxic capability of polymorphonuclear leukocytes (PMNs). In view of the emerging role of adenosine in the regulation of innate immune responses, we examined the potency of adenosine to control the release of cytotoxic H(2)O(2) by primed PMNs via the adenosine receptor system. During PFs, microgravity conditions (<10(-2) G) are generated for approximately 22 seconds, followed by a hypergravity (1.8 G) phase resulting in gravitational stress. We studied the ex vivo effects of adenosine on the production of H(2)O(2) by stimulated PMNs and determined adenosine plasma levels and adenosine A2(A) receptor transcripts of leukocytes of PF participants (n = 15). Increasing concentrations of adenosine dose dependently reduced tissue-toxic H(2)O(2) production by PMNs with a half-maximal inhibitory concentration (IC(50)) of 19.5 nM before takeoff and 7.6 nM at 48 hours after PF. This increase in the adenosine-mediated inhibition of PMNs' H(2)O(2) production was completely reversed by addition of the A2(A) receptor antagonist ZM241385. PF induced a nonsignificant elevation in adenosine plasma levels; A2(A) receptor mRNA from leukocytes remained almost unchanged. Adenosine limits the oxidative stress response of PMNs after PFs through an upregulation of the adenosine A2(A) receptor function. This stop signal on inflammation is stronger than that under normal physiologic states and may limit further cytotoxic damage. Pharmacologic manipulation of the adenosine A2(A) receptor pathway could be a potential target for control of unwanted exacerbations of cytotoxic PMN functions.

  9. Oxidant stress and damage in post-ischemic mouse hearts: effects of adenosine.

    PubMed

    Hack, Benjamin; Witting, Paul K; Rayner, Benjamin S; Stocker, Roland; Headrick, John P

    2006-07-01

    Despite the general understanding that ischemia-reperfusion (I/R) promotes oxidant stress, specific contributions of oxidant stress or damage to myocardial I/R injury remain poorly defined. Moreover, whether endogenous 'cardioprotectants' such as adenosine act via limiting this oxidant injury is unclear. Herein we characterized effects of 20 min ischemia and 45 min reperfusion on cardiovascular function, oxidative stress and damage in isolated perfused mouse hearts (with glucose or pyruvate as substrate), and examined whether 10 microM adenosine modified these processes. In glucose-perfused hearts post-ischemic contractile function was markedly impaired (< 50% of pre-ischemia), cell damage assessed by lactate dehydrogenase (LDH) release was increased (12 +/- 2 IU/g vs. 0.2 +/- 0.1 IU/g in normoxic hearts), endothelial-dependent dilation in response to ADP was impaired while endothelial-independent dilation in response to nitroprusside was unaltered. Myocardial oxidative stress increased significantly, based on decreased glutathione redox status ([GSSG]/[GSG + GSSH] = 7.8 +/- 0.3% vs. 1.3 +/- 0.1% in normoxic hearts). Tissue cholesterol, native cholesteryl esters (CE) and the lipid-soluble antioxidant alpha-tocopherol (alpha-TOH, the most biologically active form of vitamin E) were unaffected by I/R, whereas markers of primary lipid peroxidation (CE-derived lipid hydroperoxides and hydroxides; CE-O(O)H) increased significantly (14 +/- 2 vs. 2 +/- 1 pmol/mg in normoxic hearts). Myocardial alpha -tocopherylquinone (alpha-TQ; an oxidation product of alpha -TOH) also increased (10.3 +/- 1.0 vs. 1.7 +/- 0.2 pmol/mg in normoxic hearts). Adenosine treatment improved functional recovery and vascular function, and limited LDH efflux. These effects were associated with an anti-oxidant effect of adenosine, as judged by inhibition of I/R-mediated changes in glutathione redox status (by 60%), alpha-TQ (80%) and CE-O(O)H (100%). Provision of 10 mM pyruvate as sole substrate (to

  10. Role of adipokinetic hormone and adenosine in the anti-stress response in Drosophila melanogaster.

    PubMed

    Zemanová, Milada; Stašková, Tereza; Kodrík, Dalibor

    2016-01-01

    The role of adipokinetic hormone (AKH) and adenosine in the anti-stress response was studied in Drosophila melanogaster larvae and adults carrying a mutation in the Akh gene (Akh(1)), the adenosine receptor gene (AdoR(1)), or in both of these genes (Akh(1) AdoR(1) double mutant). Stress was induced by starvation or by the addition of an oxidative stressor paraquat (PQ) to food. Mortality tests revealed that the Akh(1) mutant was the most resistant to starvation, while the AdoR(1) mutant was the most sensitive. Conversely, the Akh(1) AdoR(1) double mutant was more sensitive to PQ toxicity than either of the single mutants. Administration of PQ significantly increased the Drome-AKH level in w(1118) and AdoR(1) larvae; however, this was not accompanied by a simultaneous increase in Akh gene expression. In contrast, PQ significantly increased the expression of the glutathione S-transferase D1 (GstD1) gene. The presence of both a functional adenosine receptor and AKH seem to be important for the proper control of GstD1 gene expression under oxidative stress, however, the latter appears to play more dominant role. On the other hand, differences in glutathione S-transferase (GST) activity among the strains, and between untreated and PQ-treated groups were minimal. In addition, the glutathione level was significantly lower in all untreated AKH- or AdoR-deficient mutant flies as compared with the untreated control w(1118) flies and further declined following treatment with PQ. All oxidative stress characteristics modified by mutations in Akh gene were restored or even improved by 'rescue' mutation in flies which ectopically express Akh. Thus, the results of the present study demonstrate the important roles of AKH and adenosine in the anti-stress response elicited by PQ in a D. melanogaster model, and provide the first evidence for the involvement of adenosine in the anti-oxidative stress response in insects. PMID:27374982

  11. Two-dimensional strain combined with adenosine stress echocardiography assessment of viable myocardium.

    PubMed

    Fang, Ling-Ling; Zhang, Ping-Yang; Wang, Chong; Wang, Li-Ming; Ma, Xiao-Wu; Shi, Hong-Wei; Feng, Xue-Hong

    2011-03-01

    The objective of this study was to explore a new method for the identification of viable myocardium by means of two-dimensional (2D) strain imaging combined with adenosine stress echocardiography. A total of 15 anesthetized open-chest healthy mongrel dogs underwent left anterior descending coronary artery occlusion for 90 min followed by 120-min reperfusion. Adenosine was infused at 140 μg kg(-1) min(-1) over a period of 6 min. Images were acquired at baseline (when pericardial cradle was made), after reperfusion (when reperfusion finished) and after adenosine administration (while administration stopped). Measurements of the regional peak-systolic strain in radial, circumferential, and longitudinal motion on anterior wall and anterior septum were, respectively, performed under different conditions. The dogs were killed after the echocardiographic studies finished and then the area of infracted myocardium was defined by triphenyltetrazolium chloride histology. A segment with equal or less than 50% area of infracted myocardium was considered to be viable. As a result, 37 regions were viable whereas 53 were non-viable among 90 regions in 15 dogs. At baseline, there was no significant difference in peak-systolic radial strain (Rs), circumferential strain (Cs), and longitudinal strain (Ls) between the viable and non-viable groups. After reperfusion, Rs, Cs, and Ls in absolute value decreased compared to those at baseline in both groups, although there was no significant difference between these groups. Rs and Ls increased after adenosine administration compared to reperfusion (p < 0.01; p < 0.05) in viable group while there were no changes in non-viable group. Compared with non-viable group Rs, Cs and Ls in viable group increased significantly (p < 0.01; 0.05) after adenosine administration. There was a negative correlation between Rs and infarct size (r = -0.72). Cs and Ls correlated well with infarct size, respectively (r = 0.40; 0.67). A change of Rs more than 13

  12. Oxidative Stress Biomarkers and Adenosine Deaminase over the Alopecic Area of the Patients with Alopecia Areata

    PubMed Central

    Öztürk, Perihan; Arıcan, Özer; Kurutaş, Ergül Belge; Mülayim, Kamil

    2016-01-01

    Background: Alopecia areata (AA) is an autoimmune, T-cell mediated, and chronic inflammatory disorder. The pathological mechanisms of disease are unclear, but oxidative stress may be involved. To our knowledge, no studies have examined the oxidative stress levels or biomarkers within the lesional area and skin surface in patients with AA. Similarly, adenosine deaminase (ADA) has not been characterized in AA. Aims: Therefore, we aimed to define ADA levels and the factors involved in oxidative stress from scalp-scrapes of patients with AA. Study Design: Case-control study. Method: A total of 60 patients (30 diagnosed AA patients and 30 healthy controls) were included in the study. ADA as well as oxidative stress factors, including malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were analyzed from scalp-scrapes in both groups and quantified by spectrophotometry. Results: Activities of SOD (p=0.000), CAT (p=0.033), and ADA (p=0.004) as well as levels of GSH (p=0.000) and MDA (p=0.032) in patients with AA were higher than the controls statistically significant. Conclusion: Based on these results, factors associated with oxidative stress were elevated in AA patient scalp-scrapes compared to controls and may have a defined role the disease pathogenesis. Alterations in the activities of antioxidant enzymes from AA patient scraping samples may be a local effect of elevated oxidative stress levels. In this disease, oxidative stress may affect not only hair follicle but also any layers of the skin. PMID:27403388

  13. [Detection of coronary artery disease by adenosine triphosphate stress echocardiography: comparison with adenosine triphosphate stress thallium myocardial scintigraphy and coronary angiography].

    PubMed

    Harada, M; Okura, K; Nishizawa, S; Inoue, T; Sakai, H; Lee, T; Sugiyama, Y; Suzuki, M; Hirai, H; Yamaguchi, T

    1998-09-01

    The clinical feasibility and usefulness of adenosine triphosphate-2Na (ATP) stress echocardiography for the detection of coronary artery disease (CAD) were assessed. Two-dimensional echocardiography and thallium-201 single photon emission computed tomography (SPECT) during ATP infusion were performed simultaneously in 58 consecutive patients (41 men and 17 women; mean age 66 +/- 12 years) with suspected CAD. ATP was infused intravenously at 0.16 mg/kg/min for 5 min and thallium was injected at 4 min. All patients underwent coronary angiography within 2 weeks of ATP echocardiography and ATP SPECT. An ischemic response during ATP infusion was detected by echocardiography as the development or worsening of a wall motion abnormality compared with the baseline and by SPECT as a perfusion defect that filled totally or partially during redistribution. Significant coronary artery stenosis was defined as > or = 75% diameter stenosis in a major epicardial vessel. The severity of the stenosis was classified as follows: Group A, lesions with significant coronary artery stenosis (> or = 75%, < 90%); Group B, lesions with severe coronary artery stenosis (> or = 90%) without collateral circulation; Group C, lesions with severe coronary artery stenosis (> or = 90%) with collateral circulation. Significant CAD was present in 43 of 58 patients. The overall sensitivity, specificity and accuracy of ATP echocardiography for detecting significant CAD were 70%, 100% and 78%, respectively, and those of ATP SPECT were 98%, 87% and 95%, respectively. In patients without previous myocardial infarction, the sensitivity of ATP echocardiography was 67%. The sensitivity of ATP echocardiography and ATP SPECT for detecting myocardial ischemia were 59% and 95% in patients with 1-vessel disease, 75% and 100% in those with 2-vessel disease, and 88% and 100% in those with 3-vessel disease, respectively. The induction of wall motion abnormality by ATP echocardiography was highly concordant with ATP

  14. Temporal analysis of regional strain rate during adenosine triphosphate stress before and after percutaneous coronary interventions.

    PubMed

    Gunji, Kazue; Takagi, Atsushi; Arai, Kotaro; Ashihara, Kyomi; Hagiwara, Nobuhisa

    2015-05-01

    Regional myocardial ischemia is thought to be characterized by diastolic dysfunction. We aimed to clarify whether temporal analysis of strain rate (SR) index derived from two-dimensional speckle-tracking echocardiography (2DTE) can assess the regional myocardial ischemia or not. Forty-two patients with significant coronary stenoses were referred for percutaneous coronary intervention (PCI). 2DTE was performed before and a day after PCI. Time from aortic valve closure to peak early diastolic longitudinal SR ∆(TAVC-E SR) was measured both at baseline and during adenosine triphosphate (ATP) infusion. TAVC-E SR was calculated as TAVC-E SR during ATP infusion subtracted by TAVC-E SR at baseline. In forty-five target ischemic regions, TAVC-E SR at baseline was significantly longer than that of control regions (166 ± 28 vs. 136 ± 32 ms, P < 0.0001). TAVC-E SR in target ischemic regions significantly prolonged during ATP stress to 221 ± 37 ms (P < 0.0001), while it did not change in control regions. Immediately after PCI, TAVC-E SR in target regions significantly decreased to 135 ± 27 ms, P < 0.0001 without prolongation during ATP stress. Receiver operating characteristic curves demonstrated that ∆TAVC-E SR could assess regional myocardial ischemia by a cutoff criterion of 14 ms with sensitivity of 93% and specificity of 95%. 2DTE-derived TAVC-E SR significantly increased during ATP stress only in ischemic myocardium. This phenomenon disappeared immediately after PCI. Temporal analysis of TAVC-E SR appeared to be useful to assess the regional myocardial ischemia. PMID:24633495

  15. Adenosine and the Auditory System

    PubMed Central

    Vlajkovic, Srdjan M; Housley, Gary D; Thorne, Peter R

    2009-01-01

    Adenosine is a signalling molecule that modulates cellular activity in the central nervous system and peripheral organs via four G protein-coupled receptors designated A1, A2A, A2B, and A3. This review surveys the literature on the role of adenosine in auditory function, particularly cochlear function and its protection from oxidative stress. The specific tissue distribution of adenosine receptors in the mammalian cochlea implicates adenosine signalling in sensory transduction and auditory neurotransmission although functional studies have demonstrated that adenosine stimulates cochlear blood flow, but does not alter the resting and sound-evoked auditory potentials. An interest in a potential otoprotective role for adenosine has recently evolved, fuelled by the capacity of A1 adenosine receptors to prevent cochlear injury caused by acoustic trauma and ototoxic drugs. The balance between A1 and A2A receptors is conceived as critical for cochlear response to oxidative stress, which is an underlying mechanism of the most common inner ear pathologies (e.g. noise-induced and age-related hearing loss, drug ototoxicity). Enzymes involved in adenosine metabolism, adenosine kinase and adenosine deaminase, are also emerging as attractive targets for controlling oxidative stress in the cochlea. Other possible targets include ectonucleotidases that generate adenosine from extracellular ATP, and nucleoside transporters, which regulate adenosine concentrations on both sides of the plasma membrane. Developments of selective adenosine receptor agonists and antagonists that can cross the blood-cochlea barrier are bolstering efforts to develop therapeutic interventions aimed at ameliorating cochlear injury. Manipulations of the adenosine signalling system thus hold significant promise in the therapeutic management of oxidative stress in the cochlea. PMID:20190966

  16. Adenosine-stress cardiac magnetic resonance imaging in suspected coronary artery disease: a net cost analysis and reimbursement implications.

    PubMed

    Pilz, Guenter; Patel, Pankaj A; Fell, Ulrich; Ladapo, Joseph A; Rizzo, John A; Fang, Hai; Gunnarsson, Candace; Heer, Tobias; Hoefling, Berthold

    2011-01-01

    The health and economic implications of new imaging technologies are increasingly relevant policy issues. Cardiac magnetic resonance imaging (CMR) is currently not or not sufficiently reimbursed in a number of countries including Germany, presumably because of a limited evidence base. It is unknown, however, whether it can be effectively used to facilitate medical decision-making and reduce costs by serving as a gatekeeper to invasive coronary angiography. We investigated whether the application of CMR in patients suspected of having coronary artery disease (CAD) reduces costs by averting referrals to cardiac catheterization. We used propensity score methods to match 218 patients from a CMR registry to a previously studied cohort in which CMR was demonstrated to reliably identify patients who were low-risk for major cardiac events. Covariates over which patients were matched included comorbidity profiles, demographics, CAD-related symptoms, and CAD risk as measured by Morise scores. We determined the proportion of patients for whom cardiac catheterization was deferred based upon CMR findings. We then calculated the economic effects of practice pattern changes using data on cardiac catheterization and CMR costs. CMR reduced the utilization of cardiac catheterization by 62.4%. Based on estimated catheterization costs of € 619, the utilization of CMR as a gatekeeper reduced per-patient costs by a mean of € 90. Savings were realized until CMR costs exceeded € 386. Cost savings were greatest for patients at low-risk for CAD, as measured by baseline Morise scores, but were present for all Morise subgroups with the exception of patients at the highest risk of CAD. CMR significantly reduces the utilization of cardiac catheterization in patients suspected of having CAD. Per-patient savings range from € 323 in patients at lowest risk of CAD to € 58 in patients at high-risk but not in the highest risk stratum. Because a negative CMR evaluation has high negative

  17. Neuroprotective effects of adenosine isolated from Cordyceps cicadae against oxidative and ER stress damages induced by glutamate in PC12 cells.

    PubMed

    Olatunji, Opeyemi J; Feng, Yan; Olatunji, Oyenike O; Tang, Jian; Ouyang, Zhen; Su, Zhaoliang; Wang, Dujun; Yu, Xiaofeng

    2016-06-01

    Glutamate has been proven to induce oxidative stress through the formation of reactive oxygen species (ROS) and increased calcium overload which results in neuronal injury, development of neurodegenerative diseases and death. Adenosine is one of the bioactive nucleosides found in Cordyceps cicadae and it has displayed several pharmacological activities including neuroprotection. In this study, the protective effects of adenosine from C. cicadae against glutamate-induce oxidative stress in PC12 cells were evaluated. The exposure of PC12 cells to glutamate (5mM) induced the formation of ROS, increased Ca(2+) influx, endoplasmic reticulum (ER) stress and up regulated the expression of pro-apoptotic factor Bax. However, pretreatment with adenosine markedly increased cell viability, decreased the elevated levels of ROS and Ca(2+) induced by glutamate. Furthermore adenosine increased the activities of GSH-Px and SOD, as well as retained mitochondria membrane potential (MMP), increased Bcl-2/Bax ratio, and reduced the expression of ERK, p38, and JNK. Overall, our results suggest that adenosine may be a promising potential therapeutic agent for the prevention and treatment of neurodegenerative disorders. PMID:27114365

  18. Caffeine acts through neuronal adenosine A2A receptors to prevent mood and memory dysfunction triggered by chronic stress.

    PubMed

    Kaster, Manuella P; Machado, Nuno J; Silva, Henrique B; Nunes, Ana; Ardais, Ana Paula; Santana, Magda; Baqi, Younis; Müller, Christa E; Rodrigues, Ana Lúcia S; Porciúncula, Lisiane O; Chen, Jiang Fan; Tomé, Ângelo R; Agostinho, Paula; Canas, Paula M; Cunha, Rodrigo A

    2015-06-23

    The consumption of caffeine (an adenosine receptor antagonist) correlates inversely with depression and memory deterioration, and adenosine A2A receptor (A2AR) antagonists emerge as candidate therapeutic targets because they control aberrant synaptic plasticity and afford neuroprotection. Therefore we tested the ability of A2AR to control the behavioral, electrophysiological, and neurochemical modifications caused by chronic unpredictable stress (CUS), which alters hippocampal circuits, dampens mood and memory performance, and enhances susceptibility to depression. CUS for 3 wk in adult mice induced anxiogenic and helpless-like behavior and decreased memory performance. These behavioral changes were accompanied by synaptic alterations, typified by a decrease in synaptic plasticity and a reduced density of synaptic proteins (synaptosomal-associated protein 25, syntaxin, and vesicular glutamate transporter type 1), together with an increased density of A2AR in glutamatergic terminals in the hippocampus. Except for anxiety, for which results were mixed, CUS-induced behavioral and synaptic alterations were prevented by (i) caffeine (1 g/L in the drinking water, starting 3 wk before and continued throughout CUS); (ii) the selective A2AR antagonist KW6002 (3 mg/kg, p.o.); (iii) global A2AR deletion; and (iv) selective A2AR deletion in forebrain neurons. Notably, A2AR blockade was not only prophylactic but also therapeutically efficacious, because a 3-wk treatment with the A2AR antagonist SCH58261 (0.1 mg/kg, i.p.) reversed the mood and synaptic dysfunction caused by CUS. These results herald a key role for synaptic A2AR in the control of chronic stress-induced modifications and suggest A2AR as candidate targets to alleviate the consequences of chronic stress on brain function.

  19. Caffeine acts through neuronal adenosine A2A receptors to prevent mood and memory dysfunction triggered by chronic stress.

    PubMed

    Kaster, Manuella P; Machado, Nuno J; Silva, Henrique B; Nunes, Ana; Ardais, Ana Paula; Santana, Magda; Baqi, Younis; Müller, Christa E; Rodrigues, Ana Lúcia S; Porciúncula, Lisiane O; Chen, Jiang Fan; Tomé, Ângelo R; Agostinho, Paula; Canas, Paula M; Cunha, Rodrigo A

    2015-06-23

    The consumption of caffeine (an adenosine receptor antagonist) correlates inversely with depression and memory deterioration, and adenosine A2A receptor (A2AR) antagonists emerge as candidate therapeutic targets because they control aberrant synaptic plasticity and afford neuroprotection. Therefore we tested the ability of A2AR to control the behavioral, electrophysiological, and neurochemical modifications caused by chronic unpredictable stress (CUS), which alters hippocampal circuits, dampens mood and memory performance, and enhances susceptibility to depression. CUS for 3 wk in adult mice induced anxiogenic and helpless-like behavior and decreased memory performance. These behavioral changes were accompanied by synaptic alterations, typified by a decrease in synaptic plasticity and a reduced density of synaptic proteins (synaptosomal-associated protein 25, syntaxin, and vesicular glutamate transporter type 1), together with an increased density of A2AR in glutamatergic terminals in the hippocampus. Except for anxiety, for which results were mixed, CUS-induced behavioral and synaptic alterations were prevented by (i) caffeine (1 g/L in the drinking water, starting 3 wk before and continued throughout CUS); (ii) the selective A2AR antagonist KW6002 (3 mg/kg, p.o.); (iii) global A2AR deletion; and (iv) selective A2AR deletion in forebrain neurons. Notably, A2AR blockade was not only prophylactic but also therapeutically efficacious, because a 3-wk treatment with the A2AR antagonist SCH58261 (0.1 mg/kg, i.p.) reversed the mood and synaptic dysfunction caused by CUS. These results herald a key role for synaptic A2AR in the control of chronic stress-induced modifications and suggest A2AR as candidate targets to alleviate the consequences of chronic stress on brain function. PMID:26056314

  20. CMR Catalog Service for the Web

    NASA Technical Reports Server (NTRS)

    Newman, Doug; Mitchell, Andrew

    2016-01-01

    With the impending retirement of Global Change Master Directory (GCMD) Application Programming Interfaces (APIs) the Common Metadata Repository (CMR) was charged with providing a collection-level Catalog Service for the Web (CSW) that provided the same level of functionality as GCMD. This talk describes the capabilities of the CMR CSW API with particular reference to the support of the Committee on Earth Observation Satellites (CEOS) Working Group on Information Systems and Services (WGISS) Integrated Catalog (CWIC).

  1. Complex Signaling Network in Regulation of Adenosine 5′-Phosphosulfate Reductase by Salt Stress in Arabidopsis Roots1[W

    PubMed Central

    Koprivova, Anna; North, Kathryn Anne; Kopriva, Stanislav

    2008-01-01

    Sulfur-containing compounds play an important role in plant stress defense; however, only a little is known about the molecular mechanisms of regulation of sulfate assimilation by stress. Using known Arabidopsis (Arabidopsis thaliana) mutants in signaling pathways, we analyzed regulation of the key enzyme of sulfate assimilation, adenosine 5′-phosphosulfate reductase (APR), by salt stress. APR activity and mRNA levels of all three APR isoforms increased 3-fold in roots after 5 h of treatment with 150 mm NaCl. The regulation of APR was not affected in mutants deficient in abscisic acid (ABA) synthesis and treatment of the plants with ABA did not affect the mRNA levels of APR isoforms, showing that APR is regulated by salt stress in an ABA-independent manner. In mutants deficient in jasmonate, salicylate, or ethylene signaling, APR mRNA levels were increased upon salt exposure similar to wild-type plants. Surprisingly, however, APR enzyme activity was not affected by salt in these plants. The same result was obtained in mutants affected in cytokinin and auxin signaling. Signaling via gibberellic acid, on the other hand, turned out to be essential for the increase in APR mRNA by salt treatment. These results demonstrate an extensive posttranscriptional regulation of plant APR and reveal that the sulfate assimilation pathway is controlled by a complex network of multiple signals on different regulatory levels. PMID:18218969

  2. Adenosine protects Sprague Dawley rats from high-fat diet and repeated acute restraint stress-induced intestinal inflammation and altered expression of nutrient transporters.

    PubMed

    Lee, C Y

    2015-04-01

    This study investigated the effect of repeated acute restraint stress and high-fat diet (HFD) on intestinal expression of nutrient transporters, concomitant to intestinal inflammation. The ability of adenosine to reverse any change was examined. Six-week-old male Sprague Dawley rats were divided into eight groups: control or non-stressed (C), rats exposed to restraint stress for 6 h per day for 14 days (S), control rats fed with HFD (CHF) and restraint-stressed rats fed with HFD (SHF); four additional groups received the same treatments and were also given 50 mg/l adenosine dissolved in drinking water. Fasting blood glucose, plasma insulin, adiponectin and corticosterone were measured. Intestinal expression of SLC5A1, SLC2A2, NPC1L1 and TNF-α was analysed. Histological evaluation was conducted to observe for morphological and anatomical changes in the intestinal tissues. Results showed that HFD feeding increased glucose and insulin levels, and repeated acute restraint stress raised the corticosterone level by 22%. Exposure to both stress and HFD caused a further increase in corticosterone to 41%, while decreasing plasma adiponectin level. Restraint stress altered intestinal expression of SLC5A1, SLC2A2 and NPC1L1. These changes were enhanced in SHF rats. Adenosine was found to alleviate HFD-induced increase in glucose and insulin levels, suppress elevation of corticosterone in S rats and improve the altered nutrient transporters expression profiles. It also prevented upregulation of TNF-α in the intestine of SHF rats. In summary, a combination of stress and HFD exaggerated stress- and HFD-induced pathophysiological changes in the intestine, and biochemical parameters related to obesity. Adenosine attenuated the elevation of corticosterone and altered expression of SLC5A1, NPC1L1 and TNF-α.

  3. Myocardial uptake and clearance of T1-201 in healthy subjects: Comparison of adenosine-induced hyperemia and exercise stress

    SciTech Connect

    Siffring, P.A.; Gupta, N.C.; Mohiuddin, S.M.; Esterbrooks, D.J.; Hilleman, D.E.; Cheng, S.C.; Sketch, M.H. Sr.; Frick, M.P. )

    1989-12-01

    Pharmacologic stress testing with dipyridamole is useful in patients undergoing thallium-201 myocardial perfusion scintigraphy who cannot adequately exercise. Because dipyridamole increases coronary blood flow by reducing the metabolism of adenosine, the authors compared the uptake and clearance of T1-201 following exercise stress testing (EST) and resting intravenous infusion of adenosine (AI) in crossover fashion in 20 healthy men. No perfusion defects or areas of redistribution were noted in any of the scans. Mean absolute myocardial T1-201 uptake was 1.3 times greater with AI than with EST. Mean absolute extracardiac uptake was 2.0 times greater with AI. Mean T1-201 myocardial clearance was virtually the same in all AI and EST views. During AI, 70% of the subjects experienced subjective side effects, mean arterial blood pressure decreased by 15%, and heart rate increased by 48%. The effects of adenosine on T1-201 kinetics in the myocardium are similar to those of EST. Adenosine may be useful as a pharmacologic stress agent in patients undergoing T1-201 myocardial perfusion scintigraphy.

  4. Qualitative and Quantitative Assessment of Adenosine Triphosphate Stress Whole-Heart Dynamic Myocardial Perfusion Imaging Using 256-Slice Computed Tomography

    PubMed Central

    Kurata, Akira; Kawaguchi, Naoto; Kido, Teruhito; Inoue, Katsuji; Suzuki, Jun; Ogimoto, Akiyoshi; Funada, Jun-ichi; Higaki, Jitsuo; Miyagawa, Masao; Vembar, Mani; Mochizuki, Teruhito

    2013-01-01

    Background The aim of this study was to investigate the correlation of the qualitative transmural extent of hypoperfusion areas (HPA) using stress dynamic whole-heart computed tomography perfusion (CTP) imaging by 256-slice CT with CTP-derived myocardial blood flow (MBF) for the estimation of the severity of coronary artery stenosis. Methods and Results Eleven patients underwent adenosine triphosphate (0.16 mg/kg/min, 5 min) stress dynamic CTP by 256-slice CT (coverage: 8 cm, 0.27 s/rotation), and 9 of the 11 patients underwent coronary angiography (CAG). Stress dynamic CTP (whole–heart datasets over 30 consecutive heart beats in systole without spatial and temporal gaps) was acquired with prospective ECG gating (effective radiation dose: 10.4 mSv). The extent of HPAs was visually graded using a 3-point score (normal, subendocardial, transmural). MBF (ml/100g/min) was measured by deconvolution. Differences in MBF (mean ± standard error) according to HPA and CAG results were evaluated. In 27 regions (3 major coronary territories in 9 patients), 11 coronary stenoses (> 50% reduction in diameter) were observed. In 353 myocardial segments, HPA was significantly related to MBF (P < 0.05; normal 295 ± 94; subendocardial 186 ± 67; and transmural 80 ± 53). Coronary territory analysis revealed a significant relationship between coronary stenosis severity and MBF (P < 0.05; non-significant stenosis [< 50%], 284 ± 97; moderate stenosis [50–70%], 184 ± 74; and severe stenosis [> 70%], 119 ± 69). Conclusion The qualitative transmural extent of HPA using stress whole-heart dynamic CTP imaging by 256-slice CT exhibits a good correlation with quantitative CTP-derived MBF and may aid in assessing the hemodynamic significance of coronary artery disease. PMID:24376774

  5. Efficacy of coronary fractional flow reserve using contrast medium compared to adenosine

    PubMed Central

    Tanboğa, Ibrahim Halil; Aksakal, Enbiya; Aksu, Uğur; Gulcu, Oktay; Birdal, Oğuzhan; Arısoy, Arif; Kalaycı, Arzu; Ulusoy, Fatih Rifat; Sevimli, Serdar

    2016-01-01

    Introduction Coronary fractional flow reserve (FFR) is recommended as the gold standard method in evaluating intermediate coronary stenoses. However, there are significant debates concerning the agents and the timing of the measurement. Aim To compare the contrast medium induced Pd/Pa ratio (CMR) with the FFR. Material and methods We enrolled 28 consecutive patients with 34 intermediate lesions who underwent coronary FFR measurement by intracoronary (i.c.) adenosine. After baseline Pd/Pa was calculated, a single contrast medium (Iomeron) injection of 6 ml (3 ml/s) was performed manually. Within 10 s after the contrast medium injection, the CMR was calculated. Bolus injection of i.c. adenosine was performed to induce maximal hyperemia (from 60 µg to 600 µg), and when it was ≤ 0.80, the intermediate lesion was considered as significant. Results After bolus i.c. adenosine, 12 lesions of 34 (35.3%) were identified as significant. The CMR value was 0.86 ±0.06 (range: 0.71–0.97). There were no significant differences between FFR and CMR values (p = 0.108). A substantial positive correlation between adenosine and contrast values was detected (0.886 and p < 0.001). Good agreement in Bland-Altman analysis was revealed (mean bias was 0.027, 95% confidence interval 0.038–0.092). Receiver operating characteristics curve analysis showed 90.9% sensitivity and 91.7% specificity for a cut-off value of 0.85 for the CMR compared to FFR (≤ 0.80). Conclusions Our study showed that measuring the CMR is a feasible method compared to FFR. The CMR may be used in situations where adenosine cannot be administered. PMID:27625683

  6. Making Metadata Better with CMR and MMT

    NASA Technical Reports Server (NTRS)

    Gilman, Jason Arthur; Shum, Dana

    2016-01-01

    Ensuring complete, consistent and high quality metadata is a challenge for metadata providers and curators. The CMR and MMT systems provide providers and curators options to build in metadata quality from the start and also assess and improve the quality of already existing metadata.

  7. Adenosine and sleep

    SciTech Connect

    Yanik, G.M. Jr.

    1987-01-01

    Behavioral and biochemical approaches have been used to determine the relative contribution of endogenous adenosine and adenosine receptors to the sleep-wake cycle in the rat. Adenosine concentrations in specific areas of the rat brain were not affected by 24 hours of total sleep deprivation, or by 24 or 48 hours of REM sleep deprivation. In order to assess the effect of REM sleep deprivation on adenosine A/sub 1/ receptors, /sup 3/H-L-PIA binding was measured. The Bmax values for /sup 3/H-L-PIA binding to membrane preparations of the cortices and corpus striata from 48 hour REM sleep-deprived animals were increased 14.8% and 23%, respectively. These increases were not maintained following the cessation of sleep deprivation and recovered within 2 hours. The results of a 96 hour REM deprivation experiment were similar to those of the 48 hour REM sleep deprivation experiment. However, these increases were not evident in similar structures taken from stress control animals, and conclusively demonstrated that the changes in /sup 3/H-L-PIA binding resulted from REM sleep deprivation and not from stress.

  8. Regadenoson and adenosine are equivalent vasodilators and are superior than dipyridamole- a study of first pass quantitative perfusion cardiovascular magnetic resonance

    PubMed Central

    2013-01-01

    Background Regadenoson, dipyridamole and adenosine are commonly used vasodilators in myocardial perfusion imaging for the detection of obstructive coronary artery disease. There are few comparative studies of the vasodilator properties of regadenoson, adenosine and dipyridamole in humans. The specific aim of this study was to determine the relative potency of these three vasodilators by quantifying stress and rest myocardial perfusion in humans using cardiovascular magnetic resonance (CMR). Methods Fifteen healthy normal volunteers, with Framingham score less than 1% underwent vasodilator stress testing with regadenoson (400 μg bolus), dipyridamole (0.56 mg/kg) and adenosine (140 μg /kg/min) on separate days. Rest perfusion imaging was performed initially. Twenty minutes later, stress imaging was performed at peak vasodilation, i.e. 70 seconds after regadenoson, 4 minutes after dipyridamole infusion and between 3–4 minutes of the adenosine infusion. Myocardial blood flow (MBF) in ml/min/g and myocardial perfusion reserve (MPR) were quantified using a fully quantitative model constrained deconvolution. Results Regadenoson produced higher stress MBF than dipyridamole and adenosine (3.58 ± 0.58 vs. 2.81 ± 0.67 vs. 2.78 ± 0.61 ml/min/g, p = 0.0009 and p = 0.0008 respectively). Regadenoson had a much higher heart rate response than adenosine and dipyridamole respectively (95 ± 11 vs. 76 ± 13 vs. 86 ± 12 beats/ minute) When stress MBF was adjusted for heart rate, there were no differences between regadenoson and adenosine (37.8 ± 6 vs. 36.6 ± 4 μl/sec/g, p = NS), but differences between regadenoson and dipyridamole persisted (37.8 ± 6 vs. 32.6 ± 5 μl/sec/g, p = 0.03). The unadjusted MPR was higher with regadenoson (3.11 ± 0.63) when compared with adenosine (2.7 ± 0.61, p = 0.02) and when compared with dipyridamole (2.61 ± 0.57, p = 0.04). Similar to stress MBF, these differences in MPR between regadenoson and adenosine were abolished when adjusted

  9. Interventional CMR: Clinical Applications and Future Directions

    PubMed Central

    Rogers, Toby

    2015-01-01

    Interventional cardiovascular magnetic resonance (iCMR) promises to enable radiation-free catheterization procedures and to enhance contemporary image guidance for structural heart and electrophysiological interventions. However, clinical translation of exciting pre-clinical interventions has been limited by availability of devices that are safe to use in the magnetic resonance (MR) environment. We discuss challenges and solutions for clinical translation, including MR-conditional and MR-safe device design, and how to configure an interventional suite. We review the recent advances that have already enabled diagnostic MR right heart catheterization and simple electrophysiologic ablation to be performed in humans and explore future clinical applications. PMID:25894793

  10. Cardioprotective Benefits of Adenosine Triphosphate: Sensitive Potassium Channel Opener Diazoxide Are Lost with Administration after the Onset of Stress in Mouse and Human Myocytes

    PubMed Central

    Janjua, M Burhan; Makepeace, Carol M; Anastacio, Melissa M; Schuessler, Richard B; Nichols, Colin G; Lawton, Jennifer S

    2014-01-01

    Background Adenosine triphosphate - sensitive (KATP) potassium channel opener diazoxide (DZX) maintains myocyte volume and contractility during stress via an unknown mechanism when administered at the onset of stress. This study was performed to investigate the cardioprotective potential of DZX when added after the onset of the stresses of hyperkalemic cardioplegia, metabolic inhibition, and hypo osmotic stress. Study Design Isolated mouse ventricular and human atrial myocytes were exposed to control Tyrode’s solution (TYR) for 10–20 min, test solution for 30 min (hypothermic hyperkalemic cardioplegia (CPG), CPG + 100uM diazoxide (CPG+DZX), metabolic inhibition (MI), MI+DZX, mild hypo osmotic stress (0.9T), or 0.9T + DZX) with DZX added after 10 or 20 min stress, followed by 20 min re-exposure to TYR (+/− DZX). Myocyte volume (human + mouse) and contractility (mouse) were compared. Results Mouse and human myocytes demonstrated significant swelling during exposure to CPG, MI, and hypo osmotic stress that was not prevented by DZX when administered either at 10 or 20 min after the onset of stress. Contractility following the stress of CPG in mouse myocytes significantly declined when DZX was administered 20 min after the onset of stress (p<0.05 vs. TYR). Contractility following hypo osmotic stress in mouse myocytes was not altered by the addition of DZX. Conclusions To maintain myocyte volume homeostasis and contractility during stress (hyperkalemic cardioplegia, metabolic inhibition, and hypo osmotic stress), KATP channel opener diazoxide requires administration at the onset of stress in this isolated myocyte model. These data have potential implications for any future clinical application of diazoxide. PMID:25158912

  11. Adenosine induced coronary spasm – A rare presentation

    PubMed Central

    Arora, P.; Bhatia, V.; Arora, M.; Kaul, U.

    2014-01-01

    Adenosine is commonly used as a pharmacological agent in myocardial perfusion imaging, as an antiarrhythmic agent, and in Cath Lab. during PCI for treating no reflow phenomenon. Coronary spasm has been reported following adenosine injection during stress imaging. We report a rare complication with ST segment elevation, following adenosine injection, given for treatment of supraventricular tachycardia. PMID:24581102

  12. Regulation of Cardiovascular Development by Adenosine and Adenosine-Mediated Embryo Protection

    PubMed Central

    Rivkees, Scott A.; Wendler, Christopher C.

    2012-01-01

    Few signaling molecules have the potential to influence the developing mammal as the nucleoside adenosine. Adenosine levels increase rapidly with tissue hypoxia and inflammation. Adenosine antagonists include the methlyxanthines caffeine and theophylline. The receptors that transduce adenosine action are the A1, A2a, A2b, and A3 adenosine receptors (ARs). We examined how adenosine acts via A1ARs to influence embryo development. Transgenic mice were studied along with embryo cultures. Embryos lacking A1ARs were markedly growth retarded following intrauterine hypoxia exposure. Studies of mice selectively lacking A1AR in the heart identify the heart as a key site of adenosines embryo protective effects. Studies of isolated embryos showed that adenosine plays a key role in modulating embryo cardiac function, especially in the setting of hypoxia. When pregnant mice were treated during embryogenesis with the adenosine antagonist caffeine, adult mice had abnormal heart function. Adenosine acts via A1ARs to play an essential role in protecting the embryo against intra uterine stress, and adenosine antagonists, including caffeine, may be an unwelcome exposure for the embryo. PMID:22423036

  13. Melanin biosynthesis in the maize pathogen Cochliobolus heterostrophus depends on two mitogen-activated protein kinases, Chk1 and Mps1, and the transcription factor Cmr1.

    PubMed

    Eliahu, Noa; Igbaria, Aeid; Rose, Mark S; Horwitz, Benjamin A; Lev, Sophie

    2007-03-01

    The maize pathogen Cochliobolus heterostrophus requires two mitogen-activated protein kinases (MAPKs), Chk1 and Mps1, to produce normal pigmentation. Young colonies of mps1 and chk1 deletion mutants have a white and autolytic appearance, which was partially rescued by a hyperosmotic environment. We isolated the transcription factor Cmr1, an ortholog of Colletotrichum lagenarium Cmr1 and Magnaporthe grisea Pig1, which regulates melanin biosynthesis in C. heterostrophus. Deletion of CMR1 in C. heterostrophus resulted in mutants that lacked dark pigmentation and acquired an orange-pink color. In cmr1 deletion strains the expression of putative scytalone dehydratase (SCD1) and hydroxynaphthalene reductase (BRN1 and BRN2) genes involved in melanin biosynthesis was undetectable, whereas expression of PKS18, encoding a polyketide synthase, was only moderately reduced. In chk1 and mps1 mutants expression of PKS18, SCD1, BRN1, BRN2, and the transcription factor CMR1 itself was very low in young colonies, slightly up-regulated in aging colonies, and significantly induced in hyperosmotic conditions, compared to invariably high expression in the wild type. These findings indicate that two MAPKs, Chk1 and Mps1, affect Cmr1 at the transcriptional level and this influence is partially overridden in stress conditions including aging culture and hyperosmotic environment. Surprisingly, we found that the CMR1 gene was transcribed in both sense and antisense directions, apparently producing mRNA as well as a long noncoding RNA transcript. Expression of the antisense CMR1 was also Chk1 and Mps1 dependent. Analysis of chromosomal location of the melanin biosynthesis genes in C. heterostrophus resulted in identification of a small gene cluster comprising BRN1, CMR1, and PKS18. Since expression of all three genes depends on Chk1 and Mps1 MAPKs, we suggest their possible epigenetic regulation. PMID:17237364

  14. Achieving Sub-Second Search in the CMR

    NASA Astrophysics Data System (ADS)

    Gilman, J.; Baynes, K.; Pilone, D.; Mitchell, A. E.; Murphy, K. J.

    2014-12-01

    The Common Metadata Repository (CMR) is the next generation Earth Science Metadata catalog for NASA's Earth Observing data. It joins together the holdings from the EOS Clearing House (ECHO) and the Global Change Master Directory (GCMD), creating a unified, authoritative source for EOSDIS metadata. The CMR allows ingest in many different formats while providing consistent search behavior and retrieval in any supported format. Performance is a critical component of the CMR, ensuring improved data discovery and client interactivity. The CMR delivers sub-second search performance for any of the common query conditions (including spatial) across hundreds of millions of metadata granules. It also allows the addition of new metadata concepts such as visualizations, parameter metadata, and documentation. The CMR's goals presented many challenges. This talk will describe the CMR architecture, design, and innovations that were made to achieve its goals. This includes: * Architectural features like immutability and backpressure. * Data management techniques such as caching and parallel loading that give big performance gains. * Open Source and COTS tools like Elasticsearch search engine. * Adoption of Clojure, a functional programming language for the Java Virtual Machine. * Development of a custom spatial search plugin for Elasticsearch and why it was necessary. * Introduction of a unified model for metadata that maps every supported metadata format to a consistent domain model.

  15. Functional assessment of sequential coronary artery fistula and coronary artery stenosis with fractional flow reserve and stress adenosine myocardial perfusion imaging.

    PubMed

    Yew, Kuan Leong; Ooi, Poh Siang; Law, Chiong Soon

    2015-10-01

    Coronary artery fistula is an abnormal connection between one coronary artery to another coronary artery or cardiac chambers. The coronary artery fistula may cause significant shunting of blood and cause "pseudo-stenosis" or "steal phenomenon". This will also accentuate pre-existing mild-moderate de novo coronary lesions with resultant greater pressure gradient difference across the lesions. Thus, fractional flow reserve can be a useful tool to guide intervention decision on the coronary artery fistula. There are very few published reports regarding the use of FFR to assess coronary artery fistula. In fact, there is no outcome data regarding the deferment of coronary artery fistula intervention when the FFR is not physiologically significant. This case highlighted the use of FFR to evaluate the functional significance of coronary fistula in the setting of ischemia evaluation and it was proven to be safe to defer intervention with good 3 year clinical outcome. Stress adenosine myocardial perfusion imaging correlated with the FFR result.

  16. Relation between QT dispersion and adenosine triphosphate stress thallium-201 single-photon emission computed tomographic imaging for detecting myocardial ischemia and scar.

    PubMed

    Teragawa, H; Hirao, H; Muraoka, Y; Yamagata, T; Matsuura, H; Kajiyama, G

    1999-04-15

    It is not known if QT dispersion is useful for detecting coronary artery disease. We investigated whether QT dispersion at baseline and during adenosine triphosphate (ATP) infusion correlate with the imaging patterns obtained from ATP stress thallium-201 single-photon emission computed tomography (ATP-SPECT). QT dispersion was determined in 169 patients who underwent ATP-SPECT from 12-lead electrocardiograms obtained at baseline and 3 minutes after the beginning of ATP infusion. Based on the results of ATP-SPECT, patients were divided into 4 groups: normal (n = 55), ischemia (n = 38), ischemia and scar (n = 42), and scar (n = 34). Baseline QT dispersions (mean +/- SD) in the normal, ischemia, ischemia and scar, and scar groups were 48 +/- 15, 50 +/- 17, 69 +/- 25, and 70 +/- 24 ms, respectively. Baseline QT dispersion was significantly greater in the groups with myocardial scar. QT dispersions during ATP infusion were 43 +/- 16, 63 +/- 20, 76 +/- 20, and 62 +/- 25 ms in the normal, ischemia, ischemia and scar, and scar groups, respectively. QT dispersion increased with ATP infusion in patients with myocardial ischemia. QT dispersion at baseline and during ATP infusion correlated with the ATP-SPECT imaging pattern. These findings suggest that baseline QT dispersion and ATP-induced changes in QT dispersion may help detect the presence of myocardial ischemia and scar. PMID:10215275

  17. Dietary effects of adenosine monophosphate to enhance growth, digestibility, innate immune responses and stress resistance of juvenile red sea bream, Pagrus major.

    PubMed

    Hossain, Md Sakhawat; Koshio, Shunsuke; Ishikawa, Manabu; Yokoyama, Saichiro; Sony, Nadia Mahjabin

    2016-09-01

    Our study explored the dietary effects of adenosine monophosphate (AMP) to enhance growth, digestibility, innate immune responses and stress resistance of juvenile red sea bream. A semi-purified basal diet supplemented with 0% (Control), 0.1% (AMP-0.1), 0.2% (AMP-0.2), 0.4% (AMP-0.4) and 0.8% (AMP-0.8) purified AMP to formulate five experimental diets. Each diet was randomly allocated to triplicate groups of fish (mean initial weight 3.4 g) for 56 days. The results indicated that dietary AMP supplements tended to improve growth performances. One of the best ones was found in diet group AMP-0.2, followed by diet groups AMP-0.1, AMP-0.4 and AMP-0.8. The Apparent digestibility coefficients (dry matter, protein and lipid) also improved by AMP supplementation and the significantly highest dry matter digestibility was observed in diet group AMP-0.2. Fish fed diet groups AMP-0.2 and AMP-0.4 had significantly higher peroxidase and bactericidal activities than fish fed the control diet. Nitro-blue-tetrazolium (NBT) activity was found to be significantly (P < 0.05) greater in fish fed diet groups AMP-0.4 and AMP-0.8. Total serum protein, lysozyme activity and agglutination antibody titer were also increased (P > 0.05) by dietary supplementation. In contrast, catalase activity decreased with AMP supplementation. Moreover, the fish fed AMP supplemented diets had better improvement (P < 0.05) in body lipid contents, condition factor, hematocrit content and glutamyl oxaloacetic transaminase (GOT) level than the control group. Supplementation also improved both freshwater and oxidative stress resistances. Interestingly, the fish fed diet groups AMP-0.2 and AMP-0.4 showed the least oxidative stress condition. Finally it is concluded that, dietary AMP supplementation enhanced the growth, digestibility, immune response and stress resistance of red sea bream. The regression analysis revealed that a dietary AMP supplementation between 0.2 and 0.4% supported weight gain and

  18. Cardiac functional analysis by free-breath real-time cine CMR with a spatiotemporal filtering method, TSENSE: comparison with breath-hold cine CMR.

    PubMed

    Yamamuro, Masaki; Tadamura, Eiji; Kanao, Shotaro; Okayama, Satoshi; Okamoto, Jun; Urayama, Shinichi; Kimura, Takeshi; Komeda, Masashi; Kita, Toru; Togashi, Kaori

    2006-01-01

    The aim of this study was to assess the accuracy of cardiac functional values obtained from free-breathing real-time cine CMR with the temporal sensitivity encoding (TSENSE) technique by comparing them with values obtained from conventional cine CMR. For the real-time cine CMR, two protocols were employed, one with good temporal resolution and one with good spatial resolution. The functional values obtained from the high temporal resolution real-time cine CMR agreed and correlated well with those of cine CMR. On the other hand, statistically significant but clinically slight overestimation of ESV (p < .05) and underestimation of EF (p < .01) were observed with the other protocol. Real-time cine CMR with TSENSE can provide acceptable cardiac functional values.

  19. In vivo levels of diadenosine tetraphosphate and adenosine tetraphospho-guanosine in Physarum polycephalum during the cell cycle and oxidative stress.

    PubMed Central

    Garrison, P N; Mathis, S A; Barnes, L D

    1986-01-01

    Cellular levels of diadenosine tetraphosphate (Ap4A) and adenosine tetraphospho-guanosine (Ap4G) were specifically measured during the cell cycle of Physarum polycephalum by a high-pressure liquid chromatographic method. Ap4A was also measured indirectly by a coupled phosphodiesterase-luciferase assay. No cell cycle-specific changes in either Ap4A or Ap4G were detected in experiments involving different methods of assay, different strains of P. polycephalum, or different methods of fixation of macroplasmodia. Our results on Ap4A are in contrast with those reported previously (C. Weinmann-Dorsch, G. Pierron, R. Wick, H. Sauer, and F. Grummt, Exp. Cell Res. 155:171-177, 1984). Weinmann-Dorsch et al. reported an 8- to 30-fold increase in Ap4A in early S phase in P. polycephalum, as measured by the phosphodiesterase-luciferase assay. We also measured levels of Ap4A, Ap4G, and ATP in macroplasmodia treated with 0.1 mM dinitrophenol. Ap4A and Ap4G transiently increased three- to sevenfold after 1 h and then decreased concomitantly with an 80% decrease in the level of ATP after 2 h in the presence of dinitrophenol. These results do not support the hypothesis that Ap4A is a positive pleiotypic activator that modulates DNA replication, but they are consistent with the hypothesis proposed for procaryotes that Ap4A and Ap4G are signal nucleotides or alarmones of oxidative stress (B.R. Bochner, P.C. Lee, S.W. Wilson, C.W. Cutler, and B.N. Ames, Cell 37:225-232, 1984). PMID:3785160

  20. In adenosine A2B knockouts acute treatment with inorganic nitrate improves glucose disposal, oxidative stress, and AMPK signaling in the liver

    PubMed Central

    Peleli, Maria; Hezel, Michael; Zollbrecht, Christa; Persson, A. Erik G.; Lundberg, Jon O.; Weitzberg, Eddie; Fredholm, Bertil B.; Carlström, Mattias

    2015-01-01

    Rationale: Accumulating studies suggest that nitric oxide (NO) deficiency and oxidative stress are central pathological mechanisms in type 2 diabetes (T2D). Recent findings demonstrate therapeutic effects by boosting the nitrate-nitrite-NO pathway, which is an alternative pathway for NO formation. This study aimed at investigating the acute effects of inorganic nitrate on glucose and insulin signaling in adenosine A2B receptor knockout mice (A−/−2B), a genetic mouse model of impaired metabolic regulation. Methods: Acute effects of nitrate treatment were investigated in aged wild-type (WT) and A−/−2B mice. One hour after injection with nitrate (0.1 mmol/kg, i.p.) or placebo, metabolic regulation was evaluated by intraperitoneal glucose and insulin tolerance tests. NADPH oxidase-mediated superoxide production and AMPK phosphorylation were measured in livers obtained from non-treated or glucose-treated mice, with or without prior nitrate injection. Plasma was used to determine insulin resistance (HOMA-IR) and NO signaling. Results: A−/−2B displayed increased body weight, reduced glucose clearance, and attenuated overall insulin responses compared with age-matched WT mice. Nitrate treatment increased circulating levels of nitrate, nitrite and cGMP in the A−/−2B, and improved glucose clearance. In WT mice, however, nitrate treatment did not influence glucose clearance. HOMA-IR increased following glucose injection in the A−/−2B, but remained at basal levels in mice pretreated with nitrate. NADPH oxidase activity in livers from A−/−2B, but not WT mice, was reduced by nitrate treatment. Livers from A−/−2B displayed reduced AMPK phosphorylation compared with WT mice, and this was increased by nitrate treatment. Finally, injection with the anti-diabetic agent metformin induced similar therapeutic effects in the A−/−2B as observed with nitrate. Conclusion: The A−/−2B mouse is a genetic mouse model of metabolic syndrome. Acute treatment

  1. Oxidative Stress Parameters and Erythrocyte Membrane Adenosine Triphosphatase Activities in Streptozotocin-induced Diabetic Rats Administered Aqueous Preparation of Kalanchoe Pinnata Leaves

    PubMed Central

    Menon, Nikhil; Sparks, Jean; Omoruyi, Felix O.

    2016-01-01

    Background: Diabetes mellitus is a chronic metabolic disease that according to the World Health Organization affects more than 382 million people. The rise in diabetes mellitus coupled with the lack of an effective treatment has led many to investigate medicinal plants to identify a viable alternative. Objective: To evaluate red blood cell (RBC) membrane adenosine triphosphatase (ATPase) activities and antioxidant levels in streptozotocin-induced diabetic rats administered aqueous preparation of Kalanchoe pinnata leaves. Materials and Methods: Diabetes mellitus was induced in rats by a single administration of streptozotocin (60 mg/kg). Diabetic rats were then treated with aqueous K. pinnata preparation (three mature leaves ~ 9.96 g/70 kg body weight or about 0.14 g/kg body weight/day) for 30 days. Serum glucose, RBC membrane ATPase activities, and antioxidant levels were determined. Results: We noted weight loss and reduced food consumption in the treated diabetic group. Serum glucose levels were reduced in the treated diabetic group compared to the other groups. Superoxide dismutase activity and glutathione levels were not significantly elevated in the treated group compared to the diabetic group. However, serum catalase activity was significantly (P < 0.05) increased in the treated diabetic group compared to the other groups. Serum thiobarbituric acid reactive substances were not significantly altered among the groups. There was a significant (P < 0.05) increase in Mg2+ ATPase activity and a nonsignificant increase in Na+/K+ ATPase activity in the RBC membrane of the treated diabetic group compared to the diabetic group. Conclusion: The consumption of aqueous preparation of K. pinnata may accrue benefits in the management of diabetes by lowering oxidative stress often associated with the disease and improving the availability of cellular magnesium through an increase in the magnesium ATPase pump in the RBC membrane for increased cellular metabolism of glucose

  2. Use of adenosine echocardiography for diagnosis of coronary artery disease

    SciTech Connect

    Zoghbi, W.A. )

    1991-07-01

    Two-dimensional echocardiography combined with exercise is sensitive and specific in the detection of coronary artery disease (CAD) by demonstrating transient abnormalities in wall motion. Frequently, however, patients cannot achieve maximal exercise because of various factors. Pharmacologic stress testing with intravenous adenosine was evaluated as a means of detecting CAD in a noninvasive manner. Patients with suspected CAD underwent echocardiographic imaging and simultaneous thallium 201 single-photon emission computed tomography during the intravenous administration of 140 micrograms/kg/min of adenosine. An increase in heart rate, decrease in blood pressure, and increase in double product were observed during adenosine administration. Initial observations revealed that wall motion abnormalities were induced by adenosine in areas of perfusion defects. The adenosine infusion was well tolerated, and symptoms disappeared within 1 to 2 minutes after termination of the infusion. Therefore preliminary observations suggest that adenosine echocardiography appears to be useful in the assessment of CAD.

  3. Qualitative grading of aortic regurgitation: a pilot study comparing CMR 4D flow and echocardiography.

    PubMed

    Chelu, Raluca G; van den Bosch, Annemien E; van Kranenburg, Matthijs; Hsiao, Albert; van den Hoven, Allard T; Ouhlous, Mohamed; Budde, Ricardo P J; Beniest, Kirsten M; Swart, Laurens E; Coenen, Adriaan; Lubbers, Marisa M; Wielopolski, Piotr A; Vasanawala, Shreyas S; Roos-Hesselink, Jolien W; Nieman, Koen

    2016-02-01

    Over the past 10 years there has been intense research in the development of volumetric visualization of intracardiac flow by cardiac magnetic resonance (CMR).This volumetric time resolved technique called CMR 4D flow imaging has several advantages over standard CMR. It offers anatomical, functional and flow information in a single free-breathing, ten-minute acquisition. However, the data obtained is large and its processing requires dedicated software. We evaluated a cloud-based application package that combines volumetric data correction and visualization of CMR 4D flow data, and assessed its accuracy for the detection and grading of aortic valve regurgitation using transthoracic echocardiography as reference. Between June 2014 and January 2015, patients planned for clinical CMR were consecutively approached to undergo the supplementary CMR 4D flow acquisition. Fifty four patients(median age 39 years, 32 males) were included. Detection and grading of the aortic valve regurgitation using CMR4D flow imaging were evaluated against transthoracic echocardiography. The agreement between 4D flow CMR and transthoracic echocardiography for grading of aortic valve regurgitation was good (j = 0.73). To identify relevant,more than mild aortic valve regurgitation, CMR 4D flow imaging had a sensitivity of 100 % and specificity of 98 %. Aortic regurgitation can be well visualized, in a similar manner as transthoracic echocardiography, when using CMR 4D flow imaging. PMID:26498478

  4. Microvascular Obstruction Evaluation Using Cardiovascular Magnetic Resonance (CMR) in ST-Elevated Myocardial Infarction (STEMI) Patients

    PubMed Central

    Piotrowska-Kownacka, Dorota; Kownacki, Łukasz; Kochman, Janusz; Kołodzińska, Agnieszka; Kobylecka, Małgorzata; Królicki, Leszek

    2015-01-01

    Summary Backround Restoration of blood flow in epicardial coronary artery in patients with acute myocardial infarction can, but does not have to restore efficient blood flow in coronary circulation. The aim of the study was a direct comparison of microvascular obstruction (MVO) detected by rest and stress perfusion imaging and gadolinium enhancement obtained 2 min. (early MVO) and 15 min. (delayed MVO) post contrast. Material/Methods 106 patients with first anterior myocardial infarction were studied. Cardiovascular magnetic resonance (CMR) was performed 5±2 days after primary percutaneous coronary intervention (pPCI). Stress and rest perfusion imaging was performed as well as early and delayed gadolinium enhancement and systolic function assessment. Scoring of segmental function, perfusion defect, MVO and scar transmurality was performed in 16 segment left ventricular model. Results The prevalence of MVO varies significantly between imaging techniques ranging from 48.8% for delayed MVO to 94% with stress perfusion. Median sum of scores was significantly different for each technique: stress perfusion 13 (7; 18), rest perfusion 3 (0.5; 6), early MVO 3 (0; 8), delayed MVO 0 (0; 4); p<0.05. Infarct size, stress and rest perfusion defects were independent predictors of LV EF at discharge from hospital. Conclusions Imaging protocol has a significant impact on MVO results. The study is the first to describe a stress-induced MVO in STEMI patients. Further research is needed to evaluate its impact on a long term prognosis. PMID:26740825

  5. Crystal structure of the CRISPR-Cas RNA silencing Cmr complex bound to a target analog.

    PubMed

    Osawa, Takuo; Inanaga, Hideko; Sato, Chikara; Numata, Tomoyuki

    2015-05-01

    In prokaryotes, Clustered regularly interspaced short palindromic repeat (CRISPR)-derived RNAs (crRNAs), together with CRISPR-associated (Cas) proteins, capture and degrade invading genetic materials. In the type III-B CRISPR-Cas system, six Cas proteins (Cmr1-Cmr6) and a crRNA form an RNA silencing Cmr complex. Here we report the 2.1 Å crystal structure of the Cmr1-deficient, functional Cmr complex bound to single-stranded DNA, a substrate analog complementary to the crRNA guide. Cmr3 recognizes the crRNA 5' tag and defines the start position of the guide-target duplex, using its idiosyncratic loops. The β-hairpins of three Cmr4 subunits intercalate within the duplex, causing nucleotide displacements with 6 nt intervals, and thus periodically placing the scissile bonds near the crucial aspartate of Cmr4. The structure reveals the mechanism for specifying the periodic target cleavage sites from the crRNA 5' tag and provides insights into the assembly of the type III interference machineries and the evolution of the Cmr and Cascade complexes.

  6. CMR Shuffler System: Passive Mode Calibration and Certification Report

    SciTech Connect

    Frame, Katherine C.; Gomez, Cipriano D.; Salazar, William R.; Mayo, Douglas R.; Vigil, Georgiana M.; Crooks, William J.; Stange, Sy

    2012-07-20

    Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1 to 2 inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the vessels. As debris is removed from the vessels, material will be placed in waste drums. Far-field gamma ray assay will be used to determine when a drum is nearing a {sup 239}Pu equivalent mass of less than 200 g. The drum will then be assayed using a waste drum shuffler operated in passive mode using a neutron coincidence counting method for accountability. This report focuses on the testing and calibration of the CMR waste drum shuffler in passive mode operation. Initial testing was performed to confirm previously accepted measurement parameters. The system was then calibrated using a set of weapons grade Pu (WGPu, {sup 239}Pu > 93%) oxide standards placed inside a 55 gallon drum. The calibration data ranges from Pu mass of 0.5 g to 188.9 g. The CMR waste drum shuffler has been tested and calibrated in passive mode in preparation for safeguards accountability measurements of waste drums containing material removed from CVs for the CVD project.

  7. Crystallization and preliminary X-ray diffraction analysis of the CRISPR-Cas RNA-silencing Cmr complex.

    PubMed

    Osawa, Takuo; Inanaga, Hideko; Numata, Tomoyuki

    2015-06-01

    Clustered regularly interspaced short palindromic repeat (CRISPR)-derived RNA (crRNA) and CRISPR-associated (Cas) proteins constitute a prokaryotic adaptive immune system (CRISPR-Cas system) that targets and degrades invading genetic elements. The type III-B CRISPR-Cas Cmr complex, composed of the six Cas proteins (Cmr1-Cmr6) and a crRNA, captures and cleaves RNA complementary to the crRNA guide sequence. Here, a Cmr1-deficient functional Cmr (CmrΔ1) complex composed of Pyrococcus furiosus Cmr2-Cmr3, Archaeoglobus fulgidus Cmr4-Cmr5-Cmr6 and the 39-mer P. furiosus 7.01-crRNA was prepared. The CmrΔ1 complex was cocrystallized with single-stranded DNA (ssDNA) complementary to the crRNA guide by the vapour-diffusion method. The crystals diffracted to 2.1 Å resolution using synchrotron radiation at the Photon Factory. The crystals belonged to the triclinic space group P1, with unit-cell parameters a = 75.5, b = 76.2, c = 139.2 Å, α = 90.3, β = 104.8, γ = 118.6°. The asymmetric unit of the crystals is expected to contain one CmrΔ1-ssDNA complex, with a Matthews coefficient of 2.03 Å(3) Da(-1) and a solvent content of 39.5%.

  8. Real-time cine and myocardial perfusion with treadmill exercise stress cardiovascular magnetic resonance in patients referred for stress SPECT

    PubMed Central

    2010-01-01

    Background To date, stress cardiovascular magnetic resonance (CMR) has relied on pharmacologic agents, and therefore lacked the physiologic information available only with exercise stress. Methods 43 patients age 25 to 81 years underwent a treadmill stress test incorporating both Tc99m SPECT and CMR. After rest Tc99m SPECT imaging, patients underwent resting cine CMR. Patients then underwent in-room exercise stress using a partially modified treadmill. 12-lead ECG monitoring was performed throughout. At peak stress, Tc99m was injected and patients rapidly returned to their prior position in the magnet for post-exercise cine and perfusion imaging. The patient table was pulled out of the magnet for recovery monitoring. The patient was sent back into the magnet for recovery cine and resting perfusion followed by delayed post-gadolinium imaging. Post-CMR, patients went to the adjacent SPECT lab to complete stress nuclear imaging. Each modality's images were reviewed blinded to the other's results. Results Patients completed on average 9.3 ± 2.4 min of the Bruce protocol. Stress cine CMR was completed in 68 ± 14 sec following termination of exercise, and stress perfusion CMR was completed in 88 ± 8 sec. Agreement between SPECT and CMR was moderate (κ = 0.58). Accuracy in eight patients who underwent coronary angiography was 7/8 for CMR and 5/8 for SPECT (p = 0.625). Follow-up at 6 months indicated freedom from cardiovascular events in 29/29 CMR-negative and 33/34 SPECT-negative patients. Conclusions Exercise stress CMR including wall motion and perfusion is feasible in patients with suspected ischemic heart disease. Larger clinical trials are warranted based on the promising results of this pilot study to allow comparative effectiveness studies of this stress imaging system vs. other stress imaging modalities. PMID:20624294

  9. Adenosine and Sleep

    PubMed Central

    Bjorness, Theresa E; Greene, Robert W

    2009-01-01

    Over the last several decades the idea that adenosine (Ado) plays a role in sleep control was postulated due in large part to pharmacological studies that showed the ability of Ado agonists to induce sleep and Ado antagonists to decrease sleep. A second wave of research involving in vitro cellular analytic approaches and subsequently, the use of neurochemical tools such as microdialysis, identified a population of cells within the brainstem and basal forebrain arousal centers, with activity that is both tightly coupled to thalamocortical activation and under tonic inhibitory control by Ado. Most recently, genetic tools have been used to show that Ado receptors regulate a key aspect of sleep, the slow wave activity expressed during slow wave sleep. This review will briefly introduce some of the phenomenology of sleep and then summarize the effect of Ado levels on sleep, the effect of sleep on Ado levels, and recent experiments using mutant mouse models to characterize the role for Ado in sleep control and end with a discussion of which Ado receptors are involved in such control. When taken together, these various experiments suggest that while Ado does play a role in sleep control, it is a specific role with specific functional implications and it is one of many neurotransmitters and neuromodulators affecting the complex behavior of sleep. Finally, since the majority of adenosine-related experiments in the sleep field have focused on SWS, this review will focus largely on SWS; however, the role of adenosine in REM sleep behavior will be addressed. PMID:20190965

  10. Structure of the Cmr2 Subunit of the CRISPR-Cas RNA Silencing Complex

    SciTech Connect

    Cocozaki, Alexis I.; Ramia, Nancy F.; Shao, Yaming; Hale, Caryn R.; Terns, Rebecca M.; Terns, Michael P.; Li, Hong

    2012-08-10

    Cmr2 is the largest and an essential subunit of a CRISPR RNA-Cas protein complex (the Cmr complex) that cleaves foreign RNA to protect prokaryotes from invading genetic elements. Cmr2 is thought to be the catalytic subunit of the effector complex because of its N-terminal HD nuclease domain. Here, however, we report that the HD domain of Cmr2 is not required for cleavage by the complex in vitro. The 2.3 {angstrom} crystal structure of Pyrococcus furiosus Cmr2 (lacking the HD domain) reveals two adenylyl cyclase-like and two {alpha}-helical domains. The adenylyl cyclase-like domains are arranged as in homodimeric adenylyl cyclases and bind ADP and divalent metals. However, mutagenesis studies show that the metal- and ADP-coordinating residues of Cmr2 are also not critical for cleavage by the complex. Our findings suggest that another component provides the catalytic function and that the essential role by Cmr2 does not require the identified ADP- or metal-binding or HD domains in vitro.

  11. Rat cardiac myocyte adenosine transport and metabolism

    SciTech Connect

    Ford, D.A.; Rovetto, M.J.

    1987-01-01

    Based on the importance of myocardial adenosine and adenine nucleotide metabolism, the adenosine salvage pathway in ventricular myocytes was studied. Accurate estimates of transport rates, separate from metabolic fllux, were determined. Adenosine influx was constant between 3 and 60 s. Adenosine metabolism maintained intracellular adenosine concentrations < 10% of the extracellular adenosine concentrations and thus unidirectional influx could be measured. Myocytes transported adenosine via saturable and nonsaturable processes. A minimum estimate of the V/sub max/ of myocytic adenosine kinase indicated the saturable component of adenosine influx was independent of adenosine kinase activity. Saturable transport was inhibited by nitrobenzylthioinosine and verapamil. Extracellular adenosine taken up myocytes was rapidly phosphorylated to adenine taken up by myocytes was rapidly phosphorylated to adenine nucleotides. Not all extracellular adenosine, though, was phosphorylated on entering myocytes, since free, as opposed to protein-bound, intracellular adenosine was detected after digitonin extraction of cells in the presence of 1 mM ethylene-diaminetetraacetic acid.

  12. Adenosine Receptors: Expression, Function and Regulation

    PubMed Central

    Sheth, Sandeep; Brito, Rafael; Mukherjea, Debashree; Rybak, Leonard P.; Ramkumar, Vickram

    2014-01-01

    Adenosine receptors (ARs) comprise a group of G protein-coupled receptors (GPCR) which mediate the physiological actions of adenosine. To date, four AR subtypes have been cloned and identified in different tissues. These receptors have distinct localization, signal transduction pathways and different means of regulation upon exposure to agonists. This review will describe the biochemical characteristics and signaling cascade associated with each receptor and provide insight into how these receptors are regulated in response to agonists. A key property of some of these receptors is their ability to serve as sensors of cellular oxidative stress, which is transmitted by transcription factors, such as nuclear factor (NF)-κB, to regulate the expression of ARs. Recent observations of oligomerization of these receptors into homo- and heterodimers will be discussed. In addition, the importance of these receptors in the regulation of normal and pathological processes such as sleep, the development of cancers and in protection against hearing loss will be examined. PMID:24477263

  13. Uric acid induces oxidative stress and growth inhibition by activating adenosine monophosphate-activated protein kinase and extracellular signal-regulated kinase signal pathways in pancreatic β cells.

    PubMed

    Zhang, Yongneng; Yamamoto, Tetsuya; Hisatome, Ichiro; Li, Youfeng; Cheng, Weijie; Sun, Ning; Cai, Bozhi; Huang, Tianliang; Zhu, Yuzhang; Li, Zhi; Jing, Xubin; Zhou, Rui; Cheng, Jidong

    2013-08-15

    Hyperuricaemia is a disorder of purine metabolism, and is strongly associated with insulin resistance and abnormal glucose metabolism. As the producer of insulin, pancreatic β cells might be affected by elevated serum uric acid levels and contribute to the disregulated glucose metabolism. In this study, we investigated the effect of high uric acid on rat pancreatic β cell function. Under high uric acid condition, proliferation of pancreatic β cells was inhibited, production of reactive oxygen species increased, and glucose stimulated insulin secretion was also compromised. Further examination on signal transduction pathways revealed that uric acid-induced ROS is involved in the activation of adenosine monophosphate-activated protein kinase (AMPK), and extracellular signal-regulated kinase (ERK). Pharmacological inhibition of ERK activation rescued β cells from growth inhibition. More importantly, activation of ERK induced by uric acid is significantly diminished by AMPK inhibitor, indicating ERK as a downstream target of AMPK in response to high uric acid condition. We also investigated the transportation channel for uric acid into pancreatic β cells. While major urate transporter URAT1 is not expressed in β cells, organic anion transporter (OAT) inhibitor successfully blocked the activation of ERK by uric acid. Our data indicate that high uric acid levels induce oxidative damage and inhibit growth of rat pancreatic β cells by activating the AMPK and ERK signal pathways. Hyperuricemia may contribute to abnormal glucose metabolism by causing oxidative damage and function inhibition of pancreatic β cells.

  14. Genetics Home Reference: adenosine deaminase 2 deficiency

    MedlinePlus

    ... Health Conditions adenosine deaminase 2 deficiency adenosine deaminase 2 deficiency Enable Javascript to view the expand/collapse ... PDF Open All Close All Description Adenosine deaminase 2 (ADA2) deficiency is a disorder characterized by abnormal ...

  15. Assessment of myocardial perfusion by harmonic power doppler imaging at rest and during adenosine triphosphate stress: comparison with coronary flow velocity reserve in the left anterior descending coronary arter.

    PubMed

    Takeuchi, Masaaki; Yoshitani, Hidetoshi; Miyazaki, Chinami; Otani, Shinichiro; Sakamoto, Kazuo; Yoshikawa, Junichi

    2002-02-01

    To clarify whether the myocardial perfusion abnormalities observed on harmonic power Doppler imaging (HPDI) during hyperemia are related to a decrease in coronary flow velocity reserve (CFVR), HPDI and CFVR were measured in the left anterior descending coronary artery (LAD) territory of 75 patients. During continuous infusion of Levovist, dual-frame triggered apical 4-chamber views were obtained at rest and during adenosine triphosphate (ATP) infusion. The persistence of perfusion defects during ATP infusion or stress-induced defects in the LAD territory was defined as abnormal. Both HPDI and coronary flow velocity recordings of adequate quality were successfully obtained in 73 patients, and 37 patients showed abnormal myocardial perfusion. CFVR was significantly lower in patients with abnormal perfusion than in patients who had normal findings (1.38+/-0.38 vs 2.60+/-0.76, p<0.001). A CFVR less than 1.9 had a sensitivity of 89% (33/37) and a specificity of 89% (32/36) for predicting the presence of abnormal myocardial perfusion. This study demonstrates that myocardial perfusion abnormalities observed during HPDI using ATP stress are closely correlated to a decrease in CFVR and may reflect significant stenosis or microvascular damage in the LAD territory. PMID:11999642

  16. Left ventricular strain and its pattern estimated from cine CMR and validation with DENSE.

    PubMed

    Gao, Hao; Allan, Andrew; McComb, Christie; Luo, Xiaoyu; Berry, Colin

    2014-07-01

    Measurement of local strain provides insight into the biomechanical significance of viable myocardium. We attempted to estimate myocardial strain from cine cardiovascular magnetic resonance (CMR) images by using a b-spline deformable image registration method. Three healthy volunteers and 41 patients with either recent or chronic myocardial infarction (MI) were studied at 1.5 Tesla with both cine and DENSE CMR. Regional circumferential and radial left ventricular strains were estimated from cine and DENSE acquisitions. In all healthy volunteers, there was no difference for peak circumferential strain (- 0.18 ± 0.04 versus - 0.18 ± 0.03, p = 0.76) between cine and DENSE CMR, however peak radial strain was overestimated from cine (0.84 ± 0.37 versus 0.49 ± 0.2, p < 0.01). In the patient study, the peak strain patterns predicted by cine were similar to the patterns from DENSE, including the strain evolution related to recovery time and strain patterns related to MI scar extent. Furthermore, cine-derived strain disclosed different strain patterns in MI and non-MI regions, and regions with transmural and non-transmural MI as DENSE. Although there were large variations with radial strain measurements from cine CMR images, useful circumferential strain information can be obtained from routine clinical CMR imaging. Cine strain analysis has potential to improve the diagnostic yield from routine CMR imaging in clinical practice.

  17. Left ventricular strain and its pattern estimated from cine CMR and validation with DENSE

    NASA Astrophysics Data System (ADS)

    Gao, Hao; Allan, Andrew; McComb, Christie; Luo, Xiaoyu; Berry, Colin

    2014-07-01

    Measurement of local strain provides insight into the biomechanical significance of viable myocardium. We attempted to estimate myocardial strain from cine cardiovascular magnetic resonance (CMR) images by using a b-spline deformable image registration method. Three healthy volunteers and 41 patients with either recent or chronic myocardial infarction (MI) were studied at 1.5 Tesla with both cine and DENSE CMR. Regional circumferential and radial left ventricular strains were estimated from cine and DENSE acquisitions. In all healthy volunteers, there was no difference for peak circumferential strain (- 0.18 ± 0.04 versus - 0.18 ± 0.03, p = 0.76) between cine and DENSE CMR, however peak radial strain was overestimated from cine (0.84 ± 0.37 versus 0.49 ± 0.2, p < 0.01). In the patient study, the peak strain patterns predicted by cine were similar to the patterns from DENSE, including the strain evolution related to recovery time and strain patterns related to MI scar extent. Furthermore, cine-derived strain disclosed different strain patterns in MI and non-MI regions, and regions with transmural and non-transmural MI as DENSE. Although there were large variations with radial strain measurements from cine CMR images, useful circumferential strain information can be obtained from routine clinical CMR imaging. Cine strain analysis has potential to improve the diagnostic yield from routine CMR imaging in clinical practice.

  18. Imaging Adenosine Triphosphate (ATP).

    PubMed

    Rajendran, Megha; Dane, Eric; Conley, Jason; Tantama, Mathew

    2016-08-01

    Adenosine triphosphate (ATP) is a universal mediator of metabolism and signaling across unicellular and multicellular species. There is a fundamental interdependence between the dynamics of ATP and the physiology that occurs inside and outside the cell. Characterizing and understanding ATP dynamics provide valuable mechanistic insight into processes that range from neurotransmission to the chemotaxis of immune cells. Therefore, we require the methodology to interrogate both temporal and spatial components of ATP dynamics from the subcellular to the organismal levels in live specimens. Over the last several decades, a number of molecular probes that are specific to ATP have been developed. These probes have been combined with imaging approaches, particularly optical microscopy, to enable qualitative and quantitative detection of this critical molecule. In this review, we survey current examples of technologies available for visualizing ATP in living cells, and identify areas where new tools and approaches are needed to expand our capabilities. PMID:27638696

  19. Imaging Adenosine Triphosphate (ATP).

    PubMed

    Rajendran, Megha; Dane, Eric; Conley, Jason; Tantama, Mathew

    2016-08-01

    Adenosine triphosphate (ATP) is a universal mediator of metabolism and signaling across unicellular and multicellular species. There is a fundamental interdependence between the dynamics of ATP and the physiology that occurs inside and outside the cell. Characterizing and understanding ATP dynamics provide valuable mechanistic insight into processes that range from neurotransmission to the chemotaxis of immune cells. Therefore, we require the methodology to interrogate both temporal and spatial components of ATP dynamics from the subcellular to the organismal levels in live specimens. Over the last several decades, a number of molecular probes that are specific to ATP have been developed. These probes have been combined with imaging approaches, particularly optical microscopy, to enable qualitative and quantitative detection of this critical molecule. In this review, we survey current examples of technologies available for visualizing ATP in living cells, and identify areas where new tools and approaches are needed to expand our capabilities.

  20. Alternaria alternata transcription factor CmrA controls melanization and spore development.

    PubMed

    Fetzner, Ramona; Seither, Kristin; Wenderoth, Maximilian; Herr, Andreas; Fischer, Reinhard

    2014-09-01

    Melanin is a black pigment widely distributed across the kingdoms, from bacterial to human. The filamentous fungus Alternaria alternata is a typical 'black fungus', which produces melanin in its hyphal and especially its asexual spore cell walls. Its biosynthesis follows the dihydroxynaphthalene (DHN) pathway with 1,8-DHN as an intermediate. Two genes, encoding a polyketide synthase (pksA) and a 1,3,8-trihydroxynaphthalene (THN) reductase (brm2), along with a putative transcription factor, CmrA, comprise a small gene cluster. Here we show that CmrA controls the expression of pksA and brm2, but that it also controls the expression of a scytalone dehydratase encoding gene (brm1) located elsewhere in the genome. The regulatory function of CmrA was shown in a reporter assay system. Al. alternata CmrA was expressed in the filamentous fungus Aspergillus nidulans where it was able to induce the expression of a reporter construct under the control of the putative pksA promoter. This suggests direct binding of CmrA to the promoter of pksA in the heterologous system. Likewise, silencing of cmrA in Al. alternata led to white colonies due to the lack of melanin. In addition, hyphal diameter and spore morphology were changed in the mutant and the number of spores reduced. Silencing of brm2 and inhibition of melanin biosynthesis by tricyclazole largely phenocopied the effects of cmrA silencing, suggesting a novel regulatory function of melanin in morphogenetic pathways.

  1. Intermedin1-53 attenuates vascular smooth muscle cell calcification by inhibiting endoplasmic reticulum stress via cyclic adenosine monophosphate/protein kinase A pathway.

    PubMed

    Chang, Jin-Rui; Duan, Xiao-Hui; Zhang, Bao-Hong; Teng, Xu; Zhou, Ye-Bo; Liu, Yue; Yu, Yan-Rong; Zhu, Yi; Tang, Chao-Shu; Qi, Yong-Fen

    2013-10-01

    We previously reported that endoplasmic reticulum (ER) stress-mediated apoptosis participated in vascular calcification. Importantly, a novel paracrine/autocrine peptide intermedin1-53 (IMD1-53) in the vasculature inhibited vascular calcification in rats. But the mechanisms needed to be fully elucidated. Vascular smooth muscle cells (VSMCs) calcification was induced by CaCl2 and β-glycerophosphate. Tunicamycin (Tm) or dithiothreitol (DTT) was used to induce ER stress. We found that IMD1-53 (10(-7)mol/L) treatment significantly alleviated the protein expression of ER stress hallmarks activating transcription factor 4 (ATF4), ATF6, glucose-regulated protein 78 (GRP78) and GRP94 induced by Tm or DTT. ER stress occurred in early and late calcification of VSMCs but was inhibited by IMD1-53. These inhibitory effects of IMD1-53 were abolished by treatment with the protein kinase A (PKA) inhibitor H89. Pretreatment with IMD1-53 decreased the number of apoptotic VSMCs and downregulated protein expression of cleaved caspase 12 and C/EBP homologous protein (CHOP) in calcified VSMCs. Concurrently, IMD1-53 restored the loss of VSMC lineage markers and ameliorated calcium deposition and alkaline phosphatase activity in calcified VSMCs as well. The observation was further verified by Alizarin Red S staining, which showed that IMD1-53 reduced positive red nodules among calcified VSMCs. In conclusion, IMD1-53 attenuated VSMC calcification by inhibiting ER stress through cAMP/PKA signalling.

  2. Purine metabolism in adenosine deaminase deficiency.

    PubMed Central

    Mills, G C; Schmalstieg, F C; Trimmer, K B; Goldman, A S; Goldblum, R M

    1976-01-01

    Purine and pyrimidine metabolites were measured in erythrocytes, plasma, and urine of a 5-month-old infant with adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) deficiency. Adenosine and adenine were measured using newly devised ion exchange separation techniques and a sensitive fluorescence assay. Plasma adenosine levels were increased, whereas adenosine was normal in erythrocytes and not detectable in urine. Increased amounts of adenine were found in erythrocytes and urine as well as in the plasma. Erythrocyte adenosine 5'-monophosphate and adenosine diphosphate concentrations were normal, but adenosine triphosphate content was greatly elevated. Because of the possibility of pyrimidine starvation, pyrimidine nucleotides (pyrimidine coenzymes) in erythrocytes and orotic acid in urine were measured. Pyrimidine nucleotide concentrations were normal, while orotic acid was not detected. These studies suggest that the immune deficiency associated with adenosine deaminase deficiency may be related to increased amounts of adenine, adenosine, or adenine nucleotides. PMID:1066699

  3. Adenosine-Associated Delivery Systems

    PubMed Central

    Kazemzadeh-Narbat, Mehdi; Annabi, Nasim; Tamayol, Ali; Oklu, Rahmi; Ghanem, Amyl; Khademhosseini, Ali

    2016-01-01

    Adenosine is a naturally occurring purine nucleoside in every cell. Many critical treatments such as modulating irregular heartbeat (arrhythmias), regulation of central nervous system (CNS) activity, and inhibiting seizural episodes can be carried out using adenosine. Despite the significant potential therapeutic impact of adenosine and its derivatives, the severe side effects caused by their systemic administration have significantly limited their clinical use. In addition, due to adenosine’s extremely short half-life in human blood (less than 10 s), there is an unmet need for sustained delivery systems to enhance efficacy and reduce side effects. In this paper, various adenosine delivery techniques, including encapsulation into biodegradable polymers, cell-based delivery, implantable biomaterials, and mechanical-based delivery systems, are critically reviewed and the existing challenges are highlighted. PMID:26453156

  4. [The accuracy and side effects of pharmacologic stress thallium myocardial scintigraphy with adenosine triphosphate disodium (ATP) infusion in the diagnosis of coronary artery disease].

    PubMed

    Kinoshita, S; Suzuki, S; Shindou, A; Watanabe, K; Muramatsu, T; Ide, M; Dohi, Y; Yamashita, S; Suzuki, T; Nishimura, K

    1994-08-01

    The diagnostic accuracy and side effects of pharmacologic stress thallium myocardial scintigraphy with ATP infusion were studied in 172 patients with or without coronary artery disease. ATP was infused for five minutes at a rate of 0.16 mg/kg/min (group A) or 0.18 mg/kg/min (group B) via antecubital vein. One hundred and eleven (67 of group A, 44 of group B) of 172 patients underwent coronary arteriography (CAG). In 111 patients received CAG, overall sensitivity, specificity and accuracy of this method were 88%, 84% and 87%, respectively. In 67 patients of group A, these were 92%, 81% and 90%. In 44 patients of group B, 79%, 87% and 82% were documented (NS, between group A and B). Chest pain, flushing, bradycardia and ST depression were included in side effects caused by ATP infusion. At least one of these side effects were observed in 84% of the all 172 patients, 89% of group A and 75% of group B (NS). But, all of the side effects were spontaneously alleviated within two minutes without any therapy. In conclusion, pharmacologic stress myocardial scintigraphy with ATP infusion is very accurate and safe, and infusion rate of 0.16 mg/kg/min is optimal for this purpose. PMID:7933682

  5. Clinical Utility and Future Applications of PET/CT and PET/CMR in Cardiology

    PubMed Central

    Pan, Jonathan A.; Salerno, Michael

    2016-01-01

    Over the past several years, there have been major advances in cardiovascular positron emission tomography (PET) in combination with either computed tomography (CT) or, more recently, cardiovascular magnetic resonance (CMR). These multi-modality approaches have significant potential to leverage the strengths of each modality to improve the characterization of a variety of cardiovascular diseases and to predict clinical outcomes. This review will discuss current developments and potential future uses of PET/CT and PET/CMR for cardiovascular applications, which promise to add significant incremental benefits to the data provided by each modality alone. PMID:27598207

  6. Clinical Utility and Future Applications of PET/CT and PET/CMR in Cardiology.

    PubMed

    Pan, Jonathan A; Salerno, Michael

    2016-01-01

    Over the past several years, there have been major advances in cardiovascular positron emission tomography (PET) in combination with either computed tomography (CT) or, more recently, cardiovascular magnetic resonance (CMR). These multi-modality approaches have significant potential to leverage the strengths of each modality to improve the characterization of a variety of cardiovascular diseases and to predict clinical outcomes. This review will discuss current developments and potential future uses of PET/CT and PET/CMR for cardiovascular applications, which promise to add significant incremental benefits to the data provided by each modality alone. PMID:27598207

  7. Routine Cine-CMR for Prosthesis Associated Mitral Regurgitation – A Multicenter Comparison to Echocardiography

    PubMed Central

    Simprini, Lauren A.; Afroz, Anika; Cooper, Mitchell A.; Klem, Igor; Jensen, Christoph; Kim, Raymond J.; Srichai, Monvadi B.; Heitner, John F.; Sood, Michael; Chandy, Elizabeth; Shah, Dipan J.; Lopez-Mattei, Juan; Biederman, Robert W.; Grizzard, John D.; Fuisz, Anthon; Ghafourian, Kambiz; Farzaneh-Far, Afshin; Weinsaft, Jonathan

    2016-01-01

    Background/Aim MR is an important complication after PMV. Transthoracic echocardiography is widely used to screen for native MR, but can be limited with PMV. Cine-CMR holds potential to non-invasively assess regurgitant severity based on MR-induced inter-voxel dephasing. This study evaluated routine cine-CMR for visual assessment of prosthetic mitral valve (PMV) associated mitral regurgitation (MR). Methods Routine cine-CMR was performed at 9 sites. A uniform protocol was used to grade MR based on jet size in relation to the left atrium (mild <1/3, moderate 1/3–2/3, severe >2/3): MR was graded in each long axis orientation, with overall severity based on cumulative grade. Cine-CMR was also scored for MR density and pulmonary vein systolic flow reversal (PSFR). Visual interpretation was compared to quantitative analysis in a single center (derivation) cohort, and to transesophageal echocardiography (TEE) in a multicenter (validation) cohort. Results The population comprised 85 PMV patients (59% mechanical, 41% bioprosthetic). Among the derivation cohort (n=25), quantitative indices paralleled visual scores, with stepwise increases in jet size and density in relation to visually graded MR severity (both p=0.001): Patients with severe MR had nearly a 3-fold increase in quantitative jet area (p=0.002), and 2-fold increase in density (p=0.04) than did others. Among the multicenter cohort, cine-CMR and TEE (Δ=2±3 days) demonstrated moderate agreement (κ=0.44); 64% of discordances differed by ≤ 1 grade (Δ=1.2±0.5). Using a TEE reference, cine-CMR yielded excellent diagnostic performance for severe MR (sensitivity, negative predictive value=100%). Patients with visually graded severe MR also had more frequent PVSFR (p<0.001), denser jets (p<0.001), and larger left atria (p=0.01) on cine-CMR. Conclusions Cine-CMR is useful for assessment of PMV-associated MR, which manifests concordant quantitative and qualitative changes in size and density of inter

  8. Performance of CMR Methods for Differentiating Acute From Chronic Myocardial Infarction

    PubMed Central

    Smulders, Martijn W.; Bekkers, Sebastiaan C.A.M.; Kim, Han W.; Van Assche, Lowie M.R.; Parker, Michele A.; Kim, Raymond J.

    2015-01-01

    Objectives To assess the performance of cardiovascular magnetic resonance (CMR) methods for discriminating acute from chronic myocardial infarction (MI). Background Although T2-weighted-CMR is thought to be accurate in differentiating acute from chronic MI, few studies have reported on diagnostic accuracy, and these generally compared extremes in infarct age (e.g. <1-week-old versus >6-months-old) and did not evaluate other CMR methods that could be informative. Methods 221 CMR studies were performed at various time-points after STEMI in 117 consecutive patients without prior history of MI or revascularization enrolled prospectively at 2 centers. Imaging markers of acute MI (<1-month) were T2-hyperintensity on double inversion-recovery turbo-spin-echo (DIR-TSE) images, microvascular obstruction (MO) on delayed-enhancement-CMR, and focally increased end-diastolic wall thickness (EDWT) on cine-CMR. Results The prevalence of T2-DIR-TSE hyperintensity decreased with infarct age but remained substantial up to 6-months post-MI. In contrast, the prevalence of both MO and increased-EDWT dropped sharply after 1-month. T2-DIR-TSE sensitivity, specificity, and accuracy for identifying acute MI were 88%, 66%, and 77% compared with 73%, 97%, and 85% for the combination of MO-or-increased-EDWT. On multivariable analysis, persistence of T2-hyperintensity in intermediate-aged infarcts (1–6 months-old) was predicted by larger infarct size, diabetes, and better T2-DIR-TSE image quality score. For infarct size ≥10% LV, a simple algorithm incorporating all CMR components allowed classification of infarct age into 3 categories (<1-month-old, 1–6 months-old, and ≥6-months-old) with 80% [95% CI: 73–87%] accuracy. Conclusions T2-DIR-TSE hyperintensity is specific for infarcts less than 6-months-old, whereas microvascular obstruction and increased end-diastolic wall-thickness are specific for infarcts less than 1-month-old. Incorporating multiple CMR markers of acute MI and their

  9. Sulphur flux through the sulphate assimilation pathway is differently controlled by adenosine 5'-phosphosulphate reductase under stress and in transgenic poplar plants overexpressing gamma-ECS, SO, or APR.

    PubMed

    Scheerer, Ursula; Haensch, Robert; Mendel, Ralf R; Kopriva, Stanislav; Rennenberg, Heinz; Herschbach, Cornelia

    2010-01-01

    Sulphate assimilation provides reduced sulphur for the synthesis of cysteine, methionine, and numerous other essential metabolites and secondary compounds. The key step in the pathway is the reduction of activated sulphate, adenosine 5'-phosphosulphate (APS), to sulphite catalysed by APS reductase (APR). In the present study, [(35)S]sulphur flux from external sulphate into glutathione (GSH) and proteins was analysed to check whether APR controls the flux through the sulphate assimilation pathway in poplar roots under some stress conditions and in transgenic poplars. (i) O-Acetylserine (OAS) induced APR activity and the sulphur flux into GSH. (ii) The herbicide Acetochlor induced APR activity and results in a decline of GSH. Thereby the sulphur flux into GSH or protein remained unaffected. (iii) Cd treatment increased APR activity without any changes in sulphur flux but lowered sulphate uptake. Several transgenic poplar plants that were manipulated in sulphur metabolism were also analysed. (i) Transgenic poplar plants that overexpressed the gamma-glutamylcysteine synthetase (gamma-ECS) gene, the enzyme catalysing the key step in GSH formation, showed an increase in sulphur flux into GSH and sulphate uptake when gamma-ECS was targeted to the cytosol, while no changes in sulphur flux were observed when gamma-ECS was targeted to plastids. (ii) No effect on sulphur flux was observed when the sulphite oxidase (SO) gene from Arabidopsis thaliana, which catalyses the back reaction of APR, that is the reaction from sulphite to sulphate, was overexpressed. (iii) When Lemna minor APR was overexpressed in poplar, APR activity increased as expected, but no changes in sulphur flux were observed. For all of these experiments the flux control coefficient for APR was calculated. APR as a controlling step in sulphate assimilation seems obvious under OAS treatment, in gamma-ECS and SO overexpressing poplars. A possible loss of control under certain conditions, that is Cd treatment

  10. Biological control of Rhizoctonia root rot on bean by phenazine- and cyclic lipopeptide-producing Pseudomonas CMR12a

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas CMR12a was previously selected as an efficient biocontrol strain producing phenazines and cyclic lipopeptides (CLPs). In this study, biocontrol capacity of Pseudomonas CMR12a against Rhizoctonia root rot of bean and the involvement of phenazines and CLPs in this ability were tested. Two ...

  11. Involvement of phenazines and biosurfactants in biocontrol of Pythium myriotylum root rot on cocoyam by Pseudomonas sp. CMR12A

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas sp. CMR12a was isolated from the rhizosphere of the tropical tuber crop cocoyam and produces both phenazines and cyclic lipopeptide (CLP) biosurfactants. CMR12a was shown to be an efficient biocontrol agent of P. myriotylum on cocoyam. To assess the importance of phenazine and biosurfact...

  12. Alkaline Phosphatase, Soluble Extracellular Adenine Nucleotides, and Adenosine Production after Infant Cardiopulmonary Bypass

    PubMed Central

    Davidson, Jesse A.; Urban, Tracy; Tong, Suhong; Twite, Mark; Woodruff, Alan

    2016-01-01

    Rationale Decreased alkaline phosphatase activity after infant cardiac surgery is associated with increased post-operative cardiovascular support requirements. In adults undergoing coronary artery bypass grafting, alkaline phosphatase infusion may reduce inflammation. Mechanisms underlying these effects have not been explored but may include decreased conversion of extracellular adenine nucleotides to adenosine. Objectives 1) Evaluate the association between alkaline phosphatase activity and serum conversion of adenosine monophosphate to adenosine after infant cardiac surgery; 2) assess if inhibition/supplementation of serum alkaline phosphatase modulates this conversion. Methods and Research Pre/post-bypass serum samples were obtained from 75 infants <4 months of age. Serum conversion of 13C5-adenosine monophosphate to 13C5-adenosine was assessed with/without selective inhibition of alkaline phosphatase and CD73. Low and high concentration 13C5-adenosine monophosphate (simulating normal/stress concentrations) were used. Effects of alkaline phosphatase supplementation on adenosine monophosphate clearance were also assessed. Changes in serum alkaline phosphatase activity were strongly correlated with changes in 13C5-adenosine production with or without CD73 inhibition (r = 0.83; p<0.0001). Serum with low alkaline phosphatase activity (≤80 U/L) generated significantly less 13C5-adenosine, particularly in the presence of high concentration 13C5-adenosine monophosphate (10.4μmol/L vs 12.9μmol/L; p = 0.0004). Inhibition of alkaline phosphatase led to a marked decrease in 13C5-adenosine production (11.9μmol/L vs 2.7μmol/L; p<0.0001). Supplementation with physiologic dose human tissue non-specific alkaline phosphatase or high dose bovine intestinal alkaline phosphatase doubled 13C5-adenosine monophosphate conversion to 13C5-adenosine (p<0.0001). Conclusions Alkaline phosphatase represents the primary serum ectonucleotidase after infant cardiac surgery and low post

  13. 5'-Adenosine monophosphate and adenosine metabolism, and adenosine responses in mouse, rat and guinea pig heart.

    PubMed

    Headrick, J P; Peart, J; Hack, B; Garnham, B; Matherne, G P

    2001-11-01

    We examined myocardial 5'-adenosine monophosphate (5'-AMP) catabolism, adenosine salvage and adenosine responses in perfused guinea pig, rat and mouse heart. MVO(2) increased from 71+/-8 microl O(2)/min per g in guinea pig to 138+/-17 and 221+/-15 microl O(2)/min per g in rat and mouse. VO(2)/beat was 0.42+/-0.03, 0.50+/-0.03 and 0.55+/-0.04 microl O(2)/g in guinea pig, rat and mouse, respectively. Resting and peak coronary flows were highest in mouse vs. rat and guinea pig, and peak ventricular pressures and Ca(2+) sensitivity declined as heart mass increased. Net myocardial 5'-AMP dephosphorylation increased significantly as mass declined (3.8+/-0.5, 9.0+/-1.4 and 11.0+/-1.6 nmol/min per g in guinea pig, rat and mouse, respectively). Despite increased 5'-AMP catabolism, coronary venous [adenosine] was similar in guinea pig, rat and mouse (45+/-8, 69+/-10 and 57+/-14 nM, respectively). Comparable venous [adenosine] was achieved by increased salvage vs. deamination: 64%, 41% and 39% of adenosine formed was rephosphorylated while 23%, 46%, and 50% was deaminated in mouse, rat and guinea pig, respectively. Moreover, only 35-45% of inosine and its catabolites derive from 5'-AMP (vs. IMP) dephosphorylation in all species. Although post-ischemic purine loss was low in mouse (due to these adaptations), functional tolerance to ischemia decreased with heart mass. Cardiovascular sensitivity to adenosine also differed between species, with A(1) receptor sensitivity being greatest in mouse while A(2) sensitivity was greatest in guinea pig. In summary: (i) cardiac 5'-AMP dephosphorylation, VO(2), contractility and Ca(2+) sensitivity all increase as heart mass falls; (ii) adaptations in adenosine salvage vs. deamination limit purine loss and yield similar adenosine levels across species; (iii) ischemic tolerance declines with heart mass; and (iv) cardiovascular sensitivity to adenosine varies, with increasing A(2) sensitivity relative to A(1) sensitivity in larger hearts.

  14. Introduction to Adenosine Receptors as Therapeutic Targets

    PubMed Central

    Jacobson, Kenneth A.

    2012-01-01

    Adenosine acts as a cytoprotective modulator in response to stress to an organ or tissue. Although short-lived in the circulation, it can activate four sub-types of G protein-coupled adenosine receptors (ARs): A1, A2A, A2B, and A3. The alkylxanthines caffeine and theophylline are the prototypical antagonists of ARs, and their stimulant actions occur primarily through this mechanism. For each of the four AR subtypes, selective agonists and antagonists have been introduced and used to develop new therapeutic drug concepts. ARs are notable among the GPCR family in the number and variety of agonist therapeutic candidates that have been proposed. The selective and potent synthetic AR agonists, which are typically much longer lasting in the body than adenosine, have potential therapeutic applications based on their anti-inflammatory (A2A and A3), cardioprotective (preconditioning by A1 and A3 and postconditioning by A2B), cerebroprotective (A1 and A3), and antinociceptive (A1) properties. Potent and selective AR antagonists display therapeutic potential as kidney protective (A1), antifibrotic (A2A), neuroprotective (A2A), and antiglaucoma (A3) agents. AR agonists for cardiac imaging and positron-emitting AR antagonists are in development for diagnostic applications. Allosteric modulators of A1 and A3 ARs have been described. In addition to the use of selective agonists/antagonists as pharmacological tools, mouse strains in which an AR has been genetically deleted have aided in developing novel drug concepts based on the modulation of ARs. PMID:19639277

  15. Comodulation Masking Release (CMR) in Children and the Influence of Reading Status

    ERIC Educational Resources Information Center

    Zettler, Cynthia M.; Sevcik, Rose A.; Morris, Robin D.; Clarkson, Marsha G.

    2008-01-01

    Purpose: Research suggests that children with reading disabilities (RD) have difficulty processing temporal and spectral components of sounds. Comodulation masking release (CMR) measures a listener's ability to use temporal and spectral information in noise to identify a signal. The purpose of this study was to determine whether children with RD…

  16. Genetics Home Reference: adenosine monophosphate deaminase deficiency

    MedlinePlus

    Skip to main content Your Guide to Understanding Genetic Conditions Enable Javascript for addthis links to activate. ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions adenosine monophosphate deaminase deficiency adenosine ...

  17. Predictors and Diagnostic Significance of the Adenosine Related Side Effects on Myocardial Perfusion SPECT/CT Imaging

    PubMed Central

    Yıldırım Poyraz, Nilüfer; Özdemir, Elif; Poyraz, Barış Mustafa; Kandemir, Zuhal; Keskin, Mutlay; Türkölmez, Şeyda

    2014-01-01

    Objective: The aim of this study was to investigate the relationship between patient characteristics and adenosine-related side-effects during stress myocard perfusion imaging (MPI). The effect of presence of adenosine-related side-effects on the diagnostic value of MPI with integrated SPECT/CT system for coronary artery disease (CAD), was also assessed in this study. Methods: Total of 281 patients (109 M, 172 F; mean age:62.6±10) who underwent standard adenosine stress protocol for MPI, were included in this study. All symptoms during adenosine infusion were scored according to the severity and duration. For the estimation of diagnostic value of adenosine MPI with integrated SPECT/CT system, coronary angiography (CAG) or clinical follow-up were used as gold standard. Results: Total of 173 patients (61.6%) experienced adenosine-related side-effects (group 1); flushing, dyspnea, and chest pain were the most common. Other 108 patients completed pharmacologic stress (PS) test without any side-effects (group 2). Test tolerability were similar in the patients with cardiovascular or airway disease to others, however dyspnea were observed significantly more common in patients with mild airway disease. Body mass index (BMI) ≥30 kg/m2 and age ≤45 years were independent predictors of side-effects. The diagnostic value of MPI was similar in both groups. Sensitivity of adenosine MPI SPECT/CT was calculated to be 86%, specificity was 94% and diagnostic accuracy was 92% for diagnosis of CAD. Conclusion: Adenosine MPI is a feasible and well tolerated method in patients who are not suitable for exercise stress test as well as patients with cardiopulmonary disease. However age ≤45 years and BMI ≥30 kg/m2 are the positive predictors of adenosine-related side-effects, the diagnostic value of adenosine MPI SPECT/CT is not affected by the presence of adenosine related side-effects. PMID:25541932

  18. Why do premature newborn infants display elevated blood adenosine levels?

    PubMed

    Panfoli, Isabella; Cassanello, Michela; Bruschettini, Matteo; Colella, Marina; Cerone, Roberto; Ravera, Silvia; Calzia, Daniela; Candiano, Giovanni; Ramenghi, Luca

    2016-05-01

    infants may be regarded as those in which premature exposure to ambient oxygen concentrations and oxidative stress causes a premature functioning of the extra-mitochondrial oxidative phosphorylation primarily in axons and endothelium. Adenosine may become a biomarker of prematurity risk, whose implications further studies may assess. PMID:27063086

  19. Features of adenosine metabolism of mouse heart.

    PubMed

    Deussen, Andreas; Weichsel, Johannes; Pexa, Annette

    2006-11-01

    Adenosine metabolism and transport were evaluated in the isolated perfused mouse heart and compared with the well-established model of isolated perfused guinea pig heart. Coronary venous release of adenosine under well-oxygenated conditions in the mouse exceeds that in the guinea pig threefold when related to tissue mass. Total myocardial adenosine production rate under this condition was approximately 2 nmol/min per gramme and similar in both species. Coronary resistance vessels of mice are highly sensitive to exogenous adenosine, and the threshold for adenosine-induced vasodilation is approximately 30 nmol/l. Adenosine membrane transport was largely insensitive to nitrobenzyl-thioinosine (NBTI) in mouse heart, which is in contrast to guinea pig and several other species. This indicates the dominance of NBTI-insensitive transporters in mouse heart. For future studies, the assessment of cytosolic and extracellular adenosine metabolism and its relationship with coronary flow will require the use of more effective membrane transport blockers.

  20. Volume-based considerations for the metal-insulator transition of CMR oxides

    SciTech Connect

    Neumeier, J.J. |; Hundley, M.F.; Cornelius, A.L.; Andres, K.

    1998-03-01

    The sensitivity of {rho} [electrical resistivity] to changes in volume which occur through: (1) applied pressure, (2) variations in temperature, and (3) phase transitions, is evaluated for some selected CMR oxides. It is argued that the changes in volume associated with phase changes are large enough to produce self pressures in the range of 0.18 to 0.45 GPa. The extreme sensitivity of the electrical resistivity to pressure indicates that these self pressures are responsible for large features in the electrical resistivity and are an important component for occurrence the metallicity below {Tc}. It is suggested that this is related to a strong volume dependence of the electron phonon coupling in the CMR oxides.

  1. Large magnetic-entropy change above 300 K in CMR materials

    NASA Astrophysics Data System (ADS)

    Phan, M. H.; Tian, S. B.; Hoang, D. Q.; Yu, S. C.; Nguyen, C.; Ulyanov, A. N.

    2003-03-01

    A large magnetic-entropy change Δ SM associated with the ferromagnetic-paramagnetic transition in CMR materials (La 0.65Sr 0.35MnO 3, La 0.6Sr 0.2Ca 0.2MnO 3, La 0.6Sr 0.2Ba 0.2MnO 3 and La 0.7Ca 0.06Ba 0.24MnO 3) has been observed. It is shown that the Δ SM reaches a maximum value of 2.26 J/kg/K for La 0.6Sr 0.2Ba 0.2MnO 3 composition at Curie temperature of 354 K, upon 10 kOe applied field variation. Due to the large Δ SM and high Curie temperature, these CMR materials are suggested to use as active magnetic refrigerants for magnetic refrigeration technology above room temperature.

  2. Bilayer splitting and c-axis coupling in CMR bilayer manganites

    SciTech Connect

    Jozwiak, Chris; Graf, Jeff; Zhou, Shuyun; Bostwick, Aaron; Rotenberg, Eli; Zheng, Hong; Mitchell, John; Lanzara, Alessandra

    2009-09-03

    By performing angle-resolved photoemission spectroscopy of the bilayer colossal magnetoresistive (CMR) manganite, La2-2xSr1+2xMn2O7, we provide the complete mapping of the Fermi-level spectral weight topology. Clear and unambiguous bilayer splitting of the in-plane 3dx2-y2 band, mapped throughout the Brillouin zone, and the full mapping of the 3d3z2-r2 band are reported. Peculiar doping and temperature dependencies of these bands imply that as transition from the ferromagnetic metallic phase approaches, either as a function of doping or temperature, coherence along the c-axis between planes within the bilayer is lost, resulting in reduced interplane coupling. These results suggest that interplane coupling plays a large role in the CMR transition.

  3. First Order CMR Transitions in the Two-Orbital Model for Manganites

    SciTech Connect

    Sen, Cengiz; Alvarez, Gonzalo; Dagotto, Elbio R

    2010-01-01

    Large-scale Monte Carlo simulation results for the two-orbital model for manganites, including Jahn-Teller lattice distortions, are presented here. At hole density x=1/4 and in the vicinity of the region of competition between the ferromagnetic metallic and spin-charge-orbital ordered insulating phases, the colossal magnetoresistance (CMR) phenomenon is observed with a magnetoresistance ratio {approx}10,000%. Our main result is that this CMR transition is found to be of first order in some portions of the phase diagram, in agreement with early results from neutron scattering, specific heat, and magnetization, thus solving a notorious discrepancy between experiments and previous theoretical studies. The first order characteristics of the transition survive, and are actually enhanced, when weak quenched disorder is introduced.

  4. Structures of the CRISPR-Cmr complex reveal mode of RNA target positioning

    PubMed Central

    Taylor, David W.; Zhu, Yifan; Staals, Raymond H.J.; Kornfeld, Jack E.; Shinkai, Akeo; van der Oost, John; Nogales, Eva; Doudna, Jennifer A.

    2015-01-01

    Adaptive immunity in bacteria involves RNA-guided surveillance complexes that use CRISPR (clustered regularly interspaced short palindromic repeats)-associated (Cas) proteins together with CRISPR RNAs (crRNAs) to target invasive nucleic acids for degradation. While Type I and Type II CRISPR-Cas surveillance complexes target double-stranded DNA, Type III complexes target single-stranded RNA. Near-atomic resolution cryo-electron microscopy (cryo-EM) reconstructions of native Type III Cmr (CRISPR RAMP module) complexes in the absence and presence of target RNA reveal a helical protein arrangement that positions the crRNA for substrate binding. Thumb-like β-hairpins intercalate between segments of duplexed crRNA:target RNA to facilitate cleavage of the target at 6-nt intervals. The Cmr complex is architecturally similar to the Type I CRISPR-Cascade complex, suggesting divergent evolution of these immune systems from a common ancestor. PMID:25837515

  5. The Rickettsia prowazekii invasion gene homolog (invA) encodes a Nudix hydrolase active on adenosine (5')-pentaphospho-(5')-adenosine.

    PubMed

    Gaywee, Jariyanart; Xu, WenLian; Radulovic, Suzana; Bessman, Maurice J; Azad, Abdu F

    2002-03-01

    The genomic sequence of Rickettsia prowazekii, the obligate intracellular bacterium responsible for epidemic typhus, reveals an uncharacterized invasion gene homolog (invA). The deduced protein of 18,752 Da contains a Nudix signature, the specific motif found in the Nudix hydrolase family. To characterize the function of InvA, the gene was cloned and overexpressed in Escherichia coli. The expressed protein was purified to near homogeneity and subsequently tested for its enzymatic activity against a series of nucleoside diphosphate derivatives. The purified InvA exhibits hydrolytic activity toward dinucleoside oligophosphates (Np(n)N; n > or = 5), a group of cellular signaling molecules. At optimal pH 8.5, the enzyme actively degrades adenosine (5')-pentaphospho-(5')-adenosine into ATP and ADP with a K(m) of 0.1 mM and k(cat) of 1.9 s(-1). Guanosine (5')-pentaphospho-(5')-guanosine and adenosine-(5')-hexaphospho (5')-adenosine are also substrates. Similar to other Nudix hydrolases, InvA requires a divalent metal cation, Mg(2+) or Zn(2+), for optimal activity. These data suggest that the rickettsial invasion protein likely plays a role in controlling the concentration of stress-induced dinucleoside oligophosphates following bacterial invasion.

  6. Fluorescent ligands for adenosine receptors.

    PubMed

    Kozma, Eszter; Jayasekara, P Suresh; Squarcialupi, Lucia; Paoletta, Silvia; Moro, Stefano; Federico, Stephanie; Spalluto, Giampiero; Jacobson, Kenneth A

    2013-01-01

    Interest is increasing in developing fluorescent ligands for characterization of adenosine receptors (ARs), which hold a promise of usefulness in the drug discovery process. The size of a strategically labeled AR ligand can be greatly increased after the attachment of a fluorophore. The choice of dye moiety (e.g. Alexa Fluor 488), attachment point and linker length can alter the selectivity and potency of the parent molecule. Fluorescent derivatives of adenosine agonists and antagonists (e.g. XAC and other heterocyclic antagonist scaffolds) have been synthesized and characterized pharmacologically. Some are useful AR probes for flow cytometry, fluorescence correlation spectroscopy, fluorescence microscopy, fluorescence polarization, fluorescence resonance energy transfer, and scanning confocal microscopy. Thus, the approach of fluorescent labeled GPCR ligands, including those for ARs, is a growing dynamic research field.

  7. Probability mapping of scarred myocardium using texture and intensity features in CMR images

    PubMed Central

    2013-01-01

    Background The myocardium exhibits heterogeneous nature due to scarring after Myocardial Infarction (MI). In Cardiac Magnetic Resonance (CMR) imaging, Late Gadolinium (LG) contrast agent enhances the intensity of scarred area in the myocardium. Methods In this paper, we propose a probability mapping technique using Texture and Intensity features to describe heterogeneous nature of the scarred myocardium in Cardiac Magnetic Resonance (CMR) images after Myocardial Infarction (MI). Scarred tissue and non-scarred tissue are represented with high and low probabilities, respectively. Intermediate values possibly indicate areas where the scarred and healthy tissues are interwoven. The probability map of scarred myocardium is calculated by using a probability function based on Bayes rule. Any set of features can be used in the probability function. Results In the present study, we demonstrate the use of two different types of features. One is based on the mean intensity of pixel and the other on underlying texture information of the scarred and non-scarred myocardium. Examples of probability maps computed using the mean intensity of pixel and the underlying texture information are presented. We hypothesize that the probability mapping of myocardium offers alternate visualization, possibly showing the details with physiological significance difficult to detect visually in the original CMR image. Conclusion The probability mapping obtained from the two features provides a way to define different cardiac segments which offer a way to identify areas in the myocardium of diagnostic importance (like core and border areas in scarred myocardium). PMID:24053280

  8. The Role of CMR and Others in Project Implementation using the CM Method to Support the Government

    NASA Astrophysics Data System (ADS)

    Tada, Hiroshi; Miyatake, Ichiro; Mouri, Junji; Endo, Kenji; Fueta, Toshiharu

    In Japan, the construction management (CM) method has been introduced as a measure to support the governmental agencies, in developing and maintaining local infrastructures, or in executing public works projects in an appropriate manner, etc. The scope of work of the Construction Manager (CMR) of the CM method is specified as work items, in the special specification document for CM services contained in the contract documents, as a reflection of the client's expectations towards the performance of CMR. However, the CM services has been conducted as required on a case-by-case basis, because it is not possible to anticipate the actual construction status in advance, and thus the special specification document does not provide full detail of the scope of work of CMR. In such case, there may be a difference in the way the scope of work in the special specification document is recognized between the client and the CMR, which could make the CM method less effective. Moreover, there is a case in which the role sharing between the client and the CMR is not clearly defined, and both parties may engage in the same task in such case, causing an obstacle for smooth project implementation. For this reason, it is required to prepare the special specification document which clearly defines the scope of work of CMR, by examining the status of application of the CM method in actual project cases, and to improve the practices of the CM method as necessary. In view of this background, this study looks in to the actual project cases using the CM method, for the purpose of clarifying the actual scope of work of CMR for each task item defined in the special specification document, and the role sharing between the client and CMR, in the aim of contributing the promotion of the use and the effective application of the CM method.

  9. Fluorometric Determination of Adenosine Nucleotide Derivatives as Measures of the Microfouling, Detrital, and Sedimentary Microbial Biomass and Physiological Status

    PubMed Central

    Davis, William M.; White, David C.

    1980-01-01

    Adenosine, adenine, cyclic adenosine monophosphate (AMP), AMP, nicotinamide adenine dinucleotide, adenosine diphosphate, and adenosine triphosphate (ATP) were recovered quantitatively from aqueous portions of lipid extracts of microfouling, detrital, and sedimentary microbial communities. These could be detected quantitatively in the picomolar range by forming their 1-N6-etheno derivatives and analyzing by high-pressure liquid chromatography with fluorescence detection. Lipid extraction and subsequent analysis allowed the simultaneous measurement of the microbial community structure, total microbial biomass with the quantitative recovery of the adenine-containing cellular components, which were protected from enzymatic destruction. This extraction and fluorescent derivatization method showed equivalency with the luciferin-luciferase method for bacterial ATP measurements. Quick-freezing samples in the field with dry ice-acetone preserved the ATP and energy charge (a ratio of adenosine nucleotides) for analysis at remote laboratories. The metabolic lability of ATP in estuarine detrital and microfouling communities, as well as bacterial monocultures of constant biomass, showed ATP to be a precarious measure of biomass under some conditions. Combinations of adenosine and adenine nucleotides gave better correlations with microbial biomass measured as extractable lipid phosphate in the detrital and microfouling microbial communities than did ATP alone. Stresses such as anoxia or filtration are reflected in the rapid accumulation of intracellular adenosine and the excretion of adenosine and AMP into the surrounding milieu. Increases in AMP and adenosine may prove to be more sensitive indicators of metabolic status than the energy charge. PMID:16345633

  10. Nonnucleoside inhibitors of adenosine kinase.

    PubMed

    Gomtsyan, Arthur; Lee, Chih-Hung

    2004-01-01

    Adenosine (ADO) is an endogenous inhibitory neuromodulator that increases nociceptive thresholds in response to tissue trauma and inflammation. Adenosine kinase (AK) is a key intracellular enzyme regulating intra- and extracellular concentrations of ADO. AK inhibition selectively amplifies extracellular ADO levels at cell and tissue sites where accelerated release of ADO occurs. AK inhibitors have been shown to provide effective antinociceptive, antiinflammatory and anticonvulsant activity in animal models, thus suggesting their potential therapeutic utility for pain, inflammation, epilepsy and possibly other central and peripheral nervous system diseases associated with cellular trauma and inflammation. This beneficial outcome may potentially lack nonspecific effects associated with the systemic administration of ADO receptor agonists. Until recently all of the reported AK inhibitors contained adenosine-like structural motif. The present review will discuss design, synthesis and analgesic and antiinflammatory properties of the novel nonnucleoside AK inhibitors that do not have close structural resemblance with the natural substrate ADO. Two classes of the nonnucleoside AK inhibitors are built on pyridopyrimidine and alkynylpyrimidine cores.

  11. Vasodilator effects of adenosine on retinal arterioles in streptozotocin-induced diabetic rats.

    PubMed

    Nakazawa, Taisuke; Mori, Asami; Saito, Maki; Sakamoto, Kenji; Nakahara, Tsutomu; Ishii, Kunio

    2008-02-01

    Adenosine is a potent vasodilator of retinal blood vessels and is implicated to be a major regulator of retinal blood flow during metabolic stress, but little is known about the impact of diabetes on the role of adenosine in regulation of retinal hemodynamics. Therefore, we examined how diabetes affects adenosine-induced vasodilation of retinal arterioles. Male Wistar rats were treated with streptozotocin (80 mg/kg, intraperitoneally), and experiments were performed 6-8 weeks later. Rats were treated with tetrodotoxin (50 microg/kg, intravenously [i.v.]) to eliminate any nerve activity and prevent movement of the eye and infused with methoxamine continuously to maintain adequate systemic circulation. Fundus images were captured with a digital camera that was equipped with a special objective lens, and diameters of retinal arterioles were measured. Adenosine increased diameters of retinal arterioles and decreased systemic blood pressure. These responses were significantly attenuated by the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (30 mg/kg, i.v.) and the adenosine triphosphate-dependent K+ (K(ATP)) channel blocker glibenclamide (20 mg/kg, i.v.). The depressor responses to adenosine were reduced in diabetic rats, whereas diabetes did not alter vasodilation of retinal arterioles to adenosine. In contrast, both depressor response and vasodilation of retinal arteriole to acetylcholine were reduced in diabetic rats. The retinal vasodilator responses to adenosine and acetylcholine observed in diabetic rats were diminished by N(G)-nitro-L-arginine methyl ester. There were no differences in the responses to pinacidil, a K(ATP) channel opener, between the diabetic and nondiabetic rats. These results suggest that both the activation of nitric oxide synthase and opening of K(ATP) channels contribute to the vasodilator effects of adenosine in rats in vivo. However, diabetes has no significant impact on the vasodilation mediated by these mechanisms in

  12. Effects of adenosine on polymorphonuclear leucocyte function, cyclic 3': 5'-adenosine monophosphate, and intracellular calcium.

    PubMed Central

    Nielson, C. P.; Vestal, R. E.

    1989-01-01

    1. Inhibition of human polymorphonuclear leucocyte (PMN) function by adenosine was studied with respect to effects of adenosine on intracellular cyclic AMP and calcium during the PMN respiratory burst. 2. The adenosine analogue 5'-N-ethylcarboxamide-adenosine (NECA) and L-N6-phenyl-isopropyl-adenosine (L-PIA) inhibited PMN oxygen metabolite generation with relative potencies (NECA greater than adenosine greater than L-PIA) characteristic of an A2 receptor. 3. The respiratory burst was inhibited by adenosine when PMN were activated by calcium ionophore or chemotactic peptide but not when cells where activated by oleoyl-acetyl-glycerol (OAG). 4. Adenosine increased intracellular cyclic AMP during the PMN respiratory burst regardless of whether cells were stimulated by ionophore, chemotactic peptide or OAG. 5. To determine whether the differences in cell inhibition by adenosine were related to differences in intracellular calcium mobilization by each activating agent, calcium was evaluated with the fluorescent probe, indo-1. Adenosine suppressed the increase in intracellular calcium following PMN activation by calcium ionophore or chemotactic peptide. In contrast, calcium did not increase in PMN activated by OAG and adenosine did not affect intracellular calcium changes following this stimulus. 6. These results demonstrate that physiological concentrations of adenosine inhibit the PMN respiratory burst in association with an increase in intracellular cyclic AMP and reduction of intracellular calcium. PMID:2547490

  13. Partial separation of platelet and placental adenosine receptors from adenosine A2-like binding protein

    SciTech Connect

    Zolnierowicz, S.; Work, C.; Hutchison, K.; Fox, I.H. )

    1990-04-01

    The ubiquitous adenosine A2-like binding protein obscures the binding properties of adenosine receptors assayed with 5'-N-({sup 3}H)ethylcarboxamidoadenosine (({sup 3}H)NECA). To solve this problem, we developed a rapid and simple method to separate adenosine receptors from the adenosine A2-like binding protein. Human platelet and placental membranes were solubilized with 1% 3-((3-cholamidopropyl)dimethylammonio)-1-propanesulfonate. The soluble platelet extract was precipitated with polyethylene glycol and the fraction enriched in adenosine receptors was isolated from the precipitate by differential centrifugation. The adenosine A2-like binding protein was removed from the soluble placental extract with hydroxylapatite and adenosine receptors were precipitated with polyethylene glycol. The specificity of the ({sup 3}H)NECA binding is typical of an adenosine A2 receptor for platelets and an adenosine A1 receptor for placenta. This method leads to enrichment of adenosine A2 receptors for platelets and adenosine A1 receptors for placenta. This provides a useful preparation technique for pharmacologic studies of adenosine receptors.

  14. Stratigraphy and Geologic Structure at the Chemical and Metallurgy (CMR) Building, Technical Area 3, Los Alamos National Laboratory

    SciTech Connect

    Alexis Lavine; Donathan Krier; Florie Caporuscio; Jamie Gardner

    1998-10-01

    Nine shallow (c70 ft), closely spaced core holes were continuously cored in the upper units of the 1.22 Ma Tshirege Member of the Bandelier Tuff at Technical Area (TA)-3 of the Los Alamos National Laboratory. The goal of the investigation was to identify faults that may have potential for earthquake-induced surface rupture at the site of the Chemistry and Metallurgy Research (CMR) building, a sensitive Laboratory facility that houses nuclear materials research functions. The holes were located from 25 ft to 115 ft from the building perimeter. Careful mapping of Lithologic sequences in cores, supplemented with focused sampling for geochemical analyses, yielded high confidence in the accuracy of delineating buried contacts within the Tshirege Member. Geologic analysis and investigation of the trends of surfaces interpolated from contacts in the core holes using commercially available software helped infer minor faulting in the strata beneath the building. Results show that gently north-northeast-dipping beds underlie the CMR building. The tilted beds are faulted by two small, closely spaced, parallel reverse faults with a combined vertical separation of approximately 8 ft. The faults are inferred from lithologically and geochemically repeated sections of core at about 55-ft depth in hole SHB-CMR-6. The data from nearby core holes SHB-CMR-2 and SHB-CMR-3 permit the extension of the faults, albeit with decreasing separation, toward the southwest beneath the CMR building. The fault trend is consistent with mapped lineaments from aerial photography and with nearby mapped structure, but direct evidence of the faults' orientations is lacking. No other faults were detected beneath the CMR building by this drilling and analysis method, which can detect faults with greater than about 2 ft separation.

  15. Pyridopyrimidine analogues as novel adenosine kinase inhibitors.

    PubMed

    Zheng, G Z; Lee, C; Pratt, J K; Perner, R J; Jiang, M Q; Gomtsyan, A; Matulenko, M A; Mao, Y; Koenig, J R; Kim, K H; Muchmore, S; Yu, H; Kohlhaas, K; Alexander, K M; McGaraughty, S; Chu, K L; Wismer, C T; Mikusa, J; Jarvis, M F; Marsh, K; Kowaluk, E A; Bhagwat, S S; Stewart, A O

    2001-08-20

    A novel series of pyridopyrimidine analogues 9 was identified as potent adenosine kinase inhibitors based on the SAR and computational studies. Substitution of the C7 position of the pyridopyrimidino core with C2' substituted pyridino moiety increased the in vivo potency and enhanced oral bioavailability of these adenosine kinase inhibitors.

  16. Enzymatic regeneration of adenosine triphosphate cofactor

    NASA Technical Reports Server (NTRS)

    Marshall, D. L.

    1974-01-01

    Regenerating adenosine triphosphate (ATP) from adenosine diphosphate (ADP) by enzymatic process which utilizes carbamyl phosphate as phosphoryl donor is technique used to regenerate expensive cofactors. Process allows complex enzymatic reactions to be considered as candidates for large-scale continuous processes.

  17. Fast left ventricle tracking in CMR images using localized anatomical affine optical flow

    NASA Astrophysics Data System (ADS)

    Queirós, Sandro; Vilaça, João. L.; Morais, Pedro; Fonseca, Jaime C.; D'hooge, Jan; Barbosa, Daniel

    2015-03-01

    In daily cardiology practice, assessment of left ventricular (LV) global function using non-invasive imaging remains central for the diagnosis and follow-up of patients with cardiovascular diseases. Despite the different methodologies currently accessible for LV segmentation in cardiac magnetic resonance (CMR) images, a fast and complete LV delineation is still limitedly available for routine use. In this study, a localized anatomically constrained affine optical flow method is proposed for fast and automatic LV tracking throughout the full cardiac cycle in short-axis CMR images. Starting from an automatically delineated LV in the end-diastolic frame, the endocardial and epicardial boundaries are propagated by estimating the motion between adjacent cardiac phases using optical flow. In order to reduce the computational burden, the motion is only estimated in an anatomical region of interest around the tracked boundaries and subsequently integrated into a local affine motion model. Such localized estimation enables to capture complex motion patterns, while still being spatially consistent. The method was validated on 45 CMR datasets taken from the 2009 MICCAI LV segmentation challenge. The proposed approach proved to be robust and efficient, with an average distance error of 2.1 mm and a correlation with reference ejection fraction of 0.98 (1.9 +/- 4.5%). Moreover, it showed to be fast, taking 5 seconds for the tracking of a full 4D dataset (30 ms per image). Overall, a novel fast, robust and accurate LV tracking methodology was proposed, enabling accurate assessment of relevant global function cardiac indices, such as volumes and ejection fraction

  18. Pediatric cardiovascular interventional devices: effect on CMR images at 1.5 and 3 Tesla

    PubMed Central

    2013-01-01

    Background To predict the type and extent of CMR artifacts caused by commonly used pediatric trans-catheter devices at 1.5 T and 3 T as an aid to clinical planning and patient screening. Methods Eleven commonly used interventional, catheter-based devices including stents, septal occluders, vascular plugs and embolization coils made from either stainless steel or nitinol were evaluated ex-vivo at both 1.5T and 3T. Pulse sequences and protocols commonly used for cardiovascular magnetic resonance (CMR) were evaluated, including 3D high-resolution MR angiography (MRA), time-resolved MRA, 2D balanced-SSFP cine and 2D phase-contrast gradient echo imaging (GRE). We defined the signal void amplification factor (F) as the ratio of signal void dimension to true device dimension. F1 and F2 were measured in the long axis and short axes respectively of the device. We defined F3 as the maximum extent of the off-resonance dark band artifact on SSFP measured in the B0direction. The effects of field strength, sequence type, orientation, flip angle and phase encode direction were tested. Clinical CMR images in 3 patients with various indwelling devices were reviewed for correlation with the in-vitro findings. Results F1 and F2 were higher (p<0.05) at 3T than at 1.5T for all sequences except 3D-MRA. Stainless steel devices produced greater off-resonance artifact on SSFP compared to nitinol devices (p<0.05). Artifacts were most severe with the stainless steel Flipper detachable embolization coil (Cook Medical, Bloomington, IN), with F1 and F2 10 times greater than with stainless steel stents. The orientation of stents changed the size of off-resonance artifacts by up to two fold. Sequence type did influence the size of signal void or off-resonance artifact (p<0.05). Varying the flip angle and phase encode direction did not affect image artifact. Conclusion Stainless steel embolization coils render large zones of anatomy uninterpretable, consistent with predictions based on ex

  19. Halobacterial adenosine triphosphatases and the adenosine triphosphatase from Halobacterium saccharovorum

    NASA Technical Reports Server (NTRS)

    Kristjansson, Hordur; Sadler, Martha H.; Hochstein, Lawrence I.

    1986-01-01

    Membranes prepared from various members of the genus Halobacterium contained a Triton X-l00 activated adenosine triphosphatase. The enzyme from Halobacterium saccharovorum was unstable in solutions of low ionic strength and maximally active in the presence of 3.5 M NaCl. A variety of nucleotide triphosphates was hydrolyzed. MgADP, the product of ATP hydrolysis, was not hydrolyzed and was a competitive inhibitor with respect to MgATP. The enzyme from H. saccharovorum was composed of at least 2 and possibly 4 subunits. The 83-kDa and 60-kDa subunits represented about 90 percent of total protein. The 60-kDa subunit reacted with dicyclohexyl-carbodiimide when inhibition was carried out in an acidic medium. The enzyme from H. saccharovorum, possesses properties of an F(1)F(0) as well as an E(1)E(2) ATPase.

  20. Intravenous adenosine (adenoscan) versus exercise in the noninvasive assessment of coronary artery disease by SPECT

    SciTech Connect

    LaManna, M.M.; Mohama, R.; Slavich, I.L. 3d.; Lumia, F.J.; Cha, S.D.; Rambaran, N.; Maranhao, V. )

    1990-11-01

    Fifteen patients at a mean age of 58 underwent adenosine and maximal exercise thallium SPECT imaging. All scans were performed 1 week apart and within 4 weeks of cardiac catheterization. SPECT imaging was performed after the infusion of 140 micrograms/kg/min of adenosine for 6 minutes. Mean heart rate increment during adenosine administration was 67 +/- 3.7 to 77 +/- 4.1. Mean blood pressure was 136 +/- 7.2 to 135 +/- 6.2 systolic and 78 +/- 1.8 to 68 +/- 2.6 diastolic. No adverse hemodynamic effects were observed. There were no changes in PR or QRS in intervals. Five stress ECGs were ischemic. No ST changes were observed with adenosine. Although 68% of the patients had symptoms of flushing, light-headedness, and dizziness during adenosine infusion, symptoms resolved within 1 minute of dosage adjustment or termination of the infusion in all but one patient, who required theophylline. Sensitivity for coronary artery detection was 77% and specificity 100%. Concordance between adenoscans and exercise thallium scintigraphy was high (13/15 = 87%). In two patients, there were minor scintigraphic differences. The authors conclude that adenosine is a sensitive, specific, and safe alternative to exercise testing in patients referred for thallium imaging and may be preferable to dipyridamole.

  1. Regional Heterogeneity in 3D Myocardial Shortening in Hypertensive Left Ventricular Hypertrophy: A Cardiovascular CMR Tagging Substudy to the Life Study

    PubMed Central

    Biederman, Robert W. W.; Young, Alistair A.; Doyle, Mark; Devereux, Richard B.; Kortright, Eduardo; Perry, Gilbert; Bella, Jonathan N.; Oparil, Suzanne; Calhoun, David; Pohost, Gerald M.; Dell’Italia, Louis J.

    2015-01-01

    Background Increased relative wall thickness in hypertensive left ventricular hypertrophy (LVH) has been shown by echocardiography to allow preserved shortening at the endocardium despite depressed LV midwall circumferential shortening (MWCS). Depressed MWCS is an adverse prognostic indicator, but whether this finding reflects reduced global or regional LV myocardial function, as assessed by three-dimensional (3D) myocardial strain, is unknown. Methods and Results Cardiac Magnetic Resonance (CMR) tissue tagging permits direct evaluation of regional 3D intramyocardial strain, independent of LV geometry. We evaluated 21 hypertensive patients with electrocardiographic LVH in the LIFE study and 8 normal controls using 3D MR tagging and echocardiography. Patients had higher MR LV mass than normals (116 ± 40 versus 63 ± 6 g/m2, P = 0.002). Neither echocardiographic fractional shortening (32 ± 6 versus 33% ± 3%), LVEF (63% versus 64%) or mean end-systolic stress (175 ± 27 versus 146 ± 28 g/cm2) were significantly different, yet global MWCS was decreased by both echocardiography (13.4 ± 2.8 versus 18.2% ± 1.5%, P < 0.001) and MR (16.8 ± 3.6 versus 21.6% ± 3.0%, P < 0.005). 3D MR MWCS was lower at the base versus apex (P = 0.002) in LVH and greater in lateral and anterior regions versus septal and posterior regions (P < 0.001), contributing to the higher mean global MWCS by MR than echo. MR longitudinal strain was severely depressed in LVH patients (11.0 ± 3.3 versus 16.5% ± 2.5%, P < 0.001) and apical twist was increased (17.5 ± 4.3 versus 13.7 ± 3.7, P < 0.05). Importantly, both circumferential and longitudinal shortening correlated with LV relative wall thickness (R > 0.60, P = 0.001 for both). Conclusions In patients with hypertensive LVH, despite normal LV function via echocardiography or CMR, CMR intramyocardial tagging show depressed global MWCS while 3D MR strain revealed marked underlying regional heterogeneity of LV dysfunction. PMID:27011783

  2. Optical Aptasensors for Adenosine Triphosphate

    PubMed Central

    Ng, Stella; Lim, Hui Si; Ma, Qian; Gao, Zhiqiang

    2016-01-01

    Nucleic acids are among the most researched and applied biomolecules. Their diverse two- and three-dimensional structures in conjunction with their robust chemistry and ease of manipulation provide a rare opportunity for sensor applications. Moreover, their high biocompatibility has seen them being used in the construction of in vivo assays. Various nucleic acid-based devices have been extensively studied as either the principal element in discrete molecule-like sensors or as the main component in the fabrication of sensing devices. The use of aptamers in sensors - aptasensors, in particular, has led to improvements in sensitivity, selectivity, and multiplexing capacity for a wide verity of analytes like proteins, nucleic acids, as well as small biomolecules such as glucose and adenosine triphosphate (ATP). This article reviews the progress in the use of aptamers as the principal component in sensors for optical detection of ATP with an emphasis on sensing mechanism, performance, and applications with some discussion on challenges and perspectives. PMID:27446501

  3. Adenosine Kinase: Exploitation for Therapeutic Gain

    PubMed Central

    2013-01-01

    Adenosine kinase (ADK; EC 2.7.1.20) is an evolutionarily conserved phosphotransferase that converts the purine ribonucleoside adenosine into 5′-adenosine-monophosphate. This enzymatic reaction plays a fundamental role in determining the tone of adenosine, which fulfills essential functions as a homeostatic and metabolic regulator in all living systems. Adenosine not only activates specific signaling pathways by activation of four types of adenosine receptors but it is also a primordial metabolite and regulator of biochemical enzyme reactions that couple to bioenergetic and epigenetic functions. By regulating adenosine, ADK can thus be identified as an upstream regulator of complex homeostatic and metabolic networks. Not surprisingly, ADK dysfunction is involved in several pathologies, including diabetes, epilepsy, and cancer. Consequently, ADK emerges as a rational therapeutic target, and adenosine-regulating drugs have been tested extensively. In recent attempts to improve specificity of treatment, localized therapies have been developed to augment adenosine signaling at sites of injury or pathology; those approaches include transplantation of stem cells with deletions of ADK or the use of gene therapy vectors to downregulate ADK expression. More recently, the first human mutations in ADK have been described, and novel findings suggest an unexpected role of ADK in a wider range of pathologies. ADK-regulating strategies thus represent innovative therapeutic opportunities to reconstruct network homeostasis in a multitude of conditions. This review will provide a comprehensive overview of the genetics, biochemistry, and pharmacology of ADK and will then focus on pathologies and therapeutic interventions. Challenges to translate ADK-based therapies into clinical use will be discussed critically. PMID:23592612

  4. The adenosine neuromodulation system in schizophrenia.

    PubMed

    Rial, Daniel; Lara, Diogo R; Cunha, Rodrigo A

    2014-01-01

    The management of schizophrenia endophenotypes, namely positive, negative, and cognitive symptoms is still an open goal, justifying the search of novel therapeutic avenues. We now review the evidence supporting the interest in targeting the adenosine modulation system to counteract the core features of schizophrenia. This interest is forwarded by the combined ability of strategies aimed at bolstering adenosine levels together with the increasingly recognized impact of adenosine A2A receptors to control dopaminergic signaling, working memory, and behavioral sensitization; this is further heralded by the suggested clinical effectiveness of therapies increasing extracellular adenosine such as dipyridamole and allopurinol and the emergent recognition of a role for adenosine in neurodevelopment. Finally, the combined role of A1 and A2A receptors in assisting the implementation of adaptive changes and encoding of information salience in neuronal circuits together with the adaptive alterations of A1 and A2A receptor density upon brain dysfunction prompts the novel working hypothesis that the parallel imbalance of adenosine formation and of A1 and A2A receptors blurs the adequate encoding of information salience in neuronal circuits, which we propose to be a core pathogenic feature in the development of schizophrenia endophenotypes. This proposal should also provide a rationale to assist the design of future therapeutic intervention targeting the adenosine modulation system to manage schizophrenia endophenotypes: these should not be based only on an attempt to target adenosine kinase-A1 receptors or only A2A receptors, but should instead simultaneously target these two arms of the adenosine modulation system. PMID:25175974

  5. The role of stress cardiac magnetic resonance in women.

    PubMed

    Cardona, Andrea; Zareba, Karolina M; Raman, Subha V

    2016-10-01

    Coronary artery disease (CAD) is the leading cause of death in women. Nevertheless, extensive evidence demonstrates under-diagnosis and under-treatment of women for suspected or known ischemic heart disease (IHD). Stress cardiac magnetic resonance (CMR) is becoming readily available and offers significant advantages over other stress imaging modalities. The high spatial and temporal resolution of CMR provides the unique ability to identify subendocardial ischemia, viability, and the presence of microvascular disease. Furthermore, CMR is free from ionizing radiation, and image quality is not compromised by attenuation artifacts or patient size. Over the past two decades, evidence-based data have demonstrated the high diagnostic and prognostic performance of stress CMR in the context of IHD, often superior to other stress imaging techniques. Importantly, ad hoc studies confirmed these results in women with known or suspected IHD. Stress CMR warrants consideration as the modality of choice for women requiring an imaging test for ischemia given its strong evidence base, superior test characteristics, comprehensive nature, and unique ability to characterize both epicardial and microvascular disease.

  6. Adenosine receptors as drug targets — what are the challenges?

    PubMed Central

    Chen, Jiang-Fan; Eltzschig, Holger K.; Fredholm, Bertil B.

    2014-01-01

    Adenosine signalling has long been a target for drug development, with adenosine itself or its derivatives being used clinically since the 1940s. In addition, methylxanthines such as caffeine have profound biological effects as antagonists at adenosine receptors. Moreover, drugs such as dipyridamole and methotrexate act by enhancing the activation of adenosine receptors. There is strong evidence that adenosine has a functional role in many diseases, and several pharmacological compounds specifically targeting individual adenosine receptors — either directly or indirectly — have now entered the clinic. However, only one adenosine receptor-specific agent — the adenosine A2A receptor agonist regadenoson (Lexiscan; Astellas Pharma) — has so far gained approval from the US Food and Drug Administration (FDA). Here, we focus on the biology of adenosine signalling to identify hurdles in the development of additional pharmacological compounds targeting adenosine receptors and discuss strategies to overcome these challenges. PMID:23535933

  7. Mast Cell Adenosine Receptors Function: A Focus on the A3 Adenosine Receptor and Inflammation

    PubMed Central

    Rudich, Noam; Ravid, Katya; Sagi-Eisenberg, Ronit

    2012-01-01

    Adenosine is a metabolite, which has long been implicated in a variety of inflammatory processes. Inhaled adenosine provokes bronchoconstriction in asthmatics or chronic obstructive pulmonary disease patients, but not in non-asthmatics. This hyper responsiveness to adenosine appears to be mediated by mast cell activation. These observations have marked the receptor that mediates the bronchoconstrictor effect of adenosine on mast cells (MCs), as an attractive drug candidate. Four subtypes (A1, A2a, A2b, and A3) of adenosine receptors have been cloned and shown to display distinct tissue distributions and functions. Animal models have firmly established the ultimate role of the A3 adenosine receptor (A3R) in mediating hyper responsiveness to adenosine in MCs, although the influence of the A2b adenosine receptor was confirmed as well. In contrast, studies of the A3R in humans have been controversial. In this review, we summarize data on the role of different adenosine receptors in mast cell regulation of inflammation and pathology, with a focus on the common and distinct functions of the A3R in rodent and human MCs. The relevance of mouse studies to the human is discussed. PMID:22675325

  8. [Adenosine deaminase in experimental trypanosomiasis: future implications].

    PubMed

    Pérez-Aguilar, Mary Carmen; Rondón-Mercado, Rocío

    2015-09-01

    The adenosine deaminase represents a control point in the regulation of extracellular adenosine levels, thus playing a critical role in the modulation of purinergic responses to certain pathophysiological events. Several studies have shown that serum and plasma enzyme levels are elevated in some diseases caused by microorganisms, which may represent a compensatory mechanism due to the elevated levels of adenosine and the release of inflammatory mediators. Recent research indicates that adenosine deaminase activity decreases and affects hematological parameters of infected animals with Trypanosoma evansi, so that such alterations could have implications in the pathogenesis of the disease. In addition, the enzyme has been detected in this parasite; allowing the inference that it could be associated with the vital functions of the same, similar to what occurs in mammals. This knowledge may be useful in the association of chemotherapy with specific inhibitors of the enzyme in future studies.

  9. CMR Imaging With Rapid Visual T1 Assessment Predicts Mortality in Patients Suspected of Cardiac Amyloidosis

    PubMed Central

    White, James A.; Kim, Han W.; Shah, Dipan; Fine, Nowell; Kim, Ki-Young; Wendell, David C.; Al-Jaroudi, Wael; Parker, Michele; Patel, Manesh; Gwadry-Sridhar, Femida; Judd, Robert M.; Kim, Raymond J.

    2014-01-01

    OBJECTIVES This study tested the diagnostic and prognostic utility of a rapid, visual T1 assessment method for identification of cardiac amyloidosis (CA) in a “real-life” referral population undergoing cardiac magnetic resonance for suspected CA. BACKGROUND In patients with confirmed CA, delayed-enhancement cardiac magnetic resonance (DE-CMR) frequently shows a diffuse, global hyperenhancement (HE) pattern. However, imaging is often technically challenging, and the prognostic significance of diffuse HE is unclear. METHODS Ninety consecutive patients referred for suspected CA and 64 hypertensive patients with left ventricular hypertrophy (LVH) were prospectively enrolled and underwent a modified DE-CMR protocol. After gadolinium administration a method for rapid, visual T1 assessment was used to identify the presence of diffuse HE during the scan, allowing immediate optimization of settings for the conventional DE-CMR that followed. The primary endpoint was all-cause mortality. RESULTS Among patients with suspected CA, 66% (59 of 90) demonstrated HE, with 81% (48 of 59) of these meeting pre-specified visual T1 assessment criteria for diffuse HE. Among hypertensive LVH patients, 6% (4 of 64) had HE, with none having diffuse HE. During 29 months of follow-up (interquartile range: 12 to 44 months), there were 50 (56%) deaths in patients with suspected CA and 4 (6%) in patients with hypertensive LVH. Multivariable analysis demonstrated that the presence of diffuse HE was the most important predictor of death in the group with suspected CA (hazard ratio: 5.5, 95% confidence interval: 2.7 to 11.0; p < 0.0001) and in the population as a whole (hazard ratio: 6.0, 95% confidence interval 3.0 to 12.1; p < 0.0001). Among 25 patients with myocardial histology obtained during follow-up, the sensitivity, specificity, and accuracy of diffuse HE in the diagnosis of CA were 93%, 70%, and 84%, respectively. CONCLUSIONS Among patients suspected of CA, the presence of diffuse HE by

  10. Role of adenosine receptors in caffeine tolerance

    SciTech Connect

    Holtzman, S.G.; Mante, S.; Minneman, K.P. )

    1991-01-01

    Caffeine is a competitive antagonist at adenosine receptors. Receptor up-regulation during chronic drug treatment has been proposed to be the mechanism of tolerance to the behavioral stimulant effects of caffeine. This study reassessed the role of adenosine receptors in caffeine tolerance. Separate groups of rats were given scheduled access to drinking bottles containing plain tap water or a 0.1% solution of caffeine. Daily drug intake averaged 60-75 mg/kg and resulted in complete tolerance to caffeine-induced stimulation of locomotor activity, which could not be surmounted by increasing the dose of caffeine. 5'-N-ethylcarboxamidoadenosine (0.001-1.0 mg/kg) dose dependently decreased the locomotor activity of caffeine-tolerant rats and their water-treated controls but was 8-fold more potent in the latter group. Caffeine (1.0-10 mg/kg) injected concurrently with 5-N-ethylcarboxamidoadenosine antagonized the decreases in locomotor activity comparably in both groups. Apparent pA2 values for tolerant and control rats also were comparable: 5.05 and 5.11. Thus, the adenosine-antagonist activity of caffeine was undiminished in tolerant rats. The effects of chronic caffeine administration on parameters of adenosine receptor binding and function were measured in cerebral cortex. There were no differences between brain tissue from control and caffeine-treated rats in number and affinity of adenosine binding sites or in receptor-mediated increases (A2 adenosine receptor) and decreases (A1 adenosine receptor) in cAMP accumulation. These results are consistent with theoretical arguments that changes in receptor density should not affect the potency of a competitive antagonist. Experimental evidence and theoretical considerations indicate that up-regulation of adenosine receptors is not the mechanism of tolerance to caffeine-induced stimulation of locomotor activity.

  11. Adenosine inhibits glutamatergic input to basal forebrain cholinergic neurons

    PubMed Central

    Hawryluk, J. M.; Ferrari, L. L.; Keating, S. A.

    2012-01-01

    Adenosine has been proposed as an endogenous homeostatic sleep factor that accumulates during waking and inhibits wake-active neurons to promote sleep. It has been specifically hypothesized that adenosine decreases wakefulness and promotes sleep recovery by directly inhibiting wake-active neurons of the basal forebrain (BF), particularly BF cholinergic neurons. We previously showed that adenosine directly inhibits BF cholinergic neurons. Here, we investigated 1) how adenosine modulates glutamatergic input to BF cholinergic neurons and 2) how adenosine uptake and adenosine metabolism are involved in regulating extracellular levels of adenosine. Our experiments were conducted using whole cell patch-clamp recordings in mouse brain slices. We found that in BF cholinergic neurons, adenosine reduced the amplitude of AMPA-mediated evoked glutamatergic excitatory postsynaptic currents (EPSCs) and decreased the frequency of spontaneous and miniature EPSCs through presynaptic A1 receptors. Thus we have demonstrated that in addition to directly inhibiting BF cholinergic neurons, adenosine depresses excitatory inputs to these neurons. It is therefore possible that both direct and indirect inhibition may synergistically contribute to the sleep-promoting effects of adenosine in the BF. We also found that blocking the influx of adenosine through the equilibrative nucleoside transporters or inhibiting adenosine kinase and adenosine deaminase increased endogenous adenosine inhibitory tone, suggesting a possible mechanism through which adenosine extracellular levels in the basal forebrain are regulated. PMID:22357797

  12. Environmental assessment for the proposed CMR Building upgrades at the Los Alamos National Laboratory, Los Alamos, New Mexico. Final document

    SciTech Connect

    1997-02-04

    In order to maintain its ability to continue to conduct uninterrupted radioactive and metallurgical research in a safe, secure, and environmentally sound manner, the US Department of Energy (DOE) proposes to upgrade the Los Alamos National Laboratory (LANL) Chemistry and Metallurgy Research (CMR) Building. The building was built in the early 1950s to provide a research and experimental facility for analytical chemistry, plutonium and uranium chemistry, and metallurgy. Today, research and development activities are performed involving nuclear materials. A variety of radioactive and chemical hazards are present. The CMR Building is nearing the end of its original design life and does not meet many of today`s design codes and standards. The Proposed Action for this Environmental Assessment (EA) includes structural modifications to some portions of the CMR Building which do not meet current seismic criteria for a Hazard Category 2 Facility. Also included are upgrades and improvements in building ventilation, communications, monitoring, and fire protection systems. This EA analyzes the environmental effects of construction of the proposed upgrades. The Proposed Action will have no adverse effects upon agricultural and cultural resources, wetlands and floodplains, endangered and threatened species, recreational resources, or water resources. The Proposed Action would have negligible effects on human health and transportation, and would not pose a disproportionate adverse health or environmental impact on minority or low-income populations within an 80 kilometer (50 mile) radius of the CMR Building.

  13. Characterization of a cAMP responsive transcription factor, Cmr (Rv1675c), in TB complex mycobacteria reveals overlap with the DosR (DevR) dormancy regulon

    PubMed Central

    Ranganathan, Sridevi; Bai, Guangchun; Lyubetskaya, Anna; Knapp, Gwendowlyn S.; Peterson, Matthew W.; Gazdik, Michaela; C. Gomes, Antonio L.; Galagan, James E.; McDonough, Kathleen A.

    2016-01-01

    Mycobacterium tuberculosis (Mtb) Cmr (Rv1675c) is a CRP/FNR family transcription factor known to be responsive to cAMP levels and during macrophage infections. However, Cmr's DNA binding properties, cellular targets and overall role in tuberculosis (TB) complex bacteria have not been characterized. In this study, we used experimental and computational approaches to characterize Cmr's DNA binding properties and identify a putative regulon. Cmr binds a 16-bp palindromic site that includes four highly conserved nucleotides that are required for DNA binding. A total of 368 binding sites, distributed in clusters among ∼200 binding regions throughout the Mycobacterium bovis BCG genome, were identified using ChIP-seq. One of the most enriched Cmr binding sites was located upstream of the cmr promoter, and we demonstrated that expression of cmr is autoregulated. cAMP affected Cmr binding at a subset of DNA loci in vivo and in vitro, including multiple sites adjacent to members of the DosR (DevR) dormancy regulon. Our findings of cooperative binding of Cmr to these DNA regions and the regulation by Cmr of the DosR-regulated virulence gene Rv2623 demonstrate the complexity of Cmr-mediated gene regulation and suggest a role for Cmr in the biology of persistent TB infection. PMID:26358810

  14. Blood Oxygenation Level-Dependent CMR-Derived Measures in Critical Limb Ischemia and Changes With Revascularization

    PubMed Central

    Bajwa, Adnan; Wesolowski, Roman; Patel, Ashish; Saha, Prakash; Ludwinski, Francesca; Ikram, Mohammed; Albayati, Mostafa; Smith, Alberto; Nagel, Eike; Modarai, Bijan

    2016-01-01

    Background Use of blood oxygenation level-dependent cardiovascular magnetic resonance (BOLD-CMR) to assess perfusion in the lower limb has been hampered by poor reproducibility and a failure to reliably detect post-revascularization improvements in patients with critical limb ischemia (CLI). Objectives This study sought to develop BOLD-CMR as an objective, reliable clinical tool for measuring calf muscle perfusion in patients with CLI. Methods The calf was imaged at 3-T in young healthy control subjects (n = 12), age-matched control subjects (n = 10), and patients with CLI (n = 34). Signal intensity time curves were generated for each muscle group and curve parameters, including signal reduction during ischemia (SRi) and gradient during reactive hyperemia (Grad). BOLD-CMR was used to assess changes in perfusion following revascularization in 12 CLI patients. Muscle biopsies (n = 28), obtained at the level of BOLD-CMR measurement and from healthy proximal muscle of patients undergoing lower limb amputation (n = 3), were analyzed for capillary-fiber ratio. Results There was good interuser and interscan reproducibility for Grad and SRi (all p < 0.0001). The ischemic limb had lower Grad and SRi compared with the contralateral asymptomatic limb, age-matched control subjects, and young control subjects (p < 0.001 for all comparisons). Successful revascularization resulted in improvement in Grad (p < 0.0001) and SRi (p < 0.0005). There was a significant correlation between capillary-fiber ratio (p < 0.01) in muscle biopsies from amputated limbs and Grad measured pre-operatively at the corresponding level. Conclusions BOLD-CMR showed promise as a reliable tool for assessing perfusion in the lower limb musculature and merits further investigation in a clinical trial. PMID:26821631

  15. Contrast-enhanced CMR in patients after percutaneous closure of the left atrial appendage: A pilot study

    PubMed Central

    2011-01-01

    Background To evaluate the feasibility and value of first-pass contrast-enhanced dynamic and post-contrast 3D CMR in patients after transcatheter occlusion of left atrial appendage (LAA) to identify incorrect placement and persistent leaks. Methods 7 patients with different occluder systems (n = 4 PLAATO; n = 2 Watchman; n = 1 ACP) underwent 2 contrast-enhanced (Gd-DOTA) CMR sequences (2D TrueFISP first-pass perfusion and 3D-TurboFLASH) to assess localization, artifact size and potential leaks of the devices. Perfusion CMR was analyzed visually and semi-quantitatively to identify potential leaks. Results All occluders were positioned within the LAA. The ACP occluder presented the most extensive artifact size. Visual assessment revealed a residual perfusion of the LAA apex in 4 cases using first-pass perfusion and 3D-TurboFLASH indicating a suboptimal LAA occlusion. By assessing signal-to-time-curves the cases with a visually detected leak showed a 9-fold higher signal-peak in the LAA apex (567 ± 120% increase from baseline signal) than those without a leak (61 ± 22%; p < 0.03). In contrast, the signal increase in LAA proximal to the occluder showed no difference (leak 481 ± 201% vs. no leak 478 ± 125%; p = 0.48). Conclusion This CMR pilot study provides valuable non-invasive information in patients after transcatheter occlusion of the LAA to identify correct placement and potential leaks. We recommend incorporating CMR in future clinical studies to evaluate new device types. PMID:21726450

  16. Adenosine modulation of [Ca2+]i in cerebellar granular cells: multiple adenosine receptors involved.

    PubMed

    Vacas, Javier; Fernández, Mercedes; Ros, Manuel; Blanco, Pablo

    2003-12-01

    Elimination of adenosine by addition of adenosine deaminase (ADA) to the media leads to alterations in intracellular free calcium concentration ([Ca(2+)](i)) in cerebellar granular cells. Adenosine deaminase brings about increases or decreases in [Ca(2+)](i) depending on the previous activation state of the cell. These effects are dependent on the catalytic activity of adenosine deaminase, since its previous catalytic inactivation with Hg(2+) prevents the above-mentioned changes in intracellular calcium. Extracellular calcium is required for the increase in [Ca(2+)](i) promoted by ADA. This rise is insensitive to thapsigargin, but sensitive to micromolar concentrations of Ni(2+). Toxins specific for L, N and P/Q calcium channels do not overtly reduce this effect. N(6)-Cyclopentyl adenosine (CPA), an A(1) receptor agonist, produces a partial reversion of ADA effects, while CGS21680, A(2A)/A(2B) receptor agonist, slightly enhances them. Expression of A(1), A(2A), A(2B) and A(3) adenosine receptor mRNAs was detected in cerebellar granular cell cultures. These results suggest that adenosine modulate [Ca(2+)](i) in cerebellar granule cells through different adenosine receptor subtypes which, at least in part, seem to act through R-type calcium channels.

  17. Mucosal adenosine stimulates chloride secretion in canine tracheal epithelium

    SciTech Connect

    Pratt, A.D.; Clancy, G.; Welsh, M.J.

    1986-08-01

    Adenosine is a local regulator of a variety of physiological functions in many tissues and has been observed to stimulate secretion in several Cl-secreting epithelia. In canine tracheal epithelium the authors found that adenosine stimulates Cl secretion from both the mucosal and submucosal surfaces. Addition of adenosine, or its analogue 2-chloroadenosine, to the mucosal surface potently stimulated Cl secretion with no effect on the rate of Na absorption. Stimulation resulted from an interaction of adenosine with adenosine receptors, because it was blocked by the adenosine receptor blocker, 8-phenyltheophylline. The adenosine receptor was a stimulatory receptor as judged by the rank-order potency of adenosine and its analogues and by the increase in cellular adenosine 3',5'-cyclic monophosphate levels produced by 2-chloroadenosine. Adenosine also stimulated Cl secretion when it was added to the submucosal surface, although the maximal increase in secretion was less and it was much less potent. The observation that mucosal 8-phenyletheophylline blocked the effect of submucosal 2-chloroadenosine, whereas submucosal 8-phenyltheophylline did not prevent a response to mucosal or submucosal 2-chloroadenosine, suggests that adenosine receptors are located on the mucosal surface. Thus submucosal adenosine may stimulate secretion by crossing the epithelium and interacting with receptors located on the mucosal surface. Because adenosine can be released from mast cells located in the airway lumen in response to inhaled material, and because adenosine stimulated secretion from the mucosal surface, it may be in a unique position to control the epithelium on a regional level.

  18. MOLECULAR PROBES FOR EXTRACELLULAR ADENOSINE RECEPTORS

    PubMed Central

    Jacobson, Kenneth A.; Ukena, Dieter; Padgett, William; Kirk, Kenneth L.; Daly, John W.

    2012-01-01

    Derivatives of adenosine receptor agonists (N6-phenyladenosines) and antagonists (1,3-dialkyl-8-phenylxanthines) bearing functionalized chains suitable for attachment to other molecules have been reported [Jacobson et al., J. med. Chem. 28, 1334 and 1341 (1985)]. The “functionalized congener” approach has been extended to the synthesis of spectroscopic and other probes for adenosine receptors that retain high affinity (Ki ~ 10−9 −10−8 M) in A1-receptor binding. The probes have been synthesized from an antagonist xanthine amine congener (XAC) and an adenosine amine congener (ADAC). [3H]ADAC has been synthesized and found to bind highly specifically to A1-adenosine receptors of rat and calf cerebral cortical membranes with KD values of 1.4 and 0.34 nM respectively. The higher affinity in the bovine brain, seen also with many of the probes derived from ADAC and XAC, is associated with phenyl substituents. The spectroscopic probes contain a reporter group attached at a distal site of the functionalized chain. These bifunctional ligands may contain a spin label (e.g. the nitroxyl radical TEMPO) for electron spin resonance spectroscopy, or a fluorescent dye, including fluorescein and 4-nitrobenz-2-oxa-1,3-diazole (NBD), or labels for 19F nuclear magnetic resonance spectroscopy. Potential applications of the spectroscopic probes in characterization of adenosine receptors are discussed. PMID:3036153

  19. Determination of adenosine effects and adenosine receptors in murine corpus cavernosum.

    PubMed

    Tostes, Rita C; Giachini, Fernanda R C; Carneiro, Fernando S; Leite, Romulo; Inscho, Edward W; Webb, R Clinton

    2007-08-01

    This study tested the hypothesis that adenosine, in murine corpora cavernosa, produces direct relaxation of smooth muscle cells and inhibition of contractile responses mediated by sympathetic nerve stimulation. Penes were excised from anesthetized male C57BL/6 mice, dissected, and cavernosal strips were mounted to record isometric force. Adenosine, 2-chloroadenosine (stable analog of adenosine), and 2-phenylaminoadenosine (CV1808) (A2(A)/A2(B) agonist) produced concentration-dependent relaxations of phenylephrine-contracted tissues. Relaxation to 2-chloroadenosine was inhibited, in a concentration-dependent manner, by 2-(2-furanyl)-7-(2-phenylethyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine (SCH58261; A2(A) antagonist; 10(-9)-10(-6) M) and N-(4-acetylphenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl)phenoxy]acetamida (MRS1706; A2(B) antagonist; 10(-8)-10(-6) M). The combination of both antagonists abrogated 2-chloroadenosine-induced relaxation. Electrical field stimulation (EFS; 1-32 Hz) of adrenergic nerves produced frequency-dependent contractions that were inhibited by compounds that increase adenosine levels, such as 5'-iodotubercidin (adenosine kinase inhibitor), erythro-9-(2-hydroxy-3-nonyl)adenine (adenosine deaminase inhibitor), and dipyridamole (inhibitor of adenosine transport). The adenosine A1 receptor agonist N(6)-cyclopentyladenosine (C8031) right-shifted contractile responses to EFS, with a significant inhibitory effect at 10(-6) M. Blockade of adenosine A1 receptors with 8-cyclopentyl-1,3-dipropylxanthine (C101) (10(-7) M) enhanced contractile responses to EFS and eliminated the inhibitory effects of 5'-iodotubercidin. Dipyridamole and 5'-iodotubercidin had no effect on adenosine-mediated relaxation. In summary, adenosine directly relaxes cavernosal smooth muscle cells, by the activation of A2(A)/A2(B) receptor subtypes. In addition, adenosine negatively modulates sympathetic neurotransmission, by A1 receptor

  20. Working memory and the homeostatic control of brain adenosine by adenosine kinase.

    PubMed

    Singer, P; McGarrity, S; Shen, H-Y; Boison, D; Yee, B K

    2012-06-28

    The neuromodulator adenosine maintains brain homeostasis and regulates complex behaviour via activation of inhibitory and excitatory adenosine receptors (ARs) in a brain region-specific manner. AR antagonists such as caffeine have been shown to ameliorate cognitive impairments in animal disease models but their effects on learning and memory in normal animals are equivocal. An alternative approach to reduce AR activation is to lower the extracellular tone of adenosine, which can be achieved by up-regulating adenosine kinase (ADK), the key enzyme of metabolic adenosine clearance. However, mice that globally over-express an Adk transgene ('Adk-tg' mice) were devoid of a caffeine-like pro-cognitive profile; they instead exhibited severe spatial memory deficits. This may be mechanistically linked to cortical/hippocampal N-methyl-d-aspartate receptor (NMDAR) hypofunction because the motor response to acute MK-801 was also potentiated in Adk-tg mice. Here, we evaluated the extent to which the behavioural phenotypes of Adk-tg mice might be modifiable by up-regulating adenosine levels in the cortex/hippocampus. To this end, we investigated mutant 'fb-Adk-def' mice in which ADK expression was specifically reduced in the telencephalon leading to a selective increase in cortical/hippocampal adenosine, while the rest of the brain remained as adenosine-deficient as in Adk-tg mice. The fb-Adk-def mice showed an even greater impairment in spatial working memory and a more pronounced motor response to NMDAR blockade than Adk-tg mice. These outcomes suggest that maintenance of cortical/hippocampal adenosine homeostasis is essential for effective spatial memory and deviation in either direction is detrimental with increased expression seemingly more disruptive than decreased expression.

  1. Fiber architecture in remodeled myocardium revealed with a quantitative diffusion CMR tractography framework and histological validation

    PubMed Central

    2012-01-01

    Background The study of myofiber reorganization in the remote zone after myocardial infarction has been performed in 2D. Microstructural reorganization in remodeled hearts, however, can only be fully appreciated by considering myofibers as continuous 3D entities. The aim of this study was therefore to develop a technique for quantitative 3D diffusion CMR tractography of the heart, and to apply this method to quantify fiber architecture in the remote zone of remodeled hearts. Methods Diffusion Tensor CMR of normal human, sheep, and rat hearts, as well as infarcted sheep hearts was performed ex vivo. Fiber tracts were generated with a fourth-order Runge-Kutta integration technique and classified statistically by the median, mean, maximum, or minimum helix angle (HA) along the tract. An index of tract coherence was derived from the relationship between these HA statistics. Histological validation was performed using phase-contrast microscopy. Results In normal hearts, the subendocardial and subepicardial myofibers had a positive and negative HA, respectively, forming a symmetric distribution around the midmyocardium. However, in the remote zone of the infarcted hearts, a significant positive shift in HA was observed. The ratio between negative and positive HA variance was reduced from 0.96 ± 0.16 in normal hearts to 0.22 ± 0.08 in the remote zone of the remodeled hearts (p<0.05). This was confirmed histologically by the reduction of HA in the subepicardium from −52.03° ± 2.94° in normal hearts to −37.48° ± 4.05° in the remote zone of the remodeled hearts (p < 0.05). Conclusions A significant reorganization of the 3D fiber continuum is observed in the remote zone of remodeled hearts. The positive (rightward) shift in HA in the remote zone is greatest in the subepicardium, but involves all layers of the myocardium. Tractography-based quantification, performed here for the first time in remodeled hearts, may provide a framework for assessing

  2. Evidence for Polaron Transport from Hall Effect, Resistivity and Thermopower in CMR Perovskite Materials

    NASA Astrophysics Data System (ADS)

    Jaime, Marcelo

    1998-03-01

    The experimental transport properties of so called colossal magnetoresistance (CMR) perovskite materials of composition A_1-xB_xMnO3 (A: La, Gd ; B: Sr,Ca,Pb) with x ~ 0.33, classically described in the context of the double exchange model by Zener(C. Zener, Phys. Rev. 82), 403 (1951), were studied over an extensive temperature range from a small fraction of the Curie temperature (T_C) to several times T_C. In the ferromagnetic state of La_2/3(Ca,Pb)_1/3MnO3 single crystals the resistivity reveals electron-magnon scattering processes that vanish below 20 K. The failure of single magnon scattering processes to be completely suppressed suggests the persistence of partially spin-polarized electronic bands at low temperatures. In this regime the thermopower shows evidence for mass-enhanced hole-like transport. Our high temperature thermopower measurements(M. Jaime et al. Appl. Phys. Lett. 68), 1576 (1996); Phys. Rev. B54, 11914 (1996), on the other hand, were the first unmistakable evidence for polaronic effects in CMR. Confirming the thermopower results, the Hall coefficient of Gd-doped La_2/3Ca_1/3MnO3 exhibits Arrhenius behavior over a temperature range from 2 TC to 4 T_C, with an activation energy very close to 2/3 that of the electrical conductivity. Although both the doping level and thermoelectric coefficient indicate hole-like conduction, the Hall coefficient is electron-like. This unusual result provides strong evidence in favor of small-polaronic conduction in the paramagnetic regime of the manganites(M. Jaime et al. Phys. Rev. Lett. 78) 951 (1997). La_2/3(Ca,Pb)_1/3MnO3 single crystals high temperature thermopower Hall coefficient of Gd-doped La_2/3Ca_1/3MnO_3 http://xxx.lanl.gov/abs/cond-mat/9609194

  3. Pain-relieving prospects for adenosine receptors and ectonucleotidases

    PubMed Central

    Zylka, Mark J.

    2010-01-01

    Adenosine receptor agonists have potent antinociceptive effects in diverse preclinical models of chronic pain. In contrast, the efficacy of adenosine or adenosine receptor agonists at treating pain in humans is unclear. Two ectonucleotidases that generate adenosine in nociceptive neurons were recently identified. When injected spinally, these enzymes have long-lasting adenosine A1 receptor (A1R)-dependent antinociceptive effects in inflammatory and neuropathic pain models. Furthermore, recent findings indicate that spinal adenosine A2A receptor activation can enduringly inhibit neuropathic pain symptoms. Collectively, these studies suggest the possibility of treating chronic pain in humans by targeting specific adenosine receptor subtypes in anatomically defined regions with agonists or with ectonucleotidases that generate adenosine. PMID:21236731

  4. High Concordance Between Mental Stress–Induced and Adenosine-Induced Myocardial Ischemia Assessed Using SPECT in Heart Failure Patients: Hemodynamic and Biomarker Correlates

    PubMed Central

    Wawrzyniak, Andrew J.; Dilsizian, Vasken; Krantz, David S.; Harris, Kristie M.; Smith, Mark F.; Shankovich, Anthony; Whittaker, Kerry S.; Rodriguez, Gabriel A.; Gottdiener, John; Li, Shuying; Kop, Willem; Gottlieb, Stephen S.

    2016-01-01

    Mental stress can trigger myocardial ischemia, but the prevalence of mental stress–induced ischemia in congestive heart failure (CHF) patients is unknown. We characterized mental stress–induced and adenosine-induced changes in myocardial perfusion and neurohormonal activation in CHF patients with reduced left-ventricular function using SPECT to precisely quantify segment-level myocardial perfusion. Methods Thirty-four coronary artery disease patients (mean age ± SD, 62 ± 10 y) with CHF longer than 3 mo and ejection fraction less than 40% underwent both adenosine and mental stress myocardial perfusion SPECT on consecutive days. Mental stress consisted of anger recall (anger-provoking speech) followed by subtraction of serial sevens. The presence and extent of myocardial ischemia was quantified using the conventional 17-segment model. Results Sixty-eight percent of patients had 1 ischemic segment or more during mental stress and 81% during adenosine. On segment-by-segment analysis, perfusion with mental stress and adenosine were highly correlated. No significant differences were found between any 2 time points for B-type natriuretic peptide, tumor necrosis factor-α, IL-1b, troponin, vascular endothelin growth factor, IL-17a, matrix metallopeptidase-9, or C-reactive protein. However, endothelin-1 and IL-6 increased, and IL-10 decreased, between the stressor and 30 min after stress. Left-ventricular end diastolic dimension was 179 ± 65 mL at rest and increased to 217 ± 71 after mental stress and 229 ± 86 after adenosine (P < 0.01 for both). Resting end systolic volume was 129 ± 60 mL at rest and increased to 158 ± 66 after mental stress (P < 0.05) and 171 ± 87 after adenosine (P < 0.07), with no significant differences between adenosine and mental stress. Ejection fraction was 30 ± 12 at baseline, 29 ± 11 with mental stress, and 28 ± 10 with adenosine (P = not significant). Conclusion There was high concordance between ischemic perfusion defects induced

  5. Structural studies on the substitution of Ag, Na doped LCSMO CMR manganites

    NASA Astrophysics Data System (ADS)

    Subhashini, P.; Munirathinam, B.; Krishnaiah, M.; Venkatesh, R.; Venkateswarlu, D.; Ganesan, V.

    2016-05-01

    Synthesis and characterization of colossal magnetoresistance (CMR) materials has been a subject of scientific research due to the unique transport, magnetotransport, and magnetic properties. The single phase polycrystalline La0.7Ca0.1Sr0.1M0.1MnO3 (LCSMO) (M=Ag and Na) samples prepared using nitrate route method. The structural properties are studied at different dopants by X-ray diffraction. The surface morphology and elemental analysis of both samples were carried out by scanning electron microscopy (SEM) and energy dispersive X-ray technique (EDAX) respectively. The structural analysis shows that the LCSMO is crystallized in an orthorhombic perovskite structure belonging to Pnma space group. The crystal size of the sample is calculated using Scherrer formula. The SEM images show that the polycrystalline grains are observed to be near spherical shape and uniform in size. EDAX spectra taken from the surface of the synthesized powders show a nominal composition near the desired one for M=Na sample where as some vacancies are present in the A-site in the case of Ag substitution as will be discussed in this paper.

  6. Activation of NTS A(1) adenosine receptors inhibits regional sympathetic responses evoked by activation of cardiopulmonary chemoreflex.

    PubMed

    Ichinose, Tomoko K; Minic, Zeljka; Li, Cailian; O'Leary, Donal S; Scislo, Tadeusz J

    2012-09-01

    Previously we have shown that adenosine operating via the A(1) receptor subtype may inhibit glutamatergic transmission in the baroreflex arc within the nucleus of the solitary tract (NTS) and differentially increase renal (RSNA), preganglionic adrenal (pre-ASNA), and lumbar (LSNA) sympathetic nerve activity (ASNA>RSNA≥LSNA). Since the cardiopulmonary chemoreflex and the arterial baroreflex are mediated via similar medullary pathways, and glutamate is a primary transmitter in both pathways, it is likely that adenosine operating via A(1) receptors in the NTS may differentially inhibit regional sympathetic responses evoked by activation of cardiopulmonary chemoreceptors. Therefore, in urethane-chloralose-anesthetized rats (n = 37) we compared regional sympathoinhibition evoked by the cardiopulmonary chemoreflex (activated with right atrial injections of serotonin 5HT(3) receptor agonist phenylbiguanide, PBG, 1-8 μg/kg) before and after selective stimulation of NTS A(1) adenosine receptors [microinjections of N(6)-cyclopentyl adenosine (CPA), 0.033-330 pmol/50 nl]. Activation of cardiopulmonary chemoreceptors evoked differential, dose-dependent sympathoinhibition (RSNA>ASNA>LSNA), and decreases in arterial pressure and heart rate. These differential sympathetic responses were uniformly attenuated in dose-dependent manner by microinjections of CPA into the NTS. Volume control (n = 11) and blockade of adenosine receptor subtypes in the NTS via 8-(p-sulfophenyl)theophylline (8-SPT, 1 nmol in 100 nl) (n = 9) did not affect the reflex responses. We conclude that activation of NTS A(1) adenosine receptors uniformly inhibits neural and cardiovascular cardiopulmonary chemoreflex responses. A(1) adenosine receptors have no tonic modulatory effect on this reflex under normal conditions. However, when adenosine is released into the NTS (i.e., during stress or severe hypotension/ischemia), it may serve as negative feedback regulator for depressor and sympathoinhibitory reflexes

  7. Effects of adenosine infusion into renal interstitium on renal hemodynamics

    SciTech Connect

    Pawlowska, D.; Granger, J.P.; Knox, F.G.

    1987-04-01

    This study was designed to investigate the hemodynamic effects of exogenous adenosine in the interstitium of the rat kidney. Adenosine or its analogues were infused into the renal interstitium by means of chronically implanted capsules. In fusion of adenosine decreased glomerular filtration rate (GFR) from 0.81 +/- 0.06 to 0.37 +/- 0.06 ml/min while having no effect on renal blood flow (RBF). The metabolically stable analogue, 2-chloradenosine (2-ClAdo), decreased GFR from 0.73 +/- 0.07 to 021 +/- 0.06 ml/min. Interstitial infusion of theophylline, an adenosine receptor antagonist, completely abolished the effects of adenosine and 2-ClAdo on GFR. The distribution of adenosine, when infused into the renal interstitium, was determined using radiolabeled 5'-(N-ethyl)-carboxamidoadenosine (NECA), a metabolically stable adenosine agonist. After continuous infusion, (/sup 3/H)NECA was distributed throughout the kidney. The effects of NECA to reduce GFR were similar to those of adenosine and 2-ClAdo. They conclude that increased levels of adenosine in the renal interstitium markedly decrease GFR without affecting RBF in steady-state conditions. The marked effects of adenosine agonists during their infusion into the renal interstitium and the complete blockade of these effects by theophylline suggest an extracellular action of adenosine.

  8. Comparison of Hemodynamic Effects and Negative Predictive Value of Normal Adenosine Gated Myocardial Perfusion Scan With or Without Caffeine Abstinence.

    PubMed

    Uz Zaman, Maseeh; Fatima, Nosheen; Zaman, Areeba; Zaman, Unaiza; Tahseen, Rabia

    2016-09-01

    For vasodilator stress, myocardial perfusion imaging (MPI) with at least 12-h caffeine abstinence is recommended, as it attenuates cardiovascular hyperemic response of adenosine and dipyridamole. However, many published conflicting results have shown no significant effect upon perfusion abnormalities in MPI performed without caffeine abstinence. The aim of this study was to compare the hemodynamic changes and negative predictive value (NPV) of normal MPIs with adenosine stress performed with or without caffeine abstinence. This was a prospective study that accrued 50 patients from May 2013 till September 2013 and followed till November 2014. These patients had a normal adenosine-gated MPI (GMPI) with technetium-99m methoxy isobutyl isonitrile ((99m)Tc-MIBI) after 12-h caffeine abstinence (no-caffeine). Next day, all patients had a repeat adenosine stress within 60 min after ingestion of a cup of coffee (about 80 mg of caffeine) followed by no MPI in 30 patients due to concern about radiation dose (prior-caffeine adenosine-no MPI; group A). Twenty patients opted for a repeat MPI (prior-caffeine adenosine-MPI; group B). Adenosine-induced hemodynamic response and NPV of the normal MPI with no-caffeine and prior-caffeine protocols were compared. The mean age of the study cohort was 57 ± 9 years with a male-to-female ratio of 76:24% and mean body mass index (BMI) of 26.915 ± 4.121 kg/m(2). Prevalence of hypertension, diabetes, dyslipidemia, and positive family history were 76%, 20%, 22%, and 17%, respectively. Comparison of group A with group B revealed no significant difference in demographic parameters, hemodynamic or electrocardiography (ECG) parameters, or left ventricular (LV) function parameters during adenosine intervention with prior-caffeine and no-caffeine protocols. During the follow-up, no fatal myocardial infarction (MI) was reported but 6 nonfatal MIs were reported based upon the history of short hospitalization for chest pain but without biochemical or

  9. Adenosine-induced worsening of supraventricular tachycardia

    PubMed Central

    Kunnumpuram, Georgey Koshy; Patel, Ashfaq

    2012-01-01

    An approximately 20-year-old to 30-year-old patient presented with a haemodynamically stable supraventricular tachycardia . The patient was managed with intravenous adenosine primarily, with two bolus doses of 6 and 12 mg. This, however, caused a rare paradoxical surge of tachycardia with mild haemodynamic compromise. The patient further required a combination of Metoprolol and Verapamil administration to slow down and reverse the arrhythmia. Following this the patient remained stable with no further episodes till discharge. PMID:23230260

  10. Chemoelectrical energy conversion of adenosine triphosphate

    NASA Astrophysics Data System (ADS)

    Sundaresan, Vishnu Baba; Sarles, Stephen Andrew; Leo, Donald J.

    2007-04-01

    Plant and animal cell membranes transport charged species, neutral molecules and water through ion pumps and channels. The energy required for moving species against established concentration and charge gradients is provided by the biological fuel - adenosine triphosphate (ATP) -synthesized within the cell. The adenosine triphosphatase (ATPases) in a plant cell membrane hydrolyze ATP in the cell cytoplasm to pump protons across the cell membrane. This establishes a proton gradient across the membrane from the cell exterior into the cell cytoplasm. This proton motive force stimulates ion channels that transport nutrients and other species into the cell. This article discusses a device that converts the chemical energy stored in adenosine triphosphate into electrical power using a transporter protein, ATPase. The V-type ATPase proteins used in our prototype are extracted from red beet(Beta vulgaris) tonoplast membranes and reconstituted in a bilayer lipid membrane or BLM formed from POPC and POPS lipids. A pH7 medium that can support ATP hydrolysis is provided on both sides of the membrane and ATP is dissolved in the pH7 buffer on one side of the membrane. Hydrolysis of ATP results in the formation of a phosphate ion and adenosine diphosphate. The energy from the reaction activates ATPase in the BLM and moves a proton across the membrane. The charge gradient established across the BLM due to the reaction and ion transport is converted into electrical current by half-cell reference electrodes. The prototype ATPase cell with an effective BLM area of 4.15 mm2 carrying 15 μl of ATPase proteins was observed to develop a steady state peak power output of 70 nW, which corresponds to a specific power of 1.69 μW/cm2 and a current density of 43.4 μA/cm2 of membrane area.

  11. Effect of adenosine and adenosine analogs on ( sup 14 C)aminopyrine accumulation by rabbit parietal cells

    SciTech Connect

    Ota, S.; Hiraishi, H.; Terano, A.; Mutoh, H.; Kurachi, Y.; Shimada, T.; Ivey, K.J.; Sugimoto, T. )

    1989-12-01

    Adenosine receptors that modulate adenylate cyclase activity have been identified recently in a number of tissues. Adenosine A2 receptor is stimulatory to adenylate cyclase, whereas adenosine A1 receptor is inhibitory to adenylate cyclase. We investigated the effect of adenosine and its analogs on (14C)aminopyrine accumulation by rabbit parietal cells. Rabbit gastric mucosal cells were isolated by enzyme digestion. Parietal cells were enriched by nonlinear percoll gradients. (14C)Aminopyrine accumulation was used as an indicator of acid secretion. The effect of 2-chloroadenosine on histamine-stimulated (14C)aminopyrine accumulation was studied. The effects of N-ethylcarboxamideadenosine, 2-chloroadenosine, stable analogs of adenosine, and adenosine on (14C)aminopyrine accumulation were assessed. Cyclic AMP content of parietal cells was determined by radioimmunoassay. Histamine and carbachol, known secretagogues, stimulated (14C)aminopyrine accumulation. 2-Chloroadenosine did not suppress histamine-stimulated (14C)aminopyrine accumulation. 2-Chloroadenosine, N-ethylcarboxamideadenosine, and adenosine dose dependently increased (14C)aminopyrine accumulation. The order of potency was N-ethylcarboxamideadenosine greater than 2-chloroadenosine greater than adenosine. 8-Phenyltheophylline and theophylline, adenosine-receptor antagonists, or cimetidine did not have significant effects on the increase of AP uptake induced by 2-chloroadenosine. Coadministration of dipyridamole, and adenosine uptake inhibitor, augmented the effect of adenosine on (14C)aminopyrine accumulation. 2-Chloroadenosine, N-ethylcarboxamideadenosine, and adenosine each induced a significant increase in cellular cyclic AMP. We conclude that there may be adenosine A2 receptors on rabbit parietal cells which modulate gastric acid secretion.

  12. N6-(2-Hydroxyethyl)-Adenosine Exhibits Insecticidal Activity against Plutella xylostella via Adenosine Receptors

    PubMed Central

    Fang, Ming; Chai, Yiqiu; Chen, Guanjv; Wang, Huidong; Huang, Bo

    2016-01-01

    The diamondback moth, Plutella xylostella, is one of the most important pests of cruciferous crops. We have earlier shown that N6-(2-hydroxyethyl)-adenosine (HEA) exhibits insecticidal activity against P. xylostella. In the present study we investigated the possible mechanism of insecticidal action of HEA on P. xylostella. HEA is a derivative of adenosine, therefore, we speculated whether it acts via P. xylostella adenosine receptor (PxAdoR). We used RNAi approach to silence PxAdoR gene and used antagonist of denosine receptor (AdoR) to study the insecticidal effect of HEA. We cloned the whole sequence of PxAdoR gene. A BLAST search using NCBI protein database showed a 61% identity with the Drosophila adenosine receptor (DmAdoR) and a 32–35% identity with human AdoR. Though the amino acids sequence of PxAdoR was different compared to other adenosine receptors, most of the amino acids that are known to be important for adenosine receptor ligand binding and signaling were present. However, only 30% binding sites key residues was similar between PxAdoR and A1R. HEA, at a dose of 1 mg/mL, was found to be lethal to the second-instar larvae of P. xylostella, and a significant reduction of mortality and growth inhibition ratio were obtained when HEA was administered to the larvae along with PxAdoR-dsRNA or antagonist of AdoR (SCH58261) for 36, 48, or 60 h. Especially at 48 h, the rate of growth inhibition of the PxAdoR knockdown group was 3.5-fold less than that of the HEA group, and the corrected mortality of SCH58261 group was reduced almost 2-fold compared with the HEA group. Our findings show that HEA may exert its insecticidal activity against P. xylostella larvae via acting on PxAdoR. PMID:27668428

  13. Measurement of plasma adenosine concentration: methodological and physiological considerations

    SciTech Connect

    Gewirtz, H.; Brown, P.; Most, A.S.

    1987-05-01

    This study tested the hypothesis that measurements of plasma adenosine concentration made on samples of blood obtained in dipyridamole and EHNA (i.e., stopping solution) may be falsely elevated as a result of ongoing in vitro production and accumulation of adenosine during sample processing. Studies were performed with samples of anticoagulated blood obtained from anesthesized domestic swine. Adenosine concentration of ultra filtrated plasma was determined by HPLC. The following parameters were evaluated: (i) rate of clearance of (/sup 3/H)adenosine added to plasma, (ii) endogenous adenosine concentration of matched blood samples obtained in stopping solution alone, stopping solution plus EDTA, and perchloric acid (PCA), (iii) plasma and erythrocyte endogenous adenosine concentration in nonhemolyzed samples, and (iv) plasma adenosine concentration of samples hemolyzed in the presence of stopping solution alone or stopping solution plus EDTA. We observed that (i) greater than or equal to 95% of (/sup 3/H)adenosine added to plasma is removed from it by formed elements of the blood in less than 20 s, (ii) plasma adenosine concentration of samples obtained in stopping solution alone is generally 10-fold greater than that of matched samples obtained in stopping solution plus EDTA, (iii) deliberate mechanical hemolysis of blood samples obtained in stopping solution alone resulted in substantial augmentation of plasma adenosine levels in comparison with matched nonhemolyzed specimens--addition of EDTA to stopping solution prevented this, and (iv) adenosine content of blood samples obtained in PCA agreed closely with the sum of plasma and erythrocyte adenosine content of samples obtained in stopping solution plus EDTA.

  14. Role of adenosine receptor subtypes in methamphetamine reward and reinforcement.

    PubMed

    Kavanagh, Kevin A; Schreiner, Drew C; Levis, Sophia C; O'Neill, Casey E; Bachtell, Ryan K

    2015-02-01

    The neurobiology of methamphetamine (MA) remains largely unknown despite its high abuse liability. The present series of studies explored the role of adenosine receptors on MA reward and reinforcement and identified alterations in the expression of adenosine receptors in dopamine terminal areas following MA administration in rats. We tested whether stimulating adenosine A1 or A2A receptor subtypes would influence MA-induced place preference or MA self-administration on fixed and progressive ratio schedules in male Sprague-Dawley rats. Stimulation of either adenosine A1 or A2A receptors significantly reduced the development of MA-induced place preference. Stimulating adenosine A1, but not A2A, receptors reduced MA self-administration responding. We next tested whether repeated experimenter-delivered MA administration would alter the expression of adenosine receptors in the striatal areas using immunoblotting. We observed no change in the expression of adenosine receptors. Lastly, rats were trained to self-administer MA or saline for 14 days and we detected changes in adenosine A1 and A2A receptor expression using immunoblotting. MA self-administration significantly increased adenosine A1 in the nucleus accumbens shell, caudate-putamen and prefrontal cortex. MA self-administration significantly decreased adenosine A2A receptor expression in the nucleus accumbens shell, but increased A2A receptor expression in the amygdala. These findings demonstrate that MA self-administration produces selective alterations in adenosine receptor expression in the nucleus accumbens shell and that stimulation of adenosine receptors reduces several behavioral indices of MA addiction. Together, these studies shed light onto the neurobiological alterations incurred through chronic MA use that may aid in the development of treatments for MA addiction.

  15. Caffeine intensifies taste of certain sweeteners: role of adenosine receptor.

    PubMed

    Schiffman, S S; Diaz, C; Beeker, T G

    1986-03-01

    Caffeine, a potent antagonist of adenosine receptors, potentiates the taste of some but not all sweeteners. It significantly enhances the taste of acesulfam-K, neohesperidin dihydrochalcone, d-tryptophan, thaumatin, stevioside, and sodium saccharin. Adenosine reverses the enhancement. Caffeine has no effect on aspartame, sucrose, fructose, and calcium cyclamate. These results suggest that the inhibitory A1 adenosine receptor plays an important local role in modulating the taste intensity of certain sweeteners and that several transduction mechanisms mediate sweet taste.

  16. A Metabolic Immune Checkpoint: Adenosine in Tumor Microenvironment.

    PubMed

    Ohta, Akio

    2016-01-01

    Within tumors, some areas are less oxygenated than others. Since their home ground is under chronic hypoxia, tumor cells adapt to this condition by activating aerobic glycolysis; however, this hypoxic environment is very harsh for incoming immune cells. Deprivation of oxygen limits availability of energy sources and induces accumulation of extracellular adenosine in tumors. Extracellular adenosine, upon binding with adenosine receptors on the surface of various immune cells, suppresses pro-inflammatory activities. In addition, signaling through adenosine receptors upregulates a number of anti-inflammatory molecules and immunoregulatory cells, leading to the establishment of a long-lasting immunosuppressive environment. Thus, due to hypoxia and adenosine, tumors can discourage antitumor immune responses no matter how the response was induced, whether it was spontaneous or artificially introduced with a therapeutic intention. Preclinical studies have shown the significance of adenosine in tumor survival strategy by demonstrating tumor regression after inactivation of adenosine receptors, inhibition of adenosine-producing enzymes, or reversal of tissue hypoxia. These promising results indicate a potential use of the inhibitors of the hypoxia-adenosine pathway for cancer immunotherapy. PMID:27066002

  17. Adenosine analogs inhibit fighting in isolated male mice

    SciTech Connect

    Palmour, R.M.; Lipowski, C.J.; Simon, C.K.; Ervin, F.R.

    1989-01-01

    The potent adenosine analogs N-ethylcarboxamide adenosine (NECA) and phenylisopropyladenosine (PIA) inhibit fighting and associated agonistic behaviors in isolated male mice. These effects are reversed by methylxanthines; moderate doses of NECA which inhibit fighting have minimal effects on spontaneous locomotor activity. At very low doses, both NECA and PIA increase fighting in parallel with previously reported increases of motor activity. Brain levels of (/sup 3/H)-NECA and (/sup 3/H)-PIA achieved at behaviorally effective doses suggest an involvement of adenosine receptors. The biochemical mechanism of adenosine receptor action with respect to fighting is unknown, but may include neuromodulatory effects on the release of other, more classical neurotransmitters.

  18. Adenosine signaling: good or bad in erectile function?

    PubMed

    Wen, Jiaming; Xia, Yang

    2012-04-01

    The erectile status of penile tissue is governed largely by the tone of cavernosal smooth muscle cells, which is determined by the balance of vascular relaxants and constrictors. Vascular relaxants play a key role in regulating the tone of cavernosal smooth muscle and thus the initiation and maintenance of penile erection. Early studies drew attention to the potential role of adenosine signaling in this process. However, the serendipitous discovery of the effect of sildenafil on erectile physiology drew more attention toward nitric oxide (NO) as a vasodilator in the process of penile erection, and a recently discovered, unexpected erectile phenotype of adenosine deaminase-deficient mice reemphasizes the importance of adenosine as a key regulatory of erectile status. Adenosine, like NO, is a potent and short-lived vasorelaxant that functions via cyclic nucleotide second messenger signaling to promote smooth muscle relaxation. Recent studies reviewed here show that adenosine functions to relax the corpus cavernosum and promote penile erection. Excess adenosine in penile tissue contributes to the disorder called priapism, and impaired adenosine signaling is associated with erectile dysfunction. More recent research summarized in this review reveals that adenosine functions as a key endogenous vasodilator in the initiation and maintenance of normal penile erection. This new insight highlights adenosine signaling pathways operating in penile tissue as significant therapeutic targets for the treatment of erectile disorders.

  19. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... device that measures the release of adenosine triphosphate (ATP) from platelets following aggregation.... Simultaneous measurements of platelet aggregation and ATP release are used to evaluate platelet...

  20. Interplay between orfamides, sessilins and phenazines in the control of Rhizoctonia diseases by Pseudomonas sp. CMR12a.

    PubMed

    Olorunleke, Feyisara Eyiwumi; Hua, Gia Khuong Hoang; Kieu, Nam Phuong; Ma, Zongwang; Höfte, Monica

    2015-10-01

    We investigated the role of phenazines and cyclic lipopeptides (CLPs) (orfamides and sessilins), antagonistic metabolites produced by Pseudomonas sp. CMR12a, in the biological control of damping-off disease on Chinese cabbage (Brassica chinensis) caused by Rhizoctonia solani AG 2-1 and root rot disease on bean (Phaseolus vulgaris L.) caused by R. solani AG 4-HGI. A Pseudomonas mutant that only produced phenazines suppressed damping-off disease on Chinese cabbage to the same extent as CMR12a, while its efficacy to reduce root rot on bean was strongly impaired. In both pathosystems, the phenazine mutant that produced both CLPs was equally effective, but mutants that produced only one CLP lost biocontrol activity. In vitro microscopic assays revealed that mutants that only produced sessilins or orfamides inhibited mycelial growth of R. solani when applied together, while they were ineffective on their own. Phenazine-1-carboxamide suppressed mycelial growth of R. solani AG 2-1 but had no effect on AG 4-HGI. Orfamide B suppressed mycelial growth of both R. solani anastomosis groups in a dose-dependent way. Our results point to an additive interaction between both CLPs. Moreover, phenazines alone are sufficient to suppress Rhizoctonia disease on Chinese cabbage, while they need to work in tandem with the CLPs on bean.

  1. Adenosine signaling in normal and sickle erythrocytes and beyond

    PubMed Central

    Zhang, Yujin; Xia, Yang

    2012-01-01

    Sickle cell disease (SCD) is a debilitating hemolytic genetic disorder with high morbidity and mortality affecting millions of individuals worldwide. Although SCD was discovered more than a century ago, no effective mechanism-based prevention and treatment are available due to poorly understood molecular basis of sickling, the fundamental pathogenic process of the disease. SCD patients constantly face hypoxia. One of the best-known signaling molecules to be induced under hypoxic conditions is adenosine. Recent studies demonstrate that hypoxia-mediated elevated adenosine signaling plays an important role in normal erythrocyte physiology. In contrast, elevated adenosine signaling contributes to sickling and multiple life threatening complications including tissue damage, pulmonary dysfunction and priapism. Here, we summarize recent research on the role of adenosine signaling in normal and sickle erythrocytes, progression of the disease and therapeutic implications. In normal erythrocytes, both genetic and pharmacological studies demonstrate that adenosine can enhance 2,3-bisphosphoglycerate (2,3-BPG) production via A2B receptor (ADORA2B) activation, suggesting that elevated adenosine has an unrecognized role in normal erythrocytes to promote O2 release and prevent acute ischemic tissue injury. However, in sickle erythrocytes, the beneficial role of excessive adenosine-mediated 2,3-BPG induction becomes detrimental by promoting deoxygenation, polymerization of sickle hemoglobin and subsequent sickling. Additionally, adenosine signaling via the A2A receptor (ADORA2A) on invariant natural killer T (iNKT) cells inhibits iNKT cell activation and attenuates pulmonary dysfunction in SCD mice. Finally, elevated adenosine coupled with ADORA2BR activation is responsible for priapism, a dangerous complication seen in SCD. Overall, the research reviewed here reveals a differential role of elevated adenosine in normal erythrocytes, sickle erythrocytes, iNK cells and progression

  2. Characterization of adenosine binding proteins in human placental membranes

    SciTech Connect

    Hutchison, K.A.

    1989-01-01

    We have characterized two adenosine binding proteins in human placenta. In membranes, one site is detected with ({sup 3}H) -N-ethylcarboxamidoadenosine (({sup 3}H)NECA). This site is similar to the adenosine A{sub 2} receptor. We call this site the adenosine A{sub 2}-like binding site. In detergent extracts, the second site is detected and has the characteristics of an adenosine A{sub 1} receptor. The soluble adenosine A{sub 2}-like binding site cannot be detected without a rapid assay. Binding to the adenosine A{sub 1} receptor with ({sup 3}H)-2-chloroadenosine and ({sup 3}H)NECA is time dependent, saturable, and reversible. Equilibrium displacement analysis with adenosine agonists reveals an A{sub 1} specificity: 2-chloroadenosine > R-phenylisopropyladenosine > 5{prime}-N-ethylcarboxamidoadenosine. The antagonist potency order is 1,3-diethyl-8-phenylxanthine > isobutylmethylxanthine > theophylline. Competition analysis of membranes with the A,-selective ligands ({sup 3}H)-cyclohexyladenosine ({sup 3}H) cylopentylxanthine revealed adenosine A{sub 1} agonist and antagonist potency orders. We have purified the adenosine A{sub 2}-like binding site. The adenosine A{sub 2}-like binding site is an ubiquitous major cellular protein. It is glycosylated, highly asymmetric, and acidic. The native protein is an homodimer with a subunit molecular mass of 98 kDa. The sedimentation coefficient and partial specific volume of the binding complex are 6.9 s and 0.698 ml/g, respectively. The Stokes' radius is 70 {Angstrom}. The native molecular mass of the detergent-protein complex is 230 kDa. The adenosine A{sub 2}-like binding site has an agonist potency order of 5'-N-ethylcarboxamidoadenosine > 2-chloroadenosine >> R-phenylisopropyladenosine and an antagonist potency order of isobutylmethylxanthine > theophylline >> 1,3-diethyl-8-phenylxanthine.

  3. cAMP-independent dilation of coronary arterioles to adenosine : role of nitric oxide, G proteins, and K(ATP) channels.

    PubMed

    Hein, T W; Kuo, L

    1999-10-01

    Adenosine is known to play an important role in the regulation of coronary blood flow during metabolic stress. However, there is sparse information on the mechanism of adenosine-induced dilation at the microcirculatory levels. In the present study, we examined the role of endothelial nitric oxide (NO), G proteins, cyclic nucleotides, and potassium channels in coronary arteriolar dilation to adenosine. Pig subepicardial coronary arterioles (50 to 100 microm in diameter) were isolated, cannulated, and pressurized to 60 cm H(2)O without flow for in vitro study. The arterioles developed basal tone and dilated dose dependently to adenosine. Disruption of endothelium, blocking of endothelial ATP-sensitive potassium (K(ATP)) channels by glibenclamide, and inhibition of NO synthase by N(G)-nitro-L-arginine methyl ester and of soluble guanylyl cyclase by 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one produced identical attenuation of vasodilation to adenosine. Combined administration of these inhibitors did not further attenuate the vasodilatory response. Production of NO from coronary arterioles was significantly increased by adenosine. Pertussis toxin, but not cholera toxin, significantly inhibited vasodilation to adenosine, and this inhibitory effect was only evident in vessels with an intact endothelium. Tetraethylammonium, glibenclamide, and a high concentration of extraluminal KCl abolished vasodilation of denuded vessels to adenosine; however, inhibition of calcium-activated potassium channels by iberiotoxin had no effect on this dilation. Rp-8-Br-cAMPS, a cAMP antagonist, inhibited vasodilation to cAMP analog 8-Br-cAMP but failed to block adenosine-induced dilation. Furthermore, vasodilations to 8-Br-cAMP and sodium nitroprusside were not inhibited by glibenclamide, indicating that cAMP- and cGMP-induced dilations are not mediated by the activation of K(ATP) channels. These results suggest that adenosine activates both endothelial and smooth muscle pathways to exert

  4. Norepinephrines effect on adenosine transport in the proximal straight tubule

    SciTech Connect

    Barfuss, D.W.; McCann, W.P.; Katholi, R.E.

    1986-03-01

    The effect of norepinephrine on C/sup 14/-adenosine transport in the rabbit proximal tubule (S/sub 2/) was studied. The transepithelial transport of adenosine (0.02 mM0 from lumin to bathing solution was measured by its rate of appearance (J/sub A/) in the bathing solution and by its disappearances (J/sub D/) from the luminal fluid. Norepinephrine (0.24 ..mu..M) was added to the bathing solution after a control flux period. After three samples from the experiment period the tubules were quickly harvested and the cellular concentration of C/sup 14/-adenosine was determined. The high cellular adenosine concentration and th marked difference in adenosine appearance rate in the bathing solution compared to the luminal disappearance rate indicates the absorbed adenosine is trapped in the cells. This trapping may be due to adenosine metabolism or difficulty of crossing the basolateral membrane. Whichever is the case, norepinephrine appears to stimulate movement of adenosine or its metabolites into the bathing solution across the basolateral membrane.

  5. Comorbidities in Neurology: Is Adenosine the Common Link?

    PubMed Central

    Boison, Detlev; Aronica, Eleonora

    2015-01-01

    Comorbidities in Neurology represent a major conceptual and therapeutic challenge. For example, temporal lobe epilepsy (TLE) is a syndrome comprised of epileptic seizures and comorbid symptoms including memory and psychiatric impairment, depression, and sleep dysfunction. Similarly, Alzheimer’s disease (AD), Parkinson’s disease (PD), and Amyotrophic Lateral Sclerosis (ALS) are accompanied by various degrees of memory dysfunction. Patients with AD have an increased likelihood for seizures, whereas all four conditions share certain aspects of psychosis, depression, and sleep dysfunction. This remarkable overlap suggests common pathophysiological mechanisms, which include synaptic dysfunction and synaptotoxicity, as well as glial activation and astrogliosis. Astrogliosis is linked to synapse function via the tripartite synapse, but astrocytes also control the availability of gliotransmitters and adenosine. Here we will specifically focus on the ‘adenosine hypothesis of comorbidities’ implying that astrocyte activation, via overexpression of adenosine kinase (ADK), induces a deficiency in the homeostatic tone of adenosine. We present evidence from patient-derived samples showing astrogliosis and overexpression of ADK as common pathological hallmark of epilepsy, AD, PD, and ALS. We discuss a transgenic ‘comorbidity model’, in which brain-wide overexpression of ADK and resulting adenosine deficiency produces a comorbid spectrum of seizures, altered dopaminergic function, attentional impairment, and deficits in cognitive domains and sleep regulation. We conclude that dysfunction of adenosine signaling is common in neurological conditions, that adenosine dysfunction can explain comorbid phenotypes, and that therapeutic adenosine augmentation might be effective for the treatment of comorbid symptoms in multiple neurological conditions. PMID:25979489

  6. Effect of theophylline on adenosine production in the canine myocardium

    SciTech Connect

    McKenzie, J.E.; Steffen, R.P.; Haddy, F.J.

    1987-01-01

    Adenosine is thought to participate in local regulation of coronary blood flow. However, competitive antagonists of adenosine fail to block myocardial active hyperemia. The authors examined the effect of locally administered theophylline on active hyperemia and myocardial adenosine production during intracoronary isoproterenol infusion in the dog heart. Isoproterenol decreased coronary resistance and increased myocardial adenosine production. Infusion of theophylline at a rate that attenuated the vasodilator response to exogenously administered adenosine failed to attenuate the increase in coronary blood flow produced by isoproterenol. However, theophylline plus isoproterenol production greater increases in myocardial adensine production than isoproterenol alone. The curves relating resistance and adenosine in the presence of theophylline fell to the right of those in the absence of theophylline. These findings suggest that the failure of theophylline to attenuate isoproterenol hyperemia in the dog heart results at least in part from an increase in adenosine concentration at the arteriole to a level beyond that blocked by this competitive antagonist and that adenosine may in fact play a role in isoproterenol-induced active hyperemia.

  7. A2B adenosine receptor contributes to penile erection via PI3K/AKT signaling cascade-mediated eNOS activation

    PubMed Central

    Wen, Jiaming; Grenz, Almut; Zhang, Yujin; Dai, Yingbo; Kellems, Rodney E.; Blackburn, Michael R.; Eltzschig, Holger K.; Xia, Yang

    2011-01-01

    Normal penile erection is under the control of multiple factors and signaling pathways. Although adenosine signaling is implicated in normal and abnormal penile erection, the exact role and the underlying mechanism for adenosine signaling in penile physiology remain elusive. Here we report that shear stress leads to increased adenosine release from endothelial cells. Subsequently, we determined that ecto-5′-nucleotidase (CD73) is a key enzyme required for the production of elevated adenosine from ATP released by shear-stressed endothelial cells. Mechanistically, we demonstrate that shear stress-mediated elevated adenosine functions through the adenosine A2B receptor (A2BR) to activate the PI3K/AKT signaling cascade and subsequent increased endothelial nitric oxide synthase (eNOS) phosphorylation. These in vitro studies led us to discover further that adenosine was induced during sustained penile erection and contributes to PI3K/AKT activation and subsequent eNOS phosphorylation via A2BR signaling in intact animal. Finally, we demonstrate that lowering adenosine in wild-type mice or genetic deletion of A2BR in mutant mice significantly attenuated PI3K/AKT activation, eNOS phosphorylation, and subsequent impaired penile erection featured with the reduction of ratio of maximal intracavernosal pressure to systemic arterial pressure from 0.49 ± 0.03 to 0.41 ± 0.05 and 0.38 ± 0.04, respectively (both P<0.05). Overall, using biochemical, cellular, genetic, and physiological approaches, our findings reveal that adenosine is a novel molecule signaling via A2BR activation, contributing to penile erection via PI3K/AKT-dependent eNOS activation. These studies suggest that this signaling pathway may be a novel therapeutic target for erectile disorders.—Wen, J., Grenz, A., Zhang, Y., Dai, Y., Kellems, R. E., Blackburn, M. R., Eltzschig, H. K., Xia, Y. A2B adenosine receptor contributes to penile erection via PI3K/AKT signaling cascade-mediated eNOS activation. PMID

  8. A High-Affinity Adenosine Kinase from Anopheles Gambiae

    SciTech Connect

    M Cassera; M Ho; E Merino; E Burgos; A Rinaldo-Matthis; S Almo; V Schramm

    2011-12-31

    Genome analysis revealed a mosquito orthologue of adenosine kinase in Anopheles gambiae (AgAK; the most important vector for the transmission of Plasmodium falciparum in Africa). P. falciparum are purine auxotrophs and do not express an adenosine kinase but rely on their hosts for purines. AgAK was kinetically characterized and found to have the highest affinity for adenosine (K{sub m} = 8.1 nM) of any known adenosine kinase. AgAK is specific for adenosine at the nucleoside site, but several nucleotide triphosphate phosphoryl donors are tolerated. The AgAK crystal structure with a bound bisubstrate analogue Ap{sub 4}A (2.0 {angstrom} resolution) reveals interactions for adenosine and ATP and the geometry for phosphoryl transfer. The polyphosphate charge is partly neutralized by a bound Mg{sup 2+} ion and an ion pair to a catalytic site Arg. The AgAK structure consists of a large catalytic core in a three-layer {alpha}/{beta}/{alpha} sandwich, and a small cap domain in contact with adenosine. The specificity and tight binding for adenosine arise from hydrogen bond interactions of Asn14, Leu16, Leu40, Leu133, Leu168, Phe168, and Thr171 and the backbone of Ile39 and Phe168 with the adenine ring as well as through hydrogen bond interactions between Asp18, Gly64, and Asn68 and the ribosyl 2'- and 3'-hydroxyl groups. The structure is more similar to that of human adenosine kinase (48% identical) than to that of AK from Toxoplasma gondii (31% identical). With this extraordinary affinity for AgAK, adenosine is efficiently captured and converted to AMP at near the diffusion limit, suggesting an important role for this enzyme in the maintenance of the adenine nucleotide pool. mRNA analysis verifies that AgAK transcripts are produced in the adult insects.

  9. Regional in vivo transit time measurements of aortic pulse wave velocity in mice with high-field CMR at 17.6 Tesla

    PubMed Central

    2010-01-01

    Background Transgenic mouse models are increasingly used to study the pathophysiology of human cardiovascular diseases. The aortic pulse wave velocity (PWV) is an indirect measure for vascular stiffness and a marker for cardiovascular risk. Results This study presents a cardiovascular magnetic resonance (CMR) transit time (TT) method that allows the determination of the PWV in the descending murine aorta by analyzing blood flow waveforms. Systolic flow pulses were recorded with a temporal resolution of 1 ms applying phase velocity encoding. In a first step, the CMR method was validated by pressure waveform measurements on a pulsatile elastic vessel phantom. In a second step, the CMR method was applied to measure PWVs in a group of five eight-month-old apolipoprotein E deficient (ApoE(-/-)) mice and an age matched group of four C57Bl/6J mice. The ApoE(-/-) group had a higher mean PWV (PWV = 3.0 ± 0.6 m/s) than the C57Bl/6J group (PWV = 2.4 ± 0.4 m/s). The difference was statistically significant (p = 0.014). Conclusions The findings of this study demonstrate that high field CMR is applicable to non-invasively determine and distinguish PWVs in the arterial system of healthy and diseased groups of mice. PMID:21134260

  10. Stress

    MedlinePlus

    ... hurt or killed. Examples include a major accident, war, assault, or a natural disaster. This type of ... stress, so you can avoid more serious health effects. NIH: National Institute of Mental Health

  11. Comparison of Hemodynamic Effects and Negative Predictive Value of Normal Adenosine Gated Myocardial Perfusion Scan With or Without Caffeine Abstinence

    PubMed Central

    uz Zaman, Maseeh; Fatima, Nosheen; Zaman, Areeba; Zaman, Unaiza; Tahseen, Rabia

    2016-01-01

    For vasodilator stress, myocardial perfusion imaging (MPI) with at least 12-h caffeine abstinence is recommended, as it attenuates cardiovascular hyperemic response of adenosine and dipyridamole. However, many published conflicting results have shown no significant effect upon perfusion abnormalities in MPI performed without caffeine abstinence. The aim of this study was to compare the hemodynamic changes and negative predictive value (NPV) of normal MPIs with adenosine stress performed with or without caffeine abstinence. This was a prospective study that accrued 50 patients from May 2013 till September 2013 and followed till November 2014. These patients had a normal adenosine-gated MPI (GMPI) with technetium-99m methoxy isobutyl isonitrile (99mTc-MIBI) after 12-h caffeine abstinence (no-caffeine). Next day, all patients had a repeat adenosine stress within 60 min after ingestion of a cup of coffee (about 80 mg of caffeine) followed by no MPI in 30 patients due to concern about radiation dose (prior-caffeine adenosine—no MPI; group A). Twenty patients opted for a repeat MPI (prior-caffeine adenosine—MPI; group B). Adenosine-induced hemodynamic response and NPV of the normal MPI with no-caffeine and prior-caffeine protocols were compared. The mean age of the study cohort was 57 ± 9 years with a male-to-female ratio of 76:24% and mean body mass index (BMI) of 26.915 ± 4.121 kg/m2. Prevalence of hypertension, diabetes, dyslipidemia, and positive family history were 76%, 20%, 22%, and 17%, respectively. Comparison of group A with group B revealed no significant difference in demographic parameters, hemodynamic or electrocardiography (ECG) parameters, or left ventricular (LV) function parameters during adenosine intervention with prior-caffeine and no-caffeine protocols. During the follow-up, no fatal myocardial infarction (MI) was reported but 6 nonfatal MIs were reported based upon the history of short hospitalization for chest pain but without biochemical or

  12. Comparison of Hemodynamic Effects and Negative Predictive Value of Normal Adenosine Gated Myocardial Perfusion Scan With or Without Caffeine Abstinence

    PubMed Central

    uz Zaman, Maseeh; Fatima, Nosheen; Zaman, Areeba; Zaman, Unaiza; Tahseen, Rabia

    2016-01-01

    For vasodilator stress, myocardial perfusion imaging (MPI) with at least 12-h caffeine abstinence is recommended, as it attenuates cardiovascular hyperemic response of adenosine and dipyridamole. However, many published conflicting results have shown no significant effect upon perfusion abnormalities in MPI performed without caffeine abstinence. The aim of this study was to compare the hemodynamic changes and negative predictive value (NPV) of normal MPIs with adenosine stress performed with or without caffeine abstinence. This was a prospective study that accrued 50 patients from May 2013 till September 2013 and followed till November 2014. These patients had a normal adenosine-gated MPI (GMPI) with technetium-99m methoxy isobutyl isonitrile (99mTc-MIBI) after 12-h caffeine abstinence (no-caffeine). Next day, all patients had a repeat adenosine stress within 60 min after ingestion of a cup of coffee (about 80 mg of caffeine) followed by no MPI in 30 patients due to concern about radiation dose (prior-caffeine adenosine—no MPI; group A). Twenty patients opted for a repeat MPI (prior-caffeine adenosine—MPI; group B). Adenosine-induced hemodynamic response and NPV of the normal MPI with no-caffeine and prior-caffeine protocols were compared. The mean age of the study cohort was 57 ± 9 years with a male-to-female ratio of 76:24% and mean body mass index (BMI) of 26.915 ± 4.121 kg/m2. Prevalence of hypertension, diabetes, dyslipidemia, and positive family history were 76%, 20%, 22%, and 17%, respectively. Comparison of group A with group B revealed no significant difference in demographic parameters, hemodynamic or electrocardiography (ECG) parameters, or left ventricular (LV) function parameters during adenosine intervention with prior-caffeine and no-caffeine protocols. During the follow-up, no fatal myocardial infarction (MI) was reported but 6 nonfatal MIs were reported based upon the history of short hospitalization for chest pain but without biochemical or

  13. Segmentation of scarred and non-scarred myocardium in LG enhanced CMR images using intensity-based textural analysis.

    PubMed

    Kotu, Lasya Priya; Engan, Kjersti; Eftestøl, Trygve; Ørn, Stein; Woie, Leik

    2011-01-01

    The Late Gadolinium (LG) enhancement in Cardiac Magnetic Resonance (CMR) imaging is used to increase the intensity of scarred area in myocardium for thorough examination. Automatic segmentation of scar is important because scar size is largely responsible in changing the size, shape and functioning of left ventricle and it is a preliminary step required in exploring the information present in scar. We have proposed a new technique to segment scar (infarct region) from non-scarred myocardium using intensity-based texture analysis. Our new technique uses dictionary-based texture features and dc-values to segment scarred and non-scarred myocardium using Maximum Likelihood Estimator (MLE) based Bayes classification. Texture analysis aided with intensity values gives better segmentation of scar from myocardium with high sensitivity and specificity values in comparison to manual segmentation by expert cardiologists.

  14. A quantitative comparison of regional myocardial motion in mice, rabbits and humans using in-vivo phase contrast CMR

    PubMed Central

    2012-01-01

    Background Genetically manipulated animals like mice or rabbits play an important role in the exploration of human cardiovascular diseases. It is therefore important to identify animal models that closely mimic physiological and pathological human cardiac function. Methods In-vivo phase contrast cardiovascular magnetic resonance (CMR) was used to measure regional three-directional left ventricular myocardial motion with high temporal resolution in mice (N=18), rabbits (N=8), and humans (N=20). Radial, long-axis, and rotational myocardial velocities were acquired in left ventricular basal, mid-ventricular, and apical short-axis locations. Results Regional analysis revealed different patterns of motion: 1) In humans and rabbits, the apex showed slower radial velocities compared to the base. 2) Significant differences within species were seen in the pattern of long-axis motion. Long-axis velocities during systole were fairly homogeneously distributed in mice, whereas humans showed a dominant component in the lateral wall and rabbits in the base. 3) Rotational velocities and twist showed the most distinct patterns in both temporal evolution and relative contribution of base, mid-ventricle and apex, respectively. Interestingly, a marked difference in rotational behavior during early-systole was found in mice, which exhibited clockwise rotation in all slice locations compared to counter-clockwise rotation in rabbits and humans. Conclusions Phase contrast CMR revealed subtle, but significantly different regional myocardial motion patterns in mice, rabbits and humans. This finding has to be considered when investigating myocardial motion pattern in small animal models of heart disease. PMID:23270566

  15. Quantification of myocardial perfusion using CMR with a radial data acquisition: comparison with a dual-bolus method

    PubMed Central

    2010-01-01

    Background Quantitative estimates of myocardial perfusion generally require accurate measurement of the arterial input function (AIF). The saturation of signal intensity in the blood that occurs with most doses of contrast agent makes obtaining an accurate AIF challenging. This work seeks to evaluate the performance of a method that uses a radial k-space perfusion sequence and multiple saturation recovery times (SRT) to quantify myocardial perfusion with cardiovascular magnetic resonance (CMR). Methods Perfusion CMR was performed at 3 Tesla with a saturation recovery radial turboFLASH sequence with 72 rays. Fourteen subjects were given a low dose (0.004 mmol/kg) of dilute (1/5 concentration) contrast agent (Gd-BOPTA) and then a higher non-dilute dose of the same volume (0.02 mmol/kg). AIFs were calculated from the blood signal in three sub-images with differing effective saturation recovery times. The full and sub-images were reconstructed iteratively with a total variation constraint. The images from the full 72 ray data were processed to obtain six tissue enhancement curves in two slices of the left ventricle in each subject. A 2-compartment model was used to determine absolute flows Results The proposed multi-SRT method resulted in AIFs that were similar to those obtained with the dual-bolus method. Myocardial blood flow (MBF) estimates from the dual-bolus and the multi-SRT methods were related by MBFmulti-SRT = 0.85MBFdual-bolus + 0.18 (r = 0.91). Conclusions The multi-SRT method, which uses a radial k-space perfusion sequence, can be used to obtain an accurate AIF and thus quantify myocardial perfusion for doses of contrast agent that result in a relatively saturated AIF. PMID:20653961

  16. Thoracic aortopathy in Turner syndrome and the influence of bicuspid aortic valves and blood pressure: a CMR study

    PubMed Central

    2010-01-01

    Background To investigate aortic dimensions in women with Turner syndrome (TS) in relation to aortic valve morphology, blood pressure, karyotype, and clinical characteristics. Methods and results A cross sectional study of 102 women with TS (mean age 37.7; 18-62 years) examined by cardiovascular magnetic resonance (CMR- successful in 95), echocardiography, and 24-hour ambulatory blood pressure. Aortic diameters were measured by CMR at 8 positions along the thoracic aorta. Twenty-four healthy females were recruited as controls. In TS, aortic dilatation was present at one or more positions in 22 (23%). Aortic diameter in women with TS and bicuspid aortic valve was significantly larger than in TS with tricuspid valves in both the ascending (32.4 ± 6.7 vs. 26.0 ± 4.4 mm; p < 0.001) and descending (21.4 ± 3.5 vs. 18.8 ± 2.4 mm; p < 0.001) aorta. Aortic diameter correlated to age (R = 0.2 - 0.5; p < 0.01), blood pressure (R = 0.4; p < 0.05), a history of coarctation (R = 0.3; p = 0.01) and bicuspid aortic valve (R = 0.2-0.5; p < 0.05). Body surface area only correlated with descending aortic diameter (R = 0.23; p = 0.024). Conclusions Aortic dilatation was present in 23% of adult TS women, where aortic valve morphology, age and blood pressure were major determinants of the aortic diameter. PMID:20222980

  17. Apparatus for nonresonant rf power absorption studies in high Tc superconductors and CMR materials using rf oscillators

    NASA Astrophysics Data System (ADS)

    Sarangi, S.; Bhat, S. V.

    2005-02-01

    The design, fabication, and performance of an apparatus for measurement of nonresonant rf power absorption (NRRA) in superconducting and CMR samples are described. The system consists of an effective self-resonant LC tank circuit driven by a NOT gate (Logic gate). The samples under investigation are placed in the core of an inductive coil and nonresonant power absorption is determined from the measured shift in total current supplies to the whole oscillator circuit. A customized low temperature insert is used to integrate the experiment with a commercial oxford cryostat and temperature controller. The system makes use of a sensitive digital multimeter (Keithley 2002 model) and is capable of measuring NRRA in superconducting and colossal magnetoresistance samples of volume as small as 1×10-3cm3 with a signal to noise ratio of 10. Further increase in the sensitivity of the experimental setup can be obtained by summing the results of repeated measurements obtained in the same temperature interval. The system has been tested for an IC 74LS04 oscillator at frequencies between 1MHz and 25MHz in the temperature range from 4.2Kto400K and in magnetic field from 0to1.4T. The system performance is evaluated by measuring the NRRA in YBa2Cu3O7 (YBCO) superconducting sample and La0.7Sr0.3MnO3 (LSMO) colossal magnetoresistive (CMR) manganite samples at different rf frequencies. During a measurement all operation are controlled automatically by computer from a menu-driven software system, with user input required only on initiation of measurement sequence.

  18. Identification of the heart as the critical site of adenosine mediated embryo protection

    PubMed Central

    2010-01-01

    Background Our understanding of the mechanisms that protect the developing embryo from intrauterine stress is limited. Recently, adenosine has been demonstrated to play a critical role in protecting the embryo against hypoxia via adenosine A1 receptors (A1ARs), which are expressed in the heart, nervous system, and other sites during development. However, the sites of A1AR action that mediate embryo protection are not known. To determine if the heart is a key site of adenosine-mediated embryo protection, A1ARs were selectively deleted in the embryonic heart using a Cre-LoxP system in which the alpha-myosin heavy chain promoter drives Cre-recombinase expression and excision of the A1AR gene from cardiomyocytes. Results With increasing exposure of maternal hypoxia (10% O2) from 48-96 hours beginning at embryonic day (E) 8.5, embryo viability decreased in the cardiac-A1AR deleted embryos. 48 hours of hypoxia reduced embryonic viability by 49% in embryos exposed from E10.5-12.5 but no effect on viability was observed in younger embryos exposed to hypoxia from E8.5-10.5. After 72 hours of hypoxia, 57.8% of the cardiac-A1AR deleted embryos were either dead or re-absorbed compared to 13.7% of control littermates and after 96 hours 81.6% of cardiac-A1AR deleted embryos were dead or re-absorbed. After 72 hours of hypoxia, cardiac size was reduced significantly more in the cardiac-A1AR deleted hearts compared to controls. Gene expression analysis revealed clusters of genes that are regulated by both hypoxia and A1AR expression. Conclusions These data identify the embryonic heart as the critical site where adenosine acts to protect the embryo against hypoxia. As such these studies identify a previously unrecognized mechanism of embryo protection. PMID:20509906

  19. Serum adenosine deaminase activity in cutaneous anthrax

    PubMed Central

    Sunnetcioglu, Mahmut; Karadas, Sevdegul; Aslan, Mehmet; Ceylan, Mehmet Resat; Demir, Halit; Oncu, Mehmet Resit; Karahocagil, Mustafa Kasım; Sunnetcioglu, Aysel; Aypak, Cenk

    2014-01-01

    Background Adenosine deaminase (ADA) activity has been discovered in several inflammatory conditions; however, there are no data associated with cutaneous anthrax. The aim of this study was to investigate serum ADA activity in patients with cutaneous anthrax. Material/Methods Sixteen patients with cutaneous anthrax and 17 healthy controls were enrolled. We measured ADA activity; peripheral blood leukocyte, lymphocyte, neutrophil, and monocyte counts; erythrocyte sedimentation rate; and C reactive protein levels. Results Serum ADA activity was significantly higher in patients with cutaneous anthrax than in the controls (p<0.001). A positive correlation was observed between ADA activity and lymphocyte counts (r=0.589, p=0.021) in the patient group. Conclusions This study suggests that serum ADA could be used as a biochemical marker in cutaneous anthrax. PMID:24997584

  20. Ethanol Tolerance Affects Endogenous Adenosine Signaling in Mouse Hippocampus.

    PubMed

    Zhang, Dali; Xiong, Wei; Jackson, Michael F; Parkinson, Fiona E

    2016-07-01

    Ethanol has many pharmacological effects, including increases in endogenous adenosine levels and adenosine receptor activity in brain. Ethanol consumption is associated with both positive and negative health outcomes, but tolerance to the behavioral effects of ethanol can lead to increased consumption, which increases the risk of negative health outcomes. The present study was performed to test whether a 7-day treatment with ethanol is linked to reduced adenosine signaling and whether this is a consequence of reduced ecto-5'-nucleotidase activity. Wild-type (CD73(+/+)) and ecto-5'-nucleotidase-deficient (CD73(-/-)) mice were treated with ethanol (2 g/kg) or saline for 7 days. In CD73(+/+) mice, repeated ethanol treatment reduced the hypothermic and ataxic effects of acute ethanol, indicating the development of tolerance to the acute effects of ethanol. In CD73(+/+) mice, this 7-day ethanol treatment led to increased hippocampal synaptic activity and reduced adenosine A1 receptor activity under both basal and low Mg(2+) conditions. These effects of ethanol tolerance were associated with an 18% decrease in activity of ecto-5'-nucleotidase activity in hippocampal cell membranes. In contrast, ethanol treatment was not associated with changes in synaptic activity or adenosine signaling in hippocampus from CD73(-/-) mice. These data indicate that ethanol treatment is associated with a reduction in adenosine signaling through adenosine A1 receptors in hippocampus, mediated, at least in part, via reduced ecto-5'-nucleotidase activity. PMID:27189965

  1. Ethanol Tolerance Affects Endogenous Adenosine Signaling in Mouse Hippocampus

    PubMed Central

    Zhang, Dali; Xiong, Wei; Jackson, Michael F.

    2016-01-01

    Ethanol has many pharmacological effects, including increases in endogenous adenosine levels and adenosine receptor activity in brain. Ethanol consumption is associated with both positive and negative health outcomes, but tolerance to the behavioral effects of ethanol can lead to increased consumption, which increases the risk of negative health outcomes. The present study was performed to test whether a 7-day treatment with ethanol is linked to reduced adenosine signaling and whether this is a consequence of reduced ecto-5′-nucleotidase activity. Wild-type (CD73+/+) and ecto-5′-nucleotidase-deficient (CD73−/−) mice were treated with ethanol (2 g/kg) or saline for 7 days. In CD73+/+ mice, repeated ethanol treatment reduced the hypothermic and ataxic effects of acute ethanol, indicating the development of tolerance to the acute effects of ethanol. In CD73+/+ mice, this 7-day ethanol treatment led to increased hippocampal synaptic activity and reduced adenosine A1 receptor activity under both basal and low Mg2+ conditions. These effects of ethanol tolerance were associated with an 18% decrease in activity of ecto-5′-nucleotidase activity in hippocampal cell membranes. In contrast, ethanol treatment was not associated with changes in synaptic activity or adenosine signaling in hippocampus from CD73−/− mice. These data indicate that ethanol treatment is associated with a reduction in adenosine signaling through adenosine A1 receptors in hippocampus, mediated, at least in part, via reduced ecto-5′-nucleotidase activity. PMID:27189965

  2. Identification of possible adenosine receptors in vascular smooth muscle

    SciTech Connect

    Doctrow, S.R.

    1985-01-01

    Adenosine is a vasodilator and has been implicated in increased blood flow in tissues that undergo energy deficiency. During conditions such as hypoxia and ischemia, adenosine is produced and is said to increase blood flow by relaxing the vascular smooth muscle (VSM) lining the resistance vessels. The goal of this research was to identify receptors that might be responsible for adenosine-mediated VSM relaxation. When an insoluble fraction from calf aortic VSM was incubated with /sup 32/P-ATP, two components were phosphorylated. One was identified as myosin light chain by MW, pl, and immunoprecipitation. The other product was identified as phosphatidylinositol-4-phosphate (DPI) by tic. Both phosphorylations were inhibited by adenosine and by 5'-chloro-5'-deoxyadenosine (Cl-Ado). DPI production was much more sensitive to the nucleosides than was myosin phosphorylation. Neither inhibition involved change in cAMP production. Phosphatidylinositol (Pl) kinase in the VSM membranes required magnesium, was activated and solubilized by Triton X-100, and phosphorylated both endogenous and exogenous Pl. Cl-Ado inhibited Pl kinase in a manner competitive with respect to ATP and noncompetitive with respect to Pl. Adenosine and adenosine analogs modified in the ribose ring were inhibitors with potencies comparable to that of Cl-Ado. Adenine nucleotides and purine-modified adenosine analogs were weaker inhibitors than Cl-Ado.

  3. No effect of nutritional adenosine receptor antagonists on exercise performance in the heat.

    PubMed

    Cheuvront, Samuel N; Ely, Brett R; Kenefick, Robert W; Michniak-Kohn, Bozena B; Rood, Jennifer C; Sawka, Michael N

    2009-02-01

    Nutritional adenosine receptor antagonists can enhance endurance exercise performance in temperate environments, but their efficacy during heat stress is not well understood. This double-blinded, placebo-controlled study compared the effects of an acute dose of caffeine or quercetin on endurance exercise performance during compensable heat stress (40 degrees C, 20-30% rh). On each of three occasions, 10 healthy men each performed 30-min of cycle ergometry at 50% Vo2peak followed by a 15-min performance time trial after receiving either placebo (Group P), caffeine (Group C; 9 mg/kg), or quercetin (Group Q; 2,000 mg). Serial blood samples, physiological (heart rate, rectal, and mean skin body temperatures), perceptual (ratings of perceived exertion, pain, thermal comfort, motivation), and exercise performance measures (total work and pacing strategy) were made. Supplementation with caffeine and quercetin increased preexercise blood concentrations of caffeine (55.62 +/- 4.77 microM) and quercetin (4.76 +/- 2.56 microM) above their in vitro inhibition constants for adenosine receptors. No treatment effects were observed for any physiological or perceptual measures, with the exception of elevated rectal body temperatures (0.20-0.30 degrees C; P < 0.05) for Group C vs. Groups Q and P. Supplementation did not affect total work performed (Groups P: 153.5 +/- 28.3, C: 157.3 +/- 28.9, and Q: 151.1 +/- 31.6 kJ; P > 0.05) or the self-selected pacing strategy employed. These findings indicate that the nutritional adenosine receptor antagonists caffeine and quercetin do not enhance endurance exercise performance during compensable heat stress.

  4. Adenosine deaminase in disorders of purine metabolism and in immune deficiency

    SciTech Connect

    Tritsch, G.L.

    1985-01-01

    This book consists of five parts and a section of poster papers. Some of the selection titles are: Adenosine Deaminase Impairment and Ribonucleotide Reductase in Human Cells; Adenosine Deaminase and Malignant Cells; Inhibition of Adenosine Deaminase to Increase the Antitumor Activity of Adenine Nucleoside Analogues; and Molecular Biology of the Adenosine Deaminase Gene and Messenger RNA.

  5. Arabidopsis COPPER MODIFIED RESISTANCE1/PATRONUS1 is essential for growth adaptation to stress and required for mitotic onset control.

    PubMed

    Juraniec, Michal; Heyman, Jefri; Schubert, Veit; Salis, Pietrino; De Veylder, Lieven; Verbruggen, Nathalie

    2016-01-01

    The mitotic checkpoint (MC) guards faithful sister chromatid segregation by monitoring the attachment of spindle microtubules to the kinetochores. When chromosome attachment errors are detected, MC delays the metaphase-to-anaphase transition through the inhibition of the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase. In contrast to yeast and mammals, our knowledge on the proteins involved in MC in plants is scarce. Transient synchronization of root tips as well as promoter-reporter gene fusions were performed to analyze temporal and spatial expression of COPPER MODIFIED RESISTANCE1/PATRONUS1 (CMR1/PANS1) in developing Arabidopsis thaliana seedlings. Functional analysis of the gene was carried out, including CYCB1;2 stability in CMR1/PANS1 knockout and overexpressor background as well as metaphase-anaphase chromosome status. CMR1/PANS1 is transcriptionally active during M phase. Its deficiency provokes premature cell cycle exit and in consequence a rapid consumption of the number of meristematic cells in particular under stress conditions that are known to affect spindle microtubules. Root growth impairment is correlated with a failure to delay the onset of anaphase, resulting in anaphase bridges and chromosome missegregation. CMR1/PANS1 overexpression stabilizes the mitotic CYCB1;2 protein. Likely, CMR1/PANS1 coordinates mitotic cell cycle progression by acting as an APC/C inhibitor and plays a key role in growth adaptation to stress.

  6. Adenosine through the A2A adenosine receptor increases IL-1β in the brain contributing to anxiety

    PubMed Central

    Chiu, Gabriel S.; Darmody, Patrick T.; Walsh, John P.; Moon, Morgan L.; Kwakwa, Kristin A.; Bray, Julie K.; McCusker, Robert H.; Freund, Gregory G.

    2014-01-01

    Anxiety is one of the most commonly reported psychiatric conditions, but its pathogenesis is poorly understood. Ailments associated with activation of the innate immune system, however, are increasingly linked to anxiety disorders. In adult male mice, we found that adenosine doubled caspase-1 activity in brain by a pathway reliant on ATP-sensitive potassium (KATP) channels, protein kinase A (PKA) and the A2A adenosine receptor (AR). In addition, adenosine-dependent activation of caspase-1 increased interleukin (IL)-1β in the brain by two-fold. Peripheral administration of adenosine in wild-type (WT) mice led to a 2.3-fold increase in caspase-1 activity in the amygdala and to a 33% and 42% reduction in spontaneous locomotor activity and food intake, respectively, that were not observed in caspase-1 knockout (KO), IL-1 receptor type 1 (IL-1R1) KO and A2A AR KO mice or in mice administered a caspase-1 inhibitor centrally. Finally, adenosine administration increased anxiety-like behaviors in WT mice by 28% in the open field test and by 55% in the elevated zero-maze. Caspase-1 KO mice, IL-1R1 KO mice, A2A AR KO mice and WT mice treated with the KATP channel blocker, glyburide, were resistant to adenosine-induced anxiety-like behaviors. Thus, our results indicate that adenosine can act as an anxiogenic by activating caspase-1 and increasing IL-1β in the brain. PMID:24907587

  7. Adenosine receptor ligands: differences with acute versus chronic treatment

    PubMed Central

    Jacobson, Kenneth A.; von Lubitz, Dag K. J. E.; Daly, John W.; Fredholm, Bertil B.

    2012-01-01

    Adenosine receptors have been the target of intense research with respect to potential use of selective ligands in a variety of therapeutic areas. Caffeine and theophylline are adenosine receptor antagonists, and over the past three decades a wide range of selective agonists and antagonists for adenosine receptor subtypes have been developed. A complication to the therapeutic use of adenosine receptor ligands is the observation that the effects of acute administration of a particular ligand can be diametrically opposite to the chronic effects of the same ligand. This ‘effect inversion’ is discussed here by Ken Jecobson and colleagues, and has been observed for effects on cognitive processes, seizures and ischaemic damage. PMID:8936347

  8. Extracellular Adenosine Mediates a Systemic Metabolic Switch during Immune Response

    PubMed Central

    Bajgar, Adam; Kucerova, Katerina; Jonatova, Lucie; Tomcala, Ales; Schneedorferova, Ivana; Okrouhlik, Jan; Dolezal, Tomas

    2015-01-01

    Immune defense is energetically costly, and thus an effective response requires metabolic adaptation of the organism to reallocate energy from storage, growth, and development towards the immune system. We employ the natural infection of Drosophila with a parasitoid wasp to study energy regulation during immune response. To combat the invasion, the host must produce specialized immune cells (lamellocytes) that destroy the parasitoid egg. We show that a significant portion of nutrients are allocated to differentiating lamellocytes when they would otherwise be used for development. This systemic metabolic switch is mediated by extracellular adenosine released from immune cells. The switch is crucial for an effective immune response. Preventing adenosine transport from immune cells or blocking adenosine receptor precludes the metabolic switch and the deceleration of development, dramatically reducing host resistance. Adenosine thus serves as a signal that the “selfish” immune cells send during infection to secure more energy at the expense of other tissues. PMID:25915062

  9. d-Propranolol prevents adenosine formation associated with myocardial hypoperfusion.

    PubMed

    Wangler, R D; Peterson, W P; Sparks, H V

    1989-03-01

    d-Propranolol eliminates the increased adenine nucleoside release from hypoperfused hearts [R. D. Wangler, D. F. DeWitt, and H. V. Sparks, Am. J. Physiol. 247 (Heart Circ. Physiol. 16): H330-H336, 1984]. To determine whether d-propranolol reduces adenosine formation or adenosine release into the vascular compartment, we measured myocardial tissue adenosine (TADO). Decreased formation would lower TADO, whereas decreased release would elevate TADO. Reduction of perfusion pressure by 50% reduced coronary flow (CF), venous oxygen tension (PVO2), and myocardial oxygen consumption (MVO2) by approximately 40, 25, and 35%, respectively. Total adenosine and inosine released during 30 min of hypoperfusion increased 10- and 5-fold, respectively. Also, TADO increased from 2.68 +/- 0.37 to 5.17 +/- 0.67 nmol/g (P less than 0.05). In the presence of d-propranolol, the same reduction in perfusion pressure caused a similar decrease in CF and MVO2. d-Propranolol eliminated the release of adenosine and inosine associated with hypoperfusion. TADO after 30 min of hypoperfusion plus d-propranolol was not significantly increased (3.27 +/- 0.40 nmol/g) and was significantly less than hypoperfused hearts. When severe hypoperfusion was created by reducing perfusion pressure 75%, adenosine release still did not increase if d-propranolol was present. When adenosine release was plotted as a function of oxygen supply-consumption, they were related in a hyperbolic fashion. Despite the severity of hypoperfusion, in the presence of d-propranolol the supply-to-consumption ratio was similar to that of the control perfusion group (no drug). We conclude that d-propranolol blocks nucleoside formation during hypoperfusion by reducing oxygen demand such that a reduction of oxygen supply no longer stimulates adenosine formation. PMID:2923237

  10. A label-free fluorescent molecular beacon based on DNA-templated silver nanoclusters for detection of adenosine and adenosine deaminase.

    PubMed

    Zhang, Min; Guo, Su-Miao; Li, Ying-Ru; Zuo, Peng; Ye, Bang-Ce

    2012-06-01

    A simple and reliable fluorescent molecular beacon is developed utilizing DNA-templated silver nanoclusters as a signal indicator and adenosine triphosphate (ATP) and adenosine deaminase as mechanical activators.

  11. A selective adenosine sensor derived from a triplex DNA aptamer.

    PubMed

    Patel, Mayurbhai; Dutta, Avishek; Huang, Haidong

    2011-07-01

    The aim of this study is to develop a selective adenosine aptamer sensor using a rational approach. Unlike traditional RNA aptamers developed from SELEX, duplex DNA containing an abasic site can function as a general scaffold to rationally design aptamers for small aromatic molecules. We discovered that abasic site-containing triplex DNA can also function as an aptamer and provide better affinity than duplex DNA aptamers. A novel adenosine aptamer sensor was designed using such a triplex. The aptamer is modified with furano-dU in the binding site to sense the binding. The sensor bound adenosine has a dissociation constant of 400 nM, more than tenfold stronger than the adenosine aptamer developed from SELEX. The binding quenched furano-dU fluorescence by 40%. It was also demonstrated in this study that this sensor is selective for adenosine over uridine, cytidine, guanosine, ATP, and AMP. The detection limit of this sensor is about 50 nM. The sensor can be used to quantify adenosine concentrations between 50 nM and 2 μM. PMID:21547431

  12. Intrarenal blood flow distribution during adenosine-mediated vasoconstriction.

    PubMed

    Macias, J F; Fiksen-Olsen, M; Romero, J C; Knox, F G

    1983-01-01

    Intrarenal infusion of adenosine induces an initial vasoconstriction followed by a subsequent vasodilation. The intrarenal distribution of blood flow in the vasoconstriction phase is unknown. The present study was undertaken to assess the effect of intrarenal infusion of adenosine on intracortical distribution of renal blood flow during both the vasoconstriction and vasodilation phases. Renal blood flow distribution was measured with radiolabeled microspheres in anesthetized sodium-depleted dogs before and during the early vasoconstriction phase and the late vasodilation phase of intrarenal infusion of adenosine. During the vasoconstriction phase, there was a uniform decrease in blood flow in each renal cortical zone. In the late phase of adenosine infusion, there was a significant increase in deep cortical flow without significant changes in superficial cortical flow compared with control. The effects of adenosine were also compared with those exerted by norepinephrine in which decreased blood flow was demonstrated in all zones. We conclude that the vasoconstrictor phase of adenosine infusion is characterized by a uniform reduction of renal blood flow to all cortical zones, whereas the vasodilator phase is characterized by a selective deep cortical vasodilation.

  13. Detrimental effects of adenosine signaling in sickle cell disease

    PubMed Central

    Zhang, Yujin; Dai, Yingbo; Wen, Jiaming; Zhang, Weiru; Grenz, Almut; Sun, Hong; Tao, Lijian; Lu, Guangxiu; Alexander, Danny C; Milburn, Michael V; Carter-Dawson, Louvenia; Lewis, Dorothy E; Zhang, Wenzheng; Eltzschig, Holger K; Kellems, Rodney E; Blackburn, Michael R; Juneja, Harinder S; Xia, Yang

    2016-01-01

    Hypoxia can act as an initial trigger to induce erythrocyte sickling and eventual end organ damage in sickle cell disease (SCD). Many factors and metabolites are altered in response to hypoxia and may contribute to the pathogenesis of the disease. Using metabolomic profiling, we found that the steady-state concentration of adenosine in the blood was elevated in a transgenic mouse model of SCD. Adenosine concentrations were similarly elevated in the blood of humans with SCD. Increased adenosine levels promoted sickling, hemolysis and damage to multiple tissues in SCD transgenic mice and promoted sickling of human erythrocytes. Using biochemical, genetic and pharmacological approaches, we showed that adenosine A2B receptor (A2BR)-mediated induction of 2,3-diphosphoglycerate, an erythrocyte-specific metabolite that decreases the oxygen binding affinity of hemoglobin, underlies the induction of erythrocyte sickling by excess adenosine both in cultured human red blood cells and in SCD transgenic mice. Thus, excessive adenosine signaling through the A2BR has a pathological role in SCD. These findings may provide new therapeutic possibilities for this disease. PMID:21170046

  14. Adenosine 5'-tetraphosphate and adenosine 5'-pentaphosphate are synthesized by yeast acetyl coenzyme A synthetase.

    PubMed Central

    Guranowski, A; Günther Sillero, M A; Sillero, A

    1994-01-01

    Yeast (Saccharomyces cerevisiae) acetyl coenzyme A (CoA) synthetase (EC 6.2.1.1) catalyzes the synthesis of adenosine 5'-tetraphosphate (P4A) and adenosine 5'-pentaphosphate (p5A) from ATP and tri- or tetrapolyphosphate (P3 or P4), with relative velocities of 7:1, respectively. Of 12 nucleotides tested as potential donors of nucleotidyl moiety, only ATP, adenosine-5'-O-[3-thiotriphosphate], and acetyl-AMP were substrates, with relative velocities of 100, 62, and 80, respectively. The Km values for ATP, P3, and acetyl-AMP were 0.16, 4.7, and 1.8 mM, respectively. The synthesis of p4A could proceed in the absence of exogenous acetate but was stimulated twofold by acetate, with an apparent Km value of 0.065 mM. CoA did not participate in the synthesis of p4A (p5A) and inhibited the reaction (50% inhibitory concentration of 0.015 mM). At pH 6.3, which was optimum for formation of p4A (p5A), the rate of acetyl-CoA synthesis (1.84 mumol mg-1 min-1) was 245 times faster than the rate of synthesis of p4A measured in the presence of acetate. The known formation of p4A (p5A) in yeast sporulation and the role of acetate may therefore be related to acetyl-CoA synthetase. Images PMID:7910605

  15. Helicase domain encoded by Cucumber mosaic virus RNA1 determines systemic infection of Cmr1 in pepper.

    PubMed

    Kang, Won-Hee; Seo, Jang-Kyun; Chung, Bong Nam; Kim, Kook-Hyung; Kang, Byoung-Cheorl

    2012-01-01

    The Cmr1 gene in peppers confers resistance to Cucumber mosaic virus isolate-P0 (CMV-P0). Cmr1 restricts the systemic spread of CMV strain-Fny (CMV-Fny), whereas this gene cannot block the spread of CMV isolate-P1 (CMV-P1) to the upper leaves, resulting in systemic infection. To identify the virulence determinant of CMV-P1, six reassortant viruses and six chimeric viruses derived from CMV-Fny and CMV-P1 cDNA clones were used. Our results demonstrate that the C-terminus of the helicase domain encoded by CMV-P1 RNA1 determines susceptibility to systemic infection, and that the helicase domain contains six different amino acid substitutions between CMV-Fny and CMV-P1(.) To identify the key amino acids of the helicase domain determining systemic infection with CMV-P1, we then constructed amino acid substitution mutants. Of the mutants tested, amino acid residues at positions 865, 896, 957, and 980 in the 1a protein sequence of CMV-P1 affected the systemic infection. Virus localization studies with GFP-tagged CMV clones and in situ localization of virus RNA revealed that these four amino acid residues together form the movement determinant for CMV-P1 movement from the epidermal cell layer to mesophyll cell layers. Quantitative real-time PCR revealed that CMV-P1 and a chimeric virus with four amino acid residues of CMV-P1 accumulated more genomic RNA in inoculated leaves than did CMV-Fny, indicating that those four amino acids are also involved in virus replication. These results demonstrate that the C-terminal region of the helicase domain is responsible for systemic infection by controlling virus replication and cell-to-cell movement. Whereas four amino acids are responsible for acquiring virulence in CMV-Fny, six amino acid (positions at 865, 896, 901, 957, 980 and 993) substitutions in CMV-P1 were required for complete loss of virulence in 'Bukang'.

  16. Adaptations in adenosine signaling in drug dependence: therapeutic implications.

    PubMed

    Hack, Stephen P; Christie, Macdonald J

    2003-01-01

    Adenosine is an important endogenous purine neuromodulator in the central nervous system that modulates many important cellular processes in neurons. The physiological effects of adenosine are transduced through four pharmacologically classified receptor types i.e., A1, A2A, A2B and A3. All adenosine receptors are G-protein coupled receptors (GPCR) of the type 1 variety. Adaptations in adenosine signaling have been implicated in a wide range of pathophysiological processes, such as epilepsies, sleep disorders, pain, and drug addictions. Knowledge relating to the etiology of addictive processes is far from complete, and as a result the therapeutic options to deal with drug dependence issues are limited. Drugs of abuse mediate their effects through many distinct cellular effectors, such as neurotransmitter transporters, ion channels, and receptor proteins. However, a unifying feature of the major drugs of abuse-i.e., opiates, cocaine, and alcohol-is that they all directly or indirectly modulate adenosine signaling in neurons. Agents targeting adenosine receptors may therefore offer novel avenues for the development of therapies to manage or treat addictions. A consistent cellular adaptation to long-term drug use is the up- or down-regulation of signaling pathways driven by adenylyl cyclase/cyclic AMP (cAMP) in several brain regions linked to addiction. Withdrawal from mu-opioids or cocaine following their chronic administration leads to an upregulation of adenylyl cyclase-mediated signaling, resulting in high levels of cAMP. Cyclic AMP produced in this way acts as a substrate for the endogenous production of adenosine. Increased levels of endogenous adenosine interact with presynaptic A1 receptors to inhibit the excessive neuronal excitation often seen during morphine/cocaine withdrawal. These pre-clinical findings fit well with other data indicating that drugs which boost endogenous adenosine levels or directly interact with inhibitory A1 receptors can alleviate

  17. Interstitial adenosine concentration is increased by dipyridamole

    SciTech Connect

    Gorman, M.W.; Wangler, R.D.; DeWitt, D.F.; Wang, C.Y.; Bassingthwaighte, J.B.; Sparks, H.V.

    1986-03-01

    The authors used the multiple indicator dilution technique to observe the capillary transport of adenosine (ADO) in isolated guinea pig hearts. Radiolabelled albumin, sucrose and ADO were injected on the arterial side and measured in venous samples collected during the following 20 seconds. Transport parameters calculated from these data include permeability-surface area products (PS) for transendothelial diffusion, endothelial cell (EC) uptake at the lumenal and ablumenal membranes, and EC metabolism. With simultaneous measurements of arterial and venous ADO concentrations and flow, the authors calculated the steady-state interstitial fluid (ISF) ADO concentration. Under control conditions the venous ADO concentration was 7.1 +/- 2.8 nM. The calculated ISF concentration depends on whether they assume the venous ADO comes from the ISF, or directly from ECs. These ISF concentrations are 25 +/- 12 nM and 9.8 +/- 4.0 nM, respectively. During dipyridamole infusion (10 uM) the EC transport parameters became nearly zero. Venous and ISF ADO concentrations increased to 33 +/- 8.9 nM and 169 +/- 42 nM, respectively. The authors conclude that the ISF ADO concentration is 1.5-4 fold higher than the venous concentration at rest, and the ISF concentration increases greatly with dipyridamole.

  18. Postsynaptic Adenosine A2A Receptors Modulate Intrinsic Excitability of Pyramidal Cells in the Rat Basolateral Amygdala

    PubMed Central

    Rau, Andrew R.; Ariwodola, Olusegun J.

    2015-01-01

    Background: The basolateral amygdala plays a critical role in the etiology of anxiety disorders and addiction. Pyramidal neurons, the primary output cells of this region, display increased firing following exposure to stressors, and it is thought that this increase in excitability contributes to stress responsivity and the expression of anxiety-like behaviors. However, much remains unknown about the underlying mechanisms that regulate the intrinsic excitability of basolateral amygdala pyramidal neurons. Methods: Ex vivo gramicidin perforated patch recordings were conducted in current clamp mode where hyper- and depolarizing current steps were applied to basolateral amygdala pyramidal neurons to assess the effects of adenosine A2A receptor modulation on intrinsic excitability. Results: Activation of adenosine A2A receptors with the selective A2A receptor agonist CGS-21680 significantly increased the firing rate of basolateral amygdala pyramidal neurons in rat amygdala brain slices, likely via inhibition of the slow afterhyperpolarization potential. Both of these A2A receptor-mediated effects were blocked by preapplication of a selective A2A receptor antagonist (ZM-241385) or by intra-pipette infusion of a protein kinase A inhibitor, suggesting a postsynaptic locus of A2A receptors on basolateral amygdala pyramidal neurons. Interestingly, bath application of the A2A receptor antagonist alone significantly attenuated basolateral amygdala pyramidal cell firing, consistent with a role for tonic adenosine in the regulation of the intrinsic excitability of these neurons. Conclusions: Collectively, these data suggest that adenosine, via activation of A2A receptors, may directly facilitate basolateral amygdala pyramidal cell output, providing a possible balance for the recently described inhibitory effects of adenosine A1 receptor activation on glutamatergic excitation of basolateral amygdala pyramidal cells. PMID:25716780

  19. Coronary computed tomography angiography (CCTA) and cardiac magnetic resonance (CMR) imaging in the assessment of patients presenting with chest pain suspected for acute coronary syndrome

    PubMed Central

    De Filippo, Massimo; Capasso, Raffaella

    2016-01-01

    Acute chest pain is an important clinical challenge and a major reason for presentation to the emergency department. Although multiple imaging techniques are available to assess patients with suspected acute coronary syndrome (ACS), considerable interest has been focused on the use of non-invasive imaging options as coronary computed tomography angiography (CCTA) and cardiac magnetic resonance (CMR). According to several recent evidences, CCTA has been shown to represent a useful tool to rapidly and accurately diagnose coronary artery disease (CAD) in patients with low to intermediate cardiovascular risk. CCTA examination has the unique ability to non-invasively depict the coronary anatomy, not only allowing visualization of the lumen of the arteries in order to detect severe stenosis or occlusion responsible of myocardial ischemia, but also allows the assessment of coronary artery wall by demonstrating the presence or absence of CAD. However, routine CCTA is not able to differentiate ischemic from non-ischemic chest pain in patients with known CAD and it does not provide any functional assessment of the heart. Conversely, CMR is considered the gold standard in the evaluation of morphology, function, viability and tissue characterization of the heart. CMR offers a wide range of tools for diagnosing myocardial infarction (MI) at least at the same time of the elevation of cardiac troponin values, differentiating infarct tissue and ischemic myocardium from normal myocardium or mimicking conditions, and distinguishing between new and old ischemic events. In high-risk patients, with acute and chronic manifestations of CAD, CMR may be preferable to CCTA, since it would allow detection, differential diagnosis, prognostic evaluation and management of MI. PMID:27500156

  20. Role of Perfusion at Rest in the Diagnosis of Myocardial Infarction Using Vasodilator Stress Cardiovascular Magnetic Resonance.

    PubMed

    Patel, Mita B; Mor-Avi, Victor; Kawaji, Keigo; Nathan, Sandeep; Kramer, Christopher M; Lang, Roberto M; Patel, Amit R

    2016-04-01

    In clinical practice, perfusion at rest in vasodilator stress single-photon emission computed tomography is commonly used to confirm myocardial infarction (MI) and ischemia and to rule out artifacts. It is unclear whether perfusion at rest carries similar information in cardiovascular magnetic resonance (CMR). We sought to determine whether chronic MI is associated with abnormal perfusion at rest on CMR. We compared areas of infarct and remote myocardium in 31 patients who underwent vasodilator stress CMR (1.5 T), had MI confirmed by late gadolinium enhancement (LGE scar), and coronary angiography within 6 months. Stress perfusion imaging during gadolinium first pass was followed by reversal with aminophylline (75 to 125 mg), rest perfusion, and LGE imaging. Resting and peak-stress time-intensity curves were used to obtain maximal upslopes (normalized by blood pool upslopes), which were compared between infarcted and remote myocardial regions of interest. At rest, there was no significant difference between the slopes in the regions of interest supplied by arteries with and without stenosis >70% (0.31 ± 0.16 vs 0.26 ± 0.15 1/s), irrespective of LGE scar. However, at peak stress, we found significant differences (0.20 ± 0.11 vs 0.30 ± 0.22 1/s; p <0.05), reflecting the expected stress-induced ischemia. Similarly, at rest, there was no difference between infarcted and remote myocardium (0.27 ± 0.14 vs 0.30 ± 0.17 1/s), irrespective of stenosis, but significant differences were seen during stress (0.21 ± 0.16 vs 0.28 ± 0.18 1/s; p <0.001), reflecting inducible ischemia. In conclusion, abnormalities in myocardial perfusion at rest associated with chronic MI are not reliably detectable on CMR images. Accordingly, unlike single-photon emission computed tomography, normal CMR perfusion at rest should not be used to rule out chronic MI.

  1. Adenosine deaminase from Streptomyces coelicolor: recombinant expression, purification and characterization.

    PubMed

    Pornbanlualap, Somchai; Chalopagorn, Pornchanok

    2011-08-01

    The sequencing of the genome of Streptomyces coelicolor A3(2) identified seven putative adenine/adenosine deaminases and adenosine deaminase-like proteins, none of which have been biochemically characterized. This report describes recombinant expression, purification and characterization of SCO4901 which had been annotated in data bases as a putative adenosine deaminase. The purified putative adenosine deaminase gives a subunit Mr=48,400 on denaturing gel electrophoresis and an oligomer molecular weight of approximately 182,000 by comparative gel filtration. These values are consistent with the active enzyme being composed of four subunits with identical molecular weights. The turnover rate of adenosine is 11.5 s⁻¹ at 30 °C. Since adenine is deaminated ∼10³ slower by the enzyme when compared to that of adenosine, these data strongly show that the purified enzyme is an adenosine deaminase (ADA) and not an adenine deaminase (ADE). Other adenine nucleosides/nucleotides, including 9-β-D-arabinofuranosyl-adenine (ara-A), 5'-AMP, 5'-ADP and 5'-ATP, are not substrates for the enzyme. Coformycin and 2'-deoxycoformycin are potent competitive inhibitors of the enzyme with inhibition constants of 0.25 and 3.4 nM, respectively. Amino acid sequence alignment of ScADA with ADAs from other organisms reveals that eight of the nine highly conserved catalytic site residues in other ADAs are also conserved in ScADA. The only non-conserved residue is Asn317, which replaces Asp296 in the murine enzyme. Based on these data, it is suggested here that ADA and ADE proteins are divergently related enzymes that have evolved from a common α/β barrel scaffold to catalyze the deamination of different substrates, using a similar catalytic mechanism. PMID:21511036

  2. Role of A3 adenosine receptor in diabetic neuropathy.

    PubMed

    Yan, Heng; Zhang, Enshui; Feng, Chang; Zhao, Xin

    2016-10-01

    Neuropathy is the most common diabetic complication. Although the A1 and A2A adenosine receptors are important pharmacological targets in alleviating diabetic neuropathy, the role of the A3 adenosine receptor remains unknown. Because the A3 adenosine receptor regulates pain induced by chronic constriction injury or chemotherapy, its stimulation might also attenuate diabetic neuropathy. This study examines the effects of systemic treatment with the A3 adenosine receptor agonist 1-deoxy-1-[6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-N-methyl-β-d-ribofuranuronamide (IB-MECA) on diabetic neuropathy and explores the putative mechanisms underlying its pharmacological effects. We show that IB-MECA alleviated mechanical hyperalgesia and thermal hypoalgesia in mice 2 weeks but not 4 weeks after streptozocin (STZ) treatment. Furthermore, IB-MECA prevented the reduction in sciatic motor nerve conduction velocity and sensory nerve conduction velocity in diabetic mice 2 weeks but not 4 weeks after STZ treatment. Similarly, IB-MECA inhibited the activation of nuclear factor-κB and decreased the generation of tumor necrosis factor-α in the spinal cord of mice 2 weeks but not 4 weeks after STZ treatment. These phenomena were associated with reduction of A3 adenosine receptor expression in the spinal cord after long-term diabetes. Our results suggest that the A3 adenosine receptor plays a critical role in regulating diabetic neuropathy and that reduction in A3 adenosine receptor expression/function might contribute to the progression of diabetic neuropathy. © 2016 Wiley Periodicals, Inc.

  3. Increased adenosine contributes to penile fibrosis, a dangerous feature of priapism, via A2B adenosine receptor signaling

    PubMed Central

    Wen, Jiaming; Jiang, Xianzhen; Dai, Yingbo; Zhang, Yujin; Tang, Yuxin; Sun, Hong; Mi, Tiejuan; Phatarpekar, Prasad V.; Kellems, Rodney E.; Blackburn, Michael R.; Xia, Yang

    2010-01-01

    Priapism is a condition of persistent penile erection in the absence of sexual excitation. Of men with sickle cell disease (SCD), 40% display priapism. The disorder is a dangerous and urgent condition, given its association with penile fibrosis and eventual erectile dysfunction. Current strategies to prevent its progression are poor because of a lack of fundamental understanding of the molecular mechanisms for penile fibrosis in priapism. Here we demonstrate that increased adenosine is a novel causative factor contributing to penile fibrosis in two independent animal models of priapism, adenosine deaminase (ADA)-deficient mice and SCD transgenic mice. An important finding is that chronic reduction of adenosine by ADA enzyme therapy successfully attenuated penile fibrosis in both mouse models, indicating an essential role of increased adenosine in penile fibrosis and a novel therapeutic possibility for this serious complication. Subsequently, we identified that both mice models share a similar fibrotic gene expression profile in penile tissue (including procollagen I, TGF-β1, and plasminogen activator inhibitor-1 mRNA), suggesting that they share similar signaling pathways for progression to penile fibrosis. Thus, in an effort to decipher specific cell types and underlying mechanism responsible for adenosine-mediated penile fibrosis, we purified corpus cavernosal fibroblast cells (CCFCs), the major cell type involved in this process, from wild-type mice. Quantitative RT-PCR showed that the major receptor expressed in these cells is the adenosine receptor A2BR. Based on this fact, we further purified CCFCs from A2BR-deficient mice and demonstrated that A2BR is essential for excess adenosine-mediated penile fibrosis. Finally, we revealed that TGF-β functions downstream of the A2BR to increase CCFC collagen secretion and proliferation. Overall, our studies identify an essential role of increased adenosine in the pathogenesis of penile fibrosis via A2BR signaling and

  4. [Vascular effects of adenosine-triphosphate].

    PubMed

    Colson, P; Saussine, M; Gaba, S; Sequin, J; Chaptal, P A; Roquefeuil, B

    1991-01-01

    This study assessed the effects of adenosine triphosphate (ATP) on systemic vascular resistances during the hypothermic cardiopulmonary bypass phase of cardiac surgery. Twenty patients scheduled for cardiac surgery were randomly divided into an ATP group (n = 10), and a placebo group (n = 10). Anaesthesia was similar for all the patients (diazepam, fentanyl and pancuronium). During the heart arrest phase, and as soon as the arterial pressure, the level in the venous return reservoir, and the pump flow rate had all been in steady state for 5 min, ATP or placebo was injected into the venous line of the oxygenator. Injection speed was doubled every three minutes, twice. The following ATP doses were administered: 0.012, 0.025 and 0.05 mg.kg-1.min-1. The level in the venous return reservoir was kept constant. Mean arterial pressure (MAP) and pump flow rate (DP) were assessed every half minute. Systemic vascular resistances were calculated with the relationship MAP/DP. Changes in vascular capacitance were directly proportional to changes in DP as the heart had been excluded, and all the blood returned to the pump, the blood volume being kept constant. MAP and DP remained unchanged in the placebo group. In the opposite ATP induced a dose-related systemic vasodilation: MAP decreased from 82.8 +/- 12.5 mmHg (control) to 66.0 +/- 14.8 mmHg, 59.8 +/- 10.6 mmHg, and 49.0 +/- 4.7 mmHg with 0.012, 0.025 and 0.05 mg.kg-1.min-1 ATP respectively. The MAP returned to preinfusion control levels when the ATP infusion was discontinued (90.0 +/- 17.8 mmHg). The DP, and therefore venous return, did not change, neither during ATP infusion, nor after its discontinuation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1854051

  5. Effect of adenosine on the growth of human T-lymphocyte leukemia cell line MOLT-4.

    PubMed

    Streitová, Denisa; Weiterová, Lenka; Hofer, Michal; Holá, Jirina; Horváth, Viktor; Kozubík, Alois; Znojil, Vladimír

    2007-09-01

    Adenosine has been observed to suppress the growth of MOLT-4 human leukemia cells in vitro. Changes in the cell cycle, especially increased percentage of cells in S phase, prolonged generation time, and induction of apoptosis at higher adenosine concentrations have been found to be responsible for the growth suppression. Dipyridamole, a drug inhibiting the cellular uptake of adenosine, reversed partially but significantly the adenosine-induced growth suppression. It follows from these results that the action of adenosine on the MOLT-4 cells comprises its cellular uptake and intracellular operation. These findings present new data on anticancer efficacy of adenosine.

  6. Dicinnamoylquinides in roasted coffee inhibit the human adenosine transporter.

    PubMed

    de Paulis, Tomas; Schmidt, Dennis E; Bruchey, Aleksandra K; Kirby, Michael T; McDonald, Michael P; Commers, Patricia; Lovinger, David M; Martin, Peter R

    2002-05-10

    Preliminary screening of a minor, non-xanthine constituent of roasted coffee, 3,4-diferuloyl-1,5-quinolactone (DIFEQ), showed inhibition of the adenosine transporter at low micromolar concentration. DIFEQ is a neutral derivative of the chlorogenic acids, i.e. isomeric mono- and di-substituted coumaroyl-, caffeoyl-, and feruloyl-esters of quinic acid, formed in the roasting process of coffee. Displacement of the adenosine transporter antagonist [(3)H](S)-(nitrobenzyl)-6-thioinosine binding by DIFEQ in cultured U-937 cell preparations, expressing the human adenosine transporter protein (hENT1), showed a K(i) of 0.96+/-0.13 microM. Extracts of regular and decaffeinated coffee showed binding activities equivalent to 30-40 mg DIFEQ per three cups of coffee. Acute administration of a high dose of DIFEQ (100 mg/kg i.p.) reduced open field locomotion in mice for 20 min in correlation with brain levels of DIFEQ. Both 3,4-dicaffeoyl-1,5-quinide and 3,4-dicoumaroyl-1,5-quinide, two close structural analogs of DIFEQ also present in roasted coffee, showed similar affinities for the adenosine transporter, while the corresponding 3- and 4-mono caffeoyl- and feruloyl-quinides were one to two orders of magnitudes less active. This suggests that 3,4-dicinnamoyl-1,5-quinides in coffee could have the potential to raise extra-cellular adenosine levels, thereby counteracting the stimulant effect of caffeine.

  7. Dicinnamoylquinides in roasted coffee inhibit the human adenosine transporter.

    PubMed

    de Paulis, Tomas; Schmidt, Dennis E; Bruchey, Aleksandra K; Kirby, Michael T; McDonald, Michael P; Commers, Patricia; Lovinger, David M; Martin, Peter R

    2002-05-10

    Preliminary screening of a minor, non-xanthine constituent of roasted coffee, 3,4-diferuloyl-1,5-quinolactone (DIFEQ), showed inhibition of the adenosine transporter at low micromolar concentration. DIFEQ is a neutral derivative of the chlorogenic acids, i.e. isomeric mono- and di-substituted coumaroyl-, caffeoyl-, and feruloyl-esters of quinic acid, formed in the roasting process of coffee. Displacement of the adenosine transporter antagonist [(3)H](S)-(nitrobenzyl)-6-thioinosine binding by DIFEQ in cultured U-937 cell preparations, expressing the human adenosine transporter protein (hENT1), showed a K(i) of 0.96+/-0.13 microM. Extracts of regular and decaffeinated coffee showed binding activities equivalent to 30-40 mg DIFEQ per three cups of coffee. Acute administration of a high dose of DIFEQ (100 mg/kg i.p.) reduced open field locomotion in mice for 20 min in correlation with brain levels of DIFEQ. Both 3,4-dicaffeoyl-1,5-quinide and 3,4-dicoumaroyl-1,5-quinide, two close structural analogs of DIFEQ also present in roasted coffee, showed similar affinities for the adenosine transporter, while the corresponding 3- and 4-mono caffeoyl- and feruloyl-quinides were one to two orders of magnitudes less active. This suggests that 3,4-dicinnamoyl-1,5-quinides in coffee could have the potential to raise extra-cellular adenosine levels, thereby counteracting the stimulant effect of caffeine. PMID:12065074

  8. Antagonism by theophylline of respiratory inhibition induced by adenosine.

    PubMed

    Eldridge, F L; Millhorn, D E; Kiley, J P

    1985-11-01

    The effects on respiration of an analogue of adenosine, L-2-N6-(phenylisopropyl)adenosine (PIA), and of the methylxanthine, theophylline, were determined in 19 vagotomized glomectomized cats whose end-tidal PCO2 was kept constant by means of a servo-controlled ventilator. Integrated phrenic nerve activity was used to represent respiratory output. Our results show that PIA, whether given systemically or into the third cerebral ventricle, depressed respiration. Systemically administered theophylline stimulated respiration. Theophylline given intravenously, or into the third ventricle not only reversed the depressive effects of previously administered PIA but caused further increases of respiration above the control level. Prior systemic administration of theophylline blocked both respiratory and hypotensive effects of subsequently administered PIA. Effects of either agent on medullary extracellular fluid pH did not explain the results. We conclude that the adenosine analogue PIA, acts to inhibit neurons in the brain that are involved in the control of respiration and that its effects are blocked by theophylline. We suggest that adenosine acts as a tonic modulator of respiration and that theophylline stimulates breathing by competitive antagonism of adenosine at neuronal receptor sites. PMID:4066573

  9. Adenosine signaling and the regulation of chronic lung disease

    PubMed Central

    Zhou, Yang; Schneider, Daniel J.; Blackburn, Michael R.

    2009-01-01

    Chronic lung diseases such as asthma, chronic obstructive pulmonary disease and interstitial lung disease are characterized by inflammation and tissue remodeling processes that compromise pulmonary function. Adenosine is produced in the inflamed and damaged lung where it plays numerous roles in the regulation of inflammation and tissue remodeling. Extracellular adenosine serves as an autocrine and paracrine signaling molecule by engaging cell surface adenosine receptors. Preclinical and cellular studies suggest that adenosine plays an anti-inflammatory role in processes associated with acute lung disease, where activation of the A2AR and A2BR have promising implications for the treatment of these disorders. In contrast, there is growing evidence that adenosine signaling through the A1R, A2BR and A3R may serve pro-inflammatory and tissue remodeling functions in chronic lung diseases. This review discusses the current progress of research efforts and clinical trials aimed at understanding the complexities of this signaling pathway as they pertain to the development of treatment strategies for chronic lung diseases. PMID:19426761

  10. Effect of adenosine and inosine on ureagenesis in hepatocytes.

    PubMed Central

    Guinzberg, R; Laguna, I; Zentella, A; Guzman, R; Piña, E

    1987-01-01

    Adenosine and inosine produced a dose-dependent stimulation of ureagenesis in isolated rat hepatocytes. Hypoxanthine, xanthine and uric acid were without effect. Half-maximally effective concentrations were 0.08 microM for adenosine and 5 microM for inosine. Activation of ureagenesis by both nucleosides had the following characteristics: (a) it was observed with either glutamine or (NH4)2CO3, provided that glucose was present; (b) it was not detected when glucose was replaced by lactate plus oleate; (c) it was mutually antagonized by glucagon, but not by adrenaline; and (d) it was dependent on Ca2+. We suggest that the action of adenosine and inosine on ureagenesis might be of physiological significance. PMID:3663162

  11. Adenosine receptor agonists for promotion of dermal wound healing

    PubMed Central

    Valls, María D.; Cronstein, Bruce N.; Montesinos, M. Carmen

    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 which adenosine receptor activation affects the function of the cells and tissues that participate in wound healing, emphasizing the potential beneficial impact of adenosine receptor agonists in diabetic impaired healing. PMID:19041853

  12. Role of adenosine as adjunctive therapy in acute myocardial infarction.

    PubMed

    Forman, Mervyn B; Stone, Gregg W; Jackson, Edwin K

    2006-01-01

    Although early reperfusion and maintained patency is the mainstay therapy for ST elevation myocardial infarction, experimental studies demonstrate that reperfusion per se induces deleterious effects on viable ischemic cells. Thus "myocardial reperfusion injury" may compromise the full potential of reperfusion therapy and may account for unfavorable outcomes in high-risk patients. Although the mechanisms of reperfusion injury are complex and multifactorial, neutrophil-mediated microvascular injury resulting in a progressive decrease in blood flow ("no-reflow" phenomenon) likely plays an important role. Adenosine is an endogenous nucleoside found in large quantities in myocardial and endothelial cells. It activates four well-characterized receptors producing various physiological effects that attenuate many of the proposed mechanisms of reperfusion injury. The cardio-protective effects of adenosine are supported by its role as a mediator of pre- and post-conditioning. In experimental models, administration of adenosine in the peri-reperfusion period results in a marked reduction in infarct size and improvement in ventricular function. The cardioprotective effects in the canine model have a narrow time window with the drug losing its effect following three hours of ischemia. Several small clinical studies have demonstrated that administration of adenosine with reperfusion therapy reduces infarct size and improves ventricular function. In the larger AMISTAD and AMISTAD II trials a 3-h infusion of adenosine as an adjunct to reperfusion resulted in a striking reduction in infarct size (55-65%). Post hoc analysis of AMISTAD II showed that this was associated with significantly improved early and late mortality in patients treated within 3.17 h of symptoms. An intravenous infusion of adenosine for 3 h should be considered as adjunctive therapy in high risk-patients undergoing reperfusion therapy. PMID:16961725

  13. Investigating real-time activation of adenosine receptors by bioluminescence resonance energy transfer technique

    NASA Astrophysics Data System (ADS)

    Huang, Yimei; Yang, Hongqin; Zheng, Liqin; Chen, Jiangxu; Wang, Yuhua; Li, Hui; Xie, Shusen

    2013-02-01

    Adenosine receptors play important roles in many physiological and pathological processes, for example regulating myocardial oxygen consumption and the release of neurotransmitters. The activations of adenosine receptors have been studied by some kinds of techniques, such as western blot, immunohistochemistry, etc. However, these techniques cannot reveal the dynamical response of adenosine receptors under stimulation. In this paper, bioluminescence resonance energy transfer technique was introduced to study the real-time activation of adenosine receptors by monitoring the dynamics of cyclic adenosine monophosphate (cAMP) level. The results showed that there were significant differences between adenosine receptors on real-time responses under stimulation. Moreover, the dynamics of cAMP level demonstrated that competition between adenosine receptors existed. Taken together, our study indicates that monitoring the dynamics of cAMP level using bioluminescence resonance energy transfer technique could be one potential approach to investigate the mechanism of competitions between adenosine receptors.

  14. In Emergency Department Patients with Acute Chest Pain, Stress Cardiac MRI Observation Unit Care Reduces 1- year Cardiac-Related Health Care Expenditures: A Randomized Trial

    PubMed Central

    Miller, Chadwick D.; Hwang, Wenke; Case, Doug; Hoekstra, James W.; Lefebvre, Cedric; Blumstein, Howard; Hamilton, Craig A.; Harper, Erin N.; Hundley, W. Gregory

    2013-01-01

    Objective To compare the direct cost of medical care and clinical events during the first year after patients with intermediate risk acute chest pain were randomized to stress cardiovascular magnetic resonance (CMR) observation unit (OU) testing, versus inpatient care. Background In a recent study, randomization to OU-CMR reduced median index hospitalization cost compared to inpatient care in patients presenting to the emergency department with intermediate risk acute chest pain. Methods Emergency department patients with intermediate risk chest pain were randomized to OU-CMR (OU care, cardiac markers, stress CMR) or inpatient care (admission, care per admitting provider). This analysis reports the direct cost of cardiac-related care and clinical outcomes (MI, revascularization, cardiovascular death) during the first year of follow-up subsequent to discharge. Consistent with health economics literature, provider cost was calculated from work-related relative value units using the Medicare conversion factor; facility charges were converted to cost using departmental specific cost-to-charge ratios. Linear models were used to compare cost accumulation among study groups. Results One-hundred nine (109) randomized subjects were included in this analysis (52 OU-CMR, 57 inpatient care). The median age was 56 years; baseline characteristics were similar in both groups. At 1 year, 6% of OU-CMR and 9% of inpatient care participants experienced a major cardiac event (p=0.72) with 1 patient in each group experiencing a cardiac event after discharge. First-year cardiac-related costs were significantly lower for participants randomized to OU-CMR compared to participants receiving inpatient care (geometric mean = $3101 vs $4742 including the index visit (p = .004) and $29 vs $152 following discharge (p = .012)). During the year following randomization, 6% of OU-CMR and 9% of inpatient care participants experienced a major cardiac event (p=0.72). Conclusions An OU-CMR strategy

  15. Phosphorylation of adenosine with trimetaphosphate under simulated prebiotic conditions.

    PubMed

    Cheng, Changmei; Fan, Chang; Wan, Rong; Tong, Chunyuan; Miao, Zhiwei; Chen, Jing; Zhao, Yufen

    2002-06-01

    The phosphorylation of adenosine with trimetaphosphate in solution, in solid phase and using wet-dry cycles was carried out and it was found that wet-dry cycles were the most efficient. The catalytic effects of some metal ions on the phosphorylation were also studied and it was discovered that Ni(II) is the most effective. The combination of wet-dry cycles (4 cycles) and catalysis by Ni(II) led to an unprecedented high conversion of adenosine to phosphorylated products (30%) near neutral pH. The main phosphorylated products were 2',3'-cyclic AMP (10.4%) and 5'-ATP (13.0%). PMID:12227426

  16. S-Adenosylhomocysteine toxicity in normal and adenosine kinase-deficient lymphoblasts of human origin

    PubMed Central

    Kredich, Nicholas M.; Hershfield, Michael S.

    1979-01-01

    The human lymphoblast line WI-L2 is subject to growth inhibition by a combination of the adenosine deaminase (ADA; adenosine aminohydrolase, EC 3.5.4.4.) inhibitor erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) and adenosine. Although adenosine-induced pyrimidine starvation appears to contribute to this effect, uridine only partially reverses adenosine toxicity in WI-L2 and not at all in strain 107, an adenosine kinase-(ATP:adenosine 5′-phosphotransferase, EC 2.7.1.20) deficient derivative of WI-L2. Treatment of both cell lines with EHNA and adenosine leads to striking elevations in intracellular S-adenosyl-L-homocysteine (AdoHcy), a potent inhibitor of S-adenosyl-L-methionine (AdoMet)-dependent methylation reactions. The methylation in vivo of both DNA and RNA is inhibited by concentrations of EHNA and adenosine that elevate intracellular AdoHcy. Addition of 100 μM L-homocysteine thiolactone to cells treated with EHNA and adenosine enhances adenosine toxicity and further elevates AdoHcy to levels approximately 60-fold higher than those obtained in the absence of this amino acid, presumably by combining with adenosine to form AdoHcy in a reaction catalyzed by S-adenosylhomocysteine hydrolase (EC 3.3.1.1). In the adenosine kinase-deficient strain 107, a combination of ADA inhibition and L-homocysteine thiolactone markedly increases intracellular AdoHcy and inhibits growth even in the absence of exogenous adenosine. These results demonstrate a form of toxicity from endogenously produced adenosine and support the view that AdoHcy, by inhibiting methylation, is a mediator of uridine-resistant adenosine toxicity in these human lymphoblast lines. Furthermore, they suggest that AdoHcy may play a role in the pathogenesis of the severe combined immunodeficiency disease found in most children with heritable ADA deficiency. PMID:221926

  17. The Second Extracellular Loop of the Adenosine A1 Receptor Mediates Activity of Allosteric Enhancers

    PubMed Central

    Kennedy, Dylan P.; McRobb, Fiona M.; Leonhardt, Susan A.; Purdy, Michael; Figler, Heidi; Marshall, Melissa A.; Chordia, Mahendra; Figler, Robert; Linden, Joel

    2014-01-01

    Allosteric enhancers of the adenosine A1 receptor amplify signaling by orthosteric agonists. Allosteric enhancers are appealing drug candidates because their activity requires that the orthosteric site be occupied by an agonist, thereby conferring specificity to stressed or injured tissues that produce adenosine. To explore the mechanism of allosteric enhancer activity, we examined their action on several A1 receptor constructs, including (1) species variants, (2) species chimeras, (3) alanine scanning mutants, and (4) site-specific mutants. These findings were combined with homology modeling of the A1 receptor and in silico screening of an allosteric enhancer library. The binding modes of known docked allosteric enhancers correlated with the known structure-activity relationship, suggesting that these allosteric enhancers bind to a pocket formed by the second extracellular loop, flanked by residues S150 and M162. We propose a model in which this vestibule controls the entry and efflux of agonists from the orthosteric site and agonist binding elicits a conformational change that enables allosteric enhancer binding. This model provides a mechanism for the observations that allosteric enhancers slow the dissociation of orthosteric agonists but not antagonists. PMID:24217444

  18. Intracellular adenosine 5'-triphosphate, adenosine 5'-diphosphate, and adenosine 5'-monophosphate detection by short-end injection capillary electrophoresis using methylcellulose as the effective electroosmostic flow suppressor.

    PubMed

    Zinellu, Angelo; Sotgia, Salvatore; Pasciu, Valeria; Madeddu, Manuela; Leoni, Giovanni Giuseppe; Naitana, Salvatore; Deiana, Luca; Carru, Ciriaco

    2008-07-01

    We present a new rapid CE method to measure adenine nucleotides adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and adenosine 5'-monophosphate (AMP) in cells. The short-end injection mode allows a decrease in the analysis time by injecting samples at the outlet end of a silica capillary closest to the detection window, reducing the migration distance. Moreover, the use of methylcellulose (MC) as run buffer additive to suppress EOF permits to further reduce the migration times of analytes. Thus, when a capillary with an effective length of 10.2 cm was used with a 60 mmol/L sodium acetate buffer pH 3.80 in the presence of 0.01% of MC, the migration time of analytes were 1.35 min for ATP, 1.85 min for ADP, and 4.64 min for AMP. These conditions gave a good reproducibility for intra- and interassay (CV <4 and 8%, respectively) and all the procedure demonstrated an excellent analytical recovery (from 98.3 to 99 %). The method suitability was proved both on red blood cells and in spermatozoa. We compared our proposed method to a spectrophotometric assay, by measuring ATP levels in 40 spermatozoa samples. The obtained data were analyzed by the Passing and Bablok regression and Bland-Altman test. PMID:18551716

  19. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  20. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  1. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  2. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Adenosine triphosphate release assay. 864.7040 Section 864.7040 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  3. CD39/Adenosine Pathway Is Involved in AIDS Progression

    PubMed Central

    Limou, Sophie; Younas, Mehwish; Kök, Ayrin; Huë, Sophie; Seddiki, Nabila; Hulin, Anne; Delaneau, Olivier; Schuitemaker, Hanneke; Herbeck, Joshua T.; Mullins, James I.; Muhtarova, Maria; Bensussan, Armand; Zagury, Jean-François; Lelievre, Jean-Daniel; Lévy, Yves

    2011-01-01

    HIV-1 infection is characterized by a chronic activation of the immune system and suppressed function of T lymphocytes. Regulatory CD4+ CD25high FoxP3+CD127low T cells (Treg) play a key role in both conditions. Here, we show that HIV-1 positive patients have a significant increase of Treg-associated expression of CD39/ENTPD1, an ectoenzyme which in concert with CD73 generates adenosine. We show in vitro that the CD39/adenosine axis is involved in Treg suppression in HIV infection. Treg inhibitory effects are relieved by CD39 down modulation and are reproduced by an adenosine-agonist in accordance with a higher expression of the adenosine A2A receptor on patients' T cells. Notably, the expansion of the Treg CD39+ correlates with the level of immune activation and lower CD4+ counts in HIV-1 infected patients. Finally, in a genetic association study performed in three different cohorts, we identified a CD39 gene polymorphism that was associated with down-modulated CD39 expression and a slower progression to AIDS. PMID:21750674

  4. Adenosine receptor modulation of seizure susceptibility in rats

    SciTech Connect

    Szot, P.

    1987-01-01

    Adenosine is considered to be a neuromodulator or cotransmitter in the periphery and CNS. This neuromodulatory action of adenosine may be observed as an anticonvulsant effect. Dose-response curves for R-phenylisopropyladenosine (PIA), cycohexyladenosine (CHA), 2-chloroadenosine (2-ClAdo), N-ethylcarboxamidoadenosine (NECA) and S-PIA were generated against PTZ seizure thresholds in the rat. The rank order of potency for adenosine agonists to elevate PTZ seizure threshold was R-PIA > 2-ClAdo > NECA > CHA > S-PIA. R-PIA was approximately 80-fold more potent than S-PIA. This 80-fold difference in potency between the diasteriomers of PIA was consistent with an A{sub 1} adenoise receptor-mediated response. The anticonvulsant action of 2-ClAdo was reversed by pretreatment with theoplylline. Chronic administration of theophylline significantly increased the specific binding of {sup 3}H-cyclohexyladenosine in membranes of the cerebral cortex and cerebellum of the rat. Chronic exposure to theophylline produced a significant increase in the densities of both the high- and low-affinity forms of A{sub 1} adenosine receptors in the cerebral cortex.

  5. Fast retrospectively triggered local pulse-wave velocity measurements in mice with CMR-microscopy using a radial trajectory

    PubMed Central

    2013-01-01

    Background The aortic pulse-wave velocity (PWV) is an important indicator of cardiovascular risk. In recent studies MRI methods have been developed to measure this parameter noninvasively in mice. Present techniques require additional hardware for cardiac and respiratory gating. In this work a robust self-gated measurement of the local PWV in mice without the need of triggering probes is proposed. Methods The local PWV of 6-months-old wild-type C57BL/6J mice (n=6) was measured in the abdominal aorta with a retrospectively triggered radial Phase Contrast (PC) MR sequence using the flow-area (QA) method. A navigator signal was extracted from the CMR data of highly asymmetric radial projections with short repetition time (TR=3 ms) and post-processed with high-pass and low-pass filters for retrospective cardiac and respiratory gating. The self-gating signal was used for a reconstruction of high-resolution Cine frames of the aortic motion. To assess the local PWV the volume flow Q and the cross-sectional area A of the aorta were determined. The results were compared with the values measured with a triggered Cartesian and an undersampled triggered radial PC-Cine sequence. Results In all examined animals a self-gating signal could be extracted and used for retrospective breath-gating and PC-Cine reconstruction. With the non-triggered measurement PWV values of 2.3±0.2 m/s were determined. These values are in agreement with those measured with the triggered Cartesian (2.4±0.2 m/s) and the triggered radial (2.3±0.2 m/s) measurement. Due to the strong robustness of the radial trajectory against undersampling an acceleration of more than two relative to the prospectively triggered Cartesian sampling could be achieved with the retrospective method. Conclusion With the radial flow-encoding sequence the extraction of a self-gating signal is feasible. The retrospective method enables a robust and fast measurement of the local PWV without the need of additional trigger hardware

  6. Total Energy CMR Production

    SciTech Connect

    Friedrich, S; Kolagani, R M

    2008-08-11

    The following outlines the optimized pulsed laser deposition (PLD) procedure used to prepare Nd{sub 0.67}Sr{sub 0.33}MnO{sub 3} (NSMO) temperature sensors at Towson University (Prof. Rajeswari Kolagani) for the LCLS XTOD Total Energy Monitor. The samples have a sharp metal/insulator transition at T {approx} 200 K and are optimized for operation at T {approx} 180 K, where their sensitivity is the highest. These samples are epitaxial multilayer structures of Si/YSZ/CeO/NSMO, where these abbreviations are defined in table 1. In this heterostructure, YSZ serves as a buffer layer to prevent deleterious chemical reactions, and also serves to de-oxygenate the amorphous SiO{sub 2} surface layer to generate a crystalline template for epitaxy. CeO and BTO serve as template layers to minimize the effects of thermal and lattice mismatch strains, respectively. More details on the buffer and template layer scheme are included in the attached manuscript accepted for publication in Sensor Letters (G. Yong et al., 2008).

  7. Feed-Forward Inhibition of CD73 and Upregulation of Adenosine Deaminase Contribute to the Loss of Adenosine Neuromodulation in Postinflammatory Ileitis

    PubMed Central

    Magalhães-Cardoso, Maria Teresa; Ferreirinha, Fátima; Dias, Ana Sofia; Pelletier, Julie

    2014-01-01

    Purinergic signalling is remarkably plastic during gastrointestinal inflammation. Thus, selective drugs targeting the “purinome” may be helpful for inflammatory gastrointestinal diseases. The myenteric neuromuscular transmission of healthy individuals is fine-tuned and controlled by adenosine acting on A2A excitatory receptors. Here, we investigated the neuromodulatory role of adenosine in TNBS-inflamed longitudinal muscle-myenteric plexus of the rat ileum. Seven-day postinflammation ileitis lacks adenosine neuromodulation, which may contribute to acceleration of gastrointestinal transit. The loss of adenosine neuromodulation results from deficient accumulation of the nucleoside at the myenteric synapse despite the fact that the increases in ATP release were observed. Disparity between ATP outflow and adenosine deficit in postinflammatory ileitis is ascribed to feed-forward inhibition of ecto-5′-nucleotidase/CD73 by high extracellular ATP and/or ADP. Redistribution of NTPDase2, but not of NTPDase3, from ganglion cell bodies to myenteric nerve terminals leads to preferential ADP accumulation from released ATP, thus contributing to the prolonged inhibition of muscle-bound ecto-5′-nucleotidase/CD73 and to the delay of adenosine formation at the inflamed neuromuscular synapse. On the other hand, depression of endogenous adenosine accumulation may also occur due to enhancement of adenosine deaminase activity. Both membrane-bound and soluble forms of ecto-5′-nucleotidase/CD73 and adenosine deaminase were detected in the inflamed myenteric plexus. These findings provide novel therapeutic targets for inflammatory gut motility disorders. PMID:25210228

  8. Mechanism of A2 adenosine receptor activation. I. Blockade of A2 adenosine receptors by photoaffinity labeling

    SciTech Connect

    Lohse, M.J.; Klotz, K.N.; Schwabe, U.

    1991-04-01

    It has previously been shown that covalent incorporation of the photoreactive adenosine derivative (R)-2-azido-N6-p-hydroxy-phenylisopropyladenosine ((R)-AHPIA) into the A1 adenosine receptor of intact fat cells leads to a persistent activation of this receptor, resulting in a reduction of cellular cAMP levels. In contrast, covalent incorporation of (R)-AHPIA into human platelet membranes, which contain only stimulatory A2 adenosine receptors, reduces adenylate cyclase stimulation via these receptors. This effect of (R)-AHPIA is specific for the A2 receptor and can be prevented by the adenosine receptor antagonist theophylline. Binding studies indicate that up to 90% of A2 receptors can be blocked by photoincorporation of (R)-AHPIA. However, the remaining 10-20% of A2 receptors are sufficient to mediate an adenylate cyclase stimulation of up to 50% of the control value. Similarly, the activation via these 10-20% of receptors occurs with a half-life that is only 2 times longer than that in control membranes. This indicates the presence of a receptor reserve, with respect to both the extent and the rate of adenylate cyclase stimulation. These observations require a modification of the models of receptor-adenylate cyclase coupling.

  9. The effects of methylmercury on motor activity are sex- and age-dependent, and modulated by genetic deletion of adenosine receptors and caffeine administration.

    PubMed

    Björklund, Olga; Kahlström, Johan; Salmi, Peter; Ogren, Sven Ove; Vahter, Marie; Chen, Jiang-Fan; Fredholm, Bertil B; Daré, Elisabetta

    2007-11-30

    Adenosine and its receptors are, as part of the brain stress response, potential targets for neuroprotective drugs. We have investigated if the adenosine receptor system affects the developmental neurotoxicity caused by the fish pollutant methylmercury (MeHg). Behavioral outcomes of low dose perinatal MeHg exposure were studied in mice where the A(1) and A(2A) adenosine receptors were either partially blocked by caffeine treatment or eliminated by genetic modification (A(1)R and A(2A)R knock-out mice). From gestational day 7 to day 7 of lactation dams were administered doses that mimic human intake via normal diet, i.e. 1microM MeHg and/or 0.3g/l caffeine in the drinking water. This exposure to MeHg resulted in a doubling of brain Hg levels in wild type females and males at postnatal day 21 (PND21). Open field analysis was performed at PND21 and 2 months of age. MeHg caused time-dependent behavioral alterations preferentially in male mice. A decreased response to amphetamine in 2-month-old males pointed to disturbances in dopaminergic functions. Maternal caffeine intake induced long-lasting changes in the offspring evidenced by an increased motor activity and a modified response to psychostimulants in adult age, irrespectively of sex. Similar alterations were observed in A(1)R knock-out mice, suggesting that adenosine A(1) receptors are involved in the alterations triggered by caffeine exposure during development. Perinatal caffeine treatment and, to some extent, genetic elimination of adenosine A(1) receptors, attenuated the behavioral consequences of MeHg in males. Importantly, also deletion of the A(2A) adenosine receptor reduced the vulnerability to MeHg, consistent with the neuroprotective effects of adenosine A(2A) receptor inactivation observed in hypoxia and Parkinson's disease. Thus, the consequences of MeHg toxicity during gestation and lactation can be reduced by adenosine A(1) and A(2A) receptor inactivation, either via their genetic deletion or by

  10. Metabolic changes of cultured DRG neurons induced by adenosine using confocal microscopy imaging

    NASA Astrophysics Data System (ADS)

    Zheng, Liqin; Huang, Yimei; Chen, Jiangxu; Wang, Yuhua; Yang, Hongqin; Zhang, Yanding; Xie, Shusen

    2012-12-01

    Adenosine exerts multiple effects on pain transmission in the peripheral nervous system. This study was performed to use confocal microscopy to evaluate whether adenosine could affect dorsal root ganglia (DRG) neurons in vitro and test which adenosine receptor mediates the effect of adenosine on DRG neurons. After adding adenosine with different concentration, we compared the metabolic changes by the real time imaging of calcium and mitochondria membrane potential using confocal microscopy. The results showed that the effect of 500 μM adenosine on the metabolic changes of DRG neurons was more significant than others. Furthermore, four different adenosine receptor antagonists were used to study which receptor mediated the influences of adenosine on the cultured DRG neurons. All adenosine receptor antagonists especially A1 receptor antagonist (DPCPX) had effect on the Ca2+ and mitochondria membrane potential dynamics of DRG neurons. The above studies demonstrated that the effect of adenosine which may be involved in the signal transmission on the sensory neurons was dose-dependent, and all the four adenosine receptors especially the A1R may mediate the transmission.

  11. Modulation of bladder function by luminal adenosine turnover and A1 receptor activation

    PubMed Central

    Prakasam, H. Sandeep; Herrington, Heather; Roppolo, James R.; Jackson, Edwin K.

    2012-01-01

    The bladder uroepithelium transmits information to the underlying nervous and musculature systems, is under constant cyclical strain, expresses all four adenosine receptors (A1, A2A, A2B, and A3), and is a site of adenosine production. Although adenosine has a well-described protective effect in several organs, there is a lack of information about adenosine turnover in the uroepithelium or whether altering luminal adenosine concentrations impacts bladder function or overactivity. We observed that the concentration of extracellular adenosine at the mucosal surface of the uroepithelium was regulated by ecto-adenosine deaminase and by equilibrative nucleoside transporters, whereas adenosine kinase and equilibrative nucleoside transporters modulated serosal levels. We further observed that enriching endogenous adenosine by blocking its routes of metabolism or direct activation of mucosal A1 receptors with 2-chloro-N6-cyclopentyladenosine (CCPA), a selective agonist, stimulated bladder activity by lowering the threshold pressure for voiding. Finally, CCPA did not quell bladder hyperactivity in animals with acute cyclophosphamide-induced cystitis but instead exacerbated their irritated bladder phenotype. In conclusion, we find that adenosine levels at both surfaces of the uroepithelium are modulated by turnover, that blocking these pathways or stimulating A1 receptors directly at the luminal surface promotes bladder contractions, and that adenosine further stimulates voiding in animals with cyclophosphamide-induced cystitis. PMID:22552934

  12. Fast-scan Cyclic Voltammetry for the Characterization of Rapid Adenosine Release

    PubMed Central

    Nguyen, Michael D.; Venton, B. Jill

    2014-01-01

    Adenosine is a signaling molecule and downstream product of ATP that acts as a neuromodulator. Adenosine regulates physiological processes, such as neurotransmission and blood flow, on a time scale of minutes to hours. Recent developments in electrochemical techniques, including fast-scan cyclic voltammetry (FSCV), have allowed direct detection of adenosine with sub-second temporal resolution. FSCV studies have revealed a novel mode of rapid signaling that lasts only a few seconds. This rapid release of adenosine can be evoked by electrical or mechanical stimulations or it can be observed spontaneously without stimulation. Adenosine signaling on this time scale is activity dependent; however, the mode of release is not fully understood. Rapid adenosine release modulates oxygen levels and evoked dopamine release, indicating that adenosine may have a rapid modulatory role. In this review, we outline how FSCV can be used to detect adenosine release, compare FSCV with other techniques used to measure adenosine, and present an overview of adenosine signaling that has been characterized using FSCV. These studies point to a rapid mode of adenosine modulation, whose mechanism and function will continue to be characterized in the future. PMID:26900429

  13. Harnessing nature's own cardiac defense mechanism with acadesine, an adenosine regulating agent: importance of the endothelium.

    PubMed

    Engler, R L

    1994-05-01

    Although the effects of adenosine on the heart, including the clinical suppression of cardiac arrhythmias, have been recognized for more than half a century, it is only in the last decade that the therapeutic potential of adenosine has been recognized. Research related to the clinical application of adenosine has concentrated on two areas. The first came directly from early observations about the use of adenosine in treating cardiac arrhythmias, in particular supraventricular tachycardias. The second relates to the use of adenosine to protect the heart from the deleterious consequences of myocardial ischemia and reperfusion. This review will focus on the latter cardioprotective properties of adenosine, particularly those shown by a novel group of drugs termed adenosine regulating agents, the prototype of which is acadesine (Protara).

  14. Exogenous adenosine 5'-phosphoramidate behaves as a signal molecule in plants; it augments metabolism of phenylpropanoids and salicylic acid in Arabidopsis thaliana seedlings.

    PubMed

    Pietrowska-Borek, Małgorzata; Nuc, Katarzyna; Guranowski, Andrzej

    2015-09-01

    Cells contain various congeners of the canonical nucleotides. Some of these accumulate in cells under stress and may function as signal molecules. Their cellular levels are enzymatically controlled. Previously, we demonstrated a signaling function for diadenosine polyphosphates and cyclic nucleotides in Arabidopsis thaliana and grape, Vitis vinifera. These compounds increased the expression of genes for and the specific activity of enzymes of phenylpropanoid pathways resulting in the accumulation of certain products of these pathways. Here, we show that adenosine 5'-phosphoramidate, whose level can be controlled by HIT-family proteins, induced similar effects. This natural nucleotide, when added to A. thaliana seedlings, activated the genes for phenylalanine:ammonia lyase, 4-coumarate:coenzyme A ligase, cinnamate-4-hydroxylase, chalcone synthase, cinnamoyl-coenzyme A:NADP oxidoreductase and isochorismate synthase, which encode proteins catalyzing key reactions of phenylpropanoid pathways, and caused accumulation of lignins, anthocyanins and salicylic acid. Adenosine 5'-phosphofluoridate, a synthetic congener of adenosine 5'-phosphoramidate, behaved similarly. The results allow us to postulate that adenosine 5'-phosphoramidate should be considered as a novel signaling molecule.

  15. Efficacy of cimetidin in the prevention of ulcer formation in the stomach during immobilization stress

    NASA Technical Reports Server (NTRS)

    Dorofeyev, G. I.; Litovskiy, I. A.; Gavrovskaya, L. K.; Ivashkin, V. T.

    1982-01-01

    The effect of stress on the formation of ulcers in the mucous membrane of the stomach, the increase in cyclic adenosine monophosphate level in the gastric tissues, and parietal cell structure alteration. Use of cimetidin prevents these effects

  16. [99mTc-MIBI myocardial tomography with intravenous infusion of adenosine triphosphate in the diagnosis of coronary artery disease].

    PubMed

    Kumano, S

    1996-02-01

    To evaluate its feasibility, safety and diagnostic accuracy, 99mTc-MIBI myocardial tomography with adenosine triphosphate (ATP) infusion (0.16 mg/kg/min for 5 min) was performed 100 consecutive patients using the stress/rest one day protocol. None of the patients required treatment with aminophylline during the study. The sensitivity and specificity for detecting patients with coronary artery disease were 97% and 71%, respectively. Those for detecting individual coronary lesion (> or = 75% stenosis) were 92% and 89%, respectively. The high hepatic uptake of 99mTc-MIBI causes artifactual perfusion defects in the inferior myocardial wall, particularly on ATP stress images. In order to reduce this artifactual phenomenon, the interval time between injection and stress imaging must be increased. PMID:8721103

  17. Adenosine Inhibition of Mesopontine Cholinergic Neurons: Implications for EEG Arousal

    PubMed Central

    Rainnie, Donald G.; Grunze, Heinz C. R.; McCarley, Robert W.; Greene, Robert W.

    2013-01-01

    Increased discharge activity of mesopontine cholinergic neurons participates in the production of electroencephalographic (EEG) arousal; such arousal diminishes as a function of the duration of prior wakefulness or of brain hyperthermia. Whole-cell and extracellular recordings in a brainstem slice show that mesopontine cholinergic neurons are under the tonic inhibitory control of endogenous adenosine, a neuromodulator released during brain metabolism. This inhibitory tone is mediated postsynaptically by an inwardly rectifying potassium conductance and by an inhibition of the hyperpolarization-activated current. These data provide a coupling mechanism linking neuronal control of EEG-arousal with the effects of prior wakefulness, brain hyperthermia, and the use of the adenosine receptor blockers caffeine and theophylline. PMID:8303279

  18. Adenosine: an endogenous mediator in the pathogenesis of psoriasis*

    PubMed Central

    Festugato, Moira

    2015-01-01

    It is known that inflammatory and immune responses protect us from the invasion of micro-organisms and eliminate "wastes" from the injured sites, but they may also be responsible for significant tissue damage. Adenosine, as a purine nucleoside, which is produced in inflamed or injured sites, fulfills its role in limiting tissue damage. Although, it may have a pleiotropic effect, which signals it with a proinflammatory state in certain situations, it can be considered a potent anti-inflammatory mediator. The effects of adenosine, which acts through its receptors on T cell, on mast cell and macrophages, on endothelial cells, on neutrophils and dendritic cells, as they indicate TNF-alpha and cytokines, show that this mediator has a central role in the pathogenesis of psoriasis. The way it acts in psoriasis will be reviewed in this study. PMID:26734868

  19. Structure–Activity Relationships of 9-Alkyladenine and Ribose-Modified Adenosine Derivatives at Rat A3 Adenosine Receptors†

    PubMed Central

    Jacobson, Kenneth A.; Siddiqi, Suhaib M.; Olah, Mark E.; Ji, Xiao-duo; Melman, Neli; Bellamkonda, Kamala; Meshulam, Yakov; Stiles, Gary L.; Kim, Hea O.

    2012-01-01

    9-Alkyladenine derivatives and ribose-modified N6-benzyladenosine derivatives were synthesized in an effort to identify selective ligands for the rat A3 adenosine receptor and leads for the development of antagonists. The derivatives contained structural features previously determined to be important for A3 selectivity in adenosine derivatives, such as an N6-(3-iodobenzyl) moiety, and were further substituted at the 2-position with halo, amino, or thio groups. Affinity was determined in radioligand binding assays at rat brain A3 receptors stably expressed in Chinese hamster ovary (CHO) cells, using [125I]AB-MECA (N6-(4-amino-3-iodobenzyl)adenosine-5′-(N-methyluronamide)), and at rat brain A1 and A2a receptors using [3H]-N6-PIA ((R)-N6-phenylisopropyladenosine) and [3H]CGS 21680 (2-[[[4-(2-carboxyethyl)-phenyl]ethyl]amino]-5′-(N-ethylcarbamoyl)adenosine), respectively. A series of N6-(3-iodobenzyl) 2-amino derivatives indicated that a small 2-alkylamino group, e.g., methylamino, was favored at A3 receptors. N6-(3-Iodobenzyl)-9-methyl-2-(methylthio)adenine was 61-fold more potent than the corresponding 2-methoxy ether at A3 receptors and of comparable affinity at A1 and A2a receptors, resulting in a 3–6-fold selectivity for A3 receptors. A pair of chiral N6-(3-iodobenzyl) 9-(2,3-dihydroxypropyl) derivatives showed stereoselectivity, with the R-enantiomer favored at A3 receptors by 5.7-fold. 2-Chloro-9-(β-d-erythrofuranosyl)-N6-(3-iodobenzyl)adenine had a Ki value at A3 receptors of 0.28 µM. 2-Chloro-9-[2-amino-2,3-dideoxy-β-d-5-(methylcarbamoyl)-arabinofuranosyl]-N6-(3-iodobenzyl)adenine was moderately selective for A1 and A3 vs A2a receptors. A 3′-deoxy analogue of a highly A3-selective adenosine derivative retained selectivity in binding and was a full agonist in the inhibition of adenylyl cyclase mediated via cloned rat A3 receptors expressed in CHO cells. The 3′-OH and 4′-CH2OH groups of adenosine are not required for activation at A3 receptors. A

  20. Targeting the A2B adenosine receptor during gastrointestinal ischemia and inflammation

    PubMed Central

    Eltzschig, Holger K; Rivera-Nieves, Jesus; Colgan, Sean P

    2014-01-01

    Extracellular adenosine functions as an endogenous distress signal via activation of four distinct adenosine receptors (A1, A2A, A2B and A3). Conditions of limited oxygen availability or acute inflammation lead to elevated levels of extracellular adenosine and enhanced signaling events. This relates to a combination of four mechanisms: i) increased production of adenosine via extracellular phosphohydrolysis of precursor molecules (particularly ATP and ADP); ii) increased expression and signaling via hypoxia-induced adenosine receptors, particularly the A2B adenosine receptor; iii) attenuated uptake from the extracellular towards the intracellular compartment; and iv) attenuated intracellular metabolism. Due to their large surface area, mucosal organs are particularly prone to hypoxia and ischemia associated inflammation. Therefore, it is not surprising that adenosine production and signaling plays a central role in attenuating tissue inflammation and injury during intestinal ischemia or inflammation. In fact, recent studies combining pharmacological and genetic approaches demonstrated that adenosine signaling via the A2B adenosine receptor dampens mucosal inflammation and tissue injury during intestinal ischemia or experimental colitis. This review outlines basic principles of extracellular adenosine production, signaling, uptake and metabolism. In addition, we discuss the role of this pathway in dampening hypoxia-elicited inflammation, specifically in the setting of intestinal ischemia and inflammation. PMID:19769545

  1. Ticagrelor potentiates adenosine-induced stimulation of neutrophil chemotaxis and phagocytosis.

    PubMed

    Alsharif, Khalaf F; Thomas, Mark R; Judge, Heather M; Khan, Haroon; Prince, Lynne R; Sabroe, Ian; Ridger, Victoria C; Storey, Robert F

    2015-08-01

    In the PLATO study, ticagrelor was associated with fewer pulmonary infections and subsequent deaths than clopidogrel. Neutrophils are a first-line defence against bacterial lung infection; ticagrelor inhibits cellular uptake of adenosine, a known regulator of neutrophil chemotaxis and phagocytosis. We assessed whether the inhibition of adenosine uptake by ticagrelor influences neutrophil chemotaxis and phagocytosis. Neutrophils and erythrocytes were isolated from healthy volunteers. Concentration-dependent effects of adenosine on IL-8-induced neutrophil chemotaxis were investigated and the involved receptors identified using adenosine receptor antagonists. The modulatory effects of ticagrelor on adenosine-mediated changes in neutrophil chemotaxis and phagocytosis of Streptococcus pneumoniae were determined in the presence of erythrocytes to replicate physiological conditions of cellular adenosine uptake. Low-concentration adenosine (10(-8)M) significantly increased IL-8-induced neutrophil chemotaxis (% neutrophil chemotaxis: adenosine 28.7%±4.4 vs. control 22.6%±2.4; p<0.01) by acting on the high-affinity A1 receptor. Erythrocytes attenuated the effect of adenosine, although this was preserved by ticagrelor and dipyridamole (another inhibitor of adenosine uptake) but not by control or by cangrelor. Similarly, in the presence of erythrocytes, a low concentration of adenosine (10(-8)M) significantly increased neutrophil phagocytic index compared to control when ticagrelor was present (37.6±6.6 vs. 28.0±6.6; p=0.028) but had no effect in the absence of ticagrelor. We therefore conclude that the inhibition of cellular adenosine reuptake by ticagrelor potentiates the effects of a nanomolar concentration of adenosine on neutrophil chemotaxis and phagocytosis. This represents a potential mechanism by which ticagrelor could influence host defence against bacterial lung infection.

  2. Ticagrelor potentiates adenosine-induced stimulation of neutrophil chemotaxis and phagocytosis

    PubMed Central

    Alsharif, Khalaf F.; Thomas, Mark R.; Judge, Heather M.; Khan, Haroon; Prince, Lynne R.; Sabroe, Ian; Ridger, Victoria C.; Storey, Robert F.

    2015-01-01

    In the PLATO study, ticagrelor was associated with fewer pulmonary infections and subsequent deaths than clopidogrel. Neutrophils are a first-line defence against bacterial lung infection; ticagrelor inhibits cellular uptake of adenosine, a known regulator of neutrophil chemotaxis and phagocytosis. We assessed whether the inhibition of adenosine uptake by ticagrelor influences neutrophil chemotaxis and phagocytosis. Neutrophils and erythrocytes were isolated from healthy volunteers. Concentration-dependent effects of adenosine on IL-8-induced neutrophil chemotaxis were investigated and the involved receptors identified using adenosine receptor antagonists. The modulatory effects of ticagrelor on adenosine-mediated changes in neutrophil chemotaxis and phagocytosis of Streptococcus pneumoniae were determined in the presence of erythrocytes to replicate physiological conditions of cellular adenosine uptake. Low-concentration adenosine (10− 8 M) significantly increased IL-8-induced neutrophil chemotaxis (% neutrophil chemotaxis: adenosine 28.7% ± 4.4 vs. control 22.6% ± 2.4; p < 0.01) by acting on the high-affinity A1 receptor. Erythrocytes attenuated the effect of adenosine, although this was preserved by ticagrelor and dipyridamole (another inhibitor of adenosine uptake) but not by control or by cangrelor. Similarly, in the presence of erythrocytes, a low concentration of adenosine (10− 8 M) significantly increased neutrophil phagocytic index compared to control when ticagrelor was present (37.6 ± 6.6 vs. 28.0 ± 6.6; p = 0.028) but had no effect in the absence of ticagrelor. We therefore conclude that the inhibition of cellular adenosine reuptake by ticagrelor potentiates the effects of a nanomolar concentration of adenosine on neutrophil chemotaxis and phagocytosis. This represents a potential mechanism by which ticagrelor could influence host defence against bacterial lung infection. PMID:25869515

  3. Effects of adenosine metabolism in astrocytes on central nervous system oxygen toxicity.

    PubMed

    Chen, Yu-liang; Zhang, Ya-nan; Wang, Zhong-zhuang; Xu, Wei-gang; Li, Run-ping; Zhang, Jun-dong

    2016-03-15

    Hyperbaric oxygen (HBO) is widely used in military operations, especially underwater missions. However, prolonged and continuous inhalation of HBO can cause central nervous system oxygen toxicity (CNS-OT), which greatly limits HBO's application. The regulation of astrocytes to the metabolism of adenosine is involved in epilepsy. In our study, we aimed to observe the effects of HBO exposure on the metabolism of adenosine in the brain. Furthermore, we aimed to confirm the possible mechanism underlying adenosine's mediation of the CNS-OT. Firstly, anesthetized rats exposed to 5 atm absolute HBO for 80 min. The concentrations of extracellular adenosine, ATP, ADP, and AMP were detected. Secondly, free-moving rats were exposed to HBO at the same pressure for 20 min, and the activities of 5'-nucleotidase and ADK in brain tissues were measured. For the mechanism studies, we observed the effects of a series of different doses of drugs related to adenosine metabolism on the latency of CNS-OT. Results showed HBO exposure could increase adenosine content by inhibiting ADK activity and improving 5'-nucleotidase activity. And adenosine metabolism during HBO exposure may be a protective response against HBO-induced CNS-OT. Moreover, the improvement of adenosine concentration, activation of adenosine A1R, or suppression of ADK and adenosine A2AR, which are involved in the prevention of HBO-induced CNS-OT. This is the first study to demonstrate HBO exposure regulated adenosine metabolism in the brain. Adenosine metabolism and adenosine receptors are related to HBO-induced CNS-OT development. These results will provide new potential targets for the termination or the attenuation of CNS-OT. PMID:26806404

  4. Pharmacology of the Adenosine A3 Receptor in the Vasculature and Essential Hypertension

    PubMed Central

    Ho, Ming-Fen; Low, Leanne M.; Rose’Meyer, Roselyn B.

    2016-01-01

    Background Essential hypertension is considered to be a multifactorial disorder and its aetiology has yet to be clearly identified. As the adenosine receptors have a significant role in mediating vasodilation, alterations in their structures or signalling pathways may be involved in the development of hypertension. This study aimed to measure the expression of adenosine A3 receptors in a range of cardiovascular tissues and determine whether they could be altered with essential hypertension, and to functionally test responses to adenosine A3 receptor agonists in coronary blood vessels using the isolated perfused heart preparation. Methods mRNA samples from cardiovascular tissues and a range of blood vessels were collected from 10 week old male spontaneously hypertensive rats and age-gender matched Wistar rats (n = 8). The Langendorff heart perfusion preparation was used to characterise adenosine A3 receptor mediated coronary vasodilation in the rat heart. Results Adenosine A3 receptor agonists induced coronary vasodilation. The expression of adenosine A3 receptors in cardiovascular tissues was altered in a tissue-specific pattern. Specifically, down-regulation of adenosine A3 receptor expression occurred in hypertensive hearts, which might be associated with attenuated vasodilator responses observed in coronary vessels to adenosine A3 receptor agonists. Conclusions This study demonstrated alterations in the expression of adenosine A3 receptors occurred in a tissue specific mode, and reduced adenosine A3 receptor mediated coronary vasodilation in hearts from spontaneously hypertensive rats. Our findings with regard to changes in the adenosine A3 receptor in hypertensive hearts suggest that adenosine A3 receptor might play a role in the physiopathology of essential hypertension and potentially open the way to pharmacologic manipulation of vasomotor activity by the use of adenosine A3 receptor agonists. PMID:26907173

  5. Identification of widespread adenosine nucleotide binding in Mycobacterium tuberculosis

    SciTech Connect

    Ansong, Charles; Ortega, Corrie; Payne, Samuel H.; Haft, Daniel H.; Chauvigne-Hines, Lacie M.; Lewis, Michael P.; Ollodart, Anja R.; Purvine, Samuel O.; Shukla, Anil K.; Fortuin, Suereta; Smith, Richard D.; Adkins, Joshua N.; Grundner, Christoph; Wright, Aaron T.

    2013-01-24

    The annotation of protein function is almost completely performed by in silico approaches. However, computational prediction of protein function is frequently incomplete and error prone. In Mycobacterium tuberculosis (Mtb), ~25% of all genes have no predicted function and are annotated as hypothetical proteins. This lack of functional information severely limits our understanding of Mtb pathogenicity. Current tools for experimental functional annotation are limited and often do not scale to entire protein families. Here, we report a generally applicable chemical biology platform to functionally annotate bacterial proteins by combining activity-based protein profiling (ABPP) and quantitative LC-MS-based proteomics. As an example of this approach for high-throughput protein functional validation and discovery, we experimentally annotate the families of ATP-binding proteins in Mtb. Our data experimentally validate prior in silico predictions of >250 ATPases and adenosine nucleotide-binding proteins, and reveal 73 hypothetical proteins as novel ATP-binding proteins. We identify adenosine cofactor interactions with many hypothetical proteins containing a diversity of unrelated sequences, providing a new and expanded view of adenosine nucleotide binding in Mtb. Furthermore, many of these hypothetical proteins are both unique to Mycobacteria and essential for infection, suggesting specialized functions in mycobacterial physiology and pathogenicity. Thus, we provide a generally applicable approach for high throughput protein function discovery and validation, and highlight several ways in which application of activity-based proteomics data can improve the quality of functional annotations to facilitate novel biological insights.

  6. Agonist Derived Molecular Probes for A2A Adenosine Receptors

    PubMed Central

    Jacobson, Kenneth A.; Pannell, Lewis K.; Ji, Xiao-duo; Jarvis, Michael F.; Williams, Michael; Hutchison, Alan J.; Barrington, William W.; Stiles, Gary L.

    2011-01-01

    The adenosine agonist 2-(4-(2-carboxyethyl)phenylethylamino)-5′-N-ethylcarboxamidoadenosine (CGS21680) was recently reported to be selective for the A2A adenosine receptor subtype, which mediates its hypotensive action. To investigate structurelactivity relationships at a distal site, CGS21680 was derivatized using a functionalized congener approach. The carboxylic group of CGS21680 has been esterified to form a methyl ester, which was then treated with ethylenediamine to produce an amine congener. The amine congener was an intermediate for acylation reactions, in which the reactive acyl species contained a reported group, or the precursor for such. For radioiodination, derivatives of p-hydroxyphenylpropionic, 2-thiophenylacetic, and p-aminophenylacetic acids were prepared. The latter derivative (PAPA-APEC) was iodinated electrophilically using [125I]iodide resulting in a radioligand which was used for studies of competition of binding to striatal A, adenosine receptors in bovine brain. A biotin conjugate and an aryl sulfonate were at least 350-fold selective for A, receptors. For spectroscopic detection, a derivative of the stable free radical tetramethyl-1-piperidinyloxy (TEMPO) was prepared. For irreversible inhibition of receptors, meta- and para-phenylenediisothiocyanate groups were incorporated in the analogs. We have demonstrated that binding at A2A receptors is relatively insensitive to distal structural changes at the 2-position, and we report high affinity molecular probes for receptor characterization by radioactive, spectroscopic and affinity labelling methodology. PMID:2561548

  7. Adenosine 5′-monophosphate ameliorates D-galactosamine/lipopolysaccharide-induced liver injury through an adenosine receptor-independent mechanism in mice

    PubMed Central

    Zhan, Y; Wang, Z; Yang, P; Wang, T; Xia, L; Zhou, M; Wang, Y; Wang, S; Hua, Z; Zhang, J

    2014-01-01

    D-galactosamine (GalN)/lipopolysaccharide (LPS)-induced lethality and acute liver failure is dependent on endogenously produced inflammatory cytokines. Adenosine has been proven to be a central role in the regulation of inflammatory response. It is not entirely clear that which adenosine action is actually crucial to limiting inflammatory tissue destruction. Here we showed that GalN/LPS challenge elevated hepatic adenosine and induced lethality in adenosine receptor-deficient mice with equal efficiency as wild-type mice. In GalN/LPS-treated mice, pretreatment with adenosine 5′-monophosphate (5′-AMP) significantly elevated hepatic adenosine level and reduced mortality through decreasing cytokine and chemokine production. In RAW264.7 cells, 5′-AMP treatment inhibited the production of inflammatory cytokines, which is not mediated through adenosine receptors. 5′-AMP failed to attenuate LPS-induced nuclear factor-κB (NF-κB) p65 nuclear translocation, but reduced LPS-induced recruitment of NF-κB p65 to inflammatory gene promoters and decreased LPS-induced enrichment of H3K4 dimethylation at the tumor necrosis factor-α (TNF-α) promoter, which was involved in 5′-AMP-induced elevation of cellular adenosine and a decline of methylation potential. In vitro biochemical analysis revealed that adenosine directly attenuated recruitment of NF-κB to the TNF-α and interleukin-6 promoters. Our findings demonstrate that 5′-AMP-inhibiting inflammatory response is not mediated by adenosine receptors and it may represent a potential protective agent for amelioration of LPS-induced liver injury. PMID:24407238

  8. Supplemental fat for dairy calves during mild cold stress.

    PubMed

    Litherland, N B; Da Silva, D N L; LaBerge, R J; Schefers, J; Kertz, A

    2014-05-01

    Eighty-one Holstein and Holstein-cross dairy calves fed calf milk replacer (CMR) were used to determine response to increasing amounts of supplemental fat during mild cold stress. Calves (n=27) were randomly assigned to 1 of 3 treatments: (1) low fat [LF; 28% crude protein:15% fat milk replacer (28:15 MR)]; (2) medium fat [MF; 28:15 MR+113 g/d of commercial fat supplement (FS)]; (3) high fat (HF; 28:15 MR+227 g/d of FS). The MF and HF calves received FS from d 2 to 21, and all calves were fed LF from d 22 to 49. The CMR was fed at 1.4% of birth body weight (BBW) from d 1 to 10, at 1.8% of BBW from d 11 to 42, and at 0.9% of BBW from d 43 to 49. Calves were weaned on d 49 and remained in hutches until d 56. The CMR was reconstituted to 13% solids. Calves were fed a commercial starter grain (19.2% crude protein on a dry matter basis) ad libitum and offered warm water after CMR feeding. Calves were fed CMR twice daily at 0630 and 1730 h in hutches bedded with straw. Starter intake, CMR intake, and ambient temperature were measured daily, and body weight (BW), hip height, and body length were measured weekly. Data were analyzed using PROC MIXED in SAS (SAS Institute Inc., Cary, NC) as a randomized design with linear and quadratic contrasts. Calf BBW averaged 42.0 ± 1.0 kg, total serum protein averaged 5.8 ± 0.1mg/dL, and birth ambient temperature averaged 5.0 ± 1.1°C. Feeding FS increased metabolizable energy intake (MEI) over maintenance but decreased efficiency of conversion of BW gain:MEI. Starter intake by LF calves was greatest until the beginning of weaning, after which starter intake was similar among treatments. Because of higher starter intake, total MEI was similar among treatments. Feed efficiency through d 49 was greater for calves fed MF and HF. Average daily gain during fat supplementation was greater for MF and HF than for LF. Lack of increase in BW gain and feed efficiency between MF and HF treatments indicated that HF did not result in advantages

  9. Supplemental fat for dairy calves during mild cold stress.

    PubMed

    Litherland, N B; Da Silva, D N L; LaBerge, R J; Schefers, J; Kertz, A

    2014-05-01

    Eighty-one Holstein and Holstein-cross dairy calves fed calf milk replacer (CMR) were used to determine response to increasing amounts of supplemental fat during mild cold stress. Calves (n=27) were randomly assigned to 1 of 3 treatments: (1) low fat [LF; 28% crude protein:15% fat milk replacer (28:15 MR)]; (2) medium fat [MF; 28:15 MR+113 g/d of commercial fat supplement (FS)]; (3) high fat (HF; 28:15 MR+227 g/d of FS). The MF and HF calves received FS from d 2 to 21, and all calves were fed LF from d 22 to 49. The CMR was fed at 1.4% of birth body weight (BBW) from d 1 to 10, at 1.8% of BBW from d 11 to 42, and at 0.9% of BBW from d 43 to 49. Calves were weaned on d 49 and remained in hutches until d 56. The CMR was reconstituted to 13% solids. Calves were fed a commercial starter grain (19.2% crude protein on a dry matter basis) ad libitum and offered warm water after CMR feeding. Calves were fed CMR twice daily at 0630 and 1730 h in hutches bedded with straw. Starter intake, CMR intake, and ambient temperature were measured daily, and body weight (BW), hip height, and body length were measured weekly. Data were analyzed using PROC MIXED in SAS (SAS Institute Inc., Cary, NC) as a randomized design with linear and quadratic contrasts. Calf BBW averaged 42.0 ± 1.0 kg, total serum protein averaged 5.8 ± 0.1mg/dL, and birth ambient temperature averaged 5.0 ± 1.1°C. Feeding FS increased metabolizable energy intake (MEI) over maintenance but decreased efficiency of conversion of BW gain:MEI. Starter intake by LF calves was greatest until the beginning of weaning, after which starter intake was similar among treatments. Because of higher starter intake, total MEI was similar among treatments. Feed efficiency through d 49 was greater for calves fed MF and HF. Average daily gain during fat supplementation was greater for MF and HF than for LF. Lack of increase in BW gain and feed efficiency between MF and HF treatments indicated that HF did not result in advantages

  10. Multi-vendor, multicentre comparison of contrast-enhanced SSFP and T2-STIR CMR for determining myocardium at risk in ST-elevation myocardial infarction

    PubMed Central

    Nordlund, David; Klug, Gert; Heiberg, Einar; Koul, Sasha; Larsen, Terje H.; Hoffmann, Pavel; Metzler, Bernhard; Erlinge, David; Atar, Dan; Aletras, Anthony H.; Carlsson, Marcus; Engblom, Henrik; Arheden, Håkan

    2016-01-01

    Aims Myocardial salvage, determined by cardiac magnetic resonance imaging (CMR), is used as end point in cardioprotection trials. To calculate myocardial salvage, infarct size is related to myocardium at risk (MaR), which can be assessed by T2-short tau inversion recovery (T2-STIR) and contrast-enhanced steady-state free precession magnetic resonance imaging (CE-SSFP). We aimed to determine how T2-STIR and CE-SSFP perform in determining MaR when applied in multicentre, multi-vendor settings. Methods and results A total of 215 patients from 17 centres were included after percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction. CMR was performed within 1–8 days. These patients participated in the MITOCARE or CHILL-MI cardioprotection trials. Additionally, 8 patients from a previous study, imaged 1 day post-CMR, were included. Late gadolinium enhancement, T2-STIR, and CE-SSFP images were acquired on 1.5T MR scanners (Philips, Siemens, or GE). In 65% of the patients, T2-STIR was of diagnostic quality compared with 97% for CE-SSFP. In diagnostic quality images, there was no difference in MaR by T2-STIR and CE-SSFP (bias: 0.02 ± 6%, P = 0.96, r2 = 0.71, P < 0.001), or between treatment and control arms. No change in size or quality of MaR nor ability to identify culprit artery was seen over the first week after the acute event (P = 0.44). Conclusion In diagnostic quality images, T2-STIR and CE-SSFP provide similar estimates of MaR, were constant over the first week, and were not affected by treatment. CE-SSFP had a higher degree of diagnostic quality images compared with T2 imaging for sequences from two out of three vendors. Therefore, CE-SSFP is currently more suitable for implementation in multicentre, multi-vendor clinical trials. PMID:27002140

  11. [Effects of dopamine and adenosine on regulation of water-electrolyte exchange in Amoeba proteus].

    PubMed

    Bagrov, Ia Iu; Manusova, N B

    2014-01-01

    Dopamine and adenosine both regulate transport of sodium chloride in the renal tubules in mammals. We have studied the effect of dopamine and adenosine on spontaneous activity of contractile vacuole of Amoeba proteous. Both substances stimulated contractile vacuole. The effect of dopamine was suppressed by D2 receptor antagonist, haloperidol, but not by D1 antagonist, SCH 39166. Adenylate cyclase inhibitor, 2.5-dideoxyadenosine, suppressed the effect of dopamine, but not of adenosine. Inhibitor of protein kinase C, staurosporine, in contrast, blocked the effect of adenosine, but not dopamine. Notably, dopamine opposed effect of adenosine and vice versa. These results suggest that similar effects of dopamine and adenosine could be mediated by different intracellulare mechanisms.

  12. Adenosine A1 receptors determine effects of caffeine on total fluid intake but not caffeine appetite.

    PubMed

    Rieg, Timo; Schnermann, Jürgen; Vallon, Volker

    2007-01-26

    Adenosine A1 receptor wild-type (+/+) and knockout (-/-) mice were used to elucidate the role of adenosine A1 receptors in caffeine self-administration in a two-bottle choice test and in the effect of caffeine on total fluid intake and plasma renin concentration. With access to water only, adenosine A1 receptor -/- mice showed greater basal fluid intake and greater plasma renin concentration than +/+ mice. Free access to both water and a caffeinated solution (30 mg/100 ml) for 14 days increased total fluid intake only in adenosine A1 receptor +/+ mice (by 23+/-3%), and both total fluid intake and plasma renin concentration were no longer different between genotypes. Mean intake of water and caffeinated solution was not different between adenosine A1 receptor +/+ and -/- mice. These data reveal that adenosine A1 receptors do not contribute to caffeine consumption, but determine the effects of caffeine on fluid intake and plasma renin concentration. PMID:17126319

  13. Syzygium cumini extract decrease adenosine deaminase, 5'nucleotidase activities and oxidative damage in platelets of diabetic patients.

    PubMed

    De Bona, Karine S; Bellé, Luziane P; Sari, Marcel H; Thomé, Gustavo; Schetinger, Maria R C; Morsch, Vera M; Boligon, Aline; Athayde, Margareth L; Pigatto, Aline S; Moretto, Maria B

    2010-01-01

    Diabetes mellitus, a chronic metabolic disorder, has assumed epidemic proportions and its long-term complications can have devastating consequences. The oxidative stress in diabetes was greatly increased due to prolonged exposure to hyperglycemia and impairment of oxidant/antioxidant equilibrium. Syzygium cumini is being widely used to treat diabetes by the traditional practitioners over many centuries. Adenosine deaminase (ADA) and 5'-Nucleotidase (5'NT) are enzymes of purine nucleoside metabolism that play an important role in the regulation of adenosine (Ado) levels. In this study, we investigated the effect of Syzygium cumini aqueous leaves extract (ASc) on ADA and 5'NT activities and on parameters of oxidative stress under in vitro conditions, using platelets of patients with Type 2 diabetes mellitus. Platelet-Rich Plasma (PRP) was assayed by ADA, 5'NT, Catalase (CAT), Superoxide Dismutase (SOD) activities and Thiobarbituric acid reactive substances (TBARS) levels. We observed that ADA, 5'NT activities and TBARS levels were significantly higher when compared to the control group, and ASc (100 and 200 μg/mL) prevented these effects. Our study demonstrates that ASc was able to remove oxidant species generated in diabetic conditions and modulates in the Ado levels. Then, ASc may promote a compensatory response in platelet function, improving the susceptibility-induced by the diabetes mellitus. PMID:21063110

  14. Estimation of skeletal muscle interstitial adenosine during forearm dynamic exercise in humans

    NASA Technical Reports Server (NTRS)

    Costa, F.; Heusinkveld, J.; Ballog, R.; Davis, S.; Biaggioni, I.

    2000-01-01

    It has been proposed that adenosine is a metabolic signal that triggers activation of muscle afferents involved in the exercise pressor reflex. Furthermore, exogenous adenosine induces sympathetic activation that mimics the exercise pressor reflex, and blockade of adenosine receptors inhibits sympathetic activation induced by exercise. Thus, we hypothesize that adenosine is released locally by the muscle during exercise. We used microdialysis probes, placed in the flexor digitorium superficialis muscle, to estimate muscle interstitial adenosine levels in humans. We estimated resting in vivo muscle interstitial adenosine concentrations (0.292+/-0.058 micromol/L, n=4) by perfusing increasing concentrations of adenosine to determine the gradient produced in the dialysate. Muscle interstitial adenosine concentrations increased from 0.23+/-0.04 to 0.82+/-0.14 micromol/L (n=14, P<0.001) during intermittent dynamic exercise at 50% of maximal voluntary contraction. Lactate increased from 0.8+/-0.1 to 2.3+/-0.3 mmol/L (P<0.001). Lower intensity (15% maximal voluntary contraction) intermittent dynamic exercise increased adenosine concentrations from 0.104+/-0.02 to 0.42+/-0.16 micromol/L (n=7). The addition of ischemia to this low level of exercise produced a greater increase in adenosine (from 0.095+/-0.02 to 0.48+/-0.2 micromol/L) compared with nonischemic exercise (0. 095+/-0.02 to 0.25+/-0.12 micromol/L). These results indicate that microdialysis is useful in estimating adenosine concentrations and in reflecting changes in muscle interstitial adenosine during dynamic exercise in humans.

  15. Cytoprotective effects of adenosine and inosine in an in vitro model of acute tubular necrosis

    PubMed Central

    Módis, Katalin; Gerő, Domokos; Nagy, Nóra; Szoleczky, Petra; Tóth, Zoltán Dóri; Szabó, Csaba

    2009-01-01

    Background and purpose: We have established an in vitro model of acute tubular necrosis in rat kidney tubular cells, using combined oxygen-glucose deprivation (COGD) and screened a library of 1280 pharmacologically active compounds for cytoprotective effects. Experimental approach: We used in vitro cell-based, high throughput, screening, with cells subjected to COGD using hypoxia chambers, followed by re-oxygenation. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and the Alamar Blue assay measured mitochondrial respiration and the lactate dehydrogenase assay was used to indicate cell death. ATP levels were measured using a luminometric assay. Key results: Adenosine markedly reduced cellular injury, with maximal cytoprotective effect at 100 µM and an EC50 value of 14 µM. Inosine was also found to be cytoprotective. The selective A3 adenosine receptor antagonist MRS 1523 attenuated the protective effects of adenosine and inosine, while an A3 adenosine receptor agonist provided a partial protective effect. Adenosine deaminase inhibition attenuated the cytoprotective effect of adenosine but not of inosine during COGD. Inhibition of adenosine kinase reduced the protective effects of both adenosine and inosine during COGD. Pretreatment of the cells with adenosine or inosine markedly protected against the fall in cellular ATP content in the cells subjected to COGD. Conclusions and implications: The cytoprotection elicited by adenosine and inosine in a model of renal ischaemia involved both interactions with cell surface adenosine receptors on renal tubular epithelial cells and intracellular metabolism and conversion of adenosine to ATP. PMID:19906119

  16. Adenosine stimulates Ca2+ fluxes and increases cytosolic free Ca2+ in cultured rat mesangial cells.

    PubMed Central

    Olivera, A; López-Rivas, A; López-Novoa, J M

    1992-01-01

    Adenosine has been associated with cellular Ca2+ metabolism in some cell types. Since adenosine is able to contract glomerular mesangial cells in culture, and since Ca2+ is the main messenger mediating contractile responses, we studied the effect of adenosine on 45Ca2+ movements into and out of mesangial cells and on the cytosolic free Ca2+ concentration ([Ca2+]i). Adenosine at 0.1 mM increased 45Ca2+ uptake (basal, 9993 +/- 216; + adenosine, 14823 +/- 410 d.p.m./mg; P less than 0.01) through verapamil-sensitive Ca2+ channels. These channels seem to be of the A1-adenosine receptor subtype. Adenosine also stimulated 45Ca2+ efflux from 45Ca(2+)-loaded mesangial cells. This effect was accompanied by a net depletion of intracellular 45Ca2+ content under isotopic equilibrium conditions (basal, 24213 +/- 978; + adenosine, 18622 +/- 885 d.p.m./mg; P less than 0.05). The increase in 45Ca2+ efflux was inhibited by a Ca(2+)-free medium or in the presence of 10 microM-verapamil. However, the intracellular Ca(2+)-release blocker TMB-8 (10 microM) only partially inhibited the adenosine-stimulated 45Ca2+ efflux. In addition, adenosine induced an elevation in [Ca2+]i in mesangial cells with an initial transient peak within 15 s (basal, 113 +/- 7; adenosine, 345 +/- 46 nM), and a secondary increase which was slower (3-4 min) and of lower magnitude than the initial peak (250 +/- 21 nM). In summary, adenosine elevates [Ca2+]i and stimulates both Ca2+ uptake from the extracellular pool and Ca2+ efflux from intracellular pools in mesangial cells. The Ca2+ release from internal stores is produced by a combination of a TMB-8-inhibitable and a non-TMB-8-inhibitable mechanism, and seems to be dependent on Ca2+ influx. PMID:1554371

  17. Search for New Purine- and Ribose-Modified Adenosine Analogues as Selective Agonists and Antagonists at Adenosine Receptors†

    PubMed Central

    Siddiqi, Suhaib M.; Jacobson, Kenneth A.; Esker, John L.; Olah, Mark E.; Ji, Xiao-duo; Melman, Neli; Tiwari, Kamal N.; Secrist, John A.; Schneller, Stewart W.; Cristalli, Gloria; Stiles, Gary L.; Johnson, Carl R.; IJzerman, Ad P.

    2012-01-01

    The binding affinities at rat A1, A2a, and A3 adenosine receptors of a wide range of derivatives of adenosine have been determined. Sites of modification include the purine moiety (1-, 3-, and 7-deaza; halo, alkyne, and amino substitutions at the 2- and 8-positions; and N6-CH2-ring, -hydrazino, and -hydroxylamino) and the ribose moiety (2′-, 3′-, and 5′-deoxy; 2′- and 3′-O-methyl; 2′-deoxy 2′-fluoro; 6′-thio; 5′-uronamide; carbocyclic; 4′- or 3′-methyl; and inversion of configuration). (−)- and (+)-5′-Noraristeromycin were 48- and 21-fold selective, respectively, for A2a vs A1 receptors. 2-Chloro-6′-thioadenosine displayed a Ki value of 20 nM at A2a receptors (15-fold selective vs A1). 2-Chloroadenin-9-yl(β-L-2′-deoxy-6′-thiolyxofuranoside) displayed a Ki value of 8 μM at A1 receptors and appeared to be an antagonist, on the basis of the absence of a GTP-induced shift in binding vs a radiolabeled antagonist (8-cyclopentyl-1,3-dipropylxanthine). 2-Chloro-2′-deoxyadenosine and 2-chloroadenin-9-yl(β-D-6′-thioarabinoside) were putative partial agonists at A1 receptors, with Ki values of 7.4 and 5.4 μM, respectively. The A2a selective agonist 2-(1-hexynyl)-5′-(N-ethylcarbamoyl)adenosine displayed a Ki value of 26 nM at A3 receptors. The 4′-methyl substitution of adenosine was poorly tolerated, yet when combined with other favorable modifications, potency was restored. Thus, N6-benzyl-4′-methyladenosine-5′-(N-methyluronamide) displayed a Ki value of 604 nM at A3 receptors and was 103- and 88-fold selective vs A1 and A2a receptors, respectively. This compound was a full agonist in the A3-mediated inhibition of adenylate cyclase in transfected CHO cells. The carbocyclic analogue of N6-(3-iodobenzyl)adenosine-5′-(N-methyluronamide) was 2-fold selective for A3 vs A1 receptors and was nearly inactive at A2a receptors. PMID:7707320

  18. Molecular Vibration-Activity Relationship in the Agonism of Adenosine Receptors

    PubMed Central

    Chee, Hyun Keun

    2013-01-01

    The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands. PMID:24465242

  19. Modulation of adenosine signaling prevents scopolamine-induced cognitive impairment in zebrafish.

    PubMed

    Bortolotto, Josiane Woutheres; Melo, Gabriela Madalena de; Cognato, Giana de Paula; Vianna, Mônica Ryff Moreira; Bonan, Carla Denise

    2015-02-01

    Adenosine, a purine ribonucleoside, exhibits neuromodulatory and neuroprotective effects in the brain and is involved in memory formation and cognitive function. Adenosine signaling is mediated by adenosine receptors (A1, A2A, A2B, and A3); in turn, nucleotide and nucleoside-metabolizing enzymes and adenosine transporters regulate its levels. Scopolamine, a muscarinic cholinergic receptor antagonist, has profound amnesic effects in a variety of learning paradigms and has been used to induce cognitive deficits in animal models. This study investigated the effects of acute exposure to caffeine (a non-selective antagonist of adenosine receptors A1 and A2A), ZM 241385 (adenosine receptor A2A antagonist), DPCPX (adenosine receptor A1 antagonist), dipyridamole (inhibitor of nucleoside transporters) and EHNA (inhibitor of adenosine deaminase) in a model of pharmacological cognitive impairment induced by scopolamine in adult zebrafish. Caffeine, ZM 241385, DPCPX, dipyridamole, and EHNA were acutely administered independently via i.p. in zebrafish, followed by exposure to scopolamine dissolved in tank water (200μM). These compounds prevented the scopolamine-induced amnesia without impacting locomotor activity or social interaction. Together, these data support the hypothesis that adenosine signaling may modulate memory processing, suggesting that these compounds present a potential preventive strategy against cognitive impairment.

  20. Impaired inhibitory function of presynaptic A1-adenosine receptors in SHR mesenteric arteries.

    PubMed

    Rocha-Pereira, Carolina; Arribas, Silvia Magdalena; Fresco, Paula; González, Maria Carmen; Gonçalves, Jorge; Diniz, Carmen

    2013-01-01

    In hypertension, vascular reactivity alterations have been attributed to numerous factors, including higher sympathetic innervation/adenosine. This study examined the modulation of adenosine receptors on vascular sympathetic nerves and their putative contribution to higher noradrenaline spillover in hypertension. We assessed adenosine receptors distribution in the adventitia through confocal microscopy, histomorphometry, and their regulatory function on electrically-evoked [(3)H]-noradrenaline overflow, using selective agonists/antagonists. We found that: i) A1-adenosine receptor agonist (CPA: 100 nM) inhibited tritium overflow to a lower extent in SHR (25% ± 3%, n = 14) compared to WKY (38% ± 3%, n = 14) mesenteric arteries; ii) A2A-adenosine receptor agonist (CGS 21680: 100 nM) induced a slight increase of tritium overflow that was similar in SHR (22% ± 8%, n = 8) and WKY (24% ± 5%, n = 8) mesenteric arteries; iii) A2B- and A3-adenosine receptors did not alter tritium overflow in either strain; iv) all adenosine receptors were present on mesenteric artery sympathetic nerves and/or some adventitial cells of both strains; and v) A1-adenosine receptor staining fractional area was lower in SHR than in WKY mesenteric arteries. We conclude that there is an impaired inhibitory function of vascular presynaptic A1-adenosine receptors in SHR, likely related to a reduced presence of these receptors on sympathetic innervation, which might lead to higher levels of noradrenaline in the synaptic cleft and contribute to hypertension in this strain.

  1. Endogenous adenosine is an autacoid feedback inhibitor of chloride transport in the shark rectal gland.

    PubMed Central

    Kelley, G G; Aassar, O S; Forrest, J N

    1991-01-01

    The present studies define the physiologic role of endogenous adenosine in the perfused shark rectal gland, a model epithelia for hormone-stimulated chloride transport. Chloride ion secretion, and venous adenosine and inosine concentrations increased in parallel in response to hormone stimulation. From a basal rate of 157 +/- 26 mu eq/h per g, chloride secretion increased to 836 +/- 96 and 2170 +/- 358 with 1 and 10 microM forskolin, venous adenosine increased from 5.0 +/- 1 to 126 +/- 29 and 896 +/- 181 nM, and inosine increased from 30 +/- 9 to 349 +/- 77 and 1719 +/- 454 nM (all P less than 0.01). Nitrobenzylthioinosine (NBTI), a nucleoside transport inhibitor, completely blocked the release of adenosine and inosine. Inhibition of chloride transport with bumetanide, an inhibitor of the Na+/K+/2Cl- cotransporter, or ouabain, an inhibitor of Na+/K+ ATPase activity, reduced venous adenosine and inosine to basal values. When the interaction of endogenous adenosine with extracellular receptors was prevented by adenosine deaminase, NBTI, or 8-phenyltheophylline, the chloride transport response to secretagogues increased by 1.7-2.3-fold. These studies demonstrate that endogenous adenosine is released in response to hormone-stimulated cellular work and acts at A1 adenosine receptors as a feedback inhibitor of chloride transport. Images PMID:1752953

  2. Characterization and regulation of adenosine transport in T84 intestinal epithelial cells.

    PubMed

    Mun, E C; Tally, K J; Matthews, J B

    1998-02-01

    Adenosine release from mucosal sources during inflammation and ischemia activates intestinal epithelial Cl- secretion. Previous data suggest that A2b receptor-mediated Cl- secretory responses may be dampened by epithelial cell nucleoside scavenging. The present study utilizes isotopic flux analysis and nucleoside analog binding assays to directly characterize the nucleoside transport system of cultured T84 human intestinal epithelial cells and to explore whether adenosine transport is regulated by secretory agonists, metabolic inhibition, or phorbol ester. Uptake of adenosine across the apical membrane displayed characteristics of simple diffusion. Kinetic analysis of basolateral uptake revealed a Na(+)-independent, nitrobenzylthioinosine (NBTI)-sensitive facilitated-diffusion system with low affinity but high capacity for adenosine. NBTI binding studies indicated a single population of high-affinity binding sites basolaterally. Neither forskolin, 5'-(N-ethylcarboxamido)-adenosine, nor metabolic inhibition significantly altered adenosine transport. However, phorbol 12-myristate 13-acetate significantly reduced both adenosine transport and the number of specific NBTI binding sites, suggesting that transporter number may be decreased through activation of protein kinase C. This basolateral facilitated adenosine transporter may serve a conventional function in nucleoside salvage and a novel function as a regulator of adenosine-dependent Cl- secretory responses and hence diarrheal disorders.

  3. Adenosine triphosphate (ATP) as a possible indicator of extraterrestrial biology

    NASA Technical Reports Server (NTRS)

    Chappelle, E. W.; Picciolo, G. L.

    1974-01-01

    The ubiquity of adenosine triphosphate (ATP) in terrestrial organisms provides the basis for proposing the assay of this vital metabolic intermediate for detecting extraterrestrial biological activity. If an organic carbon chemistry is present on the planets, the occurrence of ATP is possible either from biosynthetic or purely chemical reactions. However, ATP's relative complexity minimizes the probability of abiogenic synthesis. A sensitive technique for the quantitative detection of ATP was developed using the firefly bioluminescent reaction. The procedure was used successfully for the determination of the ATP content of soil and bacteria. This technique is also being investigated from the standpoint of its application in clinical medicine.

  4. The Role of Uridine Adenosine Tetraphosphate in the Vascular System

    PubMed Central

    Matsumoto, Takayuki; Tostes, Rita C.; Webb, R. Clinton

    2011-01-01

    The endothelium plays a pivotal role in vascular homeostasis, and endothelial dysfunction is a major feature of cardiovascular diseases, such as arterial hypertension, atherosclerosis, and diabetes. Recently, uridine adenosine tetraphosphate (Up4A) has been identified as a novel and potent endothelium-derived contracting factor (EDCF). Up4A structurally contains both purine and pyrimidine moieties, which activate purinergic receptors. There is an accumulating body of evidence to show that Up4A modulates vascular function by actions on endothelial and smooth muscle cells. In this paper, we discuss the effects of Up4A on vascular function and a potential role for Up4A in cardiovascular diseases. PMID:22110488

  5. Vasodilatory responsiveness to adenosine triphosphate in ageing humans

    PubMed Central

    Kirby, Brett S; Crecelius, Anne R; Voyles, Wyatt F; Dinenno, Frank A

    2010-01-01

    Endothelium-dependent vasodilatation is reduced with advancing age in humans, as evidenced by blunted vasodilator responsiveness to acetylcholine (ACh). Circulating adenosine triphosphate (ATP) has been implicated in the control of skeletal muscle vascular tone during mismatches in oxygen delivery and demand (e.g. exercise) via binding to purinergic receptors (P2Y) on the endothelium evoking subsequent vasodilatation, and ageing is typically associated with reductions in muscle blood flow under such conditions. Therefore, we tested the hypothesis that ATP-mediated vasodilatation is impaired with age in healthy humans. We measured forearm blood flow (venous occlusion plethysmography) and calculated vascular conductance (FVC) responses to local intra-arterial infusions of ACh, ATP, and sodium nitroprusside (SNP) before and during ascorbic acid (AA) infusion in 13 young and 13 older adults. The peak increase in FVC to ACh was significantly impaired in older compared with young adults (262 ± 71%vs. 618 ± 97%; P < 0.05), and this difference was abolished during AA infusion (510 ± 82%vs. 556 ± 71%; not significant, NS). In contrast, peak FVC responses were not different between older and young adults to either ATP (675 ± 105%vs. 734 ± 126%) or SNP (1116 ± 111%vs. 1138 ± 148%) and AA infusion did not alter these responses in either age group (both NS). In another group of six young and six older adults, we determined whether vasodilator responses to adenosine and ATP were influenced by P1-receptor blockade via aminophylline. The peak FVC responses to adenosine were not different in young (350 ± 65%) versus older adults (360 ± 80%), and aminophylline blunted these responses by ∼50% in both groups. The peak FVC responses to ATP were again not different in young and older adults, and aminophylline did not impact the vasodilatation in either group. Thus, in contrast to the observed impairments in ACh responses, the vasodilatory response to exogenous ATP is not

  6. Adenosine conjugated lipidic nanoparticles for enhanced tumor targeting.

    PubMed

    Swami, Rajan; Singh, Indu; Jeengar, Manish Kumar; Naidu, V G M; Khan, Wahid; Sistla, Ramakrishna

    2015-01-01

    Delivering chemotherapeutics by nanoparticles into tumor is impeded majorly by two factors: nonspecific targeting and inefficient penetration. Targeted delivery of anti-cancer agents solely to tumor cells introduces a smart strategy because it enhances the therapeutic index compared with untargeted drugs. The present study was performed to investigate the efficiency of adenosine (ADN) to target solid lipid nanoparticles (SLN) to over expressing adenosine receptor cell lines such as human breast cancer and prostate cancer (MCF-7 and DU-145 cells), respectively. SLN were prepared by emulsification and solvent evaporation process using docetaxel (DTX) as drug and were characterized by various techniques like dynamic light scattering, differential scanning calorimeter and transmission electron microscopy. DTX loaded SLNs were surface modified with ADN, an adenosine receptors ligand using carbodiimide coupling. Conjugation was confirmed using infrared spectroscopy and quantified using phenol-sulfuric acid method. Conjugated SLN were shown to have sustained drug release as compared to unconjugated nanoparticles and drug suspension. Compared with free DTX and unconjugated SLN, ADN conjugated SLN showed significantly higher cytotoxicity of loaded DTX, as evidenced by in vitro cell experiments. The IC50 was 0.41 μg/ml for native DTX, 0.30 μg/ml for unconjugated SLN formulation, and 0.09 μg/ml for ADN conjugated SLN formulation in MCF-7 cell lines. Whereas, in DU-145, there was 2 fold change in IC50 of ADN-SLN as compared to DTX. IC50 was found to be 0.44 μg/ml for free DTX, 0.39 μg/ml for unconjugated SLN and 0.22 μg/ml for ADN-SLN. Annexin assay and cell cycle analysis assay further substantiated the cell cytotoxicity. Fluorescent cell uptake and competitive ligand-receptor binding assay corroborated the receptor mediated endocytosis pathway indicated role of adenosine receptors in internalization of conjugated particles. Pharmacokinetic studies of lipidic

  7. Adenosine triphosphatases of thermophilic archaeal double-stranded DNA viruses

    PubMed Central

    2014-01-01

    Adenosine triphosphatases (ATPases) of double-stranded (ds) DNA archaeal viruses are structurally related to the AAA+ hexameric helicases and translocases. These ATPases have been implicated in viral life cycle functions such as DNA entry into the host, and viral genome packaging into preformed procapsids. We summarize bioinformatical analyses of a wide range of archaeal ATPases, and review the biochemical and structural properties of those archaeal ATPases that have measurable ATPase activity. We discuss their potential roles in genome delivery into the host, virus assembly and genome packaging in comparison to hexameric helicases and packaging motors from bacteriophages. PMID:25105011

  8. Adenosine Inhibits the Excitatory Synaptic Inputs to Basal Forebrain Cholinergic, GABAergic, and Parvalbumin Neurons in Mice

    PubMed Central

    Yang, Chun; Franciosi, Serena; Brown, Ritchie E.

    2013-01-01

    Coffee and tea contain the stimulants caffeine and theophylline. These compounds act as antagonists of adenosine receptors. Adenosine promotes sleep and its extracellular concentration rises in association with prolonged wakefulness, particularly in the basal forebrain (BF) region involved in activating the cerebral cortex. However, the effect of adenosine on identified BF neurons, especially non-cholinergic neurons, is incompletely understood. Here we used whole-cell patch-clamp recordings in mouse brain slices prepared from two validated transgenic mouse lines with fluorescent proteins expressed in GABAergic or parvalbumin (PV) neurons to determine the effect of adenosine. Whole-cell recordings were made from BF cholinergic neurons and from BF GABAergic and PV neurons with the size (>20 μm) and intrinsic membrane properties (prominent H-currents) corresponding to cortically projecting neurons. A brief (2 min) bath application of adenosine (100 μM) decreased the frequency but not the amplitude of spontaneous excitatory postsynaptic currents (EPSCs) in all groups of BF cholinergic, GABAergic, and PV neurons we recorded. In addition, adenosine decreased the frequency of miniature EPSCs in BF cholinergic neurons. Adenosine had no effect on the frequency of spontaneous inhibitory postsynaptic currents in cholinergic neurons or GABAergic neurons with large H-currents but reduced them in a group of GABAergic neurons with smaller H-currents. All effects of adenosine were blocked by a selective, adenosine A1 receptor antagonist, cyclopentyltheophylline (CPT, 1 μM). Adenosine had no postsynaptic effects. Taken together, our work suggests that adenosine promotes sleep by an A1 receptor-mediated inhibition of glutamatergic inputs to cortically projecting cholinergic and GABA/PV neurons. Conversely, caffeine and theophylline promote attentive wakefulness by inhibiting these A1 receptors in BF thereby promoting the high-frequency oscillations in the cortex required

  9. An Adenosine-Mediated Glial-Neuronal Circuit for Homeostatic Sleep

    PubMed Central

    Bjorness, Theresa E.; Dale, Nicholas; Mettlach, Gabriel; Sonneborn, Alex; Sahin, Bogachan; Fienberg, Allen A.; Yanagisawa, Masashi; Bibb, James A.

    2016-01-01

    Sleep homeostasis reflects a centrally mediated drive for sleep, which increases during waking and resolves during subsequent sleep. Here we demonstrate that mice deficient for glial adenosine kinase (AdK), the primary metabolizing enzyme for adenosine (Ado), exhibit enhanced expression of this homeostatic drive by three independent measures: (1) increased rebound of slow-wave activity; (2) increased consolidation of slow-wave sleep; and (3) increased time constant of slow-wave activity decay during an average slow-wave sleep episode, proposed and validated here as a new index for homeostatic sleep drive. Conversely, mice deficient for the neuronal adenosine A1 receptor exhibit significantly decreased sleep drive as judged by these same indices. Neuronal knock-out of AdK did not influence homeostatic sleep need. Together, these findings implicate a glial-neuronal circuit mediated by intercellular Ado, controlling expression of homeostatic sleep drive. Because AdK is tightly regulated by glial metabolic state, our findings suggest a functional link between cellular metabolism and sleep homeostasis. SIGNIFICANCE STATEMENT The work presented here provides evidence for an adenosine-mediated regulation of sleep in response to waking (i.e., homeostatic sleep need), requiring activation of neuronal adenosine A1 receptors and controlled by glial adenosine kinase. Adenosine kinase acts as a highly sensitive and important metabolic sensor of the glial ATP/ADP and AMP ratio directly controlling intracellular adenosine concentration. Glial equilibrative adenosine transporters reflect the intracellular concentration to the extracellular milieu to activate neuronal adenosine receptors. Thus, adenosine mediates a glial-neuronal circuit linking glial metabolic state to neural-expressed sleep homeostasis. This indicates a metabolically related function(s) for this glial-neuronal circuit in the buildup and resolution of our need to sleep and suggests potential therapeutic targets

  10. Presynaptic action of adenosine on a 4-aminopyridine-sensitive current in the rat carotid body

    PubMed Central

    Vandier, C; Conway, A F; Landauer, R C; Kumar, P

    1999-01-01

    Plasma adenosine concentration increases during hypoxia to a level that excites carotid body chemoreceptors by an undetermined mechanism. We have examined this further by determining the electrophysiological responses to exogenous adenosine of sinus nerve chemoafferents in vitro and of whole-cell currents in isolated type I cells.Steady-state, single-fibre chemoafferent discharge was increased approximately 5-fold above basal levels by 100 μM adenosine. This adenosine-stimulated discharge was reversibly and increasingly reduced by methoxyverapamil (D600, 100 μM), by application of nickel chloride (Ni2+, 2 mM) and by removal of extracellular Ca2+. These effects strongly suggest a presynaptic, excitatory action of adenosine on type I cells of the carotid body.Adenosine decreased whole-cell outward currents at membrane potentials above -40 mV in isolated type I cells recorded during superfusion with bicarbonate-buffered saline solution at 34–36 °C. This effect was reversible and concentration dependent with a maximal effect at 10 μM.The degree of current inhibition induced by 10 μM adenosine was voltage independent (45.39 ± 2.55% (mean ± s.e.m.) between −40 and +30 mV) and largely (∼75%), but not entirely, Ca2+ independent. 4-Aminopyridine (4-AP, 5 mM) decreased the amplitude of the control outward current by 80.60 ± 3.67% and abolished the effect of adenosine.Adenosine was without effect upon currents near the resting membrane potential of approximately −55 mV and did not induce depolarization in current-clamp experiments.We conclude that adenosine acts to inhibit a 4-AP-sensitive current in isolated type I cells of the rat carotid body and suggest that this mechanism contributes to the chemoexcitatory effect of adenosine in the whole carotid body. PMID:10050009

  11. Pyrazolo-triazolo-pyrimidines as adenosine receptor antagonists: Effect of the N-5 bond type on the affinity and selectivity at the four adenosine receptor subtypes

    PubMed Central

    Bolcato, Chiara; Cusan, Claudia; Pastorin, Giorgia; Cacciari, Barbara; Klotz, Karl Norbert; Morizzo, Erika

    2007-01-01

    In the last few years, many efforts have been made to search for potent and selective human A3 adenosine antagonists. In particular, one of the most promising human A3 adenosine receptor antagonists is represented by the pyrazolo-triazolo-pyrimidine family. This class of compounds has been strongly investigated from the point of view of structure-activity relationships. In particular, it has been observed that fundamental requisites for having both potency and selectivity at the human A3 adenosine receptors are the presence of a small substituent at the N8 position and an unsubstitued phenyl carbamoyl moiety at the N5 position. In this study, we report the role of the N5-bond type on the affinity and selectivity at the four adenosine receptor subtypes. The observed structure-activity relationships of this class of antagonists are also exhaustively rationalized using the recently published ligand-based homology modeling approach. PMID:18368532

  12. Exploring human adenosine A3 receptor complementarity and activity for adenosine analogues modified in the ribose and purine moiety

    PubMed Central

    Van Rompaey, Philippe; Jacobson, Kenneth A.; Gross, Ariel S.; Gao, Zhan-Guo; Van Calenbergh, Serge

    2012-01-01

    In this paper we investigated the influence on affinity, selectivity and intrinsic activity upon modification of the adenosine agonist scaffold at the 3′- and 5′-positions of the ribofuranosyl moiety and the 2- and N6-positions of the purine base. This resulted in the synthesis of various analogues, that is, 3–12 and 24–33, with good hA3AR selectivity and moderate-to-high affinities (as in 32, Ki = 27 nM). Interesting was the ability to tune the intrinsic activity depending on the substituent introduced at the 3′-position. PMID:15670905

  13. Opiate-induced changes in brain adenosine levels and narcotic drug responses.

    PubMed

    Wu, M; Sahbaie, P; Zheng, M; Lobato, R; Boison, D; Clark, J D; Peltz, G

    2013-01-01

    We have very little information about the metabolomic changes that mediate neurobehavioral responses, including addiction. It was possible that opioid-induced metabolomic changes in brain could mediate some of the pharmacodynamic effects of opioids. To investigate this, opiate-induced brain metabolomic responses were profiled using a semi-targeted method in C57BL/6 and 129Sv1 mice, which exhibit extreme differences in their tendency to become opiate dependent. Escalating morphine doses (10-40 mg/kg) administered over a 4-day period selectively induced a twofold decrease (p<0.00005) in adenosine abundance in the brainstem of C57BL/6 mice, which exhibited symptoms of narcotic drug dependence; but did not decrease adenosine abundance in 129Sv1 mice, which do not exhibit symptoms of dependence. Based on this finding, the effect of adenosine on dependence was investigated in genetically engineered mice with alterations in adenosine tone in the brain and in pharmacologic experiments. Morphine withdrawal behaviors were significantly diminished (p<0.0004) in genetically engineered mice with reduced adenosine tone in the brainstem, and by treatment with an adenosine receptor(1) (A(1)) agonist (2-chloro-N6-cyclopentyladenosine, 0.5mg/kg) or an A(2a) receptor (A(2a)) antagonist (SCH 58261, 1mg/kg). These results indicate that adenosine homeostasis plays a crucial role in narcotic drug responses. Opiate-induced changes in brain adenosine levels may explain many important neurobehavioral features associated with opiate addiction and withdrawal.

  14. Photomodulation of G Protein-Coupled Adenosine Receptors by a Novel Light-Switchable Ligand

    PubMed Central

    2015-01-01

    The adenosinergic system operates through G protein-coupled adenosine receptors, which have become promising therapeutic targets for a wide range of pathological conditions. However, the ubiquity of adenosine receptors and the eventual lack of selectivity of adenosine-based drugs have frequently diminished their therapeutic potential. Accordingly, here we aimed to develop a new generation of light-switchable adenosine receptor ligands that change their intrinsic activity upon irradiation, thus allowing the spatiotemporal control of receptor functioning (i.e., receptor activation/inactivation dependent on location and timing). Therefore, we synthesized an orthosteric, photoisomerizable, and nonselective adenosine receptor agonist, nucleoside derivative MRS5543 containing an aryl diazo linkage on the N6 substituent, which in the dark (relaxed isomer) behaved as a full adenosine A3 receptor (A3R) and partial adenosine A2A receptor (A2AR) agonist. Conversely, upon photoisomerization with blue light (460 nm), it remained a full A3R agonist but became an A2AR antagonist. Interestingly, molecular modeling suggested that structural differences encountered within the third extracellular loop of each receptor could modulate the intrinsic, receptor subtype-dependent, activity. Overall, the development of adenosine receptor ligands with photoswitchable activity expands the pharmacological toolbox in support of research and possibly opens new pharmacotherapeutic opportunities. PMID:25248077

  15. Perfusion pressure control by adenosine triphosphate given during cardiopulmonary bypass.

    PubMed

    Hashimoto, K; Kurosawa, H; Horikoshi, S; Miyamoto, H; Suzuki, K

    1993-01-01

    Administration of exogenous adenosine triphosphate (ATP) as a vasodilator during cardiopulmonary bypass was assessed in consecutive adult patients (n = 24) who demonstrated a high arterial perfusion pressure (mean, > 90 mm Hg). The action of ATP was characterized by rapid induction and stabilization of the blood pressure level. The dose of ATP ranged from 0.68 to 2.68 mg/min. Within 1 minute after the administration, there was a significant reduction in the perfusion pressure from 102 +/- 18 mm Hg (mean +/- standard deviation) to 72 +/- 19 mm Hg. The ATP was then able to maintain the desired pressure of 69 +/- 12 mm Hg at 5 minutes, 67 +/- 12 mm Hg at 10 minutes, and consistent values thereafter. After the ATP administration was discontinued, there was a prompt recovery of pressure without bradyarrhythmia. The frequency and amount of inotropes used were consistent with the control group (n = 26). Although the administration of ATP reduced the increase in serum catecholamine concentration, there were no significant changes in other vasoactive mediators (eicosanoid, angiotensin II, endothelin) between the two groups during cardiopulmonary bypass. There was neither an accumulation of metabolic products (uric acid, phosphate) nor a decrease in the level of divalent cation (Ca2+), which is observed when the cations combine with phosphates or adenosine nucleotides. This study confirmed the efficacy and safety of ATP infusion during cardiopulmonary bypass. PMID:8417658

  16. A continuous spectrophotometric assay for monitoring adenosine 5'-monophosphate production.

    PubMed

    First, Eric A

    2015-08-15

    A number of biologically important enzymes release adenosine 5'-monophosphate (AMP) as a product, including aminoacyl-tRNA synthetases, cyclic AMP (cAMP) phosphodiesterases, ubiquitin and ubiquitin-like ligases, DNA ligases, coenzyme A (CoA) ligases, polyA deadenylases, and ribonucleases. In contrast to the abundance of assays available for monitoring the conversion of adenosine 5'-triphosphate (ATP) to ADP, there are relatively few assays for monitoring the conversion of ATP (or cAMP) to AMP. In this article, we describe a homogeneous assay that continuously monitors the production of AMP. Specifically, we have coupled the conversion of AMP to inosine 5'-monophosphate (IMP) (by AMP deaminase) to the oxidation of IMP (by IMP dehydrogenase). This results in the reduction of oxidized nicotine adenine dinucleotide (NAD(+)) to reduced nicotine adenine dinucleotide (NADH), allowing AMP formation to be monitored by the change in the absorbance at 340 nm. Changes in AMP concentrations of 5 μM or more can be reliably detected. The ease of use and relatively low expense make the AMP assay suitable for both high-throughput screening and kinetic analyses. PMID:25957126

  17. Novel trypanocidal analogs of 5'-(methylthio)-adenosine.

    PubMed

    Sufrin, Janice R; Spiess, Arthur J; Marasco, Canio J; Rattendi, Donna; Bacchi, Cyrus J

    2008-01-01

    The purine nucleoside 5'-deoxy-5'-(hydroxyethylthio)-adenosine (HETA) is an analog of the polyamine pathway metabolite 5'-deoxy-5'-(methylthio)-adenosine (MTA). HETA is a lead structure for the ongoing development of selectively targeted trypanocidal agents. Thirteen novel HETA analogs were synthesized and examined for their in vitro trypanocidal activities against bloodstream forms of Trypanosoma brucei brucei LAB 110 EATRO and at least one drug-resistant Trypanosoma brucei rhodesiense clinical isolate. New compounds were also assessed in a cell-free assay for their activities as substrates of trypanosome MTA phosphorylase. The most potent analog in this group was 5'-deoxy-5'-(hydroxyethylthio)-tubercidin, whose in vitro cytotoxicity (50% inhibitory concentration [IC50], 10 nM) is 45 times greater than that of HETA (IC50, 450 nM) against pentamidine-resistant clinical isolate KETRI 269. Structure-activity analyses indicate that the enzymatic cleavage of HETA analogs by trypanosome MTA phosphorylase is not an absolute requirement for trypanocidal activity. This suggests that additional biochemical mechanisms are associated with the trypanocidal effects of HETA and its analogs.

  18. Purification and Properties of Adenosine Diphosphoglucose Pyrophosphorylase from Sweet Corn 1

    PubMed Central

    Amir, Jacob; Cherry, Joe H.

    1972-01-01

    A 40-fold purification of adenosine diphosphoglucose pyrophosphorylase from sweet corn (Zea mays var. Golden Beauty) revealed the enzyme to be specific for adenosine triphosphate. The enzyme has an absolute requirement for Mg2+ and is activated by 3-phosphoglycerate and to a lesser extent by ribose-5-phosphate and fructose-6-phosphate. The apparent Km values of the enzyme for glucose-1-phosphate, adenosine triphosphate, pyrophosphate, and adenosine diphosphoglucose are 1.9 × 10−4, 3.2 × 10−5, 3.3 × 10−5, and 6.2 × 10−4m, respectively. Pyrophosphate inhibits adenosine diphosphoglucose synthesis competitively (Ki = 3.8 × 10−7m), while orthophosphate and sulfate appear to inhibit the reacion noncompetitively. These results show that the production of this sugar nucleotide can be controlled by the concentration of pyrophosphate. PMID:16658078

  19. Adenosine and ATP Link PCO2 to Cortical Excitability via pH

    PubMed Central

    Dulla, Chris G.; Dobelis, Peter; Pearson, Tim; Frenguelli, Bruno G.; Staley, Kevin J.; Masino, Susan A.

    2007-01-01

    Summary In addition to affecting respiration and vascular tone, deviations from normal CO2 alter pH, consciousness, and seizure propensity. Outside the brainstem, however, the mechanisms by which CO2 levels modify neuronal function are unknown. In the hippocampal slice preparation, increasing CO2, and thus decreasing pH, increased the extracellular concentration of the endogenous neuromodulator adenosine and inhibited excitatory synaptic transmission. These effects involve adenosine A1 and ATP receptors and depend on decreased extracellular pH. In contrast, decreasing CO2 levels reduced extracellular adenosine concentration and increased neuronal excitability via adenosine A1 receptors, ATP receptors, and ecto-ATPase. Based on these studies, we propose that CO2-induced changes in neuronal function arise from a pH-dependent modulation of adenosine and ATP levels. These findings demonstrate a mechanism for the bidirectional effects of CO2 on neuronal excitability in the forebrain. PMID:16364904

  20. Respiratory stimulant effects of adenosine in man after caffeine and enprofylline.

    PubMed Central

    Smits, P; Schouten, J; Thien, T

    1987-01-01

    In a double-blind and randomized study the respiratory stimulant effect of continuous intravenous adenosine infusion was studied after previous administration of caffeine, placebo and enprofylline in 10 healthy young volunteers. After placebo, adenosine induced an increase of minute ventilation (from 6.3 to 12.5 l min-1), tidal volume (from 0.60 to 0.96 l), and breathing rate (from 11.0 to 14.8 min-1). Venous pCO2 fell and pH rose after adenosine. Caffeine significantly reduced the adenosine-induced changes of minute ventilation, tidal volume, venous pCO2 and pH, whereas no changes occurred after enprofylline. Our results suggest that adenosine stimulates respiration in man by binding with specific P1-purinoceptors, which can be blocked by caffeine, but not by enprofylline. PMID:3440102

  1. Reconstruction of the adenosine system by bone marrow-derived mesenchymal stem cell transplantation☆

    PubMed Central

    Kang, Huicong; Hu, Qi; Liu, Xiaoyan; Liu, Yinhe; Xu, Feng; Li, Xiang; Zhu, Suiqiang

    2012-01-01

    In the present study, we transplanted bone marrow-derived mesenchymal stem cells into the CA3 area of the hippocampus of chronic epilepsy rats kindled by lithium chloride-pilocarpine. Immunofluorescence and western blotting revealed an increase in adenosine A1 receptor expression and a decrease in adenosine A2a receptor expression in the brain tissues of epileptic rats 3 months after transplantation. Moreover, the imbalance in the A1 adenosine receptor/A2a adenosine receptor ratio was improved. Electroencephalograms showed that frequency and amplitude of spikes in the hippocampus and frontal lobe were reduced. These results suggested that mesenchymal stem cell transplantation can reconstruct the normal function of the adenosine system in the brain and greatly improve epileptiform discharges. PMID:25806064

  2. 2-(1-Hexyn-1-yl)adenosine-induced intraocular hypertension is mediated via K+ channel opening through adenosine A2A receptor in rabbits.

    PubMed

    Konno, Takashi; Uchibori, Takehiro; Nagai, Akihiko; Kogi, Kentaro; Nakahata, Norimichi

    2005-08-22

    The present study was performed to clarify the mechanism of change in intraocular pressure by 2-(1-hexyn-1-yl)adenosine (2-H-Ado), a selective adenosine A2 receptor agonist, in rabbits. 2-H-Ado (0.1%, 50 microl)-induced ocular hypertension (E(max): 7.7 mm Hg) was inhibited by an adenosine A2A receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine, ATP-sensitive K+ channel blocker glibenclamide or 5-hydroxydecanoic acid, but not by an adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine, an adenosine A2B receptor antagonist alloxazine or a cyclooxygenase inhibitor indomethacin. The outflow facility induced by 2-H-Ado seems to be independent of increase in intraocular pressure or ATP-sensitive K+ channel. In contrast, the recovery rate in intraocular pressure decreased by hypertonic saline was accelerated by 2-H-Ado, and this response was dependent on ATP-sensitive K+ channel. These results suggest that 2-H-Ado-induced ocular hypertension is mediated via K+ channel opening through adenosine A2A receptor, and this is probably due to aqueous formation, but independent of change in outflow facility or prostaglandin production.

  3. Involvement of adenosine A2a receptor in intraocular pressure decrease induced by 2-(1-octyn-1-yl)adenosine or 2-(6-cyano-1-hexyn-1-yl)adenosine.

    PubMed

    Konno, Takashi; Murakami, Akira; Uchibori, Takehiro; Nagai, Akihiko; Kogi, Kentaro; Nakahata, Norimichi

    2005-04-01

    The aim of the present study is to clarify the mechanism for the decrease in intraocular pressure by 2-alkynyladenosine derivatives in rabbits. The receptor binding analysis revealed that 2-(1-octyn-1-yl)adenosine (2-O-Ado) and 2-(6-cyano-1-hexyn-1-yl)adenosine (2-CN-Ado) selectively bound to the A(2a) receptor with a high affinity. Ocular hypotensive responses to 2-O-Ado and 2-CN-Ado were inhibited by the adenosine A(2a)-receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine (CSC), but not by the adenosine A(1)-receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) or the adenosine A(2b)-receptor antagonist alloxazine. In addition, 2-O-Ado and 2-CN-Ado caused an increase in outflow facility, which was inhibited by CSC, but not by DPCPX or alloxazine. Moreover, 2-O-Ado and 2-CN-Ado increased cAMP in the aqueous humor, and the 2-O-Ado-induced an increase in cAMP was inhibited by CSC. These results suggest that 2-O-Ado and 2-CN-Ado reduced intraocular pressure via an increase in outflow facility. The ocular hypotension may be mainly mediated through the activation of adenosine A(2a) receptor, although a possible involvement of adenosine A(1) receptor cannot be completely ruled out. 2-O-Ado and 2-CN-Ado are useful lead compounds for the treatment of glaucoma.

  4. Real-time monitoring of extracellular adenosine using enzyme-linked microelectrode arrays.

    PubMed

    Hinzman, Jason M; Gibson, Justin L; Tackla, Ryan D; Costello, Mark S; Burmeister, Jason J; Quintero, Jorge E; Gerhardt, Greg A; Hartings, Jed A

    2015-12-15

    Throughout the central nervous system extracellular adenosine serves important neuroprotective and neuromodulatory functions. However, current understanding of the in vivo regulation and effects of adenosine is limited by the spatial and temporal resolution of available measurement techniques. Here, we describe an enzyme-linked microelectrode array (MEA) with high spatial (7500 µm(2)) and temporal (4 Hz) resolution that can selectively measure extracellular adenosine through the use of self-referenced coating scheme that accounts for interfering substances and the enzymatic breakdown products of adenosine. In vitro, the MEAs selectively measured adenosine in a linear fashion (r(2)=0.98±0.01, concentration range=0-15 µM, limit of detection =0.96±0.5 µM). In vivo the limit of detection was 0.04±0.02 µM, which permitted real-time monitoring of the basal extracellular concentration in rat cerebral cortex (4.3±1.5 µM). Local cortical injection of adenosine through a micropipette produced dose-dependent transient increases in the measured extracellular concentration (200 nL: 6.8±1.8 µM; 400 nL: 19.4±5.3 µM) [P<0.001]. Lastly, local injection of dipyridamole, which inhibits transport of adenosine through equilibrative nucleoside transporter, raised the measured extracellular concentration of adenosine by 120% (5.6→12.3 µM) [P<0.001]. These studies demonstrate that MEAs can selectively measure adenosine on temporal and spatial scales relevant to adenosine signaling and regulation in normal and pathologic states. PMID:26183072

  5. Adenosine regulates the proinflammatory signaling function of thrombin in endothelial cells

    PubMed Central

    Hassanian, Seyed Mahdi; Dinarvand, Peyman; Rezaie, Alireza R.

    2014-01-01

    The plasma level of the regulatory metabolite adenosine increases during the activation of coagulation and inflammation. Here we investigated the effect of adenosine on modulation of thrombin-mediated proinflammatory responses in HUVECs. We found that adenosine inhibits the barrier-disruptive effect of thrombin in HUVECs by a concentration-dependent manner. Analysis of cell surface expression of adenosine receptors revealed that A2A and A2B are expressed at the highest level among the four receptor subtypes (A2B>A2A>A1>A3) on HUVECs. The barrier-protective effect of adenosine in response to thrombin was recapitulated by the A2A specific agonist, CGS 21680, and abrogated both by the siRNA knockdown of the A2A receptor and by the A2A-specific antagonists, ZM-241385 and SCH-58261. The thrombin-induced RhoA activation and its membrane translocation were both inhibited by adenosine in a cAMP-dependent manner, providing a molecular mechanism through which adenosine exerts a barrier-protective function. Adenosine also inhibited thrombin-mediated activation of NF-κB and decreased adhesion of monocytic THP-1 cells to stimulated HUVECs via down-regulation of expression of cell surface adhesion molecules, VCAM-1, ICAM-1 and E-selectin. Moreover, adenosine inhibited thrombin-induced elevated expression of proinflammatory cytokines, IL-6 and HMGB-1; and chemokines, MCP-1, CXCL-1 and CXCL-3. Taken together, these results suggest that adenosine may inhibit thrombin-mediated proinflammatory signaling responses, thereby protecting the endothelium from injury during activation of coagulation and inflammation. PMID:24477600

  6. Adenosine Deaminase Enzyme Therapy Prevents and Reverses the Heightened Cavernosal Relaxation in Priapism

    PubMed Central

    Wen, Jiaming; Jiang, Xianzhen; Dai, Yingbo; Zhang, Yujin; Tang, Yuxin; Sun, Hong; Mi, Tiejuan; Kellems, Rodney E.; Blackburn, Michael R.; Xia, Yang

    2010-01-01

    Introduction Priapism featured with painful prolonged penile erection is dangerous and commonly seen in sickle cell disease (SCD). The preventive approaches or effective treatment options for the disorder are limited because of poor understanding of its pathogenesis. Recent studies have revealed a novel role of excess adenosine in priapism caused by heightened cavernosal relaxation, and therefore present an intriguing mechanism-based therapeutic possibility. Aim The aim of this study was to determine the therapeutic effects of adenosine deaminase (ADA) enzyme therapy to lower adenosine in priapism. Methods Both ADA-deficient mice and SCD transgenic (Tg) mice display priapism caused by excessive adenosine. Thus, we used these two distinct lines of mouse models of priapism as our investigative tools. Specifically, we treated both of these mice with different dosages of polyethylene glycol–modified ADA (PEG–ADA) to reduce adenosine levels in vivo. At the end points of the experiments, we evaluated the therapeutic effects of PEG–ADA treatment by measuring adenosine levels and monitoring the cavernosal relaxation. Main Outcome Measures Adenosine levels in penile tissues were measured by high-performance liquid chromatography, and cavernosal relaxation was quantified by electrical field stimulation (EFS)-induced corporal cavernosal strip (CCS) assays. Results We found that lowering adenosine levels in penile tissues by PEG–ADA treatment from birth in ADA-deficient mice prevented the increased EFS-induced CCS relaxation associated with priapism. Intriguingly, in both ADA-deficient mice and SCD Tg mice with established priapism, we found that normalization of adenosine levels in penile tissues by PEG–ADA treatment relieved the heightened EFS-induced cavernosal relaxation in priapism. Conclusions Our studies have identified that PEG–ADA is a novel, safe, and mechanism-based drug to prevent and correct excess adenosine-mediated increased cavernosal relaxation

  7. Pharmacokinetics, biodistribution and metabolism of squalenoyl adenosine nanoparticles in mice using dual radio-labeling and radio-HPLC analysis

    PubMed Central

    Gaudin, Alice; Lepetre-Mouelhi, Sinda; Mougin, Julie; Parrod, Martine; Pieters, Grégory; Garcia-Argote, Sébastien; Loreau, Olivier; Goncalves, Jordan; Chacun, Hélène; Courbebaisse, Yann; Clayette, Pascal; Desmaële, Didier; Rousseau, Bernard; Andrieux, Karine; Couvreur, Patrick

    2015-01-01

    Adenosine is a pleiotropic endogenous nucleoside with potential neuroprotective pharmacological activity. However, clinical use of adenosine is hampered by its extremely fast metabolization. To overcome this limitation, we recently developed a new squalenoyl nanomedicine of adenosine [Squalenoyl-Adenosine (SQAd)] by covalent linkage of this nucleoside to the squalene, a natural lipid. The resulting nanoassemblies (NAs) displayed a dramatic pharmacological activity both in cerebral ischemia and spinal cord injury pre-clinical models. The aim of the present study was to investigate the plasma profile and tissue distribution of SQAd NAs using both Squalenoyl-[3H]-Adenosine NAs and [14C]-Squalenoyl-Adenosine NAs as respective tracers of adenosine and squalene moieties of the SQAd bioconjugate. This study was completed by radio-HPLC analysis allowing to determine the metabolization profile of SQAd. We report here that SQAd NAs allowed a sustained circulation of adenosine under its prodrug form (SQAd) for at least 1 h after intravenous administration, when free adenosine was metabolized within seconds after injection. Moreover, the squalenoylation of adenosine and its formulation as NAs also significantly modified biodistribution, as SQAd NAs were mainly captured by the liver and spleen, allowing a significant release of adenosine in the liver parenchyma. Altogether, these results suggest that SQAd NAs provided a reservoir of adenosine into the bloodstream which may explain the previously observed neuroprotective efficacy of SQAd NAs against cerebral ischemia and spinal cord injury. PMID:26087468

  8. Pharmacokinetics, biodistribution and metabolism of squalenoyl adenosine nanoparticles in mice using dual radio-labeling and radio-HPLC analysis.

    PubMed

    Gaudin, Alice; Lepetre-Mouelhi, Sinda; Mougin, Julie; Parrod, Martine; Pieters, Grégory; Garcia-Argote, Sébastien; Loreau, Olivier; Goncalves, Jordan; Chacun, Hélène; Courbebaisse, Yann; Clayette, Pascal; Desmaële, Didier; Rousseau, Bernard; Andrieux, Karine; Couvreur, Patrick

    2015-08-28

    Adenosine is a pleiotropic endogenous nucleoside with potential neuroprotective pharmacological activity. However, clinical use of adenosine is hampered by its extremely fast metabolization. To overcome this limitation, we recently developed a new squalenoyl nanomedicine of adenosine [Squalenoyl-Adenosine (SQAd)] by covalent linkage of this nucleoside to the squalene, a natural lipid. The resulting nanoassemblies (NAs) displayed a dramatic pharmacological activity both in cerebral ischemia and spinal cord injury pre-clinical models. The aim of the present study was to investigate the plasma profile and tissue distribution of SQAd NAs using both Squalenoyl-[(3)H]-Adenosine NAs and [(14)C]-Squalenoyl-Adenosine NAs as respective tracers of adenosine and squalene moieties of the SQAd bioconjugate. This study was completed by radio-HPLC analysis allowing to determine the metabolization profile of SQAd. We report here that SQAd NAs allowed a sustained circulation of adenosine under its prodrug form (SQAd) for at least 1h after intravenous administration, when free adenosine was metabolized within seconds after injection. Moreover, the squalenoylation of adenosine and its formulation as NAs also significantly modified biodistribution, as SQAd NAs were mainly captured by the liver and spleen, allowing a significant release of adenosine in the liver parenchyma. Altogether, these results suggest that SQAd NAs provided a reservoir of adenosine into the bloodstream which may explain the previously observed neuroprotective efficacy of SQAd NAs against cerebral ischemia and spinal cord injury. PMID:26087468

  9. Effect of adenosine and adenosine receptor antagonist on Müller cell potassium channel in Rat chronic ocular hypertension models.

    PubMed

    Yang, Zijian; Huang, Ping; Liu, Xiaohong; Huang, Shouyue; Deng, Lianfu; Jin, Zhe; Xu, Shuo; Shen, Xi; Luo, Xunda; Zhong, Yisheng

    2015-01-01

    Müller cells are principal glial cells in rat retina and have attracted much attention in glaucoma studies. However, it is not clear whether adenosine and adenosine receptor (AR) antagonists play any roles in the regulation of potassium channels in Müller cells and subsequently in the promotion of glutamine synthetase (GS) and L-Glutamate/L-Aspartate Transporter (GLAST) functions. We found that chronic ocular hypertension (COH) in rat down-regulated Müller cells Kir2.1, Kir4.1, TASK-1, GS and GLAST expressions and attenuated the peak of inward potassium current. Retinal ganglion cells (RGC) count was lower in the COH rats than that in the sham operation animals. Intravitreal injection of selective A2A AR antagonist SCH442416 up-regulated Müller cell Kir4.1, TASK-1, GS and GLAST expressions and enhanced inward potassium currents compared with those in the COH rats with vehicle control. Meanwhile, the RGC count was higher following intravitreal injection of SCH442416 in the COH rats than that after vehicle injection. The fact that PKA inhibitor H-89 blocked these SCH442416 effects suggested that the PKA signaling pathway was involved in the observed ocular responses following the intravitreal SCH442416 injection. PMID:26063641

  10. Spectroscopic and theoretical investigations of adenosine 5'-diphosphate and adenosine 5'-triphosphate dianions in the gas phase.

    PubMed

    Schinle, Florian; Crider, Paul E; Vonderach, Matthias; Weis, Patrick; Hampe, Oliver; Kappes, Manfred M

    2013-05-14

    Doubly deprotonated adenosine 5'-diphosphate ([ADP-2H](2-)) and adenosine 5'-triphosphate ([ATP-2H](2-)) dianions were investigated using infrared multiple photon dissociation (IR-MPD) and photoelectron spectroscopy. Vibrational spectra acquired in the X-H stretch region (X = C, N, O) and augmented by isotope-labelling were compared to density functional theory (DFT) calculations at the B3LYP/TZVPP level. This suggests that in [ATP-2H](2-) the two phosphate groups adjacent to the ribose ring are preferentially deprotonated. Photoelectron spectra recorded at 4.66 and 6.42 eV photon energies revealed adiabatic detachment energies of 1.35 eV for [ADP-2H](2-) and 3.35 eV for [ATP-2H](2-). Repulsive Coulomb barriers were estimated at ~2.2 eV for [ADP-2H](2-) and ~1.9 eV for [ATP-2H](2-). Time-dependent DFT calculations have been used to simulate the photoelectron spectra. Photodetachment occurs primarily from lone pair orbitals on oxygen atoms within the phosphate chain. PMID:23258289

  11. The first description of cardiac magnetic resonance findings in a severe scorpion envenomation: Is it a stress-induced (Takotsubo) cardiomyopathy like?

    PubMed

    Miranda, Carlos H; Braggion-Santos, Maria F; Schmidt, André; Pazin-Filho, Antônio; Cupo, Palmira

    2015-06-01

    There are more than 1 million cases of scorpion envenomation worldwide. Severe complications due to myocardial depression can happen in some patients, mainly children. A catecholamine-induced myocarditis probably causes this cardiac dysfunction. We describe a case of a 7-year-old boy with a severe scorpion envenomation complicated by pulmonary edema in which the cardiac magnetic resonance (CMR)was performed during the acute phase. The CMR showed an apical ballooning in the left ventricle associated with a left ventricle ejection fraction of 29% and a global edema of the midmyocardium and apical myocardiumin the T2-weighted triple inversion recovery images. The CMR was repeated after 7 months and showed complete recovery of the wall motion in the apical region and of the myocardial function (left ventricle ejection fraction, 60%) associated with normalization of the signal in the T2-weighted triple inversion recovery images. These clinical and laboratory findings, mainly the CMR images, are similar to those observed in stress-induced cardiomyopathy (Takotsubo) reinforcing the hypothesis that the catecholamine's excess has a pivotal function in the pathophysiology of the cardiac dysfunction in these 2 conditions. PMID:25601163

  12. A role for adenosine in coronary vasoregulation in man. Effects of theophylline and enprofylline.

    PubMed

    Edlund, A; Conradsson, T; Sollevi, A

    1995-11-01

    Adenosine has been suggested to have a role in regulation of the tone of the cardiac resistance vessels. To elucidate the coronary vasoregulatory role of endogenous adenosine in man, we studied the effects of adenosine receptor antagonism by theophylline on coronary blood flow at rest and during light exercise. However, theophylline may also exert pharmacological effects not related to adenosine antagonism. To clarify the contribution of endogenous adenosine in coronary hyperaemia, the effect of theophylline was compared to that of enprofylline, a xanthine which exerts similar pharmacological effects as theophylline while lacking antagonistic action at adenosine receptors. Twenty healthy subjects (10 males) aged 22-39 years were examined. Coronary sinus (CS) blood flow and blood oxygen content were determined at rest and during supine bicycle exercise, at a load of 50 watts, for 10 min. Thereafter, stepwise infusion of adenosine (30 to 60 micrograms/kg/min into the subclavian vein) was performed. Theophylline or enprofylline treatment was instituted randomly and double-blind (10 in each group), and the procedures (i.e. determinations at rest, during exercise and during infusion of adenosine) were repeated. In all 20 subjects, basal CS flow was 70 +/- 6 ml/min and the cardiac oxygen extraction ((A-CS)O2D) was 123 +/- 3 ml/l. During exercise, CS flow and (A-CS)O2D increased to 135 +/- 17 ml/min and 132 +/- 3 ml/l, respectively. Adenosine increased CS flow dose dependently to 161 +/- 27 ml/min, while (A-CS)O2D decreased to 66 +/- 7 ml/l. The vasodilatory effect of adenosine was readily counteracted by theophylline, the increase in CS flow being 33% vs. 133% in the control situation. Enprofylline, on the other hand, enhanced the response to exogenous adenosine. Theophylline, at a dose lacking effect on heart rate and blood pressure, decreased CS flow at rest by 14% (P < 0.05) and during exercise by 18% (P < 0.05). ((A-CS)O2D increased by 14% at rest and during exercise

  13. Role of Perfusion at Rest in the Diagnosis of Myocardial Infarction Using Vasodilator Stress Cardiovascular Magnetic Resonance.

    PubMed

    Patel, Mita B; Mor-Avi, Victor; Kawaji, Keigo; Nathan, Sandeep; Kramer, Christopher M; Lang, Roberto M; Patel, Amit R

    2016-04-01

    In clinical practice, perfusion at rest in vasodilator stress single-photon emission computed tomography is commonly used to confirm myocardial infarction (MI) and ischemia and to rule out artifacts. It is unclear whether perfusion at rest carries similar information in cardiovascular magnetic resonance (CMR). We sought to determine whether chronic MI is associated with abnormal perfusion at rest on CMR. We compared areas of infarct and remote myocardium in 31 patients who underwent vasodilator stress CMR (1.5 T), had MI confirmed by late gadolinium enhancement (LGE scar), and coronary angiography within 6 months. Stress perfusion imaging during gadolinium first pass was followed by reversal with aminophylline (75 to 125 mg), rest perfusion, and LGE imaging. Resting and peak-stress time-intensity curves were used to obtain maximal upslopes (normalized by blood pool upslopes), which were compared between infarcted and remote myocardial regions of interest. At rest, there was no significant difference between the slopes in the regions of interest supplied by arteries with and without stenosis >70% (0.31 ± 0.16 vs 0.26 ± 0.15 1/s), irrespective of LGE scar. However, at peak stress, we found significant differences (0.20 ± 0.11 vs 0.30 ± 0.22 1/s; p <0.05), reflecting the expected stress-induced ischemia. Similarly, at rest, there was no difference between infarcted and remote myocardium (0.27 ± 0.14 vs 0.30 ± 0.17 1/s), irrespective of stenosis, but significant differences were seen during stress (0.21 ± 0.16 vs 0.28 ± 0.18 1/s; p <0.001), reflecting inducible ischemia. In conclusion, abnormalities in myocardial perfusion at rest associated with chronic MI are not reliably detectable on CMR images. Accordingly, unlike single-photon emission computed tomography, normal CMR perfusion at rest should not be used to rule out chronic MI. PMID:26830261

  14. N6-adenosine methylation in MiRNAs.

    PubMed

    Berulava, Tea; Rahmann, Sven; Rademacher, Katrin; Klein-Hitpass, Ludgar; Horsthemke, Bernhard

    2015-01-01

    Methylation of N6-adenosine (m6A) has been observed in many different classes of RNA, but its prevalence in microRNAs (miRNAs) has not yet been studied. Here we show that a knockdown of the m6A demethylase FTO affects the steady-state levels of several miRNAs. Moreover, RNA immunoprecipitation with an anti-m6A-antibody followed by RNA-seq revealed that a significant fraction of miRNAs contains m6A. By motif searches we have discovered consensus sequences discriminating between methylated and unmethylated miRNAs. The epigenetic modification of an epigenetic modifier as described here adds a new layer to the complexity of the posttranscriptional regulation of gene expression. PMID:25723394

  15. N6-Adenosine Methylation in MiRNAs

    PubMed Central

    Berulava, Tea; Rahmann, Sven; Rademacher, Katrin; Klein-Hitpass, Ludgar; Horsthemke, Bernhard

    2015-01-01

    Methylation of N6-adenosine (m6A) has been observed in many different classes of RNA, but its prevalence in microRNAs (miRNAs) has not yet been studied. Here we show that a knockdown of the m6A demethylase FTO affects the steady-state levels of several miRNAs. Moreover, RNA immunoprecipitation with an anti-m6A-antibody followed by RNA-seq revealed that a significant fraction of miRNAs contains m6A. By motif searches we have discovered consensus sequences discriminating between methylated and unmethylated miRNAs. The epigenetic modification of an epigenetic modifier as described here adds a new layer to the complexity of the posttranscriptional regulation of gene expression. PMID:25723394

  16. Adenosine Monophosphate-Based Detection of Bacterial Spores

    NASA Technical Reports Server (NTRS)

    Kern, Roger G.; Chen, Fei; Venkateswaran, Kasthuri; Hattori, Nori; Suzuki, Shigeya

    2009-01-01

    A method of rapid detection of bacterial spores is based on the discovery that a heat shock consisting of exposure to a temperature of 100 C for 10 minutes causes the complete release of adenosine monophosphate (AMP) from the spores. This method could be an alternative to the method described in the immediately preceding article. Unlike that method and related prior methods, the present method does not involve germination and cultivation; this feature is an important advantage because in cases in which the spores are those of pathogens, delays involved in germination and cultivation could increase risks of infection. Also, in comparison with other prior methods that do not involve germination, the present method affords greater sensitivity. At present, the method is embodied in a laboratory procedure, though it would be desirable to implement the method by means of a miniaturized apparatus in order to make it convenient and economical enough to encourage widespread use.

  17. Development and structural analysis of adenosine site binding tankyrase inhibitors.

    PubMed

    Haikarainen, Teemu; Waaler, Jo; Ignatev, Alexander; Nkizinkiko, Yves; Venkannagari, Harikanth; Obaji, Ezeogo; Krauss, Stefan; Lehtiö, Lari

    2016-01-15

    Tankyrases 1 and 2, the specialized members of the ARTD protein family, are druggable biotargets whose inhibition may have therapeutic potential against cancer, metabolic disease, fibrotic disease, fibrotic wound healing and HSV viral infections. We have previously identified a novel tankyrase inhibitor scaffold, JW55, and showed that it reduces mouse colon adenoma formation in vivo. Here we expanded the scaffold and profiled the selectivity of the compounds against a panel of human ARTDs. The scaffold also enables a fine modulation of selectivity towards either tankyrase 1 or tankyrase 2. In order to get insight about the binding mode of the inhibitors, we solved crystal structures of the compounds in complex with tankyrase 2. The compounds bind to the adenosine pocket of the catalytic domain and cause changes in the protein structure that are modulated by the chemical modifications of the compounds. The structural analysis allows further rational development of this compound class as a potent and selective tankyrase inhibitor. PMID:26706174

  18. Development and structural analysis of adenosine site binding tankyrase inhibitors.

    PubMed

    Haikarainen, Teemu; Waaler, Jo; Ignatev, Alexander; Nkizinkiko, Yves; Venkannagari, Harikanth; Obaji, Ezeogo; Krauss, Stefan; Lehtiö, Lari

    2016-01-15

    Tankyrases 1 and 2, the specialized members of the ARTD protein family, are druggable biotargets whose inhibition may have therapeutic potential against cancer, metabolic disease, fibrotic disease, fibrotic wound healing and HSV viral infections. We have previously identified a novel tankyrase inhibitor scaffold, JW55, and showed that it reduces mouse colon adenoma formation in vivo. Here we expanded the scaffold and profiled the selectivity of the compounds against a panel of human ARTDs. The scaffold also enables a fine modulation of selectivity towards either tankyrase 1 or tankyrase 2. In order to get insight about the binding mode of the inhibitors, we solved crystal structures of the compounds in complex with tankyrase 2. The compounds bind to the adenosine pocket of the catalytic domain and cause changes in the protein structure that are modulated by the chemical modifications of the compounds. The structural analysis allows further rational development of this compound class as a potent and selective tankyrase inhibitor.

  19. Extraction and analysis of adenosine triphosphate from aquatic environments

    USGS Publications Warehouse

    Stephens, Doyle W.; Shultz, David J.

    1981-01-01

    A variety of adenosine triphosphate (ATP) extraction procedures have been investigated for their applicability to samples from aquatic environments. The cold sulfuric-oxalic acid procedure was best suited to samples consisting of water, periphyton, and sediments. Due to cation and fulvic acid interferences, a spike with a known quantity of ATP was necessary to estimate losses when sediments were extracted. Variable colonization densities for periphyton required that several replicates be extracted to characterize accurately the periphyton community. Extracted samples were stable at room temperature for one to five hours, depending on the ATP concentration, if the pH was below 2. Neutralized samples which were quick frozen and stored at -30C were stable for months. (USGS)

  20. An adenosine triphosphate-independent proteasome activator contributes to the virulence of Mycobacterium tuberculosis

    DOE PAGES

    Jastrab, Jordan B.; Wang, Tong; Murphy, J. Patrick; Bai, Lin; Hu, Kuan; Merkx, Remco; Huang, Jessica; Chatterjee, Champak; Ovaa, Huib; Gygi, Steven P.; et al

    2015-03-23

    Mycobacterium tuberculosis encodes a proteasome that is highly similar to eukaryotic proteasomes and is required to cause lethal infections in animals. The only pathway known to target proteins for proteasomal degradation in bacteria is pupylation, which is functionally analogous to eukaryotic ubiquitylation. However, evidence suggests that the M. tuberculosis proteasome contributes to pupylation-independent pathways as well. To identify new proteasome cofactors that might contribute to such pathways, we isolated proteins that bound to proteasomes overproduced in M. tuberculosis and found a previously uncharacterized protein, Rv3780, which formed rings and capped M. tuberculosis proteasome core particles. Rv3780 enhanced peptide and proteinmore » degradation by proteasomes in an adenosine triphosphate (ATP)-independent manner. We identified putative Rv3780-dependent proteasome substrates and found that Rv3780 promoted robust degradation of the heat shock protein repressor, HspR. Importantly, an M. tuberculosis Rv3780 mutant had a general growth defect, was sensitive to heat stress, and was attenuated for growth in mice. Collectively, these data demonstrate that ATP-independent proteasome activators are not confined to eukaryotes and can contribute to the virulence of one the world’s most devastating pathogens.« less

  1. An adenosine triphosphate-independent proteasome activator contributes to the virulence of Mycobacterium tuberculosis

    SciTech Connect

    Jastrab, Jordan B.; Wang, Tong; Murphy, J. Patrick; Bai, Lin; Hu, Kuan; Merkx, Remco; Huang, Jessica; Chatterjee, Champak; Ovaa, Huib; Gygi, Steven P.; Li, Huilin; Darwin, K. Heran

    2015-03-23

    Mycobacterium tuberculosis encodes a proteasome that is highly similar to eukaryotic proteasomes and is required to cause lethal infections in animals. The only pathway known to target proteins for proteasomal degradation in bacteria is pupylation, which is functionally analogous to eukaryotic ubiquitylation. However, evidence suggests that the M. tuberculosis proteasome contributes to pupylation-independent pathways as well. To identify new proteasome cofactors that might contribute to such pathways, we isolated proteins that bound to proteasomes overproduced in M. tuberculosis and found a previously uncharacterized protein, Rv3780, which formed rings and capped M. tuberculosis proteasome core particles. Rv3780 enhanced peptide and protein degradation by proteasomes in an adenosine triphosphate (ATP)-independent manner. We identified putative Rv3780-dependent proteasome substrates and found that Rv3780 promoted robust degradation of the heat shock protein repressor, HspR. Importantly, an M. tuberculosis Rv3780 mutant had a general growth defect, was sensitive to heat stress, and was attenuated for growth in mice. Collectively, these data demonstrate that ATP-independent proteasome activators are not confined to eukaryotes and can contribute to the virulence of one the world’s most devastating pathogens.

  2. An adenosine triphosphate-independent proteasome activator contributes to the virulence of Mycobacterium tuberculosis

    PubMed Central

    Jastrab, Jordan B.; Wang, Tong; Murphy, J. Patrick; Bai, Lin; Hu, Kuan; Merkx, Remco; Huang, Jessica; Chatterjee, Champak; Ovaa, Huib; Gygi, Steven P.; Li, Huilin; Darwin, K. Heran

    2015-01-01

    Mycobacterium tuberculosis encodes a proteasome that is highly similar to eukaryotic proteasomes and is required to cause lethal infections in animals. The only pathway known to target proteins for proteasomal degradation in bacteria is pupylation, which is functionally analogous to eukaryotic ubiquitylation. However, evidence suggests that the M. tuberculosis proteasome contributes to pupylation-independent pathways as well. To identify new proteasome cofactors that might contribute to such pathways, we isolated proteins that bound to proteasomes overproduced in M. tuberculosis and found a previously uncharacterized protein, Rv3780, which formed rings and capped M. tuberculosis proteasome core particles. Rv3780 enhanced peptide and protein degradation by proteasomes in an adenosine triphosphate (ATP)-independent manner. We identified putative Rv3780-dependent proteasome substrates and found that Rv3780 promoted robust degradation of the heat shock protein repressor, HspR. Importantly, an M. tuberculosis Rv3780 mutant had a general growth defect, was sensitive to heat stress, and was attenuated for growth in mice. Collectively, these data demonstrate that ATP-independent proteasome activators are not confined to eukaryotes and can contribute to the virulence of one the world's most devastating pathogens. PMID:25831519

  3. Adenosine, Ketogenic Diet and Epilepsy: The Emerging Therapeutic Relationship Between Metabolism and Brain Activity

    PubMed Central

    Masino, S.A; Kawamura, M; Wasser, C.D.; Pomeroy, L.T; Ruskin, D.N

    2009-01-01

    For many years the neuromodulator adenosine has been recognized as an endogenous anticonvulsant molecule and termed a “retaliatory metabolite.” As the core molecule of ATP, adenosine forms a unique link between cell energy and neuronal excitability. In parallel, a ketogenic (high-fat, low-carbohydrate) diet is a metabolic therapy that influences neuronal activity significantly, and ketogenic diets have been used successfully to treat medically-refractory epilepsy, particularly in children, for decades. To date the key neural mechanisms underlying the success of dietary therapy are unclear, hindering development of analogous pharmacological solutions. Similarly, adenosine receptor–based therapies for epilepsy and myriad other disorders remain elusive. In this review we explore the physiological regulation of adenosine as an anticonvulsant strategy and suggest a critical role for adenosine in the success of ketogenic diet therapy for epilepsy. While the current focus is on the regulation of adenosine, ketogenic metabolism and epilepsy, the therapeutic implications extend to acute and chronic neurological disorders as diverse as brain injury, inflammatory and neuropathic pain, autism and hyperdopaminergic disorders. Emerging evidence for broad clinical relevance of the metabolic regulation of adenosine will be discussed. PMID:20190967

  4. Topical adenosine increases the proportion of thick hair in Caucasian men with androgenetic alopecia.

    PubMed

    Iwabuchi, Tokuro; Ideta, Ritsuro; Ehama, Ritsuko; Yamanishi, Haruyo; Iino, Masato; Nakazawa, Yosuke; Kobayashi, Takashi; Ohyama, Manabu; Kishimoto, Jiro

    2016-05-01

    Adenosine is an effective treatment for androgenetic alopecia (AGA) in Japanese men and women. Adenosine exerts its effects by significantly increasing the proportion of thick hair. In this study, we assessed the clinical outcome of adenosine treatment for 6 months in 38 Caucasian men. The change in proportion of thick hair (≥60 μm) compared with baseline in the adenosine group was significantly higher than that in the placebo group (P < 0.0001). The change in vellus hair proportion (<40 μm) was significantly lower in the adenosine group than that in the placebo group (P = 0.0154). The change in hair density compared with baseline of the adenosine group was also significantly higher compared with that of the placebo group (P = 0.0470). No adverse effects due to treatment were noted during this study by dermatological evaluation. Adenosine is effective in increasing the proportion of thick hair in Caucasian men with AGA as well as in Japanese men and women.

  5. Adenosine dry powder inhalation for bronchial challenge testing, part 2: proof of concept in asthmatic subjects.

    PubMed

    Lexmond, Anne J; van der Wiel, Erica; Hagedoorn, Paul; Bult, Wouter; Frijlink, Henderik W; ten Hacken, Nick H T; de Boer, Anne H

    2014-09-01

    Adenosine is an indirect stimulus to assess bronchial hyperresponsiveness (BHR(2)) in asthma. Bronchial challenge tests are usually performed with nebulised solutions of adenosine 5'-monophosphate (AMP(3)). The nebulised AMP test has several disadvantages, like long administration times and a restrictive maximum concentration that does not result in BHR in all patients. In this study, we investigated the applicability of dry powder adenosine for assessment of BHR in comparison to nebulised AMP. Dry powder adenosine was prepared in doubling doses (0.01-80 mg) derived from the nebulised AMP test with addition of two higher doses. Five asthmatic subjects performed two bronchial challenge tests, one with nebulised AMP following the 2-min tidal breathing method; the second with dry powder adenosine administered with an investigational inhaler and single slow inhalations (inspiratory flow rate 30-40 L/min). All subjects reached a 20% fall in FEV₁(4) with the new adenosine test (PD20(5)) compared to four subjects with the AMP test (PC₂₀(6)). Dry powder adenosine was well tolerated by all subjects and better appreciated than nebulised AMP. In conclusion, this new bronchial challenge test appears to be a safe and convenient alternative to the nebulised AMP test to assess BHR in asthmatic subjects.

  6. Adenosine, ketogenic diet and epilepsy: the emerging therapeutic relationship between metabolism and brain activity.

    PubMed

    Masino, S A; Kawamura, M; Wasser, C D; Wasser, C A; Pomeroy, L T; Ruskin, D N

    2009-09-01

    For many years the neuromodulator adenosine has been recognized as an endogenous anticonvulsant molecule and termed a "retaliatory metabolite." As the core molecule of ATP, adenosine forms a unique link between cell energy and neuronal excitability. In parallel, a ketogenic (high-fat, low-carbohydrate) diet is a metabolic therapy that influences neuronal activity significantly, and ketogenic diets have been used successfully to treat medically-refractory epilepsy, particularly in children, for decades. To date the key neural mechanisms underlying the success of dietary therapy are unclear, hindering development of analogous pharmacological solutions. Similarly, adenosine receptor-based therapies for epilepsy and myriad other disorders remain elusive. In this review we explore the physiological regulation of adenosine as an anticonvulsant strategy and suggest a critical role for adenosine in the success of ketogenic diet therapy for epilepsy. While the current focus is on the regulation of adenosine, ketogenic metabolism and epilepsy, the therapeutic implications extend to acute and chronic neurological disorders as diverse as brain injury, inflammatory and neuropathic pain, autism and hyperdopaminergic disorders. Emerging evidence for broad clinical relevance of the metabolic regulation of adenosine will be discussed. PMID:20190967

  7. Evidence for an antagonism between caffeine and adenosine in the human cardiovascular system.

    PubMed

    Smits, P; Boekema, P; De Abreu, R; Thien, T; van 't Laar, A

    1987-08-01

    A randomized, double-blind and placebo-controlled study was performed in 10 normotensive male subjects to analyze a possible antagonism between caffeine and adenosine with respect to their effects on the cardiovascular system in humans. Caffeine alone, 250 mg intravenously (i.v.), increased blood pressure by 9/12 mm Hg, and resulted in a fall of heart rate (HR) of 3 beats/min. Plasma epinephrine (E) rose by 114% after caffeine. Adenosine alone, in an increasing dose of 0.04-0.16 mg/kg/min, induced an increase in systolic blood pressure (SBP) (17 mm Hg), and HR (33 beats/min), a moderate fall in diastolic blood pressure (DBP) (-4 mm Hg), and no change of mean arterial pressure (MAP). At the highest adenosine infusion rate, forearm blood flow, skin temperature (ST), and transcutaneous oxygen tension were lowered, whereas plasma (nor)epinephrine was increased 227.2 and 215.9%, respectively. Adenosine infusion after caffeine induced comparable effects, but the fractional adenosine-induced changes of SBP, HR, plasma catecholamines, plasma renin activity (PRA), and aldosterone all were significantly reduced by previous administration of caffeine. Our results indicate an antagonism between caffeine and adenosine in humans, which may support the suggestion that some circulatory effects of caffeine are caused by an interaction with endogenous adenosine. PMID:2441163

  8. Luciferase-based assay for adenosine: application to S-adenosyl-L-homocysteine hydrolase.

    PubMed

    Burgos, Emmanuel S; Gulab, Shivali A; Cassera, María B; Schramm, Vern L

    2012-04-17

    S-Adenosyl-L-homocysteine hydrolase (SAHH) catalyzes the reversible conversion of S-adenosyl-L-homocysteine (SAH) to adenosine (ADO) and L-homocysteine, promoting methyltransferase activity by relief of SAH inhibition. SAH catabolism is linked to S-adenosylmethionine metabolism, and the development of SAHH inhibitors is of interest for new therapeutics with anticancer or cholesterol-lowering effects. We have developed a continuous enzymatic assay for adenosine that facilitates high-throughput analysis of SAHH. This luciferase-based assay is 4000-fold more sensitive than former detection methods and is well suited for continuous monitoring of ADO formation in a 96-well-plate format. The high-affinity adenosine kinase from Anopheles gambiae efficiently converts adenosine to adenosine monophosphate (AMP) in the presence of guanosine triphosphate. AMP is converted to adenosine triphosphate and coupled to firefly luciferase. With this procedure, kinetic parameters (K(m), k(cat)) for SAHH were obtained, in good agreement with literature values. Assay characteristics include sustained light output combined with ultrasensitive detection (10(-7) unit of SAHH). The assay is documented with the characterization of slow-onset inhibition for inhibitors of the hydrolase. Application of this assay may facilitate the development of SAHH inhibitors and provide an ultrasensitive detection for the formation of adenosine from other biological reactions.

  9. Role of adenosine signalling and metabolism in β-cell regeneration

    SciTech Connect

    Andersson, Olov

    2014-02-01

    Glucose homeostasis, which is controlled by the endocrine cells of the pancreas, is disrupted in both type I and type II diabetes. Deficiency in the number of insulin-producing β cells – a primary cause of type I diabetes and a secondary contributor of type II diabetes – leads to hyperglycemia and hence an increase in the need for insulin. Although diabetes can be controlled with insulin injections, a curative approach is needed. A potential approach to curing diabetes involves regenerating the β-cell mass, e.g. by increasing β-cell proliferation, survival, neogenesis or transdifferentiation. The nucleoside adenosine and its cognate nucleotide ATP have long been known to affect insulin secretion, but have more recently been shown to increase β-cell proliferation during homeostatic control and regeneration of the β-cell mass. Adenosine is also known to have anti-inflammatory properties, and agonism of adenosine receptors can promote the survival of β-cells in an inflammatory microenvironment. In this review, both intracellular and extracellular mechanisms of adenosine and ATP are discussed in terms of their established and putative effects on β-cell regeneration. - Highlights: • A potential way to cure diabetes is to regenerate the β-cell mass by promoting cell survival, proliferation or neogenesis. • Adenosine may promote β-cell regeneration through several cellular mechanisms. • Adenosine and its cognate nucleotide ATP can each promote β-cell proliferation. • Do adenosine and ATP interact in promoting β-cell proliferation?.

  10. The resurgence of A2B adenosine receptor signaling

    PubMed Central

    Aherne, Carol M.; Kewley, Emily M.; Eltzschig, Holger K.

    2010-01-01

    Since its discovery as a low-affinity adenosine receptor (AR), the A2B receptor (A2BAR), has proven enigmatic in its function. The previous discovery of the A2AAR, which shares many similarities with the A2BAR but demonstrates significantly greater affinity for its endogenous ligand, led to the original perception that the A2BAR was not of substantial physiologic relevance. In addition, lack of specific pharmacological agents targeting the A2BAR made its initial characterization challenging. However, the importance of this receptor was reconsidered when it was observed that the A2BAR is highly transcriptionally regulated by factors implicated in inflammatory hypoxia. Moreover, the notion that during ischemia or inflammation extracellular adenosine is dramatically elevated to levels sufficient for A2BAR activation, indicated that A2BAR signaling may be important to dampen inflammation particularly during tissue hypoxia. In addition, the recent advent of techniques for murine genetic manipulation along with development of pharmacological agents with enhanced A2BAR specificity has provided invaluable tools for focused studies on the explicit role of A2BAR signaling in different disease models. Currently, studies performed with combined genetic and pharmacological approaches have demonstrated that A2BAR signaling plays a tissue protective role in many models of acute diseases e.g. myocardial ischemia, or acute lung injury. These studies indicate that the A2BAR is expressed on a wide variety of cell types and exerts tissue/cell specific effects. This is an important consideration for future studies where tissue or cell type specific targeting of the A2BAR may be used as therapeutic approach. PMID:20546702

  11. Structural and Metabolic Specificity of Methylthiocoformycin for Malarial Adenosine Deaminases

    SciTech Connect

    Ho, M.; Cassera, M; Madrid, D; Ting, L; Tyler, P; Kim, K; Almo, S; Schramm, V

    2009-01-01

    Plasmodium falciparum is a purine auxotroph requiring hypoxanthine as a key metabolic precursor. Erythrocyte adenine nucleotides are the source of the purine precursors, making adenosine deaminase (ADA) a key enzyme in the pathway of hypoxanthine formation. Methylthioadenosine (MTA) is a substrate for most malarial ADAs, but not for human ADA. The catalytic site specificity of malarial ADAs permits methylthiocoformycin (MT-coformycin) to act as a Plasmodium-specific transition state analogue with low affinity for human ADA. The structural basis for MTA and MT-coformycin specificity in malarial ADAs is the subject of speculation. Here, the crystal structure of ADA from Plasmodium vivax (PvADA) in a complex with MT-coformycin reveals an unprecedented binding geometry for 5?-methylthioribosyl groups in the malarial ADAs. Compared to malarial ADA complexes with adenosine or deoxycoformycin, 5?-methylthioribosyl groups are rotated 130 degrees. A hydrogen bonding network between Asp172 and the 3?-hydroxyl of MT-coformycin is essential for recognition of the 5?-methylthioribosyl group. Water occupies the 5?-hydroxyl binding site when MT-coformycin is bound. Mutagenesis of Asp172 destroys the substrate specificity for MTA and MT-coformycin. Kinetic, mutagenic, and structural analyses of PvADA and kinetic analysis of five other Plasmodium ADAs establish the unique structural basis for its specificity for MTA and MT-coformycin. Plasmodium gallinaceum ADA does not use MTA as a substrate, is not inhibited by MT-coformycin, and is missing Asp172. Treatment of P. falciparum cultures with coformycin or MT-coformycin in the presence of MTA is effective in inhibiting parasite growth.

  12. Amp Synthesis in Aqueous Solution of Adenosine and Phosphorus Pentoxide

    NASA Astrophysics Data System (ADS)

    Yamagata, Y.; Kojima, H.; Ejiri, K.; Inomata, K.

    1982-12-01

    Possible formation of a P4O10 molecule in magma, the stability of the molecule in hydrous volcanic gas at high temperatures and a possible prebiotic phosphate cycle were discussed in relation to chemical evolution. To demonstrate the utility of phosphorus pentoxide as a phosphorylating agent, aqueous solutions of adenosine (0.02M) and phosphorus pentoxide (0.2M) were incubated at 37°C for 5 months. The pH of the solutions was adjusted every day or every few days to each fixed value (9.0, 10.5, 11.5, 12.5) with 10 N NaOH. The HPLC analysis showed the formation of 2'-AMP, 3'-AMP, 5'-AMP, cyclic (2' 3')-AMP and cyclic (3' 5')-AMP. The main components of the products were 2'- and 3'-AMP, though cyclic (2' 3')-AMP was the main component in the early period of the incubation at pH 9.0. The yields (conversion rate of adenosine to AMPs) were increased almost linearly with the incubation time for 5 months in the case of pH 9.0. The final yields were about 3% (pH 9.0), 6% (pH 9.0, 1 M NaCl), 5% (pH 9.0, 0.01 M CaCl2, 0.01 M MgCl2), 7% (pH 9.0, 0.5 M NaCl, 0.01 M CaCl2, 0.01 M MgCl2), 9% (pH 9.0, 1 M NaCl, 0.01 M CaCl2, 0.01 M MgCl2), 32% (pH 10.5), 43% (pH 11.5), 35% (pH 12.5).

  13. Role of Adenosine Signaling on Pentylenetetrazole-Induced Seizures in Zebrafish

    PubMed Central

    Siebel, Anna Maria; Menezes, Fabiano Peres; Capiotti, Katiucia Marques; Kist, Luiza Wilges; Schaefer, Isabel da Costa; Frantz, Juliana Zanetti; Bogo, Maurício Reis; Da Silva, Rosane Souza

    2015-01-01

    Abstract Adenosine is a well-known endogenous modulator of neuronal excitability with anticonvulsant properties. Thus, the modulation exerted by adenosine might be an effective tool to control seizures. In this study, we investigated the effects of drugs that are able to modulate adenosinergic signaling on pentylenetetrazole (PTZ)-induced seizures in adult zebrafish. The adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) decreased the latency to the onset of the tonic-clonic seizure stage. The adenosine A1 receptor agonist cyclopentyladenosine (CPA) increased the latency to reach the tonic-clonic seizure stage. Both the adenosine A2A receptor agonist and antagonist, CGS 21680 and ZM 241385, respectively, did not promote changes in seizure parameters. Pretreatment with the ecto-5′nucleotidase inhibitor adenosine 5′-(α,β-methylene) diphosphate (AMPCP) decreased the latency to the onset of the tonic-clonic seizure stage. However, when pretreated with the adenosine deaminase (ADA) inhibitor, erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA), or with the nucleoside transporter (NT) inhibitors, dipyridamole and S-(4-Nitrobenzyl)-6-thioinosine (NBTI), animals showed longer latency to reach the tonic-clonic seizure status. Finally, our molecular analysis of the c-fos gene expression corroborates these behavioral results. Our findings indicate that the activation of adenosine A1 receptors is an important mechanism to control the development of seizures in zebrafish. Furthermore, the actions of ecto-5′-nucleotidase, ADA, and NTs are directly involved in the control of extracellular adenosine levels and have an important role in the development of seizure episodes in zebrafish. PMID:25560904

  14. Adenosine modulates light responses of rat retinal ganglion cell photoreceptors througha cAMP-mediated pathway

    PubMed Central

    Sodhi, Puneet; Hartwick, Andrew T E

    2014-01-01

    Adenosine is an established neuromodulator in the mammalian retina, with A1 adenosine receptors being especially prevalent in the innermost ganglion cell layer. Activation of A1 receptors causes inhibition of adenylate cyclase, decreases in intracellular cyclic AMP (cAMP) levels and inhibition of protein kinase A (PKA). In this work, our aim was to characterize the effects of adenosine on the light responses of intrinsically photosensitive retinal ganglion cells (ipRGCs) and to determine whether these photoreceptors are subject to neuromodulation through intracellular cAMP-related signalling pathways. Using multielectrode array recordings from postnatal and adult rat retinas, we demonstrated that adenosine significantly shortened the duration of ipRGC photoresponses and reduced the number of light-evoked spikes fired by these neurons. The effects were A1 adenosine receptor-mediated, and the expression of this receptor on melanopsin-containing ipRGCs was confirmed by calcium imaging experiments on isolated cells in purified cultures. While inhibition of the cAMP/PKA pathway by adenosine shortened ipRGC light responses, stimulation of this pathway with compounds such as forskolin had the opposite effect and lengthened the duration of ipRGC spiking. Our findings reveal that the modification of ipRGC photoresponses through a cAMP/PKA pathway is a general feature of rat ganglion cell photoreceptors, and this pathway can be inhibited through activation of A1 receptors by adenosine. As adenosine levels in the retina rise at night, adenosinergic modulation of ipRGCs may serve as an internal regulatory mechanism to limit transmission of nocturnal photic signals by ipRGCs to the brain. Targeting retinal A1 adenosine receptors for ipRGC inhibition represents a potential therapeutic target for sleep disorders and migraine-associated photophobia. PMID:25038240

  15. Role of adenosine signaling on pentylenetetrazole-induced seizures in zebrafish.

    PubMed

    Siebel, Anna Maria; Menezes, Fabiano Peres; Capiotti, Katiucia Marques; Kist, Luiza Wilges; da Costa Schaefer, Isabel; Frantz, Juliana Zanetti; Bogo, Maurício Reis; Da Silva, Rosane Souza; Bonan, Carla Denise

    2015-04-01

    Adenosine is a well-known endogenous modulator of neuronal excitability with anticonvulsant properties. Thus, the modulation exerted by adenosine might be an effective tool to control seizures. In this study, we investigated the effects of drugs that are able to modulate adenosinergic signaling on pentylenetetrazole (PTZ)-induced seizures in adult zebrafish. The adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) decreased the latency to the onset of the tonic-clonic seizure stage. The adenosine A1 receptor agonist cyclopentyladenosine (CPA) increased the latency to reach the tonic-clonic seizure stage. Both the adenosine A2A receptor agonist and antagonist, CGS 21680 and ZM 241385, respectively, did not promote changes in seizure parameters. Pretreatment with the ecto-5'nucleotidase inhibitor adenosine 5'-(α,β-methylene) diphosphate (AMPCP) decreased the latency to the onset of the tonic-clonic seizure stage. However, when pretreated with the adenosine deaminase (ADA) inhibitor, erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA), or with the nucleoside transporter (NT) inhibitors, dipyridamole and S-(4-Nitrobenzyl)-6-thioinosine (NBTI), animals showed longer latency to reach the tonic-clonic seizure status. Finally, our molecular analysis of the c-fos gene expression corroborates these behavioral results. Our findings indicate that the activation of adenosine A1 receptors is an important mechanism to control the development of seizures in zebrafish. Furthermore, the actions of ecto-5'-nucleotidase, ADA, and NTs are directly involved in the control of extracellular adenosine levels and have an important role in the development of seizure episodes in zebrafish.

  16. Severe hemorrhage attenuates cardiopulmonary chemoreflex control of regional sympathetic outputs via NTS adenosine receptors.

    PubMed

    Minic, Zeljka; Li, Cailian; O'Leary, Donal S; Scislo, Tadeusz J

    2014-09-15

    Selective stimulation of inhibitory A1 and facilitatory A2a adenosine receptor subtypes located in the nucleus of the solitary tract (NTS) powerfully inhibits cardiopulmonary chemoreflex (CCR) control of regional sympathetic outputs via different mechanisms: direct inhibition of glutamate release and facilitation of an inhibitory neurotransmitter release, respectively. However, it remains unknown whether adenosine naturally released into the NTS has similar inhibitory effects on the CCR as the exogenous agonists do. Our previous study showed that adenosine is released into the NTS during severe hemorrhage and contributes to reciprocal changes of renal (decreases) and adrenal (increases) sympathetic nerve activity observed in this setting. Both A1 and A2a adenosine receptors are involved. Therefore, we tested the hypothesis that, during severe hemorrhage, CCR control of the two sympathetic outputs is attenuated by adenosine naturally released into the NTS. We compared renal and adrenal sympathoinhibitory responses evoked by right atrial injections of 5HT3 receptor agonist phenylbiguanide (2-8 μg/kg) under control conditions, during hemorrhage, and during hemorrhage preceded by blockade of NTS adenosine receptors with bilateral microinjections of 8-(p-sulfophenyl) theophylline (1 nmol/100 nl) in urethane/chloralose anesthetized rats. CCR-mediated inhibition of renal and adrenal sympathetic activity was significantly attenuated during severe hemorrhage despite reciprocal changes in the baseline activity levels, and this attenuation was removed by bilateral blockade of adenosine receptors in the caudal NTS. This confirmed that adenosine endogenously released into the NTS has a similar modulatory effect on integration of cardiovascular reflexes as stimulation of NTS adenosine receptors with exogenous agonists.

  17. Severe hemorrhage attenuates cardiopulmonary chemoreflex control of regional sympathetic outputs via NTS adenosine receptors.

    PubMed

    Minic, Zeljka; Li, Cailian; O'Leary, Donal S; Scislo, Tadeusz J

    2014-09-15

    Selective stimulation of inhibitory A1 and facilitatory A2a adenosine receptor subtypes located in the nucleus of the solitary tract (NTS) powerfully inhibits cardiopulmonary chemoreflex (CCR) control of regional sympathetic outputs via different mechanisms: direct inhibition of glutamate release and facilitation of an inhibitory neurotransmitter release, respectively. However, it remains unknown whether adenosine naturally released into the NTS has similar inhibitory effects on the CCR as the exogenous agonists do. Our previous study showed that adenosine is released into the NTS during severe hemorrhage and contributes to reciprocal changes of renal (decreases) and adrenal (increases) sympathetic nerve activity observed in this setting. Both A1 and A2a adenosine receptors are involved. Therefore, we tested the hypothesis that, during severe hemorrhage, CCR control of the two sympathetic outputs is attenuated by adenosine naturally released into the NTS. We compared renal and adrenal sympathoinhibitory responses evoked by right atrial injections of 5HT3 receptor agonist phenylbiguanide (2-8 μg/kg) under control conditions, during hemorrhage, and during hemorrhage preceded by blockade of NTS adenosine receptors with bilateral microinjections of 8-(p-sulfophenyl) theophylline (1 nmol/100 nl) in urethane/chloralose anesthetized rats. CCR-mediated inhibition of renal and adrenal sympathetic activity was significantly attenuated during severe hemorrhage despite reciprocal changes in the baseline activity levels, and this attenuation was removed by bilateral blockade of adenosine receptors in the caudal NTS. This confirmed that adenosine endogenously released into the NTS has a similar modulatory effect on integration of cardiovascular reflexes as stimulation of NTS adenosine receptors with exogenous agonists. PMID:25063794

  18. Adenosine Modulates the Oocyte Developmental Competence by Exposing Stages and Synthetic Blocking during In Vitro Maturation.

    PubMed

    Cheon, Yong-Pil

    2016-06-01

    Purine metabolism is known factor for nuclear maturation of oocytes through both follicle cells and oocyte itself. However, it is largely unknown the roles of purine metabolism in the oocyte competence for fertilization and early development. In this study, the effects of adenosine in oocyte competence for development were examined using adenosine and its synthetic inhibitors. Adenosine treatment from GV intact stage for 18 hr (fGV) caused of decrease the fertilization rate but of increase the cleavage rate compared from the other stage treatment groups. Hadacidin did not effect on fertilization rate but increased cleavage rate without stage specificity. Adenosine did not block the effects of hadacidin with the exception of fGV group. By the inhibition of purine synthetic pathways the fertilization rate was decreased in the fGV and fGVB groups but increased in the fMII group. Exogenous adenosine caused of decrease fertilization rate in the fGVB group but increase in the fMII group. Cleavage rate was dramatically increased in the adenosine treatment with synthetic inhibitors. It means that the metabolism of purine has stage specific effects on fertilization and cleavage. Exogenous adenosine had only can improve oocyte developmental competence when it treated at GV intact stage. On the other hand, endogenous synthesis in all maturation stage caused of increase the cleavage rate without effects on fertilization. These data suggest that adenosine at GV stage as a paracrine fashion and inhibitions of endogenous adenosine in all stage improve oocyte developmental competence.. PMID:27660830

  19. The NLRP3 inflammasome is activated by nanoparticles through ATP, ADP and adenosine

    PubMed Central

    Baron, L; Gombault, A; Fanny, M; Villeret, B; Savigny, F; Guillou, N; Panek, C; Le Bert, M; Lagente, V; Rassendren, F; Riteau, N; Couillin, I

    2015-01-01

    The NLR pyrin domain containing 3 (NLRP3) inflammasome is a major component of the innate immune system, but its mechanism of activation by a wide range of molecules remains largely unknown. Widely used nano-sized inorganic metal oxides such as silica dioxide (nano-SiO2) and titanium dioxide (nano-TiO2) activate the NLRP3 inflammasome in macrophages similarly to silica or asbestos micro-sized particles. By investigating towards the molecular mechanisms of inflammasome activation in response to nanoparticles, we show here that active adenosine triphosphate (ATP) release and subsequent ATP, adenosine diphosphate (ADP) and adenosine receptor signalling are required for inflammasome activation. Nano-SiO2 or nano-TiO2 caused a significant increase in P2Y1, P2Y2, A2A and/or A2B receptor expression, whereas the P2X7 receptor was downregulated. Interestingly, IL-1β secretion in response to nanoparticles is increased by enhanced ATP and ADP hydrolysis, whereas it is decreased by adenosine degradation or selective A2A or A2B receptor inhibition. Downstream of these receptors, our results show that nanoparticles activate the NLRP3 inflammasome via activation of PLC-InsP3 and/or inhibition of adenylate cyclase (ADCY)-cAMP pathways. Finally, a high dose of adenosine triggers inflammasome activation and IL-1β secretion through adenosine cellular uptake by nucleotide transporters and by its subsequent transformation in ATP by adenosine kinase. In summary, we show for the first time that extracellular adenosine activates the NLRP3 inflammasome by two ways: by interacting with adenosine receptors at nanomolar/micromolar concentrations and through cellular uptake by equilibrative nucleoside transporters at millimolar concentrations. These findings provide new molecular insights on the mechanisms of NLRP3 inflammasome activation and new therapeutic strategies to control inflammation. PMID:25654762

  20. Adenosine Modulates the Oocyte Developmental Competence by Exposing Stages and Synthetic Blocking during In Vitro Maturation

    PubMed Central

    Cheon, Yong-Pil

    2016-01-01

    Purine metabolism is known factor for nuclear maturation of oocytes through both follicle cells and oocyte itself. However, it is largely unknown the roles of purine metabolism in the oocyte competence for fertilization and early development. In this study, the effects of adenosine in oocyte competence for development were examined using adenosine and its synthetic inhibitors. Adenosine treatment from GV intact stage for 18 hr (fGV) caused of decrease the fertilization rate but of increase the cleavage rate compared from the other stage treatment groups. Hadacidin did not effect on fertilization rate but increased cleavage rate without stage specificity. Adenosine did not block the effects of hadacidin with the exception of fGV group. By the inhibition of purine synthetic pathways the fertilization rate was decreased in the fGV and fGVB groups but increased in the fMII group. Exogenous adenosine caused of decrease fertilization rate in the fGVB group but increase in the fMII group. Cleavage rate was dramatically increased in the adenosine treatment with synthetic inhibitors. It means that the metabolism of purine has stage specific effects on fertilization and cleavage. Exogenous adenosine had only can improve oocyte developmental competence when it treated at GV intact stage. On the other hand, endogenous synthesis in all maturation stage caused of increase the cleavage rate without effects on fertilization. These data suggest that adenosine at GV stage as a paracrine fashion and inhibitions of endogenous adenosine in all stage improve oocyte developmental competence.. PMID:27660830

  1. Smoke extract impairs adenosine wound healing: implications of smoke-generated reactive oxygen species.

    PubMed

    Allen-Gipson, Diane S; Zimmerman, Matthew C; Zhang, Hui; Castellanos, Glenda; O'Malley, Jennifer K; Alvarez-Ramirez, Horacio; Kharbanda, Kusum; Sisson, Joseph H; Wyatt, Todd A

    2013-05-01

    Adenosine concentrations are elevated in the lungs of patients with asthma and chronic obstructive pulmonary disease, where it balances between tissue repair and excessive airway remodeling. We previously demonstrated that the activation of the adenosine A2A receptor promotes epithelial wound closure. However, the mechanism by which adenosine-mediated wound healing occurs after cigarette smoke exposure has not been investigated. The present study investigates whether cigarette smoke exposure alters adenosine-mediated reparative properties via its ability to induce a shift in the oxidant/antioxidant balance. Using an in vitro wounding model, bronchial epithelial cells were exposed to 5% cigarette smoke extract, were wounded, and were then stimulated with either 10 μM adenosine or the specific A2A receptor agonist, 5'-(N-cyclopropyl)-carboxamido-adenosine (CPCA; 10 μM), and assessed for wound closure. In a subset of experiments, bronchial epithelial cells were infected with adenovirus vectors encoding human superoxide dismutase and/or catalase or control vector. In the presence of 5% smoke extract, significant delay was evident in both adenosine-mediated and CPCA-mediated wound closure. However, cells pretreated with N-acetylcysteine (NAC), a nonspecific antioxidant, reversed smoke extract-mediated inhibition. We found that cells overexpressing mitochondrial catalase repealed the smoke extract inhibition of CPCA-stimulated wound closure, whereas superoxide dismutase overexpression exerted no effect. Kinase experiments revealed that smoke extract significantly reduced the A2A-mediated activation of cyclic adenosine monophosphate-dependent protein kinase. However, pretreatment with NAC reversed this effect. In conclusion, our data suggest that cigarette smoke exposure impairs A2A-stimulated wound repair via a reactive oxygen species-dependent mechanism, thereby providing a better understanding of adenosine signaling that may direct the development of pharmacological

  2. DIFFUSIVE-Magnetoresistance(DMR) Proton(PMR)/Hydrogen-ion WATER: PRE-``Fert''/``Grunberg'' GMR[and CMR]: Quo-Vadis ``Honesty''???: PLAGIARISM!!!

    NASA Astrophysics Data System (ADS)

    Fart, Albart; Gruntbug, Peter; Siegel, Edward

    2011-03-01

    Proton/Hydrogen-ion Diffusive-Magnetoresistance(DMR) of Siegel[APS March-Mtgs.(70s)] based upon Siegel[Int'l. Conf. Mag.-Alloys and Oxides("ICMAO"), The Technion(77); J. Mag. Mag. Mtls. 7, 312(78)] FIRST experimental-discovery of GMR and FIRST theoretical prediction of CMR[ibid. 7, 338 (78)], facilitates NEW water production in global-warming exacerbated dry arid/semi-arid regions: Only HYDROGEN is/can be "FLYING-WATER"!!! (aka "chemical-rain-in-pipelines"). EMET/TRUTH-in-the-``SEANCES'', would-be "Sciences": C. Perelman-Corredoira [Against the Tide(07)] featuring Martin-Bradshaw ["Healing the SHAME That BINDS You"(80s)] systemic sociological-dysfunctionality(S-D), and Grigory Perelman's HEROIC ETHICS (refusal of both pure-maths Poincare-conjecture proof 2007 Fields-medal and 2010 Clay-Institute so-called/media-hyped/P.Red/spin-doctored millennium-prize million-dollar would-be award, militates as well in the current "SEANCE" of physics/maths politics/media-hype/P.R /spin-doctoring VS. Siegel FIRST experimental GMR a never-acknowledged full decade PRE-"Fert"(88) /"Grunberg(89)" ``Phales-GroPE''/Thompson-CSF/ KFZ-JEWlich 2007 physics Wolf/Japan/Nobel-prizes!!!

  3. Binding of adenosine and receptor-specific analogues to lymphocytes from control subjects and patients with common variable immunodeficiency.

    PubMed Central

    Shah, T; Simpson, R J; Webster, A D; Peters, T J

    1987-01-01

    Studies were performed on the binding of tritiated adenosine and its analogues, 5'-N-ethylcarboxamide adenosine (NECA) and N6-phenylisopropyladenosine (PIA), to human peripheral blood lymphocytes. These revealed binding only of adenosine (Kd, 1-10 microM, 14,000 binding sites/cell), which was abolished by dipyridamole, a specific adenosine transport inhibitor, suggesting that the binding is to the nucleoside transporter. The absence of high affinity (Kd less than or equal to 1 microM) binding of adenosine or of the two analogues. NECA and PIA suggests that the previously reported effects of adenosine on cAMP formation are not mediated by cell surface specific nucleoside receptors. Binding of adenosine to the carrier in lymphocytes from patients with common variable immunodeficiency was similar to those from control subjects. PMID:2958197

  4. Development of a luminescent G-quadruplex-selective iridium(III) complex for the label-free detection of adenosine

    PubMed Central

    Lu, Lihua; Zhong, Hai-Jing; He, Bingyong; Leung, Chung-Hang; Ma, Dik-Lung

    2016-01-01

    A panel of six luminescent iridium(III) complexes were synthesized and evaluated for their ability to act as G-quadruplex-selective probes. The novel iridium(III) complex 1 was found to be highly selective for G-quadruplex DNA, and was employed for the construction of a label-free G-quadruplex-based adenosine detection assay in aqueous solution. Two different detection strategies were investigated for adenosine detection, and the results showed that initial addition of adenosine to the adenosine aptamer gave superior results. The assay exhibited a linear response for adenosine in the concentration range of 5 to 120 μM (R2 = 0.992), and the limit of detection for adenosine was 5 μM. Moreover, this assay was highly selective for adenosine over other nucleosides, and exhibited potential use for biological sample analysis. PMID:26778273

  5. Development of a luminescent G-quadruplex-selective iridium(III) complex for the label-free detection of adenosine

    NASA Astrophysics Data System (ADS)

    Lu, Lihua; Zhong, Hai-Jing; He, Bingyong; Leung, Chung-Hang; Ma, Dik-Lung

    2016-01-01

    A panel of six luminescent iridium(III) complexes were synthesized and evaluated for their ability to act as G-quadruplex-selective probes. The novel iridium(III) complex 1 was found to be highly selective for G-quadruplex DNA, and was employed for the construction of a label-free G-quadruplex-based adenosine detection assay in aqueous solution. Two different detection strategies were investigated for adenosine detection, and the results showed that initial addition of adenosine to the adenosine aptamer gave superior results. The assay exhibited a linear response for adenosine in the concentration range of 5 to 120 μM (R2 = 0.992), and the limit of detection for adenosine was 5 μM. Moreover, this assay was highly selective for adenosine over other nucleosides, and exhibited potential use for biological sample analysis.

  6. A2B adenosine receptors mediate relaxation of the pig intravesical ureter: adenosine modulation of non adrenergic non cholinergic excitatory neurotransmission

    PubMed Central

    Hernández, Medardo; Barahona, María Victoria; Bustamante, Salvador; García-Sacristán, Albino; Orensanz, Luis M

    1999-01-01

    The present study was designed to characterize the adenosine receptors involved in the relaxation of the pig intravesical ureter, and to investigate the action of adenosine on the non adrenergic non cholinergic (NANC) excitatory ureteral neurotransmission. In U46619 (10−7  M)-contracted strips treated with the adenosine uptake inhibitor, nitrobenzylthioinosine (NBTI, 10−6  M), adenosine and related analogues induced relaxations with the following potency order: 5′-N-ethylcarboxamidoadenosine (NECA)=5′-(N-cyclopropyl)-carboxamidoadenosine (CPCA)=2-chloroadenosine (2-CA)>adenosine>cyclopentyladenosine (CPA)=N6-(3-iodobenzyl)-adenosine-5′-N-methylcarboxamide (IB-MECA)=2-[p-(carboxyethyl)-phenylethylamino]-5′-N-ethylcarboxamidoadenosine (CGS21680). Epithelium removal or incubation with indomethacin (3×10−6  M) and L-NG-nitroarginine (L-NOARG, 3×10−5  M), inhibitors of prostanoids and nitric oxide (NO) synthase, respectively, failed to modify the relaxations to adenosine. 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 10−8 M) and 4-(2-[7-amino-2-(2-furyl) [1,2,4]-triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385, 3×10−8  M and 10−7  M), A1 and A2A receptor selective antagonists, respectively, did not modify the relaxations to adenosine or NECA. 8-phenyltheophylline (8-PT, 10−5  M) and DPCPX (10−6  M), which block A1/A2-receptors, reduced such relaxations. In strips treated with guanethidine (10−5  M), atropine (10−7  M), L-NOARG (3×10−5  M) and indomethacin (3×10−6  M), both electrical field stimulation (EFS, 5 Hz) and exogenous ATP (10−4  M) induced contractions of preparations. 8-PT (10−5  M) increased both contractions. DPCPX (10−8  M), NECA (10−4  M), CPCA, (10−4  M) and 2-CA (10−4  M) did not alter the contractions to EFS. The present results suggest that adenosine relaxes the pig intravesical ureter, independently of prostanoids

  7. Renoprotective Effects of a Highly Selective A3 Adenosine Receptor Antagonist in a Mouse Model of Adriamycin-induced Nephropathy.

    PubMed

    Min, Hye Sook; Cha, Jin Joo; Kim, Kitae; Kim, Jung Eun; Ghee, Jung Yeon; Kim, Hyunwook; Lee, Ji Eun; Han, Jee Young; Jeong, Lak Shin; Cha, Dae Ryong; Kang, Young Sun

    2016-09-01

    The concentration of adenosine in the normal kidney increases markedly during renal hypoxia, ischemia, and inflammation. A recent study reported that an A3 adenosine receptor (A3AR) antagonist attenuated the progression of renal fibrosis. The adriamycin (ADX)-induced nephropathy model induces podocyte injury, which results in severe proteinuria and progressive glomerulosclerosis. In this study, we investigated the preventive effect of a highly selective A3AR antagonist (LJ1888) in ADX-induced nephropathy. Three groups of six-week-old Balb/c mice were treated with ADX (11 mg/kg) for four weeks and LJ1888 (10 mg/kg) for two weeks as following: 1) control; 2) ADX; and 3) ADX + LJ1888. ADX treatment decreased body weight without a change in water and food intake, but this was ameliorated by LJ1888 treatment. Interestingly, LJ1888 lowered plasma creatinine level, proteinuria, and albuminuria, which had increased during ADX treatment. Furthermore, LJ1888 inhibited urinary nephrin excretion as a podocyte injury marker, and urine 8-isoprostane and kidney lipid peroxide concentration, which are markers of oxidative stress, increased after injection of ADX. ADX also induced the activation of proinflammatory and profibrotic molecules such as TGF-β1, MCP-1, PAI-1, type IV collagen, NF-κB, NOX4, TLR4, TNFα, IL-1β, and IFN-γ, but they were remarkably suppressed after LJ1888 treatment. In conclusion, our results suggest that LJ1888 has a renoprotective effect in ADX-induced nephropathy, which might be associated with podocyte injury through oxidative stress. Therefore, LJ1888, a selective A3AR antagonist, could be considered as a potential therapeutic agent in renal glomerular diseases which include podocyte injury and proteinuria. PMID:27510383

  8. Renoprotective Effects of a Highly Selective A3 Adenosine Receptor Antagonist in a Mouse Model of Adriamycin-induced Nephropathy

    PubMed Central

    2016-01-01

    The concentration of adenosine in the normal kidney increases markedly during renal hypoxia, ischemia, and inflammation. A recent study reported that an A3 adenosine receptor (A3AR) antagonist attenuated the progression of renal fibrosis. The adriamycin (ADX)-induced nephropathy model induces podocyte injury, which results in severe proteinuria and progressive glomerulosclerosis. In this study, we investigated the preventive effect of a highly selective A3AR antagonist (LJ1888) in ADX-induced nephropathy. Three groups of six-week-old Balb/c mice were treated with ADX (11 mg/kg) for four weeks and LJ1888 (10 mg/kg) for two weeks as following: 1) control; 2) ADX; and 3) ADX + LJ1888. ADX treatment decreased body weight without a change in water and food intake, but this was ameliorated by LJ1888 treatment. Interestingly, LJ1888 lowered plasma creatinine level, proteinuria, and albuminuria, which had increased during ADX treatment. Furthermore, LJ1888 inhibited urinary nephrin excretion as a podocyte injury marker, and urine 8-isoprostane and kidney lipid peroxide concentration, which are markers of oxidative stress, increased after injection of ADX. ADX also induced the activation of proinflammatory and profibrotic molecules such as TGF-β1, MCP-1, PAI-1, type IV collagen, NF-κB, NOX4, TLR4, TNFα, IL-1β, and IFN-γ, but they were remarkably suppressed after LJ1888 treatment. In conclusion, our results suggest that LJ1888 has a renoprotective effect in ADX-induced nephropathy, which might be associated with podocyte injury through oxidative stress. Therefore, LJ1888, a selective A3AR antagonist, could be considered as a potential therapeutic agent in renal glomerular diseases which include podocyte injury and proteinuria. PMID:27510383

  9. [Stress echocardiography in diagnosis of coronary artery disease].

    PubMed

    Gackowski, A; Piwowarska, W

    1996-03-01

    Diagnostic value of stress echocardiography is discussed. Different stress modalities such as exercise, pharmacological tests (dipyridamole, adenosine, dobutamine), and atrial pacing are characterized and compared. Stress echo protocols are also described. A value of stress echocardiography is discussed in comparison with ECG stress testing and thalium perfusion scintigraphy. Stress echocardiography is a valuable, safe, inexpensive diagnostic technique in case of the coronary artery disease. It is time-consuming and has limited efficiency in patients with poor echocardiographic conditions. The test requires skills and experience of the performing physician.

  10. Laboratory procedures manual for the firefly luciferase assay for adenosine triphosphate (ATP)

    NASA Technical Reports Server (NTRS)

    Chappelle, E. W.; Picciolo, G. L.; Curtis, C. A.; Knust, E. A.; Nibley, D. A.; Vance, R. B.

    1975-01-01

    A manual on the procedures and instruments developed for the adenosine triphosphate (ATP) luciferase assay is presented. Data cover, laboratory maintenance, maintenance of bacterial cultures, bacteria measurement, reagents, luciferase procedures, and determination of microbal susceptibility to antibiotics.

  11. Adenosine: A Mediator of the Sleep-Inducing Effects of Prolonged Wakefulness

    PubMed Central

    Porkka-Heiskanen, Tarja; Strecker, Robert E.; Thakkar, Mahesh; Bjørkum, Alvhild A.; Greene, Robert W.; McCarley, Robert W.

    2013-01-01

    Both subjective and electroencephalographic arousal diminish as a function of the duration of prior wakefulness. Data reported here suggest that the major criteria for a neural sleep factor mediating the somnogenic effects of prolonged wakefulness are satisfied by adenosine, a neuromodulator whose extracellular concentration increases with brain metabolism and which, in vitro, inhibits basal forebrain cholinergic neurons. In vivo microdialysis measurements in freely behaving cats showed that adenosine extracellular concentrations in the basal forebrain cholinergic region increased during spontaneous wakefulness as contrasted with slow wave sleep; exhibited progressive increases during sustained, prolonged wakefulness; and declined slowly during recovery sleep. Furthermore, the sleep-wakefulness profile occurring after prolonged wakefulness was mimicked by increased extracellular adenosine induced by microdialysis perfusion of an adenosine transport inhibitor in the cholinergic basal forebrain but not by perfusion in a control noncholinergic region. PMID:9157887

  12. Passive targeting of ischemic-reperfused myocardium with adenosine-loaded silica nanoparticles

    PubMed Central

    Galagudza, Michael; Korolev, Dmitry; Postnov, Viktor; Naumisheva, Elena; Grigorova, Yulia; Uskov, Ivan; Shlyakhto, Eugene

    2012-01-01

    Pharmacological agents suggested for infarct size limitation have serious side effects when used at cardioprotective doses which hinders their translation into clinical practice. The solution to the problem might be direct delivery of cardioprotective drugs into ischemic-reperfused myocardium. In this study, we explored the potential of silica nanoparticles for passive delivery of adenosine, a prototype cardioprotective agent, into ischemic-reperfused heart tissue. In addition, the biodegradation of silica nanoparticles was studied both in vitro and in vivo. Immobilization of adenosine on the surface of silica nanoparticles resulted in enhancement of adenosine-mediated infarct size limitation in the rat model. Furthermore, the hypotensive effect of adenosine was attenuated after its adsorption on silica nanoparticles. We conclude that silica nanoparticles are biocompatible materials that might potentially be used as carriers for heart-targeted drug delivery. PMID:22619519

  13. Role of CNPase in the oligodendrocytic extracellular 2',3'-cAMP-adenosine pathway.

    PubMed

    Verrier, Jonathan D; Jackson, Travis C; Gillespie, Delbert G; Janesko-Feldman, Keri; Bansal, Rashmi; Goebbels, Sandra; Nave, Klaus-Armin; Kochanek, Patrick M; Jackson, Edwin K

    2013-10-01

    Extracellular adenosine 3',5'-cyclic monophosphate (3',5'-cAMP) is an endogenous source of localized adenosine production in many organs. Recent studies suggest that extracellular 2',3'-cAMP (positional isomer of 3',5'-cAMP) is also a source of adenosine, particularly in the brain in vivo post-injury. Moreover, in vitro studies show that both microglia and astrocytes can convert extracellular 2',3'-cAMP to adenosine. Here, we examined the ability of primary mouse oligodendrocytes and neurons to metabolize extracellular 2',3'-cAMP and their respective adenosine monophosphates (2'-AMP and 3'-AMP). Cells were also isolated from mice deficient in 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNPase). Oligodendrocytes metabolized 2',3'-cAMP to 2'-AMP with 10-fold greater efficiency than did neurons (and also more than previously examined microglia and astrocytes); whereas, the production of 3'-AMP was minimal in both oligodendrocytes and neurons. The production of 2'-AMP from 2',3'-cAMP was reduced by 65% in CNPase -/- versus CNPase +/+ oligodendrocytes. Oligodendrocytes also converted 2'-AMP to adenosine, and this was also attenuated in CNPase -/- oligodendrocytes. Inhibition of classic 3',5'-cAMP-3'-phosphodiesterases with 3-isobutyl-1-methylxanthine did not block metabolism of 2',3'-cAMP to 2'-AMP and inhibition of classic ecto-5'-nucleotidase (CD73) with α,β-methylene-adenosine-5'-diphosphate did not attenuate the conversion of 2'-AMP to adenosine. These studies demonstrate that oligodendrocytes express the extracellular 2',3'-cAMP-adenosine pathway (2',3'-cAMP → 2'-AMP → adenosine). This pathway is more robustly expressed in oligodendrocytes than in all other CNS cell types because CNPase is the predominant enzyme that metabolizes 2',3'-cAMP to 2-AMP in CNS cells. By reducing levels of 2',3'-cAMP (a mitochondrial toxin) and increasing levels of adenosine (a neuroprotectant), oligodendrocytes may protect axons from injury. PMID:23922219

  14. Role of adenosine deaminase, ecto-(5'-nucleotidase) and ecto-(non-specific phosphatase) in cyanide-induced adenosine monophosphate catabolism in rat polymorphonuclear leucocytes.

    PubMed Central

    Newby, A C

    1980-01-01

    1. The role of adenosine deaminase (EC 3.5.4.4), ecto-(5'-nucleotidase) (EC 3.1.3.5) and ecto-(non-specific phosphatase) in the CN-induced catabolism of adenine nucleotides in intact rat polymorphonuclear leucocytes was investigated by inhibiting the enzymes in situ. 2. KCN (10mM for 90 min) induced a 20-30% fall in ATP concentration accompanied by an approximately equimolar increase in hypoxanthine, ADP, AMP and adenosine concentrations were unchanged, and IMP and inosine remained undetectable ( less than 0.05 nmol/10(7) cells). 3. Cells remained 98% intact, as judged by loss of the cytoplasmic enzyme lactate dehydrogenase (EC 1.1.1.27). 4. Pentostatin (30 microM), a specific inhibitor of adenosine deaminase, completely inhibited hypoxanthine production from exogenous adenosine (55 microM), but did not black CN-induced hypoxanthine production or cause adenosine accumulation in intact cells. This implied that IMP rather than adenosine was an intermediate in AMP breakdown in response to cyanide. 5. Antibodies raised against purified plasma-membrane 5'-nucleotidase inhibited the ecto-(5'-nucleotidase) by 95-98%. Non-specific phosphatases were blocked by 10 mM-sodium beta-glycerophosphate. 6. These two agents together blocked hypoxanthine production from exogenous AMP and IMP (200 microM) by more than 90%, but had no effect on production from endogenous substrates. 7. These data suggest that ectophosphatases do not participate in CN-induced catabolism of intracellular AMP in rat polymorphonuclear leucocytes. 8. A minor IMPase, not inhibited by antiserum, was detected in the soluble fraction of disrupted cells. PMID:6249264

  15. Effect of insulin and glucose on adenosine metabolizing enzymes in human B lymphocytes.

    PubMed

    Kocbuch, Katarzyna; Sakowicz-Burkiewicz, Monika; Grden, Marzena; Szutowicz, Andrzej; Pawelczyk, Tadeusz

    2009-01-01

    In diabetes several aspects of immunity are altered, including the immunomodulatory action of adenosine. Our study was undertaken to investigate the effect of different glucose and insulin concentrations on activities of adenosine metabolizing enzymes in human B lymphocytes line SKW 6.4. The activity of adenosine deaminase in the cytosolic fraction was very low and was not affected by different glucose concentration, but in the membrane fraction of cells cultured with 25 mM glucose it was decreased by about 35% comparing to the activity in cells maintained in 5 mM glucose, irrespective of insulin concentration. The activities of 5'-nucleotidase (5'-NT) and ecto-5'-NT in SKW 6.4 cells depended on insulin concentration, but not on glucose. Cells cultured with 10(-8) M insulin displayed an about 60% lower activity of cytosolic 5'-NT comparing to cells maintained at 10(-11) M insulin. The activity of ecto-5'-NT was decreased by about 70% in cells cultured with 10(-8) M insulin comparing to cells grown in 10(-11) M insulin. Neither insulin nor glucose had an effect on adenosine kinase (AK) activity in SKW 6.4 cells or in human B cells isolated from peripheral blood. The extracellular level of adenosine and inosine during accelerated catabolism of cellular ATP depended on glucose, but not on insulin concentration. Concluding, our study demonstrates that glucose and insulin differentially affect the activities of adenosine metabolizing enzymes in human B lymphocytes, but changes in those activities do not correlate with the adenosine level in cell media during accelerated ATP catabolism, implying that nucleoside transport is the primary factor determining the extracellular level of adenosine.

  16. Role of adenosine in the sympathetic activation produced by isometric exercise in humans.

    PubMed Central

    Costa, F; Biaggioni, I

    1994-01-01

    Isometric exercise increases sympathetic nerve activity and blood pressure. This exercise pressor reflex is partly mediated by metabolic products activating muscle afferents (metaboreceptors). Whereas adenosine is a known inhibitory neuromodulator, there is increasing evidence that it activates afferent nerves. We, therefore, examined the hypothesis that adenosine stimulates muscle afferents and participates in the exercise pressor reflex in healthy volunteers. Intraarterial administration of adenosine into the forearm, during venous occlusion to prevent systemic effects, mimicked the response to exercise, increasing muscle sympathetic nerve activity (MSNA, lower limb microneurography) and mean arterial blood pressure (MABP) at all doses studied (2, 3, and 4 mg). Heart rate increased only with the highest dose. Intrabrachial adenosine (4 mg) increased MSNA by 96 +/- 25% (n = 6, P < 0.01) and MABP by 12 +/- 3 mmHg (P < 0.01). Adenosine produced forearm discomfort, but equivalent painful stimuli (forearm ischemia and cold exposure) increased MSNA significantly less than adenosine. Furthermore, adenosine receptor antagonism with intrabrachial theophylline (1 microgram/ml forearm per min) blocked the increase in MSNA (92 +/- 15% vs. 28 +/- 6%, n = 7, P < 0.01) and MABP (38 +/- 6 vs. 27 +/- 4 mmHg, P = 0.01) produced by isometric handgrip (30% of maximal voluntary contraction) in the infused arm, but not the contralateral arm. Theophylline did not prevent the increase in heart rate produced by handgrip, a response mediated more by central command than muscle afferent activation. We propose that endogenous adenosine contributes to the activation of muscle afferents involved in the exercise pressor reflex in humans. PMID:8163667

  17. Cyclization of the phosphate side chain of adenosine triphosphate: formation of monoadenosine 5'-trimetaphosphate.

    PubMed

    Glonek, T; Kleps, R A; Myers, T C

    1974-07-26

    Monoadenosine 5'-trimetaphosphate has been prepared from adeno-sine 5'-triphosphate by a carbodiimide-mediated condensation. The molecule was characterized by (3l)P nuclear magnetic resonance, and its (31)P spectrum was simulated through the assumption of a three-phosphorus spin system. The molecule is highly reactive and is rapidly converted to adenosine triphosphate upon contact with water. PMID:4834364

  18. Adverse and Protective Influences of Adenosine on the Newborn and Embryo: Implications for Preterm White Matter Injury and Embryo Protection

    PubMed Central

    Rivkees, Scott A.; Wendler, Christopher C.

    2011-01-01

    Few signaling molecules have the potential to influence the developing mammal as the nucleoside adenosine. Adenosine levels increase rapidly with tissue hypoxia and inflammation. Adenosine antagonists include the methlyxanthines caffeine and theophylline. The receptors that transduce adenosine action are the A1, A2a, A2b, and A3 adenosine receptors (ARs). In the postnatal period, A1AR activation may contribute to white matter injury in the preterm infant by altering oligodendrocyte (OL) development. In models of perinatal brain injury, caffeine is neuroprotective against periventricular white matter injury (PWMI) and hypoxic-ischemic encephalopathy (HIE). Supporting the notion that blockade of adenosine action is of benefit in the premature infant, caffeine reduces the incidence of broncho-pulmonary dysplasia and cerebral palsy in clinical studies. In comparison with the adverse effects on the postnatal brain, adenosine acts via A1ARs to play an essential role in protecting the embryo from hypoxia. Embryo protective effects are blocked by caffeine, and caffeine intake during early pregnancy increases the risk of miscarriage and fetal growth retardation. Adenosine and adenosine antagonists play important modulatory roles during mammalian development. The protective and deleterious effects of adenosine depend on the time of exposure and target sites of action. PMID:21228731

  19. Ticagrelor Does Not Inhibit Adenosine Transport at Relevant Concentrations: A Randomized Cross-Over Study in Healthy Subjects In Vivo

    PubMed Central

    Rongen, G. A.; van den Broek, P. H. H.; Bilos, A.; Donders, A. R. T.; Gomes, M. E.; Riksen, N. P.

    2015-01-01

    Background and Purpose In patients with myocardial infarction, ticagrelor reduces cardiovascular and sepsis-related mortality, and can cause dyspnea. It is suggested that this is caused by adenosine receptor stimulation, because in preclinical studies, ticagrelor blocks the nucleoside transporter and increases cellular ATP release. We now investigated the effects of ticagrelor on the adenosine system in humans in vivo. Experimental Approach In a double-blinded, placebo-controlled cross-over trial in 14 healthy subjects, we have tested whether ticagrelor (180 mg) affects adenosine- and dipyridamole-induced forearm vasodilation, as surrogates of nucleoside uptake inhibition and adenosine formation, respectively. Also, ex vivo uptake of adenosine and uridine in isolated red blood cells was measured. Primary endpoint was adenosine-induced vasodilation. Key Results Ticagrelor did not affect adenosine- or dipyridamole-induced forearm vasodilation. Also, ex vivo uptake of adenosine and uridine in isolated red blood cells was not affected by ticagrelor. In vitro, ticagrelor dose-dependently inhibited nucleoside uptake, but only at supra-physiological concentrations. Conclusion and Implications In conclusion, at relevant plasma concentration, ticagrelor does not affect adenosine transport, nor adenosine formation in healthy subjects. Therefore, it is unlikely that this mechanism is a relevant pleiotropic effect of ticagrelor. Trial Registration ClinicalTrials.gov NCT01996735 PMID:26509673

  20. Design, Synthesis and Evaluation of Fe-S Targeted Adenosine 5′-Phosphosulfate Reductase Inhibitors

    PubMed Central

    Paritala, Hanumantharao; Suzuki, Yuta; Carroll, Kate S.

    2015-01-01

    Adenosine 5′-phosphosulfate reductase (APR) is an iron-sulfur enzyme that is vital for survival of Mycobacterium tuberculosis during dormancy and is an attractive target for the treatment of latent tuberculosis (TB) infection. The 4Fe-4S cluster is coordinated to APR by sulfur atoms of four cysteine residues, is proximal to substrate, adenosine 5′-phopsphosulfate (APS), and is essential for catalytic activity. Herein, we present an approach for the development of a new class of APR inhibitors. As an initial step, we have employed an improved solid-phase chemistry method to prepare a series of N6-substituted adenosine analogues and their 5′-phosphates as well as adenosine 5′-phosphate diesters bearing different Fe and S binding groups, such as thiols or carboxylic and hydroxamic acid moieties. Evaluation of the resulting compounds indicates a clearly defined spacing requirement between the Fe-S targeting group and adenosine scaffold and that smaller Fe-S targeting groups are better tolerated. Molecular docking analysis suggests that the S atom of the most potent inhibitor may establish a favorable interaction with an S atom in the cluster. In summary, this study showcases an improved solid-phase method that expedites the preparation of adenosine and related 5′-phosphate derivatives and presents a unique Fe-S targeting strategy for the development of APR inhibitors. PMID:25710356

  1. Striatal adenosine signaling regulates EAAT2 and astrocytic AQP4 expression and alcohol drinking in mice.

    PubMed

    Lee, Moonnoh R; Ruby, Christina L; Hinton, David J; Choi, Sun; Adams, Chelsea A; Young Kang, Na; Choi, Doo-Sup

    2013-02-01

    Adenosine signaling is implicated in several neuropsychiatric disorders, including alcoholism. Among its diverse functions in the brain, adenosine regulates glutamate release and has an essential role in ethanol sensitivity and preference. However, the molecular mechanisms underlying adenosine-mediated glutamate signaling in neuroglial interaction remain elusive. We have previously shown that mice lacking the ethanol-sensitive adenosine transporter, type 1 equilibrative nucleoside transporter (ENT1), drink more ethanol compared with wild-type mice and have elevated striatal glutamate levels. In addition, ENT1 inhibition or knockdown reduces glutamate transporter expression in cultured astrocytes. Here, we examined how adenosine signaling in astrocytes contributes to ethanol drinking. Inhibition or deletion of ENT1 reduced the expression of type 2 excitatory amino-acid transporter (EAAT2) and the astrocyte-specific water channel, aquaporin 4 (AQP4). EAAT2 and AQP4 colocalization was also reduced in the striatum of ENT1 null mice. Ceftriaxone, an antibiotic compound known to increase EAAT2 expression and function, elevated not only EAAT2 but also AQP4 expression in the striatum. Furthermore, ceftriaxone reduced ethanol drinking, suggesting that ENT1-mediated downregulation of EAAT2 and AQP4 expression contributes to excessive ethanol consumption in our mouse model. Overall, our findings indicate that adenosine signaling regulates EAAT2 and astrocytic AQP4 expressions, which control ethanol drinking in mice.

  2. Label-Free Sensing of Adenosine Based on Force Variations Induced by Molecular Recognition

    PubMed Central

    Li, Jingfeng; Li, Qing; Colombi Ciacchi, Lucio; Wei, Gang

    2015-01-01

    We demonstrate a simple force-based label-free strategy for the highly sensitive sensing of adenosine. An adenosine ssDNA aptamer was bound onto an atomic force microscopy (AFM) probe by covalent modification, and the molecular-interface adsorption force between the aptamer and a flat graphite surface was measured by single-molecule force spectroscopy (SMFS). In the presence of adenosine, the molecular recognition between adenosine and the aptamer resulted in the formation of a folded, hairpin-like DNA structure and hence caused a variation of the adsorption force at the graphite/water interface. The sensitive force response to molecular recognition provided an adenosine detection limit in the range of 0.1 to 1 nM. The addition of guanosine, cytidine, and uridine had no significant interference with the sensing of adenosine, indicating a strong selectivity of this sensor architecture. In addition, operational parameters that may affect the sensor, such as loading rate and solution ionic strength, were investigated. PMID:25808841

  3. A2B Adenosine Receptor–Mediated Induction of IL-6 Promotes CKD

    PubMed Central

    Dai, Yingbo; Zhang, Weiru; Wen, Jiaming; Zhang, Yujin; Kellems, Rodney E.

    2011-01-01

    Chronic elevation of adenosine, which occurs in the setting of repeated or prolonged tissue injury, can exacerbate cellular dysfunction, suggesting that it may contribute to the pathogenesis of CKD. Here, mice with chronically elevated levels of adenosine, resulting from a deficiency in adenosine deaminase (ADA), developed renal dysfunction and fibrosis. Both the administration of polyethylene glycol–modified ADA to reduce adenosine levels and the inhibition of the A2B adenosine receptor (A2BR) attenuated renal fibrosis and dysfunction. Furthermore, activation of A2BR promoted renal fibrosis in both mice infused with angiotensin II (Ang II) and mice subjected to unilateral ureteral obstruction (UUO). These three mouse models shared a similar profile of profibrotic gene expression in kidney tissue, suggesting that they share similar signaling pathways that lead to renal fibrosis. Finally, both genetic and pharmacologic approaches showed that the inflammatory cytokine IL-6 mediates adenosine-induced renal fibrosis downstream of A2BR. Taken together, these data suggest that A2BR-mediated induction of IL-6 contributes to renal fibrogenesis and shows potential therapeutic targets for CKD. PMID:21511827

  4. Label-free sensing of adenosine based on force variations induced by molecular recognition.

    PubMed

    Li, Jingfeng; Li, Qing; Ciacchi, Lucio Colombi; Wei, Gang

    2015-03-01

    We demonstrate a simple force-based label-free strategy for the highly sensitive sensing of adenosine. An adenosine ssDNA aptamer was bound onto an atomic force microscopy (AFM) probe by covalent modification, and the molecular-interface adsorption force between the aptamer and a flat graphite surface was measured by single-molecule force spectroscopy (SMFS). In the presence of adenosine, the molecular recognition between adenosine and the aptamer resulted in the formation of a folded, hairpin-like DNA structure and hence caused a variation of the adsorption force at the graphite/water interface. The sensitive force response to molecular recognition provided an adenosine detection limit in the range of 0.1 to 1 nM. The addition of guanosine, cytidine, and uridine had no significant interference with the sensing of adenosine, indicating a strong selectivity of this sensor architecture. In addition, operational parameters that may affect the sensor, such as loading rate and solution ionic strength, were investigated.

  5. Ethanol-induced increase in portal blood glow: Role of adenosine

    SciTech Connect

    Orrego, H.; Carmichael, F.J.; Saldivia, V.; Giles, H.G.; Sandrin, S.; Israel, Y. )

    1988-04-01

    The mechanism by which ethanol induces an increase in portal vein blood flow was studied in rats using radiolabeled microspheres. Ethanol by gavage resulted in an increase of 50-70% in portal vein blood flow. The ethanol-induced increase in portal blood flow was suppressed by the adenosine receptor blocker 8-phenyltheophylline. By itself, 8-phenyltheophylline was without effect on cardiac output or portal blood flow. Adenosine infusion resulted in a dose-dependent increase in portal blood flow. This adenosine-induced increase in portal blood flow was inhibited by 8-phenyltheophylline in a dose-dependent manner. Both alcohol and adenosine significantly reduced preportal vascular resistance by 40% and 60%, respectively. These effects were fully suppressed by 8-phenyltheophylline. It is concluded that adenosine is a likely candidate to mediate the ethanol-induced increase in portal vein blood flow. It is suggested that an increase in circulating acetate and liver hypoxia may mediate the effects of alcohol by increasing tissue and interstitial adenosine levels.

  6. Adenosine Deaminase Deficiency – More Than Just an Immunodeficiency

    PubMed Central

    Whitmore, Kathryn V.; Gaspar, Hubert B.

    2016-01-01

    Adenosine deaminase (ADA) deficiency is best known as a form of severe combined immunodeficiency (SCID) that results from mutations in the gene encoding ADA. Affected patients present with clinical and immunological manifestations typical of a SCID. Therapies are currently available that can target these immunological disturbances and treated patients show varying degrees of clinical improvement. However, there is now a growing body of evidence that deficiency of ADA has significant impact on non-immunological organ systems. This review will outline the impact of ADA deficiency on various organ systems, starting with the well-understood immunological abnormalities. We will discuss possible pathogenic mechanisms and also highlight ways in which current treatments could be improved. In doing so, we aim to present ADA deficiency as more than an immunodeficiency and suggest that it should be recognized as a systemic metabolic disorder that affects multiple organ systems. Only by fully understanding ADA deficiency and its manifestations in all organ systems can we aim to deliver therapies that will correct all the clinical consequences. PMID:27579027

  7. Development of Potent Adenosine Monophosphate Activated Protein Kinase (AMPK) Activators.

    PubMed

    Dokla, Eman M E; Fang, Chun-Sheng; Lai, Po-Ting; Kulp, Samuel K; Serya, Rabah A T; Ismail, Nasser S M; Abouzid, Khaled A M; Chen, Ching-Shih

    2015-11-01

    Previously, we reported the identification of a thiazolidinedione-based adenosine monophosphate activated protein kinase (AMPK) activator, compound 1 (N-[4-({3-[(1-methylcyclohexyl)methyl]-2,4-dioxothiazolidin-5-ylidene}methyl)phenyl]-4-nitro-3-(trifluoromethyl)benzenesulfonamide), which provided a proof of concept to delineate the intricate role of AMPK in regulating oncogenic signaling pathways associated with cell proliferation and epithelial-mesenchymal transition (EMT) in cancer cells. In this study, we used 1 as a scaffold to conduct lead optimization, which generated a series of derivatives. Analysis of the antiproliferative and AMPK-activating activities of individual derivatives revealed a distinct structure-activity relationship and identified 59 (N-(3-nitrophenyl)-N'-{4-[(3-{[3,5-bis(trifluoromethyl)phenyl]methyl}-2,4-dioxothiazolidin-5-ylidene)methyl]phenyl}urea) as the optimal agent. Relative to 1, compound 59 exhibits multifold higher potency in upregulating AMPK phosphorylation in various cell lines irrespective of their liver kinase B1 (LKB1) functional status, accompanied by parallel changes in the phosphorylation/expression levels of p70S6K, Akt, Foxo3a, and EMT-associated markers. Consistent with its predicted activity against tumors with activated Akt status, orally administered 59 was efficacious in suppressing the growth of phosphatase and tensin homologue (PTEN)-null PC-3 xenograft tumors in nude mice. Together, these findings suggest that 59 has clinical value in therapeutic strategies for PTEN-negative cancer and warrants continued investigation in this regard.

  8. Adenosine, type 1 receptors: role in proximal tubule Na+ reabsorption

    PubMed Central

    Welch, William J

    2015-01-01

    Adenosine type 1 receptor (A1-AR) antagonists induce diuresis and natriuresis in experimental animals and humans. Much of this effect is due to inhibition of A1-ARs in the proximal tubule, which is responsible for 60–70% of the reabsorption of filtered Na+ and fluid. Intratubular application of receptor antagonists indicates that A1-AR mediates a portion of Na+ uptake in PT and PT cells, via multiple transport systems, including Na+/H+ exchanger-3 (NHE3), Na+/PO4− co-transporter and Na+-dependent glucose transporter, SGLT. Renal microperfusion and recollection studies have shown that fluid reabsorption is reduced by A1-AR antagonists and is lower in A1-AR KO mice., compared to WT mice. Absolute proximal reabsorption (APR) measured by free-flow micropuncture is equivocal, with studies that show either lower APR or similar APR in A1-AR KO mice, compared to WT mice. Inhibition of A1-ARs lowers elevated blood pressure in models of salt-sensitive hypertension, partially due to their effects in the proximal tubule. PMID:25345761

  9. Adenosine Deaminase Activity in Chronic Lymphocytic Leukemia and Healthy Subjects

    PubMed Central

    Ghaderi, Bayazid; Amini, Sabrieh; Maroofi, Farzad; Jalali, Chiya; Javanmardi, Mitra; Roshani, Daem; Abdi, Mohammad

    2016-01-01

    Background B cell chronic lymphocytic leukemia is one of the most frequent hematologic malignancies in the world. Cellular surface CD markers and serum Beta-2-microglobulin may be used as a prognostic tool in CLL patients. Objectives In the present study we introduce serum adenosine deaminase as a diagnostic marker in CLL. Materials and Methods Blood samples were collected from B-CLL and healthy subjects. White blood cell, red blood cell and platelet count and blood Erythrocyte sedimentation rate was recorded and serum Beta-2-microglobulin, Lactate dehydrogenase and total ADA enzyme activity were determined. Results Serum ADA activity was significantly higher in patients group than that of controls. ADA had a significant and direct correlation with B2M, WBC, LDH and ESR. However, there was not any relation between ADA and the stages of disease. Diagnostic cut-off, sensitivity and specificity of the serum ADA test were 27.97 U/L, 91% and 94%, respectively. Conclusions A higher ADA activity in patients group and its correlation with CLL markers were seen in our study. High diagnostic value of serum ADA in our study suggests that it might be considered as a useful screening tool among the other markers in CLL. PMID:27703646

  10. Intracellular Adenosine Triphosphate Delivery Enhanced Skin Wound Healing in Rabbits

    PubMed Central

    Wang, Jianpu; Zhang, Qunwei; Wan, Rong; Mo, Yiqun; Li, Ming; Tseng, Michael T.; Chien, Sufan

    2016-01-01

    Small unilamellar lipid vesicles were used to encapsulate adenosine triphosphate (ATP-vesicles) for intracellular energy delivery. This technique was tested in full-thickness skin wounds in 16 adult rabbits. One ear was rendered ischemic by using a minimally invasive surgery. The other ear served as a normal control. Four circular full-thickness wounds were created on the ventral side of each ear. ATP-vesicles or saline was used and the wounds were covered with Tegaderm (3M, St. Paul, MN). Dressing was changed and digital photos were taken daily until all the wounds were healed. The mean healing times of ATP-vesicles–treated wounds were significantly shorter than that of saline-treated wounds on ischemic and nonischemic ears. Histologic study indicated better-developed granular tissue and reepithelial-ization in the ATP-vesicles–treated wounds. The wounds treated by ATP-vesicles exhibited extremely fast granular tissue growth. More CD31 positive cells were seen in the ATP-vesicles–treated wounds. This preliminary study shows that direct intracellular delivery of ATP can accelerate the healing process of skin wounds on ischemic and nonischemic rabbit ears. The extremely fast granular tissue growth was something never seen or reported in the past. PMID:19158531

  11. ADA (adenosine deaminase) gene therapy enters the competition

    SciTech Connect

    Culliton, B.J.

    1990-08-31

    Around the world, some 70 children are members of a select and deadly club. Born with an immune deficiency so severe that they will die of infection unless their immune systems can be repaired, they have captured the attention of would-be gene therapists who believe that a handful of these kids--the 15 or 20 who lack functioning levels of the enzyme adenosine deaminase (ADA)--could be saved by a healthy ADA gene. A team of gene therapists is ready to put the theory to the test. In April 1987, a team of NIH researchers headed by R. Michael Blaese and W. French Anderson came up with the first formal protocol to introduce a healthy ADA gene into an unhealthy human. After 3 years of line-by-line scrutiny by five review committees, they have permission to go ahead. Two or three children will be treated in the next year, and will be infused with T lymphocytes carrying the gene for ADA. If the experiment works, the ADA gene will begin producing normal amounts of ADA. An interesting feature of ADA deficiency, that makes it ideal for initial gene studies, is that the amount of ADA one needs for a healthy immune system is quite variable. Hence, once inside a patient's T cells, the new ADA gene needs only to express the enzyme in moderate amounts. No precise gene regulation is necessary.

  12. Detection of bacteriuria by luciferase assay of adenosine triphosphate.

    PubMed Central

    Thore, A; Anséhn, S; Lundin, A; Bergman, S

    1975-01-01

    A selective method for distinguishing bacterial and nonbacterial adenosine triphosphate (ATP) in clinical bacteriological specimens was studied. The method involved incubation of samples with the detergent Triton X-100 and the ATP-hydrolyzing enzyme apyrase. The incubation selectively destroyed ATP in suspensions of various human cells while not affecting the ATP content in microbial cells. ATP remaining in the sample after incubation was extracted in boiling buffer and assayed by the firefly luciferase assay. Application of the method to 469 clinical urine specimens showed that the ATP level after treatment with Triton/apyrase was correlated to bacterial counts and that the sensitivity of the assay was sufficient for the detection of 10(5) bacteria/ml. The ATP levels per bacterial cell remaining in the urine specimen after treatment with Triton/apyrase were close to values observed in laboratory-grown cultures. The specificity and sensitivity of the luciferase assay for the detection of urinary bacteria and its possible use as a bacteriuria screening method are discussed. PMID:1100645

  13. Sequence specificity of mRNA N6-adenosine methyltransferase.

    PubMed

    Csepany, T; Lin, A; Baldick, C J; Beemon, K

    1990-11-25

    The sequence specificity of chicken mRNA N6-adenosine methyltransferase has been investigated in vivo. Localization of six new N6-methyladenosine sites on Rous sarcoma virus (RSV) virion RNA has confirmed our extended consensus sequence for methylation: RGACU, where R is usually a G (7/12). We have also observed A (2/12) and U (3/12) at the -2 position (relative to m6A at +1) but never a C. At the +3 position, the U was observed 10/12 times; an A and a C were observed once each in weakly methylated sequences. The extent of methylation varied between the different sites up to a maximum of about 90%. To test the significance of this consensus sequence, it was altered by site-specific mutagenesis, and methylation was assayed after transfection of mutated RSV DNA into chicken embryo fibroblasts. We found that changing the G at -1 or the U at +3 to any other residue inhibited methylation. However, inhibition of methylation at all four of the major sites in the RSV src gene did not detectably alter the steady-state levels of the three viral RNA species or viral infectivity. Additional mutants that inactivated the src protein kinase activity produced less virus and exhibited relatively less src mRNA in infected cells. PMID:2173695

  14. Adenosine Deaminase Deficiency - More Than Just an Immunodeficiency.

    PubMed

    Whitmore, Kathryn V; Gaspar, Hubert B

    2016-01-01

    Adenosine deaminase (ADA) deficiency is best known as a form of severe combined immunodeficiency (SCID) that results from mutations in the gene encoding ADA. Affected patients present with clinical and immunological manifestations typical of a SCID. Therapies are currently available that can target these immunological disturbances and treated patients show varying degrees of clinical improvement. However, there is now a growing body of evidence that deficiency of ADA has significant impact on non-immunological organ systems. This review will outline the impact of ADA deficiency on various organ systems, starting with the well-understood immunological abnormalities. We will discuss possible pathogenic mechanisms and also highlight ways in which current treatments could be improved. In doing so, we aim to present ADA deficiency as more than an immunodeficiency and suggest that it should be recognized as a systemic metabolic disorder that affects multiple organ systems. Only by fully understanding ADA deficiency and its manifestations in all organ systems can we aim to deliver therapies that will correct all the clinical consequences. PMID:27579027

  15. Development of Novel Adenosine Monophosphate-Activated Protein Kinase Activators

    PubMed Central

    Guh, Jih-Hwa; Chang, Wei-Ling; Yang, Jian; Lee, Su-Lin; Wei, Shuo; Wang, Dasheng; Kulp, Samuel K.; Chen, Ching-Shih

    2010-01-01

    In light of the unique ability of thiazolidinediones to mediate peroxisome proliferator-activated receptor (PPAR)γ-independent activation of adenosine monophosphate-activated protein kinase (AMPK) and suppression of interleukin (IL)-6 production, we conducted a screening of an in-house, thiazolidinedione-based focused compound library to identify novel agents with these dual pharmacological activities. Cell-based assays pertinent to the activation status of AMPK and mammalian homolog of target of rapamycin (i.e., phosphorylation of AMPK and p70 ribosomal protein S6 kinase, respectively), and IL-6/IL-6 receptor signaling (i.e., IL-6 production and signal transducer and activator of transcription 3 phosphorylation, respectively) in lipopolysaccharide (LPS)-stimulated THP-1 human macrophages were used to screen this compound library, which led to the identification of compound 53 (N-{4-[3-(1-Methylcyclohexylmethyl)-2,4-dioxo-thiazolidin-5-ylidene-methyl]-phenyl}-4-nitro-3-trifluoromethyl-benzenesulfonamide) as the lead agent. Evidence indicates that this drug-induced suppression of LPS-stimulated IL-6 production was attributable to AMPK activation. Furthermore, compound 53-mediated AMPK activation was demonstrated in C-26 colon adenocarcinoma cells, indicating that it is not a cell line-specific event. PMID:20170185

  16. An adenosine nucleoside analogue NITD008 inhibits EV71 proliferation.

    PubMed

    Shang, Luqing; Wang, Yaxin; Qing, Jie; Shu, Bo; Cao, Lin; Lou, Zhiyong; Gong, Peng; Sun, Yuna; Yin, Zheng

    2014-12-01

    Enterovirus 71 (EV71), one of the major causative agents of Hand-Foot-Mouth Disease (HFMD), causes severe pandemics and hundreds of deaths in the Asia-Pacific region annually and is an enormous public health threat. However, effective therapeutic antiviral drugs against EV71 are rare. Nucleoside analogues have been successfully used in the clinic for the treatment of various viral infections. We evaluated a total of 27 nucleoside analogues and discovered that an adenosine nucleoside analogue NITD008, which has been reported to be an antiviral reagent that specifically inhibits flaviviruses, effectively suppressed the propagation of different strains of EV71 in RD, 293T and Vero cells with a relatively high selectivity index. Triphosphorylated NITD008 (ppp-NITD008) functions as a chain terminator to directly inhibit the RNA-dependent RNA polymerase activity of EV71, and it does not affect the EV71 VPg uridylylation process. A significant synergistic anti-EV71 effect of NITD008 with rupintrivir (AG7088) (a protease inhibitor) was documented, supporting the potential combination therapy of NITD008 with other inhibitors for the treatment of EV71 infections.

  17. Biophysical Mapping of the Adenosine A2A Receptor

    PubMed Central

    2011-01-01

    A new approach to generating information on ligand receptor interactions within the binding pocket of G protein-coupled receptors has been developed, called Biophysical Mapping (BPM). Starting from a stabilized receptor (StaR), minimally engineered for thermostability, additional single mutations are then added at positions that could be involved in small molecule interactions. The StaR and a panel of binding site mutants are captured onto Biacore chips to enable characterization of the binding of small molecule ligands using surface plasmon resonance (SPR) measurement. A matrix of binding data for a set of ligands versus each active site mutation is then generated, providing specific affinity and kinetic information (KD, kon, and koff) of receptor–ligand interactions. This data set, in combination with molecular modeling and docking, is used to map the small molecule binding site for each class of compounds. Taken together, the many constraints provided by these data identify key protein–ligand interactions and allow the shape of the site to be refined to produce a high quality three-dimensional picture of ligand binding, thereby facilitating structure based drug design. Results of biophysical mapping of the adenosine A2A receptor are presented. PMID:21661720

  18. Geometry and cooperativity effects in adenosine-carboxylic acid complexes.

    PubMed

    Schlund, Sebastian; Mladenovic, Milena; Basílio Janke, Eline M; Engels, Bernd; Weisz, Klaus

    2005-11-23

    NMR experiments and theoretical investigations were performed on hydrogen bonded complexes of specifically 1- and 7-15N-labeled adenine nucleosides with carboxylic acids. By employing a freonic solvent of CDClF2 and CDF3, NMR spectra were acquired at temperatures as low as 123 K, where the regime of slow hydrogen bond exchange is reached and several higher-order complexes were found to coexist in solution. Unlike acetic acid, chloroacetic acid forms Watson-Crick complexes with the proton largely displaced from oxygen to the nitrogen acceptor in an ion pairing structure. Calculated geometries and chemical shifts of the proton in the hydrogen bridge favorably agree with experimentally determined values if vibrational averaging and solvent effects are taken into account. The results indicate that binding a second acidic ligand at the adenine Hoogsteen site in a ternary complex weakens the hydrogen bond to the Watson-Crick bound carboxylic acid. However, substituting a second adenine nucleobase for a carboxylic acid in the trimolecular complex leads to cooperative binding at Watson-Crick and Hoogsteen faces of adenosine.

  19. Adenosine Deaminase Inhibition Prevents Clostridium difficile Toxin A-Induced Enteritis in Mice ▿

    PubMed Central

    de Araújo Junqueira, Ana Flávia Torquato; Dias, Adriana Abalen Martins; Vale, Mariana Lima; Spilborghs, Graziela Machado Gruner Turco; Bossa, Aline Siqueira; Lima, Bruno Bezerra; Carvalho, Alex Fiorini; Guerrant, Richard Littleton; Ribeiro, Ronaldo Albuquerque; Brito, Gerly Anne

    2011-01-01

    Toxin A (TxA) is able to induce most of the classical features of Clostridium difficile-associated disease in animal models. The objective of this study was to determine the effect of an inhibitor of adenosine deaminase, EHNA [erythro-9-(2-hydroxy-3-nonyl)-adenine], on TxA-induced enteritis in C57BL6 mice and on the gene expression of adenosine receptors. EHNA (90 μmol/kg) or phosphate-buffered saline (PBS) was injected intraperitoneally (i.p.) 30 min prior to TxA (50 μg) or PBS injection into the ileal loop. A2A adenosine receptor agonist (ATL313; 5 nM) was injected in the ileal loop immediately before TxA (50 μg) in mice pretreated with EHNA. The animals were euthanized 3 h later. The changes in the tissue were assessed by the evaluation of ileal loop weight/length and secretion volume/length ratios, histological analysis, myeloperoxidase assay (MPO), the local expression of inducible nitric oxide synthase (NOS2), pentraxin 3 (PTX3), NF-κB, tumor necrosis factor alpha (TNF-α), and interleukin-1β (IL-1β) by immunohistochemistry and/or quantitative reverse transcription-PCR (qRT-PCR). The gene expression profiles of A1, A2A, A2B, and A3 adenosine receptors also were evaluated by qRT-PCR. Adenosine deaminase inhibition, by EHNA, reduced tissue injury, neutrophil infiltration, and the levels of proinflammatory cytokines (TNF-α and IL-1β) as well as the expression of NOS2, NF-κB, and PTX3 in the ileum of mice injected with TxA. ATL313 had no additional effect on EHNA action. TxA increased the gene expression of A1 and A2A adenosine receptors. Our findings show that the inhibition of adenosine deaminase by EHNA can prevent Clostridium difficile TxA-induced damage and inflammation possibly through the A2A adenosine receptor, suggesting that the modulation of adenosine/adenosine deaminase represents an important tool in the management of C. difficile-induced disease. PMID:21115723

  20. Adenosine deaminase inhibition prevents Clostridium difficile toxin A-induced enteritis in mice.

    PubMed

    de Araújo Junqueira, Ana Flávia Torquato; Dias, Adriana Abalen Martins; Vale, Mariana Lima; Spilborghs, Graziela Machado Gruner Turco; Bossa, Aline Siqueira; Lima, Bruno Bezerra; Carvalho, Alex Fiorini; Guerrant, Richard Littleton; Ribeiro, Ronaldo Albuquerque; Brito, Gerly Anne

    2011-02-01

    Toxin A (TxA) is able to induce most of the classical features of Clostridium difficile-associated disease in animal models. The objective of this study was to determine the effect of an inhibitor of adenosine deaminase, EHNA [erythro-9-(2-hydroxy-3-nonyl)-adenine], on TxA-induced enteritis in C57BL6 mice and on the gene expression of adenosine receptors. EHNA (90 μmol/kg) or phosphate-buffered saline (PBS) was injected intraperitoneally (i.p.) 30 min prior to TxA (50 μg) or PBS injection into the ileal loop. A(2A) adenosine receptor agonist (ATL313; 5 nM) was injected in the ileal loop immediately before TxA (50 μg) in mice pretreated with EHNA. The animals were euthanized 3 h later. The changes in the tissue were assessed by the evaluation of ileal loop weight/length and secretion volume/length ratios, histological analysis, myeloperoxidase assay (MPO), the local expression of inducible nitric oxide synthase (NOS2), pentraxin 3 (PTX3), NF-κB, tumor necrosis factor alpha (TNF-α), and interleukin-1β (IL-1β) by immunohistochemistry and/or quantitative reverse transcription-PCR (qRT-PCR). The gene expression profiles of A₁, A(2A), A(2B), and A₃ adenosine receptors also were evaluated by qRT-PCR. Adenosine deaminase inhibition, by EHNA, reduced tissue injury, neutrophil infiltration, and the levels of proinflammatory cytokines (TNF-α and IL-1β) as well as the expression of NOS2, NF-κB, and PTX3 in the ileum of mice injected with TxA. ATL313 had no additional effect on EHNA action. TxA increased the gene expression of A₁ and A(2A) adenosine receptors. Our findings show that the inhibition of adenosine deaminase by EHNA can prevent Clostridium difficile TxA-induced damage and inflammation possibly through the A(2A) adenosine receptor, suggesting that the modulation of adenosine/adenosine deaminase represents an important tool in the management of C. difficile-induced disease.

  1. Comonitoring of adenosine and dopamine using the Wireless Instantaneous Neurotransmitter Concentration System: proof of principle

    PubMed Central

    Shon, Young-Min; Chang, Su-Youne; Tye, Susannah J.; Kimble, Christopher J.; Bennet, Kevin E.; Blaha, Charles D.; Lee, Kendall H.

    2010-01-01

    Object The authors of previous studies have demonstrated that local adenosine efflux may contribute to the therapeutic mechanism of action of thalamic deep brain stimulation (DBS) for essential tremor. Real-time monitoring of the neurochemical output of DBS-targeted regions may thus advance functional neurosurgical procedures by identifying candidate neurotransmitters and neuromodulators involved in the physiological effects of DBS. This would in turn permit the development of a method of chemically guided placement of DBS electrodes in vivo. Designed in compliance with FDA-recognized standards for medical electrical device safety, the authors report on the utility of the Wireless Instantaneous Neurotransmitter Concentration System (WINCS) for real-time comonitoring of electrical stimulation–evoked adenosine and dopamine efflux in vivo, utilizing fast-scan cyclic voltammetry (FSCV) at a polyacrylonitrile-based (T-650) carbon fiber microelectrode (CFM). Methods The WINCS was used for FSCV, which consisted of a triangle wave scanned between −0.4 and +1.5 V at a rate of 400 V/second and applied at 10 Hz. All voltages applied to the CFM were with respect to an Ag/AgCl reference electrode. The CFM was constructed by aspirating a single T-650 carbon fiber (r = 2.5 μm) into a glass capillary and pulling to a microscopic tip using a pipette puller. The exposed carbon fiber (the sensing region) extended beyond the glass insulation by ∼ 50 μm. Proof of principle tests included in vitro measurements of adenosine and dopamine, as well as in vivo measurements in urethane-anesthetized rats by monitoring adenosine and dopamine efflux in the dorsomedial caudate putamen evoked by high-frequency electrical stimulation of the ventral tegmental area and substantia nigra. Results The WINCS provided reliable, high-fidelity measurements of adenosine efflux. Peak oxidative currents appeared at +1.5 V and at +1.0 V for adenosine, separate from the peak oxidative current at +0.6 V

  2. Respiratory arrest during dipyridamole stress testing.

    PubMed Central

    Hillis, G. S.; al-Mohammad, A.; Jennings, K. P.

    1997-01-01

    There is an increasing usage of radionuclide scanning to assess myocardial perfusion, with dipyridamole, the most commonly used stress agent. Although this is an effective, and usually very safe, means by which to assess myocardial blood supply, there have been several incidents of acute bronchospasm in asthmatic patients. There have, however, been no previous reports of respiratory arrest occurring in patients with emphysema. This case illustrates the dangers of administering intravenous dipyridamole, or even adenosine, to patients with chronic lung disease. PMID:9196707

  3. Stress echocardiography

    MedlinePlus

    Echocardiography stress test; Stress test - echocardiography; CAD - stress echocardiography; Coronary artery disease - stress echocardiography; Chest pain - stress echocardiography; Angina - stress echocardiography; ...

  4. On the role, inactivation and origin of endogenous adenosine at the frog neuromuscular junction.

    PubMed Central

    Ribeiro, J A; Sebastião, A M

    1987-01-01

    1. The effects of adenosine deaminase, inosine, alkylxanthines (8-phenyltheophylline (8-PT), theophylline and isobutylmethylxanthine (IBMX], dipyridamole, alpha, beta-methylene ADP (AOPCP) and ATP analogues (alpha, beta-methylene ATP and beta, gamma-methylene ATP) on evoked end-plate potentials (e.p.p.s) were investigated in innervated sartorius muscles of the frog, in which twitches had been prevented with tubocurarine. The effects of 8-PT and IBMX on the amplitude and quantal content of e.p.p.s were also investigated in innervated sartorius muscles of the frog, in which twitches had been prevented with high-magnesium solutions. 2. Adenosine deaminase reversibly increased the amplitude of e.p.p.s and prevented the reduction caused by exogenously applied adenosine on e.p.p. amplitude. The increase caused by adenosine deaminase was equivalent to the decrease caused by 12 +/- 5.8 microM-adenosine on e.p.p. amplitude. 3. Inosine, the product of adenosine deamination, was virtually devoid of effect on e.p.p.s. 4. The adenosine receptor antagonists at the frog neuromuscular junction, 8-PT and theophylline, increased in a concentration-dependent manner the amplitude of e.p.p.s in the presence of tubocurarine. 8-PT increased the amplitude and quantal content of e.p.p.s in the presence of high magnesium. IBMX, which does not behave as an adenosine receptor antagonist at the frog neuromuscular junction, decreased the amplitude of e.p.p.s in the presence of tubocurarine or high-magnesium solutions. 5. Dipyridamole, an adenosine uptake blocker, decreased the amplitude of e.p.p.s, and in a concentration that did not affect neuromuscular transmission potentiated the depressing effect of adenosine, but not that of 2-chloroadenosine, on the amplitude of e.p.p.s. 6. AOPCP, an inhibitor of 5'-nucleotidase, increased the amplitude of e.p.p.s and markedly attenuated the depressing effect of ATP, but not that of adenosine, on e.p.p. amplitude. 7. The ATP analogue, alpha, beta

  5. Chronic hypoxia enhances adenosine release in rat PC12 cells by altering adenosine metabolism and membrane transport.

    PubMed

    Kobayashi, S; Zimmermann, H; Millhorn, D E

    2000-02-01

    Acute exposure to hypoxia causes a release of adenosine (ADO) that is inversely related to the O2 levels in oxygen-sensitive pheochromocytoma (PC12) cells. In the current study, chronic exposure (48 h) of PC12 cells to moderate hypoxia (5% O2) significantly enhanced the release of ADO during severe, acute hypoxia (1% O2). Investigation into the intra- and extracellular mechanisms underpinning the secretion of ADO in PC12 cells chronically exposed to hypoxia revealed changes in gene expression and activities of several key enzymes associated with ADO production and metabolism, as well as the down-regulation of a nucleoside transporter. Decreases in the enzymatic activities of ADO kinase and ADO deaminase accompanied by an increase in those of cytoplasmic and ecto-5'-nucleotidases bring about an increased capacity to produce intra- and extracellular ADO. This increased potential to generate ADO and decreased capacity to metabolize ADO indicate that PC12 cells shift toward an ADO producer phenotype during hypoxia. The reduced function of the rat equilibrative nucleoside transporter rENT1 also plays a role in controlling extracellular ADO levels. The hypoxia-induced alterations in the ADO metabolic enzymes and the rENT1 transporter seem to increase the extracellular concentration of ADO. The biological significance of this regulation is unclear but is likely to be associated with modulating cellular activity during hypoxia. PMID:10646513

  6. In vivo adenosine A(2B) receptor desensitization in guinea-pig airway smooth muscle: implications for asthma.

    PubMed

    Breschi, Maria Cristina; Blandizzi, Corrado; Fogli, Stefano; Martinelli, Cinzia; Adinolfi, Barbara; Calderone, Vincenzo; Camici, Marcella; Martinotti, Enrica; Nieri, Paola

    2007-12-01

    This study was aimed at characterizing the role of adenosine receptor subtypes in the contractility modulation of guinea-pig airway smooth muscle in normal and pathological settings. In vitro and in vivo experiments were performed by testing selective agonists and antagonists on isolated tracheal smooth muscle preparations and pulmonary inflation pressure, respectively, under normal conditions or following ovalbumin-induced allergic sensitization. In normal and sensitized animals, the adenosine A(2A)/A(2B) receptor agonist, NECA, evoked relaxing responses of isolated tracheal preparations precontracted with histamine, and such an effect was reversed by the adenosine A(2B) antagonist, MRS 1706, in the presence or in the absence of epithelium. The expression of mRNA coding for adenosine A(2B) receptors was demonstrated in tracheal specimens. In vitro desensitization with 100 microM NECA markedly reduced the relaxing effect of the agonist. In vivo NECA or adenosine administration to normal animals inhibited histamine-mediated bronchoconstriction, while these inhibitory effects no longer occurred in sensitized guinea-pigs. Adenosine plasma levels were significantly higher in sensitized than normal animals. In conclusion, our data demonstrate that: (i) adenosine A(2B) receptors are responsible for the relaxing effects of adenosine on guinea-pig airways; (ii) these receptors can undergo rapid adaptive changes that may affect airway smooth muscle responsiveness to adenosine; (iii) ovalbumin-induced sensitization promotes a reversible inactivation of adenosine A(2B) receptors which can be ascribed to homologous desensitization. These findings can be relevant to better understand adenosine functions in airways as well as mechanisms of action of asthma therapies targeting the adenosine system.

  7. Involvement of Peripheral Adenosine A2 Receptors in Adenosine A1 Receptor–Mediated Recovery of Respiratory Motor Function After Upper Cervical Spinal Cord Hemisection

    PubMed Central

    James, Elysia; Nantwi, Kwaku D

    2006-01-01

    Background/Objective: In an animal model of spinal cord injury, a latent respiratory motor pathway can be pharmacologically activated through central adenosine A1 receptor antagonism to restore respiratory function after cervical (C2) spinal cord hemisection that paralyzes the hemidiaphragm ipsilateral to injury. Although respiration is modulated by central and peripheral mechanisms, putative involvement of peripheral adenosine A2 receptors in functional recovery in our model is untested. The objective of this study was to assess the effects of peripherally located adenosine A2 receptors on recovery of respiratory function after cervical (C2) spinal cord hemisection. Methods: Respiratory activity was electrophysiologically assessed (under standardized recording conditions) in C2-hemisected adult rats with the carotid bodies intact (H-CBI; n =12) or excised (H-CBE; n =12). Animals were administered the adenosine A2 receptor agonist, CGS-21680, followed by the A1 receptor antagonist, 1, 3-dipropyl-8-cyclopentylxanthine (DPCPX), or administered DPCPX alone. Recovered respiratory activity, characterized as drug-induced activity in the previously quiescent left phrenic nerve of C2-hemisected animals in H-CBI and H-CBE rats, was compared. Recovered respiratory activity was calculated by dividing drug-induced activity in the left phrenic nerve by activity in the right phrenic nerve. Results: Administration of CGS-21680 before DPCPX (n = 6) in H-CBI rats induced a significantly greater recovery (58.5 ± 3.6%) than when DPCPX (42.6 ± 4.6%) was administered (n = 6) alone. In H-CBE rats, prior administration of CGS-21680 (n = 6) did not enhance recovery over that induced by DPCPX (n = 6) alone. Recovery in H-CBE rats amounted to 39.7 ± 3.7% and 38.4 + 4.2%, respectively. Conclusions: Our results suggest that adenosine A2 receptors located in the carotid bodies can enhance the magnitude of adenosine A1 receptor–mediated recovery of respiratory function after C2 hemisection

  8. Structural basis and evolution of redox regulation in plant adenosine-5;#8242;-phosphosulfate kinase

    SciTech Connect

    Ravilious, Geoffrey E.; Nguyen, Amelia; Francois, Julie A.; Jez, Joseph M.

    2012-05-08

    Adenosine-5'-phosphosulfate (APS) kinase (APSK) catalyzes the phosphorylation of APS to 3'-phospho-APS (PAPS). In Arabidopsis thaliana, APSK is essential for reproductive viability and competes with APS reductase to partition sulfate between the primary and secondary branches of the sulfur assimilatory pathway; however, the biochemical regulation of APSK is poorly understood. The 1.8-{angstrom} resolution crystal structure of APSR from A. thaliana (AtAPSK) in complex with {beta},{gamma}-imidoadenosine-5'-triphosphate, Mg{sup 2+}, and APS provides a view of the Michaelis complex for this enzyme and reveals the presence of an intersubunit disulfide bond between Cys86 and Cys119. Functional analysis of AtAPSK demonstrates that reduction of Cys86-Cys119 resulted in a 17-fold higher kcat/Km and a 15-fold increase in Ki for substrate inhibition by APS compared with the oxidized enzyme. The C86A/C119A mutant was kinetically similar to the reduced WT enzyme. Gel- and activity-based titrations indicate that the midpoint potential of the disulfide in AtAPSK is comparable to that observed in APS reductase. Both cysteines are invariant among the APSK from plants, but not other organisms, which suggests redox-control as a unique regulatory feature of the plant APSK. Based on structural, functional, and sequence analyses, we propose that the redox-sensitive APSK evolved after bifurcation of the sulfur assimilatory pathway in the green plant lineage and that changes in redox environment resulting from oxidative stresses may affect partitioning of APS into the primary and secondary thiol metabolic routes by having opposing effects on APSK and APS reductase in plants.

  9. IL-11 Is Required for A1 Adenosine Receptor–Mediated Protection against Ischemic AKI

    PubMed Central

    Kim, Joo Yun; Kim, Mihwa; Ham, Ahrom; Brown, Kevin M.; Greene, Robert W.; D’Agati, Vivette D.

    2013-01-01

    A1 adenosine receptor activation ameliorates ischemic AKI through the induction of renal proximal tubular sphingosine kinase-1. However, systemic adverse effects may limit A1 adenosine receptor–based therapy for ischemic AKI, indicating a need to identify alternative therapeutic targets within this pathway. Here, we evaluated the function of renal proximal tubular IL-11, a clinically approved hematopoietic cytokine, in A1 adenosine receptor–mediated induction of sphingosine kinase-1 and renal protection. Treatment of human proximal tubule epithelial (HK-2) cells with a selective A1 adenosine receptor agonist, chloro-N(6)-cyclopentyladenosine (CCPA), induced the expression of IL-11 mRNA and protein in an extracellular signal–regulated kinase–dependent manner, and administration of CCPA in mice induced renal synthesis of IL-11. Pretreatment with CCPA protected against renal ischemia-reperfusion injury in wild-type mice, but not in IL-11 receptor–deficient mice. Administration of an IL-11–neutralizing antibody abolished the renal protection provided by CCPA. Similarly, CCPA did not induce renal IL-11 expression or protect against renal ischemia-reperfusion injury in mice lacking the renal proximal tubular A1 adenosine receptor. Finally, treatment with CCPA induced sphingosine kinase-1 in HK-2 cells and wild-type mice, but not in IL-11 receptor–deficient or renal proximal tubule A1 adenosine receptor–deficient mice. Taken together, these results suggest that induction of renal proximal tubule IL-11 is a critical intermediary in A1 adenosine receptor–mediated renal protection that warrants investigation as a novel therapeutic target for the treatment of ischemic AKI. PMID:23813214

  10. Adenosine enhances sweet taste through A2B receptors in the taste bud

    PubMed Central

    Dando, Robin; Dvoryanchikov, Gennady; Pereira, Elizabeth; Chaudhari, Nirupa; Roper, Stephen D.

    2012-01-01

    Mammalian taste buds use ATP as a neurotransmitter. Taste Receptor (Type II) cells secrete ATP via gap junction hemichannels into the narrow extracellular spaces within a taste bud. This ATP excites primary sensory afferent fibers and also stimulates neighboring taste bud cells. Here we show that extracellular ATP is enzymatically degraded to adenosine within mouse vallate taste buds and that this nucleoside acts as an autocrine neuromodulator to selectively enhance sweet taste. In Receptor cells in a lingual slice preparation, Ca2+ mobilization evoked by focally applied artificial sweeteners was significantly enhanced by adenosine (50 µM). Adenosine had no effect on bitter or umami taste responses, and the nucleoside did not affect Presynaptic (Type III) taste cells. We also used biosensor cells to measure transmitter release from isolated taste buds. Adenosine (5 µM) enhanced ATP release evoked by sweet but not bitter taste stimuli. Using single-cell RT-PCR on isolated vallate taste cells, we show that many Receptor cells express adenosine receptors, Adora2b, while Presynaptic (Type III) and Glial-like (Type I) cells seldom do. Furthermore, Adora2b receptors are significantly associated with expression of the sweet taste receptor subunit, Tas1r2. Adenosine is generated during taste stimulation mainly by the action of the ecto-5′-nucleotidase, NT5E, and to a lesser extent, prostatic acid phosphatase (ACPP). Both these ecto-nucleotidases are expressed by Presynaptic cells, as shown by single-cell RT-PCR, enzyme histochemistry and immunofluorescence. Our findings suggest that ATP released during taste reception is degraded to adenosine to exert positive modulation particularly on sweet taste. PMID:22219293

  11. Adenosine enhances sweet taste through A2B receptors in the taste bud.

    PubMed

    Dando, Robin; Dvoryanchikov, Gennady; Pereira, Elizabeth; Chaudhari, Nirupa; Roper, Stephen D

    2012-01-01

    Mammalian taste buds use ATP as a neurotransmitter. Taste Receptor (type II) cells secrete ATP via gap junction hemichannels into the narrow extracellular spaces within a taste bud. This ATP excites primary sensory afferent fibers and also stimulates neighboring taste bud cells. Here we show that extracellular ATP is enzymatically degraded to adenosine within mouse vallate taste buds and that this nucleoside acts as an autocrine neuromodulator to selectively enhance sweet taste. In Receptor cells in a lingual slice preparation, Ca(2+) mobilization evoked by focally applied artificial sweeteners was significantly enhanced by adenosine (50 μM). Adenosine had no effect on bitter or umami taste responses, and the nucleoside did not affect Presynaptic (type III) taste cells. We also used biosensor cells to measure transmitter release from isolated taste buds. Adenosine (5 μM) enhanced ATP release evoked by sweet but not bitter taste stimuli. Using single-cell reverse transcriptase (RT)-PCR on isolated vallate taste cells, we show that many Receptor cells express the adenosine receptor, Adora2b, while Presynaptic (type III) and Glial-like (type I) cells seldom do. Furthermore, Adora2b receptors are significantly associated with expression of the sweet taste receptor subunit, Tas1r2. Adenosine is generated during taste stimulation mainly by the action of the ecto-5'-nucleotidase, NT5E, and to a lesser extent, prostatic acid phosphatase. Both these ecto-nucleotidases are expressed by Presynaptic cells, as shown by single-cell RT-PCR, enzyme histochemistry, and immunofluorescence. Our findings suggest that ATP released during taste reception is degraded to adenosine to exert positive modulation particularly on sweet taste.

  12. Orexin A attenuates the sleep-promoting effect of adenosine in the lateral hypothalamus of rats.

    PubMed

    Cun, Yanping; Tang, Lin; Yan, Jie; He, Chao; Li, Yang; Hu, Zhian; Xia, Jianxia

    2014-10-01

    Orexin neurons within the lateral hypothalamus play a crucial role in the promotion and maintenance of arousal. Studies have strongly suggested that orexin neurons are an important target in endogenous adenosine-regulated sleep homeostasis. Orexin A induces a robust increase in the firing activity of orexin neurons, while adenosine has an inhibitory effect. Whether the excitatory action of orexins in the lateral hypothalamus actually promotes wakefulness and reverses the sleep-producing effect of adenosine in vivo is less clear. In this study, electroencephalographic and electromyographic recordings were used to investigate the effects of orexin A and adenosine on sleep and wakefulness in rats. We found that microinjection of orexin A into the lateral hypothalamus increased wakefulness with a concomitant reduction of sleep during the first 3 h of post-injection recording, and this was completely blocked by a selective antagonist for orexin receptor 1, SB 334867. The enhancement of wakefulness also occurred after application of the excitatory neurotransmitter glutamate in the first 3 h post-injection. However, in the presence of the NMDA receptor antagonist APV, orexin A did not induce any change of sleep and wakefulness in the first 3 h. Further, exogenous application of adenosine into the lateral hypothalamus induced a marked increase of sleep in the first 3-h post-injection. No significant change in sleep and wakefulness was detected after adenosine application followed by orexin A administration into the same brain area. These findings suggest that the sleep-promoting action of adenosine can be reversed by orexin A applied to the lateral hypothalamus, perhaps by exciting glutamatergic input to orexin neurons via the action of orexin receptor 1.

  13. Relaxation of isolated taenia coli of guinea-pig by enantiomers of 2-azido analogues of adenosine and adenine nucleotides.

    PubMed Central

    Cusack, N. J.; Planker, M.

    1979-01-01

    1 2-Azido photoaffinity analogues of adenosine 5'triphosphate (ATP), adenosine 5'-diphosphate (ADP), adenosine 5'-monophosphate (AMP), and adenosine have been synthesized and tested on guinea-pig taenia coli. 2 2-Azido-ATP and 2-azido-ADP were approximately 20 times more potent than ATP as relaxants of taenia coli, and required prolonged washout times before recovery of the muscle. 3 2-Azido-AMP and 2-azidoadenosine were 2 to 12 times more potent than ATP, but took much longer (up to 100 s) to reach maximal relaxation. This behaviour is different from that of AMP and adenosine which were much less potent than ATP. 4 L-Enantiomers of adenosine and adenine nucleotides were also tested. L-ATP and L-ADP were 3 to 6 times less potent than ATP and ADP, and L-AMP and L-adenosine were inactive. 2-Azido-L-ATP and 2-azido-L-ADP were approximately 120 times less potent than 2-Azido-ATP and 6 times less potent than ATP as relaxants of taenia coli. 2-Azido-L-AMP and 2-azidio-L-adenosine were almost inactive. 5 2-Azido derivatives are photolysed by u.v. irradiation to reactive intermediates. 2-Azido-ATP and 2-azidoadenosine might be suitable photoaffinity ligands for labelling putative P2 and P1 purine receptors respectively. 2-Azido-L-ATP and 2-azido-L-adenosine could be useful controls for nonspecific labelling. PMID:497519

  14. Inhibition of Platelet Activation and Thrombus Formation by Adenosine and Inosine: Studies on Their Relative Contribution and Molecular Modeling

    PubMed Central

    Fuentes, Eduardo; Pereira, Jaime; Mezzano, Diego; Alarcón, Marcelo; Caballero, Julio; Palomo, Iván

    2014-01-01

    Background The inhibitory effect of adenosine on platelet aggregation is abrogated after the addition of adenosine-deaminase. Inosine is a naturally occurring nucleoside degraded from adenosine. Objectives The mechanisms of antiplatelet action of adenosine and inosine in vitro and in vivo, and their differential biological effects by molecular modeling were investigated. Results Adenosine (0.5, 1 and 2 mmol/L) inhibited phosphatidylserine exposure from 52±4% in the control group to 44±4 (p<0.05), 29±2 (p<0.01) and 20±3% (p<0.001). P-selectin expression in the presence of adenosine 0.5, 1 and 2 mmol/L was inhibited from 32±4 to 27±2 (p<0.05), 14±3 (p<0.01) and 9±3% (p<0.001), respectively. At the concentrations tested, only inosine to 4 mmol/L had effect on platelet P-selectin expression (p<0.05). Adenosine and inosine inhibited platelet aggregation and ATP release stimulated by ADP and collagen. Adenosine and inosine reduced collagen-induced platelet adhesion and aggregate formation under flow. At the same concentrations adenosine inhibited platelet aggregation, decreased the levels of sCD40L and increased intraplatelet cAMP. In addition, SQ22536 (an adenylate cyclase inhibitor) and ZM241385 (a potent adenosine receptor A2A antagonist) attenuated the effect of adenosine on platelet aggregation induced by ADP and intraplatelet level of cAMP. Adenosine and inosine significantly inhibited thrombosis formation in vivo (62±2% occlusion at 60 min [n = 6, p<0.01] and 72±1.9% occlusion at 60 min, [n = 6, p<0.05], respectively) compared with the control (98±2% occlusion at 60 min, n = 6). A2A is the adenosine receptor present in platelets; it is known that inosine is not an A2A ligand. Docking of adenosine and inosine inside A2A showed that the main difference is the formation by adenosine of an additional hydrogen bond between the NH2 of the adenine group and the residues Asn253 in H6 and Glu169 in EL2 of the A2A receptor. Conclusion Therefore

  15. Adenosine Phosphates in Germinating Radish (Raphanus sativus L.) Seeds 1

    PubMed Central

    Moreland, Donald E.; Hussey, Griscelda G.; Shriner, Carole R.; Farmer, Fred S.

    1974-01-01

    Changes in concentrations of adenosine phosphates (AMP, ADP, and ATP), oxygen utilization, and fresh weights were measured during the first 48 hours after imbibition of water by quiescent radish seeds (Raphanus sativus L.) at 22.5 C. The changes in ATP concentrations, oxygen utilization, and fresh weights followed a triphasic time course, characterized by a rapid initial increase, which extended from 0 to approximately 1.5 hours, a lag phase from 1.5 to 16 hours, and a sharp linear increase from 16 to 48 hours. In unimbibed seeds, the concentrations of ATP, ADP, and AMP were <0.1, 0.9, and 2.2 nmoles/seed, respectively. After imbibition of water by the quiescent seeds, for 1 hour, the ATP concentration had increased to 2.5, and ADP and AMP concentrations had decreased to 0.3 and 0.1 nmole/seed, respectively. These early changes occurred also in seeds maintained under anaerobic conditions (argon), or when treated with either 5 mm fluoroacetate, or 5 mm iodoacetate. The concentrations of ADP and AMP did not change significantly from 1 to 48 hours. The termination of the lag phase at 16 hours correlated with radicle emergence. Cell division in the radicles was initiated at approximately 28 hours. ATP concentrations in seeds maintained under argon or treated with fluoroacetate remained relatively constant from approximately 2 to 48 hours. In contrast, the ATP concentration of iodoacetate-treated seeds decreased curvilinearly from 4 to 48 hours. Oxidative phosphorylation was estimated to have contributed 15, 20, and 65% of the pool ATP at 1.5, 16, and 48 hours, respectively. PMID:16658928

  16. Equilibrium and kinetic selectivity profiling on the human adenosine receptors.

    PubMed

    Guo, Dong; Dijksteel, Gabrielle S; van Duijl, Tirsa; Heezen, Maxime; Heitman, Laura H; IJzerman, Adriaan P

    2016-04-01

    Classical evaluation of target selectivity is usually undertaken by measuring the binding affinity of lead compounds against a number of potential targets under equilibrium conditions, without considering the kinetics of the ligand-receptor interaction. In the present study we propose a combined strategy including both equilibrium- and kinetics-based selectivity profiling. The adenosine receptor (AR) was chosen as a prototypical drug target. Six in-house AR antagonists were evaluated in a radioligand displacement assay for their affinity and in a competition association assay for their binding kinetics on three AR subtypes. One of the compounds with a promising kinetic selectivity profile was also examined in a [(35)S]-GTPγS binding assay for functional activity. We found that XAC and LUF5964 were kinetically more selective for the A1R and A3R, respectively, although they are non-selective in terms of their affinity. In comparison, LUF5967 displayed a strong equilibrium-based selectivity for the A1R over the A2AR, yet its kinetic selectivity thereon was less pronounced. In a GTPγS assay, LUF5964 exhibited insurmountable antagonism on the A3R while having a surmountable effect on the A1R, consistent with its kinetic selectivity profile. This study provides evidence that equilibrium and kinetic selectivity profiling can both be important in the early phases of the drug discovery process. Our proposed combinational strategy could be considered for future medicinal chemistry efforts and aid the design and discovery of different or even better leads for clinical applications.

  17. Behavior and stability of adenosine triphosphate (ATP) during chlorine disinfection.

    PubMed

    Nescerecka, Alina; Juhna, Talis; Hammes, Frederik

    2016-09-15

    Adenosine triphosphate (ATP) analysis is a cultivation-independent alternative method for the determination of bacterial viability in both chlorinated and non-chlorinated water. Here we investigated the behavior and stability of ATP during chlorination in detail. Different sodium hypochlorite doses (0-22.4 mg-Cl2 L(-1); 5 min exposure) were applied to an Escherichia coli pure culture suspended in filtered river water. We observed decreasing intracellular ATP with increasing chlorine concentrations, but extracellular ATP concentrations only increased when the chlorine dose exceeded 0.35 mg L(-1). The release of ATP from chlorine-damaged bacteria coincided with severe membrane damage detected with flow cytometry (FCM). The stability of extracellular ATP was subsequently studied in different water matrixes, and we found that extracellular ATP was stable in sterile deionized water and also in chlorinated water until extremely high chlorine doses (≤11.2 mg-Cl2 L(-1); 5 min exposure). In contrast, ATP decreased relatively slowly (k = 0.145 h(-1)) in 0.1 μm filtered river water, presumably due to degradation by either extracellular enzymes or the fraction of bacteria that were able to pass through the filter. Extracellular ATP decreased considerably faster (k = 0.368 h(-1)) during batch growth of a river water bacterial community. A series of growth potential tests showed that extracellular ATP molecules were utilized as a phosphorus source during bacteria proliferation. From the combined data we conclude that ATP released from bacteria at high chlorine doses could promote bacteria regrowth, contributing to biological instability in drinking water distribution systems. PMID:27295623

  18. Volume and ion effects of adenosine on MDCK cells

    SciTech Connect

    Coffey, A.K.; Allen, J.C.; Coutermarsh, B.A.; Mills, J.W.

    1986-03-01

    Adenosine (ADO) receptors, both internal inhibitory (P-site) and external stimulatory (A2) and inhibitory (Al) have been shown to modulate adenylate cyclase levels. Since the authors have previously shown that cAMP modulates ion content and volume of confluent monolayers of MDCK epithelial cells, the authors investigated the effects of ADO on these parameters. Exposure of MDCK cells to 0.1 mM ADO significantly increased cell volumes (2.35 +/- .10 pL/cell vs. control 2.08 +/- .01; p < .001) as determined by /sup 14/C-urea distribution space, and increased Na content (133 +/- 13 vs. 91 +/- 11 nmol/10/sup 6/ cells; p < .0002). Cl/sup -/ content also increased while K did not change. These effects were completely inhibited by treatment with the Na/sup +//H/sup +/ exchange inhibitor amiloride (0.1 mM) and by incubation in Na-free media. Together these results suggest that cell volume increased due to Na/sup +/ entry via the Na/sup +//H/sup +/ exchanger. However, 2-chloroadenosine (2CA), a potent analogue of ADO, caused a significant decrease in cell volume (1.99 +/- .86 vs. 2.21 +/- 0.13 pL/cell; p < .02) and Na (97 +/- 22 vs. 141 +/- 21 nmol/10/sup 6/ cells; p < .005). Measurement of cell cAMP by radioimmunoassay showed an increase in response to 2CA but not to ADO. Since the effects of 2CA mimic those of exogenous cAMP, MDCK cells appear to have a stimulatory (A2) receptor. However, ADO itself did not interact with this receptor and may have produced its effects by binding to a higher affinity, inhibitory receptor.

  19. Purine derivatives as ligands for A3 adenosine receptors.

    PubMed

    Joshi, Bhalchandra V; Jacobson, Kenneth A

    2005-01-01

    Selective agonists and antagonists for A3 adenosine receptors (ARs) are being explored for the treatment of a variety of disorders, including brain and heart ischemic conditions, cancer, and rheumatoid arthritis. This review covers both the structure activity relationships of nucleoside agonist ligands and selected antagonists acting at this receptor and the routes of synthesis. Highly selective agonists have been designed, using both empirical approaches and a semi-rational approach based on molecular modeling. The prototypical A3 agonists IB-MECA 10 and the more receptor-subtype-selective Cl-IB-MECA 11, both of which have affinity in binding to the receptor of approximately 1 nM, have been used widely as pharmacological probes in the elucidation of the physiological role of this receptor. In addition to the exploration of the effects of structural modification of the adenine and ribose moieties on A3AR affinity, the effects of these structural changes on the intrinsic efficacy have also been studied in a systematic fashion. Key structural features determining A3AR interaction include the N6-benzyl group, 2-position substitution such as halo, substitution of ribose (e.g., the (N)-methanocarba ring system, various 2'- and 3'-substitutions and 4'-thio substitution of oxygen). Conformational studies of the ribose moiety and its equivalents indicate that the ring oxygen is not required and the North (N) ring conformation is preferred in binding to the A3AR. Using these observations, a series of ring constrained (N)-methanocarba 5'-uronamide derivatives was recently reported to be highly selective A3AR agonists, the most notable amongst them was MRS3558 113 having a Ki value in binding to the human A3 receptor of 0.3 nM. PMID:16305531

  20. Equilibrium and kinetic selectivity profiling on the human adenosine receptors.

    PubMed

    Guo, Dong; Dijksteel, Gabrielle S; van Duijl, Tirsa; Heezen, Maxime; Heitman, Laura H; IJzerman, Adriaan P

    2016-04-01

    Classical evaluation of target selectivity is usually undertaken by measuring the binding affinity of lead compounds against a number of potential targets under equilibrium conditions, without considering the kinetics of the ligand-receptor interaction. In the present study we propose a combined strategy including both equilibrium- and kinetics-based selectivity profiling. The adenosine receptor (AR) was chosen as a prototypical drug target. Six in-house AR antagonists were evaluated in a radioligand displacement assay for their affinity and in a competition association assay for their binding kinetics on three AR subtypes. One of the compounds with a promising kinetic selectivity profile was also examined in a [(35)S]-GTPγS binding assay for functional activity. We found that XAC and LUF5964 were kinetically more selective for the A1R and A3R, respectively, although they are non-selective in terms of their affinity. In comparison, LUF5967 displayed a strong equilibrium-based selectivity for the A1R over the A2AR, yet its kinetic selectivity thereon was less pronounced. In a GTPγS assay, LUF5964 exhibited insurmountable antagonism on the A3R while having a surmountable effect on the A1R, consistent with its kinetic selectivity profile. This study provides evidence that equilibrium and kinetic selectivity profiling can both be important in the early phases of the drug discovery process. Our proposed combinational strategy could be considered for future medicinal chemistry efforts and aid the design and discovery of different or even better leads for clinical applications. PMID:26930564

  1. Adenosine triphosphate inhibits melatonin synthesis in the rat pineal gland.

    PubMed

    Souza-Teodoro, Luis Henrique; Dargenio-Garcia, Letícia; Petrilli-Lapa, Camila Lopes; Souza, Ewerton da Silva; Fernandes, Pedro A C M; Markus, Regina P; Ferreira, Zulma S

    2016-03-01

    Adenosine triphosphate (ATP) is released onto the pinealocyte, along with noradrenaline, from sympathetic neurons and triggers P2Y1 receptors that enhance β-adrenergic-induced N-acetylserotonin (NAS) synthesis. Nevertheless, the biotransformation of NAS into melatonin, which occurs due to the subsequent methylation by acetylserotonin O-methyltransferase (ASMT; EC 2.1.1.4), has not yet been evaluated in the presence of purinergic stimulation. We therefore evaluated the effects of purinergic signaling on melatonin synthesis induced by β-adrenergic stimulation. ATP increased NAS levels, but, surprisingly, inhibited melatonin synthesis in an inverse, concentration-dependent manner. Our results demonstrate that enhanced NAS levels, which depend on phospholipase C (PLC) activity (but not the induction of gene transcription), are a post-translational effect. By contrast, melatonin reduction is related to an ASMT inhibition of expression at both the gene transcription and protein levels. These results were independent of nuclear factor-kappa B (NF-kB) translocation. Neither the P2Y1 receptor activation nor the PLC-mediated pathway was involved in the decrease in melatonin, indicating that ATP regulates pineal metabolism through different mechanisms. Taken together, our data demonstrate that purinergic signaling differentially modulates NAS and melatonin synthesis and point to a regulatory role for ATP as a cotransmitter in the control of ASMT, the rate-limiting enzyme in melatonin synthesis. The endogenous production of melatonin regulates defense responses; therefore, understanding the mechanisms involving ASMT regulation might provide novel insights into the development and progression of neurological disorders since melatonin presents anti-inflammatory, neuroprotective, and neurogenic effects.

  2. Behavior and stability of adenosine triphosphate (ATP) during chlorine disinfection.

    PubMed

    Nescerecka, Alina; Juhna, Talis; Hammes, Frederik

    2016-09-15

    Adenosine triphosphate (ATP) analysis is a cultivation-independent alternative method for the determination of bacterial viability in both chlorinated and non-chlorinated water. Here we investigated the behavior and stability of ATP during chlorination in detail. Different sodium hypochlorite doses (0-22.4 mg-Cl2 L(-1); 5 min exposure) were applied to an Escherichia coli pure culture suspended in filtered river water. We observed decreasing intracellular ATP with increasing chlorine concentrations, but extracellular ATP concentrations only increased when the chlorine dose exceeded 0.35 mg L(-1). The release of ATP from chlorine-damaged bacteria coincided with severe membrane damage detected with flow cytometry (FCM). The stability of extracellular ATP was subsequently studied in different water matrixes, and we found that extracellular ATP was stable in sterile deionized water and also in chlorinated water until extremely high chlorine doses (≤11.2 mg-Cl2 L(-1); 5 min exposure). In contrast, ATP decreased relatively slowly (k = 0.145 h(-1)) in 0.1 μm filtered river water, presumably due to degradation by either extracellular enzymes or the fraction of bacteria that were able to pass through the filter. Extracellular ATP decreased considerably faster (k = 0.368 h(-1)) during batch growth of a river water bacterial community. A series of growth potential tests showed that extracellular ATP molecules were utilized as a phosphorus source during bacteria proliferation. From the combined data we conclude that ATP released from bacteria at high chlorine doses could promote bacteria regrowth, contributing to biological instability in drinking water distribution systems.

  3. Molecular Determinants of CGS21680 Binding to the Human Adenosine A2A Receptor

    PubMed Central

    Edwards, Patricia C.; Leslie, Andrew G. W.

    2015-01-01

    The adenosine A2A receptor (A2AR) plays a key role in transmembrane signaling mediated by the endogenous agonist adenosine. Here, we describe the crystal structure of human A2AR thermostabilized in an active-like conformation bound to the selective agonist 2-[p-(2-carboxyethyl)phenylethyl-amino]-5′-N-ethylcarboxamido adenosine (CGS21680) at a resolution of 2.6 Å. Comparison of A2AR structures bound to either CGS21680, 5′-N-ethylcarboxamido adenosine (NECA), UK432097 [6-(2,2-diphenylethylamino)-9-[(2R,3R,4S,5S)-5-(ethylcarbamoyl)-3,4-dihydroxy-tetrahydrofuran-2-yl]-N-[2-[[1-(2-pyridyl)-4-piperidyl]carbamoylamino]ethyl]purine-2-carboxamide], or adenosine shows that the adenosine moiety of the ligands binds to the receptor in an identical fashion. However, an extension in CGS21680 compared with adenosine, the (2-carboxyethyl)phenylethylamino group, binds in an extended vestibule formed from transmembrane regions 2 and 7 (TM2 and TM7) and extracellular loops 2 and 3 (EL2 and EL3). The (2-carboxyethyl)phenylethylamino group makes van der Waals contacts with side chains of amino acid residues Glu169EL2, His264EL3, Leu2677.32, and Ile2747.39, and the amine group forms a hydrogen bond with the side chain of Ser672.65. Of these residues, only Ile2747.39 is absolutely conserved across the human adenosine receptor subfamily. The major difference between the structures of A2AR bound to either adenosine or CGS21680 is that the binding pocket narrows at the extracellular surface when CGS21680 is bound, due to an inward tilt of TM2 in that region. This conformation is stabilized by hydrogen bonds formed by the side chain of Ser672.65 to CGS21680, either directly or via an ordered water molecule. Mutation of amino acid residues Ser672.65, Glu169EL2, and His264EL3, and analysis of receptor activation either in the presence or absence of ligands implicates this region in modulating the level of basal activity of A2AR. PMID:25762024

  4. Adenosine stimulates DNA fragmentation in human thymocytes by Ca(2+)-mediated mechanisms.

    PubMed

    Szondy, Z

    1994-12-15

    Incubation of human thymocytes with an optimum concentration of adenosine and its receptor site agonist, 2-chloroadenosine, induced increases in intracellular cyclic AMP (cAMP) (from a resting 0.6 +/- 0.1 to 4.1 +/- 0.2 pmol/10(7) cells within 5 min) and Ca2+ (from the resting 85 +/- 7 nM to a peak of 210 +/- 25 nM) levels and resulted in internucleosomal DNA fragmentation and cell death (apoptosis). Other adenosine analogues were also effective at inducing DNA fragmentation, the order of potency being 2-p-(carboxyethylphenylethylamino)-5'-carboxyamidoadenosine < 5'-(N-ethylcarboxamide)adenosine < or = cyclopentyladenosine < 2-chloroadenosine (2-CA). 2-CA treatment (with an optimum concentration of 40 microM) selectively depleted a thymocyte subpopulation (15-20% of the total cells) which expressed higher levels of the CD3 molecule and which was found mainly in the CD4+CD8+ double positive immature thymocyte population. DNA fragmentation was prevented by the addition of actinomycin D or cycloheximide to the thymocyte suspension, indicating that this process required both mRNA and protein synthesis. Endonuclease activation and cell killing were dependent on an early, sustained increase in cytosolic Ca2+ concentration, most of which was of extracellular origin and was a result of an adenosine-induced inositol trisphosphate release. Other agents known to elevate intracellular cAMP levels by different mechanisms failed to induce similar DNA fragmentation, but enhanced the effect of adenosine. This suggested a supporting role for cAMP in adenosine-induced DNA fragmentation. Phorbol dibutyrate, a protein kinase. C activator, previously shown to inhibit Ca(2+)-dependent DNA fragmentation and cell killing in human thymocytes [McConkey, Hartzell, Jondal and Orrenius (1989) J. Biol. Chem. 264, 13399-13402], at 60 ng/ml concentration also prevented adenosine-induced DNA fragmentation when added prior to adenosine. This suggested a complex cross-talk between the adenosine

  5. Adenosine signaling inhibits CIITA-mediated MHC class II transactivation in lung fibroblast cells.

    PubMed

    Fang, Mingming; Xia, Jun; Wu, Xiaoyan; Kong, Hui; Wang, Hong; Xie, Weiping; Xu, Yong

    2013-08-01

    Efficient antigen presentation by major histocompatibility complex (MHC) molecules represents a critical process in adaptive immunity. Class II transactivator (CIITA) is considered the master regulator of MHC class II (MHC II) transcription. Previously, we have shown that CIITA expression is upregulated in smooth muscle cells deficient in A2b adenosine receptor. Here, we report that treatment with the adenosine receptor agonist adenosine-5'N-ethylcarboxamide (NECA) attenuated MHC II transcription in lung fibro-blast cells as a result of CIITA repression. Further analysis revealed that NECA preferentially abrogated CIITA transcription through promoters III and IV. Blockade with a selective A2b receptor antagonist MRS-1754 restored CIITA-dependent MHC II transactivation. Forskolin, an adenylyl cyclase activator, achieved the same effect as NECA. A2b signaling repressed CIITA transcription by altering histone modifications and recruitment of key factors on the CIITA promoters in a STAT1-dependent manner. MRS-1754 blocked the antagonism of transforming growth factor beta (TGF-β) in CIITA induction by interferon gamma (IFN-γ), alluding to a potential dialogue between TGF-β and adenosine signaling pathways. Finally, A2b signaling attenuated STAT1 phosphorylation and stimulated TGF-β synthesis. In conclusion, we have identified an adenosine-A2b receptor-adenylyl cyclase axis that influences CIITA-mediated MHC II transactivation in lung fibroblast cells and as such have provided invaluable insights into the development of novel immune-modulatory strategies.

  6. Content of Adenosine Phosphates and Adenylate Energy Charge in Germinating Ponderosa Pine Seeds

    PubMed Central

    Ching, Te May; Ching, Kim K.

    1972-01-01

    An average of 540 picomoles of total adenosine phosphates was found in the embryo of mature seeds of ponderosa pine (Pinus ponderosa Laws.) and 1140 picomoles in the gametophyte. Adenylate energy charges were 0.44 and 0.26, respectively. After stratification, total adenosine phosphates increased 7-fold and 6-fold in embryo and gametophyte, respectively, and energy charges rose to 0.85 and 0.75. During germination, total adenosine phosphates increased to a 20-fold peak on the 9th day in gametophytic tissue, parallel with the peak of reserve regradation and organellar synthesis, and then decreased. In embryo and seedling, total adenosine phosphates elevated 80-fold with two distinct oscillating increases of AMP and ADP. The oscillating increases occurred before the emergence of radicle and cotyledons during which the highest mitotic index prevailed in all tissues. Energy charges fluctuated between 0.65 at the rapid cell dividing stage to 0.85 at the fully differentiated stage of the seedling, while energy charges remained around 0.75 in the gametophyte. These data indicated that the content of adenosine phosphates of germinating seeds reflects growth, organogenesis, and morphogenesis, and that a compartmentalized energy metabolism must exist in dividing and growing plant cells. PMID:16658212

  7. Lack of tolerance to motor stimulant effects of a selective adenosine A(2A) receptor antagonist.

    PubMed

    Halldner, L; Lozza, G; Lindström, K; Fredholm, B B

    2000-10-20

    It is well known that tolerance develops to the actions of caffeine, which acts as an antagonist on adenosine A(1) and A(2A) receptors. Since selective adenosine A(2A) antagonists have been proposed as adjuncts to 3,4-dihydroxyphenylalanine (L-DOPA) therapy in Parkinson's disease we wanted to examine if tolerance also develops to the selective A(2A) receptor antagonist 5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo-[4,3-e]-1,2, 4-triazolo [1,5-c]pyrimidine (SCH 58261). SCH 58261 (0.1 and 7.5 mg/kg) increased basal locomotion and the motor stimulation afforded by apomorphine. Neither effect was subject to tolerance following long-term treatment with the same doses given intraperitoneally twice daily. There were no adaptive changes in A(1) and A(2A) adenosine receptors or their corresponding messenger RNA or in dopamine D(1) or D(2) receptors. These results demonstrate that the tolerance that develops to caffeine is not secondary to its inhibition of adenosine A(2A) receptors. The results also offer hope that long-term treatment with an adenosine A(2A) receptor antagonist may be possible in man.

  8. Squalenoyl Adenosine Nanoparticles provide Neuroprotection after Stroke and Spinal Cord Injury

    PubMed Central

    Gaudin, Alice; Yemisci, Müge; Eroglu, Hakan; Lepêtre-Mouelhi, Sinda; Turkoglu, Omer Faruk; Dönmez-Demir, Buket; Caban, Seçil; Fevzi Sargon, Mustafa; Garcia-Argote, Sébastien; Pieters, Grégory; Loreau, Olivier; Rousseau, Bernard; Tagit, Oya; Hildebrandt, Niko; Le Dantec, Yannick; Mougin, Julie; Valetti, Sabrina; Chacun, Hélène; Nicolas, Valérie; Desmaële, Didier; Andrieux, Karine; Capan, Yilmaz; Dalkara, Turgay; Couvreur, Patrick

    2014-01-01

    There is an urgent need to develop new therapeutic approaches for the treatment of severe neurological trauma, such as stroke and spinal cord injuries. However, many drugs with potential neuropharmacological activity, like adenosine, are inefficient upon systemic administration because of their fast metabolisation and rapid clearance from the bloodstream. Here, we show that the conjugation of adenosine to the lipid squalene and the subsequent formation of nanoassemblies allow a prolonged circulation of this nucleoside, to provide neuroprotection in mouse stroke and rat spinal cord injury models. The animals receiving systemic administration of squalenoyl adenosine nanoassemblies showed a significant improvement of their neurologic deficit score in the case of cerebral ischaemia, and an early motor recovery of the hindlimbs in the case of spinal cord injury. Moreover, in vitro and in vivo studies demonstrated that the nanoassemblies were able to extend adenosine circulation and its interaction with the neurovascular unit. This paper shows, for the first time, that a hydrophilic and rapidly metabolised molecule like adenosine may become pharmacologically efficient owing to a single conjugation with the lipid squalene. PMID:25420034

  9. Endogenous adenosine modulates stimulation-induced depression at the frog neuromuscular junction.

    PubMed Central

    Meriney, S D; Grinnell, A D

    1991-01-01

    1. Endogenous adenosine, which is produced by enzymatic degradation of ATP released from synaptic vesicles, has been shown to be a potent inhibitor of acetylcholine release from motor nerve terminals. It has been proposed that this auto-inhibition mechanism might contribute significantly to tetanic stimulation-induced depression. 2. Levels of facilitation and depression during a 20 Hz stimulus train differ greatly in different terminals, but are strongly and non-linearly correlated with the terminal's release characteristics (the amount of transmitter released per unit terminal length, or 'release efficacy'). There is a weaker, approximately linear, correlation between depression and release efficacy at 2 Hz stimulation. 3. The effects of both endogenous and exogenously applied adenosine are also highly variable for different nerve terminals. We have shown that much of this variability can be attributed to the release efficacy of each terminal in the case of endogenous effects, and to the size of the nerve terminal in the case of exogenously applied adenosine receptor agonists. 4. When nerve terminals are pooled according to their individual release characteristics, endogenous adenosine can be shown to contribute significantly to stimulation-induced depression of release primarily in terminals that release enough transmitter to generate significant levels of adenosine, but do not release so much transmitter that depletion of releasable quanta is severe. Images Fig. 1 PMID:1688026

  10. The impact of adenosine and A(2B) receptors on glucose homoeostasis.

    PubMed

    Rüsing, D; Müller, C E; Verspohl, E J

    2006-12-01

    Adenosine and adenosine receptor antagonists are involved in glucose homoeostasis. The participating receptors are not known, mainly due to a lack of specific agonists and antagonists, but are reasonable targets for anti-diabetic therapy. The stable, albeit nonselective, adenosine analogue NECA (5'-N-ethylcarboxamidoadenosine) (10 microM) reduced glucose-stimulated insulin release from INS-1 cells. This was mimicked by A(1)-(CHA), A(2A)-(CGS-21680) and A(3)-receptor agonists (Cl-IB-MECA). Two newly synthesized A(2B)-receptor antagonists, PSB-53 and PSB-1115, counteracted the inhibitory effect of NECA. These in-vitro effects were mirrored by in-vivo data with respect to CHA, CGS and Cl-IB-MECA. Distinct concentrations of either PSB-53 or PSB-1115 reversed the decrease in plasma insulin induced by NECA. This was not mimicked by a corresponding change in blood glucose. The effect of PSB-1115 was also obvious in diabetic GotoKakizaki rats: plasma insulin was increased whereas blood glucose was unchanged. During most experiments the effects on blood glucose were not impressive probably because of the physiologically necessary homoeostasis. The adenosine levels were not different in normal Wistar rats and in diabetic GotoKakzaki rats. Altogether the A(2B)-receptor antagonists showed an anti-diabetic potential mainly by increasing plasma insulin levels under conditions when the adenosine tonus was elevated in-vivo and increased insulin release in-vitro.

  11. Purification of an Ion-Stimulated Adenosine Triphosphatase from Plant Roots: Association with Plasma Membranes

    PubMed Central

    Hodges, T. K.; Leonard, R. T.; Bracker, C. E.; Keenan, T. W.

    1972-01-01

    A membrane-bound adenosine triphosphatase (EC 3.6.1.3) that requires Mg++ and that is stimulated by monovalent ions has been purified 7- to 8-fold from homogenates of oat (Avena sativa L. Cult. Goodfield) roots by discontinuous sucrose-gradient centrifugation. The enzyme was substrate specific; adenosine triphosphate was hydrolyzed 25 times more rapidly than other nucleoside triphosphates. The membrane fraction containing adenosine triphosphatase was enriched in plasma membranes, which were identified by the presence of a glucan synthetase (EC 2.4.1.12), a high sterol to phospholipid ratio, and by a stain consisting of periodic acid, chromic acid, and phosphotungstic acid that is specific for plant plasma membranes. Oat-root plasma membranes and the associated adenosine triphosphatase were purified on either a 6-layer discontinuous sucrose gradient or on a simplified gradient consisting of only two sucrose layers. These results represent the first demonstration that plant plasma membranes contain an adenosine triphosphatase that is activated by monovalent ions, and this finding further implicates the enzyme in the absorption of inorganic ions by plant roots. Images PMID:16592027

  12. Endogenous adenosine release is involved in the control of heart rate in rats.

    PubMed

    Jammes, Yves; Joulia, Fabrice; Steinberg, Jean Guillaume; Ravailhe, Sylvie; Delpierre, Stéphane; Condo, Jocelyne; Guieu, Regis; Delliaux, Stéphane

    2015-08-01

    Intravenous (i.v.) injections of adenosine exert marked effects on heart rate (HR) and arterial blood pressure (BP), but the role of an endogenous adenosine release by vagal stimulation has not been evaluated. In anaesthetized rats, we examined HR and BP changes induced by 1 min electrical vagal stimulation in the control condition, and then after i.v. injections of (i) atropine, (ii) propranolol, (iii) caffeine, (iv) 8 cyclopentyl-1,3-dipropylxanthine (DPCPX), or (v) dipyridamole to increase the plasma concentration of adenosine (APC). APC was measured by chromatography in the arterial blood before and at the end of vagal stimulation. The decrease in HR in the controls during vagal stimulation was markedly attenuated, but persisted after i.v. injections of atropine and propranolol. When first administered, DPCPX modestly but significantly reduced the HR response to vagal stimulation, but this disappeared after i.v. caffeine administration. Both the HR and BP responses were significantly accentuated after i.v. injection of dipyridamole. Vagal stimulation induced a significant increase in APC, proportional to the magnitude of HR decrease. Our data suggest that the inhibitory effects of electrical vagal stimulations on HR and BP were partly mediated through the activation of A1 and A2 receptors by an endogenous adenosine release. Our experimental data could help to understand the effects of ischemic preconditioning, which are partially mediated by adenosine. PMID:26222197

  13. Neurochemical Measurement of Adenosine in Discrete Brain Regions of Five Strains of Inbred Mice

    PubMed Central

    Pani, Amar K.; Jiao, Yun; Sample, Kenneth J.; Smeyne, Richard J.

    2014-01-01

    Adenosine (ADO), a non-classical neurotransmitter and neuromodulator, and its metabolites adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP), have been shown to play an important role in a number of biochemical processes. Although their signaling is well described, it has been difficult to directly, accurately and simultaneously quantitate these purines in tissue or fluids. Here, we describe a novel method for measuring adenosine (ADO) and its metabolites using high performance liquid chromatography with electrochemical detection (HPLC-ECD). Using this chromatographic technique, we examined baseline levels of ADO and ATP, ADP and AMP in 6 different brain regions of the C57BL/6J mouse: stratum, cortex, hippocampus, olfactory bulb, substantia nigra and cerebellum and compared ADO levels in 5 different strains of mice (C57BL/6J, Swiss-Webster, FVB/NJ, 129P/J, and BALB/c). These studies demonstrate that baseline levels of purines vary significantly among the brain regions as well as between different mouse strains. These dissimilarities in purine concentrations may explain the variable phenotypes among background strains described in neurological disease models. PMID:24642754

  14. Obligatory coupling between proton entry and the synthesis of adenosine 5'-triphosphate in Streptococcus lactis.

    PubMed Central

    Maloney, P C

    1977-01-01

    Proton influx was measured after imposition of an electrochemical potential difference for protons (delta muH+) across the cell membrane of the anaerobe, Streptococcus lactis. As delta muH+ was increased, there was an approximately parallel increase in proton entry, until delta muH+ attained 175 to 200 mV. At this point, a new pathway became available for proton entry, allowing an abrupt increase in both the rate and extent of H+ influx. This gated response depended upon the value of delta muH+ itself, and not upon the value of either the membrane potential or the pH gradient. For delta muH+ above 175 to 200 mV, elevated proton entry occurred only in cells having a functional membrane-bound Ca2+-stimulated, Mg2+stimulated adenosine 5'-triphosphatase (EC 3.6.1.3). When present, elevated proton entry coincided with the appearance of net synthesis of adenosine 5'-triphosphate catalyzed by this adenosine 5'-triphosphatase. These observations demonstrate that membrane-bound adenosine 5'-triphosphatase catalyzes an obligatory coupling between the inward movement of protons and synthesis of adenosine 5'-triphosphate. PMID:21165

  15. Astrocyte-derived adenosine is central to the hypnogenic effect of glucose

    PubMed Central

    Scharbarg, Emeric; Daenens, Marion; Lemaître, Frédéric; Geoffroy, Hélène; Guille-Collignon, Manon; Gallopin, Thierry; Rancillac, Armelle

    2016-01-01

    Sleep has been hypothesised to maintain a close relationship with metabolism. Here we focus on the brain structure that triggers slow-wave sleep, the ventrolateral preoptic nucleus (VLPO), to explore the cellular and molecular signalling pathways recruited by an increase in glucose concentration. We used infrared videomicroscopy on ex vivo brain slices to establish that glucose induces vasodilations specifically in the VLPO via the astrocytic release of adenosine. Real-time detection by in situ purine biosensors further revealed that the adenosine level doubles in response to glucose, and triples during the wakefulness period. Finally, patch-clamp recordings uncovered the depolarizing effect of adenosine and its A2A receptor agonist, CGS-21680, on sleep-promoting VLPO neurons. Altogether, our results provide new insights into the metabolically driven release of adenosine. We hypothesise that adenosine adjusts the local energy supply to local neuronal activity in response to glucose. This pathway could contribute to sleep-wake transition and sleep intensity. PMID:26755200

  16. Squalenoyl adenosine nanoparticles provide neuroprotection after stroke and spinal cord injury

    NASA Astrophysics Data System (ADS)

    Gaudin, Alice; Yemisci, Müge; Eroglu, Hakan; Lepetre-Mouelhi, Sinda; Turkoglu, Omer Faruk; Dönmez-Demir, Buket; Caban, Seçil; Sargon, Mustafa Fevzi; Garcia-Argote, Sébastien; Pieters, Grégory; Loreau, Olivier; Rousseau, Bernard; Tagit, Oya; Hildebrandt, Niko; Le Dantec, Yannick; Mougin, Julie; Valetti, Sabrina; Chacun, Hélène; Nicolas, Valérie; Desmaële, Didier; Andrieux, Karine; Capan, Yilmaz; Dalkara, Turgay; Couvreur, Patrick

    2014-12-01

    There is an urgent need to develop new therapeutic approaches for the treatment of severe neurological trauma, such as stroke and spinal cord injuries. However, many drugs with potential neuropharmacological activity, such as adenosine, are inefficient upon systemic administration because of their fast metabolization and rapid clearance from the bloodstream. Here, we show that conjugation of adenosine to the lipid squalene and the subsequent formation of nanoassemblies allows prolonged circulation of this nucleoside, providing neuroprotection in mouse stroke and rat spinal cord injury models. The animals receiving systemic administration of squalenoyl adenosine nanoassemblies showed a significant improvement of their neurologic deficit score in the case of cerebral ischaemia, and an early motor recovery of the hindlimbs in the case of spinal cord injury. Moreover, in vitro and in vivo studies demonstrated that the nanoassemblies were able to extend adenosine circulation and its interaction with the neurovascular unit. This Article shows, for the first time, that a hydrophilic and rapidly metabolized molecule such as adenosine may become pharmacologically efficient owing to a single conjugation with the lipid squalene.

  17. Sulfur-Containing 1,3-Dialkylxanthine Derivatives as Selective Antagonists at A1-Adenosine Receptors

    PubMed Central

    Kiriasis, Leonidas; Barone, Suzanne; Bradbury, Barton J.; Kammula, Udai; Campagne, Jean Michel; Secunda, Sherrie; Daly, John W.; Neumeyer, John L.; Pfleiderer, Wolfgang

    2012-01-01

    Sulfur-containing analogues of 8-substituted xanthines were prepared in an effort to increase selectivity or potency as antagonists at adenosine receptors. Either cyclopentyl or various aryl substituents were utilized at the 8-position, because of the association of these groups with high potency at A1-adenosine receptors. Sulfur was incorporated on the purine ring at positions 2 and/or 6, in the 8-position substituent in the form of 2- or 3-thienyl groups, or via thienyl groups separated from an 8-aryl substituent through an amide-containing chain. The feasibility of using the thienyl group as a prosthetic group for selective iodination via its Hg2+ derivative was explored. Receptor selectivity was determined in binding assays using membrane homogenates from rat cortex [[3H]-N6-(phenylisopropyl) adenosine as radioligand] or striatum [[3H]-5′-(N-ethylcarbamoyl)adenosine as radioligand] for A1- and A2-adenosine receptors, respectively. Generally, 2-thio-8-cycloalkylxanthines were at least as A1 selective as the corresponding oxygen analogue. 2-Thio-8-aryl derivatives tended to be more potent at A2 receptors than the oxygen analogue. 8-[4-[(Carboxymethyl)oxy]phenyl]-1,3-dipropyl-2-thioxanthine ethyl ester was >740-fold A1 selective. PMID:2754711

  18. An ultraviolet-inducible adenosine-adenosine cross-link reflects the catalytic structure of the Tetrahymena ribozyme

    SciTech Connect

    Downs, W.D.; Cech, T.R. )

    1990-06-12

    When a shortened enzymatic version of the Tetrahymena self-splicing intervening sequence (IVS) RNA is placed under catalytic conditions and irradiated at 254 nm, a covalent cross-link forms with high efficiency. The position of the cross-link was mapped by using three independent methods: RNase H digestion, primer extension with reverse transcriptase, and partial hydrolysis of end-labeled RNA. The cross-link is chemically unusual in that it joins two adenosines, A57 and A95. Formation of this cross-link depends upon the identity and concentration of divalent cations present and upon heat-cool renaturation of the IVS in a manner that parallels conditions required for optimal catalytic activity. Furthermore, cross-linking requires the presence of sequences within the core structure, which is conserved among group I intervening sequences and necessary for catalytic activity. Together these correlations suggest that a common folded structure permits cross-linking and catalytic activity. The core can form this structure independent of the presence of P1 and elements at the 3' end of the IVS. The cross-linked RNA loses catalytic activity under destabilizing conditions, presumably due to disruption of the folded structure by the cross-link. One of the nucleotides participating in this cross-link is highly conserved (86%) within the secondary structure of group I intervening sequences. We conclude that A57 and A95 are precisely aligned in a catalytically active conformation of the RNA. A model is presented for the tertiary arrangement in the vicinity of the cross-link.

  19. Impairment of ATP hydrolysis decreases adenosine A1 receptor tonus favoring cholinergic nerve hyperactivity in the obstructed human urinary bladder.

    PubMed

    Silva-Ramos, M; Silva, I; Faria, M; Magalhães-Cardoso, M T; Correia, J; Ferreirinha, F; Correia-de-Sá, P

    2015-12-01

    This study was designed to investigate whether reduced adenosine formation linked to deficits in extracellular ATP hydrolysis by NTPDases contributes to detrusor neuromodulatory changes associated with bladder outlet obstruction in men with benign prostatic hyperplasia (BPH). The kinetics of ATP catabolism and adenosine formation as well as the role of P1 receptor agonists on muscle tension and nerve-evoked [(3)H]ACh release were evaluated in mucosal-denuded detrusor strips from BPH patients (n = 31) and control organ donors (n = 23). The neurogenic release of ATP and [(3)H]ACh was higher (P < 0.05) in detrusor strips from BPH patients. The extracellular hydrolysis of ATP and, subsequent, adenosine formation was slower (t (1/2) 73 vs. 36 min, P < 0.05) in BPH detrusor strips. The A(1) receptor-mediated inhibition of evoked [(3)H]ACh release by adenosine (100 μM), NECA (1 μM), and R-PIA (0.3 μM) was enhanced in BPH bladders. Relaxation of detrusor contractions induced by acetylcholine required 30-fold higher concentrations of adenosine. Despite VAChT-positive cholinergic nerves exhibiting higher A(1) immunoreactivity in BPH bladders, the endogenous adenosine tonus revealed by adenosine deaminase is missing. Restoration of A1 inhibition was achieved by favoring (1) ATP hydrolysis with apyrase (2 U mL(-1)) or (2) extracellular adenosine accumulation with dipyridamole or EHNA, as these drugs inhibit adenosine uptake and deamination, respectively. In conclusion, reduced ATP hydrolysis leads to deficient adenosine formation and A(1) receptor-mediated inhibition of cholinergic nerve activity in the obstructed human bladder. Thus, we propose that pharmacological manipulation of endogenous adenosine levels and/or A(1) receptor activation might be useful to control bladder overactivity in BPH patients.

  20. The role of adenosine receptors in regulating production of tumour necrosis factor-α and chemokines by human lung macrophages

    PubMed Central

    Buenestado, A; Delyle, S Grassin; Arnould, I; Besnard, F; Naline, E; Blouquit-Laye, S; Chapelier, A; Bellamy, JF; Devillier, P

    2010-01-01

    Background and purpose: Adenosine is a major endogenous regulator of macrophage function, and activates four specific adenosine receptors (A1, A2A, A2B and A3). Here, we have assessed in human lung macrophages the modulation of the expression of adenosine receptor mRNA by lipopolysaccharide (LPS), and the relative contributions of the different adenosine receptors to LPS-induced production of tumour necrosis factor (TNF)-α and chemokines. Experimental approach: Lung macrophages isolated from resected lungs were stimulated with LPS and treated with adenosine receptor agonists or/and antagonists. Adenosine receptor expression was assessed with qRT-PCR. Cytokines were measured in lung macrophage supernatants with elisa. Key results: LPS increased (about 400-fold) mRNA for A2A adenosine receptors, decreased mRNA for A1 and A2B, but had no effect on A3 adenosine receptor mRNA. The adenosine receptor agonist NECA inhibited TNF-α production concentration dependently, whereas the A1 receptor agonist, CCPA, and the A3 receptor agonist, AB-MECA, inhibited TNF-α production only at concentrations affecting A2A receptors. NECA also inhibited the production of CCL chemokines (CCL2, CCL3, CCL4, CCL5) and CXCL chemokines (CXCL9 and CXCL10), but not that of CXCL1, CXCL8 and CXCL5. Reversal of NECA-induced inhibition of TNF-α and chemokine production by the selective A2A adenosine receptor antagonist ZM 241385, but not the A2B receptor antagonist, MRS 1754, or the A3 receptor antagonist, MRS 1220, indicated involvement of A2A receptors. Conclusions and implications: LPS up-regulated A2A adenosine receptor gene transcription, and this receptor subtype mediated inhibition of the LPS-induced production of TNF-α and of a subset of chemokines in human lung macrophages. PMID:20136829

  1. Role of adenosine in the antiepileptic effects of deep brain stimulation

    PubMed Central

    Miranda, Maisa F.; Hamani, Clement; de Almeida, Antônio-Carlos G.; Amorim, Beatriz O.; Macedo, Carlos E.; Fernandes, Maria José S.; Nobrega, José N.; Aarão, Mayra C.; Madureira, Ana Paula; Rodrigues, Antônio M.; Andersen, Monica L.; Tufik, Sergio; Mello, Luiz E.; Covolan, Luciene

    2014-01-01

    Despite the effectiveness of anterior thalamic nucleus (AN) deep brain stimulation (DBS) for the treatment of epilepsy, mechanisms responsible for the antiepileptic effects of this therapy remain elusive. As adenosine modulates neuronal excitability and seizure activity in animal models, we hypothesized that this nucleoside could be one of the substrates involved in the effects of AN DBS. We applied 5 days of stimulation to rats rendered chronically epileptic by pilocarpine injections and recorded epileptiform activity in hippocampal slices. We found that slices from animals given DBS had reduced hippocampal excitability and were less susceptible to develop ictal activity. In live animals, AN DBS significantly increased adenosine levels in the hippocampus as measured by microdialysis. The reduced excitability of DBS in vitro was completely abolished in animals pre-treated with A1 receptor antagonists and was strongly potentiated by A1 receptor agonists. We conclude that some of the antiepileptic effects of DBS may be mediated by adenosine. PMID:25324724

  2. Autoradiographic localization of adenosine receptors in rat brain using (/sup 3/H)cyclohexyladenosine

    SciTech Connect

    Goodman, R.R.; Synder, S.H.

    1982-09-01

    Adenosine (A1) receptor binding sites have been localized in rat brain by an in vitro light microscopic autoradiographic method. The binding of (/sup 3/H)N6-cyclohexyladenosine to slide-mounted rat brain tissue sections has the characteristics of A1 receptors. It is saturable with high affinity and has appropriate pharmacology and stereospecificity. The highest densities of adenosine receptors occur in the molecular layer of the cerebellum, the molecular and polymorphic layers of the hippocampus and dentate gyrus, the medial geniculate body, certain thalamic nuclei, and the lateral septum. High densities also are observed in certain layers of the cerebral cortex, the piriform cortex, the caudate-putamen, the nucleus accumbens, and the granule cell layer of the cerebellum. Most white matter areas, as well as certain gray matter areas, such as the hypothalamus, have negligible receptor concentrations. These localizations suggest possible central nervous system sites of action of adenosine.

  3. Circadian rhythm in adenosine A1 receptor of mouse cerebral cortex

    SciTech Connect

    Florio, C.; Rosati, A.M.; Traversa, U.; Vertua, R. )

    1991-01-01

    In order to investigate diurnal variation in adenosine A1 receptors binding parameters, Bmax and Kd values of specifically bound N6-cyclohexyl-({sup 3}H)adenosine were determined in the cerebral cortex of mice that had been housed under controlled light-dark cycles for 4 weeks. Significant differences were found for Bmax values measured at 3-hr intervals across a 24-h period, with low Bmax values during the light period and high Bmax values during the dark period. The amplitude between 03.00 and 18.00 hr was 33%. No substantial rhythm was found in the Kd values. It is suggested that the changes in the density of A1 receptors could reflect a physiologically-relevant mechanism by which adenosine exerts its modulatory role in the central nervous system.

  4. Activation of two sites by adenosine receptor agonists to cause relaxation in rat isolated mesenteric artery

    PubMed Central

    Prentice, D J; Payne, S L; Hourani, S M O

    1997-01-01

    In this study we have characterized the receptor(s) in the rat mesenteric artery mediating relaxant responses to adenosine and a number of adenosine analogues, N6 -R-phenylisopropyladenosine (R-PIA), N6-cyclopentyladenosine (CPA), N6-(3-iodo-benzyl)-adenosine-5′-N-methyluronamide (IB-MECA) and 5′-N-ethylcarboxamidoadenosine (NECA), by use of the non-selective antagonist 8-sulphophenyltheophylline (8-SPT) and the A2A selective ligands 2-[p-(2-carbonylethyl)-phenylethylamino]-5′-N-ethylcarboxamidoadenosine (CGS 21680) and 4-(2-[7-amino-2-(2-furyl)[1,2,4]-triazolo[2,3-a][1,3,5]-triazin-5-ylamino]ethyl) phenol (ZM 241385). We have also studied the effects of endothelial removal and uptake inhibition by nitrobenzylthioinosine (NBTI) and the effects of the A3 receptor antagonist 1,3-dipropyl-8-(4-acrylate)phenylxanthine (BWA1433).Adenosine, NECA, CPA and R-PIA all elicited relaxant responses in tissues precontracted with phenylephrine (1 μM) with the following potency order: NECA>R-PIA>adenosine=CPA. However, E/[A] curves to NECA were biphasic. CGS 21680 was inactive at concentrations up to 30 μM and IB-MECA elicited relaxant responses which were resistant to blockade by 8-SPT and BWA1433 (100 μM).Removal of the endothelium produced a small but significant decrease in the asymptote of the high potency phase of E/[A] curves to NECA with no change in p[A]50. E/[A] curves to adenosine were not altered by removal of the endothelium. However, there were small rightward shifts of E/[A] curves to CPA and R-PIA in the absence of endothelium.Inhibition of uptake by NBTI (1 μM) had no effect on E/[A] curves to NECA, CPA or R-PIA, but E/[A] curves to adenosine were significantly left-shifted in the presence of NBTI.8-SPT (10–100 μM) caused significant rightward shifts of the high potency phase of the E/[A] curves to NECA (pA2=5.63±0.26). The second phase of the concentration-response curve to NECA appeared to be resistant to blockade by 8-SPT, as were E

  5. The Three Possible 2-(Pyrenylethynyl) Adenosines: Rotameric Energy Barriers Govern the Photodynamics of These Structural Isomers.

    PubMed

    Reuss, Andreas J; Grünewald, Christian; Braun, Markus; Engels, Joachim W; Wachtveitl, Josef

    2016-05-01

    This article presents a comprehensive study of the photophysics of 2-(2-pyrenylethynyl) adenosine and 2-(4-pyrenylethynyl) adenosine, which are structural isomers of the well-established fluorescent RNA label 2-(1-pyrenylethynyl) adenosine. We performed steady-state and ultrafast transient absorption spectroscopy studies along with time-resolved fluorescence emission experiments in different solvents to work out the interplay of locally excited and charge-transfer states. We found the ultrafast photodynamics to be crucial for the fluorescence decay behavior, which extends up to tens of nanoseconds and is partially multi-exponential. These features in the ultrafast dynamics are indicative of the rotational energy barriers in the first excited state.

  6. Computational study of the molecular mechanisms of caffeine action: Caffeine complexes with adenosine receptors

    NASA Astrophysics Data System (ADS)

    Poltev, V. I.; Rodríguez, E.; Grokhlina, T. I.; Deriabina, A.; Gonzalez, E.

    To understand the molecular basis of the principal biological action of the caffeine (CAF), the molecular mechanics calculations of possible complexes between CAF and the fragments of human A1 adenosine receptor were performed. The fragments were selected after considerations of the CAF molecular structure and its possible interactions, as well as after an analysis of the extensive bibliography on the structure, biological role, site-directed mutagenesis, and the modeling of the adenosine receptors. The minimum energy configurations of these complexes were obtained using two different computer programs with different force fields. The most favorable configurations correspond to the formation of two hydrogen bonds between the CAF molecule and hydrophilic amino acid residues of the fragments of transmembrane domains of the receptor. These configurations are supposed to contribute to CAF blocking of the adenosine receptors. They will be used later for the construction of model CAF complexes with two transmembrane domains simultaneously.

  7. Structure of the DNA Ligase-Adenylate Intermediate: Lysine (ε-amino)-Linked Adenosine Monophosphoramidate*

    PubMed Central

    Gumport, Richard I.; Lehman, I. R.

    1971-01-01

    Proteolytic degradation of the Escherichia coli DNA ligase-adenylate intermediate releases adenosine 5′-monophosphate linked to the ε-amino group of lysine by a phosphoamide bond. Measurements of the rate of hydroxylaminolysis of the ligase-adenylate provide further support for a phosphoamide linkage in the native enzyme. Lysine (ε-amino)-linked adenosine monophosphoramidate has also been isolated from the T4 phage-induced ligase-adenylate intermediate. These results indicate that an initial step of the DNA ligase reaction consists of the nucleophilic attack of the ε-amino group of a lysine residue of the enzyme on the adenylyl phosphorus of DPN or ATP that leads to the formation of enzyme-bound lysine (εamino)-linked adenosine monophosphoramidate. PMID:4944632

  8. Enthalpy and enzyme activity of modified histidine residues of adenosine deaminase and diethyl pyrocarbonate complexes.

    PubMed

    Ataie, G; Moosavi-Movahedi, A A; Saboury, A A; Hakimelahi, G H; Hwu, J R; Tsay, S C

    2000-03-16

    Kinetic and thermodynamic studies have been made on the effect of diethyl pyrocarbonate as a histidine modifier on the active site of adenosine deaminase in 50 mM sodium phosphate buffer pH 6.8, at 27 degrees C using UV spectrophotometry and isothermal titration calorimetry (ITC). Inactivation of adenosine deaminase by diethyl pyrocarbonate is correlated with modification of histidyl residues. The number of modified histidine residues complexed to active site of adenosine deaminase are equivalent to 4. The number and energy of histidine binding sets are determined by enthalpy curve, which represents triple stages. These stages are composed of 3,1 and 1 sites of histidyl modified residues at diethyl pyrocarbonate concentrations, 0.63, 1.8, 3.3 mM. The heat contents corresponding to the first, second and third sets are found to be 18000, 22000 and 21900 kJ mol(-1) respectively.

  9. Autoradiographic localization of adenosine uptake sites in rat brain using (/sup 3/H)nitrobenzylthioinosine

    SciTech Connect

    Bisserbe, J.C.; Patel, J.; Marangos, P.J.

    1985-02-01

    The adenosine uptake site has been localized in rat brain by an in vitro light microscopic autoradiographic method, using (/sup 3/H)nitrobenzylthioinosine ((/sup 3/H)NBI) as the probe. The binding characteristics of (/sup 3/H)NBI on slide-mounted sections are comparable to those seen in studies performed on brain homogenates. A very high density of uptake sites occurs in the nucleus tractus solitarius, in the superficial layer of the superior colliculus, in several thalamic nuclei, and also in geniculate body nuclei. A high density of sites are also observed in the nucleus accumbens, the caudate putamen, the dorsal tegmentum area, the substantia nigra, and the central gray. The localization of the adenosine uptake site in brain may provide information on the functional activity of the site and suggests the involvement of the adenosine system in the central regulation of cardiovascular function.

  10. Caffeine's Attenuation of Cocaine-Induced Dopamine Release by Inhibition of Adenosine

    PubMed Central

    Malave, Lauren B.

    2014-01-01

    Background: It is well known that the reinforcing properties of cocaine addiction are caused by the sharp increase of dopamine (DA) in the reward areas of the brain. However, other mechanisms have been speculated to contribute to the increase. Adenosine is one system that is associated with the sleep-wake cycle and is most important in regulating neuronal activity. Thus, more and more evidence is pointing to its involvement in regulating DA release. The current study set out to examine the role of adenosine in cocaine-induced DA release. Methods: Increasing doses of cocaine, caffeine, and their combination, as well as, 8-cyclopentyltheophylline (CPT), an adenosine A1 antagonist (alone and in combination with cocaine) were used to denote a response curve. A novel biosensor, the BRODERICK PROBE® was implanted in the nucleus accumbens to image the drug-induced surge of DA release in vivo, in the freely moving animal in real time. Results: Combinations of cocaine and caffeine were observed to block the increased release of DA moderately after administration of the low dose (2.5 mg/kg cocaine and 12.5 mg/kg caffeine) and dramatically after administration of the high dose (10 mg/kg cocaine and 50 mg/kg caffeine), suggesting neuroprotection. Similarly, CPT and cocaine showed a decreased DA surge when administered in combination. Thus, the low and high dose of a nonselective adenosine antagonist, caffeine, and a moderate dose of a selective adenosine antagonist, CPT, protected against the cocaine-induced DA release. Conclusions: These results show a significant interaction between adenosine and DA release and suggest therapeutic options for cocaine addiction and disorders associated with DA dysfunction. PMID:25054079

  11. Caffeine's Attenuation of Cocaine-Induced Dopamine Release by Inhibition of Adenosine.

    PubMed

    Malave, Lauren B; Broderick, Patricia A

    2014-06-01

    Background: It is well known that the reinforcing properties of cocaine addiction are caused by the sharp increase of dopamine (DA) in the reward areas of the brain. However, other mechanisms have been speculated to contribute to the increase. Adenosine is one system that is associated with the sleep-wake cycle and is most important in regulating neuronal activity. Thus, more and more evidence is pointing to its involvement in regulating DA release. The current study set out to examine the role of adenosine in cocaine-induced DA release. Methods: Increasing doses of cocaine, caffeine, and their combination, as well as, 8-cyclopentyltheophylline (CPT), an adenosine A1 antagonist (alone and in combination with cocaine) were used to denote a response curve. A novel biosensor, the BRODERICK PROBE(®) was implanted in the nucleus accumbens to image the drug-induced surge of DA release in vivo, in the freely moving animal in real time. Results: Combinations of cocaine and caffeine were observed to block the increased release of DA moderately after administration of the low dose (2.5 mg/kg cocaine and 12.5 mg/kg caffeine) and dramatically after administration of the high dose (10 mg/kg cocaine and 50 mg/kg caffeine), suggesting neuroprotection. Similarly, CPT and cocaine showed a decreased DA surge when administered in combination. Thus, the low and high dose of a nonselective adenosine antagonist, caffeine, and a moderate dose of a selective adenosine antagonist, CPT, protected against the cocaine-induced DA release. Conclusions: These results show a significant interaction between adenosine and DA release and suggest therapeutic options for cocaine addiction and disorders associated with DA dysfunction. PMID:25054079

  12. Adenosine receptor antagonists alter the stability of human epileptic GABAA receptors

    PubMed Central

    Roseti, Cristina; Martinello, Katiuscia; Fucile, Sergio; Piccari, Vanessa; Mascia, Addolorata; Di Gennaro, Giancarlo; Quarato, Pier Paolo; Manfredi, Mario; Esposito, Vincenzo; Cantore, Gianpaolo; Arcella, Antonella; Simonato, Michele; Fredholm, Bertil B.; Limatola, Cristina; Miledi, Ricardo; Eusebi, Fabrizio

    2008-01-01

    We examined how the endogenous anticonvulsant adenosine might influence γ-aminobutyric acid type A (GABAA) receptor stability and which adenosine receptors (ARs) were involved. Upon repetitive activation (GABA 500 μM), GABAA receptors, microtransplanted into Xenopus oocytes from neurosurgically resected epileptic human nervous tissues, exhibited an obvious GABAA-current (IGABA) run-down, which was consistently and significantly reduced by treatment with the nonselective adenosine receptor antagonist CGS15943 (100 nM) or with adenosine deaminase (ADA) (1 units/ml), that inactivates adenosine. It was also found that selective antagonists of A2B (MRS1706, 10 nM) or A3 (MRS1334, 30 nM) receptors reduced IGABA run-down, whereas treatment with the specific A1 receptor antagonist DPCPX (10 nM) was ineffective. The selective A2A receptor antagonist SCH58261 (10 nM) reduced or potentiated IGABA run-down in ≈40% and ≈20% of tested oocytes, respectively. The ADA-resistant, AR agonist 2-chloroadenosine (2-CA) (10 μM) potentiated IGABA run-down but only in ≈20% of tested oocytes. CGS15943 administration again decreased IGABA run-down in patch-clamped neurons from either human or rat neocortex slices. IGABA run-down in pyramidal neurons was equivalent in A1 receptor-deficient and wt neurons but much larger in neurons from A2A receptor-deficient mice, indicating that, in mouse cortex, GABAA-receptor stability is tonically influenced by A2A but not by A1 receptors. IGABA run-down from wt mice was not affected by 2-CA, suggesting maximal ARs activity by endogenous adenosine. Our findings strongly suggest that cortical A2–A3 receptors alter the stability of GABAA receptors, which could offer therapeutic opportunities. PMID:18809912

  13. Myocardial blood flow and adenosine A2A receptor density in endurance athletes and untrained men

    PubMed Central

    Heinonen, Ilkka; Nesterov, Sergey V; Liukko, Kaisa; Kemppainen, Jukka; Någren, Kjell; Luotolahti, Matti; Virsu, Pauliina; Oikonen, Vesa; Nuutila, Pirjo; Kujala, Urho M; Kainulainen, Heikki; Boushel, Robert; Knuuti, Juhani; Kalliokoski, Kari K

    2008-01-01

    Previous human studies have shown divergent results concerning the effects of exercise training on myocardial blood flow (MBF) at rest or during adenosine-induced hyperaemia in humans. We studied whether these responses are related to alterations in adenosine A2A receptor (A2AR) density in the left-ventricular (LV) myocardium, size and work output of the athlete's heart, or to fitness level. MBF at baseline and during intravenous adenosine infusion, and A2AR density at baseline were measured using positron emission tomography, and by a novel A2AR tracer in 10 healthy male endurance athletes (ET) and 10 healthy untrained (UT) men. Structural LV parameters were measured with echocardiography. LV mass index was 71% higher in ET than UT (193 ± 18 g m−2versus 114 ± 13 g m−2, respectively). MBF per gram of tissue was significantly lower in the ET than UT at baseline, but this was only partly explained by reduced LV work load since MBF corrected for LV work was higher in ET than UT, as well as total MBF. The MBF during adenosine-induced hyperaemia was reduced in ET compared to UT, and the fitter the athlete was, the lower was adenosine-induced MBF. A2AR density was not different between the groups and was not coupled to resting or adenosine-mediated MBF. The novel findings of the present study show that the adaptations in the heart of highly trained endurance athletes lead to relative myocardial ‘overperfusion’ at rest. On the other hand hyperaemic perfusion is reduced, but is not explained by A2AR density. PMID:18772204

  14. Cloning and expression of an A1 adenosine receptor from rat brain

    SciTech Connect

    Mahan, L.C.; McVittie, L.D.; Smyk-Randall, E.M.; Nakata, H.; Monsma, F.J. Jr.; Gerfen, C.R.; Sibley, D.R. )

    1991-07-01

    The authors have used the polymerase chain reaction technique to selectively amplify guanine nucleotide-binding regulatory protein (G protein)-coupled receptor cDNA sequences from rat striatal mRNA, using sets of highly degenerate primers derived from transmembrane sequences of previously cloned G protein-coupled receptors. A novel cDNA fragment was identified, which exhibits considerable homology to various members of the G protein-coupled receptor family. This fragment was used to isolate a full-length cDNA from a rat striatal library. A 2.2-kilobase clone was obtained that encodes a protein of 326 amino acids with seven transmembrane domains, as predicted by hydropathy analysis. Stably transfected mouse A9-L cells and Chinese hamster ovary cells that expressed mRNA for this clone were screened with putative receptor ligands. Saturable and specific binding sites for the A1 adenosine antagonist (3H)-1,3-dipropyl-8-cyclopentylxanthine were identified on membranes from transfected cells. The rank order of potency and affinities of various adenosine agonist and antagonist ligands confirmed the identity of this cDNA clone as an A1 adenosine receptor. The high affinity binding of A1 adenosine agonists was shown to be sensitive to the nonhydrolyzable GTP analog guanylyl-5{prime}-imidodiphosphate. In adenylyl cyclase assays, adenosine agonists inhibited forskolin-stimulated cAMP production by greater than 50%, in a pharmacologically specific fashion. Northern blot and in situ hybridization analyses of receptor mRNA in brain tissues revealed two transcripts of 5.6 and 3.1 kilobases, both of which were abundant in cortex, cerebellum, hippocampus, and thalamus, with lower levels in olfactory bulb, striatum, mesencephalon, and retina. These regional distribution data are in good agreement with previous receptor autoradiographic studies involving the A1 adenosine receptor.

  15. Adenosine transport systems on dissociated brain cells from mouse, guinea-pig, and rat

    SciTech Connect

    Johnston, M.E.; Geiger, J.D. )

    1990-09-01

    The kinetics and sodium dependence of adenosine transport were determined using an inhibitor-stop method on dissociated cell body preparations obtained from mouse, guinea-pig and rat brain. Transport affinity (KT) values for the high affinity adenosine transport systems KT(H) were significantly different between these three species; mean +/- SEM values were 0.34 +/- 0.1 in mouse, 0.9 +/- 0.2 in rat, and 1.5 +/- 0.5 microM in guinea-pig. The KT values for the low affinity transport system KT(L) were not different between the three species. Brain cells from rat displayed a significantly greater maximal capacity to accumulate (3H)adenosine (Vmax) than did mouse or guinea-pig for the high affinity system, or than did mouse for the low affinity system. When sodium chloride was replaced in the transport medium with choline chloride, the KT(H) values for guinea-pig and rat were both increased by approximately 100%; only in rat did the change reach statistical significance. The sodium-dependence of adenosine transport in mouse brain was clearly absent. The differences between KT(H) values in mouse and those in guinea-pig or rat were accentuated in the absence of sodium. The differences in kinetic values, ionic requirements, and pharmacological characteristics between adenosine transporters in CNS tissues of mouse, guinea-pig and rat may help account for some of the variability noted among species in terms of their physiological responses to adenosine.

  16. Adenosine restores angiotensin II-induced contractions by receptor-independent enhancement of calcium sensitivity in renal arterioles.

    PubMed

    Lai, En Yin; Martinka, Peter; Fähling, Michael; Mrowka, Ralf; Steege, Andreas; Gericke, Adrian; Sendeski, Mauricio; Persson, P B; Persson, A Erik G; Patzak, Andreas

    2006-11-10

    Adenosine is coupled to energy metabolism and regulates tissue blood flow by modulating vascular resistance. In this study, we investigated isolated, perfused afferent arterioles of mice, which were subjected to desensitization during repeated applications of angiotensin II. Exogenously applied adenosine restores angiotensin II-induced contractions by increasing calcium sensitivity of the arterioles, along with augmented phosphorylation of the regulatory unit of the myosin light chain. Adenosine restores angiotensin II-induced contractions via intracellular action, because inhibition of adenosine receptors do not prevent restoration, but inhibition of NBTI sensitive adenosine transporters does. Restoration was prevented by inhibition of Rho-kinase, protein kinase C, and the p38 mitogen-activated protein kinase, which modulate myosin light chain phosphorylation and thus calcium sensitivity in the smooth muscle. Furthermore, adenosine application increased the intracellular ATP concentration in LuciHEK cells. The results of the study suggest that restoration of the angiotensin II-induced contraction by adenosine is attributable to the increase of the calcium sensitivity by phosphorylation of the myosin light chain. This can be an important component of vascular control during ischemic and hypoxic conditions. Additionally, this mechanism may contribute to the mediation of the tubuloglomerular feedback by adenosine in the juxtaglomerular apparatus of the kidney. PMID:17038642

  17. Rat fat-cells have three types of adenosine receptors (Ra, Ri and P). Differential effects of pertussis toxin.

    PubMed Central

    García-Sáinz, J A; Torner, M L

    1985-01-01

    Activation of rat adipocyte R1 adenosine receptors by phenylisopropyladenosine (PIA) decreased cyclic AMP and lipolysis; this effect was blocked in cells from pertussis-toxin-treated rats. In contrast, the ability of 2',5'-dideoxyadenosine to decrease cyclic AMP was not affected by pertussis-toxin treatment. Addition of adenosine deaminase to the medium in which adipocytes from control animals were incubated resulted in activation of lipolysis. Interestingly, adipocytes from toxin-treated rats (which had an already increased basal lipolysis) responded in an opposite fashion to the addition of adenosine deaminase, i.e. the enzyme decreased lipolysis, which suggested that adenosine might be increasing lipolysis in these cells. Studies with the selective agonists N-ethylcarboxamidoadenosine (NECA) and PIA indicated that adenosine increases lipolysis and cyclic AMP accumulation in these cells and that these actions are mediated through Ra adenosine receptors. Adenosine-mediated accumulation of cyclic AMP was also observed in cells preincubated with pertussis toxin (2 micrograms/ml) for 3 h. In these studies NECA was also more effective than PIA. Our results indicate that there are three types of adenosine receptors in fat-cells, whose actions are affected differently by pertussis toxin, i.e. Ri-mediated actions are abolished, Ra-mediated actions are revealed and P-mediated actions are not affected. PMID:3004405

  18. NTS adenosine A2a receptors inhibit the cardiopulmonary chemoreflex control of regional sympathetic outputs via a GABAergic mechanism.

    PubMed

    Minic, Zeljka; O'Leary, Donal S; Scislo, Tadeusz J

    2015-07-01

    Adenosine is a powerful central neuromodulator acting via opposing A1 (inhibitor) and A2a (activator) receptors. However, in the nucleus of the solitary tract (NTS), both adenosine receptor subtypes attenuate cardiopulmonary chemoreflex (CCR) sympathoinhibition of renal, adrenal, and lumbar sympathetic nerve activity and attenuate reflex decreases in arterial pressure and heart rate. Adenosine A1 receptors inhibit glutamatergic transmission in the CCR pathway, whereas adenosine A2a receptors most likely facilitate release of an unknown inhibitory neurotransmitter, which, in turn, inhibits the CCR. We hypothesized that adenosine A2a receptors inhibit the CCR via facilitation of GABA release in the NTS. In urethane-chloralose-anesthetized rats (n = 51), we compared regional sympathetic responses evoked by stimulation of the CCR with right atrial injections of the 5-HT3 receptor agonist phenylbiguanide (1-8 μg/kg) before and after selective stimulation of NTS adenosine A2a receptors [microinjections into the NTS of CGS-21680 (20 pmol/50 nl)] preceded by blockade of GABAA or GABAB receptors in the NTS [bicuculline (10 pmol/100 nl) or SCH-50911 (1 nmol/100 nl)]. Blockade of GABAA receptors virtually abolished adenosine A2a receptor-mediated inhibition of the CCR. GABAB receptors had much weaker but significant effects. These effects were similar for the different sympathetic outputs. We conclude that stimulation of NTS adenosine A2a receptors inhibits CCR-evoked hemodynamic and regional sympathetic reflex responses via a GABA-ergic mechanism.

  19. NTS adenosine A2a receptors inhibit the cardiopulmonary chemoreflex control of regional sympathetic outputs via a GABAergic mechanism.

    PubMed

    Minic, Zeljka; O'Leary, Donal S; Scislo, Tadeusz J

    2015-07-01

    Adenosine is a powerful central neuromodulator acting via opposing A1 (inhibitor) and A2a (activator) receptors. However, in the nucleus of the solitary tract (NTS), both adenosine receptor subtypes attenuate cardiopulmonary chemoreflex (CCR) sympathoinhibition of renal, adrenal, and lumbar sympathetic nerve activity and attenuate reflex decreases in arterial pressure and heart rate. Adenosine A1 receptors inhibit glutamatergic transmission in the CCR pathway, whereas adenosine A2a receptors most likely facilitate release of an unknown inhibitory neurotransmitter, which, in turn, inhibits the CCR. We hypothesized that adenosine A2a receptors inhibit the CCR via facilitation of GABA release in the NTS. In urethane-chloralose-anesthetized rats (n = 51), we compared regional sympathetic responses evoked by stimulation of the CCR with right atrial injections of the 5-HT3 receptor agonist phenylbiguanide (1-8 μg/kg) before and after selective stimulation of NTS adenosine A2a receptors [microinjections into the NTS of CGS-21680 (20 pmol/50 nl)] preceded by blockade of GABAA or GABAB receptors in the NTS [bicuculline (10 pmol/100 nl) or SCH-50911 (1 nmol/100 nl)]. Blockade of GABAA receptors virtually abolished adenosine A2a receptor-mediated inhibition of the CCR. GABAB receptors had much weaker but significant effects. These effects were similar for the different sympathetic outputs. We conclude that stimulation of NTS adenosine A2a receptors inhibits CCR-evoked hemodynamic and regional sympathetic reflex responses via a GABA-ergic mechanism. PMID:25910812

  20. Rapid Induction of Ion Pulses in Tomato, Cucumber, and Maize Plants following a Foliar Application of L(+)-Adenosine.

    PubMed Central

    Ries, S.; Savithiry, S.; Wert, V.; Widders, I.

    1993-01-01

    Application of picomole quantities of (+)-adenosine, a plant growth-regulating second messenger elicited by triacontanol, to tomato (Lycopersicon esculentum Mill.), maize (Zea mays L.), and cucumber (Cucumis sativa L.) foliage, increased Ca2+, Mg2+, and K+ concentrations in the exudate from the stumps of excised plants by 20 to 60% within 5 s after treatment. The change in ionic concentration of the exudate was transitory. When L(+)-adenosine and triacontanol were applied to different tomato plants at the same time, the L(+)-adenosine caused an increase in Ca2+ flux within 3 s, whereas a significant increase from triacontanol was not detectable until 5 min after application. This was expected because triacontanol elicits the formation of L(+)-adenosine. The enantiomer of L(+)-adenosine, D(-)-adenosine, had no effect on the cation concentration in tomato and inhibited the effect of L(+)-adenosine at equimolar or lower concentrations. These observations suggest that L(+)-adenosine acts by eliciting a rapidly propagated signal that increases the concentration of several ions in the apoplast. We postulate that modulations in apoplastic ion concentration, especially increases in Ca2+ concentration, constitute a mechanism by which plants regulate metabolic activity and growth in response to certain stimuli. PMID:12231664

  1. Binary Drugs: Conjugates of Purines and a Peptide That Bind to Both Adenosine and Substance P Receptors

    PubMed Central

    Jacobson, Kenneth A.; Lipkowski, Andrzej W.; Moody, Terry W.; Padgett, William; Pijl, Evelyn; Kirk, Kenneth L.; Daly, John W.

    2012-01-01

    A “functionalized congener” approach to adenosine receptor antagonists has provided a means to synthesize highly potent peptide conjugates of 1,3-dialkylxanthines. The antagonist XAC, such a functionalized xanthine amine congener, has been attached to a segment derived from the neurotransmitter peptide substance P (SP) to form a binary drug that binds to both receptors with Ki values of 35 nM (central A1-adenosine) and 300 nM (striatal SP). Coupling of the functionalized adenosine agonist N6-[p-(carboxymethyl)phenyl]adenosine to an SP C-terminal peptide also resulted in a binary drug that binds to both receptors. The demonstration that the biochemical properties of two unrelated drugs, both of which act through binding at extracellular receptors, may be combined in the same molecule suggests a novel strategy for drug design. In principle, a combined effect of the two different substances that produce the same final effect (e.g., hypotension by adenosine agonists and by SP analogues) might occur in vivo. Adenosine analogues have analgesic properties, and the binary drug derived from substance P and adenosine agonists or antagonists might provide useful tools for probing interrelationships of SP pathways and sites for the antinociceptive action of adenosine. PMID:2441057

  2. Structure-activity studies of 5-substituted pyridopyrimidines as adenosine kinase inhibitors.

    PubMed

    Cowart, M; Lee, C H; Gfesser, G A; Bayburt, E K; Bhagwat, S S; Stewart, A O; Yu, H; Kohlhaas, K L; McGaraughty, S; Wismer, C T; Mikusa, J; Zhu, C; Alexander, K M; Jarvis, M F; Kowaluk, E A

    2001-01-01

    The synthesis and SAR of a novel series of non-nucleoside pyridopyrimidine inhibitors of the enzyme adenosine kinase (AK) are described. It was found that pyridopyrimidines with a broad range of medium and large non-polar substituents at the 5-position potently inhibited AK activity. A narrower range of analogues was capable of potently inhibiting adenosine phosphorylation in intact cells indicating an enhanced ability of these analogues to penetrate cell membranes. Potent AK inhibitors were found to effectively reduce nociception in animal models of thermal hyperalgesia and persistent pain.

  3. Impaired Erectile Function in CD73-deficient Mice with Reduced Endogenous Penile Adenosine Production

    PubMed Central

    Wen, Jiaming; Dai, Yingbo; Zhang, Yujin; Zhang, Weiru; Kellems, Rodney E.; Xia, Yang

    2012-01-01

    Introduction Adenosine has been implicated in normal and abnormal penile erection. However, a direct role of endogenous adenosine in erectile physiology and pathology has not been established. Aim To determine the functional role of endogenous adenosine production in erectile function. Methods CD73-deficient mice (CD73−/−) and age-matched wild-type (WT) mice were used. Some WT mice were treated with alpha, beta-methylene adenosine diphosphate (ADP) (APCP), a CD73-specific inhibitor. High-performance liquid chromatography was used to measure adenosine levels in mouse penile tissues. In vivo assessment of intracorporal pressure (ICP) normalized to mean arterial pressure (MAP) in response to electrical stimulation (ES) of the cavernous nerve was used. Main Outcome Measurement The main outcome measures of this study were the in vivo assessment of initiation and maintenance of penile erection in WT mice and mice with deficiency in CD73 (ecto-5′-nucleotidase), a key cell-surface enzyme to produce extracellular adenosine. Results Endogenous adenosine levels were elevated in the erected state induced by ES of cavernous nerve compared to the flaccid state in WT mice but not in CD73−/− mice. At cellular levels, we identified that CD73 was highly expressed in the neuronal, endothelial cells, and vascular smooth muscle cells in mouse penis. Functionally, we found that the ratio of ES-induced ICP to MAP in CD73−/− mice was reduced from 0.48 ± 0.03 to 0.33 ± 0.05 and ES-induced slope was reduced from 0.30 ± 0.13 mm Hg/s to 0.15 ± 0.05 mm Hg/s (both P < 0.05). The ratio of ES-induced ICP to MAP in APCP-treated WT mice was reduced from 0.49 ± 0.03 to 0.38 ± 0.06 and ES-induced slope was reduced from 0.29 ± 0.11 mm Hg/s to 0.19 ± 0.04 mm Hg/s (both P < 0.05). Conclusion Overall, our findings demonstrate that CD73-dependent production of endogenous adenosine plays a direct role in initiation and maintenance of penile erection. PMID:21595838

  4. Exploiting Protein Conformational Change to Optimize Adenosine-Derived Inhibitors of HSP70.

    PubMed

    Cheeseman, Matthew D; Westwood, Isaac M; Barbeau, Olivier; Rowlands, Martin; Dobson, Sarah; Jones, Alan M; Jeganathan, Fiona; Burke, Rosemary; Kadi, Nadia; Workman, Paul; Collins, Ian; van Montfort, Rob L M; Jones, Keith

    2016-05-26

    HSP70 is a molecular chaperone and a key component of the heat-shock response. Because of its proposed importance in oncology, this protein has become a popular target for drug discovery, efforts which have as yet brought little success. This study demonstrates that adenosine-derived HSP70 inhibitors potentially bind to the protein with a novel mechanism of action, the stabilization by desolvation of an intramolecular salt-bridge which induces a conformational change in the protein, leading to high affinity ligands. We also demonstrate that through the application of this mechanism, adenosine-derived HSP70 inhibitors can be optimized in a rational manner. PMID:27119979

  5. Characterization of nitrobenzylthioinosine binding to nucleoside transport sites selective for adenosine in rat brain

    SciTech Connect

    Geiger, J.D.; LaBella, F.S.; Nagy, J.I.

    1985-03-01

    Nucleoside transport sites in rat brain membrane preparations were labeled with (/sup 3/H)nitrobenzylthioinosine ((/sup 3/H) NBI), a potent inhibitor of nucleoside transport systems. The membranes contained a single class of very high affinity binding sites with K/sub D/ and B/sub max/ values of 0.06 nM and 147 fmol/mg of protein, respectively. The displacement of (/sup 3/H)NBI binding by various nucleosides, adenosine receptor agonists and antagonists, and known nucleoside transport inhibitors was examined. The K/sub i/ values (micromolar concentration) of (/sup 3/H)NBI displacement by the nucleosides tested were: adenosine, 3.0; inosine, 160; thymidine, 240; uridine, 390; guanosine, 460; and cytidine, 1000. These nucleosides displayed parallel displacement curves indicating their interaction with a common site labeled by (/sup 3/H)NBI. The nucleobases, hypoxanthine and adenine, exhibited K/sub i/ values of 220 and 3640 microM, respectively. Adenosine receptor agonists exhibited moderate affinities for the (/sup 3/H)NBI site, whereas the adenosine receptor antagonists, caffeine, theophylline, and enprofylline, were ineffective displacers. The K/sub i/ values for cyclohexyladenosine, (+)- and (-)-phenylisopropyladenosine, 2-chloroadenosine, and adenosine 5'-ethylcarboxamide were 0.8, 0.9, 2.6, 12, and 54 microM, respectively. These affinities and the rank order of potencies indicate that (/sup 3/H)NBI does not label any known class of adenosine receptors (i.e., A1, A2, and P). The K/sub i/ values of other nucleoside transport inhibitors were: nitrobenzylthioguanosine, 0.05 nM; dipyridamole, 16 nM; papaverine, 3 microM; and 2'-deoxyadenosine, 22 microM. These results indicate that (/sup 3/H)NBI binds to a nucleoside transporter in brain which specifically recognizes adenosine as its preferred endogenous substrate. This ligand may aid in the identification of CNS neural systems that selectively accumulate adenosine and thereby control adenosinergic function.

  6. L-nucleoside analogues as potential antimalarials that selectively target Plasmodium falciparum adenosine deaminase.

    PubMed

    Brown, D M; Netting, A G; Chun, B K; Choi, Y; Chu, C K; Gero, A M

    1999-01-01

    The L-stereoisomer analogues of D-coformycin selectively inhibited P. falciparum adenosine deaminase (ADA) in the picomolar range (L-isocoformycin, Ki 7 pM; L-coformycin, Ki 250 pM). While the L-nucleoside analogues, L-adenosine, 2,6-diamino-9-(L-ribofuranosyl)purine and 4-amino-1-(L-ribofuranosyl)pyrazolo[3,4-d]-pyrimidine were selectively deaminated by P. falciparum ADA, L-thioinosine and L-thioguanosine were not. This is the first example of 'non-physiological' L-nucleosides that serve as either substrates or inhibitors of malarial ADA and are not utilised by mammalian ADA.

  7. Dielectric spectra broadening as a signature for dipole-matrix interaction. III. Water in adenosine monophosphate/adenosine-5'-triphosphate solutions.

    PubMed

    Puzenko, Alexander; Levy, Evgeniya; Shendrik, Andrey; Talary, Mark S; Caduff, Andreas; Feldman, Yuri

    2012-11-21

    In this, the third part of our series on the dielectric spectrum symmetrical broadening of water, we consider the nucleotide aqueous solutions. Where in Parts I [E. Levy et al., J. Chem. Phys. 136, 114502 (2012)] and II [E. Levy et al., J. Chem. Phys. 136, 114503 (2012)], the dipole-dipole or ion-dipole interaction had a dominant feature, now the interplay between these two types of dipole-matrix interactions will be considered. We present the results of high frequency dielectric measurements of different concentrations of adenosine monophosphate/adenosine-5'-triphosphate aqueous solutions. We observed the Cole-Cole broadening of the main relaxation peak of the solvent in the solutions. Moreover, depending on the nucleotide concentration, we observed both types of dipole-matrix interaction. The 3D trajectory approach (described in detail in Part I) is applied in order to highlight the differences between the two types of interaction.

  8. Adenosine modulates hypoxia-induced responses in rat PC12 cells via the A2A receptor.

    PubMed

    Kobayashi, S; Conforti, L; Pun, R Y; Millhorn, D E

    1998-04-01

    1. The present study was undertaken to determine the role of adenosine in mediating the cellular responses to hypoxia in rat phaeochromocytoma (PC12) cells, an oxygen-sensitive clonal cell line. 2. Reverse transcriptase polymerase chain reaction studies revealed that PC12 cells express adenosine deaminase (the first catalysing enzyme of adenosine degradation) and the A2A and A2B adenosine receptors, but not the A1 or A3 adenosine receptors. 3. Whole-cell current- and voltage-clamp experiments showed that adenosine attenuated the hypoxia-induced membrane depolarization. The hypoxia-induced suppression of the voltage-sensitive potassium current (IK(V)) was markedly reduced by adenosine. Furthermore, extracellularly applied adenosine increased the peak amplitudes of IK(V) in a concentration-dependent manner. This increase was blocked by pretreatment not only with a non-specific adenosine receptor antagonist, 8-phenyltheophylline (8-PT), but also with a selective A2A receptor antagonist, ZM241385. 4. Ca2+ imaging studies using fura-2 acetoxymethyl ester (fura-2 AM) revealed that the increase in intracellular free Ca2+ during hypoxic exposure was attenuated significantly by adenosine. Voltage-clamp studies showed that adenosine inhibited the voltage-dependent Ca2+ currents (ICa) in a concentration-dependent fashion. This inhibition was also abolished by both 8-PT and ZM241385. 5. The modulation of both IK(V) and ICa by adenosine was prevented by intracellular application of an inhibitor of protein kinase A (PKA), PKA inhibitor fragment (6-22) amide. In addition, the effect of adenosine on either IK(V) or ICa was absent in PKA-deficient PC12 cells. 6. These results indicate that the modulatory effects of adenosine on the hypoxia-induced membrane responses of PC12 cells are likely to be mediated via activation of the A2A receptor, and that the PKA pathway is required for these modulatory actions. We propose that this modulation serves to regulate membrane excitability in

  9. Adenosine modulates hypoxia-induced responses in rat PC12 cells via the A2A receptor

    PubMed Central

    Kobayashi, Shuichi; Conforti, Laura; Pun, Raymund Y K; Millhorn, David E

    1998-01-01

    The present study was undertaken to determine the role of adenosine in mediating the cellular responses to hypoxia in rat phaeochromocytoma (PC12) cells, an oxygen-sensitive clonal cell line. Reverse transcriptase polymerase chain reaction studies revealed that PC12 cells express adenosine deaminase (the first catalysing enzyme of adenosine degradation) and the A2A and A2B adenosine receptors, but not the A1 or A3 adenosine receptors. Whole-cell current- and voltage-clamp experiments showed that adenosine attenuated the hypoxia-induced membrane depolarization. The hypoxia-induced suppression of the voltage-sensitive potassium current (IK(V)) was markedly reduced by adenosine. Furthermore, extracellularly applied adenosine increased the peak amplitudes of IK(V) in a concentration-dependent manner. This increase was blocked by pretreatment not only with a non-specific adenosine receptor antagonist, 8-phenyltheophylline (8-PT), but also with a selective A2A receptor antagonist, ZM241385. Ca2+ imaging studies using fura-2 acetoxymethyl ester (fura-2 AM) revealed that the increase in intracellular free Ca2+ during hypoxic exposure was attenuated significantly by adenosine. Voltage-clamp studies showed that adenosine inhibited the voltage-dependent Ca2+ currents (ICa) in a concentration-dependent fashion. This inhibition was also abolished by both 8-PT and ZM241385. The modulation of both IK(V) and ICa by adenosine was prevented by intracellular application of an inhibitor of protein kinase A (PKA), PKA inhibitor fragment (6–22) amide. In addition, the effect of adenosine on either IK(V) or ICa was absent in PKA-deficient PC12 cells. These results indicate that the modulatory effects of adenosine on the hypoxia-induced membrane responses of PC12 cells are likely to be mediated via activation of the A2A receptor, and that the PKA pathway is required for these modulatory actions. We propose that this modulation serves to regulate membrane excitability in PC12 cells and

  10. Dietary adenine controls adult lifespan via adenosine nucleotide biosynthesis and AMPK, and regulates the longevity benefit of caloric restriction

    PubMed Central

    Stenesen, Drew; Suh, Jae Myoung; Seo, Jin; Yu, Kweon; Lee, Kyu-Sun; Kim, Jong-Seok; Min, Kyung-Jin; Graff, Jonathan M.

    2012-01-01

    SUMMARY A common thread among conserved lifespan regulators lies within intertwined roles in metabolism and energy homeostasis. We show that heterozygous mutations of adenosine monophosphate (AMP) biosynthetic enzymes extend Drosophila lifespan. The lifespan benefit of these mutations depends upon increased AMP to adenosine triphosphate (ATP) and adenosine diphosphate (ADP) to ATP ratios and adenosine monophosphate-activated protein kinase (AMPK). Transgenic expression of AMPK in adult fat body or adult muscle, key metabolic tissues, extended lifespan, while AMPK RNAi reduced lifespan. Supplementing adenine, a substrate for AMP biosynthesis, to the diet of long-lived AMP biosynthesis mutants reversed lifespan extension. Remarkably, this simple change in diet also blocked the pro-longevity effects of dietary restriction. These data establish AMP biosynthesis, adenosine nucleotide ratios, and AMPK as determinants of adult lifespan, provide a mechanistic link between cellular anabolism and energy sensing pathways, and indicate that dietary adenine manipulations might alter metabolism to influence animal lifespan. PMID:23312286

  11. Metabolic challenge to glia activates an adenosine-mediated safety mechanism that promotes neuronal survival by delaying the onset of spreading depression waves.

    PubMed

    Canals, Santiago; Larrosa, Belén; Pintor, Jesús; Mena, María A; Herreras, Oscar

    2008-11-01

    In a model of glial-specific chemical anoxia, we have examined how astrocytes influence both synaptic transmission and the viability of hippocampal pyramidal neurons. This relationship was assessed using electrophysiological, pharmacological, and biochemical techniques in rat slices and cell cultures, and oxidative metabolism was selectively impaired in glial cells by exposure to the mitochondrial gliotoxin, fluoroacetate. We found that synaptic transmission was blocked shortly after inducing glial metabolic stress and peri-infarct-like spreading depression (SD) waves developed within 1 to 2 h of treatment. Neuronal electrogenesis was not affected until SD waves developed, thereafter decaying irreversibly. The blockage of synaptic transmission was totally reversed by A(1) adenosine receptor antagonists, unlike the development of SD waves, which appeared earlier under these conditions. Such blockage led to a marked reduction in the electrical viability of pyramidal neurons 1 h after gliotoxin treatment. Cell culture experiments confirmed that astrocytes indeed release adenosine. We interpret this early glial response as a novel safety mechanism that allocates metabolic resources to vital processes when the glia itself sense an energy shortage, thereby delaying or preventing entry into massive lethal ischemic-like depolarization. The implication of these results on the functional recovery of the penumbra regions after ischemic insults is discussed.

  12. Sperm motility and kinetics of dynein ATPase in astheno- and normozoospermic samples after stimulation with adenosine and its analogues.

    PubMed

    Romac, P; Zanić-Grubisić, T; Culić, O; Cvitković, P; Flogel, M

    1994-08-01

    We tested the effects of adenosine and 2-deoxyadenosine on the activation of human spermatozoa. In the asthenozoospermic group of patients adenosine produces an increase in sperm motility from 33.3 +/- 2.1% to 42.1 +/- 3.4%, progressive motility from 22.5 +/- 1.3% to 28.6 +/- 1.7% and forward progression rating from 2.1 +/- 0.2% to 2.8 +/- 0.1%. 2-Deoxyadenosine stimulated asthenozoospermic samples to a greater degree than adenosine. Sperm motility rose to 48.9 +/- 3.4%, progressive motility to 32.1 +/- 3.4% and forward progression rating to 3.0 +/- 0.1% following stimulation with 2-deoxy-adenosine. The kinetic parameters and basic characteristics of dynein ATPase were determined. The maximum activity of dynein ATPase, Vmax, was significantly different (P < 0.001) for asthenozoospermic and normozoospermic samples: 6.46 +/- 2.1 nmol Pi/mg/min and 16.99 +/- 3.7 nmol Pi/mg/min respectively. However, the enzyme affinity for ATP was not different. Stimulation of asthenozoospermic samples with adenosine and 2-deoxyadenosine caused an increase of Vmax (70-90% and 90-110% respectively) and no significant change in KM was observed. In order to block the nucleoside transporter and to eliminate the action of adenosine inside the cell, dipyridamole was used but the effects of adenosine were not neutralized. 5'-(N-ethylcarboxy-amido)-adenosine showed effects similar to those of adenosine, even when applied in 1 microM concentration. These results indicate that adenosine and its analogues stimulate sperm motility and activity of dynein ATPase, most probably via A2 receptors.

  13. Chaperoning of the A1-Adenosine Receptor by Endogenous Adenosine—An Extension of the Retaliatory Metabolite Concept*

    PubMed Central

    Kusek, Justyna; Yang, Qiong; Witek, Martin; Gruber, Christian W.; Nanoff, Christian; Freissmuth, Michael

    2015-01-01

    Cell-permeable orthosteric ligands can assist folding of G protein–coupled receptors in the endoplasmic reticulum (ER); this pharmacochaperoning translates into increased cell surface levels of receptors. Here we used a folding-defective mutant of human A1-adenosine receptor as a sensor to explore whether endogenously produced adenosine can exert a chaperoning effect. This A1-receptor-Y288 A was retained in the ER of stably transfected human embryonic kidney 293 cells but rapidly reached the plasma membrane in cells incubated with an A1 antagonist. This was phenocopied by raising intracellular adenosine levels with a combination of inhibitors of adenosine kinase, adenosine deaminase, and the equilibrative nucleoside transporter: mature receptors with complex glycosylation accumulated at the cell surface and bound to an A1-selective antagonist with an affinity indistinguishable from the wild-type A1 receptor. The effect of the inhibitor combination was specific, because it did not result in enhanced surface levels of two folding-defective human V2-vasopressin receptor mutants, which were susceptible to pharmacochaperoning by their cognate antagonist. Raising cellular adenosine levels by subjecting cells to hypoxia (5% O2) reproduced chaperoning by the inhibitor combination and enhanced surface expression of A1-receptor-Y288 A within 1 hour. These findings were recapitulated for the wild-type A1 receptor. Taken together, our observations document that endogenously formed adenosine can chaperone its cognate A1 receptor. This results in a positive feedback loop that has implications for the retaliatory metabolite concept of adenosine action: if chaperoning by intracellular adenosine results in elevated cell surface levels of A1 receptors, these cells will be more susceptible to extracellular adenosine and thus more likely to cope with metabolic distress. PMID:25354767

  14. Activation of adenosine A1 receptors reduces anxiety-like behavior during acute ethanol withdrawal (hangover) in mice.

    PubMed

    Prediger, Rui D S; da Silva, George E; Batista, Luciano C; Bittencourt, Alvorita L; Takahashi, Reinaldo N

    2006-10-01

    Elevated signs of anxiety are observed in both humans and rodents during withdrawal from chronic as well as acute ethanol exposure, and it represents an important motivational factor for ethanol relapse. Several reports have suggested the involvement of brain adenosine receptors in different actions produced by ethanol such as motor incoordination and hypnotic effects. In addition, we have recently demonstrated that adenosine A1 receptors modulate the anxiolytic-like effect induced by ethanol in mice. In the present study, we evaluated the potential of adenosine A1 and A2A receptor agonists in reducing the anxiety-like behavior during acute ethanol withdrawal (hangover) in mice. Animals received a single intraperitoneal administration of saline or ethanol (4 g/kg) and were tested in the elevated plus maze after an interval of 0.5-24 h. The results indicated that hangover-induced anxiety was most pronounced between 12 and 18 h after ethanol administration, as indicated by a significant reduction in the exploration of the open arms of the maze. At this time interval, ethanol was completely cleared. The acute administration of 'nonanxiolytic' doses of adenosine and the selective adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA), but not the adenosine A2A receptor agonist N6-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)ethyl]adenosine (DPMA), at the onset of peak withdrawal (18 h), reduced this anxiogenic-like response. In addition, the effect of CCPA on the anxiety-like behavior of ethanol hangover was reversed by pretreatment with the selective adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). These results reinforce the notion of the involvement of adenosine receptors in the anxiety-like responses and indicate the potential of adenosine A1 receptor agonists to reduce the anxiogenic effects during ethanol withdrawal.

  15. Analgesic effects of adenosine in syndrome X are counteracted by theophylline: a double-blind placebo-controlled study.

    PubMed

    Eriksson, B E; Sadigh, B; Svedenhag, J; Sylvén, C

    2000-01-01

    It has been proposed that adenosine mediates ischaemic pain in humans. Patients with cardiac Syndrome X are hypersensitive to potential pain stimuli, including adenosine. On the other hand, recent findings suggest that low-dose adenosine infusion may have analgesic effects. Our aim was to test two hypotheses: (1) that the analgesic effect of adenosine is peripheral in origin, and (2) that part of the hypersensitivity to pain of patients with cardiac Syndrome X results from a disturbed mechanism of adenosine analgesia. A total of 12 female Syndrome X patients and eight healthy age-matched female controls were studied in a randomized, double-blind and placebo-controlled study. Adenosine (70 microg/min) or placebo was infused into the forearm via an intra-arterial catheter. After 15 min of infusion, a tourniquet on the upper arm was inflated to 225 mmHg to ensure arterial occlusion. The patient then carried out dynamic handgrip work at 60 Hz. Pain or discomfort in the forearm was estimated continuously according to the Borg CR-10 scale. After the first test, theophylline was infused for 10 min intravenously at a dose of 5 mg/kg body weight. The ischaemic forearm test was then repeated. On a second occasion, the procedure was repeated with the opposite treatment (adenosine/placebo). Only six of 12 Syndrome X patients completed the protocol because of pain during the catheterization procedure or an inability to establish an intra-arterial line. The time to onset of pain in the working, ischaemic forearm was greater for subjects treated with adenosine than for those treated with placebo, both in those Syndrome X patients who tolerated catheterization (49+/-27 s compared with 32+/-18 s; P<0.03) and in healthy controls (40+/-19 s compared with 16+/-8 s; P<0.02). The time to maximum pain, limiting ischaemic work, was also greater with adenosine pretreatment both in Syndrome X patients (137+/-28 s compared with 106+/-28 s; P<0.03) and in healthy controls (109+/-31 compared

  16. Brain stem adenosine receptors modulate centrally mediated hypotensive responses in conscious rats: A review.

    PubMed

    Nassar, Noha N; Abdel-Rahman, Abdel A

    2015-05-01

    Adenosine is implicated in the modulation of cardiovascular responses either at the peripheral or at central level in experimental animals. However, there are no dedicated reviews on the involvement of adenosine in mediating the hypotensive response of centrally administered clonidine in general and specifically in aortically barodenervated rats (ABD). The conscious ABD rat model exhibits surgically induced baroreflex dysfunction and exaggerated hypotensive response, compared with conscious sham-operated (SO) rats. The current review focuses on, the role of adenosine receptors in blood pressure (BP) regulation and their possible crosstalk with other receptors e.g. imidazoline (I1) and alpha (α2A) adrenergic receptor (AR). The former receptor is a molecular target for clonidine, whose hypotensive effect is enhanced approx. 3-fold in conscious ABD rats. We also discussed how the balance between the brain stem adenosine A1 and A2A receptors is regulated by baroreceptors and how such balance influences the centrally mediated hypotensive responses. The use of the ABD rat model yielded insight into the downstream signaling cascades following clonidine-evoked hypotension in a surgical model of baroreflex dysfunction. PMID:26257930

  17. Role of endogenous adenosine as a modulator of the renin response to salt restriction.

    PubMed

    Kuan, C J; Wells, J N; Jackson, E K

    1987-01-01

    Numerous studies indicate that exogenous adenosine can inhibit renin release. However, the hypothesis that endogenous adenosine functions to restrain the renin response to physiological and/or pharmacological stimuli remains untested. To address this hypothesis, we examined the effects of a novel adenosine receptor antagonist, 1,3-dipropyl-8-para-sulfophenylxanthine (DPSPX), on renin release in rats on a normal versus a low salt diet. DPSPX did not affect renal blood flow, glomerular filtration rate, filtration fraction, urine volume, or sodium excretion in rats on either a normal or low salt diet. In contrast, in rats on a low salt diet, DPSPX significantly increased arterial and renal venous plasma renin activity and the gradient of plasma renin activity across the kidney. DPSPX did not alter these indices of renin release in rats on a normal salt diet. These data support the hypothesis that endogenous adenosine functions to restrain the renin response to salt depletion. Finally, if these findings are applicable to man, caffeine consumption could account for the variable antihypertensive effect of a low salt diet. PMID:3330576

  18. Purine nucleoside metabolism in the erythrocytes of patients with adenosine deaminase deficiency and severe combined immunodeficiency.

    PubMed Central

    Agarwal, R P; Crabtree, G W; Parks, R E; Nelson, J A; Keightley, R; Parkman, R; Rosen, F S; Stern, R C; Polmar, S H

    1976-01-01

    Deficiency of erythrocytic and lymphocytic adenosine deaminase (ADA) occurs in some patients with severe combined immunodeficiency disease (SCID). SCID with ADA deficiency is inherited as an autosomal recessive trait. ADA is markedly reduced or undetectable in affected patients (homozygotes), and approximately one-half normal levels are found in individuals heterozygous for ADA deficiency. The metabolism of purine nucleosides was studied in erythrocytes from normal individuals, four ADA-deficiency patients, and two heterozygous individuals. ADA deficiency in intake erythrocytes was confirmed by a very sensitive ammonia-liberation technique. Erythrocytic ADA activity in three heterozygous individuals (0.07,0.08, and 0.14 mumolar units/ml of packed cells) was between that of the four normal controls (0.20-0.37 mumol/ml) and the ADA-deficient patients (no activity). In vitro, adenosine was incorporated principally into IMP in the heterozygous and normal individuals but into the adenosine nucleotides in the ADa-deficient patients. Coformycin (3-beta-D-ribofuranosyl-6,7,8-trihydroimidazo[4,5-4] [1,3] diazepin-8 (R)-ol), a potent inhibitor of ADA, made possible incorporation of adenosine nucleotides in the ADA-deficient patients... PMID:947948

  19. Gestational Diabetes Reduces Adenosine Transport in Human Placental Microvascular Endothelium, an Effect Reversed by Insulin

    PubMed Central

    Salomón, Carlos; Westermeier, Francisco; Puebla, Carlos; Arroyo, Pablo; Guzmán-Gutiérrez, Enrique; Pardo, Fabián; Leiva, Andrea; Casanello, Paola; Sobrevia, Luis

    2012-01-01

    Gestational diabetes mellitus (GDM) courses with increased fetal plasma adenosine concentration and reduced adenosine transport in placental macrovascular endothelium. Since insulin modulates human equilibrative nucleoside transporters (hENTs) expression/activity, we hypothesize that GDM will alter hENT2-mediated transport in human placental microvascular endothelium (hPMEC), and that insulin will restore GDM to a normal phenotype involving insulin receptors A (IR-A) and B (IR-B). GDM effect on hENTs expression and transport activity, and IR-A/IR-B expression and associated cell signalling cascades (p42/44 mitogen-activated protein kinases (p42/44mapk) and Akt) role in hPMEC primary cultures was assayed. GDM associates with elevated umbilical whole and vein, but not arteries blood adenosine, and reduced hENTs adenosine transport and expression. IR-A/IR-B mRNA expression and p42/44mapk/Akt ratios (‘metabolic phenotype’) were lower in GDM. Insulin reversed GDM-reduced hENT2 expression/activity, IR-A/IR-B mRNA expression and p42/44mapk/Akt ratios to normal pregnancies (‘mitogenic phenotype’). It is suggested that insulin effects required IR-A and IR-B expression leading to differential modulation of signalling pathways restoring GDM-metabolic to a normal-mitogenic like phenotype. Insulin could be acting as protecting factor for placental microvascular endothelial dysfunction in GDM. PMID:22808198

  20. Theory of Polymer Entrapped Enzyme Ultramicroelectrodes: Application to Glucose and Adenosine Triphosphate Detection

    PubMed Central

    Kottke, Peter A.; Kranz, Christine; Kwon, Yong Koo; Masson, Jean-Francois; Mizaikoff, Boris; Fedorov, Andrei G.

    2010-01-01

    We validate, by comparison with experimental data, a theoretical description of the amperometric response of microbiosensors formed via enzyme entrapment. The utility of the theory is further illustrated with two relevant examples supported by experiments: (1) quantitative detection of glucose and (2) quantitative detection of adenosine triphosphate (ATP). PMID:20445817

  1. Adenosine A2A receptor antagonists: blockade of adenosinergic effects and T regulatory cells

    PubMed Central

    Sitkovsky, M; Lukashev, D; Deaglio, S; Dwyer, K; Robson, S C; Ohta, A

    2008-01-01

    The intensity and duration of host responses are determined by protective mechanisms that control tissue injury by dampening down inflammation. Adenosine generation and consequent effects, mediated via A2A adenosine receptors (A2AR) on effector cells, play a critical role in the pathophysiological modulation of these responses in vivo. Adenosine is both released by hypoxic cells/tissues and is also generated from extracellular nucleotides by ecto-enzymes e.g. CD39 (ENTPD1) and CD73 that are expressed by the vasculature and immune cells, in particular by T regulatory cell. In general, these adenosinergic mechanisms minimize the extent of collateral damage to host tissues during the course of inflammatory reactions. However, induction of suppressive pathways might also cause escape of pathogens and permit dissemination. In addition, adenosinergic responses may inhibit immune responses while enhancing vascular angiogenic responses to malignant cells that promote tumor growth. Novel drugs that block A2AR-adenosinergic effects and/or adenosine generation have the potential to boost pathogen destruction and to selectively destroy malignant tissues. In the latter instance, future treatment modalities might include novel ‘anti-adenosinergic' approaches that augment immune clearance of malignant cells and block permissive angiogenesis. This review addresses several possible pharmacological modalities to block adenosinergic pathways and speculates on their future application together with impacts on human disease. PMID:18311159

  2. Phenylephrine stimulated breakdown of phosphoinositides in brown adipocytes is attenuated by adenosine

    SciTech Connect

    Schimmel, R.J.

    1986-03-01

    Selective activation of alpha adrenergic receptors on brown adipocytes brings about increased mitochondrial respiration. This response is associated with a rapid breakdown of phosphoinositides in the plasma membrane. The authors have shown that respiration increased by alpha receptor activation can be inhibited by adenosine but the mechanisms underlying this effect are unknown. The present study probes the possibility that adenosine inhibition of alpha receptor stimulated respiration is secondary to an inhibition of stimulated breakdown of inositol phospholipids. Phospholipids were labeled with (/sup 32/P) by incubation with (/sup 32/P)-Pi for up to four hours. Phenylephrine and other ligands were then added and the radioactivity present in individual lipids determined following their resolution by thin layer chromatography. Addition of 2-chloroadenosine or phenylisopropyl adenosine, but not 2',5'-dideoxyadenosine, inhibited phenylephrine promoted breakdown of phosphoinositides. The dose response relation for this effect was similar to that for attenuation of stimulated respiration. This finding demonstrates adenosine inhibition of a phospholipase in brown fat cells and suggests the possibility that breakdown of inositol phospholipids is a critical control site for stimulation and attenuation of respiration.

  3. Unexpected Discovery of Dichloroacetate Derived Adenosine Triphosphate Competitors Targeting Pyruvate Dehydrogenase Kinase To Inhibit Cancer Proliferation.

    PubMed

    Zhang, Shao-Lin; Hu, Xiaohui; Zhang, Wen; Tam, Kin Yip

    2016-04-14

    Pyruvate dehydrogenase kinases (PDKs) have recently emerged as an attractive target for cancer therapy. Herein, we prepared a series of compounds derived from dichloroacetate (DCA) which inhibited cancer cells proliferation. For the first time, we have successfully developed DCA derived inhibitors that preferentially bind to the adenosine triphosphate (ATP) pocket of PDK isoform 1 (PDK1).

  4. Endogenous adenosine A3 receptor activation selectively alleviates persistent pain states.

    PubMed

    Little, Joshua W; Ford, Amanda; Symons-Liguori, Ashley M; Chen, Zhoumou; Janes, Kali; Doyle, Timothy; Xie, Jennifer; Luongo, Livio; Tosh, Dillip K; Maione, Sabatino; Bannister, Kirsty; Dickenson, Anthony H; Vanderah, Todd W; Porreca, Frank; Jacobson, Kenneth A; Salvemini, Daniela

    2015-01-01

    Chronic pain is a global burden that promotes disability and unnecessary suffering. To date, efficacious treatment of chronic pain has not been achieved. Thus, new therapeutic targets are needed. Here, we demonstrate that increasing endogenous adenosine levels through selective adenosine kinase inhibition produces powerful analgesic effects in rodent models of experimental neuropathic pain through the A3 adenosine receptor (A3AR, now known as ADORA3) signalling pathway. Similar results were obtained by the administration of a novel and highly selective A3AR agonist. These effects were prevented by blockade of spinal and supraspinal A3AR, lost in A3AR knock-out mice, and independent of opioid and endocannabinoid mechanisms. A3AR activation also relieved non-evoked spontaneous pain behaviours without promoting analgesic tolerance or inherent reward. Further examination revealed that A3AR activation reduced spinal cord pain processing by decreasing the excitability of spinal wide dynamic range neurons and producing supraspinal inhibition of spinal nociception through activation of serotonergic and noradrenergic bulbospinal circuits. Critically, engaging the A3AR mechanism did not alter nociceptive thresholds in non-neuropathy animals and therefore produced selective alleviation of persistent neuropathic pain states. These studies reveal A3AR activation by adenosine as an endogenous anti-nociceptive pathway and support the development of A3AR agonists as novel therapeutics to treat chronic pain. PMID:25414036

  5. Dynamic Regulation of the Adenosine Kinase Gene during Early Postnatal Brain Development and Maturation

    PubMed Central

    Kiese, Katharina; Jablonski, Janos; Boison, Detlev; Kobow, Katja

    2016-01-01

    The ubiquitous metabolic intermediary and nucleoside adenosine is a “master regulator” in all living systems. Under baseline conditions adenosine kinase (ADK) is the primary enzyme for the metabolic clearance of adenosine. By regulating the availability of adenosine, ADK is a critical upstream regulator of complex homeostatic and metabolic networks. Not surprisingly, ADK dysfunction is involved in several pathologies, including diabetes, epilepsy, and cancer. ADK protein exists in the two isoforms nuclear ADK-L, and cytoplasmic ADK-S, which are subject to dynamic expression changes during brain development and in response to brain injury; however, gene expression changes of the Adk gene as well as regulatory mechanisms that direct the cell-type and isoform specific expression of ADK have never been investigated. Here we analyzed potential gene regulatory mechanisms that may influence Adk expression including DNA promoter methylation, histone modifications and transcription factor binding. Our data suggest binding of transcription factor SP1 to the Adk promoter influences the regulation of Adk expression. PMID:27812320

  6. Adenosine Receptor Blockade by Caffeine Inhibits Carotid Sinus Nerve Chemosensory Activity in Chronic Intermittent Hypoxic Animals.

    PubMed

    Sacramento, J F; Gonzalez, C; Gonzalez-Martin, M C; Conde, S V

    2015-01-01

    Adenosine is a key excitatory neurotransmitter at the synapse between O(2)-sensing chemoreceptor cells-carotid sinus nerve (CSN) endings in the carotid body (CB). Herein, we have investigated the significance of adenosine, through the blockade of its receptors with caffeine, on the CB hypoxic sensitization induced by chronic intermittent hypoxia (CIH) in the rat. CIH animals were obtained by submitting rats during 15 days from 8:00 to 16:00 to 10 %O(2) for 40 s and 20 % O(2) for 80 s (i.e., 30 episodes/h). Caffeine (1 mM) was tested in spontaneous and 5 %O(2) evoked-CSN chemosensory activity in normoxic and CIH animals. CIH decreased basal spontaneous activity but increased significantly CSN activity evoked by acute hypoxia. Caffeine did not modify basal spontaneous activity in normoxic rats, but decreased significantly by 47.83 % basal activity in CIH animals. In addition, acute application of caffeine decreased 49.31 % and 56.01 % the acute hypoxic response in normoxic and CIH animals, respectively. We demonstrate that adenosine contributes to fix CSN basal activity during CIH, being also involved in hypoxic CB chemotransduction. It is concluded that adenosine participates in CB sensitization during CIH. PMID:26303475

  7. Pyrazolo Derivatives as Potent Adenosine Receptor Antagonists: An Overview on the Structure-Activity Relationships

    PubMed Central

    Cheong, Siew Lee; Venkatesan, Gopalakrishnan; Paira, Priyankar; Jothibasu, Ramasamy; Mandel, Alexander Laurence; Federico, Stephanie; Spalluto, Giampiero; Pastorin, Giorgia

    2011-01-01

    In the past few decades, medicinal chemistry research towards potent and selective antagonists of human adenosine receptors (namely, A1, A2A, A2B, and A3) has been evolving rapidly. These antagonists are deemed therapeutically beneficial in several pathological conditions including neurological and renal disorders, cancer, inflammation, and glaucoma. Up to this point, many classes of compounds have been successfully synthesized and identified as potent human adenosine receptor antagonists. In this paper, an overview of the structure-activity relationship (SAR) profiles of promising nonxanthine pyrazolo derivatives is reported and discussed. We have emphasized the SAR for some representative structures such as pyrazolo-[4,3-e]-1,2,4-triazolo-[1,5-c]pyrimidines; pyrazolo-[3,4-c] or -[4,3-c]quinolines; pyrazolo-[4,3-d]pyrimidinones; pyrazolo-[3,4-d]pyrimidines and pyrazolo-[1,5-a]pyridines. This overview not only clarifies the structural requirements deemed essential for affinity towards individual adenosine receptor subtypes, but it also sheds light on the rational design and optimization of existing structural templates to allow us to conceive new, more potent adenosine receptor antagonists. PMID:25954519

  8. Adenosine A2A Receptors Modulate Acute Injury and Neuroinflammation in Brain Ischemia

    PubMed Central

    Pedata, Felicita; Pugliese, Anna Maria; Coppi, Elisabetta; Dettori, Ilaria; Maraula, Giovanna; Cellai, Lucrezia; Melani, Alessia

    2014-01-01

    The extracellular concentration of adenosine in the brain increases dramatically during ischemia. Adenosine A2A receptor is expressed in neurons and glial cells and in inflammatory cells (lymphocytes and granulocytes). Recently, adenosine A2A receptor emerged as a potential therapeutic attractive target in ischemia. Ischemia is a multifactorial pathology characterized by different events evolving in the time. After ischemia the early massive increase of extracellular glutamate is followed by activation of resident immune cells, that is, microglia, and production or activation of inflammation mediators. Proinflammatory cytokines, which upregulate cell adhesion molecules, exert an important role in promoting recruitment of leukocytes that in turn promote expansion of the inflammatory response in ischemic tissue. Protracted neuroinflammation is now recognized as the predominant mechanism of secondary brain injury progression. A2A receptors present on central cells and on blood cells account for important effects depending on the time-related evolution of the pathological condition. Evidence suggests that A2A receptor antagonists provide early protection via centrally mediated control of excessive excitotoxicity, while A2A receptor agonists provide protracted protection by controlling massive blood cell infiltration in the hours and days after ischemia. Focus on inflammatory responses provides for adenosine A2A receptor agonists a wide therapeutic time-window of hours and even days after stroke. PMID:25165414

  9. John Montgomery's legacy: carbocyclic adenosine analogues as SAH hydrolase inhibitors with broad-spectrum antiviral activity.

    PubMed

    De Clercq, Erik

    2005-01-01

    Ever since the S-adenosylhomocysteine (AdoHcy, SAH) hydrolase was recognized as a pharmacological target for antiviral agents (J. A. Montgomery et al., J. Med. Chem. 25:626-629, 1982), an increasing number of adenosine, acyclic adenosine, and carbocyclic adenosine analogues have been described as potent SAH hydrolase inhibitors endowed with broad-spectrum antiviral activity. The antiviral activity spectrum of the SAH hydrolase inhibitors include pox-, rhabdo-, filo-, arena-, paramyxo-, reo-, and retroviruses. Among the most potent SAH hydrolase inhibitors and antiviral agents rank carbocyclic 3-deazaadenosine (C-c3 Ado), neplanocin A, 3-deazaneplanocin A, the 5'-nor derivatives of carbocyclic adenosine (C-Ado, aristeromycin), and the 2-halo (i.e., 2-fluoro) and 6'-R-alkyl (i.e., 6'-R-methyl) derivatives of neplanocin A. These compounds are particularly active against poxviruses (i.e., vaccinia virus), and rhabdoviruses (i.e., vesicular stomatitis virus). The in vivo efficacy of C-c3 Ado and 3-deazaneplanocin A has been established in mouse models for vaccinia virus, vesicular stomatitis virus, and Ebola virus. SAH hydrolase inhibitors such as C-c3Ado and 3-deazaneplanocin A should in thefirst place be considered for therapeutic (or prophylactic) use against poxvirus infections, including smallpox, and hemorrhagic fever virus infections such as Ebola. PMID:16438025

  10. Determination of adenosine triphosphate on marine particulates: synthesis of methods for use on OTEC samples

    SciTech Connect

    Jones, A.T.; Hartwig, E.O.

    1982-08-01

    Adenosine triphosphate (ATP) is an indicator of living biomass in marine particulates. This report details the method used by Lawrence Berkeley Laboratory to analyze particulate ATP in samples taken from oligotrophic, tropical ocean waters. It represents a synthesis of previously published methods.

  11. Determination of Adenosine Triphosphate on Marine Particulates:Synthesis of Methods for Use on OTEC Samples

    SciTech Connect

    Jones, Anthony T.; Hartwig, Eric O.

    1982-08-01

    Adenosine triphosphate (ATP) is an indicator of living biomass in marine particulates. This report details the method used by Lawrence Berkeley Laboratory to analyze particulate ATP in samples taken from oligotrophic, tropical ocean waters. It represents a synthesis of previously published methods.

  12. Induction of phosphodiesterase by cyclic adenosine 3':5'-monophosphate in differentiating Dictyostelium discoideum amoebae.

    PubMed

    Klein, C

    1975-09-25

    Cyclic adenosine 3':5'-monophosphate added to the starvation media of Dictyostelium discoideum amoebae induces both intracellular and extracellular phosphodiesterase activities of these cells. The induced enzyme activity appears several hours earlier than that in starved cells which have not been induced with cyclic nucleotide. In both cases, the appearance of enzyme is inhibited by cycloheximide, and actinomycin D, and daunomycin. The KmS for the extracellular enzyme(s) of nucleotide-induced and uninduced control cells are identical. The induction of enzyme activity seems specific for cyclic adenosine 3':5'-monophosphate since cyclic guanosine 3':5'-monophosphate, as well as other nucleotides, have no effect. No differences in the activity or excretion of either N-acetylglucosaminidase or the inhibitory of the extracellular phosphodiesterase are observed between cyclic adenosine 3':5'-monophosphate-induced and control cells. A direct activation of phosphodiesterase by cyclic adenosine 3':5'-monophosphate can be excluded, since the addition of this nucleotide to cell lysates has no effect on the enzyme activity. PMID:170256

  13. Caffeine exposure alters adenosine system and neurochemical markers during retinal development.

    PubMed

    Brito, Rafael; Pereira-Figueiredo, Danniel; Socodato, Renato; Paes-de-Carvalho, Roberto; Calaza, Karin C

    2016-08-01

    Evidence points to beneficial properties of caffeine in the adult central nervous system, but teratogenic effects have also been reported. Caffeine exerts most of its effects by antagonizing adenosine receptors, especially A1 and A2A subtypes. In this study, we evaluated the role of caffeine on the expression of components of the adenosinergic system in the developing avian retina and the impact of caffeine exposure upon specific markers for classical neurotransmitter systems. Caffeine exposure (5-30 mg/kg by in ovo injection) to 14-day-old chick embryos increased the expression of A1 receptors and concomitantly decreased A2A adenosine receptors expression after 48 h. Accordingly, caffeine (30 mg/kg) increased [(3) H]-8-cyclopentyl-1,3-dipropylxanthine (A1 antagonist) binding and reduced [(3) H]-ZM241385 (A2A antagonist) binding. The caffeine time-response curve demonstrated a reduction in A1 receptors 6 h after injection, but an increase after 18 and 24 h. In contrast, caffeine exposure increased the expression of A2A receptors from 18 and 24 h. Kinetic assays of [(3) H]-S-(4-nitrobenzyl)-6-thioinosine binding to the equilibrative adenosine transporter ENT1 revealed an increase in Bmax with no changes in Kd , an effect accompanied by an increase in adenosine uptake. Immunohistochemical analysis showed a decrease in retinal content of tyrosine hydroxylase, calbindin and choline acetyltransferase, but not Brn3a, after 48 h of caffeine injection. Furthermore, retinas exposed to caffeine had increased levels of phosphorylated extracellular signal-regulated kinase and cAMP-response element binding protein. Overall, we show an in vivo regulation of the adenosine system, extracellular signal-regulated kinase and cAMP-response element binding protein function and protein expression of specific neurotransmitter systems by caffeine in the developing retina. The beneficial or maleficent effects of caffeine have been demonstrated by the work of different studies. It

  14. Mechanisms involved in increased sensitivity to adenosine A(2A) receptor activation and hypoxia-induced vasodilatation in porcine coronary arteries.

    PubMed

    Hedegaard, Elise R; Nielsen, Berit D; Mogensen, Susie; Rembold, Christopher M; Frøbert, Ole; Simonsen, Ulf

    2014-01-15

    Hypoxia-induced coronary vasorelaxation is a compensatory mechanism increasing blood flow. We hypothesized that hypoxia shares pathways with adenosine and causes vasorelaxation through the adenosine A(2A) receptor and force suppression by increasing cAMP and phosphorylated heat shock protein (HSP)20. Adenosine receptors in porcine left anterior descending coronary arteries (LAD) were examined by RT-PCR and isometric tension recording in myographs. Vasorelaxation was induced by adenosine, 1% oxygen, or both in the absence or presence of ZM241385, an adenosine A(2A) receptor antagonist. cAMP was determined by ELISA and p-HSP20/HSP20 and p-MLC/MLC were determined by immunoblotting and densitometric analyses. In coronary arteries exposed to 1% oxygen, there was increased sensitivity to adenosine, the adenosine A2 selective agonist NECA, and the adenosine A(2A) selective receptor agonist CGS21680. ZM241385 shifted concentration-response curves for CGS21680 to the right, whereas the adenosine A1 antagonist DPCPX, the adenosine A2B receptor antagonist MRS1754 and the adenosine A3 receptor antagonist MRS1523 failed to reduce vasodilatation induced by CGS21680. 1% oxygen or adenosine increased cAMP accumulation and HSP20 phosphorylation without changing T850-MYPT1 and MLC phosphorylation. ZM241385 failed to change 1% oxygen-induced vasodilation, cAMP accumulation, HSP20 phosphorylation and MLC phosphorylation. The PKA inhibitor Rp-8-CPT-cAMPS significantly reduced vasorelaxation induced by 1% oxygen or CGS21680. Our findings suggest that the increased sensitivity to adenosine, NECA, and CGS21680 at 1% oxygen involves adenosine A(2A) receptors. Adenosine and 1% oxygen induce vasorelaxation in PGF2α-contracted porcine coronary arteries partly by force suppression caused by increased cAMP and phosphorylation of HSP20.

  15. Adenosine, caffeine, and performance: from cognitive neuroscience of sleep to sleep pharmacogenetics.

    PubMed

    Urry, Emily; Landolt, Hans-Peter

    2015-01-01

    An intricate interplay between circadian and sleep-wake homeostatic processes regulate cognitive performance on specific tasks, and individual differences in circadian preference and sleep pressure may contribute to individual differences in distinct neurocognitive functions. Attentional performance appears to be particularly sensitive to time of day modulations and the effects of sleep deprivation. Consistent with the notion that the neuromodulator, adenosine , plays an important role in regulating sleep pressure, pharmacologic and genetic data in animals and humans demonstrate that differences in adenosinergic tone affect sleepiness, arousal and vigilant attention in rested and sleep-deprived states. Caffeine--the most often consumed stimulant in the world--blocks adenosine receptors and normally attenuates the consequences of sleep deprivation on arousal, vigilance, and attention. Nevertheless, caffeine cannot substitute for sleep, and is virtually ineffective in mitigating the impact of severe sleep loss on higher-order cognitive functions. Thus, the available evidence suggests that adenosinergic mechanisms, in particular adenosine A2A receptor-mediated signal transduction, contribute to waking-induced impairments of attentional processes, whereas additional mechanisms must be involved in higher-order cognitive consequences of sleep deprivation. Future investigations should further clarify the exact types of cognitive processes affected by inappropriate sleep. This research will aid in the quest to better understand the role of different brain systems (e.g., adenosine and adenosine receptors) in regulating sleep, and sleep-related subjective state, and cognitive processes. Furthermore, it will provide more detail on the underlying mechanisms of the detrimental effects of extended wakefulness, as well as lead to the development of effective, evidence-based countermeasures against the health consequences of circadian misalignment and chronic sleep restriction.

  16. The adenosine receptor affinities and monoamine oxidase B inhibitory properties of sulfanylphthalimide analogues.

    PubMed

    Van der Walt, Mietha M; Terre'Blanche, Gisella; Petzer, Anél; Petzer, Jacobus P

    2015-04-01

    Based on a report that sulfanylphthalimides are highly potent monoamine oxidase (MAO) B selective inhibitors, the present study examines the adenosine receptor affinities and MAO-B inhibitory properties of a series of 4- and 5-sulfanylphthalimide analogues. Since adenosine antagonists (A1 and A2A subtypes) and MAO-B inhibitors are considered agents for the therapy of neurodegenerative disorders such as Parkinson's disease and Alzheimer's disease, dual-target-directed drugs that antagonize adenosine receptors and inhibit MAO-B may have enhanced therapeutic value. The results document that the sulfanylphthalimide analogues are selective for the adenosine A1 receptor over the A2A receptor subtype, with a number of compounds also possessing MAO-B inhibitory properties. Among the compounds evaluated, 5-[(4-methoxybenzyl)sulfanyl]phthalimide was found to possess the highest binding affinity to adenosine A1 receptors with a Ki value of 0.369 μM. This compound is reported to also inhibit MAO-B with an IC50 value of 0.020 μM. Such dual-target-directed compounds may act synergistic in the treatment of Parkinson's disease: antagonism of the A1 receptor may facilitate dopamine release, while MAO-B inhibition may reduce dopamine metabolism. Additionally, dual-target-directed compounds may find therapeutic value in Alzheimer's disease: antagonism of the A1 receptor may be beneficial in the treatment of cognitive dysfunction, while MAO-B inhibition may exhibit neuroprotective properties. In neurological diseases, such as Parkinson's disease and Alzheimer's disease, dual-target-directed drugs are expected to be advantageous over single-target treatments.

  17. Nucleus tractus solitarii A(2a) adenosine receptors inhibit cardiopulmonary chemoreflex control of sympathetic outputs.

    PubMed

    Minic, Zeljka; O'Leary, Donal S; Scislo, Tadeusz J

    2014-02-01

    Previously we have shown that stimulation of inhibitory A1 adenosine receptors located in the nucleus tractus solitarii (NTS) attenuates cardiopulmonary chemoreflex (CCR) evoked inhibition of renal, adrenal and lumbar sympathetic nerve activity and reflex decreases in arterial pressure and heart rate. Activation of facilitatory A2a adenosine receptors, which dominate over A1 receptors in the NTS, contrastingly alters baseline activity of regional sympathetic outputs: it decreases renal, increases adrenal and does not change lumbar nerve activity. Considering that NTS A2a receptors may facilitate release of inhibitory transmitters we hypothesized that A2a receptors will act in concert with A1 receptors differentially inhibiting regional sympathetic CCR responses (adrenal>lumbar>renal). In urethane/chloralose anesthetized rats (n=38) we compared regional sympathetic responses evoked by stimulation of the CCR with right atrial injections of serotonin 5HT3 receptor agonist, phenylbiguanide, (1-8μg/kg) before and after selective stimulation, blockade or combined blockade and stimulation of NTS A2a adenosine receptors (microinjections into the NTS of CGS-21680 0.2-20pmol/50nl, ZM-241385 40pmol/100nl or ZM-241385+CGS-21680, respectively). We found that stimulation of A2a adenosine receptors uniformly inhibited the regional sympathetic and hemodynamic reflex responses and this effect was abolished by the selective blockade of NTS A2a receptors. This indicates that A2a receptor triggered inhibition of CCR responses and the contrasting shifts in baseline sympathetic activity are mediated via different mechanisms. These data implicate that stimulation of NTS A2a receptors triggers unknown inhibitory mechanism(s) which in turn inhibit transmission in the CCR pathway when adenosine is released into the NTS during severe hypotension. PMID:24216055

  18. Role of nitric oxide in adenosine-induced vasodilation in humans

    NASA Technical Reports Server (NTRS)

    Costa, F.; Biaggioni, I.; Robertson, D. (Principal Investigator)

    1998-01-01

    Vasodilation is one of the most prominent effects of adenosine and one of the first to be recognized, but its mechanism of action is not completely understood. In particular, there is conflicting information about the potential contribution of endothelial factors. The purpose of this study was to explore the role of nitric oxide in the vasodilatory effect of adenosine. Forearm blood flow responses to intrabrachial adenosine infusion (125 microg/min) were assessed with venous occlusion plethysmography during intrabrachial infusion of saline or the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) (12.5 mg/min). Intrabrachial infusions of acetylcholine (50 microg/min) and nitroprusside (3 microg/min) were used as a positive and negative control, respectively. These doses were chosen to produce comparable levels of vasodilation. In a separate study, a second saline infusion was administered instead of L-NMMA to rule out time-related effects. As expected, pretreatment with L-NMMA reduced acetylcholine-induced vasodilation; 50 microg/min acetylcholine increased forearm blood flow by 150+/-43% and 51+/-12% during saline and L-NMMA infusion, respectively (P<.01, n=6). In contrast, L-NMMA did not affect the increase in forearm blood flow produced by 3 microg/min nitroprusside (165+/-30% and 248+/-41% during saline and L-NMMA, respectively) or adenosine (173+/-48% and 270+/-75% during saline and L-NMMA, respectively). On the basis of our observations, we conclude that adenosine-induced vasodilation is not mediated by nitric oxide in the human forearm.

  19. Modulation of audiogenic seizures by histamine and adenosine receptors in the inferior colliculus.

    PubMed

    Feng, H J; Faingold, C L

    2000-05-01

    Susceptibility to behaviorally similar audiogenic seizures (AGS) occurs genetically and is inducible during ethanol withdrawal (ETX). Comparisons between AGS mechanisms of genetically epilepsy-prone rats (GEPR-9s) and ethanol-withdrawn rats (ETX-Rs) are yielding information about general pathophysiological mechanisms of epileptogenesis. The inferior colliculus (IC) is the AGS initiation site. Excitatory amino acid (EAA) abnormalities in the IC are implicated in AGS, and histamine and adenosine receptor activation each reduce EAA release and inhibit several seizure types. Previous studies indicate that focal infusion of an adenosine receptor agonist into the IC blocked AGS in GEPR-9s, but the effects of adenosine receptor activation in the IC on AGS in ETX-Rs are unknown. The effects of histamine receptor activation on either form of AGS are also unexamined. The present study evaluated effects of histamine or a nonselective adenosine A(1) agonist, 2-chloroadenosine, on AGS by focal microinjection into the IC. Ethanol dependence and AGS susceptibility were induced in normal rats by intragastric ethanol. Histamine (40 or 60 nmol/side) significantly reduced AGS in GEPR-9s, but histamine in doses up to 120 nmol/side did not affect AGS in ETX-Rs. 2-Chloroadenosine (5 or 10 nmol/side) did not affect AGS in ETX-Rs, despite the effectiveness of lower doses of this agent in GEPR-9s reported previously. Thus, histamine and adenosine receptors in the IC modulate AGS of GEPR-9s, but do not modulate ETX-induced AGS. The reasons for this difference may involve the chronicity of AGS susceptibility in GEPR-9s, which may lead to more extensive neuromodulation as compensatory mechanisms to limit the seizures compared to the acute AGS of ETX-Rs.

  20. Adenosine decreases post-ischaemic cardiac TNF-alpha production: anti-inflammatory implications for preconditioning and transplantation.

    PubMed Central

    Meldrum, D R; Cain, B S; Cleveland, J C; Meng, X; Ayala, A; Banerjee, A; Harken, A H

    1997-01-01

    Tumour necrosis factor-alpha (TNF-alpha) is an autocrine contributor to myocardial dysfunction and cardiomyocyte death in ischaemia-reperfusion injury (I/R), sepsis, chronic heart failure and cardiac allograft rejection. Cardiac resident macrophages, infiltrating leucocytes, and cardiomyocytes themselves produce TNF-alpha. Although adenosine reduces macrophage TNF-alpha production and protects myocardium against I/R, it remains unknown whether I/R induces an increase in cardiac TNF-alpha in a crystalloid-perfused model (in the absence of blood), and, whether adenosine decreases cardiac TNF-alpha and protects function after I/R. To study this, isolated rat hearts were crystalloid-perfused using the Langendorff method and subjected to I/R, with or without adenosine pretreatment. Post-ischaemic cardiac TNF-alpha (enzyme-linked immunosorbent assay and bioassay) and function were determined (Langendorff). I/R increased cardiac TNF-alpha and impaired myocardial function. Adenosine decreased cardiac TNF-alpha and improved post-ischaemic functional recovery. This study demonstrates that: first, I/R induces an increase in cardiac tissue TNF-alpha in a crystalloid-perfused model: second, adenosine decreases cardiac TNF-alpha and improves post-ischaemic myocardial function; third, decreased cardiac TNF-alpha may represent a mechanism by which adenosine protects myocardium; and fourth, adenosine-induced suppression of cardiac TNF-alpha may provide an anti-inflammatory link to preconditioning and have implications for cardiac allograft preservation. PMID:9497488

  1. Electrochemical aptasensor for the detection of adenosine by using PdCu@MWCNTs-supported bienzymes as labels.

    PubMed

    Wu, Dan; Ren, Xiang; Hu, Lihua; Fan, Dawei; Zheng, Yang; Wei, Qin

    2015-12-15

    A highly sensitive electrochemical adenosine aptasensor was fabricated by covalently immobilizing 3'-NH2-terminated capture probe (SSDNA1) and thionine (TH) on Au-GS modified glassy carbon electrode. 3'-SH-terminated adenosine aptamer (SSDNA2) was adsorbed onto palladium/copper alloyed supported on MWCNTs (PdCu@MWCNTs)-conjugated multiple bienzymes, glucose oxidase (GOx), and horseradish peroxidase (HRP) (SSDNA2/PdCu@MWCNTs/HRP/GOx). Then, it was immobilized onto the electrode surface through the hybridization between the adenosine aptamer and the capture probe. The signal was amplified based on the gradual electrocatalytic reduction of GOx-generated hydrogen peroxide by the multiple HRP through the mediating ability of the loaded multiple TH. However, the peak current of TH decreased in the presence of adenosine because the interaction between adenosine and its aptamer made SSDNA2/PdCu@MWCNTs/HRP/GOx release from the modified electrode. Various experimental parameters have been optimized for the detection of adenosine and tests for selectivity, reproducibility and stability have also been performed. Under the optimal condition, the proposed aptasensor displayed a wide linear range (10-400 nM) with the low detection limit (2.5 nM), which has been applied in human serum samples with satisfactory results. Thus, the combination of Au-GS as a sensor platform and PdCu@MWCNTs/HRP/GOx as labels can be a promising amplification strategy for highly sensitive adenosine detection. PMID:26164010

  2. International Union of Basic and Clinical Pharmacology. LXXXI. Nomenclature and Classification of Adenosine Receptors—An Update

    PubMed Central

    IJzerman, Adriaan P.; Jacobson, Kenneth A.; Linden, Joel; Müller, Christa E.

    2011-01-01

    In the 10 years since our previous International Union of Basic and Clinical Pharmacology report on the nomenclature and classification of adenosine receptors, no developments have led to major changes in the recommendations. However, there have been so many other developments that an update is needed. The fact that the structure of one of the adenosine receptors has recently been solved has already led to new ways of in silico screening of ligands. The evidence that adenosine receptors can form homo- and heteromultimers has accumulated, but the functional significance of such complexes remains unclear. The availability of mice with genetic modification of all the adenosine receptors has led to a clarification of the functional roles of adenosine, and to excellent means to study the specificity of drugs. There are also interesting associations between disease and structural variants in one or more of the adenosine receptors. Several new selective agonists and antagonists have become available. They provide improved possibilities for receptor classification. There are also developments hinting at the usefulness of allosteric modulators. Many drugs targeting adenosine receptors are in clinical trials, but the established therapeutic use is still very limited. PMID:21303899

  3. Differences in adenosine A-1 and A-2 receptor density revealed by autoradiography in methylxanthine-sensitive and insensitive mice

    SciTech Connect

    Jarvis, M.F.; Williams, M.

    1988-07-01

    Two strains of inbred mice, CBA/J and SWR/J, have been identified which are, respectively, sensitive and insensitive to the behavioral and toxic effects of methylxanthines. Autoradiographic analyses of brain adenosine receptors were conducted with (/sup 3/H)CHA to label adenosine A-1 receptors and (/sup 3/H)NECA, in the presence of 50 nM CPA, to label adenosine A-2 receptors. For both mouse strains, adenosine A-1 receptors were most highly concentrated in the hippocampus and cerebellum whereas adenosine A-2 receptors were selectively localized in the striatum. CBA/J mice displayed a 30% greater density of adenosine A-1 receptors in the hippocampal CA-1 and CA-3 regions and in the cerebellum as compared to the SWR/J mice. The number of A-2 receptors (Bmax) was 40% greater in the striatum and olfactory tubercle of CBA/J as compared to SWR/J mice. No significant regional differences in A-1 or A-2 receptor affinities were observed between these inbred strains of mice. These results indicate that the differential sensitivity to methylxanthines between these mouse strains may reflect a genetically mediated difference in regional adenosine receptor densities.

  4. Activation of nicotinic ACh receptors with α4 subunits induces adenosine release at the rat carotid body

    PubMed Central

    Conde, Sílvia V; Monteiro, Emília C

    2006-01-01

    The effect of ACh on the release of adenosine was studied in rat whole carotid bodies, and the nicotinic ACh receptors involved in the stimulation of this release were characterized. ACh and nicotinic ACh receptor agonists, cytisine, DMPP and nicotine, caused a concentration-dependent increase in adenosine production during normoxia, with nicotine being more potent and efficient in stimulating adenosine release from rat CB than cytisine and DMPP. D-Tubocurarine, mecamylamine, DHβE and α-bungarotoxin, nicotinic ACh receptor antagonists, caused a concentration-dependent reduction in the release of adenosine evoked by hypoxia. The rank order of potency for nicotinic ACh receptor antagonists that inhibit adenosine release was DHβE>mecamylamine>D-tubocurarine>α-bungarotoxin. The effect of the endogenous agonist, ACh, which was mimicked by nicotine, was antagonized by DHβE, a selective nicotinic receptor antagonist. The ecto-5′-nucleotidase inhibitor AOPCP produces a 72% inhibition in the release of adenosine from CB evoked by nicotine. Taken together, these data indicate that ACh induced the production of adenosine, mainly from extracellular ATP catabolism at the CB through a mechanism that involves the activation of nicotinic receptors with α4 and β2 receptor subunits. PMID:16444287

  5. Binding induced colocalization activated hybridization chain reaction on the surface of magnetic nanobead for sensitive detection of adenosine.

    PubMed

    Feng, Chunjing; Hou, Zhun; Jiang, Wei; Sang, Lihong; Wang, Lei

    2016-12-15

    Herein, a sensitive and enzyme-free assay for adenosine detection has been developed on the basis of binding induced colocalization activated hybridization chain reaction (HCR) strategy on the surface of magnetic nanobead. First, the recognition probe was fabricated and divided into two parts: the Apt-1 that composed a part of adenosine aptamer and toehold domain, and the Apt-2 that consisted of another part of adenosine aptamer and branch migration domain. The Apt-1 was immobilized on a streptavidin-magnetic nanobead (streptavidin-MNBs) that played the roles of enrichment and separation. Then the recognition event of adenosine could bring the two parts of aptamer together and induce the colocalization of toehold domain and branch migration domain, which could serve as an integrated initiator to trigger the HCR, producing a long nicked double-stranded polymer. Finally, the intercalating dye SYBR Green I was inserted into the polymer, generating an enhanced fluorescence signal. In this strategy, the initiator was divided into two parts and could be suppressed effectively in the absence of adenosine. Utilizing the separated function, the spontaneous hybridization of H1 and H2 could be avoided, and a low background could be acquired. Moreover, through the double amplification of HCR and multimolecules binding of SYBR Green I, highly sensitive and enzyme-free detection were achieved. The detection limit for adenosine detection was 2.0×10(-7)mol/L, which was comparable or superior to the previous aptasensors. Importantly, adenosine analysis in human urines has been performed, and this strategy could significantly distinguish the adenosine content in normal human urines and cancer patient urines, suggesting that this proposed assay will become a reliable and sensitive adenosine detection method in early clinical diagnosis and medical research.

  6. GLUCOSE-INDUCED INTESTINAL VASODILATION VIA ADENOSINE A1 RECEPTORS REQUIRES NITRIC OXIDE BUT NOT K+ATP CHANNELS

    PubMed Central

    Matheson, Paul J.; Li, Na; Harris, Patrick D.; Zakaria, El Rasheid; Garrison, R. Neal

    2010-01-01

    INTRODUCTION Both nitric oxide (NO) and adenosine A1 receptor activation mediate microvascular vasodilation during intestinal glucose absorption. Our overall hypothesis is that ATP utilization during glucose absorption would increase adenosine metabolite release, which acts on adenosine A1 receptors to alter endothelial production of NO and/or activate ATP-dependent potassium channels (K+ATP) to dilate intestinal microvessels. METHODS Intravital videomicroscopy of the rat jejunum was used to record the vascular responses of inflow (termed 1A) arterioles and proximal (p3A) and distal (d3A) premucosal arterioles during exposure to isotonic glucose or mannitol solutions alone or in the presence of the selective nitric oxide synthase (NOS) inhibitor (L-NMMA), an adenosine A1 receptor antagonist (8-cyclopentyl-1,3-dipropylxanthine (DPCPX)), or a K+ATP channel inhibitor (glibenclamide). RESULTS As expected, glucose exposure caused rapid dilation of both p3A and d3A arterioles, while mannitol exposure had no effect on microvascular diameters. Adenosine A1 receptor blockade completely prevented glucose-induced dilation of the premucosal arterioles. NOS inhibition significantly blunted the glucose-induced vasodilation of the premucosal arterioles, but had little effect in the mannitol group. Simultaneous application of both the NOS inhibitor and the adenosine A1 receptor antagonist gave the same reduction in glucose-induced dilation of the premucosal arterioles as the adenosine A1 receptor antagonist alone. Blockade of K+ATP channels with glibenclamide did not attenuate glucose-induced vasodilation of the premucosal arterioles. CONCLUSIONS These data suggest that glucose-induced vasodilation of premucosal jejunal arterioles is mediated through adenosine A1 receptors, and NO at least partially mediates the adenosine A1 receptor-induced vasodilation. In addition, K+ATP channels are not involved in premucosal arteriolar vasodilation during intestinal glucose exposure. PMID

  7. Muscle A-Kinase Anchoring Protein-α is an Injury-Specific Signaling Scaffold Required for Neurotrophic- and Cyclic Adenosine Monophosphate-Mediated Survival.

    PubMed

    Wang, Yan; Cameron, Evan G; Li, Jinliang; Stiles, Travis L; Kritzer, Michael D; Lodhavia, Rahul; Hertz, Jonathan; Nguyen, Tu; Kapiloff, Michael S; Goldberg, Jeffrey L

    2015-12-01

    Neurotrophic factor and cAMP-dependent signaling promote the survival and neurite outgrowth of retinal ganglion cells (RGCs) after injury. However, the mechanisms conferring neuroprotection and neuroregeneration downstream to these signals are unclear. We now reveal that the scaffold protein muscle A-kinase anchoring protein-α (mAKAPα) is required for the survival and axon growth of cultured primary RGCs. Although genetic deletion of mAKAPα early in prenatal RGC development did not affect RGC survival into adulthood, nor promoted the death of RGCs in the uninjured adult retina, loss of mAKAPα in the adult increased RGC death after optic nerve crush. Importantly, mAKAPα was required for the neuroprotective effects of brain-derived neurotrophic factor and cyclic adenosine-monophosphate (cAMP) after injury. These results identify mAKAPα as a scaffold for signaling in the stressed neuron that is required for RGC neuroprotection after optic nerve injury. PMID:26844267

  8. Long-Term Expression of Human Adenosine Deaminase in Vascular Smooth Muscle Cells of Rats: A Model for Gene Therapy

    NASA Astrophysics Data System (ADS)

    Lynch, Carmel M.; Clowes, Monika M.; Osborne, William R. A.; Clowes, Alexander W.; Dusty Miller, A.

    1992-02-01

    Gene transfer into vascular smooth muscle cells in animals was examined by using recombinant retroviral vectors containing an Escherichia coli β-galactosidase gene or a human adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) gene. Direct gene transfer by infusion of virus into rat carotid arteries was not observed. However, gene transfer by infection of smooth muscle cells in culture and seeding of the transduced cells onto arteries that had been denuded of endothelial cells was successful. Potentially therapeutic levels of human adenosine deaminase activity were detected over 6 months of observation, indicating the utility of vascular smooth muscle cells for gene therapy in humans.

  9. Cyclic aristeromycin diphosphate ribose: a potent and poorly hydrolysable Ca(2+)-mobilising mimic of cyclic adenosine diphosphate ribose.

    PubMed

    Bailey, V C; Fortt, S M; Summerhill, R J; Galione, A; Potter, B V

    1996-02-01

    Cyclic aristeromycin diphosphate ribose, a carbocyclic analogue of cyclic adenosine diphosphate ribose, was synthesised using a chemo-enzymatic route involving activation of aristeromycin 5'-phosphate by diphenyl phosphochloridate. The calcium-releasing properties of this novel analogue were investigated in sea urchin egg homogenates. While cyclic aristeromycin diphosphate ribose has a calcium release profile similar to that of cyclic adenosine diphosphate ribose (EC50 values are 80 nM and 30 nM, respectively), it is degraded significantly more slowly (t1/2 values are 170 min and 15 min, respectively) and may, therefore, be a useful tool to investigate the activities of cyclic adenosine diphosphate ribose. PMID:8603694

  10. Biosynthesis of 9-beta-D-arabinofuranosyladenine: hydrogen exchange at C-2' and oxygen exchange at C-3' of adenosine

    SciTech Connect

    Suhadolnik, R.J.; Pornbanlualap, S.; Wu, J.M.; Baker, D.C.; Hebbler, A.K.

    1989-04-01

    The data presented here describe new findings related to the bioconversion of adenosine to 9-beta-D-arabinofuranosyladenine (ara-A) by Streptomyces antibioticus by in vivo investigations and with a partially purified enzyme. First, in double label in vivo experiments with (2'-18O)- and (U-14C)adenosine, the 18O:14C ratio of the ara-A isolated does not change appreciably, indicating a stereospecific inversion of the C-2' hydroxyl of adenosine to ara-A with retention of the 18O at C-2'. In experiments with (3'-18O)- and (U-14C)-adenosine, (U-14C)ara-A was isolated; however, the 18O at C-3' is below detection. The adenosine isolated from the RNA from both double label experiments has essentially the same ratio of 18O:14C. Second, an enzyme has been isolated and partially purified from extracts of S. antibioticus that catalyzes the conversion of adenosine, but not AMP, ADP, ATP, inosine, guanosine, or D-ribose, to ara-A. In a single label enzyme-catalyzed experiment with (U-14C)adenosine, there was a 9.9% conversion to (U-14C)ara-A; with (2'-3H)-adenosine, there was a 8.9% release of the C-2' tritium from (2'-3H)adenosine which was recovered as 3H2O. Third, the release of 3H as 3H2O from (2'-3H)adenosine was confirmed by incubations of the enzyme with 3H2O and adenosine. Ninety percent of the tritium incorporated into the D-arabinose of the isolated ara-A was in C-2 and 8% was in C-3. The enzyme-catalyzed conversion of adenosine to ara-A occurs without added cofactors, displays saturation kinetics, a pH optimum of 6.8, a Km of 8 X 10(-4) M, and an inhibition by heavy metal cations. The enzyme also catalyzes the stereospecific inversion of the C-2' hydroxyl of the nucleoside antibiotic, tubercidin to form 7-beta-D-arabinofuranosyl-4-aminopyrrolo(2,3-d)pyrimidine. The nucleoside antibiotic, sangivamycin, in which the C-5 hydrogen is replaced with a carboxamide group, is not a substrate.

  11. Cine and tagged cardiovascular magnetic resonance imaging in normal rat at 1.5 T: a rest and stress study

    PubMed Central

    Daire, Jean-Luc; Jacob, Jean-Pascal; Hyacinthe, Jean-Noel; Croisille, Pierre; Montet-Abou, Karin; Richter, Sophie; Botsikas, Diomidis; Lepetit-Coiffé, Matthieu; Morel, Denis; Vallée, Jean-Paul

    2008-01-01

    Background The purpose of this study was to measure regional contractile function in the normal rat using cardiac cine and tagged cardiovascular magnetic resonance (CMR) during incremental low doses of dobutamine and at rest. Methods Five rats were investigated for invasive left ventricle pressure measurements and five additional rats were imaged on a clinical 1.5 T MR system using a cine sequence (11–20 phases per cycle, 0.28/0.28/2 mm) and a C-SPAMM tag sequence (18–25 phases per cycle, 0.63/1.79/3 mm, tag spacing 1.25 mm). For each slice, wall thickening (WT) and circumferential strains (CS) were calculated at rest and at stress (2.5, 5 and 10 μg/min/kg of dobutamine). Results Good cine and tagged images were obtained in all the rats even at higher heart rate (300–440 bpm). Ejection fraction and left ventricular (LV) end-systolic volume showed significant changes after each dobutamine perfusion dose (p < 0.001). Tagged CMR had the capacity to resolve the CS transmural gradient and showed a significant increase of both WT and CS at stress compared to rest. Intra and interobserver study showed less variability for the tagged technique. In rats in which a LV catheter was placed, dobutamine produced a significant increase of heart rate, LV dP/dtmax and LV pressure significantly already at the lowest infusion dose. Conclusion Robust cardiac cine and tagging CMR measurements can be obtained in the rat under incremental dobutamine stress using a clinical 1.5 T MR scanner. PMID:18980685

  12. Effect of adenosine A(2A) receptor antagonists and L-DOPA on hydroxyl radical, glutamate and dopamine in the striatum of 6-OHDA-treated rats.

    PubMed

    Gołembiowska, Krystyna; Dziubina, Anna

    2012-02-01

    A(2A) adenosine receptor antagonists have been proposed as a new therapy of PD. Since oxidative stress plays an important role in the pathogenesis of PD, we studied the effect of the selective A(2A) adenosine receptor antagonists 8-(-3-chlorostyryl)caffeine (CSC) and 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385) on hydroxyl radical generation, and glutamate (GLU) and dopamine (DA) extracellular level using a microdialysis in the striatum of 6-OHDA-treated rats. CSC (1 mg/kg) and ZM 241385 (3 mg/kg) given repeatedly for 14 days decreased the production of hydroxyl radical and extracellular GLU level, both enhanced by prior 6-OHDA treatment in dialysates from the rat striatum. CSC and ZM 241385 did not affect DA and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA) extracellular levels in the striatum of 6-OHDA-treated rats. L-DOPA (6 mg/kg) given twice daily for two weeks in the presence of benserazide (3 mg/kg) decreased striatal hydroxyl radical and glutamate extracellular level in 6-OHDA-treated rats. At the same time, L-DOPA slightly but significantly increased the extracellular levels of DOPAC and HVA. A combined repeated administration of L-DOPA and CSC or ZM 241385 did not change the effect of L-DOPA on hydroxyl radical production and glutamate extracellular level in spite of an enhancement of extracellular DA level by CSC and elevation of extracellular level of DOPAC and HVA by ZM 241385. The data suggest that the 6-OHDA-induced damage of nigrostriatal DA-terminals is related to oxidative stress and excessive release of glutamate. Administration of L-DOPA in combination with CSC or ZM 241385, by restoring striatal DA-glutamate balance, suppressed 6-OHDA-induced overproduction of hydroxyl radical.

  13. Regulation of muscarinic acetylcholine receptor-mediated synaptic responses by adenosine receptors in the rat hippocampus.

    PubMed Central

    Morton, R A; Davies, C H

    1997-01-01

    1. Intracellular current clamp recordings were made from CA1 pyramidal neurones in rat hippocampal slices. Experiments were performed in the presence of ionotropic glutamate receptor antagonists and gamma-aminobutyric acid (GABA) receptor antagonists to block all fast excitatory and inhibitory synaptic transmission. A single stimulus, delivered extracellularly in the stratum oriens, caused a reduction in spike frequency adaptation in response to a depolarizing current step delivered 2 s after the stimulus. A 2- to 10-fold increase in stimulus intensity evoked a slow excitatory postsynaptic potential (EPSP) which was associated with a small increase in input resistance. The peak amplitude of the EPSP occurred approximately 2.5 s after the stimulus and its magnitude (up to 30 mV) and duration (10-50 s) increased with increasing stimulus intensity. 2. The slow EPSP was unaffected by the metabotropic glutamate receptor antagonist (+)-alpha-methyl-4-carboxyphenylglycine ((+)-MCPG; 1000 microM) but was greatly enhanced by the acetylcholinesterase inhibitor physostigmine (1-5 microM). Both the slow EPSP and the stimulus-evoked reduction in spike frequency adaptation were inhibited by the muscarinic acetylcholine receptor (mAChR) antagonist atropine (1-5 microM). These results are consistent with these effects being mediated by mAChRs. 3. Both the mAChR-mediated EPSP (EPSPm) and the associated reduction in spike frequency adaptation were reversibly depressed (up to 97%) by either adenosine (100 microM) or its non-hydrolysable analogue 2-chloroadenosine (CADO; 0.1-5.0 microM). These effects were often accompanied by postsynaptic hyperpolarization (up to 8 mV) and a reduction in input resistance (up to 11%). The selective adenosine A1 receptor agonists 2-chloro-N6-cyclopentyladenosine (CCPA; 0.1-0.4 microM) and R(-)N6-(2-phenylisopropyl)-adenosine (R-PIA; 1 microM) both depressed the EPSPm. In contrast, the adenosine A2A receptor agonist 2-p-(2-carboxyethyl)-phenethylamino-5

  14. Expression of calcitonin gene-related peptide, adenosine A2a receptor and adenosine A1 receptor in experiment rat migraine models

    PubMed Central

    LU, WENXIAN; LI, BIN; CHEN, JINBO; SU, YIPENG; DONG, XIAOMENG; SU, XINYANG; GAO, LIXIANG

    2016-01-01

    A migraine is a disabling neurovascular disorder characterized by a unilateral throbbing headache that lasts from 4 to 72 h. The headache is often accompanied by nausea, vomiting, phonophobia and photophobia, and may be worsened by physical exercise. The trigeminovascular system (TVS) is speculated to have an important role in migraines, although the pathophysiology of this disorder remains to be elucidated. Trigeminal ganglion (TG) and spinal trigeminal nucleus caudalis (TNC) are important components of the TVS. Several clinical cases have provided evidence for the involvement of the brainstem in migraine initiation. Electrical stimulation of the trigeminal ganglion (ESTG) in rats can activate TVS during a migraine attack. Calcitonin gene-related peptide (CGRP) is an important vasoactive compound produced following TVS activation. Numerous studies have revealed that adenosine and its receptors have an important role in pain transmission and regulation process. However, only a few studies have examined whether adenosine A2a receptor (A2aR) and adenosine A1 receptor (A1R) are involved in migraine and nociceptive pathways. In the present study, CGRP, A2aR and A1R expression levels were detected in the TG and TNC of ESTG models through reverse transcription-quantitative polymerase chain reaction and western blot analysis. Tianshu capsule (TSC), a type of Chinese medicine, was also used in the ESTG rat models to examine its influence on the three proteins. Results demonstrated that CGRP, A2aR and A1R mediated pain transmission and the regulation process during migraine and the expression of the three proteins was regulated by TSC. PMID:26998280

  15. Differential expression of adenosine A3 receptors controls adenosine A2A receptor-mediated inhibition of TLR responses in microglia.

    PubMed

    van der Putten, Céline; Zuiderwijk-Sick, Ella A; van Straalen, Linda; de Geus, Eveline D; Boven, Leonie A; Kondova, Ivanela; IJzerman, Ad P; Bajramovic, Jeffrey J

    2009-06-15

    Microglia activation is a prominent feature in many neuroinflammatory disorders. Unrestrained activation can generate a chronic inflammatory environment that might lead to neurodegeneration and autoimmunity. Extracellular adenosine modulates cellular activation through adenosine receptor (ADORA)-mediated signaling. There are four ADORA subtypes that can either increase (A(2A) and A(2B) receptors) or decrease (A(1) and A(3) receptors) intracellular cyclic AMP levels. The expression pattern of the subtypes thus orchestrates the cellular response to extracellular adenosine. We have investigated the expression of ADORA subtypes in unstimulated and TLR-activated primary rhesus monkey microglia. Activation induced an up-regulation of A(2A) and a down-regulation of A(3) receptor (A(3)R) levels. The altered ADORA-expression pattern sensitized microglia to A(2A) receptor (A(2A)R)-mediated inhibition of subsequent TLR-induced cytokine responses. By using combinations of subtype-specific agonists and antagonists, we revealed that in unstimulated microglia, A(2A)R-mediated inhibitory signaling was effectively counteracted by A(3)R-mediated signaling. In activated microglia, the decrease in A(3)R-mediated signaling sensitized them to A(2A)R-mediated inhibitory signaling. We report a differential, activation state-specific expression of ADORA in microglia and uncover a role for A(3)R as dynamically regulated suppressors of A(2A)R-mediated inhibition of TLR-induced responses. This would suggest exploration of combinations of A(2A)R agonists and A(3)R antagonists to dampen microglial activation during chronic neuroinflammatory conditions.

  16. Role of adenosine kinase in the control of Streptomyces differentiations: Loss of adenosine kinase suppresses sporulation and actinorhodin biosynthesis while inducing hyperproduction of undecylprodigiosin in Streptomyces lividans.

    PubMed

    Rajkarnikar, Arishma; Kwon, Hyung-Jin; Suh, Joo-Won

    2007-11-16

    Adenosine kinase (ADK) catalyses phosphorylation of adenosine (Ado) and generates adenosine monophosphate (AMP). ADK gene (adk(Sli), an ortholog of SCO2158) was disrupted in Streptomyces lividans by single crossover-mediated vector integration. The adk(Sli) disruption mutant (Deltaadk(Sli)) was devoid of sporulation and a plasmid copy of adk(Sli) restored sporulation ability in Deltaadk(Sli), thus indicating that loss of adk(Sli) abolishes sporulation in S. lividans. Ado supplementation strongly suppressed sporulation ability in S. lividans wild-type (wt), supporting that disruption of adk(Sli) resulted in Ado accumulation, which in turn suppressed sporulation. Cell-free experiments demonstrated that Deltaadk(Sli) lacked ADK activity and in vitro characterization confirms that adk(Sli) encodes ADK. The intracellular level of Ado was highly elevated while the AMP level was significantly reduced after loss of adk(Sli) while Deltaadk(Sli) displayed no significant derivation from wt in the levels of S-adenosylhomocysteine (SAH) and S-adenosylmethionine (SAM). Notably, Ado supplementation to wt lowered AMP content, albeit not to the level of Deltaadk(Sli), implying that the reduction of AMP level is partially forced by Ado accumulation in Deltaadk(Sli). In Deltaadk(Sli), actinorhodin (ACT) production was suppressed and undecylprodigiosin (RED) production was dramatically enhanced; however, Ado supplementation failed to exert this differential control. A promoter-probe assay verified repression of actII-orf4 and induction of redD in Deltaadk(Sli), substantiating that unknown metabolic shift(s) of ADK-deficiency evokes differential genetic control on secondary metabolism in S. lividans. The present study is the first report revealing the suppressive role of Ado in Streptomyces development and the differential regulatory function of ADK activity in Streptomyces secondary metabolism, although the underlying mechanism has yet to be elucidated.

  17. Lipopolysaccharide rapidly modifies adenosine receptor transcripts in murine and human macrophages: role of NF-kappaB in A(2A) adenosine receptor induction.

    PubMed

    Murphree, Lauren J; Sullivan, Gail W; Marshall, Melissa A; Linden, Joel

    2005-11-01

    The A(2A) adenosine receptor (A(2A)AR) mediates anti-inflammatory actions of adenosine in a variety of cell types. LPS (lipopolysaccharide) was reported to induce a small (<2-fold) increase in the expression of A(2A)AR mRNA in human monocytes and monocytic cell lines. We investigated the effects of LPS on the expression of adenosine receptor mRNAs in primary mouse IPMPhi (intraperitoneal macrophages), human macrophages and Wehi-3 cells. Treatment with 10 ng/ml LPS for 4 h produced a >100-fold increase in A(2A)AR mRNA. LPS-induced increases in mRNA for A(2A)AR and TNFalpha (tumour necrosis factor alpha) are reduced by 90% in IPMPhi pretreated with the NF-kappaB (nuclear factor kappaB) inhibitor, BAY 11-7082 {(E)3-[(4-methylphenyl)sulphonyl]-2-propenenitrile; 10 microM}. In Wehi-3 cells exposed to LPS, A(2A)AR and A(2B)AR transcripts are elevated by 290- and 10-fold respectively, the A(1)AR transcript is unchanged and the A(3)AR transcript is decreased by 67%. The induction of A(2A)AR mRNA by LPS is detectable after 1 h, reaches a peak at 6 h at 600 times control and remains elevated beyond 24 h. The ED50 (effective dose) of LPS is 2.3 ng/ml. A(2A)AR receptor number, measured by 125I-ZM241385 binding to whole cells, is undetectable in naïve cells and increases linearly at a rate of 23 receptors x cell(-1) x min(-1) to a B(max) of 348 fmol/mg (28000 receptors/cell) in 20 h. The increase in receptor number is correlated with an increase in the potency of an A(2A) agonist (4-{3-[6-amino-9-(5-ethylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-cyclohexanecarboxylic acid methyl ester; referred to as ATL146e) to stimulate cAMP in these cells. After LPS pretreatment, the potency of the A(2A) agonist, ATL146e, to reduce TNFalpha release from IPMPhi was increased by 200-fold. The results support the hypothesis that regulation of adenosine receptor expression, especially up-regulation of the A(2A)AR, is part of a delayed feedback mechanism

  18. Extracellular purine metabolism and signaling of CD73-derived adenosine in murine Treg and Teff cells.

    PubMed

    Romio, Michael; Reinbeck, Benjamin; Bongardt, Sabine; Hüls, Sandra; Burghoff, Sandra; Schrader, Jürgen

    2011-08-01

    CD73-derived adenosine acts as potent inhibitor of inflammation, and regulatory T cells (Treg) have been shown to express CD73 as a novel marker. This study explored the role of endogenously formed adenosine in modulating NF-κB activity and cytokine/chemokine release from murine Treg and effector T cells (Teff) including key enzymes/purinergic receptors of extracellular ATP catabolism. Stimulating murine splenocytes and CD4(+) T cells with anti-CD3/anti-CD28 significantly upregulated activated NF-κB in CD73(-/-) T cells (wild type: 4.36 ± 0.21; CD73(-/-): 6.58 ± 0.75; n = 4; P = 0.029). This was associated with an augmented release of proinflammatory cytokines IL-2, TNF-α, and IFN-γ. Similar changes were observed with the CD73 inhibitor APCP (50 μM) on NF-κB and IFN-γ in wild-type CD4(+) T-cells. Treatment of stimulated CD4(+) T-cells with adenosine (25 μM) potently reduced IFN-γ release which is mediated by adenosine A2a receptors (A2aR). AMP (50 μM) also reduced cytokine release which was not inhibited by APCP. In Teff, A2aR activation (CGS21680) potently inhibited the release of IL-1, IL-2, IL-3, IL-4, IL-12, IL-13, IFN-γ, TNF-α, granulocyte-macrophage colony-stimulating factor (GM-CSF), CCL3, and CCL4. However, in Treg, CGS21680 did not alter cytokine/chemokine release. In summary, CD73-derived adenosine tonically inhibits active NF-κB in CD4(+) T-cells, thereby modulating the release of a broad spectrum of proinflammatory cytokines and chemokines. Downregulation of P2X7 and upregulation of CD73 in Treg after antigenic stimulation may be an important mechanism to maintain the ability of Treg to generate immunosuppressive adenosine.

  19. 28 kDa adenosine-binding proteins of brain and other tissues.

    PubMed Central

    Ravid, K; Rosenthal, R A; Doctrow, S R; Lowenstein, J M

    1989-01-01

    Membranes prepared from calf brain were solubilized and chromatographed on a column containing 5'-amino-5'-deoxyadenosine covalently linked to agarose through the 5'-amino group. When the column was eluted with adenosine, a pure protein emerged with subunit molecular mass of 28 kDa. The protein was extracted from the membranes with sodium cholate, but not with 100 microM-adenosine or 0.5 M-NaCl. A similar 28 kDa protein was isolated from the soluble fraction of calf brain. The yield of membrane-bound and soluble 28 kDa protein per gram of tissue was about the same. The 28 kDa protein was also found in membrane and soluble fractions of rabbit heart, rat liver and vascular smooth muscle from calf aorta. The yield per gram of tissue fell into the order brain greater than heart approximately vascular smooth muscle greater than liver for the 28 kDa protein from the membrane fraction, and brain approximately heart greater than vascular smooth muscle greater than liver for the 28 kDa protein from the soluble fraction. Polyclonal antibodies to pure 28 kDa protein from calf brain membranes cross-reacted with the 28 kDa protein from calf brain soluble fraction and with 28 kDa proteins isolated from other tissues. The 28 kDa protein from calf brain membranes was also eluted from the affinity column by AMP and 2',5'-dideoxyadenosine, but at a concentration higher than that at which adenosine eluted the protein, but N6-(R-phenylisopropyl)adenosine, 5'-N-ethylcarboxamidoadenosine, ADP, ATP, GTP, NAD+, cyclic AMP and inosine failed to elute the protein at concentrations up to 1 mM. The 28 kDa protein from the soluble fraction was not eluted by 3 mM-AMP or 1 mM-N6-(R-phenylisopropyl)adenosine,-5'-N-ethylcarboxamidoadenosine or -cyclic AMP. Unexpectedly, the soluble 28 kDa protein was eluted by AMP in the presence of sodium cholate. Soluble 28 kDa protein from calf brain had a KD for adenosine of 12 microM. Membrane 28 kDa protein from calf brain had a KD of 14 microM in the

  20. Characterization of the binding of a novel nonxanthine adenosine antagonist radioligand, ( sup 3 H)CGS 15943, to multiple affinity states of the adenosine A1 receptor in the rat cortex

    SciTech Connect

    Jarvis, M.F.; Williams, M.; Do, U.H.; Sills, M.A. )

    1991-01-01

    The triazoloquinazoline CGS 15943 is the first reported nonxanthine adenosine antagonist that has high affinity for brain adenosine receptors. In the present study, the binding of (3H) CGS 15943 to recognition sites in rat cortical membranes was characterized. Saturation experiments revealed that (3H)CGS 15943 labeled a single class of recognition sites with high affinity and limited capacity. Competition studies revealed that the binding of (3H)CGS 15943 was consistent with the labeling of brain adenosine A1 receptors. Adenosine agonists inhibited 1 nM (3H)CGS 15943 binding with the following order of activity N6-cyclopentyladenosine (IC50 = 15 nM) greater than 2-chloroadenosine greater than (R)-N6-phenylisopropyladenosine greater than 5'-N6-ethylcarboxamidoadenosine greater than (S)N6-phenylisopropylad