Wyniki wyszukiwania

1

Adenosine-peptide conjugates as a novel class of protein kinase inhibitors

100%

Loog M., Uri A., Ek P., Jary J.

Cellular and Molecular Biology Letters

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1998

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tom 03

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nr 3

2

Rescue of sympathetic neurons from NGF-withdrawal apoptosis by adenosine

100%

Wakade A. R., Wakade T. D., Przywara D. A.

Cellular and Molecular Biology Letters

|

1999

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tom 04

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nr 3

3

Purinergic signaling in the pancreas and the therapeutic potential of ecto-nucleotidases in diabetes

86%

Cieslak M., Roszek K.

Acta Biochimica Polonica

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2014

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tom 61

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nr 4

4

Elevation of the adenylate pool in rat cardiomyocytes by S-adenosyl-L-methionine

86%

Smolenski R. T.

Acta Biochimica Polonica

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2000

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tom 47

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nr 4

Rapid resynthesis of the adenylate pool in cardiac myocytes is important for recovery of contractility and normal function of regulatory mechanisms in the heart. Adenosine and adenine are thought to be the most effective substrates for nucleotide synthesis, but the possibility of using other compounds has been studied very little in cardiomyocytes. In the present study, the effect of S-adenosyl-L-methionine (SAM) on the adenylate pool of isolated cardiomyocytes was investigated and compared to the effect of adenine and adenosine. Adult rat cardiomyocytes were isolated using the collagenase perfusion technique. The cells were incubated in the presence of adenine derivatives for 90 min followed by nucleotide determination by HPLC. The concentrations of adenine nucleotides expressed in nmol/mg of cell protein were initially 22.1 ± 1.4, 4.0 ± 0.3 and 0.70 ± 0.08 for ATP, ADP and AMP, respectively (n = 10, ± S.E.M.), and the total adenylate pool was 26.8 ± 1.6. In the presence of 1.25 mM SAM in the medium, the adenylate pool increased by 5.2 ± 0.4 nmol/mg of cell protein, but only if 1 mM ribose was additionally present in the medium. No changes were observed with SAM alone. A similar increase (by 4.9 ± 0.6 nmol/mg protein) was observed after incubation with 1.25 mM adenine plus 1 mM ribose, but no increase was observed if ribose was omitted. Adenosine at 0.1 or 1.25 mM concentrations also caused an increase in the adenylate pool (by 5.2 ± 1.0 and 5.2 ± 0.9 nmol/mg protein, respectively), which in contrast to the SAM or adenine was independent of the additional presence of ribose. Thus, S-adenosyl-L-methionine could be used as a precursor of the adenylate pool in cardiomyocytes, which is as efficient in increasing the adenylate pool after 90 min of incubation as adenosine or adenine. Nucleotide synthesis from SAM involves the formation of adenine as an intermediate with its subsequent incorporation by adenine phosphoribosyltransferase

5

Adenosine and hypoxanthine inhibits neurite outgrowth from human brain cells

86%

Korenevsky A. V., Duley J. A., Connolly G. P.

Cellular and Molecular Biology Letters

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1999

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tom 04

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nr 3

6

Dinucleoside polyphosphates - friend or foe ?

86%

McLennan A. G.

Cellular and Molecular Biology Letters

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1999

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tom 04

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nr 3

7

The relationship between constitutive ATP release and its extracellular metabolism in isolated rat kidney glomeruli

86%

Karczewska J., Martyniec L., Dzierzko G., Stepinski J., Angielski S.

Journal of Physiology and Pharmacology

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2007

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tom 58

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nr 2

ATP and adenosine are important extracellular regulators of glomerular functions. In this study, ATP release from glomeruli suspension and its extracellular metabolism were investigated. Basal extraglomerular ATP concentration (1nM) increased several fold during inhibition of ecto-ATPase activity, reflecting the basal ATP release rate. Mechanical perturbation increased the amounts of ATP released from glomeruli. ATP added to glomeruli was almost completely degraded within 20 minutes. In that time, AMP was the main product of extracellular ATP metabolism. Significant accumulation of AMP was observed after 5 min (194 ±16 µM) and 20 min (271 ±11 µM), whereas at the same time concentration of adenosine was only 10 µM. A competitive inhibitor of ecto-5-nucleotidase alpha-ß-methylene-ADP (AOPCP), decreased extraglomerular ATP and adenosine concentration by 80% and 50%, respectively. Similarly, AMP (100 µM) also markedly reduced extraglomerular ATP accumulation, whereas IMP, its deamination product, was not effective. P1, P5-diadenosine pentaphosphate (Ap5A) - an inhibitor of ecto-adenylate kinase prevented significantly the disappearance of ATP from extraglomerular media caused by AMP. These findings demonstrate that the decrease in extracellular ATP concentration observed after addition of AOPCP or AMP is caused by the presence of ecto-adenylate kinase activity in the glomeruli. The enzyme catalyses reversible reaction 2ADPATP+AMP, and a rise in the AMP concentration can lead to fall in ATP level. The present study provides evidence the extraglomerular accumulation of ATP reflects both release of ATP from glomeruli cells and its metabolism by ecto-enzymes. Our data suggest that AMP, produced from ATP in the Bowman's capsular space, might plays a dual role as a substrate for ecto-adenylate kinase and ecto-nucleotidase reactions being responsible for the regulation of intracapsular ATP and adenosine concentration. We conclude that AMP degrading and converting ecto-enzymes effectively determine the balance between ATP and adenosine concentration and thus the activation of P2 and/or adenosine receptors.

8

Structure and function of ecto-nucleotidases and their role in the ischemic brain

86%

Zimmermann H., Braun N., Heine P., Kegel B., Kohring K.

Cellular and Molecular Biology Letters

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1999

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tom 04

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nr 3

9

Molecular studies of 5'nucleotidases: past achievements and future potential

86%

Newby A. C.

Cellular and Molecular Biology Letters

|

1999

|

tom 04

|

nr 3

10

Association of ecto-5'-nucleotidase activity and erbB-2 receptor function

86%

Rosi F., Tabucchi A., Carlucci F., Marinello E., Cinci G., Zanoni L.

Cellular and Molecular Biology Letters

|

1999

|

tom 04

|

nr 3

11

The role of adenosine in preconditioning

86%

De Jong J. W., De Jonge R., Bradamante S.

Cellular and Molecular Biology Letters

|

1999

|

tom 04

|

nr 3

12

Methyl orange: a selective antagonist for pyrimidinoceptors

86%

Connolly G. P.

Cellular and Molecular Biology Letters

|

1999

|

tom 04

|

nr 3

13

Effect of VMAT2 inhibition on glutamate and adenosine in rat frontal cortex

72%

Kaminska K., Golembiowska K.

Acta Neurobiologiae Experimentalis

|

2013

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tom 73

|

nr 1

Our earlier studies showed that inhibition of VMAT2 caused depletion of dopamine in rat striatum accompanied with outflow of glutamate and production of hydroxyl radical. Inhibition of VMAT2 is observed in an early phase of Parkinson’s Disease (PD) as evidenced by PET studies in PD patients and in non-human primates. Recently it is observed that many neurons also release a classical transmitter other than the one with which they are usually associated. It is shown that neurons releasing monoamines can also release the excitatory transmitter glutamate. All neurons contain glutamate for its role in protein synthesis and metabolism, but they also express VGLUTs required for excitotoxic glutamate release. Moreover, it is also shown that several catecholamine cells such as VTA dopamine neurons are able corelease glutamate. Disturbed function of both, VMAT 2 and VGLUT may start catecholamine neurons degeneration that occurs at the early pre-clinical stage of PD. Accumulation of cytosolic dopamine may be neurotoxic for neurons through the generation of free radicals. Similarly, glutamate released from neurons or glial cells via GLT-1 transporter or cystine-glutamate exchanger or purinergic P2X7 receptor may stimulate glutamate receptors on various cells, induce increase in intracellular calcium which leads to excitotoxicity and generation of free radicals. ATP is required for packing of dopamine or glutamate in neuronal and glial vesicles and disturbed vesicular function results in ATP metabolism to adenosine in the presence of 5’-nucleotidase. In our study we tried to understand the early changes in dopamine synapses and glial cell responses which may provide insights on PD pathology. We injected animals with reserpine to inhibit vesicular transport and measured veratridine-evoked (100 µM) dopamine, glutamate and adenosine release using microdialysis in frontal cortex of freely moving rats. Extracellular dopamine, adenosine and glutamate were assayed by HPLC with electrochemical, fluorescenece and VIS detection. Reserpine at a single dose of 2.5 mg/kg increased veratridine-evoked glutamate release to 200% and adenosine release to 5 000% of baseline 20 h after administration. Reserpine at a dose of 0.25 mg/kg given repeatedly for 14 days increased evoked-glutamate release to maximum 210% and adenosine to 1 400% of baseline. At the same time veratridine-induced DA release was also markedly increased as compared to control animals. Veratridine-evoked glutamate and adenosine release were increased by 150 and 600% of baseline, respectively in intact rats. Obtained results indicate that under conditions of damaged vesicular transport there is significant overflow of glutamate and adenosine as well as increase in dopamine release in the rat frontal cortex. Marked increase in extracellular adenosine release may lead to activation of adenosine A2A receptors located in glutamate terminals or glial cells causing damage through induction of oxidative stress by glutamate or dopamine. Corelease of neurotransmitters and neuromodulators from neuronal or glial cells with disturbed vesicular transport may underline cortical pathology observed in PD.

14

Control of energy metabolism in the heart and endothelial cells

72%

Schrader J., Decking U. K. M., Stumpe T., Culic O.

Cellular and Molecular Biology Letters

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1999

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tom 04

|

nr 3

15

Cross-talk between the ATP and ADP nucleotide receptor signalling pathways in glioma C6 cells

72%

Czajkowski R., Baranska J.

Acta Biochimica Polonica

|

2002

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tom 49

|

nr 4

In this review we summarize the present status of our knowledge on the enzymes involved in the extracellular metabolism of nucleotides and the receptors involved in nucleotide signalling. We focus on the mechanism of the ATP and ADP signalling pathways in glioma C6, representative of the type of nonexcitable cells. In these cells, ATP acts on the P2Y2 receptor coupled to phospholipase C, whereas ADP on two distinct P2Y receptors: P2Y1 and P2Y12. The former is linked to phospholipase C and the latter is negatively coupled to adenylyl cyclase. The possible cross-talk between the ATP-, ADP- and adenosine-induced pathways, leading to simultaneous regulation of inositol 1,4,5-trisphosphate and cAMP mediated signalling, is discussed.

16

Raised plasma adenosine in chronic fatigue syndrome

72%

Duley J. A., Shobowale-Bakre E. M., Garrick P., Pratt D.

Cellular and Molecular Biology Letters

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1999

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tom 04

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nr 3

17

Adenosine as a metabolic regulator of tissue function: production of adenosine by cytoplasmic 5'-nucleotidases

72%

Borowiec A., Lechward K., Tkacz-Stachowska K., Skladanowski A. C.

Acta Biochimica Polonica

|

2006

|

tom 53

|

nr 2

Adenosine is a product of complete dephosphorylation of adenine nucleotides which takes place in various compartments of the cell. This nucleoside is a significant signal molecule engaged in regulation of physiology and modulation of the function of numerous cell types (i.e. neurons, platelets, neutrophils, mast cells and smooth muscle cells in bronchi and vasculature, myocytes etc.). As part a of purinergic signaling system, adenosine mediates neurotransmission, conduction, secretion, vasodilation, proliferation and cell death. Most of the effects of adenosine help to protect cells and tissues during stress conditions such as ischemia or anoxia. Adenosine receptors and nucleoside transporters are targets for potential drugs in many pathophysiological situations. The adenosine-producing system in vertebrates involves a cascade dephosphorylating ATP and ending with 5'-nucleotidase (EC 3.1.3.5) localized either on the membrane or inside the cell. In this paper the cytoplasmic variants of 5'-nucleotidase are broadly characterized as well as their clinical relevance. The role of AMP-selective 5'-nucleotidase (cN-I) in the heart, skeletal muscle and brain is highlighted. cN-I action is crucial during ischemia and important for the efficacy of some nucleoside-based drugs and in the regulation of the substrate pool for nucleic acids synthesis. Inhibitors used in studying the roles of cytoplasmic and membrane-bound 5'-nucleotidases are also described.

18

Responsiveness of renal glomeruli to adenosine in streptozotocin-induced diabetic rats dependent on hyperglycaemia level

72%

Szczepanska-Konkel M., Jankowski M., Stiepanov-Trzeciak A., Rudzik A., Pawelczyk T., Angielski S.

Journal of Physiology and Pharmacology

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2003

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tom 54

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nr 1

Glomerular filtration rate (GFR) in response to adenosine precursor, NAD, and glomeruli contractility in response to adenosine were evaluated in streptozotocin-induced diabetic rats with severe (blood glucose 27.8±1.2 mmol/L) and moderate hyperglycaemia (18.2±0.9 mmol/L) compared with nondiabetic (ND)-rats. In anaesthetised rats, basal GFR was greater in moderately diabetic rats compared with severely diabetic rats (p<0.05) and ND-rats (p<0.02). Intravenous infusion of 5 nmol·min-1·kg-1 NAD reduced GFR and renal plasma flow (RPF) in diabetic rats but had no effect on these parameters in ND-rats. Moreover, NAD-induced reduction of GFR and RPF was greater in rats with severe diabetes (41% and 30%, respectively) than in with moderate diabetes (25% and 26%, respectively). Theophylline (0.2 µmol·min-1·kg-1) abolished renal response to NAD. Isolated glomeruli contraction in response to adenosine, assessed by glomerular 3H-inulin space reduction, was lowered in moderately diabetic-group and enhanced in severely diabetic-group, compared with ND-group (p<0.05). Adenosine A1-receptor antagonist DPCPX inhibited adenosine-induced glomeruli contraction. This differential response of diabetic renal glomeruli to adenosine suggests that impaired glomerular contractility in response to adenosine could be responsible for hyperfiltration in moderate diabets, whereas, the increased adenosine-dependent contractility of glomeruli in severe diabetes may increase the risk of acute renal failure in this condition.

19

Hydrolytic cleavage of purine ribonucleosides by extracts of Aspergillus terricola

72%

Abu-Shady M. R., Elshafei A. M., El-Beih F. M., Mohamed L. A.

Acta Microbiologica Polonica

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1994

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tom 43

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nr 3-4

20

Kinetics of a nucleoside release from lactide-caprolactone and lactide-glycolide polymers in vitro

72%

Kryczka T., Grieb P., Bero M., Kasperczyk J., Dobrzynski P.

Acta Biochimica Polonica

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2000

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tom 47

|

nr 1

We assessed the rate of release of a model nucleoside (adenosine, 5%, w/w) from nine different lactide-glycolide or lactide-caprolactone polymers. The polymer discs were eluted every second day with an artificial cerebrospinal fluid at the elution rate roughly approximating the brain extracellular fluid formation rate. Adenosine in eluate samples was assayed by HPLC. Three polymers exhibited a relatively constant release of adenosine for over four weeks, resulting in micromolar concentrations of nucleoside in the eluate. This points to the neccessity of further development of polymers of this types as intracerebral nucleoside delivery systems for local treatment of brain tumors.

Ograniczanie wyników

Adenosine-peptide conjugates as a novel class of protein kinase inhibitors

Rescue of sympathetic neurons from NGF-withdrawal apoptosis by adenosine

Purinergic signaling in the pancreas and the therapeutic potential of ecto-nucleotidases in diabetes

Elevation of the adenylate pool in rat cardiomyocytes by S-adenosyl-L-methionine

Adenosine and hypoxanthine inhibits neurite outgrowth from human brain cells

Dinucleoside polyphosphates - friend or foe ?

The relationship between constitutive ATP release and its extracellular metabolism in isolated rat kidney glomeruli

Structure and function of ecto-nucleotidases and their role in the ischemic brain

Molecular studies of 5'nucleotidases: past achievements and future potential

Association of ecto-5'-nucleotidase activity and erbB-2 receptor function

The role of adenosine in preconditioning

Methyl orange: a selective antagonist for pyrimidinoceptors

Effect of VMAT2 inhibition on glutamate and adenosine in rat frontal cortex

Control of energy metabolism in the heart and endothelial cells

Cross-talk between the ATP and ADP nucleotide receptor signalling pathways in glioma C6 cells

Raised plasma adenosine in chronic fatigue syndrome

Adenosine as a metabolic regulator of tissue function: production of adenosine by cytoplasmic 5'-nucleotidases

Responsiveness of renal glomeruli to adenosine in streptozotocin-induced diabetic rats dependent on hyperglycaemia level

Hydrolytic cleavage of purine ribonucleosides by extracts of Aspergillus terricola

Kinetics of a nucleoside release from lactide-caprolactone and lactide-glycolide polymers in vitro