Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.4.4 (adenosine deaminase)
 5,136 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isolated, perfused guinea pig hearts were infused with intracoronary adenosine deaminase to investigate the contribution of endogenous adenosine to the coronary vasodilation of global myocardial hypoxia. Coronary perfusate pressure was held constant at 70 cmH2O throughout the experiment. We measured retrograde aortic inflow (assumed to equal total antegrade coronary flow) for 3-5 min of hypoxia before and 4 min after initiation of intracoronary adenosine deaminase infusion (4 U.g-1.min-1). In the absence of adenosine deaminase mild global hypoxia increased coronary perfusate flow 60%. In the presence of adenosine deaminase the response was limited to a 5% increment. Myocardial O2 consumption was significantly reduced during hypoxia in the presence of adenosine deaminase. In a second group of hearts, moderate global hypoxia increased coronary perfusate flow 125%. This was limited to a 53% increment in the presence of adenosine deaminase. Adenosine deaminase vehicle had no measurable effect on coronary perfusate flow responses to repeat mild hypoxia in a third group of hearts. We conclude that endogenous adenosine is singularly important in the coronary vasodilation of mild global myocardial hypoxia, but that other regulatory mechanisms might also contribute during moderate hypoxia.
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PMID:Coronary vasodilation during global myocardial hypoxia: effects of adenosine deaminase. 336 83

Adenosine deaminase activity was determined in paired samples of serum and synovial fluid taken from patients with rheumatoid arthritis (n = 12), reactive arthritis (n = 13), and osteoarthritis (n = 7), and the value of this investigation in the diagnosis of synovial swellings was assessed. Increased activity was found in the synovial fluid taken from patients with rheumatoid disease and reactive arthritis, though values were less raised in the latter. Synovial fluid taken from patients with osteoarthritis did not show significantly raised adenosine deaminase activity as compared with that of normal controls (n = 3).
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PMID:Serum and synovial fluid adenosine deaminase activity in patients with rheumatoid arthritis, osteoarthritis, and reactive arthritis. 338 70

The effects of adenosine and of some products of its metabolic degradation on lipolysis were studied in rat fat cells isolated from epididymal adipose tissue. Basal glycerol release was not affected by adenosine and by uric acid, but it was significantly increased by inosine (1-100 microM) and by hypoxanthine (10-100 microM). Adenosine was more effective than inosine in antagonizing the lipolytic response of fat cells to theophylline. Also hypoxanthine and uric acid exerted a very potent, noncompetitive antagonism towards theophylline. Norepinephrine-induced lipolysis was inhibited by adenosine, hypoxanthine and uric acid approximately to the same extent, while inosine was ineffective at this level. Adenosine deaminase (0.5 U/ml) increased basal as well as theophylline- and norepinephrine-induced lipolysis. Moreover, adenosine deaminase enhanced the lipolytic rate in cells incubated with low (0.1, 1 microM) and, to a lesser extent, with high (10, 100 microM) inosine concentrations. These results suggest that inosine is the adenosine metabolite that may accumulate in the incubation medium following fat cell treatment with adenosine deaminase, thus contributing to the stimulatory effects of this enzyme on lipolysis.
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PMID:A reexamination of the effects induced by adenosine and its degradation products on rat fat cell lipolysis. 340 Dec 55

Adenosine deaminase (ADA; adenosine aminohydrolase, EC 3.5.4.4) deficiency is one cause of the genetic disease severe combined immunodeficiency. To identify mutations responsible for ADA deficiency, we synthesized cDNAs to ADA mRNAs from two cell lines, GM2756 and GM2825A, derived from ADA-deficient immunodeficient patients. Sequence analysis of GM2756 cDNA clones revealed a different point mutation in each allele that causes amino acid changes of alanine to valine and arginine to histidine. One allele of GM2825A also has a point mutation that causes an alanine to valine substitution. The other allele of GM2825A was found to produce an mRNA in which exon 4 had been spliced out but had no other detrimental mutations. S1 nuclease mapping of GM2825A mRNAs showed equal abundance of the full-length ADA mRNA and the ADA mRNA that was missing exon 4. Several of the ADA cDNA clones extended 5' of the major initiation start site, indicating multiple start sites for ADA transcription. The point mutations in GM2756 and GM2825A and the absence of exon 4 in GM2825A appear to be directly responsible for the ADA deficiency. Comparison of a number of normal and mutant ADA cDNA sequences showed a number of changes in the third base of codons. These changes do not affect the amino acid sequence. Analyses of ADA cDNAs from different cell lines detected aberrant RNA species that either included intron 7 or excluded exon 7. Their presence is a result of aberrant splicing of pre-mRNAs and is not related to mutations that cause ADA deficiency.
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PMID:Mutations in the human adenosine deaminase gene that affect protein structure and RNA splicing. 347 10

Adenosine deaminase is a purine salvage enzyme that catalyzes the deamination of adenosine and deoxyadenosine. Deficiency of the enzyme activity is associated with T-cell and B-cell dysfunction. Mutant adenosine deaminase has been isolated from heterozygous and homozygous deficient lymphoblast cell lines with the aid of an affinity matrix consisting of coformycin (a potent inhibitor of the enzyme) as the affinity ligand, bound to 3,3'-iminobispropylamine-derivatized Sepharose. Routinely, 80-90% of adenosine deaminase in crude cell homogenates could be bound to the material. Adenosine deaminase was specifically eluted by enzyme inhibitors or less efficiently by high substrate concentrations. Protein preparations isolated from several different deficient cell lines were highly purified and exhibited molecular weights identical to wild-type adenosine deaminase. This method produces a protein that is suitable for structural studies.
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PMID:Isolation of mutant adenosine deaminase by coformycin affinity chromatography. 349 41

In the anterogradely perfused rat heart, physiological concentrations of insulin stimulated the rates and efficiencies of protein synthesis in both ventricles and atria. Half-maximal stimulation of ventricular protein synthesis was obtained at about 35 microU/ml. Glucose uptake and lactate release were also stimulated over this range of insulin concentrations. Adenosine deaminase increased protein synthesis rates in ventricles and atria in the presence of submaximally stimulating insulin concentrations (40 microU/ml) but had no effect in the absence of insulin or in the presence of maximally stimulating concentrations. The insulin sensitivities of glucose uptake and lactate release were also increased by adenosine deaminase. Adenosine may be a modulator of insulin sensitivity in the heart.
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PMID:Stimulation of protein synthesis, glucose uptake and lactate output by insulin and adenosine deaminase in the rat heart. 351 83

Adenosine deaminase and adenosine deaminase complexing protein have been localized in rabbit brain. Brains fixed in paraformaldehyde or in Clarke's solution were blocked coronally. Blocks from brains fixed in paraformaldehyde were either frozen in liquid nitrogen or embedded in paraffin. Tissue fixed in Clarke's solution was embedded in paraffin. Sections from each block were stained by the peroxidase-antiperoxidase method for adenosine deaminase or complexing protein using affinity-purified goat antibodies. Adenosine deaminase and complexing protein did not co-localize. Adenosine deaminase was detected in oligodendroglia and in endothelial cells lining blood vessels, whereas complexing protein was concentrated in neurons. The subcellular location and appearance of the peroxidase reaction product associated with individual cells was also quite distinctive. The cell bodies of adenosine deaminase-positive oligodendroglia were filled with intense deposits of peroxidase reaction product. In contrast to oligodendroglia, the reaction product associated with most neurons stained for complexing protein was concentrated in granular-appearing cytoplasmic deposits. In some instances, these deposits were clustered about the nuclear membrane. Staining of neurons in the granular layer of cerebellum was an exception. Granule cells were lightly outlined by peroxidase reaction product. Cerebellar islands, also referred to as glomeruli, were stained an intense uniform brown. These results raise the possibility that oligodendroglia and blood vessel endothelia, through the action of adenosine deaminase, might play a role in controlling the concentration of extracellular adenosine in brain. They do not, however, support the suggestion that complexing protein aids in adenosine metabolism by positioning adenosine deaminase on the plasma membrane.
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PMID:Localization of adenosine deaminase and adenosine deaminase complexing protein in rabbit brain. 354 89

The importance of endogenous myocardial adenosine in attenuating catecholamine-elicited contractile responses was investigated in perfused oxygenated rat hearts. Perfusion of the isolated hearts with adenosine deaminase potentiated the isoproterenol-induced increases of three contractile variables (left ventricular pressure development and rates of both left ventricular pressure development and relaxation). The peak (maximal, within 30 s) and maintained (after 1 min) increases of the contractile variables caused by 10(-8) M isoproterenol were enhanced by 15-22 and 31-43%, respectively. Adenosine deaminase appeared in epicardial surface transudates of similarly perfused hearts, indicating that the enzyme had entered the myocardial interstitial space. Isoproterenol alone elevated the release of adenosine into coronary effluents of isoproterenol-stimulated hearts, and adenosine deaminase prevented the release of the nucleoside. The higher the level of adenosine in the effluent, the greater the reduction of the peak contractile variables. Phenylisopropyladenosine at 10(-8) M prevented the adenosine deaminase potentiation of 10(-9) M isoproterenol-induced contractile responses. The adenosine analogue at 10(-6) M blocked completely the isoproterenol-produced increases in the contractile variables. These results suggest that endogenous adenosine prevents full mechanical responsiveness to beta-adrenoceptor stimulation in the oxygenated myocardium. In addition, the findings support the notion that adenosine serves as an important negative feedback modulator in the oxygenated heart.
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PMID:Endogenous adenosine inhibits catecholamine contractile responses in normoxic hearts. 374 Feb 98

We studied the activity of adenosine deaminase in the peritoneal fluid of 66 patients who were divided into five groups according to causes of ascites as follows: tuberculous peritonitis (group I), septic peritonitis (group II), secondary to malignant tumours (group III), miscellaneous conditions (group IV), and control subjects of transudates (group V). In patients with tuberculous peritonitis the enzyme activity was significantly higher than for the rest of the groups (p less than 0.001), and enzyme concentrations in all patients were well above the upper non-tuberculous value. Adenosine deaminase activity in the peritoneal fluid has proved to be a simple and reliable method for early diagnosis of tuberculous peritonitis.
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PMID:Adenosine deaminase activity in the diagnosis of tuberculous peritonitis. 375 18

Adenosine as well as hypoxia and ischemia are known to cause atrioventricular conduction block. To test the hypothesis that adenosine is the primary mediator of hypoxia-induced atrioventricular conduction delay in isolated perfused guinea pig hearts, we characterized a) the time courses of hypoxia-induced adenosine release and delay in atrioventricular conduction, b) the relationships between oxygen tension, adenosine concentration in the effluent, and atria-to-His-bundle interval, and c) the adenosine receptor mediating the negative dromotropic effect of hypoxia. Oxygen tension and effluent adenosine levels were linearly related with a correlation coefficient (r) of -0.85 and a slope of -6.3 +/- 0.37 pmol/min/g/torr. Likewise, oxygen tension and atria-to-His-bundle interval prolongation were linearly related with r = -0.85 and a slope of -0.180 +/- 0.013 msec/torr. The EC50 of effluent adenosine in causing atria-to-His-bundle prolongation was 0.26 +/- 0.02 microM. Adenosine deaminase, an enzyme that deaminates adenosine to inosine and is limited to the extracellular space, significantly attenuated (61%) the atria-to-His-bundle interval prolongation caused by hypoxia. This prolongation was further reduced (81%) by a combination of adenosine deaminase and theophylline, an adenosine receptor blocker. Adenosine deaminase also reduced (by 95%) the atria-to-His-bundle interval prolongation in normoxic recipient hearts caused by the effluent of hypoxic donor hearts. Several adenosine antagonists, i.e., theophylline, 8-phenyltheophylline, and 8-(p-sulfophenyl)theophylline antagonized in a dose-dependent manner the negative dromotropic effect of exogenous adenosine and hypoxia. Schild analysis of the antagonism of hypoxia-induced atria-to-His-bundle interval prolongation by 8-(p-sulfophenyl)theophylline yielded the following pA2 values: 5.30 +/- 0.25 and 5.28 +/- 0.31 using oxygen tension and effluent adenosine vs. AH interval prolongation, respectively. 8-(p-Sulfophenyl)theophylline also antagonized to an equal extent atria-to-His-bundle interval prolongations of similar magnitude caused either by adenosine or hypoxia. We conclude that 1) adenosine is the primary mediator of hypoxia-induced atrioventricular conduction delay, and 2) the adenosine receptor that mediates the negative dromotropic effect of hypoxia is similar to that of exogenous adenosine.
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PMID:Effect of adenosine on atrioventricular conduction. II: Modulation of atrioventricular node transmission by adenosine in hypoxic isolated guinea pig hearts. 379 84


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