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)

Poly(ethylene glycol) (PEG) is a water soluble polymer that when covalently linked to proteins, alters their properties in ways that extend their potential uses. PEG-modified conjugates are being exploited in many different fields. The improved pharmacological performance of PEG-proteins when compared with their unmodified counterparts prompted the development of this type of conjugate as a therapeutic agent. Enzyme deficiencies for which therapy with the native enzyme was inefficient (due to rapid clearance and/or immunological reactions) can now be treated with equivalent PEG-enzymes. PEG-adenosine deaminase has already obtained FDA approval. PEG-modified cytokines have been constructed and, interestingly, one of the conjugates, PEG-modified granulocyte-macrophage colony-stimulating factor, showed dissociation of two biological properties. This novel observation may open new horizons to the application of PEGylation technology. The biotechnology industry has also found PEG-proteins very useful because PEG-enzymes can act as catalysts in organic solvents, thereby opening the possibility of producing desired stereoisomers, as opposed to the racemic mixture usually obtained in classical organic synthesis. Covalent attachment of PEG to proteins requires activation of the hydroxyl terminal group of the polymer with a suitable leaving group that can be displaced by nucleophilic attack of the epsilon-amino terminal of lysine residues (other nucleophilic groups can also interact). Several chemical groups have been exploited to activate PEG, thereby giving rise to a variety of PEG-proteins. Some of these varieties retain part of the activating group as a coupling moiety between PEG and protein and others provide a direct linkage. For each particular application, different coupling methods provide distinct advantages.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The uses and properties of PEG-linked proteins. 145 45

Polyethylene glycol (PEG)-modified bovine adenosine deaminase (ADA) is used for replacement therapy of severe combined immunodeficiency disease due to inherited ADA deficiency. We monitored IgG anti-ADA antibody in 17 patients treated by intramuscular injections of PEG-ADA for 1 to greater than 5.5 yr. ELISA-detectable anti-ADA IgG appeared in 10 patients, usually between the third and eighth months of treatment. Anti-ADA levels did not correlate with trough plasma ADA activity, which averaged 1.8-5 times normal blood (erythrocyte) ADA activity, depending on dose (15-60 U/kg per wk). ELISA-detectable anti-ADA antibodies were directed primarily at bovine-specific peptide (rather than PEG-containing) epitopes. Enhanced enzyme clearance, mediated by antibody that directly inhibited native and PEG-modified bovine ADA, and native, but not PEG-modified human ADA, occurred in two patients. In one, tolerance was induced; in the second, twice weekly injections of PEG-ADA compensated for accelerated clearance. We speculate that inhibitory antibodies recognize conserved, relatively PEG-free epitope(s) encompassing the active site, and that in human, but not bovine, ADA a PEG-attachment site "shields" the active site from immune recognition. We conclude that PEG-modification largely prevents the development of high affinity, or high levels of clearing antibodies to bovine ADA, and that PEG-modified human ADA should be further investigated as a possible treatment for ADA deficiency.
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PMID:IgG antibody response to polyethylene glycol-modified adenosine deaminase in patients with adenosine deaminase deficiency. 156 4

Adenosine deaminase (ADA) deficiency may manifest as severe combined immunodeficiency (SCID) in early infancy. Some of these children develop radiologic changes which may be in part related to effects of this enzyme deficiency on the bony epiphysis. We describe the radiologic changes in a neonate with ADA deficiency and their resolution with polyethylene glycol conjugated adenosine deaminase (PEG-ADA, ADAGEN: Enzon, Inc., South Plainfield, NJ) enzyme replacement therapy.
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PMID:Chondroosseous dysplasia in severe combined immunodeficiency due to adenosine deaminase deficiency (chondroosseous dysplasia in ADA deficiency SCID). 174 85

The effect of polyethylene glycol-adenosine deaminase (PEG-ADA) therapy on biochemical, immunological and clinical abnormalities in an ADA-deficit child with severe combined immunodeficiency has been studied. Following PEG-ADA therapy, total lymphocytes, lymphocyte subsets (CD3, CD4 and CD8) and the response of lymphocytes to non specific mitogens increase significantly. The improvement of immunological functions is closely related to a decrease of erythrocyte deoxyadenosine triphosphate (dATP) concentrations. This study shows that PEG-ADA therapy is sufficiently effective to reduce and to maintain erythrocyte dATP levels at values compatible with normal immune functions. PEG-ADA represents an important progress for the treatment of ADA deficiency associated with severe combined immunodeficiency disease.
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PMID:[Polyethylene glycol-adenosine deaminase: a new adenosine deaminase deficiency therapy. Value of deoxyadenosine triphosphate determination for therapeutic monitoring]. 194 9

The rat brains homogenized with different media (sucrose, ethylene glycol, dimethyl sulfoxide and urea) yielded different amounts of microsomal fractions. The dielectric constant, density and viscosity of the homogenization media did not correlate with the amount of microsomes separated by differential centrifugation. The homogenization media containing dimethyl sulfoxide were the most efficient for the isolation of rat brain microsomes. The increase in the yield was up to 4-fold when 50% (v/v) dimethyl sulfoxide was employed. Microsomes isolated in this manner were analogous to those obtained from isotonic sucrose solution, as was demonstrated by their chemical and enzymatic (5'-nucleotidase, adenosine deaminase, guanine deaminase, purine-nucleoside phosphorylase, lactate, malate and glutamate dehydrogenases, amine oxidase fumarate hydratase, acid and alkaline phosphatase, acetylcholinesterase, NADPH-cytochrome c reductase, catalase and thiamine-diphosphatase) characterization.
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PMID:An improved method for the preparation of rat brain microsomes. 371 74

Adenosine deaminase (EC 3.5.4.4) was found to occur in the extract of Azotobacter vinelandii, strain 0, and purified by heating at 65 degrees C, fractionation with ammonium sulfate, DEAE-cellulose chromatography and gel filtration on Sephadex G-150. Purified adenosine deaminase was effectively stabilized by the addition of ethylene glycol. The molecular weight of the enzyme was estimated to be 66,000 by gel filtration on Sephadex G-150. The enzyme specifically attacked adenosine and 2'-deoxyadenosine to the same extent, and formycin A to a lesser extent. The pH optimum of the enzyme was observed at pH 7.2. Double reciprocal plot of initial velocity versus adenosine concentration was concave upward, and Hill interaction coefficient was calculated to be 1.5, suggesting the allosteric binding of the substrate. ATP inhibited adenosine deaminase in an allosteric manner, whereas other nucleotides were without effect. The physiological significance of the enzyme was discussed in relation to salvage pathway of purine nucleotides.
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PMID:Adenosine deaminase from Azotobacter vinelandii. Purification and properties. 721 27

Polyethylene glycol was attached covalently to adenosine deaminase (ADA) using cyanuric chloride as the coupling agent. The modified adenosine deaminase (PEG-ADA) appears to lose its immunogenicity in mice following multiple intravenous injections. PEG-ADA does not react with antibodies raised against native ADA. The circulating half-life (T1/2) of PEG-ADA was increased to 28 hr. The lack of detectable antibody formation and long circulating life may make PEG-ADA suitable for treating human ADA deficiency.
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PMID:Alteration of the circulating life and antigenic properties of bovine adenosine deaminase in mice by attachment of polyethylene glycol. 733 81

In anesthetized, paralyzed, and ventilated rats, hypoxia or intracarotid cyanide excited the carotid chemoafferents, whereas intracarotid dopamine and tyramine inhibited the chemoafferent discharges. The inhibition was abolished by chlorpromazine without attenuating the hypoxic excitation. Comparably, the hypoxic excitation was not attenuated by the following: 1) inhibition of nitric oxide synthase with NG-nitro-L-arginine; 2) inhibition of heme oxygenase with zinc protoporphyrin IX; 3) antagonism of ATP receptors with reactive blue 2; 4) antagonism of cholinergic receptors with atropine or trimethaphan; 5) inactivation of adenosine with adenosine deaminase; and 6) blockade of glutamate receptors with kynurenate. Systemic administration of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N'N'-tetraacetic acid, in doses reversibly blocking sympathetic ganglionic transmission, was also without effect. Cyanide microinjection (0.05-0.5 nmol) into the petrosal but not nodose ganglion elicited a rapid dose-dependent elevation of arterial pressure. We conclude that excitation of the chemoreceptor afferents by hypoxia/cyanide cannot be attributed to release of these agents nor to others by Ca(2+)-dependent mechanisms. The results suggest that the afferent nerves themselves might function as oxygen detectors.
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PMID:Dopamine or transmitter release from rat carotid body may not be essential to hypoxic chemoreception. 752 4

Polyethylene glycol-modified adenosine deaminase (PEG-ADA) has now been used for 8.5 years as enzyme replacement therapy for immunodeficiency due to ADA deficiency. PEG-ADA restores a metabolic environment necessary for recovery of immune function. In most cases, the level of function achieved has been sufficient to protect against opportunistic and life-threatening infections. To date, mortality and morbidity with PEG-ADA have been less than for haploidentical bone marrow transplantation. As a true "orphan drug" used to treat a very small patient population, the cost per patient of PEG-ADA is very high, but it has been well tolerated, free of adverse reactions, and effective as an alternative for patients who lack an HLA-identical marrow donor, but are considered too ill to undergo haploidentical marrow transplantation. Concomitant treatment with PEG-ADA has also permitted investigation of gene therapy to be carried out safely.
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PMID:PEG-ADA replacement therapy for adenosine deaminase deficiency: an update after 8.5 years. 755 73

Significant increases in lymphocyte adenosine deaminase activity, T cell numbers and immune function have been achieved in the two children with SCID thus far treated with autologous T cells genetically-corrected by retroviral-mediated insertion of a normal ADA gene. Although the data obtained to date demonstrate that the use of ADA gene corrected peripheral T cells appears to be an effective treatment for ADA(-)SCID, it is theoretically preferable to try to develop a treatment for these children that will result in stem cell gene correction. The genetic correction of T cell progenitors with long-term immune reconstituting ability would be more desirable because repeated infusions of genetically altered cells should not be necessary and the generation of a more complete repertoire of T cell specificities might also be possible. Furthermore, the present treatment protocol involves indefinite continuation of enzyme replacement treatment with PEG-ADA. The demonstration of ADA gene expression in the progeny of transduced stem cells may simplify the decision concerning cessation of this very costly enzyme treatment (approximately $250,000/yr./patient). Recent evidence suggests that a small fraction of bone marrow or peripheral blood mononuclear cells bearing the CD34 antigen contains hematopoietic stem cells with both lymphoid and myeloid reconstituting ability. We propose in this amendment to supplement the infusion of human ADA gene-transduced autologous T cells in children with ADA(-)SCID with autologous peripheral blood CD34+ cells transduced with a second, readily distinguishable ADA vector.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Treatment of severe combined immunodeficiency disease (SCID) due to adenosine deaminase deficiency with CD34+ selected autologous peripheral blood cells transduced with a human ADA gene. Amendment to clinical research project, Project 90-C-195, January 10, 1992. 769 Nov 88


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