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)

Adenosine may be a physiological modulator of vascular smooth muscle tone, sympathetic neurotransmission, renin release, and renal and cardiac function. To facilitate the elucidation of the physiological role of adenosine, a microassay for adenosine was developed that allows accurate quantitation of adenosine in 75 microliters of rat plasma, thus permitting multiple determinations of plasma adenosine levels in an individual rat without inducing hemodynamic perturbations due to blood loss. The technique employs a simple and rapid extraction of plasma with a reverse-phase Sep-Pak cartridge and exploits the increased mass sensitivity of microbore high performance liquid chromatography. The assay was verified by demonstrating a linear relationship between the amount of adenosine added to plasma and the amount detected by the assay, a linear relationship between the rate of adenosine infusion into rats and plasma adenosine levels, and the absence of measurable adenosine levels in plasma incubated with adenosine deaminase. The mean arterial plasma level of adenosine in the anesthetized rat was determined to be 119 +/- 28 (SD) ng/ml (n = 10). With the use of this assay, renal venous plasma levels of adenosine were found to be elevated sixfold in two-kidney, one clip Goldblatt hypertensive rats (1 week postclipping) compared with sham-operated controls. Given the known effects of adenosine on renin release, these data support a role for endogenous adenosine as a regulator of renin release in renovascular hypertension.
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PMID:Development and application of a simple microassay for adenosine in rat plasma. 330 66

A 4-month-old male received a T-lymphocyte-depleted haploidentical bone marrow transplant (BMT) for correction of severe combined immunodeficiency (SCID) due to adenosine deaminase (ADA) deficiency. Although previous haploidentical bone marrow transplants have been attempted in ADA-deficient SCID, complete reconstitution of both B-lymphocyte and T-lymphocyte function has not been obtained after a single transplant. In this patient, however, rapid, complete, and persistent engraftment occurred. Potential reasons for this successful reconstitution include the use of ablation by chemotherapy (busulfan, cyclophosphamide, and cytosine arabinoside), the in vitro technique of using monoclonal antibody (CT-2) and complement to deplete the donor cells of T lymphocytes, and the relative good health of the patient prior to the transplant. Further trials using this method of haploidentical BMT may prove it to be a successful method of immunologic reconstitution in ADA-deficient SCID patients for whom an HLA-identical marrow is not available.
Clin Immunol Immunopathol 1987 Sep
PMID:Reconstitution of T- and B-cell function after T-lymphocyte-depleted haploidentical bone marrow transplantation in severe combined immunodeficiency due to adenosine deaminase deficiency. 330 40

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.
Biochem Pharmacol 1988 Sep 01
PMID:A reexamination of the effects induced by adenosine and its degradation products on rat fat cell lipolysis. 340 Dec 55

Pentostatin (dCF), an inhibitor of adenosine deaminase, has shown activity in the treatment of several lymphoid malignancies, even in the earliest phase I trials. An analysis of the first 300 patients treated in such trials shows a high incidence of severe infection (8%) during the relatively brief period of treatment. Of 24 patients in whom infection was diagnosed, 17 had no evidence of myelosuppression. The causative organisms included viruses, fungi, and bacteria of both high and low pathogenicity. Two-thirds of the infections were fatal. It is suggested that dCF may cause a syndrome similar to severe combined immunodeficiency during the course of treatment. Patients treated with dCF who show evidence of infection, even in the absence of neutropenia, should receive vigorous and rapid diagnostic evaluation to establish the cause of their infection, and aggressive treatment of suspected organisms.
Cancer Treat Rep 1986 Sep
PMID:Association of severe and fatal infections and treatment with pentostatin. 348 5

A retroviral vector called SAX, containing the cloned human cDNA for adenosine deaminase (ADA), has been constructed and used to introduce the ADA gene into cultured T- and B-lymphocyte lines derived from patients with ADA deficiency. DNA analysis showed that the SAX vector was inserted intact into the T and B cells at approximately one copy per cell. The treated cells produced the characteristic isozymes of human ADA at a level similar to normal T and B lymphocytes. It is known that ADA-deficient lymphocytes are unusually sensitive to high levels of 2'-deoxyadenosine, and this is the mechanism thought to underlie the selective lymphocytotoxicity associated with ADA deficiency in vivo. Expression of the introduced ADA gene was sufficient to reverse the hypersensitivity of these genetically deficient lymphocytes to 2'-deoxyadenosine toxicity. These results support the suggestion that retroviral vector gene-delivery systems show promise for application to human gene therapy.
Proc Natl Acad Sci U S A 1986 Sep
PMID:Correction of adenosine deaminase deficiency in cultured human T and B cells by retrovirus-mediated gene transfer. 348 33

Reversed-phase high-performance liquid chromatographic (HPLC) procedures are described for determining the stability of 2',3'-dideoxyadenosine (DDA) in biological fluids at therapeutic dosages. The validated methodology uses both direct injection and solid-phase extraction techniques. Deamination of DDA to 2',3'-dideoxyinosine (DDI) in plasma by adenosine deaminase was monitored by HPLC, and the identification of DDI verified by thermospray HPLC-mass spectrometry. This methodology should prove useful in future studies concerning the stability and metabolism of dideoxynucleosides.
J Chromatogr 1987 Sep 04
PMID:Application of high-performance liquid chromatography and thermospray high-performance liquid chromatography-mass spectrometry to the analysis and identification of 2',3'-dideoxyadenosine and its metabolite in biological media. 349 45

The distribution of the potent inhibitor of adenosine deaminase (ADA), 2'-deoxycoformycin (DCF), in the brain of the rat and its inhibition of ADA in brain and gut was determined. The accumulation of [3H]DCF in brain was maximal 2 hr after intraperitoneal injection and elimination was best described by a two compartment model having t1/2 phases of about 1-5 hr and 50 hr. The activity of ADA in gut exhibited dose-related inhibition at 1.9, 3.7 and 18.6 mumol/kg (i.p.) and returned to normal by 16 days. In brain, ADA was inhibited by about 95% at all three of these doses of DCF 2 hr after injection and activity returned to control levels by 30 days with the two smaller doses, but remained at 66% of control levels at 50 days with 18.6 mumol/kg. The t1/2 of the recovery of the activity of ADA in both brain and gut was found to be dose-dependent. The failure of the activity of ADA in brain to recover after treatment with 18.6 mumol/kg suggests either long-term down-regulation of the expression of ADA or irreversible damage to ADA-containing neurons.
Neuropharmacology 1987 Sep
PMID:Pharmacokinetics of 2'-deoxycoformycin, an inhibitor of adenosine deaminase, in the rat. 349 81

Neurons of the posterior hypothalamic magnocellular nucleus (PHMN) in the rat are immunoreactive for adenosine deaminase (ADA) and cells coextensive with this nucleus show immunoreactivity for serotonin after pretreatment with 5-hydroxytryptophan (5-HTP). The degree to which ADA coexists in cells having 5-HTP uptake capability was analyzed by a new double immunohistofluorescence procedure employing diethylaminocoumarin (DAMC). It was determined that 5-HTP accumulating cells of the PHMN represent a subpopulation of those immunoreactive for ADA. These results add further to the neurochemical characterization of this globally projecting hypothalamic cell group and point out the utility of DAMC as a new immunohistofluorescence marker.
Neurosci Lett 1986 Sep 25
PMID:Adenosine deaminase-containing hypothalamic neurons accumulate 5-hydroxytryptophan: a dual-colour immunofluorescence procedure using a new fluorescence marker. 353 35

The sensitivity to lipolytic agents is altered in diabetic vs. control animals. Because of its role as a diabetogenic hormone and its ability to elicit lipolysis, GH was studied in isolated fat cells (IFC) from control and streptozotocin-diabetic (STZ-DM) rats. IFCs from the epididymal fat of 150 to 200-g normal and STZ-DM Holtzman rats were prepared by collagenase digestion. Lipolysis was measured by glycerol release after either incubation or perifusion with the following concentrations: epinephrine (EPI), 0.01-0.1 microM; theophylline, 0.01-1.0 mg/ml; adenosine deaminase (ADA), and bovine GH (bGH), 0.01-1.0 microgram/ml. Rats, rendered diabetic by STZ (65 mg/kg), were used on day 3. In a dose-response study comparing glycerol release from control and STZ-DM IFC, IFC were preincubated with 1.0 microgram/ml bGH and then incubated with varying concentrations of EPI or bGH. In STZ-DM, we noted increased lipolytic sensitivity to low concentrations of EPI or bGH. Furthermore, in perifusion, STZ-DM IFC did not require obligatory preincubation with bGH for optimal glycerol release. The addition of ADA increased glycerol release from incubated IFC (STZ-DM and controls). In both systems an enhanced lipolytic response to theophylline was seen in the presence of bGH in control and STZ-DM. It was thus concluded that IFC from normal animals do not respond to GH without preincubation. IFC from STZ-DM rats show a lipolytic response to GH without preincubation. Preincubation with GH increases the lipolytic response of IFC from STZ-DM to all lipolytic agents compared to control responses. In addition, ADA greatly enhanced lipolysis in IFC from STZ-DM compared to that in controls. Together these data demonstrate enhanced sensitivity to both lipolytic stimuli and adenosine suppression of lipolysis in IFC from STZ-DM.
Endocrinology 1987 Sep
PMID:Lipolysis in diabetic adipocytes: differences in response to growth hormone and adenosine. 362 74

Since adenosine and its analogue 2-chloroadenosine prevent neutrophils from generating superoxide anion in response to chemoattractants, we sought to determine whether these agents could inhibit neutrophil-mediated injury of endothelial cells. The chemoattractant N-formyl-methionyl-leucyl-phenylalanine (FMLP, 0.1 microM) enhanced the adherence of neutrophils to endothelial cells twofold (18 +/- 2% vs. 39 +/- 3% adherence, P less than 0.001) and caused substantial neutrophil-mediated injury to endothelial cells (2 +/- 2% vs. 39 +/- 4% cytotoxicity, P less than 0.001). 2-Chloroadenosine (10 microM) not only inhibited the adherence of stimulated neutrophils by 60% (24 +/- 2% adherence, P less than 0.001) but also diminished the cytotoxicity by 51% (20 +/- 4% cytotoxicity, P less than 0.002). Furthermore, depletion of endogenously released adenosine from the medium by adenosine deaminase-enhanced injury to endothelial cells by stimulated neutrophils (from 39 +/- 4% to 69 +/- 3% cytotoxicity, P less than 0.001). Indeed, in the presence of adenosine deaminase, even unstimulated neutrophils injured endothelial cells (19 +/- 4% vs. 2 +/- 2% cytotoxicity, P less than 0.001). These data indicate that engagement of adenosine receptors prevents both the adhesion of neutrophils and the injury they cause to endothelial cells. Adenosine inhibits injury provoked not only by cells that have been stimulated by chemoattractants but also by unstimulated cells. Based on this model of acute vascular damage we suggest that adenosine is not only a potent vasodilator, but plays the additional role of protecting vascular endothelium from damage by neutrophils.
J Clin Invest 1986 Sep
PMID:Adenosine: an endogenous inhibitor of neutrophil-mediated injury to endothelial cells. 374 37


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