Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The value of ascites gamma interferon concentration and ascites adenosine deaminase activity in distinguishing tuberculosis from other causes of ascites was examined in a prospective study of 86 patients with ascites, including 16 with tuberculous peritonitis. Gamma interferon concentration was higher in tuberculous peritonitis than in the other causes of ascites (p less than 0.0001), and a cut-off between 3 and 9 u/ml reached a sensitivity and a specificity of 100%. The mean (+/- SD) gamma interferon level in tuberculous ascites was 39.3 +/- 18.3 u/ml in patients seronegative for HIV and 14.2 +/- 4.7 u/ml in patients with AIDS (p = 0.01). Adenosine deaminase activity in tuberculous ascites was also higher than in the other causes of ascites (p less than 0.0001), and a cut-off of 40 u/l reached a sensitivity of 100% and a specificity of 97%. The two false positives for adenosine deaminase test were true negatives for the gamma interferon test. There was no significant correlation between gamma interferon concentration and adenosine deaminase activity either in tuberculous ascitis or in any other group. This study suggests that ascites gamma interferon determination may be very useful in the screening of tuberculous peritonitis, but its cost makes it advisable to use adenosine deaminase activity as a routine test, at least in areas where tuberculosis is endemic.
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PMID:Diagnostic value of ascites gamma interferon levels in tuberculous peritonitis. Comparison with adenosine deaminase activity. 177 79

Adenosine deaminase is an enzyme that actively participates in the metabolism of the adenine nucleotides. It catalyzes the irreversible hydrolytic deamination of deoxyadenosine and adenosine with the production of deoxyinosine and inosine respectively and of ammonia. This enzyme thus plays an important role in lympho-monocyte maturation and activation. The increase in its activity in different biological fluids (pleural, pericardial, peritoneal, intra-articular and cerebrospinal fluids) has been used as a rapid diagnostic test in tuberculosis infection. In human immunodeficiency virus infection, it was verified that enzymatic activity progressively increases in serum and blood cells, accompanying the natural evolution of the disease. The physiopathological mechanism has not been definitely established but the CD4+ lymphocytes and macrophages are pointed to as being accountable for the enzyme's increase in activity. For this reason, adenosine deaminase could be a marker of the cellular immune response. The study of adenosine deaminase activity in blood cells elucidated the diagnosis of severe combined immunodeficiency (due to a congenital lack of the enzyme) in 30 to 50% of the cases. One type of congenital hemolytic anemia is due to an exaggerated enzymatic activity in red blood cells.
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PMID:[Adenosine deaminase. A pluridisciplinary enzyme]. 180 98

Effects of erythro-9(2-hydroxy-3-nonyl) adenine (EHNA), an inhibitor of the common Adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4.), on HIV-1 production was evaluated in vitro. Reverse transcriptase (RT) activity in the supernatant was inhibited by nearly 50% in EHNA-treated HIV-1 infected H9 cells, when compared with untreated but infected H9 cells. There was also a significant decrease in cell viability, but this was reversed following the addition of deoxycytidine (dC) to these cultures. The combined treatment was also effective in suppressing HIV-1 release from HIV-1-infected U937 cells. This combined EHNA plus dC treatment had no effect on RT activity in the cell lysates, suggesting that the inhibition of HIV-1 production may be due to the disturbance of virus release from infected cells.
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PMID:Evaluation of the effects of erythro-9(2-hydroxy-3-nonyl) adenine (EHNA) on HIV-1 production in vitro. 247 29

Enzyme activities were studied in peripheral blood lymphocytes from patients infected with, or at risk for, infection with human immunodeficiency virus (HIV). No significant differences were observed in the HIV-infected and HIV-seronegative high-risk patients with regard to enzyme activities of hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) and purine nucleoside phosphorylase (EC 2.4.2.1) in peripheral blood. Adenosine deaminase (EC 3.5.4.4) was significantly (P less than 0.02) depressed in asymptomatic HIV-seropositive patients and HIV-seronegative patients at high risk of HIV infection as compared with a healthy HIV-seronegative population. Adenosine kinase (AK, EC 2.7.1.20) was significantly increased in the asymptomatic seropositive (P less than 0.02) and also in the HIV-seronegative high-risk groups (P = 0.01) compared with the normal controls. AK activity was significantly lower in subjects with AIDS than in the asymptomatic (P less than 0.002) and high-risk groups (P less than 0.01). Taken together, these results indicate that adenosine deaminase and AK activities are influenced by the health of the patient, and that measurement of AK activity may prove useful in monitoring the clinical progress of patients with HIV infection.
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PMID:Depressed activities of purine enzymes in lymphocytes of patients infected with human immunodeficiency virus. 254 31

Adenosine deaminase activity (ADA) was assayed in the serum of 137 HIV positive subjects: 131 intravenous drug abusers, 3 female partners of HIV positive abusers, 1 son of HIV positive abuser and 2 blood-transfused patients, subdivided into the following groups: 73 asymptomatic, 15 with ARC, 37 with LAS, 5 with L-AIDS and 7 with AIDS. Results show an increase of ADA activity in 100% of L-AIDS group, in 64% of AIDS group, in 62% and 42% of LAS and ARC groups, respectively, and in 36% of the asymptomatic groups. These findings must be confirmed with wider series in order to be further and better evaluated. According to relative substrate specificities, optimal pH and Km, enzymatic activity can be attributed principally to the ADA2 isoenzyme. The probability that ADA2 originates exclusively from the Monocyte-Macrophage cell system (MoMaCS) which actively releases this enzyme in the presence of live parasites in the cells' interior, is discussed. Moreover, it was hypothesized that in the MoMaCS the enzyme constitutes a microbicidal mechanism independent of the respiratory burst.
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PMID:Serum adenosine deaminase activity in HIV positive subjects. A hypothesis on the significance of ADA2. 268 68

The glycon moiety of nucleosides in solution is known to exist in a rapid dynamic equilibrium between extreme northern and southern conformations as defined by the pseudorotation cycle. The concept of preparing rigid nucleoside analogues with the glycon conformation locked in one of these two extremes was tested with the synthesis of some cyclopropane-fused dideoxycarbocyclic nucleosides, similar to the well-known class of anti-HIV active dideoxynucleosides. The new compounds described here are dideoxynucleoside analogues of the fermentation product neplanocin C (6) which exhibits a typical northern geometry for its 6-oxabicyclo[3.1.0]hexane pseudosugar moiety. However, in view of the lability of the epoxide ring in this system, the equivalent cyclopropane-fused bicyclo[3.1.0]hexane system was used instead to prepare the corresponding dideoxynucleoside analogues bearing all the common bases [(+/-)-9-13]. Due to the well-documented preference of unrestricted bicyclo[3.1.0]hexane systems to exist exclusively in a boat conformation, the resulting nucleosides are structurally locked in a typical northern conformation similar to that of neplanocin C. The locked northern conformation in these nucleosides remained unchanged in solution in the 20-80 degrees C temperature range according to variable temperature 1H NMR studies. For the synthesis of these compounds, racemic trans-1-[(benzyloxy)methyl]-4-hydroxybicyclo[3.1.0]hexane [(+/-)-18] was prepared by a samarium-promoted cyclopropanation reaction with the antecedent cyclopentenol. All of the bases were incorporated under Mitsunobu conditions and converted to the desired final products following a standard methodology. Anti-HIV evaluation revealed that only the adenosine analogue (+/-)-9 possessed enough activity to warrant resolution into its optical antipodes. This was realized by chiral HPLC chromatography to give the individual enantiomers (-)-32 and (+)-33. Adenosine deaminase was used to identify isomer (+)-33 as the enantiomer with the "natural" configuration which was solely responsible for the observed biological activity and toxicity of (+/-)-9. It is possible that the exclusive northern conformation adopted by these nucleosides reduces their substrate affinity for the various activating kinases, except in the case of the adenosine analogue.
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PMID:Conformationally locked nucleoside analogues. Synthesis of dideoxycarbocyclic nucleoside analogues structurally related to neplanocin C. 793 67

Adenosine deaminase (ADA) and the HIV-1 transactivator protein Tat have been reported to bind to human CD26, also known as dipeptidyl peptidase IV (DPP IV). In order to demonstrate the specificity of such binding under native conditions of CD26, i.e., when expressed on the cell surface, we established murine cell lines expressing transfected human CD26, either wild-type or mutated at its serine-630, which inactivates the DPP IV activity. This experimental system is advantageous since murine ADA does not bind human CD26, whereas human and bovine ADA bind. Consequently, murine cell clones expressing either the wild-type or mutated form of human CD26 were found to bind specifically bovine 125I-labeled ADA with a high affinity (KD = 12 +/- 2 nM and 11 +/- 4 nM, respectively). No specific binding of 125I-labeled ADA was observed to murine clones not expressing human CD26. The binding of 125I-labeled ADA to CD26 was further characterized by the use of monoclonal antibodies specific to human CD26. The results obtained were in accord with those reported previously using other experimental models. These observations indicated that the murine cells expressing human CD26 provide a highly suitable model to investigate the potential binding of HIV-1 Tat to CD26. In contrast to previously published results, however, we could not demonstrate a specific interaction between Tat and human CD26. The 125I-labeled ADA-specific binding to human CD26 was not affected by Tat, even at concentrations which induced cell death. Similarly, the binding of several monoclonal antibodies to human CD26 was not modified by the addition of Tat. More significantly, Tat binding to different murine cell clones (human CD26 negative or positive) was found not to be correlated with the expression of human CD26. Finally, the toxic effect of Tat on the growth of different murine cell clones was independent of human CD26 expression. Taken together, these observations further confirm the specific binding of ADA to human CD26 and point out that CD26 is not the target of HIV-1 Tat protein.
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PMID:Specific binding of adenosine deaminase but not HIV-1 transactivator protein Tat to human CD26. 863 2

Adenosine deaminase (ADA, EC 3.5.4.4) is an enzyme of the purine metabolism which has been the object of considerable interest mainly because the congenital defect causes severe combined immunodeficiency (SCID). In the last 10 years, ADA, which was considered to be cytosolic, has been found on the cell surface of many cells and, therefore, it can be considered an ecto-enzyme. There is recent evidence about a specific role of ecto-ADA, which is different from that of intracellular ADA. Apart from degrading extracellular adenosine (Ado) or 2'-deoxyadenosine (dAdo), which are toxic for lymphocytes, ecto-ADA has an extraenzymatic function via its interaction with CD26. ADA/CD26 interaction results in co-stimulatory signals in T cells. This co-stimulation is blocked by HIV-1, thus evidencing a role for ecto-ADA in the pathophysiology of AIDS. The fact that, besides CD26, ADA can interact with different cell-surface proteins opens new perspectives in the research for a role of ecto-ADA in the function of the immune system and in the interactions that take place between different cells in the development of the immune system. The most interesting aspect is the possible participation of the ecto-enzyme in cell-to-cell contacts during ontogenesis and maturation of immunocompetent cells.
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PMID:Enzymatic and extraenzymatic role of ecto-adenosine deaminase in lymphocytes. 955 62

Adenosine deaminase activity (ADA) determination in cerebrospinal fluid (CSF) is considered a specific test for the diagnosis of tuberculous meningitis. In order to study the variability of this marker in patients with different neurological disorders associated with HIV infection, and its utility for the diagnosis of tuberculous meningitis in these patients, the ADA levels in 417 CSF samples from HIV-infected patients with neurological symptoms were reviewed. HIV infection, HIV-associated neurological disorders, and progressive multifocal leukoencephalopathy were not associated with elevated ADA in CSF. Among patients with meningitis, receiver operating characteristic curve analysis gave an optimal ADA cut-off point of 8.5 IU/l for the diagnosis of tuberculous meningitis, with 57% sensitivity, 87% specificity, and an area under the curve of 0.747 (similar to that for CSF glucose concentration). False-positive results were found in patients with neurological CMV disease and cryptococcal, lymphomatous, and probable candidal meningitis. The results of this study indicate that ADA determination in CSF has limited utility for the diagnosis of tuberculous meningitis in HIV-infected patients.
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PMID:Adenosine deaminase activity in cerebrospinal fluid of HIV-infected patients: limited value for diagnosis of tuberculous meningitis. 1514 33

Adenosine deaminase (ADA) plays an important role in the immune system, and its activity is composed of two kinetically distinct isozymes, ADA1 and ADA2. ADA2 is a major component of human plasma total ADA activity and ADA2 activity is significantly elevated in patients with various diseases such as HIV infection and chronic hepatitis. However, relatively little is known about ADA2 because of difficulties in purifying this enzyme. In this study we succeeded in purifying human plasma ADA2 and demonstrate the extracellular secretion of ADA2 from human peripheral blood monocytes stimulated with phorbol 12-myristate 13-acetate and calcium ionophore.
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PMID:Human plasma adenosine deaminase 2 is secreted by activated monocytes. 1654 54


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