UMLS:C0021051 - FACTA Search

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Query: UMLS:C0021051 (immunodeficiency)
71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of adenosine on the mitogenic response of peripheral blood lymphocytes (PBL) and on the nucleotide pools of erythrocytes from normal horses, horses heterozygous for the combined immunodeficiency (CID) trait (carriers), and foals with CID was studied. When PBL from normal, carrier, and CID horses were stimulated by phytohemagglutinin (PHA), concanavalin A, or pokeweed mitogen, [3H]thymidine uptake was inhibited by adenosine (0.1 microM) to 1.0 mM) in a dose-dependent manner. Adenosine (100 microM) mediated inhibition of [3H]thymidine uptake was prevented in both normal and carrier horse PBL by incubation with uridine. Uridine had no sparing effect on PBL from horses with CID. Differences were detected between human and horse PBL in response to adenosine and erythro-9(2-hydroxy-3-nonyl) adenine (EHNA), a competitive inhibitor of adenosine deaminase. In the first assay, mitogen-stimulated PBL from horses were more sensitive to adenosine. In the second assay, adenosine was added to PBL cultures at various times after PHA addition. Adenosine inhibited mitogenesis in horse PBL if added within the first 24 h. In human PBL cultures, adenosine inhibited mitogenesis only if added within the first 4 h. The third assay measured capacity of PHA-stimulated human and horse lymphocytes to escape inhibition by adenosine or EHNA. At the end of a 72-h culture period, horse PBL were still inhibited of mitogenesis in both human and horse PBL. With prolonged incubation (72 h), synergistic inhibition was detected only in horse PB. With high-pressure liquid chromatography, nucleotide levels in erythrocytes of normal, carrier, and CID horses were found to be similar. Incubation with adenosine produced a 1.5- to 2-fold increase in total adenine nucleotide pools in erythrocytes from all horses. However, these increases were accompanied by alterations in the relative amounts of the nucleotide components. This was seen as a significant decrease in the ATP:(AMP plus ADP plus ATP) ratio and energy charge in erythrocytes from normal horses. In contrast, the ATP:(AMP plus ADP plus ATP) ratio decreased only slightly in erythrocytes from CID horses, whereas no change in the energy charge was detected. The data from these studies indicate a difference in adenosine metabolism exists between human and horse lymphoyctes, and an abnormality may exist in purine metabolism or in an interconnecting pathway in horses with CID.
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PMID:In vitro of adenosine on lymphocytes and erythrocytes from horses with combined immunodeficiency. 44 64

Productive infection of cells by human immunodeficiency virus type 1 (HIV-1) is associated with the activation state of the cell and its obligatory expression of the interleukin-2 receptor (IL-2R), the latter providing a new target for antiviral therapy. A quantitative RNA-RNA hybridization assay is employed to detect production of HIV-1 RNA and to show that two IL-2 diphtheria toxin-related fusion proteins (DAB486IL-2 and its more potent, truncated form DAB389IL-2) inhibit HIV-1 RNA production in infected cells. A mutant form of DAB486IL-2 containing a single point mutation that inactivates the adenosine diphosphate ribosyltransferase activity of the toxin does not inhibit HIV RNA production, even though the molecule binds to the IL-2R. The active fusion proteins inhibit viral RNA replication in cells infected with HIV-1 clinical isolates as well as with a ZDV-resistant strain of HIV-1. These results indicate that IL-2 receptor-targeted fusion proteins can be utilized to inhibit HIV-1 replication effectively in infected human lymphocytes.
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PMID:Inhibition of HIV-1 RNA production by the diphtheria toxin-related IL-2 fusion proteins DAB486IL-2 and DAB389IL-2. 145 29

Candida albicans and Cryptococcus neoformans are major causes of systemic fungal infections, particularly in patients with acquired immunodeficiency syndrome. Metabolic labeling studies revealed that these organisms synthesize a small number of N-myristoylproteins, the most prominent being 20-kDa ADP-ribosylation factors (Arfs). C. albicans Arf has approximately 80% identity with the essential Arf1 and Arf2 proteins of Saccharomyces cerevisiae. [3H]Myristic acid analogs with oxygen for -CH2- substitutions at C4, C6, C11, and C13 are incorporated into cellular N-myristoylproteins, phospholipids, and neutral lipids produced by these three yeasts during exponential growth at 30 degrees C in complex media. Analog- and organism-specific differences in the efficiency of labeling of proteins and lipid classes were observed. The effects of oxatetradecanoic acids with oxygen for -CH2- substitutions at C3-C13 on C. neoformans, C. albicans, and S. cerevisiae were assessed during mid-log phase growth at 30 degrees C. A single dose of 3-oxa-, 4-oxa-, 5-oxa- or 6-oxatetradecanoic acid (O3-O6, final concentration = 300 microM) was able to inhibit growth of C. neoformans in the order O4 greater than O5 greater than O3 approximately O6. The other compounds were inactive. 4-Oxatetradecanoic acid was fungicidal, producing a 10,000-fold reduction in viable cell number 1 h after administration and continued suppression of cell growth for 7 h. A clear dose response was observed over a concentration range of 100-300 microM. 4-Oxatridecanoic acid was 100-fold less potent in reducing cell viability than 4-oxatetradecanoic acid but more potent than 5-oxatridecanoic acid. O4 produced approximately 10-100-fold reductions in the viability of C. albicans and S. cerevisiae at 300-500 microM, respectively, whereas O5 and O6 were less active. Since N-myristoylation of the Pr55gag polyprotein precursor produced by human immunodeficiency virus I (HIV-I) is essential for its assembly, we also assessed the antiviral effects of 4-oxatetradecanoic acid. O4 is able to produce a 50% reduction in the replication of HIV-I in acutely infected human T-lymphocyte cell lines at a concentration of 18 microM. Together, these data suggest that (i) the position of the oxygen for methylene substitution is a critical determinant of the fungicidal activity of O4 and (ii) NMT may be an attractive therapeutic target for treating opportunistic fungal infections in patients infected with HIV-I.
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PMID:4-oxatetradecanoic acid is fungicidal for Cryptococcus neoformans and inhibits replication of human immunodeficiency virus I. 151 54

We have previously described a recombinant protein, designated CD4(178)-PE40, consisting of the human immunodeficiency virus (HIV) envelope glycoprotein-binding region of human CD4 linked to the translocation and ADP-ribosylation domains of Pseudomonas aeruginosa exotoxin A. By virtue of its affinity for gp120 (the external subunit of the HIV envelope glycoprotein), the hybrid toxin selectively binds to and kills HIV-1-infected human T cells expressing surface envelope glycoprotein and also inhibits HIV-1 spread in mixed cultures of infected and uninfected cells. We now report that CD4(178)-PE40 and reverse transcriptase inhibitors exert highly synergistic effects against HIV-1 spread in cultured human primary T cells. Furthermore, combination treatment can completely eliminate infectious HIV-1 from cultures of human T-cell lines. This conclusion is based on protection of a susceptible cell population from HIV-induced killing, complete inhibition of virus protein accumulation, and elimination of HIV DNA (as judged by quantitative polymerase chain reaction analysis). The results highlight the therapeutic potential of treatment regimens involving combination of a virostatic drug that inhibits virus replication plus an agent that selectively kills HIV-infected cells.
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PMID:Elimination of infectious human immunodeficiency virus from human T-cell cultures by synergistic action of CD4-Pseudomonas exotoxin and reverse transcriptase inhibitors. 170 Oct 55

CD4(178)-PE40 is a genetically engineered hybrid toxin containing a portion of human CD4 linked to the translocation and ADP-ribosylation domains of Pseudomonas exotoxin A. In vitro, the molecule has been shown to selectively kill cells expressing the envelope glycoproteins of human immunodeficiency virus (HIV) or simian immunodeficiency virus (SIV), and to inhibit HIV spread. In this report we examine the activity of the hybrid toxin against cells expressing diverse forms of the HIV and SIV envelope glycoproteins, encoded by recombinant vaccinia virus vectors. The activity of CD4(178)-PE40 was found to be unaffected by mutations in the HIV-1 or HIV-2 envelope glycoprotein genes, which prevent normal proteolytic processing of the corresponding gp160 precursor molecules. Cells expressing a mutant HIV-1 envelope glycoprotein lacking most of the cytoplasmic tail of the gp41 transmembrane subunit were also sensitive to the hybrid toxin. Most interestingly, HIV-1, HIV-2, and SIVmac envelope glycoprotein molecules known to have widely differing affinities for CD4 were found to be comparably effective at mediating sensitivity to CD4(178)-PE40. By virtue of its ability to kill infected cells, the hybrid toxin inhibited the spread of SIVmac in vitro. These results indicate that CD4(178)-PE40 is active against cells expressing HIV and SIV envelope glycoproteins with a diverse array of structural differences.
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PMID:Activity of CD4-Pseudomonas exotoxin against cells expressing diverse forms of the HIV and SIV envelope glycoproteins. 173 90

Gene expression of human immunodeficiency virus type 1 (HIV-1) is induced not only by trans activation mediated through a gene product (tat) encoded by the virus but also by treatment of virus-carrying cells with DNA-damaging agents such as UV light. Employing an artificially constructed DNA in which the chloramphenicol acetyltransferase gene was placed under the control of the HIV-1 long terminal repeat, we analyzed the induction process in HeLa cells and found that inhibitors of poly(ADP-ribose) polymerase suppressed UV-induced HIV-1 gene expression but not tat-mediated expression. We also found that suppression occurs at the posttranscriptional level. These results indicate that HIV-1 gene expression is activated by at least two different mechanisms, one of which involves poly-ADP ribosylation. A possible new role of poly-ADP ribosylation in the regulation of specific gene expression is also discussed.
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PMID:Poly(ADP-ribose) polymerase inhibitors suppress UV-induced human immunodeficiency virus type 1 gene expression at the posttranscriptional level. 182 33

In this report, we have compared the uptake, metabolism, and relevant enzymology of a novel anti-acquired immunodeficiency syndrome drug, 2'-fluoro-2',3'-dideoxyarabinosyladenine (2'-F-dd-ara-A) with the corresponding properties of its parent compound 2',3'-dideoxyadenosine (2',3'-ddAdo) in three human T cell lines, MOLT-4, ATH8, and CEM. In previous communications, we have reported that the primary route of metabolism of 2',3'-ddAdo in human T lymphoblasts is catabolic, i.e., deamination to 2',3'-dideoxyinosine (2',3'-ddlno). At this point, the metabolic pathway diverges, to result in either cleavage and inactivation of 2',3'-ddlno by purine nucleoside phosphorylase or in 5'-phosphorylation by a phosphotransferase, a reaction that generates 2',3'-inosine monophosphate and ultimately the putative active metabolite 2',3'-dideoxy-ATP. Studies with kinase-deficient mutant CEM lines indicate, however, that 2'-F-dd-ara-A favors a more direct anabolic route toward formation of 2'-fluoro-dideoxynucleotides, catalyzed initially by 2'-deoxycytidine kinase. In MOLT-4 cells, amounts of 2'-fluoro-dideoxyarabinosyladenine di- and triphosphate formed were approximately 20-fold and 5-fold greater than the respective accumulation of 2',3'-dideoxy-ADP and 2',3'-dideoxy-ATP over the same time of exposure. This metabolic profile was supported by enzymological studies, which revealed that 2'-F-dd-ara-A is deaminated 10 times less rapidly than ddAdo and that the resulting deaminated product is resistant to hydrolysis by purine nucleoside phosphorylase. Under similar conditions, ddAdo was rapidly degraded through cleavage of its deamination product ddlno. Like ddAdo, 2'-F-dd-ara-A was found to be transported by passive diffusion and does not enter cells via the purine nucleoside transport carrier system. However, the rate of entry of 2'-F-dd-ara-A was about half that of ddAdo (9.7 pmol/10(6) cells/min for 2'-F-dd-ara-A versus 18.4 pmol/10(6) cells/min for ddAdo). This investigation, therefore, demonstrates that, under the conditions studied, 2'-F-dd-ara-A and its deamination product 2'-fluoro-2',3'-dideoxyarabinosylhypoxanthine have metabolic properties that differ significantly from those of their parent compounds ddAdo and ddlno. These properties, combined with the previously reported resistance of the fluorinated nucleosides to acid degradation, make these compounds interesting candidates for further study as orally administered agents for the inhibition of human immunodeficiency virus replication in patients with acquired immunodeficiency syndrome.
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PMID:2'-Fluoro-2',3'-dideoxyarabinosyladenine: a metabolically stable analogue of the antiretroviral agent 2',3'-dideoxyadenosine. 210 83

Low ATP/ADP ratios have been reported consistently for nucleotide levels of mononuclear cells separated from peripheral blood by conventional techniques. We have established that these low values (mean 2.3:1) were not due to cell damage or poor viability, but resulted from heavy platelet contamination, which is unavoidable when heparinized blood is used. The results reflect the low ATP/ADP ratios (mean 1.6:1) characteristic of platelets. Platelet-free extracts from defibrinated blood had very high ATP/ADP ratios (mean 17.4:1). The initial finding of detectable amounts of deoxy-ATP and deoxy-GTP in mononuclear cells from children with two distinct inherited immunodeficiency disorders [adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) deficiency respectively] many have been due to contamination by nucleated erythrocytes as well as platelets in non-defibrinated preparations. Defibrination before nucleotide extraction of mononuclear cells from a patient with T-cell leukaemic/lymphoma treated with the ADA inhibitor deoxycoformycin enabled the demonstration of grossly raised deoxy-ATP levels relative to deoxy-ADP levels (ratio 16.1:1), associated with severe ATP depletion. This reciprocal relationship between ATP and dATP was found by us previously in the erythrocytes in inherited ADA deficiency. These findings underline the importance of extracts uncontaminated by platelets, or nucleated erythrocytes, in the evaluation of lymphocyte nucleotide levels in inherited or acquired immunodeficiency syndromes.
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PMID:Importance of platelet-free preparations for evaluating lymphocyte nucleotide levels in inherited or acquired immunodeficiency syndromes. 641 55

The human immunodeficiency virus type-1 (HIV-1) Tat protein stimulates transcriptional elongation. Tat is introduced to the transcription machinery by binding to the transactivation response region (TAR) RNA stem-loop encoded by the 5' leader sequence found on all HIV-1 mRNAs. We have used multidimensional heteronuclear NMR to determine the structure of the TAR RNA in the presence of the ADP-1 polypeptide, a 37-mer that carries the minimal RNA recognition region of the Tat protein and closely mimics Tat binding specificity. In the presence of a variety of ligands, including ADP-1, related basic peptides and the amino acid derivative argininamide, the bulge region of TAR undergoes a local conformational rearrangement and forms a more stable structure. The structure of TAR in the bound form has been determined from over 1000 NMR-derived constraints. The U23 residue at the 5' end of the bulge is positioned near G26 and A27 in the major groove, rather than stacked on A22 as in the free TAR. U23 and G26 are brought into close proximity by contacts to the guanidinium group and side-chain amide group of a common arginine residue. However, the interaction of this guanidinium group with TAR is not the only source of binding specificity. Besides NOEs to the arginine residue participating in the conformational change, ADP-1 shows additional intermolecular NOEs to TAR, suggesting that there are multiple points of contacts between TAR RNA and residues from the basic and core regions of Tat. These structural results provide important clues towards the identification of small molecular mass and/or peptidomimetic inhibitors of the essential Tat-TAR interaction.
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PMID:The structure of the human immunodeficiency virus type-1 TAR RNA reveals principles of RNA recognition by Tat protein. 756 92

The hemostatic function of 40 feline immunodeficiency virus (FIV) seropositive and 8 FIV and feline leukemia virus (FeLV) seropositive cats was evaluated and compared with reference values from 30 clinically healthy cats. The FIV-positive cats were divided into 3 groups: group I included asymptomatic carriers; group II comprised sick FIV-infected cats with illnesses not likely to influence the hemostatic system; and group III included FIV-positive cats with diseases potentially associated with coagulopathies. Platelet counts in FIV/FeLV-infected cats were significantly lower than in healthy cats (P < .003), whereas the differences in the 3 groups of FIV-positive cats were variable (group I, P = .009; II, P = .05; III, P = .09). Thrombocytopenia (< 145,000 platelets/microL) was present in 4 FIV-positive and 3 FIV/FeLV-positive cats. Platelet aggregation induced by collagen (0.5 and 0.25 micrograms/mL), adenosine diphosphate (ADP) (1 and 0.6 mumol/L), and thrombin (0.4 and 0.25 IU/mL) was not significantly different from that of healthy cats. The plasma coagulation system was evaluated by measuring one-stage prothrombin time (OSPT), activated partial thromboplastin time (APTT), thrombin time, fibrinogen concentration, coagulation factor assays, fibrinogen and fibrin degradation products (FDP), and plasma exchange test. The OSPT was similar in FIV-seropositive cats and in the healthy control group. Cats with FIV infection, however, had markedly shorter clotting times than healthy cats when using a modified test system (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hemostatic disorders in feline immunodeficiency virus-seropositive cats. 783 13

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