Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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

5'-Methylthioadenosine (MTA) is a naturally occurring nucleoside which is degraded by MTA phosphorylase (MTAase) to adenine and methylthioribose-1-phosphate in all normal mammalian cells. These products of the phosphorylytic cleavage of MTA are recycled to the nucleotide pool and methionine, respectively. Thus, supplemental MTA could theoretically be utilized by MTAase-containing cells as a source of methionine and adenine. In fact, in vitro experiments have shown that MTAase-containing cells proliferate normally in methionine-free medium if MTA is added to the cultures (M. K. Riscoe and A. J. Ferro, J. Biol. Chem., 259: 5465-5471, 1984). In contrast, MTAase-deficient malignant cell lines do not proliferate under these conditions. In light of these observations and the recent demonstration (N. Kamatani et al., Blood, 60: 1387-1391, 1982) that a proportion of acute lymphoblastic leukemias lack MTAase, we wished to determine if this enzyme deficiency occurs in a variety of human neoplasms. Accordingly, malignant cells from eight patients with acute nonlymphocytic leukemia and ten patients with various solid tumors were assayed for MTAase activity. Samples from one of the eight acute nonlymphocytic leukemia patients and three of the 10 solid tumor patients (one with melanoma, one with squamous cell lung cancer, and one with adenocarcinoma of the rectum) had undetectable MTAase activity. In contrast, erythrocytes, neutrophils, and monocytes isolated from normal subjects and from patients with immunodeficiency syndromes or cancer all contained enzyme activity. In addition, the methods of preservation, storage, and cell disruption did not affect MTAase activity. These observations confirm and extend the findings of Kamatani et al. (Blood, 60: 1387-1391, 1982) by demonstrating that MTAase deficiency occurs in a variety of human malignancies including acute nonlymphocytic leukemia and solid tumors. This metabolic difference between normal and malignant cells may be therapeutically exploitable.
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PMID:Methylthioadenosine phosphorylase deficiency in human leukemias and solid tumors. 309 64

A sensitive high-performance liquid chromatography (HPLC) assay has been developed to simultaneously determine levels of the anti human immunodeficiency virus agent, zidovudine (AZT), and its major metabolite (the 5'-O-glucuronide) in serum. Samples were first mixed with an internal standard (a stereoisomer of AZT), then prepared for analysis using solid-phase extraction columns and chromatographed using a reversed-phase analytical column. Isocratic elution with a mobile phase of 15% acetonitrile, buffered to pH 2.70 with ammonium phosphate, gave good resolution of the three analytes and endogenous serum components. The HPLC analysis time required per sample was 34 min and analyte recoveries were reproducibly high (greater than 93%). Replicate analyses of prepared standards gave satisfactory precision and accuracy, with coefficients of variation less than 15% and deviations from expected concentrations less than 10%.
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PMID:Simultaneous quantification of zidovudine and its glucuronide in serum by high-performance liquid chromatography. 323 23

The detection of human immunodeficiency virus (HIV)-associated antigens was simplified by the application of dot immunobinding on a nitrocellulose matrix. Antigens were detected by applying the polyethylene glycol-precipitated supernatants of experimentally infected cultures directly onto nitrocellulose strips and sequentially incubating the strips with an anti-HIV antiserum and an alkaline phosphatase-conjugated, species-specific antiserum. The immune reaction was developed by adding the precipitable substrate indoyl phosphate. The dot immunobinding assay was nearly as sensitive as the reverse transcriptase assay in detecting HIV antigens in experimentally infected peripheral blood mononuclear cells, as well as in a T-cell line. The technique was also useful in the in vitro evaluation of antiviral agents. The dot immunobinding assay is a simple and sensitive technique that is useful in the detection of HIV antigens in studies of viral pathogenesis.
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PMID:Dot immunobinding assay for detection of human immunodeficiency virus-associated antigens. 331 91

Simple and sensitive methods to directly detect the human immunodeficiency virus (HIV) are needed for routine use in the clinical laboratory. In this study, we compared DNA probes prepared by: (1) nick translation with biotinylated dATP; (2) direct covalent biotinylation with photobiotin; (3) direct covalent reaction with 2-acetylaminofluorene (AAF); and (4) a standard radioactive (32P) nick translation procedure. These four DNA probes were hybridized with dilutions of purified target HIV DNA blotted onto nitrocellulose strips. Hybridization was detected using a complex of strepavidin-alkaline phosphatase [for (1) and (2)], alkaline phosphatase-tagged antibodies [for (3)] and by autoradiography [for (4)]. Alkaline phosphatase was detected colorimetrically using nitroblue tetrazolium and 5-bromo-4-chloro-3-indolyl phosphate. After 1 h, AAF probes were most sensitive (amount detected less than 5 pg), followed by biotin (10 pg), photobiotinylated probes (20 pg) and the radioactive probe (10 pg). The AAF probes were then used to detect HIV DNA in infected CEM cells. We conclude that non-radioactive DNA labelling methods can be used to directly detect HIV DNA under conditions compatible with present clinical laboratory procedures.
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PMID:Comparison of non-radioactive DNA hybridization probes to detect human immunodeficiency virus nucleic acid. 345 25

The demonstrated in vitro and in vivo activity of 3'-azido-3'-deoxythymidine (N3dThd) against the infectivity and the cytopathic effect of human immunodeficiency virus has prompted an investigation of the mechanism by which this nucleoside analogue permeates the cell membrane. As with the transport of thymidine, the influx of N3dThd into human erythrocytes and lymphocytes was nonconcentrative during short incubation times (less than 5 min) which did not allow significant metabolism of this nucleoside. However, in contrast with thymidine transport, the initial velocity of N3dThd influx was strictly a linear function of nucleoside concentration (0.5-10 mM), without evidence of saturability; insensitive to micromolar concentrations of potent inhibitors of nucleoside transport (dipyridamole, 6-[(4-nitrobenzyl)thio]-9-beta-D-ribofuranosylpurine, and dilazep); insensitive to a 1000-fold excess of other nucleosides (thymidine, uridine, 2-chloroadenosine); and relatively insensitive to temperature, with Q10 values (37-27 degrees C) of 1.4 and 2.7 for N3dThd and thymidine, respectively, determined in erythrocytes. Although the above results indicate that N3dThd permeates the cell membrane chiefly by nonfacilitated diffusion and not via the nucleoside transporter, millimolar concentrations of this nucleoside analogue were observed to inhibit both zero-trans influx of thymidine and efflux of thymidine from [3H]thymidine-loaded erythrocytes. The partition coefficients (1-octanol:0.1 M sodium phosphate, pH 7.0) of N3dThd and thymidine were determined to be 1.26 and 0.064, respectively. The unusual ability of N3dThd to diffuse across cell membranes independently of the nucleoside transport system may be attributed to the considerable lipophilicity imparted to this molecule by the replacement of the 3'-hydroxyl group of thymidine with an azido moiety.
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PMID:3'-azido-3'-deoxythymidine. An unusual nucleoside analogue that permeates the membrane of human erythrocytes and lymphocytes by nonfacilitated diffusion. 347 58

We have localized a fraction of the enzyme, purine nucleoside phosphorylase (PNP), to the centrioles and basal bodies of mammalian, avian, and protozoan cells. Two completely independent methods were used, one based on the ultrastructural cytochemistry of the enzyme activity and one based on immunofluorescence microscopy using an antibody raised in rabbit against purified human PNP. PNP catalyzes the reversible conversion of purine nucleosides and inorganic phosphate to the corresponding purine bases and ribose-1-phosphate. Its partial localization to centrioles and basal bodies raises the possibility that purine compounds are involved in centriole replication and/or in the regulation of microtubule assembly in vivo. No centriolar PNP could be detected in primary skin fibroblast from two infants with severe immunodeficiency disease associated with the absence of soluble PNP. This raises the possibility that defects in centriole function may contribute to the impaired division and maturation of T lymphoid precursor in this inherited disorder. Initially, the immunofluorescence analyses were complicated by a residual centriole-binding antibody that persisted in immunoglobulins from immune animals after complete removal of anti-PNP by affinity chromatography. Binding was abolished by exposure of cells to sodium periodate, indicating that this (and possibly other) "spontaneous" anticentriole antibodies in rabbit serum may be directed against carbohydrates.
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PMID:Purine nucleoside phosphorylase is associated with centrioles and basal bodies. 679 22

Enzyme-linked immunosorbent assay polyribosyl ribitol phosphate (PRP) antibody responses to Haemophilus influenzae type b conjugate vaccine (HbOC) given at 2, 4 and 6 months of age were retrospectively compared in 23 human immunodeficiency virus (HIV) and 24 non-HIV-infected infants. HIV-infected infants were divided into those who were P1 (asymptomatic) or P2 (symptomatic) by 1 year of age. The P2 group was further divided into P2A (mildly symptomatic) and > P2A (rapidly symptomatic) by 1 year of age. The post-third HbOC dose geometric mean antibody titer to PRP was significantly lower in 12 P2 infants (0.43 microgram/ml) than either the 11 P1 infants (5.03 micrograms/ml, P < 0.05) or the 24 non-HIV infected infants (3.43 micrograms/ml, P < 0.05). Within the P2 group, the geometric mean antibody titer to PRP was significantly higher in 5 P2A infants (1.63 micrograms/ml) compared with 7 infants who were > P2A (0.17 microgram/ml, P < 0.05). After the third HbOC dose, PRP antibody titers were > or = 1.0 micrograms/ml for 4 of 12 P2 compared with 9 of 11 P1 infants (P < 0.05). Within the P2 group, PRP antibody titers were > 1.0 micrograms/ml for 4 of 5 P2A compared to 0 of 7 infants who were > P2A (P < 0.05). HIV-infected infants with PRP antibody titers > or = 1.0 micrograms/ml after the third HbOC dose had significantly higher mean CD4 counts (2842 cells/mm3) at the time of the third HbOC dose than those with lower PRP titers (1655 cells/mm3) (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The immunogenicity of Haemophilus influenzae type b conjugate (HbOC) vaccine in human immunodeficiency virus-infected and uninfected infants. 763 8

Six affinity reagents containing chemically reactive groups, either on the phosphate residue at the 5'-end or on the 5'- or 3'-end internucleoside phosphate linkages of the oligothymidylate primers, were used to covalently modify the human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT). After covalent binding of these modified primer analogs to the enzyme, the addition of [alpha-32P]dTTP, in the presence of a complementary template, led to elongation of the primer. This reaction was catalyzed by the active site of the enzyme carrying the covalently bound primer. The relative efficiency of labeling of the p66/p51 heterodimer compared to the p66/p66 and p51/p51 homodimers of HIV-1 RT was in agreement with the previously determined affinity of the various enzyme forms toward different primers. The analogues preferentially modified the p66 subunit of the HIV-1 RT heterodimer. The labeling of all RT forms by synthetic primer analogues showed significant and specific competition by the natural primer of HIV-1 RT, tRNA(Lys). In addition, the kinetics of inactivation of RT by primer analogues was studied. The affinity of the enzyme to those derivatives in the presence of poly(A) template was about 5-10 times higher than in the absence of template. Moreover, the maximal rates of HIV-1 RT inactivation by analogues in the absence of template were 3-4 times higher. Our results suggest that the mechanism of oligonucleotide primer binding to HIV-1 RT is different in the presence or absence of template.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Affinity labeling and functional analysis of the primer binding domain of HIV-1 reverse transcriptase. 768 10

We have expressed and purified from Escherichia coli a human immunodeficiency virus type 1 (HIV-1) RNase H domain consisting of amino acids 400 to 560 of reverse transcriptase with either an N- or C-terminal polyhistidine tag. The native protease cleavage site of HIV-1 reverse transcriptase is between amino acids 440 and 441. Purification on Ni(2+)-nitrilotriacetate agarose resulted in a highly active RNase H domain dependent on MnCl2 rather than MgCl2. Activity was unambiguously attributed to the purified proteins by an in situ RNase H gel assay. Residues 400 to 426, which include a stretch of tryptophans, did not contribute to RNase H activity, and the polyhistidine tag was essential for activity. Despite the requirement for a histidine tag, the recombinant RNase H proteins retained characteristics of the wild-type heterodimer, as determined by examining activity in the presence of several known inhibitors of HIV-1 RNase H, including ribonucleoside vanadyl complexes, dAMP, and a monoclonal antibody. Importantly, the isolated RNase H domain produced the same specific cleavage in tRNA(3Lys) removal as HIV-1 heterodimer, leaving the 3'-rA (adenosine 5' phosphate) residue of a model tRNA attached to the adjacent U5 sequence. This HIV-1 RNase H domain sedimented as a monomer in a glycerol gradient.
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PMID:Purification and characterization of an active human immunodeficiency virus type 1 RNase H domain. 768 7

The crystal structure of a ternary complex of human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) heterodimer (p66/p51), a 19-base/18-base double-stranded DNA template-primer, and a monoclonal antibody Fab fragment has been determined at 3.0 A resolution. The four individual subdomains of RT that make up the polymerase domains of p66 and p51 are named fingers, palm, thumb, and connection [Kohlstaedt, L. A., Wang, J., Friedman, J. M., Rice, P. A. & Steitz, T. A. (1992) Science 256, 1783-1790]. The overall folding of the subdomains is similar in p66 and p51 but the spatial arrangements of the subdomains are dramatically different. The template-primer has A-form and B-form regions separated by a significant bend (40-45 degrees). The most numerous nucleic acid interactions with protein occur primarily along the sugar-phosphate backbone of the DNA and involve amino acid residues of the palm, thumb, and fingers of p66. Highly conserved regions are located in the p66 palm near the polymerase active site. These structural elements, together with two alpha-helices of the thumb of p66, act as a clamp to position the template-primer relative to the polymerase active site. The 3'-hydroxyl of the primer terminus is close to the catalytically essential Asp-110, Asp-185, and Asp-186 residues at the active site and is in a position for nucleophilic attack on the alpha-phosphate of an incoming nucleoside triphosphate. The structure of the HIV-1 RT/DNA/Fab complex should aid our understanding of general mechanisms of nucleic acid polymerization. AIDS therapies may be enhanced by a fuller understanding of drug inhibition and resistance emerging from these studies.
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PMID:Crystal structure of human immunodeficiency virus type 1 reverse transcriptase complexed with double-stranded DNA at 3.0 A resolution shows bent DNA. 768 65


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