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)

Tuberculosis (TB) is still a major health problem, both as a single disease entity and as a cofactor in AIDS. The interaction between macrophage and Mycobacterium tuberculosis (MTB) is a critical step in the establishment of an early chronic infection. This study analyses the capacity of MTB to induce apoptosis in cells obtained by broncho-alveolar lavage (BAL) from patients with reactive pulmonary tuberculosis and from AIDS patients with disseminated pulmonary tuberculosis. Apoptosis was increased three-fold in BAL cells obtained from patients with pulmonary tuberculosis and even more markedly in alveolar macrophages of MTB-infected AIDS patients, compared with controls. Apoptosis was analysed and characterized by propidium iodide (PI) incorporation, terminal deoxy transferase (TDT)-mediated dUTP-biotin nick end labelling (TUNEL), and tissue transglutaminase (tTG) expression. The MTB-macrophage interaction was also investigated in vitro by infecting monocyte-derived macrophages (MDM) with MTB (virulent strain H37Rv). The induction of apoptosis by MTB required viable bacteria, was dose-dependent, and was restricted to H37Rv. Infection with either Mycobacterium avium complex (MAC) or HIV-1 and treatment with heat-killed MTB failed to induce apoptosis.
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PMID:Apoptosis of human monocytes/macrophages in Mycobacterium tuberculosis infection. 907

The enzyme dUTP pyrophosphatase (dUTPase, EC 3.6.1.23) is essential for cellular DNA replication and cell viability by virtue of its role in reducing the availability of dUTP as a substrate for DNA polymerases. Several members of the onco- and lentivirus families of retroviruses encode dUTPases and mutant strains of these viruses defective in this enzyme exhibit suboptimal replication kinetics. Among the lentiviruses there exists a surprising phylogenetic discontinuity in the distribution of dUTPase genes: non-primate viruses (EIAV, CAEV, FIV, visna) contain such genes whereas the primate viruses (HIVs, SIVs) do not. The reason for this difference is unknown. We suggest the following explanation: (1) the nuclear and mitochondrial compartmentalization of the mammalian dUTPase, combined with the cytoplasmic location of ribonucleotide reductase, leads to the net synthesis of dUTP, together with dCTP, dGTP and dATP in the cytoplasm; (2) this combination of dNTPs serves as a "toxic cocktail" for viral replication by virtue of its ability to promote the synthesis of uracil-substituted DNA; (3) many viruses have adapted to this challenge by encoding dUTPases that are free of normal cellular regulatory constraints; and (4) the fortuitous expression of a dUTPase encoded by one or more human endogenous retroviruses (HERVs) has led to the evolutionary loss of the putative ancestral dUTPase gene of primate lentiviruses. Thus, we propose that efficient replication of HIV in humans depends upon expression of a dUTPase encoded by an endogenous retrovirus. If this proposal is correct, then the entry of HIV into target cells is necessary, but not sufficient, for replication of the virus in humans.
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PMID:HIV and human endogenous retroviruses: an hypothesis with therapeutic implications. 910 94

Nondenaturing gel electrophoresis was used to study the nucleotide substrate-induced conformational change in reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1). Dead-end complex was formed between HIV-1 RT, dideoxynucleotide chain-terminated primer, and DNA template in the presence of deoxynucleotide triphosphate (dNTP) complementary to the next position on the template. Complexes which form in the absence of the next complementary dNTP were disrupted by adding excess poly(rA)/oligo(dT) or heparin just prior to electrophoresis. Dead-end complex formation by noncomplementary dNTP's or ribonucleotides was at least 2000-fold less efficient than with the complementary nucleotide. When dA was the next nucleotide on the template, analogues of dTTP supported dead-end complex formation with increased apparent Kd (dTTP < dideoxy-TTP approximately alpha-thio-dTTP < dUTP < 3'-azidothymidine triphosphate). A similar relationship was observed for dGTP analogues across from dC on the template (dGTP < dideoxy-GTP < alpha-thio-dGTP << dITP < dideoxy-ITP). The optimal length of the primer/template duplex region for dead-end complex formation was between 20 and 32 base pairs. Primer-template with a mismatched primer terminus did not support dead-end complex formation, and primer terminated with 3'-azidothymidine formed dead-end complex with 25-fold elevated apparent Kd. By contrast, dead-end complex formation on primer terminated with dideoxy-IMP base paired with dC on the template was more efficient than on primer terminated with dideoxy-GMP. Implications for the mechanisms of discrimination between nucleotide analogues by HIV-1 RT are discussed.
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PMID:Nucleotide-induced stable complex formation by HIV-1 reverse transcriptase. 915 15

HIV-associated nephropathy (HIVAN) is a progressive glomerular and tubular disease that is increasingly common in AIDS patients and one of the leading causes of end stage renal disease in African Americans. A major unresolved issue in the pathogenesis of HIVAN is whether the kidney disease is due to renal cell infection or a "bystander" phenomenon mediated by systemically dysregulated cytokines. To address this issue, we have used two different experimental approaches and an HIV-1 transgenic mouse line that develops a progressive renal disease histologically similar to HIVAN in humans. In the murine model, kidney tissue expresses the transgene and in heterozygous adults, renal disease develops shortly thereafter. We demonstrate by terminal deoxynucleotide transferase-mediated dUTP-biotin nick-end labeling assay that similar to the disease in humans, apoptosis of renal tubular epithelial cells is a component of the molecular pathogenesis. To determine whether apoptosis is due to transgene expression or environmental factors, we treated fetal kidney explants (normal and transgenic) with UV light to induce transgene expression. Apoptosis occurred in transgenic but not normal littermates after stimulation of transgene expression. To confirm a direct effect of HIV expression on the production of HIVAN, we transplanted kidneys between normal and transgenic mice. HIVAN developed in transgenic kidneys transplanted into nontransgenic littermates. Normal kidneys remained disease free when transplanted into transgenic littermates. Thus, the renal disease in the murine model is intrinsic to the kidney. Using two different experimental approaches, we demonstrate a direct effect of transgene expression on the development of HIVAN in the mouse. These studies suggest that in humans, a direct effect of HIV-1 expression is likely the essential cause of HIVAN, rather than an indirect effect of cytokine dysregulation.
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PMID:Nephropathy in human immunodeficiency virus-1 transgenic mice is due to renal transgene expression. 920 60

The diagnosis of HIV infection in newborns is established by amplification of proviral DNA using the polymerase chain reaction (PCR). We developed a nonisotopic method for heminested PCR using a biotinylated primer among sets of three oligonucleotides, each selected from the HIV long terminal repeat (LTR) and gag sequences. An internal probe incorporating digoxigenin-dUTP was also synthesized by PCR. The PCR products, hybridized with LTR region or gag region probes, were captured with streptavidin-coated magnetic beads and detected by fluorescein isothiocyanate-labeled antidigoxigenin in flow cytometric analysis. This immunoreactive bead assay (PCR-IRB) detected about three copies of HIV proviral DNA. A panel of 50 coded DNA specimens of infants previously assayed by conventional PCR and with known clinical results revealed that the PCR-IRB findings using LTR, but not gag, were in agreement. A double-blind prospective study of blood samples from 14 mother-infant pairs using the PCR-IRB amplification of LTR gave results similar to the commercial Amplicor HIV-1 PCR test and were consistent with the clinical outcomes. PCR-IRB results were positive for 11 mothers and three infants, one at birth, one at 2 weeks after birth, and one at 8 weeks after birth. PCR-IRB is a simple, reliable, specific, and automatable assay useful in the early diagnosis of perinatal HIV infection in clinical practice and regional screening programs.
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PMID:Transmission of HIV-1 in infants born to seropositive mothers: PCR-amplified proviral DNA detected by flow cytometric analysis of immunoreactive beads. 921 52

Thermophilic strand displacement amplification (tSDA) is an isothermal DNA amplification technique that proceeds at 55-60 degrees C using both a thermostable restriction enzyme and a DNA polymerase. A modification of this system has been developed that allows the simultaneous amplification and detection of a DNA target by the addition of a detector probe to the reaction. This tSDA system has been further modified into a flow cytometry-based, bead capture assay for quantitation of HIV-1 RNA. A biotinylated capture probe and digoxygenin-dUTP have been incorporated into the tSDA reaction. The resulting double labelled amplicons are captured on strepavidin beads, and a fluorescent signal is generated on the beads by staining with fluorescent anti-digoxygenin antibody. The assay has a linear dynamic range of three orders of magnitude with a lower detection limit at 250 HIV-1 RNA molecules.
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PMID:A rapid and sensitive method for non-isotopic quantitation of HIV-1 RNA using thermophilic SDA and flow cytometry. 937 93

Apoptosis seems to play an important role in the decline of CD4+ T-cells in patients infected with HIV-1. Moreover, extensive interest in apoptosis comes from the observation that it correlates both with the progression and the severity of HIV-1 infection. A cross-sectional study was made to evaluate whether such correlation may also extend to the early phases of ex vivo apoptosis, after 20 h of culture. DNA fragmentation, a parameter associated with apoptosis, was evaluated with the terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling (TUNEL) technique, which preferentially labels apoptosis in comparison to necrosis. The results obtained indicate that a negative correlation exists between the proportion of lymphocytes exhibiting DNA strand breaks and the absolute number of CD4+ T-cells per microliter. DNA fragmentation was significantly higher in patients with AIDS or advanced HIV-1 infection as compared to asymptomatic patients or seronegative individuals. No significant difference was found in relation to antiretroviral therapy. Furthermore, the addition of nicotinamide to the cultures significantly reduced DNA fragmentation of both in vitro HIV-1-infected MT-4 cells and lymphocytes from six HIV-1-seropositive individuals. The results of this study confirm that DNA fragmentation, as an early marker of apoptosis, correlates with the severity of HIV-1 infection and suggest that nicotinamide may be involved in the modulation of HIV-1-related apoptosis.
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PMID:Apoptotic DNA fragmentation, and its in vitro prevention by nicotinamide, in lymphocytes from HIV-1-seropositive patients and in HIV-1-infected MT-4 cells. 937 95

Apoptosis is a main feature of AIDS pathogenesis and is thought to play a role in the progressive decrease of CD4+ T lymphocytes in infected individuals. To determine whether apoptosis occurs in infected and/or in uninfected peripheral blood T lymphocytes, we have used a recombinant human immunodeficiency virus type 1 (HIV-1) infectious clone expressing the green fluorescent protein (GFP). Using flow cytometry, we have determined the incidence of apoptosis by either terminal transferase dUTP nick end labeling or annexin-V assays in different cell subpopulations, i.e., in CD4+ or CD8+ T cells that were GFP positive or negative. After HIV-1 infection of purified peripheral blood lymphocytes, we observed that apoptosis occurred mostly in infected CD4+ peripheral blood lymphocytes. Remarkably, the presence of monocyte-derived macrophages in the culture increased dramatically the apoptosis of uninfected bystander T lymphocytes, while apoptosis in HIV-infected T lymphocytes was not changed. We therefore demonstrate that HIV-induced apoptosis results from at least two distinct mechanisms: (i) direct apoptosis in HIV-infected CD4+ T lymphocytes and (ii) indirect apoptosis in uninfected T cells mediated by antigen-presenting cells.
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PMID:Distinct mechanisms trigger apoptosis in human immunodeficiency virus type 1-infected and in uninfected bystander T lymphocytes. 942 Feb 71

Replacement of alpha-, beta- and gamma-phosphate groups in 2'-deoxynucleoside 5'-triphosphates (dNTP) with phosphonate groups yields a new set of dNTP mimics with potential biological and therapeutic applications. Here, we describe the synthesis of 15 new dNTPs modified at alpha-, beta- and gamma-phosphates containing, in the case of dUTP, reporter and ligand groups at the C5 position of uracil. It was shown that gamma-substituted dNTPs were substrates for AMV reverse transcriptase despite of the large size of substituent at the gamma-phosphonate. On the other hand, these compounds were poorly utilized by DNA polymerase alpha. For dUTP analogues substituted at both gamma-phosphonate and C5 of uracil, the substrate affinity was 1-2 orders of magnitude lower than for their counterparts containing substituents either at gamma-phosphonate or C5 position. Meanwhile, C5-substituted beta, gamma-dibromomethylenediphosphonates demonstrated poor activity or were not active at all as substrates for AMV reverse transcriptase. Finally, 2'-deoxythymidine 5'-[beta, gamma-(methylphosphinyl)methylphosphonyl]-alpha-phosphate and its 3'-azido-3'-deoxy analog were substrates for AMV reverse transcriptase, but the substrate activity of these analogues was 50-100 times lower as compared with dTTP. HIV reverse transcriptase utilized these compounds 1 order of magnitude less efficiently than AMV reverse transcriptase; terminal deoxynucleotidyl transferase did not recognize them at all.
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PMID:2'-Deoxynucleoside 5'-triphosphates modified at alpha-, beta- and gamma-phosphates as substrates for DNA polymerases. 944 70

It has been reported previously that cells expressing a truncated form of CD4 which lacks the cytoplasmic tail of the molecule (truncation at position 402) were not sensitive to human immunodeficiency virus type 1 (HIV-1)-induced apoptosis in an acute-phase model of infection (J. Corbeil, M. Tremblay, and D. D. Richman, J. Exp. Med. 183:39-48, 1996). The role played by the cytoplasmic domain of CD4 in HIV-1-induced apoptosis was reexamined here with clones of A2.01 cells expressing different forms of CD4 and the DNA intercalant YOPRO-1 assay. Six days after virus exposure, we found evidence of apoptosis in A2.01 cells expressing the wild-type CD4 (A2.01/CD4), whereas enhanced apoptosis remained absent in cultures of A2.01/CD4.401 and A2.01/CD4.403 cells (A2.01 cells which express CD4.401 and CD4.403 molecules with truncations at positions 401 and 403, respectively). However, cell death by apoptosis measured with YOPRO-1 was found in cultures of A2.01/CD4.401 and A2.01/CD4.403 cells 15 days after virus exposure. This result was confirmed with a terminal dUTP nick end-labeling assay and propidium iodide staining. The long lag time postinfection required for apoptosis to be observed in cultures of infected cells expressing truncated forms of CD4 was due to the delayed viral replication in these cells, as shown by monitoring of the viral reverse transcriptase activity and HIV-1 p24gag antigen expression. These results emphasize the relationship between virus replication and cell death by apoptosis.
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PMID:Delayed human immunodeficiency virus type 1-induced apoptosis in cells expressing truncated forms of CD4. 949 24


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