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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Physiological microenvironments such as blood, seminal plasma, mucosal secretions, or lymphatic fluids may influence the biology of the virus-host cell and immune interactions for human immunodeficiency virus type 1 (HIV-1). Relative to media, physiological levels of human plasma were found to enhance the infectivity of HIV-1 primary isolates in both phytohemagglutinin-stimulated peripheral blood mononuclear cells and monocyte-derived macrophages. Enhancement was observed only when plasma was present during the virus-cell incubation and resulted in a 3- to 30-fold increase in virus titers in all of the four primary isolates tested. Both infectivity and virion binding experiments demonstrated a slow, time-dependent process generally requiring between 1 and 10 h. Human plasma collected in anticoagulants CPDA-1 and heparin, but not EDTA, exhibited this effect at concentrations from 90 to 40%. Furthermore, heat-inactivated plasma resulted in a loss of enhancement in peripheral blood mononuclear cells but not in monocyte-derived macrophages. Physiological concentrations of human plasma appear to recruit additional infectivity, thus increasing the infectious potential of the virus inoculum.
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PMID:Human plasma enhances the infectivity of primary human immunodeficiency virus type 1 isolates in peripheral blood mononuclear cells and monocyte-derived macrophages. 766 10

The presence of HIV-1 RNA in the plasma and serum of European and African patients was monitored using RNA-polymerase chain reaction (RNA-PCR) and the new isothermal NASBA nucleic acid amplification system encompassing a gel-based detection assay (ELGA). Identical RNA extraction procedures, provided by the NASBA amplification system, were used for both methods. The detection limit for HIV-1 RNA, measured on a 10-fold dilution series of spiked HIVIIIB in negative plasma, was about 0.05 CCID50 per test for both methods. Both NASBA and RNA-PCR were more sensitive than a p24 assay for the detection of circulating HIV-1 virus in blood: 17 of the 34 (50%) p24 antigen-tested seropositives were p24-positive while 32 (94%) were positive by NASBA and 30 (88%) by RNA-PCR. Among the 45 seropositives, 34 of which were tested for p24 antigen, 43 (96%) were positive by NASBA and 41 (91%) by RNA-PCR. Almost all seropositives had a detectable viral load in 100 microliters plasma. Lower viral loads were only encountered in some healthy seropositives with a higher CD4 count. There was no cross-reactivity with HIV-2 or HIV-I with both the RNA-PCR and NASBA. The extraction method used permitted the detection of HIV-1 RNA equally well in serum and in plasma with heparin or EDTA.
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PMID:Detection of HIV-1 RNA in plasma and serum samples using the NASBA amplification system compared to RNA-PCR. 776 25

The human immunodeficiency virus type 1 (HIV-1) DNA PCR results of 94 dried blood spot (DBS) samples on filter paper and corresponding venous blood in EDTA obtained from infants born to HIV-1-seropositive mothers were compared. In addition, the results of HIV-1 DNA PCR on DBS and the HIV-1 RNA PCR from plasma of 70 paired samples were compared. A 100% specificity and a 95% sensitivity for HIV-1 DNA PCR on DBS compared with results for venous blood were observed for the 94 paired samples. The results of the DBS HIV-1 DNA PCR and HIV-1 RNA PCR of 70 corresponding plasma samples correlated perfectly (100%). The DBS HIV-1 DNA PCR method proved reliable for HIV-1 detection.
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PMID:Detection of human immunodeficiency virus type 1 (HIV-1) in heel prick blood on filter paper from children born to HIV-1-seropositive mothers. 785 88

The mechanism of CD4+ cell depletion in HIV-infected patients is poorly understood. In this study we investigated whether rgp120 can activate the complement system in the absence of anti-gp120 Abs. We found that the complement proteins C4, C3d, C5b-9, and properdin bind to rgp 120-coated CD4+ T cells of healthy individuals when incubated in autologous serum. Activation of the complement system occurred primarily via the classical pathway and was abolished in sera deficient in C1q and C4 as well as in the presence of EDTA. No cell lysis was observed in a lymphocytotoxicity assay using human serum, possibly because of homologous restriction of complement lysis. In contrast, addition of rabbit sera induced lysis of the rgp 120-precoated cells. Cell lysis by rabbit serum was found to be because of naturally occurring IgM anti-gp 120 Abs. The rgp 120, which was immobilized on the surface of microtiter plates activated complement in the absence of lymphocytes. Complement activation by cell-bound HIV-1 envelope glycoprotein gp120 with subsequent opsonization may be relevant for the elimination of noninfected CD4+ T cells in HIV-infected patients.
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PMID:Complement activation by recombinant HIV-1 glycoprotein gp120. 791 92

We developed and evaluated an automated screening test for antibody to human immunodeficiency virus type 1 (HIV-1) using EDTA-2Na-treated whole blood and an extract of paper disk-absorbed dried whole blood from 60 hemophiliacs infected with HIV-1 and 210 diseased and healthy controls. The specificity and the sensitivity of this system were judged to be 100% with both the whole blood and the extract. This test allows measurement of HIV-1 antibody in whole blood and dried whole blood on a small paper disk and gives a result within 13 minutes; the system can process 150 samples per hour. Therefore, it may be useful at many testing sites, such as emergency departments, intensive care units, blood banks, and commercial laboratories, as well as for mail-order testing from remote areas and developing countries.
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PMID:Preliminary report on an automated screening test for detection of antibody to human immunodeficiency virus type 1 in whole blood. 798 9

N-acetyl-L-cysteine (NAC) has been proposed as a therapeutic agent for AIDS patients because it reduces human immunodeficiency virus type 1 (HIV-1) replication in stimulated T cells. However, NAC and glutathione enhanced acute HIV-1 replication in monocyte-derived macrophages. Buthionine sulfoximine did not affect NAC-mediated enhanced HIV-1 replication, indicating that the NAC-mediated effects are glutathione-independent. Superoxide dismutase and the hydroxyl radical scavengers dimethylthiourea and thiourea, but not urea, inhibited acute HIV-1 replication in macrophages. NAC reduced ferricytochrome c and increased dose-dependently Fe(III)-citrate and Fe(III)-EDTA-catalyzed hydroxyl radical formation in a system using glucose and glucose oxidase. Dimethylthiourea and thiourea, but not urea and superoxide dismutase, dose-dependently inhibited NAC-mediated enhancement of HIV-1 replication. These data suggest that oxygen radicals play an important role in self-sustained HIV-1 replication in macrophages and that oxygen radical scavengers other than NAC should be considered as therapeutic agents for AIDS patients.
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PMID:Role for oxygen radicals in self-sustained HIV-1 replication in monocyte-derived macrophages: enhanced HIV-1 replication by N-acetyl-L-cysteine. 799 46

The typing of lymphocyte subsets may be influenced by a variety of technical influences including the duration and temperature of sample storage and the method used for staining samples. We have extended a previous study examining the effect of storage conditions on the baseline values of a number of lymphocyte subsets. EDTA-anticoagulated samples from 13 HIV-1-positive and 15 healthy laboratory controls were analyzed for a number of lymphocyte subsets (CD3+, CD4+/CD3+, and CD8+/CD3+ T cells and CD19+ B cells) (whole blood lysis method, Becton-Dickinson FACScan flow cytometer and reagents) at 0, 24, 48, 72, and 96 h after storage at 4 degrees C, 17 degrees C or 21 degrees C. During storage at both 4 degrees C and 21 degrees C, there were significant changes in baseline values of the majority of lymphocyte subsets and some of these were related to the HIV status of the donor. The optimum temperature for storage in our system appeared to be around 17 degrees C in both our study groups. We have also used propidium iodide in order to discriminate between viable and non-viable cells during flow cytometry of lymphocytes from eight HIV-1-positive and five control subjects. The results show that for both HIV-positive and control samples stored at 4 degrees C, and for control subjects at 21 degrees C, the changes in baseline values of lymphocyte subsets observed were not due to selective loss of particular subsets arising from cell death during storage. However, there was substantial loss of cells from all three subsets in HIV-positive subjects during storage at 21 degrees C, with loss of CD8+ and CD3+ T cells being more significant than loss of CD4+ T cells.
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PMID:Technical influences on immunophenotyping by flow cytometry. The effect of time and temperature of storage on the viability of lymphocyte subsets. 837 Sep 32

In a multi-center study, whole blood specimens from 31 HIV-positive and 43 HIV-negative donors were collected in three different anticoagulants and assayed for lymphocyte subsets fresh (within 6 h), and 1 and 2 days later. Each center prepared the specimens by their routine whole blood lysis procedure, labeling with a recommended panel of two-color monoclonal antibody combinations. 1 day (up to about 30 h) after blood collection, the results obtained from blood collected in EDTA (ethylenediamine tetra-acetate), ACD (acid citrate dextrose), and heparin were similar to fresh. Up to 48 h, only ACD and heparin, not EDTA, yielded results similar to fresh specimens. These results were similar for both HIV-positive and -negative specimens.
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PMID:Selection of anticoagulants for lymphocyte immunophenotyping. Effect of specimen age on results. 840 66

A 55 residue peptide corresponding to the nucleocapsid protein of HIV-1 (NCp7) containing two zinc binding domains as well as three truncated peptides were synthesized by Fmoc-based solid phase synthesis using the fragment condensation approach. Circular dichroism (CD) data support a conformational model in trifluoroethanol/buffer solution consisting of two helical segments at the chain ends with two Zn-modules in the center of the molecule. CD titration experiments show that the synthetic protein binds two equivalents of Zn2+ stoichiometrically, and the Zn2+ induced conformational changes are completely reversible by addition of EDTA. NCp7 and its S-acetamidomethylated analog (NCp7-Acm), devoid of the zinc co-ordination centers, exhibit preferential binding to RNA with a Kd = approximately 10(-9) M irrespective of the cysteine modification as determined by filter binding assays. The binding affinity of the NCp7 protein to single-stranded DNA is lower than to RNA. Binding to double-stranded DNA is lower than to ssDNA. The NCp7-Acm protein exhibits reduced single-stranded DNA binding affinity compared to the unmodified protein. Nucleic acid binding analyses with the fragments of NCp7 protein suggest that two basic amino acid stretches are involved in RNA binding of the NCp7.
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PMID:Conformational and nucleic acid binding studies on the synthetic nucleocapsid protein of HIV-1. 842 19

Calcium ions are required for fusion of a wide variety of artificial and biological membranes. To examine the role of calcium ions for cell fusion mediated by interactions between CD4 and the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (gp120-gp41), we used two experimental systems: (i) cells expressing gp120-gp41 and its receptor CD4, both encoded by recombinant vaccinia viruses, and (ii) chronically infected cells producing low levels of HIV-1. Fusion was measured by counting the number of syncytia and by monitoring the redistribution of fluorescence dyes by video microscopy. Syncytia did not form in solutions without calcium ions. Addition of calcium ions partially restored the formation of syncytia. EDTA and EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] blocked syncytium formation in culture media containing calcium ions. Membrane fusion as monitored by fluorescence dye redistribution also required calcium ions. Cell fusion increased with an increase in calcium ion concentration from 100 microM to 10 mM but was not affected by magnesium ions in the concentration range from 0 to 30 mM. Fibrinogen and fibronectin did not promote fusion in the absence or presence of Ca2+. Binding of soluble CD4 to gp120-gp41-expressing cells was not affected by Ca2+ and Mg2+. We conclude that Ca2+ is involved in postbinding steps in cell fusion mediated by the CD4-HIV-1 envelope glycoprotein interaction.
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PMID:Calcium ions are required for cell fusion mediated by the CD4-human immunodeficiency virus type 1 envelope glycoprotein interaction. 843 34


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