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

It has been shown that human CD4 expressed in nonhuman cells does not support HIV-1 entry into those cells and that components from human cells in addition to CD4 are required to overcome the block. We have used human red blood cells (huRBC) as a source for the accessory components since their membrane composition is less complex than that of nucleated cells and they are well characterized. Components were transferred by fusion of huRBC to nonhuman CD4(+) cells mediated by influenza hemagglutinin or polyethylene glycol. The RBC-modified nonhuman CD4(+) cells were labeled with fluorescent markers and incubated with gp 120-gp41-expressing cells labeled with a different fluorescent probe. Fusion between RBC- modified nonhuman CD4(+) cells and gp 120--gp41-expressing cells was quantified by fluorescence video microscopy. Human erythrocyte components transferred to nonhuman CD4+ cells conferred HIV-1 envelope glycoprotein-mediated fusion susceptibility to those cells. The fusion was enhanced by pretreatment of the erythrocytes for 10 min at 56 degrees. No gp 120--gp41-mediated fusion was observed when components from nonhuman RBC were transferred to nonhuman CD4+ cells. Human cell lines with pre-RBC characteristics (K562-CD4) also supported HIV-1 envelope glycoprotein-mediated fusion.
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PMID:Heat-resistant factors in human erythrocyte membranes mediate CD4-dependent fusion with cells expressing HIV-1 envelope glycoproteins. 862 37

Interference of binding of Tat protein to TAR RNA in HIV-1-infected cells may be a useful therapeutic strategy for AIDS. An electrophoretic assay to screen potential low-molecular-weight (< 2 kDa) Tat antagonists has been established. A radiolabeled TAR RNA fragment (delta TAR) is retarded in mobility when bound by a Tat peptide-polyethylene glycol conjugate (Tat-PEG), which is used in place of the Tat protein. The assay determines the ability of a potential antagonist to compete with Tat-PEG for binding to delta TAR, as measured by interference with the gel shift of delta TAR. To discriminate between specific and nonspecific interactions, the assay is done in the absence or the presence of a 250-fold molar excess of tRNA.
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PMID:Use of a polyethylene glycol-peptide conjugate in a competition gel shift assay for screening potential antagonists of HIV-1 Tat protein binding to TAR RNA. 874 81

An enzyme-linked immunosorbent assay (ELISA) for IgG using three glycolipid antigens from Mycobacterium tuberculosis in 65 tuberculosis (TB) patients and 50 healthy control subjects was performed. The circulating immune complexes (CICs) were isolated by precipitation with polyethylene glycol 6000 (PEG). This method associated to ELISA measured the specific antibodies present in these CICs. PEG [optical density (OD) 280] was shown to be significantly elevated (P < 0.001) in tuberculous samples. The concentrations of IgG antibodies complexed to the three glycolipid antigens were shown to be higher in patient with tuberculosis than in normal control subjects (P < 0.001). No correlation was observed between levels of free and CIC-bound antibodies. These antibodies isolated from CICs were responsible for almost all of the false-negative serological results. However, great heterogeneity was noticed depending on the antigen used, showing a more positive ELISAs against DAT (77%) than against LOS (71%) or PGLTb1 (18.5%). No correlation was established between the presence of specific CIC-complexed IgG and the bacteriological load or the tuberculosis localization (pulmonary vs. extrapulmonary). The sensitivity of ELISA for CIC-complexed IgG to DAT and LOS was lower in HIV-infected TB patients. From these results, we conclude that detection of complexed IgG DAT and LOS glycolipid antigen will be useful as a complementary technique for the serodiagnosis of tuberculosis.
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PMID:Circulating immune complexes in human tuberculosis sera: demonstration of specific antibodies against Mycobacterium tuberculosis glycolipid (DAT, PGLTb1, LOS) antigens in isolated circulating immune complexes. 906 6

Cellular cytotoxicity may be an important defense in the control of HIV progression. In the present study antibodies were attached to peripheral blood mononuclear cells (PBMC) by exposing them to polyethylene glycol and phthalate oil in the presence of HIV human hyperimmune IVIG (HIVIG). The attachment procedure is known as "franking" and the resultant cytotoxicity is termed "antibody-directed." The majority of the cells that are franked with attached HIVIG are CD16+ (Fc gamma RIII), placing them in the natural killer cell population. Franking increased the cytotoxicity of PBMC from both healthy controls and HIV-seropositive patients approximately fourfold compared to conventional antibody-dependent cellular cytotoxicity using CEM cells coated with HIV gp120 antigen as targets. Use of anti-HIV monoclonal antibodies for franking was less efficient than polyclonal HIVIG. The HIVIG-franked PBMC suppressed p24 production of in vitro HIV IIIb-infected human PBMC. The ability of HIVIG to enhance and direct cytotoxicity to HIV targets may suggest a new therapeutic approach to HIV control.
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PMID:Antibody-directed natural cytotoxicity results in enhanced killing of HIV gp120-coated CEMNKR cells. 914 74

The Mpl ligands are a family of closely related hematopoietic growth factors that bind to the thrombopoietin receptor, c-Mpl. In addition to the endogenous Mpl ligand, thrombopoietin, two recombinant Mpl ligands, recombinant thrombopoietin and pegylated megakaryocyte growth and development factor (PEG-MGDF) are under investigation. Endogenous thrombopoietin regulates most of the normal production of platelets but also is essential for the normal development of other lineages. When recombinant thrombopoietin or PEG-MGDF is administered to normal animals or humans, there is a dose-dependent increase in the platelet count but no effect on leukocytes or erythrocytes. When administered following chemotherapy in animal models or humans, Mpl ligands reduce the duration and sometimes the degree of thrombocytopenia. The Mpl ligands also may be effective in reducing the thrombocytopenia of patients with HIV infection, liver disease, myelodysplasia, or after plateletpheresis.
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PMID:In vivo effects of Mpl ligand administration and emerging clinical applications for the Mpl ligands. 920 31

A chemotaxis chamber has been developed to analyze both the velocity and the directionality of individual T cells in gradients of high molecular mass molecules over long periods of time. Employing this chamber, it is demonstrated that syncytia induced by HIV in SUP-T1 cell cultures release two T cell chemoattractants with approximate molecular masses of 30 and 120 kDa. Neither uninfected single cells nor polyethylene glycol-induced syncytia release detectable chemoattractant, suggesting that these chemoattractants are linked to HIV infection. Soluble gp120 functions as a T cell chemoattractant and the addition of anti-gp120 antibody to syncytium-conditioned medium blocks the high molecular mass chemoattractant activity but not the low molecular mass activity. The addition of anti-CD4 antibody to syncytium-conditioned medium also blocks the high molecular mass chemoattractant activity but not the low molecular mass activity. These results demonstrate that HIV-induced T cell syncytia release a low and a high molecular mass T cell chemoattractant, and suggest that the high molecular mass factor is gp120 and that it functions through the CD4 receptor.
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PMID:T cell syncytia induced by HIV release. T cell chemoattractants: demonstration with a newly developed single cell chemotaxis chamber. 939 16

The use of synthetic oligonucleotides as possible drugs for human therapy is usually hampered by their low in vivo stability and capacity to achieve high concentrations at their cellular targets. To overcome this, it has been suggested that they be modified chemically. Among the various options, conjugation with short- and long-chain polyethylene glycols (PEGs) has several advantages: PEG is nontoxic and very soluble, reduces immunogenic reactions, and increases the stability of the conjugated molecules. PEG is generally joined to oligonucleotides while bound to the insoluble solid-phase supports, after their synthesis, which does not allow for their being easy scaled up. The use of the liquid-phase approach as an alternative synthetic process, utilizing the PEG polymer both as a soluble, inert synthetic support and a stabilizing agent of the oligonucleotide, is proposed. A new protocol has been set up, characterized by a stable phosphate bond between the support and the oligonucleotide. This method has been tested on a 12mer previously investigated as an antisense agent against HIV. The PEG-conjugated 12mer was efficiently synthesized and purified. It was found that the high-molecular mass PEG chain results in enzymatic stability and does not interfere with the formation of the duplex with its nucleic acid target.
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PMID:Synthesis and characterization of high-molecular mass polyethylene glycol-conjugated oligonucleotides. 940 51

Electrospray ionization mass spectrometry (ESI-MS) has been used to study the noncovalent complexes formed from the interaction between HIV-1 Tat peptide and Tat protein with TAR RNA. Both positive ion and negative ion ESI mass spectra showed a maximum stoichiometry of 3:1 between Tat peptide and TAR RNA. However, the higher order complexes only occurred at high relative concentrations of Tat peptide. The 1:1 Tat peptide-TAR RNA complex is believed to involve only specific interactions, whereas the higher order complexes involve nonspecific interactions. Relative binding affinities between Tat peptide and TAR RNA and its various mutants (TAR missing the three-nucleotide bulge, TAR with a poly(ethylene glycol) linker in the bulge region, and TAR with a poly(ethylene glycol) linker in the loop region) can be differentiated by competitive binding experiments and ESI-MS measurements. The gas phase mass spectrometry experiments are consistent with solution phase studies, as they show that mutations in the bulge region reduce TAR RNA affinity to Tat peptide.
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PMID:HIV-1 Tat peptide binding to TAR RNA by electrospray ionization mass spectrometry. 941 17

A total of 234 pools were prepared from 10,692 consecutive serum samples negative for antibodies to human immunodeficiency virus type 1 (HIV-1) and HIV-2 collected at five virological laboratories (average pool size, 45 serum samples). Pools were screened for the presence of HIV-1 RNA by a modified commercial assay (Amplicor HIV-1 Monitor test) which included an additional polyethylene glycol (PEG) precipitation step prior to purification of viral RNA (PEG Amplicor assay). The sensitivity of this assay for HIV-1 RNA detection in individual serum samples within pools matches that of standard commercial assays for individual serum samples, i.e., 500 HIV-1 RNA copies per ml. Five pools were identified as positive, and each one contained one antibody-negative, HIV-1 RNA-positive serum sample, corresponding to an average of 1 infected sample per 2,138 serum samples. Retrospective analysis revealed that the five HIV-1 RNA-positive specimens originated from individuals who had symptomatic primary HIV-1 infection at the time of sample collection and who were also positive for p24 antigenemia. We next assessed the possibility of performing the prepurification step by high-speed centrifugation (50,000 x g for 80 min) of 1.5-ml pools containing 25 microl of 60 individual serum samples, of which only 1 contained HIV-1 RNA (centrifugation Amplicor assay). The sensitivity of this assay also matches the sensitivities of standard commercial assays for HIV-1 RNA detection in individual serum samples. The results demonstrate that both assays with pooled sera can be applied to the screening of large numbers of serum samples in a time- and cost-efficient manner.
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PMID:Detection of human immunodeficiency virus type 1 (HIV-1) RNA in pools of sera negative for antibodies to HIV-1 and HIV-2. 962 Mar 72

The effects of IL-2 therapy on lymphoproliferative responses to mitogens, recall antigens and HIV epitopes were studied in asymptomatic HIV-infected patients enrolled in a phase II study of intermittent continuous intravenous (Ci.v.) IL-2 and subcutaneous infusions of polyethylene glycol-modified (PEG) IL-2. Sixteen consecutive patients randomized to receive Ci.v. IL-2 (n = 5), PEG IL-2 (n = 7) or anti-viral therapy alone (n = 4) were studied. All patients were vaccinated with tetanus toxoid (TT) before receiving therapy. Proliferative responses to phytohaemagglutinin (PHA), soluble anti-CD3, TT, streptokinase/streptodornase (SK/SD) and 11 previously described HIV-specific T-helper epitopes from gag and env were studied at weeks 0, 16, 30 and 48. Median CD4+ lymphocyte increases of 272 and 255CD4+ cells/microl were observed in the Ci.v. IL-2 and PEG IL-2 groups at week 48, while decreasing by 104 cells/microl in the anti-retroviral therapy alone group. At each time point proliferative responses to PHA, anti-CD3, TT and SK/SD were not different between treatment arms. Similarly, no differences in responses to HIV epitopes were found between the groups and no new responses to HIV epitopes were detected. IL-2 therapy results in a significant increase in peripheral blood CD4+ lymphocyte count, but this increase is not associated with quantifiable improvements in lymphoproliferative responses to mitogens, recall or HIV antigens.
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PMID:Effects of IL-2 therapy in asymptomatic HIV-infected individuals on proliferative responses to mitogens, recall antigens and HIV-related antigens. 969 88


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