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)

The activity of human immunodeficiency virus 1 (HIV-1) protease has been examined as a function of solvent composition, incubation time, and enzyme concentration at 37 degrees C in the pH 4.5-5.5 range. Glycerol and dimethyl sulfoxide inhibit the enzyme, while polyethylene glycol and bovine serum albumin activate the enzyme. When incubated at a concentration of 50-200 nM, the activity of the protease decreases irreversibly with an apparent first-order rate constant of 4-9 x 10(-3) min-1. The presence of 0.1% (w/v) polyethylene glycol or bovine serum albumin in the reaction buffer dramatically stabilizes enzyme activity. In the absence of prolonged incubation of the enzyme at submicromolar concentration, the specific activity of HIV-1 protease in buffers of either high or low ionic strength is constant over the enzyme concentration range of 0.25-5 nM, indicating that dissociation of the dimeric protease, if occurring, can only be governed by a picomolar dissociation constant. Similarly, the variation of the specific activity of HIV-2 protease over the enzyme concentration of 4-85 nM is consistent only with a dimer dissociation constant of less than 10 nM. We conclude that: 1) the assumption of a nondissociating HIV-1 protease is a valid one for kinetic studies of tight-binding inhibitors where nanomolar concentrations of the enzymes are employed; 2) stock protease solutions of submicromolar concentration in the absence of activity-stabilizing compounds may lead to erroneous kinetic data and complicate mechanistic interpretations.
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PMID:Activity and dimerization of human immunodeficiency virus protease as a function of solvent composition and enzyme concentration. 140 Mar 18

Interferon-gamma (IFN-gamma) has been shown to inhibit human immunodeficiency virus (HIV) replication in macrophages. However, the site of its effect on the HIV infectious cycle is unknown. We show here that IFN-gamma inhibits the transactivation of HIV long terminal repeat (LTR) during viral infection and that it antagonizes tat effect in HT4LacZ-1 cells. HT4LacZ-1 is an indicator CD4+ HeLa cell line for HIV infectivity, because it harbors a HIV LTR-LacZ gene susceptible to transactivation by tat. It was used in combination with a computer-assisted image analyzer to quantify: (i) the number of transactivated foci following HIV infection, (ii) their individual level of transactivation, and (iii) the fusion potency of infected cells. IFN-gamma induced a 75% decrease of the number of transactivated foci following infection of HT4LacZ-1 cells by HIV. The remaining 25% foci still susceptible to transactivation were transactivated at a lower level than in control cultures, and the fusion potency of infected cells was strongly decreased. IFN-gamma acted after HIV entry into the cell and independently of reverse transcription. IFN-gamma antagonized tat-induced LTR transactivation: it inhibited transactivation of HT4LacZ-1 cells when tat was provided either from a SV40-based expression vector of tat or by polyethylene glycol-induced cell fusion with HeLa-tat-III cells. These results suggest that IFN-gamma affects the expression or the activity of cellular factors interacting with tat and that the high level of IFN-gamma production associated with HIV infection plays a role in the establishment of HIV latency.
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PMID:Antagonistic effect of interferon-gamma on tat-induced transactivation of HIV long terminal repeat. 140 Mar 76

X-ray quality crystals of an Fab fragment from an antipeptide monoclonal antibody (R/V3-50.1) that recognizes the principal neutralizing determinant (PND) of the gp120 glycoprotein of human immunodeficiency virus type 1 (HIV-1) (MN isolate) were grown as uncomplexed and peptide complexed forms. Crystals of the free Fab grew from high salt in orthorhombic space groups P2(1)2(1)2(1) and I222 and from polyethylene glycol in space groups P1 and P2(1). Seeds from either the P1 and P2(1) native (uncomplexed) Fab crystals induced nucleation of crystals of the Fab complexed to a 16-residue synthetic peptide corresponding to the PND when streak seeded into preequilibrated solutions of this complex. Data were collected from these complex crystals and from each of the four native Fab forms to at least 2.8 A resolution. The genes for the variable domain of the Fab were cloned and sequenced and the primary amino acid sequence was deduced from this information. Knowledge of the three-dimensional structure of this Fab-peptide complex will be important in the understanding of the PND of HIV-1 and its recognition by neutralizing monoclonal antibodies.
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PMID:Crystallization, sequence, and preliminary crystallographic data for an antipeptide Fab 50.1 and peptide complexes with the principal neutralizing determinant of HIV-1 gp120. 143 87

The angiotensin I-based peptide Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu-Leu-Glu-Glu-Ser yields angiotensin I (Ang I) and Leu-Glu-Glu-Ser upon hydrolysis by the human immunodeficiency virus type 1 (HIV-1) protease, but not by human renin. N-terminal sequencing of the reaction products showed that the HIV-1 protease cleaved exclusively at the Leu-Leu bond. The rate of Ang I formation can be measured by a radioimmunoassay, since the parent peptide has minimal cross reactivity in this assay. The rate of enzymatic hydrolysis is maximal at pH 4.5-5.0 and at an ionic strength of 1 M. At 37 degrees C, 0.1 M Na acetate buffer, pH 5.0, 1 M NaCl, 10% glycerol, 5% ethylene glycol, 1 mg/ml bovine serum albumin, and 3 mM EDTA, the reaction obeys Michaelis-Menten type kinetics with Km = 17.2 +/- 3.5 microM and kcat = 2.30 +/- 0.33 min-1. The activity assay readily quantitates as little as 0.25 nM of HIV-1 protease. The production of Ang I by the HIV-1 protease is inhibited in the presence of a HIV-1 protease inhibitor. The newly discovered substrate is relatively insensitive to human or monkey serum. Therefore, the effect of sera from 20 patients with advanced acquired immunodeficiency disease syndrome (AIDS) on Ang I production in the above assay system was examined. Results of this study indicate that it may be possible to adapt the above Ang I-based system to determine blood levels of HIV-1 protease inhibitors in AIDS patients during clinical trials.
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PMID:An ultrasensitive human immunodeficiency virus type 1 protease radioimmuno rate assay with a potential for monitoring blood levels of protease inhibitors in acquired immunodeficiency disease syndrome patients. 144 99

Adenosine deaminase (ADA) deficiency is one the causes of severe combined immunodeficiency syndrome. Treatment was, until now, based on bone marrow transplantation. HLA identical bone marrow transplantation yields excellent results while those of HLA haploidentical bone marrow transplantation are not so good. A new therapeutic approach was developed recently, consisting of the intramuscular infusion of ADA enzyme covalently linked to polyethylene glycol (PEG-ADA). We report the results of this treatment in a 14 month-old child presenting with a partial form of ADA deficiency revealed by an opportunistic infection. This treatment corrected the immunodeficiency and the biochemical abnormalities as well. PEG-ADA infusions were well tolerated. The onset of an immunization against the ADA enzyme led to a drop in immunologic functions, which could be partially overcome by more frequent (biweekly) administration of the product. After a 18 month-follow-up the child is doing well, living normally at home. PEG-ADA represents a possible alternative for children presenting with ADA deficiency without any available HLA identical donor.
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PMID:[Treatment of adenosine deaminase deficiency with adenosine deaminase combined with polyethylene glycol]. 149 22

Patients with common variable immunodeficiency (CVI) have decreased immunoglobulin levels resulting in frequent infections. Although previous studies have suggested that the B cell is intrinsically defective, numerous T cell deficiencies, including reduced interleukin-2 (IL-2) production, have been described. Since the addition of T cell cytokines to CVI B cells can increase Ig secretion in vitro, hypogammaglobulinemia in CVI may be due to defective T cell functions. To assess this possibility directly, we treated five CVI patients intravenously with a new biologic, human recombinant IL-2 conjugated to polyethylene glycol. Doses were 250,000 IU/m2 weekly for Weeks 1-4, 500,000 IU/m2 for Weeks 5-8, and 10(6) IU/m2 for Weeks 9-12. During and after treatment, B cells of all patients secreted 10- to 1000-fold more Ig in vitro. There was also a striking improvement in T cell helper activity since T cells of treated patients could induce 10- to 10,000-fold increases in Ig secretion by B cells from normal donors. No increase was seen in serum Igs during the study, but the anti-tetanus antibody of the IgG isotype could be detected in cell culture supernatants. Whether the effects of infused polyethylene glycol IL-2 are mediated through T or B cells, or both, is still unknown. However, these data reinforce the concept that CVI B cells may be competent, but, lacking essential T cell growth factors, in vivo maturation to Ig production does not occur.
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PMID:Restoration of immunoglobulin secretion in vitro in common variable immunodeficiency by in vivo treatment with polyethylene glycol-conjugated human recombinant interleukin-2. 160 51

A simple and rapid solid-phase reverse transcriptase assay was developed based on the use of poly(rA):oligo(dT)12-18 as template primer immobilized on DEAE cellulose paper squares to detect human immunodeficiency virus (HIV) and/or other retroviruses in cell culture supernatants. It was found that PEG (per se) -up to 4% concentrations (w/v)--did not inhibit reverse transcriptase activity. Optimal conditions of the assay were determined. This solid-phase technique is much faster and more convenient than the methods described previously.
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PMID:A solid phase reverse transcriptase micro-assay for the detection of human immunodeficiency virus and other retroviruses in cell culture supernatants. 169 Dec

Retroviral RNA is copied into DNA by reverse transcriptase when the viral genome enters into its life cycle. In the case of human immunodeficiency virus (HIV), massive amounts of unintegrated viral DNA reportedly appear in the early phase of primary infection. However, the relationship between the accumulation of this DNA and the cytopathic effect (CPE) remains obscure. In an attempt to delineate this association, we examined the appearance of the unintegrated viral DNA by means of two experimental systems: (1) primary infection of highly susceptible MOLT-4#8 cells and (2) induction of CPE by cell-fusion of persistently infected MOLT-4#8 cells. A correlation was observed between the accumulation of unintegrated viral DNA and the appearance of CPE, both when MOLT-4#8 cells were infected with cell-free virus and when persistently infected MOLT-4#8 cells were co-cultured with uninfected cells. Persistently infected cells did not fuse spontaneously in culture, because they lack the CD4-molecule on their surfaces. However, when treated with polyethylene glycol (PEG), the cells fused, exhibited ballooning degeneration, and released fewer viruses. After PEG treatment, unintegrated viral DNA also appeared. Since such DNA is generally not detected in persistently infected cells, it is possible that some cellular mechanism exists to suppress the synthesis of viral DNA and that the fusion induced by PEG treatment cancels the suppression. Treatment of persistently infected cells with Ca2+ ionophore and Ca2+ antagonist also resulted in the accumulation of unintegrated viral DNA and inhibited virus release. These findings suggest that the induction of unintegrated HIV DNA may be an effective strategy for reducing the release of the virus.
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PMID:Unintegrated DNA in cells infected in vitro with human immunodeficiency virus (HIV): a new approach to suppression of virus release. 169 87

Culture supernatants from the rabbit macrophage cell line 6083 infected with a retrovirus, human immunodeficiency virus type 1 (HIV-1), were negative for reverse transcriptase (RT) expression although the line was shown to be productively infected by all other criteria tested. Supernatants from uninfected cultures of 6083, the human monocyte line U937, and from freshly isolated peripheral human monocytes, were found to contain a monocyte-derived inhibitory factor (MDIF) which interferes with a standard assay for RT. MDIF is a heat-labile activity of approximately of 40 kD. Both substrates and products of the reverse transcriptase assay are degraded by MDIF which is not affected by reduction and alkylation of disulfide bonds. MDIF is inhibited by the addition of a particular thioated oligonucleotide (S-dG30) to the reaction mixture but this addition also inhibits RT. The optimum method to minimize MDIF interference in the RT assay is by addition of ethylene glycol bis-(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid (EGTA); MDIF requires divalent cations for activity and has a strong preference for calcium which is preferentially chelated by EGTA. The potential presence of this inhibitory activity should be considered when using RT levels as a measure of retroviral infection.
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PMID:A monocyte-derived factor interferes with detection of reverse transcriptase in HIV-1 infection. 170 43

Cell-free human immunodeficiency virus type-1 (HIV-1) was precipitated from archival serum with polyethylene glycol (PEG), and HIV-1 RNA was detected and quantified by reverse transcription and amplification in a nested polymerase chain reaction (PCR). The assay of end-point dilutions cDNA in nested PCRs allowed an estimation of the minimum RNA copies per unit volume of serum. RNA titres correlated with the classification of HIV-1 infection by CDC disease groups (30 patients). The geometric mean titres of HIV-1 serum RNA from patients grouped by disease stage gave minimum estimates of 340 and 400 virions per millilitre of serum in CDC groups II and III (n = 6 and 10, respectively) and 4,240 virions per millilitre in CDC group IV (n = 14). An overall fall in viral titre measured in this way was observed in 3 patients during zidovudine treatment. HIV-1 titres increased in a further 4 patients when therapy was interrupted, stopped, or complicated by secondary infection.
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PMID:Direct measurement of viraemia in patients infected with HIV-1 and its relationship to disease progression and zidovudine therapy. 194 Aug 82


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