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

UV irradiation provides a simple and efficient way to minimize contamination or false positivity which often occurs in laboratories performing routine PCR tests. Here, we characterize several parameters of the effect of UV irradiation on DNA template, primers, deoxynucleoside triphosphate and Taq polymerase. UV irradiation of DNA results in the formation of pyrimidine dimers and thus prevents them from being effective templates in subsequent PCR. Reduction of the HIV DNA templates in polypropylene microcentrifuge tubes by more than 1000-fold can be achieved by UV irradiation. The sensitivity of the primers is sequence- and concentration-dependent. Oligonucleotides with neighboring thymine bases are more susceptible to UV than those without. Taq polymerase is highly UV sensitive, whereas deoxynucleotide triphosphate is relatively UV resistant.
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PMID:Use of UV irradiation to reduce false positivity in polymerase chain reaction. 186 51

The inhibitory effects of a series of antiviral compounds on human immunodeficiency virus type 1 (HIV-1) were evaluated in a plaque assay (PA) in MT-4 cells and a focal immunoassay (FIA) in CD4+ HeLa cells. Similar 50% inhibitory concentrations (IC50) were obtained for the sulfated polysaccharides when measured by PA or FIA: the IC50 values of dextran sulfate and pentosan polysulfate were 0.8 microgram/ml and 0.35 microgram/ml, respectively. Also, comparable IC50 values (ranging from 1.42 to 2.71 microM) were obtained for purine 2',3'-dideoxyribosides (i.e. DDA, DDI and DDG) when evaluated by PA or FIA. In contrast, the IC50 values of pyrimidine 2',3'-dideoxyribosides were invariably 4- to 10-fold lower when monitored by PA than FIA: the IC50s of AZT, D4T and DDC in the PA were 0.015, 0.094 and 0.038 microM, respectively, and in the FIA were 0.062 microM, 0.29 microM and 0.46 microM, respectively. The differential anti-HIV-1 activities found with AZT, D4T and DDC in the PA and FIA systems may at least be related in part to differences in the metabolism of the compounds (i.e. phosphorylation by thymidine kinase or 2'-deoxycytidine kinase) between MT-4 and CD4+ HeLa cells. The novel anti-HIV-1 compounds tetrahydro-imidazo[4,5,1-jk][1,4]-benzodiazepin-2(1H)-thione (TIBO) derivatives, R82150 and R82913, and the acyclouridine derivative 1-[(2-hydroxyethoxy)methyl]-6-phenylthiothymine (HEPT) were also more inhibitory to HIV-1 in the PA than FIA system. The IC50 values of R82150, R82913 and HEPT, as based on PA, were 0.005, 0.003 and 0.79 microM, respectively. Their IC50 values, as based on FIA, were 0.020 microM, 0.015 microM and 3.77 microM, respectively. The TIBO derivatives emerged as the most effective HIV-1 inhibitors of the compounds tested whether assayed by PA or FIA.
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PMID:Anti-HIV-1 activity of antiviral compounds, as quantitated by a focal immunoassay in CD4+ HeLa cells and a plaque assay in MT-4 cells. 198 Jan 26

The structural requirements for the antiviral activity of pyrimidine nucleosides against HIV-1 virus was evaluated with the Hansch SAR analysis. Antiviral activity is best related to the hydrophobicity and steric (L and B3) properties of the substituent at the C5 of pyrimidine ring. Further, the antiviral activity is related to B4 of the substituent at position 3' of the sugar ring with a positive slope. The activity of both uracil and cytosine derivatives can be related to their structure by the same equations, which indicates that the SARs are similar in these two groups of congeners. These results suggest that compounds with a small substituent at the 5 position of the pyrimidine ring and a flat substituent at the 3' position of the sugar ring will be the most active compounds against HIV-1 virus.
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PMID:Quantitative structure-activity relationships (QSARs) of pyrimidine nucleosides as HIV-1 antiviral agents. 201 7

Oxygen-sulfur exchange at the C-4 carbonyl of several modified pyrimidine nucleosides, including 3'-azido-3'-deoxythymidine (AZT), is described in an effort to enhance the lipophilicity and, thereby, the delivery to the central nervous system of the sulfur analogues without compromising the anti-HIV activities of the parental structures. Preparation of 3'-azido-3'-deoxy-4-thiothymidine (3) proceeded from 4-thiothymidine (1) and utilized the same methodology developed for the initial synthesis of AZT. Thiation of 2',3'-didehydro-3'-deoxythymidine (4a) and 2',3'-didehydro-2',3'-dideoxyuridine (4c) was carried out with Lawesson's reagent on the corresponding 5'-O-benzoate esters, 4b and 4d, to give 5a and 5c, respectively. The latter, on alkaline hydrolysis, gave 2',3'-didehydro-3'-deoxy-4-thiothymidine (5b) and 2',3'-didehydro-2',3'-dideoxyuridine (5d), respectively. The same series of reactions were applied to the 5'-O-benzoate esters of 2',3'-dideoxyuridine (6a) and 3'-deoxythymidine (6b) to give 2',3'-dideoxy-4-thiouridine (7d) and 3'-deoxy-4-thiothymidine (7b), respectively. Characterization of the saturated and unsaturated thionucleosides included mass spectrometric studies. Under electron impact conditions, the thiated analogues gave more intense parent ions than the corresponding oxygen precursors. The lipophilicity of thymidine and the 3'-deoxythymidine derivatives are enhanced significantly, as indicated, by increases in corresponding P values (1-octanol-0.1 M sodium phosphate) upon replacement of the 4-carbonyl oxygens by sulfur. Compounds 5b, 5d, 7b, and 7d were evaluated for their effects on HIV-induced cytopathogenicity of MT-2 and CEM cells. Only 5b and 7b were moderately active in protecting both cell lines against the cytolytic effect of HIV. The inhibitory effects of analogues 5b, 5d, 7b, and 7d on thymidine phosphorylation by rabbit thymus thymidine kinase were evaluated. Only 3 showed moderate affinity (Ki = 54 microM) for the enzyme. The generally weak anti-HIV activities of the remaining thio analogues are consistent with correspondingly low susceptibilities to thymidine kinase phosphorylation as estimated from the respective Ki values of the synthetic nucleosides. However, the phosphorylation of the 5'-monophosphate derivatives to their respective 5'-triphosphates must also be considered in connection with the weak in vitro anti-HIV effects of these thiated compounds.
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PMID:Synthesis and in vitro evaluation of some modified 4-thiopyrimidine nucleosides for prevention or reversal of AIDS-associated neurological disorders. 215 6

A range of 2'-fluoro and 2',3'-difluoro analogues of pyrimidine deoxyribonucleosides have been synthesized and evaluated against human immunodeficiency virus (HIV-1) in a human lymphoblastoid cell line. Among these compounds, 1-(2,3-dideoxy-2-fluoro-beta-D-threopentofuranosyl)cytosine (12), 2',3'-didehydro-2',3'-dideoxy-2'-fluorocytidine (35), 1-(2,3-dideoxy-2,3-difluoro-beta-D-arabinofuranosyl)cytosine (41), and 3'-deoxy-2',3'-didehydro-2'-fluorothymidine (45) were found to have significant antiviral activity, with IC50 values of 0.65, 10, 10, and 100 microM, respectively. The structure-activity relationships are discussed.
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PMID:Synthesis and antiviral activity of monofluoro and difluoro analogues of pyrimidine deoxyribonucleosides against human immunodeficiency virus (HIV-1). 216 61

A series of acyclic and C-acyclic 7-deazapurine nucleosides have been synthesized and tested for antiviral activity. Reaction of the sodium salt of 2-amino-3,4-bis(aminocarbonyl)-5-(methylthio)pyrrole (6) with an appropriate electrophile gave pyrrole nucleosides which served as common intermediates to both the 7-deazaadenosine and the 7-deazaguanosine series. Several of these 5- and 5,6-substituted pyrrolo[2,3-d]pyrimidine nucleosides have shown activity against HIV virus in preliminary in vitro screens.
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PMID:Synthesis and antiviral activity of some acyclic and C-acyclic pyrrolo[2,3-d]pyrimidine nucleoside analogues. 216 63

(+-)-cis-[4-[(2,5-Diamino-6-chloropyrimidinyl)amino]-2- cyclopentenyl]carbinol (5a) was synthesized from 2-amino-4,6-dichloropyrimidine and cis-4-(hydroxymethyl)cyclopentenylamine (2a) by subsequent preparation of the 5-[(4-chlorophenyl)azo] derivative of the resulting pyrimidine (3a) and reduction of the azo moiety with zinc and acetic acid. The carbocyclic analogue of 2',3'-didehydro-2',3'-dideoxy 2-amino-6-chloropurine (6a) and the corresponding 8-azapurine (9a) were prepared from 5a. The carbocyclic 2',3'-didehydro-2',3'-dideoxy analogues of guanine (7a) and 2,6-diaminopurine (8a), and 8-azaguanine (10a) and 8-aza-2,6-diaminopurine (11a) were prepared from 6a and 9a, respectively. The corresponding 2',3'-saturated series of 2-amino-6-substituted-purine carbocyclic nucleosides was prepared following the same scheme starting with cis-4-(hydroxymethyl)cyclopentylamine (2b). Carbocyclic 2',3'-didehydro-2',3'-dideoxyguanosine (carbovir, 7a) emerged as a potent and selective anti-HIV agent. Its hydrolytic stability and its ability to inhibit the infectivity and replication of HIV in T-cells at concentrations of approximately 200-400-fold below toxic concentrations make carbovir an excellent candidate for development as a potential antiretroviral agent.
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PMID:Synthesis and anti-HIV activity of carbocyclic 2',3'-didehydro-2',3'-dideoxy 2,6-disubstituted purine nucleosides. 229 18

The synthesis and antiviral evaluation of a series of (+-)-3,5- dihydroxypentyl nucleoside analogues related to acyclic nucleoside antiviral agents are reported. All purine and pyrimidine nucleoside analogues described in this paper have been obtained from 1-amino-5-(benzyloxy)pentan-3-ol. A synthesis of this amine is reported from 1-(benzyloxy)but-3-ene after epoxidation and regiospecific diethylaluminum chloride catalyzed opening of the epoxide by trimethylsilyl cyanide. The compounds were tested in vitro in infected MRC5 and CEM cells. None of the compounds exhibited antiviral activity against HSV-1, HCMV, and HIV-1 with the exception of the guanine derivative 7, which inhibited the cytopathic effect of HSV-1 by 50% at 12.5 micrograms/mL.
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PMID:Synthesis of new (+-)-3,5-dihydroxypentyl nucleoside analogues from 1-amino-5-(benzyloxy)pentan-3-ol and their antiviral evaluation. 239 89

2',3'-Dideoxycytidine (ddCyd) is one of the most potent antiviral nucleosides for killing the human immunodeficiency virus (HIV). ddCyd is currently used in the treatment of severe HIV infections but due to its rapid clearance it must be administered to patients every 4 h reaching concentrations that are toxic. We have synthesized 2',3'-dideoxycytidine-5'-phosphate (ddCMP) as a prodrug, encapsulated it in human erythrocytes and found that it is dephosphorylated by endogenous pyrimidine nucleotidases and subsequently released by the cells as ddCyd. Encapsulated ddCMP does not affect erythrocyte metabolism and was not deaminated by cytidine deaminase. The dephosphorylation reaction has an apparent Km of 6mM, an optimum pH of 6.8 and is not inhibited by ATP or 2,3-bisphosphoglycerate. The efflux of ddCyd from the erythrocyte is a linear function of ddCyd concentration and relatively insensitive to nucleoside transporter inhibitors suggesting that ddCyd permeates the erythrocyte membrane predominantly by nonfacilitated diffusion. Thus, ddCMP-loaded erythrocytes might be used as endogenous bioreactors for ddCyd delivery in the treatment of HIV infection.
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PMID:Human red blood cells as bioreactors for the release of 2',3'-dideoxycytidine, an inhibitor of HIV infectivity. 255 18

Corticosteroids are used in treatment of a variety of human immunodeficiency virus (HIV)-related disorders. Preliminary reports of a temporal relationship between administration of these drugs to viral carriers and development of AIDS raised the possibility that they can modify the course of HIV infection. Because glucocorticoids can alter specific gene expression in at least one immunosuppressive murine retrovirus, mammary tumor virus, we explored the ability of dexamethasone (DXM) to upregulate chronic HIV replication or to alter transcription at the HIV-1 long terminal repeat (LTR). A clone of promonocytic cells chronically infected with HIV-1 could be converted to a productive state of replication by phorbol ester or halogenated pyrimidine exposure, yet was unperturbed by DXM used over broad concentrations (10(-4) to 10(-9) mol/L) and time intervals (24 to 96 hours). This unresponsiveness corresponded to the lack of a positive effect of DXM on HIV associated trans-activation in both monocytic and CD4+ T cells. These cells possessed the appropriate steroid receptors, as DXM downregulated Fc gamma type-I receptors in both normal and HIV-infected promonocytic cells. In addition, DXM could block the transcriptional enhancement of an HIV-LTR-linked reporter gene by phorbol ester, while leaving basal levels of HIV-LTR-directed transcription unperturbed. These data are discussed in the context of clinical reviews of short-term steroid use in HIV-infected individuals.
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PMID:Effect of glucocorticoids on chronic human immunodeficiency virus (HIV) infection and HIV promoter-mediated transcription. 275 16


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