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W L Fisher

Publications and source records attributed to W L Fisher.

5 recordsLinked to original sources
PubMed1993

HIV-1 reverse transcriptase: inhibition by 2',5'-oligoadenylates.

2',5'-Oligoadenylates (2-5A) and derivatives are noncompetitive inhibitors of primer/HIV-1 reverse transcriptase complex formation. The mechanism and specificity of this inhibitory action of 2-5A and 2-5A derivatives have been evaluated with 2-5A molecules modified in ribosyl moiety, chain length, extent of 5'-phosphorylation, and 2',5'-phosphodiester linkage. UV covalent cross-linking of preformed complexes of p66/p66 homodimer or p66/p51 heterodimer recombinant HIV-1 reverse transcriptase and the primer analog pd(T)16 allowed analysis of the initial step in HIV-1 reverse transcriptase-catalyzed DNA synthesis. Utilizing this primer binding assay, it is demonstrated that 2-5A and 2-5A derivatives inhibit the binding of pd(T)16 to HIV-1 reverse transcriptase. This inhibition is specific for the 2',5'-internucleotide linkage in that the corresponding 3',5'-adenylate derivatives do not exhibit inhibitory activity. Enhanced inhibitory properties were observed following modifications of the 2-5A molecule which result in an increase in hydrophobicity. Replacement of the D-ribosyl moiety of 2-5A with the 3'-deoxyribosyl moiety increased the inhibition of primer/HIV-1 reverse transcriptase complex formation 15-20%. 2',5'-Phosphorothioate substitution yielded the most effective inhibitors, with Ki's of 7-13 microM. In all cases, inhibition of primer/HIV-1 reverse transcriptase complex formation showed a preference for the 5'-triphosphate moiety. Nonphosphorylated derivatives were not inhibitory; 5'-monophosphate derivatives exhibited little or no inhibition. The inhibition of primer binding to HIV-1 reverse transcriptase correlated well with the inhibition of DNA-directed DNA synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1987

Cellular and humoral immunity to Leishmania major in genetically susceptible mice after in vivo depletion of L3T4+ T cells.

Depletion of critical T cell subsets in vivo by treatment with anti-L3T4 antibody (mAb GK1.5) enables BALB/c mice to heal subsequent Leishmania major infection. To investigate the mechanisms by which healing is established, anti-leishmania cellular and humoral responses in anti-L3T4-treated BALB/c mice were compared to those in control BALB/c and genetically resistant C57BL/6 mice. Lymph node and spleen cells were harvested from L. major-infected animals at 1, 2, 3, 4, and 8 wk post-infection and examined in vitro for concanavalin A- or L. major antigen (either promastigote or amastigote)-induced IFN-gamma production. Serum was harvested for Western blot analysis against L. major promastigote antigens. Lymph node cells from resistant C57BL/6 mice generated Leishmania antigen-induced IFN-gamma that was maximal by 3 wk; spleen cell IFN-gamma production peaked a week later. Lymph node and spleen cells from susceptible BALB/c mice generated minimal levels of IFN-gamma activity in response to Leishmania antigen stimulation throughout the experiment. Lymph node and spleen cells from BALB/c mice which had been pretreated with GK1.5 generated IFN-gamma in response to Leishmania antigens in vitro at levels that approached those generated by C57BL/6 mice. When splenic mRNA from infected animals was hybridized with a labeled murine IFN-gamma cDNA probe, there were corresponding differences in the amount of IFN-gamma message present, demonstrating that the differences observed in IFN-gamma production in vitro were also apparent in vivo, and were due to differences in transcription. In contrast to C57BL/6 mice which generated only a limited array of Leishmania-specific antibodies, BALB/c mice produced antibodies which reacted with a large number of Leishmania antigens. The GK1.5-treated BALB/c mice developed Leishmania-specific antibodies at a slower rate than did untreated BALB/c mice. However, by 8 wk after infection, the humoral responses of the anti-L3T4-treated BALB/c mice and the untreated BALB/c mice were comparable. These data document the kinetics of ascending immunity from the draining local lymph nodes to the spleen and confirm, both in vitro and in vivo, the correlation of IFN-gamma production with control of infection in leishmaniasis. Further, an L3T4+ T cell subpopulation may be incriminated in the failure of genetically susceptible BALB/c mice to activate curative cell-mediated immunity in response to Leishmania antigens.

Animals↗
PubMedDate not supplied

CCHS and home care.

Caring for a child with CCHS at home can be a challenge to home care nurses. Family support and advocacy are imperative.

Child↗