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  • 1
    Online Resource
    Online Resource
    American Society for Microbiology ; 2002
    In:  Journal of Bacteriology Vol. 184, No. 15 ( 2002-08), p. 4134-4140
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 184, No. 15 ( 2002-08), p. 4134-4140
    Abstract: The 2-aminoethylphosphonate transaminase (AEPT; the phnW gene product) of the Salmonella enterica serovar Typhimurium 2-aminoethylphosphonate (AEP) degradation pathway catalyzes the reversible reaction of AEP and pyruvate to form phosphonoacetaldehyde (P-Ald) and l -alanine ( l -Ala). Here, we describe the purification and characterization of recombinant AEPT. pH rate profiles (log V m and log V m / K m versus pH) revealed a pH optimum of 8.5. At pH 8.5, K eq is equal to 0.5 and the k cat values of the forward and reverse reactions are 7 and 9 s −1 , respectively. The K m for AEP is 1.11 ± 0.03 mM; for pyruvate it is 0.15 ± 0.02 mM, for P-Ald it is 0.09 ± 0.01 mM, and for l -Ala it is 1.4 ± 0.03 mM. Substrate specificity tests revealed a high degree of discrimination, indicating a singular physiological role for the transaminase in AEP degradation. The 40-kDa subunit of the homodimeric enzyme is homologous to other members of the pyridoxalphosphate-dependent amino acid transaminase superfamily. Catalytic residues conserved within well-characterized members are also conserved within the seven known AEPT sequences. Site-directed mutagenesis demonstrated the importance of three selected residues (Asp168, Lys194, and Arg340) in AEPT catalysis.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2002
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 2
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 52, No. 5 ( 2008-05), p. 1630-1634
    Abstract: AMD070, a CXCR4 antagonist, has demonstrated antiretroviral activity in human immunodeficiency virus-infected patients. Since AMD070 is a substrate of cytochrome P450 3A4 and P-glycoprotein, both of which may be affected by ritonavir, we tested for a ritonavir effect on AMD070 pharmacokinetics. Subjects were given a single 200-mg dose of AMD070 on days 1, 3, and 17. Ritonavir (100 mg every 12 h) was dosed from day 3 to day 18. Blood samples to test for AMD070 concentrations were collected over 48 h after each administration of AMD070. Twenty-three male subjects were recruited. Among them, 21 completed the study, and 2 were discontinued for reasons other than safety. All adverse events were grade 2 or lower. AMD070 alone had the following pharmacokinetic features, given as medians (ranges): 3 h (0.5 to 4 h) for the time to peak blood concentration, 256 ng/ml (41 to 845 ng/ml) for the peak concentration ( C max ), 934 h·ng/ml (313 to 2,127 h·ng/ml) for the area under the concentration-time curve from 0 h to infinity (AUC 0-∞ ), 214 liters/h (94 to 639 liters/h) for apparent body clearance, and 4,201 liters (1,996 to 9,991 liters) for the apparent volume of distribution based on the terminal phase. The initial doses of ritonavir increased the C max of AMD070 [geometric mean (90% confidence interval)] by 39% (3 to 89%) and the AUC 0-∞ by 60% (29 to 100%). After 14 days of ritonavir dosing, the pharmacokinetic changes in AMD070 persisted. The plasma pharmacokinetics of ritonavir were consistent with previous reports. It is concluded that AMD070 concentrations were increased with concomitant ritonavir dosing for 14 days in healthy volunteers.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2008
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 3
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 63, No. 4 ( 2019-04)
    Abstract: AIDS Clinical Trial Group study A5202 (ClinicalTrials.gov identifier NCT00118898) was a phase 3b, randomized, partially blinded equivalence study of open-label atazanavir/ritonavir or efavirenz, plus either placebo-controlled tenofovir disoproxil fumarate/emtricitabine or abacavir/lamivudine, in treatment-naive adults living with HIV-1, evaluating efficacy, safety, and tolerability. We report an analysis of the contribution of participant characteristics to the disposition of tenofovir plasma concentrations. Tenofovir concentration data from a total of 817 individuals (88% of the total number of eligible patients randomly assigned to receive treatment in the TDF-containing arms of A5202) were available for analysis. Pharmacokinetic analysis was performed using nonlinear mixed-effects modeling. One- and two-compartment models with first-order absorption and first-order elimination were evaluated. An exponential error model was used for examination of interindividual variability (IIV), and a proportional and mixed-error model was assessed for residual variability. The final structural model contained two compartments with first-order absorption and elimination. IIV was estimated for apparent clearance (CL/F) and the first-order absorption rate constant ( k a ), and a proportional residual variability model was selected. The final mean parameter estimates were as follows: k a = 2.87 h −1 , CL/F = 37.2 liters/h, apparent volumes of the central and peripheral compartments = 127 and 646 liters, respectively, and apparent intercompartmental clearance = 107 liters/h. In addition to race/ethnicity, creatinine clearance and assignment to atazanavir/ritonavir or efavirenz were significantly associated with CL/F ( P 〈 0.001). In conclusion, race/ethnicity is associated with tenofovir oral CL in HIV-1 positive, treatment-naive adults. This covariate relationship raises questions about the possibility of differences in efficacy and risk of adverse events in different patient populations and suggests that examining preexposure prophylaxis regimens and tenofovir exposure in different race/ethnicity groups be considered.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 4
    In: Infection and Immunity, American Society for Microbiology, Vol. 79, No. 10 ( 2011-10), p. 3966-3977
    Abstract: We have previously reported that compromised interleukin 17A (IL-17A) production in the lungs increased susceptibility to infection with the invasive fungal pathogen Aspergillus fumigatus . Here we have shown that culturing lung cells from A. fumigatus -challenged mice ex vivo demonstrated Dectin-1-dependent IL-17A production. In this system, neutralization of IL-23 but not IL-6, IL-1β, or IL-18 resulted in attenuated IL-17A production. Il23 mRNA expression was found to be lower in lung cells from A. fumigatus -challenged Dectin-1-deficient mice, whereas bone marrow-derived dendritic cells from Dectin-1-deficient mice failed to produce IL-23 in response to A. fumigatus in vitro . Addition of recombinant IL-23 augmented IL-17A production by wild-type (WT) and Dectin-1-deficient lung cells, although the addition of IL-6 or IL-1β did not augment the effect of IL-23. Intracellular cytokine staining of lung cells revealed lower levels of CD11b + IL-17A + and Ly-6G + IL-17A + cells in A. fumigatus -challenged Dectin-1-deficient mice. Ly-6G + neutrophils purified from the lungs of A. fumigatus -challenged Dectin-1-deficient mice displayed lower Il17a mRNA expression but surprisingly had intact Rorc and Rora mRNA expression. We further demonstrated that Ly-6G + neutrophils required the presence of myeloid cells for IL-17A production. Finally, upon in vitro stimulation with A. fumigatus , thioglycolate-elicited peritoneal neutrophils were positive for intracellular IL-17A expression and produced IL-17A in a Dectin-1- and IL-23-dependent manner. In summary, Dectin-1-dependent IL-17A production in the lungs during invasive fungal infection is mediated in part by CD11b + Ly-6G + neutrophils in an IL-23-dependent manner.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2011
    detail.hit.zdb_id: 1483247-1
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  • 5
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 51, No. 7 ( 2007-07), p. 2351-2358
    Abstract: AMD070 is an oral CXCR4 antagonist with in vitro activity against X4-tropic human immunodeficiency virus type 1. Thirty fasting healthy male volunteers received oral doses of AMD070 ranging from a single 50-mg dose to seven 400-mg doses given every 12 h (q12h). Nine subjects received a 200-mg dose during fasting and prior to a meal. Subjects were monitored for safety and pharmacokinetics. AMD070 was well tolerated, without serious adverse events. Transient headaches (13 subjects) and neurocognitive (8 subjects) and gastrointestinal (7 subjects) symptoms were the most common complaints. Seven subjects had sinus tachycardia, and two were symptomatic. AMD070 plasma concentrations peaked 1 to 2 h after patient dosing. The estimated terminal half-life ranged from 11.2 to 15.9 h among cohorts. Dose proportionality was not demonstrated. Less than 1% of the drug appeared unchanged in the urine. Food reduced the maximum concentration of drug in serum and the area under the concentration-time curve from 0 to 24 h by 70% and 56%, respectively ( P ≤ 0.01). A dose-dependent elevation of white blood cells (WBC) demonstrated a maximum twofold increase over baseline (95% confidence interval, 2.0- to 2.1-fold) in an E max model. In healthy volunteers, AMD070 was well tolerated and demonstrated mixed-order pharmacokinetics, and food reduced drug exposure. AMD070 induced a dose-related elevation of WBC which was attributed to CXCR4 blockade. Using leukocytosis as a surrogate marker for CXCR4 inhibition, this dose-response relationship suggests that the doses used in this study were active in vivo, though not maximal, throughout the dosing interval. Trough concentrations with the 400-mg dose q12h exceeded the antiviral in vitro 90% effective concentration of AMD070.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2007
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 6
    In: Infection and Immunity, American Society for Microbiology, Vol. 80, No. 1 ( 2012-01), p. 410-417
    Abstract: We have previously reported that mice deficient in the beta-glucan receptor Dectin-1 displayed increased susceptibility to Aspergillus fumigatus lung infection in the presence of lower interleukin 23 (IL-23) and IL-17A production in the lungs and have reported a role for IL-17A in lung defense. As IL-23 is also thought to control the production of IL-22, we examined the role of Dectin-1 in IL-22 production, as well as the role of IL-22 in innate host defense against A. fumigatus . Here, we show that Dectin-1-deficient mice demonstrated significantly reduced levels of IL-22 in the lungs early after A. fumigatus challenge. Culturing cells from enzymatic lung digests ex vivo further demonstrated Dectin-1-dependent IL-22 production. IL-22 production was additionally found to be independent of IL-1β, IL-6, or IL-18 but required IL-23. The addition of recombinant IL-23 augmented IL-22 production in wild-type (WT) lung cells and rescued IL-22 production by lung cells from Dectin-1-deficient mice. In vivo neutralization of IL-22 in the lungs of WT mice resulted in impaired A. fumigatus lung clearance. Moreover, mice deficient in IL-22 also demonstrated a higher lung fungal burden after A. fumigatus challenge in the presence of impaired IL-1α, tumor necrosis factor alpha (TNF-α), CCL3/MIP-1α, and CCL4/MIP-1β production and lower neutrophil recruitment, yet intact IL-17A production. We further show that lung lavage fluid collected from both A. fumigatus -challenged Dectin-1-deficient and IL-22-deficient mice had compromised anti-fungal activity against A. fumigatus in vitro . Although lipocalin 2 production was observed to be Dectin-1 and IL-22 dependent, lipocalin 2-deficient mice did not demonstrate impaired A. fumigatus clearance. Moreover, lung S100a8 , S100a9 , and Reg3g mRNA expression was not lower in either Dectin-1-deficient or IL-22-deficient mice. Collectively, our results indicate that early innate lung defense against A. fumigatus is mediated by Dectin-1-dependent IL-22 production.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2012
    detail.hit.zdb_id: 1483247-1
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  • 7
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 51, No. 8 ( 2007-08), p. 3047-3047
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2007
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
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