Last data update: Jun 24, 2024. (Total: 47078 publications since 2009)
Records 1-7 (of 7 Records) |
Query Trace: Tamura D [original query] |
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A randomized, double-blind, placebo-controlled trial evaluating the safety of early oseltamivir treatment among children 0-9 years of age hospitalized with influenza in El Salvador and Panama
Dawood FS , Jara J , Gonzalez R , Castillo JM , De Leon T , Estripeaut D , Luciani K , Sujey Brizuela Y , Barahona A , Cazares RA , Lawson AM , Rodriguez M , de Viana D , Franco D , Castillo M , Fry AM , Gubareva L , Tamura D , Hughes M , Gargiullo P , Clara W , Azziz-Baumgartner E , Widdowson MA . Antiviral Res 2016 133 85-94 BACKGROUND: Oseltamivir reduces symptom duration among children with uncomplicated influenza, but few data exist on treatment efficacy and tolerability among hospitalized children, particularly among infants aged <1 year. We evaluated tolerability and efficacy of oseltamivir treatment of children aged 0-9 years hospitalized with influenza. METHODS: We conducted a double-blind, randomized, placebo-controlled trial at tertiary care hospitals in El Salvador and Panama. Primary outcomes were length of hospitalization and increased work of breathing. Children were eligible if hospitalized <7 days after symptom onset with cough or sore throat plus tachypnea. Children were randomized 1:1 to receive oseltamivir or placebo; had swabs collected at enrollment for influenza RT-PCR testing; were assessed at enrollment and every 12 h for work of breathing; and were followed for adverse events through 7 days after discharge. Analyses were intention-to-treat. RESULTS: Overall, 683 children were randomized (oseltamivir, n = 341, placebo n = 342). Fifty-three percent were aged <1 year and 30 had influenza (oseltamivir, n = 19; placebo, n = 11). The study was terminated early after enrollment of 21% of the sample size due to lower than anticipated participant accrual. Using Kaplan-Meier analysis, there was no significant difference in median length of hospitalization (3 days, IQR 2-4 vs. 5 days, IQR 3-7, p = 0.22) and increased work of breathing (36 h, IQR 24-72 vs. 96 h, IQR 13-108, p = 0.14) between oseltamivir versus placebo recipients. There was no difference in adverse events between groups. CONCLUSION: Oseltamivir treatment was well tolerated among hospitalized children, including among infants aged <1 year. |
Emergence of multidrug resistant influenza A(H1N1)pdm09 virus variants in an immunocompromised child treated with oseltamivir and zanamivir
Tamura D , DeBiasi RL , Okomo-Adhiambo M , Mishin VP , Campbell AP , Loechelt B , Wiedermann BL , Fry AM , Gubareva LV . J Infect Dis 2015 212 (8) 1209-13 Prolonged treatment of an immunocompromised child with oseltamivir and zanamivir for A(H1N1)pdm09 virus infection led to the emergence of viruses carrying H275Y and/or E119G in the neuraminidase. When phenotypically evaluated by neuraminidase inhibition, the dual H275Y-E119G substitution caused highly reduced inhibition by four neuraminidase inhibitors including oseltamivir, zanamivir, peramivir and laninamivir. |
Application of a Seven-Target Pyrosequencing Assay To Improve the Detection of Neuraminidase Inhibitor-Resistant Influenza A(H3N2) Viruses.
Tamura D , Okomo-Adhiambo M , Mishin VP , Guo Z , Xu X , Villanueva J , Fry AM , Stevens J , Gubareva LV . Antimicrob Agents Chemother 2015 59 (4) 2374-9 ![]() National U.S. influenza antiviral surveillance incorporates data generated by neuraminidase (NA) inhibition (NI) testing of isolates supplemented with NA sequence analysis; and pyrosequencing analysis of clinical specimens. Lack of established correlates for clinically relevant resistance to NA inhibitors (NAIs) hinders interpretation of NI assay data. Nonetheless, A(H3N2) viruses are commonly monitored for highly reduced or reduced inhibition in the NI assay and/or presence of NA markers, E119V, R292K and N294S. In 2012-2013, three drug resistant A(H3N2) viruses were detected by NI assay among isolates (n=1424); all showed highly reduced inhibition by oseltamivir and had E119V. In addition, one R292K variant was detected among clinical samples (n=1024) by a 3-target pyrosequencing assay. Overall, frequency of NAI resistance was low, 0.16% (4 of 2448). To screen for additional NA markers previously identified in viruses from NAI-treated patients, the pyrosequencing assay was modified to include Q136K, I222V, del245-248 and del247-250. The 7-target pyrosequencing assay detected NA variants carrying E119V, Q136 and del245-248 in an isolate from an oseltamivir-treated patient. Next, this assay was applied to clinical specimens collected from hospitalized patients and submitted for NI testing, but failed cell culture propagation. Of the 27 clinical specimens tested, 4 (15%) contained NA changes: R292K (n=2), E119V (n=1) and del247-250 (n=1). Recombinant NAs with del247-250 and del245-248, respectively, conferred highly reduced inhibition by oseltamivir, reduced inhibition by zanamivir, and normal inhibition by peramivir and laninamivir. Our results demonstrated the benefits of the 7-target pyrosequencing assay in conducting A(H3N2) antiviral surveillance and testing for clinical care. |
Characterization of drug-resistant influenza A(H7N9) variant viruses isolated from an oseltamivir-treated patient in Taiwan
Marjuki H , Mishin VP , Chesnokov AP , Jones J , De La Cruz JA , Sleeman K , Tamura D , Nguyen HT , Wu HS , Chang FY , Liu MT , Fry AM , Cox NJ , Villanueva JM , Davis CT , Gubareva LV . J Infect Dis 2014 211 (2) 249-57 BACKGROUND: Patients contracting influenza A(H7N9) often developed severe disease causing respiratory failure. Neuraminidase (NA) inhibitors (NAIs) are the primary option for treatment, but information on drug-resistance markers for A(H7N9) is limited. METHODS: Four NA variants of A/Taiwan/1/2013 (H7N9) virus containing a single substitution (NA-E119 V, NA-I222 K, NA-I222R or NA-R292 K), recovered from an oseltamivir-treated patient, were tested for NAI susceptibility in vitro; their replicative fitness was evaluated in cell culture, mice and ferrets. RESULTS: NA-R292 K led to highly reduced inhibition by oseltamivir and peramivir, while NA-E119 V, NA-I222 K and NA-I222R caused reduced inhibition by oseltamivir. Mice infected with any virus showed severe clinical signs with high mortality rates. NA-I222 K virus was the most virulent in mice, whereas virus lacking NA change (NA-WT) and NA-R292 K virus seemed the least virulent. Sequence analysis suggests that PB2-S714N increased virulence of the NA-I222 K virus in mice; NS1-K126R, alone or in combination with PB2-V227M, produced contrasting effects in NA-WT and NA-R292 K viruses. In ferrets, all viruses replicated to high titers in the upper respiratory tract, but produced only mild illness. NA-R292 K virus, showed reduced replicative fitness in this animal model. CONCLUSIONS: Our data highlight challenges in assessment of replicative fitness of H7N9 NA variants emerged in NAI-treated patients. |
Cell culture-selected substitutions in influenza A(H3N2) neuraminidase affect drug susceptibility assessment
Tamura D , Nguyen HT , Sleeman K , Levine M , Mishin VP , Yang H , Guo Z , Okomo-Adhiambo M , Xu X , Stevens J , Gubareva LV . Antimicrob Agents Chemother 2013 57 (12) 6141-6 ![]() Assessment of drug susceptibility has become an integral part of influenza virus surveillance. In this study, we describe the drug resistance profile of influenza A(H3N2) virus, A/Mississippi/05/2011, collected from a patient treated with oseltamivir and detected via surveillance. An MDCK cell-grown isolate of this virus exhibited highly reduced inhibition by the neuraminidase (NA) inhibitors (NAIs) oseltamivir (8,005-fold), zanamivir (813-fold), peramivir (116-fold), and laninamivir (257-fold) in the NA inhibition assay. Sequence analysis of its NA gene revealed a known oseltamivir-resistance marker, the glutamic acid-to-valine substitution at position 119 (E119V), and an additional change, threonine to isoleucine at position 148 (T148I). Unlike E119V, T148I was not detected in the clinical sample but acquired during viral propagation in MDCK cells. Using recombinant proteins, T148I by itself was shown to cause only a 6-fold increase in the zanamivir 50% inhibitory concentration (IC50) and had no effect on inhibition by other drugs. The T148I substitution reduced NA activity by 50%, most likely by affecting the positioning of the 150 loop at the NA catalytic site. Using pyrosequencing, changes at T148 were detected in 35 (23%) of 150 MDCK cell-grown A(H3N2) viruses tested, which was lower than the frequency of changes at D151 (85%), an NA residue previously implicated in cell selection. We demonstrate that culturing of the A(H3N2) viruses (n = 11) at a low multiplicity of infection delayed the emergence of the NA variants with changes at position 148 and/or 151, especially when conducted in MDCK-SIAT1 cells. Our findings highlight the current challenges in monitoring susceptibility of influenza A(H3N2) viruses to the NAI class of antiviral drugs. |
Comparison of serum and red blood cell folate microbiologic assays for national population surveys
Pfeiffer CM , Zhang M , Lacher DA , Molloy AM , Tamura T , Yetley EA , Picciano MF , Johnson CL . J Nutr 2011 141 (7) 1402-9 Three laboratories participated with their laboratory-specific microbiologic growth assays (MA) in the NHANES 2007-2008 to assess whether the distributions of serum (n = 2645) and RBC folate (n = 2613) for the same one-third sample of participants were comparable among laboratories. Laboratory (L) 2 produced the highest and L1 the lowest serum and RBC folate geometric means (nmol/L) in the NHANES sample (serum: L1, 39.5; L2, 59.2; L3, 47.7; and RBC: L1, 1120; L2, 1380; L3, 1380). Each laboratory produced different reference intervals for the central 95% of the population. Pearson correlation coefficients were highest between L3 and L1 (serum, r = 0.95; RBC, r = 0.92) and lowest between L2 and L1 (serum, r = 0.81; RBC, r = 0.65). Notable procedural differences among the laboratories were the Lactobacillus rhamnosus microorganism (L1 and L3: chloramphenicol resistant, L2: wild type) and the calibrator [L1: [6S]5-methyltetrahydrofolate (5-methylTHF), L2: [6R,S] 5-formyltetrahydrofolate ([6R,S] 5-formylTHF), L3: folic acid (FA)]. Compared with 5-methylTHF as calibrator, the folate results were 22-32% higher with FA as calibrator and 8% higher with 5-formylTHF as calibrator, regardless of the matrix (n = 30 serum, n = 28 RBC). The use of different calibrators explained most of the differences in results between L3 and L1 but not between L2 and L1. The use of the wild-type L. rhamnosus by L2 appeared to be the main reason for the differences in results between L2 and the other 2 laboratories. These findings indicate how assay variations influence MA folate results and how those variations can affect population data. To ensure data comparability, better assay harmonization is needed. |
Biomarkers of folate status in NHANES: a roundtable summary
Yetley EA , Pfeiffer CM , Phinney KW , Fazili Z , Lacher DA , Bailey RL , Blackmore S , Bock JL , Brody LC , Carmel R , Curtin LR , Durazo-Arvizu RA , Eckfeldt JH , Green R , Gregory JF 3rd , Hoofnagle AN , Jacobsen DW , Jacques PF , Molloy AM , Massaro J , Mills JL , Nexo E , Rader JI , Selhub J , Sempos C , Shane B , Stabler S , Stover P , Tamura T , Tedstone A , Thorpe SJ , Coates PM , Johnson CL , Picciano MF . Am J Clin Nutr 2011 94 (1) 303S-312S A roundtable to discuss the measurement of folate status biomarkers in NHANES took place in July 2010. NHANES has measured serum folate since 1974 and red blood cell (RBC) folate since 1978 with the use of several different measurement procedures. Data on serum 5-methyltetrahydrofolate (5MTHF) and folic acid (FA) concentrations in persons aged ≥60 y are available in NHANES 1999-2002. The roundtable reviewed data that showed that folate concentrations from the Bio-Rad Quantaphase II procedure (Bio-Rad Laboratories, Hercules, CA; used in NHANES 1991-1994 and NHANES 1999-2006) were, on average, 29% lower for serum and 45% lower for RBC than were those from the microbiological assay (MA), which was used in NHANES 2007-2010. Roundtable experts agreed that these differences required a data adjustment for time-trend analyses. The roundtable reviewed the possible use of an isotope-dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) measurement procedure for future NHANES and agreed that the close agreement between the MA and LC-MS/MS results for serum folate supported conversion to the LC-MS/MS procedure. However, for RBC folate, the MA gave 25% higher concentrations than did the LC-MS/MS procedure. The roundtable agreed that the use of the LC-MS/MS procedure to measure RBC folate is premature at this time. The roundtable reviewed the reference materials available or under development at the National Institute of Standards and Technology and recognized the challenges related to, and the scientific need for, these materials. They noted the need for a commutability study for the available reference materials for serum 5MTHF and FA. |
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