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Biomedical subjects

John A Bartlett

Publications and source records attributed to John A Bartlett.

At least 19 recordsLinked to original sources
PubMed2007

Detection of minor drug-resistant populations by parallel allele-specific sequencing.

We developed a highly sensitive parallel allele-specific sequencing (PASS) assay to simultaneously analyze a large number of viral genomes and detect minor drug-resistant populations at approximately 0.1-0.01% levels. Using this assay on samples from individuals infected with human immunodeficiency viruses (HIV), we successfully detected and quantified minor populations of drug-resistant viruses and performed linkage analysis of multiple-drug resistance mutations. This assay may serve as a useful tool to study drug resistance in HIV and other infectious agents.

Anti-HIV Agents↗
PubMed2006

Long-term results of initial therapy with abacavir and Lamivudine combined with Efavirenz, Amprenavir/Ritonavir, or Stavudine.

OBJECTIVE: To compare alternative class-sparing antiretroviral regimens in treatment-naive subjects. DESIGN: Open-label, multicenter, randomized trial of up to 3 consecutive treatment regimens over 96 weeks. METHODS: Two hundred ninety-one subjects received abacavir (ABC) and lamivudine and efavirenz (nonnucleoside reverse transcriptase inhibitors [NNRTIs]), ritonavir-boosted amprenavir (protease inhibitor [PI]), or stavudine (nucleoside reverse transcriptase inhibitor [NRTI]) by random assignment. The primary end points were the percentages of subjects with plasma HIV-1 RNA levels <400 copies/mL and time to treatment failure over 96 weeks. RESULTS: Ninety percent of subjects completed 96 weeks of follow-up, and 79% remained on study treatment. At week 96, there were no differences between arms in the percentages of subjects with plasma HIV-1 RNA levels <400 and <50 copies/mL, mean changes in plasma HIV-1 RNA levels, time to treatment failure, time to first or second virologic failure, or CD4 cell counts. The NNRTI arm had a greater percentages of subjects with RNA levels <or=50 copies/mL at weeks 24 and 48 and a greater overall duration of plasma HIV-1 RNA levels <400 copies/mL. Three subjects in the NNRTI arm had treatment failure on their first regimen and switched therapy compared with 16 in the NRTI arm and 13 in the PI arm. Twenty-one subjects had hypersensitivity reactions attributed to ABC (7.3%). Fewer drugs were used by subjects in the NNRTI arm, and fewer subjects in the NNRTI arm used 3 drug classes. CONCLUSIONS: All treatment regimens demonstrated excellent 96-week results. Secondary analyses favored the NNRTI regimen over the PI and NRTI regimens.

Adult↗
PubMed2006

An updated systematic overview of triple combination therapy in antiretroviral-naive HIV-infected adults.

OBJECTIVE: To compare the effectiveness of three drug combination antiretroviral therapy (ART) in treatment-naive HIV-infected persons, and identify the predictors of responses. DESIGN AND METHODS: Overview of trials identified by searching public domain publications and conference presentations. The three-drug combination therapy was defined as two nucleoside reverse transcriptase inhibitors (NRTI) or nucleotide and NRTI, and either: (1) a protease inhibitor (PI); (2) a non-nucleoside RTI (NNRTI); (3) a third NRTI; or (4) a ritonavir-boosted PI (BPI). Week 24 and 48 results for the proportions of patients with plasma HIV RNA levels < 400 and < 50 copies/ml, and change in CD4(+) cell counts were recorded. RESULTS: Fifty-three trials met the entry criteria, and enrolled 14 264 patients into 90 treatment arms. Overall 55% of patients had plasma HIV RNA levels < 50 copies/ml at week 48 and this percentage increased with later publication dates. In unadjusted pairwise comparisons at week 48, significantly greater percentages of patients receiving NNRTI (64%) and BPI (64%) had RNA < 50 copies/ml than NRTI (54%) or PI (43%), and CD4(+) cell count increases were significantly greater in the BPI group (+200 cells/microl) than the PI (+179), NNRTI (+173), or NRTI (+161) groups. Pill count and percentage of patients with week 48 plasma HIV RNA levels < 50 copies/ml were correlated in the univariate analysis (P = 0.0053; r = -0.323), but pill count was not a significant predictor in the multivariate analyses. Drug class and baseline CD4(+) cell counts were significant predictors, but explained only a modest amount of the treatment effect, (R(2) = 0.355). CONCLUSIONS: NNRTI and BPI-containing regimens offer superior virologic suppression over 48 weeks, supporting existing guidelines for the choice of initial ART. Pill count was not a consistent predictor of virologic suppression.

Anti-HIV Agents↗
PubMed2006

Pharmacogenetics of nevirapine-associated hepatotoxicity: an Adult AIDS Clinical Trials Group collaboration.

Associations have been reported between an MDR1 variant and responses to nonnucleoside reverse-transcriptase inhibitors. We explored associations between MDR1, CYP2B6, and CYP3A polymorphisms and nevirapine hepatotoxicity. Among participants in a randomized study in South Africa (FTC-302), MDR1 3435C-->T was significantly associated with decreased risk of hepatotoxicity (risk ratio, 0.30; P=.016).

Adult↗
PubMed2006

Changing antiretroviral therapy in the setting of virologic relapse: review of the current literature.

Virologic relapse after initial virologic suppression remains a concern for patients on antiretroviral therapy (ART). Multiple factors may contribute to virologic relapse, including suboptimal adherence, resistance, and pharmacokinetic issues. The major guidelines for HIV care are in agreement that ART regimen change is indicated in relapse because resistance is identified, but the guidelines are not completely clear on the timing of regimen change. When relapse occurs due to resistance, patients may continue with viremia well below their set points, stable or increasing CD4+ counts, and clinical health for several years. However, delaying a switch in the treatment regimen may lead to the accumulation of resistance which compromises future treatment response. In general, a lower switch threshold is recommended for patients during relapse on first or second line regimens.

Anti-HIV Agents↗
PubMed2006

Minimizing resistance consequences after virologic failure on initial combination therapy: a systematic overview.

OBJECTIVE: To identify optimal first-line therapies based on the rate of virologic success (VS) and the preservation of future treatment options in antiretroviral therapy (ART)-naive subjects. DESIGN: Systematic overview of genotypic resistance mutations from clinical trials of combination ART. METHODS: Various sources were searched for studies in ART-naive subjects providing virologic response rates and genotypes from subjects with virologic failure. The International AIDS Society-USA genotypic resistance guidelines were used to calculate regimen resistance cost (RCreg) and number of active drug (AD) scores for each regimen and to rank the regimens. RESULTS: Intra- and interstudy comparisons showed higher VS rates for nonnucleoside reverse transcriptase inhibitor (NNRTI) regimens (range: 51%-76%) and boosted protease inhibitor (boosted PI) regimens (range: 55%-79%). Boosted PI failures had the lowest RCreg (range: 0.12-0.21) and the highest AD (range: 19.80-20.18) scores. NNRTI failures had higher RCreg (range: 0.00-1.22) and lower AD (range: 16.83-21) scores. CONCLUSIONS: NNRTI and boosted PI regimens provide the highest rates of VS in treatment-naive HIV-infected persons. Treatment option scores were higher in subjects who failed boosted PI- containing regimens versus NNRTI-containing regimens, however.

Anti-HIV Agents↗
PubMed2005

Cost-effectiveness of free HIV voluntary counseling and testing through a community-based AIDS service organization in Northern Tanzania.

OBJECTIVES: We evaluated the cost-effectiveness of fee-based and free testing strategies at an HIV voluntary counseling and testing (VCT) program integrated into a community-based AIDS service organization in Moshi, Tanzania. METHODS: We waived the usual fee schedule during a 2-week free, advertised VCT campaign; analyzed the number of clients testing per day during prefree, free, and postfree testing periods; and estimated the cost-effectiveness of limited and sustained free testing strategies. RESULTS: The number of clients testing per day increased from 4.1 during the prefree testing interval to 15.0 during the free testing campaign (P<.0001) and remained significantly increased at 7.1 (P<.0001) after resumption of the standard fees. HIV seroprevalence (16.7%) and risk behaviors were unchanged over these intervals. Modeled over 1 year, the costs per infection averted with the standard fee schedule, with a 2-week free VCT campaign, and with sustained free VCT year-round were $170, $105, and $92, respectively, and the costs per disability-adjusted life year gained were $8.72, $5.40, and $4.72, respectively. CONCLUSIONS: The provision of free VCT enhances both the number of clients testing per day and its cost-effectiveness in resource-limited settings.

AIDS Serodiagnosis↗
PubMed2005

Severe hepatotoxicity associated with nevirapine use in HIV-infected subjects.

Human immunodeficiency virus (HIV)-infected South African patients (n=468) received blinded lamivudine or emtricitabine, stavudine, and either nevirapine or efavirenz (based on screening viral load). Baseline characteristics were analyzed in univariate and multivariate regression, to identify risk factors for hepatotoxicity (grade 3 or greater increase in serum aminotransferase levels). The occurrence of early hepatotoxicity was 17% in the nevirapine group and 0% in the efavirenz group and was balanced between the lamivudine and emtricitabine arms. Two subjects died of hepatic failure. Independent risk factors were body-mass index (BMI) <18.5, female sex, serum albumin level <35 g/L, mean corpuscular volume >85 fL, plasma HIV-1 RNA load <20,000 copies/mL, aspartate aminotransferase level <75 IU/L, and lactate dehydrogenase level <164 IU/L. The use of nevirapine in female patients with a low BMI should be discouraged.

Adult↗
PubMed2005

Naïve T cells are maintained in the periphery during the first 3 months of acute HIV-1 infection: implications for analysis of thymus function.

A key determinant of T cell dynamics in HIV-1 infection is the status of thymic function. To date, most studies of the impact of HIV-1 on the thymus during early HIV-1 infection have been done in samples collected in the interval of 3-12 months after infection. In this study, we have probed the status of thymic function and peripheral naive T cells in patients with acute HIV-1 infection diagnosed 18-72 days after the onset of symptoms. We found that peripheral CD4 and CD8 T cell proliferation was initially elevated, then waned over time. The fall in T cell proliferation correlated with a reduction in HIV-1 viral RNA levels and a rise in peripheral blood CD4+ CD25+ T cells. In spite of elevated T cell proliferation early on in primary HIV-1 infection, levels of naive phenotype CD4 and CD8 T cells and T cell receptor excision circle positive cells (sjTREC(+)) remained constant. Taken together with the observation that T cell proliferation normally dilutes peripheral T cell episomal sjTREC levels, these data suggested that thymopoiesis contributes to maintenance of the naive T cell pool during the earliest stages of HIV-1 infection (18-72 days).

Adult↗
PubMed2005

Fixed dose combination abacavir/lamivudine in the treatment of HIV-1 infection.

The fixed dose combination of abacavir with lamivudine represents a new treatment option for patients infected with HIV. Fixed dose combination abacavir/lamivudine has the convenience of one pill and once-daily dosing. It achieves comparable suppression of plasma HIV RNA with the pill's individual components dosed twice daily and with thymidine analogs combined with lamivudine. The combination is well tolerated, with the potential advantages of less lipoatrophy and fewer metabolic perturbations. However, the abacavir component may cause hypersensitivity reactions, which are reported in up to 8% of patients, and are potentially life threatening. Fixed dose combination abacavir/lamivudine should be considered as a viable treatment option for HIV-infected patients, particularly for those who have otherwise limited nucleoside reverse transcriptase inhibitor choices.

Animals↗
PubMed2004

Persistent antiretroviral activity of nucleoside analogues after prolonged zidovudine and lamivudine therapy as demonstrated by rapid loss of activity after discontinuation.

Antiretroviral (ARV) treatment decisions are difficult for HIV-1-infected patients on complex treatment regimens who have partial suppression of HIV-1 replication and limited treatment options. Information on the ARV activity of the components of a complex regimen would be useful. Sixteen subjects who had received prolonged therapy with zidovudine (ZDV) and lamivudine (3TC), with a median duration of 32.5 months, were discontinuing this dual-nucleoside regimen and volunteered to have plasma HIV-1 RNA levels monitored over the 2 weeks after discontinuation. All subjects experienced an increase in HIV-1 RNA after discontinuation, with a median increase of 0.54 log10 copies/mL over 2 weeks (range: 0.31-1.71; P < 0.001). An inverse correlation existed between the decline in HIV-1 RNA levels over 2 to 3 years on nucleoside analogue therapy and the increase over the 10 to 14 days off therapy (Spearman r = -0.53; P = 0.036). Over the 2-week period, a subset of individuals who had genotype testing at multiple reverse transcriptase codons associated with ZDV and 3TC resistance had no changes in genotype off therapy. Nucleoside analogue reverse transcriptase inhibitors may have continued ARV activity despite long durations of partially suppressive therapy and the presence of resistant HIV-1.

Anti-HIV Agents↗
PubMed2004

Safety and immunogenicity of a polyvalent peptide C4-V3 HIV vaccine in conjunction with IL-12.

We examined the safety and immunogenicity of a human leukocyte antigen-based HIV envelope polyvalent synthetic peptide vaccine, C4-V3, alone and in combination with subcutaneous IL-12 in nine HIV-infected patients. Lymphocyte proliferative responses increased threefold or more to all four peptides at two consecutive post-immunization timepoints for four individuals. Three responders had received IL-12, suggesting a possible adjuvant effect of Il-12. Transient mild injection site reactions (7.9) and systemic symptoms (3/9) occurred.

AIDS Vaccines↗
PubMed2004

Short-term safety and antiretroviral activity of T-1249, a second-generation fusion inhibitor of HIV.

T-1249 is a 39-aa synthetic peptide that inhibits fusion of human immunodeficiency virus (HIV) to the host target cell. A 14-day open-label, phase 1/2 dose-escalation monotherapy study of the safety and antiretroviral activity of T-1249 was performed on 115 HIV-1-infected adults. At baseline, the majority of the patients had advanced HIV disease (baseline median CD4(+) cell count, 57 cells/microL) and had extensive pretreatment (i.e., pre-T-1249) experience with antiretroviral medications (median, 11 antiretroviral drugs). Patients received T-1249 monotherapy by subcutaneous injection, for 14 days, at doses ranging from 6.25 to 192 mg/day. T-1249 was generally well tolerated, and no dose-limiting toxicity was identified. Injection-site reactions were the most commonly reported adverse event (57%). Dose-dependent decreases in plasma HIV-1 RNA load were observed; the median maximum change from baseline across dose groups ranged from -0.29 log(10) copies/mL (95% confidence interval [CI], -0.43 to -0.05 log(10) copies/mL) for the lowest dose to -1.96 log(10) copies/mL (95% CI, -2.02 to -1.37 copies/mL) for the highest dose. These results indicate that T-1249 is a potent new therapeutic agent for HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Changes in CD4+ T-cell differentiation phenotype during structured treatment interruption in patients with chronic HIV-1 infection.

Markers of maturation and activation were measured on peripheral CD4+ T cells in chronically HIV-1-infected patients in a randomized, controlled pilot study of structured treatment interruption (STI). Eight subjects underwent 2 cycles of 1 month off and 1 month on highly active antiretroviral therapy (HAART), followed by a final 3-month interruption. During STI, CD4+ T-cell percentage remained relatively stable in 4 of 8 subjects. The remaining 4 STI subjects had significant rapid decline in CD4+ T-cell percentage during STI, followed by return to pre-STI baseline while on HAART. Changes in overall CD4+ T-cell percentage corresponded with fluctuations in the CD45RA+CCR7+ naive and CD45RA-CCR7+ central memory subsets. Subjects with variable CD4+ T-cell percentages tended to have higher pre-HAART plasma HIV-1 RNA set-points and experienced higher levels of plasma HIV-1 RNA rebound during STI. These results suggest that interruptions should be avoided whenever possible in patients on HAART with high plasma HIV-1 RNA set-points.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Emergence of drug-resistant HIV-1 variants in patients undergoing structured treatment interruptions.

We report the emergence of drug-resistant viral mutations in chronically HIV-infected individual undergoing structured treatment interruptions (STI). THe protease mutations K101E and K103N were detected at the end of the second or third STI. We concluded that the repeated abrupt termination and resumption of certain antiretroviral drug regimens during STI therapy may lead to the development of drug resistance in chronically HIV-infected individuals.

Anti-HIV Agents↗