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Biomedical subjects

C A Boucher

Publications and source records attributed to C A Boucher.

At least 55 records · Page 3Linked to original sources
PubMed1998

Early recovery of CD4+ T lymphocytes in children on highly active antiretroviral therapy. Dutch study group for children with HIV infections.

INTRODUCTION: Regeneration of CD4+ T lymphocytes has been shown to be thymus-dependent in bone marrow transplant recipients and after intensive chemotherapy. The rate of CD4+ T cell regeneration is correlated positively with enlargement of the thymus, as shown on radiographs, and higher rates of CD4+ T lymphocyte regeneration were observed in children as compared with adults, consistent with thymic function diminishing with age. We hypothesized that in HIV infected patients CD4+ T cell recovery during highly active antiretroviral therapy (HAART) may also be thymus dependent. Therefore, repopulation of naive (CD45RA+), memory (CD45RO+) and total CD4+ T lymphocytes and total CD8+ T lymphocytes in peripheral blood was assessed in 13 HIV infected children during the initial 3 months of HAART. RESULTS: Significantly higher recovery rates of naive, memory and total CD4+ T cells were observed in children below the age of 3 years as compared with older children. Kinetics of total CD8+ T cells showed no relation to age. Moreover, recovery rates of naive CD4+ T cells in patients below 3 years of age were 10-40 fold higher as compared with previously reported naive CD4+ T cell recovery rates in adults on HAART. CONCLUSIONS: High recovery rates of naive, memory and total CD4+ T cells can be achieved in children below 3 years of age. Changes in CD8 counts did not correlate with age. These results indicate that regeneration of CD4+ T cells during HAART may be a thymus-dependent process.

Adolescent↗
PubMed1998

Cellular proviral HIV type 1 DNA load persists after long-term RT-inhibitor therapy in HIV type 1 infected persons.

In a set of 42 antiretroviral naive HIV-1 infected persons who were treated with either Zidovudine (AZT) monotherapy, or a combination of AZT + ddC (Zalcitabine) or AZT + ddI (Didanosine), the HIV-1 DNA load was measured by competitive polymerase chain reaction (PCR) and related to the HIV-1 RNA load in plasma, the CD4+ counts and to clinical markers. The question was whether a reduction in the cellular HIV-1 DNA level contributes to clinical benefit, as predicted by a lasting response in HIV-1 RNA levels in plasma. No significant decline relative to baseline in HIV-1 DNA load was found in the AZT monotherapy arm. In this arm the differences from baseline for both HIV-1 RNA load and CD4+ T cell counts were small and transient. In both combination therapy arms, the maximum mean decline in HIV-1 DNA load was 0.6 log and it never differed significantly from baseline. This is in contrast to plasma HIV-1 RNA load that declined earlier and steeper (mean of 1.5 and 1.9 log for AZT + ddC and AZT + ddI, respectively) and that remained significantly below baseline for 80 weeks. Although 9 of 42 (32%) of the patients under combination therapy had prolonged decreased plasma RNA levels, the proviral HIV-1 DNA remained present in the cells throughout the total follow-up of 144 weeks. In conclusion, combination therapy showed better laboratory parameter responses than AZT monotherapy, in agreement with the clinical data. The HIV-1 DNA sequences did not disappear in any of the patients, heralding renewed active infection after cessation of therapy.

Anti-HIV Agents↗
PubMed1998

Efficient inhibition of both syncytium-inducing and non-syncytium-inducing wild-type HIV-1 by lamivudine in vivo.

OBJECTIVE: To determine the effect of lamivudine (3TC) on syncytium-inducing (SI) and non-SI (NSI) HIV-1 populations in vivo. DESIGN: Responses in virus load and 3TC resistance in 40 3TC-treated subjects were analysed in relation to the presence or absence of SI HIV-1 variants. METHODS: Peripheral blood samples were collected at regular intervals from 40 HIV-1-infected subjects during 3TC treatment. Virus isolates obtained at the start of treatment were typed for SI-capacity by coculture with MT-2 cells. Changes in levels of viral RNA in plasma were determined by quantitative reverse transcriptase PCR. The relative amount of wild-type and mutant virus at codon 184, associated with HIV resistance to 3TC, was determined using a primer-guided nucleotide incorporation assay after amplification of part of the reverse transcriptase gene. In five subjects the frequency of productively infected CD4+ cells with SI or NSI variants was determined in relation to codon 184 genotype. RESULTS: Twenty-six subjects harboured only NSI variants at baseline, whereas 14 subjects also harboured SI variants. Although baseline plasma viral RNA load and CD4 cell counts were different between the two groups, no differences in the response to 3TC therapy were observed for these parameters. In-depth analysis of five subjects showed that the kinetics of virus load changes and emergence of 3TC resistance mutations were similar in plasma and cells, and comparable for the SI and NSI populations present in one individual. CONCLUSIONS: These data show that, in contrast to didanosine and zidovudine, the pressure exerted by 3TC is similar for SI and NSI M184 populations.

Anti-HIV Agents↗
PubMed1998

Activation and cell cycle antigens in CD4+ and CD8+ T cells correlate with plasma human immunodeficiency virus (HIV-1) RNA level in HIV-1 infection.

The relationship between T cell activation and human immunodeficiency virus type 1 (HIV-1) replication was studied in HIV-infected subjects, 20 with and 10 without anti-HIV treatment. Expression of Ki-67 proliferation-associated antigen was increased in CD4+ and CD8+ T cells and correlated with HLA-DR. In subjects without anti-HIV treatment, the plasma HIV-1 RNA level correlated with HLA-DR in CD4+ T cells, with Ki-67 in CD8+ T cells, and with expression of CD38 in both T cell subsets. A proportion of treated subjects had increased T cell activation despite 4 months of highly active antiretroviral treatment (HAART). In subjects receiving HAART, a high percentage of HLA-DR+ CD4+ T cells was associated with signs of opportunistic infections. This work supports the concept that, in the natural course of HIV-1 infection, HIV replication itself leads to general T cell activation and that opportunistic infections generate additional CD4+ T cell activation and HIV replication.

ADP-ribosyl Cyclase↗
PubMed1998

Maximum cardiac output during incremental exercise by first-pass radionuclide ventriculography.

STUDY OBJECTIVE: To validate a noninvasive first-pass radionuclide ventriculographic (FPRV) measurement of maximum cardiac output (Qv) during exercise. DESIGN: Comparison of Qv to that measured by the Fick principle (Qf) at peak exercise. SETTING: Academic cardiopulmonary exercise laboratory. PATIENTS: Seventy-eight consecutive patients without a history of septal defect undergoing clinically indicated maximum incremental cardiopulmonary exercise testing with pulmonary arterial catheterization and FPRV. MEASUREMENTS AND RESULTS: Ventilation and gas exchange were measured breath-by-breath or by a mixing chamber/mass spectrometer system. Arterial and mixed venous O2 content were measured each minute during exercise. When patients without left-to-right ventricular stroke count ratio evidence for left-sided regurgitation were isolated, peak Qv was linearly related to Qf (r=0.75, p=0.0001). To account for a small systematic overestimation (bias) of Qf by Qv, the linear equation for the Qv/Qf relation was derived for patients studied between 1990 and 1993 and applied to those studied subsequently. The resulting corrected peak Qv was tightly related to peak Qf (r=0.90, p<0.001) with confidence intervals for slope and intercept overlapping identity. CONCLUSION: FPRV can reasonably estimate maximum cardiac output during incremental exercise in patients for whom the technique has ruled out left-sided cardiac regurgitant lesions.

Cardiac Catheterization↗
PubMed1997

Selective inhibition of syncytium-inducing and nonsyncytium-inducing HIV-1 variants in individuals receiving didanosine or zidovudine, respectively.

By studying changes in the clonal composition of HIV-1 populations during the first weeks of zidovudine (ZDV) treatment before the development of ZDV resistance-conferring mutations, we demonstrated previously a selective inhibition of nonsyncytium-inducing (NSI) HIV-1, even when present as coexisting population in individuals also harboring syncytium-inducing (SI) HIV-1. In this study, we observed the opposite in individuals receiving didanosine (ddI) treatment. In these individuals (n = 7) a median -0.98 log change (range -1.55-0.08) in infectious cellular SI load was observed, whereas the coexisting NSI load was only minimally affected (median -0.15 log, range -1.27-0.50; P = 0.03). The virus phenotype-dependent treatment responses were independent of the clonal composition of HIV-1 populations at baseline. Individuals treated with a combination of ZDV and ddI revealed an equal decline of both NSI and SI infectious cellular load (n = 4; NSI: median -1.55 log, range -2.19 to -1.45; SI: median -1.47 log, range -1.81 to -0.86; P = 0.56). To test the hypothesis that the previously reported optimal activation of ZDV and ddI in activated and resting T cells, respectively, in combination with the differential T cell tropism of NSI and SI HIV-1 is the basis for the observed virus phenotype specific efficacy of nucleoside analogs, we studied the effect of treatment with a protease inhibitor that does not require intracellular activation. Individuals receiving ritonavir (n = 4) indeed showed equal declines in NSI and SI infectious cellular load (NSI: median -2.37 log, range -2.59 to -2.16; SI: median -2.82 log, range -3.14 to -2.50; P = 0.25). Our data suggest HIV-1 phenotype as an additional parameter in the design of optimal treatment regimens.

Animals↗
PubMed1997

[AIDS; new developments. II. Treatment of HIV infection].

The currently available anti-HIV drugs can be subdivided according to the mechanisms of action into two main groups, viz, reverse transcriptase (RT) inhibitors and protease inhibitors; the former may be subdivided into nucleoside inhibitors and non-nucleoside inhibitors of reverse transcriptase. Combination therapy is preferable to monotherapy because of resistance problems. The 'ideal' combination consists of two RT inhibitors plus one protease inhibitor. Of the RT inhibitors, zidovudine is to be preferred because it slows the development of AIDS dementia. Other RT inhibitors are didanosine, zalcitabine, stavudine and lamivudine. As regards the protease inhibitors; in view of the development of resistance, it is advised to prescribe ritonavir, indinavir or saquinavir. The antiretroviral management should be adjusted as soon as signs appear of toxicity or failure of the treatment due to resistance or poor compliance.

Anti-HIV Agents↗
PubMed1997

Vertical HIV-1 transmission correlates with a high maternal viral load at delivery.

Transmission of HIV-1 from an infected mother to her child occurs in around 20% of cases. Although maternal, immunological, and virological factors have been implicated in transmission, clear association is not yet well defined. For this reason, we have conducted a study to determine the relative contribution of the above-mentioned factors with special emphasis on quantitative viral load. We studied 67 HIV-1-infected mothers during pregnancy and labor and their 69 newborns (two sets of twins) from two university hospitals in Barcelona. Plasma and cell samples were collected at delivery between January 1992 and May 1994, and HIV-1 RNA and p24 in plasma, CD4 cell counts, and tissue culture infectious doses (TCID) were measured. Diagnosis of infection in children was based on persistence of anti-HIV-1 antibodies at 18 months of age, a positive HIV-1 culture or polymerase chain reaction in two separate samples, or presence of signs or symptoms of AIDS before 18 months of age. Results showed a very high relationship between > 10(5)/ml viral RNA copies (odds ratio [OR] 22, 95% confidence interval [CI] 4.4-119.2, p < 0.00001), > 0.5 TCID (OR 17, 95% CI 2.1-139.7, p = 0.001), CDC B + C (OR 3.5, 95% CI 0.98-12.5, p = 0.055), < 400 CD4 cells (OR 4.1; 95% CL 1.1-15.4, p = 0.01) and transmission of HIV-1. In this study, a strong association between mother-to-child transmission of HIV-1 and a high maternal viral RNA load in plasma at delivery is demonstrated. Viral load, which is related to clinical and immunological status in the mother, is the main contributing factor for HIV-1 vertical transmission, and these findings may have global and even individual therapeutic implications.

CD4 Lymphocyte Count↗
PubMed1997

High-dose nevirapine in previously untreated human immunodeficiency virus type 1-infected persons does not result in sustained suppression of viral replication.

High-dose nevirapine treatment has been reported to confer sustained antiretroviral effects, despite a rapid development of resistance. The use of this strategy was evaluated in 20 previously untreated human immunodeficiency virus type 1 (HIV-1) p24 antigenemic persons with CD4 cell counts between 100 and 500/mm3. Treatment consisted of 400 mg of nevirapine, after a 2-week lead-in dose of 200 mg. Rash was the most frequently reported adverse event, occurring in 25%. While sustained declines in p24 antigen levels were observed in the majority, serum HIV-1 RNA load and CD4 cell counts returned to baseline values within 12 weeks in virtually all subjects. The resistance-conferring tyrosine-to-cysteine substitution at reverse transcriptase position 181 was detected after 4 weeks in most subjects. These observations suggest that plasma drug levels attained with high-dose nevirapine were not sufficient to inhibit nevirapine-resistant virus, although they were approximately 2-fold higher than reported IC50 values of resistant virus.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Lamivudine-resistant human immunodeficiency virus type 1 variants (184V) require multiple amino acid changes to become co-resistant to zidovudine in vivo.

Exposure of human immunodeficiency virus to the nucleoside analogue lamivudine (3TC) rapidly selects for resistant variants with a valine at codon 184 (M184V) in the catalytic site of reverse transcriptase. In vitro, 184V demonstrated increased enzyme fidelity and suppressed zidovudine resistance. Clinical trials demonstrated that 3TC-zidovudine combination therapy results in a strong and sustained antiviral response. To investigate the role of 184V on in vivo virus evolution, the effect of zidovudine addition in 3TC-pretreated patients harboring 184V was studied. In vivo, no significant change in fidelity was observed with 184V, shown by generation of the classical pattern of zidovudine mutations. Of interest, in contrast to zidovudine monotherapy, in which just one substitution is sufficient for in vivo development of significant zidovudine resistance, multiple substitutions are required for the same level of zidovudine resistance in strains harboring 184V. This need for multiple substitutions may be one of the mechanisms explaining the sustained antiretroviral response of the 3TC-zidovudine combination.

Amino Acid Sequence↗
PubMed1997

Somatic instability of the myotonic dystrophy (CTG)n repeat during human fetal development.

Myotonic dystrophy is characterised by the striking level of somatic heterogeneity seen between and within tissues of the same patient, which probably accounts for a significant proportion of the pleiotropy associated with this disorder. The congenital form of the disease is associated with the largest (CTG)n repeat expansions. We have investigated the timing of instability of myotonic dystrophy (CTG)n repeats in a series of congenitally affected fetuses and neonates. We find that during the first trimester the repeat is apparently stable and that instability only becomes detectable during the second and third trimesters. In our series repeat instability is apparent only after 13 weeks gestational age and before 16 weeks. The appearance of heterogeneity shows some tissue specificity, with heart most commonly having the largest expansion. The degree of heterogeneity is not correlated with initial expansion size as gauged by chorionic villus and blood (CTG)n repeat sizes.

Embryonic and Fetal Development↗
PubMed1997

In-vitro selection of HIV-1 variants resistant to non-nucleoside reverse transcriptase inhibitors in monocyte-derived macrophages.

Unlike the selection of HIV-1 variants resistant to anti-retroviral drugs in human peripheral blood mononuclear cells and T cell lines, induction of resistance in monocyte-derived macrophages has not been widely studied. Since macrophages serve as a potential HIV-1 reservoir in humans, knowledge of the effect of anti-retroviral drugs on macrophage-tropic HIV-1 isolates may help in the design of a strategy for prolonged suppression of viral replication. In-vitro selection and drug susceptibility testing of macrophage-tropic HIV-1 variants with reduced sensitivity to two non-nucleoside reverse transcriptase inhibitors, atevirdine and delavirdine (both bis-heteroarylpiperazines), is described here. The atevirdine-resistant isolate was cross-resistant to delavirdine, and the delavirdine-resistant isolate was cross-resistant to atevirdine. Interestingly, the atevirdine-resistant isolate, but not the delavirdine-resistant isolate, was also cross-resistant to nevirapin while the inhibition of viral replication of both isolates in macrophages by zidovudine was the same as that in the parental HIV-1 strain. Nucleotide sequence analysis of the resistant macrophage-tropic HIV-1 isolates showed that the atevirdine-induced resistance was due to a single amino acid change at codon 106 and that the delavirdine-induced resistance could be attributed to an amino acid change at codon 236. This study demonstrates that monocyte-derived macrophages can be used to investigate the phenotypic and genotypic acquisition of anti-retroviral drug resistance of macrophage-tropic HIV-1.

Amino Acid Sequence↗