Plasma and cellular markers of 3'-azido-3'-dideoxythymidine (AZT) metabolism as indicators of DNA damage in cord blood mononuclear cells from infants receiving prepartum NRTIs.

Several systemic and cellular markers of 3'-azido-3'-dideoxythymidine (AZT) metabolism and AZT incorporation into nuclear DNA were measured in cord blood from uninfected infants born to HIV-1-infected mothers receiving prepartum therapies based on AZT or AZT in combination with 2',3'-dideoxy-3'-thiacytidine (3TC). In addition, the relationships among these pharmacological end points, levels of AZT-DNA incorporation, and the previously reported mutagenic responses in these infants were evaluated. AZT- and 3TC-specific radioimmunoassays (RIAs), or HPLC coupled with AZT-RIA, were used to measure plasma levels of AZT and the AZT-glucuronide, and cellular levels of AZT, phosphorylated AZT, and DNA incorporation of AZT or 3TC in cord blood mononuclear cells from treated infants compared with unexposed controls born to HIV-uninfected mothers. Fewer infants had detectable AZT-DNA incorporation levels in the group exposed to AZT (71%; n = 7) compared with those receiving AZT-3TC (100%; n = 21), and the mean AZT-DNA incorporation for AZT-exposed infants (14.6 +/- 6.3 AZT/10(6) nucleotides) was significantly lower than that in AZT-3TC exposed infants (51.6 +/- 10.2 AZT/10(6) nucleotides; P = 0.028). Low levels of 3TC-DNA incorporation found in a few AZT-3TC-exposed newborns correlated with AZT-DNA incorporation values in the same samples. Among the metabolites studied, there were positive correlations between levels of AZT-diphosphate and AZT-triphosphate, and AZT-triphosphate and AZT-DNA incorporation, in nucleoside analog-exposed infants. Levels of AZT-DNA incorporation, however, did not correlate well with the reported frequencies of somatic mutations in the same population of nucleoside analog-treated children. While these data support the continued use of AZT-based therapies during pregnancy, infants receiving prepartum AZT should be monitored long-term for adverse health effects.

Genotoxicity assessed by the comet and GPA assays following in vitro exposure of human lymphoblastoid cells (H9) or perinatal exposure of mother-child pairs to AZT or AZT-3TC.

The genotoxicity of zidovudine (AZT) based treatments was investigated in human H9 lymphoblastoid cells in an in vitro study and in red blood cells (RBCs) from perinatally exposed HIV-1-infected mothers and their infants in an observational cohort study. Exposure of H9 cells for 24 hr to AZT produced dose-dependent increases in Comet assay tail moment (TM) when electrophoresed at pH 13.0, but not at pH 12.1 or pH 8.0, suggesting that DNA damage was via alkali-labile lesions and not double-stranded DNA strand breaks. The TM dose response at pH 13.0 correlated directly with AZT-DNA incorporation determined by AZT-radioimmunoassay. Levels of DNA damage in utero, measured by Comet assay TM, were similar in cord blood mononuclear cells of nucleoside analog-exposed newborns (n = 43) and unexposed controls (n = 40). In contrast, the glycophorin A (GPA) somatic cell mutation assay (which screens for large-scale DNA damage in RBCs) showed clear evidence that GPA N/N variants, arising from chromosome loss and duplication, somatic recombination, and gene conversion, were significantly elevated in mother-child pairs receiving prepartum AZT plus lamivudine (3TC). Cord blood from newborns exposed to AZT-3TC had GPA N/N variant frequencies of 4.7 +/- 0.7 (mean +/- SE) x 10(-6) RBCs (n = 26 infants) compared with 2.2 +/- 0.3 x 10(-6) RBCs for unexposed controls (n = 30 infants; P < 0.001). Elevations in GPA N/N variants generally persisted through 1 year of age in nucleoside analog-exposed children. Overall, the mutagenic effects found in mother-child pairs receiving AZT-based treatments justify their surveillance for long-term genotoxic consequences.

Transplacentally exposed human and monkey newborn infants show similar evidence of nucleoside reverse transcriptase inhibitor-induced mitochondrial toxicity.

Effective reduction in maternal-fetal human immunodeficiency virus-1 (HIV-1) transmission has been achieved by administration of nucleoside reverse transcriptase inhibitors (NRTIs) during pregnancy, and although most exposed children are clinically normal at birth, mitochondrial dysfunction has been reported. To examine mitochondrial integrity on a molecular level, we evaluated mitochondrial morphology by electron microscopy (EM) and mitochondrial DNA (mtDNA) quantity in umbilical cords and cord blood from NRTI-exposed and unexposed human and monkey newborns. Human subjects included infants born to HIV-1-infected mothers who received Combivir (Zidovudine [AZT] plus Lamivudine [3TC]) (n = 9) or AZT plus Didanosine [ddI] (n = 2) during pregnancy, and infants born to HIV-1-uninfected mothers (n = 7). NRTI-exposed Erythrocebus patas monkey dams (n = 3 per treatment group) were given human-equivalent dosing regimens containing 3TC, AZT/3TC, AZT/ddI, or Stavudine (d4T)/3TC during gestation. Four infants born to unexposed patas dams served as controls. Mitochondria in umbilical cord endothelial cells from NRTI-exposed monkey and human infants showed substantial abnormal pathology by EM, the extent of which was quantified from coded photomicrographs and shown to be different (P < 0.05) from the unexposed monkey and human newborns. Significant (P < 0.05) mtDNA depletion was found in umbilical cords from both human and monkey NRTI-exposed infants and in human, but not in monkey, cord blood leukocytes. For umbilical cords, an increase in mitochondrial morphological damage correlated with reduction in mtDNA quantity in fetal monkeys (r = 0.94). The treatment-induced mitochondrial compromise in infant monkeys ranked as follows: d4T/3TC > AZT/ddI > AZT/3TC > 3TC. The study demonstrates that transplacental NRTI exposures induce similar mitochondrial damage in cord blood and umbilical cords taken from retroviral-uninfected monkey infants and from human infants born to HIV-1-infected women.

Pharmacokinetics and safety of stavudine in HIV-infected pregnant women and their infants: Pediatric AIDS Clinical Trials Group protocol 332.

This study evaluates the safety, tolerance, and pharmacokinetics of stavudine (d4T) in human immunodeficiency virus (HIV)-infected zidovudine (ZDV)-intolerant/refusing pregnant women and of single-dose d4T in their infants. Women received d4T and lamivudine (3TC) from enrollment until labor. During labor, women received oral 3TC and either intravenous or oral d4T. Infants received ZDV and 3TC for 6 weeks and a single dose of oral d4T at weeks 1 and 6. Mean maternal antenatal d4T pharmacokinetics (terminal plasma half-life [T1/2], 83.5+/-16.8 min; area under the plasma-concentration time curve [AUC0-infinity), 81.6+/-22.0 microg.min/mL; n=6) were not significantly different from those during labor (T(1/2), 87.3+/-24.7 min; AUC0-infinity, 88.1+/-16.6 microg.min/mL; n=6). Umbilical-cord and maternal plasma concentrations were not significantly different from one another. The oral clearance of d4T in infants was significantly greater at week 6 versus week 1 (6.8+/-1.0 vs. 5.6+/-1.2 mL/min/kg). There were no toxicities, in women or infants, that required discontinuation or modification of the study drug. No infants had positive HIV viral diagnostic tests. d4T with or without 3TC is a potential alternative to ZDV for HIV-infected pregnant women.

Decline in perinatal HIV transmission in New York State (1997-2000).

BACKGROUND: Perinatal HIV transmission has declined significantly in New York State (NYS) since implementation of a 3-part regimen of zidovudine prophylaxis in the antenatal, intrapartum, and newborn periods. This study describes the factors associated with perinatal transmission in NYS from 1997 to 2000, the first 4 years of NYS's comprehensive program in which all HIV-exposed newborns were identified through universal HIV testing of newborns. METHODS: This population-based observational study included all HIV-exposed newborns whose infection status was known and their mothers identified in NYS through the universal Newborn HIV Screening Program (NSP) from February 1997 to December 2000. Antepartum, intrapartum, newborn, and pediatric medical records of HIV-positive mothers/infants were reviewed for history of prenatal care, antiretroviral therapy (ART), and infant infection status. Risks associated with perinatal HIV transmission were examined. RESULTS: Perinatal HIV transmission declined significantly from 11.0% in 1997 to 3.7% in 2000 (P < 0.05). Prenatal ART was associated with a decline in perinatal HIV transmission both for monotherapy (5.8%, relative risk [RR] = 0.3, 95% confidence interval: 0.2%-0.5%) and combination therapy [2.4%, RR = 0.1, 95% confidence interval: 0.1%-0.2%) compared with no prenatal antiretroviral prophylaxis (P < 0.05). CONCLUSIONS: Public health policies to improve access to care for pregnant women and advances in clinical care, including receipt of appropriate preventive therapies, have contributed to declines in perinatal HIV transmission in NYS.

Mitochondrial damage and DNA depletion in cord blood and umbilical cord from infants exposed in utero to Combivir.

OBJECTIVE: Although most uninfected infants born to women infected with HIV-1 show no clinical evidence of mitochondrial compromise, mitochondrial dysfunction has been reported in children born to women receiving zidovudine and/or lamivudine during pregnancy. In this pilot study we examined mitochondrial integrity in HIV-1-uninfected infants born to HIV-1-infected women receiving Combivir during pregnancy. DESIGN: : Samples of umbilical cord and cord blood were obtained from HIV-1-uninfected infants born to either HIV-1-infected women receiving Combivir therapy during pregnancy (n = 10) or HIV-1-uninfected women (n = 9). METHODS: Mitochondrial morphological integrity was examined in umbilical cords (n = 16) by electron microscopy and mtDNA quantity was determined in DNA from cord blood (n = 18) and umbilical cord (n = 18) by PCR-chemiluminescence immunoassay detection. RESULTS: In umbilical cords from six of nine infants born to HIV-1-infected mothers taking Combivir moderate to severe mitochondrial morphological damage was observed (P = 0.011), while none of seven unexposed infants showed similar damage. Compared to unexposed infants, statistically significant mtDNA depletion was observed in umbilical cord (P = 0.006) and cord blood (P = 0.003) from drug-exposed infants. CONCLUSIONS: A cohort of HIV-1-uninfected Combivir-exposed infants with no clinical symptoms showed morphological and molecular evidence of mitochondrial damage.