Hematological Changes in Women and Infants Exposed to an AZT-Containing Regimen for Prevention of Mother-to-child-transmission of HIV in Tanzania.

Tanzanian guidelines for prevention of mother-to-child-transmission of HIV (PMTCT) recommend an antiretroviral combination regimen involving zidovudine (AZT) during pregnancy, single-dosed nevirapine at labor onset, AZT plus Lamivudine (3TC) during delivery, and AZT/3TC for 1-4 weeks postpartum. As drug toxicities are a relevant concern, we assessed hematological alterations in AZT-exposed women and their infants. A cohort of HIV-positive women, either with AZT intake (n = 82, group 1) or without AZT intake (n = 62, group 2) for PMTCT during pregnancy, was established at Kyela District Hospital, Tanzania. The cohort also included the infants of group 1 with an in-utero AZT exposure ≥4 weeks, receiving AZT for 1 week postpartum (n = 41), and infants of group 2 without in-utero AZT exposure, receiving a prolonged 4-week AZT tail (n = 58). Complete blood counts were evaluated during pregnancy, birth, weeks 4-6 and 12. For women of group 1 with antenatal AZT intake, we found a statistically significant decrease in hemoglobin level, red blood cells, white blood cells, granulocytes, as well as an increase in red cell distribution width and platelet count. At delivery, the median red blood cell count was significantly lower and the median platelet count was significantly higher in women of group 1 compared to group 2. At birth, infants from group 1 showed a lower median hemoglobin level and granulocyte count and a higher frequency of anemia and granulocytopenia. At 4-6 weeks postpartum, the mean neutrophil granulocyte count was significantly lower and neutropenia was significantly more frequent in infants of group 2. AZT exposure during pregnancy as well as after birth resulted in significant hematological alterations for women and their newborns, although these changes were mostly mild and transient in nature. Research involving larger cohorts is needed to further analyze the impact of AZT-containing regimens on maternal and infant health

Failure of dideoxynucleosides to inhibit human immunodeficiency virus replication in cultured human macrophages.

Primary human monocyte-derived macrophages (MDM) were shown to have diminished deoxynucleoside kinase activities compared to T lymphoblasts, and a reduced ability to phosphorylate dideoxynucleosides with anti-human immunodeficiency virus (HIV) activity. These drugs, azidothymidine (AZT), dideoxycytidine (ddC), and dideoxyadenosine (ddA), which are potent anti-HIV agents in CD4 lymphocytes, did not inhibit HIV replication in MDM, even at concentrations of 100 microM. This drug concentration of AZT is approximately 100-fold higher than the levels attained in the serum of treated patients and the levels required to inhibit HIV replication in lymphocytes. These observations may explain the failure of AZT therapy to clear viremia, consistent with the presence of a drug-resistant reservoir of infected cells in vivo. New therapeutic approaches to inhibit the replication of HIV in MDM may be needed

AZT exerts its antitumoral effect by telomeric and non-telomeric effects in a mammary adenocarcinoma model

Limitless replicative potential is one of the hallmarks of cancer that is mainly due to the activity of telomerase. This holoenzyme maintains telomere length, adding TTAGGG repetitions at the end of chromosomes in each cell division. In addition to this function, there are extratelomeric roles of telomerase that are involved in cancer promoting events. It has been demonstrated that TERT, the catalytic component of telomerase, acts as a transcriptional modulator in many signaling pathways. Taking into account this evidence and our experience on the study of azidothymidine (AZT) as an inhibitor of telomerase activity, the present study analyzes the effect of AZT on some telomeric and extratelomeric activities. To carry out the present study, we evaluated the transcription of genes that are modulated by the Wnt/β-catenin pathway, such as c-Myc and cyclin-D1 (Cyc-D1) and cell processes related with their expression, such as, proliferation, modifications of the actin cytoskeleton, cell migration and cell cycle in a mammary carcinoma cell line (F3II). Results obtained after treatment with AZT (600 µM) for 15 passages confirmed the inhibitory effect on telomerase. Regarding extratelomeric activities, our results showed a decrease of 64, 38 and 25% in the transcription of c-Myc, Cyc-D1 and TERT, respectively (p<0.05) after AZT treatment. Furthermore, we found an effect on cell migration, reaching an inhibition of 48% (p<0.05) and a significant passage-dependent increase on cell doubling time during treatment. Finally, we evaluated the effect on cell cycle, obtaining a decline in G0/G1 in AZT-treated cells. These results allow us to postulate that AZT is not only an inhibitor of telomerase activity, but also a potential modulator of extratelomeric processes involved in cancer promotion.Fil: Armando, Romina Gabriela. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Cost and cost-effectiveness of switching from d4T or AZT to a TDF-based first-line regimen in a resource-limited setting in rural Lesotho

Article approval pendingLatest World Health Organization guidelines recommend shifting away from Stavudine (d4T)-based regimens due to severe side effects. However, widespread replacement of d4T by Tenofovir (TDF) or Zidovudine (AZT) is hampered by cost concerns

Evaluation of HIV counseling and testing in ANC settings and adherence to short course antiretroviral prophylaxis for PMTCT in Francistown, Botswana

Worldwide, it is estimated that two million children are infected with HIV (USAID 2005). The vast majority of these infections are the result of mother-to-child transmission (MTCT) of the virus during pregnancy, labor, or breastfeeding. However, there are effective methods for prevention of mother-to-child transmission (PMTCT). Botswana is one of the first countries in the developing world with a national PMTCT program that uses an efficacious and complex regimen to reduce vertical transmission. At the time of this evaluation (August - December 2005), the standard of care for prevention of MTCT of HIV in Botswana included three-drug antiretroviral therapy for HIV-infected women with a CD4 count of 200 (300 mg AZT in the morning and 300 mg AZT in the evening); four weeks of AZT for their infants; single-dose maternal and infant nevirapine (NVP); and 12 months of free infant formula. Botswana's PMTCT program also provided routine HIV testing for all pregnant women during antenatal care (ANC) to identify HIV-positive women for prophylaxis or treatment. While programs often report the number of individuals beginning AZT and receiving nevirapine for PMTCT, effectiveness is dependent on the level of adherence of individuals to these regimens. To describe adherence of pregnant women to the current PMTCT regimen, the Horizons Program of the Population Council, in collaboration with the Centers for Disease Control and Prevention (CDC) and Premiere Personnel in Botswana, conducted an evaluation to describe HIV-related services provided to women during their pregnancies, document the content of post-test counseling sessions for HIV-positive pregnant women, whether HIV-positive women remembered what had been discussed, the extent of AZT adherence based on self-reports, and the operational successes and barriers to adherence to AZT for PMTCT

Utilization of a deoxynucleoside diphosphate substrate by HIV reverse transcriptase

Background: Deoxynucleoside triphosphates (dNTPs) are the normal substrates for DNA sysnthesis is catalyzed by polymerases such as HIV-1 reverse transcriptase (RT). However, substantial amounts of deoxynucleoside diphosphates (dNDPs) are also present in the cell. Use of dNDPs in HIV-1 DNA sysnthesis could have significant implications for the efficacy of nucleoside RT inhibitors such as AZT which are first line therapeutics fro treatment of HIV infection. Our earlier work on HIV-1 reverse transcriptase (RT) suggested that the interaction between the γ phosphate of the incoming dNTP and RT residue K65 in the active site is not essential for dNTP insertion, implying that this polymerase may be able to insert dNPs in addition to dNTPs. Methodology/Principal Findings: We examined the ability of recombinant wild type (wt) and mutant RTs with substitutions at residue K65 to utilize a dNDP substrate in primer extension reactions. We found that wild type HIV-1 RT indeed catalyzes incorporation of dNDP substrates whereas RT with mutations of residue K645 were unable to catalyze this reaction. Wild type HIV-1 RT also catalyzed the reverse reaction, inorganic phosphate-dependent phosphorolysis. Nucleotide-mediated phosphorolytic removal of chain-terminating 3′-terminal nucleoside inhibitors such as AZT forms the basis of HIV-1 resistance to such drugs, and this removal is enhanced by thymidine analog mutations (TAMs). We found that both wt and TAM-containing RTs were able to catalyze Pi-mediated phosphorolysis of 3′-terminal AZT at physiological levels of Pi with an efficacy similar to that for ATP-dependent AZT-excision. Conclusion: We have identified two new catalytic function of HIV-1 RT, the use of dNDPs as substrates for DNA synthesis, and the use of Pi as substrate for phosphorolytic removal of primer 3′-terminal nucleotides. The ability to insert dNDPs has been documented for only one other DNA polymerase The RB69 DNA polymerase and the reverse reaction employing inorganic phosphate has not been documented for any DNA polymerase. Importantly, our results show that Pi-mediated phosphorolysis can contribute to AZT resistance and indicates that factors that influence HIV resistance to AZT are more complex than previously appreciated. © 2008 Garforth et al

Fitness Ranking of Individual Mutants Drives Patterns of Epistatic Interactions in HIV-1

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A Method for the Quantification of Intracellular Zidovudine Nucleotides

An assay to quantify the phosphorylation products of zidovudine (AZT) in peripheral blood mononuclear cells (PBMC) was developed. Extracts of PBMC were separated by high-performance liquid chromatography. Eluted AZT mono- (MP), di- (DP), and triphosphate (TP) were collected in separate portions. Treatment with alkaline phosphatase yielded equimolar amounts ofAZT, which after solid-phase enrichment were assayed by radioimmunoassay. Detection limit was 0.1 pmol/106 PBMC for each nucleotide. Recoveries of 102%-118% were observed. AZT nucleotides were measured in samples from three patients receiving 250 mg ofAZT every 12 h. Intracellular concentrations of AZT-MP after 1-2 h ranged from 0.9 to 1.4 pmol/106 PBMC and then declined to 0.3-1.1 pmol/106 PBMC after 4 h. AZT-DP and AZT-TP reached concentrations of 0.3-0.5 pmol/106 PBMC after 1-2 h and could not be detected after 4 h in any of the three patients. Duplicate determinations deviated by <20

Immunovirological outcomes and resistance patterns at 4 years of antiretroviral therapy use in HIV-infected patients in Cambodia

Objectives  To report immunovirological outcomes and resistance patterns in adults treated with triple combination antiretroviral therapy (cART) for 4 years in an HIV programme of Phnom Penh, Cambodia. Methods  It is a longitudinal study and cross-sectional evaluation of adults receiving cART for 4 years. CD4 cell counts and HIV-1 RNA were quantified, and resistance patterns were determined. Drug-related toxicity was assessed by clinicians and through laboratory testing. Results  After 4 years of cART start, the cumulative probability of retention in care was 0.80 and survival among patients not lost to follow-up was 0.85. A total of 349 patients (98% of eligible) participated in the cross-sectional evaluation. Ninety per cent were receiving first-line therapy, 29% stavudine- and 58% zidovudine-containing regimens (compared with 94% and 3% at cART initiation). Ninety-three per cent of patients were clinically asymptomatic, and severe lipodystrophy and dyslipidemia were diagnosed in 7.2% and 4.0%, respectively. Good treatment adherence was reported by 83% of patients. Median CD4 T-cell count was 410 cells/μl [IQR 290-511], and 90% of patients had >200 cells/μl. Only 15 (4%) patients had detectable HIV viral load (eight had <200 CD4 cells/μl), five had thymidine analogue mutations, and nine were resistant to two drug classes. In an intention-to-treat analysis, 26.1% (95% CI 22.0-30.5) of patients had failed first-line therapy. Conclusions  In this Cambodian cohort of adults who started cART at an advanced stage of HIV disease, we observed good clinical and immunovirological outcomes and self-reported treatment adherence at 4 years of therapy

Observations of SN 2017ein Reveal Shock Breakout Emission and A Massive Progenitor Star for a Type Ic Supernova

We present optical and ultraviolet observations of nearby type Ic supernova SN 2017ein as well as detailed analysis of its progenitor properties from both the early-time observations and the prediscovery Hubble Space Telescope (HST) images. The optical light curves started from within one day to $\sim$275 days after explosion, and optical spectra range from $\sim$2 days to $\sim$90 days after explosion. Compared to other normal SNe Ic like SN 2007gr and SN 2013ge, \mbox{SN 2017ein} seems to have more prominent C{\footnotesize II} absorption and higher expansion velocities in early phases, suggestive of relatively lower ejecta mass. The earliest photometry obtained for \mbox{SN 2017ein} show indications of shock cooling. The best-fit obtained by including a shock cooling component gives an estimate of the envelope mass as $\sim$0.02 M$_{\odot}$ and stellar radius as 8$\pm$4 R$_{\odot}$. Examining the pre-explosion images taken with the HST WFPC2, we find that the SN position coincides with a luminous and blue point-like source, with an extinction-corrected absolute magnitude of M$_V$$\sim$$-$8.2 mag and M$_I$$\sim$$-$7.7 mag.Comparisons of the observations to the theoretical models indicate that the counterpart source was either a single WR star or a binary with whose members had high initial masses, or a young compact star cluster. To further distinguish between different scenarios requires revisiting the site of the progenitor with HST after the SN fades away.Comment: 28 pages, 19 figures; accepted for publication in The Astrophysical Journa