Mitomycin C potentiates ultraviolet-related cytotoxicity in corneal fibroblasts

Pharmacokinetics and safety of early nevirapine-based antiretroviral therapy for neonates at high risk for perinatal HIV infection: a phase 1/2 proof of concept study

BACKGROUND

With increasing intention to treat HIV as early as possible, evidence to confirm the safety and therapeutic drug concentrations of a nevirapine-based antiretroviral regimen in the early neonatal period is needed. This study aims to establish dosing of nevirapine for very early treatment of HIV-exposed neonates at high risk of HIV acquisition.

METHODS

IMPAACT P1115 is a multinational phase 1/2 proof-of-concept study in which presumptive treatment for in-utero HIV infection is initiated within 48 h of birth in HIV-exposed neonates at high risk of HIV acquisition. Participants were neonates who were at least 34 weeks gestational age at birth and enrolled within 48 h of birth, born to women with presumed or confirmed HIV infection who had not received antiretrovirals during this pregnancy. The regimen consisted of two nucleoside reverse transcriptase inhibitors plus nevirapine dosed at 6 mg/kg twice daily for term neonates (≥37 weeks gestational age) or 4 mg/kg twice daily for 1 week and 6 mg/kg twice daily thereafter for preterm neonates (34 to <37 weeks gestational age). Here, we report the secondary outcomes of the study: nevirapine exposures in study weeks 1 and 2 and treatment-associated grade 3 or 4 adverse events at least possibly related to study treatment up to study week 4. A population pharmacokinetic model to assess nevirapine exposure was developed from dried blood spot and plasma nevirapine concentrations at study weeks 1 and 2. Nevirapine exposure was assessed in all patients with available blood samples and safety was assessed in all participants. This trial is registered at ClinicalTrials.gov (NCT02140255).

FINDINGS

Between Jan 23, 2015, and Sept 4, 2017, 438 neonates were enrolled and included in analyses; 36 had in-utero HIV infection and 389 (89%) were born at term. Neonates without confirmed in-utero HIV infection received nevirapine for a median of 13 days (IQR 7-14). Measured dried blood spot nevirapine concentrations were higher than the minimum HIV treatment target (3 μg/mL) in 314 (90%, 95% CI 86-93) of 349 neonates at week 1 and 174 (87%, 81-91) of 201 at week 2. In Monte-Carlo simulations, week 1 nevirapine concentrations exceeded 3 μg/mL in 80% of term neonates and 82% of preterm neonates. DAIDS grade 3 or 4 adverse events at least possibly related to antiretrovirals occurred in 30 (7%, 95% CI 5-10) of 438 infants but did not lead to nevirapine cessation in any neonates; neutropenia (25 [6%] neonates) and anaemia (six [1%]) were most common.

INTERPRETATION

Nevirapine at the dose studied was confirmed to be safe and provides therapeutic exposure concentrations. These data support nevirapine as a component of presumptive HIV treatment in high-risk neonates.

FUNDING

National Institute of Allergy and Infectious Diseases, Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the National Institute of Mental Health.

Reduced Time to Suppression Among Neonates With HIV Initiating Antiretroviral Therapy Within 7 Days After Birth

There are limited data on infants with HIV starting antiretroviral therapy (ART) in the neonatal period. We investigated the association between the timing of ART initiation and time-to-suppression among infants who tested HIV-positive and initiated ART within the first 28 days of life. The effect was estimated using cumulative probability flexible parametric spline models and a multivariable generalized additive mixed model was performed to test nonlinear associations. Forty-four neonates were included. Nineteen (43.2%) initiated ART within 7 days of life and 25 (56.8%) from 8 to 28 days. Infants treated within 7 days were 4-fold more likely to suppress earlier than those treated after 7 days [Hazard ratio (HR) 4.01 (1.7-9.5)]. For each week the ART initiation was delayed, the probability of suppression decreased by 35% (HR 0.65 [0.46-0.92]). Age at ART start was linearly associated with time-to-suppression. However, a linear association with normally distributed residuals was not found between baseline viral load and time-to-suppression, with no association found when baseline viral loads were ≤5 log(10) copies/mL, but with exponential increase in time-to-suppression with > log5 copies/mL at baseline. Starting ART within 7 days of life led to 4-fold faster time to viral suppression, in comparison to initiation from 8 to 28 days.

Optimizing Pediatric Dosing Recommendations and Treatment Management of Antiretroviral Drugs Using Therapeutic Drug Monitoring Data in Children Living With HIV

INTRODUCTION

This review summarizes the current dosing recommendations for antiretroviral (ARV) drugs in the international pediatric guidelines of the World Health Organization (WHO), US Department of Health and Human Services (DHHS), and Pediatric European Network for Treatment of AIDS (PENTA), and evaluates the research that informed these approaches. We further explore the role of data generated through therapeutic drug monitoring in optimizing the dosing of ARVs in children.

METHODS

A PubMed search was conducted for the literature on ARV dosing published in English. In addition, the registration documentation of European Medicines Agency and the US Food and Drug Administration for currently used ARVs and studies referenced by the WHO, DHHS, and EMA guidelines were screened. Resulting publications were screened for papers containing data on the area under the concentration-time curve, trough concentration, and peak concentration. Studies with enrolled participants with a median or mean age of ≥18 years were excluded. No restriction on publishing date was applied.

DISCUSSION AND CONCLUSION

Pediatric ARV dosing is frequently based on data obtained from small studies and is often simplified to facilitate dosing in the context of a public health approach. Pharmacokinetic parameters of pediatric ARVs are subject to high interpatient variation and this leads to a potential risk of underdosing or overdosing when drugs are used in real life. To ensure optimal use of ARVs and validate dosing recommendations for children, it is essential to monitor ARV dosing more thoroughly with larger sample sizes and to include diverse subpopulations. Therapeutic drug monitoring data generated in children, where available and affordable, have the potential to enhance our understanding of the appropriateness of simplified pediatric dosing strategies recommended using a public health approach and to uncover suboptimal dosing or other unanticipated issues postmarketing, further facilitating the ultimate goal of optimizing pediatric ARV treatment.

Nevirapine Concentrations During the First Month of Life and Maternal Efavirenz Washout in High-Risk HIV-Exposed Infants Receiving Triple Antiretroviral Prophylaxis

BACKGROUND

Triple-drug infant antiretroviral prophylaxis containing nevirapine (NVP) is increasingly used to prevent HIV transmission among neonates at high risk of HIV infection. Our aim was to describe NVP concentration from birth through the first month of life.

METHODS

High-risk HIV-exposed neonates were enrolled in a prospective cohort in Thailand. High-risk neonates defined as maternal HIV RNA >50 copies/mL before delivery or mother received antiretroviral treatment for <12 weeks before delivery. Neonates received zidovudine (4 mg/kg) and lamivudine (2 mg/kg) twice daily, plus NVP (4 mg/kg) once daily (no lead-in) from birth to 6 weeks of life. Infant plasma samples were collected at 1, 2, 14 or 2, 7, 28 days of life. NVP trough concentrations (C24) were estimated using a population pharmacokinetic model and target C24 was ≥0.1 mg/L. "Washout" efavirenz (EFV) concentrations were assessed in infants whose mother received EFV-based antiretroviral treatment.

RESULTS

A total of 48 infants were included: 25 (52%) were male and 12 (25%) were preterm (gestational age 34-37 weeks). Median (interquartile range) predicted NVP C24 were 1.34 mg/L (1.13-1.84), 2.24 (2.00-2.59), 2.78 (2.61-3.12), 2.20 (1.86-2.44) and 0.81 (0.58-0.98) on days 1, 2, 7, 14 and 28 of life, respectively. NVP C24 was not significantly different between term and preterm infants. All infants maintained NVP C24 ≥0.1 mg/L. EFV via placental transfer remained detectable in infants up to 7 days of life.

CONCLUSIONS

NVP 4 mg/kg daily from birth provided adequate prophylactic concentrations during the first month of life in high-risk HIV-exposed neonates.

The protective effect of simvastatin against ultraviolet B-induced corneal endothelial cell death

Purpose:

Excessive ultraviolet B (UVB) exposure causing corneal endothelium injury, including apoptosis, is a serious condition. Therefore, drugs that can inhibit apoptosis in corneal endothelial cells represent an effective strategy. Simvastatin is widely used as a specific inhibitor of 3-hydroxy-3-methyl-glutaryl-CoA reductase, can reduce levels of low density lipoprotein (LDL) cholesterol, and exerts anti-inflammatory effects. However, the protective effect of simvastatin on corneal endothelial cells remains unclear. Therefore, the aim of this study was to elucidate whether UVB promotes the initiation of apoptosis in corneal endothelial cells and injury reversible by simvastatin treatment.

Methods:

We detected the cell viability, subG1 population, and caspase-3 activity.

Results:

Results showed that simvastatin alleviates UVB-induced cell death, cell apoptosis, and caspase-3 activity.

Conclusion:

Our findings indicated that simvastatin alleviated UVB-induced corneal endothelial cell apoptosis via caspase-3 activity.

Nevirapine Pharmacokinetics and Safety in Neonates Receiving Combination Antiretroviral Therapy for Prevention of Vertical HIV Transmission

BACKGROUND

Nevirapine (NVP)-based combination antiretroviral therapy is routinely prescribed to infants deemed at high risk of vertical HIV infection in our centers. We evaluated NVP pharmacokinetics and safety of this regimen.

METHODS

Neonates were recruited prospectively between September 2012 and April 2015 or enrolled retrospectively if treated similarly before prospective study initiation. NVP was dosed at 150 mg/m daily for 14 days, then twice daily for 14 days. NVP levels were drawn at weeks 1, 2, and 4 [target trough (NVP-T): 3-8 mg/L].

RESULTS

Thirty-three neonates were included (23 prospectively). Median gestational age (GA) and birth weight were 38 weeks (32-41 weeks) and 2.9 kg (1.5-4.2 kg), respectively. Median NVP-Ts were 8.2 mg/L (1.6-25.1 mg/L), 3.5 mg/L (1.6-6.8 mg/L), and 4.3 mg/L (0.1-19.9 mg/L) at weeks 1, 2, and 4, respectively. The proportions with therapeutic NVP-T were 42%, 61%, and 73% at these same timepoints. Median apparent oral clearance (CL/F) increased from 0.05 L·kg·h (0.01-0.50 L·kg·h) at week 2 to 0.18 L·kg·h (0.01-0.78 L·kg·h) at week 4. Increased drug exposure [area under the curve (AUCτ)] correlated with younger GA (r = 0.459, P = 0.032) and lower birth weight (r = 0.542, P = 0.009). The most common adverse events potentially attributable to combination antiretroviral therapy were transient asymptomatic hyperlactatemia (26%), anemia (24.7%), and neutropenia (22.1%).

CONCLUSIONS

Treatment dose NVP was generally well-tolerated and associated with normalization of trough levels over time in most cases without dose adjustment. Lower empiric dosing is recommended for infants <34 weeks of GA. Routine therapeutic drug monitoring may not be required for infants ≥34 weeks of GA.

Macrophage phagocytosis alters the MRI signal of ferumoxytol-labeled mesenchymal stromal cells in cartilage defects

Human mesenchymal stem cells (hMSCs) are a promising tool for cartilage regeneration in arthritic joints. hMSC labeling with iron oxide nanoparticles enables non-invasive in vivo monitoring of transplanted cells in cartilage defects with MR imaging. Since graft failure leads to macrophage phagocytosis of apoptotic cells, we evaluated in vitro and in vivo whether nanoparticle-labeled hMSCs show distinct MR signal characteristics before and after phagocytosis by macrophages. We found that apoptotic nanoparticle-labeled hMSCs were phagocytosed by macrophages while viable nanoparticle-labeled hMSCs were not. Serial MRI scans of hMSC transplants in arthritic joints of recipient rats showed that the iron signal of apoptotic, nanoparticle-labeled hMSCs engulfed by macrophages disappeared faster compared to viable hMSCs. This corresponded to poor cartilage repair outcomes of the apoptotic hMSC transplants. Therefore, rapid decline of iron MRI signal at the transplant site can indicate cell death and predict incomplete defect repair weeks later. Currently, hMSC graft failure can be only diagnosed by lack of cartilage defect repair several months after cell transplantation. The described imaging signs can diagnose hMSC transplant failure more readily, which could enable timely re-interventions and avoid unnecessary follow up studies of lost transplants.

Serious adverse events are uncommon with combination neonatal antiretroviral prophylaxis: a retrospective case review

Six weeks of zidovudine (ZDV) is recommended for postnatal prophylaxis of HIV-exposed infants, but combination antiretrovirals are indicated if HIV transmission risk is increased. We investigated the frequency and severity of adverse events (AE) in infants receiving multiple drug prophylaxis compared to ZDV alone. In this retrospective review of 148 HIV-exposed uninfected infants born between 1997–2009, we determined clinical and laboratory AE that occurred between days of life 8–42. Thirty-six infants received combination prophylaxis; among those, a three-drug regimen containing ZDV, lamivudine, and nevirapine was most common (53%). Rates of laboratory AE grade ≥1 were as follows for the combination prophylaxis and ZDV alone groups, respectively: neutropenia 55% and 39%; anemia 50% and 39%; thrombocytopenia 0 and 3%; elevated aspartate aminotransferase 3% and 3%; elevated alanine aminotransferase 0 and 1%; hyperbilirubinemia 19% and 42%. Anemia occurred more frequently in infants who received three-drug prophylaxis compared to infants who received ZDV alone (63% vs. 39%, p = 0.04); all anemia AE were grade 1 or 2 in the three-drug prophylaxis group. Overall, 75% of infants on combination prophylaxis and 66% of infants on ZDV alone developed grade ≥1 AE (p = 0.32), and 17% of infants in either group developed grade ≥3 AE. Stavudine was substituted for ZDV in 23 infants due to anemia or neutropenia. After this antiretroviral change, 50% of evaluable infants demonstrated improvement in AE grade, and 25% had no change. In conclusion, low grade anemia, neutropenia, and hyperbilirubinemia occurred frequently regardless of the prophylactic regimen, but serious AE were uncommon. Although most AE were typical of ZDV toxicity, the combination of ZDV with lamivudine and nevirapine resulted in an increased frequency of low-grade anemia. Further studies are needed to identify prophylactic regimens with less toxicity for infants born to HIV-infected mothers.

Is infant exposure to antiretroviral drugs during breastfeeding quantitatively important? A systematic review and meta-analysis of pharmacokinetic studies

Objectives

The objectives of this study were to summarize antiretroviral drug concentrations in breast milk (BM) and exposure of breast-fed infants.

Methods

This was a systematic review of pharmacokinetic studies of HIV-positive women taking antiretrovirals that measured drugs in BM. The quality of pharmacokinetic and laboratory methods was assessed using pre-defined criteria. Pooled ratios and 95% CIs were calculated using the generalized inverse variance method and heterogeneity was estimated by the I² statistic. PubMed Central, SCOPUS and LactMed databases were searched. No date or language restrictions were applied. Searches were conducted up to 10 November 2014. Clinical relevance was estimated by comparing ingested dose with the recommended therapeutic dose for each drug.

Results

Twenty-four studies were included. There was substantial variability in the clinical and laboratory methods used and in reported results. Relative to maternal plasma (MP), NRTIs accumulate in BM, with BM : MP ratios (95% CI estimates) from 0.89 to 1.21 (14 studies, 1159 paired BM and MP samples). NNRTI estimates were from 0.71 to 0.94 (17 studies, 965 paired samples) and PI estimates were from 0.17 to 0.21 (8 studies, 477 paired samples). Relative to the recommended paediatric doses, a breast-fed infant may ingest 8.4% (95% CI 1.9–15.0), 12.5% (95% CI 2.6–22.3) and 1.1% (95% CI 0–3.6) of lamivudine, nevirapine and efavirenz, respectively, via BM.

Conclusions

Transfer to untreated infants appears quantitatively important for some NRTIs and NNRTIs. The pharmacokinetic methods varied widely and we propose standards for the design, analysis and reporting of future pharmacokinetic studies of drug transfer during breastfeeding.

Evaluation of nevirapine dosing recommendations in HIV-infected children

AIMS

Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor used for chronic human immunodeficiency virus infections in adults and children. The aims of this study were to investigate the population pharmacokinetics of NVP in children, establish factors that influence NVP pharmacokinetics and evaluate the current dosing recommendations.

METHODS

Concentrations were measured on a routine basis in 94 children aged from 2 months to 17 years. A total of 390 NVP plasma concentrations were retrospectively collected, and a population pharmacokinetic model was developed with Monolix 4.0.

RESULTS

Nevirapine pharmacokinetics was best described by a one-compartment model with first-order absorption and elimination. After standardization to a 70 kg adult using allometry, postmenstrual age had a significant effect on the bioavailability. Estimates of apparent clearance and volume of distribution were 3.9 l h(-1) (70 kg)(-1) and 140 l (70 kg)(-1) , respectively. Based on simulations of European Medicines Agency (EMA) and World Health Organization (WHO) dosing recommendations, the probability of observing minimal concentrations below the efficacy target of 3 mg l(-1) is higher following the EMA recommendations than the WHO recommendations. However, NVP underdosing persists for the 3-6 and 6-10 kg weight ranges following the WHO recommendations.

CONCLUSIONS

It is suggested to increase doses to 75 and 100 mg twice daily for the 3-6 and 6-10 kg weight ranges, respectively, in order to obtain more than 95% of children with concentrations above 3 mg l(-1) .

Moxifloxacin modifies corneal fibroblast-to-myofibroblast differentiation

BACKGROUND AND PURPOSE

Fibroblast-to-myofibroblast differentiation is associated with scarring, an important issue in corneal surgery. Moxifloxacin (MOX), commonly applied to prevent post-operative infection, would benefit more if it modifies fibroblast-to-myofibroblast differentiation other than antimicrobial activity. Our purpose was to explore whether MOX has anti-fibrotic effect in human corneal fibroblasts (HCFs).

EXPERIMENTAL APPROACH

HCFs were incubated in MOX-containing medium concurrently with TGF-β1 (co-treatment), before (pretreatment) or after (post-treatment) adding TGF-β1. HCF contractility was evaluated with a type I collagen gel contraction assay. Expression of α-smooth muscle actin (α-SMA), Smad2, phospho-Smad2-Ser467, Smad4 and Smad7 was determined by immunoblotting. Formation of α-SMA-positive filaments and distribution of active Smad2 were observed under confocal microscopy. Expression of TGF-β receptor types I (TGFBR1) and II (TGFBR2) was assessed with flow cytometry.

KEY RESULTS

MOX did not affect gel contractility or α-SMA filament formation in HCFs without TGF-β1 stimulation. MOX did, however, retard HCF-containing gel contractility and α-SMA filament formation following TGF-β1 stimulation in the pretreatment and co-treatment groups but not in the post-treatment group. MOX blocked the expression of Smad2, phospho-Smad2-Ser467 and TGFBR1 under TGF-β1 incubation. Additionally, MOX enhanced Smad7 expression in TGF-β1-incubated HCFs, but did not interfere with TGF-β-triggered Smad2 nuclear translocation or Smad4 expression.

CONCLUSIONS AND IMPLICATIONS

MOX inhibited TGF-β-induced fibroblast-to-myofibroblast differentiation via blocking TGFBR1 and enhancing Smad7 expression. MOX should be used before or during surgery to achieve these effects. These results suggest a de novo mechanism by which MOX participates in corneal wound healing.

Translation of biomedical prevention strategies for HIV: prospects and pitfalls

Early achievements in biomedical approaches for HIV prevention included physical barriers (condoms), clean injection equipment (both for medical use and for injection drug users), blood and blood product safety, and prevention of mother-to-child transmission. In recent years, antiretroviral drugs to reduce the risk of transmission (when the infected person takes the medicines; treatment as prevention) or reduce the risk of acquisition (when the seronegative person takes them; preexposure prophylaxis) have proven to be efficacious. Circumcision of men has also been a major tool relevant for higher prevalence regions such as sub-Saharan Africa. Well-established prevention strategies in the control of sexually transmitted diseases and tuberculosis are highly relevant for HIV (ie, screening, linkage to care, early treatment, and contact tracing). Unfortunately, only slow progress is being made in some available HIV-prevention strategies such as family planning for HIV-infected women who do not want more children and prevention of mother-to-child HIV transmission. Current studies seek to integrate strategies into approaches that combine biomedical, behavioral, and structural methods to achieve prevention synergies. This review identifies the major biomedical approaches demonstrated to be efficacious that are now available. We also highlight the need for behavioral risk reduction and adherence as essential components of any biomedical approach.

Intravenous ferumoxytol allows noninvasive MR imaging monitoring of macrophage migration into stem cell transplants

PURPOSE

To develop a clinically applicable imaging technique for monitoring differential migration of macrophages into viable and apoptotic matrix-associated stem cell implants (MASIs) in arthritic knee joints.

MATERIALS AND METHODS

With institutional animal care and use committee approval, six athymic rats were injected with intravenous ferumoxytol (0.5 mmol iron per kilogram of body weight) to preload macrophages of the reticuloendothelial system with iron oxide nanoparticles. Forty-eight hours later, all animals received MASIs of viable adipose-derived stem cells (ADSCs) in an osteochondral defect of the right femur and mitomycin-pretreated apoptotic ADSCs in an osteochondral defect of the left femur. One additional control animal each received intravenous ferumoxytol and bilateral scaffold-only implants (without cells) or bilateral MASIs without prior ferumoxytol injection. All knees were imaged with a 7.0-T magnetic resonance (MR) imaging unit with T2-weighted fast spin-echo sequences immediately after, as well as 2 and 4 weeks after, matrix-associated stem cell implantation. Signal-to-noise ratios (SNRs) of viable and apoptotic MASIs were compared by using a linear mixed-effects model. MR imaging data were correlated with histopathologic findings.

RESULTS

All ADSC implants showed a slowly decreasing T2 signal over 4 weeks after matrix-associated stem cell implantation. SNRs decreased significantly over time for the apoptotic implants (SNRs on the day of matrix-associated stem cell implantation, 2 weeks after the procedure, and 4 weeks after the procedure were 16.9, 10.9, and 6.7, respectively; P = .0004) but not for the viable implants (SNRs on the day of matrix-associated stem cell implantation, 2 weeks after the procedure, and 4 weeks after the procedure were 17.7, 16.2, and 15.7, respectively; P = .2218). At 4 weeks after matrix-associated stem cell implantation, SNRs of apoptotic ADSCs were significantly lower than those of viable ADSCs (mean, 6.7 vs 15.7; P = .0013). This corresponded to differential migration of iron-loaded macrophages into MASIs.

CONCLUSION

Iron oxide loading of macrophages in the reticuloendothelial system by means of intravenous ferumoxytol injection can be utilized to monitor differential migration of bone marrow macrophages into viable and apoptotic MASIs in a rat model.

Three postpartum antiretroviral regimens to prevent intrapartum HIV infection

BACKGROUND

The safety and efficacy of adding antiretroviral drugs to standard zidovudine prophylaxis in infants of mothers with human immunodeficiency virus (HIV) infection who did not receive antenatal antiretroviral therapy (ART) because of late identification are unclear. We evaluated three ART regimens in such infants.

METHODS

Within 48 hours after their birth, we randomly assigned formula-fed infants born to women with a peripartum diagnosis of HIV type 1 (HIV-1) infection to one of three regimens: zidovudine for 6 weeks (zidovudine-alone group), zidovudine for 6 weeks plus three doses of nevirapine during the first 8 days of life (two-drug group), or zidovudine for 6 weeks plus nelfinavir and lamivudine for 2 weeks (three-drug group). The primary outcome was HIV-1 infection at 3 months in infants uninfected at birth.

RESULTS

A total of 1684 infants were enrolled in the Americas and South Africa (566 in the zidovudine-alone group, 562 in the two-drug group, and 556 in the three-drug group). The overall rate of in utero transmission of HIV-1 on the basis of Kaplan-Meier estimates was 5.7% (93 infants), with no significant differences among the groups. Intrapartum transmission occurred in 24 infants in the zidovudine-alone group (4.8%; 95% confidence interval [CI], 3.2 to 7.1), as compared with 11 infants in the two-drug group (2.2%; 95% CI, 1.2 to 3.9; P=0.046) and 12 in the three-drug group (2.4%; 95% CI, 1.4 to 4.3; P=0.046). The overall transmission rate was 8.5% (140 infants), with an increased rate in the zidovudine-alone group (P=0.03 for the comparisons with the two- and three-drug groups). On multivariate analysis, zidovudine monotherapy, a higher maternal viral load, and maternal use of illegal substances were significantly associated with transmission. The rate of neutropenia was significantly increased in the three-drug group (P<0.001 for both comparisons with the other groups).

CONCLUSIONS

In neonates whose mothers did not receive ART during pregnancy, prophylaxis with a two- or three-drug ART regimen is superior to zidovudine alone for the prevention of intrapartum HIV transmission; the two-drug regimen has less toxicity than the three-drug regimen. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development [NICHD] and others; ClinicalTrials.gov number, NCT00099359.).

Pharmacokinetics and safety of single-dose tenofovir disoproxil fumarate and emtricitabine in HIV-1-infected pregnant women and their infants

Tenofovir (TFV) is effective in preventing simian immunodeficiency virus (SIV) transmission in a macaque model, is available as the oral agent tenofovir disoproxil fumarate (TDF), and may be useful in the prevention of mother-to-child transmission of human immunodeficiency virus (HIV). We conducted a trial of TDF and TDF-emtricitabine (FTC) in HIV-infected pregnant women and their infants. Women received a single dose of either 600 mg TDF, 900 mg TDF, or 900 mg TDF-600 mg FTC at labor onset or prior to a cesarean section. Infants received no drug or a single dose of TDF at 4 mg/kg of body weight or of TDF at 4 mg/kg plus FTC at 3 mg/kg as soon as possible after birth. All regimens were safe and well tolerated. Maternal areas under the serum concentration-time curve (AUC) and concentrations at the end of sampling after 24 h (C(24)) were similar between the two doses of TDF; the maximum concentrations of the drugs in serum (C(max)) and cord blood concentrations were higher in women delivering via cesarean section than in those who delivered vaginally (P = 0.04 and 0.046, respectively). The median ratio of the TFV concentration in cord blood to that in the maternal plasma at delivery was 0.73 (range, 0.26 to 1.95). Without TDF administration, infants had a median TFV concentration of 12 ng/ml 12 h after birth. Following administration of a single dose of TDF at 4 mg/kg, infant TFV concentrations fell below the targeted level, 50 ng/ml, by 24 h postdose. In HIV-infected pregnant women and their infants, 600 mg of TDF is acceptable as a single dose during labor. Low concentrations at birth support infant dosing as soon after birth as possible. Rapidly decreasing TFV levels in infants suggest that multiple or higher doses of TDF will be necessary to maintain concentrations that are effective for viral suppression.

Nelfinavir and Lamivudine pharmacokinetics during the first two weeks of life

BACKGROUND

There are no previous data describing nelfinavir and lamivudine pharmacokinetics in neonates treated with weight-band dosing regimens.

DESIGN

Pharmacokinetic study of nelfinavir and lamivudine pharmacokinetics in infants during the first 2 weeks of life treated with weight-band dosing regimens.

METHODS

Intensive 12-hour pharmacokinetic profiles were performed between either days 4-7 or days 10-14 of life in 26 Brazilian infants.

RESULTS

Pharmacokinetic data were obtained from 26 infants who received median (range) per kg doses of 58.8 (48.4-79.0) mg/kg for nelfinavir and 2.0 (1.5-3.2) mg/kg for lamivudine. Median nelfinavir 12-hour AUC (AUC0-12) was 25.5 (1.7-183.5) μg*h/mL and median 12-hour concentration (C12h) was 1.09 (<0.04-14.44) μg/mL. AUC0-12 was less than 15 μg*h/mL (the 10% for adults) in 12 infants (46%). Median lamivudine AUC0-12 was 7.8 (2.7-15.6) μg*h/mL and median C12h was 0.23 (<0.04-0.74) μg/mL.

CONCLUSIONS

: Lamivudine pharmacokinetic parameters observed in this study were consistent with those seen in other studies of neonates. While median nelfinavir AUC and C12h in these neonates were above the exposure targets, interindividual variability in nelfinavir exposure was large and nelfinavir exposure failed to meet the exposure targets in 46% of infants.

MR signal characteristics of viable and apoptotic human mesenchymal stem cells in matrix-associated stem cell implants for treatment of osteoarthritis

OBJECTIVE

To compare magnetic resonance (MR) signal characteristics of contrast agent-labeled apoptotic and viable human mesenchymal stem cells (hMSCs) in matrix-associated stem cell implants.

METHODS

hMSCs were labeled with Food and Drug Administration-approved ferumoxides nanoparticles. One group (A) remained untreated whereas a second group (B) underwent mitomycin C-induced apoptosis induction. Viability of group A and apoptosis of group B was confirmed by caspase-assays and terminal dUTP nick-end labeling (TUNEL) stains. Labeled viable hMSCs, unlabeled viable hMSCs, labeled apoptotic hMSCs, and unlabeled apoptotic hMSCs (n = 7 samples each) in an agarose scaffold were implanted into cartilage defects of porcine patellae specimens and underwent MR imaging at 7 T, using T1-weighted spin-echo sequences, T2-weighted spin-echo sequences, and T2*-weighted gradient-echo sequences. Signal-to-noise ratios (SNR) of the implants were calculated and compared between different experimental groups using linear mixed regression models.

RESULTS

Ferumoxides-labeled hMSCs provided a strong negative T2 and T2*-enhancement. Corresponding SNR data of labeled hMSCs were significantly lower compared with unlabeled controls (P < 0.05). Apoptosis induction resulted in a significant signal decline of ferumoxides-labeled hMSC transplants on short echo time T2-weighted spinecho sequences. SNR data of labeled apoptotic hMSCs were significantly lower compared with labeled viable hMSCs (P < 0.05).

CONCLUSION

Apoptosis of transplanted ferumoxides-labeled stem cells in cartilage defects can be visualized noninvasively by a significant signal decline on T2-weighted MR images. The described MR signal characteristics may serve as a noninvasive outcome measure for the assessment of matrix-associated stem cell implants in clinical practice. Additional studies are needed to further enhance the observed differences between viable and apoptotic cells, for example, by further optimizing the applied MR pulse sequence parameters or intracellular contrast agent concentration.

Dexamethasone reduces mitomycin C-related inflammatory cytokine expression without inducing further cell death in corneal fibroblasts

The purpose of this study was to investigate the effect of dexamethasone (DEX) on mitomycin C (MMC)-induced inflammatory cytokine expression in corneal fibroblasts. Primary human corneal fibroblasts were treated with MMC, dexamethasone, or in combination. Morphological changes and cell growth were documented using phase-contrast microscopy and PicoGreen assay, respectively. Cell apoptosis was evaluated by annexin V/propidium iodide staining, whereas viability was tested by the live/dead assay and analyzed by flow cytometry. The relative expression of interleukin-8 and monocyte chemoattractant protein-1 was investigated with quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Mitogen-activated protein kinase activation and mitogen-activated protein kinase phosphatase-1 expression were documented by Western blot analysis. We found that MMC induced corneal fibroblast elongation, apoptosis, and retarded cell growth, whereas DEX did not significantly alter cell morphology or viability. The combination of DEX and MMC did not induce additional apoptosis and cell death. DEX dose dependently down-regulated basal and MMC-induced interleukin-8 and monocyte chemoattractant protein-1 mRNA expression and protein secretion. DEX attenuated MMC-induced p38 and Jun N-terminal kinases activation and up-regulated expression. These suggested that DEX may inhibit MMC-induced interleukin-8 and monocyte chemoattractant protein-1 by up-regulating MKP-1 expression, which subsequently deactivated p38 and Jun N-terminal kinases activation. Combined MMC and DEX treatment may facilitate corneal wound healing.

Mitomycin C in corneal refractive surgery

Mitomycin C has played a deciding role in the current revival of excimer laser surface ablation techniques. We review the literature regarding mechanism of action of mitomycin C, histological effects on the cornea, and indications, dose, exposure time, and toxicity of mitomycin C in corneal refractive surgery. Mitomycin C is an alkylating agent with cytotoxic and antiproliferative effects that reduces the myofibroblast repopulation after laser surface ablation and, therefore, reduces the risk of postoperative corneal haze. It is used prophylactically to avoid haze after primary surface ablation and therapeutically to treat pre-existing haze. There is no definite evidence that establishes an exact diopter limit or ablation depth at which to apply prophylactic mitomycin C. It is usually applied at a concentration of 0.2mg/ml (0.02%) for 12 to 120 seconds over the ablated stroma, although some studies suggest that lower concentrations (0.01%, 0.002%) could also be effective in preventing haze when treating low to moderate myopia. This dose of mitomycin C has not been associated with any clinically relevant epithelial corneal toxicity. Its effect on the endothelium is more controversial: two studies report a decrease in endothelial cell density, but the majority of reports suggest that the endothelium is not altered. Regarding mitomycin C's effect on keratocyte population, although animal studies report keratocyte depletion after its use, longer follow-up suggested that the initial keratocyte depletion does not persist over time.

Advances and failures in preventing perinatal human immunodeficiency virus infection

An estimated 2.5 million children are currently living with HIV, the vast majority as a result of mother-to-child transmission. Prevention of perinatal HIV infection has been immensely successful in developed countries. A comprehensive package of services, including maternal and infant antiretroviral therapy, elective cesarean section, and avoidance of breast-feeding, has resulted in transmission rates of less than 2%. However, in developing countries, access to such services is often not available, as demonstrated by the fact that the vast majority of children with HIV live in Africa. Over the past few years, many developing nations have made great strides in improving access to much-needed services. Notably, in eastern and southern Africa, the regions most affected by HIV, mother-to-child-transmission coverage rates for HIV-positive women increased from 11% in 2004 to 31% in 2006. These successes are deserving of recognition, while not losing sight of the fact that much remains to be done; currently, an estimated 75% of pregnant women worldwide have an unmet need for antiretroviral therapy. Further work is needed to determine the optimal strategy for reducing perinatal transmission among women in resource-poor settings, with a particular need for reduction of transmission via breast-feeding.

Persistence of nevirapine in breast milk and plasma of mothers and their children after single-dose administration

OBJECTIVES

Nevirapine is widely used in the developing world for the prevention of mother-to-child transmission (PMTCT) of HIV. A single mutation in the HIV genome is sufficient to lead to significant nevirapine resistance. Persistence of low-level drug concentrations in body compartments can foster resistance formation. In this study, concentration-time courses of nevirapine after single-dose administration were analysed over an extended post-partum period.

PATIENTS AND METHODS

Breast milk and plasma samples of 62 HIV-positive Ugandan mother-child pairs who had received single-dose nevirapine were collected at delivery and 1, 2 and 6 weeks post-partum. Nevirapine concentrations were quantified by LC/tandem-mass-spectrometry using a quantification limit of 15 ng/mL, and a population pharmacokinetic (PK) analysis was performed.

RESULTS

Concentration-time profiles in breast milk, maternal plasma and child plasma showed similar shapes. At week 1, median nevirapine concentrations were 164 ng/mL in maternal plasma, 114 ng/mL in breast milk and 183 ng/mL in child plasma. The population PK model predicted nevirapine concentrations>10 ng/mL (IC50 for nevirapine) for 13 days in breast milk, 14 days in maternal plasma and 18 days in child plasma in 80% of the samples.

CONCLUSIONS

Nevirapine concentrations were present for 2-3 weeks in the three compartments. The concentrations are probably sufficiently high to protect most breastfed children from HIV transmission during the first 2 weeks. The long presence of slowly decreasing levels of nevirapine is likely to induce resistance formation. Post-natal addition of antiretrovirals for 1 week only, as recommended in the current PMTCT guidelines, will not suffice to avoid nevirapine resistance formation.