Browsing by Subject "Linear Models"

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    Open Access
    Could cash and good parenting affect child cognitive development? A cross-sectional study in South Africa and Malawi
    (2017) Sherr, Lorraine; Macedo, Ana; Tomlinson, Mark; Skeen, Sarah; Cluver, Lucie Dale
    BACKGROUND: Social protection interventions, including cash grants and care provision have been shown to effectively reduce some negative impacts of the HIV epidemic on adolescents and families. Less is known about the role of social protection on younger HIV affected populations. This study explored the impact of cash grants on children's cognitive development. Additionally, we examined whether combined cash and care (operationalised as good parenting) was associated with improved cognitive outcomes. METHODS: The sample included 854 children, aged 5 - 15, participating in community-based organisation (CBO) programmes for children affected by HIV in South Africa and Malawi. Data on child cognitive functioning were gathered by a combination of caregiver report and observer administered tests. Primary caregivers also reported on the economic situation of the family, cash receipt into the home, child and household HIV status. Parenting was measured on a 10 item scale with good parenting defined as a score of 8 or above. RESULTS: About half of families received cash (55%, n = 473), only 6% (n = 51) reported good parenting above the cut-off point but no cash, 18% (n = 151) received combined cash support and reported good parenting, and 21% (n = 179) had neither. Findings show that cash receipt was associated with enhanced child cognitive outcomes in a number of domains including verbal working memory, general cognitive functioning, and learning. Furthermore, cash plus good parenting provided an additive effect. Child HIV status had a moderating effect on the association between cash or/plus good parenting and cognitive outcomes. The association between cash and good parenting and child cognitive outcomes remained significant among both HIV positive and negative children, but overall the HIV negative group benefited more. CONCLUSIONS: This study shows the importance of cash transfers and good parenting on cognitive development of young children living in HIV affected environments. Our data clearly indicate that combined provision (cash plus good parenting) have added value.
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    Open Access
    Maternal blood contamination of collected cord blood can be identified using DNA methylation at three CpGs
    (2017) Jones, Meaghan J
    Abstract Background Cord blood is a commonly used tissue in environmental, genetic, and epigenetic population studies due to its ready availability and potential to inform on a sensitive period of human development. However, the introduction of maternal blood during labor or cross-contamination during sample collection may complicate downstream analyses. After discovering maternal contamination of cord blood in a cohort study of 150 neonates using Illumina 450K DNA methylation (DNAm) data, we used a combination of linear regression and random forest machine learning to create a DNAm-based screening method. We identified a panel of DNAm sites that could discriminate between contaminated and non-contaminated samples, then designed pyrosequencing assays to pre-screen DNA prior to being assayed on an array. Results Maternal contamination of cord blood was initially identified by unusual X chromosome DNA methylation patterns in 17 males. We utilized our DNAm panel to detect contaminated male samples and a proportional amount of female samples in the same cohort. We validated our DNAm screening method on an additional 189 sample cohort using both pyrosequencing and DNAm arrays, as well as 9 publically available cord blood 450K data sets. The rate of contamination varied from 0 to 10% within these studies, likely related to collection specific methods. Conclusions Maternal blood can contaminate cord blood during sample collection at appreciable levels across multiple studies. We have identified a panel of markers that can be used to identify this contamination, either post hoc after DNAm arrays have been completed, or in advance using a targeted technique like pyrosequencing.