Biology subjects

Keiser, O.

Publications and source records attributed to Keiser, O..

3 recordsLinked to original sources

bioRxiv2019

Sociobehavioural characteristics and HIV incidence in 29 sub-Saharan African countries: Unsupervised machine learning analysis using the Demographic and Health Surveys

IntroductionHIV incidence varies widely between sub-Saharan African (SSA) countries. This variation coincides with a substantial sociobehavioural heterogeneity, which complicates the design of effective interventions. In this study, we investigated how sociobehavioural heterogeneity in sub-Saharan Africa could account for the variance of HIV incidence between countries. MethodsWe analysed aggregated data, at the national-level, from the most recent Demographic and Health Surveys of 29 SSA countries [2010-2017], which included 594644 persons (183310 men and 411334 women). We preselected 48 demographic, socio-economic, behavioural and HIV-related attributes to describe each country. We used Principal Component Analysis to visualize sociobehavioural similarity between countries, and to identify the variables that accounted for most sociobehavioural variance in SSA. We used hierarchical clustering to identify groups of countries with similar sociobehavioural profiles, and we compared the distribution of HIV incidence (estimates from UNAIDS) and sociobehavioural variables within each cluster. ResultsThe most important characteristics, which explained 69% of sociobehavioural variance across SSA among the variables we assessed were: religion; male circumcision; number of sexual partners; literacy; uptake of HIV testing; womens empowerment; accepting attitude toward people living with HIV/AIDS; rurality; ART coverage; and, knowledge about AIDS. Our model revealed three groups of countries, each with characteristic sociobehavioural profiles. HIV incidence was mostly similar within each cluster and different between clusters (median(IQR); 0.5/1000(0.6/1000), 1.8/1000(1.3/1000) and 5.0/1000(4.2/1000)).

epidemiology↗

bioRxiv2019

Socio-behavioural characteristics and HIV: findings from a causal modelling analysis of 29 sub-Saharan African countries

IntroductionSocio-behavioural factors may contribute to the wide variance in HIV prevalence between and within sub-Saharan African (SSA) countries. We studied the associations between socio-behavioural variables potentially related to the risk of acquiring HIV. MethodsWe used Bayesian network models to study associations between socio-behavioural variables that may be related to HIV. A Bayesian network consists of nodes representing variables, and edges representing the conditional dependencies between variables. We analysed data from Demographic and Health Surveys conducted in 29 SSA countries between 2010 and 2016. We predefined and dichotomized twelve variables, including factors related to age, literacy, HIV knowledge, HIV testing, domestic violence, sexual activity, and womens empowerment. We analysed data on men and women for each country separately and then summarised the results across the countries. We conducted a second analysis including also the individual HIV status in a subset of 23 countries where this information was available. We presented summary graphs showing associations that were present in at least six countries (five in the analysis with HIV status). ResultsWe analysed data from 190,273 men (range across countries 2,295-17,359) and 420,198 women (6,621-38,948). The two variables with the highest total number of edges in the summary graphs were literacy and rural/urban location. Literacy was negatively associated with false beliefs about AIDS and, for women, early sexual initiation, in most countries. Literacy was also positively associated with ever being tested for HIV and the belief that women have the right to ask their husband to use condoms if he has a sexually transmitted infection. Rural location was positively associated with false beliefs about HIV and the belief that beating ones wife is justified, and negatively associated with having been tested for HIV. In the analysis including HIV status, being HIV positive was associated with female-headed household, older age and rural location among women, and with no variables among men. ConclusionsLiteracy and urbanity were strongly associated with several factors that are important for HIV acquisition. Since literacy is one of the few variables that can be improved by interventions, this makes it a promising intervention target.

epidemiology↗

bioRxiv2018

Microfluidic device for on-chip mixing and encapsulation of lysates

Emulsion drops are often employed as picoliter-sized containers to perform screening assays. These assays usually entail the formation of drops encompassing discrete objects such as cells or microparticles and reagents to study interactions between the different encapsulants. Drops are also used to screen influences of reagent concentrations on the final product. However, these latter assays are less frequently performed because it is difficult to change the reagent concentration over a wide range with high precision within a single experiment. In this paper, we present a microfluidic double emulsion drop maker containing pneumatic valves that enable injection of different reagents using pulsed width modulation and subsequent mixing. This device can produce drops from reagent volumes as low as 10 l with minimal sample loss, thereby enabling experiments that would be prohibitively expensive using droplet generators that do not contain valves. We employ this device to monitor the kinetics of cell free synthesis of green fluorescent proteins inside double emulsions. To demonstrate the potential of this device, we perform DNA titration experiments in double emulsion drops to test the influence of the DNA concentration on the amount of green fluorescence proteins produced.

synthetic biology↗