Yi, S. — Page 4 | Search bioRxiv

bioRxiv2019

Accelerated evolution of oligodendrocytes in human brain

Recent discussions of human brain evolution have largely focused on increased neuron numbers and changes in their connectivity and expression. However, it is increasingly appreciated that oligodendrocytes play important roles in cognitive function and disease. Whether both cell-types follow similar or distinctive evolutionary trajectories is not known. We examined the transcriptomes of neurons and oligodendrocytes in the frontal cortex of humans, chimpanzees, and rhesus macaques. We identified human-specific trajectories of gene expression in neurons and oligodendrocytes and show that both cell-types exhibit human-specific upregulation. Moreover, oligodendrocytes have undergone accelerated gene expression evolution in the human lineage compared to neurons. The signature of acceleration is enriched for cell type-specific expression alterations in schizophrenia. These results underscore the importance of oligodendrocytes in human brain evolution.

evolutionary biology↗

bioRxiv2019

Acceptability of active case finding with a seed-and-recruit model to improve tuberculosis case detection and linkage to treatment in Cambodia: a qualitative study

BackgroundWith support of the national tuberculosis (TB) program, KHANA has implemented an innovative approach using a seed-and-recruit model to actively find TB cases in the community. The intervention engaged community members including TB survivors to recruit people with TB symptoms in a snowball approach for screening and linkage to treatment. This study aims to explore the acceptability of active case finding with the seed-and-recruit model in detecting new TB cases and determine the characteristics of successful seeds.\n\nMethodsThis qualitative study was conducted in four provinces (Banteay Meanchey, Kampong Chhnang, Siem Reap, and Takeo) in Cambodia in 2017. Fifty six in-depth interviews and ten focus group discussions were conducted to gain insights into the acceptability, strengths, and challenges in implementing the model. Transcripts were coded and content analyses were performed.\n\nResultsThe seed-and-recruit active case finding model was generally well-received by the study participants. They saw the benefits of engaging TB survivors and utilize their social network to find new TB cases in the community. The social embeddedness of the model within the local community was one of the major strengths. The success of the model also hinges on the integration with existing health facilities. Having extensive social network, being motivated, and having good knowledge about TB were important characteristics of successful seeds. Study participants reported challenges in motivating the recruits for screening, logistic capacities, and high workload during implementation. However, there was a general consensus that the model ought to be expanded.\n\nConclusionsThese findings indicate that the seed-and-recruit model should be fine-tuned and scaled up as part of the national TB Program to increase TB new case detection in Cambodia. Further studies are needed to more comprehensively evaluate the impacts and cost-effectiveness of the model in Cambodia as well as in other resource-limited settings.

epidemiology↗