The transition from a rural to an urban environment in Africa alters G protein-coupled receptor signaling

Differential expression of nuclear genes encoding mitochondrial proteins from urban and rural populations in Morocco

Urbanization in low-income countries represents an important inflection point in the epidemiology of disease, with rural populations experiencing high rates of chronic and recurrent infections and urban populations displaying a profile of noncommunicable diseases. To investigate if urbanization alters the expression of genes encoding mitochondrial proteins, we queried gene microarray data from rural and urban populations living in Morocco (GSE17065). The R Bioconductor packages edgeR and limma were used to identify genes with different expression. The experimental design was modeled upon location and sex. Nuclear genes encoding mitochondrial proteins were identified from the MitoCarta2.0 database. Of the 1158 genes listed in the MitoCarta2.0 database, 847 genes (73%) were available for analysis in the Moroccan dataset. The urban-rural comparison with the greatest environmental differences showed that 76.5% of the MitoCarta2.0 genes were differentially expressed, with 97% of the genes having an increased expression in the urban area. Enrichment analysis revealed 367 significantly enriched pathways (adjusted p value < 0.05), with oxidative phosphorylation, insulin secretion and glucose regulations (adj.p values = 6.93E-16) being the top three. Four significantly perturbed KEGG disease pathways were associated with urbanization-three degenerative neurological diseases (Huntington's, Alzheimer's, and Parkinson's diseases) and herpes simplex infection (false discover rate corrected p value (PGFdr) < 0.2). Mitochondrial RNA metabolic processing and translational elongation were the biological processes that had the greatest enrichment (enrichment ratios 14.0 and 14.8, respectively, FDR < 0.5). Our study links urbanization in Morocco with changes in the expression of the nuclear genes encoding mitochondrial proteins.

Socioeconomic Status and Temporal Urban Environmental Change in Accra: a Comparative Analysis of Area-based Socioeconomic and Urban Environmental Quality Conditions Between Two Time Points

The influence of area-based socioeconomic (SE) conditions on environmental quality conditions has recently been reported showing the precise spatial relationship between area-based SE conditions and neighborhood environmental quality in an urban area in a low-income setting. Nonetheless, there is still a lack of understanding of the nature of the relationship on a temporal scale. This study aimed to investigate the dynamic temporal relationship between area-based SE conditions and urban environmental quality conditions over a decadal period in Accra, Ghana. The results showed that there were differences in environmental quality across the SE quintiles in space (with regard to per capita waste generation (p < 0.012), waste collection/clearing (p < 0.01), and waste deposition (p < 0.001) and that the urban environmental quality conditions had changed dramatically over the decade for most of the environmental variables (p < 0.001). Despite the enormous urban development initiatives, some of the environmental quality indicators (e.g., proportion of households without flush toilet/Water Closet, connection to central sewer p < 0.001) appeared to have worsened in the high class quintile, suggesting that a high proportion of households were without acceptable sanitation facilities. The study concludes that urban development in low-income countries will need to follow strictly international best practice by observing standardized building codes and guidelines, if progress should be made in meeting the Millennium Development Goals targets.

Urbanization in Sub-Saharan Africa: Declining Rates of Chronic and Recurrent Infection and Their Possible Role in the Origins of Non-communicable Diseases

BACKGROUND

Non-communicable diseases (NCDs), such as atherosclerosis and cancers, are a leading cause of death worldwide. An important, yet poorly explained epidemiological feature of NCDs is their low incidence in under developed areas of low-income countries and rising rates in urban areas.

METHODS

With the goal of better understanding how urbanization increases the incidence of NCDs, we provide an overview of the urbanization process in sub-Saharan Africa, discuss gene expression differences between rural and urban populations, and review the current NCD determinant model. We conclude by identifying research priorities.

RESULTS

Declining rates of chronic and recurrent infection are the hallmark of urbanization in sub-Saharan Africa. Gene profiling studies show urbanization results in complex molecular changes, with almost one-third of the peripheral blood leukocyte transcriptome altered. The current NCD determinant model could be improved by including a possible effect from declining rates of infection and expanding the spectrum of diseases that increase with urbanization.

CONCLUSIONS

Urbanization in sub-Saharan Africa provides a unique opportunity to investigate the mechanism by which the environment influences disease epidemiology. Research priorities include: (1) studies to define the relationship between infection and risk factors for NCDs, (2) explaining the observed differences in the inflammatory response between rural and urban populations, and (3) identification of animal models that simulate the biological changes that occurs with urbanization. A better understanding of the biological changes that occur with urbanization could lead to new prevention and treatment strategies for some of the most common surgical diseases in high-income countries.

Out of Africa: Insights from a prospective pediatric surgery database

In this year's Robert E. Gross lecture, I describe how experiences early in my career at a government referral hospital in Banjul, The Gambia, influenced my research. Collecting prospective data on all children presenting to the hospital with surgical problems allowed me to gain an understanding of the epidemiology of childhood surgical conditions in sub-Saharan Africa and an appreciation for the inherent challenges of delivering surgical care in settings of limited resources. Based on findings from this database, my research over the past 20years has focused on developing strategies for improving surgical care in low-income countries and better understanding the geographical variations that occur in some of the most common surgical conditions in high-income countries (e.g., appendicitis). Although this research continues to be a work-in-progress, it has the potential to improve the surgical care of children in both high- and low-income countries. Much of this research would not have been possible had I not ventured off the usual path for an academic surgeon.