Oxygen delivery systems for adults in Sub-Saharan Africa: A scoping review

Background

Respiratory diseases are the leading cause of death and disability worldwide. Oxygen is an essential medicine used to treat hypoxemia from respiratory diseases. However, the availability and utilization of oxygen delivery systems for adults in sub-Saharan Africa is not well-described. We aim to identify and describe existing data around oxygen availability and provision for adults in sub-Saharan Africa, determine knowledge or research gaps, and make recommendations for future research and capacity building.

Methods

We systematically searched four databases for articles on April 22, 2020, for variations of keywords related to oxygen with a focus on countries in sub-Saharan Africa. Inclusion criteria were studies that included adults and addressed hypoxemia assessment or outcome, oxygen delivery mechanisms, oxygen availability, oxygen provision infrastructure, and oxygen therapy and outcomes.

Results

35 studies representing 22 countries met inclusion criteria. Availability of oxygen delivery systems ranged from 42%-94% between facilities, with wide variability in the consistency of availability. There was also wide reported prevalence of hypoxemia, with most studies focusing on specific populations. In facilities where oxygen is available, health care workers are ill-equipped to identify adult patients with hypoxemia, provide oxygen to those who need it, and titrate or discontinue oxygen appropriately. Oxygen concentrators were shown to be the most cost-effective delivery system in areas where power is readily available.

Conclusions

There is a substantial need for building capacity for oxygen delivery throughout sub-Saharan Africa. Addressing this critical issue will require innovation and a multi-faceted approach of developing infrastructure, better equipping facilities, and health care worker training.

Functional identification of integrin laminin receptors that mediate process outgrowth by human SY5Y neuroblastoma cells

Treatment of the human neuroblastoma cell line SY5Y with nerve growth factor (NGF) induces terminal neuronal differentiation of a subpopulation of cells which can be selected by treatment with a DNA synthesis inhibitor. We have examined the interactions of naive (untreated) and NGF-differentiated SY5Y cells with laminin, and identified integrin receptors that mediate laminin-induced process outgrowth. Differentiated cells displayed a greater capacity for process extension, which correlated with increased expression of integrin laminin receptors. Both naive and differentiated cells expressed integrins alpha 1/beta 1, alpha 2/beta 1, and alpha 3/beta 1 but the differentiated population expressed about 5-fold higher levels of alpha 1/beta 1 and about 2-fold more alpha 2/beta 1 and alpha 3/beta 1 on their surface. Function blocking monoclonal antibodies were used to identify integrin receptors mediating process outgrowth. The anti-alpha 1 monoclonal antibody SR84 was shown to block alpha 1 function and inhibit process outgrowth on laminin. Despite the presence of multiple integrins which have been shown to bind laminin in other cell types, alpha 1/beta 1 mediated the majority of process outgrowth in both naive and differentiated cells, with a minor role played by alpha 3/beta 1. These data indicate that alpha 1/beta 1 function is required for process outgrowth on laminin by SY5Y cells and suggest that increased expression may be a crucial aspect of neuronal differentiation.