Pregnancy cohorts and biobanking in sub-Saharan Africa: a systematic review

Evaporation of serum after long-term biobank storage: A chemical analysis of maternal serum from a large Danish pregnancy screening registry

BACKGROUND

Relying on freezer stored biospecimens is preferred in epidemiolocal studies exploring environmental pregnancy exposures and later offspring health. Storage duration may increase the pre-analytical variability, potentially adding measurement uncertainty. We investigated evaporation of maternal serum after long-term biobank storage using ions (sodium, Na+; chloride, Cl-) recognized for stability and relatively narrow normal biological reference ranges in human serum.

METHODS

A chemical analysis study of 275 biobanked second trimester maternal serum from a large Danish pregnancy screening registry. Serum samples were collected between 1985-1995 and stored at -20°C. Ion concentrations were quantified with indirect potentiometry using a Roche Cobas 6000 analyzer and compared according to storage time and normal biological ranges in second trimester. Ion concentrations were also compared with normal biological variation assessed by baseline Na+ and Cl- serum concentrations from a separate cohort of 24,199 non-pregnant women measured before freezing with the same instrument.

RESULTS

The overall mean ion concentrations in biobanked serum were 147.5 mmol/L for Na+ and 109.7 for Cl-. No marked linear storage effects were observed according to storage time. Ion concentrations were consistently high across sampling years, especially for specific sampling years, and a relatively large proportion were outside respective normal ranges in second trimester: 38.9% for Na+ and 43.6% for Cl-. Some variation in concentrations was also evident in baseline serum used as quality controls.

CONCLUSIONS

Elevated ion concentrations suggest evaporation, but independent of storage duration in the present study (27-37 years). Any evaporation may have occurred prior to freezer storage or during the first 27 years. Other pre-analytical factors such as low serum volume have likely influenced the concentrations, particularly given the high within year variability. Overall, we consider the biobanked serum samples internally comparable to enable their use in epidemiological studies.

Building a national framework for multicentre research and clinical trials: experience from the Nigeria Implementation Science Alliance

There is limited capacity and infrastructure in sub-Saharan Africa to conduct clinical trials for the identification of efficient and effective new prevention, diagnostic and treatment modalities to address the disproportionate burden of disease. This paper reports on the process to establish locally driven infrastructure for multicentre research and trials in Nigeria known as the Nigeria Implementation Science Alliance Model Innovation and Research Centres (NISA-MIRCs). We used a participatory approach to establish a research network of 21 high-volume health facilities selected from all 6 geopolitical zones in Nigeria capable of conducting clinical trials, implementation research using effectiveness-implementation hybrid designs and health system research. The NISA-MIRCs have a cumulative potential to recruit 60 000 women living with HIV and an age-matched cohort of HIV-uninfected women. We conducted a needs assessment, convened several stakeholder outreaches and engagement sessions, and established a governance structure. Additionally, we selected and trained a core research team, developed criteria for site selection, assessed site readiness for research and obtained ethical approval from a single national institutional review board. We used the Exploration, Preparation, Implementation, Sustainment framework to guide our reporting of the process in the development of this network. The NISA-MIRCs will provide a nationally representative infrastructure to initiate new studies, support collaborative research, inform policy decisions and thereby fill a significant research infrastructure gap in Africa’s most populous country.