The "ready-to-hand" test: Diagnostic availability and usability in primary health care settings in Sierra Leone.

This article assesses the availability of essential diagnostic tests in primary health care facilities in two districts in Sierra Leone. In addition to evaluating whether a test is physically present at a facility, it extends the concept of availability to include whether equipment is functional and whether infrastructure, systems, personnel and resources are in place to allow a particular test to be "ready to hand", that is, available for immediate use when needed. Between February 2019 and September 2019, a cross-sectional mixed-methods survey was conducted in all 40 Community Health Centres (CHCs) in Western Area, one of five principal divisions in Sierra Leone. The number of rapid diagnostic tests (RDTs) available ranged from 1-12, with 75% of facilities having 9 or less RDTs available out of a possible 17. While RDTs were overall more widely present than manual assays, there was wide variation between tests. The presence of RDTs at individual facilities was associated with having a permanent laboratory technician on staff. Despite CHCs being formally designated as providing laboratory services, no CHC fulfilled standard World Health Organisation (WHO) criteria for a laboratory. Only 9/40 (22.5%) CHCs had a designated laboratory space and a permanently employed laboratory technician. There was low availability of essential equipment and infrastructure. Supply chains were fragmented and unreliable, including a high dependency (>50%) on informal private sources for the majority of the available RDTs, consumables, and reagents. We conclude that the readiness of diagnostic services, including RDTs, depends on the presence and functionality of essential infrastructure, human resources, equipment and systems and that RDTs are not on their own a solution to infrastructural failings. Efforts to strengthen laboratory systems at the primary care level should take a holistic approach and focus on whether tests are "ready-to-hand" in addition to whether they are physically present.

Loss of endosomal exchanger NHE6 leads to pathological changes in tau in human neurons.

Disruption of endolysosomal and autophagy-lysosomal systems is increasingly implicated in neurodegeneration. Sodium-proton exchanger 6 (NHE6) contributes to the maintenance of proper endosomal pH, and loss-of function mutations in the X-linked NHE6 lead to Christianson syndrome (CS) in males. Neurodegenerative features of CS are increasingly recognized, with postmortem and clinical data implicating a role for tau. We generated cortical neurons from NHE6 knockout (KO) and isogenic wild-type control human induced pluripotent stem cells. We report elevated phosphorylated and sarkosyl-insoluble tau in NHE6 KO neurons. We demonstrate that NHE6 KO leads to lysosomal and autophagy dysfunction involving reduced lysosomal number and protease activity, diminished autophagic flux, and p62 accumulation. Finally, we show that treatment with trehalose or rapamycin, two enhancers of autophagy-lysosomal function, each partially rescue this tau phenotype. We provide insight into the neurodegenerative processes underlying NHE6 loss of function and into the broader role of the endosome-lysosome-autophagy network in neurodegeneration.

Stem cell-derived neurons reflect features of protein networks, neuropathology, and cognitive outcome of their aged human donors.

We have generated a controlled and manipulable resource that captures genetic risk for Alzheimer's disease: iPSC lines from 53 individuals coupled with RNA and proteomic profiling of both iPSC-derived neurons and brain tissue of the same individuals. Data collected for each person include genome sequencing, longitudinal cognitive scores, and quantitative neuropathology. The utility of this resource is exemplified here by analyses of neurons derived from these lines, revealing significant associations between specific Aß and tau species and the levels of plaque and tangle deposition in the brain and, more importantly, with the trajectory of cognitive decline. Proteins and networks are identified that are associated with AD phenotypes in iPSC neurons, and relevant associations are validated in brain. The data presented establish this iPSC collection as a resource for investigating person-specific processes in the brain that can aid in identifying and validating molecular pathways underlying AD.

Homologous elements hs3a and hs3b in the 3' regulatory region of the murine immunoglobulin heavy chain (Igh) locus are both dispensable for class-switch recombination.

Immunoglobulin heavy chain (IgH) genes are formed, tested, and modified to yield diverse, specific, and high affinity antibody responses to antigen. The processes involved must be regulated, however, to avoid unintended damage to chromosomes. The 3' regulatory region of the Igh locus plays a major role in regulating class-switch recombination (CSR), the process by which antibody effector functions are modified during an immune response. Loss of all known enhancer-like elements in this region dramatically impairs CSR, but individual element deletions have no effect on this process. In the present study, we explored the hypothesis that an underlying functional redundancy in the homologous elements hs3a and hs3b was masking the importance of either element to CSR. Several transgenic mouse lines were generated, each carrying a bacterial artificial chromosome transgene that mimicked Igh locus structure but in which hs3a was missing and hs3b was flanked by loxP sites. Matings to Cyclization Recombination Enzyme-expressing mice established "pairs" of lines that differed only in the presence or absence of hs3b. Remarkably, CSR remained robust in the absence of both hs3a and hs3b, suggesting that the remaining two elements of the 3' regulatory region, hs1.2 and hs4, although individually dispensable for CSR, are, together, sufficient to support CSR.