Early-life decline in neurogenesis markers and age-related changes of TrkB splice variant expression in the human subependymal zone.

Neurogenesis in the subependymal zone (SEZ) declines across the human lifespan, and reduced local neurotrophic support is speculated to be a contributing factor. While tyrosine receptor kinase B (TrkB) signalling is critical for neuronal differentiation, maturation and survival, little is known about subependymal TrkB expression changes during postnatal human life. In this study, we used quantitative PCR and in situ hybridisation to determine expression of the cell proliferation marker Ki67, the immature neuron marker doublecortin (DCX) and both full-length (TrkB-TK+) and truncated TrkB receptors (TrkB-TK-) in the human SEZ from infancy to middle age (n = 26-35, 41 days to 43 years). We further measured TrkB-TK+ and TrkB-TK- mRNAs in the SEZ from young adulthood into ageing (n = 50, 21-103 years), and related their transcript levels to neurogenic and glial cell markers. Ki67, DCX and both TrkB splice variant mRNAs significantly decreased in the SEZ from infancy to middle age. In contrast, TrkB-TK- mRNA increased in the SEZ from young adulthood into ageing, whereas TrkB-TK+ mRNA remained stable. TrkB-TK- mRNA positively correlated with expression of neural precursor (glial fibrillary acidic protein delta and achaete-scute homolog 1) and glial cell markers (vimentin and pan glial fibrillary acidic protein). TrkB-TK+ mRNA positively correlated with expression of neuronal cell markers (DCX and tubulin beta 3 class III). Our results indicate that cells residing in the human SEZ maintain their responsiveness to neurotrophins; however, this capability may change across postnatal life. We suggest that TrkB splice variants may differentially influence neuronal and glial differentiation in the human SEZ.

Dysregulation of lipids in Alzheimer's disease and their role as potential biomarkers.

The brain is highly enriched in lipids, and an intensive study of these lipids may be informative, not only of normal brain function but also of changes with age and in disease. In recent years, the development of highly sensitive mass spectrometry platforms and other high-throughput technologies has enabled the discovery of complex changes in the entire lipidome. This lipidomics approach promises to be a particularly useful tool for identifying diagnostic biomarkers for early detection of age-related neurodegenerative disease, such as Alzheimer's disease (AD), which has till recently been limited to protein- and gene-centric approaches. This review highlights known lipid changes affecting the AD brain and presents an update on the progress of lipid biomarker research in AD. Important considerations for designing large-scale lipidomics experiments are discussed to help standardize findings across different laboratories, as well as challenges associated with moving toward clinical application.

Impact of patient and visitor hand hygiene interventions at a pediatric hospital: A stepped wedge cluster randomized controlled trial.

BACKGROUND: Patient and visitor hand hygiene has the potential to prevent health care-associated infections, but there are few data on the efficacy of interventions to improve patient/visitor hand hygiene. OBJECTIVE: To determine whether conventional and front-line ownership (FLO) patient/visitor hand hygiene interventions improve patient/visitor and health care worker (HCW) hand hygiene rates. METHODS: A stepped wedge cluster randomized controlled trial was conducted on inpatient units and the emergency department. A conventional intervention included pediatric-focused posters, which also served as reminders for HCWs. This was compared to a FLO intervention aimed at finding "positive deviants," staff who were already taking steps to improve patient/visitor hand hygiene. Patient/visitor and HCW hand hygiene rates were measured covertly by trained medical students. RESULTS: Patient/visitor hand hygiene rates increased from 9.2% at baseline to 13.9% in the post-intervention period. Hand hygiene rates on units randomized to the standard intervention changed from 7.3% to 10.9% (P = .46), but FLO intervention units significantly changed from 14.3% to 25% (P = .03). The baseline HCW hand hygiene rate was 68.2%, which increased to a greater extent in the FLO group (79.1%) than in the standard intervention (73.1%), but the change was not statistically significant for either intervention compared to control (P = .18 and P = .64, respectively). CONCLUSIONS: Hand hygiene interventions in hospitals can improve patient/visitor and HCW hand hygiene rates, and a FLO intervention appears to be more effective than a conventional intervention.

Reduction in IGF1 mRNA in the Human Subependymal Zone During Aging.

The cell proliferation marker, Ki67 and the immature neuron marker, doublecortin are both expressed in the major human neurogenic niche, the subependymal zone (SEZ), but expression progressively decreases across the adult lifespan (PMID: 27932973). In contrast, transcript levels of several mitogens (transforming growth factor α, epidermal growth factor and fibroblast growth factor 2) do not decline with age in the human SEZ, suggesting that other growth factors may contribute to the reduced neurogenic potential. While insulin like growth factor 1 (IGF1) regulates neurogenesis throughout aging in the mouse brain, the extent to which IGF1 and IGF family members change with age and relate to adult neurogenesis markers in the human SEZ has not yet been determined. We used quantitative polymerase chain reaction to examine gene expression of seven IGF family members [IGF1, IGF1 receptor, insulin receptor and high-affinity IGF binding proteins (IGFBPs) 2, 3, 4 and 5] in the human SEZ across the adult lifespan (n=50, 21-103 years). We found that only IGF1 expression significantly decreased with increasing age. IGFBP2 and IGFBP4 expression positively correlated with Ki67 mRNA. IGF1 expression positively correlated with doublecortin mRNA, whereas IGFBP2 expression negatively correlated with doublecortin mRNA. Our results suggest IGF family members are local regulators of neurogenesis and indicate that the age-related reduction in IGF1 mRNA may limit new neuron production by restricting neuronal differentiation in the human SEZ.

The application of lipidomics to biomarker research and pathomechanisms in Alzheimer's disease.

PURPOSE OF REVIEW: Alzheimer's disease is the most common cause of dementia. There are still no disease modifying treatments that can cure or slow disease progression. Recently, Alzheimer's disease researchers have attempted to improve early detection and diagnostic criteria for Alzheimer's disease, with the rationale that treatment of disease, or even prevention, may be more successful during the early preclinical stages of Alzheimer's disease when neurodegenerative damage is not as widespread. As the brain has a high lipid content, lipidomics may offer novel insights into the underlying pathogenesis of Alzheimer's disease. This review reports on recent developments in the relatively unexplored field of lipidomics in Alzheimer's disease, including novel biomarkers and pathomechanisms of Alzheimer's disease. RECENT FINDINGS: Numerous biomarker panels involving phospholipids and sphingolipids have been proposed, indicating perturbed lipid metabolism in early stages of Alzheimer's disease. Future strategies targeting these metabolic changes through dietary supplementation could have therapeutic benefits in at-risk individuals. SUMMARY: Dysregulated lipid metabolism could reflect pathological changes in synaptic function and neuronal membranes, leading to cognitive decline. However, extensive validation in large independent cohorts is required before lipid biomarkers can be used clinically to assess Alzheimer's disease risk and progression.

Decline in Proliferation and Immature Neuron Markers in the Human Subependymal Zone during Aging: Relationship to EGF- and FGF-Related Transcripts.

Neuroblasts exist within the human subependymal zone (SEZ); however, it is debated to what extent neurogenesis changes during normal aging. It is also unknown how precursor proliferation may correlate with the generation of neuronal and glial cells or how expression of growth factors and receptors may change throughout the adult lifespan. We found evidence of dividing cells in the human SEZ (n D 50) in conjunction with a dramatic age-related decline (21-103 years) of mRNAs indicative of proliferating cells (Ki67) and immature neurons (doublecortin). Microglia mRNA (ionized calcium-binding adapter molecule 1) increased during aging, whereas transcript levels of stem/precursor cells (glial fibrillary acidic protein delta and achaete-scute homolog 1), astrocytes (vimentin and pan-glial fibrillary acidic protein), and oligodendrocytes (oligodendrocyte lineage transcription factor 2) remained stable. Epidermal growth factor receptor (EGFR) and fibroblast growth factor 2 (FGF2) mRNAs increased throughout adulthood, while transforming growth factor alpha (TGFα), EGF, Erb-B2 receptor tyrosine kinase 4 (ErbB4) and FGF receptor 1 (FGFR1) mRNAs were unchanged across adulthood. Cell proliferation mRNA positively correlated with FGFR1 transcripts. Immature neuron and oligodendrocyte marker expression positively correlated with TGFα and ErbB4 mRNAs, whilst astrocyte transcripts positively correlated with EGF, FGF2, and FGFR1 mRNAs. Microglia mRNA positively correlated with EGF and FGF2 expression. Our findings indicate that neurogenesis in the human SEZ continues well into adulthood, although proliferation and neuronal differentiation may decline across adulthood. We suggest that mRNA expression of EGF- and FGF-related family members do not become limited during aging and may modulate neuronal and glial fate determination in the SEZ throughout human life.