ANALYSIS OF β8 INTEGRIN IN NEUROGENESIS AND NEUROVASCULAR HOMEOSTASIS

Neurogenesis in the adult mouse brain occurs within the subventricular zone (SVZ) of the lateral ventricle. In the SVZ, neural stem cells (NSC) reside in a specialized microenvironment, or vascular niche, consisting of blood vessels and their basement membranes. Most NSCs in the SVZ differentiate into progenitor cells, which further differentiate to generate neuroblasts, which then migrate from the SVZ to the olfactory bulbs (OB) along the rostral migratory stream (RMS). ECM-mediated adhesion and signaling within the vascular niche likely contribute to proper NSC self-renewal, survival, differentiation and neuroblast motility. The mechanisms that control these events are poorly understood. Previous studies from our group and others have shown that loss of the ECM receptor, αvβ8 integrin, in NSCs in the embryonic mouse brain leads to severe developmental vascular defects and premature death. Here, the functions of αvβ8 integrin in the adult brain have been examined using mice that have been genetically manipulated to lack a functional β8 integrin gene. This study reveals that loss of β8 integrin leads to widespread defects in homeostasis of the neurovascular unit, including increased intracerebral blood vessels with enhanced perivascular astrogliosis. Additionally, β8 integrin dependent defects in NSC proliferation, survival, and differentiation, as well as neuroblast migration in the RMS were observed both in vivo and in vitro. The defects correlated, in part, with diminished integrin-mediated activation of TGFβ, an ECM ligand of β8 integrin. Collectively, these data identify important adhesion and signaling functions for β8 integrin in the regulation of neural stem and progenitor cells in the SVZ as well as in neuroblast migration along the RMS in the adult brain.

Commentary on "Expanded Learning Time in Schools"

As co-founder of KIPP, I know from experience and research that more time in school works. A well-designed extended-time program can help underserved students catch up academically, and prepare them for the rigors of higher education. Implementing extended time more widely poses challenges, but there are also creative solutions to these challenges.

Perceptions of Family Preservation Practitioners: A Preliminary Study

This exploratory, qualitative study examined practitioners' perceptions about family preservation practice. Findings reveal a wide range of identified strengths as well as the limitations of such a model. Interestingly, the most frequently identified strengths were value based rather than practice based in perspective whereas limitations were practice based. Keeping families together was the most common perceived strength but concern about children's safety by keeping the family intact was a frequently reported limitation. Further, lack of support and a lack of theoretical clarity were identified as considerable limitations. Implications suggest these practitioners (mostly child welfare/mental health workers) believe in the approach for the sake of keeping families together but are concerned with endangering the child in the process and recognize the need for theoretical guidance.