Villous explant culture: Characterization and evaluation of a model to study trophoblast invasion

The mechanisms that control invasion of cytotrophoblast (CTB) cells into the maternal decidua and myometrium with transformation of the maternal spiral arteries are not fully understood, but oxygen is thought to be a key factor. We carried out a semiquantitative evaluation of an explant culture model for use in the study of trophoblast proliferation and invasion. Explants of human villous tissue (6–9 weeks of gestation) cultured on Matrigel in both standard culture conditions (18% O2) and in a low oxygen environment (2% O2) produced regions of outgrowth, of cytotrophoblast cells from villous tips and migration of cells into the Matrigel. The number of sites of outgrowth and migration, area of outgrowth, and extent of migration of cells into the Matrigel tended to increase throughout the culture period (144 h) but varied between explants from the same placenta and those from different placentas. There were no significant differences in the number of sites of outgrowth or migration scores in explants cultured in a low oxygen environment compared to those cultured in standard conditions. This study highlights the importance of careful validation, design and interpretation of experiments using in vitro culture systems, particularly those investigating the regulatory role of oxygen

Tree shade coverage optimization in an urban residential environment

Shade provided by trees, shrubs and other vegetation serves as a natural umbrella to mitigate insolation absorbed by features of the urban environment, especially building structures. For a desert community, tree shade is a valuable asset, contributing to energy conservation efforts, improving home values, enabling cost savings, and promoting enhanced health and well-being. Therefore, maximizing tree shade coverage is an important component in creating an eco-friendly and sustainable urban environment. Strategic placement of trees enhances tree shade coverage of buildings. This paper details an optimization method to simultaneously maximize tree shade coverage on building facades and open structures and to minimize shade coverage on building rooftops in a 3-dimensional environment. This method integrates geographic information systems and spatial optimization approaches for placing trees that provide the greatest potential benefit to a building. A residential area in Tempe, Arizona is utilized to demonstrate the capabilities of the method. The optimization results show that two trees can provide up to 22.20 m2 shade coverage at 12:00 across a 54 m2 south-facing facade. This research offers a method to help homeowners, urban planners, and policy makers to quantitatively evaluate shade coverage from trees for building structures in a residential environment