Inherent Interfacial Mechanical Gradients in 3D Hydrogels Influence Tumor Cell Behaviors

Cells sense and respond to the rigidity of their microenvironment by altering their morphology and migration behavior. To examine this response, hydrogels with a range of moduli or mechanical gradients have been developed. Here, we show that edge effects inherent in hydrogels supported on rigid substrates also influence cell behavior. A Matrigel hydrogel was supported on a rigid glass substrate, an interface which computational techniques revealed to yield relative stiffening close to the rigid substrate support. To explore the influence of these gradients in 3D, hydrogels of varying Matrigel content were synthesized and the morphology, spreading, actin organization, and migration of glioblastoma multiforme (GBM) tumor cells were examined at the lowest (<50 µm) and highest (>500 µm) gel positions. GBMs adopted bipolar morphologies, displayed actin stress fiber formation, and evidenced fast, mesenchymal migration close to the substrate, whereas away from the interface, they adopted more rounded or ellipsoid morphologies, displayed poor actin architecture, and evidenced slow migration with some amoeboid characteristics. Mechanical gradients produced via edge effects could be observed with other hydrogels and substrates and permit observation of responses to multiple mechanical environments in a single hydrogel. Thus, hydrogel-support edge effects could be used to explore mechanosensitivity in a single 3D hydrogel system and should be considered in 3D hydrogel cell culture systems

Effect of duct orientation on particle deposition in the human respiratory tract

A two-dimensional model of transport and deposition of particles in the human acinus is formulated. The model simulates airway generations 20-23 of the respiratory tract by solving numerically the system of Navier-Stokes equations for continuity and momentum. The finite volume method under the platform of the FLUENT code was employed to perform the numerical calculations and the fully implicit discretization approach was used for discretizing the transient equations on the grounds of its superior stability. The simulations of macron size particles (1-5 &#956;m) show that the existence of alveolar re-circulation and gravity orientation are key factors in determining the deposition in the last four generations of the human respiratory tract.Keywords: duct orientation, particle deposition, respiratory tract, discretization approachAfrican Journal of Educational Studies in Mathematics and Sciences Vol. 9, 201

Exposure to a Slightly Sweet Lipid-Based Nutrient Supplement During Early Life Does Not Increase the Preference for or Consumption of Sweet Foods and Beverages by 4–6-y-Old Ghanaian Preschool Children: Follow-up of a Randomized Controlled Trial

BackgroundWhether consuming sweet foods early in life affects sweet food preferences and consumption later in childhood is unknown.ObjectiveWe tested the hypothesis that exposure to a slightly sweet lipid-based nutrient supplement (LNS) early in life would not increase preference for or consumption of sweet items at preschool age.MethodsWe followed up children who had participated in a randomized trial in Ghana in which LNS was provided to 1 group of women during pregnancy and 6 mo postpartum and to their infants from ages 6-18 mo (LNS group). The control group (non-LNS group) received iron and folic acid during pregnancy or multiple micronutrients during pregnancy and 6 mo postpartum, with no infant supplementation. At 4-6 y, we obtained data from caregivers on children's food and beverage preferences and consumption (n&nbsp;=&nbsp;985). For a randomly selected subsample (n&nbsp;=&nbsp;624), we assessed preference for sweet items using a photo game (range in potential scores, 0-15). For the photo game and reported consumption of sweet items, we examined group differences using predetermined noninferiority margins equivalent to an effect size of 0.2.ResultsMedian (quartile 1, quartile 3) reported consumption of sweet items (times in previous week) was 14 (8, 23) in the LNS group and 16 (9, 22) in the non-LNS group; in the photo game, the number of sweet items selected was 15 (11, 15) and 15 (11, 15), respectively. The upper level of the 95% CI of the mean difference between LNS and non-LNS groups did not exceed the noninferiority margins for these outcomes. Caregiver-reported preferences for sweet items also did not differ between groups (P&nbsp;=&nbsp;0.9).ConclusionIn this setting, where child consumption of sweet foods was common, exposure to a slightly sweet LNS early in life did not increase preference for or consumption of sweet foods and beverages at preschool age. This trial was registered at clinicaltrials.gov as NCT00970866