The ecological schoolyard project at St. Paul Lutheran School, Ann Arbor, Michigan, USA /

Master of ScienceLandscape ArchitectureUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/115745/1/39015069212028.pd

TRANSPORT OF BIOSYNTHETIC SPHINGOLIPIDS FROM GOLGI TO PLASMA-MEMBRANE IN HT29 CELLS - INVOLVEMENT OF DIFFERENT CARRIER VESICLE POPULATIONS

Intracellular transport of the sphingolipids glucosylceramide (GlcCer) and sphingomyelin (SM), was examined in HT29 human colon adenocarcinoma cells. After synthesis from a fluorescent precursor, 6-[N-(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]hexanoylceramide (C-6-NBD-Cer), transfer of SM from the Golgi complex to the plasma membrane can occur independently of that of GlcCer, as revealed by temperature-dependent experiments. Thus, at 20 degrees C, SM trafficking to the cell surface is essentially unaffected, whereas GlcCer transport to the plasma membrane is ininhibited by approximately 75 %, when compared to the transfer of both lipids at 37 degrees C. The mechanism by which SM and GlcCer are transported to the cell surface involves at least in part a vesicular mechanism. Transport vesicles, containing both lipids at their luminal surface, as revealed by the inaccessibility of the NBD fluorescence to the quencher sodium dithionite, have been isolated from cells, permeabilized by filter stripping. As evidenced by electron microscopic and biochemical criteria, no vesicles or lipids were released when cell permeabilization had been carried out with streptolysin. Density gradient analysis indicates the potential existence of several vesicle populations, distinctly enriched in either lipid, involved in transport of sphingolipids to the plasma membrane in HT29 cells

Reconsidering the Alternatives: The Relationship between Suspension, Disciplinary Alternative School Placement, Subsequent Juvenile Detention, and the Salience of Race

Alternative school settings for students who are identified as “disruptive or dangerous” are playing an increasingly prominent role in the world of public education, yet significant gaps in our understanding of their efficacy remain. Despite mounting use of disciplinary alternative schools, the vast majority of urban districts report that the demands for enrollment space outweigh the supply. While in theory these schools exist to provide alternative learning environments for students deemed too disruptive for mainstream schools, the evidence suggests that promoting this approach with little to no regulation is having grave unintended consequences for many students. The increasing demands for disciplinary alternative schools is indicative of the wider pervasive problems of detrimental school discipline policies, the criminalization of misbehavior and the exclusion and segregation of students based on race, poverty and disability in the educational system. This longitudinal investigation within a large school district serving 100,000 students examines multiple factors to determine how the risk of placement in the disciplinary alternative schools is systematically related to predictors and the risk of juvenile subsequent juvenile detention between 3rd and 12th grade. Results revealed that cumulatively, nearly 1 in 10 children entering 3rd grade experienced placement in a disciplinary alternative school by 12th grade. The racial gaps were pronounced as 13% of all African- American students in the cohort experienced placement compared to 4% of the White students. The risk of placement was greatest in 7th grade. Race, school mobility, grade retention, special education status, attendance, and out of school suspension were systematically related to the risk of placement in alternative school. African-American students were disproportionately represented among those suspended, placed in alternative school, and detained as juveniles. Half of the students placed in elementary experienced subsequent juvenile detention within less than four years, 43% of students placed in middle school were detained as juveniles within less than two years. These findings, based on a robust data set, highlight strong relationships between out of school suspensions, disciplinary alternative school placement, and subsequent juvenile detention that are most salient for African-American children, particularly those receiving free/reduced lunch. These relationships raise considerable doubts about the efficacy of a system that relies on out of school suspensions and disciplinary alternative schools as strategies reduce delinquency and provide support for children deemed disruptive or dangerous. The results strongly suggest that early warning systems connected to supportive early intervention strategies would produce better and more equitable outcomes in the short and long term than exclusionary discipline practices and policies