Measuring Erodibility of Cohesive Soils Using Laboratory Submerged Jet Test

Abstract

Shigella flexneri causes a severe form of bacillary dysentery characterized by cramping, diarrhea, and fever. S. flexneri uses a type three seceretion system (TTSS) to invade the colonic epithelium by injecting effector proteins directly into the host cell cytoplasm. The TTSS consists of a basal body, spanning both the outer and inner membranes, and a surface exposed needle. After the proper environmental stimuli, the 62kDa Invasion Plasmid Antigen B (IpaB) is stably maintained at the needle tip. IpaB, along with IpaC, is important in forming a pore in the host membrane to allow the injection of later effector proteins into the host cell cytoplasm. The pore may be formed selectively in lipid rafts, and IpaB is hypothesized to be a cholesterol binding protein. To address this question, we used a variety of biophysical techniques to evaluate the ability of IpaB to bind to Dehydroergosterol (DHE), a naturally occurring fluorescent derivative of cholesterol. DHE fluorescence is observed when it has entered an apolar environment, and it is quenched in aqueous solution. Here we shed some light on this important step in TTS induction. Subject Area: Biological Sciences Vitamin D is a principal factor required for the development and maintenance of bone and for the maintenance of calcium homeostasis. When blood calcium levels decrease, calcium is obtained through bone resorption and kidney reabsorption. However the ultimate source of calcium is through intestinal calcium absorption of dietary calcium, where calcium is transported across the intestinal wall into the bloodstream via the actions of vitamin D. The process by which vitamin D mediates intestinal calcium transport involves both an active transcellular pathway and a passive paracellular pathway, but the exact mechanism is unknown. The purpose of this study was to determine the capacity of 1,25(OH)2D3 to stimulate the expression of calbindin-D9K protein in the different regions of mouse intestine. Intestinal sections analyzed were duodenum, jejunum, ileum and colon. This study, confirming the capacity of 1,25(OH)2D3 to induce calbindin-D9K protein expression in other distal regions of the intestine supports a possible role for 1,25(OH)2D3 action in the distal intestine, and shows that additional studies are warranted to explore the mechanism of calcium absorption in these regions and the significance of vitamin D in the process. Subject Area: Biomedical Sciences Many health care professionals incorporate the use of topical counterirritants for pain relief. Some are under the impression that they desensitize the skin and increase tissue …

Cite this paper

@inproceedings{Adam2011MeasuringEO, title={Measuring Erodibility of Cohesive Soils Using Laboratory Submerged Jet Test}, author={P. Adam and Nicholas E Dickenson and Wendy L. Picking and Micheal Barta and Brian V. Geisbrecht and William D. Picking and Juliana Agudelo and Angela Porta and Kazuma Akehi and Blaine C Long}, year={2011} }