ABSTRACT
Dynamic surface tension measurements were used to track adsorption kinetics for dilauroylphosphatidylcholine (DLPC) or dimyristoylphosphatidylcholine (DMPC) from monodisperse vesicle dispersions to an air-water interface at elevated temperatures ≥30 °C. Effects of vesicle concentration, aqueous solubility of the lipids, and temperature T on the adsorption kinetics were determined, and the controlling transport pathway was identified. Adsorption dynamics were tracked for 0.1-10 mM DLPC at 30 and 38 °C and for 1-10 mM DMPC at 30, 50, and 58 °C. Experimental results were compared to theoretical predictions for a reaction-enhanced, molecular transport mechanism, which was previously shown to effectively predict DLPC adsorption kinetics at 22 °C. At higher temperatures, for DLPC concentrations ≥0.25 mM or DMPC concentrations ≥1 mM, a weak dependence of adsorption time on concentration was observed, again consistent with the reaction-enhanced molecular pathway. Molecular release rates from vesicles increased with increasing temperature or decreasing acyl chain length. At equivalent ratios T/Tm of the dispersion temperature to the lipid chain phase transition temperature Tm, measured adsorption times for DLPC were approximately 10-fold shorter than those for DMPC, suggesting that the fluidity of the acyl tails is not the only lipid property determining adsorption rates. Despite the significant difference in aqueous solubility and chain phase transition temperature between DLPC and DMPC, the results provide further evidence for an adsorption mechanism that is well described by diffusion of molecular lipid, with rates of molecular diffusion near the interface enhanced by release from nearby vesicles.
ABSTRACT
BACKGROUND: Fostering partnerships was critical to the success of the Colon Health Program (CHP) in Greater Seattle. The CHP was built on the Breast and Cervical Health Program (BCHP) framework. A replicable system to provide quality colorectal screening services for individuals with limited incomes and no health insurance was developed. METHODS: Partners were recruited and engaged during 3 programmatic phases: 1) development and start-up, 2) implementation, and 3) sustainability planning. Several tactics were used to develop trust and build bridges among the partners and to create an effective work group. RESULTS: The partners were critical to developing clinic policies, procedures, and systems to increase colorectal screening and improve follow-up; expanding access to colonoscopies; and initiating statewide dissemination of training and systems as well as policy change. The fecal occult blood test completion rate was 61%, and the colonoscopy completion rate was 78%. The colonoscopy navigation system was effective with a low "no show" rate (8%). The partners were instrumental in helping Washington State obtain funding from the Centers for Disease Control and Prevention to continue the CHP statewide. CONCLUSIONS: During implementation, key elements for success included: building the project on the successful BCHP framework, meticulous training of clinic staff about colorectal cancer and screening methods, frequent consultation to identify and solve problems, active support of the clinic administration, and the presence of a CHP champion in the clinic. Institutionalization of the CHP depended on: assessing progress after the first year, documenting experience with the program, disseminating lessons learned, engaging new partners, and determining steps to expand the program.
