In vitro adsorption of tear proteins to hydroxyethyl methacrylate-based contact lens materials

OBJECTIVES: Investigations of polymer interactions in single protein solutions is a necessary step in the elucidation of in vivo early binding events during protein deposition on hydroxyethyl methacrylate-based contact lens materials. Quantity and tenacity of binding of significant tear components to groups I and IV contact lenses was assessed. Competitive binding by these components was also examined. METHODS: Adsorption on FDA groups I and IV hydrogel lenses was monitored using I-labeled protein. Lenses were incubated in increasing concentrations of radiolabeled single species proteins in solution. For competition experiments, concentration of each radiolabeled protein was held constant and the adsorption/sorption challenged with increasing concentrations of nonlabeled proteins. Lenses were soaked in phosphate-buffered saline to determine desorption. RESULTS: Group IV lenses bound large amounts of lysozyme, whereas group I lenses bound highest amounts of albumin. Albumin binding to both lens types was relatively strong and could not be competed from binding by other proteins lysozyme, lactoferrin, and mucin. Mucin at high concentrations tended to positively cooperate with the binding of lactoferrin and albumin to all lenses. CONCLUSIONS: Binding of proteins to hydroxyethyl methacrylate-based hydrogel lens surfaces is affected by charge and polymer components, and perhaps manufacturing processes. Albumin binds strongly to lens surfaces, and this may play an adverse role during contact lens wear

Review of evidence for temporal transferability of mode-destination models

One main motivation for developing travel behavior models is to use them to forecast future levels of transport demand. Given that the interest in transport planning is often in long-term forecasts, with forecast horizons of up to 30 years, it is important to consider the transferability of travel behavior models over time. The importance of model transferability has been recognized since disaggregate models were first applied in the late 1970s and early 1980s, but seems to have been largely forgotten recently, because the focus has been on the development of ever more advanced models that better explain current behavior, with a particular focus on the representation of taste heterogeneity. However, there are sufficient grounds to suspect that the model that best explains current behavior may not necessarily be the best tool for forecasting, not least because of the risk of overfitting to the base data. This paper aims to return the crucial issue of temporal transferability of travel demand models to the research agenda. First, the notion of transferability is discussed, highlighting the potential impacts of violations of the assumption of transferability, and the way transferability can be assessed is also described. Next, the most complete review of existing work investigating the temporal transferability of mode and mode-destination models to date is presented. Finally, a number of areas in which future research should be directed are identified