An integrated instrument for rapidly deforming living cells using rapid pressure pulses and simultaneously monitoring applied strain in near real time.

Because many types of living cells are sensitive to applied strain, different in vitro models have been designed to elucidate the cellular and subcellular processes that respond to mechanical deformation at both the cell and tissue level. Our focus was to improve upon an already established strain system to make it capable of independently monitoring the deflection and applied pressure delivered to specific wells of a commercially available, deformable multiwell culture plate. To accomplish this, we devised a custom frame that was capable of mounting deformable 6 or 24 well plates, a pressurization system that could load wells within the plates, and a camera-based imaging system which was capable of capturing strain responses at a sufficiently high frame rate. The system used a user defined program constructed in Labview(®) to trigger plate pressurization while simultaneously allowing the deflection of the silicone elastomeric plate bottoms to be imaged in near real time. With this system, up to six wells could be pulsed simultaneously using compressed air or nitrogen. Digital image capture allowed near-real time monitoring of applied strain, strain rate, and the cell loading profiles. Although our ultimate goal is to determine how different strain rates applied to neurons modulates their intrinsic biochemical cascades, the same platform technology could be readily applied to other systems. Combining commercially available, deformable multiwell plates with a simple instrument having the monitoring capabilities described here should permit near real time calculations of stretch-induced membrane strain in multiple wells in real time for a wide variety of applications, including high throughput drug screening.

Extractable free monomers from self-cured dental sealants resulting from dispensing errors.

High performance liquid chromatography (HPLC) experiments were performed on a series of commercially available self-curing dental sealant materials that were deliberately mismixed. The goal of the experiments was to measure the amount of extractable sealant under conditions of nonideal processing as might happen clinically. The stoichiometry of the two component resins ranged from a 2/1 to a 1/2 catalyst to base mixture using a commercially available self-cure sealant that was to be mixed 1/1 based on the manufacturer's recommendations. Following fabrication the samples were immersed in an ethanol/water mixture as an extraction fluid that was then analyzed using HPLC. Values other than the 1-1 stoichiometry led to a statistically larger extractable content of bis-glycidyl methacrylate relative to the control. The extractable fraction of triethylene glycol dimethacrylate also increased with mismixing, although statistical differences varied somewhat more. Given the increased concerns about the effects of extractable monomers on the endocrine system, there may be an increased need to maintain proper stoichiometry in a clinical setting.

Developing national standard clinical EDI messages.

This paper presents a case study and methodology derived from the experience of the National Health Service (NHS) in England. The methodology is based on explicit ownership by clinicians of the message development process and a separation of the task of definition of information requirement from that of technical assurance and testing.

Developing EDI messages and supporting data models: a "bottom up" approach based on "single business purpose" messages meets user needs.

Electronic Data Interchange (EDI) is increasingly being used for the exchange of patient, administrative, and clinical information. There is work in Europe and the United States directed at describing a preferred approach to the task of defining and modeling the information content of standard EDI messages. The literature is currently silent about the criteria for selecting the scope of an individual message. This paper argues the case for developing a larger number of discrete, simpler single purpose messages, rather than "superset" framework messages. The paper also questions the validity of the currently prevailing view that EDI messages should draw their initial content and business purpose from an already predefined model purporting to be "the model of the healthcare delivery system." The paper also examines the ongoing work on defining EDI scenarios of the Open EDI Group [1], which is developing an Open EDI Reference Model Standard on experience gained in using the approach to message development advocated in CR 1350:1993 [1] and the early experience in gaining user acceptance of the first messages developed using this approach.