The limitations of in vitro experimentation in understanding biofilms and chronic infection

We have become increasingly aware that during infection, pathogenic bacteria often grow in multi- cellular biofilms which are often highly resistant to antibacterial strategies. In order to understand how biofilms form and contribute to infection, in vitro biofilm systems such as microtitre plate as- says and flow cells, have been heavily used by many research groups around the world. Whilst these methods have greatly increased our understanding of the biology of biofilms, it is becoming increasingly apparent that many of our in vitro methods do not accurately represent in vivo conditions. Here we present a systematic review of the most widely used in vitro biofilm systems, and we discuss why they are not always representative of the in vivo biofilms found in chronic infections. We present examples of methods that will help us to bridge the gap between in vitro and in vivo biofilm work, so that our bench-side data can ultimately be used to improve bedside treatment

Digitally Reconstructed Portal Radiographs for Use in Radiotherapy Treatment Verification

Introduction In radiation treatment planning using virtual simulation [Sherouse, 1991], it is common practice in our clinic to verify a treatment plan by comparing a diagnostic-energy x-ray film from physical simulation to a digitally reconstructed radiograph (DRR) derived from the patient's CT dataset and the prescribed beam orientation [Chaney, 1994]. Likewise, the simulator radiograph is compared to a portal image (either a portal film or an electronic portal image) to verify the proper patient/treatment machine setup during actual therapy. Unfortunately, due to very different attenuation processes occurring at the different imaging energies, comparison of a diagnostic-energy simulator film or standard DRR to a megavoltage-energy portal image is not optimal for verification purposes. In this work, we describe a new means for generating realistic, reconstructed portal radiographs from virtual simulation and discuss their potential uses in areas related to radiotherapy treat

An aggregate deformation homotopy method for min-max-min problems with max-min constraints

Nonsmooth optimization, Min-max-min problem, Aggregate function, Homotopy method,