Targeting cyclic di-GMP signalling: a strategy to control biofilm formation?

Cyclic di-GMP is a second messenger found in almost all eubacteria that acts to regulate a wide range of functions including developmental transitions, adhesion and biofilm formation. Cyclic di-GMP is synthesised from two GTP molecules by diguanylate cyclases that have a GGDEF domain and is degraded by phosphodiesterases with either an EAL or an HD-GYP domain. Proteins with these domains often contain additional signal input domains, suggesting that their enzymatic activity may be modulated as a response to different environmental or cellular cues. Cyclic di-GMP exerts a regulatory action through binding to diverse receptors that include a small protein domain called PilZ, enzymatically inactive GGDEF, EAL or HD-GYP domains, transcription factors and riboswitches. In many bacteria, high cellular levels of cyclic di-GMP are associated with a sessile, biofilm lifestyle, whereas low levels of the nucleotide promote motility and virulence factor synthesis in pathogens. Elucidation of the roles of cyclic di-GMP signalling in biofilm formation has suggested strategies whereby modulation of the levels of the nucleotide or interference with signalling pathways may lead to inhibition of biofilm formation or promotion of biofilm dispersal. In this review we consider these approaches for the control of biofilm formation, beginning with an overview of cyclic di-GMP signalling and the different ways that it can act in regulation of biofilm dynamics.

Application of in situ diffraction in high-throughput structure determination platforms.

Macromolecular crystallography (MX) is the most powerful technique available to structural biologists to visualize in atomic detail the macromolecular machinery of the cell. Since the emergence of structural genomics initiatives, significant advances have been made in all key steps of the structure determination process. In particular, third-generation synchrotron sources and the application of highly automated approaches to data acquisition and analysis at these facilities have been the major factors in the rate of increase of macromolecular structures determined annually. A plethora of tools are now available to users of synchrotron beamlines to enable rapid and efficient evaluation of samples, collection of the best data, and in favorable cases structure solution in near real time. Here, we provide a short overview of the emerging use of collecting X-ray diffraction data directly from the crystallization experiment. These in situ experiments are now routinely available to users at a number of synchrotron MX beamlines. A practical guide to the use of the method on the MX suite of beamlines at Diamond Light Source is given.

New camera-based microswitch technology to monitor small head and mouth responses of children with multiple disabilities.

OBJECTIVE: Assessing a new camera-based microswitch technology, which did not require the use of color marks on the participants' face. METHOD: Two children with extensive multiple disabilities participated. The responses selected for them consisted of small, lateral head movements and mouth closing or opening. The intervention was carried out according to a multiple probe design across responses. The technology involved a computer with a CPU using a 2-GHz clock, a USB video camera with a 16-mm lens, a USB cable connecting the camera and the computer, and a special software program written in ISO C++ language. RESULTS: The new technology was satisfactorily used with both children. Large increases in their responding were observed during the intervention periods (i.e. when the responses were followed by preferred stimulation). CONCLUSION: The new technology may be an important resource for persons with multiple disabilities and minimal motor behavior.

Persons with multiple disabilities use forehead and smile responses to access or choose among technology-aided stimulation events.

A variety of technology-aided programs have been developed to help persons with congenital or acquired multiple disabilities access preferred stimuli or choose among stimulus options. The application of those programs may pose problems when the participants have very limited behavior repertoires and are unable to use conventional responses and microswitches. The present two studies assessed non-conventional response-microswitch solutions for three of those participants. Study I included two participants who were exposed to a program in which forehead skin movement was the response required to access preferred stimulation. The microswitch was an optic sensor combined with a small black sticker on the forehead. Study II included one participant who was exposed to a program in which a smile response was required to choose among stimuli. The microswitch for monitoring the smile was a new camera-based technology. The results of the two studies showed that the response-microswitch solutions were suitable for the participants and enabled them to perform successfully. Implications of the studies for people with limited motor behavior and issues for future research were discussed.

Two persons with multiple disabilities use camera-based microswitch technology to control stimulation with small mouth and eyelid responses.

BACKGROUND: A camera-based microswitch technology was recently developed to monitor small facial responses of persons with multiple disabilities and allow those responses to control environmental stimulation. This study assessed such a technology with 2 new participants using slight variations of previous responses. METHOD: The technology involved a computer with a CPU using a 2GHz clock, a USB video camera with 16-mm lens, and special software. Small colour spots were used under the lower lip of one participant and on the eyelid of the other participant to aid the camera and computer to detect their mouth and eyelid responses. The study involved an ABAB design and included a 3-week post-intervention check. RESULTS: The participants' mouth and eyelid responses increased during the intervention (B) phases and post-intervention check (i.e., when the technology allowed them to control stimulation). CONCLUSIONS: Camera-based microswitch technology can help persons with multiple disabilities control stimulation with small responses.

Persons with multiple disabilities select environmental stimuli through a smile response monitored via camera-based technology.

OBJECTIVE: To assess whether two persons with multiple disabilities could use smile expressions and new camera-based microswitch technology to select environmental stimuli. METHOD: Within each session, a computer system provided samples/reminders of preferred and non-preferred stimuli. The camera-based microswitch determined whether the participants had smile expressions in relation to those samples. If they did, stimuli matching the specific samples to which they responded were presented for 20 seconds. RESULTS: The smile expression could be profitably used by the participants who managed to select means of ∼70% or 75% of the preferred stimulus opportunities made available by the environment while avoiding almost all the non-preferred stimulus opportunities. CONCLUSION: Smile expressions (a) might be an effective and rapid means for selecting preferred stimulation and (b) might develop into cognitively more elaborate forms of responding through the learning experience (i.e. their consistent association with positive/reinforcing consequences).

Camera-based microswitch technology for eyelid and mouth responses of persons with profound multiple disabilities: two case studies.

These two studies assessed camera-based microswitch technology for eyelid and mouth responses of two persons with profound multiple disabilities and minimal motor behavior. This technology, in contrast with the traditional optic microswitches used for those responses, did not require support frames on the participants' face but only small color marks. The person involved in Study I had previously used optic sensors fixed on an eyeglasses' frame for detecting his eyelid- and mouth-opening responses. However, a deterioration of his head posture was making the correct location/use of this frame progressively more difficult. The person involved in Study II had previously been selected for a program relying on eyelid-closure responses and an optic sensor. Such a program however appeared difficult to implement given his sideward lying position and dystonic head movements. The new technology could be satisfactorily applied with both participants using mouth and eyelid opening with the first participant and eyelid closures with the second participant. Both participants had large increases in responding during the intervention periods (i.e., when their responses were followed by preferred stimulation). The findings are discussed in relation to the role of the new technology in helping persons with multiple disabilities and minimal motor behavior.