Magneto-mechanically actuated microstructures to efficiently prevent bacterial biofilm formation.

Biofilm colonisation of surfaces is of critical importance in various areas ranging from indwelling medical devices to industrial setups. Of particular importance is the reduced susceptibility of bacteria embedded in a biofilm to existing antimicrobial agents. In this paper, we demonstrate that remotely actuated magnetic cantilevers grafted on a substrate act efficiently in preventing bacterial biofilm formation. When exposed to an alternating magnetic field, the flexible magnetic cantilevers vertically deflect from their initial position periodically, with an extremely low frequency (0.16 Hz). The cantilevers' beating prevents the initial stage of bacterial adhesion to the substrate surface and the subsequent biofilm growth. Our experimental data on E. coli liquid cultures demonstrate up to a 70% reduction in biofilm formation. A theoretical model has been developed to predict the amplitude of the cantilevers vertical deflection. Our results demonstrate proof-of-concept for a device that can magneto-mechanically prevent the first stage in bacterial biofilm formation, acting as on-demand fouling release active surfaces.

Dual role of splenic mononuclear and polymorphonuclear cells in the outcome of ciprofloxacin treatment of Salmonella enterica infections.

OBJECTIVES: To determine the immune cell populations associated with Salmonella enterica serovar Typhimurium before and after ciprofloxacin treatment using a murine model of systemic infection. The effect of depletion of immune cells associating with Salmonella on treatment outcome was also determined. METHODS: We infected mice with a Salmonella enterica serovar Typhimurium strain expressing GFP and used multicolour flow cytometry to identify splenic immune cell populations associating with GFP-positive Salmonella before and after treatment with ciprofloxacin. This was followed by depletion of different immune cell populations using antibodies and liposomes. RESULTS: Our results identified CD11b+CD11chi/lo (dendritic cells/macrophages) and Ly6G+CD11b+ (neutrophils) leucocytes as the main host cell populations that are associated with Salmonella after ciprofloxacin treatment. We therefore proceeded to test the effects of depletion of such populations during treatment. We show that depletion of Ly6G+CD11b+ populations resulted in an increase in the number of viable bacterial cells in the spleen at the end of ciprofloxacin treatment. Conversely, treatment with clodronate liposomes during antimicrobial treatment, which depleted the CD11b+CD11chi/lo populations, resulted in lower numbers of viable bacteria in the tissues. CONCLUSIONS: Our study identified host cells where Salmonella bacteria persist during ciprofloxacin treatment and revealed a dual and opposing effect of removal of Ly6G+CD11b+ and CD11b+CD11chi/lo host cells on the efficacy of antimicrobial treatment. This suggests a dichotomy in the role of these populations in clearance/persistence of Salmonella during antimicrobial treatment.

Crowdsourcing: A novel tool to elicit the student voice in the curriculum design process for an undergraduate diagnostic radiography degree programme.

INTRODUCTION: Stakeholder participation in healthcare curriculum design is an important aspect of higher education with stakeholders including students, staff members, clinical partners, healthcare organisations, patients and members of the public. Significantly, student co-creation, of the curriculum, has become increasingly important. Yet there is limited research which addresses how to engage this group in design processes. METHODS: This paper represents the first phase of a three stage action research spiral whereby the authors evaluated the use of a novel tool for curriculum design processes, anonymised crowdsourcing. This initial phase was open to all students enrolled on an undergraduate diagnostic radiography programme in the UK. To confirm the reliability of the crowdsource design an established eight point crowdsourcing verification tool was applied. RESULTS: Twenty-three unique ideas were generated by participants, 40 comments made and 173 votes cast. Inductive analysis of the comments generated five themes. These included: the role of technology enhanced learning; simulation activities; patient focused curriculum; mental wealth (resilience) authentic assessment approaches. An evaluation of those who had and had not engaged highlighted areas of improvement for the administration of the second and third iterations which will include a wider pool of participants. CONCLUSION: This study from a single programme offers lessons for others wishing to adopt and develop this approach elsewhere. IMPLICATIONS FOR PRACTICE: Several ideas elicited by the crowdsource have been considered by the curriculum design team and will be implemented in the 2020 curriculum thus demonstrating the impact on local education practice of this research approach.

Crowdsourcing in health professions education: What radiography educators can learn from other disciplines.

OBJECTIVES: Crowdsourcing works through an institution outsourcing a function normally performed by an employee or group of individuals. Within a crowdsource users, known as the crowd, form a community who voluntarily undertake a task which involves the pooling of knowledge resources. A literature review was undertaken to identify how the tool is being used in health professions education, and potential for use in radiography education. KEY FINDINGS: 17 papers were returned. Literature identified was assessed against an established crowdsourcing definition. Reviewing these yielded four themes for discussion: student selection procedures, lesson planning, teaching materials and assessment. CONCLUSION: Crowdsourcing is associated with innovative activities through collective solution seeking via a large network of users. It is increasingly being adopted in healthcare training and maybe transferable to educational activities within the field of radiography education.

Within-host spatiotemporal dynamics of systemic Salmonella infection during and after antimicrobial treatment.

OBJECTIVES: We determined the interactions between efficacy of antibiotic treatment, pathogen growth rates and between-organ spread during systemic Salmonella infections. METHODS: We infected mice with isogenic molecularly tagged subpopulations of either a fast-growing WT or a slow-growing ΔaroC Salmonella strain. We monitored viable bacterial numbers and fluctuations in the proportions of each bacterial subpopulation in spleen, liver, blood and mesenteric lymph nodes (MLNs) before, during and after the cessation of treatment with ampicillin and ciprofloxacin. RESULTS: Both antimicrobials induced a reduction in viable bacterial numbers in the spleen, liver and blood. This reduction was biphasic in infections with fast-growing bacteria, with a rapid initial reduction followed by a phase of lower effect. Conversely, a slow and gradual reduction of the bacterial load was seen in infections with the slow-growing strain, indicating a positive correlation between bacterial net growth rates and the efficacy of ampicillin and ciprofloxacin. The viable numbers of either bacterial strain remained constant in MLNs throughout the treatment with a relapse of the infection with WT bacteria occurring after cessation of the treatment. The frequency of each tagged bacterial subpopulation was similar in the spleen and liver, but different from that of the MLNs before, during and after treatment. CONCLUSIONS: In Salmonella infections, bacterial growth rates correlate with treatment efficacy. MLNs are a site with a bacterial population structure different to those of the spleen and liver and where the total viable bacterial load remains largely unaffected by antimicrobials, but can resume growth after cessation of treatment.

Small can be beautiful: 10 years managing colorectal cancer in a rural general hospital.

There has been much recent debate on the relationship between surgical volume and outcomes. The aim of this study was to assess the ability of a rural general hospital to provide care for patients with colorectal cancer in a small-volume practice. A retrospective review of patients treated in a rural general hospital, between January 1993 and December 2002, was undertaken. Patient demographics, disease characteristics, treatments and complications were all recorded. Ninety-eight patients had a final diagnosis of colorectal cancer. There was an equal male: female ratio and an average age of 69 years (40-88 years). Eighty-five percent underwent treatment with curative intent. The postoperative complication rate was low (2% wound infections, 2.3% anastomotic leak rate) and Dukes-specific five-year survival was satisfactory (A > 80%, B and C > 60%). In conclusion, this study adds weight to the argument that even with low-volume workload, satisfactory results can still be obtained.

The effect of intra-neural local anaesthetic infusion on pain following major lower limb amputation.

BACKGROUND: Critical lower limb ischaemia has an annual incidence of 500-1000 per million and around a quarter will undergo a major lower limb amputation. Post operative pain and phantom pain are recognised complications. AIM: The aim of this study was to assess the role of postoperative intraneural infusion of local anaesthetic in patients under-going major lower limb amputation. METHODS: Between May 1998 and July 2001, following amputation patients either had standard post-operative analgesia or had an intra-neural infusion of 0.5% bupivicaine via an infant feeding catheter connected to a standard syringe pump (Alaris). This was a retrospective review and clinical notes of these patients were analysed to assess their post operative course, analgesic requirements and to ascertain phantom limb pain/sensation rates. All the data collected was from standard drug charts, case note entries and out-patient letters. RESULTS: During this time period 64 patients had a major lower limb amputation (31 patients treated routinely and 33 patients had an intra-neural anaesthetic (INA) catheter placed). In the INA group median post-operative opioid analgesia requirement was 10mg versus 74 mg (p=0.0002, Mann-Whitney U) and post-operative prescription of amitriptyline for phantom pain was less common (4 patients versus 11 patients; p=0.0281, Mann-Whitney U). There was no obvious increase in complications or significant adverse events. CONCLUSIONS: Postoperative intra-neural local anaesthetic infusion is a safe and effective technique. It reduces post-operative opioid analgesia requirement and seems to reduce phantom pain development.

Separation of two cell signalling molecules from a symbiotic sponge that modify algal carbon metabolism.

Two distinct cell signals have been isolated from the sponge host of the tropical sponge/macroalga symbiotic association Haliclona cymiformis/Ceratodictyon spongiosum. These water soluble cell signals (M(r) between 500 and 1000) modify separate steps in the carbon metabolism in both C. spongiosum and the microalga, Symbiodinium from the coral Plesiastrea versipora. The first signal, host release factor (HRF), stimulates the release of compounds derived from algal photosynthesis; the second signal, photosynthesis inhibiting factor (PIF), partially inhibits photosynthesis. Both HRF from the sponge H. cymiformis and HRF from the coral P. versipora stimulated the release of glycerol from Symbiodinium suggesting that they act at a similar step in the metabolism of this alga. This is the first time that such cell signals have been isolated from a sponge. We suggest that they belong to a family of similar cell signals from symbiotic invertebrates that modify algal carbon metabolism.

A cell signal from the coral Plesiastrea versipora reduces starch synthesis in its symbiotic alga, Symbiodinium sp.

We have previously shown that the coral cell signal, host release factor (HRF) from the scleractinian coral Plesiastrea versipora (Lamarck) stimulates the release of glycerol from its symbiotic dinoflagellate, Symbiodinium sp. Glycerol is a precursor for algal triacylglycerol (TG) and starch, and we have previously observed that HRF reduces the amount of newly synthesized TG in Symbiodinium sp. We have now examined the effect of P. versipora HRF on starch synthesis in isolated Symbiodinium. HRF had no effect on starch synthesis after 2 h photosynthesis (16.3+/-3.0 microg starch per 10(6) algae) compared with algae in seawater (13.9+/-1.2 microg starch per 10(6) algae). However, after 4 h incubation in HRF, there was a reduction (0-76%), in the amount of newly synthesized starch which was correlated with the amount of HRF (10-76 microg/ml). Reducing algal synthesis of both TG and starch in parallel with stimulating glycerol release may provide a mechanism to regulate the population density of intracellular symbiotic algae while still ensuring the transfer of photosynthetically fixed carbon to the animal host in the form of glycerol.

Aposymbiotic Plesiastrea versipora continues to produce cell-signalling molecules that regulate the carbon metabolism of symbiotic algae.

The scleractinian coral Plesiastrea versipora produces cell signals that regulate the carbon metabolism of its symbiotic algae. Host release factor (HRF) stimulates the release of photosynthate, and photosynthesis inhibiting factor (PIF) partially inhibits carbon fixation in freshly isolated symbiotic algae. Naturally occurring aposymbiotic specimens of P. versipora are rare in Port Jackson, Australia, but one that was collected contained HRF and PIF. Artificially produced aposymbiotic corals of P. versipora that had been kept in the dark for up to 23 months continued to produce both HRF and PIF in the absence of photosynthetically active algae. Aposymbiotic P. versipora from which most of the tissue had been removed, regenerated when they were kept in the dark and fed; the regenerated tissue also contained HRF and PIF. These results suggest that the presence of symbiotic algae is not required for the production of HRF and PIF in P. versipora. We suggest that these cell signals may have evolved in response to symbiosis with Symbiodinium sp. but are now always expressed in the coral P. versipora.

A symbiosome membrane is not required for the actions of two host signalling compounds regulating photosynthesis in symbiotic algae isolated from cnidarians.

In many cnidarians, symbiotic algae live within host-derived symbiosomes. We determined whether a symbiosome membrane alters the response of isolated symbiotic algae to two signalling compounds that regulate algal carbon metabolism. Host release factor (HRF), which stimulates photosynthate release, and photosynthesis inhibiting factor (PIF), which inhibits photosynthetic carbon fixation, are found in homogenised tissue of the scleractinian coral Plesiastrea versipora. Compared with seawater controls, photosynthate release from isolated algae incubated in P. versipora homogenate for 2 h in the light was: 6 to 19-fold higher from its own algae (free of symbiosomes); 19 to 32-fold higher from Zoanthid robustus algae (within symbiosomes) and 3 to 24-fold higher from Z. robustus algae (free of symbiosomes); and from cultured algae (free of symbiosomes) was seven-fold higher from Montipora verrucosa and four-fold higher from Cassiopeia xamachana. Incubation of algae in P. versipora homogenate inhibited photosynthesis by: 33-49% in P. versipora algae; 29-47% in Z. robustus algae (regardless of whether or not the symbiosome was present); and 25% in M. verrucosa algae. In C. xamachana algae, photosynthesis increased. We conclude that the symbiosome is not essential for, yet does not block, the effects of HRF and PIF.

An in vitro transposon system for highly regulated gene expression: construction of Escherichia coli strains with arabinose-dependent growth at low temperatures.

Placing a gene of interest under the control of an inducible promoter greatly aids the purification, localization and functional analysis of proteins but usually requires the sub-cloning of the gene of interest into an appropriate expression vector. Here, we describe an alternative approach employing in vitro transposition of Tn Omega P(BAD) to place the highly regulable, arabinose inducible P(BAD) promoter upstream of the gene to be expressed. The method is rapid, simple and facilitates the optimization of expression by producing constructs with variable distances between the P(BAD) promoter and the gene. To illustrate the use of this approach, we describe the construction of a strain of Escherichia coli in which growth at low temperatures on solid media is dependent on threshold levels of arabinose. Other uses of the transposable promoter are also discussed.

MAdCAM-1 expressed in chronic inflammatory liver disease supports mucosal lymphocyte adhesion to hepatic endothelium (MAdCAM-1 in chronic inflammatory liver disease).

Mucosal addressin cell adhesion molecule (MAdCAM-1) plays a pivotal role in T-lymphocyte homing to the gut. Given the strong association between the autoimmune liver diseases primary sclerosing cholangitis and autoimmune hepatitis and inflammatory bowel disease, we investigated the role of MAdCAM-1 in recruiting mucosal lymphocytes to the liver. MAdCAM-1 was strongly expressed on inflamed portal vein/sinusoidal endothelium in autoimmune mediated liver disease. In modified Stamper-Woodruff assays, MAdCAM-1 on hepatic vessels supported adhesion of alpha4beta7+ lymphocytes (i.e., gut-derived T cells) from patients with inflammatory bowel disease and primary sclerosing cholangitis. This adhesion was inhibited by pretreatment with blocking antibodies to MAdCAM-1, alpha4beta7, or the integrin alpha4 chain indicating that MAdCAM-1 in inflamed liver is functionally active. Circulating lymphocytes from patients with primary sclerosing cholangitis showed rolling adhesion on MAdCAM-1 transfectants in a flow-based adhesion assay that could be blocked by anti-MAdCAM-1 or anti-alpha4beta7 mAbs. These findings indicate that, under certain circumstances, vessels in the human liver support adhesion of alpha4beta7+ mucosal lymphocytes via binding to aberrantly expressed MAdCAM-1 on liver endothelium. This provides a mechanism to explain the hepatic recruitment of mucosal lymphocytes in inflammatory liver disease complicating inflammatory bowel disease.

Responses of olfactory receptor neurons in Utetheisa ornatrix to gender-specific odors.

We recorded the electrophysiological responses of individual olfactory receptor neurons in sensilla trichodea on the antennae of adult arctiid moths, Utetheisa ornatrix, to stimulation with volatiles associated with both sexes. All trichoid sensilla contain at least two receptor neurons, each with distinct action potential amplitudes and waveforms, that respond dichotomously to male and female odors. Although, neither female neuron responds to extracts of coremata or the male-produced pheromone hydroxydanaidal, they do respond in a gender-specific manner to the volatiles emanating from whole pupae, hemolymph, thoracic froth, and adult animals of several ages. Thoracic froth, which contains pyrrolizidine alkaloids, is thought to play a role in defense. Froth from moths reared on diets, with or without added pyrrolizidine alkaloids, were equally effective in eliciting gender-specific patterns of response. Male trichoid receptor neurons respond to these same materials with similar patterns of activation. These receptor neurons provide information about substances, which we have termed "gender odors," that are persistently emitted by nearby animals. These substances do not appear to be the same as those already known to be involved in defense or the sexual dialog between individuals.

Comparison of three-dimensional visualization techniques for depicting the scala vestibuli and scala tympani of the cochlea by using high-resolution MR imaging.

BACKGROUND AND PURPOSE: Cochlear implantation requires introduction of a stimulating electrode array into the scala vestibuli or scala tympani. Although these structures can be separately identified on many high-resolution scans, it is often difficult to ascertain whether these channels are patent throughout their length. The aim of this study was to determine whether an optimized combination of an imaging protocol and a visualization technique allows routine 3D rendering of the scala vestibuli and scala tympani. METHODS: A submillimeter T2 fast spin-echo imaging sequence was designed to optimize the performance of 3D visualization methods. The spatial resolution was determined experimentally using primary images and 3D surface and volume renderings from eight healthy subjects. These data were used to develop the imaging sequence and to compare the quality and signal-to-noise dependency of four data visualization algorithms: maximum intensity projection, ray casting with transparent voxels, ray casting with opaque voxels, and isosurface rendering. The ability of these methods to produce 3D renderings of the scala tympani and scala vestibuli was also examined. The imaging technique was used in five patients with sensorineural deafness. RESULTS: Visualization techniques produced optimal results in combination with an isotropic volume imaging sequence. Clinicians preferred the isosurface-rendered images to other 3D visualizations. Both isosurface and ray casting displayed the scala vestibuli and scala tympani throughout their length. Abnormalities were shown in three patients, and in one of these, a focal occlusion of the scala tympani was confirmed at surgery. CONCLUSION: Three-dimensional images of the scala vestibuli and scala tympani can be routinely produced. The combination of an MR sequence optimized for use with isosurface rendering or ray-casting algorithms can produce 3D images with greater spatial resolution and anatomic detail than has been possible previously.

Symptomatic carpal tunnel syndrome after orthotopic liver transplantation: a retrospective analysis.

BACKGROUND: Carpal tunnel syndrome (CTS) is an entrapment neuropathy of the median nerve and has been reported after renal transplantation; there are no reports of CTS after liver transplantation. METHODS: The incidence of and the risk factors for CTS were assessed in 1350 liver allograft recipients. RESULTS: Seventeen women and two men with CTS were identified. Women developed symptoms at a median time of 6.8 months, and all but one received transplants because of primary biliary cirrhosis (PBC). All 17 patients were taking cyclosporine. The only risk factor for CTS was the pretransplant diagnosis of PBC (6.7% of 240 PBC patients surviving 6 months or more compared with 0.4% of 717 patients who received grafts for other indications). CONCLUSIONS: CTS may occur in patients early after liver transplantation; because in many cases the symptoms were attributed to cyclosporine neurotoxicity, the diagnosis should be considered, especially in patients who received grafts because of PBC.

Electrophysiological responses from receptor neurons in mosquito maxillary palp sensilla.

We recently completed an electrophysiological study of the receptor neurons found in the sensilla basiconica on the maxillary palps of mosquitoes. Our results describe a class of receptor neurons whose properties could provide the afferent input required for some aspects of CO2-modulated host-locating behaviour. First, these neurons have apparent thresholds (150-300 ppm) which are at, or below, the concentration of CO2 (300-330 ppm) normally reported for ambient air. Second, their concentration-response functions are steep, such that small (50 ppm) fluctuations in concentration elicit reliable changes in activity. Third, they behave like absolute CO2 detectors in that their ability to respond to step increases in CO2 concentration is little influenced by the background concentration of CO2. And fourth, a linear extrapolation of the observed response function to the levels that might be expected near vertebrate hosts suggests that these neurons have sufficient dynamic range to cover those CO2 concentrations that should be encountered during a large portion of the behaviour likely involved in host location. The mosquito CO2 receptor neuron thus has an appropriately low threshold and a steep concentration-response function, it is not desensitized by ambient levels of stimulation, and it has a dynamic range appropriate for the distribution of CO2 concentrations expected in the environment. In addition, this sensillum contains two other receptor neurons, neither of which respond to CO2. One of these neurons responds to stimulation with very low doses of another behaviourally relevant compound, 1-octen-3-ol.

Electrophysiological responses of receptor neurons in mosquito maxillary palp sensilla to carbon dioxide.

Sensilla basiconica on the maxillary palps of female Aedes aegypti contain a receptor neuron which produces a phasic-tonic pattern of action potential response to low concentrations (150-300 ppm) of carbon dioxide (CO2), a stimulus known to be involved with host seeking behavior. These receptor neurons respond reliably to small increments in CO2 concentration (e.g., 50 ppm). We were particularly interested in evaluating the possibility that the sensitivity to step increases in CO2 concentration could be modulated by alterations in the background levels of CO2, over a range which might be encountered during host-seeking behavior. We report here that the response (impulses/s) to a single pulse of a given concentration of CO2 appears to be independent of the background level of CO2, unless that level is equal to or greater than the concentration of the stimulus pulse. Females of other mosquito species, including: Anopheles stephensi, Culex quinquefasciatus, Culiseta melanura, and Aedes taeniorhynchus, also possess sensilla with receptor neurons that respond with comparable sensitivity to CO2 stimulation. However, there is much interspecific variation in both the external morphology of the maxillary palp and the distribution of sensilla along the palp. Male Ae. aegypti have morphologically similar sensilla which also contain a receptor neuron that responds to CO2.