On the equivalence of the X-ray scattering retrieval with beam tracking and analyser-based imaging using a synchrotron source.

X-ray phase contrast imaging (XPCI) methods give access to contrast mechanisms that are based on the refractive properties of matter on top of the absorption coefficient in conventional x-ray imaging. Ultra small angle x-ray scattering (USAXS) is a phase contrast mechanism that arises due to multiple refraction events caused by physical features of a scale below the physical resolution of the used imaging system. USAXS contrast can therefore give insight into subresolution structural information, which is an ongoing research topic in the vast field of different XPCI techniques. In this study, we quantitatively compare the USAXS signal retrieved by the beam tracking XPCI technique with the gold standard of the analyzer based imaging XPCI technique using a synchrotron x-ray source. We find that, provided certain conditions are met, the two methods measure the same quantity.

On the influence of lipid-induced optical anisotropy for the bioimaging of exo- or endocytosis with interference microscopic imaging.

Some implementations of interference microscopy imaging use digital holographic measurements of complex scattered fields to reconstruct three-dimensional refractive index maps of weakly scattering, semi-transparent objects, frequently encountered in biological investigations. Reconstruction occurs through application of the object scattering potential which assumes an isotropic refractive index throughout the object. Here, we demonstrate that this assumption can in some circumstances be invalid for biological imaging due to the presence of lipid-induced optical anisotropy. We show that the nanoscale organization of lipids in the observation of cellular endocytosis with polarized light induces a significant change in far-field scattering. We obtain this result by presenting a general solution to Maxwell's equations describing light scattering of core-shell particles near an isotropic substrate covered with an anisotropic thin film. This solution is based on an extension of the Bobbert-Vlieger solution for particle scattering near a substrate delivering an exact solution to the scattering problem in the near field as well as far field. By applying this solution to study light scattering by a lipid vesicle near a lipid bilayer, whereby the lipids are represented through a biaxial optical model, we conclude through ellipsometry concepts that effective amounts of lipid-induced optical anisotropy significantly alter far-field optical scattering in respect to an equivalent optical model that neglects the presence of optical anisotropy.

Polarization-multiplexed encoding at nanometer scales.

Optical data storage was developed using binary encoding primarily due to signal to noise ratio considerations. We report on a multiplexing method that allows a seven fold storage increase, per storage layer, per side, and propose one that can yield theoretically a 20+ fold increase. Multiplexing is achieved by encoding information in polarization via appropriately oriented nanostructures that emit strongly polarized light when excited by unpolarized light. The storage increase is possible due to the significantly reduced crosstalk that results form using unpolarized light.

Confocal polarization imaging in high-numerical-aperture space.

In this work we describe theoretical and experimental physical aspects of high-resolution imaging polarimetry and its application to polarization-multiplexed encoding. We theoretically demonstrate that it is possible to resolve the orientation of two fixed dipole-like emitters placed significantly below the resolution limit if their emission is uncorrelated. Furthermore, we experimentally demonstrate this phenomenon by illuminating closely spaced asymmetric nanopits with unpolarized light and subsequently determining their individual orientation and position from the measured spatial distributions of the azimuth angle of the polarization and degree of polarization, respectively. Reduction of the optical resolution of the imaging system is also shown to only weakly affect resolution obtainable via polarization measurements.

T staging esophageal tumors with x rays.

With histopathology results typically taking several days, the ability to stage tumors during interventions could provide a step change in various cancer interventions. X-ray technology has advanced significantly in recent years with the introduction of phase-based imaging methods. These have been adapted for use in standard labs rather than specialized facilities such as synchrotrons, and approaches that enable fast 3D scans with conventional x-ray sources have been developed. This opens the possibility to produce 3D images with enhanced soft tissue contrast at a level of detail comparable to histopathology, in times sufficiently short to be compatible with use during surgical interventions. In this paper we discuss the application of one such approach to human esophagi obtained from esophagectomy interventions. We demonstrate that the image quality is sufficiently high to enable tumor T staging based on the x-ray datasets alone. Alongside detection of involved margins with potentially life-saving implications, staging tumors intra-operatively has the potential to change patient pathways, facilitating optimization of therapeutic interventions during the procedure itself. Besides a prospective intra-operative use, the availability of high-quality 3D images of entire esophageal tumors can support histopathological characterization, from enabling "right slice first time" approaches to understanding the histopathology in the full 3D context of the surrounding tumor environment.

Restoration of photoreceptor ultrastructure and function in retinal degeneration slow mice by gene therapy.

The gene Prph2 encodes a photoreceptor-specific membrane glycoprotein, peripherin-2 (also known as peripherin/rds), which is inserted into the rims of photoreceptor outer segment discs in a complex with rom-1 (ref. 2). The complex is necessary for the stabilization of the discs, which are renewed constantly throughout life, and which contain the visual pigments necessary for photon capture. Mutations in Prph2 have been shown to result in a variety of photoreceptor dystrophies, including autosomal dominant retinitis pigmentosa and macular dystrophy. A common feature of these diseases is the loss of photoreceptor function, also seen in the retinal degeneration slow (rds or Prph2 Rd2/Rd2) mouse, which is homozygous for a null mutation in Prph2. It is characterized by a complete failure to develop photoreceptor discs and outer segments, downregulation of rhodopsin and apoptotic loss of photoreceptor cells. The electroretinograms (ERGs) of Prph2Rd2/Rd2 mice have greatly diminished a-wave and b-wave amplitudes, which decline to virtually undetectable concentrations by two months. Subretinal injection of recombinant adeno-associated virus (AAV) encoding a Prph2 transgene results in stable generation of outer segment structures and formation of new stacks of discs containing both perpherin-2 and rhodopsin, which in many cases are morphologically similar to normal outer segments. Moreover, the re-establishment of the structural integrity of the photoreceptor layer also results in electrophysiological correction. These studies demonstrate for the first time that a complex ultrastructural cell defect can be corrected both morphologically and functionally by in vivo gene transfer.

Diabetic fatty liver disease is associated with specific changes in blood-borne markers.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) can lead to cirrhosis and hepatocellular carcinoma and is strongly associated with obesity and insulin resistance. The aim of this study was to assess if plasma markers associated with NAFLD are increased in people with concomitant diabetes compared with those without. METHODS: A total of 68 participants were recruited from diabetes and liver clinics. Fatty liver disease was indicated by routine blood tests and ultrasonography. Forty-seven participants had type 2 diabetes; of them, 18 had no fatty liver disease as defined previously (DNoFLD) and 29 had fatty liver disease (DFLD); the remaining 21 had fatty liver disease but no diabetes (NonDFLD). Serum samples were analyzed for adiponectin (APN), alanine and aspartate aminotransferases and plasma for cholesterol, triglyceride, hyaluronic acid (HA), procollagen peptide III, alkaline phosphatase and fibrinogen. RESULTS: Hyaluronic acid and procollagen peptide III were significantly higher and adiponectin significantly lower in DFLD than NonDFLD and DNoFLD, the difference being particularly marked for hyaluronic acid and APN. There was no difference in these markers between NonDFLD and DNoFLD and no association between any plasma or serum marker and ultrasound grade of steatosis. CONCLUSION: We have identified markers of hepatic steatosis that appear to be specific for people with type 2 diabetes. A further longitudinal study is merited to assess the role of these markers in understanding the progression of hepatic steatosis and fibrosis in people with and without diabetes.

The effect of a variable focal spot size on the contrast channels retrieved in edge-illumination X-ray phase contrast imaging.

Multi-modal X-ray imaging allows the extraction of phase and dark-field (or "Ultra-small Angle Scatter") images alongside conventional attenuation ones. Recently, scan-based systems using conventional sources that can simultaneously output the above three images on relatively large-size objects have been developed by various groups. One limitation is the need for some degree of spatial coherence, achieved either through the use of microfocal sources, or by placing an absorption grating in front of an extended source. Both these solutions limit the amount of flux available for imaging, with the latter also leading to a more complex setup with additional alignment requirements. Edge-illumination partly overcomes this as it was proven to work with focal spots of up to 100 micron. While high-flux, 100 micron focal spot sources do exist, their comparatively large footprint and high cost can be obstacles to widespread translation. A simple solution consists in placing a single slit in front of a large focal spot source. We used a tunable slit to study the system performance at various effective focal spot sizes, by extracting transmission, phase and dark-field images of the same specimens for a range of slit widths. We show that consistent, repeatable results are obtained for varying X-ray statistics and effective focal spot sizes. As the slit width is increased, the expected reduction in the raw differential phase peaks is observed, compensated for in the retrieval process by a broadened sensitivity function. This leads to the same values being correctly retrieved, but with a slightly larger error bar i.e. a reduction in phase sensitivity. Concurrently, a slight increase in the dark-field signal is also observed.

High prevalence of edin-C encoding RhoA-targeting toxin in clinical isolates of Staphylococcus aureus.

Staphylococcus aureus, a major causative agent of human infection, produces a large array of virulence factors, including various toxins. Among them, the host RhoA GTPase ADP-ribosylating EDIN toxins are considered as potential virulence factors. Using the polymerase chain reaction (PCR) assay, we analyzed the virulence profile of 256 S. aureus isolates from various clinical sites of infections. We developed specific primers to detect the three isoforms of edin-encoding genes. We found a prevalence of 14% (36 bacteria) of edin-encoding genes among these clinical isolates. Strikingly, we found that 90% of all edin-bearing S. aureus isolates carried the type-C allele. Both the spa types and the profile of virulence factors of these edin-positive isolates are highly variable. Notably, we show for the first time that edin-C-positive isolates were more frequently recovered from deep-seated infections than other types of infections. Our present work, thus, strongly suggests that the presence of edin-C is a risk factor of S. aureus dissemination in tissues and, thus, represents a predictive marker for a pejorative evolution of staphylococcal infections.

Pulmonary rehabilitation following lung transplantation.

Pulmonary rehabilitation (PR) following lung transplantation (LT) is regarded as part of best practice management; however, the optimal duration and composition of PR programs for LT patients is unknown. This study aimed to describe changes in functional outcomes of LT patients who participated in our standard outpatient post-LT PR program. A prospective, repeated measures design was used. Functional exercise capacity (6-minute walk distance [6MWD]), lung function (forced expiratory volume in 1 second [FEV(1)], forced vital capacity [FVC]) and quality of life (Short Form 34 [SF-36]) were assessed at 1, 2, and 3 months following LT. All subjects attended a 1-hour outpatient group exercise training class 3 days per week until 12 weeks post-LT and education sessions facilitated by the multidisciplinary team. Patients with postoperative complications (mechanical ventilation, major myopathy) were excluded. Data were analyzed using descriptive statistics and analysis of variance with repeated measures. Thirty-six subjects (50% men), 81% bilateral LT, mean age 46 +/- 14 years were included. Significant improvements were demonstrated in 6MWD (451 +/- 126 m to 543 +/- 107 m, P < .001), FEV(1) (71% +/- 18% to 81% +/- 4%, P < .0001), FVC (69% +/- 14% to 81% +/- 18%, P < .0001), and all SF36 domains (P < .05). Large improvements were seen in the first month of rehabilitation, with smaller but clinically significant improvements continuing in the second month. Further prospective, longitudinal studies are required to determine whether a longer period of pulmonary rehabilitation would result in additional improvements.

Rehabilitation and transition after lung transplantation in children.

We describe the key components of an outpatient pediatric recovery and rehabilitation program set up within the adult lung transplant service at the Alfred Hospital, Melbourne. Following discharge, pediatric lung transplant recipients and their families participated in an intensive 3-month outpatient rehabilitation program. Weekly sessions included education regarding transplant issues, physiotherapy, and occupational therapy sessions. The overall aim of the program was to comprehensively address physical rehabilitation and psychosocial and educational needs. Sessions tailored to meet the individual needs of the child were presented at an appropriate cognitive level. Education sessions for both the children and parents focused on medications, identification of infection and rejection, nutrition, physiotherapy/rehabilitation, occupational roles and stress management, donor issues, psychosocial readjustment, and transition issues. Physiotherapy included a progressive aerobic and strength training program, postural reeducation, and core stability. We incorporate Age-appropriate play activities: running, dancing, jumping, ball skills, and so on. Occupational therapy sessions addressed the primary roles of patient, students, and player. Transitions such as returning to school, friends, and the community were explored. Issues discussed included adjustment to new health status, strategies to manage side effects of medications, and altered body image issues. Weekly multidisciplinary team meetings were used to discuss and plan the rehabilitation progress. School liaison and visits occurred prior to school commencement with follow-up offered to review the ongoing transition process. Both patients and parents have reported a high level of satisfaction with the rehabilitation program. We plan to formally evaluate the program in the future.

Short term improvement in exercise capacity and symptoms following exercise training in interstitial lung disease.

BACKGROUND: Interstitial lung disease (ILD) is characterised by exertional dyspnoea, exercise limitation and reduced quality of life. The role of exercise training in this diverse patient group is unclear. The aims of this study were to establish the safety of exercise training in ILD; its effects on exercise capacity, dyspnoea and quality of life; and whether patients with idiopathic pulmonary fibrosis (IPF) had similar responses to those with other types of ILD. METHODS: 57 subjects with ILD (34 IPF) were randomised to receive 8 weeks of supervised exercise training or weekly telephone support. The 6 min walk distance (6MWD), incremental exercise test, modified Medical Research Council (MRC) dyspnoea score and Chronic Respiratory Disease Questionnaire (CRDQ) were performed at baseline, following intervention and at 6 months. RESULTS: 80% of subjects completed the exercise programme and no adverse events were recorded. The 6MWD increased following training (mean difference to control 35 m, 95% CI 6 to 64 m). A significant reduction in MRC score was observed (0.7 points, 95% CI 0.1 to 1.3) along with improvements in dyspnoea (p = 0.04) and fatigue (p<0.01) on the CRDQ. There was no change in peak oxygen uptake; however, exercise training reduced heart rate at maximum isoworkload (p = 0.01). There were no significant differences in response between those with and without IPF. After 6 months there were no differences between the training and control group for any outcome variable. CONCLUSIONS: Exercise training improves exercise capacity and symptoms in patients with ILD, but these benefits are not sustained 6 months following intervention.

High numerical aperture vectorial imaging in coherent optical microscopes.

Imaging systems are typically partitioned into three components: focusing of incident light, scattering of incident light by an object and imaging of scattered light. We present a model of high Numerical Aperture (NA) imaging systems which differs from prior models as it treats each of the three components of the imaging system rigorously. It is well known that when high NA lenses are used the imaging system must be treated with vectorial analysis. This in turn requires that the scattering of light by the object be calculated rigorously according to Maxwell's equations. Maxwell's equations are solvable analytically for only a small class of scattering objects necessitating the use of rigorous numerical methods for the general case. Finally, rigorous vectorial diffraction theory and focusing theory are combined to calculate the image of the scattered light. We demonstrate the usefulness of the model through examples.

Calculation of the image of an arbitrary vectorial electromagnetic field.

In order to rigorously calculate the image of a scattered field, it must be propagated into the far-field before vectorial focusing theory is applied. This approach may become difficult when, for example, the scattering object is embedded in a stratified medium, requiring calculation of the appropriate Green's tensor. We present a method for calculating the image of an arbitrary vectorial field by decomposing the field into a superposition of magnetic-dipole waves. We show that this technique can significantly simplify the calculation of the image of arbitrary vectorial fields even when the field is known within a stratified medium. The technique is more computationally efficient than existing methods however we also show that the method retains accuracy.

Bacterial toxins activating Rho GTPases.

The CNF1 toxin is produced by some uropathogenic (UPECs) andmeningitis-causing Escherichia coli strains. It belongs to a large family of bacterial virulence factors and toxins modifying cellular regulators of the actin cytoskeleton, namely the Rho GTPases. CNF1 autonomously enters the host cell cytosol, where it catalyzes the constitutive activation of Rho GTPases by deamidation. This activation is, however, attenuated because of activated Rho protein ubiquitin-mediated proteasomal degradation. Both Rho protein activation and deactivation confer phagocytic properties on epithelial and endothelial cells, as well as epithelial cell motility and cell-cell junction dynamics. Transcriptome analysis using DNA microarray revealed that endothelial cells respond to high doses of CNF1 by launching a genetic program of host alarm. This host cell reaction to CNF1 intoxication also indicates that degradation of activated Rho proteins by the proteasome may lead to a lowering of the threshold of the intoxicated cell inflammatory response. These results are consistent with growing evidence that Rho proteins control the cell inflammatory responses. It is tempting to assume that Rho deregulation may participate in various immunological disorders also involved in cancer.

Toxins from anaerobic bacteria: specificity and molecular mechanisms of action.

Major advances have been made in the past five years in the identification of cellular targets of toxins produced by anaerobic bacteria. These targets include the vesicular membrane docking and fusion apparatus, the actin cytoskeleton, the signal transduction machinery and the cell membrane. The recent discovery that large clostridial toxins (Clostridium difficile A and B toxins, C. sordellii lethal and hemorrhagic toxins, and alpha C. novyi toxin) are monoglucosyltransferases, together with the establishment of the perfringolysin crystal structure, has led to new insights in the field of toxins from anaerobic bacteria.

Rapid sequence intubation in the emergency department: 5 year trends.

AIM: Airway management is a core aspect of emergency medicine. The technique of rapid sequence intubation (RSI) creates continuing debate between anaesthetists and emergency physicians in the UK, although similar complication rates for emergency department (ED) RSI have been shown for both specialties. This study examined prospectively collected data on every ED RSI performed in a university hospital in Glasgow over 5 years. METHODS: Data were prospectively recorded for every attempted RSI in the ED on a dedicated form (as used in previous studies) between January 1999 and December 2003. Immediate complications were specifically sought in the questionnaire, as was the immediate destination on leaving the ED. The chi2 test was used for categorical data. RESULTS: On average, 51 ED RSI were performed annually (range 42-60). Emergency physician RSI for trauma increased from 32% (7/22) in 1999 to 75% (21/28) in 2003 (chi2 = 9.32, df = 1, p = 0.002) and for non-trauma from 62% (18/29) in 1999 to 79% (23/29) in 2003 (chi2 = 2.08, df = 1, p = 0.15). Complication rates for emergency physician RSI decreased from 43% (3/7) to 14% (3/21) for trauma (chi2 = 2.55, df = 1, p = 0.11) and from 28% (5/18) to 4% (1/23) for non-trauma (chi2 = 4.44, df = 1, p = 0.035). This compares with mean complication rates for anaesthetists for trauma of 17% and for non-trauma of 22%. Incidence of hypotension decreased in all groups; however, oxygen desaturation is now the most common complication. The rate of ED RSI prior to computed tomography (CT) scans increased in both the trauma (79% v 42%; chi2 = 7.42, df = 1, p = 0.0065) and non-trauma (48% v 17%; chi2 = 5.85, df = 1, p = 0.016) groups. CONCLUSION: Emergency physician performed ED RSI is increasingly common but is not associated with overall higher numbers of RSIs being performed in the ED. Effective pre-oxygenation should be emphasised during training.

Alcoholic ketoacidosis.

Alcoholic ketoacidosis (AKA) is a common reason for investigation and admission of alcohol dependent patients in UK emergency departments. Although well described in international emergency medicine literature, UK emergency physicians rarely make the diagnosis of AKA. There is increasing evidence that rather than being benign and self limiting, AKA may be a significant cause of mortality in patients with alcohol dependence. This literature review discusses the history, characterisation, pathophysiology, diagnosis, and management of AKA.

Aeromedical retrieval to a university hospital emergency department in Scotland.

Rural and island areas of Scotland benefit from the availability of the Scottish Ambulance Service paramedic staffed helicopter for transfers and primary scene responses. There are a small number of patients who require advanced airway management, invasive procedures, or critical care interventions to stabilise them before transport to definitive care. At present these additional skills are provided on an ad hoc basis by senior medical staff drawn from intensive care and emergency medicine at the receiving hospitals. Given the potential difficulties of training paramedics to use these infrequently used skills it may be preferable to establish a formalised system to access suitably trained medical staff. This case series illustrates the clinical challenges and potential benefits of such a service and discusses the practicalities involved.

Dynamic gender-related differences in dichotic listening performance.

This experiment investigated dynamic gender-related differences in perceptual asymmetry (PA) in a dichotic task. Twenty right-handed males and 20 right-handed females performed a 200 trial directed attention dichotic listening task using consonant-vowel-consonant nonsense syllables. Men showed a greater right-ear advantage (REA) at the beginning of the test than did women. Over the course of the test the REA in men declined significantly (P < 0.001) whilst in females the REA showed a significant increase (P < 0.001). Thus by the end of the test the REA was greater in females than males. However, the reduced REA in males was entirely due to improved left-ear (LE) performance and the increased REA in females was due to improved right-ear (RE) performance. The change in PA in women is consistent with a dynamic improvement in left hemisphere (LH) syllable processing and in men a dynamic improvement in the transmission of information through the right hemisphere (RH) to the language processing areas in the LH.