Assessing lung aeration using ultrasound after birth in near-term lambs at risk of respiratory distress.

Background: Optimizing respiratory support after birth requires real-time feedback on lung aeration. We hypothesized that lung ultrasound (LUS) can accurately monitor the extent and progression of lung aeration after birth and is closely associated with oxygenation. Methods: Near-term (140 days gestation, term ∼147 days), spontaneously breathing lambs with normal (controls; n = 10) or elevated lung liquid levels (EL; n= 9) were delivered by Caesarean section and monitored for four hours after birth. LUS (Phillips CX50, L3-12 transducer) images and arterial blood gases were taken every 5-20 min. LUS images were analyzed both qualitatively (grading) and quantitatively (using the coefficient of variation of pixel intensity (CoV) to estimate the degree of lung aeration), which was correlated with the oxygen exchange capacity of the lungs (Alveolar-arterial difference in oxygen; AaDO2). Results: Lung aeration, measured using LUS, and the AaDO2 improved over the first 4 h after birth. The increase in lung aeration measured using CoV of pixel intensity, but not LUS grade, was significantly reduced in EL lambs compared to controls (p = 0.02). The gradual decrease in AaDO2 after birth was significantly correlated with increased lung aeration in both control (grade, r2 = 0.60, p < 0.0001; CoV, r2 = 0.54, p < 0.0001) and EL lambs (grade, r2 = 0.51, p < 0.0001; CoV, r2 = 0.44, p < 0.0001). Conclusions: LUS can monitor lung aeration and liquid clearance after birth in spontaneously breathing near-term lambs. Image analysis techniques (CoV) may be able detect small to moderate differences in lung aeration in conditions with lung liquid retention which are not readily identified using qualitative LUS grading.

Accurate measures of changes in regional lung air volumes from chest x-rays of small animals.

Objective. To develop a robust technique for calculating regional volume changes within the lung from x-ray radiograph sequences captured during ventilation, without the use of computed tomography (CT).Approach. This technique is based on the change in transmitted x-ray intensity that occurs for each lung region as air displaces the attenuating lung tissue.Main results. Lung air volumes calculated from x-ray intensity changes showed a strong correlation (R2= 0.98) against the true volumes, measured from high-resolution CT. This correlation enables us to accurately convert projected intensity data into relative changes in lung air volume. We have applied this technique to measure changes in regional lung volumes from x-ray image sequences of mechanically ventilated, recently-deceased newborn rabbits, without the use of CT.Significance. This method is suitable for biomedical research studies,enabling quantitative regional measurement of relative lung air volumes at high temporal resolution, and shows great potential for future clinical application.

Tomographic reconstruction using tilted Laue analyser-based X-ray phase-contrast imaging.

Analyser-based phase-contrast imaging (ABPCI) is a highly sensitive phase-contrast imaging method that produces high-contrast images of weakly absorbing materials. However, it is only sensitive to phase gradient components lying in the diffraction plane of the analyser crystal [i.e. in one dimension (1-D)]. In order to accurately account for and measure phase effects produced by the wavefield-sample interaction, ABPCI and other 1-D phase-sensitive methods must achieve 2-D phase gradient sensitivity. An inclined geometry method was applied to a Laue geometry setup for X-ray ABPCI through rotation of the detector and object about the optical axis. This allowed this traditionally 1-D phase-sensitive phase-contrast method to possess 2-D phase gradient sensitivity. Tomographic datasets were acquired over 360° of a multi-material phantom with the detector and sample tilted by 8°. The real and imaginary parts of the refractive index were reconstructed for the phantom.

DNA methylation across the genome in aged human skeletal muscle tissue and muscle-derived cells: the role of HOX genes and physical activity.

Skeletal muscle tissue demonstrates global hypermethylation with age. However, methylome changes across the time-course of differentiation in aged human muscle derived cells, and larger coverage arrays in aged muscle tissue have not been undertaken. Using 850K DNA methylation arrays we compared the methylomes of young (27 ± 4.4 years) and aged (83 ± 4 years) human skeletal muscle and that of young/aged heterogenous muscle-derived human primary cells (HDMCs) over several time points of differentiation (0, 72 h, 7, 10 days). Aged muscle tissue was hypermethylated compared with young tissue, enriched for; pathways-in-cancer (including; focal adhesion, MAPK signaling, PI3K-Akt-mTOR signaling, p53 signaling, Jak-STAT signaling, TGF-beta and notch signaling), rap1-signaling, axon-guidance and hippo-signalling. Aged cells also demonstrated a hypermethylated profile in pathways; axon-guidance, adherens-junction and calcium-signaling, particularly at later timepoints of myotube formation, corresponding with reduced morphological differentiation and reductions in MyoD/Myogenin gene expression compared with young cells. While young cells showed little alterations in DNA methylation during differentiation, aged cells demonstrated extensive and significantly altered DNA methylation, particularly at 7 days of differentiation and most notably in focal adhesion and PI3K-AKT signalling pathways. While the methylomes were vastly different between muscle tissue and HDMCs, we identified a small number of CpG sites showing a hypermethylated state with age, in both muscle tissue and cells on genes KIF15, DYRK2, FHL2, MRPS33, ABCA17P. Most notably, differential methylation analysis of chromosomal regions identified three locations containing enrichment of 6-8 CpGs in the HOX family of genes altered with age. With HOXD10, HOXD9, HOXD8, HOXA3, HOXC9, HOXB1, HOXB3, HOXC-AS2 and HOXC10 all hypermethylated in aged tissue. In aged cells the same HOX genes (and additionally HOXC-AS3) displayed the most variable methylation at 7 days of differentiation versus young cells, with HOXD8, HOXC9, HOXB1 and HOXC-AS3 hypermethylated and HOXC10 and HOXC-AS2 hypomethylated. We also determined that there was an inverse relationship between DNA methylation and gene expression for HOXB1, HOXA3 and HOXC-AS3. Finally, increased physical activity in young adults was associated with oppositely regulating HOXB1 and HOXA3 methylation compared with age. Overall, we demonstrate that a considerable number of HOX genes are differentially epigenetically regulated in aged human skeletal muscle and HDMCs and increased physical activity may help prevent age-related epigenetic changes in these HOX genes.

Auditing HIV Testing Rates across Europe: Results from the HIDES 2 Study.

European guidelines recommend the routine offer of an HIV test in patients with a number of AIDS-defining and non-AIDS conditions believed to share an association with HIV; so called indicator conditions (IC). Adherence with this guidance across Europe is not known. We audited HIV testing behaviour in patients accessing care for a number of ICs. Participating centres reviewed the case notes of either 100 patients or of all consecutive patients in one year, presenting for each of the following ICs: tuberculosis, non-Hodgkins lymphoma, anal and cervical cancer, hepatitis B and C and oesophageal candidiasis. Observed HIV-positive rates were applied by region and IC to estimate the number of HIV diagnoses potentially missed. Outcomes examined were: HIV test rate (% of total patients with IC), HIV test accepted (% of tests performed/% of tests offered) and new HIV diagnosis rate (%). There were 49 audits from 23 centres, representing 7037 patients. The median test rate across audits was 72% (IQR 32-97), lowest in Northern Europe (median 44%, IQR 22-68%) and highest in Eastern Europe (median 99%, IQR 86-100). Uptake of testing was close to 100% in all regions. The median HIV+ rate was 0.9% (IQR 0.0-4.9), with 29 audits (60.4%) having an HIV+ rate >0.1%. After adjustment, there were no differences between regions of Europe in the proportion with >0.1% testing positive (global p = 0.14). A total of 113 patients tested HIV+. Applying the observed rates of testing HIV+ within individual ICs and regions to all persons presenting with an IC suggested that 105 diagnoses were potentially missed. Testing rates in well-established HIV ICs remained low across Europe, despite high prevalence rates, reflecting missed opportunities for earlier HIV diagnosis and care. Significant numbers may have had an opportunity for HIV diagnosis if all persons included in IC audits had been tested.

Decoding the structure of granular and porous materials from speckled phase contrast X-ray images.

Imaging techniques for studying the structure of opaque, granular and porous materials are limited by temporal resolution and radiation dose. We present a technique for characterising the structure of such materials by decoding three dimensional structural information from single, propagation based phase contrast X-ray images. We demonstrate the technique by measuring the distribution of diameters of glass microspheres in packed samples. We also present synthetic data, which shows that our inverse method is stable and that accuracy is improved by phase contrast X-ray imaging. Compared to computed tomography, our technique has superior temporal resolution and lower radiation dose.

Single-exposure dual-energy-subtraction X-ray imaging using a synchrotron source.

Projection radiography of the chest has long been plagued by the presence of bony anatomy obscuring visibility of the lungs and heart. Dual-energy subtraction is a well known method for differentiating bone and soft tissue, but existing techniques are not ideally suited to dynamic imaging. Herein a new technique to address this problem is presented. The harmonic content of a monochromated X-ray beam is exploited, and two in-line detectors are used to perform single-exposure dual-energy imaging. Images of a phantom demonstrate the ability to both separate and quantitatively measure the thickness of constituent materials, whilst images of a mouse thorax demonstrate the ability to separate bone and soft tissue in a biological specimen. The technique is expected to improve the performance of dynamic lung imaging.

Determining particle size distributions from a single projection image.

Imaging techniques employed to measure the structure of granular, particulate and porous materials are limited by scale, temporal resolution and, for biological samples, radiation exposure. This paper describes a technique for determining the distribution of particle sizes in opaque samples, for particle volume fractions less than ten percent, using a single projection radiograph. The method is based on the derived property of the additivity of the particles' spatial autocorrelation function in projection images. Simulations and experiments demonstrate the ability to use this property to determine the distribution of particle sizes in a material.

Interface-specific x-ray phase retrieval tomography of complex biological organs.

We demonstrate interface-specific propagation-based x-ray phase retrieval tomography of the thorax and brain of small animals. Our method utilizes a single propagation-based x-ray phase-contrast image per projection, under the assumptions of (i) partially coherent paraxial radiation, (ii) a static object whose refractive indices take on one of a series of distinct values at each point in space and (iii) the projection approximation. For the biological samples used here, there was a 9-200 fold improvement in the signal-to-noise ratio of the phase-retrieved tomograms over the conventional attenuation-contrast signal. The ability to 'digitally dissect' a biological specimen, using only a single phase-contrast image per projection, will be useful for low-dose high-spatial-resolution biomedical imaging of form and biological function in both healthy and diseased tissue.

SMART lunch box intervention to improve the food and nutrient content of children's packed lunches: UK wide cluster randomised controlled trial.

BACKGROUND: Government standards are now in place for children's school meals but not for lunches prepared at home. The aim of this trial is to improve the content of children's packed lunches. METHODS: A cluster randomised controlled trial in 89 primary schools across the UK involving 1291 children, age 8-9 years at baseline. Follow-up was 12 months after baseline. A "SMART" lunch box intervention programme consisted of food boxes, bag and supporting materials. The main outcome measures were weights of foods and proportion of children provided with sandwiches, fruit, vegetables, dairy food, savoury snacks and confectionery in each packed lunch. Levels of nutrients provided including energy, total fat, saturated fat, protein, non-milk extrinsic sugar, sodium, calcium, iron, folate, zinc, vitamin A and vitamin C. RESULTS: Moderately higher weights of fruit, vegetables, dairy and starchy food and lower weights of savoury snacks were provided to children in the intervention group. Children in the intervention group were provided with slightly higher levels of vitamin A and folate. 11% more children were provided with vegetables/salad in their packed lunch, and 13% fewer children were provided with savoury snacks (crisps). Children in the intervention group were more likely to be provided with packed lunches meeting the government school meal standards. CONCLUSIONS: The SMART lunch box intervention, targeting parents and children, led to small improvements in the food and nutrient content of children's packed lunches. Further interventions are required to bring packed lunches in line with the new government standards for school meals. Current controlled trials ISRCTN77710993.

2D and 3D X-ray phase retrieval of multi-material objects using a single defocus distance.

A method of tomographic phase retrieval is developed for multi-material objects whose components each has a distinct complex refractive index. The phase-retrieval algorithm, based on the Transport-of-Intensity equation, utilizes propagation-based X-ray phase contrast images acquired at a single defocus distance for each tomographic projection. The method requires a priori knowledge of the complex refractive index for each material present in the sample, together with the total projected thickness of the object at each orientation. The requirement of only a single defocus distance per projection simplifies the experimental setup and imposes no additional dose compared to conventional tomography. The algorithm was implemented using phase contrast data acquired at the SPring-8 Synchrotron facility in Japan. The three-dimensional (3D) complex refractive index distribution of a multi-material test object was quantitatively reconstructed using a single X-ray phase-contrast image per projection. The technique is robust in the presence of noise, compared to conventional absorption based tomography.

Dynamic measures of regional lung air volume using phase contrast x-ray imaging.

Phase contrast x-ray imaging can provide detailed images of lung morphology with sufficient spatial resolution to observe the terminal airways (alveoli). We demonstrate that quantitative functional and anatomical imaging of lung ventilation can be achieved in vivo using two-dimensional phase contrast x-ray images with high contrast and spatial resolution (<100 microm) in near real time. Changes in lung air volume as small as 25 microL were calculated from the images of term and preterm rabbit pup lungs (n = 28) using a single-image phase retrieval algorithm. Comparisons with plethysmography and computed tomography showed that the technique provided an accurate and robust method of measuring total lung air volumes. Furthermore, regional ventilation was measured by partitioning the phase contrast images, which revealed differences in aeration for different ventilation strategies.

Analyser-based phase contrast image reconstruction using geometrical optics.

Analyser-based phase contrast imaging can provide radiographs of exceptional contrast at high resolution (<100 microm), whilst quantitative phase and attenuation information can be extracted using just two images when the approximations of geometrical optics are satisfied. Analytical phase retrieval can be performed by fitting the analyser rocking curve with a symmetric Pearson type VII function. The Pearson VII function provided at least a 10% better fit to experimentally measured rocking curves than linear or Gaussian functions. A test phantom, a hollow nylon cylinder, was imaged at 20 keV using a Si(1 1 1) analyser at the ELETTRA synchrotron radiation facility. Our phase retrieval method yielded a more accurate object reconstruction than methods based on a linear fit to the rocking curve. Where reconstructions failed to map expected values, calculations of the Takagi number permitted distinction between the violation of the geometrical optics conditions and the failure of curve fitting procedures. The need for synchronized object/detector translation stages was removed by using a large, divergent beam and imaging the object in segments. Our image acquisition and reconstruction procedure enables quantitative phase retrieval for systems with a divergent source and accounts for imperfections in the analyser.

Phase contrast X-ray imaging of mice and rabbit lungs: a comparative study.

The significant degree of X-ray phase contrast created by air-tissue interfaces, coupled with the poor radiographic contrast of conventional chest radiographs, makes the inflated lung an ideal candidate for investigating the potential diagnostic improvement afforded by phase contrast X-ray imaging. In small animals these methods highlight the lung airways and lobe boundaries and reveal the lung tissue as a speckled intensity pattern not seen in other soft tissues. We have compared analyser-based and propagation-based phase contrast imaging modalities, together with conventional radiographic imaging, to ascertain which technique shows the greatest image enhancement for various lung sizes. The conventional radiographic image of a mouse was obtained on a Siemens Nova 3000 mammography system, whilst phase contrast images of mice and rabbit chests were acquired at the medical imaging beamline (20B2) at the SPring-8 synchrotron radiation research facility in Japan. For mice aged 1 day, 1 week and 1 month old it was determined that analyser-based imaging showed the greatest overall image contrast, however, for an adult rabbit both techniques yielded excellent contrast. The success of these methods in creating high quality images for rabbit lungs raises the possibility of improving human lung imaging using phase contrast techniques.

Dynamic imaging of the lungs using x-ray phase contrast.

High quality real-time imaging of lungs in vivo presents considerable challenges. We demonstrate here that phase contrast x-ray imaging is capable of dynamically imaging the lungs. It retains many of the advantages of simple x-ray imaging, whilst also being able to map weakly absorbing soft tissues based on refractive index differences. Preliminary results reported herein show that this novel imaging technique can identify and locate airway liquid and allows lung aeration in newborn rabbit pups to be dynamically visualized.

On the origin of speckle in x-ray phase contrast images of lung tissue.

Phase contrast x-ray imaging of small animal lungs reveals a speckled intensity pattern not seen in other tissues, making the lungs highly visible in comparison to other organs. Although bearing a superficial resemblance to alveoli, the cause of this speckle has not been established. With a view to determining the mechanism for the formation of speckle, this paper details the results of propagation-based phase contrast experiments performed on mice lungs, together with packed glass microspheres used to emulate lung tissue. These experimental studies are compared to numerical simulations, based on wave propagation techniques. We find that speckle arises from focusing effects, with multiple alveoli acting as aberrated compound refractive lenses. Both experiments and modelling suggest that this speckle-formation phenomenon may lead to better screening methods for human lungs than conventional radiography.

R(+)-8-OH-DPAT, a 5-HT1A receptor agonist, inhibits amphetamine-induced dopamine release in rat striatum and nucleus accumbens.

Systemic administration of R(+)-8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin), a selective serotonin (5-hydroxy-tryptamine, 5-HT)1A receptor agonist (25, 50, and 100 mu g/kg s.c.), administered 30 min prior to d-amphetamine, significantly inhibited the d-amphetamine sulfate (1.0 mg/kg s.c.)-induced increase in extracellular dopamine levels in the striatum and nucleus accumbens of freely moving rats, as determined by in vivo microdialysis. The ability of R(+)-8-OH-DPAT (50 mu g/kg s.c.) to inhibit d-amphetamine sulfate (1.0 mg/kg s.c.)-induced increase in extracellular dopamine levels was abolished by WAY 100,635 (n-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-n-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride), a selective 5-HT1A receptor antagonist (100 mu g/kg s.c.), administered 5 min prior to R(+)-8-OH-DPAT in both regions. These results indicate that the 5-HT1A receptor may exert an inhibitory effect on amphetamine-induced dopamine release.

An urban epidemic of North American blastomycosis.

Five culturally proved cases of blastomycosis occurred in a 9-month period during 1974 and 1975 in a western suburb of Chicago. All patients lived within a 1-mile radius of the center of Westmont, Ill. (population, 12,000). Three of these patients lived in adjacent buildings in the same apartment complex. None of the patients had significant outdoor exposure. Dust from a nearby construction site was postulated as a possible common source, although soil cultures from the area were negative. This is the third chronologic epidemic of the blastomycosis; a fourth one has been reported. It is the only outbreak to occur in a major metropolitan area.