bluuebunny/crossref_metadata_2025_split huggingface dataset:
Occult H. pylori infection partially explains ‘false‐positive’ results of 13 C‐urea breath test
Authors: Ramírez-Lázaro María J , Lario Sergio , Calvet Xavier , Sánchez-Delgado Jordi , Montserrat Antònia , Quílez Elisa M , Casalots Alex , Suarez David , Campo Rafel , Brullet Enric , Junquera Félix , Sanfeliu Isabel , Segura Ferran 
Published: March 2015

BackgroundIn a previous study, UBiT‐100 mg, (Otsuka, Spain), a commercial 13 C‐urea breath test omitting citric acid pre‐treatment, had a high rate of false‐positive results; however, it is possible that UBiT detected low‐density ‘occult’ infection missed by other routine reference tests. We aimed to validate previous results in a new cohort and to rule out the possibility that false‐positive UBiT were due to an ‘occult’ infection missed by reference tests.MethodsDyspeptic patients (n = 272) were prospectively enrolled and UBiT was performed, according to the manufacturer's recommendations. Helicobacter pylori infection was determined by combining culture, histology and rapid urease test results. We calculated UBiT sensitivity, specificity, positive and negative predictive values (with 95% CI). In addition, we evaluated ‘occult’ H. pylori infection using two previously‐validated polymerase chain reaction (PCR) methods for urease A (UreA) and 16 S sequences in gastric biopsies. We included 44 patients with a false‐positive UBiT, and two control groups of 25 patients each, that were positive and negative for all H. pylori tests.ResultsUBiT showed a false‐positive rate of 17%, with a specificity of 83%. All the positive controls and 12 of 44 patients (27%) with false‐positive UBiT were positive for all two PCR tests; by contrast, none of our negative controls had two positive PCR tests.ConclusionsUBiT suffers from a high rate of false‐positive results and sub‐optimal specificity, and the protocol skipping citric acid pre‐treatment should be revised; however, low‐density ‘occult’ H. pylori infection that was undetectable by conventional tests accounted for around 25% of the ‘false‐positive’ results.
A combined antral and corpus rapid urease testing protocol can increase diagnostic accuracy despite a low prevalence of Helicobacter pylori infection in patients undergoing routine gastroscopy
Authors: Parihar Vikrant , Holleran Grainne , Hall Barry , Brennan Denise , Crotty Paul , McNamara Deirdre 
Published: March 2015

BackgroundThe effects of an increased risk of sampling error and the lower prevalence of Helicobacter pylori infection on the diagnostic accuracy of standard invasive tests needs to be considered. Despite evidence of enhanced yield with additional biopsies, combined Rapid Urease Tests (RUTs) have not been widely adopted. We aimed to compare the diagnostic efficacy of a combined antral and corpus rapid urease test (RUT) to a single antral RUT in a low prevalence cohort.MethodsBetween August 2013 and April 2014 adult patients undergoing a scheduled gastroscopy were prospectively recruited. At endoscopy biopsies were taken and processed for single and combined RUTs, histology and culture using standard techniques. Infection was defined by positive culture or detection of Helicobacter like organisms on either antral or corpus samples.ResultsIn all 123 patients were recruited. H. pylori prevalence was low at 36%, n  = 44. There was a significant difference in positivity between single and combined RUTs, 20% (n  = 25) versus 30% (n  = 37), p  = 0.0094, (95% CI 0.15–0.04). The number needed to treat (NNT) for an additional diagnosis of infection using a combined versus a single RUT is 4 (95% CI 2.2–11). The only factor associated with a reduction in RUT yield was regular proton pump inhibitor (PPI) use. Overall the sensitivity, specificity, positive and negative predictive value for any RUT test was 84%, 100%, 100% and 92% respectively.ConclusionOur data suggests taking routine antral and corpus biopsies in conjunction with a combined RUT appears to optimizing H. pylori detection and overcome sampling error in a low prevalence population.
Adolescents’ perception of substance use and factors influencing its use: a qualitative study in Abu Dhabi
Authors: Alhyas Layla , Al Ozaibi Naseeba , Elarabi Hisham , El-Kashef Ahmed , Wanigaratne Shamil , Almarzouqi Amna , Alhosani Ayesha , Al Ghaferi Hamad 
Published: March 2015

Summary Objective The objective of this article is to gain a deeper understanding of the attitudes and perceptions of adolescents in the United Arab Emirates regarding substance and to identify factors that, in their view, may influence the risk of substance use and suggest possible interventions. Design This was a qualitative study that used a focus group approach. Setting The study was carried out in Abu Dhabi, United Arab Emirates. Participants Male and female teenagers aged 13-18 years residing in the emirate of Abu Dhabi. Main outcome measures Adolescents’ awareness of substance use, patterns of use and associated harm; Adolescents' perceptions about the factors associated with substance use. Results Six focus groups were carried out, and a total of 41 adolescents (20 males and 21 females) participated. Data analysis identified three main themes: (1) adolescents’ awareness of substance use and associated harm; (2) gender role and image and (3) perceived factors affecting substance use among adolescents. Knowledge of substances and related consequences of use varied between groups but was compatible with participants’ age and school years. Factors that participants believed influenced substance use were classified into: (1) parent–adolescent relationship, (2) peer pressure, (3) substance accessibility, (4) religiosity and (5) others. Many factors were believed to increase the risk of substance use among adolescents such as peer pressure, inadequate knowledge of the harmful consequences of drug use, family-related factors (e.g. low monitoring and poor parent–adolescents relationship), affordability and availability of substances, boredom and affluence. On the other hand, religiosity was as a shield against substance use, especially alcohol. Other identified protective factors included carrying out schools- and communities-based educational campaigns, enhancing social workers’ ability to raise awareness and detect early signs of addiction and implementing CCTV systems in schools. Conclusions The study was successful in exploring adolescents’ awareness of substances and associated harm to health from their use. Also, it identifies a number of risk and protective factors based on the perceptions of a group of adolescents residing in the United Arab Emirates. Such factors can guide the planning, designing and implementing of prevention programmes that focus on raising awareness about the harms of substance use. The study findings would suggest that multifactorial prevention programmes that address social norms, gender role and image, and incorporate drug policy, religion, family and school would be more effective and may have better protective outcomes.
Evaluation of the effect of ambrisentan on digital microvascular flow in patients with systemic sclerosis using laser Doppler perfusion imaging: a 12-week randomized double-blind placebo controlled trial
Authors: Bose Nilanjana , Bena James , Chatterjee Soumya 
Published: March 2015

Abstract
Introduction
In patients with systemic sclerosis (SSc), digital ischemia results from an occlusive microvasculopathy that may not respond adequately to conventional vasodilators. Endothelin receptor antagonists can potentially modify the fibroproliferative vascular remodeling in SSc, and hence their use may be justified in the management of digital ischemia. The objective of this clinical trial was to evaluate the effect of ambrisentan, a selective endothelin type A receptor antagonist, on microvascular blood flow in patients with limited systemic sclerosis (SSc) using laser Doppler perfusion imaging (LDPI).

Methods
In this randomized, double-blind, placebo controlled study we enrolled 20 patients with limited SSc. Fifteen patients received ambrisentan 5 mg daily for one month and then 10 mg daily for two months, and five received a placebo. There were three visits: weeks 0 (baseline), one and 12. Three patient-oriented questionnaires were completed at each visit: Scleroderma-Health Assessment Questionnaire (S-HAQ), Raynaud Condition Score (RCS), and Pain-Visual Analog Scale (P-VAS). At each visit, LDPI was used to obtain three blood flow readings involving regions of interest in second to fifth fingers of the non-dominant hand at room temperature (25°C) and after cooling (10°C) for two minutes.

Results
There were 16 females (80%); mean age was 50 years. None of the differences in blood flow (as measured by LDPI) were significant both at baseline and after cooling. However, patients in the ambrisentan group showed significant improvement in the patient-oriented outcomes: RCS (P = 0.001) and S-HAQ score (P = 0.005).

Conclusions
This pilot study did not show evidence of significant increase in digital blood flow over time; however, there was an improvement in RCS and S-HAQ score. We conclude that continuous use of ambrisentan for three months does not seem to significantly improve digital blood flow in SSc patients.

Trial registration
Clinicaltrials.gov NCT01072669. Registered 19 February 2010.
Rapid resistivity imaging for marine controlled-source electromagnetic surveys with two transmitter polarizations: An application to the North Alex mud volcano, West Nile Delta
Authors: Swidinsky Andrei , Hölz Sebastian , Jegen Marion 
Published: March 2015

To image the internal resistivity structure of the North Alex mud volcano offshore Egypt, the marine electromagnetics group at the Helmholtz Centre for Ocean Research Kiel (GEOMAR) developed and conducted a novel transient marine controlled-source electromagnetic experiment. The system, which was specifically developed to image the mud volcano, is also generally suitable for surveys of other small seafloor targets, such as gas-hydrate reservoirs, fluid-flow features, and submarine massive-sulfide deposits. An electric bipole antenna is set down by a remotely operated vehicle on the seafloor sequentially in two perpendicular polarizations at each transmission station. Two orthogonal horizontal electric field components are recorded on the seabed by an array of independently deployed nodal receivers (RXs). With two transmitter polarizations, the unique acquisition geometry of the system provides a very rich data set. However, for this geometric setup, conventional marine electromagnetic interpretation schemes (such as normalized magnitude variation with offset plots) have been difficult to implement. We have developed a simple imaging technique, which can be used for a first-step mapping of seafloor apparent resistivity with the GEOMAR system. Images can be produced in just a few minutes on a regular laptop computer, and the robustness of the approach was demonstrated using two synthetic data sets from simple seafloor models. The method was then applied to the real data acquired at the North Alex mud volcano in 2008. Results found increased apparent sediment resistivities of up to 4 Ωm near the center of the mud volcano occurring at source-RX offsets greater than 500 m, which mapped to apparent depths of greater than 150 m. This may be caused by large quantities of free gas or freshwater in the sediment pore space.
Time-lapse seismic performance of a sparse permanent array: Experience from the Aquistore CO2 storage site
Authors: White Don J. , Roach Lisa A. N. , Roberts Brian 
Published: March 2015

A sparse areal permanent array of buried geophones was deployed at the Aquistore [Formula: see text] storage site in Saskatchewan, Canada. The purpose of this array is to facilitate 4D seismic monitoring of [Formula: see text] that is to be injected to the deep subsurface. Use of a sparse buried array is designed to improve the repeatability of time-lapse data and to economize the monitoring effort. Prior to the start of [Formula: see text] injection, two 3D dynamite seismic surveys were acquired in March 2012 and May 2013 using the permanent array. The objective of acquiring these data was to allow an assessment of the data repeatability and overall performance of the permanent array. A comparison of the raw data from these surveys and with a conventional high-resolution 3D vibroseis survey demonstrated that (1) the signal-to-noise ratio for the buried geophones was increased by 6–7 dB relative to surface-deployed geophones and by an additional 20 dB for dynamite relative to a vibroseis source, (2) the use of buried sensors and sources at this site did not appear to be significantly degraded by the effects of ghosting, (3) repeatability for the permanent array data was excellent with a mean normalized root-mean-square (nrms) value of 57% for the raw baseline-monitor difference, (4) the variance of nrms values was higher for shot gathers (18%) compared with receiver gathers (7%), and (5) the raw data repeatability was a factor of three improved over that of comparable surface-geophone data acquired at a nearby location. The use of a sparse buried permanent array at the Aquistore site has demonstrably achieved a reduction in ambient noise levels and overall enhanced data repeatability, both of which are keys to successful 4D seismic monitoring.
The Impact of Diabetes and Diabetes Medications on Bone Health
Authors: Gilbert Matthew P. , Pratley Richard E. 
Published: March 2015

Abstract
Patients with type 2 diabetes mellitus (T2DM) have an increased risk of fragility fractures despite increased body weight and normal or higher bone mineral density. The mechanisms by which T2DM increases skeletal fragility are unclear. It is likely that a combination of factors, including a greater risk of falling, regional osteopenia, and impaired bone quality, contributes to the increased fracture risk. Drugs for the treatment of T2DM may also impact on the risk for fractures. For example, thiazolidinediones accelerate bone loss and increase the risk of fractures, particularly in older women. In contrast, metformin and sulfonylureas do not appear to have a negative effect on bone health and may, in fact, protect against fragility fracture. Animal models indicate a potential role for incretin hormones in bone metabolism, but there are only limited data on the impact of dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 agonists on bone health in humans. Animal models also have demonstrated a role for amylin in bone metabolism, but clinical trials in patients with type 1 diabetes with an amylin analog (pramlintide) have not shown a significant impact on bone metabolism. The effects of insulin treatment on fracture risk are inconsistent with some studies showing an increased risk and others showing no effect. Finally, although there is limited information on the latest class of medications for the treatment of T2DM, the sodium-glucose co-transporter-2 inhibitors, these drugs do not seem to increase fracture risk. Because diabetes is an increasingly common chronic condition that can affect patients for many decades, further research into the effects of agents for the treatment of T2DM on bone metabolism is warranted. In this review, the physiological mechanisms and clinical impact of diabetes treatments on bone health and fracture risk in patients with T2DM are described.
Bat flight: aerodynamics, kinematics and flight morphology
Authors: Hedenström Anders , Johansson L. Christoffer 
Published: March 2015

ABSTRACT
Bats evolved the ability of powered flight more than 50 million years ago. The modern bat is an efficient flyer and recent research on bat flight has revealed many intriguing facts. By using particle image velocimetry to visualize wake vortices, both the magnitude and time-history of aerodynamic forces can be estimated. At most speeds the downstroke generates both lift and thrust, whereas the function of the upstroke changes with forward flight speed. At hovering and slow speed bats use a leading edge vortex to enhance the lift beyond that allowed by steady aerodynamics and an inverted wing during the upstroke to further aid weight support. The bat wing and its skeleton exhibit many features and control mechanisms that are presumed to improve flight performance. Whereas bats appear aerodynamically less efficient than birds when it comes to cruising flight, they have the edge over birds when it comes to manoeuvring. There is a direct relationship between kinematics and the aerodynamic performance, but there is still a lack of knowledge about how (and if) the bat controls the movements and shape (planform and camber) of the wing. Considering the relatively few bat species whose aerodynamic tracks have been characterized, there is scope for new discoveries and a need to study species representing more extreme positions in the bat morphospace.
Coordination between catch connective tissue and muscles through nerves in the spine joint of the sea urchin Diadema setosum
Authors: Motokawa Tatsuo , Fuchigami Yoshiro 
Published: March 2015

ABSTRACT
Echinoderms have catch connective tissues that change their stiffness as a result of nervous control. The coordination between catch connective tissue and muscles was studied in the spine joint of the sea urchin Diadema setosum. Spine joints are equipped with two kinds of effector: spine muscles and a kind of catch connective tissue, which is called the catch apparatus (CA). The former is responsible for spine movements and the latter for maintenance of spine posture. Diadema show a shadow reaction in which they wave spines when a shadow falls on them, which is a reflex involving the radial nerves. Dynamic mechanical tests were performed on the CA in a joint at which the muscles were severed so as not to interfere with the mechanical measurements. The joint was on a piece of the test that contained other spines and a radial nerve. Darkening of the preparation invoked softening of the CA and spine waving (the shadow reaction). Electrical stimulation of the radial nerve invoked a similar response. These responses were abolished after the nerve pathways from the radial nerve to spines had been cut. A touch applied to the CA stiffened it and the adjacent spines inclined toward the touched CA. A touch to the base of the adjacent spine softened the CA and the spines around the touched spine inclined towards it. The softening of the CA can be interpreted as a response that reduces the resistance of the ligaments to spine movements. Our results clearly show coordination between catch connective tissue and muscles through nerves.
Comparison of Structural and Electrical Characteristics between Tetrabenzoporphyrin- and Phthalocyanine-based Charge-transfer Complexes
Authors: Nishi Miki , Matsuda Masaki , Hoshino Norihisa , Akutagawa Tomoyuki 
Published: March 2015

Abstract
A charge-transfer complex based on axially CN-substituted iron tetrabenzoporphyrin has been fabricated. X-ray structure analysis reveals that the differences in the distances and angles around the meso positions between tetrabenzoporphyrin and phthalocyanine are substantial between the porphin and porphyrazine frameworks. Electrical transport measurements reveal semiconducting behavior with higher activation energy due to the reduction in π–π overlapping, compared to an isostructural phthalocyanine complex.
Musculoskeletal dysfunction in chronic obstructive pulmonary disease (COPD): An observational study
Authors: Heneghan Nicola , Adab Peymane , Jackman Sarah , Balanos George 
Published: March 2015

Background/Aims: Chronic obstructive pulmonary disease (COPD) is widely recognised as a multi-system disease that extends beyond the lung and can further impair functional capacity, including that of the musculoskeletal system. While it has been reported that these changes may contribute to exercise limitation and disability, there has been little research to describe the nature and extent of changes in the musculoskeletal system. Therefore, the aim of this study was to examine differences in posture, joint mobility and muscle sensitivity in subjects with COPD compared with a matched group of healthy subjects. A secondary aim was to explore whether a relationship exists between pulmonary function and musculoskeletal changes. Finally, the data were used to evaluate whether an association exists between cervicothoracic posture, joint mobility and muscle sensitivity, and having diagnosed COPD. Methods: A prospective observational study was reported in accordance with Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. Participants with stable COPD (n=33; mean±SD age: 67 ± 9 years; FEV1% predicted: 50.94 ±19.40%) and age-matched controls (n=55; mean±SD age: 67 ± 6 years; FEV1% predicted: 104.53 ±16.86%) were recruited from primary and secondary care sources. Pulmonary function and performance-based outcome measures (predictors) included posture, spinal joint mobility, and accessory respiratory muscle sensitivity. Sociodemographic data and confounding variables were assessed using questionnaires and performance-based measures. Results: Reduced thoracic (p<0.001, 95%CI −21.64, −8.86) and cervical spine rotation (p=0.01, 95%CI −25.57, −3.33), altered cervicothoracic posture and heightened sensitivity in accessory muscles (p=0.01, 95% CI −601.81,−97.31) of respiration were found in the COPD population. Reduced thoracic axial rotation and altered neck posture were associated with poorer pulmonary function (p<0.05) and having diagnosed COPD, with odds ratios of 0.90 (0.84, 0.97) and 1.15 (1.02, 1.29), respectively. Conclusions: This is the first study to examine musculoskeletal changes in patients with COPD. The results show that musculoskeletal changes are evident in the cervicothoracic region and may contribute to exercise limitation and disability reported in this patient population.