bluuebunny/crossref_metadata_2025 huggingface dataset:
Flyway structure in the circumpolar greater white‐fronted goose
Authors: Wilson Robert E. , Ely Craig R. , Talbot Sandra L.
Published: July 2018

Dispersal and migratory behavior are influential factors in determining how genetic diversity is distributed across the landscape. In migratory species, genetic structure can be promoted via several mechanisms including fidelity to distinct migratory routes. Particularly within North America, waterfowl management units have been delineated according to distinct longitudinal migratory flyways supported by banding data and other direct evidence. The greater white‐fronted goose (Anser albifrons) is a migratory waterfowl species with a largely circumpolar distribution consisting of up to six subspecies roughly corresponding to phenotypic variation. We examined the rangewide population genetic structure of greater white‐fronted geese using mtDNA control region sequence data and microsatellite loci from 23 locales across North America and Eurasia. We found significant differentiation in mtDNA between sampling locales with flyway delineation explaining a significant portion of the observed genetic variation (~12%). This is concordant with band recovery data which shows little interflyway or intercontinental movements. However, microsatellite loci revealed little genetic structure suggesting a panmictic population across most of the Arctic. As with many high‐latitude species, Beringia appears to have played a role in the diversification of this species. A common Beringian origin of North America and Asian populations and a recent divergence could at least partly explain the general lack of structure at nuclear markers. Further, our results do not provide strong support for the various taxonomic proposals for this species except for supporting the distinctness of two isolated breeding populations within Cook Inlet, Alaska (A. a. elgasi) and Greenland (A. a. flavirostris), consistent with their subspecies status.
Changing environmental gradients over forty years alter ecomorphological variation in Guadalupe Bass Micropterus treculii throughout a river basin
Authors: Pease Jessica E. , Grabowski Timothy B. , Pease Allison A. , Bean Preston T.
Published: July 2018

Understanding the degree of intraspecific variation within and among populations is a key aspect of predicting the capacity of a species to respond to anthropogenic disturbances. However, intraspecific variation is usually assessed at either limited temporal, but broad spatial scales or vice versa, which can make assessing changes in response to long‐term disturbances challenging. We evaluated the relationship between the longitudinal gradient of changing flow regimes and land use/land cover patterns since 1980 and morphological variation of Guadalupe Bass Micropterus treculii throughout the Colorado River Basin of central Texas. The Colorado River Basin in Texas has experienced major alterations to the hydrologic regime due to changing land‐ and water‐use patterns. Historical collections of Guadalupe Bass prior to rapid human‐induced change present the unique opportunity to study the response of populations to varying environmental conditions through space and time. Morphological differentiation of Guadalupe Bass associated with temporal changes in flow regimes and land use/land cover patterns suggests that they are exhibiting intraspecific trait variability, with contemporary individuals showing increased body depth, in response to environmental alteration through time (specifically related to an increase in herbaceous land cover, maximum flows, and the number of low pulses and high pulses). Additionally, individuals from tributaries with increased hydrologic alteration associated with urbanization or agricultural withdrawals tended to have a greater distance between the anal and caudal fin. These results reveal trait variation that may help to buffer populations under conditions of increased urbanization and sprawl, human population growth, and climate risk, all of which impose novel selective pressures, especially on endemic species like Guadalupe Bass. Our results contribute an understanding of the adaptability and capacity of an endemic population to respond to expected future changes based on demographic or climatic projection.
From dispersal to predation: A global synthesis of ant–seed interactions
Authors: Penn Hannah J. , Crist Thomas O.
Published: July 2018

Ant–seed interactions take several forms, including dispersal, predation, and parasitism, whereby ants consume seed appendages without dispersal of seeds. We hypothesized that these interaction outcomes could be predicted by ant and plant traits and habitat, with outcomes falling along a gradient of cost and benefit to the plant. To test this hypothesis, we conducted a global literature review and classified over 6,000 pairs of ant–seed interactions from 753 studies across six continents. Linear models showed that seed and ant size, habitat, and dispersal syndrome were the most consistent predictors. Predation was less likely than parasitism and seed dispersal among myrmecochorous plants. A classification tree of the predicted outcomes from linear models revealed that dispersal and predation formed distinct categories based on habitat, ant size, and dispersal mode, with parasitism outcomes forming a distinct subgroup of predation based on seed size and shape. Multiple correspondence analysis indicated some combinations of ant genera and plant families were strongly associated with particular outcomes, whereas other ant–seed combinations were much more variable. Taken together, these results demonstrate that ant and plant traits are important overall predictors of potential seed fates in different habitat types.
Unexpected prey of juvenile spotted scat (Scatophagus argus) near a wharf: The prevalence of fouling organisms in stomach contents
Authors: Lin Xianzhi , Hu Simin , Liu Sheng , Huang Hui
Published: July 2018

A knowledge of fish diets can contribute to revealing the trophic role and ecological function of species in aquatic ecosystems. At present, however, there are no efficient or comprehensive methods for analyzing fish diets. In this study, we investigated the diets of juvenile Scatophagus argus collected near a wharf in Daya Bay, China, by dissection and high‐throughput sequencing (HTS) using the 18S rDNA V4 region. Microscopy disclosed large amounts of bryozoans and unrecognizable detritus. In contrast, HTS analysis indicated that the fish diets were considerably more diverse than visual inspection suggested. After eliminating fish sequences, approximately 17,000 sequences from taxa in nine phyla (Ciliophora, Bryozoa, Annelida, Bacillariophyta, Chlorophyta, Arthropoda, Dinoflagellata, Tunicata, and Phaeophyta) were identified from the analysis of stomach contents. Twenty‐one food categories were identified, most of which (95.2%) were benthic fouling organisms that could easily be collected around wharfs. These consisted of bryozoans (31.9%), ciliates (45.7%), polychaetes (14.6%), and green algae (3.0%). Therefore, to adapt to anthropogenic habitat modification, the fish had probably shifted from planktonic to benthic feeding. The prevalence of fouling organisms in the stomachs of juvenile S. argus indicates that the fish have responded to habitat changes by widening their food spectrum. This adaptation may have increased their chances of survival. The fouling organisms that inhabit highly perturbed coastal ecosystems could represent a food source for animals at higher trophic levels. Our results accordingly suggest that human activity might significantly influence fish feeding behavior and material transfer along the food chain.
Root exudation rate as functional trait involved in plant nutrient‐use strategy classification
Authors: Guyonnet Julien P. , Cantarel Amélie A. M. , Simon Laurent , Haichar Feth el Zahar
Published: July 2018

Plants adopt a variety of life history strategies to succeed in the Earth's diverse environments. Using functional traits which are defined as “morphological, biochemical, physiological, or phonological” characteristics measurable at the individual level, plants are classified according to their species’ adaptative strategies, more than their taxonomy, from fast growing plant species to slower‐growing conservative species. These different strategies probably influence the input and output of carbon (C)‐resources, from the assimilation of carbon by photosynthesis to its release in the rhizosphere soil via root exudation. However, while root exudation was known to mediate plant‐microbe interactions in the rhizosphere, it was not used as functional trait until recently. Here, we assess whether root exudate levels are useful plant functional traits in the classification of plant nutrient‐use strategies and classical trait syndromes? For this purpose, we conducted an experiment with six grass species representing along a gradient of plant resource‐use strategies, from conservative species, characterized by low biomass nitrogen (N) concentrations and a long lifespans, to exploitative species, characterized by high rates of photosynthesis and rapid rates of N acquisition. Leaf and root traits were measured for each grass and root exudate rate for each planted soil sample. Classical trait syndromes in plant ecology were found for leaf and root traits, with negative relationships observed between specific leaf area and leaf dry matter content or between specific root length and root dry matter content. However, a new root trait syndrome was also found with root exudation levels correlating with plant resource‐use strategy patterns, specifically, between root exudation rate and root dry matter content. We therefore propose root exudation rate can be used as a key functional trait in plant ecology studies and plant strategy classification.
Rainfall seasonality and drought performance shape the distribution of tropical tree species in Ghana
Authors: Amissah Lucy , Mohren Godefridus M. J. , Kyereh Boateng , Agyeman Victor K. , Poorter Lourens
Published: July 2018

Tree species distribution in lowland tropical forests is strongly associated with rainfall amount and distribution. Not only plant water availability, but also irradiance, soil fertility, and pest pressure covary along rainfall gradients. To assess the role of water availability in shaping species distribution, we carried out a reciprocal transplanting experiment in gaps in a dry and a wet forest site in Ghana, using 2,670 seedlings of 23 tree species belonging to three contrasting rainfall distributions groups (dry species, ubiquitous species, and wet species). We evaluated seasonal patterns in climatic conditions, seedling physiology and performance (survival and growth) over a 2‐year period and related seedling performance to species distribution along Ghana's rainfall gradient. The dry forest site had, compared to the wet forest, higher irradiance, and soil nutrient availability and experienced stronger atmospheric drought (2.0 vs. 0.6 kPa vapor pressure deficit) and reduced soil water potential (−5.0 vs. −0.6 MPa soil water potential) during the dry season. In both forests, dry species showed significantly higher stomatal conductance and lower leaf water potential, than wet species, and in the dry forest, dry species also realized higher drought survival and growth rate than wet species. Dry species are therefore more drought tolerant, and unlike the wet forest species, they achieve a home advantage. Species drought performance in the dry forest relative to the wet forest significantly predicted species position on the rainfall gradient in Ghana, indicating that the ability to grow and survive better in dry forests and during dry seasons may allow species to occur in low rainfall areas. Drought is therefore an important environmental filter that influences forest composition and dynamics. Currently, many tropical forests experience increase in frequency and intensity of droughts, and our results suggest that this may lead to reduction in tree productivity and shifts in species distribution.
Optimization of tea‐leaf saponins water extraction and relationships between their contents and tea (Camellia sinensis) tree varieties
Authors: Yu Xiao‐Lan , He Yong
Published: July 2018

Resulting from the year‐on‐year increase in tea plantations and the saturated consumption of tea leaves, the relative overcapacity in China's tea‐leaf production appears. Discovering the new utilization of tea leaves is helpful to alleviate this phenomenon. The feasibility of extracting saponins from aged tea leaves was investigated and confirmed; three major variables in water extraction were optimized by Box‐Behnken designs. The significant variable found in Box‐Behnken designs, liquid–solid ratio, was went through single‐variable experiments for a more accurate optimization. Seventy‐five ml/g, 1 hr, and 80°C were optimal values and tea‐leaf saponins yield of tea tree variety Longjing 43 reached 12.19% ± 0.0030% after optimizations, higher than the yield of tea‐seed saponins from Camellia oleifera seed meals using the same extraction method (water extraction based on optimizations). According to correlation analyses, tea tree's leaf type and germination stage affected tea‐leaf saponins contents positively, indicating tea trees with larger leaves and later germination stage would have a higher content of tea‐leaf saponins with a higher yield of tea‐leaf saponins under the same extraction method.
Doppler and biochemical assessment for the prediction of early pregnancy outcome in patients experiencing threatened spontaneous abortion
Authors: Shehata Nesreen A.A. , Ali Hamada A.A. , Hassan Abd El Gany M.A. , Katta Maha A. , Ali Ashraf S.F.
Published: July 2018

Objective

To evaluate the usefulness of Doppler indices of the corpus luteum and uterine artery in combination with serum progesterone and cancer antigen 125 (CA125) as prognostic tools in first‐trimester threatened spontaneous abortion.

Methods

Pregnant women with threatened spontaneous abortion at a pregnancy duration 8–10 weeks were enrolled into an observational prospective clinical trial at a university hospital in Egypt during 2015. Doppler indices (uterine artery/corpus luteum resistance index and pulsatility index) and biochemical markers (CA125, progesterone) were determined and compared by pregnancy outcome (spontaneous abortion vs continuing pregnancy at 20 weeks).

Results

Of 100 women included, 16 had a spontaneous abortion. These women had a higher CA125 value than did women without an abortion (P<0.001), whereas the progesterone level among women with an abortion was lower (P<0.001). The Doppler indices were not significantly different between the groups, but calculation of the uterine artery resistance index as a percentage of the normal standard value at a given pregnancy duration revealed significant differences (P<0.001) between the two groups.

Conclusion

Serum progesterone and CA125 are useful provisional predictors of spontaneous abortion, whereas the Doppler indices are not. The two biomarkers could be used as a basis to counsel anxious couples.

ClinicalTrials.gov

NCT02420769.
Toward trusted open data and services
Authors: Nati Michele , Mayer Simon , Capossele Angelo , Missier Paolo
Published: July 2018

The number of connected devices is quickly approaching 20 billion, thanks to the increasing availability of connectivity technologies and decreasing hardware costs, and driven by a growing ability to mine the generated data. This market is expected to grow even larger if access to devices and their data were open, with a flourishing ecosystem of applications and services being created around them. Web of Things APIs are paving the way to standardize this process; however, with more access and more revenue come more responsibilities for both device manufacturers and providers of add‐on services: misuse of data and devices needs to be prevented and trust systems need to be in place to reinforce customer confidence in the resulting service systems. In this paper we discuss the opportunities and risks associated with opening up connected devices and propose a technical and legal framework for regulating the resulting service ecosystems.
Case‐specific non‐linear finite element models to predict failure behavior in two functional spinal units
Authors: Groenen Karlijn H. J. , Bitter Thom , van Veluwen Tristia C. G. , van der Linden Yvette M. , Verdonschot Nico , Tanck Esther , Janssen Dennis
Published: July 2018

Current finite element (FE) models predicting failure behavior comprise single vertebrae, thereby neglecting the role of the posterior elements and intervertebral discs. Therefore, this study aimed to develop a more clinically relevant, case‐specific non‐linear FE model of two functional spinal units able to predict failure behavior in terms of (i) the vertebra predicted to fail; (ii) deformation of the specimens; (iii) stiffness; and (iv) load to failure. For this purpose, we also studied the effect of different bone density–mechanical properties relationships (material models) on the prediction of failure behavior. Twelve two functional spinal units (T6‐T8, T9‐T11, T12‐L2, and L3‐L5) with and without artificial metastases were destructively tested in axial compression. These experiments were simulated using CT‐based case‐specific non‐linear FE models. Bone mechanical properties were assigned using four commonly used material models. In 10 of the 11 specimens our FE model was able to correctly indicate which vertebrae failed during the experiments. However, predictions of the three‐dimensional deformations of the specimens were less promising. Whereas stiffness of the whole construct could be strongly predicted (R2 = 0.637–0.688, p < 0.01), we obtained weak correlations between FE predicted and experimentally determined load to failure, as defined by the total reaction force exhibiting a drop in force (R2 = 0.219–0.247, p > 0.05). Additionally, we found that the correlation between predicted and experimental fracture loads did not strongly depend on the material model implemented, but the stiffness predictions did. In conclusion, this work showed that, in its current state, our FE models may be used to identify the weakest vertebra, but that substantial improvements are required in order to quantify in vivo failure loads. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodical, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 36:3208–3218, 2018.
Bone regeneration with bovine bone impairs orthodontic tooth movement despite proper osseous wound healing in a novel mouse model
Authors: Klein Yehuda , Fleissig Omer , Stabholz Ayala , Chaushu Stella , Polak David
Published: July 2018

Background

The aim of this study was to investigate the biological mechanisms underlying alveolar bone regeneration (ABR) and orthodontic tooth movement into bovine bone (BB) regenerated sites.

Methods

Two mouse models were established in C57BL/6 mice. The ABR model was based on osseous defects filled with BB. The orthodontic tooth movement‐ABR model was used to move a molar into the regenerated site. Osseous morphometric analysis and tooth movement distance were evaluated with micro‐CT. Histologic characteristics and osteoclast (OCS) accumulation were evaluated by hematoxylin and eosin and tartrate‐resistant acid phosphatase staining (TRAP). Expression and location of the receptor activator of nuclear factor‐kappa B (RANKL) and of osteoprotegerin (OPG) were evaluated by immunofluorescent staining.

Results

Bone healing peaked at 4 weeks. The distance of the orthodontic tooth movement into the bovine bone was significantly reduced versus that of the nonbovine bone controls. BB particles accumulated along the root's pressure side during orthodontic treatment. Despite the osteoclasts’ presence adjacent to the BB particles, no BB resorption was observed. Increased RANKL expression was seen at the orthodontic tooth movement pressure zone, without any change in OPG expression.

Conclusion

The two novel mouse models show that the lack of resorption of BB xenografts renders them inadequate for proper orthodontic tooth movement at a later stage.
Characteristics of starch from different bean genotypes and its effect on biodegradable films
Authors: Vanier Nathan Levien , de Oliveira Jean Paulo , Bruni Graziella Pinheiro , El Halal Shanise Lisie Mello , Villanova Franciene Almeida , Zavareze Elessandra da Rosa , Dias Alvaro Renato Guerra , Bassinello Priscila Zaczuk
Published: July 2018

BACKGROUND

Starches from four common bean genotypes were characterized and used in the production of biodegradable films. Starches were characterized by their swelling power, solubility, amylose content, granule morphology, relative crystallinity, thermal and pasting properties, and susceptibility to α‐amylase hydrolysis. Films were characterized according to their morphology, mechanical and water vapor barrier properties, whiteness and opacity.

RESULT

Depending on the common bean genotype, a great variation on starch properties was found, which, in turn, clearly impacted on the characteristics of the starch‐based films. Starches from BRS Pitanga and BRS Pérola genotypes exhibited the highest amylose content and the lowest swelling capabilities. Bean starch from the IPR Uirapuru genotype presented granules with an irregular surface and shape. Starches from IPR Uirapuru and BRS Estilo genotypes provided well‐structured biodegradable films, without the occurrence of fissures or cracks. Moreover, starch films containing starch from BRS Estilo genotype exhibited the highest flexibility, permeability and solubility.

CONCLUSION

The morphological, mechanical and water vapor barrier properties of films elaborated with common bean starch vary greatly as a function of the bean genotype used for starch production. © 2018 Society of Chemical Industry
Ex Vivo High‐Frequency Ultrasound for Assessment of Basal Cell Carcinoma
Authors: Vilas‐Sueiro Alejandro , Alfageme Fernando , Salgüero Irene , De las Heras Cristina , Roustan Gastón
Published: July 2018

The use of Mohs micrographic surgery for poorly defined cutaneous tumors is present in a few departments in Spain. Reintervention is occasionally necessary when the margins of the surgical specimen are invaded by the tumor. We propose the use of ultrasound to assess these margins by imaging the surgical specimen once excised.
Whitepaper: Practical challenges for researchers in data sharing: Review
Authors: Kessler Rachel
Published: July 2018

Key points

Springer Nature's white paper seeks to determine the main obstacles for data sharing and looks at how discipline, region, and seniority impact data sharing.

The greatest issue around data sharing is organizing the data in a useful way.

The amount of data sharing varies widely within the sciences, with biology researchers sharing the most and physical sciences sharing the least.

Asian researchers share their data the most while Australasians share the least.

The white paper underestimates the importance of attitudes when assessing the obstacles.

The report does not include a statistical analysis to confirm whether the observed trends were significant.
1.7 micron optical coherence tomography for vaginal tissue characterization in vivo
Authors: Li Yan , Sudol Neha T. , Miao Yusi , Jing Joseph C. , Zhu Jiang , Lane Felicia , Chen Zhongping
Published: July 2018

Objectives

Optical coherence tomography (OCT) can noninvasively visualize in vivo tissue microstructure with high spatial resolution that approaches the histologic level. Currently, OCT studies in gynecology are few and limited to a conventional 1.3 μm center wavelength swept light source which provides high spatial resolution but limited penetration depth. Here, we present a novel endoscopic OCT system with improved penetration depth and high resolution.

Methods

A novel endoscopic OCT system was developed based on a 1.7 µm swept source laser, which is capable of deeper tissue penetration due to its longer wavelength. To evaluate the performance of system, we imaged the human vaginas in vivo with both conventional 1.3 and 1.7 μm endoscopic OCT systems.

Results

With the 1.7 μm endoscopic OCT system, imaging depth was improved by more than 25%, allowing better visualization of the lamina propria and clear contrast of the epithelial layer from the surrounding tissues.

Conclusion

The significantly improved performance of the novel 1.7 μm OCT imaging system demonstrates its potential use as a minimally‐invasive monitoring tool of vaginal health in gynecologic practice. Lasers Surg. Med. 51:120–126, 2019. © 2018 Wiley Periodicals, Inc.
Combined Hypothermic and Normothermic Machine Perfusion Improves Functional Recovery of Extended Criteria Donor Livers
Authors: Boteon Yuri L. , Laing Richard W. , Schlegel Andrea , Wallace Lorraine , Smith Amanda , Attard Joseph , Bhogal Ricky H. , Neil Desley A. H. , Hübscher Stefan , Perera M. Thamara P. R. , Mirza Darius F. , Afford Simon C. , Mergental Hynek
Published: July 2018

Hypothermic oxygenated perfusion (HOPE) and normothermic perfusion are seen as distinct techniques of ex situ machine perfusion of the liver. We aimed to demonstrate the feasibility of combining both techniques and whether it would improve functional parameters of donor livers into transplant standards. Ten discarded human donor livers had either 6 hours of normothermic perfusion (n = 5) or 2 hours of HOPE followed by 4 hours of normothermic perfusion (n = 5). Liver function was assessed according to our viability criteria; markers of tissue injury and hepatic metabolic activity were compared between groups. Donor characteristics were comparable. During the hypothermic perfusion phase, livers down‐regulated mitochondrial respiration (oxygen uptake,P= 0.04; partial pressure of carbon dioxide perfusate,P= 0.04) and increased adenosine triphosphate levels 1.8‐fold. Following normothermic perfusion, those organs achieved lower tissue expression of markers of oxidative injury (4‐hydroxynonenal,P= 0.008; CD14 expression,P= 0.008) and inflammation (CD11b,P= 0.02; vascular cell adhesion molecule 1,P= 0.05) compared with livers that had normothermic perfusion alone. All livers in the combined group achieved viability criteria, whereas 40% (2/5) in the normothermic group failed (P= 0.22). In conclusion, this study suggests that a combined protocol of hypothermic oxygenated and normothermic perfusions might attenuate oxidative stress, tissue inflammation, and improve metabolic recovery of the highest‐risk donor livers compared with normothermic perfusion alone.
Advances in digital and physical anthropomorphic breast phantoms for x‐ray imaging
Authors: Glick Stephen J. , Ikejimba Lynda C.
Published: July 2018

Purpose

With the advent of three‐dimensional (3D) breast imaging modalities such as digital breast tomosynthesis (DBT) and dedicated breast CT (bCT), research into new anthropomorphic breast phantoms has accelerated. These breast phantoms are important for the optimization of new breast imaging systems, assessing new regulatory submissions to prove safety and effectiveness, and for developing new approaches to acceptance and constancy testing of 3D breast imaging systems. This paper provides a review of current research investigating both digital and physical breast phantom development for use in x‐ray based imaging.

Methods

Two approaches for designing anthropomorphic, digital breast phantoms are discussed, procedural model‐based phantom generation, where breast features are expressed using mathematical models, and patient‐based generation, where breast structures from tissue specimens or patient‐based breast MR or CT volumes are segmented. Following this discussion, a review of physical anthropomorphic phantoms is given, with emphasis on the advantages and disadvantages present with each approach.

Conclusions

This paper provides a summary of the state‐of‐the‐art in anthropomorphic breast phantom development for x‐ray breast imaging. The primary advantage of model‐based digital phantoms is that an unlimited number of phantoms with varying size, shape, and density can be generated. Current research on model‐based breast phantoms is producing more and more realistic breast models; however, they probably are not yet able to pass the so‐called “fool the radiologist” visualization test. Empirical patient‐based breast phantoms are typically based on clinical breast CT data and look more realistic. However, clinical breast CT images have limited spatial resolution and thus do not always portray the finer details in the breast. A number of innovative solutions have been proposed for fabricating physical anthropomorphic breast phantoms based on digital phantom models; however, a number of challenges remain, including realistic modeling of x‐ray attenuation properties and accurately representing high‐frequency structures within breast.
Comparison of prospective head motion correction with NMR field probes and an optical tracking system
Authors: Eschelbach Martin , Aghaeifar Ali , Bause Jonas , Handwerker Jonas , Anders Jens , Engel Eva‐Maria , Thielscher Axel , Scheffler Klaus
Published: July 2018

Purpose

The aim of this study was to compare prospective head motion correction and motion tracking abilities of two tracking systems: Active NMR field probes and a Moiré phase tracking camera system using an optical marker.

Methods

Both tracking systems were used simultaneously on human subjects. The prospective head motion correction was compared in an MP2RAGE and a gradient echo sequence. In addition, the motion tracking trajectories for three subjects were compared against each other and their correlation and deviations were analyzed.

Results

With both tracking systems motion artifacts were visibly reduced. The precision of the field probe system was on the order of 50 µm for translations and 0.03° for rotations while the camera's was approximately 5 µm and 0.007°. The comparison of the measured trajectories showed close correlation and an average absolute deviation below 500 µm and 0.5°.

Conclusion

This study presents the first in vivo comparison between NMR field probes and Moiré phase tracking. For the gradient echo images, the field probes had a similar motion correction performance as the optical tracking system. For the MP2RAGE measurement, however, the camera yielded better results. Still, both tracking systems substantially decreased image artifacts in the presence of subject motion. Thus, the motion tracking modality should be chosen according to the specific requirements of the experiment while considering the desired image resolution, refresh rate, and head coil constraints.
Five‐minute whole‐heart coronary MRA with sub‐millimeter isotropic resolution, 100% respiratory scan efficiency, and 3D‐PROST reconstruction
Authors: Bustin Aurélien , Ginami Giulia , Cruz Gastão , Correia Teresa , Ismail Tevfik F. , Rashid Imran , Neji Radhouene , Botnar René M. , Prieto Claudia
Published: July 2018

Purpose

To enable whole‐heart 3D coronary magnetic resonance angiography (CMRA) with isotropic sub‐millimeter resolution in a clinically feasible scan time by combining respiratory motion correction with highly accelerated variable density sampling in concert with a novel 3D patch‐based undersampled reconstruction (3D‐PROST).

Methods

An undersampled variable density spiral‐like Cartesian trajectory was combined with 2D image‐based navigators to achieve 100% respiratory efficiency and predictable scan time. 3D‐PROST reconstruction integrates structural information from 3D patch neighborhoods through sparse representation, thereby exploiting the redundancy of the 3D anatomy of the coronary arteries in an efficient low‐rank formulation. The proposed framework was evaluated in a static resolution phantom and in 10 healthy subjects with isotropic resolutions of 1.2 mm3 and 0.9 mm3 and undersampling factors of ×5 and ×9. 3D‐PROST was compared against fully sampled (1.2 mm3 only), conventional parallel imaging, and compressed sensing reconstructions.

Results

Phantom and in vivo (1.2 mm3) reconstructions were in excellent agreement with the reference fully sampled image. In vivo average acquisition times (min:s) were 7:57 ± 1:18 (×5) and 4:35 ± 0:44 (×9) for 0.9 mm3 resolution. Sub‐millimeter 3D‐PROST resulted in excellent depiction of the left and right coronary arteries including small branch vessels, leading to further improvements in vessel sharpness and visible vessel length in comparison with conventional reconstruction techniques. Image quality rated by 2 experts demonstrated that 3D‐PROST provides good image quality and is robust even at high acceleration factors.

Conclusion

The proposed approach enables free‐breathing whole‐heart 3D CMRA with isotropic sub‐millimeter resolution in <5 min and achieves improved coronary artery visualization in a short and predictable scan time.
Rapid dynamic contrast‐enhanced MRI for small animals at 7T using 3D ultra‐short echo time and golden‐angle radial sparse parallel MRI
Authors: Zhang Jin , Feng Li , Otazo Ricardo , Kim Sungheon Gene
Published: July 2018

Purpose

To develop a rapid dynamic contrast‐enhanced MRI method with high spatial and temporal resolution for small‐animal imaging at 7 Tesla.

Methods

An ultra‐short echo time (UTE) pulse sequence using a 3D golden‐angle radial sampling was implemented to achieve isotropic spatial resolution with flexible temporal resolution. Continuously acquired radial spokes were grouped into subsets for image reconstruction using a multicoil compressed sensing approach (Golden‐angle RAdial Sparse Parallel; GRASP). The proposed 3D‐UTE‐GRASP method with high temporal and spatial resolutions was tested using 7 mice with GL261 intracranial glioma models.

Results

Iterative reconstruction with different temporal resolutions and regularization factors λ showed that, in all cases, the cost function decreased to less than 2.5% of its starting value within 20 iterations. The difference between the time‐intensity curves of 3D‐UTE‐GRASP and nonuniform fast Fourier transform (NUFFT) images was minimal when λ was 1% of the maximum signal intensity of the initial NUFFT images. The 3D isotropic images were used to generate pharmacokinetic parameter maps to show the detailed images of the tumor characteristics in 3D and also to show longitudinal changes during tumor growth.

Conclusion

This feasibility study demonstrated that the proposed 3D‐UTE‐GRASP method can be used for effective measurement of the 3D spatial heterogeneity of tumor pharmacokinetic parameters.
Toward more reliable measurements of NOE effects in CEST spectra at around −1.6 ppm (NOE (−1.6)) in rat brain
Authors: Zu Zhongliang
Published: July 2018

Purpose

Recently, a new relayed nuclear Overhauser enhancement (NOE) saturation transfer effect at around −1.6 parts per million, termed NOE(−1.6), and its potential applications in tumor and stroke were reported by several institutes. However, there is a concern of the reproducibility of NOE(−1.6) measurements because it is not reported by many other publications. This paper aims to study the influence of typically overlooked experimental settings on the NOE(−1.6) signal and to build a framework for more reliable measurements of NOE(−1.6) at 9.4T.

Methods

Z‐spectra were obtained in rat brains. A fitting approach was performed to quantify all known saturation transfer effects except NOE(−1.6). Residual signals were obtained by removing these confounding effects from Z‐spectra and were then used to quantify NOE(−1.6). Multislice imaging was performed to study the NOE(−1.6) dependence on brain regions. The influences of euthanasia, anesthesia, breathing gases, and RF irradiation power were also evaluated.

Results

Results demonstrate that the NOE(−1.6) signal contributions are often not clearly observable in raw Z‐spectra at relatively high irradiation powers due to, for example, the direct water saturation effect, but they can be visualized after removing other nonspecific effects. In addition, the NOE(−1.6) effect depends on brain region, decreases postmortem, shifts after long‐duration anesthesia, and may be enhanced by increasing O2 and N2O breathing air concentrations.

Conclusion

Because the NOE(−1.6) effect is more susceptible to the direct water saturation effect and more sensitive to physiological conditions than are other CEST effects, incorporating known sensitivities into the experimental design and data analysis is necessary to ensure more reliable NOE(−1.6) results.
Determination of multipool contributions to endogenous amide proton transfer effects in global ischemia with high spectral resolution in vivo chemical exchange saturation transfer MRI
Authors: Zhou Iris Yuwen , Lu Dongshuang , Ji Yang , Wu Limin , Wang Enfeng , Cheung Jerry S. , Zhang Xiao‐An , Sun Phillip Zhe
Published: July 2018

Purpose

Chemical exchange saturation transfer (CEST) MRI has been used for quantitative assessment of dilute metabolites and/or pH in disorders such as acute stroke and tumor. However, routine asymmetry analysis (MTRasym) may be confounded by concomitant effects such as semisolid macromolecular magnetization transfer (MT) and nuclear Overhauser enhancement. Resolving multiple contributions is essential for elucidating the origins of in vivo CEST contrast.

Methods

Here we used a newly proposed image downsampling expedited adaptive least‐squares fitting on densely sampled Z‐spectrum to quantify multipool contribution from water, nuclear Overhauser enhancement, MT, guanidinium, amine, and amide protons in adult male Wistar rats before and after global ischemia.

Results

Our results revealed the major contributors to in vivo T1‐normalized MTRasym (3.5 ppm) contrast between white and gray matter (WM/GM) in normal brain (−1.96%/second) are pH‐insensitive macromolecular MT (−0.89%/second) and nuclear Overhauser enhancement (−1.04%/second). Additionally, global ischemia resulted in significant changes of MTRasym, being −2.05%/second and −1.56%/second in WM and GM, which are dominated by changes in amide (−1.05%/second, −1.14%/second) and MT (−0.88%/second, −0.62%/second). Notably, the pH‐sensitive amine and amide effects account for nearly 60% and 80% of the MTRasym changes seen in WM and GM, respectively, after global ischemia, indicating that MTRasym is predominantly pH‐sensitive.

Conclusion

Combined amide and amine effects dominated the MTRasym changes after global ischemia, indicating that MTRasym is predominantly pH‐sensitive and suitable for detecting tissue acidosis following acute stroke.
Intricacies in three‐dimensional limit analysis of earth slopes
Authors: Park Dowon , Michalowski Radoslaw L.
Published: July 2018

Analyses of three‐dimensional slope failures can be elaborate because of the complexity owed to the geometry of the failure mechanism that needs to conform to an admissible kinematics of the slope collapse. This admissibility is imposed by the soil limit state condition, the normality plastic flow rule, and the boundary conditions. The kinematic approach of limit analysis is employed, and a rotational 3D slope failure is revisited. The study leads to the conclusion that some geometric constraints used in previous studies limit the range of admissible mechanisms resulting in overestimating stability factors. A set of results is presented that was obtained using an algorithm that allowed eliminating limitations present in previous studies. The largest improvements in the solutions were found for undrained failures of narrow slopes. For a 30° slope limited in width by the width‐to‐height ratio of 0.6, the stability factor calculated in previous studies overestimated the current calculations by nearly 39%. This overestimation is smaller for drained failures, and it drops significantly with an increase in the width of the failure mechanism.
Rheological determinants for simultaneous staging of hepatic fibrosis and inflammation in patients with chronic liver disease
Authors: Sinkus Ralph , Lambert Simon , Abd‐Elmoniem Khaled Z. , Morse Caryn , Heller Theo , Guenthner Christian , Ghanem Ahmed M. , Holm Sverre , Gharib Ahmed M.
Published: July 2018

The purpose of this study is to investigate the use of fundamental rheological parameters as quantified by MR elastography (MRE) to measure liver fibrosis and inflammation simultaneously in humans.

MRE was performed on 45 patients at 3 T using a vibration frequency of 56 Hz. Fibrosis and inflammation scores were obtained from liver biopsies. Biomechanical properties were quantified in terms of complex shear modulus G* as well as shear wave phase velocity c and shear wave attenuation α. A rheological fractional derivative order model was used to investigate the linear dependence of the free model parameters (dispersion slope y, intrinsic speed c0, and intrinsic relaxation time τ) on histopathology. Leave‐one‐out cross‐validation was then utilized to demonstrate the effectiveness of the model.

The intrinsic speed c0 increases with hepatic fibrosis, while an increased relaxation time τ is reflective of more inflammation of the liver parenchyma. The dispersion slope y does not depend either on fibrosis or on inflammation. The proposed rheological model, given this specific parameterization, establishes the functional dependences of biomechanical parameters on histological fibrosis and inflammation. The leave‐one‐out cross‐validation demonstrates that the model allows identification, from the MRE measurements, of the histology scores when grouped into low−/high‐grade fibrosis and low−/high‐grade inflammation with significance levels of P = 0.0004 (fibrosis) and P = 0.035 (inflammation).

The functional dependences of intrinsic speed and relaxation time on fibrosis and inflammation, respectively, shed new light onto the impact hepatic pathological changes on liver tissue biomechanics in humans. The dispersion slope y appears to represent a structural parameter of liver parenchyma not impacted by the severity of fibrosis/inflammation present in this patient cohort. This specific parametrization of the well‐established rheological fractional order model is valuable for the clinical assessment of both fibrosis and inflammation scores, going beyond the capability of the plain shear modulus measurement commonly used for MRE.
Multilevel heterogeneity of mitochondrial respiratory chain deficiency
Authors: Vincent Amy E , Picard Martin
Published: July 2018

Mitochondrial diseases are heterogeneous multisystem disorders that show a mosaic pattern of mitochondrial respiratory chain dysfunction. The mitochondrial DNA (mtDNA) mutation load is heterogeneous at multiple levels: across organs, between cells, and between subcellular compartments. Such heterogeneity poses a diagnostic challenge, but also provides a scientific opportunity to explore the biological mechanisms underlying the onset and progression of these disorders. A recent article in The Journal of Pathology described a novel histochemical technique – nitro blue tetrazolium exclusion assay (NBTx) ‐ to quantify mitochondrial cytochrome c oxidase (COX, or complex IV) deficiency. This technique is rapid, cost‐effective, and quantitative, and is more sensitive than previous histochemical methods. It can also be applied across model organisms and human tissues. The NBTx method should therefore be a useful diagnostic tool, and may catalyze research examining the cellular and subcellular mechanisms that drive the onset and progression of inherited and acquired mtDNA disorders. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Influence of fitness on health status among survivors of acute lymphoblastic leukemia
Authors: Wilson Carmen L. , Howell Carrie R. , Partin Robyn E. , Lu Lu , Kaste Sue C. , Mulrooney Daniel A. , Pui Ching‐Hon , Lanctot Jennifer Q. , Srivastava Deo Kumar , Robison Leslie L. , Hudson Melissa M. , Ness Kirsten K.
Published: July 2018

Introduction

We aimed to determine the prevalence of self‐reported adverse health status among childhood acute lymphoblastic leukemia (ALL) survivors and to identify associations between components of physical fitness and health status.

Methods

Participants included 365 ALL survivors (mean age at evaluation of 28.6 ± 5.9 years) and 365 age‐, sex‐, and race‐matched community controls. Self‐report of poor general health, poor mental health, functional impairments, and activity limitations were used to describe adverse health status. Fitness was evaluated by assessing flexibility, muscular strength and endurance, peak oxygen uptake, and balance. Generalized linear models were used to examine associations between fitness metrics and health status.

Results

Survivors were more likely than controls to report poor general health (20.6% vs. 10.4%, risk ratio [RR] = 2.0, 95% confidence intervals [CI] = 1.4–2.9), poor mental health (28.0% vs. 14.5%, RR = 1.9, 95% CI = 1.4–2.6), functional impairments (10.5% vs. 4.1%, RR = 2.5, 95% CI = 1.4–4.6), and activity limitations (29.0% vs. 14.4%, RR = 2.0, 95% CI = 1.5–2.7). Survivors whose balance scores were more than 1.5 standard deviations below the mean of the control population were more likely to report poor general health (RR = 1.7, 95% CI = 1.1–2.8), poor mental health (RR = 1.9, 95% CI = 1.3–2.8), and functional limitations (RR = 2.5, 95% CI = 1.2–56). Survivors with low strength were more likely to report poor general health (RR = 1.8, 95% CI = 1.1–3.1), functional impairments (RR = 4.2, 95% CI = 1.7–10.4), and activity limitations (RR = 1.8, 95% CI = 1.2–2.8).

Conclusions

ALL survivors, particularly those with poor balance and reduced muscular strength, are at increased risk for adverse health status.
Parvoviral disease in childhood cancer: Clinical outcomes and impact on therapy at a tertiary cancer center in India
Authors: Ramanathan Subramaniam , Narula Gaurav , Prasad Maya , Vora Tushar , Chinnaswamy Girish , Banavali Shripad
Published: July 2018

Background and aim

Parvovirus‐B19 disease in immunocompromised children can cause myelosuppression and therapeutic delays. We studied the clinical profiles of children having symptoms suggestive of parvoviral disease at our institution, a large tertiary cancer center.

Methods

Children below age 15 years undergoing treatment for malignancies with clinical features suggestive of parvoviral infection, and/or unexplained drop in hemoglobin, and/or prolonged cytopenia were screened for parvovirus infection using DNA‐PCR for parvovirus‐B19 (PB19) in the peripheral blood. Patients testing positive from September 2014 till February 2017 were studied.

Results

Of the 59 patients (36 patients with hematolymphoid malignancies, 23 with solid tumors) screened for suspected parvoviral infections, 27 tested positive. Median age was 9.6 years (2.25–15 years), 18 (66%) had hematolymphoid malignancies, while 7 (33%) had solid tumors. Six patients (26%) were on intensive phases, 16 (60%) patients developed the symptoms during maintenance chemotherapy, and 4 (15%) after completion of therapy. Isolated anemia was the commonest feature seen in 10 patients (37%) while bicytopenia and pancytopenia were noticed in 8 (30%) and 9 (33%) patients respectively. Fifty percent of patients those who received rituximab (3/6) developed persistent parvoviremia (>4 weeks) as compared with 24% (5/21) of those who did not. Two patients (7%) developed hemophagocytic lymphohistiocytosis (HLH). Treatment delay by more than 14 days was encountered in a majority (62%), with 5 patients requiring treatment modification or even suspension.

Conclusions

Parvoviral infection in children who are on or have recently completed chemotherapy can lead to multiple cytopenias and significant treatment delays. Rituximab exposure may lead to persistent parvoviral disease (p < 0.05). HLH, though occasional, can be a serious complication.