bluuebunny/crossref_metadata_2025 huggingface dataset:
Future of brain stimulation: New targets, new indications, new technology
Authors: Hariz Marwan , Blomstedt Patric , Zrinzo Ludvic
Published: October 2013

In the last quarter of a century, DBS has become an established neurosurgical treatment for Parkinson's disease (PD), dystonia, and tremors. Improved understanding of brain circuitries and their involvement in various neurological and psychiatric illnesses, coupled with the safety of DBS and its exquisite role as a tool for ethical study of the human brain, have unlocked new opportunities for this technology, both for future therapies and in research. Serendipitous discoveries and advances in structural and functional imaging are providing abundant “new” brain targets for an ever‐increasing number of pathologies, leading to investigations of DBS in diverse neurological, psychiatric, behavioral, and cognitive conditions. Trials and “proof of concept” studies of DBS are underway in pain, epilepsy, tinnitus, OCD, depression, and Gilles de la Tourette syndrome, as well as in eating disorders, addiction, cognitive decline, consciousness, and autonomic states. In parallel, ongoing technological development will provide pulse generators with longer battery longevity, segmental electrode designs allowing a current steering, and the possibility to deliver “on‐demand” stimulation based on closed‐loop concepts. The future of brain stimulation is certainly promising, especially for movement disorders—that will remain the main indication for DBS for the foreseeable future—and probably for some psychiatric disorders. However, brain stimulation as a technique may be at risk of gliding down a slippery slope: Some reports indicate a disturbing trend with suggestions that future DBS may be proposed for enhancement of memory in healthy people, or as a tool for “treatment” of “antisocial behavior” and for improving “morality.” © 2013 International Parkinson and Movement Disorder Society
Alcohol challenge and sensitivity to change of the essential tremor rating assessment scale
Authors: Voller Bernhard , Lines Emily , McCrossin Gayle , Artiles Aaron , Tinaz Sule , Lungu Codrin , Hallett Mark , Haubenberger Dietrich
Published: October 2013

Background

The ability of the Essential Tremor (ET) Rating Assessment Scale (TETRAS) to detect changes in tremor severity is unknown.

Methods

Fifteen adult ET patients received a single oral ethanol dose calculated to reach 0.05 g/dL breath alcohol content (brAC). Effects were investigated independently with accelerometry and TETRAS.

Results

Accelerometry data were log‐transformed and a cumulative score logACC(R+L) was calculated. Correlation between logACC(R+L) and TETRAS was significant. TETRAS and accelerometry showed a significant effect of time point using repeated‐measures analysis of variance. The difference between baseline and each of the following six time points as well as the correlation of TETRAS with brAC were significant. The calculated minimum detectable change of TETRAS was 8.9% and the effect size was d = 4.75 (95% confidence interval: 3.60–5.90).

Conclusion

We demonstrated sensitivity to change of the TETRAS performance scale after a therapeutic intervention, which further establishes its potential for use in both clinical and research settings. © 2013 International Parkinson and Movement Disorder Society
Dopamine overdose hypothesis: Evidence and clinical implications
Authors: Vaillancourt David E. , Schonfeld Daniel , Kwak Youngbin , Bohnen Nicolaas I. , Seidler Rachael
Published: October 2013

About a half a century has passed since dopamine was identified as a neurotransmitter, and it has been several decades since it was established that people with Parkinson's disease receive motor symptom relief from oral levodopa. Despite the evidence that levodopa can reduce motor symptoms, there has been a developing body of literature that dopaminergic therapy can improve cognitive functions in some patients but make them worse in others. Over the past two decades, several laboratories have shown that dopaminergic medications can impair the action of intact neural structures and impair the behaviors associated with these structures. In this review, we consider the evidence that has accumulated in the areas of reversal learning, motor sequence learning, and other cognitive tasks. The purported inverted‐U shaped relationship between dopamine levels and performance is complex and includes many contributory factors. The regional striatal topography of nigrostriatal denervation is a critical factor, as supported by multimodal neuroimaging studies. A patient's individual genotype will determine the relative baseline position on this inverted‐U curve. Dopaminergic pharmacotherapy and individual gene polymorphisms can affect the mesolimbic and prefrontal cortical dopaminergic functions in a comparable, inverted‐U dose‐response relationship. Depending on these factors, a patient can respond positively or negatively to levodopa when performing reversal learning and motor sequence learning tasks. These tasks may continue to be relevant as our society moves to increased technological demands of a digital world that requires newly learned motor sequences and adaptive behaviors to manage daily life activities. © 2013 International Parkinson and Movement Disorder Society
A class of multi‐step difference schemes by using Padé approximant
Authors: Wu Jinming , Zhang Xiaolei
Published: October 2013

In this paper, we present a method for the construction of a class of multi‐step finite differences schemes for solving arbitrary order linear two‐point boundary value problems. The construction technique is based on Padé approximant. It is easy to derive multi‐step difference schemes, and it includes many existing schemes as its special cases. Numerical experiments show that the proposed schemes are flexible and convergent. Copyright © 2013 John Wiley & Sons, Ltd.
Quercetin prevents liver carcinogenesis by inducing cell cycle arrest, decreasing cell proliferation and enhancing apoptosis
Authors: Casella María Laura , Parody Juan Pablo , Ceballos María Paula , Quiroga Ariel Darío , Ronco María Teresa , Francés Daniel Eleazar , Monti Juan Alberto , Pisani Gerardo Bruno , Carnovale Cristina Ester , Carrillo María Cristina , de Luján Alvarez María
Published: October 2013

Scope

Quercetin is the most abundant flavonoid in human diet. It has special interest as it holds anticancerous properties. This study aims to clarify the mechanisms involved in quercetin effects during the occurrence of preneoplastic lesions in rat liver.

Methods and results

Adult male Wistar rats were subjected to a two‐phase model of hepatocarcinogenesis (initiated‐promoted group). Initiated‐promoted animals also received quercetin 10 and 20 mg/kg body weight (IPQ10 and IPQ20 groups, respectively). Antioxidant defenses were modified by quercetin administration at both doses. However, only IPQ20 group showed a reduction in number and volume of preneoplastic lesions. This group showed increased apoptosis and a reduction in the proliferative index. In addition, IPQ20 group displayed a reduction of cell percentages in G1 and S phases, accumulation in G2, and decrease in M phase, with reduced expression of cyclin D1, cyclin A, cyclin B, and cyclin‐dependent kinase 1. Interestingly, peroxisome proliferator activated receptor‐α levels were reduced in IPQ20 group.

Conclusion

The outcomes of this study represent a significant contribution to the current understanding on the preventive mechanisms of quercetin during the early stages of liver cancer development, demonstrating that in addition to its known proapoptotic characteristics, the flavonoid modulates the expression of critical cell cycle regulators and peroxisome proliferator activated receptor‐α activity.
Prediction of the wine polyphenol metabolic space: An application of the Phenol‐Explorer database
Authors: Boto‐Ordóñez María , Rothwell Joseph A. , Andres‐Lacueva Cristina , Manach Claudine , Scalbert Augustin , Urpi‐Sarda Mireia
Published: October 2013

Scope

Knowledge of in vivo polyphenol metabolites derived from the consumption of red wine could be key to understanding its health benefits. This work aimed to predict the wine polyphenol metabolic space in biofluids by using all available data compiled in the Phenol‐Explorer database.

Methods and results

A search strategy was developed for Phenol‐Explorer to obtain the widest range of metabolites related to wine consumption. A total of 97 metabolites have been described in intervention studies with wine and related products (n = 37), and after consumption of pure compounds known to be wine constituents (n = 90). These 97 metabolites, derived from host and microbial metabolism of several classes of polyphenols, were found in plasma and urine samples and some of them have demonstrated higher or lower biological activities than the parent compound in in vitro studies. The metabolites have been linked to generate, for the first time, a global pathway map of wine in vivo polyphenol metabolism.

Conclusion

The retrieval of the widest range of metabolites so far described and their assembly as a metabolic pathway map could aid the identification of possible biomarkers of wine consumption and improve current understanding of the health effects of wine consumption.
Computational NMR coupling constants: Shifting and scaling factors for evaluating 1JCH
Authors: San Fabián J. , García de la Vega J.M. , Suardíaz R. , Fernández‐Oliva M. , Pérez C. , Crespo‐Otero R. , Contreras R.H.
Published: October 2013

Optimized shifting and/or scaling factors for calculating one‐bond carbon–hydrogen spin–spin coupling constants have been determined for 35 combinations of representative functionals (PBE, B3LYP, B3P86, B97‐2 and M06‐L) and basis sets (TZVP, HIII‐su3, EPR‐III, aug‐cc‐pVTZ‐J, ccJ‐pVDZ, ccJ‐pVTZ, ccJ‐pVQZ, pcJ‐2 and pcJ‐3) using 68 organic molecular systems with 88 1JCH couplings including different types of hybridized carbon atoms. Density functional theory assessment for the determination of 1JCH coupling constants is examined, comparing the computed and experimental values. The use of shifting constants for obtaining the calculated coupling improves substantially the results, and most models become qualitatively similar. Thus, for the whole set of couplings and for all approaches excluding those using the M06 functional, the root‐mean‐square deviations lie between 4.7 and 16.4 Hz and are reduced to 4–6.5 Hz when shifting constants are considered. Alternatively, when a specific rovibrational contribution of 5 Hz is subtracted from the experimental values, good results are obtained with PBE, B3P86 and B97‐2 functionals in combination with HIII‐su3, aug‐cc‐pVTZ‐J and pcJ‐2 basis sets. Copyright © 2013 John Wiley & Sons, Ltd.
In vivo detection of citrate in brain tumors by 1H magnetic resonance spectroscopy at 3T
Authors: Choi Changho , Ganji Sandeep K. , Madan Akshay , Hulsey Keith M. , An Zhongxu , Zhang Song , Pinho Marco C. , DeBerardinis Ralph J. , Bachoo Robert M. , Maher Elizabeth A.
Published: October 2013

Purpose

To test whether citrate is elevated in adult patients with gliomas using 1H magnetic resonance spectroscopy (MRS) at 3T in vivo.

Methods

Thirty‐four adult patients were enrolled in the study, including six subjects with glioblastomas, eight subjects with astrocytomas (World Health Organization grade 3, n = 5; grade 2, n = 3), and 20 subjects with oligodendrogliomas (grade 3, n = 5; grade 2, n = 15). Five healthy volunteers were studied for baseline citrate data. Single‐voxel localized spectra were collected with point‐resolved spectroscopy (PRESS) echo times of 35 and 97 ms and were analyzed with LCModel software using numerically calculated basis spectra that included the effects of the PRESS radiofrequency and gradient pulses.

Results

Citrate was not measurable by MRS in healthy brain but was detected in tumor patients at both echo times. The citrate concentration was estimated to be as high as 1.8 mM with reference to water at 42 M, with Cramér‐Rao lower bounds (CRLB) as low as 5%. The mean citrate level was 0.7 ± 0.4 mM (mean ± SD, n = 32) with a median CRLB of ∼12%. No correlation was identified between citrate concentration and tumor grade or histological type.

Conclusion

Citrate was increased in the majority of gliomas in adult patients. The elevated citrate in our data indicates an altered metabolic state of tumor relative to healthy brain. Magn Reson Med 72:316–323, 2014. © 2013 Wiley Periodicals, Inc.
Imaging neurodegeneration in the mouse hippocampus after neonatal hypoxia–ischemia using oscillating gradient diffusion MRI
Authors: Aggarwal Manisha , Burnsed Jennifer , Martin Lee J. , Northington Frances J. , Zhang Jiangyang
Published: October 2013

Purpose

To investigate if frequency‐dependent contrasts using oscillating gradient diffusion MRI (dMRI) can detect hypoxia–ischemia (HI) ‐induced neurodegeneration in the neonatal mouse hippocampus.

Methods

Pulsed‐ and oscillating‐gradient dMR images (at 50, 100, and 150 Hz) were acquired from postmortem fixed brains of mice exposed to neonatal HI using the Rice‐Vanucci model. MRI data were acquired at 1, 4, and 8 days following HI, and compared with histological data from the same mice for in situ histological validation of the MRI findings.

Results

The rate of change of apparent diffusion coefficient with gradient frequency (ΔfADC) revealed unique layer‐specific contrasts in the neonatal mouse hippocampus. ΔfADC measurements were found to show a significant decrease in response to neonatal HI injury, in the pyramidal (Py) and granule (GrDG) cell layers compared with contralateral regions. The areas of reduced intensity in the ΔfADC maps corresponded to regional neurodegeneration seen with H&E and Fluoro‐Jade C stainings, indicating that alterations in ΔfADC contrasts are sensitive to early microstructural changes due to HI‐induced neurodegeneration in the studied regions.

Conclusion

The findings show that the frequency‐dependence of ADC measurements with oscillating‐gradient dMRI can provide a sensitive contrast to detect HI‐induced neurodegeneration in neuronal layers of the neonatal mouse hippocampus. Magn Reson Med 72:829–840, 2014. © 2013 Wiley Periodicals, Inc.
Absolute magnetic susceptibility of rat brain tissue
Authors: Peprah Marcus K. , Astary Garrett W. , Mareci Thomas H. , Meisel Mark W.
Published: October 2013

Purpose

This study was performed to test the commonly held hypothesis that the absolute magnetic susceptibility of brain tissue is close to that of water since water accounts for over 50% of the tissue composition. In addition, the absolute value of susceptibility of brain tissue is needed for the development of materials that are implanted into or in close proximity to tissue.

Methods

The absolute magnetic susceptibilities of different sections of rat brain, which were exsanguinated and perfusion‐fixed, have been measured in a commercial superconducting quantum interference device magnetometer operating in fields up to 7T.

Results

The average measured values ranged from −(9.51 ± 0.01) × 10−6 for the cerebellum to −(8.99 ± 0.01) × 10−6 for a mixture of hippocampus, corpus callosum, and striatum. The time evolution of the samples was also studied, and deviations of <1% were observed after 4 weeks, although this trend was sample‐specific.

Conclusion

The measured susceptibilities are close to the value measured for high‐performance liquid chromatography H2O and depend on the amount of gray and white matter regions present in the samples. Magn Reson Med 72:876–879, 2014. © 2013 Wiley Periodicals, Inc.
Free‐breathing cardiac MR stress perfusion with real‐time slice tracking
Authors: Basha Tamer A. , Roujol Sébastien , Kissinger Kraig V. , Goddu Beth , Berg Sophie , Manning Warren J. , Nezafat Reza
Published: October 2013

Purpose

To develop a free‐breathing cardiac MR perfusion sequence with slice tracking for use after physical exercise.

Methods

We propose to use a leading navigator, placed immediately before each 2D slice acquisition, for tracking the respiratory motion and updating the slice location in real‐time. The proposed sequence was used to acquire CMR perfusion datasets in 12 healthy adult subjects and 8 patients. Images were compared with the conventional perfusion (i.e., without slice tracking) results from the same subjects. The location and geometry of the myocardium were quantitatively analyzed, and the perfusion signal curves were calculated from both sequences to show the efficacy of the proposed sequence.

Results

The proposed sequence was significantly better compared with the conventional perfusion sequence in terms of qualitative image scores. Changes in the myocardial location and geometry decreased by 50% in the slice tracking sequence. Furthermore, the proposed sequence had signal curves that are smoother and less noisy.

Conclusion

The proposed sequence significantly reduces the effect of the respiratory motion on the image acquisition in both rest and stress perfusion scans. Magn Reson Med 72:689–698, 2014. © 2013 Wiley Periodicals, Inc.
Water‐selective excitation of short T2 species with binomial pulses
Authors: Deligianni Xeni , Bär Peter , Scheffler Klaus , Trattnig Siegfried , Bieri Oliver
Published: October 2013

Purpose

For imaging of fibrous musculoskeletal components, ultra‐short echo time methods are often combined with fat suppression. Due to the increased chemical shift, spectral excitation of water might become a favorable option at ultra‐high fields. Thus, this study aims to compare and explore short binomial excitation schemes for spectrally selective imaging of fibrous tissue components with short transverse relaxation time (T2).

Methods

Water selective 1‐1‐binomial excitation is compared with nonselective imaging using a sub‐millisecond spoiled gradient echo technique for in vivo imaging of fibrous tissue at 3T and 7T.

Results

Simulations indicate a maximum signal loss from binomial excitation of approximately 30% in the limit of very short T2 (0.1 ms), as compared to nonselective imaging; decreasing rapidly with increasing field strength and increasing T2, e.g., to 19% at 3T and 10% at 7T for T2 of 1 ms. In agreement with simulations, a binomial phase close to 90° yielded minimum signal loss: approximately 6% at 3T and close to 0% at 7T for menisci, and for ligaments 9% and 13%, respectively.

Conclusion

Overall, for imaging of short‐lived T2 components, short 1‐1 binomial excitation schemes prove to offer marginal signal loss especially at ultra‐high fields with overall improved scanning efficiency. Magn Reson Med 72:800–805, 2014. © 2013 Wiley Periodicals, Inc.
Effects of botulinum toxin type A on non‐injected bi‐articular muscle include a narrower length range of force exertion and increased passive force
Authors: Ateş Filiz , Yucesoy Can A.
Published: October 2013

Introduction: The goal of this study was to test the hypothesis that botulinum toxin type A (BTX‐A) injection in rat tibialis anterior (TA) muscle affects the mechanics of its bi‐articular synergist, both actively and passively. Methods: Two groups of Wistar rats were tested: control (no BTX‐A) and BTX (0.1 U of BTX‐A) animals were injected exclusively to the mid‐belly of TA. Extensor digitorum longus (EDL) muscle isometric forces were measured after proximal and distal lengthening. Results: Five days after injection, BTX‐A administration changed EDL mechanics: (1) active forces decreased (proximal muscle length dependently); (2) length range of active force exertion decreased both proximally and distally; and (3) passive muscle forces increased. Conclusions: Effects of BTX‐A appear to not be limited to decreased active muscle tone, but may cause also a narrower active range of movement and increased passive resistance. Through spread of BTX‐A to a bi‐articular muscle, such effects are plausible for both joints spanned. Muscle Nerve 49: 866–878, 2014
Activity rating scales in adult muscle disease: How well do they actually measure?
Authors: Seedat Farah , James Meredith K. , Rose Michael R.
Published: October 2013

Introduction: In an accompanying study we reported on the content of several activity rating scales that have been used for muscle disease. To further aid in achieving consensus we conducted a systematic review to assess the quality of the 19 activity rating scales designed specifically for muscle disease. Methods: We analyzed the measurement properties and the feasibility of the 19 instruments. Several databases were searched for studies relating to the quality of the instruments under review. Two independent reviewers selected studies and assessed instrument quality using pre‐agreed criteria based on published frameworks. Results: We found that none of the 19 instruments have sufficiently comprehensive reporting of measurement or feasibility performance as would be required by regulatory authorities. Conclusions: Further work is required urgently to address these deficiencies of reporting or acquiring additional data. Until then, there will remain a major barrier for translational research to overcome. Muscle Nerve 50: 24–33, 2014
De novo partial deletion in GRID2 presenting with complicated spastic paraplegia
Authors: Maier André , Klopocki Eva , Horn Denise , Tzschach Andreas , Holm Teresa , Meyer Robert , Meyer Thomas
Published: October 2013

Introduction: Complex forms of spastic paraplegia (SPG) are rare and genetically heterogeneous. In apparently sporadic cases, analysis of known SPG genes often fails to reveal a mutation. Methods: We report a 24‐year‐old patient with a syndrome of spastic paraplegia, ataxia, frontotemporal dementia, and lower motor neuron involvement. Results: Screening of the patient's genome for copy number variation identified a novel 276 kb deletion spanning the first exon of the GRID2 gene. MRI scan showed atrophy of the cerebellum, and electromyography revealed a chronic disorder of motor neurons or their axons. A deletion in GRID2, coding for the glutamate receptor delta‐2 subunit precursor protein, was excluded in either parent, suggesting that the deletion in the index patient occurred de novo. Conclusions: We hypothesize that the deletion identified here is the cause of our patient's clinical presentation, due to the resemblance to the GRID2 mutation phenotype in mouse models. Muscle Nerve 49: 289–292, 2014
Frictional contact algorithms in SPH for the simulation of soil–structure interaction
Authors: Wang Jian , Chan Dave
Published: October 2013

Simulation of frictional contact between soils and rigid or deformable structure in the framework of smoothed particle hydrodynamics (SPH) is presented in this study. Two algorithms are implemented into the SPH code to describe contact behavior, where the contact forces are calculated using the law of conservation of momentum based on ideal plastic collision or using the criteria of partial penetrating. In both algorithms, the problem of boundary deficiency inherited from SPH is properly handled so that the particles located at contact boundary can have precise acceleration, which is critical for contact detection. And the movement and rotation of the rigid structure are taken into account so that it is easy to simulate the process of pile driving or movement of a retaining wall in geotechnical engineering analysis. Furthermore, the capability of modeling deformability of a structure during frictional contact simulations broadens the fields of SPH application. In contrast to previous work dealing with contact in SPH, which usually use particle‐to‐particle contact or ignoring sliding between particles and solid structure, the method proposed here is more efficient and accurate, and it is suitable to simulate interaction between soft materials and rigid or deformable structures, which are very common in geotechnical engineering. A number of numerical tests are carried out to verify the accuracy and stability of the proposed algorithms, and their results are compared with analytical solutions or results from finite element method analysis. Good agreement obtained from these comparisons suggests that the proposed algorithms are robust and can be applied to extend the capability of SPH in solving geotechnical problems. Copyright © 2013 John Wiley & Sons, Ltd.
The effects of prolapse surgery on vaginal wall sensibility, vaginal vasocongestion, and sexual function: A prospective single centre study
Authors: Lakeman Marielle M. E. , Laan Ellen , Roovers Jan‐Paul W. R.
Published: October 2013

Aims

Prolapse surgery has been shown to positively alter body image and decrease pelvic floor symptoms, hereby possibly improving sexual function. However, the surgical trauma itself may adversely affect sexual function, by damaging vaginal innervation and vascularization. The aim of this study is to evaluate the effects of vaginal prolapse surgery on vaginal vasocongestion, vaginal wall sensibility, and sexual function.

Methods

A prospective study was performed, including patients scheduled for vaginal prolapse surgery. Participants underwent measurements before and 6 months after surgery, during non‐erotic and erotic visual stimuli. Measurements were performed using a vaginal combi‐probe which includes vaginal photoplethysmography to assess vaginal pulse amplitude (VPA) (representing vaginal vasocongestion), and four pulse‐generating electrodes to measure vaginal wall sensibility (representing vaginal innervation). Sexual function was assessed using validated questionnaires (FSFI, FSDS‐R, SSAQ).

Results

Twenty‐nine women were included, 24 (83%) completed the 6 months follow‐up. VPA analysis showed a significant reduction in vaginal vasocongestion during sexual stimulation post‐operatively (pre‐op 2.4 mV (SD 2.5) vs. post‐op 1.7 mV (SD 2.4), P = 0.05). Vaginal wall sensibility in the cranial posterior vaginal wall was significantly reduced after surgery (pre‐op 13.3 mA vs. post‐op 17.5 mA, P < 0.05). Vaginal wall sensibility in the other three locations was not affected by surgery. Sexual function as assessed with questionnaires, was not significantly affected.

Conclusion

Prolapse surgery negatively impacted levels of vaginal vasocongestion during erotic stimuli as well as vaginal wall sensibility in the cranial posterior wall. Future studies are needed to tease out if these changes in physiological factors are relevant for subjective sexual function. Neurourol. Urodynam. 33:1217–1224, 2014. © 2013 Wiley Periodicals, Inc.
Quantitative proton MR techniques for measuring fat
Authors: Hu H. H. , Kan H. E.
Published: October 2013

Accurate, precise and reliable techniques for the quantification of body and organ fat distributions are important tools in physiology research. They are critically needed in studies of obesity and diseases involving excess fat accumulation. Proton MR methods address this need by providing an array of relaxometry‐based (T1, T2) and chemical shift‐based approaches. These techniques can generate informative visualizations of regional and whole‐body fat distributions, yield measurements of fat volumes within specific body depots and quantify fat accumulation in abdominal organs and muscles. MR methods are commonly used to investigate the role of fat in nutrition and metabolism, to measure the efficacy of short‐ and long‐term dietary and exercise interventions, to study the implications of fat in organ steatosis and muscular dystrophies and to elucidate pathophysiological mechanisms in the context of obesity and its comorbidities. The purpose of this review is to provide a summary of mainstream MR strategies for fat quantification. The article succinctly describes the principles that differentiate water and fat proton signals, summarizes the advantages and limitations of various techniques and offers a few illustrative examples. The article also highlights recent efforts in the MR of brown adipose tissue and concludes by briefly discussing some future research directions. Copyright © 2013 John Wiley & Sons, Ltd.
Cerebral blood flow response to acute hypoxic hypoxia
Authors: Harris Ashley D. , Murphy Kevin , Diaz Claris M. , Saxena Neeraj , Hall Judith E. , Liu Thomas T. , Wise Richard G.
Published: October 2013

Hypoxic hypoxia (inspiratory hypoxia) stimulates an increase in cerebral blood flow (CBF) maintaining oxygen delivery to the brain. However, this response, particularly at the tissue level, is not well characterised. This study quantifies the CBF response to acute hypoxic hypoxia in healthy subjects. A 20‐min hypoxic (mean PETo2 = 52 mmHg) challenge was induced and controlled by dynamic end‐tidal forcing whilst CBF was measured using pulsed arterial spin labelling perfusion MRI. The rate constant, temporal delay and magnitude of the CBF response were characterised using an exponential model for whole‐brain and regional grey matter. Grey matter CBF increased from 76.1 mL/100 g/min (95% confidence interval (CI) of fitting: 75.5 mL/100 g/min, 76.7 mL/100 g/min) to 87.8 mL/100 g/min (95% CI: 86.7 mL/100 g/min, 89.6 mL/100 g/min) during hypoxia, and the temporal delay and rate constant for the response to hypoxia were 185 s (95% CI: 132 s, 230 s) and 0.0035 s–1 (95% CI: 0.0019 s–1, 0.0046 s–1), respectively. Recovery from hypoxia was faster with a delay of 20 s (95% CI: –38 s, 38 s) and a rate constant of 0.0069 s–1 (95% CI: 0.0020 s–1, 0.0103 s–1). R2*, an index of blood oxygenation obtained simultaneously with the CBF measurement, increased from 30.33 s–1 (CI: 30.31 s–1, 30.34 s–1) to 31.48 s–1 (CI: 31.47 s–1, 31.49 s–1) with hypoxia. The delay and rate constant for changes in R2* were 24 s (95% CI: 21 s, 26 s) and 0.0392 s–1 (95% CI: 0.0333 s–1, 0.045 s–1 ), respectively, for the hypoxic response, and 12 s (95% CI: 10 s, 13 s) and 0.0921 s–1 (95% CI: 0.0744 s–1, 0.1098 s–1/) during the return to normoxia, confirming rapid changes in blood oxygenation with the end‐tidal forcing system. CBF and R2* reactivity to hypoxia differed between subjects, but only R2* reactivity to hypoxia differed significantly between brain regions. © 2013 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd.
q‐Space diffusion MRI (QSI) of the disease progression in the spinal cords of the Long Evans shaker: diffusion time and apparent anisotropy
Authors: Anaby Debbie , Duncan Ian D. , Smith Chelsey M. , Cohen Yoram
Published: October 2013

q‐Space diffusion MRI (QSI) was used to study the spinal cords of Long Evans shaker (les) rats, a model of dysmyelination, and their age‐matched controls at different maturation stages. Diffusion was measured parallel and perpendicular to the fibers of the spinal cords of the two groups and at different diffusion times. The results showed that QSI is able to detect the dysmyelination process that occurs in this model in the different stages of the disease. The differences in the diffusion characteristics of the spinal cords of the two groups were found to be larger when the diffusion time was increased from 22 to 100 ms. We found that the radial mean displacement is a much better parameter than the QSI fractional anisotropy (FA) to document the differences between the two groups. We observed that the degree of myelination affects the diffusion characteristics of the tissues, but has a smaller effect on FA. All of the extracted diffusion parameters that are affected by the degree of myelination are affected in a diffusion time‐dependent fashion, suggesting that the terms apparent anisotropy, apparent fractional anisotropy and even apparent root‐mean‐square displacement (rmsD) are more appropriate. Copyright © 2013 John Wiley & Sons, Ltd.
A survey of autonomic networking architectures: towards a Unified Management Framework
Authors: Tsagkaris Kostas , Nguengang Gerard , Galani Aristi , Grida Ben Yahia Imen , Ghader Majid , Kaloxylos Alexandros , Gruber Markus , Kousaridas Apostolis , Bouet Mathieu , Georgoulas Stylianos , Bantouna Aimilia , Alonistioti Nancy , Demestichas Panagiotis
Published: October 2013

Academic and industrial research initiatives have sought to make fully autonomic networks a reality. Some of these initiatives pursued a holistic approach, while others focused on setting up functionalities for specific networking domains. These efforts did not succeed in being extensively deployed, because the goals of network operators were not satisfactorily met. These goals include unification of management operations, enablement of end‐to‐end management and enhancement of the overall system performance in a trusted way, while reducing management cost. In this paper, we analyse a set of existing autonomic management architectures and frameworks with respect to a selected set of criteria. We then identify missing parts and challenges and propose a framework to unify the most promising attributes towards a novel approach of realization of autonomic networking management. We call this proposal Unified Management Framework (UMF). Copyright © 2013 John Wiley & Sons, Ltd.
Robust capacity assignment solutions for telecommunications networks with uncertain demands
Authors: Babonneau F. , Vial J.‐P. , Klopfenstein O. , Ouorou A.
Published: October 2013

We consider the capacity planning of telecommunications networks with linear investment costs and uncertain future traffic demands. Transmission capacities must be large enough to meet, with a high quality of service (QoS), the range of possible demands, after adequate routings of the traffic on the created network. We use the robust optimization methodology to balance the need for a given QoS with the cost of investment. Our model assumes that the traffic for each individual demand fluctuates in an interval around a nominal value. We use a refined version of affine decision rules based on a concept of demand proximity to model the routings as affine functions of the demand realizations. We then give a probabilistic analysis assuming the random variables follow a triangular distribution. Finally, we perform numerical experiments on network instances from Survivable fixed telecommunication Network Design Library (SNDlib) and measure the quality of the solutions by simulation. Copyright © 2013 Wiley Periodicals, Inc. NETWORKS, Vol. 62(4), 255–272 2013
A maritime inventory routing problem: Discrete time formulations and valid inequalities
Authors: Agra Agostinho , Andersson Henrik , Christiansen Marielle , Wolsey Laurence
Published: October 2013

A single‐product maritime inventory routing problem (MIRP) is studied in which the production and consumption rates vary over the planning horizon. The problem involves a heterogeneous fleet and multiple production and consumption ports with limited storage capacity. Two discrete time formulations are developed: an original model and a reformulated model that is a pure fixed charge network flow (FCNF) model with side constraints. Mixed integer sets arising from the decomposition of the formulations are identified. In particular, several lot‐sizing relaxations are derived for the formulations and used to establish valid inequalities to strengthen the proposed formulations. Until now, the derivation of models and valid inequalities for MIRPs has mainly been inspired by the developments in the routing community. Here, we have developed a new model leading to new valid inequalities for MIRPs obtained by generalizing valid inequalities from the recent lot‐sizing literature. Considering a set of instances based on real data, a computational study is conducted to test the formulations and the effectiveness of the valid inequalities. The FCNF formulation is generally much stronger than the original formulation. The developed valid inequalities reduce the integrality gap significantly for both formulations. By using a branch‐and‐bound scheme based on the strengthened FCNF formulation, most of our test instances are solved to optimality. © 2013 Wiley Periodicals, Inc. NETWORKS, Vol. 62(4), 297–314 2013
The split delivery capacitated team orienteering problem
Authors: Archetti C. , Bianchessi N. , Speranza M.G. , Hertz A.
Published: October 2013

In this article, we study the capacitated team orienteering problem where split deliveries are allowed. A set of potential customers is given, each associated with a demand and a profit. The set of customers to be served by a fleet of capacitated vehicles has to be identified in such a way that the profit collected is maximized, while satisfying constraints on the maximum time duration of each route and the vehicle capacity constraints. When split deliveries are allowed, each customer may be served by more than one vehicle. We show that the profit collected by allowing split deliveries may be as large as twice the profit collected under the constraint that each customer has to be served by one vehicle at most. We then present a branch‐and‐price exact algorithm and a hybrid heuristic. We show the effectiveness of the proposed approaches on benchmark instances and on a new set of instances that allow us to computationally evaluate the impact of split deliveries. © 2013 Wiley Periodicals, Inc. NETWORKS, Vol. 63(1), 16–33 2014
A detailed description of the Gurson–Tvergaard–Needleman model within a mixed velocity–pressure finite element formulation
Authors: Cao T.‐S. , Montmitonnet P. , Bouchard P.‐O.
Published: October 2013

In an effort to implement Gurson‐type models into a mixed velocity–pressure finite element formulation with the MINI‐element P1 +  ∕ P1, the algorithm proposed by Aravas (IJNME, 1987) to integrate the pressure dependent plasticity as well as the formulations of consistent tangent moduli have been analyzed. This work firstly reviews and clarifies the mathematical basis of the formulations used by Aravas (IJNME, 1987) and demonstrates the equality of the tangent moduli formulations proposed by Govindarajan and Aravas (CNME, 1995) and Zhang (CMAME, 1995), which are widely used in the literature. A unified formulation to calculate the tangent moduli is proven, and its accuracy is also investigated by the finite difference method. The implementation of the Gurson–Tvergaard–Needleman model is then detailed for the mixed velocity–pressure finite element formulation, which employs the MINI‐element P1 +  ∕ P1. Due to the particularity of this element, one needs to calculate two tangent moduli instead of one. The formulas for calculating the ‘linear tangent modulus’ and the ‘bubble tangent modulus’ are then detailed. Finally, comparison tests are carried out with ABAQUS (Dassault System, Simulia Corp., Providence, RI, USA) in order to validate the present implementation for both homogeneous and heterogeneous deformations. Copyright © 2013 John Wiley & Sons, Ltd.
Global 2D digital image correlation for motion estimation in a finite element framework: a variational formulation and a regularized, pyramidal, multi‐grid implementation
Authors: Fedele R. , Galantucci L. , Ciani A.
Published: October 2013

In this study, the inverse problem of reconstructing the in‐plane (2D) displacements of a monitored surface through a sequence of two‐dimensional digital images, severely ill‐posed in Hadamard's sense, is deeply investigated. A novel variational formulation is presented for the continuum 2D digital image correlation problem, and critical issues such as semi‐coercivity and solution multiplicity are discussed by functional analysis tools. In the framework of a Galerkin, finite element discretization of the displacement field, a robust implementation for 2D digital image correlation is outlined, aiming to attenuate the spurious oscillations which corrupt the deformation scenario, especially when very fine meshes are adopted. Recourse is made to a hierarchical family of grids linked by suitable restriction and prolongation operators and defined over an image pyramid. Multi‐grid cycles are performed ascending and descending along the pyramid, with only one Newton iteration per level irrespective of the tolerance satisfaction, as if the problem were linear. At each level, the conventional least‐square matching functional is herein enriched by a Tychonoff regularization provision, preserving the solution against an unstable response. The algorithm is assessed on the basis of both synthetic and truly experimental image pairs. Copyright © 2013 John Wiley & Sons, Ltd.
Finite volume element approximation of the coupled continuum pipe‐flow/Darcy model for flows in karst aquifers
Authors: Liu Wei , Kang Zhijiang , Rui Hongxing
Published: October 2013

A finite volume element method is applied to approximate the continuum pipe‐flow/Darcy problem, which models the coupled conduit flow and porous media flow in Karst aquifers. A decoupled scheme is proposed for solving the coupled discretization problem. Optimal error estimates in L2 norm and H1 norm are given in this article. Some numerical examples are presented to verify the theoretical results and demonstrate the effectiveness of the decoupling approach. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 376–392, 2014
A Multilevel Analysis of the Effects of the Practice Environment Scale of the Nursing Work Index on Nurse Outcomes
Authors: Gabriel Allison S. , Erickson Rebecca J. , Moran Christina M. , Diefendorff James M. , Bromley Gail E.
Published: October 2013

Few researchers have examined how the components of the Practice Environment Scale of the Nursing Work Index (PES‐NWI) relate to nurses' well‐being at multiple organizational levels. The objective of the study was to perform a multilevel assessment of the relationships of the PES‐NWI subscales with three nurse outcomes: job satisfaction, emotional exhaustion, and turnover intentions. Additionally, we tested the multilevel factor structure of the PES‐NWI. In a sample of 699 full‐time registered nurses in 79 units and 9 branches of a hospital system, relationships of the NWI with nurse outcomes were fairly consistent across levels of analysis. However, subscales contributed differently to the three outcomes, demonstrating the complexity of environmental influences on nurses' work experience. © 2013 Wiley Periodicals, Inc. Res Nurs Health 36: 567–581, 2013
A risk algorithm for assessing short–term mortality for obese black and white men and women
Authors: Lakoski Susan G. , Mallick Himel , McClure Leslie A. , Safford Monika , Kissela Brett , Howard George , Cushman Mary
Published: October 2013

Objective

To develop and validate a mortality risk algorithm for obese black and white men and women to elucidate risk factors prognostic of short‐term mortality among obese persons.

Methods

Prospective cohort study. Reasons for geographic and racial differences in stroke (REGARDS) study, is a cohort of black and white men and women aged ≥45 years. Obese (≥30 kg m−2) participants in REGARDS (n = 11 288) were randomly assigned to the derivation data set or an independent validation set.

Results

During the mean follow‐up period of 4.9 years, 8.9% (n = 504) in the derivation cohort and 8.7% (n = 492) in the validation cohort died. The best‐fitting model based on data from the derivation cohort included demographic (age, sex), coronary heart disease (CHD) conditions (diabetes, systolic blood pressure, history of CHD), health behaviors (smoking, physical activity, alcohol use), and socioeconomic variables (income, use of physician services). The C‐statistic when the model was applied to the validation cohort was 0.80. Observed and predicted rates of mortality were similar across deciles of mortality risk by race.

Conclusions

A risk algorithm was established and validated to predict mortality among black and white obese subjects based on CHD risk factors, behavioral risk factors, and socioeconomic status.
Hepatic insulin clearance is the primary determinant of insulin sensitivity in the normal dog
Authors: Ader Marilyn , Stefanovski Darko , Kim Stella P. , Richey Joyce M. , Ionut Viorica , Catalano Karyn J. , Hucking Katrin , Ellmerer Martin , Van Citters Gregg , Hsu Isabel R. , Chiu Jenny D. , Woolcott Orison O. , Harrison Lisa N. , Zheng Dan , Lottati Maya , Kolka Cathryn M. , Mooradian Vahe , Dittmann Justin , Yae Sophia , Liu Huiwen , Castro Ana Valeria B. , Kabir Morvarid , Bergman Richard N.
Published: October 2013

Objective

Insulin resistance is a powerful risk factor for Type 2 diabetes and a constellation of chronic diseases, and is most commonly associated with obesity. We examined if factors other than obesity are more substantial predictors of insulin sensitivity under baseline, nonstimulated conditions.

Methods

Metabolic assessment was performed in healthy dogs (n = 90). Whole‐body sensitivity from euglycemic clamps (SICLAMP) was the primary outcome variable, and was measured independently by IVGTT (n = 36). Adiposity was measured by MRI (n = 90), and glucose‐stimulated insulin response was measured from hyperglycemic clamp or IVGTT (n = 86 and 36, respectively).

Results

SICLAMP was highly variable (5.9‐75.9 dl/min per kg per μU/ml). Despite narrow range of body weight (mean, 28.7 ± 0.3 kg), adiposity varied approximately eight‐fold and was inversely correlated with SICLAMP (P < 0.025). SICLAMP was negatively associated with fasting insulin, but most strongly associated with insulin clearance. Clearance was the dominant factor associated with sensitivity (r = 0.53, P < 0.00001), whether calculated from clamp or IVGTT.

Conclusions

These data suggest that insulin clearance contributes substantially to insulin sensitivity, and may be pivotal in understanding the pathogenesis of insulin resistance. We propose the hyperinsulinemia due to reduction in insulin clearance is responsible for insulin resistance secondary to changes in body weight.
Cord blood levels of osteopontin as a phenotype marker of gestational age and neonatal morbidities
Authors: Joung Kyoung Eun , Christou Helen , Park Kyung‐Hee , Mantzoros Christos S.
Published: October 2013

Objectives

Osteopontin (OPN) is a proinflammatory cytokine associated with metabolic syndrome. Extreme birth weight categories including small for gestational age (SGA), and large for gestational age (LGA) are risk factors for metabolic syndrome. However normal levels of plasma OPN in neonates and the relationship of OPN to fetal growth remain unknown. We evaluated the association of umbilical cord blood OPN with gestational age, birth weight, and neonatal outcomes.

Methods

A cross‐sectional study of 261 newborns of all gestational ages beginning at week 26, and 26 adults for comparison was performed. Umbilical cord blood from newborns and analyzed plasma for OPN by ELISA was collected.

Results

Plasma OPN was significantly higher in neonates (414.65 ± 136.72 ng/mL) compared to adults (33.37 ± 14.66 ng/mL, P < 0.001). There was an inverse correlation between OPN and gestational age (r = −0.48, P < 0.0001). LGA infants had lower OPN than appropriate for gestational age (AGA) infants, but LGA was not an independent predictor of OPN in multivariate analysis. Among preterm infants, patent ductus arteriosus (PDA) was independently associated with higher OPN (OR = 2.49, P = 0.02).

Conclusion

Our results raise the possibility that OPN has a physiologic role in fetal growth and development, and may be a useful biomarker for PDA.