bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leg blood flow is impaired during small muscle mass exercise in patients with COPD
Authors: Iepsen U. W. , Munch G. W. , Rugbjerg M. , Ryrsø C. K. , Secher N. H. , Hellsten Y. , Lange P. , Pedersen B. K. , Thaning P. , Mortensen S. P. 
Published: July 2017

Skeletal muscle blood flow is regulated to match the oxygen demand and dysregulation could contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). We measured leg hemodynamics and metabolites from vasoactive compounds in muscle interstitial fluid and plasma at rest, during one-legged knee-extensor exercise, and during arterial infusions of sodium nitroprusside (SNP) and acetylcholine (ACh), respectively. Ten patients with moderate to severe COPD and eight age- and sex-matched healthy controls were studied. During knee-extensor exercise (10 W), leg blood flow was lower in the patients compared with the controls (1.82 ± 0.11 vs. 2.36 ± 0.14 l/min, respectively; P < 0.05), which compromised leg oxygen delivery (372 ± 26 vs. 453 ± 32 ml O2/min, respectively; P < 0.05). At rest, plasma endothelin-1 (vasoconstrictor) was higher in the patients with COPD ( P < 0.05) and also tended to be higher during exercise ( P = 0.07), whereas the formation of interstitial prostacyclin (vasodilator) was only increased in the controls. There was no difference between groups in the nitrite/nitrate levels (vasodilator) in plasma or interstitial fluid during exercise. Moreover, patients and controls showed similar vasodilatory capacity in response to both endothelium-independent (SNP) and endothelium-dependent (ACh) stimulation. The results suggest that leg muscle blood flow is impaired during small muscle mass exercise in patients with COPD possibly due to impaired formation of prostacyclin and increased levels of endothelin-1. NEW & NOTEWORTHY This study demonstrates that chronic obstructive pulmonary disease (COPD) is associated with a reduced blood flow to skeletal muscle during small muscle mass exercise. In contrast to healthy individuals, interstitial prostacyclin levels did not increase during exercise and plasma endothelin-1 levels were higher in the patients with COPD.
Effects of acute hypoxia on human cognitive processing: a study using ERPs and SEPs
Authors: Nakata Hiroki , Miyamoto Tadayoshi , Ogoh Shigehiko , Kakigi Ryusuke , Shibasaki Manabu 
Published: July 2017

Although hypoxia has the potential to impair the cognitive function, the effects of acute hypoxia on the high-order brain function (executive and/or inhibitory processing) and somatosensory ascending processing remain unknown. We tested the hypothesis that acute hypoxia impairs both motor executive and inhibitory processing and somatosensory ascending processing. Fifteen healthy subjects performed two sessions ( sessions 1 and 2), consisting of electroencephalographic event-related potentials with somatosensory Go/No-go paradigms and somatosensory-evoked potentials (SEPs) under two conditions (hypoxia and normoxia) on different days. On 1 day, participants breathed room air in the first and second sessions of the experiment; on the other day, participants breathed room air in the first session, and 12% O2 in the second session. Acute hypoxia reduced the peak amplitudes of Go-P300 and No-go-P300, and delayed the peak latency of Go-P300. However, no significant differences were observed in the peak amplitude or latency of N140, behavioral data, or the amplitudes and latencies of individual SEP components between the two conditions. These results suggest that acute hypoxia impaired neural activity in motor executive and inhibitory processing, and delayed higher cognitive processing for motor execution, whereas neural activity in somatosensory processing was not affected by acute hypoxia. NEW & NOTEWORTHY Hypoxia has the potential to impair the cognitive function, but the effects of acute hypoxia on the cognitive function remain debatable. We investigated the effects of acute hypoxia on human cognitive processing using electroencephalographic event-related potentials and somatosensory-evoked potentials. Acute normobaric hypoxia impaired neural activity in motor executive and inhibitory processing, but no significant differences were observed in neural activity in somatosensory processing.
Eupnea, tachypnea, and autoresuscitation in a closed-loop respiratory control model
Authors: Diekman Casey O. , Thomas Peter J. , Wilson Christopher G. 
Published: July 2017

How sensory information influences the dynamics of rhythm generation varies across systems, and general principles for understanding this aspect of motor control are lacking. Determining the origin of respiratory rhythm generation is challenging because the mechanisms in a central circuit considered in isolation may be different from those in the intact organism. We analyze a closed-loop respiratory control model incorporating a central pattern generator (CPG), the Butera-Rinzel-Smith (BRS) model, together with lung mechanics, oxygen handling, and chemosensory components. We show that 1) embedding the BRS model neuron in a control loop creates a bistable system; 2) although closed-loop and open-loop (isolated) CPG systems both support eupnea-like bursting activity, they do so via distinct mechanisms; 3) chemosensory feedback in the closed loop improves robustness to variable metabolic demand; 4) the BRS model conductances provide an autoresuscitation mechanism for recovery from transient interruption of chemosensory feedback; and 5) the in vitro brain stem CPG slice responds to hypoxia with transient bursting that is qualitatively similar to in silico autoresuscitation. Bistability of bursting and tonic spiking in the closed-loop system corresponds to coexistence of eupnea-like breathing, with normal minute ventilation and blood oxygen level and a tachypnea-like state, with pathologically reduced minute ventilation and critically low blood oxygen. Disruption of the normal breathing rhythm, through either imposition of hypoxia or interruption of chemosensory feedback, can push the system from the eupneic state into the tachypneic state. We use geometric singular perturbation theory to analyze the system dynamics at the boundary separating eupnea-like and tachypnea-like outcomes.NEW & NOTEWORTHY A common challenge facing rhythmic biological processes is the adaptive regulation of central pattern generator (CPG) activity in response to sensory feedback. We apply dynamical systems tools to understand several properties of a closed-loop respiratory control model, including the coexistence of normal and pathological breathing, robustness to changes in metabolic demand, spontaneous autoresuscitation in response to hypoxia, and the distinct mechanisms that underlie rhythmogenesis in the intact control circuit vs. the isolated, open-loop CPG.
Chronic pain alters spatiotemporal activation patterns of forearm muscle synergies during the development of grip force
Authors: Manickaraj Nagarajan , Bisset Leanne M. , Devanaboyina Venkata S. P. T. , Kavanagh Justin J. 
Published: July 2017

It is largely unknown how the CNS regulates multiple muscle systems in the presence of pain. This study used muscle synergy analysis to investigate multiple forearm muscles in individuals with chronic elbow pain during the development of grip force. Eleven individuals with chronic elbow pain and 11 healthy age-matched control subjects developed grip force to 15% and 30% of maximum voluntary contraction (MVC). Surface electromyography was obtained from six forearm muscles during force development before nonnegative matrix factorization was performed. The relationship between muscle synergies and standard clinical tests of elbow pain were examined by linear regression. During grip force development to 15% MVC the pain group had a lower number of forearm muscle synergies, increased similarity in spatial activation patterns, increased cocontraction of forearm flexors, and a greater magnitude of muscle weightings across the forearm when performing the task. During the 30% MVC grip the numbers of muscle synergies were the same for both groups; however, the pain group had lower activation and reduced variability in the timing of peak activation. The timing of peak activation was delayed in the pain group regardless of the task, and performing the grip in different wrist postures did not affect muscle synergy characteristics in either group. Although localized pain causes direct dysfunction of an affected muscle, this study provides evidence that the timing and amplitude of agonist and antagonist muscle activity are also affected with chronic pain. NEW & NOTEWORTHY Muscle activation patterns of individuals with chronic elbow pain are simplified compared with healthy individuals. This is apparent as individuals with pain exhibit fewer forearm muscle synergies, and increased similarity of activation patterns between forearm muscles, when performing pain-free isometric gripping. As such, even during pain-free tasks it is possible to observe changes in motor control in people with chronic pain.
Muscle disuse caused by botulinum toxin injection leads to increased central gain of the stretch reflex in the rat
Authors: Pingel Jessica , Hultborn Hans , Näslund-Koch Lui , Jensen Dennis B. , Wienecke Jacob , Nielsen Jens Bo 
Published: July 2017

Botulinum toxin (Btx) is used in children with cerebral palsy and in other neurological patients to diminish spasticity and reduce the risk of development of contractures. We investigated changes in the central gain of the stretch reflex circuitry in response to Btx injection in the triceps surae muscle in rats. Experiments were performed in 21 rats. Eight rats were a control group, and 13 rats were injected with 6 IU of Btx in the left triceps surae muscle. Two weeks after Btx injection, larger monosynaptic reflexes (MSR) were recorded from the left (injected) than the right (noninjected) L4 + L5 ventral roots following stimulation of the corresponding dorsal roots. A similar increase on the left side was observed in response to stimulation of descending motor tracts, suggesting that increased excitability of spinal motor neurons may at least partly explain the increased reflexes. However, significant changes were also observed in postactivation depression of the MSR, suggesting that plastic changes in transmission from Ia afferent to the motor neurons also may be involved. The data demonstrate that muscle paralysis induced by Btx injection is accompanied by plastic adaptations in the central stretch reflex circuitry, which counteract the antispastic effect of Btx.NEW & NOTEWORTHY Injection of botulinum toxin into ankle muscles causes increased gain of stretch reflex. This is caused by adaptive changes in regulation of transmitter release from Ia afferents and increased excitability of spinal motor neurons.
Intra- and intersegmental influences among central pattern generating networks in the walking system of the stick insect
Authors: Mantziaris Charalampos , Bockemühl Till , Holmes Philip , Borgmann Anke , Daun Silvia , Büschges Ansgar 
Published: July 2017

To efficiently move around, animals need to coordinate their limbs. Proper, context-dependent coupling among the neural networks underlying leg movement is necessary for generating intersegmental coordination. In the slow-walking stick insect, local sensory information is very important for shaping coordination. However, central coupling mechanisms among segmental central pattern generators (CPGs) may also contribute to this. Here, we analyzed the interactions between contralateral networks that drive the depressor trochanteris muscle of the legs in both isolated and interconnected deafferented thoracic ganglia of the stick insect on application of pilocarpine, a muscarinic acetylcholine receptor agonist. Our results show that depressor CPG activity is only weakly coupled between all segments. Intrasegmental phase relationships differ between the three isolated ganglia, and they are modified and stabilized when ganglia are interconnected. However, the coordination patterns that emerge do not resemble those observed during walking. Our findings are in line with recent studies and highlight the influence of sensory input on coordination in slowly walking insects. Finally, as a direct interaction between depressor CPG networks and contralateral motoneurons could not be observed, we hypothesize that coupling is based on interactions at the level of CPG interneurons.NEW & NOTEWORTHY Maintaining functional interleg coordination is vitally important as animals locomote through changing environments. The relative importance of central mechanisms vs. sensory feedback in this process is not well understood. We analyzed coordination among the neural networks generating leg movements in stick insect preparations lacking phasic sensory feedback. Under these conditions, the networks governing different legs were only weakly coupled. In stick insect, central connections alone are thus insufficient to produce the leg coordination observed behaviorally.
An impact evaluation of the FoodMate programme: Perspectives of homeless young people and staff
Authors: Meiklejohn Sarah J , Barbour Liza , Palermo Claire E 
Published: July 2017

Objectives: Food insecurity remains an issue for vulnerable populations in developed countries. The potential dietary and food security impacts of nutrition education programmes in Australia remain largely undocumented. This study investigated the impacts of an eight-session nutrition education programme delivered within community case management services for young people experiencing homelessness. Design and setting: A qualitative case study was undertaken in a community-based youth housing agency in Western Melbourne, Australia. Methods: Seven semi-structured interviews and two focus groups were conducted with a purposive sample of 10 past programme graduates and five youth service staff. Data were thematically analysed using a phenomenological lens. Results: The impacts of the programme were described by four themes: (1) the nutrition education programme created a platform for social engagement, (2) reduced reliance on emergency food relief for participants, (3) participants developed food-related knowledge and skills and (4) the programme was seen as a step towards food security for young people. These impacts were dependent on a myriad of personal and programme-related characteristics. Personal characteristics included participants’ intrinsic motivating factors to change their behaviours or a pre-existing interest in nutrition. Programme characteristics included the programme’s flexible structure and facilitation by caseworkers that were known to the young people. Conclusion: Study findings highlight the potential impacts of a nutrition education programme on dietary behaviours and food security status when embedded within community-based services.
Cockpit Displayed Traffic Information and Distributed Management in Air Traffic Control
Authors: Kreifeldt John G. 
Published: July 2017

The technical feasibility of graphically displaying information such as surrounding aircraft and navigation routes in the cockpit on a cathode ray tube has been suggested as a viable method for improving the safety, orderliness, and expeditiousness of the air traffic control system by distributing some of its management to the pilots equipped with this cockpit displayed traffic and navigation information (CDTI). Several years of experimental study of this Concept, using a three-cab simulator facility at NASA-Ames, have produced several consistent findings relating to system performance and pilot and controller work loads and opinions. These findings generally agree with those from other studies. The most consistent result is a considerable reduction in controller verbal work load without any appreciable increase in pilot verbal work load, although they may report an increase in visual work load. However, pilots tend to prefer distributed management to centralized management, while this is generally reversed for controllers. The reduced response delays in the system obtainable using CDT/ permit pilots to maintain their own spacing more closely and precisely than when depending entirely upon controller-issued radar vectors and speed commands. As a result, time between successive aircraft landings and its variability can be reduced, thereby increasing runway utilization. Limited findings suggest that CDTI-based benefits do not detract from system safety. On balance, distributed management offers significant advantages for air traffic control.
A Methodology for Quantifying the Effects of Aging on Perceptual-Motor Capability
Authors: Levison William H. 
Published: July 2017

A methodology is described for providing a quantitative description of the effects of aging on human perceptual-motor capability. Specifically, application of the experimental and analytical techniques of manual control is suggested so that these effects can be quantified in terms of the parameters of a model for human perception and control. Important and immediate contributions to the study of aging can be expected from application of the methodology outlined in this paper. First, measures of perceptual-motor performance that are expected to be more sensitive to the effects of age than those usually available will be obtained. Second, these measures will be interpretable in terms of a model for human information processing that has been validated extensively for subjects in the 20-to 40-year age bracket. Using this model, one would be able to predict the effects of aging on a variety of tasks. Finally, a basis would be developed for a functional (rather than chronological) description of aging.
Biomechanical Stresses as Related to Motion Trajectory of Lifting
Authors: Garg Arun , Sharma Deven , Chaffin Don B. , Schmidler John M. 
Published: July 2017

A laboratory study was conducted to assess the effects of lift angle on biomechanical stresses to the musculoskeletal system, and in particular, on the lower back. Male subjects were required to lift four different tote boxes from the floor to a height of 0.81 m using two different lifting techniques. Maximum acceptable weights were determined using a psychophysical method. The motion trajectory of lift was studied by means of stroboscopic photography. Moments and forces at various body joints were computed using a biomechanical strength model. Maximum acceptable weights were 16% (range = 9 to 23%) greater for the free-style lifting technique as compared with the squat method of lifting. There were large differences between the maximum acceptable weights and the "maximum permissible limits" recommended by NIOSH. The results showed that the subjects pulled the load toward the body when lifting psychophysically determined maximum weights. The lift angle increased with an increase in box width. The lift angle was greater for the free-style lifting method as compared with the squat lifting technique for lifting compact loads. Lifting at an angle resulted in a decrease in moment at the elbow, shoulder, L5IS1 disc, and hips, and an increase in moment at the knees and ankles. The estimated compressive force on the lumbar spine was, on the average, 11% lower for lifting at an angle as compared with a straight vertical lift.
Surgical Anatomy Does Not Affect the Progression of Intestinal Failure–Associated Liver Disease in Neonatal Piglets
Authors: Lavallee Celeste M. , Wizzard Pamela R. , Lansing Marihan , Vine Donna F. , Nation Patrick N. , Yap Jason Y. , Willing Benjamin P. , Wales Paul W. , Turner Justine M. 
Published: July 2017

AbstractBackground: Intestinal failure–associated liver disease (IFALD) causes significant morbidity in neonates with short bowel syndrome (SBS) dependent on parenteral nutrition (PN). Resected ileum, with loss of the ileocecal valve (ICV), is the most common anatomy in SBS, yet its impact on IFALD has not been adequately studied. Methods: Neonatal piglets were randomized to 75% intestinal resection with jejunocolic anastomosis (JC, n = 12), 75% resection with jejunoileal anastomosis and intact ICV (JI, n = 13), PN‐fed sham (sham, n = 14), or sow‐fed control (SF, n = 8). Surgical and sham piglets received 100% PN for 14 days before bile flow was measured and blood chemistry, liver pathology, jejunal permeability, and bacterial translocation were assessed. Results: Bile flow was lower for PN‐fed compared with SF (P = .002) but not different between the PN‐fed groups. Total bilirubin (P = .03) and liver pathology (P < .001) were greater in PN‐fed than SF groups but not different between PN‐fed groups. Serum bile acids were increased in sham (P = .01) but not different between SBS groups. PN‐fed piglets with sepsis had lower bile flow (P = .001) and increased bilirubin (P = .04). Neither jejunal permeability nor bacterial translocation were different between JC, JI, or sham groups. Conclusion: Contrary to our hypothesis, the remnant anatomy does not appear to worsen the progression of IFALD. However, the role of sepsis in IFALD should be further explored, in addition to other mechanisms, including PN factors, host immune responses, and intestinal bacterial dysbiosis.
Optimal sizing of iliac vein stents
Authors: Raju Seshadri , Buck William J , Crim William , Jayaraj Arjun 
Published: July 2017

Background Iliac vein stenting has emerged as a therapeutic option in chronic venous disease. The optimal stent size is unknown but should match normal caliber at a minimum. Methods Teleology: The iliac-femoral outflow caliber was measured by Duplex in healthy volunteers to determine normal caliber. Patient IVUS data: The distribution curve of IVUS planimetry data in 345 chronic venous disease limbs was analyzed: values at the right tail end of the curve should approach normal values according to distribution theory. The optimal stent size was also projected using Poiseuille equation and Young’s scaling rule. Results The optimal stent sizes in the common iliac, external iliac, and common femoral vein segments are: 16, 14, and 12 mm diameters, respectively. Conclusion Stent correction of iliac vein stenosis should aim to restore the lumen to the minimum recommended caliber during the initial procedure and later re-interventions.
Towards an individualized management strategy for patients with chronic venous disease: Results of a Delphi consensus
Authors: van der Velden SK , van den Bos RR , Pichot O , Nijsten T , De Maeseneer MGR 
Published: July 2017

Objective To obtain consensus on management criteria for symptomatic patients with chronic venous disease (CVD; C2–C6) and superficial venous reflux. Method We used a Delphi method by means of 36 statements sent by email to experts in the field of phlebology across the world over the course of three rounds. The statements addressed criteria for different venous treatments in patients with different characteristics (e.g. extensive comorbidities, morbid obesity and peripheral arterial disease). If at least 70% of the ratings for a specific statement were between 6 and 9 (agreement) or between 1 and 3 (disagreement), experts’ consensus was reached. Results Twenty-five experts were invited to participate, of whom 24 accepted and completed all three rounds. Consensus was reached in 25/32 statements (78%). However, several statements addressing UGFS, single phlebectomies, patients with extensive comorbidities and morbid obesity remained equivocal. Conclusion Considerable consensus was reached within a group of experts but also some gaps in available research were highlighted.