oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Spin Wheel  [PDF]
S. R. Mane
Physics , 2015,
Abstract: A distillation of Koop's idea of the Spin Wheel.
Treadmill Experience Alters Treadmill Effects on Perceived Visual Motion  [PDF]
Yoshiko Yabe,Hama Watanabe,Gentaro Taga
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0021642
Abstract: Information on ongoing body movements can affect the perception of ambiguous visual motion. Previous studies on “treadmill capture” have shown that treadmill walking biases the perception of ambiguous apparent motion in backward direction in accordance with the optic flow during normal walking, and that long-term treadmill experience changes the effect of treadmill capture. To understand the underlying mechanisms for these phenomena, we conducted Experiment 1 with non-treadmill runners and Experiment 2 with treadmill runners. The participants judged the motion direction of the apparent motion stimuli of horizontal gratings in front of their feet under three conditions: walking on a treadmill, standing on a treadmill, and standing on the floor. The non-treadmill runners showed the presence of downward bias only under the walking condition, indicating that ongoing treadmill walking but not the awareness of being on a treadmill biased the visual directional discrimination. In contrast, the treadmill runners showed no downward bias under any of the conditions, indicating that neither ongoing activity nor the awareness of spatial context produced perception bias. This suggests that the long-term repetitive experience of treadmill walking without optic flow induced the formation of a treadmill-specific locomotor-visual linkage to perceive the complex relationship between self and the environment.
Treadmill Exercise Induces Hippocampal Astroglial Alterations in Rats  [PDF]
Caren Bernardi,Ana Carolina Tramontina,Patrícia Nardin,Regina Biasibetti,Ana Paula Costa,Adriana Fernanda Vizueti,Cristiane Batassini,Lucas Silva Tortorelli,Krista Minéia Wartchow,Márcio Ferreira Dutra,Larissa Bobermin,Patrícia Sesterheim,André Quincozes-Santos,Jaqueline de Souza,Carlos Alberto Gon?alves
Neural Plasticity , 2013, DOI: 10.1155/2013/709732
Abstract: Physical exercise effects on brain health and cognitive performance have been described. Synaptic remodeling in hippocampus induced by physical exercise has been described in animal models, but the underlying mechanisms remain poorly understood. Changes in astrocytes, the glial cells involved in synaptic remodeling, need more characterization. We investigated the effect of moderate treadmill exercise (20?min/day) for 4 weeks on some parameters of astrocytic activity in rat hippocampal slices, namely, glial fibrillary acidic protein (GFAP), glutamate uptake and glutamine synthetase (GS) activities, glutathione content, and S100B protein content and secretion, as well as brain-derived neurotrophic factor (BDNF) levels and glucose uptake activity in this tissue. Results show that moderate treadmill exercise was able to induce a decrease in GFAP content (evaluated by ELISA and immunohistochemistry) and an increase in GS activity. These changes could be mediated by corticosterone, whose levels were elevated in serum. BDNF, another putative mediator, was not altered in hippocampal tissue. Moreover, treadmill exercise caused a decrease in NO content. Our data indicate specific changes in astrocyte markers induced by physical exercise, the importance of studying astrocytes for understanding brain plasticity, as well as reinforce the relevance of physical exercise as a neuroprotective strategy. 1. Introduction Studies have shown that physical exercise can have profound effects on cardiovascular, pulmonary, and the musculoskeletal system, as well as the central nervous system (CNS) [1, 2]. Moderate physical activity improves memory and learning [3–8] and is associated with a lower risk for Alzheimer's dementia [9], Parkinson's disease [10] and other types of neurodegenerative diseases [2]. One of the regions of CNS more affected by exercise is the hippocampus. A putative mechanism, through which the exercise exerts its effects on the hippocampus, is the induction of brain-derived neurotrophic factor (BDNF) [11]. Astrocytes, the most abundant glial cells, particularly those of the glutamatergic type, are very important elements in neurotransmission [12, 13] and antioxidant defense, and this action involves the synthesis and secretion of glutathione (GSH) [14]. These cells are responsible for glutamate removal from the synaptic cleft and its conversion, through glutamine synthetase (GS) catalysis, into glutamine for replacement in the neurons. Moreover, increments in energy demand and functional activity during exercise may require functional and structural
RU486 did not exacerbate cytokine release in mice challenged with LPS nor in db/db mice
Yang Baichun,Trump Ryan P,Shen Ying,McNulty Judi A
BMC Pharmacology , 2008, DOI: 10.1186/1471-2210-8-7
Abstract: Background Glucocorticoids down-regulate cytokine synthesis and suppress inflammatory responses. The glucocorticoid receptor (GR) antagonist RU486 may exacerbate the inflammatory response, and concerns over this exacerbation have limited the development and clinical use of GR antagonists in the treatment of diabetes and depression. We investigated the effects of RU486 on serum cytokines in db/db mice and on lipopolysaccharide (LPS)-induced circulating TNFα levels in both normal AKR mice and diet-induced obese (DIO) C57BL/6 mice. Results Chronic treatment of db/db mice with RU486 dose-dependently decreased blood glucose, increased serum corticosterone and ACTH, but did not affect serum MCP-1 and IL-6 levels. LPS dose-dependently increased serum TNFα in both AKR and C57BL/6 DIO mice, along with increased circulating corticosterone and ACTH. Pretreatment of the mice with RU486 dose-dependently suppressed the LPS induced increases in serum TNFα and further increased serum corticosterone. Conclusion RU486 at doses that were efficacious in lowering blood glucose did not exacerbate cytokine release in these three mouse models. RU486 actually suppressed the lower dose LPS-mediated TNFα release, possibly due to the increased release of glucocorticoids.
On wheel-free graphs  [PDF]
Pierre Aboulker,Frédéric Havet,Nicolas Trotignon
Mathematics , 2013,
Abstract: A wheel is a graph formed by a chordless cycle and a vertex that has at least three neighbors in the cycle. We prove that every 3-connected graph that does not contain a wheel as a subgraph is in fact minimally 3-connected. We give a new proof of a theorem of Thomassen and Toft: every graph that does not contain a wheel as a subgraph is 3-colorable.
Wheel Random Apollonian Graphs  [PDF]
Piero Giacomelli
Computer Science , 2010,
Abstract: In this paper a subset of High-Dimensional Random Apollonian networks, that we called Wheel Random Apollonian Graphs (WRAG), is considered. We show how to generate a Wheel Random Apollonian Graph from a wheel graph. We analyse some basic graph properties like vertices and edges cardinality, some question concerning cycles and the chromaticity in such type of graphs, we suggest further work on this type of graphs.
Human treadmill walking needs attention
Jean Regnaux, Johanna Robertson, Djamel Smail, Olivier Daniel, Bernard Bussel
Journal of NeuroEngineering and Rehabilitation , 2006, DOI: 10.1186/1743-0003-3-19
Abstract: 11 healthy adult subjects were required to walk while simultaneously performing a RT task. Participants were instructed to bite a pressure transducer placed in the mouth as quickly as possible in response to an unpredictable electrical stimulation applied on the back of the neck. Each subject was tested under five different experimental conditions: simple RT task alone and while walking, recognition RT task alone and while walking, walking alone. A foot switch system composed of a pressure sensitive sensor was placed under the heel and forefoot of each foot to determine the gait cycle duration.Gait cycle duration was unchanged (p > 0.05) by the addition of the RT task. Regardless of the level of difficulty of the RT task, the RTs were longer during treadmill walking than in sitting conditions (p < 0.01) indicating that an increased amount of resources are required for the maintainance of walking performance on a treadmill at a steady state. No interaction (p > 0.05) was found between the attentional demand of the walking task and the decrement of performance found in the RT task under varying levels of difficulty. This finding suggests that the healthy subjects prioritized the control of walking at the expense of cognitive performance.We conclude that treadmill walking in young adults is not a purely automatic task. The methodology and outcome measures used in this study provide an assessment of the attentional resources required by walking on the treadmill at a steady state.A technique extensively used to study the neural processes involved in the control of walking in animals or in humans is walking on a treadmill [1]. This technique has also been proposed during the past decade as a training approach [2,3] to promote the recovery of locomotor function after a lesion of the central nervous system. It has been clearly demonstrated that non primate adult animals are able to "walk" and even adjust their gait patterns on a treadmill after transection of the spinal cor
Graphs with no induced wheel or antiwheel  [PDF]
Frédéric Maffray
Computer Science , 2015,
Abstract: A wheel is a graph that consists of a chordless cycle of length at least 4 plus a vertex with at least three neighbors on the cycle. It was shown recently that detecting induced wheels is an NP-complete problem. In contrast, it is shown here that graphs that contain no wheel and no antiwheel have a very simple structure and consequently can be recognized in polynomial time.
Corticosterone selectively decreases humoral immunity in female eiders during incubation  [PDF]
Sophie Bourgeon,Thierry Raclot
Quantitative Biology , 2007, DOI: 10.1242/jeb.02610
Abstract: Immunity is hypothesized to share limited resources with other physiological functions and this may partly account for the fitness costs of reproduction. Previous studies have shown that the acquired immunity of female common eider ducks (Somateria mollissima) is suppressed during their incubation, during which they entirely fast. Corticosterone was proposed to be an underlying physiological mechanism for such immunosuppression. Therefore, the current study aimed to assess the effects of exogenous corticosterone on acquired immunity in captive eiders. To this end, females were implanted with corticosterone pellets at different stages of their incubation fast. We measured total immunoglobulin levels, T-cell-mediated immune response, body mass and corticosterone levels in these females and compared them with those of control females prior to and after manipulation (i.e. corticosterone pellet implantation). To mimic corticosterone effects on body mass, we experimentally extended fasting duration in a group of females termed ;late fasters'...
Role of Corticosterone on Sleep Homeostasis Induced by REM Sleep Deprivation in Rats  [PDF]
Ricardo Borges Machado, Sergio Tufik, Deborah Suchecki
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0063520
Abstract: Sleep is regulated by humoral and homeostatic processes. If on one hand chronic elevation of stress hormones impair sleep, on the other hand, rapid eye movement (REM) sleep deprivation induces elevation of glucocorticoids and time of REM sleep during the recovery period. In the present study we sought to examine whether manipulations of corticosterone levels during REM sleep deprivation would alter the subsequent sleep rebound. Adult male Wistar rats were fit with electrodes for sleep monitoring and submitted to four days of REM sleep deprivation under repeated corticosterone or metyrapone (an inhibitor of corticosterone synthesis) administration. Sleep parameters were continuously recorded throughout the sleep deprivation period and during 3 days of sleep recovery. Plasma levels of adrenocorticotropic hormone and corticosterone were also evaluated. Metyrapone treatment prevented the elevation of corticosterone plasma levels induced by REM sleep deprivation, whereas corticosterone administration to REM sleep-deprived rats resulted in lower corticosterone levels than in non-sleep deprived rats. Nonetheless, both corticosterone and metyrapone administration led to several alterations on sleep homeostasis, including reductions in the amount of non-REM and REM sleep during the recovery period, although corticosterone increased delta activity (1.0–4.0 Hz) during REM sleep deprivation. Metyrapone treatment of REM sleep-deprived rats reduced the number of REM sleep episodes. In conclusion, reduction of corticosterone levels during REM sleep deprivation resulted in impairment of sleep rebound, suggesting that physiological elevation of corticosterone levels resulting from REM sleep deprivation is necessary for plentiful recovery of sleep after this stressful event.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.