Base de dados : MEDLINE
Pesquisa : G01.060.350 [Categoria DeCS]
Referências encontradas : 6348 [refinar]
Mostrando: 1 .. 10   no formato [Detalhado]

página 1 de 635 ir para página                         

  1 / 6348 MEDLINE  
              next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:27775722
[Au] Autor:Laurens J; Kim B; Dickman JD; Angelaki DE
[Ad] Endereço:Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA.
[Ti] Título:Gravity orientation tuning in macaque anterior thalamus.
[So] Source:Nat Neurosci;19(12):1566-1568, 2016 12.
[Is] ISSN:1546-1726
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Gravity may provide a ubiquitous allocentric reference to the brain's spatial orientation circuits. Here we describe neurons in the macaque anterior thalamus tuned to pitch and roll orientation relative to gravity, independently of visual landmarks. We show that individual cells exhibit two-dimensional tuning curves, with peak firing rates at a preferred vertical orientation. These results identify a thalamic pathway for gravity cues to influence perception, action and spatial cognition.
[Mh] Termos MeSH primário: Potenciais de Ação/fisiologia
Núcleos Anteriores do Tálamo/fisiologia
Cognição/fisiologia
Gravitação
Neurônios/fisiologia
Orientação/fisiologia
Percepção Espacial/fisiologia
[Mh] Termos MeSH secundário: Animais
Macaca
Estimulação Luminosa/métodos
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL
[Em] Mês de entrada:1709
[Cu] Atualização por classe:180223
[Lr] Data última revisão:
180223
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161108
[St] Status:MEDLINE
[do] DOI:10.1038/nn.4423


  2 / 6348 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:29342202
[Au] Autor:Mayorova TD; Smith CL; Hammar K; Winters CA; Pivovarova NB; Aronova MA; Leapman RD; Reese TS
[Ad] Endereço:Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America.
[Ti] Título:Cells containing aragonite crystals mediate responses to gravity in Trichoplax adhaerens (Placozoa), an animal lacking neurons and synapses.
[So] Source:PLoS One;13(1):e0190905, 2018.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Trichoplax adhaerens has only six cell types. The function as well as the structure of crystal cells, the least numerous cell type, presented an enigma. Crystal cells are arrayed around the perimeter of the animal and each contains a birefringent crystal. Crystal cells resemble lithocytes in other animals so we looked for evidence they are gravity sensors. Confocal microscopy showed that their cup-shaped nuclei are oriented toward the edge of the animal, and that the crystal shifts downward under the influence of gravity. Some animals spontaneously lack crystal cells and these animals behaved differently upon being tilted vertically than animals with a typical number of crystal cells. EM revealed crystal cell contacts with fiber cells and epithelial cells but these contacts lacked features of synapses. EM spectroscopic analyses showed that crystals consist of the aragonite form of calcium carbonate. We thus provide behavioral evidence that Trichoplax are able to sense gravity, and that crystal cells are likely to be their gravity receptors. Moreover, because placozoans are thought to have evolved during Ediacaran or Cryogenian eras associated with aragonite seas, and their crystals are made of aragonite, they may have acquired gravity sensors during this early era.
[Mh] Termos MeSH primário: Carbonato de Cálcio/metabolismo
Gravitação
Placozoa/metabolismo
[Mh] Termos MeSH secundário: Animais
Carbonato de Cálcio/química
Cristalização
Corantes Fluorescentes
Microscopia Eletrônica de Varredura
Microscopia Eletrônica de Transmissão
Neurônios
Placozoa/citologia
Análise Espectral/métodos
Sinapses
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., INTRAMURAL
[Nm] Nome de substância:
0 (Fluorescent Dyes); H0G9379FGK (Calcium Carbonate)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180221
[Lr] Data última revisão:
180221
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:180118
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0190905


  3 / 6348 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:27776994
[Au] Autor:Kokhan VS; Matveeva MI; Bazyan AS; Kudrin VS; Mukhametov A; Shtemberg AS
[Ad] Endereço:Laboratory of Extreme Physiology, Institute of Medico-Biological Problems RAS, Moscow, Russia. Electronic address: viktor_kohan@hotmail.com.
[Ti] Título:Combined effects of antiorthostatic suspension and ionizing radiation on the behaviour and neurotransmitters changes in different brain structures of rats.
[So] Source:Behav Brain Res;320:473-483, 2017 03 01.
[Is] ISSN:1872-7549
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:Space flight factors (SFF) significantly affect the operating activity of astronauts during deep space missions. In contrast to an orbital flight, leaving the Earth's magnetic field is fraught with the dangers of exposure to ionizing radiation and more specifically, the high-energy nuclei component of galactic cosmic rays. Microgravity, just another critical non-radiation factor, significantly affects the normal functioning of the CNS. Some morphological structures of the brain, such as the prefrontal cortex and the hippocampus, that are rich in monoaminergic and acetylcholinergic neurones, are the most sensitive to the effects of ionizing radiation and non-radiation spaceflight factors (SFF). In this work we have studied the combined effects of microgravity (in antiorthostatic suspension model, AS) and irradiation (γ-ray and protons in spread-out Bragg peak) on the behaviour, cognitive abilities, and metabolism of monoamines and acetylcholine in the key structures of the rat's brain. Irradiation (as independently as combined with AS) resulted in the decrease of thigmotaxis in rats. Learning problems, caused by the malfunctioning of the working memory but not the spatial memory, were observed in response to AS as well as to the SFF in combination. Analysis of monoamines metabolism showed that the serotoninergic system was the most affected by the SFF. Concentration of acetylcholine in the hippocampus significantly increased in the groups of irradiated rats, and in the groups which were exposed to the SFF in combination, compared to the rats exposed only to AS.
[Mh] Termos MeSH primário: Comportamento Animal/efeitos da radiação
Encéfalo/metabolismo
Encéfalo/efeitos da radiação
Gravitação
Neurotransmissores/metabolismo
Radiação Ionizante
[Mh] Termos MeSH secundário: Animais
Aprendizagem da Esquiva/fisiologia
Aprendizagem da Esquiva/efeitos da radiação
Comportamento Animal/fisiologia
Comportamento Exploratório/efeitos da radiação
Masculino
Aprendizagem em Labirinto/fisiologia
Aprendizagem em Labirinto/efeitos da radiação
Ratos
Ratos Wistar
Voo Espacial
Fatores de Tempo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Neurotransmitter Agents)
[Em] Mês de entrada:1712
[Cu] Atualização por classe:180104
[Lr] Data última revisão:
180104
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161108
[St] Status:MEDLINE


  4 / 6348 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:27776740
[Au] Autor:Mills C; Sanchez A; Scurr J
[Ad] Endereço:Department of Sport and Exercise Sciences, Spinnaker Building, University of Portsmouth, PO1 2ER, United Kingdom. Electronic address: chris.mills@port.ac.uk.
[Ti] Título:Estimating the gravity induced three dimensional deformation of the breast.
[So] Source:J Biomech;49(16):4134-4137, 2016 12 08.
[Is] ISSN:1873-2380
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:As human breast tissue is continuously deformed by gravity, it is difficult to identify the non-loaded neutral breast position from which to take measurements. To estimate the neutral nipple position, this study proposed a simple novel method to counteract the three dimensional effect of gravity on the breast using the buoyant forces from water and soybean oil (ρ = 994kgm ; ρ = 909kgm ). Fourteen female participants with breast sizes ranging from 30 to 34in. under band and B to E cup size took part in this study. Each participant had their static gravity-loaded nipple position measured and their neutral nipple position estimated (as the midpoint between the nipple position during water and soybean oil immersion). Participants were asked to sit in each fluid and fully submerge their torso and breasts. The mean gravity-induced nipple displacements from the neutral nipple position were 15.3mm in the posterior direction, 7.4mm in the lateral direction, and 25.7mm in the inferior direction. Gravity had a significant (p < 0.05, r > 0.82) measurable effect on the static nipple position, particularly in the inferior and posterior directions. Furthermore the density difference between water and soybean oil produced a significant difference (p < 0.05, r = 0.72) in superior-inferior nipple position (5.6mm). These findings suggest that neglect of gravity-induced breast deformations may lead to errors when assessing breast position and its relationship to possible breast pain, and that water alone may not be sufficient to estimate the neutral nipple position.
[Mh] Termos MeSH primário: Mama/fisiologia
[Mh] Termos MeSH secundário: Adulto
Mama/anatomia & histologia
Feminino
Gravitação
Seres Humanos
Mamilos/anatomia & histologia
Mamilos/fisiologia
Adulto Jovem
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Em] Mês de entrada:1710
[Cu] Atualização por classe:180104
[Lr] Data última revisão:
180104
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161026
[St] Status:MEDLINE


  5 / 6348 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:29065112
[Au] Autor:Liu H; Zong Q; Lv H; Jin J
[Ad] Endereço:College of Water Conservancy and Architectural Engineering, Shihezi University, Shihezi, China.
[Ti] Título:Analytical equation for outflow along the flow in a perforated fluid distribution pipe.
[So] Source:PLoS One;12(10):e0185842, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Perforated fluid distribution pipes have been widely used in agriculture, water supply and drainage, ventilation, the chemical industry, and other sectors. The momentum equation for variable mass flow with a variable exchange coefficient and variable friction coefficient was developed by using the momentum conservation method under the condition of a certain slope. The change laws of the variable momentum exchange coefficient and the variable resistance coefficient along the flow were analyzed, and the function of the momentum exchange coefficient was given. According to the velocity distribution of the power function, the momentum equation of variable mass flow was solved for different Reynolds numbers. The analytical solution contains components of pressure, gravity, friction and momentum and reflects the influence of various factors on the pressure distribution along the perforated pipe. The calculated results of the analytical solution were compared with the experimental values of the study by Jin et al. 1984 and Wang et al. 2001 with the mean errors 8.2%, 3.8% and 2.7%, and showed that the analytical solution of the variable mass momentum equation was qualitatively and quantitatively consistent with the experimental results.
[Mh] Termos MeSH primário: Fricção
Gravitação
Abastecimento de Água
Água
[Mh] Termos MeSH secundário: Pressão
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
059QF0KO0R (Water)
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171113
[Lr] Data última revisão:
171113
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171025
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0185842


  6 / 6348 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28983570
[Au] Autor:Niehof N; Tramper JJ; Doeller CF; Medendorp WP
[Ad] Endereço:Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, The Netherlands.
[Ti] Título:Updating of visual orientation in a gravity-based reference frame.
[So] Source:J Vis;17(12):4, 2017 Oct 01.
[Is] ISSN:1534-7362
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The brain can use multiple reference frames to code line orientation, including head-, object-, and gravity-centered references. If these frames change orientation, their representations must be updated to keep register with actual line orientation. We tested this internal updating during head rotation in roll, exploiting the rod-and-frame effect: The illusory tilt of a vertical line surrounded by a tilted visual frame. If line orientation is stored relative to gravity, these distortions should also affect the updating process. Alternatively, if coding is head- or frame-centered, updating errors should be related to the changes in their orientation. Ten subjects were instructed to memorize the orientation of a briefly flashed line, surrounded by a tilted visual frame, then rotate their head, and subsequently judge the orientation of a second line relative to the memorized first while the frame was upright. Results showed that updating errors were mostly related to the amount of subjective distortion of gravity at both the initial and final head orientation, rather than to the amount of intervening head rotation. In some subjects, a smaller part of the updating error was also related to the change of visual frame orientation. We conclude that the brain relies primarily on a gravity-based reference to remember line orientation during head roll.
[Mh] Termos MeSH primário: Gravitação
Rememoração Mental/fisiologia
Orientação Espacial/fisiologia
Orientação/fisiologia
Percepção Espacial/fisiologia
[Mh] Termos MeSH secundário: Adulto
Feminino
Seres Humanos
Masculino
Propriocepção/fisiologia
Desempenho Psicomotor/fisiologia
Adulto Jovem
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171018
[Lr] Data última revisão:
171018
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171007
[St] Status:MEDLINE
[do] DOI:10.1167/17.12.4


  7 / 6348 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28880282
[Au] Autor:Hossenfelder S; Marletto C; Vedral V
[Ad] Endereço:Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany.
[Ti] Título:Quantum gravity: Quantum effects in the gravitational field.
[So] Source:Nature;549(7670):31, 2017 09 06.
[Is] ISSN:1476-4687
[Cp] País de publicação:England
[La] Idioma:eng
[Mh] Termos MeSH primário: Gravitação
[Mh] Termos MeSH secundário: Seres Humanos
[Pt] Tipo de publicação:JOURNAL ARTICLE; COMMENT
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171113
[Lr] Data última revisão:
171113
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170908
[St] Status:MEDLINE
[do] DOI:10.1038/549031a


  8 / 6348 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28772091
[Au] Autor:Linakis MW; Job KM; Liu X; Collingwood SC; Pangburn HA; Ott DK; Sherwin CMT
[Ad] Endereço:a Division of Clinical Pharmacology, Department of Pediatrics , University of Utah , Salt Lake City , UT , USA.
[Ti] Título:Riding (High) into the danger zone: a review of potential differences in chemical exposures in fighter pilots resulting from high altitude and G-forces.
[So] Source:Expert Opin Drug Metab Toxicol;13(9):925-934, 2017 Sep.
[Is] ISSN:1744-7607
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:INTRODUCTION: When in flight, pilots of high performance aircraft experience conditions unique to their profession. Training flights, performed as often as several times a week, can expose these pilots to altitudes in excess of 15 km (~50,000 ft, with a cabin pressurized to an altitude of ~20,000 ft), and the maneuvers performed in flight can exacerbate the G-forces felt by the pilot. While the pilots specifically train to withstand these extreme conditions, the physiologic stress could very likely lead to differences in the disposition of chemicals in the body, and consequently, dangerously high exposures. Unfortunately, very little is known about how the conditions experienced by fighter pilots affects chemical disposition. Areas covered: The purpose of this review is to present information about the effects of high altitude, G-forces, and other conditions experienced by fighter pilots on chemical disposition. Using this information, the expected changes in chemical exposure will be discussed, using isopropyl alcohol as an example. Expert opinion: There is a severe lack of information concerning the effects of the fighter pilot environment on the pharmacokinetics and pharmacodynamics of chemicals. Given the possibility of exposure prior to or during flight, it is important that these potential effects be investigated further.
[Mh] Termos MeSH primário: Altitude
Doenças Profissionais/fisiopatologia
Pilotos
[Mh] Termos MeSH secundário: 2-Propanol/envenenamento
Aeronaves
Animais
Gravitação
Seres Humanos
Exposição Ocupacional/efeitos adversos
Estresse Fisiológico/fisiologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
ND2M416302 (2-Propanol)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170922
[Lr] Data última revisão:
170922
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170804
[St] Status:MEDLINE
[do] DOI:10.1080/17425255.2017.1360867


  9 / 6348 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28724444
[Au] Autor:Takeda K; Mani H; Hasegawa N; Sato Y; Tanaka S; Maejima H; Asaka T
[Ad] Endereço:Graduate School of Health Sciences, Hokkaido University, N12-W5, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan.
[Ti] Título:Adaptation effects in static postural control by providing simultaneous visual feedback of center of pressure and center of gravity.
[So] Source:J Physiol Anthropol;36(1):31, 2017 Jul 19.
[Is] ISSN:1880-6805
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:BACKGROUND: The benefit of visual feedback of the center of pressure (COP) on quiet standing is still debatable. This study aimed to investigate the adaptation effects of visual feedback training using both the COP and center of gravity (COG) during quiet standing. METHODS: Thirty-four healthy young adults were divided into three groups randomly (COP + COG, COP, and control groups). A force plate was used to calculate the coordinates of the COP in the anteroposterior (COP ) and mediolateral (COP ) directions. A motion analysis system was used to calculate the coordinates of the center of mass (COM) in both directions (COM and COM ). The coordinates of the COG in the AP direction (COG ) were obtained from the force plate signals. Augmented visual feedback was presented on a screen in the form of fluctuation circles in the vertical direction that moved upward as the COP and/or COG moved forward and vice versa. The COP + COG group received the real-time COP and COG feedback simultaneously, whereas the COP group received the real-time COP feedback only. The control group received no visual feedback. In the training session, the COP + COG group was required to maintain an even distance between the COP and COG and reduce the COG fluctuation, whereas the COP group was required to reduce the COP fluctuation while standing on a foam pad. In test sessions, participants were instructed to keep their standing posture as quiet as possible on the foam pad before (pre-session) and after (post-session) the training sessions. RESULTS: In the post-session, the velocity and root mean square of COM in the COP + COG group were lower than those in the control group. In addition, the absolute value of the sum of the COP - COM distances in the COP + COG group was lower than that in the COP group. Furthermore, positive correlations were found between the COM velocity and COP - COM parameters. CONCLUSIONS: The results suggest that the novel visual feedback training that incorporates the COP -COG interaction reduces postural sway better than the training using the COP alone during quiet standing. That is, even COP fluctuation around the COG would be effective in reducing the COM velocity.
[Mh] Termos MeSH primário: Adaptação Fisiológica/fisiologia
Retroalimentação Sensorial/fisiologia
Equilíbrio Postural/fisiologia
Postura/fisiologia
[Mh] Termos MeSH secundário: Adulto
Feminino
Gravitação
Seres Humanos
Masculino
Análise e Desempenho de Tarefas
Adulto Jovem
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170828
[Lr] Data última revisão:
170828
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170721
[St] Status:MEDLINE
[do] DOI:10.1186/s40101-017-0147-5


  10 / 6348 MEDLINE  
              first record previous record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28720183
[Au] Autor:Kim S; Cho T; Lee Y; Koo H; Choi B; Kim D
[Ti] Título:G-LOC Warning Algorithms Based on EMG Features of the Gastrocnemius Muscle.
[So] Source:Aerosp Med Hum Perform;88(8):737-742, 2017 Aug 01.
[Is] ISSN:2375-6314
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:BACKGROUND: G-induced loss of consciousness (G-LOC) is mainly caused by failure to sustain an oxygenated blood supply to the pilot's brain because of the sudden acceleration in the direction of the +Gz axis, and is considered a critical safety issue. The purpose of this study was to develop G-LOC warning algorithms based on monitoring electromyograms (EMG) of the gastrocnemius muscle on the calf. METHODS: EMG data was retrieved from a total of 67 pilots and pilot trainees of the Korean Air Force during high-G training on a human centrifugal simulator. Seven EMG features were obtained from root mean square (RMS), integrated absolute value (IAV), and mean absolute value (MAV) for muscle contraction, slope sign changes (SSC), waveform length (WL), zero crossing (ZC), and median frequency (MF) for muscle contraction and fatigue. RESULTS: Out of seven EMG features, IAV and WL showed a rapid decay before G-LOC. Based on these findings, this study developed two algorithms which can detect G-LOC during flight and provide warning signals to the pilots. The probability of G-LOC occurrence was detected through monitoring the decay trend for representing muscle endurance and climb rate of the IAV and WL value during sudden acceleration above 6 G, representing muscle power. The sensitivity of the algorithms using IAV and WL features was 100% and the specificity was 66.7%. DISCUSSION: This study suggests that a G-LOC detecting and warning system may be a customized, real-time countermeasure by improving the accuracy of detecting G-LOC.Kim S, Cho T, Lee Y, Koo H, Choi B, Kim D. G-LOC warning algorithms based on EMG features of the gastrocnemius muscle. Aerosp Med Hum Perform. 2017; 88(8):737-742.
[Mh] Termos MeSH primário: Aceleração/efeitos adversos
Algoritmos
Gravitação
Hipergravidade/efeitos adversos
Militares
Músculo Esquelético/fisiopatologia
Pilotos
Inconsciência/fisiopatologia
[Mh] Termos MeSH secundário: Adulto
Medicina Aeroespacial
Eletromiografia
Seres Humanos
Treinamento por Simulação
Inconsciência/etiologia
Adulto Jovem
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170926
[Lr] Data última revisão:
170926
[Sb] Subgrupo de revista:IM; S
[Da] Data de entrada para processamento:170720
[St] Status:MEDLINE
[do] DOI:10.3357/AMHP.4781.2017



página 1 de 635 ir para página                         
   


Refinar a pesquisa
  Base de dados : MEDLINE Formulário avançado   

    Pesquisar no campo  
1  
2
3
 
           



Search engine: iAH v2.6 powered by WWWISIS

BIREME/OPAS/OMS - Centro Latino-Americano e do Caribe de Informação em Ciências da Saúde