Base de dados : MEDLINE
Pesquisa : E05.723.402.201 [Categoria DeCS]
Referências encontradas : 278 [refinar]
Mostrando: 1 .. 10   no formato [Detalhado]

página 1 de 28 ir para página                         

  1 / 278 MEDLINE  
              next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:27732921
[Au] Autor:Silva PE; Babault N; Mazullo JB; de Oliveira TP; Lemos BL; Carvalho VO; Durigan JL
[Ad] Endereço:Physical Therapy Division, University Hospital of Brasília, University of Brasília, Brasília, Federal District, Brazil; Health Sciences and Technologies PhD Program, University of Brasilia, Federal District, Brazil. Electronic address: pauloeugenio.bsb@gmail.com.
[Ti] Título:Safety and feasibility of a neuromuscular electrical stimulation chronaxie-based protocol in critical ill patients: A prospective observational study.
[So] Source:J Crit Care;37:141-148, 2017 Feb.
[Is] ISSN:1557-8615
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:PURPOSE: The aim of this study was to evaluate the safety and feasibility of a neuromuscular electrical stimulation (NMES) protocol based on neuromuscular excitability and applied in numerous muscle groups of critical ill patients. MATERIALS AND METHODS: We performed a prospective observational study using an NMES applied daily and bilaterally into 5 muscle groups in lower limbs for 3 consecutive days. The characteristics of NMES were 90 contractions per muscle, pulse width equal to chronaxie, and a pulse frequency of 100 Hz. We assessed safety with central venous oxygen saturation, serum lactate, and creatine phosphokinase measurements. To evaluate feasibility, we recorded the time spent for the entire NMES protocol and the number of NMES sessions completed. RESULTS: Eleven male patients finished the study. There were no significant changes observed in creatine phosphokinase from baseline up to 96 hours: 470(±270) IU/L and 455(±240) IU/L (P>.99). Central venous oxygen saturation and serum lactate had the same pattern with no significant variations (P=.23 and P=.8, respectively). The time spent during the whole procedure and the number of complete NMES sessions performed were 107±24 minutes and 84 sessions (85%), respectively. CONCLUSIONS: We demonstrated that NMES chronaxie-based protocol is safe and feasible.
[Mh] Termos MeSH primário: Estado Terminal
Terapia por Estimulação Elétrica/métodos
Contração Muscular/fisiologia
Músculo Esquelético/irrigação sanguínea
[Mh] Termos MeSH secundário: APACHE
Adulto
Cronaxia
Cuidados Críticos
Feminino
Seres Humanos
Ácido Láctico/sangue
Masculino
Estudos Prospectivos
Segurança
[Pt] Tipo de publicação:JOURNAL ARTICLE; OBSERVATIONAL STUDY
[Nm] Nome de substância:
33X04XA5AT (Lactic Acid)
[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:161013
[St] Status:MEDLINE


  2 / 278 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:27584138
[Au] Autor:Pinheiro-Dardis CM; Russo TL
[Ad] Endereço:From the Laboratory of Neurological Physiotherapy Research (LaFiN), Department of Physiotherapy (DFisio), Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil.
[Ti] Título:Electrical Stimulation Based on Chronaxie Increases Fibrosis and Modulates TWEAK/Fn14, TGF-ß/Myostatin, and MMP Pathways in Denervated Muscles.
[So] Source:Am J Phys Med Rehabil;96(4):260-267, 2017 Apr.
[Is] ISSN:1537-7385
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:OBJECTIVE: The aim of this work was to investigate the effects of electrical stimulation (ES) of denervated muscles of rat in neuromuscular performance, muscle atrophy, and fibrosis formation. DESIGN: Wistar rats were divided into normal (N), 7- or 15-day denervation (D7d and D15d), D7d or D15d plus ES (DES7d and DES15d, respectively). Sciatic nerves were crushed causing muscle denervation. Two hundred muscle contractions were electrically induced daily by surface electrodes, considering muscle chronaxie. Sciatic functional index was used to determine neuromuscular performance during walking. The muscle fiber cross-sectional area and percentage of connective tissue were assessed by light microscopy. Molecular markers of extracellular matrix production and remodeling were evaluated. Metalloproteinase (MMP) activity was assessed by zymography, and TWEAK, Fn14, myostatin, and transforming growth factor (TGF)-ß gene expressions were determined by real-time PCR. RESULTS: Electrical stimulation impaired natural recovery of walking at 15 days. In addition, ES induced fibrosis and accentuated muscle atrophy in denervated muscles. Although ES reduced the accumulation of TWEAK and myostatin expressions, it up-regulated Fn14 and TGF-ß in a time-dependent manner. Electrical stimulation also increased the activity of MMP-2 compared to the other groups (P < 0.05). CONCLUSIONS: Electrical stimulation applied to denervated muscles induced muscle fibrosis and atrophy, as well as loss of performance. The TWEAK/Fn14 system, TGF-beta/myostatin pathway, and MMP activity seem to be involved in these deleterious changes.
[Mh] Termos MeSH primário: Cronaxia
Estimulação Elétrica
Denervação Muscular
[Mh] Termos MeSH secundário: Animais
Proteínas Reguladoras de Apoptose/metabolismo
Citocina TWEAK
Regulação para Baixo
Fibrose/etiologia
Metaloproteinase 2 da Matriz/metabolismo
Proteínas de Membrana/metabolismo
Modelos Animais
Músculo Esquelético/metabolismo
Músculo Esquelético/patologia
Atrofia Muscular/etiologia
Miostatina/metabolismo
Ratos Wistar
Receptores do Fator de Necrose Tumoral/metabolismo
Receptor de TWEAK
Fator de Crescimento Transformador beta/metabolismo
Fatores de Necrose Tumoral/metabolismo
Regulação para Cima
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Apoptosis Regulatory Proteins); 0 (Cytokine TWEAK); 0 (Gdf8 protein, rat); 0 (Membrane Proteins); 0 (Myostatin); 0 (Receptors, Tumor Necrosis Factor); 0 (TWEAK Receptor); 0 (Tnfrsf12a protein, rat); 0 (Tnfsf12 protein, rat); 0 (Transforming Growth Factor beta); 0 (Tumor Necrosis Factors); EC 3.4.24.24 (Matrix Metalloproteinase 2)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:171116
[Lr] Data última revisão:
171116
[Sb] Subgrupo de revista:AIM; IM
[Da] Data de entrada para processamento:160902
[St] Status:MEDLINE
[do] DOI:10.1097/PHM.0000000000000601


  3 / 278 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo
[PMID]:26186201
[Au] Autor:Stern S; Agudelo-Toro A; Rotem A; Moses E; Neef A
[Ad] Endereço:Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel.
[Ti] Título:Chronaxie Measurements in Patterned Neuronal Cultures from Rat Hippocampus.
[So] Source:PLoS One;10(7):e0132577, 2015.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Excitation of neurons by an externally induced electric field is a long standing question that has recently attracted attention due to its relevance in novel clinical intervention systems for the brain. Here we use patterned quasi one-dimensional neuronal cultures from rat hippocampus, exploiting the alignment of axons along the linear patterned culture to separate the contribution of dendrites to the excitation of the neuron from that of axons. Network disconnection by channel blockers, along with rotation of the electric field direction, allows the derivation of strength-duration (SD) curves that characterize the statistical ensemble of a population of cells. SD curves with the electric field aligned either parallel or perpendicular to the axons yield the chronaxie and rheobase of axons and dendrites respectively, and these differ considerably. Dendritic chronaxie is measured to be about 1 ms, while that of axons is on the order of 0.1 ms. Axons are thus more excitable at short time scales, but at longer time scales dendrites are more easily excited. We complement these studies with experiments on fully connected cultures. An explanation for the chronaxie of dendrites is found in the numerical simulations of passive, realistically structured dendritic trees under external stimulation. The much shorter chronaxie of axons is not captured in the passive model and may be related to active processes. The lower rheobase of dendrites at longer durations can improve brain stimulation protocols, since in the brain dendrites are less specifically oriented than axonal bundles, and the requirement for precise directional stimulation may be circumvented by using longer duration fields.
[Mh] Termos MeSH primário: Potenciais de Ação/fisiologia
Axônios/metabolismo
Cálcio/metabolismo
Cronaxia/fisiologia
Dendritos/metabolismo
[Mh] Termos MeSH secundário: 2-Amino-5-fosfonovalerato/farmacologia
4-Aminopiridina/farmacologia
6-Ciano-7-nitroquinoxalina-2,3-diona/farmacologia
Potenciais de Ação/efeitos dos fármacos
Animais
Axônios/efeitos dos fármacos
Axônios/ultraestrutura
Bicuculina/análogos & derivados
Bicuculina/farmacologia
Cronaxia/efeitos dos fármacos
Dendritos/efeitos dos fármacos
Dendritos/ultraestrutura
Embrião de Mamíferos
Antagonistas de Aminoácidos Excitatórios/farmacologia
Antagonistas GABAérgicos/farmacologia
Hipocampo/efeitos dos fármacos
Hipocampo/metabolismo
Hipocampo/ultraestrutura
Bloqueadores dos Canais de Potássio/farmacologia
Cultura Primária de Células
Ratos
Ratos Wistar
Receptores de AMPA/antagonistas & inibidores
Receptores de AMPA/metabolismo
Receptores de GABA/metabolismo
Receptores de N-Metil-D-Aspartato/antagonistas & inibidores
Receptores de N-Metil-D-Aspartato/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Excitatory Amino Acid Antagonists); 0 (GABA Antagonists); 0 (Potassium Channel Blockers); 0 (Receptors, AMPA); 0 (Receptors, GABA); 0 (Receptors, N-Methyl-D-Aspartate); 6OTE87SCCW (6-Cyano-7-nitroquinoxaline-2,3-dione); 76726-92-6 (2-Amino-5-phosphonovalerate); BH3B64OKL9 (4-Aminopyridine); I3UNE1K4AF (bicuculline methochloride); SY7Q814VUP (Calcium); Y37615DVKC (Bicuculline)
[Em] Mês de entrada:1604
[Cu] Atualização por classe:170414
[Lr] Data última revisão:
170414
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150718
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0132577


  4 / 278 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:25714722
[Au] Autor:da Silva-Alves KS; Ferreira-da-Silva FW; Coelho-de-Souza AN; Albuquerque AA; do Vale OC; Leal-Cardoso JH
[Ad] Endereço:Laboratory of Electrophysiology, Superior Institute of Biomedical Sciences, State University of Ceará, Fortaleza, Ceará, Brazil.
[Ti] Título:Essential oil of Croton zehntneri and its main constituent anethole block excitability of rat peripheral nerve.
[So] Source:Planta Med;81(4):292-7, 2015 Mar.
[Is] ISSN:1439-0221
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:Croton zehntneri is an aromatic plant native to Northeast Brazil and employed by local people to treat various diseases. The leaves of this plant have a rich content of essential oil. The essential oil of C. zehntneri samples, with anethole as the major constituent and anethole itself, have been reported to have several pharmacological activities such as antispasmodic, cardiovascular, and gastroprotective effects and inducing the blockade of neuromuscular transmission and antinociception. Since several works have demonstrated that essential oils and their constituents block cell excitability and in view of the multiple effects of C. zehntneri essential oil and anethole on biological tissues, we undertook this investigation aiming to characterize and compare the effects of this essential oil and its major constituent on nerve excitability. Sciatic nerves of Wistar rats were used. They were mounted in a moist chamber, and evoked compound action potentials were recorded. Nerves were exposed in vitro to the essential oil of C. zehntneri and anethole (0.1-1 mg/mL) up to 180 min, and alterations in excitability (rheobase and chronaxie) and conductibility (peak-to-peak amplitude and conduction velocity) parameters of the compound action potentials were evaluated. The essential oil of C. zehntneri and anethole blocked, in a concentration-dependent manner with similar pharmacological potencies (IC50: 0.32 ± 0.07 and 0.22 ± 0.11 mg/mL, respectively), rat sciatic nerve compound action potentials. Strength-duration curves for both agents were shifted upward and to the right compared to the control curve, and the rheobase and chronaxie were increased following essential oil and anethole exposure. The time courses of the essential oil of C. zehntneri and anethole effects on peak-to-peak amplitude of compound action potentials followed an exponential decay and reached a steady state. The essential oil of C. zehntneri and anethole caused a similar reduction in conduction velocities of the compound action potential waves investigated. In conclusion, we demonstrated here that the essential oil of C. zehntneri blocks neuronal excitability and that this effect, which can be predominantly attributable to its major constituent, anethole, is important since these agents have several pharmacological effects likely related to the alteration of excitability. This finding is relevant due to the use of essential oils in aromatherapy and the low acute toxicity of this agent, which exhibits other effects of potential therapeutic usefulness.
[Mh] Termos MeSH primário: Potenciais de Ação/efeitos dos fármacos
Anisóis/farmacologia
Croton/química
Óleos Voláteis/farmacologia
Extratos Vegetais/farmacologia
Nervo Isquiático/efeitos dos fármacos
[Mh] Termos MeSH secundário: Animais
Brasil
Cronaxia/efeitos dos fármacos
Feminino
Masculino
Folhas de Planta
Ratos Wistar
Nervo Isquiático/fisiologia
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Anisoles); 0 (Oils, Volatile); 0 (Plant Extracts); Q3JEK5DO4K (anethole)
[Em] Mês de entrada:1512
[Cu] Atualização por classe:150312
[Lr] Data última revisão:
150312
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:150226
[St] Status:MEDLINE
[do] DOI:10.1055/s-0034-1396309


  5 / 278 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo SciELO Brasil
[PMID]:23969978
[Au] Autor:Alves JS; Leal-Cardoso JH; Santos-Júnior FF; Carlos PS; Silva RC; Lucci CM; Báo SN; Ceccatto VM; Barbosa R
[Ad] Endereço:Universidade Estadual do Ceará, Instituto Superior de Ciências Biomédicas, FortalezaCE, Brasil.
[Ti] Título:Limb immobilization alters functional electrophysiological parameters of sciatic nerve.
[So] Source:Braz J Med Biol Res;46(8):715-21, 2013 Aug.
[Is] ISSN:1414-431X
[Cp] País de publicação:Brazil
[La] Idioma:eng
[Ab] Resumo:Immobilization, used in clinical practice to treat traumatologic problems, causes changes in muscle, but it is not known whether changes also occur in nerves. We investigated the effects of immobilization on excitability and compound action potential (CAP) and the ultrastructure of the rat sciatic nerve. Fourteen days after immobilization of the right leg of adult male Wistar rats (n=34), animals were killed and the right sciatic nerve was dissected and mounted in a moist chamber. Nerves were stimulated at a baseline frequency of 0.2 Hz and tested for 2 min at 20, 50, and 100 Hz. Immobilization altered nerve excitability. Rheobase and chronaxy changed from 3.13 ± 0.05 V and 52.31 ± 1.95 µs (control group, n=13) to 2.84 ± 0.06 V and 59.71 ± 2.79 µs (immobilized group, n=15), respectively. Immobilization altered the amplitude of CAP waves and decreased the conduction velocity of the first CAP wave (from 93.63 ± 7.49 to 79.14 ± 5.59 m/s) but not of the second wave. Transmission electron microscopy showed fragmentation of the myelin sheath of the sciatic nerve of immobilized limbs and degeneration of the axon. In conclusion, we demonstrated that long-lasting leg immobilization can induce alterations in nerve function.
[Mh] Termos MeSH primário: Potenciais de Ação/fisiologia
Membro Posterior/inervação
Imobilização/efeitos adversos
Degeneração Neural/fisiopatologia
Nervo Isquiático/fisiopatologia
[Mh] Termos MeSH secundário: Animais
Cronaxia/fisiologia
Masculino
Microscopia Eletrônica de Transmissão
Bainha de Mielina/fisiologia
Ratos Wistar
Fatores de Tempo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Em] Mês de entrada:1410
[Cu] Atualização por classe:161018
[Lr] Data última revisão:
161018
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:130824
[St] Status:MEDLINE


  6 / 278 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
PubMed Central Texto completo
Texto completo
[PMID]:22516015
[Au] Autor:Rattay F; Paredes LP; Leao RN
[Ad] Endereço:Institute for Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria. frank. rattay@tuwien. ac. at
[Ti] Título:Strength-duration relationship for intra- versus extracellular stimulation with microelectrodes.
[So] Source:Neuroscience;214:1-13, 2012 Jul 12.
[Is] ISSN:1873-7544
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Chronaxie, a historically introduced excitability time parameter for electrical stimulation, has been assumed to be closely related to the time constant of the cell membrane. Therefore, it is perplexing that significantly larger chronaxies have been found for intracellular than for extracellular stimulation. Using compartmental model analysis, this controversy is explained on the basis that extracellular stimulation also generates hyperpolarized regions of the cell membrane hindering a steady excitation as seen in the intracellular case. The largest inside/outside chronaxie ratio for microelectrode stimulation is found in close vicinity of the cell. In the case of monophasic cathodic stimulation, the length of the primarily excited zone which is situated between the hyperpolarized regions increases with electrode-cell distance. For distant electrodes this results in an excitation process comparable to the temporal behavior of intracellular stimulation. Chronaxie also varies along the neural axis, being small for electrode positions at the nodes of Ranvier and axon initial segment and larger at the soma and dendrites. As spike initiation site can change for short and long pulses, in some cases strength-duration curves have a bimodal shape, and thus, they deviate from a classical monotonic curve as described by the formulas of Lapicque or Weiss.
[Mh] Termos MeSH primário: Cronaxia/fisiologia
Líquido Extracelular/fisiologia
Líquido Intracelular/fisiologia
Potenciais da Membrana/fisiologia
Microeletrodos
[Mh] Termos MeSH secundário: Animais
Estimulação Elétrica/métodos
Hipocampo/fisiologia
Camundongos
Camundongos Endogâmicos C57BL
Fatores de Tempo
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Em] Mês de entrada:1304
[Cu] Atualização por classe:170220
[Lr] Data última revisão:
170220
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:120421
[St] Status:MEDLINE
[do] DOI:10.1016/j.neuroscience.2012.04.004


  7 / 278 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:21561804
[Au] Autor:Murray JE; Jankelowitz SK
[Ad] Endereço:Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia.
[Ti] Título:A comparison of the excitability of motor axons innervating the APB and ADM muscles.
[So] Source:Clin Neurophysiol;122(11):2290-3, 2011 Nov.
[Is] ISSN:1872-8952
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:OBJECTIVE: Threshold tracking allows the non-invasive assessment of axonal excitability. This study aimed to determine whether axonal excitability of the motor axons of the median nerve (to APB) and ulnar nerve (to ADM) to the small muscles of the hands is sufficiently similar to be interchangeable; confirm the feasibility and reproducibility of ulnar studies and obtain control data for a young population for this site of stimulation. METHODS: Twenty normal subjects between the ages of 23-43 were studied using the TRONDF protocol of QTRACS, (©Prof Hugh Bostock, London). The median and ulnar nerves were stimulated at the wrist and the compound muscle action potentials were recorded from abductor pollicis brevis and abductor digiti minimi, respectively. Repeat studies were performed in four subjects to confirm reproducibility of the recordings. RESULTS: Stimulus intensity was greater and strength duration time constant was longer for the median nerve. Threshold electrotonus showed there was a greater change in threshold in the hyperpolarising direction for the median nerve compared with the ulnar nerve. There was however little difference in the recovery cycle and current threshold relationship. CONCLUSIONS: Although recovery cycles and the current thresholds are similar for APB and ADM, there are definite differences in stimulus threshold, SDTC and threshold electrotonus which question the interchangeability of studies for these two sites. SIGNIFICANCE: This study demonstrates reproducibility of motor axonal excitability studies of the ulnar nerve at the wrist, provides young control data for this site of stimulation and suggests that although certain excitability indices are similar for the median nerve to APB and ulnar nerve to ADM there are definite differences making the interchangeability of the data questionable.
[Mh] Termos MeSH primário: Axônios/fisiologia
Mãos/inervação
Neurônios Motores/fisiologia
Músculo Esquelético/inervação
[Mh] Termos MeSH secundário: Adulto
Cronaxia/fisiologia
Estimulação Elétrica
Estudos de Viabilidade
Feminino
Mãos/fisiologia
Seres Humanos
Masculino
Nervo Mediano/fisiologia
Músculo Esquelético/fisiologia
Tempo de Reação/fisiologia
Reprodutibilidade dos Testes
Nervo Ulnar/fisiologia
Adulto Jovem
[Pt] Tipo de publicação:COMPARATIVE STUDY; JOURNAL ARTICLE
[Em] Mês de entrada:1111
[Cu] Atualização por classe:110929
[Lr] Data última revisão:
110929
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:110513
[St] Status:MEDLINE
[do] DOI:10.1016/j.clinph.2011.04.007


  8 / 278 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:20132498
[Au] Autor:Irnich W
[Ad] Endereço:Justus-Liebig-University, Faculty of Medicine, Giessen, Germany. werner@irni.ch
[Ti] Título:The terms "chronaxie" and "rheobase" are 100 years old.
[So] Source:Pacing Clin Electrophysiol;33(4):491-6, 2010 Apr.
[Is] ISSN:1540-8159
[Cp] País de publicação:United States
[La] Idioma:eng
[Mh] Termos MeSH primário: Cronaxia
Eletrofisiologia/história
[Mh] Termos MeSH secundário: França
História do Século XIX
História do Século XX
Seres Humanos
Masculino
[Pt] Tipo de publicação:BIOGRAPHY; HISTORICAL ARTICLE; JOURNAL ARTICLE; PORTRAITS
[Ps] Nome de pessoa como assunto:Lapicque LE
[Em] Mês de entrada:1008
[Cu] Atualização por classe:100813
[Lr] Data última revisão:
100813
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:100206
[St] Status:MEDLINE
[do] DOI:10.1111/j.1540-8159.2009.02666.x


  9 / 278 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:19759411
[Au] Autor:Recoskie BJ; Scholl TJ; Chronik BA
[Ad] Endereço:Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada.
[Ti] Título:The discrepancy between human peripheral nerve chronaxie times as measured using magnetic and electric field stimuli: the relevance to MRI gradient coil safety.
[So] Source:Phys Med Biol;54(19):5965-79, 2009 Oct 07.
[Is] ISSN:1361-6560
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Peripheral nerve stimulation (PNS) resulting from electric fields induced from the rapidly changing magnetic fields of gradient coils is a concern in MRI. Nerves exposed to either electric fields or changing magnetic fields would be expected to display consistent threshold characteristics, motivating the direct application of electric field exposure criteria from the literature to guide the development of gradient magnetic field exposure criteria for MRI. The consistency of electric and magnetic field exposures was tested by comparing chronaxie times for electric and magnetic PNS curves for 22 healthy human subjects. Electric and magnetic stimulation thresholds were measured for exposure of the forearm using both surface electrodes and a figure-eight magnetic coil, respectively. The average chronaxie times for the electric and magnetic field conditions were 109 +/- 11 micros and 651 +/- 53 micros (+/-SE), respectively. We do not propose that these results call into question the basic mechanism, namely that rapidly switched gradient magnetic fields induce electric fields in human tissues, resulting in PNS. However, this result does motivate us to suggest that special care must be taken when using electric field exposure data from the literature to set gradient coil PNS safety standards in MRI.
[Mh] Termos MeSH primário: Cronaxia
Eletricidade
Imagem por Ressonância Magnética/efeitos adversos
Magnetismo
Nervos Periféricos/fisiologia
[Mh] Termos MeSH secundário: Segurança de Equipamentos
Feminino
Seres Humanos
Imagem por Ressonância Magnética/métodos
Masculino
Fatores de Tempo
Adulto Jovem
[Pt] Tipo de publicação:CLINICAL TRIAL; JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL; RESEARCH SUPPORT, NON-U.S. GOV'T
[Em] Mês de entrada:1001
[Cu] Atualização por classe:100209
[Lr] Data última revisão:
100209
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:090918
[St] Status:MEDLINE
[do] DOI:10.1088/0031-9155/54/19/020


  10 / 278 MEDLINE  
              first record previous record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:19175850
[Au] Autor:Lawo T; Deneke T; Schrader J; Danilovic D; Wenzel B; Buddensiek M; Muegge A
[Ad] Endereço:Medical Clinic II (Cardiology), BG University Hospital Bergmannsheil, Bochum, Germany. thomas.lawo@rub.de
[Ti] Título:A comparison of chronaxies for ventricular fibrillation induction, defibrillation, and cardiac stimulation: unexpected findings and their implications.
[So] Source:J Cardiovasc Electrophysiol;20(3):307-14, 2009 Mar.
[Is] ISSN:1540-8167
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:INTRODUCTION: A low-energy (
[Mh] Termos MeSH primário: Cronaxia
Cardioversão Elétrica/efeitos adversos
Cardioversão Elétrica/métodos
Sistema de Condução Cardíaco/fisiopatologia
Fibrilação Ventricular/prevenção & controle
Fibrilação Ventricular/fisiopatologia
[Mh] Termos MeSH secundário: Animais
Achados Incidentais
Modelos Cardiovasculares
Suínos
Fibrilação Ventricular/etiologia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Em] Mês de entrada:0906
[Cu] Atualização por classe:090305
[Lr] Data última revisão:
090305
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:090130
[St] Status:MEDLINE
[do] DOI:10.1111/j.1540-8167.2008.01319.x



página 1 de 28 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