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1.
J Neurophysiol ; 129(4): 914-926, 2023 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-36947887

RESUMO

Muscle stiffness is altered following postmastectomy breast reconstruction and breast cancer treatment. The exact mechanisms underlying these alterations are unknown; however, muscle stretch reflexes may play a role. This work examined short- (SLR) and long-latency (LLR) shoulder muscle stretch reflexes in breast cancer survivors. Forty-nine patients who had undergone postmastectomy breast reconstruction, 17 who had undergone chemoradiation, and 18 healthy, age-matched controls were enrolled. Muscle activity was recorded from the clavicular and sternocostal regions of the pectoralis major and anterior, middle, and posterior deltoids during vertical ab/adduction or horizontal flex/extension perturbations while participants maintained minimal torques. SLR and LLR were quantified for each muscle. Our major finding was that following postmastectomy breast reconstruction, SLR and LLR are impaired in the clavicular region of the pectoralis major. Individuals who had chemoradiation had impaired stretch reflexes in the clavicular and sternocostal region of the pectoralis major, anterior, middle, and posterior deltoid. These findings indicate that breast cancer treatments alter the regulation of shoulder muscle stretch reflexes and may be associated with surgical or nonsurgical damage to the pectoral fascia, muscle spindles, and/or sensory Ia afferents.NEW & NOTEWORTHY Shoulder muscle stretch reflexes may be impacted following postmastectomy breast reconstruction and chemoradiation. Here, we examined short- and long-latency shoulder muscle stretch reflexes in two experiments following common breast reconstruction procedures and chemoradiation. We show impairments in pectoralis major stretch reflexes following postmastectomy breast reconstruction and pectoralis major and deltoid muscle stretch reflexes following chemoradiation. These findings indicate that breast cancer treatments alter the regulation of shoulder muscle stretch reflexes.


Assuntos
Neoplasias da Mama , Mamoplastia , Humanos , Feminino , Ombro/fisiologia , Neoplasias da Mama/cirurgia , Mastectomia , Músculo Esquelético/fisiologia , Reflexo de Estiramento/fisiologia
2.
Muscle Nerve ; 62(1): 111-114, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32291768

RESUMO

BACKGROUND: Increment of compound muscle action potential amplitude is a diagnostic hallmark of Lambert-Eaton myasthenic syndrome (LEMS). Making a diagnosis can be challenging, therefore, a proper cutoff for abnormal increment is highly relevant for improved recognition of this rare disease. METHODS: We determined the sensitivity and specificity of 60% and 100% cutoff values in all consecutive patients who underwent increment testing in our hospital from 1999 to 2016. RESULTS: We included 156 patients, 63 with LEMS and 93 without LEMS. Sensitivity of a 60% cutoff for increment testing was 77.8% (95% confidence interval 65.5%-87.3%) and 58.7% (45.6%-71.0%) for 100%. Specificity was 98.9% (94.2%-100%) and 100% (96.1%-100%) using a threshold of 60% and 100%, respectively. CONCLUSIONS: Lowering the cutoff value for abnormal increment to 60% greatly increases sensitivity to diagnose LEMS without an overt loss in specificity.


Assuntos
Eletrodiagnóstico/métodos , Eletrodiagnóstico/normas , Síndrome Miastênica de Lambert-Eaton/diagnóstico , Síndrome Miastênica de Lambert-Eaton/fisiopatologia , Potenciais de Ação/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Debilidade Muscular/diagnóstico , Debilidade Muscular/fisiopatologia , Reflexo de Estiramento/fisiologia , Estudos Retrospectivos , Adulto Jovem
3.
PLoS One ; 11(4): e0153283, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27077743

RESUMO

BACKGROUND: Hereditary spastic paraplegias (HSP) are a composite and genetically heterogeneous group of conditions mainly expressed by the impairment of the central motor system ("pure" forms). The involvement of other components of the central nervous system or of other systems is described in the "complicate" forms. The definition of an investigation protocol capable, by assembling clinical and paraclinical indicators to fully represent the extent of the motor system impairment, would help both the clinical handling of these conditions and contribute to our understanding of their pathogenesis. METHODS: We applied a clinical and paraclinical protocol which included tools exploring motor and non motor functioning, neurophysiology and MRI to a composite cohort of 70 molecularly defined HSP patients aged 3 to 65, to define for each indicator its significance in detailing the presence and the severity of the pathology. RESULTS: Clinically increased deep tendon reflexes and lower limb (LL) weakness are constant findings in all patients. The "complicated" forms are characterized by peripheral motor impairment, cognitive and cerebellar involvement. The Spastic Paraplegia Rating Scale efficiently reflects the severity of functional problems and correlates with disease duration. Neurophysiology consistently documents the impairment of the central motor pathway to the LLs. Nevertheless, the upper extremities and sensory system involvement is a frequent finding. MRI diffusion tensor imaging (DTI) highlighted a significant alteration of FA and MD. Combining the sampling of the various portion of the cortico-spinal tract (CST) DTI consistently discriminated patients from controls. CONCLUSION: We propose a graded clinical and paraclinical protocol for HSP phenotype definition, indicating for each tool the discriminative and descriptive capacity. Our protocol applied to 9 different forms of HSP showed that the functional impairment often extends beyond the CST. The novel DTI approach may add significant elements in disease recognition, staging and mapping.


Assuntos
Extremidade Inferior/fisiopatologia , Reflexo de Estiramento/fisiologia , Paraplegia Espástica Hereditária/fisiopatologia , Tendões/fisiopatologia , Adenosina Trifosfatases/genética , Adolescente , Adulto , Idoso , Análise de Variância , Cerebelo/fisiopatologia , Criança , Pré-Escolar , Cognição/fisiologia , Estudos de Coortes , Feminino , Proteínas de Ligação ao GTP/genética , Humanos , Imageamento por Ressonância Magnética , Masculino , Proteínas de Membrana/genética , Pessoa de Meia-Idade , Mutação , Projetos Piloto , Paraplegia Espástica Hereditária/diagnóstico , Paraplegia Espástica Hereditária/genética , Espastina , Adulto Jovem
4.
Curr Biol ; 25(5): 656-62, 2015 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-25702578

RESUMO

Myoclonic twitches are jerky movements that occur exclusively and abundantly during active (or REM) sleep in mammals, especially in early development [1-4]. In rat pups, limb twitches exhibit a complex spatiotemporal structure that changes across early development [5]. However, it is not known whether this developmental change is influenced by sensory experience, which is a prerequisite to the notion that sensory feedback from twitches not only activates sensorimotor circuits but modifies them [4]. Here, we investigated the contributions of proprioception to twitching in newborn ErbB2 conditional knockout mice that lack muscle spindles and grow up to exhibit dysfunctional proprioception [6-8]. High-speed videography of forelimb twitches unexpectedly revealed a category of reflex-like twitching-comprising an agonist twitch followed immediately by an antagonist twitch-that developed postnatally in wild-types/heterozygotes, but not in knockouts. Contrary to evidence from adults that spinal reflexes are inhibited during twitching [9-11], this finding suggests that twitches trigger the monosynaptic stretch reflex and, by doing so, contribute to its activity-dependent development [12-14]. Next, we assessed developmental changes in the frequency and organization (i.e., entropy) of more-complex, multi-joint patterns of twitching; again, wild-types/heterozygotes exhibited developmental changes in twitch patterning that were not seen in knockouts. Thus, targeted deletion of a peripheral sensor alters the normal development of local and global features of twitching, demonstrating that twitching is shaped by sensory experience. These results also highlight the potential use of twitching as a uniquely informative diagnostic tool for assessing the functional status of spinal and supraspinal circuits.


Assuntos
Animais Recém-Nascidos/fisiologia , Mioclonia/fisiopatologia , Propriocepção/fisiologia , Receptor ErbB-2/metabolismo , Reflexo Anormal/fisiologia , Sono/fisiologia , Fatores Etários , Análise de Variância , Animais , Genótipo , Camundongos , Camundongos Knockout , Fusos Musculares/fisiologia , Músculo Esquelético/fisiologia , Receptor ErbB-2/genética , Reflexo de Estiramento/fisiologia , Gravação em Vídeo
5.
Arch Oral Biol ; 59(12): 1321-7, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25173665

RESUMO

OBJECTIVES: The jaw-stretch reflex (JSR) was studied in both patients and healthy participants in order to investigate the possible long-term impact of orthognathic surgery on the motor function of the masticatory system. DESIGN: JSR was measured in patients before surgery (PC), 1year after surgery (PS) and in healthy controls (HC) (N=31 in each group). JSR was evoked by a standardized stretch device and recorded bilaterally from masseter and anterior temporalis muscles using surface electromyography (EMG). RESULTS: The peak-to-peak amplitude (which was normalized to pre-stimulus EMG activity) of JSRs in PC and PS were significantly smaller than in HC (P<0.001; P<0.001). The onset latency in PS was significantly longer compared with HC (P<0.05). The duration of JSR in PS was significantly longer than in HC and PC (P<0.001; P<0.05). CONCLUSION: Patients with dentofacial deformities are characterized by reduced JSR amplitude. The delayed onset and elongated duration of JSR might be potential indicators of a long-term surgical impact on the motor function of the masticatory system.


Assuntos
Deformidades Dentofaciais/fisiopatologia , Deformidades Dentofaciais/cirurgia , Arcada Osseodentária/fisiopatologia , Músculo Masseter/fisiopatologia , Cirurgia Ortognática , Reflexo de Estiramento/fisiologia , Músculo Temporal/fisiopatologia , Adolescente , Adulto , Estudos de Casos e Controles , Eletromiografia , Feminino , Humanos , Masculino , Medição da Dor , Inquéritos e Questionários
7.
J Oral Maxillofac Surg ; 71(10): 1810.e1-11, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23871317

RESUMO

PURPOSE: Bifocal distraction osteogenesis has been shown to be a reliable method for reconstructing missing bone segments. However, no reports have been published regarding inferior alveolar nerve regeneration during this procedure. We assumed that the nerve could regenerate with the bone regeneration during bifocal distraction, if the nerve had been saved at a mesial site of the transport disc. In the present study, we investigated that possibility in dogs. MATERIALS AND METHODS: Using a bifocal distraction osteogenesis method, we produced a 10-mm mandibular defect, including the nerve defect, and distracted the transport disc at a rate of 1 mm/day in 12 dogs. The nerve was saved at the mesial site of the transport disc. The regenerated nerve was evaluated by a jaw opening reflex examination performed once daily. Histologic examinations with hematoxylin-eosin and immunohistochemical staining with neurofilament and S-100 antibody were also performed on all dogs after death at 3, 6, and 12 months after the first operation. RESULTS: The jaw opening reflex had recovered in all dogs. The average period of recovery was 109.5 ± 24.7 days. On histologic examination, although consecutive nerves were observed in all areas, cellular nerve fascicles were seen, consistent with wallerian degeneration at 3 and 6 months in the nerve connection area on the distal side of the transport disc. CONCLUSIONS: Our results have indicated that inferior alveolar nerve regeneration after bifocal distraction osteogenesis is successful in dogs. Although our research is still at the stage of animal experiments, future application in humans can be considered to be possible.


Assuntos
Mandíbula/cirurgia , Nervo Mandibular/fisiologia , Regeneração Nervosa/fisiologia , Osteogênese por Distração/métodos , Animais , Axônios/patologia , Regeneração Óssea/fisiologia , Cães , Mandíbula/inervação , Mandíbula/fisiologia , Doenças Mandibulares/cirurgia , Nervo Mandibular/patologia , Degeneração Neural/patologia , Fibras Nervosas/patologia , Proteínas de Neurofilamentos/análise , Osteogênese/fisiologia , Osteogênese por Distração/instrumentação , Recuperação de Função Fisiológica/fisiologia , Reflexo de Estiramento/fisiologia , Proteínas S100/análise , Células de Schwann/patologia , Fatores de Tempo
8.
Spinal Cord ; 50(12): 878-81, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22584286

RESUMO

OBJECTIVES: To identify any observations that could aid in the diagnosis of cervical myelopathy in patients suffering from diabetes mellitus (DM). We compared the preoperative neurological findings in patients with cervical myelopathy among non-diabetics, mild diabetics and severe diabetics. STUDY DESIGN: A retrospective comparative study. SETTING: Department of Orthopaedic Surgery, Wakayama Medical University, Japan. METHODS: We retrospectively reviewed 111 patients who had undergone laminoplasty for cervical compressive myelopathy: 56 without DM and 29 with severe diabetes more than 10 years of medication; more than 7.0% HbA1c; diabetic retinopathy; and delayed conduction velocity of peripheral nerves. For preoperative neurological assessment we compared the following among the three groups: the 10 s test whereby the myelopathy in the hand was quantified; sensory disturbance; deep tendon reflexes; Hoffmann's, Trömner's and Babinski's reflexes; and bladder dysfunction. RESULTS: There was no significant difference preoperatively in the 10 s test between the groups. Deep tendon reflexes were significantly decreased in group S. There were no significant differences in sensory disturbance and bladder dysfunction. Although Hoffmann's and Trömner's reflexes significantly disappeared in group S, there was no significant difference in positivity of Babinski's reflex between the groups. CONCLUSIONS: The 10 s test and Babinski's reflex are helpful for the diagnosis of cervical myelopathy in patients suffering from DM.


Assuntos
Vértebras Cervicais , Complicações do Diabetes/diagnóstico , Compressão da Medula Espinal/diagnóstico , Compressão da Medula Espinal/etiologia , Atividades Cotidianas , Adulto , Idoso , Idoso de 80 Anos ou mais , Vértebras Cervicais/cirurgia , Complicações do Diabetes/cirurgia , Feminino , Transtornos Neurológicos da Marcha/etiologia , Transtornos Neurológicos da Marcha/fisiopatologia , Hemoglobinas Glicadas/análise , Humanos , Masculino , Pessoa de Meia-Idade , Exame Neurológico , Procedimentos Ortopédicos , Reflexo de Babinski , Reflexo de Estiramento/fisiologia , Estudos Retrospectivos , Transtornos de Sensação/etiologia , Transtornos de Sensação/fisiopatologia , Compressão da Medula Espinal/cirurgia , Bexiga Urinaria Neurogênica/etiologia , Retenção Urinária/etiologia , Retenção Urinária/fisiopatologia , Caminhada
9.
QJM ; 105(4): 315-20, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22071964

RESUMO

BACKGROUND: Ankle reflex is a simple screening tool frequently used in the detection of peripheral neuropathy. AIM: The purpose of this study is to assess the performance characteristics of ankle reflex in detecting diabetic peripheral neuropathy (DPN) by evaluating the sensitivity, specificity and the predictive ability of the ankle reflex, a component of Neuropathy Disability Score (NDS) with reference to Nerve Conduction Studies (NCS). METHODS: A total of 151 patients with type 2 diabetes were assessed (47 males, 104 females). Grading of neuropathy was done using Neuropathy Symptom Score (NSS), NDS and NCS. Patients were divided into two groups, those with abnormal NCS (Group 1) and those with normal NCS (Group 2). Demographic characteristics, biochemistry, NSS and NDS were assessed between the two groups. Taking NCS as the gold standard, sensitivity, specificity and predictive ability of the ankle reflex were calculated and compared with other tests included in NDS, namely vibration sense, superficial pain and temperature sensation. RESULTS: There were 59 (39.1%) patients in Group 1 and 92 (60.9%) in Group 2. NSS and NDS demonstrated strong positive association with NCS. Taking NCS as the gold standard, ankle reflex yielded the highest sensitivity and specificity (91.5 and 67.4%, respectively), closely followed by that of vibration sense. CONCLUSION: Ankle reflex is a powerful screening tool with high sensitivity and negative predictive value, but a combination of ankle reflex and vibration sense has superior sensitivity and specificity compared with either of them done alone for the detection of DPN in clinical settings.


Assuntos
Articulação do Tornozelo/inervação , Diabetes Mellitus Tipo 2/fisiopatologia , Neuropatias Diabéticas/diagnóstico , Doenças do Sistema Nervoso Periférico/diagnóstico , Reflexo de Estiramento/fisiologia , Idoso , Neuropatias Diabéticas/fisiopatologia , Técnicas de Diagnóstico Neurológico , Métodos Epidemiológicos , Feminino , Humanos , Masculino , Programas de Rastreamento/métodos , Pessoa de Meia-Idade , Condução Nervosa/fisiologia , Doenças do Sistema Nervoso Periférico/fisiopatologia , Reflexo Anormal/fisiologia
10.
J Korean Acad Nurs ; 41(2): 191-6, 2011 Apr.
Artigo em Coreano | MEDLINE | ID: mdl-21551990

RESUMO

PURPOSE: We investigated the effects of group III mechanoreceptors to cardiovascular responses in both pre-menopausal woman and post-menopausal woman during passive ankle dorsiflexion (PAD). METHODS: Twenty healthy volunteers (10 post-menopausal women and 10 pre-menopausal women) were recruited for this study. Stroke volume (SV), heart rate (HR), cardiac output (CO), and total vascular conductances (TVC) were measured continuously throughout the experiment. To stimulate the group III mechanoreceptors, PAD was performed for one minute. RESULTS: The results showed that mean arterial pressure (MAP) mediated by the mechanoreflex activation was significantly increased in both groups. However, this pressor response was significantly higher in post-menopausal women. This reflex significantly increased both SV and CO in pre-menopausal women, while there were no differences in post-menopausal women. There was no difference in HR in either group. The mechanoreflex significantly decreased TVC in post-menopausal woman, while there was no difference in pre-menopausal woman. CONCLUSION: The results indicate that the excessive pressor response mediated by the mechanoreflex occurs due to overactivity of group III mechanorecptors and the mechanism is produced mainly via peripheral vasoconstriction in post-menopausal women.


Assuntos
Estrogênios/metabolismo , Reflexo de Estiramento/fisiologia , Idoso , Pressão Sanguínea , Índice de Massa Corporal , Débito Cardíaco , Feminino , Frequência Cardíaca , Humanos , Mecanorreceptores , Pessoa de Meia-Idade , Pós-Menopausa , Pré-Menopausa , Volume Sistólico
11.
Am J Physiol Regul Integr Comp Physiol ; 300(1): R140-9, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21084678

RESUMO

Mechanisms regulating stretch response in the left ventricle are investigated in detail but not well understood in atrial myocardium. Hypertrophic growth of atrial myocardium contributes to the pathogenesis of atrial fibrillation. In this study, we sought to elucidate mechanisms of stretch-induced activation of key signaling pathways and hypertrophy-associated genes in rat atria. Stretching of isolated atria induced a rapid increase in phosphorylation of p38 MAPK and ERK and induced a p38 MAPK-dependent increase in DNA binding activity of transcription factors Elk-1 and GATA-4. Inhibition of the ERK pathway had no effect on the cardiac transcription factors studied. Stretch-induced increase in atrial contractile function was substantially enhanced by inhibition of p38 MAPK. p38 MAPK also regulated stretch-induced increase in c-fos, ß-myosin heavy chain, B-type natriuretic peptide mRNA levels, and atrial natriuretic peptide secretion in isolated atria. Various autocrine/paracrine factors are known to mediate the stretch response in the left ventricle. Stretching of isolated atria resulted in a robust increase in endothelin-1 (ET-1) mRNA levels, while apelin and adrenomedullin signaling cascades were downregulated. Administration of mixed ET(A/B) receptor antagonist bosentan attenuated the stretch-induced activation of GATA-4 in isolated atria, whereas ANG II receptor type-1 antagonist CV-11974 had no effect. Moreover, analysis of RNA from intact atrial and ventricular myocardium revealed significantly higher mRNA levels of ET(A) receptor and ET converting enzyme-1 in atrial compared with ventricular myocardium. In conclusion, our findings identify the local ET-1 system and p38 MAPK as key regulators of load-induced hypertrophic response in isolated rat atria.


Assuntos
Função Atrial/fisiologia , Endotelina-1/fisiologia , Contração Miocárdica/fisiologia , Reflexo de Estiramento/fisiologia , Proteínas Quinases p38 Ativadas por Mitógeno/fisiologia , Animais , Fator de Transcrição GATA4/fisiologia , Masculino , Modelos Animais , Cadeias Pesadas de Miosina/fisiologia , Peptídeo Natriurético Encefálico/fisiologia , Fosforilação , Proteínas Proto-Oncogênicas c-fos/fisiologia , Ratos , Ratos Sprague-Dawley , Receptores de Endotelina/fisiologia
12.
Am J Physiol Heart Circ Physiol ; 300(2): H527-40, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21076019

RESUMO

Loss of the cardiovagal baroreflex (CVB), thoracic hypovolemia, and hyperpnea contribute to the nonlinear time-dependent hemodynamic instability of vasovagal syncope. We used a nonlinear phase synchronization index (PhSI) to describe the extent of coupling between cardiorespiratory parameters, systolic blood pressure (SBP) or arterial pressure (AP), RR interval (RR), and ventilation, and a directional index (DI) measuring the direction of coupling. We also examined phase differences directly. We hypothesized that AP-RR interval PhSI would be normal during early upright tilt, indicating intact CVB, but would progressively decrease as faint approached and CVB failed. Continuous measurements of AP, RR interval, respiratory plethysomography, and end-tidal CO2 were recorded supine and during 70-degree head-up tilt in 15 control subjects and 15 fainters. Data were evaluated during five distinct times: baseline, early tilt, late tilt, faint, and recovery. During late tilt to faint, fainters exhibited a biphasic change in SBP-RR interval PhSI. Initially in fainters during late tilt, SBP-RR interval PhSI decreased (fainters, from 0.65±0.04 to 0.24±0.03 vs. control subjects, from 0.51±0.03 to 0.48±0.03; P<0.01) but then increased at the time of faint (fainters=0.80±0.03 vs. control subjects=0.42±0.04; P<0.001) coinciding with a change in phase difference from positive to negative. Starting in late tilt and continuing through faint, fainters exhibited increasing phase coupling between respiration and AP PhSI (fainters=0.54±0.06 vs. control subjects=0.27±0.03; P<0.001) and between respiration and RR interval (fainters=0.54±0.05 vs. control subjects=0.37±0.04; P<0.01). DI indicated respiratory driven AP (fainters=0.84±0.04 vs. control subjects=0.39±0.09; P<0.01) and RR interval (fainters=0.73±0.10 vs. control subjects=0.23±0.11; P<0.001) in fainters. The initial drop in the SBP-RR interval PhSI and directional change of phase difference at late tilt indicates loss of cardiovagal baroreflex. The subsequent increase in SBP-RR interval PhSI is due to a respiratory synchronization and drive on both AP and RR interval. Cardiovagal baroreflex is lost before syncope and supplanted by respiratory reflexes, producing hypotension and bradycardia.


Assuntos
Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Frequência Cardíaca/fisiologia , Mecânica Respiratória/fisiologia , Síncope Vasovagal/fisiopatologia , Nervo Vago/fisiopatologia , Adolescente , Adulto , Dióxido de Carbono/sangue , Eletrocardiografia , Feminino , Hemodinâmica/fisiologia , Humanos , Pulmão/fisiologia , Masculino , Dinâmica não Linear , Pletismografia , Reflexo de Estiramento/fisiologia , Teste da Mesa Inclinada , Adulto Jovem
15.
J Physiol ; 588(Pt 21): 4131-43, 2010 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-20807787

RESUMO

Muscle spindle afferent (MSA) neurons can show rapid and sustained firing. Immunostaining for the α3 isoform of the Na(+)/K(+)-ATPase (α3) in some large dorsal root ganglion (DRG) neurons and large intrafusal fibres suggested α3 expression in MSAs (Dobretsov et al. 2003), but not whether α3-immunoreactive DRG neuronal somata were exclusively MSAs. We found that neuronal somata with high α3 immunointensity were neurofilament-rich, suggesting they have A-fibres; we therefore focussed on A-fibre neurons to determine the sensory properties of α3-immunoreactive neurons. We examined α3 immunointensity in 78 dye-injected DRG neurons whose conduction velocities and hindlimb sensory receptive fields were determined in vivo. A dense perimeter or ring of staining in a subpopulation of neurons was clearly overlying the soma membrane and not within satellite cells. Neurons with clear α3 rings (n = 23) were all MSAs (types I and II); all MSAs had darkly stained α3 rings, that tended to be darker in MSA1 than MSA2 units. Of 52 non-MSA A-fibre neurons including nociceptive and cutaneous low-threshold mechanoreceptive (LTM) neurons, 50 had no discernable ring, while 2 (Aα/ß cutaneous LTMs) had weakly stained rings. Three of three C-nociceptors had no rings. MSAs with strong ring immunostaining also showed the strongest cytoplasmic staining. These findings suggest that α3 ring staining is a selective marker for MSAs. The α3 isoform of the Na(+)/K(+)-ATPase has previously been shown to be activated by higher Na(+) levels and to have greater affinity for ATP than the α1 isoform (in all DRG neurons). The high α3 levels in MSAs may enable the greater dynamic firing range in MSAs.


Assuntos
Imuno-Histoquímica/métodos , Fusos Musculares/inervação , Neurônios Aferentes/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Fenômenos Eletrofisiológicos , Feminino , Corantes Fluorescentes , Gânglios Espinais/citologia , Gânglios Espinais/metabolismo , Cobaias , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Neurônios Aferentes/citologia , Ratos , Ratos Wistar , Reflexo de Estiramento/fisiologia , ATPase Trocadora de Sódio-Potássio/química , ATPase Trocadora de Sódio-Potássio/genética
16.
J Hand Surg Am ; 35(7): 1059-66, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20610049

RESUMO

PURPOSE: The presence of wrist proprioceptive reflexes after stimulation of the dorsal scapholunate interosseous ligament has previously been described. Because this ligament is primarily innervated by the posterior interosseous nerve (PIN) we hypothesized altered ligamento-muscular reflex patterns following desensitization of the PIN. METHODS: Eight volunteers (3 women, 5 men; mean age, 26 y; range 21-28 y) participated in the study. In the first study on wrist proprioceptive reflexes (study 1), the scapholunate interosseous ligament was stimulated through a fine-wire electrode with 4 1-ms bipolar pulses at 200 Hz, 30 times consecutively, while EMG activity was recorded from the extensor carpi radialis brevis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris, with the wrist in extension, flexion, radial deviation, and ulnar deviation. After completion of study 1, the PIN was anesthetized in the radial aspect of the fourth extensor compartment using 2-mL lidocaine (10 mg/mL) infiltration anesthesia. Ten minutes after desensitization, the experiment was repeated as in study 1. The average EMG results from the 30 consecutive stimulations were rectified and analyzed using Student's t-test. Statistically significant changes in EMG amplitude were plotted along time lines so that the results of study 1 and 2 could be compared. RESULTS: Dramatic alterations in reflex patterns were observed in wrist flexion, radial deviation, and ulnar deviation following desensitization of the PIN, with an average of 72% reduction in excitatory reactions. In ulnar deviation, the inhibitory reactions of the extensor carpi ulnaris were entirely eliminated. In wrist extension, no differences in the reflex patterns were observed. CONCLUSIONS: Wrist proprioception through the scapholunate ligament in flexion, radial deviation, and ulnar deviation depends on an intact PIN function. The unchanged reflex patterns in wrist extension suggest an alternate proprioceptive pathway for this position. Routine excision of the PIN during wrist surgical procedures should be avoided, as it alters the proprioceptive function of the wrist. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.


Assuntos
Lidocaína/farmacologia , Propriocepção/fisiologia , Reflexo de Estiramento/fisiologia , Articulação do Punho/inervação , Adulto , Eletromiografia/métodos , Feminino , Humanos , Contração Isométrica/efeitos dos fármacos , Contração Isométrica/fisiologia , Ligamentos Articulares/efeitos dos fármacos , Ligamentos Articulares/inervação , Ligamentos Articulares/fisiologia , Masculino , Inibição Neural/efeitos dos fármacos , Vias Neurais/efeitos dos fármacos , Vias Neurais/fisiologia , Propriocepção/efeitos dos fármacos , Nervo Radial/efeitos dos fármacos , Nervo Radial/fisiologia , Amplitude de Movimento Articular/fisiologia , Valores de Referência , Reflexo de Estiramento/efeitos dos fármacos , Estudos de Amostragem , Nervo Ulnar/efeitos dos fármacos , Nervo Ulnar/fisiologia , Articulação do Punho/fisiologia , Adulto Jovem
18.
Neuroscience ; 167(1): 185-98, 2010 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-20149848

RESUMO

Progressive changes in the muscle tone and stretch reflex after spinal cord injury (SCI) provide insight into the time-course development of spasticity. This study quantified the time-course changes of hypertonia for rats following SCI of T8 hemisection. A miniature manual stretching device measured the reactive torque via a pair of pressure sensing balloons; the angular displacement was measured via an optoelectronic device. Various stretching frequencies were tested, specifically 1/3, 1/2, 1, 3/2 and 2 Hz. The reactive torque and angular displacement were used to derive the viscous and elastic components representing the viscosity and stiffness of the rat's ankle joint. The enhanced velocity-dependent properties of spasticity were observed in the SCI hemisection rats (n=9) but not in the controls (n=9). Time-course measurements from pre-surgery to 56 days following SCI showed that the muscle tone of the hemisection rats dropped immediately after spinal shock and then gradually increased to reach a peak around 21 days postinjury (P<0.01). The muscle tone remained at least 75% of the peak value up to the end of an 8 week observation period (P<0.05). The changes of muscle tone can also be verified from the electrophysiological evaluations of electromyography (EMG) (P<0.05). In addition to conventional BBB motor behavior score, our results provided time-course quantification of the biomechanical and electrophysiological properties of muscle tone from the onset of SCI. Such data are useful for investigating progressive recovery of spinal damage in animal model and for future objective assessment of improved treatment for SCI human subjects.


Assuntos
Hipertonia Muscular/fisiopatologia , Espasticidade Muscular/fisiopatologia , Traumatismos da Medula Espinal/fisiopatologia , Animais , Articulação do Tornozelo/fisiopatologia , Fenômenos Biomecânicos , Avaliação da Deficiência , Lateralidade Funcional , Locomoção/fisiologia , Masculino , Tono Muscular/fisiologia , Ratos , Ratos Wistar , Reflexo de Estiramento/fisiologia , Fatores de Tempo
19.
Clinics ; 65(12): 1363-1369, 2010. graf, tab
Artigo em Inglês | LILACS | ID: lil-578578

RESUMO

OBJECTIVES: The aim of the study was to investigate the effect of fetal undernutrition on the passive mechanical properties of skeletal muscle of weaned and young adult rats. INTRODUCTION: A poor nutrition supply during fetal development affects physiological functions of the fetus. From a mechanical point of view, skeletal muscle can be also characterized by its resistance to passive stretch. METHODS: Male Wistar rats were divided into two groups according to their mother's diet during pregnancy: a control group (mothers fed a 17 percent protein diet) and an isocaloric low-protein group (mothers fed a 7.8 percent protein diet). At birth, all mothers received a standardized meal ad libitum. At the age of 25 and 90 days, the soleus muscle and extensor digitorum longus (EDL) muscles were removed in order to test the passive mechanical properties. A first mechanical test consisted of an incremental stepwise extension test using fast velocity stretching (500 mm/s) enabling us to measure, for each extension stepwise, the dynamic stress (σd) and the steady stress (σs). A second test consisted of a slow velocity stretch in order to calculate normalized stiffness and tangent modulus from the stress-strain relationship. RESULTS: The results for the mechanical properties showed an important increase in passive stiffness in both the soleus and EDL muscles in weaned rat. In contrast, no modification was observed in young adult rats. CONCLUSIONS: The increase in passive stiffness in skeletal muscle of weaned rat submitted to intrauterine undernutrition it is most likely due to changes in muscle passive stiffness.


Assuntos
Animais , Feminino , Masculino , Gravidez , Ratos , Elasticidade/fisiologia , Desenvolvimento Fetal/fisiologia , Desnutrição/complicações , Músculo Esquelético/fisiopatologia , Efeitos Tardios da Exposição Pré-Natal/fisiopatologia , Reflexo de Estiramento/fisiologia , Análise de Variância , Animais Recém-Nascidos , Dieta com Restrição de Proteínas/efeitos adversos , Modelos Animais , Contração Muscular/fisiologia , Fenômenos Fisiológicos da Nutrição Pré-Natal/fisiologia , Ratos Wistar , Desmame
20.
J Neurosurg Spine ; 10(5): 452-7, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19442007

RESUMO

OBJECT: Neurogenic bladder dysfunction following spinal cord injury (SCI) is a major medical and social problem for which there is no ideal treatment strategy. In the present study, the authors analyze the effectiveness of neurogenic bladder reinnervation in patients with SCIs by using Achilles tendon reflexes below the paraplegic level. METHODS: Spinal root anastomoses were performed in 12 paraplegic patients with hyperreflexic neurogenic bladder and detrusor external sphincter dyssynergia (DESD) caused by complete suprasacral SCI, in an attempt to reinnervate the bladder. The surgery anastomosed the unilateral proximal end of the S-1 ventral root and the distal end of the S-2 and/or S-3 ventral roots to build the Achilles tendon-to-bladder reflex, while the S-1 dorsal root was kept intact as the trigger for micturition after axonal regeneration. All patients underwent urodynamic evaluation before surgery and at follow-up. RESULTS: The mean follow-up duration was 3 years. Of the 12 patients, 9 (75%) regained satisfactory bladder control within 6 to 12 months after ventral root microanastomosis. In these 9 patients, urodynamic studies revealed a change from detrusor hyperreflexia with DESD and high detrusor pressure to almost normal storage and synergic voiding without DESD. The average bladder capacity increased from 258 +/- 33 ml to 350 +/- 49 ml, residual urine decreased from 214 +/- 36 ml to 45 +/- 11 ml, and urinary infections were not observed. Patients with impaired renal function experienced a full recovery. Three patients failed to show any improvement after the operation. CONCLUSIONS: These results suggest the effectiveness of bladder innervation below the level of SCI to produce urination by Achilles tendon-to-bladder reflex contractions, and might therefore provide a new clinical approach to reconstructing spasmodic bladder urination function.


Assuntos
Tendão do Calcâneo/fisiologia , Reflexo de Estiramento/fisiologia , Traumatismos da Medula Espinal/fisiopatologia , Bexiga Urinaria Neurogênica/cirurgia , Bexiga Urinária/inervação , Micção/fisiologia , Adolescente , Adulto , Anastomose Cirúrgica , Feminino , Seguimentos , Humanos , Masculino , Microcirurgia/métodos , Pessoa de Meia-Idade , Resultado do Tratamento , Urodinâmica , Procedimentos Cirúrgicos Urológicos/métodos
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